JPH08267663A - Single-sided metallic foil-clad laminate - Google Patents

Abstract

PURPOSE: To provide a single-sided metallic foil-clad laminate of small warpage by a method wherein tensile strength of paper base material on a metallic foil side for respective length and bredth of the paper base material is made a specific number of times the tensile strength of the paper base material on an opposite side to the metallic foil. CONSTITUTION: For one side metallic foil-clad laminate wherein paper is used as base material and a metallic foil is arranged only on one side, tensile strength of paper base material on a metallic foil side for respective length and width of the paper base material is made 0.8-0.95 times the tensile strength of the paper base material on an opposite side to the metallic foil. When the tensile strength of the paper base material on the metallic foil side is smaller than 0.8 times the tensile strength of the paper base material on the opposite side to the metallic foil, minus warpage wherein a copper foil surface becomes depressed in an etching process or a printing process increases to cause a line trouble. Further, when it is larger than 0.95, there is no effect. For the paper base material to be used, kraft paper of excellent thermal expansion and contraction coefficient being linter paper, kraft paper, etc., is preferable. For thermosetting resin with which the paper base material is impregnated, phenolic resin, epoxy resin or its modified resin can be used, and those can independently or jointly used also.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper-based single-sided metal-clad laminate used as a rigid printed wiring board.

[0002]

2. Description of the Related Art Paper-based metal foil-clad laminates, which are widely used in consumer electronic equipment, are metal foils on the surface of a paper-based laminate with a thermosetting resin matrix. It is stuck.

As the thermosetting resin, phenol resin,
Polyester resins and epoxy resins are used, but the ones that use phenol resin as a matrix are the main ones because the cost is low. Kraft paper is mainly used as the paper. Copper foil, which is a good conductor of electricity, is mainly used as the metal foil.

Metal foil-clad laminates (copper foils are mostly used as metal foils, and henceforth referred to as copper-clad laminates) must have small warpage.
This is to ensure accurate component mounting by an automatic machine and to prevent peeling and dropping of components after component mounting. This warpage occurs during the solder flow in the circuit processing step and component mounting step of the copper clad laminate.

In order to reduce warpage, use of a paper base material having a ratio of tensile strength in the vertical direction to that in the transverse direction of 1.10 to 1.30 (see Japanese Patent Laid-Open No. 58-128844),
It is known to use paper base materials having different warp ratios of tensile strength between the outside and the middle of the laminated plate (see JP-A-60-40244 and JP-A-60-40243).

[0006]

However, in the case of a single-sided copper-clad laminate having a copper foil on only one side, when the residual copper rate after circuit processing is high and there are many punched holes, copper is not removed after punching. A sled with a convex surface (hereinafter referred to as a plus sled)
There was a problem that became large. An object of the present invention is to provide a single-sided metal-clad laminate having a small warpage.

[0007]

DISCLOSURE OF THE INVENTION The present invention is a single-sided metal-clad laminate having paper as a base material and a metal foil disposed on only one surface thereof. A single-sided metal-clad paper base laminate, wherein the tensile strength of the paper base on the side of the foil is 0.8 to 0.95 times the tensile strength of the paper base on the side opposite to that of the metal foil. .

If the tensile strength of the paper base material on the metal foil side is smaller than 0.8 of the tensile strength of the paper base material on the side opposite to the metal foil, the copper foil surface in the etching process and the printing process is concave. As a result, the negative sled becomes large and causes line trouble.
Further, if it is larger than 0.95, there is no effect.

The paper base material used is linter paper, kraft paper, mixed paper or the like, but kraft paper having excellent thermal expansion / shrinkage properties is preferable. The thermosetting resin with which the paper base material is impregnated may be a phenol resin, an epoxy resin, a melamine resin, an unsaturated polyester resin, or a modified resin thereof, and these may be used alone or in combination. Further, a flame retardant can be added to or reacted with the above resin to form a flame retardant laminate.

The single-sided metal-clad laminate of the present invention is obtained by impregnating the paper base material with the thermosetting resin and heating the prepreg in a semi-cured state by laminating a plurality of prepregs by a conventional method. It is manufactured by a method in which copper foil is superposed on and heat and pressure are applied.

[0011]

[Function] The plus sled of the printed wiring board using the single-sided copper-clad laminate after punching is different from the thermal expansion and contraction behavior of the copper foil in the laminate portion, that is, the portion of the thermosetting resin and the paper base material. One of the causes is that the heat shrinkage after heating and cooling is large. Since the tensile strength of the paper base material used for the prepreg in contact with the copper foil of the one-sided copper-clad laminate is 0.8 to 0.95 times the tensile strength of the paper base material of the prepreg on the opposite side of the copper foil, The heat shrinkage on the side opposite to the foil side is small.
Therefore, the positive sled becomes small.

[0012]

【Example】

Manufacture of prepreg A The tensile strength is 42.14 N / 15 mm in the vertical direction and 3 in the horizontal direction.
Kraft paper of 1.36 N / 15 mm was impregnated with a tung oil-modified phenolic resin and dried. Manufacture of prepreg B Tensile strength is vertical 46.06N / 15mm, horizontal 3
4.30 N / 15 mm kraft paper was impregnated with a tung oil-modified phenolic resin and dried. Manufacture of prepreg C The tensile strength is 44.10 N / 15 mm in the vertical direction, 3 in the horizontal direction.
A kraft paper of 2.34 N / 15 mm was impregnated with a tung oil-modified phenol resin and dried.

Example 1 One prepreg A was placed at a position in contact with the copper foil, and seven prepregs B were placed on the opposite side of the copper foil.
Heating and pressurizing at 9.8MPa for 80 minutes, thickness 1.6m
A single-sided copper clad laminate of m was obtained.

Example 2 One prepreg A was placed in contact with the copper foil, one prepreg B was placed on the opposite side of the copper foil, and 6 prepregs C were placed on the intermediate layer.
The sheets were superposed on each other, and the thickness was 1.
A 6 mm single-sided copper clad laminate was obtained.

Example 3 Seven prepregs A were used on the side in contact with the copper foil, and one prepreg B was used on the side opposite to the copper foil. A single-sided copper clad laminate was obtained.

Comparative Example Eight prepregs B were used and overlaid with one copper foil, and a single-sided copper clad laminate having a thickness of 1.6 mm was obtained in the same manner as in Example 1.

The warpage amount of the obtained single-sided copper-clad laminate was examined as follows. After the circuit processing of each copper-clad laminate sample, a test piece having a vertical length of 300 mm and a horizontal length of 200 mm was punched out. The test piece was allowed to stand on a surface plate, and the rises at the four corners were measured with a dial gauge to obtain an average value.
The results obtained are shown in Table 1.

[0018]

[Table 1]

From the results in Table 1, it can be seen that the single-sided copper-clad laminate of the present invention has a smaller amount of warpage 9 than the conventional single-sided copper-clad laminate.

[0020]

According to the present invention, the tensile strength of the paper base material on the side in contact with the copper foil is 0.8 to 0.95 times that of the paper base material on the opposite side of the copper foil. By doing so, a single-sided copper-clad laminate having excellent warpage characteristics can be obtained.

Claims (1)

[Claims] 1. A single-sided metal-clad laminate having paper as a base material and a metal foil disposed on only one surface, wherein the tensile strength of the paper base material on the side of the metal foil is measured for each vertical bar of the paper base material. But,
0.8 to 0.95 of the tensile strength of the paper substrate on the side opposite to the metal foil
Double-sided metal-clad paper-based laminated board characterized by being doubled.