Novel adhesion promoting agents for bonding dielectric material to metal layers

Field of the Invention

The present invention relates to methods for firmly bonding plastics material to layers of a metal, a metal oxide or a semi-conductor by applying novel adhesion promoting agents comprising nanometer-sized particles. The present invention further relates to the resulting bonded pack of a layer of a metal, a metal oxide or a semi-conductor and plastics material. The present invention further relates to a method of forming metal structures on a circuit carrier, using the novel adhesion promoting agents.

Background of the Invention

Many highly varied processes of chemically or physically treating the surface of a metal substrate, such as copper, to improve the bonding of the metal to a polymeric material, such as epoxy or polyimide, are used in industries such as printed circuit board (PCB) or integrated circuit substrate (IC substrate) fabrication. In manufacturing printed circuit boards, various steps are carried out in which metal surfaces, e.g. copper surfaces, must be firmly bonded to a plastics material. In some cases, the required adhesion of the formed bonds must be ensured over a long period. In other cases, a firm bond only has to exist for a short period, e.g. when the plastics material only remains on the metal surfaces during manufacture of the printed circuit board. For example, the firm bond of dry film resists (for structuring conductor lines on printed circuit boards) to the metal surfaces only has to exist while manufacturing the printed circuit board. After the conductor line structures are formed, the resists can be removed.

The easiest way to increase the adhesion is to etch and hence roughen the metal surfaces before forming the bond. When the metal surfaces are made of copper, micro- etching solutions are used, such as sulfuric acid solutions of hydrogen peroxide or sodium peroxodisulfate.

Another procedure is described in U.S. Pat. No. 3,645, 772. A pre-treatment solution is used for copper surfaces that e.g. contains a tetrazole.

Long-term stability is especially necessary when laminating multilayer printed circuit boards. Other treatments for the copper surfaces are required in this case.

When manufacturing multilayer boards, several inner layers of copper are laminated to insulating artificial resin layers (so-called prepregs: epoxide resin films reinforced with fiberglass nets). The inner bonds of the laminate must hold throughout the entire life of the printed circuit board. The copper layers (preferably the conductor line structures) on the inner layers must be surface-treated. Various procedures have been developed to solve this problem.

A known procedure for surface-treating copper layers before lamination is to form an oxide layer on the copper surfaces. In this process, known as the brown or black oxide process, very aggressive reaction conditions are used to form the oxide. A disadvantage of this procedure is that the oxide layer used for enhancing adhesion to the artificial resin layer is not very resistant to acid and especially to hydrochloric treatment solutions. They are hence attacked in subsequent processes for plating the through- holes in the boards. The adhesive bond is eliminated, and delamination occurs at the attacked sites, for example next to a hole in printed circuit boards creating defects known as pink ring and wedge void.

Another option for promoting adhesion is to treat copper surfaces with an aqueous or alcoholic solution of an azole compound. Such a procedure is e.g. presented in WO 96/19097 A1 and U.S. Pat. No. 4,917,758. The copper surfaces are treated with a solution that contains i.a. hydrogen peroxide and an azole compound. The hydrogen peroxide etches the copper surface to produce micro-rough surfaces.

Methods of preparing a metal surface, e.g. a copper clad printed circuit board material, for subsequent coating the surface thereof with a plastics material, e.g. a resist, are known in the art. At various stages in the process of manufacturing printed circuit boards, resists are coated to the copper surface of the printed circuit board material and must excellently adhere to the copper base. For example, in creating copper structures, i.e. lines, as well as bonding and soldering pads, a photo imageable resist is used to define these structures. Furthermore, after these copper structures have been created, a solder mask is applied to the structures in those regions which shall not be soldered. In both cases, the resist is applied to the copper surface and must well adhere thereto both during the imaging process (exposing and developing) and during any subsequent process steps, like copper plating (in the course of copper structure generation) and soldering.

For this reason, pre-treatment of the metal surfaces is at all events to be performed in order to prepare e.g. a copper surface for a good resist reception and hence adherence thereon. Etching solutions are used for this purpose, such as for example solutions containing an oxidant for copper, like hydrogen peroxide, sodium peroxodisulfate or sodium caroate. Etching has generally been considered indispensable because etching is used to roughen the copper surface. This is because roughening has been considered requisite to achieve good adherence of the resist to the copper surface.

For example EP 0 890 660 A1 discloses a micro-etching agent for copper or copper alloys. This agent also contains hydrogen peroxide, sulfuric acid and a tetrazole compound. This solution is used to roughen the copper surface of a printed circuit board by micro-etching and imparting deep, biting ruggedness in the copper surface of a depth of 1 to 5 μηι.

The aforementioned etching solutions, however, are not suitable to be used in recent most sophisticated processes in which finest lines and other structures on the printed circuit boards are generated, like 5 μηι lines and 5 μηι spaces. Using the above conventional micro-etchants, copper will be removed to a depth of at least 1 or 2 μηι. Therefore, there will be the risk of significant under etching or of removing the copper structures due to the microetching step.

In addition to including nitrogen containing organic heterocycles such as imidazoles, triazoles or thiazoles into the resist material, to attain good adherence of a resist to copper surfaces, K.H.Dietz in: Dry Film Photoresist Processing Technology, Electro- chemical Publications Ltd., 2001 , reports on using antitarnishing agents. Such agents may be strong or mild, the strong ones being benzotriazole and the derivatives thereof and the mild ones being hydroxycarboxylic acids such as citric acid. It has yet been ascertained that benzotriazole is not effective as non-etching adhesion promoter because it can only react with the metal surface and not with the photo imageable resist.

Objective of the present Invention

It is therefore the objective of the present invention to provide an adhesion promoter and a method that can create a firm bond between surfaces of a metal, a metal oxide or a semi-conductor and plastics material surfaces. The process should be simple, easy to use, and inexpensive. It is also important that treatment with the adhesion promoter produces a material bond that is not problematic (no pink ring and wedge voids) in the subsequent PCB manufacturing processes, e.g. plating through-holes in board materials. The adhesion promoter and the method utilizing the adhesion promoter should therefore be suitable for manufacturing printed circuit boards.

It is a particular objective of the present invention to provide an adhesion promoter and a method to achieve good permanent adherence of an insulating artificial resin layer to a layer of a metal, a metal oxide or a semi-conductor.

It is a further particular objective of the present invention to provide an adhesion promoter and a method to achieve good temporary adherence of a resist coating, more specifically a photo imageable resist coating, to a layer of a metal, a metal oxide or a semi-conductor.

Another object of the present invention is to provide a method of forming metal structures on a circuit carrier, more specifically a printed circuit board.

Summary of the Invention

These objects are solved by treating a surface of a metal, a metal oxide or a semi- conductor with a solution containing nanometer-sized particles prior to bonding the surface of a metal, a metal oxide or a semi-conductor to a plastics materials surface. The nanometer-sized particles have at least one attachment group bearing a functional chemical group suitable for binding to the surface of a metal, a metal oxide or a semiconductor. Thus, a layer of the nanometer-sized particles is formed on at least a portion of the surface of a metal, a metal oxide or a semi-conductor.

The at least one attachment group has the general Formula (I)

- B - L - FG (I), wherein B is a binding group, L is a linking group and FG is the functional chemical group.

The binding group B represents

1 . -Si(R R ² )-, wherein R and R ² independently of each other represent alkoxy groups having from 1 to 12 carbon atoms, alkyl groups having from 1 to 12 carbon atoms, halogen atoms and a bond to oxygen atoms originating from the nanometer-sized particle and/or further attachment groups; or

2. -CH ₂ -R ³ -, -CO-NH-, -CO-0-, unsubstituted or substituted aryl, wherein R ³ represents -CHOH-CH ₂ -0- -CHOH-CH ₂ -; a linear, unsubstituted or substituted hydrocarbon group having from 1 to 5 carbon atoms.

The linking group L represents a linear, unsubstituted or substituted hydrocarbon group having from 1 to 20 carbon atoms; a cyclic, unsubstituted or substituted hydrocarbon group having from 3 to 8 carbon atoms; the linear or cyclic hydrocarbon group interrupted by one or more oxygen atoms and/or nitrogen atoms; the linear or cyclic hydrocarbon group having one or more double and/or triple bonds; unsubstituted or substituted aryl or heteroaryl, phosphonates and bipyridyl.

The functional chemical group FG represents an amino, carbonyl, carboxyl, ester, epoxy, hydroxyl, acrylic, methacrylic, anhydride, acid halide, halogen, allyl, vinyl, styrene, aryl, acetylene, azide, ureido group; 5 to 6 membered heterocyclic hydrocar- bon groups containing from 1 to 3 nitrogen atoms; isonicotinamidyl, bi-pyridyl, nitrile, isonitrile, mercapto, sulfide, sulfonic acid, sulfinic acid, thiosulfonic acid, and thiocya- nate.

The nanometer-sized particles attached to the surface of a metal, a metal oxide or a semi-conductor render the surface susceptible to the subsequently bonded plastics material and increase the adhesion between the surface of a metal, a metal oxide or a semi-conductor and the plastics material thereby providing a firm bond between the surface of a metal, a metal oxide or a semi-conductor and the plastics materials surface.

The attachment group bearing a functional chemical group suitable for binding to the surface of a metal, a metal oxide or a semi-conductor can be any chemical entity suitable to bind chemically or physically to the surface of a metal, a metal oxide or a semiconductor. A chemical bond between the attachment group and the surface of a metal, a metal oxide or a semi-conductor is preferred since the bond strength is higher.

Brief Description of the Figures

Figure 1 describes the manufacturing scheme of nanometer-sized silica particles and the functionalization of the nanometer-sized silica particles by an attachment group. In this drawing in a first step a tetraalkyl silicate is used in order to prepare the nanometer-sized silica particles according to the Stober process. In the second step the nanometer-sized silica particles are functionalized using a trial- koxysilane compound having a 3-FG-propyl group. FG represents the functional chemical group. The trialkoxysilane part of the silane compound contains the binding group B which binds to oxygen groups originating from the nanometer- sized oxide particle. The linking group L is e.g. a propyl group and the functional chemical group FG may be an amino group. L-FG is introduced by reacting the binding group B with the nanometer-sized silica particle.

Figure 2 shows the particle size distribution determined by the Dynamic Light Scattering (DLS) method for synthesized and functionalized nano-sized silica particles. Figure 3 shows FTIR-ATR spectra of non functionalized silica nanoparticles (Si Colloid) and silica particles functionalized with 3-aminopropyl triethoxysilane (NH2 Modified Si Colloid).

Figure 4 shows 1 H-NMR spectra of non functionalized silica nanoparticles (Figure 4A:

Blank silica nanoparticles) and silica particles functionalized with 3-aminopropyl triethoxysilane (Figure 4B: amine functionalized silica nanoparticles).

Figure 5 shows the adhesion strength of the photo resist Hitachi RY 5319 bonded to a copper panel of type A) treated with inventive functionalized nanometer-sized silica particles or a conventional adhesion enhancer.

Figure 6 shows the adhesion strength of the photo resist Hitachi RY 3525 bonded to a copper panel of type A) treated with inventive functionalized silica particles or a conventional adhesion enhancer.

Figure 7 shows the adhesion strength of the photo resist DuPont FX 925 bonded to a copper panel of type A) treated with inventive functionalized silica particles or a conventional adhesion enhancer.

Figure 8 shows the adhesion strength of the photo resist Hitachi RY 3525 bonded to a copper panel of type B) treated with inventive functionalized silica particles or a conventional adhesion enhancer.

Figure 9 shows the adhesion strength of the photo resist DuPont FX 925 bonded to a copper panel of type B) treated with inventive functionalized silica particles or a conventional adhesion enhancer.

Detailed Description of the Invention

The manufacture of nanometer-sized silica particles can be performed according to methods known in the art. The particles can also be purchased commercially, e.g. from Sigma-Aldrich. Also, the binding of the at least one attachment group to nanometer- sized silica particles is known in the art. The binding of the at least one attachment group to nanometer-sized particles is also called functionalization of the particles.

A suitable method to functionalize nanometer-sized silica particles is disclosed in the Examples section of the description. Such method is also suitable to functionalize nanometer-sized particles comprising reactive oxygen groups on their outer surface. Such method is particularly suitable to functionalize nanometer-sized oxide particles of alumina, titania, zirconia, tin oxide and zinc oxide.

The manufacture of the nanometer-sized silica particles can be performed e.g. by the process described by Stober et al. (Stober et al., Journal of Colloid and Interface Science 26, p. 62-69, 1968) and as described by patent application PCT/EP 2012/074433 which is referred to be incorporated into the description of the present application.

The reaction is believed to consist of a hydrolysis step and a condensation step as shown in Figure 1 . During the hydrolysis step the alkoxy groups of the tetraalkyl silicate are hydrolysed to give the corresponding silanol. During the condensation step the hydroxy groups of different silanol molecules condensate and thus build up a silica structure.

The nanometer-sized oxide particles of alumina, titania, zirconia, tin oxide and zinc oxide of a preferred embodiment of the present invention can be manufactured by similar procedures. For example Park et al. present a method for the production of nanometer-sized alumina particles from AI(OC ₃ H ₇ ) ₃ (Park et al., Materials Research Bulletin 40, p. 1506-1512, 2005). Zinc (II) oxide can be produced from metallic zinc or zinc ores by vaporisation in the presence of oxygen, or from zinc carbonates or zinc hydroxides by calcination. Zirconia can be fabricated from zirconium silicate by calcination. In addition Peng et al. show the formation of nanometer-sized titania particles starting with Ti(S0 ₄ ) ₂ (Peng et al., Journal of Physical Chemistry B 109, p. 4947-4952, 2005) and Taib & Sorrel present the synthesis of tin (IV) oxide particles from tin oxalate (Taib and Sorrel, J. Aust. Ceram. Soc. 43[1 ], p. 56-61 , 2007).

