A membrane keypad is a thin, sealed assembly where a polycarbonate (Lexan) front face is bonded to a printed circuit beneath. Pressing the front face actuates a tactile dome that closes a switch on the underlying PCB. Lexan is the only material that delivers the optical clarity, mechanical flex and surface resistance this application demands.
📌 Layers of a Membrane Keypad
- Lexan front overlay: reverse-printed graphics, embossed tactile domes
- Spacer layer: die-cut, defines the gap above each dome
- Dome circuit: printed conductive contacts on flexible film
- Adhesive backing: 3M industrial double-sided
📌 Designing the Lexan Front
The Lexan overlay must include embossed tactile domes (typically 0.6–1.0 mm projection), transparent LED indicator windows, diffuser ink layers for backlight uniformity and reverse-printed graphics that survive thousands of actuation cycles. Thicknesses 0.125 mm to 0.25 mm are typical for membrane keypads.
📌 LED Backlight Compatibility
Lexan's optical clarity makes it the only practical choice for backlit keypads. Diffuser ink between LED and graphic homogenises hot spots; opaque blockout ink masks areas that should not glow.
📌 Bora Ajans Capability
We produce the Lexan overlay portion of membrane keypad assemblies — embossed domes, LED windows, reverse-printed graphics. Customers integrate our overlay with their dome circuit and backlight assembly, or we work with partner keypad makers for full assembly.