Membrane switches are best explained by contrasting them against the other popular switch type. The two types are commonly used in electronic devices and throughout one’s home. Mechanical Switches are usually made from hard-plastic and copper, and they function by manually opening or closing a circuit connection. Membrane switches are far cheaper, and they are more commonly used in silicone keypads, as well as in other electronic devices that require a relatively durable solution to switching. Membrane switches, like their mechanical counterparts, can turn circuits on and off – but they are usually printed on PET or ITO with copper/silver ink that is conductive but also easy to mass-produce on a flat circuit board.
Construction of Membrane Switches
Image courtesy of AGE IncorporatedThe construction techniques that are used for membrane switches are actually relatively simple. Membrane switches are usually made in four different layers – with the top layer of the membrane switch made out of silicone for the best combination of flexibility and ease-of-cleaning. Silicone Dynamics makes tons of membrane switches every year. We work with product designers and manufacturers to help integrate silicone switches and custom membrane switches into any products.
Membrane Switch Backlighting
One of the best things about membrane switches is the ability for manufacturers to produce the switches in a multitude of different transparency levels and colors. For example, if you are producing a calculator or another electronic device that is designed to be used in low light levels, you can easily backlight those switches.
• LED Backlights – LEDs are basically tiny lamps. This makes them ideal for backlighting indicator lights or individual keys, but less suitable for backlighting large panels. The reason for this is that they create bright spots. On the other hand, LED lights are easy to produce, they consume very little energy, and they are “cool” lights that do not create excessive heat.
• Optical Fiber – Optical fiber is actually a woven cloth that is used to create a light diffusing array hooked up to an LED. This setup provides a more even lighting surface. Optical fiber is ideal for backlighting, and is extremely durable (and will even work underwater!)
• Electroluminescent Lamps – EL lamps are cheaper than optical fiber. They have been used successfully in many older electronic devices and cheaper consumer devices. The biggest downside of EL lamps is their relatively short life, as they can burn out after around 3000 hours of use. EL lamps are better for devices that are considered “disposable” like calculators and some cheaper consumer electronic devices.
Uses for Membrane Switches
Membrane switches are used in virtually every industry. They are ideal for electronic devices with thin flat panels. Microwaves are usually made with membrane switches because they can be easily cleaned, as are devices in hospitals and in laboratories where sterility is of primary concern. Many television remotes also use membrane switches. They have formed silicone buttons to change the tactile response of the remote control. The devices accomplish this by shaping the buttons and embedding metal snap domes or creating a different graphic layer.
Membrane switches are easy to clean, they are self-sealing and have a low profile when compared to mechanical switches. Silicone Dynamics can help you integrate silicone membrane switches into your own projects by creating custom silicone keypads to your exact specifications.