STUDY OF INTERFACIAL REACTIONS BETWEEN TIN AND COPPER BY DIFFERENTIALSCANNING CALORIMETRY

The interfacial reactions at the solder joints of interest in microele ctronic structures have been extensively investigated in order to cont rol the soldering process and thereby to provide strong and reliable s older 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. Va rious experimental techniques employed include conventional cross-sect ional metallography, scanning electron microscopy, electron microprobe analysis, x-ray diffraction and others. In this study, the interfacia l reaction between tin and copper has been investigated by using diffe rential scanning calorimetry which provides a simple means to study su ch reactions and complements information obtained from other technique s. The experimental results have been applied to understand the interf acial reactions in two important examples: one for a soldering process with copper metallization, and another for a high conductivity, Pb-fr ee, electrically conducting adhesive which contains tin-coated copper powder as conducting filler particles.