USE OF NICKEL AND MCKEL-CONTAINING ALLOYS AS

CONDUCTIVE FILLERS- IN ADHESIVE FORMULATIONS:

FIELD OF THE INVENTION

[1] The present invention relates to conductive adhesives and method for the preparation thereof. In another aspect, the invention relates to conductive inks and methods for the preparation thereof. In yet another aspect, the Invention relates to die attach films and methods tor the preparation thereof. In still another aspect, the invention relates to die attac pastes and methods fo the preparation thereof. In a further aspect, the invention: relates to assemblies comprising a first and a second article adhered to one another wit a conductive adhesive according to the presen t invention, and methods for the preparation thereof.

BACKGROUND OF THE INVENTION

[2] While silver and copper are widely used in conductive adhesives, there are potential problems with their use. For example, while silver is a good conductor, it is expensive.

Similarly, while copper is also a good conductor, it corrodes easily. I addition, both silver and coppe are expensive.

[3:] Accordingly, there: is a need in the art for conductive materials which provide

■conductivity levels of the same magnitude as provided by silver, while at the same time being relatively non-corrosive, stable to oxidation, and highly cost competitive with silver-based conductive formulations,

SUMMARY OF TEE INVENTION

[41 hi accordance with the present invention, there a : provided novel conducti ve adhesives and methods for the preparation thereof hi another aspect, the present invention provides novel conductive inks and methods for the preparation thereof. In yet another aspect the present invention provides novel die attach films and methods for the preparation thereof. In still another aspect, the present invention provides novel die attach pastes and methods: for the preparation thereof. In a further aspect the present invention provides assemblies comprising a first and a second article adhered to one another with a conductive adhesive according to the present invention, and methods for the preparation thereof. DETAILED DESCRIPTION OF THE INVENTION

[5| In accordance with the present invention, there are provided electrically conductive adhesive formulations, said formulations comprising: about 5 up to about 50 wt % of an organic matrix,

about 45 u to about 95 wt % of a particulated. filler, wherein:

about 5 up to about 100 wt % of said particulated filler is particulated nickel or a particulated nickel-alloy, and

0 up to about 95 wt % of said particulated filler is particulated, conductive noiMiiekei -containing filler,

optionally a curing agent, which, when presexit, is present in the range of about 0.1 up to about 20 wt %„ and .

optionally a reactive and/or ^■ non-reactive organic diluent therefor, wherein said formulation, upon curing thereof, has a volume resistivity in the range of about 10 ^"5 up to about ! 0 Ohm cm.

[6] Formulations according to the invention can be further characterized by one or more of the following:

- the volume resistivity of said formulation falls in the range of about 10 ^"4 up to about 10

Ohm cm; in some embodiments, the volume resisti vity of said formulation falls in the range of about ίθ ^"3 up to about 10· Ohm cm; in ..some .embodiments, the volume resistivity of said fomiuiation falls in the range of about lO ^"2 up to about 10 Ohm cm;

- said formulatioa is such that the effect of corrosion on the electrical properties of the particulated filler is minimal, and

- the coefficient of thermal, expansion (CTE) of said formulation is highly compatible with silicon wafers to which it may be applied.

[7] In accordance with another aspect of the present invention, there are provided assemblies comprising a first article permanentl adhered to a second article by a cured aliquot of the adhesive formula tion described herein.

Organic matrices [8] Organic matrices contemplated for use herein include at least one thermosetting resin or thermoplastic resin component, not including any organic solvent that may be employed. The thermosetting resin or thermoplastic resin componerit(s) are provided in the compositions described herein to improve: one or more performance properties suc as, for example, film quality, tackiness, wetting ability, flexibility, work life, high temperature adhesion, resin- filler compatibility, and/or curability of adhesive layers (e.g., films) prepared from, the compositions. In addition, the thermosetting resin or thennop!astic resin component(s) are provided in the compositions described herein to improve one or more performance properties such as, for example, rheo logy, dispensability, work life, and curability of adhesive layers (e.g., pastes) prepared from invention compositions.

[9] The thermosetting resin or thermoplastic resin components) can be any resin capable of imparting one or more of the above-listed properties to the compositions, including, but not limited to an acetal, an acrylic monomer, oligomer, or polymer, an acrylonitriie-butadiene- styrene (ABS) polymer or copolymer or a polycarbonate/ABS alloy, an alkyd, a butadiene, a styrene-butadiene, a cellulosic, a coumarone-mdene, a cyanate ester, diallyl phthalaie (DAP), an epoxy monomer, oligomer, or polymer, a flexible epoxy or polymer with epoxy functional groups, a fiuoropolymer, a melamine- formaldehyde, a neoprene, a nitrite resin, a novolac, nylon, a petroleum resin, a phenolic, a polyamide-imide, a polyarylate and polyarylate ether sulfone or ketone, a polybutylene, a polycarbonate, a polyester and co-polyestercarbonate, a polyetherester, a polyethylene, a polyimide, a maieimide, a nadimicle, an itaconamide, a polyketone, a polyolefin, a polyphenylene oxide, a sulfide, an ether, a polypropylene and polypropylene-EPDM blend, a polystyrene, a polyurea, a polyurethane, a vinyl polymer _* rubbers, a silicone polymer, a siloxane polymer, a styrene aerylonitriie, a styrene butadiene latex and other styrene copolymers, a sulfone polymer, a thermoplastic polyester (Saturated), a phthalaie, an unsaturated polyester, a urea-formaldehyde,, a polyacrylamide, a olyg!yeol, a polyacrylie acid, a. ^■ polyethylene glycol), an inherently conductive polymer, a fiuoropolymer, and the like, as well as combinations of any two or more thereof.

[10] Maleimides, nadnrtides, or itaconamides contemplated for use herein have the structure:

respectively, wherein:

m is 1-15,

is 0-15,

each R ^" is independently selected from hydrogen or .lower alkyl (such as C.1-5), and J is a monovalent or a polyvalent radicai comprising organic or organosiloxane radicals, and

combinations of any two or more thereof.

[11 j In certain embodiments, J is a monovalent or polyvalent radical selected from:

- hydrocarbyl or substituted hydrocarbyl species typical ly having in the range of about 6 up to about 500 carbon atoms, where the hydrocarbyl species is selected from alkyl, aikenyl, alkynyl, cycloalkyl, eyeloalkenyl, aryi, alkyiaryl, arylaikyL aryalkenyl, alkenylaryl, arylalkynyl or alkynylaryl, provided, however, that X can be aryi only when X comprises a combination of two or more d ifferent species;

- hydroearbylene or substituted hydroearbylene species typically having in the range of about 6 up to about 500 carbon atoms, where the hydroearbylene species are selected from alkylene, alkenylene, alkynyl ene, cycloaikylene, cycloalkenylene, arylene, aikylarylene, arylalkylene, aryialkenylene, alkenylarylene, arylalkynylene or alkynylaryiene,

- heterocyclic or substituted heterocyclic species typically having in the range of about 6 up to about 500 carbon atoms,

- polysiioxane, or

- poiysiio ane-pofyiirethajie block copolymers, as well as

combinations of one or more of the above with a linker selected from covalent bond, -0-, -S-, - NR-, ~NR-C(0 , -NR-C(0>0-, -NR-C.(0)-NR-, -S-C(0 , -S-C(0)-0- _> -S-C(0)-NR~, -0-S(0) ₂ - , -0-8(0)2-0-, ~0~S(Q) ₂ -NR-, -O-S(O)-, -0-S(0)-0-, -0-S(0)-NR- , -O-NR-C(O)-, -Q-NR-C(0)-0-, -O-NR-C(0)-NR-

