JPH10282659A - Photosensitive resin composition for wiring board, adhesive for electroless plating and printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To expose and cure a composition without acrylating an epoxy resin and to maintain characteristics of an epoxy resin by constituting a resin compsn. of a thermosetting epoxy resin and a photosensitive monomer. SOLUTION: This photosensitive resin compsn. for a wiring board is composed of at least a thermosetting epoxy resin and a photosensitive monomer. The photosensitive resin compsn. for a wiring board is suitable as a plating resist or solder resist. The photosensitive monomer is preferably acryl monomer having plural acrylic groups, and the thermosetting epoxy resin is preferably at least one kind of cresol novolac epoxy resin and alicyclic epoxy resin produced by conversion and modification of naphthol. When the photosensitive resin compsn. for a wiring board is irradiated with light, the photosensitive monomer in the irradiated part is cured by the light to form a mesh structure to fix the thermosetting epoxy resin. Therefore, the thermosetting epoxy resin in the irradiated part does not dissolve in a developer in the developing process after exposure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a photosensitive resin composition for a wiring board, an adhesive for electroless plating, and a printed wiring board, and more particularly to a method for ensuring that exposure curing is achieved without deteriorating the inherent properties of an epoxy resin. This is a proposal for a photosensitive resin composition that can be implemented.

[0002]

2. Description of the Related Art In recent years, electronic equipment has been reduced in size or increased in speed with the progress of the electronic industry. For this reason, printed circuit boards and wiring boards on which LSIs are mounted are also required to have higher densities and higher reliability using fine patterns.

[0003] One of the conventional methods for manufacturing a printed wiring board that meets this kind of demand is an additive method. In the additive method, an adhesive for electroless plating is applied to the surface of a substrate to form an adhesive layer, and after the surface of the adhesive layer for electroless plating is roughened, a conductor is formed by electroless plating. How to

In this method, since a conductor circuit is formed by electroless plating, a high-density wiring with high pattern accuracy can be formed easily and at low cost, compared with an etched foil method (subtractive method) in which a pattern is formed by etching. There is an advantage that it can be manufactured. Moreover, in this method, since the conductor circuit is firmly adhered to the roughened adhesive layer, excellent bonding between the two is ensured.
There is a feature that the conductor circuit is difficult to peel off from the adhesive layer.

As a conventional printed wiring board based on such an additive method, there are the following proposals regarding an adhesive for electroless plating and a plating resist. For example, JP-A-61-276875, JP-A-2-188992, US Pat.
In Japanese Patent Application Publication No. 21 (1999) and the like, there is proposed a printed wiring board using a photosensitive adhesive for electroless plating in which a heat-resistant resin fine powder is dispersed in a photosensitive resin matrix. According to this technique, it is possible to obtain a printed wiring board having excellent peel strength even in a wiring having higher density and higher pattern accuracy.

Japanese Patent Application Laid-Open No. Hei 6-317904 proposes a wiring board using a resist composition comprising a cresol novolak type epoxy resin acrylate and an imidazole hardener as a plating resist. According to this technique, it is possible to obtain a printed wiring board having excellent reliability such as heat resistance and alkali resistance even in a fine pattern.

As described above, a photosensitive resin obtained by acrylizing an epoxy resin is used for the resin layer such as the adhesive for electroless plating and the plating resist of the wiring board from the viewpoint of cost and heat resistance. In particular, an alicyclic epoxy resin or a naphthol-modified cresol novolak type epoxy resin is used as the epoxy resin because it is effective in improving the elongation.

[0008]

However, since these epoxy resins are colored, there has been a problem that even if they are acrylated, they have low photosensitivity and do not cause a photocuring reaction. In addition, since these epoxy resins are acrylated, the inherent properties of the epoxy resin deteriorate, so cracks occur during heat cycles.
There was a problem. In addition, these epoxy resins
If an acid such as methacrylic acid used for acrylation remains in the resin, copper migration occurs under high-temperature and high-humidity conditions, causing a problem of short-circuiting between conductor circuits.

