Thin-film multilayer wiring board and production thereof

A process for producing a thin-film multilayer wiring board, which comprises the steps of:

• (1) laminating a composite sheet comprising a carrier sheet and an adhesive layer on a substrate having a first metallic wiring layer on the surface thereof so as to contact the adhesive layer with the first metallic wiring layer;
• (2) removing said carrier sheet and hardening the adhesive layer to form an insulating layer;
• (3) forming via holes in said insulating layer;
• (4) filling said via holes with a conductive metal by electroless plating;
• (5) grinding out projected portions of the conductive metal from the surface of said insulating layer to flatten the conductive metal and to-form via studs;
• and
• (6) forming a second metallic wiring layer on said insulating layer and connecting it to said via studs.