The nanometer-sized oxide particles of silica, alumina, titania, zirconia, tin oxide and zinc oxide of a preferred embodiment of the present invention can also be purchased, for example from American Elements. Characterization of nanometer-sized particles can be performed by dynamic light scattering (DLS). This method for determination of particle size distribution is known in the art. Determination of size of the silica particles of the present invention is described in the Example Section.

The nanometer-sized particles of the present invention may comprise only one material or may comprise more than one material. The material the nanometer-sized particles comprise is selected from an inorganic oxide, an organic polymer and a metal. Preferably, the material is selected from an inorganic oxide and a metal. More preferably the material is an inorganic oxide.

The metal the nanometer-sized particles comprise is selected from one or more of Ag, Au and Cu.

The inorganic oxide the nanometer-sized particles comprise is selected from one or more of silica, alumina, titania, zirconia, tin oxide, zinc oxide, silica gel, silicon oxide- coated Ti0 ₂ , Sb-Sn0 ₂ , Fe ₂ 0 ₃ , magnetite, IndiumTinOxide (ITO), antimony-doped tin oxide (ATO), indium oxide, antimony oxide, fluorine-doped tin oxide, phosphorous- doped tin oxide, zinc antimonite and indium doped zinc oxide.

The organic polymer the nanometer-sized particles comprise is selected from thermoplastic, elastomeric or crosslinked polymers. Examples of thermoplastic, elastomeric or crosslinked polymers are polymers of mono- and diolefins, e.g. polyethylene, polypropylene, polybutadiene; polystyrene, polyacrylate, polymethacrylate, halogen containing polymers, e.g. polyvinylchloride, poly-vinylfluoride, polyvinylidene fluoride; polypyrrole, polyvinyl alcohol, polyvinyl acetate, polyalkylene glycols, polyethylene oxide, polyure- thanes, polyamides, e.g. polyamide 4, polyamide 6; polyimides, polyesters, e.g. polyethylene terephthalate, polybutylene terephthalate; polycarbonates, polysulfones, poly- ethersulfones, epoxy resins, natural polymers, e.g. cellulose, cellulose acetates, cellulose ethers, gelatin, natural rubber; as well as mixtures, copolymers, block copolymers and graft polymers thereof.

In one preferred embodiment the nanometer-sized particles comprise only one material. In a more preferred embodiment the one material is the inorganic oxide defined above. Thus, in the more preferred embodiment the nanometer-sized particles are nanometer-sized oxide particles. In the even more preferred embodiment the nanometer- sized oxide particles are selected from one or more of silica, alumina, titania, zirconia, tin oxide and zinc oxide particles. In the most preferred embodiment the nanometer- sized oxide particles are silica particles.

In a further preferred embodiment the nanometer-sized particles comprise more than one material which means the nanometer-sized particles comprise a mixture of the materials defined above.

In a further preferred embodiment the nanometer-sized particles comprise more than one material which means the nanometer-sized particles comprise an inner core of one material, which is covered by an outer shell of another material. The outer shell comprises one or more layers of another material. The outer shell has an outermost layer also called an outer surface. The one material the core comprises is selected from the inorganic oxide, the organic polymer and the metal defined above. The another material the shell comprises is selected from the inorganic oxide, the organic polymer and the metal defined above. Within this preferred embodiment the one material the core comprises and the another material the shell comprises differ from each other. More preferred nanometer-sized particles comprising an inner core and an outer shell comprise for core / shell materials: polystyrene / polypyrrole; polystyrene / silica; zirconia / silica; gold / polypyrrole.

In an even more preferred embodiment the another material the outer surface of the shell comprises is the inorganic oxide. In the most preferred embodiment the inorganic oxide of the outer surface of the shell is selected from one or more of silica, alumina, titania, zirconia, tin oxide and zinc oxide. In the further most preferred embodiment the inorganic oxide of the outer surface of the shell is silica.

In a further more preferred embodiment the nanometer-sized particles have an outer surface which comprises the inorganic oxide. These nanometer-sized particles are called nanometer-sized oxide particles. The nanometer-sized oxide particles of this more preferred embodiment comprise only one material selected from the inorganic oxide. Alternatively the nanometer-sized oxide particles of this more preferred embod- iment comprise a mixture of the inorganic oxides. Alternatively the nanometer-sized oxide particles comprise an inner core and an outer shell wherein the outer surface of the outer shell comprises the inorganic oxide. The core comprises the material selected from the inorganic oxide, the organic polymer and the metal. The inorganic oxide of the outer surface is as defined above. In the most preferred embodiment the inorganic oxide of the outer surface is selected from one or more of silica, alumina, titania, zirconia, tin oxide and zinc oxide. In the further most preferred embodiment the inorganic oxide of the outer surface is silica.

In a further preferred embodiment the nanometer-sized particles comprise reactive oxygen groups on their outer surface. If the outer surface of the nanometer-sized particles comprises the inorganic oxide, the reactive oxygen groups may be -OH, -OOH, -0-, -00-. If the outer surface of the nanometer-sized particles comprises the organic polymer, the reactive oxygen groups may be -OH, -OOH, -0-, -00-, -CHO, -CO-, -COOH, -C00-, -C00-, -OCO- and -CON-.

Nanoparticles having a core-shell-structure are commercially available; for example particles with a core of zirconia and tin oxide and a shell of silica are available from Nissan Chemical Industry, Ltd. (High refractive index sol).

The nanometer-sized particles of the present invention have a mean diameter in a range of from 0.5 nm to 500 nm, preferably from 1 nm to 200 nm, more preferably from 10 to 100 nm and most preferably from 2 nm to 50 nm. The expression "mean diameter" is defined here as the d ₅₀ value of the particle size distribution obtained by dynamic laser scattering measurement (number median of particle size distribution). The d ₅₀ value of the particle size distribution means that 50 % of the particles have a diameter below the given d ₅₀ value. This method is equally applicable for all types of nano-sized particles of the present invention.

The particles of the present invention have at least one attachment group bearing a functional chemical group suitable for binding to a surface of a metal, a metal oxide or a semi-conductor.

The at least one attachment group has the general Formula (I) - B - L - FG (I), wherein B is a binding group, L is a linking group and FG is a functional chemical group.

The binding group B represents

1 . -Si(R R ² )-, wherein R and R ² independently of each other represent alkoxy groups having from 1 to 12 carbon atoms, alkyl groups having from 1 to 12 carbon atoms, halogen atoms, and a bond to oxygen atoms originating from the nanometer-sized particle and/or further attachment groups; or

2. -CH ₂ R ³ -, -CO-NH-, -CO-0-, unsubstituted or substituted aryl, wherein R ³ represents -CHOH-CH ₂ -0- -CHOH-CH ₂ -; a linear, unsubstituted or substituted hydrocarbon group having from 1 to 5 carbon atoms.

The linking group L represents a linear, unsubstituted or substituted hydrocarbon group having from 1 to 20 carbon atoms; a cyclic, unsubstituted or substituted hydrocarbon group having from 3 to 8 carbon atoms; the linear or cyclic hydrocarbon group interrupted by one or more oxygen atoms and/or nitrogen atoms; the linear or cyclic hydrocarbon group having one or more double and/or triple bonds; unsubstituted or substituted aryl or heteroaryl, phosphonates, and bipyridyl.

The functional chemical group FG represents an amino, carbonyl, carboxyl, ester, epoxy, hydroxyl, acrylic, methacrylic, anhydride, acid halide, halogen, allyl, vinyl, styrene, aryl, acetylene, azide, ureido group; 5 to 6 membered heterocyclic hydrocarbon groups containing from 1 to 3 nitrogen atoms; isonicotinamidyl, bi-pyridyl, nitrile, isonitrile, mercapto, sulfide, sulfonic acid, sulfinic acid, thiosulfonic acid, and thiocya- nate.

In a preferred embodiment the functional chemical group FG is selected from amino, ureido and mercapto groups.

In more preferred embodiments in which the plastics material is a prepreg the functional chemical group FG is selected from amino, ureido and mercapto groups. In a more preferred embodiment in which the plastics material is a solder resist the preferred functional chemical group FG is selected from amino, ureido, mercapto, sulfide, sulfonic acid, sulfinic acid, thiosulfonic acid, and thiocyanate groups.

In a more preferred embodiment in which the plastics material is a patterning resist the preferred functional chemical group FG is selected from mercapto, sulfide, sulfonic acid, sulfinic acid, thiosulfonic acid, and thiocyanate groups.

The attachment group bearing a functional chemical group suitable for binding to a metal surface is attached to the outer surface of the nanometer-sized particles or to the outer surface and the interior structure of the nanometer-sized particles. Preferably the attachment group bearing a functional chemical group suitable for binding to the surface of a metal, a metal oxide or a semi-conductor is attached to the outer surface of the nanometer-sized particles.

The nanometer-sized particles attached to the surface of a metal, a metal oxide or a semi-conductor render the surface susceptible to the subsequently bonded plastics material and increase the adhesion between the metal and the plastics material thereby providing a firm bond between the metal and the plastics materials surface.

The attachment group bearing a functional chemical group suitable for binding to the surface of a metal, a metal oxide or a semi-conductor can be any chemical entity suitable to bind chemically or physically to the substrate surface. The attachment group bearing a functional chemical group is preferably one or more of the above mentioned attachment groups.

For the purposes of disclosure the following definitions apply:

"alkoxy" means an alkyl group (R ₄ ) singulary bonded to an oxygen atom, such like: R4-O-. Preferred alkoxy groups are selected from -0-CH ₂ -CH ₃ , -0-(CH ₂ ) ₂ -CH ₃ , -0-(CH ₂ ) ₃ -CH ₃ , -0-CH-(CH ₃ ) ₂ , -0-(CH ₂ ) ₃ -CH ₃ , and -0-(CH ₂ ) ₄ -CH ₃ .

"alkyl" (R ₄ ) means any saturated monovalent radical hydrocarbon chain having general chemical Formula C _n H _2n+1 , wherein n is an integer from 1 to 12, preferably an integer from 1 to 5, like methyl, ethyl, n-propyl, i-propyl, n-butyl, n-pentyl, and the like, most preferably methyl, ethyl or n-propyl. The alkyl groups may be unsubstituted or substituted and/or may be branched or unbranched. "branched" means that at least one hydrogen atom is displaced by an alkyl group.

"halogen" means chlorine, bromine, iodine, and fluorine atom.

"hydrocarbon group" means any saturated or unsaturated divalent radical hydrocarbon chain. The divalent saturated hydrocarbon chain, when being unsubstituted, has general chemical Formula C _n H ₂ n , wherein n is an integer from 1 to 20, preferably from 2 to 15 and more preferably from 2 to 5, such like methylen (-CH ₂ -), ethylen (-CH ₂ -CH ₂ -), n- propylene (-CH ₂ -CH ₂ -CH ₂ -), n-butylene (-CH ₂ -CH ₂ -CH ₂ -CH ₂ -), n-pentylene (-CH ₂ -CH ₂ - CH ₂ -CH ₂ -CH ₂ -). Divalent unsaturated hydrocarbon chains correspond to the definition of the divalent saturated hydrocarbon chain wherein at least two hydrogen atoms are displaced by an additional C-C bond to give at least one double bond or at least four hydrogen atoms are displaced by two additional C-C bonds to give at least one triple bond or both, such like -CH=CH- -CH ₂ -CH=CH- -CH=CH-CH ₂ - -CH ₂ -CH=CH-CH ₂ - -CH=CH-CH ₂ -CH ₂ - -CH ₂ -CH ₂ -CH=CH- and

-CH=CH-CH=CH- The hydrocarbon groups may be unsubstituted or substituted and/or may be branched or unbranched.

"linear hydrocarbon group" means a saturated or unsaturated divalent radical hydrocarbon chain as defined above which may be branched or unbranched. "branched" means that at least one hydrogen atom is displaced by an alkyl group. Branched linear hydrocarbon groups are for example -CH(CH ₃ )-, -CH(-CH ₂ -CH ₃ )- -CH(CH ₃ )-CH ₂ - -CH ₂ -CH(CH ₃ )-, -CH(-CH ₂ -CH ₃ )-CH ₂ -

-CH ₂ -CH(-CH ₂ -CH ₃ )-, -CH(CH ₃ )-CH ₂ -CH ₂ - -CH ₂ -CH(CH ₃ )-CH ₂ -

-CH ₂ -CH ₂ -CH(CH ₃ )-, -CH(CH ₃ )-CH ₂ -CH(CH ₃ )-, -CH(-CH ₂ -CH ₃ )-CH ₂ -CH ₂ - -CH ₂ -CH(-CH ₂ -CH ₃ )-CH ₂ - -CH ₂ -CH ₂ -CH(-CH ₂ -CH ₃ )-, and

-CH(-CH ₂ -CH ₃ )-CH ₂ -CH(-CH ₂ -CH ₃ )-. The linear hydrocarbon groups may be unsubstituted or substituted.

"cyclic hydrocarbon group" means a saturated or unsaturated divalent radical hydrocarbon chain the ends of which are bond to each other as to form a cyclic structure. The cyclic divalent saturated hydrocarbon group, when being unsubstituted, has gen- eral chemical Formula C _n H _2n - ₂ , wherein n is an integer from 3 to 8, preferably from 3 to 6, such like cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl. Cyclic divalent unsaturated hydrocarbon groups correspond to the definition of the cyclic divalent saturated hydrocarbon group wherein at least two hydrogen atoms are displaced by an additional C-C bond to give at least one double bond; such like cyclopropenyl, cyclobutenyl, cyclobu- tadienyl, cyclopentenyl, cyclopentadienyl, cyclohexenyl, and cyclohexadienyl. The cyclic hydrocarbon groups may be unsubstituted or substituted and/or may be branched or unbranched.