The present invention proposes a technique for solving the above-mentioned problems of the prior art. That is, a main object of the present invention is to provide a photosensitive resin composition for a wiring board that can be cured by exposure without acrylizing an epoxy resin and that can maintain the inherent properties of the epoxy resin.
Another object of the present invention is to provide an adhesive for electroless plating to which the photosensitive resin composition for a wiring board is applied. Still another object of the present invention is to provide a printed wiring board which is excellent in reliability even in wiring with higher density and higher pattern accuracy.

[0010]

Means for Solving the Problems The inventor of the present invention has intensively studied to realize the above object. As a result, they have found that the above-described various problems can be solved by fixing a non-acrylic thermosetting epoxy resin with a photocurable material of a photosensitive monomer and then heating and curing the same.

The photosensitive resin composition for a wiring board of the present invention developed on the basis of such knowledge is characterized by having the following constitution. (1) The photosensitive resin composition for a wiring board of the present invention is characterized by comprising at least a thermosetting epoxy resin and a photosensitive monomer. The photosensitive resin composition for a wiring board is suitably used as a plating resist or a solder resist.

In this photosensitive resin composition for wiring boards,
The photosensitive monomer is desirably a polyacrylic monomer, and the thermosetting epoxy resin is at least one selected from a naphthol-modified cresol novolak type epoxy resin, an alicyclic epoxy resin and a biphenyl type epoxy resin. Desirably a seed.

In this photosensitive resin composition for wiring boards,
The mixing ratio of the thermosetting epoxy resin and the photosensitive monomer is
Thermosetting epoxy resin / photosensitive monomer = 40 by weight ratio
/ 3 to 40/15.

Further, the adhesive for electroless plating of the present invention comprises:
It is characterized by having the following configuration. (2) The adhesive for electroless plating of the present invention is an uncured heat-resistant resin matrix in which cured heat-resistant resin particles soluble in an acid or an oxidizing agent become hardly soluble in an acid or an oxidizing agent by the curing treatment. In the adhesive for electroless plating dispersed therein, the heat-resistant resin matrix is a photosensitive resin composition comprising at least a thermosetting epoxy resin and a photosensitive monomer.

Further, the printed wiring board of the present invention is characterized in having the following configuration. (3) The printed wiring board of the present invention forms a predetermined conductor pattern via an electroless plating adhesive layer and a plating resist provided on a substrate, and supplies a solder body to a mounting surface via a solder resist. In the printed wiring board, a resin matrix of the adhesive layer for electroless plating,
At least one resin layer selected from a plating resist and a solder resist is obtained by curing a photosensitive resin composition comprising at least a thermosetting epoxy resin and a photosensitive monomer.

In this printed wiring board, the adhesive layer for electroless plating is formed by a method in which cured heat-resistant resin particles soluble in an acid or an oxidizing agent become hardly soluble in an acid or an oxidizing agent by the curing treatment. It is desirable that the adhesive for electroless plating, which is dispersed in a cured heat-resistant resin matrix, be cured.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The photosensitive resin composition for a wiring board of the present invention forms a network structure by irradiating light to cure the photosensitive monomer in a portion irradiated with the light. As a result, the thermosetting epoxy resin is fixed. Therefore, the thermosetting epoxy resin in the portion irradiated with the light does not dissolve in the developing solution during the developing process after the exposure. As a result, the opening for forming the via hole, the opening for the plating resist, and the opening for the solder resist can be accurately formed. Further, by heating and curing (post-baking) the thermosetting epoxy resin after the development processing, it is possible to maintain the original properties of the epoxy resin such as chemical resistance (alkali resistance, oxidizing agent resistance, etc.) and heat resistance. .

As described above, according to the photosensitive resin composition for a wiring board of the present invention, the epoxy resin is fixed by the photo-cured body of the photosensitive monomer without being cross-linked and cured by the acrylic group, and is fixed to the developer. Since it becomes insoluble, even a colored epoxy resin such as a naphthol-modified cresol novolak type epoxy resin or an alicyclic epoxy resin can be reliably exposed and cured. Moreover, since the epoxy resin is thermally cured by post-baking, the chemical resistance (such as alkali resistance and oxidizing agent resistance) and the heat resistance do not deteriorate.

In the photosensitive resin composition for a wiring board according to the present invention, as the thermosetting epoxy resin, an alicyclic epoxy resin, a naphthol-modified cresol novolak type epoxy resin, and a biphenyl type epoxy resin are preferably used. The reason is that these resins can improve the fracture toughness value.

