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Upgrade your input and swap membrane keys for PCAP

By Stefano Rosato | 24 May 2023
We are frequently asked if we can replace old membrane keypads with a new PCAP design. It makes sense, as the membrane design can present many problems – particularly as it ages. Simply put, membrane keys are less durable and their PET foil, which controls responsiveness, can and will break with frequent use.

Take a look at the membrane key design below to see the enormous potential for malfunction. Here we have some mechanical keys, which are protected by a membrane and backlit from beneath. It comprises a huge number of layers.

Keypad
Keypad graphic

Not only do these layers suffer from wear and tear, but just cleaning the keys can introduce liquids onto the PET foil and cause permanent damage to the internal electronics.

Keypad layers

To prevent this from happening, we can replace the entire stack with just three layers:

  • Cover glass with haptic buttons
  • A printed circuit board (PCB) for capacitive keys
  • A backlight

The thickness of this new stack is a 100% mechanical fit and equal in size to the original membrane key stack. It has no issue with liquids (it won’t even register a ghost touch from them) and will suffer no mechanical stress.

Keypad Schematic 1
New cover glass, front and side view
Keypad Schematic 2
No electronic adaptations are required

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10 September 2024

From an electrical point of view, our uC solution generates exactly the same signals as mechanical keys, so our customers don’t even have to worry about any adaptations to their electronics either.

About Author

 Stefano Rosato - Director, Technical Touch Technology at Avnet

Stefano Rosato is director of technical touch technology in the Display Solutions team at Avnet. Stefano helps customers solve touch challenges and supports customers through the whole design-in phase for touchscreen integration. With deep knowledge about PCAP technology, along with its design-in rules, tuning and pattern designs, Stefano is a leading expert in the touchscreen industry.Read More

Our Avnet Displays come in a range of form-factors and our display-experts are on hand to guide you in the creation of display or touch solutions that meet your requirements. Find out how Avnet Displays can propel your product innovation and get in touch today.