PARK, Se-Hyung (6409, Taepyeong 1-dongSujeong-gu, Seongnam-s, Gyeonggi-do 461-823, KR)
LEE, Byrong-Il (3 Cheongmyeong Maeul 3-danji, Samick apartmentYeongtong-dong, Yeongtong-gu, Suwon-s, Gyeonggi-do 443-737, 21-1603, KR)
PARK, Jong-Min (505-301, Saemmaeul woobang apartmentHogye-dong, Dongan-gu, Anyang-s, Gyeonggi-do 431-080, KR)
SONG, Seog-Jeong (506-502, Byeoksan Chelseavill Apt. 723,Seongbok-dong, Suji-gu, Yongin-s, Gyeonggi-do 449-530, KR)
KIM, Byoung-Kee (204-504, Byeoksan town 2-danji apartment832-1, Jukjeon-dong, Yongin-s, Gyeonggi-do 449-160, KR)
PARK, Se-Hyung (6409, Taepyeong 1-dongSujeong-gu, Seongnam-s, Gyeonggi-do 461-823, KR)
LEE, Byrong-Il (3 Cheongmyeong Maeul 3-danji, Samick apartmentYeongtong-dong, Yeongtong-gu, Suwon-s, Gyeonggi-do 443-737, 21-1603, KR)
PARK, Jong-Min (505-301, Saemmaeul woobang apartmentHogye-dong, Dongan-gu, Anyang-s, Gyeonggi-do 431-080, KR)
SONG, Seog-Jeong (506-502, Byeoksan Chelseavill Apt. 723,Seongbok-dong, Suji-gu, Yongin-s, Gyeonggi-do 449-530, KR)
WHAT IS CLAIMED IS:
1. A method of manufacturing a metal electrode, comprising: (I) a
step of forming a photoresist layer over a whole surface of a substrate
by means of coating or laminating method, then, enabling the whole
surface of the substrate with the photoresist layer to successively
undergo pre-baking, exposing, developing and post-baking processes to
form a metal electrode pattern, so that the photoresist layer remains on any region of the substrate other than a region which has the metal
electrode formed thereon; (II) a step of metal plating the patterned
substrate so as to form the metal electrode only on the region of the substrate which has no photoresist layer formed thereon; and (III) a
step of releasing the residual photoresist layer from the substrate.
2. The method according to claim 1, wherein the post-baking is carried out at 120 to 150°C for 3 to 20 minutes.
3. The method according to claim 1, wherein the metal plating is performed under a strong alkali condition of pH 11 to 12.
4. The method according to claim 1, wherein a composition for positive type photoresist comprising an alkali soluble resin, a photosensitive compound, a thermo-curable cross linking agent, a sensitivity enhancer and a solvent is applied to the whole surface of a
metal plate.
5. The method according to claim 4, wherein the composition for
positive type photoresist includes 30 to 80 parts by weight of the
photosensitive compound, 3 to 15 parts by weight of the sensitivity enhancer, 10 to 30 parts by weight of the thermo-curable cross linking
agent and 30 to 120 parts by weight of the solvent, based on 100 parts
by weight of the thermoplastic resin.
6. The method according to claim 1, wherein a positive type
photoresist film having a supporting film and a photoresist layer formed on the supporting film, which comprises an alkali soluble resin, a
photosensitive compound, a thermo-curable cross linking agent and a sensitivity enhancer, is laminated on the whole surface of the metal
plate.
7. The method according to claim 6, wherein the photoresist layer includes 30 to 80 parts by weight of a diazide based photosensitive
compound, 10 to 30 parts by weight of the thermo-curable cross linking agent and 3 to 15 parts by weight of the sensitivity enhancer, based on 100 parts by weight of the alkali soluble resin.
8. The method according to claim 4 or 6, wherein the alkali soluble
resin is cresol novolac resin.
9. The method according to claim 8, wherein the cresol novolac
resin has a weight average molecular weight (based on GPC) ranging
from 2,000 to 30,000.
10. The method according to claim 8, wherein the cresol novolac resin has a meta/para-cresol content in a mixing ratio by weight
ranging from 4:6 to 6:4.
11. The method according to claim 8, wherein the cresol novolac
resin is a mixture of (i) cresol novolac resin having a weight average molecular weight (based on GPC) ranging from 8,000 to 30,000 and (ii)
cresol novolac resin having a weight average molecular weight (based on
GPC) ranging from 2,000 to 8,000 in a mixing ratio ranging from 7:3 to 9: 1.
12. The method according to claim 4 or 6, wherein the photosensitive compound is at least one selected from a group consisting of: 2,3,4,4-tetrahydroxybenzophenone-l,2-
naphthoquinonediazide-sulfonate; 2,3,4-trihydroxybenzophenone- 1 ,2-
naphthoquinonediazide-5-sulfonate; and (l-[l-(4-hydroxyphenyl)-
isopropyl]-4-[ 1 , l-bis(4-hydroxyphenyl)ethyl]benzene)- 1 ,2-
naphthoquinonediazide - 5 - sulfonate .
13. The method according to claim 4 or 6, wherein the sensitivity
enhancer is at least one selected from a group consisting of 2,3,4-
trihydroxybenzophenone, 2,3,4,4-tetrahydroxybenzophenone and 1-[1-
(4-hydroxyphenyl)isopropyl]-4-[ 1 , 1 -bis(4-hydroxyphenyl)ethyl]benzene.
14. The method according to claim 4 or 6, wherein the thermo- curable cross linking agent is methoxymethylmelamine based resin.
15. The method according to claim 14, wherein the
methoxymethylmelamine based resin is hexamethoxymethylmelamine
resin.
16. The method according to claim 4, wherein the composition for positive type photoresist includes 30 to 80 parts by weight of the photosensitive composition, 3 to 15 parts by weight of the sensitivity enhancer, 10 to 30 parts by weight of the thermo-curable cross linking agent and 190 to 250 parts by weight of the solvent, based on 100 parts
by weight of the alkali soluble resin.
17. The method according to claim 4 or 16, wherein the solvent is
at least one selected from a group consisting of ethyl acetate, butyl
acetate, ethyleneglycol monoethylether acetate, diethyleneglycol
monoethylether acetate, propyleneglycol monoethylether acetate,
acetone, methylethyl ketone, ethyl alcohol, methyl alcohol, propyl alcohol, isopropyl alcohol, benzene, toluene, cyclopentanone, cyclohexanone, ethyleneglycol, xylene, ethyleneglycol monoethylether
and diethyleneglycol monoethylether.
18. The method according to claim 1, wherein a composition for
positive type photoresist comprising an alkali soluble resin, a
photosensitive compound, a thermo-curable cross linking agent, a sensitivity enhancer, an isocyanate compound and a solvent is applied
to the whole surface of the substrate.
19. The method according to claim 18, wherein the composition for positive type photoresist includes 30 to 80 parts by weight of the
photosensitive compound, 3 to 15 parts by weight of the sensitivity enhancer, 10 to 30 parts by weight of the thermo-curable cross linking agent, 1 to 5 parts by weight of the an isocyanate compound and 30 to
120 parts by weight of the solvent, based on 100 parts by weight of the alkali soluble resin.
20. The method according to claim 1, wherein a positive type photoresist film having a supporting film and a photoresist layer formed
on the supporting film, which comprises an alkali soluble resin, a
photosensitive compound, a thermo-curable cross linking agent, an
isocyanate compound and a sensitivity enhancer, is laminated on the whole surface of the substrate.
