When we design the PCB, we will send it to the PCB board factory for online production through PCB pricing, and then there will be a series of subsequent welding, assembly and so on. However, with the increasingly fierce market competitiveness, the price of raw materials for PCB has also increased with the supply and demand of the market. PCB manufacturers have to reduce material costs in order to make their own competitiveness in the market. The cost of the process keeps itself competitive and attracts customers with ultra-low price. Therefore, the inevitable performance, density and quality of the PCB produced in the future will be greatly reduced. When welding, there will be many problems, and the reliability of the product itself will of course be Will receive the suspicion of the majority of users.
Therefore, when we face the PCB circuit boards produced by various board manufacturers in the market, how to judge naturally becomes a top priority. There are two ways to judge whether the circuit board is good or bad. One is to pass the appearance, and the other is to judge according to the quality of the board itself.
By discriminating the appearance of the PCB circuit board, there are usually three ways to discriminate
The color and luster of the board, the outside of the PCB circuit board is wrapped by ink of various colors, the ink can play the role of insulation protection on the line. If the surface gloss is dim, the ink is thin and the circuit board itself is not Ok.
The size of the board and the accuracy of the board thickness, the dimensional accuracy of the board and the tolerance of the board thickness determine the quality of the production.
For a circuit board with many soldered parts, observe the sharpness and microscopic fineness of the surface package gap. In these places, many soldering operations are performed, and the easier it is to distinguish, the better the fabrication.
For the other part of the PCB, the quality specifications are:
1. After the components are installed, the electrical performance is not abnormal, then the surface circuit board is ok.
2. The copper surface is not easily oxidized, affecting the speed of placement, and the oxidation rate is too fast, which may cause problems soon.
3. When the welding encounters high temperature, the ink will not fall, and the copper will not fall.
4. Whether the actual pitch and line width of the fabricated PCB circuit board are made according to the document, which affects the heating, open circuit and open circuit of the line.
5. Whether the war page of the board is too large, often encounters a high temperature environment during re-production, and a certain degree of war page is caused by stress deformation. Serious deformation will seriously affect the placement welding.
6. Whether the PCB circuit board can reach the standard under high temperature and high pressure environment, whether its own raw material can reach the TG value is also an important factor for judgment.
In the PCB design process, if the risk can be predicted and circumvented in advance, the success rate of PCB design will be greatly improved. Many companies have indicators of PCB design success rates when evaluating projects.
The key to improving the success rate is signal integrity design. Currently, there are many product solutions for electronic system design, and chip manufacturers have done it, including what chips are used, how to build peripheral circuits, and so on. In many cases, hardware engineers usually do not need to consider the circuit principle, just need to make the PCB itself.
However, in the PCB design process, many companies have encountered difficulties, that is, the PCB design is unstable or not working properly. For large enterprises, many chip manufacturers will provide technical support to guide PCB design. However, some SMEs have difficulty obtaining support in this regard. Therefore, we have to find a way to do it ourselves, so we have a lot of problems, we may need to play multiple versions and debug for a long time. In fact, if you understand how the system is designed, you can avoid these situations. Next, let's talk about three techniques for reducing the risk of PCB design.
First, it is best to consider signal integrity issues during the system planning phase so that the entire system can be built and can signals be properly transferred from one PCB to another. This will be evaluated early and it is not difficult to assess this. Some signal integrity can be understood through simple software operations.
Secondly, in the PCB design process, the simulation software is used to evaluate the specific traces to see if the signal quality can meet the requirements. The simulation process itself is very simple. The key is to understand the principle of signal integrity and guide.
Third, in the PCB manufacturing process, it is necessary to conduct risk control. There are many problems. At present, there is no way to solve the simulation software, and the designer must control it artificially. The key to this step is to understand where risks exist, how to avoid them, and what is needed for signal integrity.
If you master these three points in the PCB design process, you will greatly reduce the risk of PCB design. The probability of making a mistake after playing back is much smaller, and debugging is relatively easy.