Core issues and solutions of CB design

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Core issues and solutions of CB design [Copy link]

Printed circuit board (PCB) design refers to the process of designing schematics, laying out circuits, and producing circuit boards at the lowest possible cost. In the past, this was usually done with expensive, specialized tools, but now, with the increasing popularity of free, high-performance software tools and design models, the design speed of circuit board designers has been greatly accelerated. Although engineering designers know that a perfect design is the best way to avoid problems, this is still a waste of time and money, and it only treats the symptoms rather than the root cause. For example, if a problem is found during the electromagnetic compatibility (EMC) testing phase, it will result in a large amount of cost investment, and even the original design needs to be adjusted and remade, which will take months. Layout is the first problem that designers face. This depends on the content of the drawing. Some devices need to be placed together for logical reasons. However, it should be noted that temperature-sensitive components, such as sensors, should be placed separately from heat-generating components, including power converters. For designs with multiple power settings, 12V and 15V power converters can be placed in different locations on the board, because the heat and electronic noise they generate will affect the reliability and performance of other components and boards. The above components will also affect the electromagnetic performance of the circuit design, which is not only important for the performance and energy consumption of the board, but also for the economics of the board. Therefore, all board devices sold in Europe must obtain CE marking to prove that they will not interfere with other systems. However, this is usually only from the power supply side. There are many devices that emit noise, such as DC-DC converters and high-speed data converters. Due to defects in the board design, this noise can be captured by the channel and radiated as a small antenna, resulting in spurious noise and frequency anomalies. Far-field electromagnetic interference (EMI) can be solved by adding filters to noise points or using metal housings to shield signals. However, paying full attention to the devices on the circuit board that can release electromagnetic interference (EMI) allows the circuit board to use a cheaper housing, which effectively reduces the cost of the entire system. In the design process of the circuit board, electromagnetic interference (EMI) is indeed a factor that must be taken into account. Electromagnetic crosstalk can couple with the channel, thereby disrupting the signal into noise and affecting the overall performance of the circuit board. If the coupled noise is too high, the signal may be completely covered, so a more expensive signal amplifier must be installed to restore it to normal. However, if the signal line layout can be fully considered at the beginning of the circuit board design, the above problems can be avoided. Since the design of the circuit board will vary according to different devices, different usage locations, different heat dissipation requirements, and different electromagnetic interference (EMI) situations, design templates come in handy at this time. Capacitance is also an important issue in board design that cannot be ignored because it affects the speed of signal propagation and increases power consumption. Channels can couple with adjacent lines or cross two circuit layers vertically, thus inadvertently forming a capacitor. This problem can be solved relatively easily by reducing the length of parallel lines and adding a kink to one of the lines to cut off the coupling. However, this also requires the engineer to fully consider production design principles to ensure that the design is easy to manufacture and avoid any noise radiation caused by excessive line bends. The distance between lines may also be too close, which will create short loops between lines, especially at line bends, and metal "whiskers" will appear over time. Design rule checking can often indicate areas where the risk of loops is higher than normal. This problem is particularly prominent in the design of ground planes. A metal circuit layer may couple with all the lines above and below it. Although the metal layer can effectively block noise, it will also produce associated capacitance, which will affect the speed of the circuit and increase power consumption. As far as the design of multi-layer circuit boards is concerned, the design of through-holes between different circuit board layers is probably the most controversial issue, because through-hole design will bring many problems to the production and manufacturing of circuit boards. Through-holes between circuit board layers will affect the performance of signals and reduce the reliability of circuit board design, so they should be given full attention. Solution: In the design process of printed circuit boards (PCBs), many different methods can be used to solve various problems. Among them, there are adjustments to the design itself, such as adjusting the circuit layout to reduce noise; there are also methods for printed circuit board layout. Design components can be automatically installed through layout tools, but if the automatic layout can be manually adjusted, it will help improve the quality of circuit board design. Through this measure, the design rule detection will use the technical files to ensure that the design of the circuit board can meet the requirements of the circuit board manufacturer. Separating different circuit board layers can reduce the associated capacitance, but this will increase the number of layers of the circuit board, thereby increasing the cost and bringing more through-hole problems. Although the use of orthogonal power supply system and ground line design may increase the physical size of the circuit board, it can effectively play the role of the ground layer in the double-layer circuit board, reducing the capacitance and complexity of circuit board manufacturing. Many PCB design tools can help engineering designers solve many problems at the beginning of the design, but engineering designers still need to have a full understanding of the design requirements of the printed circuit board (PCB). For example, if the editor of the printed circuit board (PCB proofing) needs to know the number of layers of the circuit board at the beginning of the design, for example, a double-layer circuit board needs to have a ground layer and a power layer, two independent board layers. Automatic component placement technology is very useful and can help designers spend more time designing the layout area of the equipment. For example, if the power supply equipment is too close to sensitive signal lines or high temperature areas, many problems will arise. Similarly, signal lines can also be automatically routed and most problems will be avoided. However, analysis and manual operation of high-risk areas will help to greatly improve the quality of printed circuit board (PCB) design, increase revenue and reduce overall costs. Design rule detection is also a very powerful tool that can detect the lines to ensure that the distance between the lines is not too close, which will cause the loop to be too short. However, the overall design still has a high economic value. The design planning detection tool can also be used to detect and adjust the power and ground layers to avoid large associated capacitance areas. 251)] The above tools will also be of great help to Gerber and Excellon, helping them to print circuits and circuit boards and drill through holes in order to produce the final design products. In this way, the technical files are closely linked to the circuit board manufacturers.