21. The method according to claim 20, wherein the photoresist
layer includes 30 to 80 parts by weight of a diazide based photosensitive
compound, 10 to 30 parts by weight of the thermo-curable cross linking
agent, 1 to 5 parts by weight of the an isocyanate compound and 3 to 15 parts by weight of the sensitivity enhancer, based on 100 parts by weight of the alkali soluble resin.
22. The method according to claim 18, wherein the solvent is at least one selected from a group consisting of ethyl acetate, butyl acetate, ethyleneglycol monoethylether acetate, diethyleneglycol monoethylether
acetate and propyleneglycol monoethylether acetate.
23. The method according to claim 1, further comprising: (a) a
step of etching the substrate formed patterns; (b) a step of dipping the
etched substrate in a coupling agent solution; and (c) a step of dipping
the previously dipped substrate in a plating catalyst solution, between
the step of forming the pattern on the substrate and the step of forming the metal electrode.
24. The method according to claim 1, wherein it additionally
includes: (a) a process of depositing a plating catalyst on the insulating
substrate before formation of patterns on the substrate, and (b) a
process of etching the plating catalyst deposited on the region with the
photoresist layer released therefrom, by using an etching solution after the releasing process of the photoresist layer.
25. The method according to claim 24, wherein the etching solution for the plating catalyst is one selected from a group consisting
of hydrofluoric acid, hydrochloric acid and nitric acid.
26. The method according to claim 1, wherein the metal plating is electroless metal plating.
27. The method according to claim 26, wherein the electroless
metal plating is one selected from a group consisting of electroless gold
plating, electroless silver plating, electroless tin plating and electroless
copper plating.
28. The method according to claim 1, wherein the substrate is one
selected from a metal plate and an insulating substrate.
29. The method according to claim 28, wherein the insulating
substrate is a glass plate. |
METHOD OF MANUFACTURING METAL ELECTRODE
TECHNICAL FIELD
The present invention relates to a method of manufacturing a metal electrode, and more particularly, to a method of manufacturing a
metal electrode such as silver electrode (hereinafter, referred to as "Ag
electrode") for PDP, which can reduce loss of metal ingredients such as
silver required for plating the metal electrode, thereby considerably
reducing production cost of the metal electrode.
Also, the present invention relates to a method of
manufacturing a metal electrode, and more particularly, to a method of directly forming patterns of the metal electrode, for example, Ag
electrode on an insulating substrate in flat display panel applications,
characterized in that it can reduce loss of metal ingredients of the metal
electrode and not cause deformation of the substrate and/ or the metal
electrode patterns.
BACKGROUND ART
As one of conventional techniques for the formation of a metal electrode, a method for manufacturing Ag electrode of PDP comprises a glass substrate being coated with a resin composition containing silver particles dispersed therein (hereinafter, referred to as "silver paste") by
means of screen printing process, then, successively subjected to pre-
baking, exposing, developing, drying and calcination processes to
produce the final Ag electrode.
However, since the above method developed and removed
undesirable portions (that is, any part except electrode formation part)
after application of the silver paste over the glass substrate, it caused
excessive loss of the silver paste and metal ingredients such as silver
required for forming the electrode, causing a problem of increase in
production cost.
Further, since such a method described above formed the
patterns while containing the metal ingredients in a resin composition
and produced the final metal electrode by removing the resin composition with calcination, it generated a lot of pores due to the calcination process. It is known that such pores cause a problem of
affecting the electrode by acting as an obstacle to current flow such that
electrical resistance is increased.
Therefore, it is an abject of the present invention to solve the
above problems and adopt a novel plating method in place of typical methods using metal paste such as Ag paste as described below, so that it can greatly reduce loss of metal ingredients such as silver during the formation of the metal electrode, thereby decreasing the production cost thereof, and is useful for forming the metal electrode with high density.
Generally, it is understood that a plating method is to form a
coating on the surface of a metal or non-metal substrate by using
another metal material different from the substrate so as to prevent corrosion of the substrate and/ or improve abrasion resistance, thermal
resistance or polishing properties thereof.
Among those, a common gold-plating method comprises
multiple steps of: washing out impurities from the surface of the
substrate; activating the surface of the substrate with cations; adhering
palladium (Pd) to the surface of the activated substrate; removing Pd and oxidized metal ions adhered to the surface of the substrate; electro-
depositing nickel (Ni) to the surface of the substrate by immersing the
substrate in a solution bath containing Ni ions; and again immersing
the treated substrate in alternative solution bath containing gold (Au) ions to electro -deposit Au to the surface of the substrate. Herein, Au
has reduction potential higher than that of Ni, and Au ions take inner
electrons from Ni. As a result, Ni becomes oxide ion while Au is electro- deposited by the inner electrons from Ni.
Such Au plating method forms a coating of solder paste on a
subject, for example, semiconductor circuit of a substrate to protect the same and the substrate is mostly made of copper (Cu) component with conductive properties.
Next, an illustrative example of electroless Au plating methods
for conductive materials will be disclosed as follows.
A substrate normally used in printed circuit board (PCB) has a
construction in that a copper layer is formed to a thickness of 30 to 40 μm on an epoxy substrate, that is, a nonconductor. By the above
plating method, the substrate also has Ni coating to a thickness of 3 to
5 μm and Au coating to a thickness of not more than 0.1 μm, respectively.
After completion of Au plating, the resultant PCB substrate is coated
with the solder paste, loaded with essential parts and dried by passing
the substrate through an oven. The processed PCB substrate prevents surface oxidation thereof and maintains stability of circuit with respect
to external environment.
Such a plating method described above is developed at present as one of circuit fabrication methods. As compared to the silver paste
method requiring a high temperature sintering process, the plating
method includes an etching process instead of the sintering process and can form electrode patterns in a photoresist layer of the substrate without deformation of the substrate and the patterns so that it has an
advantage of preventing undercut. However, it also has a problem in that a part of the photoresist layer cannot tolerate the plating process and is removed from the substrate.
Conductive materials to form an electrode generally include
silver, gold, metal catalyst materials and, especially, the most widely
and commonly used material is silver with excellent conductive
properties and less affinity to oxygen.
Conventionally known methods for forming metal electrode
patterns on a substrate include, but are not limited to, silver paste
method, metal deposition method and plating method.
A metal electrode formation method using silver paste normally includes steps of placing a screen mask on an insulating substrate and
applying the silver paste thereon and calcining the silver paste at a temperature of not less than 500 °C , thereby producing the electrode.
Although this method can reduce production processes, it also has
disadvantages such as severe contraction of silver paste pattern caused
by the calcining process at high temperature, higher specific resistance due to additives for facilitating paste formation and adhesion to the substrate, high price of the silver paste and so on.
A metal deposition method includes steps of depositing a metal
seed layer on a substrate so as to increase adhesiveness between the surface of the substrate and the metal electrode, and again depositing a
metal electrode layer over the metal seed layer adhered to the substrate.
Next, the treated substrate is coated with a photoresist layer and undergoes exposing and developing processes to form an electrode pattern on the substrate. The metal electrode layer and the metal seed layer are removed except for the electrode pattern by using an etching
solution and the photoresist layer is removed by a releasing process,
thereby forming the electrode. Although the above method has an
advantage of forming microfine patterns with high resolution, it is slow
and shows great loss of raw materials due to an etching process since
deposition of the metal electrode layer and the metal seed layer is repeatedly performed.
