JPH03255184A - Adhesive for printed wiring board made by the additive process - Google Patents

Abstract

PURPOSE:To obtain the title adhesive improved in the resistance to electrolytic corrosion and the adhesiveness to deposited copper plating by using a COOH- containing acrylonitrile/butadiene rubber, an alkylphenolic resin, an epoxy resin, and Al(OH)3 as the constituents. CONSTITUTION:Acrylonitrile is copolymerized with butadiene to give an acrylonitrile/butadiene rubber (A) containing at least 3wt.% COOH groups in the molecule. Solid matter consisting of 30-70wt.% component A (solid content after removing organic solvents, the same applies hereinafter), 10-40wt.% alkylphenolic resin (B), 5-50wt.% epoxy resin (C), Al(OH)3 (D) having a mean particle diameter of 0.5-10mum, in an amount of 10-100 pts.wt. based on 100 pts.wt. total solids content of components A, B, and C after removing the organic solvents, and if necessary, 0.01-5.0wt.% catalyst (E) is dissolved or dispersed in an organic solvent (F).

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is directed to improving electrolytic corrosion resistance and adhesion f'E with deposited plated copper.
This invention relates to an adhesive for additive printed wiring boards that has excellent properties.

(Prior Art) As is well known, in printed wiring boards produced by the additive method, necessary wiring patterns are formed on an adhesive-coated insulating substrate by electroless plating.

For example, an adhesive layer for carrying out the plating catalyst is provided on an insulating substrate such as a plating board, which is coated with a plating catalyst, and after masking the area other than the circuit formation area with a plating resist, electroless plating is used as a pretreatment to chromium. The surface of the adhesive layer in the circuit forming area is selectively chemically roughened using an oxidizing etching solution such as sulfuric acid.

After neutralization and washing with water, it is immersed in an electroless copper plating solution to deposit copper on the circuit area to form a wiring pattern.

Adhesives for printed wiring boards using such an additive method generally contain acrylonitrile butadiene rubber or acrylonitrile butadiene rubber containing carboxyl groups at both ends as a main component, and which have excellent adhesion to deposited copper plating. Adhesives that contain thermosetting resin components such as alkylphenol resins or epoxy resins to ensure heat resistance, and inorganic fillers, etc., are proposed to strengthen the adhesive coating and chemically roughen it. It has been.

For example, as such
No. 45-9843.

Special Publication No. Sho 45-9996, Special Publication No. Sho 55-16391
Publication No. 52-31539.

There are Japanese Patent Laid-Open No. 51-28668, etc.

(Problems to be Solved by Hitting) Incidentally, in recent years, with the miniaturization and weight reduction of electronic devices, there has been a demand for higher wiring densities, and accordingly, the spacing between through holes has become narrower.

The viscosity, the electric field generated between adjacent wiring conductors or the conductors on the inner wall of the through pole activates the treatment solution remaining on or inside the insulating substrate supporting the conductor, and the migration of the conductor progresses, resulting in electrolytic corrosion. This makes it difficult to narrow the conductor spacing and screen spacing.

Therefore, in order to perform high-density wiring, it is necessary to reduce only the conductor flux, which has created a limit to increasing the wiring density.

This electrolytic corrosion is thought to be caused by ionic impurities that are washed into the adhesive layer provided on the surface of the insulating substrate, or by residual treatment liquid from the additive method.

Electrolytic corrosion resistance can be improved to some extent by using high-purity materials with a reduced amount of ionic impurities, but if additive process treatment i1k remains, the electrolytic corrosion resistance will not necessarily be improved. It wasn't 1 minute.

This additive process solid treatment liquid tends to remain if the fine voids formed because the filler contained in the adhesive L1 is not uniformly dispersed with the resin or if the uneven shape after chemical roughening is too large.

However, it is important to increase the fine voids in the adhesive coating and the uneven shape after chemical roughening in order to improve the adhesion to the deposited copper.

That is, the resistance to electrolytic corrosion and the adhesion to deposited copper tend to be contradictory, and it has been extremely difficult to satisfy both properties at the same time.

