Abstract: This invention relates to a laminate which is excellent in heat resistance after moisture absorption required in a lead-free solder joint, and is suitable for use in flexible printed wiring boards or HDD suspensions. The laminate for electronic materials of this invention is constituted of a conductor layer and an insulating resin layer having a polyimide-based resin layer (A) and a polyimide-based resin layer (B). The polyimide-based resin layer (A) constituting the insulating layer includes a polyimide-based resin obtained by reacting a diamine containing 40 mol % or more of 4,4?-diamino-2,2?-dimethylbiphenyl with an aromatic tetracarboxylic acid, and the polyimide-based resin layer (B) includes a polyimide-based resin containing 80 mol % or more of a structural unit generated from bis(4-aminophenoxy)benzene or 2,2-bis[4-(4-aminophenoxy)phenyl]propane, and pyromellitic acid, benzophenonetetracarboxylic acid, diphenylsulfonetetracarboxylic acid or biphenyltetracarboxylic acid.

Abstract: This invention relates to a laminate which is excellent in heat resistance after moisture absorption required in a lead-free solder joint, and is suitable for use in flexible printed wiring boards or HDD suspensions. The laminate for electronic materials of this invention is constituted of a conductor layer and an insulating resin layer having a polyimide-based resin layer (A) and a polyimide-based resin layer (B). The polyimide-based resin layer (A) constituting the insulating layer includes a polyimide-based resin obtained by reacting a diamine containing 40 mol % or more of 4,4′-diamino-2,2′-dimethylbiphenyl with an aromatic tetracarboxylic acid, and the polyimide-based resin layer (B) includes a polyimide-based resin containing 80 mol % or more of a structural unit generated from bis(4-aminophenoxy)benzene or 2,2-bis[4-(4-aminophenoxy)phenyl]propane, and pyromellitic acid, benzophenonetetracarboxylic acid, diphenylsulfonetetracarboxylic acid or biphenyltetracarboxylic acid.

Abstract: This invention relates to laminates for use in HDD suspensions which are composed of a stainless steel base material and successive layers formed thereon of polyimides and an electrical conductor and in which the linear expansion coefficient of the polyimide layer is controlled in the range of 1×10−5/° C. to 3×10−5/° C. and the adhesive strength between stainless steel and polyimide and that between polyimide and electrical conductor are controlled at 0.5 kg/cm or more. This invention also relates to a process for preparing laminates for use in HDD suspensions comprising applying a solution of polyimide precursors or polyimides to a stainless steel base material with a thickness of 10 to 70 &mgr;m in one layer or more, drying, performing heat treatment at 250° C. or more to form a layer of polyimides with a thickness of 3 to 20 &mgr;m and a linear expansion coefficient of 1×10−5/° C. to 3×10−5/° C.