Silver circuit (Silver paste line)
PCB Introduction
Flexible membrane keyboard is a typical form of membrane keyboard. This kind of membrane keyboard is called flexible because its mask layer, isolation layer, and circuit layer are all composed of software films with different properties.
The circuit layer of the flexible membrane keyboard uses polyester film (PET) with good electrical properties as the carrier of the switch circuit pattern. Due to the influence of the properties of the polyester film, the film keyboard has good insulation, heat resistance, flexural resistance and high resilience. The graphics of the switch circuit, including the switch connection and its lead wires, are printed with low-resistance, conductive paint that cures under low-temperature conditions. Therefore, the composition of the entire membrane keyboard has a certain degree of flexibility, which is not only suitable for use on a flat body, but can also be matched with a curved body. The lead wire of the flexible membrane keyboard is integrated with the switch body itself. When making the connection of the group switch, it is gathered in a certain place of the membrane and extended outward according to the designated position and standard line distance of the design as a soft , The arbitrarily bendable and sealed lead wire is connected to the rear circuit of the whole machine.
1. Line switch The line switch is essentially the membrane switch with the panel removed. In some specific occasions, or some users who already have an indicator panel, they don’t need a complete membrane switch, but only the bottom line switch. .
2. Double-sided circuits Double-sided circuits can be divided into two types. One type is printed with wires on both sides. A small hole of about 0.5mm is opened at the connection end of the wire, and conductive material is poured into this hole to make the front face. It is connected with the reverse circuit to achieve the required function; the other structure is mainly that the front printed circuit is in the X axis direction, the back circuit is in the Y axis direction, and the two circuits are not connected to each other. This kind of circuit is mainly used for e-books or other electronics. Similar products with sensing function.
For monolithic circuits with bridges, when two sets of circuits are crossed, UV insulating ink should be screen printed between them. This program will increase the number of screen printings and the cost will also increase. The designer should try to avoid crossing the lines when designing the circuit again.
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