Design and Implementation of a Thin Film Tensile Testing Apparatus for Cryogenic Applications

Due to the temperature dependence of stress–strain response in polymers, it is essential to characterize these materials at cryogenic temperatures for use as dielectrics in superconducting electronics. To date, limited efforts have been carried out to explore the experimental devices and procedures required for mechanical testing of polymer thin films in a cryogenic environment. In this work, we develop a novel tensile testing apparatus for thin film samples in cryogenic temperature conditions. The system’s highly cost-effective design, simple manufacturing process, and ease of integration into conventional mechanical test equipment are discussed. Finite element (FE) analyses are utilized to show the effective operating range of the apparatus in terms of environmental chamber temperature and sample stiffness. Digital image correlation (DIC) is also used to show that frame deformation is minimal during testing, validating the finite element analyses. Polyimide tape samples are tested in tension at room temperature and in a liquid nitrogen (LN₂) cooled environment. Room temperature test results are compared to published data for verification. Results obtained herein demonstrate the accuracy and usability of this apparatus for mechanical characterization of thin films in cryogenic conditions. The experimental methodology presented in this work also has the potential to be extended to the characterization of thin films from other material classes for cryogenic applications.