Unveiling High Performance Solder Alloys for Automotive Applications

Abstract

Vehicle electrification and advances in autonomous driving technologies are creating unique opportunities and challenges in the automotive electronics assembly industry. The ever-increasing demand of reliability at higher temperatures and longer service life, especially for automotive electronics, is leading to the evolution of high reliability solder alloy design in the electronics assembly industry. The combination of harsh operating conditions, increasing power densities, and miniaturization has added to the complexity of assembly designs in the automotive electronics market for which traditional surface mount solders are no longer applicable. Thermo-mechanical reliability of solder alloys under harsh operating conditions has been a primary factor for defining suitability and selection of solder alloy for next generation designs. A next generation high reliability alloy for automotive electronics is introduced herein. The microstructure of this novel alloy consists of a well-distributed eutectic phase and finely distributed precipitates of intermetallic compounds which contributes towards solid solution strengthening as well as precipitation strengthening. It is shown that a high-temperature superior creep strength improvement of more than 100% over existing high reliability alloys is achieved at temperatures of 150°C. This and other mechanical properties of the bulk alloy are then correlated to performance with thermal cycling testing under extreme conditions. The novel alloy showed significantly higher thermal cycling performance, exhibiting more than 40% increase in the characteristic life over other existing high-reliability alloys while maintaining traditional surface mount target reflow temperatures. Considering these results, this new class of alloys has the capability to meet the increasingly challenging reliability requirements of automotive electronics.