Tips for Selecting or Designing a Membrane Switch
- Saturday, 01 June 2013
Membrane switches are known for standing up to tough environmental conditions. Flexible and durable, the membrane switch can be customized with embossing, backlighting, sealing, and electrostatic discharge (ESD) shielding. Membrane switches can be made with either tactile or non-tactile feedback and they can be integrated with LEDs and other components. To get the switch that works for your application, follow these simple guidelines.
What Is A Membrane Switch And Why Use It?
A membrane switch is a multi-layered momentary switch consisting of a graphic overlay, top circuit and bottom circuit. Pressing a key activates the electrical connection. Membrane switches are durable and have a low profile, which allows for space-saving designs and adaptability to each project. Table 1 shows the electrical rating for membrane switches.
Over the past decade, the membrane switch has grown in popularity as designers are seeking a more modernized look, avoiding the older, bulky switches, and looking for ways to fit switches into smaller footprints in today’s equipment. The membrane switch’s sleek, flat design with modern LED lights is appealing with a less industrial look. Figure 1 shows some of the many applications for membrane switches. Table 2 lists some of their design advantages.
Which Overlay Material Is Best For My Application?
The two most common materials used in making the graphic overlay for membrane switches are polycarbonate and polyester. All overlays begin as clear material, with the graphics printed on the reverse side. A variety of finishes can be placed to visually enhance the final membrane switch, including embossing, texturing or finish, varied colors, or backlighting. Table 3 is a guide for selecting the right material for an application.
A Word About Environmental Regulations
Most industries now require RoHS compliance. The RoHS (Restriction of Hazardous Substances) Directive, most well known as the lead-free requirement, also restricts the use of lead (Pb), mercury (Hg), Cadmium (Cd), Hexavalent chromium (Cr 6+), and polybrominated diphenyls (PBB and PBDE).
Ask The Right Questions
Membrane switches are usually customized to fit each project and there is a virtually unlimited range of styles, colors and switch sizes. Please don’t be afraid to ask a professional; use experts who will advise you on your design. They can help you save money, create the most efficient membrane switch, and advise on graphic aesthetics. To find the right switch for your application, use your imagination, and ask yourself these questions. After establishing these answers, create a drawing and schematic for your membrane switch. This will give you a good starting point for requesting an accurate quote.
Overlay or membrane? Decide if you need an overlay (just the graphic) or a membrane switch (includes circuitry).
What size does the switch need to be? Determine the dimensions of the membrane switch and the total thickness that you can have. Remember, if you don’t adhere to the space you have available in your product, the membrane could be too high or too low. To save space, the circuit can be designed in a matrix layout (mapping of the traces using leads that run in both the “X” (rows) and “Y” (columns) directions, resulting in fewer leads with a greater number of connections.