Comparison between Polyimide Thin Film Microstrip Line and CoZrNb/Polyimide Hybrid Thin Film Microstrip Line

We investigated a hybrid thin film microstrip line with a polyimide (1 μm)/CoZrNb (1 μm)/polyimide (1 μm) sandwich structure and a polyimide (3 μm) microstrip line on the basis of electromagnetic field analysis, and we evaluated their characteristics for the fabricated device. Results showed that the distributed inductance of the polyimide thin film microstrip line depends on the operating frequency, because of the frequency-dependent magnetic shielding of the bottom ground plane. In the case of a hybrid thin film microstrip line, the distributed inductance is nearly constant, hence the characteristic impedance also becomes constant in the wide-band frequency range.