Evaluation of Critical Design Parameters for Surface Mount Leadless Solder Joints Subjected to Thermal Cycling

Abstract Failures in electronic packaging under thermal fatigue often results from cracking in solder joints due to creep/fatigue crack growth. A nonlinear, time-dependent finite element analysis was performed to study the effect of critical design parameters on thermal reliability of leadless chip capacitor or resistor solder joints. The shear strain range based on thermal hysteresis response was used to study the sensitivity of various parameters, such as solder stand-off height, fillet geometry, Cu-pad length, and component length and thickness. The results were used as guidelines for designing reliable solder joints. In addition, an analytical model for the solder joint assembly was derived. It can be used as an engineering approach for rapid assessment of large amounts of design parameters. The accuracy and effectiveness of the analytical model were evaluated by comparing with finite element results.