The present invention was made as a result of intensive research and consideration on such problems, and is a high-density wiring that has excellent electrolytic corrosion resistance, is effective against insulation deterioration on the surface of an insulating substrate, and has high adhesion to deposited copper. The present invention provides an adhesive for additive printed wiring boards that is suitable for.

(Means for Solving the Problems) The present invention comprises (A) acrylonitrile butadiene rubber having a carboxyl group in the molecule, (B) an alkylphenol resin, (C) an epoxy resin, and (D) aluminum hydroxide. This invention relates to an adhesive for additive printed wiring boards containing as an essential component.

The acrylonitrile butadiene rubber containing carboxyl groups in the molecule used in the present invention is a copolymer of acrylonitrile, butadiene, and methacrylic acid.

Although the carboxyl group is not particularly limited, it is preferable that the carboxyl group contains 3% by weight or more of Ah-N.

In addition, of the solid content excluding organic solvents, the composition of acrylonitrile butadiene rubber which has carboxyl groups in the molecule is preferably 30% to 70% by weight, and if it is less than 30% by weight, copper will precipitate. The adhesive force with the
Above this level, the electrolytic corrosion resistance decreases.

As the alkylphenol resin, P-phenol, P
- Using P-iW substituted dealkylphenols such as cumylphenol or amylphenol, butylphenol, 5eC-butylphenol or octylphenol.

In addition, the amount of this alkylphenol resin welding agent in the solid content excluding the h'' mechanical solvent is 10% by weight to 40% by weight.
is preferable; if it is less than 10% by weight, the crosslinking with the rubber will be insufficient, resulting in a decrease in heat resistance, and if it is 40% by weight, the adhesive strength with the deposited plated copper will be decreased.

The epoxy resin is not particularly limited, and any resin such as bisphenol A epoxy resin or novolak epoxy resin can be used.

In addition, the amount of the epoxy resin adhesive in the solid content excluding the organic solvent is preferably 5% to 50% by weight.
If it is less than 5% by weight, crosslinking with acrylonitrile butadiene rubber having carboxyl groups will not take 1 minute, and the electrolytic corrosion resistance will not be improved. On the other hand, if it exceeds 50% by weight, the reaction between the rubber and the epoxy resin will proceed too much and the adhesion to the precipitated plated copper will decrease.

The aluminum hydroxide preferably has an average particle size in the range of 0.5 to 10 μm.

The amount of aluminum hydroxide is the total solid content of acrylonitrile butadiene rubber with carboxyl groups in the molecule, alkylphenol resin, and epoxy resin excluding organic solvent: ill, 0 Of'rcffi
If it is less than 10 parts, the uneven shape after chemical roughening will not be uniform and the surface will be locally roughened in deep or shallow parts.

For this reason, the processing solution of additive process solid G tends to remain H, which deteriorates the electrolytic corrosion resistance and makes it impossible to obtain stable adhesion to plated copper.

Furthermore, if the amount of aluminum hydroxide added is more than 100%, the heat resistance may decrease.

In the present invention, the adhesive can contain a plating catalyst that serves as the core of electroless plating.

As the plating catalyst, salts or oxides of metals from Groups 8, IB, and 2B of the Periodic Table of the Elements can be used.

For example, compounds such as platinum, palladium, and tin are used and can be mixed into the adhesive as a solution in which they are dissolved in solid particles or an organic solvent or dissolved and dispersed together with other resins.

The amount of catalyst contained in the adhesive is 0% in the adhesive solids content.
．． 01-5. Range 4 of 3% by weight is preferred.

-! : The adhesive sound component is kneaded in an organic solvent and adjusted to a mixed solution mixture, and the VT machine solvent includes toluene, methyl ethyl ketone, and acetone.

One or more of the following can be used: methyl isobutyl ketone, xylene, diethylene glycol monomethyl ether, diethylene glycol monomethyl ether acetate, ethyl acetate, and the like.