, -NR~O-C(0>, -NR-0-C(0)-0-, -NR-0-C(0)-N ^" R-, -0-NR-C(S)-, -0-NR-C(S)-0-, -O-NR-C(S) -NR-, ~NR-0-C(S)- _s -NR-0-C(S)-0~, -NR-0~C(S)-NR-, -0-C(S)-, -0-C(S)-0-, -0-C(S)-NR- _¾ - NR-C S)-, -NR-€(S)-0~, -NR-C(S)-NR~, -S-S(0) ₂ -, -S-S.(0) ₂ .0-, -:S-S(0) ₂ -NR-, -NR-O-S(O)- , ~NR-0~S(0)~CK -NR-0~S(0)~NR-, ~NR~0-S(0) ₂ -, -NR~0-S(G) ₂ -0-, ~NR-0-S(0)2.-NR~ , -O-NR-S(O)-, -0-NR-S(0)-0-, -0-NR-S(0)-NR-, -0-NR-S(0) ₂ -0-, -0-NR-S(0) ₂ -NR~ , -0~N.R-S(0) ₂ -, -0-P(0)R ₂ -, -S-P(0)R ₂ -, or -NR-PiO)R ₂ ^» ; where each R is independently hydrogen, aikyi or substituted alky! . 12 Exemplary maleimid.es, nadimides, or itaconamides contemplated for use herein include 4,4 -diphenylmethane bismaleimide. 4,4'-diiphenylether bismaleimide.

4.4'diiphenylsiilfo:ne. bismaleimide, phenylmethane maleimide, m-phenylene bisinaleiniide, 2,2'- bis.[4-(4-maleiinidoplienosy)phenyl]propane _; 3 _> 3'-dJmefliyi 5,5'-diethyl-4,4 -dipheay-meillane- bismaleimide, 4-methyl~l,3-phenyIene bismaleimide, l,6 ^, -bismaleimide-(2 _J 2,4-trimethyr)hexane ₅ 1 ,3-bis(3-maiehnidopl ^' ienoxy}beirzene, 1 ,3-bis(4-maieimidophenoxy)-benzer!:e, and the like.

[13] The one or more epoxy monomers, oligomers, o polymers contemplated for use herein, which are also referred to herein as epoxy resins, can include an epoxy having an aliphatic backbone, an aromatic backbone, a modified epoxy resin, or a mixture of these. In certain embodiments, the one or more epoxy monomers, oligomers, or polymers include a fiinctionalized epoxy monomer, oligomer, or polymer. The epoxy functionality in the epoxy resin is at least one. hi some embodiments, the epoxy resin is one (i.e., the epoxy resin is a mono-functional epoxy resin). In other embodiments, the epoxy resin contains at least two or more epoxy functional groups (e.g., 2, 3, 4, 5, or more).

{14] The epoxy resins contemplated for use in the practice of the present invention are not limited to resins having a particular molecular weight. Exemplary epoxy resins can _. have, a molecular weight in the range of about 50 or less up to about ί ,000,000. In certain

embodiments, epoxy resins contemplated, for use herein have a molecular weight in the range of about 200,000 up to about 900,000. In other embodiments, epoxy resins contemplated for use herein have a molecular weight in the. range of about .10,000 up to about 200,000. In still other embodiments, epoxy resins contemplated for use herein have a molecular weight in the range of about 1,00:0 up to about 10,000. In still other embodiments, epoxy resins contemplated, for use herein have a molecular weight i tire range of about 50 up to about 10,000.

[15] In some embodiments, the epoxy resins can be liquid epoxy resins or solid epoxy resins containing aromatic and/or aliphatic backbones, such as the diglycidyl ether of bisphenol F or the diglycidyl ether of bisphenol A. Optionally, the epoxy resin is a flexible epoxy. The flexible epoxy can have a chain length, of variable length (e.g., a short chain or a long chain), suc as a short-chain length or long-chain length polygiyeol diepoxide liquid resin. An exemplary short chain length polygiyeol diepoxide liquid resin includes D.E.E.. 736 and an exemplary long chain length polygiyeol diepoxide liquid resin includes D.E.R. 732, both commercially available from Dow Chemical Company (Midland. MI).

[16] Exemplary epoxies contemplated for use herein include liquid-type epoxy resins based on bisphenol A, solid-type epoxy resins based on bisphenol. A, liquid-type epoxy resins based on bisphenol F (e.g., Epielon EXA~835LV), multifunctional epox resins based on phenol-noyoiae resin,, dieyclopentadiene-type epoxy resins (e.g., Epielon HP-7200L), naphthalene-type epoxy resins, and the like, as well as mixtures of any two or more thereof.

|1.7] hi certain embodiments, epoxies contemplated for use herein hiciu.de diglycidyl ether of bisphenol A epoxy resin, of diglycidyl ether of bisphenol. F epoxy resin, epoxy novolac resins, epoxy cresol resins, and the like.

[18] In some embodiments, the epoxy resins can be toughened epoxy resins, such as epoxidized carboxyl-terminated butadiene-acrylo trile (CTBN) oligomers or polymers, epoxidized polybuiadiene iglycidylether oligomers or polymers, heterocyclic epoxy resins (e.g., isocyanate-modified epoxy resins), and the like.

[19] In certain embodiments, the epoxidized CTB oligomer or polymer is an epoxy- containing derivative of an oligomeric or polymeric precursor having the structure: iIO()C[(Bu)x(AC ) _y ] _m COOH wherein: each Bu is a butyl erte moiety (e.g., 1 ,2-butadie.nyi or 1,4-buiadienyl),

each ACN is an aer lonitrile moiety. the Bu units and the ACN uni ts can be arranged randomly or in blocks,

each of x and y are greater than zero, provided the total ofx + y - 1 ,

the ratio of x:y falls in th range of about 10: 1 - 1 : 10, and

m falls in the range of about 20 about 100.

[20] As readily recognized by those of skill n the art, epoxidized CTBN oiig

polymers can be made h a variety of ways, e.g., from (I) a carboxyl terminated

butadiene/acryionitrile copolymer, (2) an epoxy resin and (3) bisphenoi A:

Bisp eno!A Chain Extender Reactive Epoxy R=Ca?hoxyi Grot by reaction between the carboxylic acid group of CTBN and epoxies (via chain-extension

reactions), and the like.

[21] In some embodiments, the epoxy resin can include epoxidized CTBN oligomers or polymers made .from. (1 ) a carboxyl terminated butadiene/acrylonitTile copolymer, (2) an epox resin, and (3) bisphenoi A as described above; Hypro™ Epoxy-Functional Butadiene- Acry!onitrile Polymers (formerly Flycar© ETBN), and the like,

[22] I certain embodiments, the epoxy resin contemplated tor use herein includes a rubber or elastomer-modified epoxy. Rubber or elastomer-modified epoxies include epoxidized

derivatives of:

(a homopolymers or copolymers of conjugated dienes having a weight average

molecular weigh (M ) of 30,000 to 400,000 or higher as described in U.S. Pat. No. 4,020,036 (the entire contents of which are hereby incorporated by reference herein), in which conjugated dienes contain from 4-1 1 carbon atoms per molecule (such as 1,3 -butadiene, isoprene, and the like): (b) ^■ epibalohydrin hemopolymers, a copolymer of two or more epihalohydriii monomers, or a copolymer of an epibalohydrin monomer(s) with an oxide nionomer(s) having a number average molecular weight (M _n ) which varies from about 800 to about 50,000, as described. in U.S. Pat. No. 4,101 ,604 (the entire contents of which are hereby incorporated by reference herein);

(c) hydrocarbon polymers including ethylene propylene copolymers and copolymers of ethylene/propylene and at least one noncorrjugated diene, such as

ethylene/propyleB¾¾exadiene/horbornadieiie, as described in U.S. Pat. No. 4,161,471 ; or

(d) conjugated diene butyl elastomers, such as copolymers consisting of from §5 to 99.5% ^' by weight of a C ₄ -C5 olefin combined with about 0.5 to about 15% by weight of a conjugated muki-olefin having 4 to 1 carbon atoms, copolymers of.isobuty.ene· and. isoprene where a major portion of the isoprene units combined therein ha ve conj uga ted diene unsat uration (see, for example, U.S. Pat, No. 4,160,759; the entire contents of which are hereby mcoiporated by reference herein).

