Packaging of RF MEMS Switches in LTCC

摘要

Currently one of the main limitations for the commercialisation of RF MEMS components is packaging. This paper will present the results related to the packaging of bare RF MEMS switch dies in an LTCC substrate. A so-called multi-user run was utilised and in this way it was possible to share the manufacturing costs between the designers. The basis LTCC substrate consisted of 8 Ferro A6-S tape layers, each being 99 μm thick after firing. This substrate contained both coplanar waveguide and microstrip transmission lines. In addition to this, additional tape layers were co-fired to form housing for MEMS components. These LTCC substrates contained chips which require either flip-chip or wire-bonding assembly methods. The length of bonding wires and the size of the cavity were minimised in order to reduce inductive parasitics. The electrical properties, i.e. S-parameters, of MEMS components were measured before and after the assembly to verify the effects of the LTCC package. The insertion loss of the bare MEMS component was 0.3 dB at 20 GHz whereas it was 0.8 dB for the packaged MEMS. The effect of the package in flip-chipped MEMS components was found to be small up to about 50 GHz.