JP3316015B2 - Heat resistant photosensitive resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant photosensitive resin composition, and more particularly to a solder heat-resist for a printed wiring board, which is excellent in solder heat resistance, flame resistance, plating resistance, chemical resistance, and electric insulation. And an alkali-developable heat-resistant photosensitive resin composition having good adhesion to a substrate, stability over time, and developability.

[0002]

2. Description of the Related Art With the recent increase in the degree of integration in the field of electronic devices, the field of manufacturing printed wiring boards also requires a wiring board having a higher integration degree of semiconductor components and a smaller wiring pattern and insulating pattern line width. It has come to be. For this reason, the conventional method of forming a heat-resistant resin pattern by the screen printing method causes a phenomenon such as bleeding, bleeding or sagging at the time of printing, and cannot cope with high integration of a printed wiring board.

[0003] For this reason, photo-curing type resin compositions and solder-resistant resin compositions, plating-resistant resin compositions and the like have come to be used.
Dry film form, although a lot of liquid forms are commercially available, dry film form photosensitive resin composition, when thermocompression bonding with the substrate, there is also a problem in the adhesion at the step portion and the gap is generated, On the other hand, as the liquid type, there are an organic solvent developing type and an alkaline aqueous solution developing type, but those sufficiently satisfying solvent resistance, acid resistance, heat resistance, flame resistance and plating resistance have been obtained. Did not.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of such problems of the prior art, and has as its object to be particularly useful as a photo solder resist for printed wiring boards. Solder heat resistance, flame resistance,
An object of the present invention is to provide an alkali-developable heat-resistant photosensitive resin composition having excellent plating resistance and chemical resistance, and having good electrical insulation, adhesion to a substrate, stability over time, and developability.

[0005]

Means for Solving the Problems In order to solve the above-mentioned problems, a heat-resistant photosensitive resin composition of the present invention comprises an epoxy group-containing compound represented by the following general formula (2), wherein n is 1 to 3. 2
And R1 to R8 are a hydrogen atom, a halogen element, or a lower alkyl group having 1 to 4 carbon atoms. ) And a compound which reacts with a hydroxyl group of the epoxy group-containing compound to form glycidyl ether, reacts the obtained reactant with an ethylenically unsaturated carboxylic acid, and further reacts with the polycarboxylic acid or (2) one molecule contained in an amount of 10 to 100 parts by weight based on 100 parts by weight of the unsaturated group-containing polycarboxylic acid resin obtained by reacting the anhydride; an epoxy compound having two or more epoxy groups, (3) hex
1 mol of methoxymethyl melamine and hydroxyalkyl
Acrylate or hydroxyalkyl methacrylate 1
It contains a melamine acrylate obtained by reacting with at least one mole and (4) a photopolymerization initiator.

[0006]

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In the present invention, the reaction ratio between the chemical equivalent of the epoxy group of the reactant and the chemical equivalent of the ethylenically unsaturated carboxylic acid is 1: 0.8 to 1: 1.5. Is preferred. It is also preferable that the acid value of these unsaturated group-containing polycarboxylic acid resins is 30 to 160 mg · KOH / g.

Hereinafter, each configuration of the present invention will be described in detail. The epoxy group-containing compound represented by Chemical Formula 2 according to the present invention has a repeating unit n in the formula of 1 to 2 as described above.
R _{1 to} R ₈ can be arbitrarily selected from a hydrogen atom, a halogen element, and a lower alkyl group having 1 to 4 carbon atoms. Examples of such epoxy group-containing compounds include those shown in Chemical Formulas 3, 4 and 5 below.

[0009]

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[0010] The epoxy group-containing compound preferably has a softening point of 50 to 100 ° C.
~ 90 ° C is preferred. The n and R _{1 to} R ₈ are necessarily limited by the range of the softening point. This softening point is 50
When the temperature is lower than 0 ° C, the dryness to the touch is poor, and when the softening point exceeds 100 ° C, the flexibility is poor. The term "dryness to the touch" refers to JI
SK 5400 defines that "gently touching the center of the painted surface with a fingertip, if the fingertip is not stained with the sample, the sample is assumed to be dry to the touch."

The epoxy group-containing compound can be reacted with epichlorohydrin or methyl epichlorohydrin, for example, to give a reaction product in which an epoxy group is added in the form of glycidyl ether to part or all of the hydroxyl groups. This epoxy group needs to be added to at least 50% or more, preferably 80% or more of the hydroxyl group. If this reaction ratio is less than 50%,
It is not preferable because the heat resistance of the finally obtained heat-resistant photosensitive resin composition is extremely reduced.