"linear hydrocarbon group interrupted by one or more oxygen atoms and/or nitrogen atoms" means a linear hydrocarbon group as defined above, wherein 1 to 10 of not neighbouring methylene groups (-CH ₂ -) are displaced by -0-; and/or 1 to 10 of methylene groups are displaced by -NR ⁵ -; and/or 1 to 10 of groups -CH= are displaced by -N=, and wherein R ⁵ is selected from the group comprising hydrogen and alkyl; such like -0-CH ₂ - -0-CO-CH ₂ - -CH ₂ -0-CH ₂ - -C ₂ H ₄ -0-C ₂ H ₄ -, -0-C ₂ H ₄ -0-C ₂ H ₄ -, -0-C ₂ H ₄ -0- -0-CO-C ₂ H ₄ -0-C ₂ H ₄ - -0-CO-C ₂ H ₄ -0- -0-CO-C ₂ H ₄ , -CH ₂ -0-CH ₂ -0-CH ₂ - -C ₂ H ₄ -0-C ₂ H ₄ -0-C ₂ H ₄ -

-C ₂ H ₄ -0-C ₂ H ₄ -0-C ₂ H ₄ -0-C ₂ H ₄ - -NH-CH ₂ - -NH-C ₂ H ₄ - -NH-C ₃ H ₆ - -NH-CO-CH ₂ - -NH-CO-C ₂ H ₄ - -NH-CO-C ₃ H ₆ - -CH ₂ -NH-CH ₂ - -NH-CH ₂ -NH-CH ₂ - -CH ₂ -NCH ₃ -CH ₂ - -CH ₂ -NC ₂ H ₅ -CH ₂ - -CH ₂ -NC ₃ H ₇ -CH ₂ - -C ₂ H ₄ -NH-C ₂ H ₄ - -NH-C ₂ H ₄ -NH-C ₂ H ₄ - -NH-CO-C ₂ H ₄ -NH-C ₂ H ₄ -

— C ₂ H ₄ — NCH ₃ — C ₂ H ₄ — , — C ₂ H ₄ — NC ₂ H5— C ₂ H ₄ — , — CH ₂ — NH— CH ₂ — O— CH ₂ — ,

-CH ₂ -0-CH ₂ -NH-CH ₂ - -CH ₂ -NH-CH ₂ -NH-CH ₂ - -CH ₂ -NCH ₃ -CH ₂ -0-CH ₂ - -CH ₂ -0-CH ₂ -NCH ₃ -CH ₂ - -CH ₂ -NCH ₃ -CH ₂ -NCH ₃ -CH ₂ - and

-CH ₂ -NH-CH ₂ -NCH ₃ -CH ₂ - The linear hydrocarbon groups interrupted by one or more oxygen atoms and/or nitrogen atoms may be unsubstituted or substituted and/or may be branched or unbranched.

"cyclic hydrocarbon group interrupted by one or more oxygen atoms and/or nitrogen atoms" means a cyclic hydrocarbon group as defined above, wherein 1 to 4 of not neighbouring methylen groups (-CH ₂ -) are displaced by -0-; and/or 1 to 4 of meth- ylen groups are displaced by -NR ⁵ -; and/or 1 to 4 of groups -CH= are displaced by -N=, and wherein R ⁵ is selected from the group comprising hydrogen and alkyl; such like oxirane, aziridine, azetidine, diazetidine, oxazetidine, oxetane, dioxetane, tetrahy- drofurane, dioxolane, oxazolidine, dioxazolidine, pyrrolidine, imidazolidine, oxadiazoli- dine, piperidine, hexahydropyrimidine, triazinane, oxazinane, dioxazinane, oxadia- zinane, tetrahydropyrane, dioxane, trioxane, oxirene, azirine, dihydro-azete, dihydro- diazete, diazete, oxazete, oxete, dihydro-furane, dioxole, dihydro-oxazole, dioxazole, dihydro-pyrrole, dihydro-imidazole, dihydro-oxadiazole, oxadiazole, tetrahydro-pyridine, dihydro-pyridine, tetrahydro-pyrimidine, dihydro-pyrimidine, tetrahydro-triazine, dihydro- triazine, dihydro-oxazine, oxazine, dioxazine, dihydro-oxadiazine, oxadiazine, dihydro- pyran, pyran, dioxine, oxazole, pyrrole, and furan. The cyclic hydrocarbon groups interrupted by one or more oxygen atoms and/or nitrogen atoms may be unsubstituted or substituted and/or may be branched or unbranched.

"aryl" means an aromatic hydrocarbon group having from 5 to 12 carbon atoms which may be substituted or unsubstituted and/or may be branched or unbranched and/or may be monovalent or divalent, such like phenyl, naphthyl, diphenyl, benzyl. Most preferably aryl is phenyl or benzyl.

"heteroaryl" means an aromatic moiety having 5 to 6 ring members and having as the ring members, in addition to carbon atoms, from 1 to 3 nitrogen atoms. Heteroaryl moieties may be unsubstituted or substituted and/or may be branched or unbranched and/or may be monovalent or divalent. Most preferably heteroaryl is pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, pyrrolyl, pyrazoyl, imidazoyl, triazoyl, and the like.

"phosphonate" means an organic derivative of phosphonic acid having general chemical Formula -R ⁶ -PO(OR ⁷ -)(OR ⁸ ), wherein R ⁶ to R ⁷ are independently selected from the group comprising a linear hydrocarbon group and aryl; and wherein R ⁸ is selected from the group comprising hydrogen, alkyl, aminoalkyl and aryl.

"amino" means the moiety -NR ⁹ R ¹⁰ , wherein R ⁹ and R ⁰ are independently selected from the group comprising hydrogen and alkyl, such like -NH ₂ , -NH-CH ₃ , -NH-CH ₂ -CH ₃ , -NH-CH ₂ -CH ₂ -CH ₃ , -N(CH ₃ ) ₂ , -N(CH ₃ )-CH ₂ -CH ₃ , -N(CH ₃ )-CH ₂ -CH ₂ -CH ₃ , -N(C ₂ H ₅ ) ₂ , -N(C ₂ H ₅ )-CH ₂ -CH ₂ -CH ₃ , and -N(C ₃ H ₇ ) ₂ .

"aminoalkyl" means an alkyl group as defined above substituted with one or more ami- no groups as defined above. Preferred aminoalkyl groups are selected from -CH ₂ -NH ₂ , -(CH ₂ ) ₂ -NH ₂ , -(CH ₂ ) ₃ -NH ₂ , -(CH ₂ ) ₄ -NH ₂ , and -(CH ₂ ) ₅ -NH ₂ .

"ester" means the moiety -CO-OR , wherein R is selected from the group comprising alkyl, such like -CO-OCH ₃ , -CO-OCH ₂ -CH ₃ , -CO-OCH ₂ -CH ₂ -CH ₃ , -CO-OCH ₂ -CH ₂ -CH ₂ -CH ₃ , and -CO-OCH ₂ -CH ₂ -CH ₂ -CH ₂ -CH ₃ .

"epoxy" means the moiety having general chemical Formula wherein R ² to R ⁴ are independently selected from the group comprising hydrogen, alkyl, hydroxyalkyi and aryl.

"hydroxyalkyi" means an alkyl group as defined above substituted with one or more hydroxy groups; such like -CH ₂ -OH, -CH(OH)-CH ₃ , -CH ₂ -CH ₂ -OH, -CH(OH)-CH ₂ -OH, -CH(OH)-CH ₂ -CH ₃ , -CH ₂ -CH(OH)-CH ₃ ,

-CH ₂ -CH ₂ -CH ₂ -OH, -CH(OH)-CH ₂ -CH ₂ -OH, and -CH ₂ -CH(OH)-CH ₂ -OH. The hydroxyalkyi groups may be branched or unbranched.

"acetylene" means -C≡CH, -C≡C-CH ₃ , -C≡C-CH ₂ -CH ₃ , and -C≡C-(CH ₂ )-CH ₃ .

"acrylic" means the moiety -CO-CR ⁶ =CR ⁷ R ¹⁸ , wherein R ⁶ to R ⁸ are independently selected from the group comprising hydrogen, alkyl and aryl such like -CO-CH=CH ₂ , -CO-C(CH ₃ )=CH ₂ , -CO-CH=CH-CH ₃ , -CO-CH=C(CH ₃ ) ₂ , -CO-C(CH ₃ )=C(CH ₃ ) ₂ , -CO-C(CH ₃ )=CH-CH ₃ , and -CO-CH=CH-C ₆ H ₅ .

"methacrylic" means the moiety -CO-CR ⁶ =CR ⁷ R ¹⁸ , wherein R ⁶ is -CH ₃ and R ⁷ to R ⁸ are as defined above.

"anhydride" means the moiety -CO-O-CO-R ⁹ , wherein R ⁹ is selected from the group comprising hydrogen and alkyl; such like -CO-O-CO-H, -CO-0-CO-CH ₃ , -CO-0-CO-CH ₂ -CH ₃ , and -CO-0-CO-CH ₂ -CH ₂ -CH ₃ .

"allyl" means the moiety -CR ²⁰ R ² -CR ²² =CR ²³ R ²⁴ , wherein R ²⁰ to R ²⁴ are independently selected from the group comprising hydrogen, alkyl and aryl; such like ^— CH

-CH2-C(CH ₃ )=C(CH ₃ )2, and

^— CH ₂ ^— CH=CH— C ₂ H ₅ .

"vinyl" means the moiety -CR ²⁵ =CR ²⁶ R ²⁷ , wherein R ²⁵ to R ²⁷ are independently selected from the group comprising hydrogen, alkyl and aryl; such like -CH=CH ₂ , -C(CH ₃ )=CH _2! -CH=CH-CH ₃ , -CH=C(CH ₃ ) ₂ , -C(CH ₃ )=C(CH ₃ ) ₂ , -CH=CH-C ₆ H ₅ ,

-CH=C(C ₂ H ₅ )2, -C(C2H ₅ )=CH-C ₆ H ₅ , and -CH=C(C ₂ H5)-C ₆ H ₅ .

"styrene" means the moiety -CR ²⁵ =CR ²⁶ R ²⁷ , wherein R ²⁶ is phenyl and R ²⁵ and R ²⁷ are as defined above. The phenyl group may be unsubstituted or substituted.

"carbonyl" means the moiety -CO-R ²⁸ , wherein R ²⁸ is selected from the group comprising hydrogen, alkyl and aryl; such like -COH, -CO-CH ₃ , -CO-CH ₂ -CH ₃ , -CO-CH ₂ -CH ₂ -CH ₃ , and -CO-C ₆ H ₅ . "acid halide" means the moiety -CO-R ²⁸ , wherein R ²⁸ is selected from the group comprising chloride and bromide, such like -CO-CI, and -CO-Br.

"heterocyclic" means a monovalent or divalent cyclic moiety having 5 to 6 ring members and having as the ring members, in addition to carbon atoms, from 1 to 3 nitrogen atoms. Heterocyclic moieties may be unsubstituted or substituted and/or may be branched or unbranched. Most preferably a heterocyclic hydrocarbon group is pyrroli- dinyl, imidazolidinyl, pyrazolidinyl, triazolidinyl, piperidinyl, hexahydropyridazinyl, hexa- hydropyrimidinyl, piperazinyl, triazinanyl, pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl, tria- zinyl, pyrrolyl, pyrazoyl, imidazoyl, triazoyl, and the like.

"ureido" means the moiety -NR ³ -CO-NR ²⁹ R ³⁰ , wherein R ²⁹ to R ³ are independently selected from the group comprising hydrogen, alkyl and aryl; such like -NH-CO-NH ₂ , -N(CH ₃ )-CO-NH ₂ , -NH-CO-NH(CH ₃ ), -NH-CO-N(CH ₃ ) ₂ , -N(CH ₃ )-CO-NH(CH ₃ ), -N(CH ₃ )-CO-N(CH ₃ ) ₂ , -NH-CO-NH-C ₆ H ₅ ,

-N(CH ₃ )-CO-NH-C ₆ H ₅ , -NH-CO-N(CH ₃ )-C ₆ H ₅ , -N(C ₂ H ₅ )-CO-NH _2>

-NH-CO-NH(C ₂ H ₅ ), -NH-CO-N(C ₂ H ₅ )2, -N(C2H5)-CO-NH(C ₂ H ₅ ),

-N(C2H ₅ )-CO-N(C2H ₅ )2, -N(C ₂ H5)-CO-NH-C ₆ H ₅ , -NH-CO-N(C ₂ H5)-C ₆ H ₅ . 'mercapto" means the moiety -S-R , wherein R is hydrogen.

"sulfide" means the moiety -S-R ¹⁵ , wherein R ⁵ is alkyl; such like -S-CH ₃ , — S— CH ₂ — CH ₃ , — S— C H ₂ ^_ C H ₂ ^_ C H 3 , — S ^— CH ₂ ^— CH ₂ ^— CH ₂ ^— CH ₃ , and

— S— C H ₂ — C H ₂ — C H ₂ — C H ₂ — C H ₃ .

"sulfonic acid" means the moiety -S0 ₂ -OH. "sulfinic acid" means the moiety -SO-OH. "thiosulfonic acid" means the moiety -SSO-OH. "thiocyanate" means the moiety -SCN.

"substituted" means that at least one hydrogen atom in an organic moiety is substituted by a substituent selected from hydroxyl, carbonyl, carboxyl, ester, anhydride, acid halide, epoxy, amino, nitrile, isonitrile, thiocyanate, halogen, mercapto, acrylic, meth- acrylic, allyl, vinyl, styrene, aryl, acetylene, azide, ureido group; 5 to 6 membered heterocyclic hydrocarbon groups containing from 1 to 3 nitrogen atoms; isonicotinamidyl, and bipyridyl. The mentioned substituents are as defined above.

