One of the most common questions asked when designing a membrane switch is: should I use polyester or polycarbonate material? There was a time when polycarbonate was the standard for membrane switches, but that has certainly changed over the years. Polyester has since become the industry standard and is what CSI recommends for the majority of our designs.
Circuit Layers: For the membrane switch circuit layers, polyester is always used as it works best with the higher temperatures that are required for conductive printing. Polyester can be heat stabilized so that it can withstand the any potential for shrinkage during processing.
Graphic Overlay: The choice between polyester and polycarbonate really appears when designing the graphic layer. Embossing the keys gives a better user experience and a nicer look, this is where polyester shines and many think this is the biggest advantage that it has over polycarbonate. Embossing will stress any material (polyester or polycarbonate), affecting it’s life, but polyester can handle this much better than polycarbonate. In fact, it is not recommended to emboss polycarbonate as it can lead to cracking, reduced life, and even failure.
Durability and Chemical & UV Resistance: Polyester also has a greater resistance to chemical and UV exposure. This is critical for any membrane switch that is used in an outdoor or other harsh environment.
Dielectric Resistance: Both polyester and polycarbonate have good dielectric resistance but polyester is typically slightly better.