Fabrication of metallic micromolds by laser and electro-discharge micromachining |
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Authors: | Pun-Pang Shiu George K Knopf Mile Ostojic |
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Affiliation: | (1) Department of Mechanical and Materials Engineering, The University of Western Ontario, London, ON, N6A 5B9, Canada;(2) Industrial Materials Institute, National Research Council Canada, London, ON, N6G 4X8, Canada; |
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Abstract: | A method of creating metallic micromolds with features that have high-aspect ratios is described in this paper. The proposed
manufacturing process utilizes laser micromachining to cut the negative two-dimensional profiles of the desired microfeatures
and fluidic network patterns on a 100 μm thick brass sheet. The positive relief of the cut pattern is then created by using
electro-discharge micromachining (micro-EDM) die-sinking the metallic mask onto a brass substrate. The final substrate with
the desired relief pattern becomes the molding tool used for either elastomer casting or thermoplastic hot embossing. To validate
the proposed fabrication methodology and evaluate the quality of surface finishes, a brass mold master of a T-channel micromixer
(50 μm width, 25 μm height) is developed and multiple replicated devices are cast on this mold using poly-di-methyl-siloxane
(PDMS). The surface finish of both the original micromold master and final molded channels on PDMS are measured using an optical
profiler and found to have a roughness of approximately 400 nm Ra. The ability of the proposed fabrication technique to create
high-aspect ratio features is illustrated by manufacturing a Y-channel micromixer with an aspect ratio of 4. Experimental
results are discussed and suggestions for improvement are presented. |
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