JPH06336527A - Single-copper-clad laminate for printed circuit - Google Patents

Abstract

PURPOSE:To obtain the subject laminate proofed against warpage by making a woven glass fabric on the side of a copper foil thinner than the one on the other side. CONSTITUTION:A woven glass fabric prepreg (A) as the surface layer on the side of a copper foil is formed by impregnating a woven glass fabric (a) of a thickness of 100-200mum with 35-50wt.% epoxy resin. A nonwoven glass fabric (C) as the interlayer is formed by impregnating a nonwoven glass fabric with an epoxy resin and an inorganic filler such as talc. A woven glass fabric prepreg (B) as the surface layer on the other side is formed by impregnating a woven glass fabric prepreg (b) of a thickness larger than that of the woven glass fabric (a) by 30-80mum with 40-52wt.% epoxy resin. Prepreg A and prepreg B are applied to the upper and lower surfaces of fabric C, and a copper foil is laminated on the surface of prepreg A. The assemblage is subjected to laminate molding under pressure at a specified temperature to obtain the objective laminate proofed against warpage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-sided copper clad laminate for printed circuits, which has less warpage.

[0002]

2. Description of the Related Art Copper clad laminates for printed circuits often cause troubles in the circuit making process and component mounting process due to warping and twisting of the board due to repeated humidification and heat treatment during the process of manufacturing the circuit board. I may come.
In particular, with the increase in the size of the board, the increase in the density of the circuit, and the automation of the processing process, the requirements for preventing the warp and the twist of the board are becoming more and more strict. Since the one-sided copper-clad laminate has an asymmetric structure in which one surface is made of copper foil and the other surface is made of prepreg, a difference in expansion and contraction occurs between the copper foil and the prepreg during molding of the laminate and manufacture of the circuit board. In addition, in the case of a composite laminated plate, complicated warp and twist occur due to the difference in linear expansion coefficient and elastic modulus between the glass woven cloth layer and the glass nonwoven cloth layer. In particular, the warpage and twist caused by the way heat is applied during heating in the lamination molding process are large. This warp generally occurs with the copper foil inside. This is largely because the temperature rises on the hot platen side and the center side of the laminated plate are non-uniform, and the cured state on both sides is non-uniform. In order to improve this warpage, the temperature of the hot platen should be slowly raised so that the temperature rise of both the hot platen side and the center plate is the same during heat molding, and after the molding is completed, there is no additional processing. Although a method of relaxing stress due to heating and pressurization by performing only heating with pressure has been proposed, none of them is generally applied because of a definite problem that the molding cycle becomes significantly long.

[0003]

The present invention has been made as a result of various studies in order to solve the above problems. That is, the present inventor pays attention to the fact that the warp of the laminated plate after the molding process is small, the warp is small even during heating and humidification during the circuit board manufacturing process, and the warp during molding of the laminated plate is small. As a result of extensive studies aimed at providing a copper-clad laminate, the warpage that occurs in the single-sided copper-clad laminate after heat and pressure molding is due to the difference in the tensile elastic modulus in the plane direction of the copper foil and the substrate. It was found that the warp was prevented by changing the elastic modulus in the plane direction by making the thicknesses of the glass woven fabric layer on the copper foil side and the glass woven fabric layer on the opposite side different from each other in the surface layer. The present invention has been completed based on the knowledge that it can be achieved.

[0004]

The present invention comprises a prepreg made of a glass woven cloth impregnated with an epoxy resin in a surface layer and a prepreg made of a glass nonwoven cloth impregnated with an epoxy resin and an inorganic filler in an intermediate layer. In a single-sided copper-clad laminate having a copper foil arranged on the surface on one side thereof, the glass woven fabric of the surface layer has a thickness of the glass woven fabric on the copper foil side set to be thinner than the thickness of the glass woven fabric on the opposite side. The present invention relates to a single-sided copper-clad laminate. Hereinafter, the present invention will be described in detail. In the epoxy resin-impregnated glass woven fabric used in the present invention, the epoxy resin is a brominated epoxy resin,
It may be any non-brominated epoxy resin. A glass woven fabric (a) used for the glass woven fabric layer (A) on the copper foil side
Is thinner than the glass woven fabric (b) on the opposite side. The ratio of the glass woven fabric (a) to the glass woven fabric (b) is preferably 6/10 to 9/10. Outside this range, the effect of preventing warpage tends to decrease. Specifically, for example, the glass woven fabric (a) is WEA manufactured by Nitto Boseki.
15-RB84 (thickness 150 μm) is used, and the glass woven fabric (b) is WEA18K-RB84 (thickness 18 made by Nitto Boseki).
0 μm) and thicknesses of 0.15 mm and 0.1, respectively.
Adjust the resin content to 2 mm. As the intermediate layer, a predetermined number of glass nonwoven fabrics impregnated with an epoxy resin and an inorganic filler are stacked and used. The filler may be any of aluminum hydroxide, mica, talc, clay, wollastonite, magnesium oxide and the like, and may be used alone or in combination of two or more. The single-sided copper-clad laminate of the present invention has a predetermined number of glass nonwoven fabrics impregnated with an epoxy resin and an inorganic filler as an intermediate layer, and the glass woven fabric (a) on the copper foil side has a thickness of 100 to 200 μm. Prepreg is made so that the content of the epoxy resin is 35 to 50%, and the glass woven cloth (b) on the opposite side is 30 to 80 μm thicker than the glass woven cloth (a) on the copper foil side. One is used to prepare a prepreg so that the epoxy resin content is 40 to 52%, and then the copper foil is placed on the glass woven fabric layer (A) side, and heat and pressure molded to form one-sided copper. Obtain a stretched laminate.

