JPH0784041B2 - Laminated board manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a copper clad laminate for printed circuits.

(Prior Art) In recent years, copper clad laminates have been strongly required to have excellent dimensional accuracy and less warpage as the printed wiring board processing technology is advanced and component insertion is automated. For this reason, the adoption of a paper base material made from wood pulp with less warp, twist, and dimensional change, and the ratio of the tensile strength of the paper base material in the vertical direction and the horizontal direction is in the range of 1.0: 1 to 1.4: 1. Some have addressed the need by using one.

(Problems to be Solved by the Invention) However, the current situation is that the warp and twist of the printed wiring board cannot be sufficiently eliminated by the measures described above. When the shape or residual copper rate of the printed wiring board changes, warping and twisting become large, and the results cannot be put to practical use.

(Means for Solving Problems) The present inventors have obtained the present invention as a result of research in view of the above problems.

A copper clad laminate is manufactured by heating and pressing a required number of prepregs obtained by impregnating a paper base material with a thermosetting resin and drying. When the structure of this prepreg does not uniformly expand and contract, warpage and twisting increase. . In order to reduce this warpage and twist, it is necessary to have a uniform fiber distribution and resin adhesion on the front and back of the prepreg.

The present invention has five types of fiber lengths of 42M / S on, 60M / S on, 100M / S on, 150M / S on, 150M / S pass in front and back layers formed by dividing the paper in the thickness direction into three layers. A paper base material having a uniform fiber length distribution in which the absolute value of each difference in distribution ratio is 1.5% or less is used.

(Example) (Production Example and Measuring Method) LBKP (hardwood bleached kraft pulp) having a fiber length of 0.8 to 1.8 mm was used as a 5% aqueous dispersion using a 250 mesh screen to obtain a basis weight of 132 g / m ² . Paper was made. If a 150 mesh screen is used, short fibers will pass through the screen and the fiber length distribution on the screen side (wire side) will be distributed in the longer direction. On the other hand, on the felt surface on the opposite side, short fibers are captured by the fibers laminated on the screen, and the fiber length distribution is shorter than that of the wire surface. Therefore, the fiber length distribution differs in the thickness direction of the paper. The deviation of the fiber length distribution in the thickness direction warps and adversely affects the twist. A fine screen was used to prevent short fiber lengths from slipping out.
There is also a method in which long mesh fibers having a long fiber length are separated in advance, and the dispersion is used to clog the mesh surface very thinly and then the normal operation is performed.

The fiber length distribution of the front and back layers when the paper base material was divided into three layers was performed as follows. Apply a 100 mm wide polyester tape with adhesive (adhesive tape) to one side (surface layer) of the paper substrate, press it, and then remove the adhesive tape. At this time, in the adhesive tape, the paper is peeled off from the paper base material and adheres to the adhesive surface. By adjusting the pressing pressure of the adhesive tape and the peeling angle, about 1/3 of the thickness of the paper substrate when peeling
Can be peeled off. Adjustable mainly by peeling angle 18
The 0 ° peeling was good in the experimental results. The peeled pressure-sensitive adhesive tape is dipped in water to peel the paper base material from the pressure-sensitive adhesive. To check the fiber length distribution, approximately the same as JIS P8207,
10 g of sample is required. Similarly, the other side of the paper substrate (back layer)
Also process. Then, a small amount of a surfactant was added to the paper base material dispersed in water and stirred to prepare a paper base material dispersion liquid.
Next, receiving container, 150M / S (mesh) tank, 100M / S tank,
The dry weight of the paper fiber remaining on each sieve was measured by adding the paper substrate dispersion liquid and water through the sieves of the 60 M / S tank and the 42 M / S tank. The contents in the receiving container were filtered with a filter paper, and the dry weight of the paper fiber remaining on the filter paper was measured. In this way, the fiber length distributions of the surface layer and the back layer of the paper substrate were examined. An example is shown in Table 2.

Example 1 A mixture of 700 g of phenol, 300 g of cresol, 100 g of formalin (37% formaldehyde aqueous solution) and 35 g of 25% ammonia water was heated and reacted, and dehydrated under reduced pressure. An organic solvent was added to the mixture to obtain a phenol resin varnish. Consisting of hardwood halves, the ratio of 42M / S on is 0.8%, 60M / S on is 0.3%, 100M / S on is 0.5%, 150M in the fiber length distribution of the front and back layers.
The varnish was impregnated into a paper base material having a / S ON of 0.3% and a 150M / S pass of 0.3% to obtain a prepreg having a total resin adhesion amount of 50%. The required number of this prepreg and the copper foil with adhesive are overlaid, and heated and pressed at 165 ° C and 85Kg / cm ² for 40 minutes to obtain a thickness
A 1.6 mm copper vibration laminated plate was obtained. The performance is shown in Table 1.

Example 2 Consisting of hardwood pulp, the fiber length distribution of the front and back layers was 42.
Example for paper base material with M / S on ratio difference of 1.5%, 60M / S on 0.5%, 100M / S on 0.5%, 150M / S on 0.3%, 150M / S pass 1.4% A copper clad laminate was obtained in the same manner as in 1.
The performance is shown in Table 1.

Comparative Example Made of hardwood pulp, in the fiber length distribution of the front and back layers,
42M / S ON ratio difference 2.9%, 60M / S ON 0.6%, 100M / S
On: 0.3%, 150M / S On: 0.2%, 150M / S Pass: 2.3%
A copper clad laminate was obtained in the same manner as in Example 1 on the paper base material. The performance is shown in Table 1.

The test methods whose numerical values are shown in Table 1 are as follows for both (1) warpage and (2) twist.

Specimen size 500 x 250 (vertical direction) mm (remaining copper rate 50
%) Treatment Normal condition → Etching → Dry at 160 ° C for 10 minutes Measuring method Measure the four corners by the static method and use the maximum value as the warpage. The absolute value difference between the maximum value and the minimum value is the twist.

(Effects of the invention) As the measurement results shown in Table 1 show, it became possible to manufacture a thermosetting resin copper-clad laminate excellent in warpage and twist by the method of the present invention.

Claims (1)

[Claims] 1. A method for producing a laminated plate, comprising heating and pressing a required number of prepregs obtained by impregnating a paper base material with a thermosetting resin and drying the paper base material, wherein the front and back layers are divided into three layers in the thickness direction. The fiber length distribution of the difference (weight percentage) of 5 types of fiber length distribution of 42M / S (mesh) on, 60M / S on, 100M / S on, 150M / S on, 150M / S pass Absolute value is 1.
A method for producing a laminated plate, which comprises homogenizing so as to be 5% or less.