The finite element analysis model of BGA (Ball Grid Array) solder joints is established.The height of solder joints

the maximum radial dimension of solder joints

the diameter of upper and lower solder joints are selected as design variables

and the stress of solder joints is taken as target value.29 groups of solder joints with different levels are designed and simulated by response surface methodology.The regression equation of solder joint stress and structural parameters is established.The structural parameters of solder joint are optimized based on the regression equation and genetic algorithm

and the optimal level combination of structural parameters with minimum solder joint stress is obtained.The results show that for lead-free solder SAC387

the solder joint stress decreases with the increase of solder joint height

and decreases with the decrease of maximum radial dimension;the combination of solder joint level with minimum stress is:solder joint height 0.38mm

maximum radial dimension 0.42mm

upper pad diameter 0.34mm and lower pad diameter 0.35mm.The results show that the maximum stress of the solder joint decreases by 4.66MPa after optimization

and the structure optimization of BGA solder joint is realized.