With the rapid development of electronic technology, the process requirements of pcb circuit boards in each industry are different. For example, there are gold and copper in the circuit boards of mobile phones and computers. Therefore, the recycling price of waste circuit boards can reach more than 30 yuan per kilogram. It is much more expensive than selling waste paper, glass bottles, and scrap iron. The editor of Intellectual Innovation pcb circuit board manufacturer will introduce to you how to understand the surface technology of pcb. From the outside, the outer layer of the circuit board mainly has three colors: gold, silver, and light red. Gold is the most expensive, silver is cheap, and light red is the cheapest.
It can be seen from the color whether the hardware manufacturer has cut corners or not,
In addition, the circuit inside the circuit board is mainly pure copper, which is easily oxidized if exposed to the air, and the outer layer must have the above-mentioned protective layer. Some people say that the golden color is copper, but that is wrong.
Gold: Large area gold plating/immersion gold on the circuit board
Gold is the most expensive and is real gold. Although only a thin layer, it also accounts for nearly 10% of the board cost. Some places along the coast of Guangdong and Fujian specialize in purchasing waste circuit boards and peeling off the gold, making considerable profits.
The reason why gold is used has two purposes, one is to facilitate welding, and the other is to prevent corrosion.
The gold finger of the 8-year-old memory stick below is still shining golden. If it were replaced with copper, aluminum, or iron, it would have rusted and become unusable.
The gold-plated layer is widely used in component pads, gold fingers, connector shrapnel and other positions of the circuit board.
If you find some boards that are all silver, you must have cut corners. The industry term is called "costdown". Most of the main boards of mobile phone circuit boards are gold-plated boards, immersion gold boards, computer motherboards, audio and small digital circuit boards are generally not gold-plated boards. The golden finger of the memory stick 8 years ago.
The exposed parts of the circuit board of Phone X are all gold-plated.
silver
Gold is gold and silver is silver?
Of course not, it's tin.
The silver board is called a tin plate. Spraying a layer of tin on the outer layer of the copper line can also help soldering. But it cannot provide long-term contact reliability like gold.
The tin plate has no effect on the soldered components, but the reliability is not enough for the pads exposed to the air for a long time, such as ground pads, spring pin sockets, etc. Long-term use is prone to oxidation and rust, resulting in poor contact.
The circuit boards of small digital products, without exception, are tin-sprayed boards. There is only one reason: cheap
Small digital products like to use tin plate
light red:
OSP, organic solder flux. Because it is organic, not metal, it is cheaper than the tin spraying process.
The only function of this layer of organic film is to ensure that the inner copper foil will not be oxidized before soldering. Once heated during welding, this layer of film will evaporate. Solder can weld the copper wire and components together.
But it is not resistant to corrosion. If an OSP circuit board is exposed to the air for ten days, it will not be able to solder components.
Many computer motherboards use the OSP process. Because the circuit board area is too large, gold plating cannot be used.
