Flexible Bandpass Filter Fabricated on Polyimide Substrate by Surface Modification and In Situ Self-Metallization Technique

Polymer, especially polyimide (PI), is the best suitable substrate material for the design of flexible electronics. The compact silver can be reduced on the surface of PI films by surface modification and in situ self-metallization technique. The formed silver layers have good electrical and mechanical flexibility. A flexible bandpass filter on a PI flexible substrate by surface modification and in situ self-metallization technique at room temperature are presented in this work. Measured results show that the proposed flexible bandpass filter could achieve a fractional bandwidth of 80.8% with an insertion loss (IL) of less than 0.6 dB. The performance of the designed filter is almost constant under different bending, folding, and rolling conditions. The formed silver layers also present good adhesion with PI substrates. This technology provides an alternative approach for manufacturing flexible filters without high-temperature thermal annealing, costly equipment, and vacuum conditions.Keywords:flexible electronics;polyimide substrate;bandpass filter;surface modification;in situ self-metallization