TWI602691B

To attain simultaneously the prevention of a tip from sinking into a substrate film layer in bonding the tip to metal wiring (namely mountability) and properties which have a trade-off relationship therewith, namely, flex resistance, folding endurance, pliability, and reduction in spring back which is seen as a problem in mounting a circuit board in a bent state or the like. A metal foil laminate composed of a metal foil and a substrate film which is made of a heat-resistant resin composition that comprises a polyimide-based resin crosslinked with an epoxy resin and which is laminated on at least one surface of the metal foil, characterized by satisfying the requirements (a) and (b): (a) when the total amount of the polyimide-based resin and the epoxy resin is taken as 100 mass%, the amount of the epoxy resin is 0.1 to 10 mass%; and (b) the insoluble matter rate of a base film which has been prepared by removing the metal foil from the metal foil laminate is 40% or more as determined by adding N-methyl-2-pyrr