JPH05116249A - Manufacture of laminated board - Google Patents

Abstract

PURPOSE:To prevent copper migration effectively by blending a substance absorbing moisture into thermo-setting resin varnish in a laminated board for a printed circuit, in which a copper foil is superposed to a prepreg obtained by impregnating a fiber base material with a thermo-setting resin and heated and pressure-molded. CONSTITUTION:A thermo-setting resin such as an epoxy resin, a phenol resin, an unsaturated polyester resin, etc., is impregnated with a glass woven fabric, a glass nonwoven fabric, a synthetic fiber woven fabric, etc., thus preparing a prepreg. One prepreg or a plurality of prepregs are superposed, and a copper foil is superposed onto one surface or both surfaces of the stack, thus manufacturing a laminated board. In the manufacture of such a laminated board, a substance having action, in which moisture is absorbed, such as an oxide such as calcium oxide, magnesium oxide, silica gel, etc., a hydrolytic silane compound, etc., are blended in thermo-setting resin varnish. Accordingly, the moisture in a printed circuit board is reduced extremely, and the ionization of copper by moisture is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a laminated board for a printed circuit, which prevents copper migration.

[0002]

2. Description of the Related Art Conventionally, in order to prevent copper migration, a novolac type phenol resin is used as a curing agent in the epoxy resin formulation, and in the case of a dicyandiamide curing agent, its equivalent ratio is 0.5 or less. Measures have been taken such as using triphenyl phosphate or DBU as a catalyst, or using a material having a low water absorption rate or a material having a small amount of ionic impurities. In addition, a method of preventing moisture absorption by treatment with a coupling agent has also been adopted in order to improve the adhesion between a substrate such as glass cloth or the adhesive surface between the copper foil and the resin.

[0003]

SUMMARY OF THE INVENTION The present invention has been completed by various studies in order to further improve this effect as compared with the conventional method for preventing copper migration, and moisture is contained in the thermosetting resin varnish. It is characterized by blending a substance to be absorbed.

[0004]

Means for Solving the Problems The present invention provides a prepreg obtained by impregnating a woven fabric with a thermosetting resin, laminating one or more prepregs, and laminating a copper foil on one or both sides of the prepreg. In the method for producing a laminate for heating and pressurizing, the gist of the method for producing a laminate is to add a substance having an action of absorbing water such as calcium oxide into a thermosetting resin varnish. is there.

The thermosetting resin used in the present invention is an epoxy resin, a phenol resin, an unsaturated polyester resin or the like, and is not particularly limited. The fiber base material is glass woven cloth, glass nonwoven cloth, synthetic fiber woven cloth, or the like.

Examples of the substance having a function of absorbing water, which is mixed in the thermosetting resin varnish, include calcium oxide, magnesium oxide, oxides such as silica gel, and hydrolyzable silane compounds. The compounding amount of such a substance depends on the amount of water in the varnish, but is usually 2 to 15% by weight in terms of solid content. When it is more than 15% by weight, the effect of preventing copper migration is not improved and other characteristics may be deteriorated. When it is less than 2% by weight, copper migration may not be sufficiently prevented. 2 if the amount of water in the varnish is very small due to dehydration
It may be less than or equal to%. A solid substance such as calcium oxide is preferably finely pulverized.

The water content in the thermosetting resin varnish should be as low as possible because it lowers the compounding effect of the substance having the function of absorbing water. However, a normal varnish contains a small amount of resin, curing agent or solvent. ing. It is preferable to remove this moisture in advance, and the resin and the curing agent can be removed by individually heating them before compounding. The solvent may be purified by distillation or the like. However, even with these methods, it is substantially impossible to completely remove water, so that it is necessary to determine the amount of the substance that absorbs water to be blended, depending on the content of water in the varnish.

By such a method, the amount of water remaining in the laminated plate can be reduced to almost zero, and copper migration can be prevented by the action of the substance even if the laminated plate absorbs moisture in the subsequent steps. it can.

[0009]

EXAMPLES The present invention will be described below with reference to examples. The blending amount of each material is part by weight. The composition of the varnish was as follows (in terms of solid content), and the resin solid content was adjusted to about 55% by weight with a solvent (methyl cellosolve dimethylformamide 1: 1). Bisphenol A type epoxy resin 70 parts (Ep-5049 epoxy equivalent 760) Novolac type epoxy resin 30 parts (EPC-N-865 epoxy equivalent 203) Dicyandiamide 2.4 parts 2-Ethyl-4-methylimidazole 0.2 parts Calcium oxide (Change)

The blending amount of calcium oxide is as follows,
A glass cloth was impregnated into a prepreg, and a copper foil was laminated and heat-pressed by a conventional method to obtain a copper-clad laminate. Table 1 shows the copper migration measurement results for each example. It should be noted that the varnish was used with and without dehydration of the solvent.

[0011]

[Table 1]

Copper migration was measured by the following method. The copper foil of the copper clad laminate is etched to form the comb-shaped circuit (circuit width 100 μm, circuit interval 100 μm) of FIG.
It was treated for 1000 hours while applying a voltage of 50 V under the conditions of 5 ° C. and a humidity of 85%. Then, a voltage of 500 V was applied, and the following judgment was made based on the number of resistances between the comb-shaped circuits which were 1 × 10 ⁸ Ω or less. Ten sheets were tested each. 0 sheets A 1-2 sheets B 3-4 sheets C 5 sheets or more D

[0013]

According to the method of the present invention, the amount of water in the printed circuit board is very small and copper is not ionized by the water, so that copper migration can be effectively prevented. In addition, since the moisture that enters through the post-treatment of the substrate is also captured by the substance, the ionization of copper can be prevented in this respect as well.

[Brief description of drawings]

FIG. 1 is a plan view of a comb-shaped circuit used for a copper migration test.

[Explanation of symbols]

 1 copper circuit 2 copper circuit

Claims (2)

[Claims] 1. Production of a laminated plate in which a fibrous base material is impregnated with a thermosetting resin to obtain a prepreg, one or more prepregs are superposed, and a copper foil is superposed on one or both sides of the prepreg and heat-pressed. In the method, a method for producing a laminated board is characterized in that a substance having an action of absorbing water is mixed in the thermosetting resin varnish. 2. The method for manufacturing a laminated board according to claim 1, wherein the substance is calcium oxide.