What is a Silicon Rubber Keypad?

The silicon rubber keypad, also known as an elastomeric keypad, is a widely used product in consumer and industrial electronic appliances. It compromises a low cost and unswerving switching solution that combines consistent performance, tactility, and durability. Its significant characteristic is the use of silicone rubber webbing - a type of rubber-like medium comprising mainly of silicone with the consistency of the liquid gel.

The rubber moulded by heat and pressure gives it a concrete finishing for effective utilization as a keypad. This standalone component extensively offers innovative design possibilities than conventional two-dimensional keypad design.

Design of a Silicon Rubber Keypad

It is a user interface design created to enhance the performance of appliances. There are different ways to design rubber keypads; however, a traditional silicon rubber based keypad incorporates an elevated switch with silicone rubber webbing.

The compression moulding quality of this soft and sponge-like product provides tactile feedback. A switch button exists at the top of the keypad, and under this button lies a conductive material such as carbon or gold pill.

All silicon rubber based keypads integrate a circuit layer that acts as a brain and enables the keypad to function. Usually, the circuits use copper flex, but they may also inscribe a rigid printed circuit board, generally known and written as PCB.

Inert Layer

An inert layer of silicon rubber lies below the conductive gold or carbon pill to separate it from the PCB. Accordingly, it averts the switches from actuating until applying an action to the circuitry instituted within each button.

The keyboard has four types of in-built keys, which focus on the relationship between pressure and stroke.

The design of a customized silicon rubber based keypad contemplates size overall, positioning of keys, the thickness of base material, stroke, height overall (including keys), the diameter of pills and key heads, actuation force, and preferred tactile feeling outer diameters, and inner diameters.

How Does a Silicon Rubber Keypad Work?

The silicone rubber's compression moulding qualities form a specific geometry to create angled webbing around a switch, which evenly bends when actuated to yield a tactile reaction.

On pressing the keys or buttons, the initially uniform webbing deforms to let the conductive pill create an electronic switch by connecting with the printed circuit board (PCB). The circuit within the layer completes initiating the required function. As long the keys are held, the circuit remains intact.

When pressure abates from the key, the deformed webbing gets back to its normal position with positive and tactile feedback indicating proper command registration.

The impulse behind Using a Silicone Rubber Keypad

Inexpensive

The moderately cost-effective feature of a silicon integrated keypad makes it an indispensable component of different applications.

Flexible 

It capacitates designers to incorporate aesthetic and cosmetic impacts in the keypad. They can make creative shapes and add pigments into the keys to give an aesthetic and eye-catching touch to the finished product. It is a highly effective way to customize the look of a silicone-based rubber keypad.

 User Friendly 

The angles of this rubber keypad are usually very sharp, naturally yielding a 0.5-millimeter corner radius. This quality makes the keypad much easier to use and more comfortable than usual plastic keypads.

Soft Texture of Rubber Buttons

Keypads can either have rubber or plastic injection moulded buttons depending upon the requirement to add aesthetic touch and the application's end-use. As against plastic, rubber exhibits a soft texture. Plastic keycaps are stiff and rigid. Due to such softness, mechanical engineers opt for silicone rubber instead of using other materials for their keypads.

 Natural Tactile Response

The silicon rubber keypad produces a negligible “popping” impression due to its soft and flexible contact structure. Resultantly, it delivers natural tactile feedback. This feature encourages user’s satisfaction and general input precision. The button on a silicone rubber keypad deforms on pressing. On release, the button “pops” back and produces a tactile response.

Silicone rubber keypad is amazingly easy-going and comfortable to use when compared to other keypads. The three-dimensional buttons assimilated to the keypad conform a consistent tactile feel, making it the first choice in numerous keypad designs built on the product’s provisions.

The user feels a physical click of the buttons as pressure is applied and released from them. The travel, actuation force, and an audible click of the metal dome present inside each button signify that the keypad is working accurately. Such perfect registration of command eliminates erroneous errors and double entries.

 Laser Etching

Silicone rubber keypad upkeeps laser etching causing the keys and legends to look highly visible and stylish. The technique involves burning the upper layer of paint with a laser beam to produce a lighter colour. The embedded backlight selectively lights the laser-etched area within the keypad.

The advantage of laser etching is that the manufacturers don’t need to add colour pigment to the keypad already illuminated with lighting.

Backlit Aesthetics

Backlighting is a discrete feature of most silicon rubber-based keypads. Such keypads have applications in various appliances ranging from medical instruments to educational and industrial products. Some keypads require a backlighting element in specific environments so that the switch or devices may be luminous for better vision in low lighting areas. Backlighting in a silicon based rubber keypad distinguishes the icons and logos and enables the user to understand each button's functionality separately.

The use of EL lighting, fiber optic lamps, and light pipes in the keypad are few things to modify backlighting and avoiding scattering of light.

Resilient to Tough Environments and Aging

Silicone rubber keypad has an inherited ability to withstand extreme temperatures and repel environmental-related dilapidation. The keypad efficiently survives damage under extreme temperatures. This fact holds because the silicone rubber-based webbing can endure temperatures varying from minus 67 degrees to 572 degrees Fahrenheit.

It does not matter if the keypad integrates into applications operating in hot or cold surroundings. This feature makes it a viable option in factories or assembly lines where heat is inevitable.

Water and Chemical Resistant

Silicon rubber keypad is exceptionally resistant to chemical and water exposure. It can efficiently work where moisture is prevalent in the atmosphere, such as in the construction industry. As a result, this component is reliable in outdoor applications where conventional keypads might malfunction.

Durable

Silicone rubber keypad enjoys a durable strength over an extended period. As it can withstand moisture, chemicals, and harsh environments, it can make it through years of wear and tear. Minimal abrasion, anti-rusting qualities, resistance to dust, and liquids further enhance its life quality. Additionally, rubber keypad switches are spray glazed with polyurethane for value-added durability.

Application 

The keypad is used in various consumer items such as remote controls of TVs and split ACs. Due to space constraint in multiple products, such as a digital pocket manometer, calculator, or blackberry type cell phone, the miniature silicon rubber based keypad can maintain the product’s dimensions. It has practical use in various industrial process control applications.

In the medical profession, the power wheelchair application can effectively utilize a silicon based rubber keypad while maintaining the product’s long life expectancy.

Summary

The custom moulded Silicone Rubber Keypad conceives many resourceful design prospects compared to conventional two-dimensional keypad designs. Created by compression moulded silicon-based material, this tactile, reliable, and economical elastomeric keypad is used comprehensively in various industrial, consumer, and medical appliances. Moreover, the flexibility of silicone allows the designers to make an impressive variety of shapes of the keypad.