Patent ID: 8993108
Filing Date: 2015-03-31
Classification: B32B,H05K,Y10T

Abstract:
1. A multilayer polyimide film being a polyimide film having a multilayer structure, comprising: a core layer; and clad layers provided on each side of the film, the clad layers being exposed, the core layer being a non-thermoplastic polyimide having an average coefficient of linear expansion at a temperature from 100° C. to 200° C. in a range of 5 ppm/° C. to 20 ppm/° C., each of the clad layers being a polyimide having a peeling strength of 3 N/cm or less, the film as a whole having an average coefficient of linear expansion at a temperature from 100° C. to 200° C. in a range of 9 ppm/° C. to 30 ppm/° C., and where (a) is an average modulus of elasticity of the core layer and (b) is an average modulus of elasticity of the clad layers; wherein the peeling strength denotes an adhesion strength determined by the following method: (i) a copper foil having a thickness of 18 μm is provided on (a) both sides of the multilayer polyimide film itself or on (b) both sides of a polyimide film formed as a 12.5 μm-thick single layer film from a polyamic acid solution from which the clad layer is made, (ii) the copper foil and the polyimide film are thermally compressed together at a laminating temperature of 380° C., laminating pressure of 0.8 t, and line speed of 1 m/min, so as to prepare a sample according to JIS C6471 “6.5 Peeling Strength”, and (iii) a load for peeling the metal foil part having a width of 5 mm with a peeling angle of 180 degrees at a peeling rate of 50 mm/min is measured.