Preferred attachments groups are selected from -SiR R ² -(CH ₂ )3-NH ₂ , -SiR R ² -(CH ₂ ) ₃ -SH, -SiR R ² -(CH ₂ ) ₃ -OH, -SiR R ² -(CH ₂ ) ₃ -COOH, -SiR R ² -(CH ₂ ) ₃ -COCI, -SiR R ² -(CH ₂ ) ₃ -CN,

-SiR R ² -(CH ₂ ) ₃ -SCN, -SiR R ² -(CH ₂ ) ₃ -CI, -SiR

-SiR R ² -(CH ₂ ) ₃ -C≡CH, -SiR R ² -(CH ₂ )3-C ₆ H5, -SiR ¹ R ² -(CH ₂ )3-N ₃ ,

-SiR R ² -(CH ₂ )3-S-CH ₃ , -SiR R ² -(CH ₂ )3-S-CH ₂ -CH3, -SiR R ² -(CH ₂ )3-S0 ₂ -OH, -SiR ¹ R -(CH ₂ ) ₃ -SO-OH, -SiR R ² -(CH ₂ ) ₃ -SSO-OH, -SiR R ² -(CH ₂ ) ₃ — H-CO-NH2, -(CH ₂ ) ₄ -NH ₂ , -(CH ₂ ) ₄ -SH,

-(CH ₂ ) ₄ -OH, -(CH ₂ ) ₄ -COOH, -(CH ₂ ) ₄ -COCI, -(CH ₂ ) ₄ -CN, -(CH ₂ ) ₄ -SCN, -(CH ₂ ) ₄ -CI, -(CH ₂ ) ₄ -CH=CH ₂ , -(CH ₂ ) ₄ -C≡CH, -(CH ₂ ) ₄ -C ₆ H ₅ , -(CH ₂ ) ₄ -N ₃ , -(CH ₂ ) ₄ -CO-CH=CH ₂ , -(CH ₂ ) ₄ -CO-C(CH ₃ )=CH2, -(CH ₂ ) ₄ -S-CH ₃ ,

-(CH ₂ ) ₄ -S-CH ₂ -CH ₃ , -(CH ₂ ) ₄ -S0 ₂ -OH, -(CH ₂ ) ₄ -SO-OH, -(CH ₂ ) ₄ -SSO-OH, -(CH ₂ ) ₄ -NH-CO-NH ₂ , -CH ₂ -CHOH-CH ₂ -0-(CH ₂ )3-NH ₂ , -CH ₂ - -CHOH-CH ₂ -0-(CH ₂ ) ₃ -SH,

-CH ₂ - -CHOH-CH ₂ -0-(CH ₂ ) ₃ -OH, -CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -COOH, -CH ₂ - -CHOH-CH ₂ -0-(CH ₂ ) ₃ -COCI, -CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -CN, -CH ₂ - -CHOH-CH ₂ -0-(CH ₂ ) ₃ -SCN, -CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -CI, -CH ₂ - -CHOH-CH ₂ -0-(CH ₂ ) ₃ -CH=CH ₂ , -CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -C≡CH, -CH ₂ - -CHOH-CH ₂ -0-(CH ₂ ) ₃ -C ₆ H ₅ , -CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -N ₃ , -CH ₂ - -CHOH-CH ₂ -0-(CH ₂ ) ₃ -CO-CH=CH ₂ ,

-CH ₂ - -CHOH-CH ₂ -0-(CH ₂ ) ₃ -CO-C(CH ₃ )=CH ₂ ,

-CH ₂ - -CHOH-CH ₂ -0-(CH ₂ ) ₃ -S0 ₂ -OH, -CHOH-CH ₂ -0-(CH ₂ ) ₃ -SO-OH, -CH ₂ - -CHOH-CH ₂ -0-(CH ₂ ) ₃ -SSO-OH, ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -S-CH ₃ , -CH ₂ - -CHOH-CH ₂ -0-(CH ₂ ) ₃ -S-CH ₂ -CH ₃ ,

-CH ₂ - -CHOH-CH ₂ -0-(CH ₂ ) ₃ -NH-CO-NH ₂ , -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -NH _2! -CH ₂ - -C ₆ H ₄ -(CH ₂ ) ₃ -SH, -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -OH, -CH ₂ - -C ₆ H ₄ -(CH ₂ ) ₃ -COOH, -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -COCI, -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -CN, -CH ₂ - -C ₆ H ₄ -(CH ₂ ) ₃ -SCN, -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -CI, -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -CH=CH ₂ , -CH ₂ - -C ₆ H ₄ -(CH ₂ ) ₃ -C≡CH, -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -C ₆ H ₅ , -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -N ₃ , -CH ₂ - -C ₆ H ₄ -(CH ₂ ) ₃ -CO-CH=CH ₂ , -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -CO-C(CH ₃ )=CH ₂ , -CH ₂ - -C ₆ H ₄ -(CH ₂ ) ₃ -S-CH ₃ , -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -S-CH ₂ -CH ₃ , -CH ₂ - -C ₆ H ₄ -(CH ₂ ) ₃ -S0 ₂ -OH, -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -SO-OH, -CH ₂ - -C ₆ H ₄ -(CH ₂ ) ₃ -SSO-OH, -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -NH-CO-NH ₂ , -CO- NH-(CH ₂ ) ₃ -NH ₂ , -CO-NH-(CH ₂ ) ₃ -SH, -CO- NH-(CH ₂ ) ₃ -OH, -CO-NH-(CH ₂ ) ₃ -COOH, -CO-NH-(CH ₂ ) ₃ -COCI, -CO- ^■ NH-(CH ₂ ) ₃ -CN, -CO-NH-(CH ₂ ) ₃ -SCN, -CO-NH-(CH ₂ ) ₃ -CI, -CO- ^■ NH-(CH ₂ ) ₃ -CH=CH ₂ , -CO-NH-(CH ₂ ) ₃ -C≡CH, -CO-NH-(CH ₂ ) ₃ -C ₆ H ₅ , -CO- ^■ NH-(CH ₂ ) ₃ -N ₃ , -CO-NH-(CH ₂ ) ₃ -CO-CH=CH ₂ , -CO- ^■ NH-(CH ₂ ) ₃ -CO-C(CH ₃ )=CH ₂ -CO-NH-(CH ₂ ) ₃ -S-CH ₃ , -CO-■NH-(CH ₂ ) ₃ -S-CH ₂ -CH ₃ , -CO-NH-(CH ₂ ) ₃ -S0 ₂ -OH, -CO- NH-(CH ₂ ) ₃ -SO-OH, -CO-NH-(CH ₂ ) ₃ -SSO-OH, -CO- NH-(CH ₂ ) ₃ -NH-CO-NH ₂ ,

-Si^ R _g - -CH^CHOH-CH^O-iCH^^^ ⁷

3 O

R and R ² are as defined above.

More preferred attachments groups are selected from -SiR R ² -(CH ₂ )3-NH ₂ , -SiR R ² -(CH ₂ ) ₃ -SH, -SiR R ² -(CH ₂ ) ₃ -SCN,

-SiR R ² -(CH ₂ ) ₃ -S-CH ₃ , -SiR R ² -(CH ₂ ) ₃ -S-CH ₂ -CH ₃ , -SiR R ² -(CH ₂ ) ₃ -S0 ₂ -OH, -SiR ¹ R ² -(CH ₂ ) ₃ -SO-OH, -SiR ¹ R ² -(CH ₂ ) ₃ -SSO-OH, -SiR R ² -(CH ₂ ) ₃ — NH-CO-NH ₂ , -(CH ₂ ) ₄ -NH ₂ , -(CH ₂ ) ₄ -SH,

-(CH ₂ ) ₄ -SCN, -(CH ₂ ) ₄ -S-CH ₃ , -(CH ₂ ) ₄ -S-CH ₂ -CH ₃ , -(CH ₂ ) ₄ -S0 ₂ -OH, -(CH ₂ ) ₄ -SO-OH, -(CH ₂ ) ₄ -SSO-OH, -(CH ₂ ) ₄ -NH-CO-NH ₂ ,

-CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -NH ₂ , -CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -SH,

-CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -SCN,

-CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -S0 ₂ -OH, -CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -SO-OH,

-CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -SSO-OH, -CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -S-CH ₃ ,

-CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -S-CH ₂ -CH ₃ ,

-CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -NH-CO-NH ₂ , — CH ₂ — CeH ₄ — (CH ₂ ) ₃ — NH ₂ ,

-CH ₂ — CeH ₄ — (CH ₂ ) ₃ — SH, -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -SCN,

-CH ₂ — C6H4— (CH ₂ ) ₃ — S— CH ₃ , — C H ₂ — C 6 H 4— ( C H ₂ ) 3— S— C H ₂ — C H ₃ ,

-CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -S0 ₂ -OH, -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -SO-OH,

-CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -SSO-OH, -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -NH-CO-NH ₂ ,

-CO-NH-(CH ₂ ) ₃ -NH ₂ , -CO-NH-(CH ₂ ) ₃ -SH,

-CO-NH-(CH ₂ ) ₃ -SCN, -CO-NH-(CH ₂ ) ₃ - -CO-NH-(CH ₂ ) ₃ -S-CH ₂ -CH ₃ , -CO-NH-(CH ₂ ) ₃ -S0 ₂ -OH, -CO-NH-(CH ₂ ) ₃ -SO-OH, -CO-NH-(CH ₂ ) ₃ -SSO-OH, and -CO-NH-(CH ₂ ) ₃ -NH-CO-NH ₂ .

Even more preferred attachments groups are selected from -SiR R ² -(CH ₂ ) ₃ -NH ₂ , -SiR R ² -(CH ₂ ) ₃ -SH, -SiR R ² -(CH ₂ ) ₃ -SCN, -SiR R ² -(CH ₂ ) ₃ -S-CH ₃ ,

-SiR R ² -(CH ₂ ) ₃ -S-CH ₂ -CH ₃ , -SiR R ² -(CH ₂ ) ₃ -S0 ₂ -OH, -SiR R ² -(CH ₂ ) ₃ -SO-OH, -SiR R ² -(CH ₂ ) ₃ -SSO-OH, and -SiR R ² -(CH ₂ ) ₃ — NH-CO-NH ₂ .

In one embodiment in which the plastics materials is a solder resist the more preferred attachments groups are selected from -SiR R ² -(CH ₂ )3-NH2, -SIR ¹ R ² -(CH ₂ ) ₃ -SH, -SIR ¹ R ² -(CH ₂ ) ₃ -SCN,

-SiR R ² -(CH ₂ ) ₃ -NH-CO-NH ₂ , -(CH ₂ ) ₄ -NH ₂ , -(CH ₂ ) ₄ -SH,

-(CH ₂ ) ₄ -SCN, -(CH ₂ ) ₄ -NH-CO-NH ₂ , -CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -NH ₂ ,

-CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -SH,

-CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -NH-CO-NH ₂ , -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -NH ₂ , -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -SH, -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -SCN, -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -NH-CO-NH ₂ , -CO-NH-(CH ₂ ) ₃ -NH ₂ , -CO-NH-(CH ₂ ) ₃ -SH, -CO-NH-(CH ₂ ) ₃ -SCN, and -CO-N H-(C H ₂ ) ₃ -N H-CO-N H ₂ .

In a more preferred embodiment in which the plastics materials is a solder resist the more preferred attachments groups are selected from -SiR R ² -(CH ₂ ) ₃ -NH ₂ , -SiR R ² -(CH ₂ ) ₃ -SH, -SiR R ² -(CH ₂ ) ₃ -SCN, and -SiR R ² -(CH ₂ ) ₃ — NH-CO-NH ₂ .

In one embodiment in which the plastics materials is a resist the more preferred attachments groups are selected from attachment groups containing a sulphur containing group. In this embodiment the resist is preferably selected from patterning resists and solder resists, preferably it is one or more patterning resists.

In a more preferred embodiment in which the plastics materials is a resist the more preferred attachments groups are selected from -SiR R ² -(CH ₂ ) ₃ -SH, -SiR R ² -(CH ₂ ) ₃ -SCN, -SiR R ² -(CH ₂ ) ₃ -S-CH ₃ , -SiR R ² -(CH ₂ ) ₃ -S-CH ₂ -CH ₃ , -SiR R ² -(CH ₂ ) ₃ -S0 ₂ -OH, -SiR R ² -(CH ₂ ) ₃ -SO-OH, -SiR R ² -(CH ₂ ) ₃ -SSO-OH, -(CH ₂ ) ₄ -SH, -(CH ₂ ) ₄ -SCN,

-(CH ₂ ) ₄ -S-CH ₃ , -(CH ₂ ) ₄ -S-CH ₂ -CH ₃ , -(CH ₂ ) ₄ -S0 ₂ -OH, -(CH ₂ ) ₄ -SO-OH, -(CH ₂ ) ₄ -SSO-OH, -CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -SH, -CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -SCN,

-CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -S0 ₂ -OH, -CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -SO-OH, -CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -SSO-OH, -CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -S-CH ₃ , -CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -S-CH ₂ -CH ₃ , — CH ₂ — C6H— (CH ₂ ) ₃ — SH, -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -SCN, — C H ₂ — CQH— (C H ₂ ) ₃ — S— C H 3 , ^— CH ₂ — CeH ₄ — (CH ₂ ) ₃ — S ^— CH ₂ — CH ₃ , -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -S0 ₂ -OH, -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -SO-OH, -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -SSO-OH, -CO-NH-(CH ₂ ) ₃ -SH, CO-NH-(CH ₂ ) ₃ -SCN, -CO-NH-(CH ₂ ) ₃ -S-CH _3! CO-NH-(CH ₂ ) ₃ -S-CH ₂ 3, -CO-NH-(CH ₂ ) ₃ -S0 ₂ -OH,

-CO-NH-(CH ₂ ) ₃ -SO-OH, and -CO-NH-(CH ₂ ) ₃ -SSO-OH. In this embodiment the resist is preferably selected from patterning resists and solder resists, preferably it is one or more patterning resists.

In a more preferred embodiment in which the plastics materials is a resist the more preferred attachments groups are selected -SiR R ² -(CH ₂ ) ₃ -SH,

-SiR R ² -(CH ₂ ) ₃ -SCN, -SiR R ² -(CH ₂ ) ₃ -S-CH ₃ , -SiR R ² -(CH ₂ ) ₃ -S-CH ₂ -CH ₃ , -SiR R ² -(CH ₂ ) ₃ -S0 ₂ -OH, -SiR R ² -(CH ₂ ) ₃ -SO-OH, and -SiR R ² -(CH ₂ ) ₃ -SSO-OH. In this embodiment the resist is preferably selected from patterning resists and solder resists, preferably it is one or more patterning resists.

