JPH0360189A - One side metal laminated phenol resin board - Google Patents

Abstract

PURPOSE:To prevent bend or twist of the title laminated board used as a printed circuit board by making elongation rate of the kraft-paper based material of the outermost layer of the board on which no metallic foil is formed larger than that of the other kraft-paper based material of the main layer. CONSTITUTION:Elongation rate of the kraft-paper based material of the outermost layer 2 of this laminated board on the side where no metallic foil 1 is formed is made larger than that of the other kraft-paper based material of the main layer 3 of the circuit board. In this one side metal laminated board, the kraft-paper based material 2 having larger elongation rate of the outermost layer on the side where no metallic foil is formed suppresses the heat shrinkage of a phenol resin to keep balance with that on the circuit surface side and bend or twist of the laminated board can be prevented. When elongation rate of the material 2 becomes smaller than 1.2%, bend or twist suppressing effect decreases and, when elongation rate becomes larger than 1.5%, on the contrary, bend occurs in the opposite direction. This laminated board is suitable for manufacturing processes which are associated with heating processes and for manufacturing printed circuit boards having no insulating coat on the surface or having insulating coat which is formed after the heating processes.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a phenolic resin single-sided metal foil laminate for printed circuit boards. It is particularly suitable for printed circuit boards that involve heat treatment in the manufacturing process of printed circuit boards and do not have an insulating coat on the surface of the circuit board, or are formed after the heat treatment. This invention relates to a single-sided metal foil clad laminate.

BACKGROUND OF THE INVENTION Phenolic resin copper clad laminates are widely used for printed circuit boards in the consumer electronics field. As electronic components have become more sophisticated and denser in recent years, demands for suppressing warpage and twisting during the circuit board manufacturing process have become increasingly strict.

In particular, single-sided printed circuit boards are susceptible to warping and twisting because of their asymmetrical structure in the thickness direction. For example, when through-holes are formed by filling with silver paint, the heat treatment for this purpose causes warping and twisting of the board, causing problems during the circuit board manufacturing process and parts assembly process. Furthermore, it is difficult to cope with higher density.

Conventionally, in order to reduce the occurrence of warping and wrinkling in the above process, a resin with low heating dimensional shrinkage was used as the phenolic resin, and the base material to be impregnated with the phenolic resin was made of kraft paper and kraft linter mixed paper, etc. Compatible with combinations.

Problems to be Solved by the Invention However, as long as addition condensation type phenolic resins are used, it is difficult to obtain phenolic resins with low dimensional shrinkage through modification. Furthermore, in the case of a combination of paper mixed with kraft and linter, whose dimensional change behavior is completely different from that of kraft paper, a large amount of twisting tends to occur.

An object of the present invention is to provide a phenolic resin single-sided metal foil-clad laminate that can suppress the occurrence of warping and twisting as a printed circuit board. In particular, for printed circuit boards where heat treatment is involved in the manufacturing process of the printed circuit board, and where the surface of the circuit board does not have an insulating coating or is formed after the heat treatment. An object of the present invention is to provide a suitable single-sided metal foil-clad laminate.

Means for Solving the Problems The phenolic resin single-sided metal foil laminate according to the present invention includes:
Kraft paper is used as the base material to be impregnated with phenolic resin. As shown in FIG. 1, the elongation rate of the outermost N2 kraft paper base material on the side without the metal foil 1 is
It is characterized by having a higher elongation rate than that of the other kraft paper base material which is the main layer 3.

In addition, the kraft paper base material for both the main layers has a basis weight of 200 to 250.
g/% may be used to reduce the number of stacked sheets to obtain a laminate of a predetermined thickness. Furthermore, the elongation rate of the kraft paper base material with a large elongation rate of the outermost layer 2 is 1
．． A range of 2 to 1.5% is preferred. Here, the growth rate is
It was measured according to JISP-8132-1976.

A single-sided printed circuit board obtained by processing a phenolic resin single-sided metal foil-clad laminate has an asymmetrical structure in the thickness direction, and therefore warps and twists occur during heat treatment. That is, although the phenol resin thermally shrinks during the heat treatment, the shrinkage is prevented because the metal foil circuit exists integrally on the circuit surface side. As a result, the surface opposite to the circuit surface shrinks a lot, causing warpage in which the circuit surface side becomes convex.

In addition, twisting occurs due to the difference in contraction between the circuit side and the opposite side.

In the single-sided metal foil-clad laminate according to the present invention, the kraft paper base material with a high elongation rate on the outermost layer on the side without metal foil suppresses the heat shrinkage of the phenolic resin and balances the amount of shrinkage on the circuit side side. This prevents warping and twisting. When the elongation rate of the kraft paper base material, which has a high elongation rate, becomes smaller than 1.2%, the effect of suppressing warping and twisting becomes smaller, and the elongation rate becomes smaller than 1.5%.
%, the opposite warp occurs (the circuit side is concave)
will be invited.

