LTCC-Based vertical VIA interconnects for RF MEMS packaging

This article reports on a low temperature cofired ceramic (LTCC)-based RF MEMS packaging and its electrical modeling using lumped elements and microstrip lines. An LTCC cap with vertical vias was flip-chip bonded with a glass substrate, where a coplanar waveguide (CPW) formed to measure the RF characteristics of packaging structure. We measured return loss (S₁₁) and insertion loss (S₂₁) of the fabricated packaging structure in a frequency range of 1 to 30 GHz. The parameters of two different equivalent circuits using lumped elements and physical microstrip lines were extracted from the measured results. The mean absolute errors (MAEs) were calculated to show the agreement between measured properties and electrical equivalent circuits. The calculated MAEs were 0.591 dB (S₁₁) and 0.146 dB (S₂₁) for lumped elements, and 0.926 dB (S₁₁) and 0.179 dB (S ₂₁) for microstrip lines, respectively.