Introduction To The Design Skills And Key Points To Achieve Efficient PCB Automatic Wiring

Although today’s EDA tools are powerful, PCB design is not easy as PCB size requirements become smaller and device densities become higher. How to achieve a high PCB distribution rate and shorten the design time?

Now PCB design time is getting shorter and shorter, smaller and smaller board space, higher and higher device density, extremely strict layout rules, and large component size make the designer’s job more difficult. In order to solve the difficulties in design and speed up the marketing of products, many manufacturers now tend to use special EDA tools to achieve PCB design. However, dedicated EDA tools do not produce the desired results, do not achieve a 100% pass rate, and are messy, often taking a lot of time to complete the rest of the work.

Now there are many popular EDA tools in the market, but they are all the same except the terminology and the position of function keys. How to use these tools to better realize the design of PCB?

The wiring of key signals should consider the control of some electrical parameters during wiring, such as the reduction of distributed inductance and EMC, etc. The wiring of other signals is similar. All EDA vendors provide a way to control these parameters. The quality of automatic wiring can be guaranteed to a certain extent by understanding the input parameters of the automatic wiring tool and its effect on wiring.

Generic rules should be adopted for the automatic wiring of signals.

By limiting the number of layers to be used and the number of holes to be used for a given signal by setting limits and forbidden wiring areas, the wiring tool can automatically route the wires according to the engineer’s design. If there are no restrictions on the number of layers used by the auto wiring tool and the number of holes placed, each layer will be used during auto wiring and many holes will be created.

After the constraints are set and the rules created are applied, the automatic cabling results will be close to what is expected, although some tidied up work may be required, and space for other signals and network cabling will need to be ensured. After a part of the design is completed, it is fixed in place to protect it from subsequent wiring processes.

The same procedure is used for wiring the remaining signals.

The number of cabling depends on the complexity of the circuit and how many general rules you have defined. After each type of signal is completed, the constraints on the remaining network wiring are reduced. But with that comes a lot of signal wiring that requires manual intervention.

Today’s automatic wiring tools are very powerful and can typically complete 100% of the wiring. However, when the automatic routing tool does not complete the signal routing, the remaining signals need to be manually routed.

The key points of automatic routing design include:

1. Change the Settings slightly and try out multiple routing paths;
2. Keep the basic rules unchanged, try different wiring layers, different printed lines and spacing widths, different line widths, different types of through holes, such as blind holes, buried holes, etc., observe how these factors affect the design results;
3. Let the cabling tool handle those default networks as needed;
4. The less important the signal is, the more freedom the automatic wiring tool has over its wiring.