Analysis of the surface treatment process of PCB board

Analysis of the surface treatment process of PCB board, its advantages and disadvantages and applicable scenarios

With the continuous development of electronic science and technology, PCB technology has also undergone tremendous changes, and the manufacturing process also needs to be improved.

Colleagues in each industry have gradually improved the process requirements of PCB circuit boards. For example, in the circuit boards of mobile phones and computers, gold and copper are used, which makes the advantages and disadvantages of circuit boards gradually become easier to distinguish.

Take everyone to understand the surface technology of the PCB board, compare the advantages and disadvantages and applicable scenarios of different PCB board surface treatment processes.

Simply looking from the outside, the outer layer of the circuit board mainly has three colors: gold, silver, and light red. According to the price, gold is the most expensive, silver is the second, and light red is the cheapest. From the color, it is easy to judge whether the hardware manufacturers are cutting corners. But the circuit inside the circuit board is mainly pure copper, that is, bare copper board.

1. Bare copper

The advantages and disadvantages are obvious

Advantages: low cost, smooth surface, good weldability (without being oxidized)

Disadvantages: It is easily affected by acid and humidity, and cannot be left for a long time. It needs to be used within 2 hours after unpacking. Because copper is easily oxidized when exposed to air, it cannot be used for double-sided boards. It has been oxidized. If there are test points, solder paste must be added to prevent oxidation, otherwise it will not be able to make good contact with the probe later.

Pure copper is easily oxidized if exposed to air. The outer layer must have the above protective layer. And some people think that the gold color is copper, which is a wrong idea. Because that is the protective layer over copper. Therefore, a large area of gold plating is required on the circuit board. That is the sinking gold craft.

2. Gold plate

Gold is real gold. Even if only a very thin layer is applied. It has already accounted for nearly 10% of the cost of circuit boards. In Shenzhen, there are many businessmen who specialize in acquiring old circuit boards, and the gold is washed out by certain means, which is a good income.

The use of gold as a coating is for welding convenience and corrosion protection. Even the gold fingers of memory sticks that have been used for several years are still shining as before. If they used copper, aluminum and iron, they have now been embroidered into a pile of waste products.

Gold-plated layers are widely used in circuit board component pads, gold fingers, and connector shrapnel. If you find that the circuit board is actually silver, then needless to say. It must be that the manufacturer cut corners and did not use materials properly. Used other metals to fool customers. Most of the most widely used motherboards for mobile phone circuit boards are gold-plated boards, sunken gold boards, computer motherboards, speakers and small digital circuit boards. Generally, they are not gold-plated boards.