Automotive Grade WLCSP for Radar Applications

Abstract

Wafer-Level Chip Scale Packages (WLCSPs) are becoming commonplace in the industry due to their small form factor. Applications include industrial and automotive which demand high reliability performance. Additionally, WLCSPs may be superior in some implementations to other package options for RF performance in the mmWave spectrum, which is desired for automotive radar application. In this study the industry’s first auto grade 1 capable large WLCSP package. (~ 72 mm2 body size, 18x15 BGA array, 0.5 mm pitch) will be presented. It will be demonstrated how extensive design enhancements, predictive simulations, careful package materials and process selection and assembly process optimization studies are required to develop a robust package solution. Multiple assembly process experiments and corner studies were conducted to demonstrate robustness of WLCSP package solution to meet automotive grade quality and reliability requirements. Both component/unit level and board level reliability was evaluated as per AECQ100 standards. Robustness margins were confirmed through reliability testing performed up to 2-3x reliability requirements.