Article about the future potential of silicone keymats
Published in PC & Industry 6/2023 Article as .pdf >>
The ongoing trend in HMI solutions towards a more intuitive, personalized and responsive user experience seems to be increasingly displacing tried and tested silicone keymats as keyboard solutions. The combination of classics, such as the silicone keymat, and innovative interface technologies offers interesting possibilities and potential for the design of efficient and user-friendly human-machine control units. Because the maxim of making the interface between man and machine uncomplicated and intuitive often requires a mix of proven electromechanical components in combination with multi-touch displays and, for example, gesture and voice control technologies. The keyword here is the integration and sensible combination of the advantages of both worlds. In doing so, attention should be paid to cost-effectiveness, since not everything that is technically possible can also make economic sense.
Use in almost all industries
Especially in the industrial sector, when controlling loads and machines, operating elements must work reliably and be protected for the harsh operating environment. A haptic feedback, especially when handling with work gloves, is important to minimize incorrect operation. Here, the silicone keymat is still a preferred choice due to its closed surface and resistance to moisture, dirt, chemicals and thermal influences.
Improved surface technologies create new standards with regard to the abrasion classes of the coating and the design options for the keyboard layout. In addition to concise haptic feedback, the integration of lighting elements, for example for status display and for finding in diffuse ambient light, plays an important role in the industrial sector. In addition, silicone switch mats enable noiseless operation, which is advantageous in some application areas such as medical technology or audio engineering. Silicone keymats are also very durable and resistant to wear and tear, which is an advantage in a harsh and demanding environment such as automotive.
Endless design options for the silicone keymat
Manufactured using the injection molding process, the silicone keymatsilicone keymats almost infinite design possibilities. It also adapts to your design and is extremely flexible. Different button shapes and individual button colors can be implemented without any problems. Integrated surface structures and textures, elevations or depressions in individual keys create haptic feedback. This allows the user to easily identify and operate. Special surface coatings, such as PU or epoxy coating, make the keys permanently abrasion-resistant.
Illumination of a silicone keymat
A common way to silicone keymats to illuminate is to use SMD LEDs. These small LEDs are mounted on the underlying circuit board and are available in different colors and sizes. A translucent silicone is used for the silicone keypad itself, in order to distribute the light and ensure illumination. The keys are then printed or painted and then labeled using laser engraving. The laser enables very filigree inscriptions.
Through precise injection molding process is a multicolored keyboard backlight possible. An opaque light channel is integrated into each individual key, which is absolutely isolated from the rest of the transparent key and creates a precise bundling of the light beam. status lights of the individual keys are possible.
The standard transparent silicone keymat material is more milky, which is the case with larger ones switch mats can lead to scattering losses of the light source. Enable new materials Crystal clear, highly transparent keyboardsthat offer minimal light scattering. As a result, the luminous flux reaches almost all of the surface. This makes them particularly interesting for brightly lit work environments or for use in daylight. The integration of light channels is dispensed with, resulting in a closed surface that ensures extensive protection of the underlying electronics from dust and moisture.
Integration of silicone keymats
A seamless integration of the end product is guaranteed by an optimal design of the silicone keymat. Injection molding also allows the key layout to be sprayed directly onto a plastic frame as a front frame. This creates an optimal bond between the two components and a completely closed surface. In combination with that injection molded housing a protection class of up to IP68 is achieved.
When more functionality or a more complex operating menu are desired, a combination of silicone keymat and more modern Touchscreen solutions realized. The display and the electronics are combined with the resulting frame in a further processing step. advantage of Multi-component injection molding technology is that only one component is designed. This leads to significantly reduced investments and effort in production and quality assurance.
Robust and durable
silicone keymats impress with their robustness and longevity. Ever more advanced silicone materials meanwhile enable a temperature range of -40°C to +250°C and a mechanical service life of up to 10 million switching cycles. Lifting and actuating forces can be individually adapted to customer requirements. In addition, various button functions are possible, such as rocker buttons.
Key travel from 0,3 to 5,0mm
The key travel varies by application and is usually fixed in the circuit design process to ensure the best possible user experience. Typically, a silicone keymat has a key travel of about 0,5 to 1,5mm, but a range of 0,3 to 5,0mm is possible. Key travel refers to the distance the pressed key travels before making electrical contact. A short key stroke means the buttons are easy to press and require less effort. This can be particularly advantageous for devices with many buttons, in order to ensure fast and convenient operation. In the industrial sector, on the other hand, controlling heavy machinery often requires a longer key travel Desired to get better feedback and tactile feel when pressing the keys.
Electrical contacting of silicone switch mats
However, it is important to note that key travel is not the only indicator of a silicone keymat's quality or durability. There are many other factors to consider when choosing a mat, such as contact life. There are a variety of implementation options for electrical contacting - from inexpensive carbon printing to high-quality metal contact pills with a current carrying capacity of up to 2A. The use of metal snap disks or the actuation of a tact switch is also possible.
carbon pills a cheap variant is often used in silicone switch mats as conductive elements in order to transmit electrical signals from the buttons to the electronic components. The carbon pills are available in various round and oval shapes. Depending on the size and shape, resistances in the range of < 150 Ω ~ 500 Ω can be implemented. For applications that require very low electrical resistance, Low Resistance Carbon Pill (LRCP for short) with a resistance of < 30 Ω is used.
Another important feature of carbon printing is that it has a very low profile, which helps the buttons on silicone keypads to be flat and easy to press. In addition, there is also the possibility of metal contacts, optionally also coated with gold, which enable a resistance of <1Ω. Is a acoustic and concise feedback desired, too metal snap diskn glued in. The actuation forces can be flexibly selected from 20g to 500g and are influenced by the hardness of the silicone, the thickness of the switch mat and the size and shape of the button, among other things.
Inexpensive input solution
Even if the initial costs are higher due to the tools, the silicone keymats Inexpensive to manufacture compared to other custom input solutions. The demand for devices with a high level of reliability, convenience and flexibility will continue to make the silicone keymat an attractive input solution in the future. It should be noted that the construction requires a great deal of experience and expertise in materials science, design and manufacturing technologies. Competent companies usually take over the construction of a suitable silicone keymat and accompany the customer up to series delivery.
pattern set
The N&H sample set includes a special sample silicone keymat with a variety of sample keys and constructions, as well as a samplemembrane keyboard with the various equipment options.
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