Designing a PCB is one of the most crucial and important aspects of manufacturing any electronic product. The overall layout and design process should be handled by a skilled individual, who is not only an expert in using PCB design software and CAD systems, but understands the proper assembly of basic and complex circuit designs into the whole printed circuit board.
Aside from experience, it is often helpful to follow a guideline to ensure that the design and layout of printed circuit design is close to perfection. There are a number of different guidelines that can be concluded for the design of PCB. One has to make a judgment to balance the importance of one requirement from the other.
Board design constraints
Some of the basic factors that have to be considered when designing the board of the PCB are its size, weight, shape and others that might affect the overall concept of the printed circuit board.
• Appropriate reference points –
The reference holes or points on the board should fit in the manufacturing process. Normally, these are points for test fixtures, so they should be exposed, clear, and not covered by anything.
• Estimate the size of the board-
Even before starting the process of designing, one has to have a rough idea of the appropriate size of the board. Make sure that all its components can be accommodated without overcrowding or jamming all the circuit wires and tracks.
• Decide on the number of layers –
This is important to consider because it affects the overall cost of producing PCB—more layers means additional costs and more complex designs. So, it has to be decided at the beginning of the design process.
• Determine the board mounting procedure –
There are different methods of mounting the board. All of them require varied amounts of space and involve different areas of the board. So, decide upon the method to be used at the beginning to be sure that there’s enough free space.
Planes and Layers
One may use complete or partial layers for power rails. The former is recommended and widely used as it modulates noise and supports current features. Meanwhile, partial planes may result to warping when the bare board is being manufactured or soldered. This may lead to a higher risk of malfunction and system failure.
The number of tracks that can be put in one space of the board is determined by its size. When tracks are too wide and far from one another, it may require extra planes on the board to make sure that the PCB is routed. Conversely, too narrow and close tracks are likely to short-circuit. Additionally, track size determines the amount of current that can be carried. Normally, thin-layered planes have limited current. Consider the size of the track which can carry power rails instead of lower level signals.
It is also necessary to determine the size, shape, and dimensions of both the hole and the board pad. The manufacturer of the raw PCB can determine the standard qualifications for this.
In addition, proper placement of the tracks affects its signal integrity. Parallel tracks with the same lengths have a higher possibility to crosstalk. This could lead to array of problems which will be difficult to remove once the whole printed circuit board is finished. However, the tendency of having tracks meet is sometimes inevitable. So, to decrease the likelihood of crosstalk occurring, make sure that they meet at the right angles.
Following the guidelines on designing the basic parts of PCB is equally important. Some of the guidelines in designing its components are making nodes accessible, providing adequate space between each component, understanding the manufacturer’s specifications, avoiding the use of 90-degree angles for traces, etc. Its components and parts should be designed in harmony to ensure that the printed circuit board will function properly.
The creation of the printed circuit board solved the incoming issue of complex wiring in electronic components when it first started.