In one preferred embodiment in which the plastics materials is a prepreg the more preferred attachments groups are selected from -SiR R ² -(CH ₂ ) ₃ -NH ₂ , -SiR R ² -(CH ₂ ) ₃ -SH, -SiR R ² -(CH ₂ ) ₃ -SCN,

-SiR R ² -(CH ₂ ) ₃ — NH-CO-NH ₂ , -(CH ₂ ) ₄ -NH ₂ , -(CH ₂ ) ₄ -SH,

-(CH ₂ ) ₄ -SCN, -(CH ₂ ) ₄ -NH-CO-NH ₂ , -CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -NH ₂ ,

-CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -SH,

-CH ₂ -CHOH-CH ₂ -0-(CH ₂ ) ₃ -NH-CO-NH ₂ , -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -NH ₂ , -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -SH, -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -SCN, -CH ₂ -C ₆ H ₄ -(CH ₂ ) ₃ -NH-CO-NH ₂ , -CO-NH-(CH ₂ ) ₃ -NH ₂ , -CO-NH-(CH ₂ ) ₃ -SH, -CO-NH-(CH ₂ ) ₃ -SCN, and -CO-N H-(C H ₂ ) ₃ -N H-CO-N H ₂ .

In a more preferred embodiment in which the plastics materials is a prepreg the more preferred attachments groups are selected from -SiR R ² -(CH ₂ ) ₃ -NH ₂ , -SiR R ² -(CH ₂ ) ₃ -SH, -SiR R ² -(CH ₂ ) ₃ -SCN, and -SiR R ² -(CH ₂ ) ₃ — NH-CO-NH ₂ .

By at least one attachment group it is meant that attachment groups with different linking groups L and/or different functional chemical groups FG can be bound to the same nanometer-sized particle. For example, the linking group L of a first attachment group can be an alkyl group and the linking group L of a second attachment group can be an aryl group bound to the same nanometer-sized particle. For example, the functional chemical group FG of a first attachment group can be a thiol group and the functional chemical group FG of a second attachment group can be an amino group, both attachment groups bound to the same nanometer-sized particle. The functional chemical group FG suitable for binding to a surface of a metal, a metal oxide or a semiconductor can be any functionality which forms a bond to the respective surface. Preferably the functional chemical group FG is as defined above.

Generally, the attachment group bearing a functional chemical group suitable for binding to a surface of a metal, a metal oxide or a semi-conductor is bound to the surface of the nanometer-sized particles chemically by forming a chemical bond or physically by adhesion forces.

In accordance with a preferred embodiment of the present invention, the at least one attachment group is bound to nanometer-sized silica particles as shown in Figure 1 . This means, that a chemical (covalent) bond is formed between the binding group B of the attachment group according to Formula (I) and a reactive center on the silica surface of the particle. As an example the reaction of (3-aminopropyl) triethoxysilane with a silica particle is discussed. Such reaction is believed to be a condensation reaction at the silica particle's surface which normally has, due to hydrolysis, Si-OH groups which are exposed at the surface thereof. Such condensation reaction of a silane compound, in this example (3-aminopropyl) triethoxysilane, with the silica particle's surface Si-OH groups may be as follows:

Si-OH + (C ₂ H ₅ 0) ₃ Si-(CH ₂ )3-NH ₂ Si-0-Si(C ₂ H ₅ 0) ₂ -(CH ₂ )3-NH ₂ + C ₂ H ₅ OH

It is believed that further reaction steps may take place at further surface Si-OH groups as follows:

Si-OH + Si-0-Si(OC ₂ H ₅ ) ₂ -(CH ₂ ) ₃ -NH ₂ >- + C ₂ H ₅ OH and Si-0

Si-0 - I

Si-OH + Si(OC ₂ H ₅ )-(CH ₂ ) ₃ -NH Si-0-Si-(CH ₂ ) ₃ -NH ₂ C ₂ H ₅ OH

Si-O ^' I

Si-0

The further surface Si-OH groups may stem from the silica particle or may stem from further attachment groups that reacted in the nearest vicinity of the attachment group in focus onto the silica's particle surface. Thus, the trialkoxy silicon moiety of the silane compound may create an additional layer of a silica structure on the surface of the silica particle, while the organic functional group also being part of the silane compound builds the outer layer of the silica particle. A simple model of this structure generated by reaction of a silane compound with a silica particle is presented in Figure 1 . This model is presented in order to facilitate understanding of the functionalization step by using silane compounds. The real structure generated by reaction of a silane compound with a silica particle might be more diverse and complicated than the simple model is able to describe. Halogen atoms instead of alkoxy groups in the silane compound react in a similar way. The formation of an additional layer of a silica structure from silane compounds is also possible on the surface of nanometer-sized particles comprising reactive oxygen groups on their outer surface. The formation of an additional layer of a silica structure from silane compounds is in particular possible on the surface of nanometer-sized oxide particles of alumina, titania, zirconia, tin oxide and zinc oxide of a preferred embodiment of the present invention.

The silica particles having at least one attachment group bearing a functional chemical group suitable for binding to a surface of a metal, a metal oxide or a semi-conductor can be produced by reacting the silica particles with a trialkoxy silane compound bearing an organic functional group according to the process described by Choi and Chen (Choi & Chen, Journal of Colloid and Interface Science 258, p. 435-437, 2003) and as described by patent application PCT/EP 2012/074433 which is referred to be incorporated into the description of the present application. More elaborate and diverse embodiments and examples of preparing the silica particles modified by bonding one or a plurality of different aminosilanes to the surface thereof are disclosed in EP 1 894 888 A1 , which are referred to be incorporated into the description of the present application. The nanometer sized oxide particles of alumina, titania, zirconia, tin oxide and zinc oxide of a preferred embodiment of the present invention having at least one attachment group bearing a functional chemical group suitable for binding to a surface of a metal, a metal oxide or a semi-conductor can be produced in a way analogous to the functionalized silica particles as described above. Lesniak et al. present for example an analogous functionalization of iron oxide particles with organo silanes (US 6, 183,658). Further silane compounds for functionalization of silica particles were reported by Radhakrishnan et al. (Radhakrishnan et al., Soft Matter, 2006, 2, p. 386-396) and Park et al (Park et al., Chem. Commun., 201 1 , 47, 4860-4871 ). Using these silane compounds various organic functional groups were introduced to the particle's surfaces which could further be modified to bind polymers.

In addition to silane compounds reagents not containing silicon moieties were developed for functionalization of silica particles. Organic compounds bearing an organic functional group and containing isocyanato groups or oxirane groups are also reactive to silanol groups of silica particles according to Liu et al. (Liu et al., Journal of Colloid and Interface Science 336, 2009, 189-194, and Liu et al., Nanotechnology 14, 2003, 813-819). Various organic functional groups were introduced to the particle's surfaces. The organic functional groups could also be modified in order to bind polymers.

A multiple step and thus more elaborate strategy for functionalizing silica particles starts with replacing the silanol groups with chlorine atoms (see Locke et al., Analytical Chemistry, Vol. 44, No. 1 , 1972, 90-92). The activated particle surface can be modified with aryl or alkyl moieties by grignard reaction or wurtz reaction creating a covalent bond between the silicon of the silica particle and a carbon atom of the aryl or alkyl moiety. The aryl or alkyl moieties can be further modified by reactions known in the field of organic synthetic chemistry in order to bear organic functional groups.

All of the above described functionalizations relate to already existing particles and belong therefore to the group of post modification of particles. It is also possible to generate functionalized particles by so called in situ modification or co-condensation. These methods simultaneously generate particles and functionalize it. Functionalized silica particles for example can be synthesized by reacting tetraethoxysilane (TEOS) in the presence of a trialkoxysilane bearing an organic functional group according to Rahman et al. and Naka et al. (Rahman et al., Ceramics International 35, 2009, 1883- 1888, and Naka et al., Colloids and Surfaces A: Physicochem. Eng. As-pects 361 , 2010, 162-168). Thus, silica particles are created that already have organic functional groups attached to their outer surface and within their interior structure. In contrast, particles functionalized by post modification have organic functional groups attached to their outer surface, solely.

All functionalities of particles initially introduced by in situ modification or post modification can be further modified by reactions known in the field of organic synthetic chemistry in order to create the desired organic functional groups.

Characterization of the functionalization of nanometer-sized particles can be performed by Fourier Transform Infra Red - Attenuated Total Reflectance (FTIR-ATR) spectroscopy and Nuclear Magnetic Resonance (NMR) spectroscopy. These methods for characterizing surface functionalities of nanometer-sized particles are known to the persons skilled in the art. Characterization of the surface functionalities of silica particles of the present invention is described in the Example Section. These methods are equally applicable for other types of nanosized-particles, e.g. alumina, titania, zirconia, tin oxide and zinc oxide particles, a preferred embodiment of the present invention.

The attachment groups bearing a functional chemical group suitable for binding to a surface of a metal, a metal oxide or a semi-conductor serve to create a bond between the particles and the surface of a metal, a metal oxide or a semi-conductor to be bonded to the plastics materials surface. The bond between the particles and the surface of a metal, a metal oxide or a semi-conductor can be both a chemical as well as a physical bond. A chemical bond generally is a covalent bond formed between the metal, the metal oxide or the semi-conductor and at least one functional chemical group suitable for binding to a surface of a metal, a metal oxide or a semi-conductor. The bond between the particles and the surface of a metal, a metal oxide or a semi-conductor can as well be an ionic bond. A physical bond generally is provided by adhesion forces between the surface of a metal, a metal oxide or a semi-conductor and the attachment group bearing a functional chemical group suitable for binding to the surface of a metal, a metal oxide or a semi-conductor. A physical bond can be based on the formation of hydrogen bridges, on van der Waals interactions or dispersion forces. The present invention relates to a method for the treatment of a surface of a metal, a metal oxide or a semi-conductor for the subsequent formation of a firmly adhesive bonding between the surface of a metal, a metal oxide or a semi-conductor and a plastics materials surface comprising the step of

i. contacting the surface of a metal, a metal oxide or a semi-conductor with a solution containing nanometer-sized particles having at least one attachment group bearing a functional chemical group suitable for binding to the surface of a metal, a metal oxide or a semi-conductor, thereby forming a layer of said nanometer-sized particles on at least a portion of the surface of a metal, a metal oxide or a semi-conductor.

The surface of a metal, a metal oxide or a semi-conductor is provided in the form of a layer already existing prior to contacting it with the nanometer-sized particles of the invention. The surface of a metal, a metal oxide or a semi-conductor may be a sole layer or may be a layer attached to a substrate. A sole layer, for example, may be a metal foil or semiconductor wafer. The substrate a layer of a metal, a metal oxide or a semi-conductor is attached to, for example, may be a circuit carrier. In a preferred embodiment the surface of a metal, a metal oxide or a semi-conductor is on a printed circuit board, an IC substrate or a semi-conductor wafer. In a more preferred embodiment the metal surface is on a printed circuit board or an IC substrate. Thus, the surface or the layer of a metal, a metal oxide or a semi-conductor is not deposited onto the nanometer-sized particles of the invention by wet-chemical methods or by vacuum deposition methods.

Various kinds of metals, metal oxides or semi-conductors can be bonded to a plastics material with a method according to the present invention. The metals to be bonded to a plastics material are selected from the group comprising copper, copper alloy, tin, zinc, nickel, aluminium, gold, silver, platinum, iron, iridium, and alloys thereof. Preferred metals are selected from the group comprising copper, copper alloy, tin, zinc, nickel, aluminium, gold, silver and alloys thereof. Even more preferred are metals selected from the group comprising copper, copper alloy and tin. The method according to the present invention is particularly suitable to bond a plastics material surface to a surface of a metal. The metal oxides to be bonded to a plastics material are selected from the group comprising tin oxide, indium tin oxide (ITO) and aluminium doped zinc oxide (AZO).

The semi-conductors to be bonded to a plastics material are selected from the group comprising silicon, germanium, gallium, arsenide and silicon carbide.

The plastics material is selected from a prepreg or a resist. The resist is selected from a patterning resist and a solder resist.

In one embodiment, the plastics material is a partially cured thermosetting polymer composition, also known in the art as a prepreg or "B" stage resin. The polymer composition or prepregs may be prepared by impregnating woven glass reinforcement materials, e.g. fiberglass, with partially cured resins or polymers. The partially cured resins or polymers are selected from the group comprising epoxy resins, e.g. difunctional, tetrafunctional and other multifunctional epoxies; amino-type resins produced from the reaction of formaldehyde and urea or formaldehyde and melamine; polyesters, phenol- ics, silicones, polyamides, polyimides, diallyl phthalates, phenyl silanes, polybenzimid- azoles, diphenyloxides, polytetrafluoroethylenes (PTFE), polycyanate esters, butadiene terephthalate resins, and mixtures thereof.

The nanometer-sized functionalized particles of the present invention impart improved adhesion strength and a permanent firm adhesion of the plastics material bonded to the surface of a metal, a metal oxide or a semi-conductor. In particular, the nanometer- sized particles of the present invention impart improved adhesion strength and a permanent firm adhesion of the prepreg bonded to the surface of a metal or a metal oxide. The nanometer-sized particles of the present invention thus provide a firm bond of the prepreg to the layer of a metal or a metal oxide throughout the entire life of a circuit carrier, preferably a printed circuit board or an integrated circuit substrate.

The term "circuit carrier" is defined herein as a device which is used to provide electrical interconnections between various electronic components and other components mounted thereon, such as resistors, capacitors, transistors, integrated circuits, transformers, LEOs, switches, edge connectors and the like. A circuit carrier may be a printed circuit board or a hybrid circuit board or a multi chip module or an integrated circuit substrate or a semi-conductor wafer or the like.