Next, the reaction product to which the epoxy group has been added is further reacted with an ethylenically unsaturated carboxylic acid in order to impart photopolymerizability. The ethylenically unsaturated carboxylic acid has an ethylenically unsaturated double bond such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, monomethyl maleate, monopropyl maleate, monobutyl maleate, and sorbic acid. Carboxylic acids can be suitably used, and these may be used alone or in combination of two or more. As the esterification catalyst used in the reaction between the epoxy group-containing compound and the ethylenically unsaturated carboxylic acid, secondary and tertiary salts such as diethylamine acetate, diethylamine hydrochloride, and triethylamine can be used.

The reaction ratio between the chemical equivalent of the epoxy group of the reactant and the chemical equivalent of the ethylenically unsaturated carboxylic acid is 1: 0.8 to 1: 1.5 as described above. Is preferred. When the chemical equivalent ratio is less than 1: 0.8, the alkali developability deteriorates and a residue may be left in an unexposed portion of the obtained resist pattern. This ratio is 1:
If it exceeds 1.5, heat resistance and chemical resistance may deteriorate due to insufficient photopolymerization.

Next, the reaction product is reacted with a polycarboxylic acid or its anhydride to add a carboxyl group. Examples of polycarboxylic acids or anhydrides used for this purpose include phthalic acid, maleic acid, succinic acid, phthalic anhydride,
Maleic anhydride, succinic anhydride and the like can be mentioned. The acid value of the unsaturated group-containing polycarboxylic acid resin thus obtained is 3
It is preferable to be 0 to 160 mg · KOH / g. If the acid value at this time is less than 30 mg · KOH / g, alkali developability may be deteriorated.
If it exceeds / g, water resistance and moisture resistance are poor, and good electrical properties may not be obtained.

The epoxy compound according to the present invention having two or more epoxy groups in one molecule includes bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolak type epoxy resin, cresol An epoxidized triazine resin such as a novolak type epoxy resin and tris- (2,3-diepoxypropyl) isocyanurate can be used. Particularly, an epoxidized triazine resin having a triazine skeleton has heat resistance and chemical resistance. And is suitably used.

The epoxidized triazine resin includes:
For example, TEPIC-G, TEPIC- manufactured by Nissan Chemical Co., Ltd.
P, TEPIC-L, TEPIC-S, TEPIC-H
And the like.

The amount of the epoxy compound to be added is 10 to 100 parts by weight based on 100 parts by weight of the unsaturated group-containing polycarboxylic acid resin as described above, but is 20 to 80 parts by weight, and more preferably 30 to 50 parts by weight. Parts by weight are preferred. This addition amount is 1
If the amount is less than 0 parts by weight, the heat resistance deteriorates, and if it exceeds 100 parts by weight, the developability deteriorates, and none of the effects of the present invention can be achieved.

The photopolymerizable monomer according to the present invention includes methyl acrylate, methyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate,
1,6-hexanediol diacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, trimethylolpropane diacrylate, trimethylolpropane dimethacrylate,
Tetramethylol methane triacrylate, tetramethylolpropane tetraacrylate, tetramethylolpropane tetramethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, dipentaerythritol pentaacrylate,
Melamine acrylate, phenol novolac type epoxy resin or cresol obtained by reacting 1,1,1-tri (acryloxypropoxypropoxymethyl) propane, 1 mol of hexamethoxymethylmelamine with 1 mol or more of hydroxyalkyl acrylate or hydroxyalkyl methacrylate There is a reaction product obtained by reacting an epoxy group of a novolak type epoxy resin with acrylic acid or methacrylic acid, and the like, but not limited thereto.

Among the above photopolymerizable monomers, melamine acrylate obtained by reacting 1 mol of hexamethoxymethyl melamine with 1 mol or more of hydroxyalkyl acrylate or hydroxyalkyl methacrylate can be prepared by appropriately adjusting the reaction molar ratio. This is advantageous because 1 to 6 acrylates can be contained therein. Such melamine acrylate is obtained by converting hexamethylolmelamine from melamine to hexamethoxymelamine,
It can be obtained by reacting with hydroxyalkyl acrylate or hydroxyalkyl methacrylate such as hydroxyethyl acrylate or hydroxyethyl methacrylate, hydroxypropyl acrylate and hydroxypropyl methacrylate. Even if such a melamine acrylate is photopolymerized by ultraviolet irradiation, if a methoxy group remains in the melamine acrylate molecule, it is crosslinked and cured by heating, so that the heat resistance can be further improved.

