A Cost-Effective Universal Wafer Level Packaging Platform for Ba Wand Thin-Film SAW Filters

This paper presents a universal wafer level packaging (WLP) platform for bulk acoustic wave (BAW) and thin-film surface acoustic wave (SAW) filters. Unlike conventional WLP methods that typically perform all processes on the cap wafer, including signal routing, the proposed method diverges by routing signals from the device wafer, effectively alleviating bonding concerns on the bonding material. This novel approach integrates a unique organic bonding material and the similarities between the two methods facilitate the unification of the supply chain, resulting in a cost-effective manufacturing process. This universal platform not only improves the reliability and performance of BAW and SAW filters but also offers flexibility in cap wafer selection, potentially reducing costs and enabling functional integration. The results demonstrate the efficacy of the proposed WLP methods, highlighting their potential in meeting the stringent demands of next-generation communication technologies.