A study on the application of electromagnetic-field-assisted magnetic soft mold photocuring imprinting technology in micro-structure gradient replication molding

Abstract

This study proposed a new imprinting process using electromagnetic-field- assisted imprinting technology, a composite PDMS magnetic soft mold, and UV-LED arrays photocuring equipment to change an even microlens mold by imprinting the replication into a gradient microlens structure. This function is similar to the continuous gray scale technology of the semi-conductor industry. However, the structural appearance, as defined by the gray scale photo mask process, is smoother and continuous. As the method only requires one time of imprinting, the process is simple, with lower cost and higher competitiveness, thus providing a more effective alternative for imprinting technology and applications. This study used pressure-sensitive film to explore the imprinting pressure distribution of gradient magnetic soft molding. The imprinting results showed that, magnetic powder is distributed in a linear tilting pattern that is consistent with pressure measurement distribution. Hence, the magnetic powder casting angle control of a precision tilt platform can achieve gradient control of imprinting pressure. Finally, the observations and analysis by instruments, including SEM, a surface profiler, and a Laser Scanning Confocal Microscope, confirmed that the gradient magnetic PDMS film made using a precision tilt platform to control the magnetic powder casting angle, coupled with electromagnetic-field-assisted imprinting and UV-LED arrays light curing technology, can replicate the gradient microlens arrays structure of the same tilt angle through one imprinting.