Precision 3-D metal microstructure array fabrication with direct-write electrodeposition
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One of the major challenges in 3-D manufacturing is to develop a parallel manufacturing process for fabricating precision metal microstructures. Its realization promises the development of high aspect-ratio metal microstructures that could provide microscale mechanical and electrical interfaces for applications in electronic testing and bio-sensing. In this research, the self-regulated growth mechanism in the meniscus-confined direct-write electrodeposition was exploited to realize the parallel process fabrication of high density area arrays of ultrahigh aspect-ratio solid metal microwire structures; micromachining processes were developed to produce precision nozzle arrays required for the high throughput parallel process fabrications; and the underlying physics that enabled this parallel manufacturing process were revealed and formulated to guide the development. A 3-D micro-printing process that integrated the concept of discretized 3-D printing manufacturing with meniscus-confined direct-write electrodeposition was also developed to enable the fabrication of ultrahigh-density and complex-structured 3-D micro/nano-scale metal structures. Further on, a parallel 3-D micro-printing process for metal was realized. Specifically, mesoscale high quality and high-density arrays of curvilinear Cu spirals with designed mechanical and dimensional characteristics were fabricated with the metal spirals having a wire diameter of 20 μm, a coil diameter less than 100 μm, a structural aspect-ratio of over 40 and a pitch of 50 μm. High quality metal springs and spring arraying having a wire diameter of only 1 μm, a coil diameter of only 5 μm and an aspect-ratio exceed 100 were also readily fabricated. More interestingly, the Cu spirals were found to acquire exceedingly high yield strength of over 800 MPa due to the nanocrystalline microscopic nature of the Cu wires. Targeted studies of the precision metal structures uniquely produced by such parallel manufacturing processes were carried out for applications especially in the field of microelectronics and biosensing.