Method of producing a thin film multilayer wiring board

A thin film multilayer wiring board-producing method comprising the steps of:

• (1) forming a first metallic undercoat film on a substrate, then forming a soluble insulating film on said metallic undercoat film, forming grooves in said soluble insulating film so that at least a part of the metallic undercoat film is exposed at the bottom of each of the grooves, and then filling a first conductor in said grooves by electroplating, thereby forming a first layer;
• (2) subsequently forming an insoluble insulating film on said first layer or on a patterned metallic undercoat film formed on said first layer, which metallic undercoat film is electrically connected to said conductor provided in the first layer, forming grooves in said insoluble insulating film so that at least a part of the first layer or the metallic undercoat layer formed on the first layer is exposed at the bottom of each of the grooves, and then filling a second conductor in said grooves by the use of electroplating or both electroless plating and electroplating, thereby forming a second layer on said first layer or on the metallic undercoat layer formed on the first layer;
• (3) subsequently repeating said step (2) one or more times to provide a multilayer construction;
• and
• (4) subsequently removing said soluble insulating film and a part of said first metallic undercoat film which is exposed, and forming an insoluble insulating film at those portions from which said soluble insulating film and said first metallic undercoat film have been removed.