An integrated approach is developed for optimum design and reliability assessment of sodler interconnections by taking into conideration sodler interconnection geometry, thermal and mechanical characteristics of component and printed circuit board materials, as well as application conditions. For a given design configuration and manufacturing process, sodler joint geometry is first predicted; then a macroanalysis is undertaken to sstimate the thermal mismatch; and the corresponding thermal strain and stress on solder joints are estimated by using elastic and creep analyses. Fatigue life is assessed base on an energy-based fatigue failure criterion. A numerical implementation into an integrated analysis tool is pursued in this investigation in such a way that for a given sodler joint design and service condition, it provides an efficient way to assess solder joint fatigue life; likewise, for a required service life, it then solves for the optimum solder geometry, and, if needed, points out a way to achieve the optimum tthermal matching by intelligent selection of component and substrate materials for any specific service condition.
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