JPH053378A - Adhesive composition for printed wiring board - Google Patents

Abstract

PURPOSE:To improve the hollowing resistance of oxidated inner layer copper by constituting the adhesive composition part for a printed wiring board out of thermosetting resin and alkaline metallic carbonate whose surface is hydrophobically treated or alkaline rare earth metallic carbonate whose surface is hydrophobically treated. CONSTITUTION:Thermosetting resin such as epoxy resin, phenol resin, etc., and alkaline carbonate whose surface is hydrophobically treated such as lithium carbonate, sodium carbonate, magnesium carbonate, etc., or alkaline metallic carbonate whose surface is hydrophobically treated are used. For mixture quantity, it is not specified, but carbonate is 200-150wt. portion against 100wt. portion for thermosetting resin. And a harder and further a hardening accelerator are mixed at need to the adhesive composition constituted this way Hereby, the hollowing resistance of the oxidated inner layer copper can be improved remarkably, and also it can be made a binder for a printed wiring beard favorable in electrical insulation reliability.

Description

Detailed Description of the Invention

The present invention relates to an adhesive composition for printed wiring boards, which has excellent haloing resistance.

2. Description of the Related Art Conventionally, an outer layer copper foil is laminated on an inner layer circuit board via a resin layer, and a printed circuit is formed on the outer layer copper foil to form a multilayer printed wiring board (multilayer printed wiring board). Then, in this case, in order to improve the adhesion between the laminated layers, the copper foil of the printed wiring board on which the inner layer circuit is formed is subjected to a blackening treatment (oxidation treatment) with sodium chlorite or potassium persulfate, and the copper foil surface is The needle-like protrusions are formed on the. However, the copper oxide (CuO or Cu ₂ O) on the surface of the copper foil produced by this treatment
Is easily dissolved in acid, so after the through-hole processing after forming the multilayer printed wiring board, the acidity of the plating pretreatment liquid during the through-hole plating process elutes the inner layer copper around the through-hole, that is, There was a problem that "haloing" occurred. This haloing has a serious adverse effect on the thinning and high density of the multilayer printed wiring board.

Various methods have been proposed to prevent the occurrence of this haloing. For example, a method of reducing the inner layer surface to metallic copper resistant to acid while maintaining the surface shape after the inner layer copper oxidation treatment (JP-A-1-223799), a method of treating the inner layer copper by electroetching without oxidizing treatment ( JP-A-2-236993), a method of forming a fine copper rough surface on the inner layer copper surface by electrolysis (JP-A-2-266594), and the like. However, none of them are enough to prevent the occurrence of haloing,
In addition, since a new manufacturing process is provided and it is also necessary to control the treatment liquid or the electrolytic solution, it is complicated.
As another method, although the inner layer copper is oxidized as in the conventional method, an epoxy resin layer is formed on the outer peripheral edge of the through hole portion to improve the adhesion of the through hole portion and prevent haloing. 265594).
However, this method cannot be said to be perfect because it depends only on the adhesion between the resin and the inner layer copper.

[0003]

DISCLOSURE OF THE INVENTION The present invention is an adhesive composition used for forming a laminate of a multilayer printed wiring board, which has a haloing resistance even when laminated using a conventional oxidation-treated inner layer copper. It is an object of the present invention to provide an adhesive composition for a printed wiring board that can be improved.

[0004]

The adhesive composition for a printed wiring board of the present invention comprises a thermosetting resin and a surface-hydrophobicized alkali metal carbonate and / or a surface-hydrophobicized alkaline earth metal carbonate. It consists of and. Less than,
The configuration of the present invention will be described in detail.

(1) Thermosetting resin. For example, epoxy resin, phenol resin, acrylic resin, polyester resin, etc., are not limited to these. As the epoxy resin, epichlorhydrin / bisphenol A type epoxy resin, novolac type epoxy resin,
An alicyclic epoxy resin, a liquid rubber-modified epoxy resin, a flame-retardant brominated epoxy resin, or the like is used. A mixture of these may be used. The phenol resin may be a novolac type or a resol type. It may be a reaction product of phenol and / or substituted phenols and aldehydes.