The plating method may partially use nickel or chromium based
alloy oxide to form a part of the metal seed layer when the metal seed
layer is deposited on the electrode of the substrate in order to enhance
adhesiveness of the electrode to the substrate. In addition, in order to improve the conductivity of the electrode, a part of the metal seed layer
may be made of conductive metal materials. The substrate is coated
with the photoresist layer and subjected to the exposing and developing processes to form the metal electrode pattern. After the electrode
pattern is formed by an electro-plating process, the photoresist layer is
released and followed by the etching of metal seed layer to finish and complete the substrate.
Electroless plating among the plating methods is a method of
depositing metal moiety on the surface of the substrate by using a reductant to carry out reduction of metal ions into an auto-catalyst without electric power supplied from the outside, the metal ions being contained in a metal salt solution. In comparison with the electro-
plating method, the electroless plating method has an advantage in that
it can give a plating layer which is more minute or finer, has uniform
thickness and is applicable to even a substrate based on plastic or
organic materials as well as a conductive material. Moreover, this
method has excellent corrosion resistance and abrasion resistance.
A photoresist or a photoresist film is used in the manufacture of
highly integrated semiconductors such as integrated circuits (IC),
printed circuit boards (PCB), and/ or electronic display devices, such as
cathode ray tubes (CRTs), color LCD displays or organic EL displays.
And, such devices are generally manufactured by using
photolithography and photo-fabrication techniques.
The photoresist film requires a resolution sufficient to form a
pattern with extremely fine lines and small space area of not more than
7 μm 2 .
The physical properties of the photoresist can be altered, such
as alteration in solubility to certain solvent (that is, increase or decrease
in solubility), coloration, curing and the like, via chemical modification
of the molecular structure of the photoresist resin or the photoresist.
Therefore, it is an object of the present invention to solve the above problems and provide a method of directly forming a metal electrode pattern with improved solidity on an insulating substrate.
DISCLOSURE OF INVENTION
(TECHNICAL PROBLEM)
Accordingly, an object of the present invention is to provide a method of manufacturing a metal electrode which can considerably
reduce loss of metal ingredients used for forming the metal electrode
while forming the metal electrode with high density.
In order to achieve the above object, the present invention provides a method of forming a photoresist layer which has excellent
plating resistance under even strong alkali conditions as well as high
film speed, and favorable developing contrast, sensitivity and resolution, on a part of a metal plate before the metal plating process.
Also, the present invention provides a method of forming a
photoresist layer with excellent plating resistance under even strong
alkali condition.
Further, the present invention provides a method of directly
and more securely forming a metal electrode on an insulating substrate without requiring deposition of a plating catalyst. In addition, the
present invention provides a method of manufacturing a metal electrode
which can exclude high temperature treatment and remarkably reduce deformation of the substrate and /or the metal electrode pattern while reducing loss of metal ingredients used for the metal electrode.
Alternatively, the present invention provides a method of
forming a photoresist layer with superior thermal resistance,
adhesiveness and plating resistance.
Also, the present invention provides a method of directly
forming a metal electrode on an insulating substrate by the plating
process.
(TECHNICAL MEANS TO SOLVE THE PROBLEM)
In order to achieve the objects described above, there is
provided a method of manufacturing a metal electrode according to the
present invention comprising: (I) a step of forming a photoresist layer
over a whole surface of a substrate by means of coating or laminating
method, then, enabling the whole surface of the substrate with the
photoresist layer to successively undergo pre-baking, exposing, developing and post-baking processes to form a metal electrode pattern,
so that the photoresist layer remains on any region of the substrate
other than a region which has the metal electrode formed thereon; (II) a
step of metal plating the patterned substrate so as to form the metal electrode only on the region of the substrate which has no photoresist
layer formed thereon; and (III) a step of releasing the residual photoresist layer from the substrate.
The above description and the following embodiments are all illustrative of the present invention in order to more specifically describe
the present invention as defined by the appended claims.
The objects and other aspects of the present invention will
become apparent from the following examples with reference to the
accompanying drawings. However, the detailed description and
examples are intended to illustrate the invention as preferred
embodiments of the present invention and do not limit the scope of the
present invention. Accordingly, it will be understood to those skilled in the art that various modifications and variations may be made therein
without departing from the scope of the present invention.
Hereinafter, the present invention will be described in detail, with reference to the accompanying drawings.
First, the present inventive method for forming metal electrode
pattern includes steps of: forming a photoresist layer over a whole surface of the substrate by means of coating or lamination method, the photoresist layer comprising an alkali soluble resin, a photosensitive
compound, a thermo-curable cross linking agent and a sensitivity
enhancer; and successively pre-baking, exposing, developing and post- baking the substrate coated with the photoresist layer so as to cause
the photoresist layer to remain on any region of the substrate other than a region which has the photoresist layer formed thereon.
As the method of forming the photoresist layer, there may be used a coating method that coats a substrate with a composition for
positive type photoresist comprising an alkali soluble resin, a
photosensitive compound, a thermo-curable cross linking agent, a
sensitivity enhancer and a solvent, or a lamination method that
laminates a positive type photoresist film which includes a supporting
film and a photoresist layer comprising an alkali soluble resin, a
photosensitive compound, a thermo-curable cross linking agent and a
sensitivity enhancer formed on the supporting film, over the whole
surface of the substrate.
The substrate may be a metal plate or an insulating substrate.
The photoresist layer formed over the substrate may further contain a releasing agent.
The composition for positive type photoresist includes, but is
not limited to: a composition comprising 30 to 80 parts by weight of the
photosensitive compound, 3 to 15 parts by weight of the sensitivity enhancer, 10 to 30 parts by weight of the thermo-curable cross linking
agent and 30 to 120 parts by weight of the solvent based on 100 parts
by weight of a thermoplastic resin; a composition comprising 30 to 80
parts by weight of the photosensitive compound, 3 to 15 parts by weight of the sensitivity enhancer, 10 to 30 parts by weight of the thermo- curable cross linking agent and 190 to 250 parts by weight of the solvent based on 100 parts by weight of the alkali soluble resin; or a composition comprising 30 to 80 parts by weight of the photosensitive
compound, 3 to 15 parts by weight of the sensitivity enhancer, 10 to 30
parts by weight of the thermo-curable cross linking agent, 1 to 5 parts
by weight of isocyanate compound and 30 to 120 parts by weight of the
solvent based on 100 parts by weight of the alkali soluble resin.
The alkali soluble resin used in the photoresist layer is any of
commercially available alkali soluble resins.
The alkali soluble resin preferably includes, but is not limited to,
thermo-curable novolac resin as a condensation product of phenols and aldehydes and, most preferably ere sol novolac resin.
Novolac resin is obtained by polycondensation of phenols alone
or in combination with aldehydes and an acidic catalyst according to
known reaction mechanisms.
