Fabrication of nickel micro gears by microelectroforming using PDMS molds

Abstract

Nickel micro gears of a diameter of 3.60 mm and a thickness of 0.18 mm are prepared by soft lithography and microelectroforming. Two different molds are used; one is composed of a polydimethylsiloxane (PDMS) mold which is adhered onto a graphite substrate, the other one is a PDMS mold coated with Au. The PDMS molds are firstly replicated from a micro gear master by soft lithography. Then the nickel micro gears are microelectroformed in the molds in a Watt’s solution. The structural integrity, growth of layers and phase compositions of the nickel micro gears are investigated by scanning electron microscope and X-ray diffraction. The results show that micro gears of high integrity can be fabricated by using the Au-coated PDMS mold. Compared with the high quality micro gear deposited layer by layer in the Au-coated PDMS mold, cracks are easily formed in the micro gear which is epitaxially grown in the mold that consists of the PDMS mold and the graphite substrate. The micro gears have similar grain sizes, howerver, the micro gear prepared in the Au-coated PDMS mold has smaller residual stress.