In a further embodiment, the plastics material is a resist for a solder mask, also called solder stop mask or solder resist. The solder resist is a polymer layer that is applied to the conductive lines of a circuit carrier, for example the copper traces of a printed circuit board. The solder resist protects the conductive lines against oxidation and prevents solder bridges from forming between closely spaced solder pads. A solder bridge is an unintended electrical connection between two conductors by a small spot of solder. The polymers for solder masks are based on epoxy resins.

Solder masks may be applied in different ways to the surface of the circuit carrier. Solder masks may be applied as a liquid that is silkscreen printed onto the circuit carrier. Other types are liquid photoimageable solder masks (LPSM) inks and dry film pho- toimageable solder masks (DFSM). LPSM can be silkscreen printed or sprayed on the circuit carrier, exposed and developed to provide openings in the conductive line pattern for parts to be soldered to the metal pads. A DFSM is vacuum laminated on the circuit carrier then exposed and developed. Afterwards, the polymer layer of the solder mask is thermally cured.

The solder resist has to withstand soldering conditions, like high temperatures, and remains on the surface of the circuit carrier after manufacturing process throughout the whole lifetime of the circuit carrier. The nanometer-sized functionalized particles of the present invention impart improved adhesion strength and a permanent firm adhesion of the solder resist bonded to the surface of a metal, a metal oxide or a semi-conductor. The nanometer-sized particles of the present invention thus provide a firm bond of the solder resist to the surfaces of a metal, a metal oxide or a semi-conductor during manufacturing a circuit carrier.

In a further embodiment, the plastics material is a resist, in particular a photo imagea- ble resist. Resists are usually acrylic-based resists, i.e., they have an acrylic or meth- acrylic backbone. These resists are used to generate conductor line patterns on circuit carriers. These resists are therefore called patterning resists or photo imageable resists herein. They are usually applied as a dry film or a liquid film. The dry film is a common imageable photoresist consisting of a cover or support sheet, a photoimageable layer, and a protective layer, as provided by DuPont, Hitachi. Liquid photo resists are applied directly onto the metal layer by, e.g., roller coating, curtain coating, without protective layers (e.g., Huntsman, Rohm & Haas, Atotech). The nanometer-sized functionalized particles of the present invention impart improved adhesion strength and a temporary firm adhesion of the resist bonded to the surface of a metal, a metal oxide or a semiconductor. The nanometer-sized particles of the present invention thus provide a firm bond of the resist to the surfaces of a metal, a metal oxide or a semi-conductor during manufacturing a circuit carrier.

In one embodiment the plastics material is a resist, preferably selected from a patterning resist and a solder resist, more preferably a patterning resist. In this embodiment the material, of which the nanometer-sized particles are comprised, is preferably selected from an inorganic oxide and a metal, more preferably an inorganic oxide. In this embodiment the attachment group is preferably an attachment group containing a sulphur containing group. Preferably the functional chemical group FG of the attachment group is selected from amino, ureido, mercapto, sulfide, sulfonic acid, sulfinic acid, thi- osulfonic acid, and thiocyanate group, more preferably from mercapto, sulfide, sulfonic acid, sulfinic acid, thiosulfonic acid, and thiocyanate group.

In one embodiment, the method of the invention comprises the further step of pre- treating the surface of a metal, a metal oxide or a semi-conductor prior to contacting the surface of a metal, a metal oxide or a semi-conductor with a solution containing nanometer-sized particles (step i.). The pre-treating step may comprise one or more of the following steps.

In one embodiment the pre-treating step may comprise a pre-treating with an etching solution. Thus, the surface of a metal, a metal oxide or a semi-conductor is treated with an etching solution prior to step i.

The etching solution comprises a sulfuric solution. The etching solution further comprises an oxidizing agent. The sulfuric solution comprises sulfuric acid and/or an alkali metal hydrogensulfate, like sodium or potassium hydrogensulfate. The oxidising agent comprises peroxo compounds. The peroxo compounds are selected from the group comprising hydrogen peroxide, disodium peroxodisulfate, dipotassium peroxodisulfate, ammonium peroxodisulfate, sodium caroate and potassium caroate; preferably disodi- um peroxodisulfate.

The concentration of sulfuric acid in the etching solution ranges from 20 - 100 g/l, preferably from 40 - 80 g/l. The concentration of the alkali metal hydrogensulfate in the etching solution ranges from 10 - 40 g/l. The concentration of the oxidising agent in the etching solution ranges from 80 - 120 g/l.

The duration of pre-treating the metal layer with the etching solution ranges from 30 seconds - 10 minutes, preferably from 30 seconds - 5 minutes, more preferably from 30 seconds - 2 minutes.

During contacting the metal layer with the etching solution the temperature of the etching solution ranges from 20 °C - 40 'Ό, preferably from 25 °C - 35 'Ό, more preferably from 25 °C - 30 °C.

In a further embodiment the pre-treating step may comprise a pre-treating with 0.5 to 2 M sulfuric acid for 0.5 to 5 minutes at a temperature between 15 and 40 'Ό.

In a further embodiment the pre-treating step may comprise a pre-treating with a surface activator. The surface activator is used for cleaning and conditioning the surface of a metal, a metal oxide or a semi-conductor.

The surface activator may be acidic or alkaline and comprises a surfactant and a silicate. If the surface activator is acidic it comprises an acid, preferably an inorganic acid, like sulphuric acid, phosphoric acid or nitric acid. If the surface activator is alkaline it comprises an alkaline compound, like sodium hydroxide, potassium hydroxide, borates or phosphates.

Pre-treating with a surface activator is performed for 10 seconds to 5 minutes at a temperature ranging from 30 °C - 60 °C.

The pre-treating step is performed in order to clean the surface of a metal, a metal oxide or a semi-conductor to ensure that the contacting with a solution containing nanometer-sized particles (method step i.) is effective. Any conventional cleaning solution can be used. Normally, wetting agents and sometimes complexer (such as triethanol- amine)-containing aqueous solutions are used. The pre-treating step may be performed in order to additionally etch the surface of a metal, a metal oxide or a semiconductor.

The further steps comprised in the pre-treating step may be followed by a rinsing step, preferably with warm, deionized water. The last step of the pre-treating step may be a drying of the pre-treated surface of a metal, a metal oxide or a semi-conductor, i.e. a drying step, e.g. with hot air.

The method of the present invention for the treatment of a surface of a metal, a metal oxide or a semi-conductor for the subsequent formation of a firmly adhesive bonding between the surface of a metal, a metal oxide or a semi-conductor and a plastics materials surface comprises the step of i. contacting the surface of a metal, a metal oxide or a semi-conductor with a solution containing nanometer-sized particles having at least one attachment group bearing a functional chemical group suitable for binding to the surface of a metal, a metal oxide or a semi-conductor, thereby forming a layer of said nanometer-sized particles on at least a portion of the surface of a metal, a metal oxide or a semi-conductor.

The method steps of the present invention are performed according to the given order but do not necessarily have to be performed directly one after another. Additional steps may be performed between the said method steps.

The nanometer-sized particles according to method step i. are selected from the nanometer-sized particles comprising only one material or comprising more than one material. In a preferred embodiment the nanometer-sized particles according to method step i. are selected from the group of nanometer-sized oxide particles comprising one or more of silica, alumina, titania, zirconia, tin oxide and zinc oxide particles.

The nanometer-sized particles according to method step i. are in a concentration ranging from 0.5 g/l to 100.0 g/l, preferred in a range from 2.5 g/l to 75.0 g/l, more preferred in a range from 2.5 g/l to 50.0 g/l, and most preferred in a range from 2.5 g/l to 20.0 g/l. The nanometer-sized particles are suspended in a solution in a concentration that is easy to handle physically or that is suited to create at least a monolayer of the particles on the surface of the substrate.

The nanometer-sized particles according to method step i. have a number of attachment groups on their surface ranging from 1 to 100 attachment groups / nm ² of particle surface area, preferably ranging from 1 to 80 attachment groups / nm ² of particle surface area, more preferably ranging from 1 to 60 attachment groups / nm ² of particle surface area, even more preferably ranging from 1 to 30 attachment groups / nm ² of particle surface area, even more preferably ranging from 1 to 10 attachment groups / nm ² of particle surface area. In one embodiment in which the attachment group has a functional chemical group selected from amino and ureido groups, the number of attachment groups ranges from 10 to 80 attachment groups / nm ² of particle surface area, preferably from 10 to 60 attachment groups / nm ² of particle surface area, more preferably from 30 to 60 attachment groups / nm ² of particle surface area. In another embodiment in which the attachment group is selected from attachment groups containing a sulphur containing group, preferably selected from mercapto, sulfide, sulfonic acid, sulfinic acid, thiosulfonic acid, and thiocyanate group, the number of attachment groups ranges from 1 to 30 attachment groups / nm ² of particle surface area, preferably from 1 to 10 attachment groups / nm ² of particle surface area, more preferably from 2 to 6 attachment groups / nm ² of particle surface area.

The number of attachment groups on the particle surfaces is determined by methods for measuring numbers of chemical functional groups. The methods are known in the art, for example H. Choi, I. W. Chen, Journal of Colloid and Interface Science 2003, 258, 435-437; I. Bravo-Osuna, D. Teutonico, S. Arpicco, C. Vauthier, G. Ponchel, International Journal of Pharmaceutics 2007, 340, 173-181 . Determination of the number of attachment groups on particle surfaces is described in the Examples.

The solution containing nanometer-sized particles according to method step i. further comprises a solvent selected from alcohols, ketones and water. Examples of solvents are methanol, ethanol, propanol, butanol or acetone. Preferred solvents are selected from ethanol, n-propanol, i-propanol, acetone and water. Contacting the surface of a metal, a metal oxide or a semi-conductor with a solution containing nanometer-sized particles according to method step i. is performed by dipping or immersing the surface of a metal, a metal oxide or a semi-conductor into said solution; or by spraying or pipetting the solution onto the surface of a metal, a metal oxide or a semi-conductor. Contacting the surface of a metal, a metal oxide or a semiconductor with a solution containing nanometer-sized particles according to method step i. is performed at least once. Alternatively, said contacting can be performed several times, preferably between 1 to 20 times, more preferred between 1 to 10, even more preferred between 1 to 5 times, and most preferred between once to twice.

Contacting the surface of a metal, a metal oxide or a semi-conductor with a solution containing nanometer-sized particles according to method step i. is performed for a time period ranging from 1 to 20 minutes, preferred from 2 to 10 minutes, most preferred from 4 to 7 minutes.

Contacting the substrates with a solution containing nanometer-sized particles according to method step i. is performed at a temperature ranging from 15 to 80 'C, preferred from 20 to 70 'C, most preferred from 25 to 65 'C. The substrates are the surfaces of a metal, a metal oxide or a semi-conductor.

The solution containing one or more nanometer-sized particles generally is a colloid.

Method step i. of the present invention may be followed by a rinsing step. Rinsing the surface of a metal, a metal oxide or a semi-conductor may be performed in order to remove the non-reacted nanometer-sized particles from the surface of the metal layer.

Rinsing is performed in an acid solution, an alkaline solution or deionized water. The acid may be any inorganic or organic acid. The chemical base may be any inorganic or organic base. The concentration of the acid or chemical base in the acid solution or alkaline solution, respectively, is set in order not to dissolve the nanometer-sized particles, but keep the particles solvolytically stable and keep a stable suspension or colloid of the nanometer-sized particles. Rinsing the substrates may be performed for 0.5 to 10 minutes at a temperature ranging from 20 to 45 'C. The substrates are the surfaces of a metal, a metal oxide or a semi-conductor. In a further embodiment of the present invention a further method step may be performed after method step i.:

ia. heating the surface of a metal, a metal oxide or a semi-conductor to an elevated temperature.

Step ia. is performed after step i. or after the rinsing step. This further method step is also called annealing. The elevated temperature ranges from 60 to 400 °C, preferred from 80 to 200 °C, more preferred from 100 to 160 ^< €, most preferred from 120 to 140 °C.

Annealing according to method step ia., is performed for a time period ranging from 1 to 60 minutes, preferred from 1 to 30 minutes, more preferred from 7 to 20 minutes, most preferred from 5 to 15 minutes.

Method step ia. is performed in order to attach the functional chemical groups present on the surface of the nanometer-sized particles to the metal. This method step further improves the adhesion strength between surfaces of a metal, a metal oxide or a semiconductor and plastics material surfaces. This effect is particularly pronounced when the plastics material is selected from a prepreg and a solder resist. This effect is further pronounced when the functional chemical group FG is selected from amino, ureido, mercapto, sulfide, sulfonic acid, sulfinic acid, thiosulfonic acid, and thiocyanate group, preferably from amino, ureido and mercapto group.

An etching of the surface of a metal, a metal oxide or a semi-conductor is not required in order for the nanometer-sized particles of the present invention to impart improved adhesion strength to the surface of a metal, a metal oxide or a semi-conductor. The sole application of the nanometer-sized particles (without an etching step) contributes the major portion to improvement of the adhesion strength. Nevertheless, an etching has also a minor enhancing influence on the adhesion strength. The combination of etching the surface of a metal, a metal oxide or a semi-conductor prior to applying an adhesion promoter of the present invention significantly enhances the adhesion strength of the plastics material bonded to the surface of a metal, a metal oxide or a semi-conductor. In a preferred embodiment, the method of the invention comprises the further step of ii. bonding the surface of a metal, a metal oxide or a semi-conductor treated according to step i. to a plastics materials surface.

Step ii. is performed after step i. or after step ia.

Preferably the bonding is a lamination process. The lamination process is performed by pressing the surface of a metal, a metal oxide or a semi-conductor and the plastics materials surface together. The lamination process is performed at a specific pressure and temperature.