Phenols include, but are not limited to: primary phenols such
as phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,5-xylenol, 3,4-
xylenol, 3,5-xylenol, 2,3,5-trimethylphenol-xylenol, 4-t-5-butylphenol, 2-t-butylphenol, 3-t-butylphenol, 4-methyl-2-t-butylphenol and the like;
and polyhydric phenols such as 2-naphthol, 1 ,3-dihydroxy naphthalene,
1,7-dihydroxy naphthalene, 1,5-dihydroxyl naphthalene, resorcinol, pyrocatechol, hydroquinone, bisphenol A, phloroglucinol, pyrogallol and the like, which may be used alone or in combination. A combination of
m-cresol and p-cresol is particularly preferred.
Suitable aldehydes include, but are not limited to,
formaldehyde, trioxane, paraformaldehyde, benzaldehyde, acetaldehyde,
propylaldehyde, phenylacetaldehyde, α or β-phenyl propylaldehyde, o-,
m- or p-hydroxybenzaldehyde, glutaraldehyde, terephthalaldehyde and the like and may be used alone or in combination.
The cresol novolac resin used in the present invention
preferably has a weight average molecular weight (based on GPC) ranging from 2,000 to 30,000.
In addition, the cresol novolac resin for use in the present
invention preferably has a meta/para-cresol content in a mixing ratio
by weight ranging from 4:6 to 6:4, since the resin has varied physical properties such as film speed and film residual rate dependent on the
mixing ratio of the meta/para-cresol content.
If the meta-cresol content among the cresol novolac resin
exceeds the above range, the film speed becomes higher while the film
residual rate is rapidly lowered. On the other hand, the film speed
becomes unfavorably slow when the para-cresol content exceeds the above range.
Although such cresol novolac resin having a meta/para-cresol
content in the mixing ratio by weight ranging from 4:6 to 6:4 can be used alone, more preferably used are resins with different molecular weights in combination. In this case, the cresol novolac resin is preferably a mixture of (i) cresol novolac resin having a weight average
molecular weight (based on GPC) ranging from 8,000 to 30,000 and (ii)
cresol novolac resin having a weight average molecular weight (based on
GPC) ranging from 2,000 to 8,000 in a mixing ratio ranging from 7:3 to 9: 1.
The term "weight average molecular weight" used herein refers
to a conversion value of polystyrene equivalent determined by Gel Permeation Chromatography (GPC). If the weight average molecular
weight is less than 2,000, the photoresist resin film exhibits a dramatic
thickness reduction in unexposed regions after development of the film.
On the other hand, when the weight average molecular weight exceeds
30,000, the development speed is lowered thereby reducing sensitivity.
The novolac resin of the present invention can achieve the most
preferable effects when a resin obtained after removing low molecular weight ingredients present in the reaction product has a weight average
molecular weight within the range (of 2,000 to 30,000). In order to
remove the low molecular weight ingredients from the novolac resin, conventional techniques known in the art including fractional precipitation, fractional dissolution, column chromatography and the
like may be conveniently employed. As a result, performance of the photoresist resin film is improved, especially, scumming, thermal resistance, etc.
As the above alkali soluble resin, the novolac resin can be
dissolved in an alkaline solution without increase in volume and
provides images exhibiting high resistance to plasma etching when the
resin is used as a mask for the etching.
The photosensitive compound as a constitutional ingredient of
the present inventive composition is a diazide based photosensitive
compound and, in addition, acts as a dissolution inhibitor to reduce
alkali-solubility of the novolac resin. However, this compound is
converted into an alkali- soluble material when light is irradiated
thereon, thereby serving to increase the alkali- solubility of the novolac resin.
The diazide based photosensitive compound may be synthesized
by esterification between a polyhydroxy compound and a
quinonediazide sulfonic compound. The esterification for synthesizing the photosensitive compound comprises: dissolving the polyhydroxy
compound and the quinonediazide sulfonic compound in a solvent such as dioxane, acetone, tetrahydrofuran, methylethylketone, N- methylpyrolidine, chloroform, trichloroe thane, trichloroethylene or
dichloroethane; condensing the prepared solution by adding a basic
catalyst such as sodium hydroxide, sodium carbonate, sodium hydrogen carbonate, trie thy lamine, N-methyl morpholine, N-methyl piperazine or 4-dimethyl aminopyridine to the solution; and successively washing, purifying and drying the resulting product.
Desirable isomers can be selectively esterified and the esterification rate
(average esterification rate) is not specifically limited, but is preferably
in the range of 20 to 100% and more preferably 60 to 90% in terms of the esterification of the diazide sulfonic compound to OH groups of a
polyhydroxy compound. When the esterification rate is too low, pattern
structure and resolution are deteriorated. In contrast, deterioration of
sensitivity occurs if the esterification rate is too high.
The quinonediazide sulfonic compound includes, for example,
o-quinone diazide compounds such as 1,2-benzoquinone diazide-4-
sulfonic acid, 1,2-naphthoquinone diazide-4-sulfonic acid, 1,2- benzoquinone diazide-5-sulfonic acid and 1,2-naphthoquinone diazide-
5-sulfonic acid; and other quinone diazide sulfonic derivatives. The diazide based photosensitive compound is preferably at least one selected from a group consisting of 1,2-benzoquinone diazide-4-sulfonic
chloride, 1,2-naphthoquinone diazide-4-sulfonic chloride and 1,2-
naphthoquinone diazide-5-sulfonic chloride.
The quinonediazide sulfonic compound itself functions as a dissolution inhibitor to decrease the solubility of novolac resin in
alkaline solutions. However, said compound is decomposed to produce alkali soluble resin during an exposing process and, thereby has a characteristic of accelerating the dissolution of novolac resin in an
alkaline solution.
As the poly hydroxy compound, preferable examples are:
trihydroxybenzophenones such as 2,3,4-trihydroxy benzophenone,
2,2',3-trihydroxy benzophenone, 2,3,4'-trihydroxy benzophenone; tetrahydroxybenzophenones such as 2,3,4,4-tetrahydroxybenzophenone,
2,2',4,4'-tetreahydroxybenzophenone, 2,3,4,5-
tetrahydroxybenzophenone; pentahydroxy benzophenones such as
2,2',3,4,4'-pentahydroxybenzophenone, 2, 2', 3,4,5- pentahydroxybenzophenone; hexahydroxybenzophenones such as
2,3,3',4,4',5'-hexahydroxybenzophenone, 2,2,3,3' ,4,5'-
hexahydroxybenzophenone; gallic alkylester; oxyflavans, etc.
The diazide based photosensitive compound for use in the
present invention is preferably at least one selected from a group consisting of 2,3,4,4-tetrahydroxybenzophenone-l,2-
naphthoquinonediazide-sulfonate, 2,3,4-trihydroxybenzo phenone- 1 ,2- naphthoquinonediazide-5-sulfonate and (l-[l-(4-
hydroxyphenyl)isopropyl]-4-[ 1 , 1 -bis(4-hydroxyphenyl)ethyl]benzene)-
1,2 -naphthoquinone diazide-5-sulfonate. Also, the diazide based photosensitive compound prepared reacting polyhydroxybenzophenone
and a diazide based compound such as 1,2-naphto quinonediazide, 2- diazo-l-naphthol-5-sulfonic acid may be used.
The diazide based photosensitive compound is concretely described in Chapter 7 of Light Sensitive Systems, Kosar, J.; John Wiley
& Sons, New York, 1965.
