How Thermal Mass Changes the Behavior of a PI Heater

https://precision-heater-hub.swiftnestly.com/posts/kapton-heater-applications-in-electronics-and-precision-equipment

In sensors, a pi heater must deliver heat in a controlled way. It uses a thin resistive foil circuit laminated in polyimide film. One useful trait is fast response. Still, local hot spots can change the result