Patent ID: 6962726

Claim:
A production method for a substrate for a flexible print wiring board, the method comprising: applying a polyimide-based resin precursor solution directly on an electrically conducting material for formation of a polyimide-based resin precursor layer; and thermally curing the polyimide-based resin precursor layer for production of a flexible print wiring substrate having a polyimide-based resin layer; wherein a solution of a polyimide-based resin precursor (B), which is one out of two types of polyimide-based resin precursors, is applied directly on the electrically conducting material; wherein a solution of the other polymide-based resin precursor (A) is applied on a layer of the polyimide-based resin precursor (B) prior to thermalcuring, the polyimide-based resin precursor (A) counterbalancing residual strain generated in a polyimide-based resin formed by the thermalcuring of the polyimide-based resin precursor (B); wherein a polyimide-based resin precursor having a higher thermalcuring rate than the polyimide-based resin precursor (B) is employed as the polyimide-based resin precursor (A).