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What is a Membrane Switch? JRPanel

What is a Membrane Switch?

A membrane switch or more precisely a membrane switch assembly is comprised of several flexible layers that make up a complete switch package. This assembly can have as few as one active area (key or button) to several dozen active areas. How many keys or buttons is only limited by the physical size of the finished application.



A membrane switch is built in such a way to provide a momentary contact when force is applied to a key area. The most common materials that are used in the construction of a membrane are polyester (PET) and pressure sensitive adhesive (PSA). There are two polyester layers required, these layers are selectively printed with conductive inks and separated by an adhesive layer that has been die cut as to provide an opening between the polyester layers. In its most basic form, when a human finger pushes on an active area, one layer of polyester flexes or moves through the opening in the adhesive layer and shorts to the other, stable, polyester layer causing the momentary contact. The distance that the polyester travels can be as small as .007”, once the force is removed, the switch opens again.



Membrane switch technology has become a reliable front panel solution where environmental concerns or frequent cleaning are an issue. The sealed nature of the technology coupled with its reliability and ability to offer tremendous aesthetic flexibility make it the solution of choice for many industries.



Types of Membrane Switches



Non-Tactile Membrane Switches

The most reliable and economical membrane switch is the non-tactile type. However, they do not give the user direct feedback from the switch. Using a LED indicator or display change can sometimes overcome this drawback.
Non-tactile switches also have the advantage of easily creating custom shapes and sizes of the active keypad areas.


Tactile Membrane Switches

Tactile membrane switches have a snap action that is clearly noticeable to the operator. Conductive stainless steel snap domes have the best action. They can also eliminate the need for a flexible upper circuit layer. To ease the final mating of the switch and avoid the possibility of a dome becoming inverted a .015" - .020" backing layer can be provided.
Hydro formed poly domes offer a milder tactile response and a narrower operating temperature range then the metal dome.
Because of the relatively short travel of membrane switches, it is often necessary to provide users with some type of feedback. Feedback can be visual, audible, or tactile. Visual or audible feedback should be a consideration in the electronics design. Domes can be added to a membrane switch to provide tactile feedback. There are two types of domes that we use in membrane switches, stainless steel and polyester. There is no significant difference in reliability between these two dome technologies.

Mixed Panels

Non-tactile and tactile switches can be mixed in the same panel. This can be desirable when a large active area is needed for a particular switch or perhaps hidden maintenance or programming switches.

PCB Backed Membrane Switches

A Flex printed circuit board can be used for the lower circuit. The board can provide structural support and incorporate numerous surface mount components. This assembly can be bonded to your PCB or sub-contractors can be utilized to provide this type of construction.

Membrane switches have been a versatile and durable option for human to machine interfaces since the late 1970’s and are still used across the globe today.
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