The above photopolymerizable monomer is used in an amount of 10 to 100 parts by weight based on 100 parts by weight of the unsaturated group-containing polycarboxylic acid resin.
It is preferred to be contained in parts by weight. If this content is less than 10 parts by weight, poor photocuring may occur, making it difficult to obtain sufficient heat resistance and chemical resistance. On the other hand, if it exceeds 100 parts by weight, the tackiness of the surface after drying may increase, and the workability may decrease.

As the photopolymerization initiator according to the present invention, all conventionally known photopolymerization initiators can be used. Specifically, benzophenone derivatives such as benzophenone, 4,4′-bis (dimethylamino) benzophenone, anthraquinone,
Methylanthraquinone, 2-ethylanthraquinone, t
anthraquinone derivatives such as tert-butylanthraquinone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin alkyl ether derivatives such as benzoin propyl ether, acetophenone,
2,2-dimethoxy-2-phenylacetophenone,
Acetophenone derivatives such as 2,2-diethoxyacetophenone, thioxanthone derivatives such as 2-chlorothioxanthone, diethylthioxanthone and diisopropylthioxanthone, acetophenone, dimethoxyphenylacetophenone, 2-hydroxy-2-methylpropiophenone, 4′-isopropyl-2 -Hydroxy-2-
Acetophenone derivatives such as methylpropiophenone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-1-propanone, Michler's ketone,
Benzyl and the like, but are not limited thereto.

One or more of the above photopolymerization initiators are used in an amount of 0.1 to 0.1% based on the total weight of the unsaturated group-containing polycarboxylic acid resin, epoxy compound and photopolymerizable monomer.
It can be added in the range of 20% by weight.

In the present invention, other components can be added as required. For example, as a tackiness improver, a compound having a carboxyl group and an N-alkoxyacrylamide group, or a copolymer of styrene and maleic anhydride as a compound which is solid at room temperature, is soluble in alkali, and polymerizes or crosslinks by light or heat. It is possible to use a compound obtained by reacting hydroxyethyl methacrylate with a polymer or the like.

Further, an epoxy curing agent may be blended,
Commonly known amine-based curing agents, acid anhydride-based curing agents, phenolic resins, melamine resins, cationic epoxy curing agents, and the like can be used, but in the present invention, amine-based epoxy curing is particularly preferred since sensitivity is less affected. It is preferable to use an agent and a cationic epoxy curing agent. Examples of such an epoxy curing agent include 2-methyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, and isocyanuric acid adduct of 2-methylimidazole ( Shikoku Chemical Industry Co., Ltd .: 2MZ-OK), 1-
(4,5-diamino-2-triazinyl) -2- (2-
Imidazole compounds such as methyl-1-imidazolyl) ethane (2MZ-AZINE, manufactured by Shikoku Chemical Industry Co., Ltd.), tertiary amines such as benzylmethylamine and dimethylaminomethylphenol, boron trifluoride monoethylamine, and boron trifluoride Amino complex compounds such as ethanolamine, and a cationic epoxy curing agent that generates a Lewis acid upon irradiation with ultraviolet rays (CG-2: CG-2)
61) is effective.

These epoxy curing agents are used in an amount of 1 to 20% by weight, preferably 2 to 20% by weight, based on the epoxy compound.
The range is from 10 to 10% by weight. When the amount of the epoxy curing agent used is less than 1% by weight, it takes a long time for heat curing, and the effect as the epoxy curing agent is not exhibited. 20
If the amount is more than the weight%, the stability will be poor.

In addition to the above, silicone-based or fluorine-based antifoaming agents, polymerization inhibitors such as hydroquinone and hydroquinone monomethyl ether for preventing gelation and improving storage stability, coloring agents such as dyes and pigments, silica,
Fillers such as talc, barium sulfate and calcium carbonate can be added.

As the solvent for dissolving the heat-resistant photosensitive resin composition of the present invention, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether,
Ether solvents such as propylene glycol monomethyl ether, diethylene glycol monoethyl ether, dipropylene glycol monomethyl ether, and their acetate solvents, ester solvents such as methyl acetate, ethyl acetate, and butyl acetate; and methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Ketone solvents can be used.

