1 / 5
EN 
DE 
FR 
ES 
RU 
JA EN DE FR ES RU JA
The circuit of membrane switches can be flex and rigid. It depends on the customer end application and also related to the cost budget and other considerations. For example, life, resistance, connection type on main board etc. For the flex circuit membrane switches, there are two types: Silver printed PET circuit and copper etched FPC circuit. Their difference and advantages & disadvantages are listed below:
| Items | Silver Printed Circuit | Copper Etched FPC Circuit |
|---|---|---|
| Material | PET (Polyester) | Polyimide |
| Conductor | Printed silver | Copper |
| Contact Fingers | Silver and Carbon | Gold plated |
| Contact Buttons Pads | Silver | Gold plated |
| Life & Reliability | Normal | Good |
| Stability | Normal | Good |
| Resistance | Normal | Very low |
| Cost | Low | High |
| Lead Time | 12-15 working days | 12-15 working days |
| Pitch | 1.0mm, 1.27mm, 2.54mm | 0.5mm, 1.0mm, 1.27mm, 2.54mm |
Copper Flex FPC circuit membrane switch panels can be produced using polyester or polyimide (Kapton) as the base material, depending on your interface requirements. A very thin sheet of copper is laminated to the flexible film substrate then chemically etched away, leaving copper traces. The etching process is not environmentally friendly due to the chemicals used, and is also more expensive than screen printing the silver traces used in Silver Flex membrane switches. Copper Flex switches can be constructed as:
FPC Membrane switch panel with LEDs are still the most popular and economical method for keyboard backlighting. LEDs are most commonly used to backlight keys, icons and symbols. LEDs are also typically used as indicator lights. A combination of LEDs, Light Guide Film and proprietary tiantai backlighting methods can be designed to backlight the entire surface of a user interface.
Sometimes, the membrane switch size is small, but there are many buttons and LEDs, then by the single PET circuit layer couldn't place so many components, then can consider to use double sided FPC as the circuit layer. By the way, the FPC circuit cost is higher than PET circuit, but it also has its advantages, for example, the FPC is more stable, tough. Especially when should assemble many LEDs on the circuit, then use FPC, the quality and stability will be much better then PET circuit. Of course, this depends on customer's requirements and decisions. If the customer no requirements, then we suggest use FPC as circuit only when it couldn't fulfill customer's function by PET circuit.
