JP2000052481A - Metal laminate using stainless steel foil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a warpage of a base material and enhance reliability and dimensional stability at the time of processing by using a stainless steel foil having a dimensional contraction rate after cooling which is similar to a metal glued on the other side. SOLUTION: A stainless steel foil having a dimensional contraction rate after cooling similar to a metal glued on the other side is used. A metal laminate may be made of any material so long as an insulation layer and the metal glued on the other side have the same thermal expansion coefficient, and the same is applied to the case where a multilayer laminate is formed. The metal glued may be stainless steel, Cu, Fe, Ni, Mo, Al or the like. To constitute the insulation layer may use a method of applying or curing amide varnish to the stainless steel foil and a method of using a base film. The non-thermoplastic resin used as a base film may be polyimide, amideimide, and amide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated board in which metal is laminated on both sides of an insulating layer widely used for a flexible printed wiring board and the like. One side of the metal laminated here is a stainless steel foil, and more specifically, has excellent dimensional stability, and has a dimensional shrinkage ratio during heating in the longitudinal direction (MD direction) and the width direction (TD direction) isotropic. Is a stainless steel foil. The dimensional stability referred to here indicates not only the coefficient of thermal expansion at the time of temperature rise but also the dimensional resilience at the time of cooling after temperature rise.

[0002]

2. Description of the Related Art In metal laminates which have been widely used for printed wiring boards and the like, the dimensional difference between layers of the laminates during processing is within an appropriate range (within 5%, preferably 1%), and is flat. Or, it is desirable to be in a state close to it. In particular, with the spread of portable terminals in recent years, market demands such as weight reduction of electronic components have been rapidly increasing.
As a result, the necessity of fine pattern processing increases, and the base material is required to have high dimensional stability. However, in a normal metal laminate, the thermal expansion coefficients of the metal foil and the insulating layer are significantly different, and there has been a problem that the dimensional change rate deviates from 0 according to the difference in the thermal expansion coefficients. for that reason,
Conventionally, a method of defining the coefficient of thermal expansion of each layer has been adopted, but the problem of warpage has not been solved.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a metal laminate having reduced warpage of a substrate, high reliability during processing and high dimensional stability.

[0004]

As a result of investigations by the present inventors, the cause of the warpage is not only the coefficient of thermal expansion but also the cooling of the once heated metal foil does not return to the original size. It has also been found that the rate has anisotropy in the longitudinal direction (MD) and width direction (TD) of the metal foil.

In the present invention, not only the thermal expansion coefficient is specified, but also
Dimensional shrinkage after cooling is reduced by using a stainless steel foil close to the metal adhered to the other side to reduce warpage and provide a metal laminate excellent in workability. It is characterized in that the difference in heat shrinkage after high-temperature bonding, which is a main cause of warpage, in the metal laminate is reduced by regulation.

According to the present invention, a metal laminate having an equal thermal contraction difference and no warpage can be obtained, so that a product having excellent workability and excellent dimensional stability at the time of forming a pattern such as a printed board, a TAB base, a CSP board, etc. It is possible to obtain.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The metal laminate according to the present invention is not limited to the material as long as the metal bonded to the insulating layer and the other side has the same coefficient of thermal expansion,
This is the same when forming a multilayer laminate. The type of metal to be bonded is not limited, and includes stainless steel, Cu, Fe, Ni, Mo, Al, and the like. In order to form the insulating layer, there are a method of applying and curing polyimide, amide imide, and amide varnish to a stainless steel foil and a method of using a base film. Examples of the non-thermoplastic resin used as the base film include polyimide, amide imide, and amide. More specifically, there may be mentioned polyimide film Apical series manufactured by Kanegabuchi Chemical Co., Ltd., polyimide film Upilex series manufactured by Ube Industries, and polyimide film Kapton series manufactured by Toray DuPont.

[0008]

Next, examples of the present invention will be described. However, the present invention is not limited to the following examples. (Example 1) Using a double-sided adhesive sheet in which a thermoplastic polyimide adhesive was applied to both sides of a base film, a stainless steel foil (A; Nippon Steel Corp.
04HTA) and two types of stainless steel foils with different dimensional stability
(B, C) were laminated. The dimensional stability was measured by TMA, and was calculated by comparing the linear expansion coefficient during heating between 30 ° C. and 300 ° C. with the linear expansion coefficient during cooling. Table 1 shows the results of the dimensional stability. Stainless steel foil A and adhesive sheet and B, A and adhesive sheet and C are laminated and vacuum hot pressed (300
° C, 75 kg / cm ² , 1 hour), and the warpage of a 75 mmφ coupon after pressing was measured. Table 2 shows the measurement results.

(Example 2) The stainless steel foil A and the adhesive sheet, copper foil (C7025 manufactured by Ohlin), and the stainless steel foil B and the adhesive sheet, copper foil (C702 manufactured by Ohrin) in Example 1 were used.
5) A stainless steel foil C, a double-sided adhesive sheet, and a copper foil (copper foil C7025 manufactured by Ohlin Co., Ltd.) were laminated, and subjected to vacuum hot pressing under the same conditions as in Example 1. Table 1 shows the dimensional stability of the copper foil. The warpage of the coupon (75 mmφ) after pressing was measured in the same manner as in Example 1. Table 2 shows the measurement results.

[0010]

[Table 1]

[0011]

[Table 2]

[0012]

As shown in the examples, the metal laminate of the present invention reduces warpage of the substrate by using a stainless steel foil with dimensional stability specified, and increases reliability and dimensional stability during processing. This has the effect of improving.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takao Kimura 2-1-1 Tango-dori, Minami-ku, Nagoya-shi, Aichi F-term (reference) in Mitsui Chemicals, Inc. 4F100 AB01B AB04A AB33A AK49G BA02 CB00 GB43 JL04 5E315 AA03 BB04 BB05 BB16 CC14 GG05 GG22

Claims (1)

[Claims] 1. A metal laminate using a stainless steel foil, wherein a stainless steel foil is used as the metal used for the metal laminate, and the dimensional stability of the metal is made equal to the dimensional stability of the other metal to be laminated. Board.