Overview on Custom Elastomer Keypad Design | Manufacturer

Elastomer Keypad Introduction: What is elastomer keypad?

Elastomer keypad (also known as elastomer buttons, elastomer switch, rubber/button pad or silicone button, silicone keyboard) is made from silicone rubber, which is a kind of elastomeric translucent synthetic material. The “Silicone-Oxygen” molecular structure shown below provides it with good resistance to heat and low temperature, aging resistance and excellent electrical properties.

Elastomer keypads are widely used for electronics, including electronic calculators, remote controls, telephones, electronic toys, computer keyboards, learning machine buttons, encoder buttons, and digital product buttons. The following are some features of elastomer buttons:

①Support the design of various styles and colors

②Waterproof and contamination prevention

③Cost effective

Elastomer Keypad Structure: How do silicone buttons work？

Basic Structure:

① Silicone button/key

② Silicone button pads/Key mat

③ Key & Button webbing/Elastic webbing

④ Button travel

⑤ Conductive pill (Contact area)

The basic structure and mechanics of most silicone keyboards are similar. On the top, it is switch button. Under the button, it is conductive contact. Below the conductive contact, it will be a PCB board. Key webbing can be found between conductive contact and key mat. When we press a silicone button, the key webbing will be forced to deform, then the conductive contact will touch the PCB board. The action will realize a button press. Due to the actuation force, the button will rebound to its original position when pressure is removed from the button.  

Button Pad Manufacturing Process: How to make a silicone keypad?

Elastomer keypads are formed by using compression molds.

First the mixed and pigmented raw silicone material should be cut into equal sizes, thickness and specific weights to ensure their volume will appropriately fill the cavity.

Second the cut pieces should be placed in a pre-heated mold correctly and the mold should be closed. Sometimes the Teflon is usually used to place the material.

Third, under certain pressure, temperature and time, these cut pieces will be transformed into the shape of the cavity. The vulcanization process will harden the material and permanently transforming it into its finished shape. The forming of different types and designs of silicone keypads need different pressure, heat temperature and time. The molded silicone keypad with flash should be removed from the mould manually. The flash can be tore off by hand easily.

Fourth, some residual catalyst material from the raw silicone may not have fully vulcanized and that will gradually affect keypad function. Under the circumstances, the button should be placed in an oven to heat and evaporate residual catalyst material.

What affects silicone rubber pad actuation force/pressing force?

① Return force of raw material

Return force, also known as rebound resilience, which is defined as the force that help the button return to a non-actuated position. Raw material with good rebound resilience will have better actuation force. 

② Material placed on the cavity

Material placed on the cavity should have the same size and weight. The weight of a cut piece depends on the weight of a silicone keypad. If a cut pieces weight more, actuation force of the button will increase.

③ Hardness of material

Silicone material with higher hardness will provide elastomer keypads with larger actuation force to a certain degree. If the actuation force cannot meet the requirement, changing the hardness of raw material is an option.

④ Button webbing

Button webbing is the important factor that will affect silicone button’s actuation force. A silicone button with thicker key webbing will provide button with larger actuation force. Generally, the button webbing will be made thinner first because to thicken key webbing is easier and more cost-effective than to thin it. 

⑤ Protection coating

Protection coating is to protect surface symbols/legends from abrasion, which includes oil coating and PU coating. The actuation force will increase if silicone keypad is coated.

Why is the silicone keyboard jammed?

① The key web is too thin so that the actuation force is too small to rebound. In addition, uneven thickness of button webbing may also cause silicone button to stuck.

② The narrow clearance between the silicone button its mating structure will lead to the jam of keypad.

③ If the silicone button leans to one side when pressing and then gets stuck, it may caused by the loose of the mould positioning legs, its improper positioning or the uneven material placement.  

                                                                                                                                                                                                                                  Elastomer Silicone Button Classification

Elastomer Keypad Surface Symbols/Legends:

① Silkscreen printing: It is a process that squeezing paint through a silkscreen to print symbols on the surface of button. Using silkscreen printing over clear silicone is a economical way to achieve backlight effect.

② Laser etching/engraved: Laser etching is the process that removing the color coating (usually black in color) in top layer to reveal silicone translucent white below. It has great backlit effect.

③ Embossed & Debossed molded symbols: The legend is a part of the mold. Embossing or debossing symbols is the most cost effective way. The marking will not wear off is its greatest advantage. However, the dirt is easily to trap in the corners or recesses.

Elastomer Keypad Protection Coating：

①PU coating: PU coating has good protective effect and abrasion resistance. It offers a great performance over cost ratio.

②Oil coating/Matte smooth coating: Oil coating has good tactile feel and it is cheap. For most application of silicone button, matte smooth coating is suggested.

③Epoxy coating: Epoxy is thick and glossy which should be applied by hand. It looks like plastic. This coating is extremely durable but expensive.

Conductive Rubber Keypad(Conductive Material):

①Carbon pills/Graphite pads

②Conductive ink printing

③ Nickle pills

④ Golden Pills & Cooper pads

⑤Metal domes

Xiamen Better Silicone rubber Co., Ltd as a reliable silicone rubber keypad manufacturer and suppliers, provides various designs of silicone buttons and offers professional service for you.