[23] in certain embodiments, the epoxy resin is an epoxidized polybu adiene diglycidylether oligomer or polymer,

[24] In :certain embodiments, epoxidized polybutadiene diglycidylether oligomers contemplated for use herein have the structure:

wherein:

1 and R ² are each independently PI or lower alkyl,

R ³ is H, saturated or unsaturated hydroearbyi, or epoxy,

at. least 1 epoxy-contaimng repeating unit set forth above, and at least one oiefinic repeating unit set forth above are present in each oligomer, and, when present, in the range of 1- 10 of each repeating unit is present, and

n falls in the range of 2 - 150. [25] In certain embodiments, an epoxidized poly-butadiene diglycidylether oligomer or polymer contemplated for use in the practice of the present invention has the structure:

wherein R is H, OH, lower alkyl. epoxy, ©xirane-substituted lower alkyl, aryl, a!karyl, and the l ike. Further examples of the epoxy resin contemplated for use herein include epoxies havin a flexible backbone. For example, the epoxy resin can include:

and the like.

[26] In some embodiments, additional epoxy materials may be included in invention formulations. When included in invention formolations, a wide variety of epoxy- functionalized resins are contemplated for use herein, e.g., epoxy resins based on hisphenol A (e.g., Epon Resin 834), epoxy resins based on bisphenol F (e.g., RSL-173 or JER YL980), multifunctional epoxy resins based on phenol-novoiac resin, dicyelopentadiene-type: epox resins (e.g., Epiclon HP-- 72O0L), naphthalene-type epoxy resins, and the like, as well as mixtures of any two or more thereof!

[27] Exemplary epoxy-functionalized resins contemplated for use herein include the diepoxide of the cycioaliphatic alcohol, hydrogeiiated bispiienol A (commercially available as Epalloy 5000), a Afunctional cycioaliphatic glycidyl ester of hexahydrophthallie anhydride (commercially available as Epalloy 5200), Epiclon EXA-835LV, Epiclon HP-7200L, and the like, as well as mixtures of any two or more thereof.

[28] Additional examples of conventional epoxy materials which are suitable for use as optional additional component of invention formulations include:

and the like.

[29] Exemplary epoxy- ftinctionalized resins contemplated for use herein incl ude the epoxidized CTBN rubbers 561 A, 24-440B, and BP -7 (commercially available from Henkel Corporation; Salisbury, NC & Rancho Dominguez, CA); diepoxide of the cycioaliphatic alcohol hydrogenated bisphenol A (commercially available as Epalloy $000); a difi ctional

cycioalipliatic glycidyl ester of hexahydrophtballic anhydride (commercially available as Epalloy 5200); E ^' RL 4299; CY-179; CY-I84; and the like, as well as mixtures of an two or more thereof

^' [30] Optionally, the epoxy resin can be a copolymer that has a backbone that is a.rmxture of mononreric units (i.e., a hybrid backbone). The epoxy resin can include straight or branched chain segments. In certain embodiments, the epoxy resin can be an epoxidized silicone monomer or oligomer. Optionally, the epoxy resin can be a flexible epoxy-silicone copolymer. Exemplary flexible epoxy-silicone copolymers contemplated for use herein include ALBIFLEX 296 and ALBIFLEX 348, both commercially available from Evonik industries (Germany).

[31] I some embodiments, one epoxy monomer,, oligomer, or polymer is present in the: composition. In certain embodiments, combinations of epoxy monomers, oligomers, or polymers are present in the composition. For example, two or more, three or more, four or more, five or more, or si or more epoxy monomers, oligomers, or polymers are present in the composition. Combinations of epoxy resins can be selected and used to achieve the desired properties fo films or pastes prepared from the compositions. For example, combinations of epoxy resins can be selected such that, films prepared from the compositions exhibit one or more of the following improved properties: film quality, tackiness, wetting ability, flexibility, w ^r ork life, high temperature adhesion, resin-filler compatibility, sintering capability, and the like.

Combinations of epoxy resins can be selected such that pastes prepared from the compositions exhibit one or more improved properties such as theology,, dispensability, work life, sintering capability, and the like.

[32:1 The one or more epoxy monomers, oligomers, or polymers can be present in the composition in an amount of up to about 50 percent by weight of the total solids content of the composition (i.e., the composition excluding ^' diluents). For example, the one or more epoxy monomers, oligomers, or polymers can be present in the composition in an amount of from about 5 percent by weight to about 50 percent by weight, from about 10 percent by weight to about 50 percent by weight, or from about 10 percent by weight to about 35 percent by weight. In some embodiments, the one or more epoxy monomers, oligomers, or polymers can be present in the composition in an amount of about 50 percent by weight or less, about 45 percent by weight or less, about 40 percent by weight or less, _, about 5 percent by weight or less, about 30 percent by weight or less, about 25 percent by weight or less, about 20 percent by weight or less, about 15

1.1 percent by weight or less, about 10 percent by weight or less, or about 5 percent by weight or less based on the weight of the total solids content of the composition,

[33] The compositions described herein can farther include an acrylic monomer, polymer, or oligomer. Acryiates contemplated for use in the practice of the present invention are well known in the art. See, for example, U S Pat. No. 5,717.034, the entire contents Of which are hereby incorporated by reference herein.

[34] The acrylic monomers, polymers, or oligomers contemplated for use in the practice of the present invention are not limited to a particular molecular weight Exemplary acrylic resins can have a molecular weight i the range of about 50 or less up to about 1 ,000,000. In some embodiments, acrylic polymers contemplated for use herein can have a molecular weight in the ^• range of about 100 up to about 10,000 and a ^' Tg in the range of about -40°C up to about 20°C, In certain embodiments, acrylic polymers contemplated for use herein have a molecular weight in the range of about 10,000 up to about 900,000 (e.g., about 100,000 up to about 900,000 or about 200,000 up to about 900,000) and a Tg in the range of abou -40°C up to about 20°C. Examples of acrylic copolymers for use in the compositions described herein include Teisan Resin SG-P3 and Teisan Resin SG-80H (both commercially available from Nagase Chemtex Corp. Japan). Optionally, the acrylic polymer or oligomer for use in tire compositions described herein can be degradable acrylic polymers or oligomers or epoxy--modified acrylic resins.

[35] The acrylic monomers, polymers, and/or oligomers can be present in the composition in an amount of up to about 50 percent by weight of the total soli ds content of the composition. Fo example, the acrylic monomers, copolymers, and/or oligomers can be present in the composition in an amount from about 5 percent by weight to about 50 percent by weight, or from about 10 percent by weight to about 5.0 percent by weight, or from about 10 percent by weight to about 35 percent by weight or from about 5 percent by weight to about 30 percent by weight, or from, about 5 percent by weight to about 20 percent by weight. In some embodiments, the acrylic monomers, copolymers, and/o oligomers are present in the composition in an amount of about 50 percent by weight or less, about 45 percent by weight or less, about 40 percent by weight or less, about 35 percent by weight or less, about 30 percent by weight or less, about 25 percent by weight or less, 20 percent by weight or less, about 15 percent by weight or less, about 10 percent by weight or less, or about 5: percent by weight or less based on the weight of the total solids content of the composition.

[36] Exemplar}-- (metlijacrylates contemplated for use herein include monofunctional (meih)acrylates, difunetional (mem)a.cryiates, trifunctional (mem)aerylates. polyfunctionai {rneth)acr lates. and the like, as well as mixtures of any two or more thereof.

