MEMBRANE SWITCH KEYBOARDS

WHAT ARE MEMBRANE SWITCH KEYBOARDS?

Is there a more iconic piece of hardware associated with computers than the keyboard? Born from the lowly typewriter, most keyboards today still have the QWERTY key layout, designed to slow a typist down so the keys would not jam together. Whether you type 60 WPM or punch it one finger style, your keyboard must do its job day in and day out without fail.  Did you know a membrane switch is hidden within the keyboard you are using right at this moment?

Membrane switches are ideal for use in a keyboard application for many reasons, including the low cost of manufacturing so many switches in such a tight proximity, low material cost, the high reliability rate, and the need for sealing out the occasional liquid bombardment of soda or coffee. The membrane switch resides directly under the plastic key caps which are there mostly for tactile feel. The plastic cap acts as a plunger and pushes down on the membrane creating a momentary contact of the membrane layer.

The membrane itself is made of layers of polyester with printed conductive traces that is die cut and folded three times. The middles layer of the tri-fold has the spacer holes and this is what makes it a membrane switch.  The three layers are bonded together with ultrasonic welds, eliminating the need for costly adhesives.  The membrane layer typically connects to the wire harness by means of a Z axis connector and a small circuit board all held together by the plastic housing which makes up your keyboard.

MEMBRANE KEYBOARD SWITCH ASSEMBLY

A membrane keyboard switch assembly can also be incorporated into molded rubber rather than the hard plastic keycaps. This useful combination works well when making custom keyboards of all different shapes, sizes and colors. Rubber keyboards can be used in extreme environments in which normal keyboards would fail. Typical high volume keyboards for computers are designed around low cost and are generally not sealed. Membrane keyboards applications used in hostile environments include medical devices, CNC mills, and irrigation controllers.

BACKLIGHTING YOUR MEMBRANE SWITCH KEYBOARD APPLICATION

If you would like to backlight your application, the membrane switch construction would incorporate either light guides or LEDs for uniform lighting.  Other options for backlighting are fiber optic backlighting and EL backlighting.  Depending on the requirements of your application such as thickness preference, shape, environmental exposure, and other unique specifications, the backlighting options would vary and be selected specifically to fit the function of your device.  Using the latest LED powered lighting can reduce cost and reduce power used by a device.  Since many devices today are portable, this backlighting solution is more relevant than ever.

A variety of applications that use backlighting solutions are: remote controls, laboratory equipment, airplane dashboards, medical devices in dimly lit operating rooms, consumer appliances, such as coffee makers and microwaves, laptop keyboards, and many other applications that we all come in contact with daily or sporadically.

We have various backlighting samples that you can evaluate and consider for your application.  Please feel free to submit a sample request  and we’ll send you a variety of useful samples and tools you can experiment with for your application.

NormaTec membrane switch with embossed keys, a lens, and gradient color patterns
5-button membrane switch, with integrated window, designed and manufactured for Bunn-O-Matic
12-button, embossed key, membrane switch with integrated window, designed and manufactured for Baxter Healthcare
10-button membrane switch, with mechanical rotary-dial cut out, designed and built for CareFusion

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