Reliability study for CTE mismatching in build-up structure

This paper describes the study for dependence of CTE mismatching in build-up structure on reliability. Eight-layer build-up structure was fabricated where four kinds of dielectrics having different CTE value were employed. Two via-chain groups were fabricated inside the substrate and three LSIs were assembled onto the boards. Thermal cycling tests were employed to evaluate reliability and cross-sectional observation was completed to determine the failure mode. Simulation activity was also done to predict thermomechanical behavior of the interconnects. Through the experimental activity, reliability of DSP was analyzed and good agreement of failure mode analysis by thermal cycling tests with finite element method predictive analysis was obtained. CTE mismatching clearly had an effect on the reliability and the smallest CTE value exhibited the highest reliability in the system.