Joint Mechanism of Press-Soldered Joints in Copper to Copper

Copper to Cu lap joint was made by resistance heating, applying pressure simultaneously. The Cu plate was pre-soldered and the alloyed layer was pre-formed by using Pb--50Sn solder. Then the joint mechanism of press-soldered joints was analyzed. The reason of enhancing strength and heat resistance heated by applying voltage in press-soldered joints is summarized as follows. (1) Solder composition turns to Cu--Sn alloy composition. (2) Joint layer with higher melting point was formed in which Cu increases and Sn decreases. (3) In terms of the crystal structure, Cu sub 3 Sn, Cu sub 6 Sn sub 5 , and Cu( alpha ) phases turn into Cu sub 41 Sn sub 11 and Cu( alpha ) phases which have high heat resistance.