(2) Carbonate. A surface-hydrophobized alkali metal carbonate and / or a surface-hydrophobized alkaline earth metal carbonate is used. The alkali metal carbonate or alkaline earth metal carbonates, such as lithium carbonate (Li ₂ CO _3), sodium carbonate (Na ₂ CO _3), calcium carbonate (CaCo _3), magnesium carbonate (MgCO _3), barium carbonate (BaCO ₃ ) and the like. All of these carbonates are basic and have a neutralizing effect on acids. By this neutralizing action, the inner copper layer subjected to the oxidation treatment can be protected from the acid, so that the haloing resistance can be improved.
The particle size of these carbonates is 10 μm or less, preferably 1 μm
The following is good. This is because if it exceeds 10 μm, the dispersion of the thermosetting resin and the carbonate becomes too coarse, and the haloing resistance is deteriorated.

Here, the surface hydrophobizing treatment means, for example, a surface treatment with a fatty acid, a resin acid or the like. By this treatment, the carbonate itself becomes hydrophobic, and at the same time, the affinity of the carbonate with the resin is increased and the dispersibility is improved, so that the electrical insulation reliability under high temperature and high humidity is improved. The compounding amount is 100% of thermosetting resin.
From the viewpoint of haloing resistance, it is preferable that the amount of carbonate is 20 parts by weight to 150 parts by weight with respect to parts by weight.

(3) If necessary, the adhesive composition of the present invention thus obtained may further contain other additives, for example, a curing agent depending on the type of resin used, and further a curing accelerator. May be.

[0009]

[Examples] Examples 1 to 8 and Comparative Examples 1 to 6 M compositions having the formulation contents (parts by weight) shown in Tables 1 and 2 were used.
A varnish was prepared by dissolving it in EK (methyl ethyl ketone). Using this varnish, haloing resistance and electrical insulation (Ω) were evaluated as follows.

Evaluation method of haloing resistance. The prepared varnish was applied to a glass epoxy substrate (1.6 mm pressure) with a double-sided BO-treated copper foil (35 μm) on one side and the film thickness after drying was 5
It was coated to a thickness of 0 μm and dried, and then the other surface was similarly coated and dried. Then 170
The varnish was cured in an oven for 1 hour at 0 ° C. Next, FR-4 grade glass prepreg (thickness
0.1 m) copper foil (18 μm) was placed through each of the 3 sheets, and press-cured at a temperature of 170 ° C. for 1 hour at a pressure of 40 kg / cm ² to obtain a copper foil 4-layer board. The drill diameter is 0.8m
The hole drilled at m and a rotation speed of 12000 rpm was dipped in an 18% HCl aqueous solution for 30 minutes to measure the halo size around the inner drill hole. The results are shown in Tables 1 and 2.

A method for evaluating electric insulation. Comb type pattern circuit board (line / space = 0.
2 mm / 0.2 mm) so that the film thickness after drying would be 50 μm, and after drying, curing was performed in an oven at 170 ° C. for 1 hour. The line insulation resistance (DC500V, resistance value after 1 minute application) of the obtained sample was measured. This is the normal value, and then the sample is 85 ℃, 85% RH
Under the conditions, 50V DC was applied for 500 hours, and the line insulation resistance was measured in the same manner. The results are shown in Tables 1 and 2.

[0012]

[0013] From Table 1 and Table 2, the adhesive composition of the present invention (Examples 1 to 8)
Compared with the case where no carbonate was blended (Comparative Example 5),
It can be seen that it has excellent haloing resistance. Further, it is understood that the insulation resistance between lines is less deteriorated and the reliability is high as compared with the case where the surface treatment of carbonate is not performed (Comparative Examples 1 to 4). In Comparative Example 6 in which the particle size of the carbonate is coarse and the surface treatment is not performed, the haloing resistance is inferior and the electrical insulation is also deteriorated by heat.

[0014]

As described above, since the adhesive composition of the present invention remarkably improves the haloing resistance of the conventional oxidation-treated inner layer copper and has a good electric insulation reliability, it can be adhered to a printed wiring board. It is suitable as an agent.

Claims (1)

Claim: What is claimed is: 1. An adhesive composition for a printed wiring board, comprising a thermosetting resin and a surface-hydrophobized alkali metal carbonate and / or a surface-hydrophobized alkaline earth metal carbonate. ..