Failure Mechanism Study for Flip Chip QFN Crack Issue under Temperature Cycling Test

In this work, finite element analysis and failure analysis are performed to analyze the crack failure in flip chip quad flat no-lead (Flip Chip QFN). Although a QFN is a traditional package, the reliability requirements of Flip Chip QFN in power applications have become strict and more and more challenging to meet. This paper elaborates the thermomechanical reliability challenges of Flip Chip QFN associated with its unique package construction features, and investigate the failure mechanisms of package cracking issue found in thermal cycling test. Parametric analysis is conducted to determine the optimal design in the Flip Chip QFN to combat crack failure. This investigation can help improve the product reliability by preventing crack failures in the Flip Chip QFN package.