Such photosensitive compounds (that is, sensitizer) used as a
constitutional ingredient of the resin composition for positive type photoresist according to the present invention is selected from
substituted naphthoquinone diazide based sensitizers generally
employed in positive type photoresist resin compositions, which is
disclosed in, for example, U.S. Patent Nos. 2,797,213; 3,106,465;
3, 148,983; 3,201,329; 3,785,825; and 3,802,885, etc.
The diazide based photosensitive compound described above is
used alone or in combination in an amount of 30 to 80 parts by weight, based on 100 parts by weight of the alkali soluble resin. If less than 30
parts by weight of the diazide based photosensitive compound is used,
the compound does not undergo development in a developing solution
and exhibits drastically reduced residual rate of the photoresist film. In
contrast, if the amount exceeds 80 parts by weight, costs are too high,
thus being economically disadvantageous and, in addition, the
solubility in the solvent becomes lower.
Such a diazide based photosensitive compound is capable of
controlling film speed of the positive type photoresist resin film according to the present invention by procedures including, for example, the control of amount of the photosensitive compound and the control of esterification between the polyhydroxy compound such as 2,3,4-
trihydroxybenzophenone and the quinonediazide sulfonic compound
such as 2-diazo-l-naphthol-5-sulfonic acid.
The diazide based photosensitive compound reduces the solubility of alkali soluble resin in an aqueous alkali developing solution
to about 1/ 100th that prior to exposure. However, after the exposure,
the compound is converted into a carboxylic acid soluble in the alkaline solution, thereby exhibiting a solubility increase of about 1000 to 1500 fold, compared to non-exposed positive type photoresist compositions.
The above characteristic is preferably employed in formation of micro-
circuit patterns for devices such as LCDs, organic ELDs and the like. More particularly, a photoresist applied over a silicon wafer or a glass
substrate is subjected to UV irradiation through a semiconductor mask
in a circuit form, and then, is treated using the developing solution,
resulting in a desired circuit pattern remaining on the silicon wafer or
the glass substrate.
The thermo-curable cross linking agent described above comprises, for example, methoxymethylmelamine based resin and is preferably added to the composition in an amount of 10 to 30 parts by
weight based on 100 parts by weight of the alkali soluble resin. If not less than 10 parts by weight of the thermo-curable cross linking agent is used, the present composition shows excellent alkali- resistance and plating resistance. Furthermore, if the amount is not more than 30
parts by weight, it undergoes more convenient developing process.
As the methoxymethylmelamine based resin, more preferable
example is hexamethoxymethylmelamine resin.
Since the photoresist layer contains the thermo-curable cross linking agent as proposed above, it derives cross-linking reaction of the
thermo-curable cross linking agent during formation of the metal
electrode so as to considerably improve alkali-resistance and plating resistance.
The above sensitivity enhancer may be used for improving
sensitivity of the photoresist layer. The sensitivity enhancer comprises a
polyhydroxy compound which contains 2 to 7 phenol based hydroxy
groups and has a weight average molecular weight less than 1,000
relative to polystyrene. Preferred examples are at least one selected from a group consisting of 2,3,4-trihydroxybenzophenone, 2,3,4,4-
tetrahydroxybenzophenone, 1 -[ 1 -(4-hydroxyphenyl)isopropyl]-4-[ 1 , 1 -
bis(4-hydroxyphenyl)ethyl]benzene.
The polyhydroxy compound serving as the sensitivity enhancer is preferably used in an amount of 3 to 15 parts by weight based on 100
parts by weight of the alkali soluble resin. If less than 3 parts by weight of the polyhydroxy compound is used, it exhibits insignificant
photosensitizing effects and unsatisfactory resolution and sensitivity. When the amount exceeds 15 parts by weight, it exhibits high
sensitivity but narrows window processing margin.
The solvent contained in the positive type photoresist
composition described above is preferably at least one selected from a
group consisting of ethyl acetate, butyl acetate, ethyleneglycol monoethylether acetate, diethyleneglycol monoethylether acetate,
propyleneglycol monoethylether acetate, acetone, methylethyl ketone,
ethyl alcohol, methyl alcohol, propyl alcohol, isopropyl alcohol, benzene, toluene, cyclopentanone, cyclohexanone, ethyleneglycol, xylene,
ethyleneglycol monoethylether and diethyleneglycol monoethylether.
Amount of the solvent in the present inventive composition preferably ranges from 30 to 120 parts by weight based on 100 parts by
weight of the alkali soluble resin so as to enhance coating effect
achieved by the present invention. If less than 30 parts by weight of the solvent is used, it is unsatisfactory to improve film formation and
lamination properties of the photoresist resin layer. In contrast, when
the amount exceeds 120 parts by weight, adhesiveness of the
photoresist resin layer becomes too high and undesirable.
The above photoresist layer and the composition used for forming the photoresist layer may additionally comprise a releasing agent to improve release properties of a supporting film after lamination, other than the above ingredients. Preferred examples of the releasing agent are silicon resin, fluorine resin, olefin resin, wax, etc. Among
these, particularly preferable releasing agent is a fluorine resin with a
viscosity ranging from 1,000 to 10,000cps.
Content of the releasing agent preferably ranges from 0.5 to 4
parts by weight based on 100 parts by weight of the alkali soluble resin.
When the supporting film 10 of the above positive type photoresist film is oriented polypropylene (OPP) film, the OPP film has
superior release properties because of original hydrophobic property in
itself. Therefore, the photoresist layer does not always need to contain
the releasing agent.
However, if the supporting film 10 is polyethylene terephthalate
(PET) film, the film has poor releasing properties caused by original
hydrophilic property in itself. Accordingly, the photoresist layer should contain the releasing agent.
In addition to the above constitutional composition, generally
known components such as additional components such as leveling agents, fillers, pigment, dyes, surfactants and the like and /or additives
for use in conventional photoresist resin compositions may, of course,
be included in the photoresist layer according to the present invention.
As shown in FIG. 1, a photoresist resin film used in the present invention comprises a supporting film 10 and a photoresist layer 20
laminated over the supporting film 10. Occasionally, in order to improve safety of storage and transportation of the positive type photoresist
resin film according to the present invention, the film further includes a
protective layer (not shown in drawings) over the photoresist layer 20.
The photoresist layer 20 normally comprises alkali soluble resin, a diazide based photosensitive compound, a thermo-curable cross linking
agent and a sensitivity enhancer.
The supporting film 10 of the invention should have satisfactory
physical properties for the positive type photoresist film. Examples of suitable supporting film materials include, but are not limited to,
polycarbonate film, polyethylene (PE) film, polypropylene (PP) film, OPP film, PET film, polyethylene naphthalate (PEN) film, ethylenevinyl acetate (EVA) film, polyvinyl film, and any suitable polyolefin films,
epoxy film, etc. Particularly preferable polyolefin film is PP film, PE film,
EVA film and so on. Preferable polyvinyl film is polyvinyl chloride (PVC)
film, polyvinyl acetate (PVA) film, polyvinylalcohol (PVOH) film and the
like. Particularly preferable polystyrene film is polystyrene (PS) film,
acrylonitril/butadiene/styrene (ABS) film and so on. In particular, the
supporting film is preferably transparent to allow light to pass through the supporting film and irradiate the photoresist resin layer.
The supporting film 10 may preferably have a thickness ranging from 10 to 50 μm, preferably 15 to 50 μm, and more preferably 15 to 25 μm, in order to function as a framework for supporting shape of the positive type photoresist resin film.
