PCB board design is a crucial part of the entire circuit board production, whether it is design direction, selection of grounding points, arrangement of power filter/decoupling capacitors, line diameter, as well as the number of vias, solder joints and line density, these five major key points determine the final overall structure and application quality of the PCB board. The following will give you a detailed introduction to the five key points of PCB board design.
It is a combination of scattered components, while ensuring the regularity of circuit design, and avoiding confusion and errors caused by manual wiring and wiring.
1. There must be a reasonable direction.
Such as input/output, AC/DC, strong/weak signal, high frequency/low frequency, high voltage/low voltage, etc. Their direction should be linear (or separated) and must not blend with each other. Its purpose is to prevent mutual interference. The best trend is in a straight line, but it is generally not easy to achieve. The most unfavorable trend is a circle. Fortunately, isolation can be set to improve it. For DC, small signal, low voltage PCB design requirements can be lower. So “reasonable” is relative.
2. Choose A Good Grounding Point: The grounding point is often the most important.
Many engineers and technicians have talked about the small grounding point, which shows its importance. Under normal circumstances, a common ground is required, such as multiple ground wires of the forward amplifier should be merged and then connected to the main ground and so on. In reality, it is difficult to achieve this completely due to various restrictions, but we should try our best to follow it. This problem is quite flexible in practice. Everyone has their own set of solutions. It is easy to understand if they can explain it for a specific circuit board.
3. Reasonably Arrange Power Filter/Decoupling Capacitors
Generally, only a number of power filter/decoupling capacitors are drawn in the schematic, but they are not pointed out where they should be connected. In fact, these capacitors are provided for switching devices (gate circuits) or other components that require filtering/decoupling. These capacitors should be placed as close to these components as possible, and there is no effect when too far away. Interestingly, when the power supply filter/decoupling capacitors are arranged properly, the problem of grounding points becomes less obvious.
4. There is a requirement for the line diameter to be the appropriate size of the buried hole through hole.
If possible, wide lines should never be made thin. High-voltage and high-frequency lines should be round and slippery, without sharp chamfers, and corners should not be at right angles. The ground wire should be as wide as possible, and it is best to use a large area of copper, which can greatly improve the problem of grounding points. The size of the pad or via is too small, or the size of the pad and the hole size are not properly matched. The former is unfavorable for manual drilling, and the latter is unfavorable for CNC drilling. It is easy to drill the pads into a “c” shape, and to drill off the pads. If the wire is too thin, and the large area of the unwiring area is not provided with copper, which is easy to cause uneven corrosion. That is, when the unwiring area is corroded, the thin wire is likely to be over corroded, or it may appear to be broken, or completely broken. Therefore, the role of setting copper is not only to increase the area of the ground wire and anti-interference.
5. Number of Vias, Solder Joints And Line Density
Some problems are not easy to be found in the early stage of circuit production, and they tend to emerge in the later stage. For example, if there are too many vias, a slight mistake in the copper sinking process will bury hidden dangers. Therefore, we should minimize the wire hole. If the density of parallel lines in the same direction is too large, and it is easy to join together when welding. Therefore, the line density should be determined according to the level of the welding process. If the distance between the solder joints is too small, which is not conducive to manual welding, and the welding quality can only be solved by reducing the work efficiency. Otherwise, hidden dangers will remain. Therefore, the minimum distance of solder joints should be determined by comprehensive consideration of the quality and work efficiency of the welding personnel.
Mastering and understanding the five key points of PCB board design can effectively improve the efficiency of the entire PCB board production process and ensure product quality, save time, save manpower and material resources, and reduce rework rate and reduce material input costs.
XPCB Limited is a manufacturer specializing in the production of high-precision double-sided, multi-layer and impedance, blind buried vias, and thick copper circuit boards. The products cover HDI, thick copper, backplanes, rigid-flex combined, buried capacitance and buried resistance, Golden Finger and other kinds of circuit boards, which can meet the needs of customers for all kinds of products.
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