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Silicone Rubber Keypads are manufactured from elastic, nontoxic silicone rubber compounds and are processed from compression or injection moulding. The result is an economical and reliable keypad for small, medium and large production runs. Silicone keypads can be integrated with printed circuit boards or flexible circuits and have excellent resistance to temperature and aging.

The natural colour of raw silicone rubber material is translucent white. Raw materials are blended with silicone-based colour pigments to obtain the colour required. Phosphorescent materials can be blended with the base rubber to create a “glow-in-the-dark” effect.

Durometer is one of several ways to indicate the hardness of a material. It defines the material’s resistance to permanent indentation. It is named for instrument maker Albert F. Shore, who developed a measurement device called a durometer in the 1920’s. The term durometer is often used to refer to the measurement, as well as the instrument itself. Durometer is typically used as a measure of hardness in polymers, elastomers and rubbers.                  (Source: Wikipedia)

Suggested hardness for silicone rubber keypads is 40 to 60 ‘Shore A’ depending on your requirements for actuation force, tactile response and life. Higher hardness rubber keypads offer higher actuation force and snap ratio but shorter life. Lower hardness rubber keypads have lower actuation force and snap ratio but longer life.

Silicon Rubber Keypads

COMPARISON OF ‘SHORE A’ DUROMETERS

Silkscreen printing

Graphics can be applied directly to the keytops of the rubber keypad by screen printing. Multiple colours may be printed, with each colour requiring an additional process. The optimum keytop for printing is a flat keytop. However, some curved keytops can also be printed.

 

Laser etch

A laser is used to etch graphics on the keytops to expose either an underlying layer of paint or the raw rubber. When backlit, light will pass through the translucent rubber and be visible in the etched areas.

 

Two-shot moulding

A keypad can be produced using one colour of rubber for the key top and a separate colour for the base.

 

Flow moulding

This process allows specific areas of a keypad to be moulded with different coloured rubber. This provides different base colours without requiring complicated spray-paint techniques. Silk screening is typically done on top of these base colours to provide additional graphics.

 

Key caps

Pre-moulded hard plastic keytops can be applied to the moulded rubber keypad. This provides a hard key feel with the economies and efficiencies of a rubber keypad.

 

PU coating

Silicone rubber keypads can also be spray-coated with PU resin to provide absolute lifetime abrasion resistance and oil resistance.  

 

Hard coating

A screen-printing or spray-painting process is used to apply an additional protective clear silicone ink on the keytops. This increases the abrasion resistance of the printed graphics.

 

Epoxy coating

Silicone rubber keypads can be coated with a layer of epoxy resin to form a hard top and feel like plastic. The epoxy coating also provides additional abrasion resistance for the printed graphics.

ABS Plastic Keypad