INSULATOR FILM AND SUBSTRATE USING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide an insulator film having a low thermal expansion coefficient and improved adhesion to a plating layer, and a substrate using the same.SOLUTION: An insulator film comprises a coarse grain filler 110, a fine grain filler 120, and a resin 440. The ratio between grain size distributions of the coarse grain filler 110 and the fine grain filler 120 is from 1 to 3 inclusive. Also provided is a substrate using the same. Thereby, the insulator film can be provided which has a high filler filling ratio, prevents the filler from being extruded to a junction interface with a plating layer, and realizes a low thermal expansion coefficient and improved adhesion to the plating layer.