Choosing between Polycarbonate and Polyester overlay material for your next membrane switch or graphic overlay?
The graphic layer of the membrane switch should be aesthetically appealing and ensure a proper life for your environment.
Polycarbonate
The most common graphic material used in overlay applications is polycarbonate which is easy to print, die cut, and emboss. Polycarbonate has excellent optical clarity and color stability in light or white colors and can remain clear above 10 (0.010) mil; available in sizes up to 30 (0.060) mil and higher.
The disadvantage of polycarbonate is that it begins to show signs of wear and tear sooner than some of the alternate materials and if a hard coat is not applied the material will be susceptible to damage from a variety of chemicals and UV light. In most applications polycarbonate overlays will last a minimum of 100,000 cycles during life cycle testing.
Polyester
A more robust material, Polyester, has superior life cycle and chemical resistance properties. In life cycle testing, polyester shows no signs of wear at 1,000,000 cycles and is recommended for use with tactile metal domes or polydomes.
Known for superior physical and electrical properties, polyester is the most commonly used base material for circuitry. Because of its poorer dimensional stability and memory, the switch layer is preshrunk and the graphic layer needs to be specially embossed.