As the alicyclic epoxy resin, Araldite CY179 (manufactured by Ciba Geigy), EPICLON HP-7200
(Manufactured by Dainippon Ink Co., Ltd.) is preferred. EPIC of these
The structural formula of LON HP-7200 is shown in (Formula 1).

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The naphthol-modified cresol novolak epoxy resin has the structural formula shown in (Chemical Formula 2).

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The biphenyl type epoxy resin has the structural formula shown in (Chem. 3).

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As the photosensitive monomer, a polyvalent acrylic monomer is preferably used. This is because this polyvalent acrylic monomer has a plurality of acrylic groups in one molecule and is easily crosslinked. Examples of the polyvalent acrylic monomer include Nippon Kayaku's DPE-6A (Chemical Formula 4), Kyoeisha Chemical's R-604 (Chemical Formula 5), and Toagosei Aronix 325.
(Chem. 6), Alonix 315 (Chem. 7) manufactured by Toagosei Co., Ltd. is preferable.

[0024]

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[0025]

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[0026]

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[0027]

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In the photosensitive resin composition for a wiring board of the present invention, the mixing ratio of the thermosetting epoxy resin and the photosensitive monomer is, by weight, thermosetting epoxy resin / photosensitive monomer = 40/3 to 40 / Preferably it is 15. The reason for this is
When the amount of the photosensitive monomer is small, sufficient exposure and curing cannot be performed, and when the amount is large, the curing proceeds too much and the curing reaction proceeds to the back side of the photomask, and the plating resist, the opening for forming a via hole, and the solder resist are hardened. This is because the opening cannot be formed with high accuracy.

The mixed solvent of the thermosetting epoxy resin and the photosensitive monomer is alcohol such as methanol or ethanol, diethylene glycol dimethyl ether (DMD
G) or triethylene glycol dimethyl ether (DM
Preferred are glycol ether solvents such as TG) and N-methylpyrrolidone (NMP). In particular, glycol ether solvents and NMP are desirable because they can dissolve almost all thermosetting resins and thermoplastic resins.

In the present invention, a composite resin may be formed by adding a thermoplastic resin such as polyethersulfone, polysulfone, polyphenylsulfone, or polyphenylene ether in addition to the thermosetting epoxy resin and the photosensitive monomer.

The above-described photosensitive resin composition for a wiring board according to the present invention is suitably used as a resin matrix of a plating resist, a solder resist or an adhesive for electroless plating.

Among these uses, in particular, the adhesive for electroless plating refers to an uncured heat-resistant resin particle which is soluble in an acid or an oxidizing agent and becomes hardly soluble in an acid or an oxidizing agent by the curing treatment. The photosensitive resin composition for a wiring board comprising at least a thermosetting epoxy resin and a photosensitive monomer is applied as the above-mentioned heat-resistant resin matrix in an adhesive for electroless plating dispersed in a heat-resistant resin matrix. " This is another feature of the present invention.

Such an adhesive for electroless plating uses, as a resin matrix, a photosensitive resin composition comprising at least the above-mentioned thermosetting epoxy resin and a photosensitive monomer. Instead of being cured by the cross-linking of the acrylic group, it is fixed and cured by the photocured product of the photosensitive monomer. Therefore, even a bulky epoxy resin such as a naphthol-modified cresol novolac epoxy resin or an alicyclic epoxy resin can be reliably exposed and cured. Moreover, since the epoxy resin is cured by heating in post-baking, the epoxy resin does not deteriorate in chemical resistance (alkali resistance, oxidizing agent resistance), heat resistance and the like. The adhesive for electroless plating is prepared by mixing a water-miscible organic solvent with a heat-resistant resin and heat-resistant resin particles, and kneading the mixture with a three-roller or a homodisper.

