METALLURGICAL REACTIONS AT THE INTERFACE OF SN/PB SOLDER AND ELECTROLESS COPPER-PLATED ALN SUBSTRATE

Abstract

Intermetallic formation between electroless-plated copper and Sn/Pb solder is investigated. An interlayer is formed between copper and solder, and segregation of Pb-rich and Sn-rich phases are observed. X-ray diffraction and EDX analysis results suggest that the major intermetallic formed in the interlayer is Cu6Sn5. For the as-plated sample, the adhesion strength of Cu to the AIN substrate after 150 degrees C aging is affected by both the recrystallization and the creep of copper. For the soldered specimen, the presence of intermetallic compound causes cracks to propagate along the intermetallic/Cu interface and results in a decrease of the adhesion strength.