In a nutshell, silicone keypads act as a mask that’s placed over switches to provide a comfortable, tactile surface for users. There are many varieties of silicon keypads, some with highly advanced features. The silicone compression molding process itself is quite complex, with a couple of main ways to do it: compression molding and liquid silicone injection molding (LIM).
A Look at Compression Molding
Silicone keypads are commonly created by compression molding, which uses a blend of pressure and temperature to create a durable yet pliable surface around many central electronic contacts. Silicone keypads are desirable because they offer a uniform tactile response across the surface.
The goal is to manufacture the entire keypad in just one piece of silicone webbing, instead of producing individual keys separately. Let’s take a TV remote control for instance. Silicone keypads offer lower costs and greater ease of production because the keypad is able to be inserted under the plastic holding device as a single piece.
The resistance of the device to fluids and surrounding environmental damage is increased, such as in the case of spills. Spilling a drink on a silicone keypad that is comprised of one big piece means you can easily wipe down the device without the liquid getting into the inner workings.
Compression molding is a simple, basic form of silicone rubber keypad molding.
The Mechanics of Rubber Keypads
Most silicone rubber keypads feature a similar construction, with the switch button located on top, with a button underneath acting as a conductive contact. This is usually made of carbon or gold. Underneath the conductive contact, you’ll find the PCB contact separated with air, and the silicone rubber webbing between the button and PCB contact. This basically forms a bubble around the exterior.
When you depress a button on a silicone rubber keypad, this action forces the webbing material to become deformed, making the switch’s conductive contact touch the PCB contact. The keypad then registers this action as being a button press, and the desired outcome is achieved. In the case of the remote control example, a channel may be changed or the volume adjusted.
Silicone Rubber: It’s Ideal For Molding
There’s a reason why silicone rubber is used often for keypads, and that’s because it boasts a low viscosity and can flow into a hot mold with little fuss – even at low pressures.
Silicone rubber has the ability to completely fill the mold no matter what the material, from steel to aluminum. The result is a product with a cleaner, matte-type finish, or a shiny finish if you so choose.
Contact Si-Tech
We love working with silicone rubber for our keypads, and we’d be happy to explain more about why. To ask questions or to get a quote on a project, contact us today at 757-887-8488.
