Repairing the membrane keypad or rebuilding the membrane keypad

Repairing a membrane keypad is usually not possible, so rebuilding it is usually the last option. In this article we explain how a membrane keypad is constructed and why it is easier to rebuild it than to repair it. There are several reasons why a membrane keypad can be damaged or defective. For example, liquids or dirt can get between the foils. Oxidation of the contacts and contact surfaces is also a common problem.

Structure of a membrane keypad

A membrane keyboard consists of several layers that are firmly glued together. The bonded layers cannot be separated without damage, so it is usually not possible to repair a membrane keypad. The keyboard itself is also firmly glued to the device, which makes it difficult to remove the membrane keyboard without damaging it. The picture shows a schematic side view of a membrane keyboard. Below you will find a brief explanation of the layers.

Top layer of the keyboard

The top layer of the membrane keypad consists of a printed, abrasion-resistant plastic film with an adhesive surface on the back. The adhesive is cut out on the key surfaces so that the foil does not stick to the actual key. Optionally, the foil can be embossed on the keys, which makes the key visually stand out from the rest of the foil and is tactile.

Spacer layer

This layer is optional and is usually a clear plastic film. This is used to provide more space for the snap-on discs (also known as the Knackfrosch ) or to provide the rubber buttons. If the buttons are embossed in the front foil, this layer is usually not necessary.

Electronic layer

The second layer is the actual electronics of the keyboard and consists of a printed circuit board or conductor foil. Depending on the design of the membrane keypad, the layer consists of a conductor foil with click frogs or a conductive rubber button, or of two glued conductor foils that are pressed together by the keystroke. This layer is then glued to the device via adhesive. The electronic layer is connected to the actual device either with a plug or with an extended foil board (flex board).

Rebuilding instead of repairing a membrane keypad

Unfortunately, it is not always possible to repair membrane keyboards, so rebuilding is often the last option for repairing old machines without spare parts. For simple membrane keyboards, the development costs of the first piece are between 500€ and 1000€, depending on the effort. The production of further pieces is then much cheaper. Therefore, reproduction is usually only worthwhile for large machines or if more than one membrane keyboard is needed. Send us pictures, dimensions and the required pieces of the membrane keyboard by e-mail or contact form, and we will prepare a non-binding cost estimate.

Develop New Membrane Keyboard

We have the necessary know-how and technical skills to develop membrane keyboards according to specific requirements. We use only high-quality materials and ensure that the new keyboard functions reliably and is durable. Our bespoke membrane keyboards are perfect for businesses that have specific requirements or need certain features. We work closely with our customers to develop a membrane keyboard that meets their needs and expectations. Please feel free to contact us for more information. For more detailed information about the development itself, you can read our article Hardware development View.

Examples of replicated membrane keypads

In the meantime, we have already rebuilt several membrane keyboards. In the illustration you will find two foils and four replacement boards for repairing or replacing membrane keyboards. The PCBs are made as FR4 PCBs or as Flex PCBs, depending on what is needed. The brown/gold PCB in the middle is a flex PCB while the red, green and black are normal FR4 PCBs. If possible, for a simple repair we make only one PCB with mechanical buttons, which is mounted under the original foil. If this is not possible, we will make a new foil with the matching PCB. If you are interested in the repair itself, I can recommend the article Repair circuit boards or Electronics repair recommend

Mosertronik - Your partner in repair and small series development

If you have problems with your membrane keypad or need a new membrane keypad, you are welcome to contact us. We offer you a fast and reliable solution at fair prices. Contact us for more information.