Development of 3-D Wafer Level Packaging for SAW Filters Using Non-photosensitive dry Film Capping

The advent of 5G necessitates advanced packaging technologies compared to traditional RF packaging, prompting 3-D wafer level packaging (3-D WLP) to progress towards smaller sizes, improved electrical performance, and reduced costs. A non-photosensitive dry film (SIF03) with high strength and high modules of elasticity was utilized as capping layer, which exhibits excellent pressure capability. Finite element modeling (FEM) simulation was employed to evaluate the reliability of package structure, we compared the performance of this film with others, the deformation of roof films on different substrates, and the deformation of roof films with different cavity wall layer thicknesses during reflow process and molding test. At the same time, the packaging scheme has passed the process verification, which has been successfully applied in the SAW filter package.