In a further preferred embodiment the plastics material is a prepreg and the lamination process is performed at a pressure of between 5 - 60 bar at a temperature of between 100 and 350 ^< C, preferably 100 and 300 ^< C and more preferably 150 and 200 ^< C. A laminating cycle ranges from 30 to 120 minutes, preferably from 60 to 100 minutes. The lamination may be performed under vacuum conditions. The lamination of a prepreg to a metal surface is one step in the manufacturing of a circuit carrier, e.g. a PCB.

In a further preferred embodiment the plastics material is a resist, in particular a dryfilm, and the lamination process is performed at a pressure of between 1 - 5 bar at a temperature of between 100 and 150°C. Dry film resists are laminated onto the surface of a metal or a metal oxide by means of a hot roller with a conveyor speed of 1 m/minute or higher. The lamination of a resist to a metal surface is one step in the production of metal circuitry in and on a circuit carrier, e.g. a PCB.

In particular, the lamination process is suited for prepregs or dry film resists as plastics materials. The lamination process is further suited for surfaces of a metal or a metal oxide.

A circuit carrier, e.g. a PCB, may be a single-side board consisting of a single layer of prepreg and a single layer of metal bonded to each other. It may be a double-side board consisting of a single layer of prepreg the two sides of which are bonded to a metal layer each. It may be a multi-layer board sandwiching several metal layers (circuitry layers) and prepregs together in alternating sequence. The outer sides of a multilayer board also exhibit a metal layer. The metal circuitry on the circuit carrier may be prepared from a metal foil layer by conventional techniques such as by a photoimage technique of a photosensitive resist film followed by etching of the unprotected areas of metal on the circuit carrier to form electrically conductive paths or electrically conductive patterns. Methods of forming circuit metal structures on a circuit carrier may be a semi-additive process sequence or a panel plating process sequence. The metal is preferably copper.

For the manufacture of a circuit carrier, e.g. a PCB,

(a) a circuit carrier is generally used which comprises a metal coating on at least one side thereof and which is further provided with through-holes which serve to electrically contact individual circuit planes within the carrier;

(b) this circuit carrier is first metal coated on the outer sides and on the hole walls, in general with electroless metal plating only or with electroless and subsequently electrolytic metal plating or with electrolytic metal plating only.

Further processing depends on the methods involved:

In the panel plating process variation, in general, a metal clad material is used, which is drilled to form the through-holes and is then electrolytic metal-plated to provide electrical conductivity in the through-holes. The panel plating method further comprises the following general method steps:

(c) contacting the surface of the metal layer formed in method step (b) with the solution containing nanometer-sized particles having at least one attachment group bearing a functional chemical group suitable for binding to the metal surface, thereby forming a layer of said nanometer-sized particles on at least a portion of the metal surface;

(d) applying a resist to the metal surface and imaging the resist, thereby forming resist voids;

(e) removing metal which is exposed in the resist voids; and

(f) stripping the resist from the surface of the metal surface; the resist is preferably a photo imageable resist. In the semi-additive plating process variation, in general, a circuit carrier is used, which is provided on the outer sides with a resist and which, after having been drilled to form the through-holes, is metal-plated to form a thin metal layer on the outer sides. In this case, a conventional printed circuit board may be used for example which is additionally provided with a resin coating on the outer sides to form the resist. The semiadditive plating method further comprises the following general method steps:

(c) contacting the surface of the metal layer formed in method step (b) on the outer sides of the circuit carrier with the solution containing nanometer-sized particles having at least one attachment group bearing a functional chemical group suitable for binding to the metal surface, thereby forming a layer of said nanometer-sized particles on at least a portion of the metal surface;

(d) applying a resist to the metal surface and imaging the resist, thereby forming resist voids;

(e) depositing metal in the resist voids;

(f) stripping the resist from the metal surface; and

(g) etching off the metal in those regions which have previously been covered by the resist; the resist is preferably a photo imageable resist.

The circuit carrier with the metal surfaces can be treated in conventional dipping systems. In treating the printed circuit boards, it is particularly good to use so-called continuous systems. The boards are guided along a horizontal transport path through the system. They are brought into contact with the treatment solutions by guiding them through a liquid bed between squeezing rollers located at the beginning and end of the treatment path, and/or bringing them into contact with the treatment liquid using suitable nozzles such as spray or surge nozzles. The printed circuit boards can be held in a horizontal or vertical position or at any other angle.

The method utilizing the nanometer-sized particles having at least one attachment group bearing a functional chemical group suitable for binding to the surface of a metal, a metal oxide or a semi-conductor has turned out to be effective in preparing a surface of a metal, a metal oxide or a semi-conductor for achieving firm adherence of a plastics material being applied thereon. In particular, the method of the invention is effective in treating a surface of a metal, a metal oxide or a semi-conductor for achieving permanent firm adherence of a prepreg suited for manufacturing of circuit carriers, i.a. PCBs. Further, the method of the invention is effective in treating a surface of a metal, a metal oxide or a semi-conductor for achieving permanent firm adherence of a resist suited for manufacturing of circuit carriers, i.a. PCBs. Further, the method of the invention is effective in treating a surface of a metal, a metal oxide or a semi-conductor for achieving temporary firm adherence of a resist suited for manufacturing of circuit carriers, i.a. PCBs. Firm adherence has been proved by a peel strength test according to standard ASTM D6862 90 °. Firm adherence has further been proved by visually inspecting consistency of a dot pattern of a resist laminated on a copper surface and exposed and developed. Both adherence tests are further described in the Examples. Consistency and adherence have been proved excellent.

The present invention also relates to surfaces of a metal, a metal oxide or a semiconductor having a layer of nanometer-sized particles as described above and a plastics material thereon. The present invention also relates to circuit carriers having a layer of nanometer-sized particles as described above.

The present invention further relates to surfaces of a metal, a metal oxide or a semiconductor obtainable by the methods as described above. The present invention also relates to circuit carriers obtainable by the methods as described above.

Examples

The present invention is further illustrated by the following non-limiting examples. Example 1

Silica nanoparticle colloids were prepared according the Stober process as described in Journal of Colloid and Interface Science 26, 62 - 69 (1968) by using TEOS (Tetrae- thylorthosilicate) as the precursor reacted in an ethanol and water mixture. NH ₄ OH (25%) solution was used as the catalyst to accelerate the hydrolysis and condensation reaction. 44 ml/l of TEOS was added to a solution of 2 ml/l H ₂ 0, 10m l/l NH ₄ OH and 944 ml/l Ethanol. The solution was stirred for 15 hours at room temperature to obtain highly dispersed colloidal silica particles. The silica particles were washed with ethanol. Afterwards the silica particles were stored in ethanol or in a dried condition or they were used immediately for functionalization. Higher volumes of ammonium hydroxide solution were used to obtain silica colloids with bigger particle size.

Example 2

The surface of the nanometer-sized silica colloids prepared in Example 1 was next functionalized with an alkyl amino group. In order to perform this functionalization 2 ml of 3-aminopropyl triethoxysilane (APTS) was added to 50 ml of prepared colloidal silica solution (2 g of silica particles in 50 ml ethanol). Before adding the amino silane, 57.2 ml/l of acetic acid was added into colloidal silica solution to maintain pH in a range from 3 to 6. The intermediate hydrolysis product of APTS, the corresponding silanol, has a higher stability in that pH range. This reaction mixture was stirred for 2 hours to obtain good mixing between the silica nanoparticles and APTS. Then the reaction mixture was refluxed for 3 hours at 80 'Ό. Refluxing the reaction mixture is needed in order to initiate the condensation between the silanol groups of the APTS hydrolysis product and the surface hydroxyl groups of the silica particles. Afterwards the functionalized silica particles were washed and stored in ethanol.

Example 3

The size distribution of the functionalized silica particles synthesized in Example 2 was determined by DLS.

Samples of the silica particles were prepared by further diluting the ethanol solution containing about 1 wt.% of functionalized silica nanoparticles with absolute ethanol (99 vol.%) to give a concentration that yielded a good signal intensity. Usually the end concentration was in the range 0.1 mg/l to 1 g/l nanoparticles. The prepared samples were filled into a measurement cuvette through a Sartorius celluloseacetate filter (pore size: 5μηι) in order to remove dust and/or artifacts.

The following data of ethanol was used in order to calculate the size distribution of the functionalized silica particles:

Refractive index of ethanol at 25 ^< €: 1 .36

Viscosity of ethanol at 25 ^< €: 1 .1 cP

Measurement conditions were set as listed in Table 1 below:

Table 1 : Conditions for DLS measurements

DLS measurement was performed on an instrument DelsaNano C from Beck- mannCoulter with measurement and instrument parameters set to:

Light detection angle: 165°

Wavelength: 658 nm Cell Center: z= 6.3mm; x= 7.55mm

Reproducibility of measurements was reviewed for samples of silica particles synthesized using 10 ml/l and 20 ml/l ammonium hydroxide solution. The variation in intensity of laser light scattered from the particles were autocorrelated to give the corresponding intensity distribution and the average particle diameter and the polydispersity index were calculated according to ISO 22412:2008. The results are shown in Table 2.

Table 2: Average diameter and Polydispersity Index of synthesized and functionalized silica particle samples calculated according to ISO 22412:2008

The intensity distributions were converted to number based particle size distributions and the values di ₀ , d ₅ o and d ₉₀ were calculated on the basis of the number based distributions. The value d ₅₀ has been defined above. The value di ₀ means that 10 % of the particles have a diameter below the di ₀ value and d ₉₀ means that 90 % of the particles have a diameter below the d ₉₀ value. The d values resulting for silica particle samples synthesized using different volumes of ammonium hydroxide solution are summarized in Table 3.

The resulting particle size distributions for different volumes of ammonium hydroxide solution used during synthesis (according to Examples 1 and 2) of the silica particles as determined by DLS are shown in Figure 2. Table 3: Size distributions of synthesized and functionalized silica particle samples.

Example 4

Characterization of the surface functionalities of the silica particles by FTIR-ATR spectroscopy

The surface functionalities of silica nanoparticles generated in Example 2 were analysed before and after surface functionalization by FTIR-ATR spectroscopy.

The PerkinElmer Spectrum™ 100 FTIR-ATR spectrometer was used to analyse the surface functionalized silica nanoparticles. 100 μΙ solution containing 40 mg/ml silica particles (sample 2) were applied directly onto the ATR measurement unit (germanium crystal).

The samples of silica particles were analysed within a wavelength number range from 4000 cm ^"1 to 500 cm ^"1 with 4 cm ^"1 resolution for 16 times for a more reliable result. Semi-quantitative analysis was provided by using this instrument.

The result is shown in Figure 3. While the non functionalized silica particles of Example 1 (named Si Colloid in Figure 3) show no signal at a wavelength number range characteristic for N-H vibrations, the silica particles of Example 2 (named NH2 Modified Si Colloid in Figure 3) clearly exhibit the deformation vibration of N-H at a wavelength number of 1560 cm ^"1 proving the successful amine functionalization of the silica nanoparticles.

Example 5

Characterization of the surface functionalities of the silica particles by H-NMR spectroscopy

In addition, the surface functionalities of silica nanoparticles generated in Example 2 were analysed by H-NMR spectroscopy before and after surface functionalization.

Samples of non functionalized silica particles of Example 1 (sample 2) and of silica particles functionalized with APTS of Example 2 (sample 2) were prepared.

For preparing the samples at first water was added to silica particles. Afterwards the silica particle suspensions in water were lyophilized and resuspended in CD ₃ OD or a CD ₃ OD/D ₂ 0 mixture. Non functionalized silica nanoparticles could not be resuspended completely. So filtration was necessary in order to remove insoluble aggregates of particles. Non-functionalized and functionalized silica particles were resuspended in CD ₃ OD or a CD ₃ OD/D ₂ O mixture giving 1 ml each of a suspension containing 40 mg/ml silica particles. These samples were introduced directly to the NMR measurement column at room temperature. H-NMR spectra were measured on a Bruker NMR spectrometer at 250 MHz at room temperature (23 ^Q C).

The result of NMR spectroscopy is shown in Figure 4. Figure 4A presents the H-NMR spectrum of non-functionalized silica particles. There are no signals for protons belonging to a propylene group (-CH ₂ -CH ₂ -CH ₂ -). Signals marked with an A (quartet at 3.64 ppm) and B (triplett at 1 .19) are caused by ethyl groups originating from TEOS. Figure 4B shows a spectrum of silica particles functionalized with APTS (3-aminopropyl trieth- oxysilane). The additional signals with chemical shifts of 0.78 ppm; 1 .80 ppm and 2.95 ppm originate from propylene groups. Thus, 3-aminopropyl groups were bound to the surface of the silica particles by reacting the particles with APTS. Example 6

Preparation and characterization of mercapto alkyl functionalized silica particles

The surface of the nanometer-sized silica colloids prepared in Example 1 was functionalized with a mercapto alkyl group. In order to perform this functionalization 0.34 M of 3-mercaptopropyltriethoxysilane was slowly added into prepared colloidal silica solution with a constant flow rate F = 3 ml/min. The reaction conditions were kept at R = 300 rpm and T = 20 'C. After 1 h, the temperature rose slowly with a rate ΔΤ = 5 K/min from T = 20 °C to T = 75 °C and the reaction mixture was refluxed for 3 hours. 1 .4 M of acetic acid was added into the suspension solution of 3-Mercaptopropyl functionalized silica nanoparticles after cooling down to room temperature (20 'C).

The size distribution of the mercapto propyl functionalized silica particles was determined by DLS as described in Example 3. The results are summarized in Table 4. Elemental analyses (CHNS) were performed on an Elementar Vario EL Cube and results are presented in Table 5.

Table 4: Size distribution of the mercapto propyl functionalized silica particles

Example 7

Amino propyl functionalized silica nanoparticles applied on a tin foil and bonding of a FR4 plastics material (fiberglass impregnated with epoxy resin).

Aminopropyl functionalized silica nanoparticles of Example 2, sample 2 were used as adhesion promoter between tin and a plastics material (FR4). A sample of tin foil without aminopropyl functionalized silica treatment was prepared as comparison (sample 5).

