MANUFACTURE OF PRINTED CIRCUIT BOARD

摘要

PURPOSE:To obtain sufficient solder wettability and to solder with high reliability by allowing silver powder to adhere onto thermally curable conductive paste before the thermally curable conductive paste on an uppermost layer printed on an insulating board is cured. CONSTITUTION:A circuit pattern 2 of thermally curable silver paste such as an epoxy silver paste is printed on an insulating board 1. Silver powder 3 is applied to at least the soldered part of the pattern 2 before the pattern 2 is solidified but still viscous. Then, the pattern 2 is thermally cured, and the silver powder of the part except the pattern 2 is washed out. Then, the solder wettability of the pattern 2 is obtained by the powder 3. Since the thermoplastic conductive paste is not used, no void is generated due to the impregnation and foaming of solder flux to obtain a printed circuit board which can be soldered with high reliability.