JPH0355239A - Paper base laminate - Google Patents

Abstract

PURPOSE:To decrease warpage by processing and dimensional change when a print wiring board is manufactured by impregnating a craft original paper with elongation of 1.8% or less in the longitudinal direction and of 3.0% or less in the width direction as a base material with a resin, laminating it with a metal foil and molding them in a body. CONSTITUTION:After a craft original paper with elongation of 1.8% or less in the longitudinal direction and 3.0% or less in the width direction is impregnated with a resin, it is laminated with a metal foil and the laminate is molded in a body. As a resin with which the paper base material is impregnated, a phenol resin, an epoxy resin, an unsatd. polyester resin etc., can be cited, but the phenol resin is especially suitable from the points of combination with the paper base material, its characteristics and the cost. Impregnation with this resin can be performed over a wide tange of wt. ratio and a curing agent, a curing auxiliary, a thickener, an inorg. additive etc., can be compounded therewith. It is possible thereby to obtain a paper base material laminate with less warpage on processing and dimensional change when a print wiring board is manufactured.

Description

[Detailed description of the invention] (Industrial application field) This invention relates to a paper base laminate.

More specifically, the present invention relates to a highly reliable paper-based laminate that exhibits minimal processing warpage and dimensional change during printed wiring board manufacturing. (Prior art) Conventionally, laminated boards for printed wiring boards have been made using resin-impregnated paper, which is made by impregnating phenol resin or epoxy resin on kraft paper, along with glass substrates such as glass sheets and glass mats, or resin sheets. It is known to use a base material. This paper base material has the characteristics of being easy to use and inexpensive. This paper base material is similar to the case where a glass base material is used, for example, as shown in Fig. 1, (a) Kraft base paper (a) is coated with phenol i! l#
t. or impregnated with resin such as epoxy resin. (b)
Layer the required number of sheets of this resin-impregnated paper base material (a), laminate metal foil such as copper or aluminum for circuit formation (c), and (c) heat and process these to integrate the laminate,
This is a laminate for a specified printed wiring board. The laminate thus manufactured is then subjected to (d) machining, y-ching, etc. to give it a gold finish. Circuit made from lJ foil (c)
In addition, punching is performed to form a through-hole (e) shape. (Problem to be solved by the invention!M) Paper-based m-laminates have been used in the same way as glass substrates, etc., but on the other hand, this paper-based laminate has In some cases, the paper used as the base material has a characteristic of high elongation, and due to this high elongation, processing warpage is unavoidable during processing such as etching and punching during the manufacture of printed wiring boards, and However, the disadvantage was that the rate of dimensional change was large. Such defects have led to deterioration in the quality of printed wiring boards and impair their reliability.

This invention has been made in view of the above-mentioned circumstances, and aims to solve the drawbacks of the conventional laminate base material and to create a highly reliable resin-containing paper base material with low processing warpage and dimensional change rate. (Measures to Solve the Problems) The present invention solves the above problems and has a growth rate of ff! To provide a paper base laminate, characterized in that the base material is kraft paper having a weight of 1.8% or less and a width of 3.0% or less, which is laminated and integrally molded with metal foil after being impregnated with resin. This regulation of 1.8% or less in length and 3.0% or less in width indicates the elongation rate until the paper breaks in the tensile strength test, and paper with the above elongation rate or less is used as the base material. This is a major feature of this invention. Various types of kraft paper can be used, including those of previously used quality. In addition, this paper base material is impregnated with a resin. Examples of the resin used at this time include phenol resin, epoxy resin, and unsaturated polyester resin, but depending on the combination with the paper base material and its characteristics. From a cost point of view, phenol v! J
Fats are exemplified as particularly suitable. The resin impregnation can be carried out in a wide range of weight ratios, but generally it can be about 40-80% by weight. It goes without saying that curing agents, curing aids, thickeners, inorganic additives, etc. may be added. As the metal foil to be laminated and integrated, various metals or alloys such as copper, aluminum, and iron can be used.

A required number of resin-impregnated substrates and metal foils are heated and pressed in accordance with the steps shown in FIG. 1 in the same manner as in the prior art to produce a single-sided or double-sided metal-clad laminate having a predetermined thickness. The temperature at this time is 140-180"C, and the pressure is 80"C.
~140 kg/ad, or more. (Function) In this invention, the elongation rate is 1.8% or less, and the horizontal 3.
By using 0% or less paper as the base material, processing warpage and dimensional change rate can be minimized in laminates that repeatedly expand and contract during processing during printed wiring board manufacturing. As a result, a laminate of much higher quality and reliability than before can be obtained.

When using a paper base material with an elongation rate higher than the above range, the elongation will increase and the shrinkage will also increase.
It degrades the quality of laminates for printed wiring boards. EXAMPLES Hereinafter, the paper base laminate of the present invention will be described in more detail with reference to Examples.

(Example) Kraft paper with various elongation rates shown in Table 1 (thickness 0.2 m
) was impregnated with a phenolic resin varnish having a resin content of 50% by weight so that the resin content after drying was 50% by weight. After drying, six sheets of this resin-impregnated paper base material were stacked, and a copper foil with a thickness of 0.035 cm was placed on the top layer using an adhesive at a pressure of 100 k.
g/cd and laminated molding for 60 minutes at a concentration of 160°C. Single-sided #1 clad phenolic resin-impregnated paper base material W with a thickness of L6 m
A four-layer board was obtained. The tensile strength, processing warpage, and dimensional change rate of the laminates were evaluated. The evaluation method used at this time was as follows. In addition, the elongation rate was taken as the elongation rate up to cutting in the tensile strength test.

(1) Processing warp ■ Warp after pattern creation and etching 250 x 200 rm After cutting, a predetermined pattern is printed and etched to obtain a printed wiring board.

Evaluate the degree of warpage at this time. ■ Warpage after punching Print the resist ink and perform punching after curing.
The magnitude of warpage at this time is evaluated.

<2) Dimensional change: Heat at 120°C for 15 minutes. Evaluate the dimensional change before and after this. These evaluation results are also shown in Table 1. In the examples of the present invention, the processing warpage during etching and punching was small, and the dimensional change rate was also small, compared to the comparative example in which the elongation rate exceeded 1.8% in the vertical direction and 3.0% in the horizontal direction. This shows that the laminate of the present invention is of high quality and excellent in reliability.

Table 1 (Effects of the Invention) According to the present invention, a paper base laminate with small processing warpage and dimensional change rate during printed wiring board production can be obtained.

A high quality, inexpensive paper base laminate is provided by the present invention.

[Brief explanation of drawings]

FIG. 1 is a process cross-sectional view illustrating a conventionally known method of manufacturing and processing a paper base laminate.

Claims (2)

[Claims] (1) A paper base laminate, characterized in that it is made of kraft paper with an elongation rate of 1.8% or less in length and 3.0% or less in width, which is impregnated with resin and then laminated and integrally molded with metal foil. (2) The paper base laminate according to claim (1), which is impregnated with a phenolic resin.