Flip chip assembly of a 40-60 GHz GaAs microstrip amplifier

This paper describes the successful flip chip assembly of a broadband GaAs amplifier in microstrip design. The flip chip technology used was tbermo compression (TC) flip chip bonding of the MMICs to gold ball bumps bonded on the thin film patterned alumina carrier. Also, we report on the occurrence of parasitic parallel plate (PPL) modes in the assemblies and we propose and investigate a scheme to eliminate the modes which, to the best our knowledge, have not been reported on before. Finally we introduce our own flip chip transition equivalent circuit and we use this model in ADS to compare the simulated results with measurements. It is fair to say that the equivalent circuit models the flip chip transition well. This work was performed in the European MEDEA+ packaging project HIMICRO.