[37] Additional thermosetting resin or thermoplastic resin components contemplated for use in the compositions described herein can include poiyurethanes, cyanate esters, polyvinyl alcohols, polyesters, polyureas, polyvinyl aeeta! resins, and phenoxy resins. In some embodiments, the compositions can include imide-eontaining monomers, oligomers, or polymers, such as maleimides, nadimides, _. itaconimides, bisma!eimides, or polyimides.

[38] ^' The: thermosetting resin or thermoplastic resin components, including the one or more epoxy monomers, polymers, or oligomers; the acrylic monomers, polymers, or oligomers,, the phenolics; the novalacs; the poiyurethanes; the cyanate esters; the polyvinyl alcohols; the polyesters; the polyureas; me polyvinyl ace al resins; the phenoxy resins; and/or the irnide- eontaimng monomers, polymers, or oligomers (e.g., the .maleimides, Msmaleimides, and polyimides) can be combined to form a binder. The binder can be solid, semi-solid, or liquid. Optionally, the binder has a decomposition temperature of less than 350 °C.

[39} Cyanate ester monomers contemplated for use herein contain two or more ring forming cyanate -Q-C≡N) groups which cyclotrimerize to form substituted triazme rings upon heating.

Fillers

[40] The compositions described herein also include one or more particulated, conductive fillers, wherein:

about 5 up to about 100 wt % of said particulated, conductive filler is

particulated nickel or a particulated nickel-alloy, and

0 up to about 95 wt % of said particulated, conductive filler is particulated, conducti ve non-nickel-containing filler.

[41] in some embodiments, the nickel or nickel-allo filler contemplated for use herein comprises substantially 100 wt % nickel; in some embodiments, the nickel or nickel-alloy filler contemplated for use herein comprises at least about 20 wt % nickel; in some embodiments, the nickel or nickel-allo filler comprises at least about 30 wt % nickel; in some embodiments, the nickel or nickel-alloy filler comprises in the range of about 30 up to about 50 w % nickel; in some embodiments, the nickel or nickel-alloy filler comprises about 36 wt % nickel (wherein said nickel or nickel-allo filler comprises about 64 wt % iron); in some embodiments, the nickel •or nickel-alloy filler comprises at least about 40 wt % nickel; in some embodiments, the nickel or nickel-alloy filler comprises in the range of about 40 up to about 50 wt % nickel; in some embodiments, the nickel or nickel-alloy filler comprises in the range of about 41-43 wt % nickel; in some embodiments, the nickel or nickel-alloy filler comprises about 42 wt % nickel (wherein said nickel or nickel-alloy filler comprises about 58 wt % iron); in some embodiments, the nickel or nickel-alloy filler comprises at least about 50 wt % nickel; in some embodiments, the nickel or nickel-alloy filler comprises in the range of about 57-59 wt % nickel; in some embodiments, the nickel or nickel-alloy filler comprises in the range of about 30 up to about 80 wt % nickel.

[42] In some embodiments, nickel or a nickel-alloy is present as the major conductive filler (i.e., at least 50 weight percent, at least 60 weight percent, at least 70 weight percent, at least 80 weight percent, or at least 90 weight percent) of the total cond uctive fillers present in the composition) along with one or more additional conductive fillers.

[43] hi some embodiments, the nickel or nickel-alloy filler comprises in the range of about 10 up to about 95 wt % of said particulated filler; in some embodiments, the nickel or nickel- alloy filler comprises in the range of about 20 up to about 85 wt % of said particulated filler; in some embodiments, the nickel or nickel-alloy filler comprises in the range of about 30 up to about 75 wt % of said particulated filler; in some embodiments, the nickel or nickel-alloy filler comprises in the range of about 40 u to about 60 wt % of said particulated filler.

[44] In some embodiments, the nickel or nickel-alloy filler contemplated for use herein is substantially silver free.

[45] in some embodiments, the nickel-alloy filler contemplated for use herein comprises nickel and iron, and, optionally, cobalt.

[46] In some embodiments, the particulated, conductive non-nickel-containing filler contemplated for use herein is Ag, Co. silver coated copper, silver coated glass, silver coated graphite, silver coated nickel, silver coated iron, silver coated nickel-iron alloy, silver coated ferrites, and the like, as well as mixtures of any two or more thereof.

[47] In some embodiments, the ratio of particulated nickel-containing filler to particulated conductive non-nickel-containing filler fails in the range of about 10:1 - 1 : 10. In some embodiments, the ratio of particulated nickel-containing filler to particulated conductive nort- nickef containing filler falls in the range of about 8 : 1 - 1 :8. In some embodiments, the ratio of particulated nickel-containing filler to. particulated conductive non-niekel-contaiiimg filler falls in the range of about 6: 1 - 1 :6.

[48] In some embodiments, the nickel or nickel-alloy filler contemplated for use herein has a partieie size in the range of about 0.1 up to about 100 μηι. In some embodiments, the nickel or nickel-allo filler contemplated for use herein has a particle size in the range of about 1 up to about 50 pm. In som embodiments, the nickel or nickel-alloy fille contemplated for use herein, has a particle size in the range of about 5 up to about i 5 pm.

[49] In some embodiments, the nickel or nickel-alloy filler contemplated for use herein is in the form of a powder or flake having a surface area in the range of about 0.01 up to about 10 nrVmg.

[50] In some embodiments, the nickel or nickel-alloy filler contemplated for use herein has a tap densi ty in the range of about 0.2 up to about 8 g/cm ³ .

[51] In some embodiments, the filler surface is treated to increase filler/resin compatibility. Such treatments include mechanical treating to increase filler/resm compatibility, chemical treatment to increase fiiler/resm compatibility, and the like.

[52] Exemplary mechanical treatments contemplated for use herein to increase filler/resin compatibility include plasma, treatment, and the like.

[S3] Exemplary chemical treatments contemplated for use herein to increase filler/resin compatibility include treating the filler surface with a saturated fatty acid, an unsaturated fatty acid, a. mixture of saturated and unsaturated fatty acid, a sorbitan ester, a fatty acid ester, an organosilane, and the like, or mixtures- of any two or more thereof.

L5 [54] The conductive filler can have a size suitable for use in the methods described herein and is not limited to any particular range. Exemplary conducti e fillers can have an average particle size ranging from about G.I μπι to about 20 μηι. In some embodiments, the conductive filler can have an average particle size ranging from about 1 , ιη to about 10 μηι. In other embodiments, the conductive filler can have an average particle size that ranges from about 1 μηι to about 3 μιη. f 55] The conductive filler is present in the composition in an amo unt of at least 65 percent by weight of the total solids content of the composition. For example, the conductive filler can be present in the composition in an amount of from about 65 percent by weight to about 95 percent by weight o from about 75 percent by weight to about 85: percent by weight. In some embodiments, the conductive filler can be present in the composition in an amount of at least about 65: percent by weight, at least: about 70 percent by weight, at least about 75 percent by weight, at least about 80 percent by weight, at least about 85 percent by weight or at least about 90 percent by weight of the total solids content of the composition.

[56] The: compositions described herein can optionally include one or more particulate fillers. The particulate filler can include, for example, silica, alumina, boron nitride, iron-based alloys, zirconium tungstate, or mixtures thereof. For example, the particulate filler can be a nickel/iron composition or a lithium aimninium silicate. Exemplary particulate fillers have a coefficient of thermal expansion (CTE) of 10: ppm/°C or lower (e.g., 5 ptn/°C or lower, 0 ppm/°C or lower, or -5 ppm/°€ or lower), in some embodiments, the particulate fillers can include the following materials: carbon nanotubes, β-eucrypiite, -Zr aOg, -ZrWiOg, Cd(CN)¾ ReCk, (HfIVlg)(W04)3, Sn¾. ₇ sQ» _? Blo.9sLao.o5Ni(¾, Invar (Fe-36N¾ Invar (Fe ₃ Pt), TmaFeveCr, CuO nanopaxtieies, M 3Cuo.53G ^' eo;4 N,. n3Z 0. Su0.6N0.85C0.15» Mn3Zn .3Sn0.5Nft85C0.iB0.05., an the like, as well as- mixtures of any two or more thereof.

