Have you ever wondered how momentary contact buttons and switches work on modern electronic devices? These things don’t work like the switch you flip to turn the light on in your bedroom or the one you push or twist to turn on a lamp. Components like membrane switches and membrane switch spacers have different materials. Let’s look a little closer at the world of switches to see how they operate.
Standard Wall Switches
A wall switch uses copper conductors to make or break a circuit. For example, you need black (hot) and white (neutral) wires to complete a 120-volt circuit. A typical single pole switch is wired in series with the black (hot) conductor). When the switch is “on” current can flow from the electrical source to the ceiling light. Once you flip the switch to the “off” position, it breaks the contacts, and the light no longer has any power, so the room goes dark.
Membrane Switches
To see an example of membrane switches, look at the control panel for most microwave ovens. You’ll see a number pad and several other selections. This panel has several layers, and the outside layer (with the push buttons) is the graphic layer. It may also have a top switch and bottom switch layer, and they are separated by membrane switch spacers. Each spacer insulates a circuit from other circuits and electronic connections.
When you push a specific button the thin membrane contacts a printed circuit in one area. Once you release the pressure, the contact stops. For example, if you press the “baked potato” button, the oven will operate on high heat for about 6 minutes. However, without the membrane switch spacers, the panel could not work because the circuits could short together. The spacers also work as effective heat seals to prevent damage from heat.
