INSULATING RESIN FILM, PRODUCTION METHOD OF INSULATING RESIN FILM, PRELIMINARILY CURED PRODUCT, LAMINATE, AND MULTILAYER SUBSTRATE

摘要

PROBLEM TO BE SOLVED: To provide an insulating resin film having such properties that dimensional changes of a cured product due to heat can be reduced and that when a metal layer is formed on a surface of the cured product, adhesion strength between the cured product and the metal layer can be increased.SOLUTION: An insulating resin film 1 relating to the present invention is used after a roughening treatment. The insulating film 1 has a first major surface 1a and a second major surface 1b. The first major surface 1a is subjected to the roughening treatment. The insulating resin film 1 contains an epoxy resin, a curing agent and silica 2. In the insulating resin film 1, the silica 2 is unevenly distributed in such a manner that the amount of silica 2 on the first major surface 1a side to be subjected to the roughening treatment is smaller than the amount of silica on the second major surface 1b side.