Membrane switch keypad supplier

In general, membrane switch keypads have six parts. Including graphic overlay, graphic adhesive, upper circuit layer, adhesive separator, lower circuit layer, and adhesive bottom layer.

2.1 Graphic overlay

Screen printing beautiful patterns and texts on the raw material, then the graphic overlay is finished. Usually, In general, the membrane switch manufacturer uses PET, PC or other colorless transparent sheets, which thickness is less than 0.25mm. As we all know, the main function of graphic overlay is to play the role of mark and button. It always acts as a touch screen not only in membrane switch keyboards but also membrane switch panels. And for keypads, their control panels are raised. Therefore, the material should have features of high transparency, high ink adhesion, high elasticity, and high toughness. Of course, according to the needs of customers and application scenarios, we HuaiSong Industrial can change the material to engineer and manufacture cost effective products. Usually, we also use silicone rubber keypad, commonly known as a rubber dome keyboard or rubber dome switches.

2.2 Graphic adhesive layer

The main function of the graphic adhesive is to closely connect the membrane overlay with the upper circuit layer. So that it will achieve the sealing and connection effect. In general, this layer requires a thickness of between 0.05 and 0.15 MM. Also, it should have high strength and aging resistance. In the production, the switch manufacturer always uses a special membrane switch double-sided tape. However, some membrane switches are required to be waterproof and resistant to high temperatures. Therefore, we have to select materials of different properties according to the different needs of customers.

2.3 Upper circuit layer

It is between the graphic adhesive layer and the adhesive separator. Generally, we use PET double-side tape. An upper circuit is formed by attaching the metal dome to a single layer of glue. Materials include flexible circuit layer, copper flex, and hard circuit board. As we all know, the metal dome can generate tactile feedback. While pressing membrane switches, the contacts of the upper circuit are deformed downward and are in contact with the plates of the lower circuit. After releasing the finger, you can get a tactile feel, and the upper circuit contact bounces back. Then, the circuit is broken, and the loop triggers a signal.

2.4 Adhesive separator

It is between the upper circuit and the lower circuit layer. And it functions as a seal and connection. In general, we use high quality PET double-sided tape, which thickness ranges from 0.05 MM to 0.2 MM. When selecting this layer material, we should fully consider the product features. Including the overall thickness, insulation, the hand feeling of circuit keys package and sealing.

2.5 Lower circuit layer

This layer usually uses a good performance polyester film (PET) as a carrier for the switching circuit pattern. Membrane switch keypad suppliers use a special process to screen conductive silver paste and conductive inks. So, the custom membrane switch will have electrical conductivity. In general, its thickness is within 0.05MM–0.175MM, and the most common is 0.125MM PET. Because it has good insulation, heat resistance, high mechanical strength, transparency, and air tightness. Especially, it has flexural resistance and high elasticity is the ideal material of making a custom membrane keypad.

Of course, according to customer needs, we also use FPC or PCB board to design and manufacture this layer. In order to increase some display effects on user interfaces, we can add LED light and SMT components. Furthermore, the fiber optic can be used under the user interface to provide visual feedback. What’s more, sometimes, the lower circuit layer may have terminals to connect the machine interfaces.

2.6 Rear adhesive layer

The use of the rear adhesive layer is closely related to the material which pastes with the keypad. Commonly, membrane switch keypad suppliers use ordinary double sides tape, 3M glue, waterproof glue and so on.

I worked in HuaiSong, which has been providing membrane switches, graphic overlays, siicone keypads, SMT since 2010. We have ISO9001:2015 and ISO14001:2015 Certification, make high quality and environmental friendly products.