采用PDMS芯模微电铸成形镍微齿轮

Fabrication of nickel micro gears by microelectroforming using PDMS molds

以Φ3.60 mm×0.18 mm的微齿轮作为模板,先用软刻蚀技术制备聚二甲基硅氧烷(PDMS)弹性模具,通过将PDMS模具黏附在石墨基片上与在PDMS模具表面喷金制备成两种不同的芯模,再采用微电铸技术成形镍微齿轮.通过对在两种不同芯模上制备的镍微齿轮的结构完整性、铸层的生长方式和物相组成进行对比,分析芯模对微电铸成形的影响.结果表明:表面喷金的PDMS芯模可以精确复制微齿轮模板的微结构.相比于在喷金的PDMS芯模上微齿轮的逐层生长,在石墨基片上微齿轮是以外延的方式生长,在微齿轮中易产生裂纹等缺陷.两种芯模上制备的镍微齿轮晶粒尺寸基本相同,但相比于将PDMS模具黏附在石墨基片上制成的芯模,在喷金的PDMS芯模上成形的镍微齿轮(200)晶面择优取向增强,(111)晶面择优取向减弱,且残余应力更小.

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.