A Unique and Robust Technique to Eliminate Warpage for FOWLP and FOPLP During the Termal Debonding Process

Abstract

The paper revolves around a method to reduce warpage, which is one of the issues commonly encountered by OSATs offering Fan-out Wafer Level Package (FOWLP). Warpage introduced by handling during thermal debonding will be the focus of this presentation and will also cover the concept of warpage reduction after debonding. The warpage adjustment concept consists of subjecting the reconstituted wafer to a temperature that is equal or higher than its glass transition temperature (Tg) for specific dwell time. The wafer should then be placed on a cold thermal chuck, and a vacuum chuck should be used to lock the profile. Contactless transport method, which proved to play a significant impact on warpage reduction for wafer level and panel level fan-out (FOWLP and FOPLP), will also be covered. The paper gives details to the common issues encountered (i.e. warpage and die shift), the test methodology, results of the experimentation, as well as the challenges encountered when applying such methodology to panel level format.