| 摘要 |
PROBLEM TO BE SOLVED: To provide a built-up printed wiring board in which a surface smoothness and board thickness precision are superior, a galss transition temperature is high, and a migration-resistance and electric insulation after the humidity absorption are superior. SOLUTION: In this method, 75 to 100 wt.% of thermosetting resin composition solution is applied to a thickness 15 to 50μm to a surface of a board having a metal foil circuit which is to be an inner layer, and a solvent is removed by drying. After half-cured so that the gelling time is 10 to 100 sec. at 170 deg.C, 75 to 100 wt.% of thermaosetting resin composition solution in concentration is again applied to a thickness 15 to 50μm to the surface, and a solvent is removed by drying, and simultaneously the gelling time of the resin layer applied initially is set 30 sec. or less, and the gelling time of the resin layer applied at the second time is set 30 to 120 sec. or less, so that the total thickness of the resin layers is 10 to 50μm than that of the inner layer metal foil. A metal foil is placed so as to come into contact with the second resin layer, and a lamination is formed by heating under pressure, and further a circuit is formed. |