The heat-resistant resin particles constituting such an adhesive include heat-resistant resin powder having an average particle size of 10 μm or less, aggregated particles obtained by aggregating heat-resistant resin powder having an average particle size of 2 μm or less, and average particle size. A mixture of a heat-resistant resin powder having a particle size of 2 μm to 10 μm and a heat-resistant resin powder having an average particle size of 2 μm or less
Pseudo particles obtained by adhering at least one of a heat-resistant resin powder having an average particle diameter of 2 μm or less and an inorganic powder to the surface of a heat-resistant resin powder having an average particle diameter of 2 μm to 10 μm. desirable. This is because they can form more complex anchors. As the heat-resistant resin particles, epoxy resin, amino resin (melamine resin, urea resin, guanamine resin) and the like can be used.

Next, a method for manufacturing a printed wiring board using the photosensitive resin composition according to the present invention will be described. (1) First, a wiring board having an inner copper pattern formed on the surface of a core board is manufactured. The copper pattern is formed on the core substrate by etching the copper clad laminate, or
An adhesive layer for electroless plating is formed on a substrate such as a glass epoxy substrate, a polyimide substrate, a ceramic substrate, or a metal substrate, and the surface of the adhesive layer is roughened to a roughened surface, which is then subjected to electroless plating. There is a way. Further, if necessary, an adhesive layer for electroless plating is formed on the wiring substrate, an opening for a via hole is formed in this layer, the surface of the layer is roughened, and electroless plating is performed thereon to form a copper pattern and a via. By repeating the step of forming holes, a multilayer wiring board can be obtained. Note that a through hole is formed in the core substrate, and the wiring layer on the front surface and the wiring layer on the back surface can be electrically connected through the through hole.

(2) Next, an interlayer resin insulating layer is formed on the wiring board prepared in (1). In particular, in the present invention,
It is desirable to use the above-described adhesive for electroless plating as an interlayer resin insulating agent.

(3) After the adhesive layer for electroless plating formed in (2) is dried, openings for forming via holes are provided as necessary. At this time, in the case of photosensitive resin, exposure,
An opening for forming a via hole is provided in the adhesive layer by performing thermosetting after development, or in the case of a thermosetting resin, by performing thermosetting and then laser processing.

(4) Next, the heat-resistant resin particles present on the surface of the cured adhesive layer are dissolved and removed with an acid or an oxidizing agent to roughen the surface of the adhesive layer. Here, examples of the acid include phosphoric acid, hydrochloric acid, sulfuric acid, and organic acids such as formic acid and acetic acid, and it is particularly preferable to use an organic acid. This is because when the roughening treatment is performed, the metal conductor layer exposed from the via hole is hardly corroded. On the other hand, it is desirable to use chromic acid and permanganate (such as potassium permanganate) as the oxidizing agent.

(5) Next, a catalyst nucleus is applied to the wiring board whose surface of the adhesive layer is roughened. It is desirable to use a noble metal ion or a noble metal colloid for providing the catalyst nucleus, and generally, palladium chloride or a palladium colloid is used. Note that it is desirable to perform a heat treatment to fix the catalyst core. Palladium is preferred as such a catalyst core.

(6) Next, a plating resist is formed on the wiring substrate to which the catalyst nucleus has been applied. It is particularly desirable to use the photosensitive resin composition according to the present invention as the plating resist composition.

(7) Next, electroless plating is applied to the portion where the plating resist is not formed to form a conductor circuit including a pad and a via hole to manufacture a printed wiring board. Here, it is desirable to use copper plating as the electroless plating.

(8) Here, a roughened conductive layer may be formed on the surface of the conductive circuit. Examples of the method of forming the roughened layer include an etching process, a polishing process, an oxidation-reduction process, and a plating process. Among these treatments, the roughened layer formed by the oxidation-reduction treatment was composed of NaOH (10 g / l) as an oxidation bath (blackening bath),
It is formed using NaClO ₂ (40 g / l), Na ₃ PO ₄ (6 g / l), and NaOH (10 g / l) and NaBH ₄ (5 g / l) as a reducing bath. When forming a roughened layer by a copper-nickel-phosphorus alloy layer, this alloy layer is deposited by electroless plating. As the electroless plating of this alloy, copper sulfate 1
Up to 40 g / l, nickel sulfate 0.1-6.0 g / l, citric acid
10-20 g / l, hypophosphite 10-100 g / l, boric acid 10
It is desirable to use a plating bath having a liquid composition of 4040 g / l and a surfactant of 0.01〜10 g / l.

