A method for the accelerated simulation of micro-embossed topographies in thermoplastic polymers

Abstract

Users of hot micro-embossing often wish to simulate numerically the topographies produced by the process. We have previously demonstrated a fast simulation technique that encapsulates the embossed layer's viscoelastic properties using the response of its surface topography to a mechanical impulse applied at a single location. The simulated topography is the convolution of this impulse response with an iteratively found stamp–polymer contact-pressure distribution. Here, we show how the simulation speed can be radically increased by abstracting feature-rich embossing-stamp designs. The stamp is divided into a grid of regions, each characterized by feature shape, pitch and areal density. The simulation finds a contact-pressure distribution at the resolution of the grid, from which the completeness of pattern replication is predicted. For a 25 mm square device design containing microfluidic features down to 5 µm diameter, simulation can be completed within 10 s, as opposed to the 104 s expected if each stamp feature were represented individually. We verify the accuracy of our simulation procedure by comparison with embossing experiments. We also describe a way of abstracting designs at multiple levels of spatial resolution, further accelerating the simulation of patterns whose detail is contained in a small proportion of their area.