Recent developments in hot embossing – a review

Generation of micron-scale structures on a substrate is an emerging area in the manufacturing sector owing to its application in different fields such as micro-lenses, micro-needles, micro-reactors, micro-pumps, etc. Specifically, a patterned polymer is a much-desired product having applications in optics, hydrophobicity, micro-fluidic chip, etc. Such structures can be fabricated through photolithography, micro-milling, laser ablation, etc. But these processes involve a large number of steps, which makes them time-consuming and prone to error. Also, some fabrication routes are not suitable for generating patterns on a polymer substrate. In hot embossing (HE), structures from a patterned mold are transferred on to a polymer substrate by application of an optimum amount of temperature and pressure. It has problems like a long cycle and non-uniform pressure distribution during the embossing stage. To overcome these problems, different variants such as gas-pressurized hot embossing, ultrasonic hot embossing, reel to reel hot embossing, inductive hot embossing, laser-assisted hot embossing, far infrared assisted hot embossing, etc. have been developed. This article aims to review state of the art in hot embossing setup development and to point out the scope for further work and the direction in which the research on hot embossing can progress in the future.