Ten rules of PCB design
Although the current level of semiconductor integration is getting higher and higher, many applications also have system-on-chips available at any time, and many powerful and out-of-the-box development boards are also more and more easily available, but many use cases in electronic products The application still needs to use a custom PCB. In one-time development, even an ordinary PCB can play a very important role. PCB is the physical platform for design and the most flexible part for electronic system design of original components.
This article will introduce ten rules that should keep in mind and practice when using design software for PCB layout design and commercial manufacturing. Most of these rules have not changed since the commercial PCB design was born 25 years ago, and they are widely applicable to various PCB design projects. They have a great guiding role for young electronic design engineers and mature print circuit board manufacturers.
Rule 1: Choose the right grid-set and always use the grid spacing that matches the most components.
Although the multi-grid seems to be effective, if engineers can think more in the early stage of PCB layout design, they can avoid the problems encountered in the interval setting and maximize the application of the circuit board. Because many devices use multiple package sizes, engineers should use the product that is most conducive to their own design. In addition, polygon is very important for circuit board copper. Multi-grid circuit boards generally produce polygonal filling deviation when polygonal copper is applied. Although it is not as standard as based on a single grid, it can provide more than the required circuit board life.
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 to change the circuit board layout to optimize the wiring length.
Rule 3: Group related components together with the required test points.
Rule 4: Use the power layer as much as possible to manage the distribution of power lines and ground lines.
The power layer copper is a faster and simpler choice for most PCB design software. By connecting a large number of wires in common, it is possible to ensure that the current with the highest efficiency and minimum impedance or voltage drop is provided, while providing sufficient ground return paths.
Rule 5: Copy the required circuit board on another larger circuit board multiple times for PCB imposition.
Choosing the size that is most suitable for the equipment used by the manufacturer will help reduce the cost of prototyping and manufacturing. First carry out the 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: Integrate component values.
As a designer, you will choose discrete components with higher or lower component values ??but the same performance. By integrating within a smaller standard value range, the bill of materials can be simplified and costs can be reduced. If you have a series of PCB products based on the value of the preferred component, it will be more conducive to you to make the correct inventory management decision from a longer-term perspective.
Rule 7: Perform design rule checks (DRC) as much as possible.
Although it only takes a short time to run the DRC function on the PCB software, in a more complex design environment, as long as you always perform checks during the design process, you can save a lot of time. This is a good habit worth keeping
Rule 8: Decoupling capacitors must be selected.
Don't try to optimize your design by avoiding decoupling the power lines and based on the limit values ??in the component data sheet. Capacitors are inexpensive and durable. You can spend as much time as possible to assemble the capacitors. At the same time, follow Rule 6 and use the standard value range to keep your inventory tidy.
Rule 9: Use screen printing flexibly.
Screen printing can be used to mark various useful information for future use by circuit board manufacturers, service or test engineers, installers, or equipment debuggers. Not only mark clear function and test point labels, but also mark the direction of components and connectors as much as possible, even if these comments 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 on the upper and lower surfaces of the circuit board can reduce repetitive work and streamline the production process.
Rule 10: Generate PCB manufacturing parameters and verify them before submitting for production.
Although most print circuit board manufacturers are happy to download it directly and verify it for you, you'd better output the Gerber file yourself and check whether it is the same as expected with a free viewer to avoid misunderstandings. Through personal verification, you may even find some negligent errors, and therefore avoid losses caused by completing production according to the wrong parameters.