Digital image correlation for solder joint fatigue reliability in microelectronics packages

Digital image correlation (DIC) measurement of solder joint strain resulting from thermal cycling fatigue loading is reported in this study. The experimental measurements are compared to finite element analysis modeling of solder joint strain in a plastic ball grid array (PBGA) soldered assembly. The PBGA test sample was cross-sectioned and mounted in a thermal cycling chamber and subject to in-situ temperature cycling between 25 °C and 100 °C. The local solder joint strain range accumulated during temperature cycling was measured by the DIC technique. The in-plane inelastic strains in the solder joint accumulated after the 7th and the 14th thermal cycle were measured directly by the DIC system and computed by an element-based DIC analysis software developed by the author. Finite element analysis was conducted to simulate the loading used in the experiments and comparison was made to the experimental results. The measured and predicted displacement field patterns show satisfactory correlation and agreement.