THE INVESTIGATIONS OF THE KINETICS ON INTERMETALLIC COMPOUND GROWTH AT THE INTERFACE OF THE SUBSTRTE COPPER AND TIN OR TIN-LEAD COATING AND THE SOLDERABILITY

The studies ot copper-tin intertnetallic compounds growth rates at the interface of the copper substrate and tin or lead-64-76% tin coating were conducted in this paper. The thickness of intermetallic compound layers formed with a variety of aging time at 100±1℃ and 155±2℃ had been measued. The dependences of the intermetallic compound thickness on time and temperature were shown. It had experimentally been observed that the growth rate of compound in lead-tin coating at near eute-ctic point is faster than that in purely tin coating. The compound layers have not been detected on the leader which had been stored at room temperature for about a year. In addition, the relationship between the remaining coating and the solderability of leader was also discussed.