PCB Technical - Other factors of PCB circuit board production

For some products, such as blind and buried vias, immersion gold boards, and pressed copper seat boards, some special calculation methods must be adopted due to the particularity of the process or all materials.

In the same way, the size of the drill nozzle used in the drilling process will also affect the cost of the product, which directly affects the calculation and evaluation of WIP costs and scrap costs.

So how can we better use the design software to lay out the PCB? What are the design rules? Next, this article comes with ten classic rules of PCB design.

1. Choose the correct grid settings and always use the grid spacing that can match the most components. Although 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, polygons are very important for circuit board copper. Multi-grid circuit boards generally have polygonal filling deviations 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.

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.

This is especially applicable to analog and high-speed digital circuits whose system performance is always partially limited by impedance and parasitics.

3. 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.

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 of a certain layer of the PCB, which is conducive to the interaction between running lines on adjacent layers.

4. Group related components and required test points together.

For example: Place the discrete components required by OpAmp operational amplifiers closer to the device so that bypass capacitors and resistors can work with them in the same place, thereby helping to optimize the wiring length mentioned in the second rule, while also enabling testing and fault detection It becomes easier.

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.

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.

7. Perform design rule checking (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.

Every wiring decision is critical, and you can always remind you of the most important wiring by implementing DRC.

8. Flexible use of screen printing.

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).

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.

9. 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.

10. Generate PCB manufacturing parameters and verify them before submitting for production.

Although most circuit board manufacturers are happy to download it directly and verify it for you, it is better for you to output the Gerber file first and use a free viewer to check whether it is as expected 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.