[57] The particulate filler can be present in the composition in an. amount of about 20 percent by weight or less (i.e., up to 20 percent by weight) of the total solids content of the composition. For example, the particulate filler can be present in the composition in an amount of less than about 20 percent by weight, less than about 1 percent by weight, less than about 18 percent by weight, less than about 17 percent by weight, less than about 16 percent by weight, less than about 15 percent by weight, less than about 14 percent by weight, less than about 13 percent by weight, less than about: 12 percent by weight, less than about 11 percent by weight, less than, about 10 percent by weight, less than about percent by weight, less than about 8 percent by weight, less than about 7 percent b weight, less than, about 6 percent by weight, less than .about 5 percent by weight, less than about 4 percent by weight, less than about 3 percent by weight, less than about 2 percent by weight, or less than about 1 percent by weight of the total solids content of the composition.

Curing agent

[58] The compositions described herein can optionally include one or more curing agents. The curing agents can optionally function as conductivity promoters and/or reducing agents in the compositions. Curing agents contemplated for use in. the practice of the present invention include ureas, aliphatic and aromatic amines, polyamides, imidazoles, dicyandiam des, hydra.zides, wea~amine hybrid curing systems, free radical initiators, organic bases, transition metal catalysts, phenols, acid anhydrides, Lewis acids, Lewis bases, and the like. See, for example, U.S. Pat. No. 5,397,618, the entire contents of which are hereby incorporated b reference herein.

[53] The .curing, agent can optionally be present in the composition in an. amount of up to about 4 percent by weight of the total solids content of the composi tion. In some embodiments, the curing agent is absent from the composition (Le„ 0 percent by weight of the total solids content, of the composition), in other embodiments, the carin agent can. be present in the composition in an amount from about 0.05 percent by weight to about 4 percent by weight. -or from, about 0,1 percent b weight to about 3 percent by weight. Optionally, the curing agent is present in the composition in an amount of about 4 percent b weight or less, about 3 percent by weight or less, about 2 percent, by weight or less, or about 1 percent by weight or less.

Diluents

[60] The compositions described herein can further include a diluent, including, for example, an organic diluent. The organic diluent can be a reactive organic diluent, a non- reactive organic diluent, or a mixture thereof. Exemplary diluents include, for example, aromatic hydrocarbons (e.g., benzene, toluene, xylene, and the like); aliphatic hydrocarbons (e.g., hexane, cyeiohexane, heptane, teiradecane, and the like); chlorinated hydrocarbons (e.g., methylene chloride, chloroform, carbon tetrachloride, diehloroethaiie, tricMoroethylene, and the like); ethers (e.g., diethyl ether, ietrahydrc/fcuran, dlosane, glycol ethers, xnonoalkyl or dialkyl ethers of ethylene glycol, and the like); esters (e.g., ethyl acetate, butyl acetate, methoxy propyl acetate, and the like); polyols (e.g., polyethylene glycol, propylene glycol, polypropylene glycol, and the like); ketones (e.g., acetone, methyl ethyl ketone, and the like) amides (e.g.,

dimethylfonnainide, dimethylaeetaniide, and the like); heteioaromatic compounds (e.g., N- methyipyrro!idone, and the like); and heteroaliphatic compounds.

[61] The amount of non-reactive diluent contemplated for use in accordance with the present invention can vary widely, so long as a sufficient quantity is employed to dissolve and/or disperse the components of invention compositions. When present, the amount of non-reactive diluent employed typically falls in the range of about 2 up to about 30 percent b weight of the composition. In certain embodiments, the amount of non-reactive diluent falls in the range of about 5 up to 20 percent by weight of the total composition, in some embodiments, the amount of non-reactive diluent falls in the range of about 10 up to about 18 percent by weight of the total composition. Th amount of reacti ve dil uent contemplated for use in accordance with the present invention can be up to 5 percent by weight of the composition (e.g., 5 percent or less, 4 percent or less, 3 percent or less, 2 percent or less, or 1 percent or less).

[62] As readily recognized by those of skill in the art, in certain embodiments, invention compositions contain substantially no non-reactive diluent therein. Even if non-reacti ve diluent is, at one time, present, it can be removed during the formation of films in the B-staging process, as further described herein.

[63] Invention formulations may further comprise one or more flow additives, adhesion promoters, Theology modifiers, toughening agents, fluxing agents, film forming resins (u to 40 t % when present), film . flexibilizers, epoxy-eurmg catalysts, curing agents, and/or radical polymerization regulators, as well as mixtures of any wo of more thereof.

[64] As used herein, the term "flow additives ^5' ' refers to compounds which modify the viscosity of the formulation to which they are introduced. Exemplary compounds which impart such properties include silicon polymers, ethyl acrylate/2-ethyihexyl acrylate copolymers, aikylol. ammonium salts of phosphoric acid esters of ketoxime, and the like, as well as combinations of any two or more thereof. [65j As used herein, the term "adhesion promoters" refers to compounds which enhance the adhesive properties of the formulation to which the are introduced.

[■66] As used herein, the term "rheo!ogy modifiers" refers to additives which modify one or more physical properties of the formulation to which they are introduced,

[67] As used herein, the term "toughening agents" refers to additives which enhance the impact resistance of the formulation to which they are introduced,

[68] As used herein, the term "fluxing agents" refers to reducing agents which prevent oxides from forming on the surface of the molten metal.

[69] As used herein, the ter "film fiexibilizers" refers to agents which impart flexibility to the films prepared from formulations containing same.

[70] As used herein, the term "phenoi-novolac hardeners" refers to materials which participate in the further interaction of reactive groups so as to i ncrease the cross-linking thereof - -thereby enhancing the stiffness thereof. 7i I As used herein, the term "epoxy-euring catalysts" refers to reactive agents which promote oiigomerizaiion and/or polymerization, of epoxy-containing moieties, e.g., imidazole,

[72] As used herein, the term "curing agents" refers to reactive agents such as dicumyl peroxide which promote the curing of monomelic, oligomeric or polymeric materials.

[73] In accordance with the present invention, provided herein are fbnnulations useful as conductive .inks. Exemplary conductive inks comprise: in the range of about 5 - 50 wt% of a poiymerizahle monomer comprising a

thermosetting or thermoplastic resin component selected from the group consisting of an acetai, an acrylic monomer, oligomer, or polymer, an aciylonitrite-butadiene- styrene (ABS) polymer or copolymer or.a olycarborraie/ABS alloy, an alkyd, a butadiene, a styrene-butadiene, a cellulosic, a coumarone-indene, a cyanate ester, a dialiyl phthalate (DAP), an epoxy monomer, oligomer, or polymer, a flexible epoxy or polymer with epoxy functional groups, a fluoropolymer, a. mei amines- formaldehyde, a neoprene, a mtrile resin, a novolac, a nylon, a petroleum resin, a phenolic, a polyamicle-imide, a polyarylate and polyarylate ethe sulfone or ketone, a polybutylene, a polycarbonate, a polyester and co-polyestercarbonate, a

polyetherester, a polyethylene, a jpolyimide, a mdemiide, _. a uadimide, an itaconarnide, a polyketone, a polyolefm, a polyphenylene oxide, a sulfide, an ether, a

'polypropylene and polypropyiene-EPDM blend, a polystyrene, a polyurea, a

. polyurethane, a vinyl polymer, rubbers, a silicone polymer, a siloxane polymer, a styrene acr lonitrile, a styrene butadiene latex and other styrene copolymers, a sulfone polymer, a thermoplastic polyester (Saturated), a phthaiate, an unsaturated polyester, a urea-formaldehyde,, a polyacrylamide, a polyglycol, a polyaerylic acid, a polyethylene glycol), an inherently conductive polymer, a lluoropolymers, as well as combinations of any two or more thereof,

in the range of about 45—95 wt% of a particulated filler having a particle size in the range of 1 up to about 50 urn, wherein:

about 10 up to about 70 wt % of said particulated filler is a particulated nickel or particulated nickel-alloy, and.

