Carbon pill silicone buttons are one kinds of conductive silicone keypads. Carbon pill switch buttons are more durable than condcutive ink printing keypads. Conductve carbon pills are made from rubebr infused with graphite (carbon). When pressing the silicone rubber buttons, the carbon pills push again the circuit board to forming the electric current.
What is Conductive Carbon Pills?
Carbon Pills & Graphite Pads are widely used in silicone rubber keypad due to its economy and low resistance. Conductive carbon pills is made by adding carbon to macromolecule elastomer (such as silicone) to reduce its volume resistance. The resistance depends on carbon particle properties and filling quantity. The samller the carbon particle, the lower resistance the conductive carbon pills. Carbon pills are widely used in carbon pill button, carbon pill switch and conductive keypad.
Carbon pills are made by die-cutting tools or compression molding. There are two kinds carbon pills, textured finish pills and smooth finish carbon pills. Silicone rubber keypad manufacturers usually adopt four conduction ways to make the rubber keypad according to the keypad resistance requirements and application. They are conductive ink, carbon pills, metal dome and golden pills.
Carbon Pills Silicone Buttons Manufacturing Process
Different from conductive ink keypad which is prnted with conductive ink after compression molding, carbon pill silicone keypads are combined with the carbon pills during the compression molding. Before compression molding, the carbon pills are placed into the mold cavities by positioning tool. So the carbon pills will be combined with the silicone while the vulcanization. The time of vulcanization and the mold temperature will affect the combination of carbon pills with silicone button pad. Low temperature will cause th falling of the carbon pills, while high temperature will cause the melting of carbon pills into the silicone.
The Advantages of Carbon Pill Silicone Keypad
1. More durable than conductive ink keypad
Compared with carbon conductive paint keypad, carbon pill switch button are more durable as it can not be erased with long-term usage. The electric resistance of conductive ink button will increase after the long-time usage, but the resistance of carbon pill switch is stable.
2. Save more cost
The metal domes keypad or golden pill keypad button are rather expensive. For silicone rubber keypad manufacturing, conductive carbon pills are enough to meet keypad resistance requirements. The price of carbon pills is cheaper than than the metal pills.
The Disadvantages of Carbon Pill Switch Button
1. Carbon pills buttons can not be reworked once molded
Unlike conductive ink keypad, it is infeasible to rework carbon pill button keypad if the carbon pills falling off from the silicone keypad.
2. Limited shapes of the carbon pills
The regular shape of carbon pills in market is only round. If the irregular shapes are needed, such as trianle carbon pills, it need to customize. So the custom made carbon pills are expensive. Moreover, the production efficency is lower than conductive ink priting buttons, because the carbon pill need to be gripped by the position tool and then put them into the mold cavities, which will take more time and labor source.
Different Types of Silicone Keypads
Silk screen printing keypad Laser engraved illuminated backlit silicone keypad
Epoxy coating silicone rubber buttons PU coating silicone rubber button pad
Oil coating conductive silicone switch buttons Rubber keypad buttons with plastic caps
Conductive ink prting silicon keypad Conductive Gold Pills Silicone Keypad
Silicone Rubber Keypad Manufacturing Process Machines