Laser micropen integrated direct writing for fabrication of thick film gap-tuning capacitor

• Thick film gap-tuning capacitors are fabricated by a new method of laser micropen integrated direct writing.
• Gold and polyimide are used as the materials of structural and sacrificial layers, respectively.
• The maximum tuning range (MTR) of the gap-tuning capacitor is 30.35% with the practical pull-in voltage of 39 V.
• The process enables a practical route to a desktop fabrication system for electronic circuitry of RF MEMS.

With a fixed base-electrode and a movable upper-electrode structure, the electrostatic actuated parallel plate tuning capacitors have the advantages of no DC power consumption, high efficiency and easy to implement. We propose a novel approach of laser micropen integrated direct writing for fabrication of the thick film electrostatic-controlled gap-tuning capacitors. Adopting commercial gold paste (Au) as the material of structural electrodes and polyimide colloid as the material of sacrificial layer, the thick film gap-tuning capacitor arrays are successfully fabricated on the fused silica glass substrate. The electrical analysis shows that the maximum tuning range (MTR) of the thick film gap-tuning capacitor is 30.35% with the practical pull-in voltage of 39 V, and the Q value is 50 under the frequency of 1 GHz.