Thermal Failure Analysis And Optimization Design Of Microelectronic Packaging Device

Because of its excellent performance, microelectronic packaging device is widely used in various fields, such as communications, transportation, defence, aerospace and medical. With the continuous improvement of its packaging density, its importance get a remarkable promotion, and the failure of packaging structure could even cause serious consequences. After extensively reviewing the domestic and foreign literature related to this research, this paper analyzed thermal fatigue failure behavior of the solder joints, where the failure of microelectronic package mainly occurred, by finite element method. This paper also put forward proposals of optimum design.This paper selected one of the typical microelectronic packaging devices, a DC-DC Power Converter, as the research model, and analyzed its overall temperature and stress and strain distribution combined with thermoelastic theory and viscoplastic theory by using finite element software. It has also analyzed inelastic strain behavior of solder joints under thermal cyclic loading conditions and predicted the fatigue life of the solder joints. Based on the classic form of thermal cycling load which widely used in solder joint thermal fatigue analysis and the actual transient thermal analysis, a improved form of thermal cyclic load was proposed. Compared two results obtained from the two loading form, it found that there is a large gap between the fatigue life preditions. Finally, using the improved form of thermal cyclic load, the enhance of solder joint’s fatigue life through using lead-free solder or underfill or lead-free solder combined with underfill was quantitative analyzed. The results showed that compared with the tin-lead solder without underfill, the use of lead-free solder can extend the thermal fatigue life of solder joint by 17.72 percent and the use of underfill can extend the thermal atigue life of solder joint by 31.83 percent. Integrated use of lead-free solder and underfill can significantly ehance the fatigue life, it reached 253.90 percent, much larger than the cumulative effects of using two methods alone.