Solder resist structure for embedded die packaging of power semiconductor devices

Abstract

Embedded die packaging for high voltage, high temperature operation of power semiconductor devices is disclosed, wherein a power semiconductor die is embedded in package body comprising dielectric layers and electrically conductive layers, and where an external dielectric coating, such as a solder resist coating is provided on one or both external sides of the package body. The solder resist coating is patterned to avoid inside corners, e.g. the solder resist does not extend around or between electrical contact areas and thermal pads. It is observed that in conventional solder resist coatings, during thermal cycling, cracks tend to initiate at high stress points, such as at sharp inside corners. A solder resist layout which omits inside corners, and comprises outside corners only, is demonstrated to provide significantly improved resistance to initiation and propagation of cracks. Where inside corners are unavoidable, they are appropriately radiused to reduce stress.