Different methods for the fabrication of UV-LIGA molds using SU-8 with tapered de-molding angles


De-molding is one of the most crucial steps for successful mass production of high aspect ratio microstructures in microreplication technologies of LIGA process. With a proper taper angle in mold structure, normal contact pressure on the structure will be abated; this will facilitate the de-molding procedure and at the same time prevent the microstructures of mold from being damaged. However, in the case of UV lithography, the top area of the patterned SU-8 resist is observed to be larger than the bottom area especially in cases of thick layer and high aspect ratio structures. In order to obtain an applicable metal mold for hot-embossing process, we purpose here several novel methods with backside exposure which can fabricate different taper angles with proper direction on the mold structures easily. In this paper, we described the technology concept, process details and related experimental results both in mold structures and molded PMMA replicas. In addition, various interesting 3D microstructures can be produced by combining these exposure methods. On-chip microneedle arrays were selected to demonstrate this ability.

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This research is supported partially by National Science Council Taiwan with a Grant of No. NSC 93-2212-E-007-058. In addition, the author would like to thank especially National Synchrotron Radiation Center in Taiwan (NSRRC) and Precision Instrument Development Center (PIDC) for their support in expensive facilities

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Correspondence to C. Fu.

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Fu, C., Huang, H. Different methods for the fabrication of UV-LIGA molds using SU-8 with tapered de-molding angles. Microsyst Technol 13, 293–298 (2007). https://doi.org/10.1007/s00542-006-0197-9

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  • Soda Lime Glass
  • Metal Mold
  • Microneedle Array
  • Transparent Substrate
  • Normal Contact Pressure