A petroleum-based solvent can be used as a diluent for the purpose of adjusting the viscosity and the like. Examples of such a petroleum-based solvent include swazole (manufactured by Maruzen Petrochemical Co., Ltd.) and Solvesso (manufactured by Tonen Petrochemical Co., Ltd.).

[0029]

The composition of the present invention uses an aromatic compound having a plurality of ethylenically unsaturated bonds and a carboxyl group in a molecule, so that photopolymerization excellent in heat resistance, chemical resistance, plating resistance and the like is achieved. A possible alkali-soluble resin composition is formed.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. Synthesis Example 1 Epoxy group-containing compound represented by Chemical Formula 3 (Epicoat 100
1: Bisphenol A type epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd., average degree of polymerization 1.7, softening point 64 ° C.) 10
60 g and 235 g of epichlorohydrin were reacted in the presence of a strong alkali to obtain a reaction product. This reaction product had an epoxy group added to all the hydroxyl groups of the epoxy group-containing compound. Next, acrylic acid 18 was added to 1205 g of the reaction product.
8 g was added and reacted. The chemical equivalent ratio between the epoxy group and acrylic acid of the reactant was 1: 1. further,
1393 g of this reaction product was added to 39 parts of tetrahydrophthalic anhydride.
1 g was reacted to obtain an unsaturated group-containing polycarboxylic acid resin (A-1) according to the present invention. The acid value of this resin is 101.
It was 3 mg · KOH / g.

Synthesis Example 2 The epoxy group-containing compound of Synthesis Example 1 was coated with Epicoat 828.
(Yasuka Shell Epoxy Co., Ltd., bisphenol A type epoxy resin, average polymerization degree 0.14, liquid at room temperature) except that the unsaturated group-containing polycarboxylic acid resin (A- 2) was obtained. The acid value of this resin is 97.4
mg · KOH / g.

Synthesis Example 3 40 parts by weight of methyl methacrylate, 25 parts by weight of styrene,
A polymerization reaction was carried out by mixing 25 parts by weight of methacrylic acid and 10 parts by weight of N-iso-butoxymethylacrylamide to obtain a copolymer (B-1) as a tackiness improver. The average molecular weight of this copolymer was 50,000, and the softening point was 150 ° C.

Examples 1 to 4 and Comparative Examples 1 and 2 Solder resist ink compositions were blended according to the blending compositions shown in Table 1 below and kneaded with a three-roll mill. This is applied to the entire surface of the copper through-hole printed wiring board by screen printing so that the film thickness after drying is 15 to 25 μm,
After the coating film was preliminarily dried at 75 ° C. for 15 minutes, the back surface was similarly printed and preliminarily dried at 75 ° C. for 25 minutes. With respect to the obtained wiring board, a test for [touch dryness] described later was performed.

[0034]

[Table 1]

The compounds having trade names in Table 1 are as follows. TEPIC: manufactured by Nissan Chemical Co., Ltd .: Tris (2,3-diepoxypropyl) isocyanurate epicoat 1001 manufactured by Yuka Shell Epoxy Co., Ltd .:
Bisphenol A type epoxy resin SP-4010: manufactured by Showa Polymer Co., Ltd .: phenol novolak type epoxy acrylate KAYARAD DPHA: manufactured by Nippon Kayaku Co., Ltd .: dipentaerythritol hexaacrylate NK ester A-BPE-4: new Nakamura Chemical Co., Ltd.
Manufactured by: 2,2-bis [4- (acryloxydiethoxy) phenyl] propane nicarac MX-302: manufactured by Sanwa Chemical Co., Ltd.
Reaction product of hexamethoxymethylated melamine and hydroxyethyl methacrylate Irgacure 907: Ciba Geigy: benzophenone photopolymerization initiator KAYACURE DETX: Nippon Kayaku Co., Ltd .: diethylthioxanthone

Next, the solder mask pattern film is brought into contact with the coating surface and exposed with a light amount of 400 mJ / cm ² , and then the unirradiated portion of the coating film is sprayed using a 1.0% by weight aqueous sodium carbonate solution. The solution was developed at a pressure of 2.0 kg / cm ² and a liquid temperature of 30 ° C. for 80 seconds, and dissolved and removed. The obtained [developability] and [development resistance] were evaluated as described below.

