The panel layer is usually made of fine patterns and characters on the screen printing of colorless transparent sheets such as PET and PC less than 0.25mm. The main function of the panel layer is to mark and press buttons, so the selected materials must have high transparency, high ink adhesion, high elasticity, high toughness, and other characteristics.
The surface of the rubber:
The most important role of the surface adhesive is to connect the panel layer and the circuit layer closely to achieve the sealing and connection effect. The thickness of this layer is generally required to be between 0.05– 0.15mm, with high viscosity and anti-aging;In the production, the general choice of special film switch double-sided adhesive, some of the film switch requirements can be waterproof high temperature, so the adhesive must be used according to the needs of different properties of the material.
Control the upper and lower layers of the circuit:
This layer is made of polyester film (PET) with good performance as the carrier of switch circuit graphics, and conductive silver paste and conductive carbon paste are printed on it with a special process to make it conductive. The thickness is generally within 0.05–0.175MM, and the most common is 0.125MM PET.
It is located between the upper circuit and the lower circuit layer and plays the role of sealing and connection. Generally, PET double-sided adhesive tape is used with thickness ranging from 0.05 to 0.2MM. When choosing the material of this layer, the overall thickness, insulation, handle and sealing of the circuit key package should be fully considered.
On the back of the rubber:
Back adhesive is closely related to the film switch and what kind of material phase paste, the common double-sided adhesive, 3M adhesive, waterproof adhesive, etc.