PCB News - Take you to understand the difference between black oil and green oil on pcb boards

Take you to understand the difference between black oil and green oil on PCB boards

Before discussing the difference between black oil and green oil on PCB boards, let's first understand why PCB boards should be coated with solder resist (solder resist paint)?

Anyone who knows the circuit board knows that the front and back sides of the PCB board are copper layers. No matter what method is used to make the copper layer, a smooth and unprotected surface will be obtained in the end. Regarding copper, friends who know some chemistry should know that although the chemical properties of copper are not as active as aluminum, iron, magnesium and other metals, in the presence of water, pure copper and oxygen contact each other, which can easily cause copper to oxidize. . On the other hand, because the thickness of the copper layer in the PCB is relatively thin, the oxidized copper will be a poor conductor of electricity, which will seriously damage the entire electrical performance of the PCB.

In order to protect the surface of the PCB and prevent the copper from being oxidized, engineers have researched and invented a solder resist paint. Brushing this solder resist paint on the surface of the PCB will form a protective layer of a certain thickness to block the contact between copper and air. This protective layer This is what is now called the solder mask, and the solder mask is the solder mask oil.

There are many colors of solder mask, why is green oil commonly used on circuit boards?

Green is generally less irritating to the eyes, PCB production and maintenance personnel are not easy to cause eye fatigue when working for a long time, and it does little damage to the eyes. On the other hand, green is the color commonly used by PCB manufacturers, and green paint is also the most stocked by the factory, which is cheap and relatively cost-effective.

We are talking about black oil PCB, in fact, there is no difference in performance from butter PCB, blue oil PCB and other PCBs with different colors. The only difference is that the color of the solder mask is different at the end.

Many people think that black PCB is very high-end, because many manufacturers like to use black PCB to make high-end products. This is why? The black PCB surface traces are almost completely covered, and it is difficult to repair later. It is a kind of solder mask color that is inconvenient to manufacture and produce. This also reflects the superb technology of some manufacturers who use black PCB to produce products. It is a kind of technical confidence. And black PCB is the most difficult for holes, and the yield rate is lower than other colors of PCB boards, but the price of black PCB is a bit more expensive than other colors.

Summary: The difference between black oil and green oil on PCB board is only the difference in color, which has no effect on performance. It is the product that gives the color meaning, not the color that gives the product meaning.