Sample preparation:

Firstly, tin foils were cut in dimension of 75 mm in width and 150 mm in length. The foil's surface was activated by using Atotech secure activator solution before adhesion promoter treatment. Lamination was done by pressing the FR4 on the adhesion promoter treated tin surface. Water rinsing and drying step was implemented in between secure activator and adhesion promoter. Water rinsing and annealing step after adhesion promoter treatment was varied in order to assess its influence on adhesion strength. The process sequence is summarized in Table 6.

Table 6: Process sequence

Adhesion evaluation:

Standard ASTM D6862 90° peel strength test was conducted for adhesion evaluation. The tin foils treated with adhesion promoter and laminated with FR4 sheet were cut into long strips with the size of 1 cm in width. Small part of the tin foil was removed intentionally from the epoxy polymer surface of the FR4 sheet and banded upward for fixing to peel test compartment. All measurements were carried out at a peeling speed of 45 mm/min. Each adhesion strength value is the average of at least two measurements for every sample. Normally the results from both measurements should not vary more than 0.5 N/cm. The resulting adhesion strengths are presented in Table 7.

Table 7: Adhesion strength of a FR4 plastics material bonded to a tin foil treated with amino propyl functionalized silica nanoparticles as adhesion promoter

Example 8

Mercapto propyl functionalized silica nanoparticles applied on a copper foil and bonding of a FR4 plastics material.

Mercapto propyl functionalized silica nanoparticles of Example 6 were used as adhesion promoter between copper and a FR4 plastics material. A sample of copper foil without mercapto propyl functionalized silica treatment was prepared as comparison (sample 7).

Sample preparation:

Firstly, copper foils were cut in dimension of 75 mm in width and 150 mm in length. The foil's surface was cleaned by using Atotech CupraEtch PT and 1 M sulfuric acid before adhesion promoter treatment. Lamination was done by pressing a FR4 sheet on the adhesion promoter treated copper surface. A water rinsing step was implemented after cleaning. The copper foil was dried prior to adhesion promoter treatment. The process sequence is summarized in Table 8.

Table 8: Process sequence

Adhesion evaluation:

Adhesion strength was determined as described in Example 7 and the resulting values are presented in Table 9.

Table 9: Adhesion strength of a FR4 plastics material bonded to a copper foil treated with mercapto propyl functionalized silica nanoparticles as adhesion promoter

Example 9

Mercapto propyl functionalized silica nanoparticles applied on a copper panel and bonding of a photo resist

Mercapto propyl functionalized silica nanoparticles of Example 6 were used as adhesion promoter between copper panels and a photo resist.

7,5 cm x 15 cm large copper panels were prepared from the following material:

Type A) Copper Clad (35 μηι copper) laminated on FR4 dielectric (abbreviated CCL),

Type B) GX92 dielectric panels provided with an electroless copper layer of about 1 μηι thickness (Printoganth® PV, Atotech Deutschland, DE) (abbreviated e-less).

The following photo resists were used for lamination onto copper panels treated with different adhesion enhancers:

1 . Hitachi RY 5319

2. Hitachi RY 3525

3. DuPont FX 925

The copper panels were first cleaned and rinsed and afterwards treated either with the adhesion promoter of the invention or with a conventional adhesion enhancer for comparison purposes.

1 . Mercapto propyl functionalized silica nanoparticles of Example 6, 2.5 % in etha- nol (abbreviated MNP, according to invention)

2. Sulfuric acid 5 % (abbreviated POR, comparative)

Afterwards, these copper panels were laminated with one of the photo resists (dry film, 19-25 μηι thickness) using a hot-roll laminator. A glass artwork for imaging was used having a dot pattern of dots with diameters varying between 3 μηι and 23 μηι and a space between the dots of 23 μηι. Then, the dry film was exposed using a UV exposure unit (EXM-1201 ). Unexposed film was removed with standard sodium carbonate developer solution, thereby removing the film except on the dot features.

After developing, rinsing and drying, the test panels were evaluated by counting the number of completely intact dots for every diameter. If all dots of a specific diameter remained completely intact during development, the respective dot size on a panel was assigned a value of 100 %.

The process sequence for treating the copper panels is summarized in Table 10. Table 10: Process sequence for treating the copper panels

The adhesion strengths resulting from a specific adhesion enhancer for each panel type and photo resist are shown in Figures 5 - 9 and in Table 1 1 . The figures and the adhesion strength values show that in particular fine structures of resist, like dots with small diameters, have a significantly increased adhesion strength to metal surfaces treated with the nanometer-sized particles of the invention in comparison to metal surfaces treated with a conventional adhesion enhancer.

Table 1 1 : Adhesion strength values resulting from a specific adhesion enhancer for each panel type and photo resist

"— " means: not measured Example 10

A chemical derivatization method was used to determine the number of functional groups on the surface of silica nanoparticles which were prepared as described in Example 2 (called amino functionalized silica nanoparticles of Example 10). The amino functionalized silica nanoparticles prepared in Example 2 were analysed in the same way (called amino functionalized silica nanoparticles of Example 2). The number of functional groups corresponds to the number of attachment groups. In this method, the functionalized silica nanoparticles were purified before characterisation to remove all precursors, especially those which can also react with the indicator molecule. After the reaction of the functional groups with the indicator, a new specific absorption turns up, which can be used to quantify the number of functional groups in the solution using a calibration curve. This result together with the total dry mass and the particle size allows to quantify the number of functional groups per nanometer-sized particle area. For amino functionalised nanoparticles, the indicator molecule was salicylaldehyde.

Salicylaldehyde was used as the indicator molecule as it easily reacts with the primary amine on the functionalized silica nanoparticles. The resulting adducts suspension turns bright yellow and has a strong maximum absorbance at around 404 nm. A calibration curve was generated by using a 3-aminopropyltriethoxysilane (APTES) as the model molecule. The absorbance at a wavelength of 404 nm was measured as a function of APTES concentration.

Measurement Procedure:

10 μΙ_ of the silica nanoparticle suspension (aminopropyl functionalized silica) and 100 μΙ_ of 1 M salicylaldehyde (MW = 122.12) were placed in absolute ethanol in a 10 ml_ volumetric flask and the flask filled with ethanol. The flask was shaken vigorously and let stand for half an hour. Absorbance of the solution was measured at a wavelength of 404 nm.

Measurement Results:

A ₄₀₄ = 0.359 (from UV-vis absorption measurement)

Particle size/diameter = 52 nm (from DLS measurement) Calculation of the number of APTES molecules

Using a calibration curve the data of which are presented in Table 12, the concentration of APTES in the solution was:

\ APTES] = ^{Abs 404nm} ^-°- ⁰ⁿⁱ

1180.2

0.0359-0.0117

[APTES] = = 2.943 *10 ^~4

1180.2

Dilution factors: The solution was diluted by 1000 times of the original concentration. Thus, the original APTES concentration was:

[APTES ] _{ori inal} = 2.943*10^ *1/10 ^~3 = 0.2943

Considering 1 L of solution, using Avogadro's number, the number of APTES molecules was: number _of _ APTES _ molecules = 0.2943 * N _A number _of _ APTES _ molecules = 0.2943 * (6.022 * 10 ²³ ) = 1.7721 * 10 ²³

Calculation of total surface area of silica nanoparticles

With the assumption that the nanoparticles were a perfectly spherical with a diameter of 52 nm and a silica density (p = 2.2 g/cm ³ ), the mass of ONE nanoparticle can be approximated to be:

4 * * 3

m sphere = ^~ π* * Τ {X ΪΠ OT) fn _sphere = * 2.2 * (26 * 10 ^"7 ) ³ = 1.62 * 1 (Γ ¹⁶ #

The number of nanoparticles, based on 1 L of nanoparticle suspension solution, the total mass (75 g) was divided by the mass of a single nanoparticle: m

number _of _ NP = —

m number of NP = ^15g = 4.63 * 10 ¹⁷

^{~ ~} 1.62 * 10 ¹⁶

The surface area of ONE nanoparticle was calculated with the above-mentioned considerations regarding its geometric shape to be:

Aphere = ⁴ ^

A _phere = 4^(26) ² = 8494« ² Thus, the total surface area of the nanoparticles was:

Aotai = number _ of _ NP * A _here = 4.63 * 10 ¹⁷ * 8494 = 3.9327 * 10 ²¹ wn ²

Calculation of amine group concentration

Thus, the total number of APTES molecules per nm ² was: number of APTES molecules 1.7721 * 10 ²³

~ ^~ = = = 45

A _Total {nm ² ) 3.9327 * 10 ²¹

The total number of APTES molecules and thus attachment groups per nm ² was 45.

Results:

Amino functionalized silica nanoparticles of Example 10: 45 attachment groups / nm ² of particle surface area Amino functionalized silica nanoparticles of Example 2: 35 attachment groups / nm ² of particle surface area

Calibration Curve

A number of APTES calibration solutions were prepared by reacting ethanol solutions having specific APTES concentrations (see Table 12) with salicylaldehyde and the absorption of the formed yellow adduct was measured at a wavelength of 404 nm.

Table 12: Concentration and absorption of APTES calibration solutions.

The characteristic absorbance of the adduct at 404 nm was plotted against the APTES concentration getting a linear fit with the following equation:

Abs(404nm) - 0.0m

[APTES] =

1 180.2

The correlation coefficient was 0.99.

Example 11 For determining the number of attachment groups of mercapto functionalized silica nanoparticles a method similar to the one of example 10 was used. The mercapto functionalized silica nanoparticles were prepared according to Example 6 (called mercapto functionalized silica nanoparticles of Example 1 1 ). The mercapto functionalized silica nanoparticles prepared in Example 6 were analysed in the same way (called mercapto functionalized silica nanoparticles of Example 6). The number of attachment groups of mercaptopropyl functionalized silica nanoparticles was analyzed by the Ellman's reaction. In this method, 5,5-dithio-bis (2-nitrobenzoic acid) also abbreviated as DTNB in a phosphate buffer solution (pH 8, 0.7mM) was used as the indicator molecule as it easily reacts with the mercapto group on the functionalized silica nanoparticles. The formation of the yellow dianion of 5-thio-2-nitrobenzoic acid (TNB) is measured by UV-Vis, with the absorption peak at 412 nm.

Measurement Procedure:

10 μΙ_ of the mercaptopropyl functionalized silica and 1 mL of 0.7 mM DTNB were placed in a 10 mL volumetric flask and the flask was filled with pH 8.0 phosphate buffer solution. The flask was shaken vigorously and let stand for half an hour. The absorb- ance of the solution was measured at a wavelength of 412 nm.

Measurement Results

A412 = 0.279 (from UV-vis absorption measurement)

Particle size/diameter = 50 nm (from DLS measurement)

Calculation of the number of mercaptopropyltriethoxysilane (MPTES) concentration Using a calibration curve, the concentration of mercapto group in the solution was:

Abs(420nm) - 0.0106

[ ^{tMPTEs i} - 0.0138

. 0.3 - 0.0106 ^ „,

[ ^C ™ ^{] =} 0.0138 ^{= 21//} Dilution factors: The solution was diluted by a factor 1000 of the original concentration. Thus, the original MPTES concentration was:

[MPTES} = 21 * 10 ^~3 mM * 1/10 ³ = 2lmM

Considering 1 L of solution, using Avogadro's number (N _A ), the number of mercapto- propyl triethoxysilane (MPTES) molecules was: number _ of _MPTES _ molecules = 0.021 * N _A number _ of _ MPTES _ molecules = 0.021 * (6.022 * 10 ²³ ) = 1.26462 * 10 ²² Calculation of total surface area of silica nanoparticles

With the assumption that the nanoparticles were perfectly spherical with a diameter of 50 nm and a silica density (p = 2.2 g/cm ³ ), the mass of ONE nanoparticle could be approximated to be:

m sphere

The number of nanoparticles, based on 1 L of nanoparticle suspension solution, the total mass (75 g) was divided by the mass of a single nanoparticle: m

number _of _ NP = —

sphere

ISs

number of NP = ≥— - = 4.63 * 10

1.62 * 10

The surface area of ONE nanoparticle was calculated with the above-mentioned considerations regarding its geometric shape to be:

^ A-sphere = Δ ^ ^/L ' A _sphere = 4π(26) ² = 8494 m ²

Thus, the total surface area of the nanoparticles was: = number _ of _ NP * A _sphere = 4.63* 10 ¹⁷ * 8494 = 3.9327 * 10 ²¹ nm ²

Calculation of mercapto group concentration

Thus, the total number of mercapto group per nm ² was: number _of _MPTES _ molecules _ 1.26462 *10 ²² _

, _a ^m2 ) ^~ 3.9327 *10 ²¹

The total number of mercapto group and thus attachment groups per nm ² was 3.

Results:

Mercapto functionalized silica nanoparticles of Example 1 1 : 3 attachment groups / nm ² of particle surface area

Mercapto functionalized silica nanoparticles of Example 6: 4 attachment groups / nm ² of particle surface area

Calibration Curve

A number of calibration solutions were prepared by reacting solutions having specific glutathion concentrations (see Table 13) with DTNB and the absorption of the formed yellow adduct was measured at a wavelength of 420 nm. Solvent was an aqueous phosphate buffer, pH 8. DTNB had the concentration of 0.7 mM in aqueous phosphate buffer of pH 8.

Table 13: Concentration and absorption of glutathion calibration solutions

Stock Gluthation 12 nm Solution cone [μΜ]

1 0 0.004202

2 8.13 0.124923

3 16.25 0.23899

4 24.38 0.35022

5 32.5 0.450778

6 65 0.917841

7 97.5 1 .349216

The characteristic absorbance of the adduct at 412 nm was plotted against the gluta- thion concentration and a linear fitting was obtained with the following equation:

Abs(420nm) + 0.0106

gluthation 0 0138

The correlation coefficient was 0.99.

Instrumentation:

UV/Visible spectrum was obtained using a Perkin Elmer Lambda 25 double beam operation in conjunction with the software Perkin Elmer UV WinLab.