For a long time, circuit board buyers have always been confused about the color of the circuit board, and do not know what color circuit board is of high quality. How does the color of a circuit board affect its performance?
From the outside, the outer layer of the circuit board mainly has three colors: gold, silver, light red. Gold is more expensive, silver is cheaper, and light red is cheaper.
It can be seen from the color that the hardware manufacturers have cut corners. In addition, the lines inside the circuit board are mainly pure copper, which is easy to be oxidized if exposed to the air, and the outer layer must have the above protective layer. Some people say that the golden color is copper, which is not true.
Large area gold plating on circuit boards
Gold is expensive, it is real gold. Although only a thin layer, it also accounts for nearly 10% of the cost of the circuit board. Some places along the coast of Guangdong and Fujian specialize in purchasing waste circuit boards and stripping off the gold, and the profits are considerable.
Gold is used for two purposes, one is to facilitate welding, and the other is to prevent corrosion.
For example, the golden fingers of the memory sticks 8 years ago are still shiny. If they are replaced with copper, aluminum, or iron, they will be rusted and unusable.
Gold plating is widely used in the component pads, fingers, connector shrapnel and other positions of the circuit board.
The silver board is called spray tin board. Spraying a layer of tin on the outer layer of the copper circuit can also help with soldering. But it cannot provide long-term contact reliability like gold.
The tin-sprayed board has no effect on the components that have been soldered, but the reliability is not enough for the pads exposed to the air for a long time, such as ground pads, pin sockets, etc. Long-term use is easy to oxidize and rust, resulting in poor contact.
The circuit boards of small digital products, without exception, are spray tin boards. There is only one reason: cheap.
OSP, organic flux film. Because it is organic, not metal, it is cheaper than the tin spraying process.
The best function of this organic film is to ensure that the inner copper foil will not be oxidized before welding. When soldering - heating, the film will volatilize
Lost. Soldering can be used to solder copper wires and components together.
However, it is not resistant to corrosion. An OSP circuit board cannot be soldered after being exposed to the air for ten days.
Many computer motherboards use the OSP process. Because the area of the circuit board is too large, gold plating cannot be used.
