Since the iPhone (Apple) era, 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. A slight deviation in the process will cause an increase in the defect rate of the PCB board due to color difference. So, what should we do?
Resentment: First of all, I have never encountered the problem of color difference that the circuit board proofing manufacturer told me. Chromatic aberration is not an item for customer assessment, 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, try to be as black as possible, and there are many other colors. For example green has:
Statement 2: Because the circuit traces of the black pcb circuit board are difficult to identify, it will increase the difficulty of later maintenance and debugging. Generally, if there is no brand with strong RD (R&D) designers and a strong maintenance team, it will not be easy to use black pcb Yes, this is why only a few high-end brands (such as ASUS) use black pcb boards in their high-end series—it can be said that the use of black pcb proofing is a sign of a brand's confidence in RD design and post-maintenance teams. From the side view , It is also a reflection of the confidence of circuit board manufacturers in their own strength.
Resentment: This statement is simply serious nonsense, and it seems to make sense.
First of all, Debug has blueprints, self-developed circuits, when debugging, you can look at the blueprints if you can't see clearly. Besides, whoever finds a signal depends entirely on the pcb board to find it.
Statement 3: To prevent plagiarism
Resentment: Brother, have you ever made a 4-layer, 6-layer, 8-layer, 10-layer....
Statement 4: Increase maintenance costs. Although the black pcb board does not mean that it must be a high-end product, but the use of a black pcb board reflects a manufacturer's confidence in its own products, and also reflects its cautious workmanship. Because the subsequent maintenance of products produced by black pcb boards is more difficult, if the quality is not up to standard, the subsequent maintenance costs will be very high. Therefore, products using black PCB boards are generally self-designed, and only 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 stricter, which can improve the utilization rate of good products of circuit boards.
Resentment: People who design circuits will not be cheap. Will not increase maintenance costs just to pretend to be cool. Maintenance with tools, not by eyes. I can see with my eyes where there is a problem with the circuit, so I sent it to Zhichuang Circuit Board Factory as a research object. The masters in the general electronics market are all modular replacement parts. Even if the chip is replaced, they will not observe the pcb wiring, mainly relying on tools and experience.
Just imagine: Apple maintenance workers in the electronics market, do they use the naked eye to look for the wires to find the pads. Are you sure about the green board, and you can find the line with the naked eye?
Statement 5: Good heat dissipation? Why use black oil is actually because black oil dissipates heat better than any other color oil. Everyone only knows that black objects absorb heat better. In fact, from the 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 of black. Refrigerator condensers, compressors, etc. are all black, which is the reason.
Resentment: Black is good for heat dissipation, but your PCB itself is so hot, and your design is enough.
According to the classic radiation law of physics - the radiation ability of all objects is equal to its absorption ability, and the absorption ability of non-black bodies is always smaller than that of black bodies at the same temperature. Therefore, comparing the heat dissipation capabilities of non-black and black objects under the same conditions, the heat dissipation of black objects is significantly faster, and the darker the color, the higher the emissivity and absorption rate of heat energy.
Finally, black absorbs all the light, and naturally absorbs more heat 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 equal heat , so that it can absorb more heat.
If your pcb needs to dissipate heat, you will use bright copper, and you will also use aluminum substrates, and the copper substrates are not black. In fact color is negligible compared to other dimensional measures. If the MOSFET needs good heat dissipation, the pad on the front side will be enlarged, and the solder resist layer on the back side will be removed.
1. The cost of black PCB is indeed more expensive than that of green. Some manufacturers charge for color. There are two reasons:
Reason 1. There are many users who choose green, so green is relatively cheap, so some fees need to be charged for other colors.
Reason 2. All the boards with batch and black solder mask color need to be tested! Because it is difficult to find the problem by visually inspecting the processing errors of the surface layer.
During the assembly process of pcb (pcb assembly), there is visual inspection (visual inspection). Human vision is very prone to visual fatigue for yellow, red and black. Let you test 6,000 black pcbas on the Foxconn assembly line 12 hours a day.
2. Because we are used to seeing green pcb boards, it was also because of a coincidence that we chose green paint as the material for pcb solder mask. But if 90% of the PCBs in the world are black, it is estimated that people will think that black is ugly, but green is taller.
It is estimated that Jobs had such a strong obsessive-compulsive disorder that he liked the strong contrast between black and bright gold pads, so he chose black uniformly. In fact, the iPod has always been green. Using black pcb has nothing to do with high-end, it is just a style of the designer.
These blade servers of China Telecom are priced at 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 point, you can forcefully make a reason.
In addition, Hard Ten is about to launch a "completely open source" open source hardware crowdfunding, which is also the choice of black. Because, commonly known as the black pcb convention has become synonymous with quality. Chip solder joints are bright white with silver tin and printed boards and chip packages are jet black
