Effect of solder joint parameter on vibration fatigue reliability of high density PCB assembly

In order to explore the influence of solder joint parameter on vibration fatigue reliability of high density PCB assembly, a three-dimensional simulation model which was almost completely in keeping with test samples was created, and the modal parameters were obtained through modal test and finite element method respectively. Based on the verification of FEM model correctness, through designed different solder joint parameters, such as height, diameter, and material, and based on GJB-150.16-86 vibration test standard, random vibration finite element simulation was being done, and vibration parameters were picked up and analyzed. The result shows that more PCB fixations could increase the first frequency, decrease the deformation of PCB. Moreover, solder joint stress and strain decreases with solder joint height decreasing and diameter increasing, but when height and diameter reaches a certain value, stress and strain will almost keep constant. Under the same conditions, the order of the strains of the joints is: lead solder joints (Sn63Pb37) > mixed solder joints (79% SAC and 21% SnPb) > lead-free solder joints (SAC305). Consequently, more PCB fixations and solder joints which have smaller height, larger diameter or have lead-free will decrease stress and strain of key positions of PCB assembly, and BGA (ball grid array) devices should be placed near the region which has more fixation positions. Finally, based on stress and strain failure criteria, it can make some references for predicting and optimizing random vibration fatigue life of solder joints, guiding BGA layout and selecting solder joints.