Complete guide to membrane switches for 2021
Today engineers can choose from a variety of switch technologies: mechanical switches, capacitive switches, and membrane switches. This decision is more significant than you may realize. The switch is the component that breaks the electrical circuit and either diverges or stops the current flowing between the conductors. If you select a low-quality switch, it will affect the entire experience of your application.
In this guide, we focus on the most commonly chosen switch type: membrane switch. Keep on reading to learn more about:
- A guide to membrane switch types,
- Key advantages and drawbacks of membrane switches,
- Common membrane switch materials with their pros and cons.
What is a membrane switch?
A membrane switch is a touch-sensitive device manufactured using precise thin-film plastic materials that are printed, laminated, and more. Membrane switches are often used in communication, appliance, instrumentation, and medical equipment that employ microprocessor-based control systems.
The technology is so popular because it provides a reliable front panel option, especially for applications that require regular cleaning. Membrane switches are waterproof and provide a wide range of aesthetic options.
Key membrane switch types
Tactile membrane switches
These are membranes that have a snap motion noticeable by the person controlling the switch. Conductive stainless steel snap domes provide the finest movement. A flexible top circuit layer is not required in this setup. Professional manufacturers can offer a backing layer that facilitates the final assembly.
Hydroformed poly domes are another sort of tactile membrane switch. These domes have a moderate tactile sensation and operate at lower temperatures than metal domes.
Giving users feedback about their actions is an important element in membrane switch design. Tactile, auditory, or visual feedback are all available. If you’d like to add visual or auditory feedback, it’s necessary to factor it into the electrical design from the start.
To offer tactile feedback, manufacturers add domes to membrane switches. Stainless steel and polyester are the most frequently used materials for domes. These two technologies are quite comparable, and there isn’t much of a difference between them in terms of capability.
The technology is so popular because it provides a reliable front panel option, especially for applications that require regular cleaning. Membrane switches are waterproof and provide a wide range of aesthetic options.
Non-tactile membrane switches
Non-tactile and tactile membrane switches can be combined in a single panel. When is such a combination a good idea? Applications that require a large active area for a specific switch might benefit from mixed panels. Hidden programming or maintenance switches are another good reason for choosing mixed panels.
Mixed panels
Non-tactile and tactile membrane switches can be combined in a single panel. When is such a combination a good idea? Applications that require a large active area for a specific switch might benefit from mixed panels. Hidden programming or maintenance switches are another good reason for choosing mixed panels.
PCB backed membrane switches
PCB is a printed circuit board that may be used for the bottom circuit as well as providing structural support by combining different surface mount components. The assembly can be bonded to a PCB by a manufacturer or built by subcontractors.
User interface design and membrane switches
When selecting a membrane switch, consider its impact on the user interface design. Here’s a short guide to potential user interface choices available in membrane switches.
Graphic overlays
Display windows
A membrane switch’s design may accommodate integrated display windows and LED indications.
Single-point and block LEDs are a good option with the fewest drawbacks. These LEDs work nicely with almost any material surface finish. They do, however, require a matte or textured surface finish to produce better dispersion.
On the bottom layer lower circuit, you may place integral single-point LEDs (also known as surface-mounted LEDs). Customers can pick from a variety of colors, including bi-color options. Manufacturers may offer termination from the same connection tail as the switch if the graphic layer is embossed to accept LEDs.
Digital windows can be designed to enhance the individual display utilized in your application. A display that is not directly against an overlay may be distorted by any texture. As a result, matte and glossy surfaces are found to perform well in this situation. Additionally, you can use transparent filtering inks printed on the overlay to enhance the display’s look.
Selective texturing
What is selective texturing? It’s a screen-printed application of a scratch-resistant surface hard finish on the front of the graphic overlay. Using such chosen texturing often aims to make display windows clearer or emphasize particular parts of your application. A textured hard finish, for example, can be placed on anti-glare or glossy surfaces to improve visibility.
