This paper presents a bulk micro-machining process to fabricate micro-constrained layer treatments (MCLT) on a microstructure to increase its damping. MCLT consists of a silicon base beam or plate, a viscoelastic photoresist layer, and an aluminum constraining layer. Silicon base beams and plates are fabricated from {100} wafer through EDP etch and BOE etch. A 4.5-μm thick photoresist AZ4620 is deposited on the silicon base beam as the viscoelastic layer. Finally, an aluminum layer is deposited through LPVD as the constraining layer. To evaluate damping performance of MCLT, silicon beams with and without MCLT are subjected to swept-sine excitations by PZT from 0 to 100 kHz. In addition, laser Doppler vibrometer and spectrum analyzer were used to measure frequency response functions (FRF) of the specimen. A finite element analysis identifies the resonance modes measured in FRF. Experimental results confirm that MCLT can increase damping of silicon beams by at least 40%. Significantly larger damping improvement is expected, when the fabrication process is refined.

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