As the insulating substrate on which the adhesive according to the present invention is used, a phenol resin-based or epoxy resin-based resin laminate, or a base layer made of an inorganic or organic composite is used,
The adhesive is applied and dried by heating at a temperature of about 120°C to 190°C.

The thickness of the adhesive coating film is approximately 1011 m to 50 μm.

When depositing electroless plating, the surface of the adhesive is chemically roughened to form a shape suitable for adhesion, and the catalyst for electroless plating is exposed on the surface.

The treatment liquid used for chemical tnization is chromic acid-sulfuric acid.

Chromic acid - sulfuric acid - thorium fluoride, hydrofluoroboric acid - chromic acid, etc. can be used.

As the electroless plating bath, one that can form a copper plating film is generally used.

Holes for mounting electronic components and holes for electrical conduction in the wiring board are made using a punch press or an NC drill machine.

The pattern is formed by screen printing a plating resist or by curing a photomask with ultraviolet light and developing it.

These plating resists are formed before or after the chemical roughening treatment.

(Function) When using the adhesive according to the composition of the present invention, the acrylonitrile butadiene rubber, which has carboxyl groups in its molecules, reacts with the epoxy resin and carboxyl groups in addition to the reaction with the phenol resin, resulting in crosslinking of the rubber. Since the degree L is increased, the movement of copper ions can be suppressed, and the addition of aluminum hydroxide results in a uniformly roughened surface, making it difficult for the processing solution solidified by the additive method to remain.

As a result, the electrolytic corrosion resistance is improved, and the adhesive strength with plated copper is also improved.

(Example) (Example 1) The following composition was dissolved in a mixed solvent of cellosolve acetate and methyl ethyl ketone using a kneader and a stirrer to create an adhesive solution with a solid content of 25%.

A, carboxyl foundation h acrylonitrile butadiene rubber, PNR-1 (manufactured by genuine synthetic rubber ■; product η)
: 50 Heavy Equipment Part B, alkylphenol resin, 5P-126 (manufactured by Schenectady; trade name)
:3CH1'j product part C, epoxy resin, Epicor 1-1
001FR (Made by Yuka Shell Epoxy Resin; Product Name):
30 parts by weight, aluminum hydroxide, Hisilite H-43M (manufactured by Showa Deno Co., Ltd.; trade name): 30 parts by weight E, electroless plating catalyst, PEC-8 (manufactured by Tachi Kasei T-gyo ■; product name)
: 5 parts by weight This adhesive solution was applied to a glass cloth base epoxy resin insulating substrate, LE-168 (Tokyo Kasei T)
The thickness after drying is approximately 25 mm on both sides of the
The adhesive was coated by dip coating to give a thickness of m, and then heated and dried at 170° C. for 60 minutes to prepare an insulating substrate with an adhesive.

On this substrate, photoresist SR-30 for electroless plating is applied.
00 (manufactured by Hitachi Chemical T-gyo ■; Product Ro) is laminated,
After exposure and development with ultraviolet rays, both the conductor width and conductor spacing are 0.
．． 2mm comb pattern, 5mm width and 100m length
A resist for electroless plating was formed so that the adhesive was exposed in a pattern of m and a square pattern of 25 mm on a side.

To chemically roughen this exposed adhesive, chromic acid
Sulfuric acid (chromic acid: 55g/, 5, concentrated sulfuric acid 300m, e/
．． e) G: Soaked at 40°C for 15 minutes, washed with water and neutralized.

Next, it was immersed in an electroless plating solution, CC-41 plating solution (manufactured by Rotatsu Kasei Kogyo ■; trade name) to a thickness of about 30 tlm.
Electroless plating copper was formed, and 5 (pieces) of an additive printed wiring board were created.

(Example 2) An adhesive having the following composition was prepared in the same manner as in Example 1,
A test piece was prepared in the same manner as in Example 1.

