How to make your PCB design better

(1) Draw a schematic

Many engineers feel that the layout work is more important. The schematic diagram is for the purpose of generating a netlist for PCB inspection. In fact, the schematic diagram will be more important in the subsequent circuit debugging process. Whether it's finding a problem or communicating with a colleague, the schematic is more intuitive and convenient. In addition, develop the habit of making annotations in the schematic diagram, and mark the problems that should be noticed when the various parts of the circuit are laid out on the schematic diagram, which is a good reminder to yourself or to others. The hierarchical schematic diagram divides the circuits of different modules with different functions into different pages, so that the workload can be significantly reduced whether it is read or reused. Using a mature design is always less risky than designing a new circuit. Every time I see that all the circuits are placed on a single sheet of paper, a dense piece of equipment, the head can be a big circle.

(2) Do a good job of circuit layout

The anxious engineer draws the schematic diagram, and after importing the netlist into the PCB, he can't wait to put the device in place and start pulling the wire. In fact, a good PCB layout can make your wire drawing work easier and make your PCB work better. Each board will have a signal path. The PCB layout should also follow this signal path as much as possible so that the signal can be transmitted smoothly on the board. People don't like to go through the maze, and the signal is the same. If the schematic is designed according to the module, the PCB is the same. The board can be divided into several areas according to different functional modules. The analog numbers are separated, the power signals are separated, the heating device and the susceptible device are separated, the larger device is not too close to the board edge, pay attention to the shielding of the RF signal, etc. It takes a minute to optimize the layout of the PCB. Save more time when pulling the cable.

(3) Learn to set rules

In fact, not only advanced PCB design software needs to set wiring rules, but some simple and easy-to-use PCB tools can also be set. After all, the human brain is not a machine, and it is inevitable that there will be negligence and mistakes. So put some easy to ignore problems into the rules, let the computer help us check, try to avoid making some low-level mistakes. In addition, the perfect rule setting can better regulate the work behind. The so-called sharpening of the knife does not mistakenly cut the woodworker. The more complicated the scale of the board, the more important the importance of the rule setting. Many EDA tools now have an automatic routing function. If the rules are set in enough detail, let the tools help you design them yourself. Isn't it a more pleasant thing to have a cup of coffee?

(4) The more you think about others, the less your work

When designing the PCB, consider as many end users as possible. For example, if you are designing a development board, you should consider placing more silkscreen information when designing the PCB, so it will be more convenient when you use it. You don't have to go back and forth to find the schematic or find support from the designer. If you are designing a mass-produced product, you should consider more of the problems encountered on the production line. The same type of device should be in the same direction, the device spacing is appropriate, the process side width of the board, and so on. The earlier these issues are considered, the less the design will be affected, and the amount of work and the number of boards that will be supported later. It seems that the time spent on design has increased, actually reducing the amount of work that follows. In the case that the board space signal allows, try to place more test points and improve the testability of the board, so that more time can be saved in the subsequent debugging stage, and more ideas can be provided for finding problems.

(5) Details determine success or failure

PCB design is a meticulous job that requires care and patience. The mistakes often made by newcomers who are just beginning to design are some details. The device pins are wrong, the device package is wrong, the pin sequence is reversed, and so on, some can be solved by flying lines, and some may make a board directly become waste. When you draw the package, check it again. Before you cast the board, print the package and compare it with the actual device. Look at it more. It is not obsessive-compulsive to check it again. It is just to avoid these low-level mistakes that are easy to make. Otherwise, the design of the good-looking board, covered with flying lines, is far from excellent.

(6) Try to do the simulation

Simulation is often something that PCB design engineers are not willing to touch. Some people may say that even if I simulate, the actual PCB and simulation results will be different. Then I am going to waste time doing simulation? I don’t simulate the board that is not working properly. The idea is very helpless. There is no problem with one or two designs, and it does not mean that there will be no problems in the future. Although the simulation results are different from the actual results, the simulation can show the correct trend, and we can make our own judgment according to the trend. It may be difficult at first, and it is normal for the simulation parameters simulation model to be foggy. As soon as you start, slowly do it and slowly accumulate it, you will realize the importance of simulation. Determine the location that is prone to problems before the board is completed, and solve it in advance to avoid problems. If the simulation is done much, it will fundamentally understand the cause of the problem and will greatly help improve the design ability.