JPH0753793B2 - Epoxy resin composition for wiring board - Google Patents

Description

TECHNICAL FIELD The present invention relates to an epoxy resin composition for wiring boards, which is excellent in insulating properties, particularly in suppressing metal migration.

[Conventional technology]

With the miniaturization and high performance of electronic devices, the printed wiring boards mounted therein are becoming higher in density by increasing the number of layers, reducing the diameter of through holes, and reducing the hole spacing. For this reason, the demand for electric insulation characteristics of printed wiring boards, which has not been a serious problem until now, has become strict.

Epoxy resins have hitherto been widely used as insulating materials for printed wiring boards. However, along with this increase in density, there has been a problem that a printed wiring board using an epoxy resin is liable to cause insulation failure or conduction breakdown due to metal migration. The metal migration is a phenomenon in which a metal forming wirings, circuit patterns, electrodes, or the like on or in an insulating material migrates on or in the insulating material due to the action of a potential difference in a high humidity environment.

When a dicyandiamite curing type epoxy resin that has been widely used in the past is used as a printed wiring board, its adhesiveness with a copper foil or the like is improved, but it has a high hygroscopicity and has a problem that metal migration easily occurs.

[Problems to be Solved by the Invention]

As a resin excellent in migration prevention, a triazine resin can be mentioned, but it has drawbacks such as a large curing shrinkage at the time of molding, a low adhesive property, and a hardness and brittleness. Further, in the method of adding a triazine compound as an anti-migration agent to an epoxy resin as disclosed in JP-A-63-54300, it is difficult to uniformly disperse the triazine compound, resulting in large variations in characteristics.

The present invention has been made in view of the above circumstances, and provides an epoxy resin composition which, when applied to a material for a printed wiring board, provides excellent electrical insulating properties.

[Means for Solving the Problems]

That is, the epoxy resin composition of the present invention comprises one or more of (a) epoxy resin, (b) dicyandiamide, (c) curing accelerator, (d) hindered phenol antioxidant or sulfur organic compound antioxidant. It is characterized by blending as an essential component.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. The epoxy resin (a) may be any polyfunctional resin, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac. Type epoxy resin, cresol novo hook type epoxy resin, bisphenol A novolac type epoxy resin, bisphenol F
Novolac type epoxy resin, alicyclic epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, hydantoin type epoxy resin, isocyanurate type epoxy resin, aliphatic chain epoxy resin and their halides, hydrogenated products, etc. However, any molecular weight may be used, and it is possible to use several kinds in combination.

The dicyandiamide (b) is preferably added in an amount of 0.3 to 1.0 equivalent (when the number of functional groups of dicyandiamide is 4) with respect to 1 equivalent of the epoxy resin.

As the curing accelerator of (c), an imidazole compound, an organic phosphorus compound, a tertiary amine, a quaternary ammonium salt, or the like is used, and an imidazole compound in which an imino group is masked with acrylonitrile, isocyanate, melamine acrylate, or the like. By using, it is possible to obtain a prepreg having a storage stability that is at least twice that of the conventional one.

Examples of the imidazole compound used here include imidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, and 2-heptadecylimidazole. , 4,5-diphenylimidazole, 2-methylimidazoline, 2-phenylimidazoline, 2-undecylimidazoline, 2
-Heptadecyl imidazoline, 2-isopropyl imidazole, 2,4-dimethyl imidazole, 2-phenyl-
4-methylimidazole, 2-ethylimidazoline, 2
-Isopropylimidazoline, 2,4-dimethylimidazoline, 2-phenyl-4-methylimidazoline and the like, as the masking agent, acrylonitrile, phenylene diisocyanate, toluene diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, methylenebisphenyl isocyanate, melamine There are acrylates.

Several kinds of these curing accelerators may be used in combination, and the compounding amount is preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the epoxy resin. If it is less than 0.01 parts by weight, the promoting effect is small,
If it is more than 5 parts by weight, the storage stability becomes poor.

The antioxidant of (d) uses at least one of a hindered phenol-based antioxidant and a sulfur organic compound-based antioxidant, but when a hindered phenol-based antioxidant is used, other properties such as drill workability are deteriorated. It is possible to improve the electric insulation characteristics without performing the above. As the hindered phenolic antioxidant, butylated hydroxyanisole, 2,
Monophenol compounds such as 6 -di-t-butyl-4-ethylphenol and 2,2'-methylene-bis (4-methyl-)
6- t -butylphenol), 4,4'-thiobis- (3
- methyl-6-t - butylphenol), 4,4'-butylidene bis (3-methyl -6-t-butylphenol)
Bisphenol-based and 1,1,3-tris (2-methyl-4-hydroxy-5-butylphenyl) butane, 1,
3,5-Trimethyl-2,4,6-tris (3,5-di- t -butyl-4-hydroxybenzyl) benzene, tetrakis-
[Methylene-3- (3 ', 5'-di- t -butyl-4'-
There are polymer type phenolic compounds such as hydroxyphenyl) propionate] methane.

Examples of sulfur organic compound-based antioxidants include dilauryl thiodipropionate and distearyl thiodipropionate.

Several kinds of these antioxidants may be used in combination, and the compounding amount is preferably 0.1 to 20 parts by weight with respect to 100 parts by weight of the epoxy resin. When the amount is 0.1 parts by weight or less, the insulating property is not improved, and when the amount is 20 parts by weight or more, the insulating property tends to decrease.

The epoxy resin composition according to the present invention is used in various forms, but a solvent is often used when coating and impregnating a substrate. These solvents include acetone, methyl ethyl ketone, toluene, xylene, methyl isobutyl ketone, ethyl acetate, ethylene glycol monomethyl ether, N, N-dimethylformamide, N, N-dimethylacetamide, methanol and ethanol. You may mix and use it.

