A Process Planning Method for Thin Film Mask Projection Micro-Stereolithography

Abstract

In this study, a process planning method is presented for the Mask Projection Micro-Stereolithography process with the ability to cure a film of various thicknesses on flat or curved transparent substrates. In this process, incident radiation, patterned by a dynamic mask, passes through a transparent substrate to cure photopolymer resin layers that grow progressively from the substrate surface. When compared to existing Stereolithography techniques, this technique eliminates the necessity of recoating, reducing process time and improving accuracy. A regression model is adopted in this process plan to accurately control the curing front on the substrate. An existing Mask Projection Micro-Stereolithography process planning method is extended to account for radiation transmission through the substrate. The models are verified using experiments.

Modeling effects of oxygen inhibition in mask‐based stereolithography

“…The schematic of our film micro stereolithography (FMSL) system is shown in Figure 3. The specifications of the system can be found in Jariwala et al (2009). The design of the system can be divided into three modules.…”

“…1 which shows the schematic of the polymerization process studied in this paper. Based on experimental observations, this model was modified in [3,4] as follows: z…”

“…The cured part height, z is shown in Figure 1 which shows the schematic of the polymerization process studied in this paper. Based on experimental observations, this model was modified in Limaye and Rosen (2007) and Jariwala et al (2009) as follows: Equation 2 where D pL is the depth of penetration for liquid resin and D pS is the depth of penetration for a cured layer. The parameters E c , D pL and D pS are usually fit to experimental data at a specific resin composition and cure intensity.…”

A Review on Modeling Cure Kinetics and Mechanisms of Photopolymerization

“…ECPL is an additive manufacturing process in which UV curing radiation, controlled by a dynamic mask is projected through a transparent substrate onto the photopolymer resin to fabricate three-dimensional structures. Compared to similar techniques to model the ECPL process, for instance, published by Mizukami et al [ 163 ], Erdmann et al [ 164 ], and Jariwala et al [ 165 ], Wang et al [ 105 ] present a more accurate, experimentally validated model with revised photopolymerization rates. The authors used the capabilities of COMSOL software to model the photopolymerization reaction kinetics for a two-dimensional finite element (FE) model, predicting the cured part geometry based on certain process parameters.…”

“…To estimate the concentration of the individual species at a given time and location within the resin chamber (double bonds, live radicals, oxygen) the rate constants (for the propagation of a radical), (for termination between two radicals), (for termination of a radical with an oxygen molecule), and oxygen diffusion constant were modeled along with a diffusional model (chdi) in COMSOL. Compared to Jariwala et al [ 165 ], who estimated the rate constants , , and by fitting the simulation results with the experimental data from Fourier-Transform Infrared (FTIR) experiments, Wang et al [ 105 ] suggest, that the individual rate constants are not unique and may vary. Therefore, the authors provide revised values for , , and .…”