(9) Next, a solder resist composition is applied to at least both surfaces of the printed wiring board which has been subjected to the processing up to (7). It is particularly desirable to use the photosensitive resin composition according to the present invention as the solder resist composition.

(10) Next, the coating film of the solder resist composition is dried, and a photomask film having an opening formed thereon is placed on the coating film and exposed and developed, thereby forming a conductive circuit. An opening exposing the pad portion is formed. Here, the opening diameter of the opening may be larger than the pad diameter, and the pad may be completely exposed.

(11) Next, a “nickel-gold” metal layer is formed on the pad portion exposed from the opening. (12) Then, a solder body is supplied onto the pad portion exposed from the opening. As a method of supplying the solder body, a solder transfer method or a printing method can be used. Here, in the solder transfer method, a solder foil is bonded to a prepreg, and the solder foil is etched leaving only a portion corresponding to an opening portion to form a solder pattern to form a solder carrier film. After applying flux to the solder resist opening of the board, laminate so that the solder pattern contacts the pad,
This is a method of transferring by heating. On the other hand, the printing method
This is a method in which a metal mask having a through hole at a position corresponding to a pad is placed on a substrate, and a solder paste is printed and heat treatment is performed.

[0046]

【Example】

[Preparation of Adhesive A1 for Electroless Plating] Alicyclic epoxy resin dissolved in DMDG (diethylene glycol dimethyl ether) (EPICLO, manufactured by Dainippon Ink Co., Ltd.)
N HP-7200) 35 parts by weight, imidazole curing agent (manufactured by Shikoku Chemicals, trade name: 2E4MZ-CN) 2 parts by weight, polyvalent acrylic monomer that is a photosensitive monomer (manufactured by Kyoeisha Chemical, trade name: DP)
E6A) 6.0 parts by weight, 1.5 parts by weight of polyacrylic monomer (manufactured by Nippon Kayaku, trade name: R604), 2 parts by weight of photoinitiator (manufactured by Ciba Geigy, trade name: Irgacure 907), photosensitizer (Nippon Kagaku) 0.2 parts by weight of a drug, trade name: DETX-S) and 0.5 parts by weight of an antifoaming agent (manufactured by San Nopco, trade name: S-65) were mixed, and epoxy resin particles (manufactured by Sanyo Chemical Co., Ltd., Product name: Polymer Pole) average particle size 3.0μ
m with 10.3 parts by weight, average particle size 0.5 μm with 3.09
After mixing, the mixture was further mixed while adding 30 parts by weight of NMP, and the viscosity was adjusted to 7 Pa · s with a modiper stirrer to obtain an adhesive for electroless plating.

[Preparation of Adhesive A2 for Electroless Plating] DM
35 parts by weight of a biphenyl type epoxy resin (manufactured by Mitsubishi Yuka) dissolved in DG (diethylene glycol dimethyl ether), an imidazole curing agent (manufactured by Shikoku Chemicals, trade name: 2E4MZ)
-CN) 2 parts by weight, 6.0 parts by weight of a polyacrylic monomer as a photosensitive monomer (manufactured by Kyoeisha Chemical, trade name: DPE6A)
Polyacrylic monomer (Nippon Kayaku, trade name: R604)
1.5 parts by weight, 2 parts by weight of photoinitiator (manufactured by Ciba-Geigy, trade name: Irgacure 907), 0.2 parts by weight of photosensitizer (manufactured by Nippon Kayaku, trade name: DETX-S), defoamer (manufactured by San Nopco) , Trade name: S-65) 0.5 parts by weight were mixed, and epoxy resin particles (manufactured by Sanyo Chemical Co., trade name:
After mixing 10.3 parts by weight of a polymer pole having an average particle size of 3.0 μm and 3.09 parts by weight of an average particle size of 0.5 μm, the mixture was further mixed while adding 30 parts by weight of NMP, and the viscosity was 7 Pa · s with a modiper stirrer. To obtain an adhesive for electroless plating.

