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26 Sep 2018

How Are Membrane Switches Designed?

How Are Membrane Switches Designed?

When you hear the word “membrane switch” you may think of some sort of biological mechanism in a living being. However, in actuality a membrane switch product is actually the touch switch in an electrical circuit. Instead of being made of copper or metal, it is made of PET or ITO. The CCL Design experts can help you in regards to more information on them, but why not begin your discovery of them by reading the list below.

Firstly, a little history…

At first membrane switches were mocked for being a low-cost alternative, however as the 1980’s rolled on, they established their potential, and were upgraded from simply being decorative elements to domed keys with metal domes to improve tactile feedback. Eventually LED lights were even incorporated into the design to assist with viewing the keys. But in the present, they have now made their way into being incorporated into the touch screen market. Membrane switches present engineers an opportunity in regards to their flexible design and IP rating options, so much so that they are now the standard for many start up businesses and industries.

Understanding the Basic Design

With membrane switches, it is important to remember that whilst the design is extremely flexible, there is always the basic components that are needed to make them. As designers usually work to make them as compact as possible, most designs have metal domes which are around 7-mm thick, to avoid any air gaps allowing in toxic chemicals or dust. If there is a potential gap, then this can be compensated by adding a small vent. Another means of avoiding this in the basic design is also to look into Laser Cut membrane keyboards. This is to ensure that the keyboard remains as tight as possible whilst maintaining its aesthetic design.

To round things up, it is normal to see the following parts within a membrane switch:

• A Compact Support Layer

• Bottom Circuit and the Back Adhesive

• Top Circuit

• Space Adhesive

• Graphic Adhesive and Overlay

Display Options

When it comes to the display, Integral display windows and LED indicators can be easily incorporated into the design of your membrane switch. Out of all the LED’s you could choose to light up your display, the best are Single Point and Block-LED, as both perform well with any surface cover. However, be warned that LED’s cannot appear through the active area of the switch, although they can appear as part of it.

You can even include Digital Windows that are designed to enhance your display. However, try not to incorporate too many textures as these may distort the overlays within the display. It is best to stick with Matte and Gloss finishes, or even Translucent filtering inks.

Electronic Additions

When looking into which membrane switch may suit your product, it is essential that you look into the electronic performance in regards to their circuitry.There are a number of basic performance specifications that can be chosen for the circuits including:

• Open Circuit Resistance: Fifty Mega Ohms

• Loop Resistance: Less than One Hundred Ohms

• Contact Bounce: Five Milliseconds Nominal.

Extra Electronics

Whilst Polyester is the most common material used for the Graphic Overlay, there is a lot more customisation that is required for the touch screen side of your membrane switch. This includes LED lighting and textures, as well as embossed features and keys. You can even update the sensitivity of the keys to contain backlighting and sensitivity or haptic feedback.

Potential Problems

Whilst these LED and additional electronics can provide a more personalised touch in regards to your touch screen and membrane switch, you must remember that these devices can be fragile if not correctly assembled. The sheer stress, vibration and use can cause problems on the print of the membrane’s switch’s printed keypad. Failures from the LEDs can happen if the membrane is stressed from inadequate handling, (OEM) inspection line damage or even just from being shipped to your house. Be wary that most failures occur once the product has been received by the client. If you receive a faulty product then be sure to alert the company, as you certainly do not want to be paying any repair or replacement costs.

For only the best…

As the membrane switch can make or break a product, it is important to keep an eye on the most up-to-date versions of them on the market. There are certain features that you should certainly be willing to invest in. For instance, Optical Bonding laminates over the cover screen, touch screen, LED cell and the membrane switch with a transparent liquid adhesive.This means that the screen has the chance of having a long life without scratches, as well as the keys and internal components being protected from the outside environment. With dirt, oxygen, condensation and liquid kept on the outside, this will also allow the temperature to remain stable without fluctuating. Any scratches or cracks will also have a higher chance of remaining un-shattered.

It is important to have as much as assistance as you can when choosing the correct membrane switch and system for your product. It should be easy to clean and easily operable, as well as simple to install and connective to additional devices. CCL Design would be more than happy to provide this help, so feel free to get in contact any time!

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