INVESTIGATION OF THE PERFORMANCE OF SAC AND SACBi LEAD-FREE SOLDER ALLOYS WITH OSP AND IMMERSION SILVER PCB FINISHES

摘要

The primary objective of this research is to compare thernperformance of two lead-free solder alloys (Sn-Ag-Curn(SAC) and Sn-Ag-Cu-Bi (SACBi)) when assembled withrnOSP and Immersion silver (ImAg) PCB finishes. Thernperformance of the solder joints obtained with theserncombinations of alloy and PCB finish is evaluated usingrnshear testing, under as-soldered, thermal aging and thermalrnshock test conditions. The shear energy required to shear thernsolder joints is used as the primary response variable torninvestigate the performance of the joints. Sn-Pb componentsrnassembled on a PCB with HASL finish using Sn-Pb solderrnis used as the control for comparing the performance of Sn-rnPb and lead-free solder joints. Cross-sectional analysis isrnused to investigate the intermetallic growth due to thermalrnaging and crack propagation due to thermal shock.rnPreliminary results reveal that under all three test conditionsrnlead-free solder joints require higher shear energy than Sn-rnPb solder joints. The two surface finishes used in thisrnresearch were not found to be significantly affecting thernsolder joint strength. The SAC alloy was found to performrnbetter under as-soldered and thermal aging conditions whenrncompared to SACBi and Sn-Pb alloys. However, duringrnthermal shock SACBi solder alloy exhibited superiorrnperformance.