JPH0339320A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain the title composition suppressing metal migration, improving electrical insulating characteristics in application to materials of printed circuit boards, comprising an epoxy resin, dicyandiamide, curing promoter and reducing agent as essential components. CONSTITUTION:The aimed composition comprising (A) an epoxy resin (e.g. bisphenol A type epoxy resin), (B) dicyandiamide, (C) a curing promoter (e.g. imidazole) and (D) a reducing agent (preferably phenolic reducing agent such as 1,2,3-trihydroxybenzene) as essential components. The blending ratio is preferably 0.3-1.0 equivalent based on 1 equivalent component A, 0.01-5 pts.wt. component C and 0.1-20 pts.wt. component D based on 100 pts.wt. component A.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an epoxy resin composition that has excellent insulation properties, particularly in suppressing metal migration.

[Conventional technology]

BACKGROUND ART As electronic devices become smaller and more sophisticated, the printed wiring boards mounted thereon are becoming more dense due to higher multilayers, smaller diameter through holes, and shorter hole spacing. For this reason, demands on the electrical insulation properties of printed wiring boards, which have not been much of a problem in the past, have become stricter.

Epoxy m11M has been widely used as an insulating material for printed wiring boards. However, with this increase in density, a problem has arisen in that printed wiring boards using epoxy resin are susceptible to insulation failure and conduction breakdown due to metal migration.

Metal migration is a phenomenon in which metal constituting wiring, circuit patterns, electrodes, etc. on or within an insulating material migrates on or within the insulating material due to the action of a potential difference in a high humidity environment.

Dicyandiamide curing epoxy resin, which has been widely used in the past, has improved adhesion to w4Fi etc. when used in printed wiring boards, but has a problem in that it has high hygroscopicity and is susceptible to metal migration.

(31 problems to be solved by the invention) Triazine resins are examples of resins that are excellent in preventing migration, but they have drawbacks such as large curing shrinkage during molding, low adhesiveness, and being hard and brittle. ing. Furthermore, in the method of adding a triazine compound as a migration silane inhibitor to an epoxy resin as disclosed in JP-A-6354300, it is difficult to uniformly disperse the triazine compound, resulting in large variations in properties.

The present invention was made in view of this situation, and provides an epoxy resin composition that provides excellent electrical insulation properties when applied to materials for printed wiring boards.

[Means to solve the problem]

That is, the epoxy resin of the present invention is (a)
It is characterized by containing an epoxy resin (b) dicyandiamide (c) a curing accelerator (d) a reducing agent as essential components.

The epoxy resin (a) used in the detailed explanation of the present invention may be any polyfunctional epoxy resin, such as bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, phenol novolak. Type epoxy resin, Talesol novolac type epoxy resin, Bisphenol A novolac type epoxy resin, Bisphenol F
Novolac type epoxy resin, alicyclic epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, hydantoin type epoxy resin, isocyanurate type epoxy resin, aliphatic chain epoxy resin and their halides, hydrogenated substances, etc. They can have any molecular weight, and several types can be used in combination.

Dicyandiamide (b) is preferably used in an amount of 0.3 to 1.0 equivalent (dicyandiamide) per equivalent of epoxy resin.
(If the number of functional groups in the compound is 4).

As the curing accelerator (C), imidazole compounds, organic phosphorus compounds, tertiary amines, quaternary ammonium salts, etc. are used, but imidazole compounds whose imino groups are masked with acrylonitrile, isocyanate, melamine acrylate, etc. By using this method, it is possible to obtain a prepreg that has storage stability that is more than twice that of conventional prepregs.

The imidazole compounds used here include imidazole, 2-ethylimidazole, 2-ethyl-4-ethylimidazole, 2-phenylimidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, and 2-hebutadecylimidazole. , 4.5-diphenylimidazole, 2-methylimidacillin, 2-
Phenylimidacillin, 2-undecyl imidacillin,
2-hebutadecy-ξdacillin, 2-isopropylimidazole, 2,4-dimethylimidazole, 2-phenyl-4-ethylimidazole, 2-ethylimidacilline,
Examples include 2-isoprobylimidacyline, 2.4-dimethylimidacyline, 2-phenyl-4-methylimidacyline, and masking agents include acrylonitrile, phenylene diisocyanate, toluene diisocyanate,
Examples include naphthalene diisocyanate, hexamethylene diisocyanate, methylene bisphenyl isocyanate, and melamine acrylate.

Several types of these curing accelerators may be used in combination, and the blending amount is preferably 0.01 to 5 parts by weight per 100 parts by weight of the epoxy resin.If it is less than 0.01 parts by weight, the accelerating effect will be small; If the amount exceeds 5 parts by weight, storage stability will deteriorate.

Phenol-based, sulfur-based, phosphorus-based reducing agents, etc. are used as the reducing agent in (d), but using a phenolic reducing agent improves electrical insulation properties without degrading other properties such as drill workability. can be improved. As the phenolic reducing agent, 12.3-trihydroxybenzene, butylated hydroxyanisole, 2.4-di-t-
Monophenols such as butyl-4-ethylphenol, 2゜2'-methylene-bis-(4-methyl-6-tert-butylphenol), 4,4'-thiobis-(3-methyl-6-tert -butylphenol) and 1,3.5-)rifthyl-2,4,6-1-
Lis(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tetrakis-[methylene-3-(3'
, 5'-di-tert-butyl-4'-hydroxyphenyl) propionate comethane and other polymeric phenols. Examples of the sulfur-based reducing agent include dilaurylthiodipropionate and distearylthiodipropinate. Examples of the phosphorus reducing agent include triphenyl phosphite and diphenylisodecyl phosphite. Several types of these reducing agents may be used in combination, and the blending amount is preferably 0.1 to 20 parts by weight per 100 parts by weight of the epoxy resin.If it is less than 0.1 part by weight, no improvement in insulation properties is observed. On the other hand, if the amount exceeds 20 parts by weight, the 2 insulation properties tend to deteriorate.

