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 profiles 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 profile 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 influence of temperature history on solder joint fatigue life. In order to measure deformations in the solder joint under cycling loading, a new Moire interferometry grating replication technique was developed to be able to measure strain field during fatigue testing.