Polyester is used for circuit layers where its thermal stability, insulator properties, in high specification overlays, especially when embossing is required. It provides excellent chemical resistance and mechanical durability to enable it to withstand millions of cycles of switch operation without fatigue.

Polycarbonate is used exclusively for overlays. It also has excellent thermal stability and can be made chemically resistant through the use of sur UV hard-coatings. Polycarbonate is an excellent choice when high cycle life is not required.