Reliability and Simulation of composite BGA solder joint connecting LTCC substrates

Due to the rapid development of the miniature microwave module, package-on-package (PoP) configuration is extensively used. The interconnection providing both signal and mechanical support is the significant area to investigate. This paper focuses on the relationship between the arrangement of solder joints and the reliability of vertical interconnection concatenating two low temperature co-fired ceramic (LTCC) substrates at the cooling stage of the reflow soldering. A thermal-mechanical model is established, while the technology of "Element Birth and Death" is applied for simulating the phase change of solders. It is found that the arrangement of solder joints matters in the temperature and thermal stress response of the microwave module. The results show that arranging some solder joints in the middle of substrates and distributing solder joints uniformly are benificial for the reliabilty of interconnection.