Common overlay materials for membrane switch applications
Polycarbonate
Polycarbonate is the most often common material for membrane switch production since it’s simple to die-cut, print, and emboss. It’s also a more cost-effective option than other materials.
It does, however, have certain drawbacks that you should be aware of. When compared to other materials, polycarbonate begins to show symptoms of wear sooner. During lifetime testing, polycarbonate overlays will withstand 100,000 cycles in most applications.
It’s worth noting that uncoated polycarbonate might be vulnerable to chemical degradation. If you’re planning to use your polycarbonate overlay in a rough environment where it could be exposed to chemicals, you should protect it with a hard coat.
Polyester
Polyester is more durable and has better chemical resistance and lifetime characteristics. It exhibits no indications of wear after 1 million cycles in lifetime testing. This, however, comes at a cost.
Polyester frequently needs hydroforming rather than embossing because of its memory characteristics. Hydroforming is also significantly more costly, both in terms of unit cost and tooling. Furthermore, die-cutting polyester is more challenging for producers. Steel rule dies must be re-bladed three times more frequently.
Both kinds of materials come in a variety of hard coatings and textures. Polycarbonate and polyester are scratch-prone in their uncoated glossy state. To guarantee a long lifetime, we recommend applying a hard coat to gloss materials.
How to select the best membrane switch for your application?
Membrane switches come in a variety of forms. How can you choose the best type of membrane switch for your project? Here’s a quick guide to the most important considerations you need to make.
1. Key size
The size of the key is critical when selecting the proper membrane switch for your application. Put yourself in the shoes of your app’s user. Consider how they’ll use the membrane keypad in a variety of situations. This will give you an idea of the correct key size to fit the user’s expectations and make it easy to operate your equipment.
Most mobile phones with membrane keypads, for example, feature smaller keys to assist minimize the overall size of the device. The same may be said of remote controllers. If the membrane keypad is to be used in a large machine, it will almost certainly require larger keys. As a result, while designing your membrane switch, it’s critical to think about key size from the start.
2. Key spacing
Another thing to consider while designing membrane switches is key spacing. Make sure your keys are placed far enough apart to avoid users from accidentally hitting the wrong keys. Users may make similar errors if the keys are set too close together. This will have a negative impact on the user experience.
Make sure that your keyspaces aren’t too big and that your keys aren’t too far apart. To provide the best user experience, establish a balanced spacing between the keys.
3. Pressure
Membrane switches detect the pressure exerted by the user’s fingertips. That’s essentially how they operate. Consider yourself a user who presses a key. The electrical contact establishes a direct link to the circuit underneath it. The keypress is recorded at this point.
Membrane switches today have varying levels of pressure sensitivity. As a result, you must evaluate the pressure that will be exerted on your equipment’s membrane switch.
While many users prefer low pressure, depending on the situation, some may feel that higher pressure is more practical. When developing a membrane and creating a good user experience, one of the most crucial elements to consider is pressure.
4. Tactile feedback
Another thing to think about is tactile feedback. Many membrane keyboards are made with relatively minimal tactile feedback in mind (or even no tactile feedback at all). This implies that when users push keys, they receive no feedback.
Tactile feedback keyboards and switches may increase the accuracy of user actions while also creating a far more pleasant experience with your equipment. So keep that in mind and learn more about your target customers’ tastes before opting for a tactile feedback-free alternative.
5. Water resistance
Water-resistance is a crucial quality to consider when selecting a membrane switch for your application. Even if the keypad is placed or used indoors, it may be damaged by dampness. Moisture from the air, for example, might collect and settle beneath the keys. As a result, the electrical circuits will be damaged. Fortunately, manufacturers can eliminate this risk with the use of gaskets.
Get a high-quality membrane switch for your project
Our specialists assist our customers at every stage of the process to ensure that the components they select are of the highest quality and precisely balance cost and performance.
We have a long history of supplying membrane switches to the most demanding applications in areas such as healthcare, navigation, and the military.
Do you have any further questions about membrane switches and their construction? Get in contact with us for skilled guidance and to learn how our membrane switches could enhance your application.
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