0 up to about 65 wt % of said particulated .filler is a particulated, conductive non-nickgl-containmg filler,

in the range of about 0.1 ^■ - 10 wt% of a curing agent selected from: an amine, an acid, an

•anhydride., a dicyl. an imidazole, or a peroxide, and

a non-reaetive organic diluent therefor, which, when present, is present in the amount of 20 up to 80 wt % of said formulation, in some embodiments, conductive ink formulations contemplated herein comprise: in the range of about 5 - 20 wt% of a palymerizable monomer comprising a

thermosetting or thermoplastic resin component selected from the group consisting of a maleimide, a nadimide, an itaconarnide., an acrylic monomer, oligomer, ^■ or polymer, an epoxy monomer, oligomer, or -polymer, a flexible epoxy or polymer with epoxy fiinctional groups, as well as combinations of any two: or more thereof,

in the range of about 70 - 95 wt% of a particulated filler having a particle size in the

range of 1. up to about 50 μηα, wherein:

about 50 up to about 95 wt % of said particulated filler is a particulated nickel or particulated nickel-alloy, and 5 up to about SO: wt % of said particulated filler is parti eulated, conductive non~nickei-eontaimng filler,

in the range of about 0.1 - 10 wt% of a caring agent selected from an amine, an acid, an anhydride, a dicyl, animidazole, or a peroxide, and

a non-reactive organic diluent therefor, which, when present, is present in the amount of 20 up to 8:0 wt % of said formulation. } In accordance with the present invention, also provided herein are femiulations useful conductive die attach films. Exemplary die attach film formulations comprise: in the range of about 10: - 50 wt% of a polymer izable monomer- comprising a

thei iiosetiing or thermoplastic resin component selected from the grou consisting of an aeetai, an acrylic monomer, oligomer, or polymer, an aerylonitrile-ibutadiene- styrene (A S) polymer or copolyme or a polycarbon-ate/ABS alloy, an alkyd, a butadiene, a styrene-butadiene, a cellulosic, a coumarone-indene*. a cyanate ester, a dialiyl phthalate (DAP), an epoxy monomer, oligomer, or polymer, a flexible epoxy or polymer with epoxy functional groups, a fluoropolymer, a melamine-- formaideliyde, a neoprene, a nitrite- resin, a novolae, a nylon, a petroleum resin, a phenolic, a polyarnide-imide, a polyarylate and polyarylate ether sulfone or ketone, a polybutylene, a polycarbonate, a polyester and co-poiyestercarbonate, a

poiyetherester, a polyethylene, a polyimide, a maleimide, a nadimide, an itaeonarnide. a polyketone, a polyolefin, a polyphen lene oxide, a sulfide, an ether, a

polypropylene and polypropylene- EPDM blend, a polystyrene, .a polyurea, a polyurethane, a vinyl, polymer, rubbers _* a silicone polymer, a siloxane polymer,, a styrene acryionitrile, a styrene butadiene latex and other styrene copolymers, a sulfone polymer, a thermoplastic polyester (Saturated), a phthalate, an unsaturated polyester, a urea-fomialdehyde, a polyacryiamide, a: pojyglyeol, a polyacrylie acid, a poiy(ethylene glycol), an inherently conductive polymer, a fiuofopoiy ers, as well as combinations of any two or more thereof,

in the range of about 50 - 90 wt% of said filler having a particle- size in the range of 1 up to about 50 μηι, wherein said filler comprises:

about 1 up to about 90 \vt % of a . particulated nickel or nickel-alloy filler, and 0 up t about 70 t % of a patiiculated, conductive non-nickel-eontaimng filler,

in the range of about 0 - 20 wt% of a film forming resin selected from a (meth)acryiate, an epoxy, a vinyl ether, a vinyl ester, a vinyl ketone, a vinyl aromatic, a vinyl eyeloalkyl, or an ally! amide,

in the range of about 0.1 - 10 wt% of a curing agent selected from an amine, an acid, a

^■ anhydride* a dicyl, animidazole, or a. peroxide, and

a non-reactive organic diluent therefor, which, when present, is present in the amount of

5 up to 50 wt % of said formulation, in some embodiments, die attach film formulations contemplated herein comprise: in the range of about 30 - 40 wt% of a polymerizab!e monomer comprising a

themvosetting o thermoplastic resin compo t selected from the group consisting of a maleimide, a nadiinide, an itaconamide, an epoxy monomer, oligomer, or polymer, a flexible epoxy or polymer with epox functional groups, as well as combinations of any two or more thereof,

in the range of about 50 - 90 wt% of said .filler having a particle size in the range of 1 up to about 50 μηι, wherein said filler comprises:

about 1 up to about 90 wt % of a particulated nickel or nickel-alloy filler, and 0 up to about 70 wt % of a particulated, conductive non-nickel -containing filler,

in the range of about 0.1 - 10 wt.% of a film forming resin selected from a (ineth)acrylate, an epoxy, a vinyl ether, a vinyl ester, a vinyl ketone, a vinyl aromatic, a vinyl eyeloalkyl, or an ally! amide,

in the range of about 0.1 - 10 wt% of a curing agent selected from an amine, an acid, an anhydride, a dicyl, animidazole, or a peroxide, and

a non-reactive organic diluent therefor, which, when present, is present in the amount of

5 up to 50 wt % of said formulation.

In accordance with the present invention, also provided herein re: formulations useful ductive die attach pastes. Exemplary die attach paste formulations comprise: in the range of about 5 - 50 wt% of a polymerizable monomer com prising a

thennosetiing or thermoplastic resin component selected from the group consisting of an aeetal, an acrylic monomer, oligomer, or pol mer, an aerydonitiile¾riacliene- styrene (ABS) polymer o copolymer or a polyearbonate/ABS alloy, an alkyd, a butadiene, a styrene-butadiene, a eeliulosic, eoumarone-indene, a cyaaate ester, a diallyl phthalate. (DAP).,, an epoxy monomer, oligomer, or polymer, a flexible epoxy or polymer with epoxy functional groups, a fluoropolymer, a melamine- formaidehyde, a neoprene, a nitrile resin, a novolac, a nylon, a petroleum resin, a phenolic, a polyamide-imide, a polyarylate and polyarylate ethe sulibne or ketone, a polybutyiene, a polycarbonate,, a polyester and co-pol ^' yesterca bonate, a

polyetherester, a polyethylene, a olyimide, a maieimide, a nadimide, an itaconamide, a polyketone, a polyolefm, a poiyphenyiene oxide, a sulfide, an ether, a

polypropylene and polypropylene-EPDM blend, a polystyrene, a polyurea, a polyurethane, a vinyl polymer, rubbers, a silicone: polymer, a silo ane polymer, a styrene acryionitrile, a styrene butadiene latex and other styrene copolymers, a sulfone polymer, a thermoplastic: polyester (Saturated), a phthalate, an vmsa.tura.ted polyester, a isrea-fomialdehyde, a polyacrylamide, a olygiyeol, a polyacrylic acid, a poly(ethyiene glycol ), an inherently conductive polymer, a lluoropolymers, as well as combinations of an two or more thereof.

