PCB News - Basic knowledge of PCB circuit board

1. What is a PCB circuit board

The structure of PCB circuit boards and printed circuit boards can generally be divided into two parts, namely the base material part (generally using engineering plastics with good heat insulation and insulation and not easy to bend) and the circuit layer part. The conductive medium used in the circuit layer part is Copper foil, also called copper skin, covers the two outer surfaces of the entire base layer. This layer is the core part of the entire PCB. After the designer has designed the circuit through various design software, a special machine will engrave the copper foil layer according to the design drawing, and the unnecessary parts will be engraved to form a complete circuit. At the same time, various components (Chips, resistors, capacitors, inductors, plugs, fuses, etc.) are welded or patched on the PCB to make it together with the copper foil layer to form a complete circuit.

2. What is the layering of PCB circuit boards

Generally speaking, the PCB circuit board has two upper and lower layers, which are located on the upper and lower surfaces of the substrate. The circuits on the upper and lower layers are different. This is because of the needs of circuit design and safety considerations, such as the power supply circuit and the grounding part. The circuit is generally separated from the circuit layer on an unconnected layer. And in some special times, for some complex circuits, it may not be possible to line up all the lines on one layer or the lines under a layer can not realize the control of the circuit (for example, some components have very fine impedance requirements), At this time, a multi-layer PCB is needed.Multi-layer PCBs actually stack single-layer PCBs together, so that different circuits can be designed on different circuit layers to meet the needs of complex circuits. Generally, the number of layers of PCBs is divided into 2 layers and 4 layers., 6 layers, 8 layers, 10 layers and so on.

3. How to distinguish the layering of PCB circuit boards

It is relatively easy to distinguish whether the PCB circuit board is multi-layered. Just look at the light and observe whether the parts that are not covered by copper on the upper and lower surfaces are translucent. Because if there are other circuit layers in the middle, the transparency will naturally be very low. It is possible for some senior developers to distinguish how many layers of a PCB are by the naked eye, but it is difficult to accurately determine how many layers are.

4. The color difference of PCB circuit board

There is no uniform standard for the color of PCB circuit boards, so there is no saying that other colors of PCB must be better than green. But in PCB design, green board is the most commonly used because the green surface does not look dazzling, and some In order to highlight their own design, manufacturers often change the color of PCB on some relatively high-quality products, such as purple ink PCB, yellow ink PCB, black ink PCB, etc. to achieve distinctive visual effects. Maybe this is it. It is the source of the feeling that "other colors are better than green".

5. How to choose PCB circuit board

First of all, the PCB is specified in several layers according to the customer’s industry needs. For example, if a customer is a circuit board for a motherboard graphics card, it is only a small part of the purchase, because all the boards are before mass production. It will definitely undergo reliability tests. Even if a 4-layer board or even a 2-layer board is used, the product performance requirements can definitely be achieved, and because of the several layers of PCB boards, most businesses will not understand, so this aspect is in The actual purchase is of little significance, so you don't need to be too restrictive.