Selecting a Temperature Time History for Predicting Fatigue Life of Microelectronics Solder Joints

Temperature cycling tests are standard industry practice for determining the thermomechanical fatigue life of solder joints. Industry-standard temperature pro¢les usually start from room temperature, then go to a high temperature, then to a cold temperature, and then back to room temperature. In addition, most of the time, the temperature pro¢le contains dwell times at the highest and lowest temperatures. The dwell time at a high temperature corresponds to the on-state storage of the device, and the cold-temperature dwell time simulates the off-state storage of the device. In this study, the actual temperature history of a Ball Grid Array (BGA) package in a laptop computer was measured in situ. Experimental reliability studies were conducted using the in situ measured temperature history as well as industry-standard temperature history. This article presents the in£uence of temperature history on solder joint fatigue life. In order to measure deformations in the solder joint under cycling loading, a new Moirë interferometry grating replication technique was developed to be able to measure strain ¢eld during fatigue testing. Journal of Thermal Stresses, 24:1063^1083 , 2001 Copyright # 2001 Taylor & Francis 0149-5739 /01 $12.00 + .00