A. Carboxyl group-containing acrylonitrile butadiene rubber, PNR-1 (manufactured by Rohonkai Bogomu ■; trade name)
:55 Market Department B. Alkylphenol resin, Hytanol 2400 (manufactured by Rikka Boogyo; iR
iShinro): 30 Market Department C. Epoxy resin, DEN438 (manufactured by Down Chemical Company; trade name) = 201Tr'@part. Aluminum hydroxide, Noidilite H-43M (manufactured by Showa Denshi ■; trade name) 730 parts by weight E. Electroless plating catalyst, PEC-8 (Machi Kasei Ohgyo ■
Product: Product θ) = 5 Vertical Part (Example 3) An adhesive having the following composition was prepared using the same knob method as in Example 1, and a test piece was prepared in the same manner as in Example 1.

A. Carboxyl group Nh acrylonitrile butadiene rubber, PNR-1. (Made of genuine synthetic rubber; product)
:55 parts by weightB. Alkylphenol resin, Hytanol 2400 (manufactured by Takuka Boogyo ■; product name) = 25 Market information. Epoxy resin, Epicoat 100IFR (made by oil-based shell epoxy resin ■; product η): 12.5 middle part, epoxy resin, DEN438 (manufactured by Down Chemical Company; product η): 12.5 type assembly part E. Aluminum hydroxide, Hisilite H-32 (manufactured by Showa Denshi ■;
Commercial name): 30 market volume city information. Electroless plating catalyst, PEC-8 (Machi Kasei Ohgyo ■
Manufactured by: Commercial Armor η): 5 Agile Part (Comparatively 1) In Example 1, instead of the aluminum hydroxide Hisilite H-43M (manufactured by Showa Den Tami; commercial name),
The procedure was the same as in Example 1 except that silium silicate Micropax 2OA (manufactured by Hakusui Kagaku Kogyo ■; trade name) was used.

(Comparative Example 2) In Example 1, a carboxyl group-containing acrylonitrile butadiene rubber, PNR, -1 (manufactured by Romoto Synthetic Rubber Co., Ltd.;
The procedure was the same as in Example 1, except that a carboxyl group-free acrylonitrile butadiene rubber, N23O8 (manufactured by Hyakumoto Synthetic Rubber Co., Ltd.; trade name) was used instead of N23O8 (trade name).

The following tests were conducted on the test pieces prepared as described above.

[Electrolytic corrosion resistance carpet test] At 85°C and 85% RH, a DC voltage of 1
00V was applied continuously, and the insulation resistance value was measured after a predetermined period of time.

In addition, in order to prevent water droplets from adhering between the electrodes during the test, a solder resist was applied by printing on the entire surface between the electrodes.

[Beer strength test] A patterned conductor with a width of 5 mm and a length of 100 mm was
-(, -6481).

[Solder Heat Resistance Test] A 25 mm square pattern was tested at 260° C. to determine the time required for blistering to occur in accordance with J I 5-C-6481.

The results are shown in Table 1.

(Effects of the Invention) As described below, the composition according to the present invention provides an adhesive for additive printed wiring boards that has excellent electrolytic corrosion resistance and excellent adhesion to deposited plated copper. be able to.

Claims (3)

[Claims] 1. An adhesive consisting of the following ingredients used for printed wiring boards on which the necessary circuit patterns are formed by electroless plating. A. Acrylonitrile butadiene rubber with carboxyl groups in the molecule. B. Alkylphenol resin. C. Epoxy resin. D. Aluminum hydroxide. 2. Claim 1, wherein 10 to 100 parts by weight of aluminum hydroxide is contained per 100 parts by weight of the total solid content of acrylonitrile butadiene rubber having a carboxyl group in the molecule, alkylphenol resin, and epoxy resin excluding organic solvents. Adhesive for additive printed wiring boards. 3. Acrylonitrile butadiene rubber having a carboxyl group in the molecule is 30 to 7 in solid content excluding organic solvent.
0% by weight, alkylphenol resin 10-40% by weight
, wherein the epoxy resin is in the range of 5 to 50% by weight.
Adhesive for additive printed wiring boards as described.