Thereafter, the coating was cured by heating at 150 ° C. for 60 minutes using a hot air drier.
[Coating film hardness], [Adhesion], [Solder heat resistance],
[Acid resistance], [Alkali resistance], and [Solvent resistance] were tested. The results of each of these tests are shown in Table 2 below. As is clear from Table 2, the heat-resistant photosensitive resin composition according to the present invention showed excellent results in all test items.

[0038]

[Table 2]

The test method and the evaluation method of each of the above tests are as follows. [Touch dryness] After leaving to cool for 10 minutes, JIS
It was determined according to K5400. …: No tack was observed at all △: Slight tack was observed × :: Tack was noticed XX: Ink adhered to the finger

[Developability] The developability was visually determined using a magnifying glass. △: Completely developed ×: Some parts are not thinly developed ××: Some parts are not developed

[Development resistance] The state of the coating film was visually determined. Δ: no change was observed ×: gloss of the coating film surface decreased ××: a part of the coating film was peeled off

[Coating film hardness] The hardness of the coating film is JIS K54.
It was measured according to 00. The hardness in Table 2 is based on the hardness of the pencil lead.

[Adhesion] According to the test method of JIS D0202, the coating film was cut into a cross-cut in a grid pattern to obtain 1
After making 00 cells, a peeling test was performed using cellophane tape.
In accordance with IS D0202, the number of cells that did not peel out of 100 cells was examined and evaluated.

[Solder Heat Resistance] Immersion of the test piece in a solder bath at 260 ° C. for 10 seconds was repeated five times, and the change in appearance was examined. Δ: No change in appearance ×: Discoloration of the coating film is observed ××: Floating, peeling, and solder dipping of the coating film Note) The solder used was JS-64P manufactured by Yamaei Chemical Co., Ltd. .

[Acid Resistance] A test piece was immersed in a 10% by volume aqueous sulfuric acid solution at 25 ° C. for 30 minutes, and the appearance change of the coating film was visually examined. At the same time, the adhesion after acid immersion was examined in the same manner as in the above [Adhesion]. Δ: No change in appearance and no peeling of coating film ×: No change in appearance, but slight peeling of coating film ××: Floating of coating film is observed and peeling is large in peeling test thing

[Alkali Resistance] A test piece was immersed in a 10% by weight aqueous solution of sodium hydroxide at 25 ° C. for 30 minutes, and the same test as the acid resistance test was performed to evaluate.

[Solvent resistance] A test piece was placed in methylene chloride for 25 minutes.
The sample was immersed at 30 ° C. for 30 minutes, and the appearance change was observed. △ …… No change in appearance ×× …… Swelled and permeated

[0048]

As described above, the heat-resistant photosensitive resin composition of the present invention is excellent in solder heat resistance, flame resistance, plating resistance and chemical resistance, and has electrical insulation and adhesion to a substrate. Because of its excellent stability over time and alkali developability, it is particularly suitable as a photo solder resist for printed wiring boards.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI H01L 21/027 H05K 3/28 D H05K 3/28 H01L 21/30 502R (56) References JP-A-5-32746 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03F 7/004 503

Claims (3)

(57) [Claims] (1) An epoxy group-containing compound represented by the following general formula (1), wherein n is 1 to 20,
1 to R8 are a hydrogen atom, a halogen element, or a carbon number 1 to
4 is a lower alkyl group. ) And a compound which reacts with a hydroxyl group of the epoxy group-containing compound to form glycidyl ether, reacts the obtained reactant with an ethylenically unsaturated carboxylic acid, and further reacts with the polycarboxylic acid or (2) 10 to 1 part by weight based on 100 parts by weight of the unsaturated group-containing polycarboxylic acid resin obtained by reacting the anhydride.
An epoxy compound having two or more epoxy groups in one molecule contained in 00 parts by weight, and (3) hexamethoxymethyl
1 mol of melamine and hydroxyalkyl acrylate
Or 1 mole or more of hydroxyalkyl methacrylate
A heat-resistant photosensitive resin composition comprising melamine acrylate obtained by the reaction and (4) a photopolymerization initiator. Embedded image 2. The method according to claim 1, wherein the chemical equivalent of the epoxy group contained in the reactant and the chemical equivalent of the ethylenically unsaturated carboxylic acid are reacted in a ratio of 1: 0.8 to 1: 1.5. heat-resistant photosensitive resin composition according to 1. 3. A heat-resistant photosensitive resin composition according to claim 1 or 2 acid value of the unsaturated group-containing polycarboxylic acid resin is characterized in that 30 to 160mg · KOH / g.