The varnish obtained by blending the above (a), (b), (c), and (d) is impregnated into a base material such as glass cloth, non-woven glass cloth or paper, cloth having a component other than glass, and dried in a drying oven. At 80-200
A prepreg for a printed wiring board is obtained by drying in the range of ° C. Prepreg is 150-190 ℃, 20-80kgf / cm ²
It is used for producing a printed wiring board or a metal-clad laminate (hereinafter referred to as MCL) by heating and pressing within the range of.

The drying here means removing the solvent when the solvent is used, and making the fluidity disappear at room temperature when the solvent is not used.

〔Example〕

 The present invention will be further described below based on examples.

Example 1 Brominated bisphenol A type epoxy resin (epoxy equivalent
530) 100 parts by weight dicyandiamide 4 parts by weight 2-ethyl-4-methylimidazole masked with hexamethylene diisocyanate 0.2 parts by weight 4,4'-butylidene bis (3-methyl-6-t-butylphenol) 0.5 parts by weight And dissolved in ethylene glycol monomethyl ether to prepare a varnish having a nonvolatile content of 70%.

Example 2 Instead of 4,4′-butylidene bis (3-methyl-6-t-butylphenol) in Example 1, 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) was used. ) 0.5 parts by weight of butane was blended.

Example 3 Instead of 4,4'-butylidenebis (3-methyl-6-t-butylphenol) in Example 1, tetraxy [methylene-3- (3 ', 5'-di-t-butyl-4'-] was used.
0.5 parts by weight of hydroxyphenyl) propionate] methane was blended.

Example 4 Instead of 4,4'-butylidene bis (3-methyl-6-t-butylphenol) in Example 1, 0.5 part by weight of diralyl thiopropionate was blended.

Example 5 In place of 4,4′-butylidene bis (3-methyl-6-t-butylphenol) in Example 1, 0.25 parts by weight of 4,4′-butylidene bis (3-methyl-6- t -butylphenol) was used. , Diralyl thiopropionate to 0.
25 parts by weight was compounded.

Comparative Example 1 The 4,4′-butylidene bis (3-methyl-6-t-butylphenol) in Example 1 was not added.

A glass cloth having a thickness of 0.2 mm was impregnated with the varnishes obtained in Examples 1 to 5 and Comparative Example 1 and then heated at 140 ° C. for 5 to 10 minutes to obtain a prepreg.

18 μm on each side of the 8 prepregs thus obtained
A thick copper foil was placed, and a double-sided copper-clad laminate was produced under the press conditions of 170 ° C., 90 minutes, and 50 kg / cm ² . Circuit processing was performed on this MCL and a migration test was performed. Through hole drilling was performed using a 0.9 mm diameter drill under the conditions of a rotational speed of 60,000 rpm and a feed rate of 1,800 mm / min.

The hole wall spacing was 350 μm, and the insulation resistance of 400 holes (200 between sley holes / through holes) was measured for each sample over time. The test conditions were 100 V applied in an atmosphere of 85 ° C./90% RH, and the number of days until conduction breakdown occurred between the through holes was measured. The insulation resistance was measured at 100V / 1min.

Solder heat resistance test is conducted at 260 ° C for MCL with double-sided etching.
After 20 seconds of immersion in the solder, the appearance was visually evaluated, and those without blisters were OK and those with blisters were NG.

The gel time of the prepreg was measured at 160 ° C, and the storage stability of the prepreg was evaluated by measuring the gel time of the prepreg immediately after coating and the prepreg after storage at 20 ° C / 40% RH for 60 days. The results are shown in Table 1.

In Examples 1 to 5 in which the antioxidant was blended, the number of days until conduction breakdown became long, and particularly in Examples 1 to 3 in which the hindered phenolic antioxidant was used, the insulating characteristics tended to be improved.

[Effects of the Invention] As is clear from the above description, the epoxy resin composition of the present invention suppresses the occurrence of metal migration and improves the electrical insulation characteristics when applied to the material of the printed wiring board as compared with the prior art. It is a thing.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C08L 63/00 NLB H05K 1/03 D 7011-4E (56) Reference JP-A-60-53524 ( JP, A) JP 61-272246 (JP, A) JP 61-272245 (JP, A) JP 61-278537 (JP, A)

Claims (3)

[Claims] 1. An epoxy resin composition for wiring boards, which comprises the following (a), (b), (c) and (d) as essential components. (A) Epoxy resin (b) Dicyandiamide (c) Curing accelerator (d) One or more of a hindered phenol-based antioxidant or a sulfur organic compound-based antioxidant. 2. The hindered phenolic antioxidant of (d) is butylated hydroxyanisole, 2,6-di-t-.
Butyl-4-ethylphenol, 2,2'-methylene-bis (4-methyl-6-t-butylphenol), 4,4 '
-Thiobis- (3-methyl-6-t-butylphenol), 4,4'-butylidenebis (3-methyl-6-t-)
Butylphenol), 1,1,3-tris (2-methyl-4)
-Hydroxy-5-t-butylphenyl) butane, 1,3,
5-Trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis-
[Methylene-3- (3 ', 5'-di-t-butyl-4'-
The epoxy resin composition for wiring boards according to claim 1, which is a hindered phenolic antioxidant selected from the group of hydroxyphenyl) propionate] methane. 3. The epoxy resin composition for wiring boards according to claim 1, wherein the sulfur organic compound antioxidant of (d) is dilauryl thiodipropionate or distearyl thiodipropionate.