Study of interfacial reactions between tin and copper by differential scanning calorimetry

Abstract

The interfacial reactions at the solder joints of interest in microelectronic structures have been extensively investigated in order to control the soldering process and thereby to provide strong and reliable solder joints. These reactions comprise the dissolution of a base metal into a molten solder, the concomitant growth of intermetallics in the liquid state, and the growth of intermetallics in the solid state. Various experimental techniques employed include conventional cross-sectional metallography, scanning electron microscopy, electron microprobe analysis, x-ray diffraction and others. In this study, the interfacial reaction between tin and copper has been investigated by using differential scanning calorimetry which provides a simple means to study such reactions and complements information obtained from other techniques. The experimental results have been applied to understand the interfacial reactions in two important examples: one for a soldering process with copper metallization, and another for a high conductivity, Pb-free, electrically conducting adhesive which contains tin-coated copper powder as conducting filler particles.