FE analysis and experimental testing of a 4-pin ceramic test vehicle with tin-lead and tin-silver-copper solder joints

摘要

Solder joint lifetime predictions are typically based on FE simulation to determine the load on the joints and then an empirical equation to derive the expected lifetime. In this paper the authors presented a test vehicle for testing the lifetime of solder joints and the results that were obtained by temperature cycling, including the lifetime prediction models that were created based on the experimental results. The test vehicle is a ceramic substrate with four solder joints. It has a very simple geometry that is well-suited for FE analysis. The board is a two-layer PCB with traces for 4-wire resistance measurements. The resistance was measured in regular intervals and mean lifetimes were extracted for the observed failures by fitting the results to the Weibull-equation with a maximum likelihood estimator. Two solders were used for soldering the test vehicle to the PCB: eutectic tin-lead solder and eutectic tin-silver-copper solder. Temperature-shock tests were performed with four different test conditions. Based on these experimental results, coefficients for the two most common lifetime models, the Coffin-Manson equation and the creep strain energy density approach, were determined. The logarithmic standard deviation was used to quantify the mean error of the predictions from the lifetime models.