Predicting solder joint reliability for thermal, power, and bendcycle within 25 accuracy

摘要

Solder joint reliability has received a renewed interest since theinception of BGA and CSP type packages. While traditionally board levelreliability during thermal and power cycling is considered important formost applications, solder joint failures due to board bending have alsobecome a major reliability concern for portable applications. With thecurrent trend of cheaper, faster, and better electronic equipment, ithas become increasingly important to evaluate the package and systemperformance very early in the design cycle using simulation tools.Although a number of life prediction models for solder joint underthermal cycle conditions have been proposed in the literature, notenough work has been reported in extending these models to power andbend cycle simulations. The accuracy of life prediction tool has alsobecome critically important, as the designs need to be evaluated andimproved with high degree of confidence not through relative comparisonbut by providing absolute numbers. This paper describes in detail thelife prediction model for solder joints for thermal cycle conditions andits extension to power and bend, cycle conditions. The approach usesadvance finite element modeling and analysis techniques such asconstraint equations and sub-structuring and is based on mechanics ofdeformation. The model has been correlated with more than 60 data pointsand predicts life within 25% in most cases. The framework of modelingand prediction methodology described here is fully applicable fordeveloping life prediction models for Pb free solder also, once thedeformation mechanisms are identified