Wide-band characterization of average power handling capabilities of some microstrip interconnects on polyimide and polyimide/GaAs substrates

Based on some derived closed-form equations for determining the wide-band frequency-dependent ohmic attenuation constant, loss tangent, and equivalent permittivity, the average power handling capabilities (APHC) are accurately characterized for some thin-film microstrip interconnects (TFMIs) on a single-layer polyimide and a microstrip on a double-layer polyimide and GaAs substrates, respectively. The accuracy problem arising from some closed-form equations for calculating the ohmic attenuation constant is highlighted, and the temperature-dependent property of thermal conductivity needs to be considered in calculating the temperature rise in some substrates, such as GaAs, etc. Possible ways to efficiently predict and improve the APHC are suggested, which could be useful when applying the microstrip interconnects in a high-power operating environment.