JP2621504B2 - Adhesive composition for printed wiring boards - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a printed wiring board by an additive method, which has good adhesion to copper deposited by electroless plating and has excellent corrosion resistance between plated copper circuits. The present invention relates to an adhesive composition.

[Conventional technology]

A printed wiring board by the additive method forms a wiring pattern on an insulating substrate with an adhesive by electroless plating.
For example, an adhesive layer containing a plating catalyst is provided on an insulating substrate of a laminate, and a portion other than a circuit forming portion thereof is masked with a plating resist, and then first treated with an oxidizing etching solution such as chromic sulfuric acid to chemically roughen. Then, when the substrate is treated with an electroless copper plating solution, copper is deposited on the circuit portion to form a circuit.

Adhesive for providing the above adhesive layer, acrylonitrile butadiene rubber excellent in deposition plating and adhesion is generally used, and a phenol resin to further heat resistance, a thermosetting resin component such as an epoxy resin, In addition, an inorganic filler is appropriately blended in order to supplement reinforcement after application of the adhesive and to compensate for chemical roughening.

[Problems to be solved by the invention]

In recent years, circuit pattern intervals have become narrower with the increase in density of printed wiring boards, and the occurrence of dendrites due to copper migration between patterns under an electric field has become a problem. The generation of dendrites is considered to occur because migration with copper tends to occur due to the rubber component in the adhesive. Conventionally, as a countermeasure to prevent this phenomenon, a thermosetting resin such as an epoxy resin or a phenolic resin having a cross-linking property with rubber is blended to reduce the ratio of rubber to reduce the generation of dendrites.

However, according to this conventional method, the chemical roughening property during the plating pretreatment step is remarkably reduced, and the adhesion strength of the plated copper is insufficient.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a printed wiring board which is excellent in adhesion to deposited copper and has excellent electrical corrosion resistance in the production of a printed wiring board by an additive method.

[Means for solving the problem]

In order to achieve the above object, the present invention relates to an adhesive for a printed wiring board, wherein 1 to 20 parts by weight of an alkylated melamine is compounded with respect to 100 parts by weight (hereinafter referred to as "part") of a mixture of acrylonitrile butadiene rubber and a thermosetting resin. Agent composition.

If the addition amount of the alkylated melamine is less than 1 part, the effect of suppressing adhesion to the plated copper and dendrite is small,
If the amount exceeds 20 parts, the crosslinkability of the rubber decreases and the heat resistance deteriorates. Preferably, 5 to 10 parts is appropriate.

[Action]

Regarding the compounding ratio of the acrylonitrile butadiene rubber and the thermosetting resin in the present invention, when the ratio of the thermosetting resin is 40% or more, the generation of dendrite is reduced, but the entire adhesive becomes rigid and the chemical roughening property is reduced. The adhesive strength with the plated copper becomes insufficient.

When an alkylated melamine is added, the triazine ring has a chelating effect with copper, so that the triazine ring has an effect of increasing the adhesion to the plated copper and suppressing the generation of dendrites.

〔Example〕

(Example 1) Acrylonitrile butadiene (N-230, Nippon Synthetic Rubber Co., Ltd.)
S) 50 parts Alkyl phenol resin (Hitachi Chemical Hitachino 2400) 25
Parts Epoxy resin (Shell Epicoat 1001) 10 parts Filler zirconium silicate (Hakusui Chemical Micropax 20A) 25 parts Plating catalyst (Hitachi Chemical PFC-8) 5 parts Methylated melamine (Hitachi Chemical Melamine 523) 10 parts It was dissolved and dispersed in cellosolve acetate using a kneader to prepare an adhesive solution having a solid content of 22%. This adhesive was dip-coated on both sides of a substrate in which a glass fiber base material was impregnated with an epoxy resin so that the film thickness after drying was 25 μm, and dried by heating to obtain an insulating substrate with an adhesive. Line / space is 0.2 / 0.2m by photoresist on this substrate
A m-shaped dendrite evaluation comb pattern and a test pattern consisting of 25 mm square and 100 × 50 mm for measuring solder heat resistance and peel strength were prepared and cured by heating. Next, the adhesive surface of the pattern portion was selectively treated with a NaF-based roughening solution to be chemically roughened and neutralized by washing with water. Subsequently, it was put into an electroless plating bath to precipitate copper having a thickness of 30 μm, washed with water and dried to obtain a test pattern of an additive printed wiring board. The test pattern for measuring the peeling strength used was a test piece having a size of 100 × 50 mm and etched to a width of 5 mm.

To facilitate this, the corrosion resistance test should be performed at 85 ° C and 85 ° C.
In a heated and humidified state at% RH, DC 100 V was applied between the electrode circuits to continuously supply current, and sampling was performed at predetermined time intervals to check for the occurrence of dendrite between the circuits.

Solder heat resistance and peel strength were measured according to JIS C6481.

(Example 2) Acrylonitrile butadiene (Zeon Corporation DN-406) 6
0 parts Alkylphenol resin (Schenectady SP-126) 3
0 parts Epoxy resin (Dow Chemical DEN-438) 10 parts Filler zirconium silicate (Hakusui Chemical Micropax 20A) 25 parts Plating catalyst (Hitachi Chemical PEC-8) 6.9 parts Butylated melamine (Hitachi Chemical Melan X66) 8 parts or more Was treated in the same manner as in Example 1 to prepare an adhesive solution, and a test pattern of an additive printed wiring board was obtained.

(Comparative Example 1) A test pattern was prepared using the adhesive obtained in Example 1 except that methylated melamine was not added.

(Comparative Example 2) A test pattern was prepared using the adhesive obtained in Example 2 except that butylated melamine was not added.

Table 1 shows the test results obtained in the above Examples and Reference Examples.

[Effect of the Invention] The additive method printed wiring board using the adhesive composition of the present invention is less likely to generate dendrites, is excellent in electric corrosion resistance, and does not impair heat resistance, and also has a peeling strength of deposited copper. At a high level.

Further, when specifically described with reference to Table 1, the difference in the performance between the example and the comparative example is clear. Regarding the difference between Examples 1 and 2, there was no generation of dendrites in Example 1 because the addition ratio of alkylated melamine was large, and in Example 2, there was little generation of dendrites because the addition ratio of alkylated melamine was small. Is recognized. Further, in each of Comparative Examples 1 and 2, no alkylated melamine was added, and as a result, the generation of dendrites was remarkable and the adhesiveness was poor.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication location C09J 163: 00) (72) Inventor Toshiro Oka 1500 Ogawa Oji, Shimodate City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. (72) Inventor Noriyoshi Fukuoka 413 Kushita, Ninomiya-cho, Haga-gun, Tochigi Pref.

Claims (1)

(57) [Claims] An adhesive composition for printed wiring boards comprising 100 parts by weight of acrylonitrile butadiene, a thermosetting resin and 1 to 20 parts by weight of an alkylated melamine resin.