Innovation ultra thin packaging for RF-MEMS devices

In this paper, we report a novel RF-MEMS packaging technology with lightweight, small size, and short electric path length. To achieve this goal, we used the ultra thin silicon substrate as a packaging substrate. The via holes for vertical feed-through were fabricated on the thin silicon wafer by wet chemical processing. Then, via holes were filled and micro-bumps were fabricated by electroplating. To make up hermetic sealing, metal bonding (Au/Sn-Au) was used in the sealing line. Bonding strength after dipping in the water was about 60Mpa and there was no change. The packaged RF device has a reflection loss under -19 [dB] and a insertion loss of -0.54/spl sim/-0.67 [dB]. These measurements show that we could package the RF device without loss and interference by using the vertical feed-through. Specially, with the ultra thin silicon wafer we can realize of a device package that has low-cost, lightweight and small size. Also, we can extend a 3-D packaging structure by stacking assembled thin packages.