[Preparation of Plating Resist Composition B] 28% by weight of a 50% naphthol-modified cresol novolak type epoxy resin (molecular weight: 3,000 to 5,000) and 20% by weight of a bisphenol A type epoxy resin (oiled shell) dissolved in methyl ethyl ketone Product name: Epicoat 1001) 12 parts by weight,
Imidazole curing agent (Shikoku Chemicals, trade name: 2E4MZ-C
N) 1.6 parts by weight, photosensitive monomer polyvalent acrylic monomer (Nippon Kayaku, trade name: R604) 1.5 parts by weight, photosensitive monomer polyvalent acrylic monomer (Kyoeisha Chemical, trade name: DPE6A) 6.0 parts by weight were mixed, and the mixture was further mixed with 0.36 parts by weight of a leveling agent (manufactured by Kyoeisha Chemical Co., Ltd., trade name: Polyflow No. 75), followed by stirring to obtain a mixed solution X. On the other hand, 2 parts by weight of a photoinitiator (manufactured by Ciba Geigy, trade name: Irgacure 907), 0.2 parts by weight of a photosensitizer (Nippon Kayaku, trade name: DETX-S), and 3 parts by weight heated to 40 ° C. Was dissolved in diethylene glycol dimethyl ether (DMDG) to obtain a mixed solution Y. Then, the mixed liquid X and the mixed liquid Y were mixed and stirred to obtain a liquid resist composition.

[Preparation of Solder Resist Composition C] 50%
28 parts by weight of naphthol modified cresol novolak type epoxy resin (molecular weight 3000 to 5000), 12 parts by weight of 20% by weight bisphenol A type epoxy resin (manufactured by Yuka Shell, trade name: Epicoat 1001) dissolved in methyl ethyl ketone, imidazole cured (Shikoku Chemicals, trade name: 2E4MZ
-CN) 1.6 parts by weight, and 1.5 parts by weight of a polyacrylic monomer which is a photosensitive monomer (trade name: R604, manufactured by Nippon Kayaku)
6.0 parts by weight of a polyacrylic monomer (Kyoeisha Chemical, trade name: DPE6A), also a photosensitive monomer, 2 parts by weight of a photoinitiator (Ciba Geigy, trade name: Irgacure 907), photosensitizer (Nippon Kayaku) (Trade name: DETX-S) 0.2 part by weight and an antifoaming agent (manufactured by San Nopco: S-65) were mixed to obtain a solder resist composition having a viscosity adjusted to 2.0 Pa · s at 25 ° C.

The viscosity was measured using a B-type viscometer (Tokyo Keiki, DVL-B type) at 60 rpm with a rotor No. 4 and 6 rpm.
In the case of rotor No.3.

[Manufacture of Printed Wiring Board] (Example 1) (1) A copper-clad laminate having 18 μm copper foil laminated on both sides of a substrate is used as a starting material, and the copper foil is formed into a pattern according to a conventional method. By etching, inner layer copper patterns were formed on both surfaces of the substrate. (2) The adhesive of A1 was applied to both surfaces of the substrate after the treatment of the above (1) with a roll coater and dried to form an adhesive layer. (3) Place a photomask film with via holes on both sides of the substrate on which the adhesive layer is formed, and apply 400 mJ
/ Cm ² of ultraviolet light. This is spray-developed with a DMTG solution, and the substrate is treated with an ultra-high pressure mercury lamp.
Exposure at 3000mJ / cm ² , 1 hour at 100 ° C, then
By performing heat treatment at 150 ° C. for 5 hours, a 50 μm thick interlayer resin insulating layer (adhesive layer) having a 100 μm φ opening (via hole forming opening) having excellent dimensional accuracy equivalent to a photomask film is obtained. Formed.

(4) Next, the substrate on which the adhesive layer having via hole forming openings is formed is immersed in chromic acid for 2 minutes to dissolve the epoxy resin particles in the resin matrix existing on the surface of the adhesive layer. By removing the adhesive layer, the surface of the adhesive layer was roughened. Thereafter, the adhesive layer was immersed in a neutralizing solution (manufactured by Shipley) and then washed with water. Further, a palladium catalyst (manufactured by Atotech) was applied to the surface of the substrate that had been subjected to the surface roughening treatment (roughening depth: 6 μm), whereby catalyst nuclei were attached to the surface of the adhesive layer and the openings for via holes. (5) The liquid resist composition of B is applied to both surfaces of the substrate subjected to the treatment of the above (4) using a roll coater,
Drying was performed for 30 minutes to form a resist layer having a thickness of 30 μm. Next, a photomask film on which a pattern is drawn is placed on the resist layer, exposed to ultraviolet light of 400 mJ / cm ² and exposed, and after removing the photomask film, DMTG is dissolved and developed. After exposure at 6000 mJ / cm ² with an ultra-high pressure mercury lamp, heat treatment was performed at 100 ° C for 1 hour, and then at 150 ° C for 3 hours. = 37 / 37μm
A permanent resist for plating was formed.

