Mechanical response of BGA micro solder joints with different shape combinations under thermal cycling

Purpose This paper aims to conduct a finite element simulation to study the method of changing the shape of array micro solder joints at dangerous positions in electronic packaging design, to reduce overall stress and strain during service and thereby enhance the fatigue life. Design/methodology/approach Based on the stress-strain response and fatigue life of individual micro solder joints under alternating temperature loads, hybrid micro solder joints were designed with a drum-shaped middle part and an hourglass-shaped/laminated drum-shaped part on both sides. Through finite element analysis, the mechanical responses of the three different-shaped hybrid micro solder joints under temperature cycling were studied and analyzed. Findings The finite element analysis result illuminates that the stress of laminated drum-shaped micro solder joints is the smallest, and the fatigue life is the largest. According to the calculated results of the single solder joints, hourglass-drum-shaped, laminated drum-drum-shaped and all drum-shaped micro solder joint arrays are designed. The results show that the maximum stress produced by the laminated drum-drum-shaped and hourglass-drum-shaped micro solder joint is small, which is 46.17 MPa and 46.64 MPa, respectively. While all drum-shaped micro solder joints are the largest (47.02 MPa). The fatigue life of hourglass-drum-shaped micro solder joints is the longest. Originality/value According to the calculated results of individual solder joints, an innovative three-dimensional hybrid micro solder joint array model is proposed to characterize the influence of micro solder joint shape on temperature-dependent behavior.