Kapton RS Flexible Heaters – Design and Applications

DuPont
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Kapton
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RS is a two-layer polyimide film consisting of a $25\mu \mathrm {m}$ thick, 100 Ω/□ resistor layer on one side, and a $25\mu \mathrm {m}$ thick dielectric layer on the other side. This engineered, electrically resistive film is utilized to fabricate flexible heaters that are rated for up to 240 °C continuous operation. Flexible high performance heaters are fabricated by adhering positive and negative electrodes to the resistor side of the Kapton RS film. Electrode deposition on the resistor side of Kapton RS film is accomplished in two ways: (1) By screen printing a conductive paste. (2) By deposition of copper. Design and fabrication methods of Kapton RS heaters are described in this work. This work also presents the nuances of the electrode design for these heaters using 3D numerical modeling. This work discusses the optimization of the electrode design to minimize hotspots with the help of COMSOL numerical simulation. A comparison study of various heater technologies that include etched-foil heaters on a polyimide substrate, silicone wire-wound heaters, and Kapton RS heaters are described in this work. Heaters with similar power densities were selected and evaluated based on various criteria including voltage and current inputs as well as temperature outputs, time to thermal stability, temperature uniformity and heat up / cool down time. Other criteria that will be reported in this paper include weight, thickness, resistance and flexibility. Conclusions are drawn regarding the best use-cases for each of these heater technologies. A list of flexible heater applications that are being developed with Kapton RS film is given at the end.