(6) Next, the substrate on which the permanent resist is formed is subjected to a pre-plating treatment (specifically, activation of the catalyst nucleus), and thereafter, by electroless plating using an electroless copper plating bath. Electroless copper plating having a thickness of about 15 μm was deposited on the non-resist-formed portion to form an outer copper pattern and a via hole required as a conductor layer by an additive method.

(7) The solder resist composition of C was applied to both sides of the wiring board thus obtained in a thickness of 20 μm. Next, after drying at 70 ° C. for 20 minutes and at 70 ° C. for 30 minutes, the substrate was exposed to ultraviolet rays of 1000 mJ / cm ² and developed by DMTG. Further, a heat treatment was performed at 80 ° C. for 1 hour, at 100 ° C. for 1 hour, at 120 ° C. for 1 hour, and at 150 ° C. for 3 hours, and the pad portion was opened (opening diameter: 200 μm). Was formed. (8) The substrate on which the solder resist layer is formed is immersed in an electroless nickel plating solution having a pH of 5 consisting of 30 g / l of nickel chloride, 10 g / l of sodium hypophosphite, and 10 g / l of sodium citrate for 20 minutes. Then, a nickel plating layer having a thickness of 5 μm was formed in the opening. Further, the substrate was treated with potassium gold cyanide 2 g / l and ammonium chloride 75 g / l.
l, sodium citrate 50g / l, and sodium hypophosphite 10g / l in an electroless gold plating solution at 93 ° C.
By dipping for 2 seconds, a gold plating layer having a thickness of 0.03 μm was formed on the nickel plating layer. (9) Then, a solder paste was printed on the opening of the solder resist layer and reflowed at 200 ° C. to form a solder bump, thereby producing a printed wiring board having the solder bump.

(Example 2) A printed wiring board having solder bumps was manufactured in the same manner as in Example 1 except that the adhesive A2 for electroless plating was used instead of the adhesive A1 for electroless plating.

Comparative Example 1 Basically the same as in Example 1, but an alicyclic epoxy resin dissolved in DMDG (diethylene glycol dimethyl ether) (trade name: EPICLON HP-7200, manufactured by Dainippon Ink Co., Ltd.) 35% by weight of 25% acrylate, 2 parts by weight of an imidazole curing agent (manufactured by Shikoku Chemicals, trade name: 2E4MZ-CN), a polyvalent acrylic monomer which is a photosensitive monomer (manufactured by Kyoeisha Chemical, trade name: DPE6A)
6.0 parts by weight, polyhydric acrylic monomer (Nippon Kayaku, trade name: R604) 1.5 parts by weight, photoinitiator (Ciba Geigy,
Product name: Irgacure 907) 2 parts by weight, photosensitizer (manufactured by Nippon Kayaku, trade name: DETX-S) 0.2 part by weight, defoamer (manufactured by San Nopco, trade name: S-65) 0.5 part by weight Mix
After mixing 10.3 parts by weight of an epoxy resin particle (manufactured by Sanyo Chemical Industries, trade name: Polymer Pole) having an average particle diameter of 3.0 μm and 3.09 parts by weight of an epoxy resin particle having an average particle diameter of 0.5 μm, the mixture was further mixed. The mixture was mixed while adding 30 parts by weight of NMP, and an adhesive for electroless plating obtained by adjusting the viscosity to 7 Pa · s with a homodisper stirrer was used. In this case, the adhesive for electroless plating did not cure even when exposed to light and was dissolved by development, making it impossible to produce a wiring board.

