PCB Tech - Interesting difference between PCB and FPC

PCB, the so-called printed circuit board, is usually called hard board. It is the support body of electronic components, which is a very important electronic component. PCB generally uses FR4 as base material, also known as hard board, which can not be bent and flexed. PCB is generally used in some places where there is no need to bend, such as computer motherboard, mobile phone motherboard, etc.

FPC, in fact, belongs to a kind of PCB, but it is quite different from the traditional printed circuit board. It is called flexible board, the full name is flexure circuit board. FPC generally uses Pi as base material, which is flexible material and can be bent and flexed at will. FPC generally needs to repeat the flexure and link some small parts, but now it is more than that. At present, smart phones are trying to prevent bending, which requires the use of FPC as a key technology.

In fact, FPC is not only a flexible circuit board, but also an important design method for connecting three-dimensional circuit structure. With other electronic product design, this structure can build a variety of different applications. Therefore, from this point of view, FPC and PCB are very different.

For PCB, unless the circuit is made into three-dimensional form by filling film glue, the circuit board is generally planar. Therefore, in order to make full use of the three-dimensional space, FPC is a good solution. In terms of hard board, the common space extension scheme is to use the slot and interface card. However, as long as the FPC is designed as an adapter, it can make similar structure, and has more flexibility in the directional design. With one FPC connected, two hard boards can be connected into a group of parallel circuit system, and can also be turned into any angle to adapt to different product shape design.

Of course, FPC can use terminal connection mode for line connection, but soft and hard board can also be used to avoid these connection mechanisms. A single FPC can use layout to configure many hard boards and connect them. This method reduces the interference of connector and terminal, and can improve the signal quality and product reliability. The figure shows the soft and hard board constructed by multi PCB and FPC.