Patent ID: 7311966

Claim:
A laminate, comprising: a conductive metal layer for an electronic circuit; and a porous insulating film, wherein the conductive metal layer is laminated on one or both sides of the porous insulating film either directly or via a heat resistant adhesive layer, and wherein the porous insulating film consists essentially of a highly heat resistant polyimide resin film having a fine porous structure wherein a) fine continuous channels reach to both surfaces of the porous insulating film in a nonlinear fashion and have a mean pore size of 0.01 to 0.2 μm in the center of the film and 0.4 to 0.9 μm at both surfaces of the film and a void volume of 15 to 80%; b) the polyimide resin film consists essentially of a polyimide obtained from the combination of at least one tetracarboxylic acid component and a diamine component; and c) the porous insulating film has a thickness of 5 to 150 um, a resistance to passage of air from 30 sec/100 cc to 2,000 sec/100 cc, a heat shrinkage of no greater than ±1% after being heat-treated at 105° C. for 8 hours, and does not contain a dense layer on either of the surfaces.