PCB News - Single, double, multi-layer circuit boards

Single, double, multi-layer circuit boards

Printed circuit boards {Printed circuit boards}, also known as printed circuit boards, are providers of electrical connections for electronic components.
Printed circuit boards are often represented by "PCB", but cannot be called "PCB boards".
Its development has a history of more than 100 years; its design is mainly layout design; the main advantage of using circuit boards is to greatly reduce wiring and assembly errors, and improve the level of automation and production labor.
According to the number of circuit boards, it can be divided into single-sided boards, double-sided boards, four-layer boards, six-layer boards and other multilayer circuit boards.
Since the printed circuit board is not a general terminal product, the definition of the name is slightly confusing. For example, the motherboard for personal computers is called the motherboard, and cannot be directly called the circuit board. Although there are circuit boards in the motherboard, They are not the same, so when evaluating the industry, the two are related but cannot be said to be the same. Another example: because there are integrated circuit components mounted on the circuit board, the news media call it an IC board, but in fact it is not equivalent to a printed circuit board. We usually say that the printed circuit board refers to the bare board-that is, the circuit board without upper components.

According to the general distribution of printed circuits, printed circuit boards can be divided into single-sided, double-sided, and multilayer circuit boards.

The single-sided board is on a 0.2-5mm thick insulating substrate, and only one surface is covered with copper foil. The printed circuit is formed on the substrate by printing and etching. The single panel is simple to manufacture and easy to assemble. It is suitable for single-channel amplifying circuits, such as radios, televisions, etc., but not suitable for occasions that require high integration density or complex circuits.

The double-sided board is on both sides of a 0.2-5mm thick insulating substrate. It is suitable for electronic products with general requirements such as electronic computers, electronic instruments and meters. Since the wiring density of the double-sided PCB circuit board is higher than that of the single board, the device volume can be reduced.

Printed circuit boards with more than 3 layers printed on insulating substrates are called multilayer circuit boards. It consists of several thin single-sided or double-sided panels, and the thickness is generally 1.2-2.5mm. In order to lead out the circuit sandwiched between the insulating substrate, the holes for mounting the components on the multilayer circuit board need to be metalized, that is, the inner surface of the small round hole is coated with a layer of metal material, and the insulating substrate is sandwiched The printed circuit connection in the middle.

Multilayer circuit board

Most of the components used in multi-layer circuit boards are SMD components, and its characteristics are:

1. Combined with multi-layer circuit boards, the whole machine is miniaturized and weight is reduced;

2. Increase the density of wiring, reduce the spacing between components, and reduce signal transmission paths;

3. The soldering points of the components are reduced, and the failure rate is greatly reduced;

4. By increasing the shielding layer, the signal distortion of the circuit is reduced;

5. The introduction of a grounded cooling layer can reduce local over-temperature and improve the reliability of the whole machine;