Ten golden rules of PCB design
Although the current semiconductor integration is getting higher and higher, many applications also have ready-to-use system-on-chips, and many powerful and out-of-the-box development boards are becoming more and more easily available, but there are many use cases for electronics applications You still need to use a custom PCB. Let ’s take a look at the related content with the mobile phone editor.
In one-time development, even an ordinary PCB can play a very important role. PCB is the physical platform for design, and it is also the most flexible part for electronic system design of original components. This article will introduce several golden rules of PCB design. Most of these rules have not changed since the birth of commercial PCB design 25 years ago. They are widely applicable to various PCB design projects, both for young electronic design engineers and more mature ones. Circuit board manufacturers are extremely instructive.
以下 This article introduces the ten most effective design rules that electronic design engineers should keep in mind and practice when using design software for PCB layout design and commercial manufacturing. Engineers don't need to implement these rules in order of chronological or relative importance, and simply follow them all to greatly change product design.
Rule number one: choose the right grid-set and always use the grid spacing that matches the most components. Although the multi-grid seems to have significant utility, if engineers can think more in the early stage of PCB layout design, they can avoid difficulties in spacing settings and maximize the use of circuit boards. Because many devices are available in multiple package sizes, engineers should use the product that is best for their design. In addition, polygons are very important for circuit board copper plating. Multi-grid circuit boards generally produce polygon filling deviations when performing polygonal copper plating. Although not as standard as based on a single grid, they can provide longer circuit board life than required. .
Rule 2: Keep the path shortest and most direct. This sounds simple and common, but it should be kept in mind at every stage, even if it means changing the board layout to optimize the wiring length. This is especially applicable to analog and high-speed digital circuits where system performance is always partially limited by impedance and parasitics.
Rule # 3: Use the power plane as much as possible to manage the distribution of power and ground lines. Power layer copper is a faster and simpler option for most PCB design software. By connecting a large number of wires in common, it is guaranteed to provide the highest efficiency current with the lowest impedance or voltage drop, while providing a sufficient ground return path. If possible, you can also run multiple power supply lines in the same area of the circuit board to confirm whether the ground layer covers most layers of a certain layer of the PCB, which is beneficial to the interaction between the running lines on adjacent layers.
Rule 4: Group related components together with the required test points. For example: Place the discrete components required by the OpAmp op amp closer to the device so that the bypass capacitors and resistors can work with them in the same place, thereby helping to optimize the wiring length mentioned in rule two, while also enabling testing and fault detection Made easier.
Rule 5: Copy the required circuit board repeatedly on another larger circuit board for PCB imposition. Choosing the size that best fits the equipment used by the manufacturer helps reduce prototyping and manufacturing costs. First make a circuit board layout on the panel, contact the circuit board manufacturer to obtain their preferred size specifications for each panel, then modify your design specifications and try to repeat your design multiple times within these panel sizes.
Rule 6: Integrated component values. As a designer, you will choose discrete components with high or low component values, but with the same performance. By integrating within a smaller range of standard values, the bill of materials can be simplified and costs can be reduced. If you have a range of PCB products based on preferred device values, then in the longer term, it will also help you make the right inventory management decisions.
Rule # 7: Perform as many design rule checks (DRC) as possible. Although it only takes a short time to run the DRC function on the PCB software, in more complex design environments, as long as you always perform checks during the design process, you can save a lot of time, which is a good habit worth keeping. Every wiring decision is critical, and the most important wiring can be reminded at any time by performing DRC.
Rule VIII: Flexible use of screen printing. Screen printing can be used to label a variety of useful information for future use by circuit board manufacturers, service or test engineers, installers, or equipment debuggers. Not only the clear function and test point labels, but also the orientation of the components and connectors as much as possible, even if these notes are printed on the lower surface of the components used on the circuit board (after the circuit board is assembled). The full application of screen printing technology to the lower and upper surfaces of circuit boards can reduce repetitive work and streamline the production process.
Rule 9: Decoupling capacitors must be selected. Don't try to optimize your design by avoiding decoupling power lines and limiting values in component data sheets. Capacitors are inexpensive and rugged. You can spend as much time as possible to assemble the capacitors, while following rule six, use standard value ranges to keep your inventory neat.
Rule 10: Generate PCB manufacturing parameters and verify before submitting to production. Although most circuit board manufacturers are happy to download and verify it for you directly, it is best to output the Gerber file yourself and check with a free viewer to see if it is as expected to avoid misunderstanding. By verifying it yourself, you will even discover some negligent mistakes, and thus avoid losses caused by completing production according to the wrong parameters.
As circuit design sharing becomes more and more extensive, and internal teams are increasingly relying on reference designs, basic rules similar to the above will still be a feature of printed circuit board design. We believe this is very important for PCB design. With these basic rules in mind, developers have the flexibility to increase the value of their products and get the most out of the boards they make. Even if you are new to board design, just keeping these basic rules in mind will speed up the learning process and increase confidence.