The epoxy resin & Il compound according to the present invention can be used in various forms, but a solvent is often used when coating or impregnating a base material. These solvents include acetone, methyl ethyl ketone, toluene, xylene, methyl isobutyl ketone, ethyl acetate, ethylene glycol monomethyl ether, N, N-dimethylbormamide, N, N
-Dimethylacetamide, medanol, ethanol, etc., and some of these may be used in combination.

The varnish obtained by blending the above (a), (b), (c), and (d) can be applied to base materials such as glass cloth, glass nonwoven fabric, paper, and cloth containing components other than glass in a machine or a drying oven. 80-20
A prepreg for printed wiring boards is obtained by drying at a temperature of 0°C. Prepreg is 150-190℃, 20
It is used for manufacturing printed wiring boards or metal clad laminates (hereinafter referred to as MCL) by heating and pressurizing in the range of ~80 kgf/cd.

Drying here means removing the solvent if a solvent is used, or making it lose fluidity at room temperature if no solvent is used.

〔Example〕

The present invention will be further explained below based on Examples.

Example 1 Brominated bisphenol A type epoxy resin 100 parts by weight (epoxy equivalent: 530) Dicyandiamide 4 parts by weight 2-ethyl-4-methylimidazole masked with hexamethylene diisocyanate 0.2 parts by weight Pyrogallol 0.5 parts by weight The above compound was dissolved in methyl ethyl ketone and ethylene glycol monomethyl ether to prepare a varnish with a nonvolatile content of 70%.

Example 2 Instead of the brominated bisphenol A epoxy resin in Example 1, 100 parts by weight of bisphenol A epoxy resin (epoxy equivalent: 450) was blended.

Example 3 Instead of the brominated bisphenol A epoxy resin in Example 1, 80 parts by weight of a bisphenol A epoxy resin (epoxy equivalent: 450) and 20 parts by weight of a cresol novolak epoxy resin (epoxy equivalent: 220) were used, and 5 parts by weight of dicyandiamide were used. and 5 parts by weight of tetrabromobisphenol A (hydroxyl equivalent: 272).

Example 4 Instead of 2-ethyl-4-methylimidazole masked with hexamethylene diisocyanate in Example 1, 0.2 parts by weight of 2-ethyl-4-methyligodazole, which was not masked, was blended.

Example 5 Instead of 2-ethyl-4-methylimidazole masked with hexamethylene diisocyanate in Example 1, 0.2 parts by weight of 2-undecylimidazole was blended.

Example 6 Instead of pyrogallol in Example 1, 4°4'-buty1! 0.5 parts by weight of Denbis (3-methyl-6-tert-butylphenol) was blended.

Example 7 l in place of pyrogallol in Example 1.

l 3-tris(2-methyl-4-hydroxy-5-t
-butylphenyl)butane was blended in an amount of 0.5 part by weight.

Example Day Instead of pyrogallol in Example 1, tetrakis[methylene-3-(3'5'-di-butyl-4
'-Hydroxyphenyl〉propionate comethane 0
．． 5 parts by weight was blended.

Example 9 Instead of pyrogallol in Example 1, 0.5 parts by weight of dilaurylthiopropionate was blended.

Example 10 Instead of pyrogallol in Example 1, 0.5 parts by weight of triphenyl phosphite was blended.

Example 11 Instead of pyrogallol in Example 1, 4°4'-
0.25 parts by weight of butylidene bis(3-methyl-6-tert-butylphenol) and 0.255 parts by weight of dilaurylthiopropionate were placed.

Comparative example 1 Pyrogallol in Example 1 was not blended.

Examples 1-11. A glass cloth having a thickness of 0.2 mm was impregnated with the varnish obtained in Comparative Example 1, and then heated at 140°C for 5 to 10 minutes to obtain a prepreg.

18 μm on both sides of the 8 sheets of prepreg obtained in this way.
Lay out thick copper foil and heat at 170°C for 190 minutes at 50kg/c.
A double-sided copper-clad tank N plate was produced under the pressing conditions of d. This MC
Circuit processing was performed on L, and a migration test was conducted.

Through-hole drilling was performed using a 0.9 mm diameter drill at a rotation speed of 60.00 rpm.

Feed rate 1. The test was carried out under the conditions of 800+m/min.

The hole wall spacing was 350μ, and 400 holes were prepared for each sample (
200 locations between through holes) t@edge low resistance was measured over time. Test conditions are 85'C/90%
The test was performed by applying 100V in an RH atmosphere, and the number of days until continuity breakdown occurred between the through holes was measured. Further, the insulation resistance was measured at 100V/1mfn.

The solder heat resistance test was conducted using MCL with double-sided etching.
After dipping in 60"C solder for 20 seconds, visually evaluate the appearance. If there is no blistering, it is OK.

Items with swelling were rejected.

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 after storage for 60 days at 20°C/40% RH. The results are shown in Table 1.

In Examples 1 to 11 in which a reducing agent was added, the number of days until continuity failure was longer, especially in Example 1 in which a phenolic reducing agent was used.
~8, the insulation properties tended to become higher.

Table ■ Characteristic evaluation results [Effects of the invention] As is clear from the above explanation, the epoxy resin composition of the present invention suppresses the occurrence of metal migration and improves electrical This improves insulation properties.

Claims (2)

[Claims] 1. (a) Epoxy resin (b) Dicyandiamide (c) Curing accelerator (d) Reducing agent An epoxy resin composition containing as an essential component 2. The epoxy resin composition according to claim 1, wherein the reducing agent is a phenolic reducing agent.