2*2 matrix 4 buttons poly dome membrane switch
Membrane keypads are the most widely used form of switch technology today. We offer reliability, long life and design flexibility. Conductive rubber switches and keypads were originally developed the electronics industry to meet the increasing demand for inexpensive momentary switches. Conductive rubber keypads became desirable because they look and feel like traditional push-button style switches, but do not have their inherent disadvantages.
1.Membrane keypads panel layer
The panel layer is generally made of exquisite patterns and text on the screen printing of PET, PC and other colorless light-transmissive sheets that are less than 0.25MM. Since the main role of the panel layer is to function as a logo and buttons, the selected material must have high transparency , High ink adhesion, high elasticity, high toughness and so on.
The most important role of the adhesive is to closely connect the panel layer and the circuit layer to achieve the effect of sealing and connection. This layer generally requires a thickness of 0.05 — 0.15MM, with high strength and anti-aging properties; in production In general, special membrane switch double-sided adhesive is generally used. Some membrane switches require waterproof and high temperature resistance. Therefore, the surface adhesive must also use different materials according to needs.
3. Membrane keypads control circuit upper and lower layers
This layer uses a polyester film (PET) with good performance as the carrier of the switch circuit pattern, and a conductive silver paste and a conductive carbon paste are silk-screened on it by a special process to make it conductive. Its thickness is generally 0.05– Within 0.175MM, the most common is to use 0.125MM PET.
It is between the upper circuit and the lower circuit layer and plays the role of sealing and connection. Generally, PET double-sided adhesive is used, and its thickness ranges from 0.05 to 0.2MM; when selecting the material of this layer, the overall product should be fully considered. Thickness, insulation, circuit button package feel and sealing.
5.Membrane keypads back adhesive layer
The use of adhesive is closely related to the material with which the membrane switch is pasted. Common double-sided adhesives, 3M adhesives, and waterproof adhesives are more commonly used.