A method of forming the positive type photoresist resin layer on
the supporting film comprises coating the supporting film with the
admixture of the present inventive composition and the solvent by way
of generally known coating methods using a roller, roll coater, meyer
rod, gravure, sprayer, etc.; and drying the coated film to volatilize the
solvent. If required, the applied composition may be treated by heating
and curing.
Moreover, the photoresist film used in the present invention
may further comprise a protective layer formed on top of the photoresist
layer. Such a protective layer serves to block air penetration and protect the photoresist resin layer from impurities or contaminants and is preferably a polyethylene film, polyethylene terephthalate film,
polypropylene film, etc. and preferably has a thickness ranging from 15
to 30μm.
The substrate coated with the photoresist layer is successively
subjected to pre-baking, exposing, developing and post-baking
processes to cause the photoresist layer to remain as cross-linked in any region of the substrate other than the region which has the metal electrode thereon.
Herein, the post-baking is carried out at 125 to 150°C for 3 to 20 minutes to progress cross-linking reaction of the thermo-curable cross linking agent in the photoresist layer. If the temperature for post-
baking is less than the lower limit, the cross-linking reaction is
insufficient whereby causing a problem such as decrease in plating
properties of the photoresist layer. In contrast, when the temperature exceeds the upper limit, it causes the cross-linking reaction to excessively occur and causes a problem in that it is difficult to release
the photoresist layer from the substrate.
Consequently, the present invention is characterized in that it can remarkably enhance the plating resistance of the photoresist layer
by cross-linking the thermo-curable cross linking agent in the
photoresist layer during the post-baking process.
Next, the substrate partially coated with the photoresist layer described above undergoes a metal plating process to form a metal
electrode only on any region of the substrate which does not have the
photoresist layer formed thereon. Such metal plating process is
conducted under a strong alkali condition of pH 11 to 12 in order to
fulfill fine metal plating on the substrate.
After that, the photoresist layer remaining in the substrate after completion of the above process is removed to produce the metal electrode on the substrate. The produced metal electrode is transferred to a glass substrate by a transcription process in order to fabricate, for
example, Ag electrode for PDP. In this case, the Ag plating process is normally conducted under the strong alkali condition of pH 11 to 12.
Meanwhile, if the substrate of the present invention is made of
insulating materials, the present invention may additionally include (a)
a process of depositing a plating catalyst on the insulating substrate
before formation of patterns on the substrate, and (b) a process of etching the plating catalyst deposited on the region with the photoresist
layer released therefrom, using an etching solution after the releasing
process of the photoresist layer.
The insulating substrate includes a glass substrate, a ceramic
substrate, etc. and the plating catalyst includes palladium (Pd),
platinum (Pt), etc.
Examples of the etching solution for the plating catalyst include,
but are not limited to, hydrofluoric acid, hydrochloric acid, nitric acid,
etc.
The metal plating is electroless metal plating, more particularly,
includes electroless gold plating, electroless silver plating, electroless tin
plating, electroless copper plating, etc.
The electroless metal plating is preferably conducted at 80 ° C for
5 to 20 minutes but can be suitably varied dependent on height of the electrode to be formed.
Furthermore, the present invention may further comprise: (a) a step of etching the substrate with desired patterns; (b) a step of dipping the etched substrate in a coupling agent solution; and (c) a step of
dipping the previously dipped substrate in a plating catalyst solution,
between the pattern formation process and the metal electrode formation process.
More particularly, the patterned substrate undergoes a process
of etching a part of the substrate without the photoresist layer (a part to
be hereafter under the electroless metal plating process). The etching
solution includes, for example, hydrofluoric acid, hydrochloric acid,
nitric acid, etc.
After that, the etched substrate is subjected to a process of
applying the coupling agent to the etched part by dipping the substrate
into the coupling agent solution.
Preferred example of the coupling agent is silane based compounds.
Subsequently, the substrate dip treated with the coupling agent
solution is again subjected to a process of applying the plating catalyst to the etched part by dipping the substrate into the plating catalyst
solution.
Contrary to previously known methods, the present invention described above is characterized in that only a part of the substrate to be electroless metal plated is coated with the plating catalyst by means
of dipping process instead of a deposition procedure.
As a result, the present invention can eliminate a relatively
complex deposition process of the plating catalyst. In addition, since the
present invention can etch the substrate part to be metal plated before
the electroless metal plating, it leads to extension of surface area for the
substrate part to be plated and greatly improves adhesiveness between
the metal electrode and the substrate.
When the present invention additionally includes the deposition
of the metal catalyst and the etching process of the plating catalyst
using the etching solution, or, multiple dipping processes of the
patterned substrate in the coupling agent solution and the plating
catalyst solution in turn after the etching process, the solvent for
forming the photoresist layer is preferably used in an amount ranging
from 190 to 250 parts by weight based on 100 parts by weight of the alkali soluble resin. If less than 190 parts by weight of the solvent is
used, it is unsatisfactory to improve film formation and lamination
properties of the photoresist resin layer. With the above range, the present invention shows superior coating properties.
In order to improve adhesiveness between the photoresist layer
and the deposited plating catalyst in the positive type photoresist
composition, additives such as, for example, isocyanate based compound or the coupling agent can be used.
It is well known that isocyanate based compounds have high reactivity and, in particular, readily react with some compounds having
active hydrogen. Not to be limited to self-reaction thereof, the isocyanate
based compounds also easily react with alcohol, amine, water,
carboxylic acid, epoxide, etc..
Among the coupling agents, especially, a silane based coupling
agent is polymerized by condensation thereof in water at room
temperature. The coupling agent has an organic functional group at one
end while having a methoxy group or ethoxy group at the other end and,
the ethoxy group at the end is hydrolyzed by water to separate ethanol and become Si-OH group. Si-OH group is unstable and converted into Si-O-Si as a siloxane bond so that silane is cross-linked and becomes a
gel state.
Content of the additive preferably ranges from 0.1 to 2 parts by weight based on 100 parts by weight of the alkali soluble resin.
The above described features and other advantages of the
present invention will become more apparent from the following non-
restrictive examples. However, it should be understood that these
examples are intended to illustrate the invention more fully as practical
embodiments and do not limit the scope of the present invention.
(ADVANTAGEOUS EFFECTS)
As described in detail above, the present invention has
advantages in that it can reduce working processes, eliminate deposition of the plating catalyst and considerably reduce loss of metal
ingredients used for manufacturing metal electrode, thereby greatly reducing production cost thereof.
Further, the present invention can more precisely manufacture
the metal electrode by using a photoresist layer with high film speed,
and superior developing contrast, sensitivity and resolution.
The present invention can also eliminate high temperature
treatment and reduce deformation of metal electrode pattern and/ or the substrate.
In addition, the present invention can more securely form the metal electrode on a glass substrate. BRIEF DESCRIPTION OF THE DRAWINGS
The above objects and other aspects of the present invention will be apparent from the following preferred embodiments of the invention
with reference to accompanying drawing in which:
Figure 1 is a cross-sectional view illustrating a positive type
photoresist resin film of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
Example 1
First, a solution comprising: cresol novolac resin as an alkali soluble resin; 34 parts by weight of l,2-naphthoquinone-2-diazide-5-
sulfonic chloride as a photosensitive compound; 15 parts by weight of
hexamethoxymethylmelamine as a thermo-curable cross linking agent;
3.6 parts by weight of 2,3,4-trihydroxybenzophenone as a sensitivity
enhancer; 165 parts by weight of methylethyl ketone and 55 parts by
weight of diethyleneglycol monoethylether acetate as the solvents; and
0.5 parts by weight of fluorine based silicon resin as a releasing agent,
on the base of 100 parts by weight of the above alkali soluble resin, was prepared. The prepared solution was subjected to filtering through a
0.2 μm millipore Teflon™ filter to remove insoluble materials. The
resultant solution was applied to a PET film having a thickness of 19 μm to a thickness of 5 μm to form a positive type photoresist resin film.
