Discrete Microparts Production Using Through-Thickness Hot Embossing and Rubber-Assisted Ejection

The hot embossing process has so far been mainly developed for replication of surface structures on thermoplastic substrates. Because of the lack of a through-thickness action, fabrication of discrete microparts such as microgears is considered difficult. In this study, an embossing mold having 13 microcavities was used in a through-thickness embossing process with a rubber-assisted ejection mechanism. Microparts made of HDPE and ABS with each part weighing approximately 0.9 and 1.4 mg, respectively, were produced. When in the mold, embossed microparts were intermittently connected to each other through thin residual films of a thickness approximately 20–30 μm on one surface. The residual films were detached from the microparts during ejection. Because no resin delivery path, e.g., runner and gate, is needed for microcavities on the mold, this micropart fabrication process could replace micro injection molding in numerous applications.