Multi-Axis Loading Effect on Edgebond and Cornerfilled WLCSP Thermal Cycling Performance
Authors: Andy Hsiao, Tae-Kyu Lee, Edward Ibe and Karl Loh Company: Portland State University and Zymet Date Published: 9/22/2019
Abstract: Various external load conditions affecting components on electronic devices and modules are constant factors, which need to be considered for the component long-term reliability. Recently, to enhance the high stress component thermo-mechanical cycling performance, various types and configuration using edgebond and cornerfill technology are introduced and tested. These applications induce a multi-axis loading condition, which alter the degradation mechanism and failure location during thermal cycling, which need closer investigation. In this study, high stress 12x12mm2 wafer level chip scale packages (WLCSP) were selected and subject to thermal cycling with full-edgebond, dot-edgebond and cornerfill adhesive, which improves the characteristic lifecycle numbers base on the configurations, but altered the failure location due to different stress conditions. The -40 to 125oC thermal cycling profile revealed localized degradation per configuration during thermal cycling, showed a shift of the crack propagation path, based on full-edgebond, dot-edgebond and cornerfill adhesive sample conditions. Through these series of observation, the interconnect thermal cycling degradation mechanisms are able to be explained. The correlation between the stress condition and microstructure are presented and discussed based on EBSD analysis.