After laminating the formed photoresist resin film on a SUS metal plate,
the treated substrate was successively subjected to pre-baking, exposing, developing and post-baking processes to form a photoresist layer on any region of the substrate other than a region which has a
metal electrode formed thereon. Next, Ag electrode was formed on the
region not coated with the photoresist layer by Ag plating process. After separating only the Ag electrode from the SUS metal plate by a releasing
process, the separated Ag electrode was transferred to a glass substrate
by a transcription process to produce the final Ag electrode for PDP. Herein, the post-baking process was performed at 130 ° C for 10 minutes while the Ag plating process was conducted under the strong alkali condition of pH 12. Physical properties of the produced positive type
photoresist resin layer were evaluated and the results are shown in
Table 2.
Examples 2 to 4 and Comparative Example 1
Each of positive type photoresist resin films and Ag electrodes
was prepared in the same manner as in Example 1 , except that content
of hexamethoxymethylmelamine as the thermo-curable cross linking
agent, temperature and working time of the post-baking process, and
pH condition of the Ag plating process were varied as shown in Table 1.
The results of evaluating physical properties of the produced positive
type photoresist resin layers are shown in Table 2. Table 1
Manufacturing condition
Table 2
Results of physical properties evaluation
* In the comparative example 1, since the positive type
photoresist portion was released during the Ag plating process, it was
nearly impossible to produce the Ag electrode. Physical properties as
shown in Table 2 were evaluated by the following methods.
[Sensitivity evaluation]
After exposing each of the laminated substrates with varied
amount of light, the photoresist layer was developed using 2.38 % by
mass of TMAH solution for 60 seconds and washed for 30 seconds then dried. Exposure amount of the resulting layer was measured using an optical microscope.
[Resolution evaluation]
After lamination of the prepared film onto the substrate at a
lamination speed of 2.0m/min, at a temperature of 110 0 C and under a heating roller pressure of 10 to 90psi, the laminated film was subjected
to UV irradiation using the photomask and removal of PET film as the
supporting film. Subsequently, the treated film was developed using 2.38% TMAH alkali developer, resulting in a micro circuit with
unexposed regions. Resolution of the formed micro circuit was observed using the electron microscope. Example 5
A solution comprising: cresol novolac resin as the alkali soluble
resin; 34 parts by weight of l,2-naphthoquinone-2-diazide-5-sulfonic
chloride as the photosensitive compound; 15 parts by weight of
hexamethoxymethylmelamine as the thermo-curable cross linking
agent; 3.6 parts by weight of 2,3,4-trihydroxybenzophenone as the
sensitivity enhancer; and 165 parts by weight of methylethyl ketone and
55 parts by weight of diethyleneglycol monoethylether acetate as the solvents, on the base of 100 parts by weight of the above alkali soluble resin, was prepared. The prepared solution was applied to a SUS metal
plate to a thickness of 3 μm, then successively subjected to pre-baking,
exposing, developing and post-baking processes to form a photoresist
layer on any region of the substrate other than a region which has a
metal electrode formed thereon. Next, Ag electrode was formed on the
region not coated with the photoresist layer by Ag plating process. After
removing the photoresist layer, only the Ag electrode was separated
from the SUS metal plate by the releasing process and transferred to a
glass substrate by the transcription process to produce the final Ag
electrode for PDP. Herein, the post-baking process was performed at 130°C for 10 minutes while the Ag plating process was conducted under
the strong alkali condition of pH 12. Physical properties of the produced positive type photoresist resin layer were evaluated and the results are shown in Table 4. Examples 6 to 8 and Comparative Example 2
Each of positive type photoresist resin layers and Ag electrodes
was prepared in the same manner as in Example 5, except that content
of hexamethoxymethylmelamine as the thermo-curable cross linking agent, temperature and working time of the post-baking process, and
pH condition of the Ag plating process were varied as shown in Table 3.
The results of evaluating physical properties of the produced positive
type photoresist resin layers are shown in Table 4. Table 3
Manufacturing condition
Table 4
Results of physical properties evaluation
* In the comparative example 2, since the positive type photoresist portion was released during the Ag plating process, it was
nearly impossible to produce the Ag electrode. Physical properties as
shown in Table 4 were evaluated by the following methods.
[Sensitivity evaluation]
After exposing each of the produced photoresist resin layers which formed a coating to the thickness of 3 μm with varied amount of
light, the photoresist resin layer was developed using 2.38 % by mass of
TMAH solution for 60 seconds and washed for 30 seconds then dried.
Exposure amount of the resulting layer was measured using an optical
microscope.
[Resolution evaluation]
After coating a substrate with the composition (the solution) prepared as described above to the thickness of 3 μm, the coated
substrate was subjected to UV irradiation using a photomask and the formed coating layer was developed using 2.38% TMAH alkali developer,
resulting in a micro circuit with unexposed regions. Resolution of the
produced micro circuit was observed using an electron microscope.
Example 9
A solution comprising: cresol novolac resin as the alkali soluble resin; 34 parts by weight of l,2-naphthoquinone-2-diazide-5-sulfonic
chloride as the photosensitive compound; 15 parts by weight of hexamethoxymethylmelamine as the thermo-curable cross linking agent; 3.6 parts by weight of 2,3,4-trihydroxybenzophenone as the
sensitivity enhancer; 165 parts by weight of methylethyl ketone and 55 parts by weight of diethyleneglycol monoethylether acetate as the
solvents; and 0.5 parts by weight of fluorine based silicon resin as the
releasing agent, on the basis of 100 parts by weight of the above alkali
soluble resin, was prepared. The prepared solution was subjected to
filtering through a 0.2 μm millipore Teflon™ filter to remove insoluble
materials. The resultant solution was applied to a PET film having a
thickness of 19 μm to a thickness of 5 μm to form a positive type
photoresist film. After laminating the formed positive type photoresist
film on a glass substrate, the treated substrate was successively
subjected to pre-baking, exposing, developing and post-baking processes to form a photoresist layer on any region of the substrate
other than a region which has a metal electrode formed thereon. Next,
the photoresist layer was etched by using hydrofluoric acid, dipped in a silane based compound solution and a Pd solution in turn, and undergoes an electroless Ag plating process to form Ag electrode on a
region of the glass substrate not coated with the photoresist layer. After
removing the photoresist layer from the substrate, the final Ag electrode for PDP was produced. Herein, the post-baking process was performed at 130 ° C for 10 minutes while the Ag plating process was conducted
under the strong alkali condition of pH 12. Physical properties of the produced positive type photoresist resin layer were evaluated and the
results are shown in Table 6.
