One of the key steps to designing high-quality equipment is choosing the right components for it. Unfortunately, many businesses out there are so busy focusing on the mission-critical tasks that they forget about the many elements of their applications. However, a component like the right membrane switch can take the project to a new level.
We decided to share this guide to help you understand what types of membrane switches are available on the market today and to make the most of this component for your project. Read on to find out everything you need to know about membrane switches and their design.
What is a membrane switch?
A membrane switch is a device sensitive to touch, which is created by the printing, cutting, and lamination of film plastic materials that are precision thin. By applying fingertip force to the front surface of the switch, the membrane switch makes and retains the low voltage and low current momentary electrical contact.
Membrane switches are often used in microprocessor-based control systems that you find in communication, appliance, instrumentation, and medical products.
The membrane switch technology is a reliable front panel solution, especially for applications where frequent cleaning or environmental concerns are important. Membrane switches are sealed, reliable, and able to offer extraordinary aesthetic flexibility. That’s you can benefit from a broad solution choice that fit the demands of any industry.
Membrane switches you can choose from
Tactile membrane switches
These are membranes that offer a snap action that is most clearly noticeable to the person operating the switch. The best action is offered by conductive stainless use snap domes. Such a setup can eliminate the need for a flexible upper circuit layer. Professional manufacturers can provide a backing layer that allows easing the final meeting of the switch and helps to avoid the scenario of the dome becoming inverted.
Another type of tactile membrane switch is hydroformed poly domes. These offer a mild tactile response and narrower operating temperatures than the metal domes.
Given the relatively short travel of membrane switches, it might be necessary to provide users with some kind of feedback. This feedback can be tactile, audible, or visual. If you’re aiming for visual or audible feedback, it’s necessary to consider that already in electronics design. You can add domes to a membrane switch in order to provide tactile feedback. The most common types of domes are made of stainless steel or polyester. These two technologies are quite similar and offered no significant difference in their capabilities.
Non-tactile membrane switches
This type of membrane switches is the most reliable and economical one. However, note that non-tactile membrane switches don’t give users direct feedback from the switch. You can address this problem by using a display change or LED indicator. Another advantage of non-tactile switches is that they allow to easily create custom shapes and sizes of the active keypad area.
It’s possible to combine non-tactile and tactile membrane switches in one panel. When to use such a mix? Applications that can benefit from mixed panels are ones that require a large active area for a particular switch. Another reason is hidden programming or maintenance switches.
PCB backed membrane switches
PCB stands for a printed circuit board. This board can be used for the lower circuit and provides structural support, incorporating various surface mount components. A manufacturer can bond this assembly into a PCB or utilize subcontractors to provide this type of construction for your application.
User interface design and membrane switches
When choosing the membrane switch for your application, it’s necessary to take the question of user interface design into account as well. Here’s a short guide to help you understand what your options you can choose from when it comes to the user interface in membrane switches.
The look on the graphic overlay is critical to the user’s experience with your equipment. The good news is that manufacturers like Melrose Nameplates can produce nearly all callers of graphic overlays.
Graphic overlays can be equipped with even the finest lines or spaces between the lines that are printed and .006″ thickness. And the maximum line screening is 230 LPI (lines per inch) for process printing and graduated halftones.
Moreover, manufacturers can use embossing together with non-tactile or tactile membrane switches. Note that pillow embossing doesn’t give the membrane switch a tactile response.
Integrated display windows and LED indicators can be easily incorporated into the design of a membrane switch.
The option that poses the least limitations is single-point and block LEDs. Such LEDs perform well with practically any material surface finishes. However, to achieve greater diffusion, they require a matte or textured surface finish. Note that LEDs can’t come through the active area of the tactile switch. However, experienced manufactures can make them appear as if they were a part of the switch.
Integral single-point LEDs (also called surface mounted) can be mounted onto the bottom layer lower circuit. You can choose from a wide range of colors, including the bicolor option. If the graphic layer is embossed to accommodate LEDs, the manufacturer can provide termination from the same connector tail as the switches. In this case, the graphic doesn’t need to be embossed if the LED termination is set up on a separate tail.
Manufacturers can design digital windows to boost the specific display used in your application. The texture might distort the appearance of a display that is not directly against an overlay. That’s why matte and gloss finishes work best here. Moreover, you can take advantage of translucent filtering inks that can be printed to enhance the display’s appearance.
Selective texturing is a screen-printed application of a scratch-resistant surface hard coat to the front of the graphic overlay. Why is selected texturing so popular? The main idea here is to improve the clarity of display windows or visually emphasize specific areas of your application. For example, a textured hard coat can be applied to anti-glare or glossy materials to result in enhanced display windows. You can also apply clear hard coat textured material as well.
Overlay materials for membrane switch applications
The most commonly used material is polycarbonate because it’s easy to die-cut, print on, and emboss. It’s a cost-effective alternative to other materials. But it also comes with some disadvantages you should be aware of. Polycarbonate begins to show signs of wear sooner than alternative materials. In most applications, overlays made of polycarbonate will last 100,000 cycles during lifecycle testing. Note that uncoated polycarbonate might be susceptible to damage from chemicals. If your polycarbonate overlay is going to be used in a harsh environment where it might be subjected to chemicals, you should definitely cover it with a hard coat for protection.
An alternative material is polyester. In general, polyester is more robust and has superior lifecycle and chemical resistance properties. For example, in lifecycle testing, polyester shows no signs of wear after even 1 million cycles. However, this comes at a price. Due to its memory properties, polyester often requires hydroforming rather than embossing. And hydroforming is much more expensive, both for unit cost and tooling. Moreover, manufacturers find polyester more difficult to die cut. This results in more frequent three reblading of steel rule dies.
Both types of materials are available with various hard coats and textures. In their uncoated glossy form, polycarbonate and polyester are susceptible to scratching. That’s why we recommend to add a hard coat to gloss materials to ensure its long operation.
We hope this article helps you understand the value a membrane switch brings to an application and all the different options you can choose from to find exactly what you need. Different materials come with different pros and cons, so it’s essential to research the matter before approaching the manufacturer.
At Melrose Nameplates, we have years of experience in providing clients from the most demanding industries, such as healthcare, aviation, and defense, with high-quality components for their diverse applications.
If you have any questions about membrane switches, get in touch with our consultants to clarify any doubts and see how we could provide you with membrane switches that perfectly match the demands of your project.