Development of Two-Tier FO-WLP AiPs for Automotive Radar Application

A Fan-out wafer level package (FO-WLP), Antenna in Package (AiP) test vehicle built for 77 GHz automotive radar was demonstrated in this paper. The AiP test vehicle is made up of three layers of Cu redistribution lines in a two-tier mold construction. The antenna arrays are manufactured on the top tier mold compound layer, while the MMIC device chips are implanted in the bottom tier mold compound layer. This two-tier mold structure was created to reduce the form factor of the AiP. A series of material evaluation was performed to select suitable material candidates for the FO-WLP AiP test vehicle fabrication. Mold compound and photo-dielectric were evaluated for their process-ability, reliability and electrical performance. Temporary bonding adhesive and carrier types were also evaluated for their bonding/de-bonding performance and warpage. AiP test vehicles were fabricated with the selected materials using the "mold-first" process flow and reliability test was performed on the fabricated samples.