What are membrane switches?
Membrane switches, also known as membrane panels or keypads, are electrical switches with a user interface to control equipment and machines. The top layer is typically the graphical interface, also known as a graphic overlay, which identifies the functions being controlled using icons or text.
Next, below the graphic overlay, are adhesive layers and a spacer layer to bond the circuit to the graphic overlay. The circuit layer is where the magic happens. Conductive inks are applied through a silk screen-printing process. In some cases, the membrane switch requires additional insulating layers made of non-conductive materials to prevent short-circuits. To complete the switch, an additional adhesive layer is used on the rear of the circuit to bond it to the bezel or substrate.
To improve the user experience, membrane switches typically provide haptic or visual feedback. A great example of haptic feedback is through the use of tactile metal domes or poly-dome construction. When this type of feedback is used, a user will press a key or button and feel a ‘snap’ action as the dome is compressed. This type of key might also provide some audible feedback from the ‘snap’ of the dome. As for visual feedback, the membrane switch can have embedded LED indicators or feedback can be visually displayed on a separate display or monitor. Typically the membrane switch circuit only has resistors and LEDs mounted to it, as opposed to a circuit board which has limitless options.
Membrane switches have replaced mechanical switches since they tend to be low-cost, user friendly and durable in multiple environments.
What kinds of industries are membrane switches used in?
Membrane switches can be created for a variety of industries and environments. Some common uses are in appliances, consumer products, industrial machinery, medical instruments and automotive industries.
Creating a Membrane Switch with RSP
In order to create a properly designed membrane switch, RSP is very involved in the development. RSP helps customers develop a membrane switch based on sketches from a napkin, a verbal description or a production file created by the customer. The most common approach is when a customer supplies the graphics and a description of how they plan to connect the circuit to their device (also known as a pin out). From there, RSP creates the circuit layout and details.
In order to provide the optimal solution, it is very important to consider how and where the membrane switch will be used. For instance, if the switch will be used in a damp environment rather than a dry environment, the membrane switch will need to be created with different materials and additional design elements like a gasket.
Additional considerations may be, but not limited to:
- How many actuations are required?
- Lifetime of switch?
- Where will the switch be used? i.e. dusty environment
- How will the switch be used? i.e. Operator with or without gloves
When we begin quoting a membrane switch opportunity the following information is needed:
- Desired dimensions
- Number of opaque and/or transparent colors
- Desired top layer material
- Desired adhesive (top and bottom layers)
- If embossing is required
- Type and number of keys
- Desired number of LEDs and colors
- Connector type
- Desired quantity
There are many other details that may be needed, but the above is a great start.
Don’t know where to start? We’re here for you and will walk you through every step along the way.
Mounting Membrane Switches
Once membrane switches are created, they need to be mounted or assembles to the equipment/machine they control. At this point, the switches are vulnerable to damage prior to mounting them. It is important to follow the specific mounting instructions to prevent damage (see mounting instructions tab). If needed, customers can send RSP their enclosures to assemble the membrane switches for them to prevent damage.