Silicone keymats – on-site advice, production in Asia
Published in Markt & Technik
"The business with silicone keymats requires a lot of consultation, because the interaction with the housing and the printed circuit board is more complex than, for example, with membrane keyboards," emphasizes Yine Zhang, Managing Director of N&H Technology. Therefore, the company considers the keymat not only as a component, but as part of the entire electronic input system.
N&H Technology is a medium-sized company specializing in input elements. Silicone keymats are part of the company's core business. According to the company, the product area is growing by around 30 percent every year!
N&H's approach is to realize customer-specific projects in this country; production is inexpensive and takes place at various locations in China. “Price pressure is increasing. With regard to the competition in the market, however, we judge this development to be rather positive because our Chinese roots enable us to hold our own better than other competitors «, says the managing director and owner of N&H Technology, who was born in China.
Application of silicone keymats
The field of application for silicone switch mats is extremely diverse: it ranges from telecommunications, medical technology and industrial electronics to automotive applications and measurement and control technology.
The technology can demonstrate its advantages above all when large quantities are required. In the case of small series, there are high one-off costs for the tools. Furthermore, the silicone keymats allow a very flexible design. For example, different button shapes can be implemented without any problems. The force-displacement behavior can also be adapted to the respective requirements of the application.
The choice of surface materials, such as plastic or epoxy coatings and different paints, also allows freedom of design. In addition, there are different implementation options for the electrical contacts - from inexpensive, yet safe carbon printing to high-quality metal contact pills with a current carrying capacity of up to 2 A.
However, the flexible design is offset by a higher construction effort than with membrane keyboards. In addition, "most designers have the same way of thinking as with plastic injection parts," reports Yine Zang. However, in the case of silicone keymats, which are usually manufactured using vulcanization press tools, important design features are different from those of the plastic injection-moulded parts:
The tolerances are larger and require an appropriate design. A special design for tolerance compensation is often required for large silicone switch mats. No draft angles are required. Slight undercuts can be realized without additional effort. The formation of burrs is stronger than with plastic injection-moulded parts. However, it is usually not disruptive in the invisible range. The mechanical measurement is much more difficult than with plastic injection parts because the material is flexible.
Silicone keymats retain their volume
In addition to the differences mentioned, Yine Zhang wants to clear up a widespread misunderstanding: »Most designers assume that the silicone material is flexible and compressible. In reality, the material can be compressed, but it retains its volume!«
N&H Technology offers silicone keymats in all common technologies. "The trend is towards silicone keymats with integrated plastic and metal parts," says Yine Zhang. The company is increasingly making such composite components.
N&H also includes housings, printed circuit boards, displays, acoustic components and special connection cables with connectors in its design and technical advice. If required, the company can supply complete assemblies and complete solutions. "There are many interfaces with our other product areas," explains the managing director. The company assembles the assemblies and complete solutions in Chinese plants that are certified according to TS 16949.
N&H Technology has a development and design team as well as a technical laboratory for safety mats in China and also in Germany.
And when are membrane keyboards superior?
Membrane keyboards are stable on the market. The advantage: they are waterproof and resistant to chemicals. Even under special operating conditions, the membrane keyboard remains permanently operational! This is a basic requirement for many custom designs. A big advantage that the membrane keyboard has over other technologies is the closed surface. As a rule, polyester films are used as decorative film material, which have good resistance to mechanical stress and chemicals. Therefore, membrane keyboards from medical technology or the food industry have become indispensable. Special coatings can even actively counteract the formation of germs.
Membrane keyboards allow almost unlimited color design options. In addition, very ergonomic key shapes can be realized using various embossing techniques such as dome, key and edge embossing. In the case of customer-specific input elements in the medium quantity range, the membrane keyboard offers a thoroughly acceptable price-performance ratio. (c.p.)
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