(Comparative Example 2) Basically the same as in Example 1, except that a 25% acrylated product of a cresol novolak type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., molecular weight 2500) dissolved in DMDG (diethylene glycol dimethyl ether) was used. Parts by weight, 12 parts by weight of polyethersulfone (PES), imidazole curing agent (Shikoku Chemicals, trade name: 2E4MZ-CN)
2 parts by weight, 4 parts by weight of caprolactone-modified tris (acroxyethyl) isocyanurate (trade name: Aronix M325) manufactured by Toagosei Co., Ltd., 2 parts by weight of benzophenone (Kanto Chemical) as a photoinitiator, light 0.2 part by weight of Michler's ketone (manufactured by Kanto Kagaku) as a sensitizer was mixed, and the resulting mixture was mixed with an epoxy resin particle (manufactured by Sanyo Chemical Co., trade name: polymer pole) having an average particle size of 3.
10.3 parts by weight of 0 μm and 0.5 μm average particle size
3.09 parts by weight, antifoaming agent (manufactured by San Nopco, trade name: S-65)
After mixing 0.8 parts by weight, an adhesive obtained by mixing while further adding 30 parts by weight of NMP was used to produce a printed wiring board having solder bumps.

The printed wiring boards of Examples 1 and 2 and Comparative Example 2 manufactured as described above were subjected to a temperature of 135 ° C. and a humidity of 85.
% And a bias of 3.3 V for 48 hours, and the presence or absence of interlayer short-circuit was measured. In addition, a heat cycle test was performed 1,000 times at -55 ° C to 125 ° C, and it was confirmed whether cracks occurred. Table 1 shows the results.

As is clear from the results shown in this table, no interlayer short-circuit or crack was observed in the wiring board of the example, while an interlayer short-circuit or crack was observed in the wiring board of the comparative example. The reason for this is that the adhesive for electroless plating of the comparative example is that the epoxy resin is acrylated, the original properties of the epoxy resin are reduced, and the methacrylic acid used at the time of acrylation remains in the epoxy resin. It is considered that copper migration occurred.

[0060]

[Table 1]

[0061]

As described above, the photosensitive resin composition for a wiring board of the present invention can be cured by exposure without acrylizing the epoxy resin, so that the original properties of the epoxy resin can be maintained. Therefore, the printed wiring board using the photosensitive resin composition for a wiring board of the present invention has no residual methacrylic acid or the like and does not cause interlayer short-circuit due to migration of copper.

Claims (8)

[Claims] 1. A photosensitive resin composition for a wiring board comprising at least a thermosetting epoxy resin and a photosensitive monomer. 2. The photosensitive resin composition for a wiring board according to claim 1, which is used as a plating resist or a solder resist. 3. The photosensitive resin composition for a wiring board according to claim 1, wherein the photosensitive monomer is a polyacrylic monomer. 4. The thermosetting epoxy resin according to claim 1, wherein the thermosetting epoxy resin is at least one selected from a naphthol-modified cresol novolak epoxy resin, an alicyclic epoxy resin, and a biphenyl epoxy resin. Photosensitive resin composition for wiring boards. 5. The wiring board according to claim 1, wherein the mixing ratio of the thermosetting epoxy resin and the photosensitive monomer is 40/3 to 40/15 by weight ratio of the thermosetting epoxy resin / photosensitive monomer. Photosensitive resin composition. 6. Electroless plating in which cured heat-resistant resin particles soluble in an acid or an oxidizing agent are dispersed in an uncured heat-resistant resin matrix which becomes hardly soluble in an acid or an oxidizing agent by the curing treatment. An adhesive for electroless plating, wherein the heat-resistant resin matrix is a photosensitive resin composition comprising at least a thermosetting epoxy resin and a photosensitive monomer. 7. A printed wiring board formed by forming a predetermined conductor pattern via an electroless plating adhesive layer and a plating resist provided on a substrate and supplying a solder body to a mounting surface via a solder resist. In at least one resin layer selected from a resin matrix, a plating resist and a solder resist of the adhesive layer for electroless plating, a photosensitive resin composition comprising at least a thermosetting epoxy resin and a photosensitive monomer A printed wiring board obtained by curing an object. 8. An uncured heat-resistant resin matrix in which a cured heat-resistant resin particle soluble in an acid or an oxidizing agent becomes hardly soluble in an acid or an oxidizing agent by the curing treatment. The printed wiring board according to claim 7, wherein the adhesive for electroless plating dispersed therein is cured.