Analysis of stress strain and shape size optimization of 3D micro-scale CSP solder joints in random vibration

Three-dimensional finite analysis models of micro-scale chip-scale package were set up in ANSYS. Micro-scale chip-scale package (CSP) solder joints were analyzed in the random vibration of loads, then stress and strain distribution of micro-scale CSP were obtained. And the effects of different solder materials, pad diameter, and solder joint volume to stress and strain of micro-scale CSP solder joints were analyzed. The size of the solder joint, solder joint height, the diameter of pad size as design parameters, the value of stress of the micro-scale CSP solder joints as the target value are applied to design and calculation of 17 sets of experiments using computational simulation. The stresses and shape parameters of micro-scale CSP solder joints are fitted by the response surface method and genetic algorithm for fitting function optimization. The results show:the CSP solder joint parameters with the minimum value of stress in the random vibration is, the maximum size of 0.093 mm solder joint, the height of solder joint is 0.077 mm, the radius of the pad is 0.068 mm. Finally, the optimal combination is verified by simulation experiments:the result of optimal combination is better than 17 sets of experimental results, and the optimization of the micro-scale CSP solder joint structure in the random vibration is realized.