Since the era of iPhone (Apple), almost all mobile phones have used black pcb circuit boards. What prompted this change? What is so special about the black pcb circuit board?
Statement 1. In the process of washing PCB circuit boards, black PCB boards are the most likely to cause chromatic aberration. If the raw materials used by PCB circuit board manufacturers and their own craftsmanship are slightly deviated, the defective rate of PCB boards will increase due to chromatic aberration. high. So, what should we do?
Explanation 1. First of all, I have never encountered the problem of chromatic aberration that the circuit board proofing manufacturer told me. The chromatic aberration is not an item assessed by customers, and it is difficult to quantify. In addition, compared with black, other colors are more likely to cause chromatic aberration. Because there is one kind of black, it is enough to be as black as possible, and there are many other colors.
Statement 2. Because the circuit traces of the black PCB circuit board are difficult to identify, it will increase the difficulty of post-maintenance and Debugging. Generally, if there is no brand with strong RD (R&D) designers and a strong maintenance team, it is not easy to use black PCB. Yes, this is why only a few high-end brands (such as ASUS) use black PCB boards for their high-end series - it can be said that the use of black PCB proofing is a sign of a brand's confidence in the RD design and post-maintenance team. It is also a reflection of the confidence of circuit board manufacturers in their own strength.
Explanation 2. This statement is just serious nonsense, and it seems to make sense.
First of all, Debug has drawings, the circuit developed by yourself, when debugging, you can see the drawings if you can't see clearly. Besides, whoever is looking for a signal relies on the PCB board to find it.
Argument 3, in order to prevent plagiarism
Explanation 3. Have you ever made a 4-layer board, a 6-layer board, an 8-layer board, a 10-layer board...a 20-layer board? Even if it is made green, do your eyes see the line? Do you know a multimeter?
Argument 4, increase maintenance costs. Although black PCB boards are not necessarily high-end products, the use of black PCB boards reflects a manufacturer's confidence in their products and their own workmanship. Because the follow-up maintenance of products produced by black PCB boards is relatively difficult, if the quality is not up to standard, the follow-up maintenance costs will be very large. Therefore, products using black PCB boards are generally self-designed, and high-end products that are confident in product quality will be used. In order to reduce maintenance costs, the quality control of products using black PCB boards will be more stringent, which can improve the utilization rate of good products of printed circuit boards.
Explanation 4. The person who designs the circuit will not be cheap. Will not increase maintenance costs just to pretend. Maintenance has tools, not by eyes. If you can see where there is a problem with the circuit, you can send it to Zhichuang Circuit Board Factory as a research object. In general, the masters in the electronic market are all modular replacements. Even if the chip is replaced, they will not observe the PCB traces, mainly relying on tools and experience.
Just think: Apple repairmen in the electronics market, do they look for the pads by looking at the wires with the naked eye. Do you confirm the green board and find the line with the naked eye?
Statement 5. Is the heat dissipation good? The reason why black oil is used is because black oil dissipates heat better than any other color oil. Everyone only knows that black objects absorb heat better. In fact, from the theory of heat radiation, heat dissipation is the same as heat absorption. The darker the color and the rougher the surface, the better the heat radiation, so many heat sinks are made black. Refrigerator condensers, compressors, etc. are all black, that's why.
Explanation 5. Black is good for heat dissipation, but your PCB itself is so hot, your design is enough.
According to the classical radiation law of physics - the radiation power of all objects is equal to its absorption power, and the absorption power of a non-black body is always smaller than that of a black body at the same temperature. Therefore, when comparing the heat dissipation capabilities of non-black and black objects under the same conditions, black objects dissipate heat significantly faster, and the darker the color, the higher the emissivity and absorption rate of thermal energy.
In the end, black absorbs all the light, and naturally absorbs heat more than white under the same conditions. However, according to the classical radiation law, a black object absorbs heat faster and dissipates heat faster, so when it absorbs too much heat, it will dissipate the same amount of heat. This allows it to absorb more heat.
If your PCB needs to dissipate heat, it will brighten copper and use aluminum substrates. These copper substrates are not black. In fact, color is insignificant compared to other measures of dimension. If the MOSFET needs to have good heat dissipation, the pad on the front will be enlarged and the solder mask on the back will be removed.
1. The cost of black PCB is indeed more expensive than the cost of green. Some manufacturers will charge a fee for the color. There are two reasons:
a. There are more users who choose green, so green is relatively cheap, so other colors need to charge some fees.
b. All boards with black solder mask color need to be tested in batches! It is more difficult to find the problem because of the processing errors of the surface layer when inspected with the naked eye.
In the PCB assembly process, there is a visual inspection (visual inspection). People's vision is very easy to produce visual fatigue for yellow, red and black. Let you inspect 6000 pieces of black pcba on the Foxconn assembly line 12 hours a day. It is said that there is no visual inspection of the Apple production line (to be verified), and it should mainly rely on automatic optical inspection machines (AOI) and non-destructive flaw detectors (X-Ray).
2. Because we are used to seeing green PCB boards, it was also a coincidence that we chose green paint as the material for PCB solder resist. But if 90% of PCBs in the world are black, it is estimated that people will think that black is ugly, and green is taller.
In fact, the iPod has always been green. Using a black PCB has nothing to do with high-end, just a style of the designer. These telecommunications blade servers cost tens of thousands or even hundreds of thousands, and they are often green.
3. The black PCB is not easy to be found inside the product. This is a fact. If you are particularly concerned about this, let’s try to make an excuse.
In addition, the "completely open source" open source hardware crowdfunding that Hard Ten is about to launch is also black. Because the black PCB convention has become synonymous with quality. The chip solder joints are silver tin bright white and the printing board and chip package are jet black.
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