JP2000058989A - Flexible metal wheel laminate plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize excellent dimensional stability without sacrifice of adhesion and to enhance moisture swelling characteristics after pattern formation by employing a material having a moisture swelling coefficient lower than a specified value in the base film of an adhesive sheet. SOLUTION: Metal plates are laminated through an adhesive sheet on the opposite sides of an insulation layer, i.e., a base film, to obtain athree layer structure wherein the moisture swelling coefficient of the base film is set at 200 ppm or below and the thickness of the adhesive layer is set at 5 μm or less. The metal plate to be laminated is composed of stainless steel, Cu, Fe, or the like, and the base film employed in the adhesive sheet is composed of non-thermoplastic resin. Coefficient of thermal expansion of the adhesive sheet is controlled by selecting a base film having coefficient of thermal expansion lower than that of the metal being used and then determining the thickness of the adhesive layer roughly using the coefficient of thermal expansion of a thermoplastic polyimide forming the base film and the adhesive layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal laminate used by patterning a metal portion.

[0002]

2. Description of the Related Art Conventionally, a metal laminate has a large coefficient of hygroscopic expansion of a portion of an adhesive resin exposed after a pattern is formed, and therefore depends on a change in the amount of moisture absorbed by an adhesive corresponding to a change in environmental humidity. Repeat contraction and expansion. This causes undulations in the product, defects such as misalignment in the subsequent processing steps, etc., and greatly affects the reliability of the final product. In order to reduce the influence of shrinkage and expansion due to changes in the amount of moisture absorption, in a metal laminate using an adhesive sheet as an insulating layer, the coefficient of moisture absorption and expansion of the exposed adhesive layer after pattern formation and the amount of moisture absorption should be reduced. Is effective, but it is very difficult to improve these properties in order to obtain good adhesion to metal.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a flexible metal foil laminate excellent in dimensional stability when absorbing moisture.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a metal laminate having improved dimensional stability and improved moisture absorption / expansion characteristics after pattern formation without impairing adhesion to metal. By using a material having a coefficient of hygroscopic expansion of 20 ppm or less and a thickness of 5 μm or less for the base film of the adhesive sheet also used as the insulating layer, one side of the adhesive layer is fixed to the base film, and the dimensions are restricted. Due to this effect, the apparent hygroscopic expansion coefficient of the adhesive layer itself is affected by the hygroscopic expansion coefficient of the base film and is reduced.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The metal laminate according to the present invention basically has an adhesive sheet on an insulating layer, and the metal adhered to both sides thereof is not limited to a particular material, and the same applies to the case of forming a multilayer laminate. Specific examples of the metal to be stacked here include stainless steel, Cu, Fe, Ni, Mo, and Al.

[0006] A non-thermoplastic resin is usually used as a base film used for the adhesive sheet.
Polyimide, polyamide, polyamide imide, nylon and the like are used. More specifically, there may be mentioned a polyimide film Upilex series of thermoplastic Ube Industries, a polyimide film Apical series manufactured by Kanegafuchi Chemical Co., a polyimide film Kapton series manufactured by DuPont, and an amide film Aramica series manufactured by Toray Industries, Inc.

As a control of the thermal expansion coefficient of the adhesive sheet,
Basically, after selecting a base film with a coefficient of thermal expansion lower than the coefficient of thermal expansion of the metal to be used, the coefficient of thermal expansion of the thermoplastic polyimide forming the base film and the adhesive layer is determined using the following empirical formula. Estimate the layer thickness.

The coefficient of thermal expansion of metal = the coefficient of thermal expansion of the adhesive sheet = (the coefficient of thermal expansion of the base film × the thickness of the base film + the coefficient of thermal expansion of the adhesive × the total thickness of the adhesive layer) / the total thickness of the adhesive sheet After preparing the adhesive sheet having the thickness of the adhesive layer, the thermal expansion coefficient is measured, and the thickness is adjusted again and controlled so that the adhesive layer thickness is actually the same as that of the metal.
The term "the same coefficient of thermal expansion as that of a metal" as used herein means that the object of the present invention is sufficiently achieved if the coefficient of thermal expansion of the adhesive sheet is within ± 5 ppm of the coefficient of thermal expansion of the metal. The bonding with the metal is performed by press bonding with a press, a laminator or the like.

[0009]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples. Here, as an index of dimensional stability at the time of moisture absorption, a disk having a diameter of 75 mm was prepared by etching a single-sided metal of a metal laminate, and the amount of warpage after leaving for 24 hours at a temperature of 23 ° C. and a humidity of 50% was used. Compared.

