A computationally simple method for simulating the micro-embossing of thermoplastic layers

We demonstrate a highly computationally efficient approach to simulating the embossing of micrometer-scale, feature-rich patterns on to thermoplastic polymeric layers. The method employs a linear viscoelastic model for the embossed layer and computes the distribution of contact pressure between the polymeric layer and a rigid embossing stamp that is consistent with the progression of the polymer deformation. An approximation to the embossed topography of the polymeric layer is thereby generated as a function of the material being embossed, the stamp's design, and the embossing process's temperature, duration and applied load. For a stamp design described with an 800 × 800 matrix of topographical heights, simulation can be completed within 30–100 s using a personal computer with an Intel Pentium 4 processor and 2 GB RAM. Our method is sufficiently fast for it to be employed iteratively for designing a pattern to be embossed or for selecting processing parameters. The viscoelastic properties of three polymeric materials—polymethylmethacrylate, polycarbonate and Zeonor 1060R, a cyclic olefin polymer—have been experimentally calibrated. For a test pattern having features with diameters of 5 µm to 90 µm, simulated and experimental topographies agree with rms errors of less than 2 µm across all processing conditions tested, with absolute topographical heights ranging up to 30 µm