Novel Lead-Free Solder Alloys Development for Automotive Applications
Authors: Weiping Liu, Ph.D. and Ning-Cheng Lee, Ph.D. Company: Indium Corporation Date Published: 9/27/2015
Abstract: For high power device applications, where silicon die is mounted onto leadframe with solder preform, six lead-free solder alloys were evaluated for reliability against 92Pb5.25Sn2.75Ag. The solder joints were pre-conditioned with Thermal Shock treatment, then followed by shear strength test, or cross-sectional analysis, or C-SAM and XRay analysis. The shear strength test and cross-sectional analysis data are consistent, with results indicating that the top four alloys are SAC+SbBi alloys, followed by SAC+SbNi. SAC+SbBiNiCo and high-Pb alloy are poorer, with solder paste joint being the poorest, attributable to the high voiding within joints. C-SAM data showed different reliability data trend, probably due to misleading signal caused by cracked joints with solder remaining in contact. X-ray voiding data also showed poor correlation with shear strength and crack.
lead-free solder, automotive, high power device, preform, reflow, thermal shock, die shear, reliability