Example 1 An all-polyimide adhesive sheet formed by using a polyimide film, Apical HP (12.5 μm in thickness) manufactured by Kaneguchi Chemical Industry Co., Ltd. as a base film, and forming thermoplastic polyimide PI-A (3 μm in thickness) on both sides thereof And OLIN rolled copper foil C7025 (thickness: 18μm), Nippon Steel stainless steel foil SUS304
H-TA (thickness 18 μm) was laminated on both sides of the adhesive sheet, and hot-pressed using a hot press. The adhesive sheet thus obtained has a coefficient of hygroscopic expansion of 10 ppm, and the amount of warpage of the copper-etched disk having a diameter of 75 mm is 2 mm with the resin surface facing upward.
Met.

Comparative Example 1 An all-polyimide adhesive sheet having a base film made of polyimide film Apical HP (12.5 μm thick) manufactured by Kaneguchi Chemical Industry and thermoplastic polyimide PI-A (10 μm thick) formed on both sides thereof And OLIN rolled copper foil C7025 (thickness: 18μm), Nippon Steel stainless steel foil SUS304
H-TA (thickness 18 μm) was laminated on both sides of the adhesive sheet, and hot-pressed using a hot press. The adhesive sheet thus obtained has a coefficient of moisture absorption and expansion of 30 ppm, and the amount of warpage of the copper-etched disk having a diameter of 75 mm is 10 m above the resin surface.
m.

Example 2 An all-polyimide adhesive formed by forming a polyimide film, Apical HP (10 μm thick) manufactured by Kaneguchi Chemical Industry Co., Ltd. on the base film and forming a thermoplastic polyimide PI-AU (2 μm thick) on both sides of the base film Sheet and (thickness: 18μ
m), NGK beryllium copper alloy foil (thickness: 14μ)
m) and Nippon Steel stainless steel foil SUS304H-TA (18μm thick)
Were laminated on both sides of the adhesive sheet, and heated and pressed using a hot press. The adhesive sheet thus obtained had a coefficient of hygroscopic expansion of 10 ppm, and the amount of warpage of the copper-etched disk having a diameter of 75 mm was 4 mm with the resin surface facing upward.

Comparative Example 2 An all-polyimide adhesive sheet formed by using a polyimide film, Apical HP (10 μm in thickness) manufactured by Kaneguchi Chemical Industry Co., Ltd. as a base film, and forming a thermoplastic polyimide, PI-AU (10 μm in thickness), on both sides thereof. And (thickness: 18 μm),
NGK beryllium copper alloy foil (thickness: 14 μm) and Nippon Steel stainless steel foil SUS304H-TA (thickness: 18 μm) were laminated on both sides of the adhesive sheet, and heated and pressed using a hot press. The adhesive sheet moisture absorption expansion coefficient thus obtained is
The amount of warpage of a disk having a diameter of 75 mm with a copper side etched at 30 ppm was 15 mm with the resin surface facing upward.

Example 3 An all-polyimide adhesive sheet comprising a polyimide film, Apical HP (10 μm thick) manufactured by Kaneka Chemical Industry Co., Ltd. as a base film, and a thermoplastic polyimide PI-A (2 μm thick) formed on both sides thereof. (Thickness: 18 μm), NGK beryllium copper alloy foil (thickness: 14 μm) and Nippon Steel stainless steel foil SUS304H-TA (thickness: 18 μm) were laminated on both sides of the adhesive sheet, and heated and pressed using a hot press. The adhesive sheet moisture absorption expansion coefficient thus obtained is
The amount of warpage of the disk having a diameter of 75 mm with the copper side etched at 10 ppm was 2 mm with the resin surface facing upward.

Comparative Example 3 An all-polyimide adhesive sheet formed by using a polyimide film Apical HP (10 μm thick) manufactured by Kaneka Chemical Industry Co., Ltd. as a base film, and forming a thermoplastic polyimide PI-A (2 μm thick) on both sides thereof. (Thickness: 18 μm), NGK beryllium copper alloy foil (thickness: 14 μm) and Nippon Steel stainless steel foil SUS304H-TA (thickness: 18 μm) were laminated on both sides of the adhesive sheet, and heated and pressed using a hot press. The adhesive sheet moisture absorption expansion coefficient thus obtained is
The amount of warpage of a disk having a diameter of 30 mm and a diameter of 75 mm with the copper side etched was 10 mm with the resin surface facing upward.

With respect to the obtained flexible metal foil laminate, the dimensional stability of each metal foil / polyimide interface and the peel strength after the solder heat resistance test were measured. Here, the solder heat resistance test was performed under the IPC-class3 test condition.

[0017]

According to the present invention, a metal foil laminate with improved dimensional stability and improved moisture absorption properties after pattern formation is provided without impairing the adhesion to metal. Since the adhesive layer is fixed to the base film on one side and the dimensions are constrained, the apparent hygroscopic expansion coefficient of the adhesive layer itself is affected by the expansion coefficient of the base film, and is reduced.

Claims (1)

[Claims] In a metal laminate using a three-layer adhesive sheet having an adhesive formed on both sides of a base film as an insulating layer, the base film has a coefficient of hygroscopic expansion of 20.
ppm, and the thickness of the adhesive layer is 5 μm or less.