Investigation on the reliability risk for high density Fan-Out packages

Fan-Out (FO) technologies are used for consumer electronic products generally due to the small and very thin features. Thinner packages are required by mobile industry and Fan-Out (FO) provides a good solution. Some risks would be found when the design transfer from of 2.5D Integrated Circuit (2.5D IC) or system in packages (SiPs) to the FO packages. This paper investigation on the reliability risk for High Density Fan-Out (HDFO) with thermal cycle test (TCT) and the test vehicle is open fail. The test vehicle is examined by curve tracer (I-V), 3D X-ray, Focus Ion Beam (FIB) and Scanning Electron Microscope (SEM) to find out the failure mode. The failure mode is trace broken at the Redistribution Layer (RDL). Follow up the failure mode be observed, we use the Finite element method analysis (FEMA) to do the further simulation. Root cause of the stress concentration was investigated in this study.