What are the design requirements for PCB circuit board layout and wiring?

As PCB size requirements are getting smaller and smaller, device density requirements are getting higher and higher, pcba manufacturer design is becoming more and more difficult, and higher requirements are put forward for PCB layout and wiring. So, what are the design requirements for PCB layout and wiring?

1. Determine the number of PCB layers

The size of the circuit board and the number of wiring layers need to be determined at the initial stage of the design. The number of wiring layers and the stacking method will directly affect the wiring and impedance of the circuit board; at the beginning of the design, it is best to use more circuit layers and evenly distribute the copper.

2. Design rules and restrictions

To classify all signal lines with special requirements, each signal class should have a priority. The higher the priority, the stricter the rules. The rules involve the width of the printed lines, the number of vias, the degree of parallelism, the mutual influence between the signal lines, and the layer restrictions, which have a great impact on the performance of the wiring tool.

3. The layout of the components

If the assembly department allows the components to move, the circuit can be appropriately optimized, which is more convenient for automatic wiring. The automatic wiring tool only considers one signal at a time. By setting the wiring constraints and setting the layer of the signal line, the wiring tool can complete the wiring as the designer imagined.

4. Fan-out design

In the fan-out design stage, each pin of the surface mount device should have at least one via, so that when more connections are needed, the circuit board can perform internal connection, online testing, and circuit reprocessing. In order to make the automatic routing tool efficient, it is necessary to use as large a via size and printed line as possible, and the interval is ideally set to 50mil.

5. Manual wiring and processing of key signals

The key signals are wired first, either manually or in combination with automatic wiring tools. After the wiring is completed, the relevant engineering and technical personnel will check the signal wiring. After the inspection is passed, the wires will be fixed, and then the remaining signals will be automatically wired.

6. Automatic wiring

General rules should be used when automatically routing signals. By setting restrictions and prohibiting wiring areas to limit the layers used by a given signal and the number of vias used, the wiring tool can automatically route the wires according to the engineer's design ideas. After setting the constraints and applying the created rules, the automatic routing will achieve results similar to expectations.

7. Arrangement of wiring

For some signals with few constraints, the wiring length is very long. At this time, you can first determine which wiring is reasonable and which wiring is unreasonable, and then manually edit to shorten the signal wiring length and reduce the number of vias.

The above are the ten design requirements of quick turn PCB circuit board layout and wiring. Have you learned it?