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  • Technical guide to silicone rubber keypads
19. March 2025

Coating options for a silicone keypad

Silicone rubber keypads can be coated with different materials to enhance their performance and appearance. Two common coating types are:

  • PU Coating: This coating offers excellent abrasion resistance and durability, with a smooth finish that can range from matte to high gloss.
  • Silicone Coating: Silicone coatings have non-stick properties and are highly resistant to moisture and temperature variations.

 

The choice of coating depends on the desired mechanical properties, environmental resistance, and finish of the keypad.

Silicone rubber keypad with raised keys and good tactility for outdoor machinery. Silicone rubber is easy to mould to the shape your product needs.
Silicone rubber keypad with distinct shaped buttons for outdoor, rugged environments. Using rubber keypad material opens up endless possibilities for key design.

Shapes and 3D Design

One of the key advantages of silicone rubber keypads is the ability to create various shapes and 3D designs. The silicone overlay is made using a compression-molding technique, which allows for flexibility in shaping the material.

 

This opens up opportunities for:

  • Concave buttons
  • Distinct recesses around keys
  • Split lines between different areas
  • Multi-level designs
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Color options

There are three primary methods for adding color to silicone rubber keypads:

  • Co-molding: In this process, two or more different colored silicone rubbers are molded together. This method ensures high durability and long-lasting color.
  • Spray-painting: This technique allows for the addition of fine graphic details on specific parts of the keypad.
  • Silkscreen printing: While silkscreen printing is effective for adding color, it requires a flat surface for the ink application.

 

Additionally, silicone rubber's durability allows for laser engraving or laser etching, where the top color layer is selectively removed to reveal the underlying color or translucent material.

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Silicone rubber keypad for forlift trucks with LED status light. Backlight is essential for safe operation of a rubber keypad in dark environments.

Backlighting options

Backlighting adds both aesthetic appeal and functional benefits to silicone rubber keypads. The key options for backlighting include:

  • Status indicators: These are backlit windows or symbols that provide immediate feedback about the device's status or required actions.
  • Deadfront or ghost effect: In this design, the backlit symbols remain hidden until illuminated, providing a sleek, modern look.
  • Functional backlighting: This type of backlighting ensures key visibility in low-light conditions, improving usability.

Click layer technology

Tactile feedback is a crucial feature for many keypads, and silicone rubber keypads can achieve a tactile click in several ways:

  • Metal domes: Metal domes are the most common method for generating a tactile click. They come in various shapes and sizes, offering flexibility in design.
  • Tactile switches: These switches are often used together with a PCB (Printed Circuit Board) as the circuit layer, making them ideal for designs with limited space.
  • Silicone click: Silicone keys can be designed to snap when pressed, with a carbon pill for connectivity. This solution reduces the number of layers required, making it more sustainable.
Design guide and more insights in tactile feedback
Membrane switch with metal domes
FPC - flexible printed circuit - copper-based electrically conductive foil for industrial keypads

Electric layer materials

The electric layer in a silicone rubber keypad is typically made from one of the following materials, each offering distinct benefits:

  • PET - PET is a cost-effective and widely available material, making it the most common choice for electric layers.
  • FPC - FPC uses copper-based foil for excellent conductivity and flexibility, making it ideal for applications that require bending.
  • PCB - a rigid option, PCB is best for applications that need soldering and offer stability for complex circuits.

 

Selecting the ideal circuit layer material for your keypad is determined by the product's intended use environment, along with its electrical and mechanical design requirements.

Integration considerations

For mechanical and electrical integration of a silicone rubber keypad consider the following:

  • Attachment method: How will the silicone keypad be secured to the device? Options include adhesives, screws, or press-fit techniques.
  • Mounting orientation: Where will the keypad be installed (front, back, or side of the device)?
  • Connecting tail length: Determine the distance between the keypad and the PCB. Will the connecting tail need to bend or twist?
  • Connection durability: Consider whether the electrical connection will be subjected to vibrations or tension during use.
  • Serviceability: Will the keypad need to be removable for maintenance or servicing?

 

Electrical tail for industrial keypad - connection between keypad and PCB

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