in. the range of about 50: - 95 wt% of said filler, wherein said filler has a particle size in the range of 1 up to about 50 μίη, wherein said filler comprises:

about 10 up to about 95 wt. % of a particulated nickel or nickel-alloy filler, and 0 u to about 85 wt % of a particulated, conductive non-nickel-containing filler,

i the range of about 0.1 - 20 wt% of a curing agent selected from an amine, an acid, an anhydride, a. dieyi, an imidazole, or a peroxide, and

optionally,, a reactive organic diluent therefor, which, when present, is present in the

amount of 1 up to 30 wt % of said formulation, and is a low molecular weight epox diluent. In some embodiments, die attach paste formulations contemplated herein comprise: in the range of about 20 -- 40 wt% of a polymerizable monomer comprising a thermosetting or thermoplastic resin component selected from the group consisting of a nialeimide, a iiadimlde, an itaconamide, an epoxy monomer, oligomer, or polymer, a flexible epoxy or polymer with epoxy funetional groups, as well as coiribinations of any two or more thereof,

in the range of about 50 - 95 wt% of said filler, wherein said filler ha a particle size in the range of 1 up to about 50 pm, wherein said- filler ^■ comprises;

about 20 up to about 80 wt % of a particulated nickel or nickel-alloy filler, and 20 up to about 80 wt % of a particulated, conductive iion-nickel-coiitaining filler,

in the range of about 0,1 - 20 wt% of a curing agent selected from an amine, an acid, an anhydride, a dicyl, an imidazole, or a peroxide, and

optionally, a reactive organic diluent therefor, which, when present, is present in the amount of 1 up to 30 wt % of said formulation, and is a low molecular weight epoxy diluent

[79] In accordance with the present invention, there are also provided methods for adhesively attaching a. first article to a second article, said methods comprising:

(a) applying an aliquot of any of the formulations described herein to said first article,

(b) bringing said first and second articles into intimate contact to form an assembly wherein said first article and said second article are separated only by the formulation applied in step (a), and thereafter

(c) subjecting said assembly to conditions suitable to cure said formulation.

[80] The compositions described herein provide a number of useful performance properties. For example, the composition, when cured, has a die shear strength of at least 1 ,0 kg/mm ² at 260 °C (e.g., at least 1.5 kg nim ² a 260 °C). In addition, the composition undergoes lamination onto a wafer at a temperature of 100 °C or lower and a pressure of 40 psi or lower. Further, the composition, in the form of a film, can undergo dicing and pick-up processes to result in a die/film that can bond to a substrate at a temperature: that can range from about 110 °C to 350 °C and under a pressure of from about 0.2 to 1 kg/mrrr. The die size can range from about 1x1 mm or less to about 8x8 mm or greater. The bonding time can be less: than 3 seconds.

[81] In certain embodiments of the present invention, there are provided methods of making the compositions described herein. The invention compositions ca be made in the form of a film or in the form of a paste.

[82] Invention methods for forming adhesive formulations comprise subjecting the con templated combination of components to high shear- mixi ng for a period of time sufficient to obtain a substantially homogeneous blend. In some embodiments, the components can be mixed for a period of time up to about 3 hours (e.g., from about 1 hour to 3 hours). The combination of components can be mixed at room temperature.

[83] In embodiments where the composition is to be in the form of a film, the compositions are applied to a suitable substrate (e.g., a release liner), and then heated at elevated temperature to remove substantially all of the non-reactive diluent (i.e., solvent) therefrom. For example, at least 65%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% of the solvent can be removed. The process of heating a paste or a film to dry it is referred to herein as B-staging. The resulting film can have a thickness, of from about 5 microns to. about 50 microns.

[84] In certain embodiments of the present invention, there are provided films comprising the reaction product obtained upon removin subs tantially all of the sol vent diluent from the above-described B-staged compositions. The film can be wound on a roll.

[85] The film as described herein can be laminated onto a substrate (e.g., a wafer) using a conventional laminator in the semi-conductor industry. For example, the film can be laminated onto a wafer using a roll laminator. Exemplary larninators that can be used include the DFM 2700 (Disco Corporation; Japan), the Leonardo 200 LD (Microcontrol Electronic; Italy), and the Western Magnum RL- 120 (E! Segundo, CA). As described above, the lamination can be performed at a temperature of less than 100 °C (e.g., 95 °C or less, 90 °C or less, 85 °C or less, 80 °C or less, 75 °C or less, 70 °G or less, or 65 °C or less). The lamiiiation can be performed at a pressure of 40 psi or less: (e.g. , 35 psi or less or 30 psi or less). [86] The release liner, if used, can be peeled off from the film. The film can then be laminated to a dicing tape, which serves as support during the dicing process. The lamination of th film to the dicing tape can be performed at room temperature. As a result of the lamination process, the film is held between and in direct contact with the dicing tape and the wafer. During the dicing process, the wafer and film can ^' be diced into individual dies wi th the film adhered to the die. The individual dies and adhered film can be removed from the dicing tape during the pick-up process and then can be attached to a substrate in a bonding/die attach step. The bonding/ die attach ste can be performed at a temperature of from about 110 °C to 350 °C for a bonding time of less than 3 seconds. A bonding/ die attach pressure of 0.2 kg/mm ² to 1 kg/mm ² can be used for a variety of die sizes (e.g., for die sizes ranging from less than 1x1 mm to 8x8 mm or above). The resulting die/film/substrate assembly can then be processed in at least one thermal operation, such as curing in an oven, wirebonding followed by molding, and the like.

[87] Suitable substrates contemplated for use herein include lead-frame(s). As used herein, "iead-frame(s)" comprise a base plate consisting of copper or copper alloys, and a protective coating formed on the upper (or both) surface(s) of the base plate. The protective coating is composed of at least one metal selected from the group consisting of gold, gold alloy, silver, silver alloy, palladium or palladium alloy, and has a thickness of about 10-500 angstrom. The protective coating is formed by suitable means, e.g., by vapor deposition. It is possible to fomi an mtermediate coating of nickel or nickel alloys between the surface of the base pla te and the protective: coating, by means of vapor deposition or wet plating. A -suitable thickness for the intermediate coating is within the range of about 50-20,000 angstrom. See, for example. U.S. Pat. No. 5,510,197, the entire contents of which are hereby incorporated by reference herein.

[88] Optionally, the substrates for use in the present invention include laminate substrate(s) designed for semiconductor packages (e.g., BT substrate, FR4 substrate, and the like), polyethylene terephthalate, polymethyl methacrylate, polyethylene, polypropylene,

polycarbonate, an epoxy resin, polyimide, polyamide, polyester, glass, and the like.

^' [89] In accordance: with yet another embodiment of the present invention, there are provided methods for preparing die attach films and pastes. For pastes, the methods can comprise curing the above-described compositions after application thereof to a suitable substrate, as described above. For films, the methods can comprise high temperature bonding of the dies and films to a suitable substrate, as described above. Optionally, the methods for preparing die attach films can include a curing process to optimize the morphology and- for device stress stabilization. The curing process can be performed in an oven.

[90] As described herein, the films and pastes according to the present invention can be used for die attach. The die surface can optionally be coated with a metal, such as silver.

[91 J In accordance with yet another embodiment of the present invention, there are provided articles comprising die attach films and pastes as described herein adhered to a suitable substrate therefor.

