Finite-Element Simulation And Solder Joint Life Predictions For Chip Scale Ball Grid Array Size Package

At present, BGA/CSP is becoming the mainstream of the advanced IC package technology. Its development is based upon the solution of the reliability of solder ball, which is one of the key problems. It is proved that thermal fatigue is the main cause of the invalidity of the package. Therefore, it is significant to research the reliability of solder ball under the thermal cycle. In this paper, BGA/CSP is simulated and analyzed as implemented in the ANSYS finite element simulation software tool to evaluate the affect on its reliability; the constitutive model of the solder ball is constructed tentatively to find a better description for the solder ball.First, the paper discusses briefly the IC package technology, the reliability analysis methodologies and the current situation of the IC package. Second, it eonstructs a typical BGA/CSP 3D model by programming the APDL code, then analyzes its life prediction. Third, it analyzes different influences upon the life predication by comparing different models of the same package, different constitutive models of the same solder ball's materials, different life prediction models, different solder ball dimensions, different mesh density etc. Finally, it compares some popular constitutive models of the solder ball materials, and constructs an integrated constitutive model by different curve fits.The paper makes a "second exploitation" of ANSYS for solving certain problems through FORTRAN and APDL programming in order to apply the ANSYS finite element simulation software tool more conveniently and effectively to the simulation analysis of the IC package.