[0005]

In the conventional composite laminated plate, the glass woven fabrics arranged on both sides of the glass non-woven fabric layer have the same thickness, so that the elastic modulus in the plane direction is the same. In the laminated plate, the thickness of the glass woven cloth on the surface layer on the copper foil side should be thin, and the elastic modulus in the plane direction should be smaller than that of the glass woven cloth layer on the opposite side (preferably 5% or more). Warp after lamination molding is reduced by
Warpage during circuit processing can also be reduced. That is, by setting the insulating layer so that it warps toward the opposite side of the copper foil as a whole, and by balancing with the elastic modulus of the copper foil, warping toward the copper foil side is prevented.

[0006]

EXAMPLES Examples of the present invention and comparative examples (conventional examples) are described below.
Indicates. <Example> The composition of the epoxy resin-containing varnish for the surface layer is as follows. (1) Brominated epoxy resin (Ep-1046 manufactured by Yuka Shell Co., Ltd.) 100 parts (2) Dicyandiamide 4 parts (3) 2-Ethyl-4-methylimidazole 0.15 part (4) Methylcellosolve 36 parts (5) Acetone 60 parts Epoxy resin varnish prepared in this way was impregnated into a glass woven cloth (Nitto Boseki WEA15-RB84, thickness 150 μm) to a resin content of 45% and dried to obtain a glass woven cloth prepreg (A). Obtained. Furthermore, glass woven fabric (Nitto Boseki WEA18K-RB
Glass woven prepreg (B) was obtained by impregnation and drying so that the resin content was 84%. Subsequently, the following inorganic filler was added to and mixed with 100 parts of the resin content of the above epoxy resin varnish to prepare an inorganic filler-containing epoxy resin varnish. (1) Gibbsite type aluminum hydroxide 60 parts (Showa Denko's Heidilite H-42) This inorganic filler-containing varnish was added to a glass non-woven fabric (Japan Vilene EP-4075) containing 90 parts of resin and inorganic filler.
The glass nonwoven fabric prepreg (C) was obtained by impregnating and drying so that the prepreg (C) became. 3 of the above-mentioned Gasla nonwoven fabric prepreg (C)
One sheet each of the above glass woven prepregs (A) and (B) is placed on the upper and lower surface layers by stacking the sheets to form an intermediate layer, and a copper foil having a thickness of 35 μm is further placed on the prepreg (A), and the molding temperature is set. 1
By laminating at 70 ° C. and a pressure of 60 kg / cm ² for 90 minutes, a single-sided copper clad laminate having a thickness of 1.6 mm was obtained. <Comparative Example 1> A single-sided copper clad laminate was obtained by the same process as in Example except that WEA18K-RB84 (thickness 180 μm) manufactured by Nitto Boseki was used for both the glass woven fabric (a) and the glass woven fabric (b). It was <Comparative example 2> WEA18K-RB84 manufactured by Nitto Boseki on glass woven fabric (a)
A single-sided copper-clad laminate was obtained by the same process as in Example except that the thickness (180 μm) was used for the glass woven fabric (b) on the opposite side and WEA15-RB84 (thickness 150 μm) manufactured by Nitto Boseki was used. The warpage of the single-sided copper-clad laminate obtained in each of the above examples was measured. The results are shown in Table 1.

[0007]

[Table 1]

[0008]

INDUSTRIAL APPLICABILITY The single-sided copper-clad laminate of the present invention has a small warpage after heat and pressure molding, and therefore can easily be rewarped, so that it is easy to handle after molding and the warpage after circuit formation is also small. It is a thing.

Claims (1)

[Claims] 1. A single-sided copper-clad laminate for a printed circuit, wherein a surface layer is composed of a glass woven fabric layer impregnated with an epoxy resin, and an intermediate layer is composed of a glass nonwoven fabric layer impregnated with an epoxy resin and an inorganic filler. A single-sided copper-clad laminate, wherein the glass woven cloth on the copper foil side is made thinner than the glass woven cloth on the other side.