Label：Screen Printing, Electrostatic Shielding, Flexible Circuit
Nov 17, 202014000
Since the birth of the membrane switch, it has experienced several technological innovations. JRPanel would like to talk about the development trend of membrane switch technology today.
Multifunctional integrated membrane switch
The traditional membrane switch only has the function of switching on and off, and has a single function. According to the needs of instruments and meters, electronic components (including RC components, inductance components, light-emitting devices, sound-emitting devices, etc.) have been installed into membrane switches, and new light storage and fluorescent inks have been applied. The membrane switch integrates multiple functions such as switches, decorations, regular panel notes, luminous displays, and sound prompts, and realizes part of the circuit board functions.
Screen printing isolation layer
The structure of the membrane switch requires that the two circuits must have an isolation layer, which plays the role of separating the circuit, controlling the switch stroke, and conducting airflow. The traditional isolation layer uses an insulating membrane. Currently, the new process of screen printing dot-shaped rubber particles instead of the isolation layer is mostly used, that is, between the upper and lower circuits, a layer of viscous latex with high tension and high elasticity is screen printed to isolate the upper and lower circuits . This process not only simplifies the process, but also has its unique advantages in the application of transparent circuits.
Electrostatic shielding technology
The silicone switch factory stated that traditional membrane switches have replaced mechanical keyboards and are widely used in electromechanical instruments and meters. On this basis, a layer of conductive metal material (usually a mixture of silver paste and carbon paste) is printed on the panel of the membrane switch and connected to the chassis, which can effectively ground the electrostatic charge on the surface of the plastic membrane through the chassis. It has electrostatic shielding performance and is applied to instruments and meters in flammable and explosive environments such as underground coal mines.
Flexible circuit board technology
With the application of high-performance flexible solder mask inks, the technology of flexible printed circuit boards based on polyimide copper-clad foil and polyester copper-clad foil as the base material has become more mature, making the performance of thin-membrane key technology a substantial leap. In traditional membrane switches, the metal material of the membrane circuit is mainly silver paste, which is polymerized on the membrane by screen printing technology. The contact resistance of the circuit is relatively large, generally 0.5 milli-ohm/square (resistance per unit square). The connection between the lead wire and the connector adopts riveting or plug-in connection. The membrane switch adopts the combination of a membrane panel and a flexible circuit board, and replaces the traditional membrane circuit with a single-sided and double-sided flexible circuit board as the membrane switch circuit, which can greatly reduce the contact resistance. The connection of the rear circuit can be riveted, plugged, welding greatly improves the reliability of the membrane switches.