iNEMI Pb-Free Alloy Characterization Project Report: Part IV - Effect Of Isothermal Preconditioning On Thermal Fatigue Life
Authors: Richard Coyle, et al. Date Published: 10/14/2012
Abstract: The Pb-Free Alloy Characterization Program sponsored by International Electronics Manufacturing Initiative (iNEMI) is conducting an extensive investigation using accelerated temperature cycling (ATC) to evaluate ball grid array (BGA) thermal fatigue performance of a significant number of commercial and experimental Sn based Pb-free solder alloys. The temperature cycling test matrix includes a subset of test cells designed to evaluate the influence of aging or isothermal preconditioning on temperature cycling performance. The aging tests consist of a comparison of two commercial Sn based Pb-free alloys, SAC305 and SAC105, with and without aging for 10 days at 125 °C. Results are presented for multiple temperature cycles in order to compare the relationship between cyclic temperature ranges (delta T) and temperature extremes on the thermal fatigue life and microstructural evolution. The test data and failure analyses are discussed in terms of the relationship to Ag content and to the initial as well as evolving microstructures during temperature cycling.