The cause of waviness is the strain left between the base material layers during the forming of the laminate, but by using paper with a high basis weight, fewer layers are required to obtain a laminate of the same thickness. As a result, since the number of interlayers is reduced, the amount of residual strain during molding is reduced, and twisting can be suppressed.

Example Examples of the present invention will be described.

Example 1 A kraft paper base material having a basis weight of 135 g/ni and an elongation rate of 1.2% was impregnated with a tung oil-modified phenolic resin and dried to obtain a prepreg with a resin gold content of 148% (prepreg A).

A kraft paper base material with a basis weight of 135 g/n (and an elongation rate of 0.7%) was impregnated with tung oil-modified phenolic resin and dried to obtain a prepreg with a resin content of 48% (prepreg B).

1 ply of prepreg A, 4 plies of prepreg B, and 35μ thick copper foil coated with adhesive are stacked in this order, and this is stacked at a temperature of 160'C and a pressure of 100kg/c++.
A single-sided copper-clad laminate having a thickness of 1.0 mm was obtained by heating and press-forming for 60 minutes at 1.0 mm.

Example 2 A kraft paper base material with a tsubo IT of 250 g/m and an elongation rate of 0.7% was impregnated with tung oil-modified phenolic resin and dried to have a resin content of 49.
% prepreg was obtained (prepreg C).

1 ply of prepreg A of Example 1, 2 plies of prepreg C
A ply and a 35μ thick copper foil coated with an adhesive were stacked in this order, and molded under the same molding conditions as in Example 1. A single-sided copper-clad laminate with a thickness of 〇-thickness was obtained.

Comparative Example 1 5 plies of prepreg A obtained in Example 1 were stacked with 35μ thick copper foil coated with adhesive, and the same molding conditions as Example 1 were used to produce a single-sided copper-clad laminate with a thickness of 1. Onrm. I got it.

Comparative Example 2 A kraft/linter mixed paper base material (tsubo @ 135 g/ho) was impregnated with tung oil modified phenolic resin and dried to have a resin content of 48%.
A prepreg of (prepreg D) was obtained.

4 plies of prepreg B, 1 ply of prepreg D, and 35 μ thick copper foil coated with adhesive were stacked in this order, and a single-sided copper-clad laminate with a thickness of 1.0 mm was obtained under the same molding conditions as in Example 1. Ta.

Etch each of the above single-sided copper-clad laminates to a size of 300 x 200 mm (remaining copper ratio: 40%), punch out the outer shape,
Figure 3 shows the change in warpage over time when heat treated (E-3/160). Moreover, it is shown by the maximum value of the lifting amount of the edge in FIG.

Note that if the circuit surface is coated with an insulating coating, if heat treatment is performed after coating, the coating will shrink due to heat, so special measures are required.

The single-sided metal foil-clad laminate according to the present invention is effective for use in single-sided printed circuit boards where the circuit surface is not coated or coated after heat treatment.

Effects of the Invention As described above, the phenolic resin single-sided metal foil-clad laminate according to the present invention is suitable for use in single-sided printed circuit boards that require heat treatment in the manufacturing process, and can suppress warpage and twisting to a minimum in the above-mentioned applications in particular. can.

In addition, by suppressing warpage and twisting, it becomes possible to support high-density fine patterns of circuits.

[Brief explanation of drawings]

Figures 1 and 2 are cross-sectional explanatory diagrams of a phenolic resin single-sided metal foil-clad laminate according to the present invention, Figure 3 is a curve diagram showing changes in warpage over time during the printed circuit board manufacturing process, and Figure 4 is a heating It is a comparison diagram of twisting after treatment. 1 is metal foil, 2 is outermost layer, 3 is main layer

Claims (3)

[Claims] 1. In a single-sided metal foil-covered laminate made by placing metal foil on one surface of a phenolic resin-impregnated kraft paper base layer and integrally laminating it, the elongation rate of the outermost kraft paper base layer on the side without metal foil A phenolic resin single-sided metal foil-clad laminate, characterized in that the elongation rate is greater than that of other kraft paper base materials, which are the main layer. 2. The basis weight of the kraft paper base material that is not located in the outermost layer is 200
The phenolic resin single-sided metal foil-clad laminate according to claim 1, which has a high basis weight of ~250 g/m^2. 3. The elongation rate of the kraft paper base material, which has a high elongation rate, is 1.2.
The phenolic resin single-sided metal foil-clad laminate according to claim 1 or 2, wherein the phenol resin content is in the range of 1.5%.