Membrane keyboards are an example of the category of membrane switches. Membrane switches with many buttons and neatly arranged are commonly referred to as membrane keyboards. Membrane keyboard is a kind of keyboard that integrates decoration and functionality, which is popular internationally in recent years. It consists of four parts: panel, upper circuit, isolation layer, and lower circuit. The membrane keyboard is beautiful and novel in appearance, small in size, light in weight and strong in airtightness. It has the characteristics of moisture-proof, dust-proof, oil-proof, acid and alkali resistance, shock resistance and long service life. Widely used in medical equipment, computer control, digital machine tools, electronic scales, post and telecommunications, copiers, refrigerators, microwave ovens, electric fans, washing machines, remote controls, electronic game consoles and other fields.
The panel layer is generally made of exquisite patterns and text printed on colorless transparent sheet materials such as PET, PC, etc. less than 0.25MM. Because the main function of the panel layer is to play the role of identification and keys, the selected material must have high transparency , High ink adhesion, high elasticity, high toughness and other characteristics.
The main function of the surface glue is to connect the panel layer and the circuit layer closely to achieve the effect of sealing and connection. The thickness of this layer is generally required to be between 0.05 and 0.15 mm, with high viscosity and anti-aging properties; in production In general, special membrane switch double-sided adhesive is used, and some membrane switches require waterproof and high temperature resistance. Therefore, the surface adhesive must also use materials of different properties according to needs.
Control circuit upper and lower layers
This layer uses polyester film (PET) with good performance as the carrier of the switch circuit pattern, and uses a special process to silk-screen conductive silver paste and conductive carbon paste to make it conductive, and its thickness is generally 0.05-- Within 0.175MM, 0.125MM PET is the most common.
It is located between the upper circuit and the lower circuit layer and functions as a seal and connection. Generally, PET double-sided tape is used, and its thickness ranges from 0.05 to 0.2MM; when choosing this layer of material, the overall product should be fully considered Thickness, insulation, feel and airtightness of the circuit key pack.
The use of adhesive is closely related to the material of the membrane switch. Common double-sided adhesives, 3M adhesives, waterproof adhesives, etc. are commonly used.