Examples 10 to 12 and Comparative Example 3
Each of positive type photoresist resin layers and Ag electrodes was prepared in the same manner as in Example 1 , except that content
of hexamethoxymethylmelamine as the thermo-curable cross linking
agent, temperature and working time of the post-baking process, and
pH condition of the silver plating process were varied as shown in Table
5. The results of evaluating physical properties of the produced positive type photoresist resin films are shown in Table 6.
Table 5
Manufacturing condition
Table 6
Results of physical properties evaluation
* In the comparative example 3, since the positive type photoresist portion was released during the silver plating process, it
was nearly impossible to produce the Ag electrode. Physical properties
as shown in Table 6 were evaluated by the same methods with those for evaluating the physical properties shown in Table 2. Example 13
A solution comprising: cresol novolac resin as the alkali soluble
resin; 34 parts by weight of l,2-naphthoquinone-2-diazide-5-sulfonic chloride as the photosensitive compound; 15 parts by weight of
hexamethoxymethylmelamine as the thermo-curable cross linking agent; 3.6 parts by weight of 2,3,4-trihydroxybenzophenone as the sensitivity enhancer; and 219 parts by weight of methylethyl ketone as
the solvent, on the basis of 100 parts by weight of the above alkali
soluble resin, was prepared. The prepared solution was applied to a glass substrate to a thickness of 3 μm to form a positive type photoresist
layer, and the treated substrate was successively subjected to pre-
baking, exposing, developing and post-baking processes to form a photoresist layer on any region of the substrate other than a region which has a metal electrode formed thereon. Next, the photoresist layer was etched by using hydrofluoric acid, dipped in a silane based compound solution and a Pd solution in turn, and undergoes the electroless Ag plating process to form Ag electrode on a region of the
glass substrate not coated with the photoresist layer. After removing the
photoresist layer, the final Ag electrode for PDP was produced. Herein, the post-baking process was performed at 130°C for 10 minutes while
the Ag plating process was conducted under the strong alkali condition
of pH 12. Physical properties of the produced positive type photoresist
resin layer were evaluated and the results are shown in Table 8.
Examples 14 to 16 and Comparative Example 4
Each of positive type photoresist resin layers and Ag electrodes
was prepared in the same manner as in Example 1, except that content of hexamethoxymethylmelamine as the thermo-curable cross linking
agent, temperature and working time of the post-baking process, and
pH condition of the silver plating process were varied as shown in Table
7. The results of evaluating physical properties of the produced positive
type photoresist resin layers are shown in Table 8.
Table 7
Manufacturing condition
Table 8
Results of physical properties evaluation
* In the comparative example 4, since the positive type
photoresist portion was released during the Ag plating process, it was
nearly impossible to produce the Ag electrode. Physical properties as shown in Table 8 were evaluated by the same methods with those for
evaluating the physical properties shown in Table 4.
Example 17
A solution comprising: cresol novolac resin as the alkali soluble resin; 34 parts by weight of l,2-naphthoquinone-2-diazide-5-sulfonic
chloride as the photosensitive compound; 15 parts by weight of
hexamethoxymethylmelamine as the thermo-curable cross linking agent; 3.6 parts by weight of 2,3,4-trihydroxybenzophenone as the
sensitivity enhancer; 165 parts by weight of methylethyl ketone and 55
parts by weight of diethyleneglycol monoethylether acetate as the solvents; and 0.5 parts by weight of fluorine based silicon resin as the releasing agent, on the basis of 100 parts by weight of the above alkali
soluble resin, was prepared. The prepared solution was subjected to
filtering through a θ.2 p millipore Teflon™ filter to remove insoluble
materials. The resultant solution was applied to a PET film having a thickness of 19 f an to a thickness of 5 p to form a positive type
photoresist film. After laminating the formed positive type photoresist
film on a glass substrate having Pd deposit formed thereon as a plating
catalyst, the treated substrate was successively subjected to pre-baking, exposing, developing and post-baking processes to form a photoresist
layer on any region of the substrate other than a region which has a
metal electrode formed thereon. Next, Ag electrode was formed on the region not coated with the photoresist layer by the electroless Ag plating
process. After removing the photoresist layer from the substrate by the
releasing process, the final Ag electrode for PDP was formed by etching the plating catalyst deposited on the region from which the photoresist
layer was released. Herein, the post-baking process was performed at 130°C for 10 minutes while the Ag plating process was conducted under
the strong alkali condition of pH 12. Physical properties of the produced positive type photoresist resin layer were evaluated and the results are
shown in Table 10.
Examples 18 to 20 and Comparative Example 5
Each of positive type photoresist resin films and Ag electrodes was prepared in the same manner as in Example 1, except that content of hexamethoxymethylmelamine as the thermo-curable cross linking
agent, temperature and working time of the post-baking process, and
pH condition of the Ag plating process were varied as shown in Table 9.
The results of evaluating physical properties of the produced positive
type photoresist resin layers are shown in Table 10.
Table 9
Manufacturing Condition
Table 10
Results of physical properties evaluation
* In the comparative example 5, since the positive type
photoresist portion was released during the silver plating process, it
was nearly impossible to produce the Ag electrode. Physical properties
as shown in Table 10 were evaluated by the same methods with those
for evaluating the physical properties shown in Table 2.
Example 21
A solution comprising: cresol novolac resin as the alkali soluble
resin; 34 parts by weight of l,2-naphthoquinone-2-diazide-5-sulfonic
chloride as the photosensitive compound; 15 parts by weight of
hexamethoxymethylmelamine as the thermo-curable cross linking
agent; 3.6 parts by weight of 2,3,4-trihydroxybenzophenone as the sensitivity enhancer; and 219 parts by weight of methylethyl ketone as
the solvent, on the basis of 100 parts by weight of the above alkali
soluble resin, was prepared. The prepared solution was applied to a glass substrate having Pd deposit formed thereon as a plating catalyst,
to a thickness of 3 μm to form a positive type photoresist layer. The
treated substrate was successively subjected to pre-baking, exposing, developing and post-baking processes to form a photoresist layer on any
region of the substrate other than a region which has a metal electrode
formed thereon. Next, Ag electrode was formed on the region not coated with the photoresist layer by the electroless Ag plating process. After removing the photoresist layer from the substrate by the releasing
process, the final Ag electrode for PDP was formed by etching the plating catalyst deposited on the region from which the photoresist layer was released. Herein, the post- baking process was performed at 130 ° C
for 10 minutes while the Ag plating process was conducted under the
strong alkali condition of pH 12. Physical properties of the produced
positive type photoresist resin layer were evaluated and the results are shown in Table 12.
Examples 22 to 24 and Comparative Example 6
Each of positive type photoresist resin layers and Ag electrodes
was prepared in the same manner as in Example 1 , except that content
of hexamethoxymethylmelamine as the thermo-curable cross linking agent, temperature and working time of the post-baking process, and
pH condition of the silver plating process were varied as shown in Table
11. The results of evaluating physical properties of the produced positive type photoresist resin layers are shown in Table 12.
Table 11
Manufacturing Condition
Table 12
Results of physical properties evaluation
* In the comparative example 6, since the positive type
photoresist portion was released during the Ag plating process, it was
nearly impossible to produce the Ag electrode. Physical properties as
shown in Table 12 were evaluated by the same methods with those for
evaluating the physical properties shown in Table 4.
INDUSTRIAL APPLICABILITY
As described above, the present invention is employed in manufacturing metal electrodes such as, for example, Ag electrode for
PDP.
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