Optimization of laser release layer, glass carrier, and organic build-up layer to enable RDL-first fan-out wafer-level packaging

Abstract With increasing demand for mobile devices to be lighter and thinner and consume less power while operating at high speed and high bandwidth, many equipment suppliers and assembly participants have invested great efforts to achieve fine-line fan-out wafer-level packaging (FOWLP). However, the inherent warp of reconstituted wafers, which can contribute to poor die placement accuracy and/or delamination at the interface of the build-up layer and carrier, remains a major challenge. In this study, the interactions among laser release layer, glass carrier, and build-up layer were evaluated for optimization of redistribution layer (RDL)–first FOWLP as a foundation to move toward fine-line FOWLP. In this study, a series of experiments incorporating glass carrier, laser release layer, and build-up layers were carried out to determine the optimal setup for RDL-first FOWLP. First, glass carriers (300 mm × 300 mm × 0.7 mm) with coefficients of thermal expansion of 3 and 8 ppm/°C were treated with 150-nm lase...