In this paper, a finite element model is developed, and experimentally validated, for predicting the force required to produce a compression seal between a polycarbonate sealing boss and a 25-μm thick elastoviscoplastic hemodialysis membrane. This work leverages previous efforts to determine the conditions for hermetic sealing in a microchannel hemodialyzer fabricated using hot-embossed polycarbonate microchannel laminae containing sealing boss features. Methods are developed for mechanically characterizing the thin elastoviscoplastic hemodialysis membrane. The experimental data for assessing the depth of penetration into the membrane as a function of force show an R2 value of 0.85 showing good repeatability. The average percent error was found to be −8.0% with a range between −21.9% and 4.4% error in the strain region of interest.