Temperature Cycling Failure Analysis and Improvement of A Panel Level Fan-out QFN Package

This article analyzed the temperature cycling test failure root cause and molding film crack mechanism of a panel level fan-out QFN package. Improvement actions are proposed according to Kitagawa-Takahashi diagram. In the micro crack stage, reducing the thermal stress is the key point. As the crack dimension grows to the macro crack propagation stage, crack propagation threshold and SIF must be well balanced. In addition, the maximum non-propagation crack length is also a key factor to optimize the crack issue. These factors are strongly related to material properties such as CTE and Young’s modules. Detail improvement actions are advised by finite element analysis method and verified through experiments. The optimized products have passed TC1000 cycles reliability test with crack free.