Suppression of leakage and crosstalk in typical millimeter-wave flip-chip packages

Leakage phenomena of flip-chip structures on common GaAs and alumina main substrates are characterized using the spectral domain approach to reduce the possible chip-to-chip crosstalk and transmission resonance. We have found that the longitudinal section magnetic mode is dominant for the coplanar waveguide leakage and the leakage can be suppressed by properly managing the gap height and the main substrate thickness in addition to the dielectric constant.