Thermal and Thermomechanical Behaviors of the Fan-out Package with Embedded Ag Patterns

Fan-out wafer/panel level package (PLP) is an advanced package. Compared to the conventional package, its thickness is reduced, and electrical and thermal characteristics are improved, through the substitution of a substrate/interposer with a redistribution layer (RDL). However, its thermal and thermomechanical characteristics need to be improved and controlled more elaborately. In this article, six types of Ag patterns were embedded in the upper side of the fan-out package. Thermal emission was improved by building an efficient thermal conductive path, while warpage was improved by vertical symmetry and strain distribution. Overall, the large pattern in both fan-out and fan-in zones reduced the warpage and the pattern embedded in the fan-in zone efficiently improved the thermal emission. However, the pattern area should be designed by considering the overlapped areas with the through via interconnection or the embedded component in the fan-out zone. Because the embedded pattern with a large area is not necessarily a proper approach, an optimum pattern was studied with the simulation and measurement of the thermogram and warpage. The approach of the embedding pattern in the fan-out package is expected to improve its thermal and thermomechanical behaviors.