THIN FILM WIRING BOARD AND PRODUCTION THEREOF

PROBLEM TO BE SOLVED: To obtain a method for forming a fine wiring at high density on the smooth surface of an insulation layer by coating a first insulation layer with liquid resin to form a second insulation layer and then forming a second wiring layer to be connected with a first wiring layer through a through hole on the second insulation layer. SOLUTION: An insulation sheet 11 is coated with a liquid insulating resin to form a second insulation layer 14 having smooth surface which is then thermally cured and a metal film 4 is formed in the pattern of the through hole by sputtering aluminum. Subsequently, patterning is carried out and a through hole 5 is made by means of excimer laser and the metal film 4 is etched to form a conductor 6 for second wiring layer. Finally, patterning is carried out using a resist to form a second wiring layer 15 being connected with a first wiring layer 2. According to the method, a fine second wiring layer can be formed at high density while preventing short-circuiting or open circuits of the line.