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Semiconductor packages using solder balls as interconnect to the printed circuit board (PCB) are very popular especially in mobile products like smart phones. Recent requirement to make the package much thinner is very challenging. The solder ball collapse height after the solder ball is reflowed on the package substrate metal pad would need to be tightly controlled and aligned with the required height to meet the target overall package thickness. Another challenge is that the package has to be developed in a short period of time. In this study, theoretical and solid modeling techniques were developed to estimate the solder ball collapse height and compared with actual evaluation results. With these, the solder ball collapse height could be quickly estimated to make the package design and development faster avoiding several trial evaluations on different combinations of solder ball size, substrate pad solder mask opening diameter and solder mask thickness. Based on the estimation results, using these techniques showed good agreement with actual solder ball height measurements and have now been successfully used in coming up with final package designs in a fast and cost-effective way.
Tian YH, Wang CQ. Shape prediction and reliability design of ball grid array solder joints. Key Engineering Materials. 2007; 2944-2947.
Chiang KN, Yuan CA. An overview of solder bump shape prediction algorithms with validations. IEEE Transaction on Advanced Packaging; 2001.
Zheng JO. Equilibrium configurations of oxygen bubbles on surfaces for applications in nanostructured hematite electrodes. Thesis submitted to Massachusetts Institute of Technology; 2015.
Lin HC, Kung C, Chen RS. Evaluations of the BGA solder ball shape by using energy method. Tech Science Press; 2007.
Josell D, Wallace WE, Warren JA, Wheeler D, Powell IV AC. Misaligned flip-chip solder joints: Prediction and experimental determination of force-displacement curves. Journal of Electronic Packaging; 2002.
Lim SF, Nurulakmal MS. Wetting characterization of flip chip’s lead-free solder interconnect using surface Evolver. Journal of Physics; 2018.
Liu X, Lu G. Effects of solder joint shape and height on thermal fatigue lifetime. IEEE transactions on components and packaging technologies. 2003;26(2):455-465.
Ogunsemi B, Ikubanni P, Adediran A, Agboola O. Effect of stand‑off height on the shear strength of ball grid array solder joints under varying pad sizes. SN Applied Sciences; 2018.
Njoku JE, Mallik S, Bhatti R, Emeka HA, Ekere NN. Effect of component standoff height on thermo-mechanical reliability of Ball Grid Array (BGA) solder joints operating in high-temperature ambient. IEEE 38th International Spring Seminar on Electronics Technology. 2015;231–236.
Lau CS, Abdullah MZ, Mujeebu MA, Yusop NMD. Finite element analysis on the effect of solder joint geometry for the reliability of ball grid array assembly with flexible and rigid PCBs. Journal of Engineering Science and Technology. 2014;9(1):47-63.
Che FX, Pang JHL. Fatigue reliability analysis of Sn–Ag–Cu solder joints subject to thermal cycling. IEEE Transactions on Device and Materials Reliability. 2013; 13(1).
Choubey A, Ghaffarian R. FEA and analysis for BGA/CGA assemblies under thermal cycling. Proceedings of SMTA International; 2016.