On-wafer packaging is a premium concern when considering RF-MEMS. Being a mechanical switch, it is very susceptible to handling forces and process steps like wafer dicing, would destroy a MEMS-switch. It is therefore imperative to package the MEMS-switch on wafer. For this, a special packaging method using BCB-caps (BenzoCycloButene) has been developed. The result is shown below. The transparent BCB caps have a height of about 25 µm. Their wall has a thickness of approximately 100 µm. The 100 µm-wide BCB sealing ring (footprint on the chip) is completely bonded to the GaAs-wafer surface.
Besides 0-level packaging, packaging on sub-module and module level has also been investigated within the project. Several modules were realized using LTCC (Low Temperature Co-Firing) technology of VTT for RF-MEMS MMIC packaging. The next figure shows one of such packages. Measured results of these modules using three different LTCC sealing ring widths indicate a loss less than 0.5 dB up to 60 GHz.