FPC structure - single panel and single copper double fabrICation

FPC structure - single panel and single copper double fabrication

FPC (flexible printed circuit board) can be divided into single layer, double layer, multi layer and other soft circuit boards according to its structure and complexity, and there is also a composite soft and hard board (Regid Flex) that combines both soft and hard boards

Traditional single side flexible circuit

Single layer soft board is the SIMplest application of soft circuit boards, and it is also the most widely used design. Because of its simple structure, it is also the cheapest soft circuit board. The manufacturing process is basically completed by using copper foil with substrate, then removing the excess copper foil by etching, and then printing solder resist on it or coating it with a cover film.

The places that need to contact with the outside world are not printed with solder proof ink or insulated. They are usually the places that need to be connected with the connector or hot bar welding. These parts are directly exposed to the air because they are not protected. In order to prevent oxidation, they also need to be connected subsequently, so they will be treated with a layer of solder or electrogilding depending on the assembly design. Generally, the design that needs to be connected to the connector adopts electrogilding, because the thickness is relatively controllable and uniform.

Double Access Flexible Circuit

That is, a single copper layer is used to make a soft plate that can conduct electricity on both sides. Usually, this kind of soft plate is designed to achieve the purpose of assembly, which is commonly used in the hot bar process. This kind of soft board can generally use double-layer soft board to achieve the same assembly purpose, but the more layers of copper foil, the thicker the soft board will be, and the harder it will be to bend. If it is necessary to withstand multiple activities, this design can greatly increase its reliability without breaking.

Basically, there are many ways to achieve the production of such single-layer and double made soft boards, such as punching or window first, then pressing, chEMIcal etching substrate, mechanical cutting, laser drilling, plaSMA etching, etc.

Pressing after punching is one of the most common methods in this kind of products, because this method is the simplest. This method is to punch the required holes on the substrate first, and then combine with the copper sheet. After the line is etched, take a piece of covering layer with holes and cover it on the line, and then press it. Finally, the exposed lines are treated with metal surface.

The circuit board manufacturer and circuit board designer will explain the FPC structure - single panel and single copper double fabrication.