[92] Articles according to the present invention can be characterized in terms of the adhesion of the cured die attach film or paste to the substrate; typically the adhesion is at least about 1.0 kg/mm" at 260 °C (e.g., at least about 1,5 kg/mm ² at 260 ^i: ( ^' ).; in some embodiments, the adhesion is at least about 2.5 kg/mm ² at 260 °C. As described above, the die shear strength is measured on a die shear tester using a die metallized with titanium-nickel-sil ver and a silver- coated lead-frame substrate. f 93J As readily recognized by those of skill in the ait, the dimensions of invention articles can vary over a wide range. Exemplary articles include, for example, semiconductor dies. Dies for use in the present invention ca vary in surface area, In some embodiments, semiconductor dies tor use in the present invention can range from 1x1 mm or less _: to 8x8 mm or greater.

[94 ] In accordance with yet another embodiment of the present invention, there are pro vided methods for laminating a film onto a semiconductor wafer, comprising: applying a composition for a film as described herein to a, semiconductor wafer; and laminating the composition onto the semiconducto wafer at a temperature of 100 °C or lower and pressure of 40 psi or lower.

[95] In accordance with yet anothe embodiment of the present invention, there are provided methods for preparing a conductive network, said method comprising: applying a composition for a film as described herein to _: a wafer;

laminating the composition onto the wafer at a temperature of 100 °C or lower and a pressure of 40 psi or lower to result in a fi.hn attached to: a wafer; dicing the film attached to the wafer to result in a die and film; and

bonding the die and film, to a substrate under .a pressure of 0.2 kg/mm ² to I kg/mm ² .

[96] In accordance with yet another embodiment of the present invention, there are provided methods for preparing a conductiv network, said method comprising: applying a composition for a paste as described, herein to a substrate (e.g., a lead-frame) in a predefined pattern;

die attaching the composition to a die and the substrate; and

curing the composition.

[97] Optionally, the composition can be applied . such that the .resulting film or paste is present at a thickness of at least about 5 microns. For example, the thickness of the film can be from about 5 microns to about 50 microns (e.g.. f om about S microns to about 30 microns) and the thickness of the paste can be from about 5 microns to about 50 microns.

(98] In accordance with still another embodiment, of the present invention, there are provided conductive networks prepared as described herein.

[99] The formulations described herein can be used within the ^■ electronics industry and other industrial applications. For example, the formulations described herein can be used for die attach applications on lead-frames for power discretes, for clip attach applications as wire bond replacements for high performance discretes, for heat slug attach applications for the cooling of power discretes with, exposed, pads, for single- and multi -die devices, and for other devices requiring high electrical and/or thermal conductivity between a die and a frame.

{100] Various aspects of the present invention are illustrated by the following non-limiting examples. The examples are for illustrative purposes and are not a limitation on any practice of the present invention. It will, be understood that variations and modifications can be made without departing from the spirit and scope of the invention. One of ordinary skill in the art readily knows how to synthesize or commercially obtain the reagents and components described herein. EXAMPLE 1

Adhesive Films

[101] Formulations according to the invention were prepared by combining the components set forth in Table 1 , as follows.

Table 1

f 102] The volume resistivity (VR) of the resulting formulation was evaluated as noted in Table 1 , demonstrating that an exemplary formulation, according to. the invention (wherein 75% of the particulated, conducti ve filler is nickel or a nickel-alloy, and only 25% of the particulated, conductive filler is silver], provides an adhesive film with a desirable VR of ixl 0 ^"2 Ohm cm..

EXAMPLE 2

Adhesive Films

103] Additional formulations according to the invention were prepared by combining the components set forth in Table 2, as follows.

Table 2

[104] The volume resistivity (VR) of the: resulting formulation was evaluated as noted in Table 2, demonstrating that an exemplary fomiulation according to the invention (wherein about 69% of the particuiated., conductive filler is nickel or a nickel-alloy, and only 31% of the particuiated, conductive filler is silver), provides an adhesive film with a desirable VR of 2x10 ^"3 Ohm cm.

EXAMPLE 3

Adhesive Pastes

[1:05] Additional formulations according to the invention were prepared by combining the compone ts set forth in Table 3, as follows.

Table 3

|106] The volume resistivity: (VR) of the resulting formulation was evaluated as noted in Table 3, demonstrating that an exemplary formulation according to the invention (wherem 75% of the particuiated, conductive filler is nickel or a nickel-alloy., and onl 25% of the particuiated, conductive filler is silver), provides an adhesive paste with a desirable VR of 2x10 ^" Ohm cm.

EXAMPLE 4

Adhesive Pastes

[107] Additional formulations according to the invention were prepared by combining the components set forth in Table 4, as follows.

Table 4

[108] The volume resistivit (VR) of the resulting form illation was evaluated as noted in Table 4, demonstrating that an exemplaiy formulation according to the invention (wherein about 73% of the parlieulated, conductive filler is nickel or a nickel-alloy, and only about 26% of the particixlated. eonductive filler is silver), provides an adhesive paste with a desirable VR of 8x10 ^" Ohm cm.

EXAMPLE S

Adhesive Pastes

[1091 Additional formulations according to the invention were prepared by combining the components set forth in Table % as follows.

Table 5

[110] The volume resistivity (VR) of the resulting formulation was evaluated as noted in Table 5, demonstrating that, an exemplary formulation according to the invention (wherein 65% of the particulatedv conductive filler is nickel or a nickel-alloy, and only 3.5% of the partieulated, eonductive filler is silver), provides an adhesive film with a desirable VR of 2 10 ^"3 Ohm cm.

EXAMPLE 6

Conductive Inks

[1 11] Formulations according to the invention were prepared by combining the components set forth in Table 6, as follows.

Table 6

f 1121 The .volume resistivity (VR) of the resulting formulation was evaluated as noted In Table 6, demonstrating that an exemplary formulation according to th invention (wherein about 89% of the partioulated, conductive filler is nickel or a nickel-alloy, and only 10% of the particulate*!, conductive filler is silver), provides a conductive ink with a desirable VR of 4xl0 ^"3 Ohm cm.

EXAMPLE 7

Conductive inks

[1131 Formulations according to the invention were prepared by combining the components set forth m Table 7, as follows.

Table 7

[114] The volume resistivity (VR) of the resul ting formulation was evaluated as noted in Table 7. demonstrating that an exemplary formulation accordmg to the invention (wherein about 79% of the particulated, conductive filler is nickel or a nickel-alloy, and only about 21% of the particulated, conductive filler is silver), provides a conductive: ink with a desirable VR of 5 10 ^"4 Ohm em.

EXAMPLE 8

Conductive inks

[115] Formulations accordmg to the invention were prepared by combining the components set forth in Table 8, as follows.

Table 8

[116] The volume resistivity (VR) of the resulting formulation was evaluated as noted in Table 8, demonstrating that an exemplary fonmiiation according to the invention (wherein 75% of the particulated, conductive filler is nickel or a nickel-alloy, and only 25% of the partieulated, conductive filler is silver), provides an adhesive film with a desirable VR of 6x10 ^'3 Ohm cm.

EXAMPLE 9

Conductive Inks

[117] Formulations according to the invention were prepared by combining the components set forth in Table 9. as follows.

Table 9

[118} The volume resistivity (VR) of the resulting formulation was evaluated as noted in Table 9, demonstrating that an exemplary formulation according to the invention (wherein 50% of the partieulated, conductive filler is nickel or a nickel-alloy,, and 50% of the partieulated, conductive filler is silver), provides a conductive ink with a desirable VR of 9x10" Ohm cm.

[11 ] Various modifications of the present invention, in addition to those shown and described herein, will be apparent to those skilled in the art of the above description. Such modifications are also intended to fall within the scope of the appended claims.

[120] Patents and publications mentioned in the specification are indicative of the levels of those skilled in the art to which the invention pertains. These patents and publications are incorporated, herein by reference to the same extent as if each individual application or publication was specifically and individually incorporated herein by reference.

[121] The foregoing description is illustrative of particular embodiments of the invention, but is not meant to be a limitation upon the practice thereof. The following claims, including all equivalents thereof, ^' are intended to define the scope of the invention.