Abstract: Hot embossing serves as an important technology for continuous production of polymer microcomponents, yet its heating stage still relies on conventional resistance or infrared heating, which struggle to balance heating rate and temperature uniformity. To address this limitation, this study proposes a novel microwave-assisted hot embossing (MHE) process for rapid polymer microfabrication, using microwave (MW) magnetrons as the sole power source. In MHE, two MW-absorbing microstructured molds and an MW-transparent insulating sleeve are first designed to achieve targeted and rapid heating of embossing parts, followed by precise servo-electric loading to replicate mold microstructures onto polymer surfaces. Using the typical thermoplastic polymer—polymethyl methacrylate (PMMA), MHE experiments of microring arrays are conducted under varied heating/loading conditions. The results indicate that: (i) MHE enables rapid heating of SiC molds to 200 ℃ at low power (600 W) within 8 s, and its average heating rate (25 ℃/s) is over five times faster than conventional heating (<5 ℃/s); the temperature difference between the upper and lower molds is down to 2.0 ℃, demonstrating the temperature uniformity comparable to conventional heating. (ii) Theaverage height of PMMA microrings increases with the increasing embossing temperature, embossing speed, and holding time, albeit with diminishing returns. (iii) Using the preferred processing parameters (embossing temperature 180 ℃, embossing speed 0.06 mm/s, holding time 250 s), the filling ratio of the microring replica reaches 98.39%, and regular hundred-micrometer-scale straight grooves and single-micrometer-scale conical arrays are successfully replicated onto PMMA surfaces. These results show that the proposed method can achieve rapid and uniform heating of polymer preforms, thus allowing for precise replication of multi-scale and muti-type surface structures, and offering a promising pathway for green and efficient manufacturing of microoptics and microfluidics components.

Key words: PMMA, microstructure array, microwave-assisted hot embossing, heating rate, filling ratio