Surface Contact and Bonding Tips for Polyimide Heater
https://thermal-engineer.talesignal.com/posts/temperature-control-for-a-mica-heating-plate-sensors-setpoints-and-stability
Many heating problems look like a power problem at first. In practice, the cause may be contact, heat loss, sensor position, or poor fit. A polyimide heater works best when these parts are planned together