LEAD PIECE JUNCTION OF ELECTRONIC CIRCUIT BOARD AND ELECTRONIC CIRCUIT BOARD

PURPOSE:To improve junction strength of each board with each lead piece by depositing two-layer plating layer consisting of Ag and Cu through an Ni plating layer on circuits which are formed at both ceramic and enameled boards or at a ceramic flame coating board. CONSTITUTION:After forming required circuits by printing conductors to both ceramic and enameled boards or to a ceramic flame coating board. Ni plating is performed to a lead junction part exposed to the outside in order to improve Ag solder wettability. Further, a two-layer plating of Ag and Cu is performed after selecting the thickness of a plating layer so as to obtain an alloy composition that is selected according to the material quality of joined lead pieces. Further, after making each lead piece come closely into contact with a lead piece junction part, the two-layer plating layer is fused by heating at an Ag-Cu alloy eutectic temperature or more and at an Ag melting point or less and then, junction of each board and lead piece is performed. It is preferable to perform a diffusion thermal treatment in an atmosphere of H2 or N2, and or the mixture of these gases or in a vacuum atmosphere.