Drawing paths in a PCB design is often considered a simple task. After transferring the schematic to the PCB page and placing the components on the board, it seems a relatively easy task to start connecting the components with copper. While this is true in the days when low-speed TTL DIP components are used on simple cards, today's design requirements are much more complex. Paths on a PCB can carry very specific design requirements for ensuring signal integrity during routing.
While routes have specific routing requirements, today's more advanced PCB routing features can help you set and comply with design rules for your paths. The important routing techniques you use for your card depend on the signal standard you work with and the required routing topology. At this point, altium designer provides you with good help.
At this point, there are actually two types of general path drawing methods. The first is automatic path drawing and the other is manual path drawing. Let's see them both, respectively.
Auto Route is a tool found in almost all PCB design software. As beginners, this way of drawing is thought to be really easy, but in fact it will not replace manual drawing for a long time.
We had a little introduction to this topic in our PCB design article. In this article, we will collect all the information in general and present it to you collectively.
This command is accessed from the PCB Editor by selecting the Route » Auto Route » All command. But remember, each manufacturer has certain PCB parameter ranges. When you exceed these limits or want to produce at lower values, you will encounter major problems. Therefore, if you first set the limits that your manufacturer can produce from PCB Rules, you eliminate such problems from the beginning. This point is really critical.
This tool really helps you with road drawing, but as we said at the beginning, manual drawing is always more advantageous.
Manual Path Drawing
Altium Designer already clearly indicates to you where the path will go in the road drawing essence. If you make the component layout beautifully, your road drawing will be just as smooth. Otherwise, you're very likely to have problems. This part of the job will get better as your experience increases.
As we know in the path drawing, using the shortcut CTRL-W would be the simplest method. Then you can easily draw your way to the point where it is shown by tapping on a desired pine. Just make sure your path doesn't overlap with other pads, pins. Anyway Altium Designer will help you again by showing you warning at this point.
At this point, there are some points where paying attention will give us an advantage. Let's see them in the title.
You can use the automatic router after you have placed all your components to see which components are completed. If the location rate is below 85%, it indicates that you need to make some adjustments to your part placement.
You can also use the automated router to find bottlenecks and other critical ports that you may not have seen during your component placement.
Finally, you can use the automatic router as an inspiration for how you might want to redirect some tracks that you can't complete. Running the automatic router quickly can show you a new way you haven't thought of it before.
Thanks to this image, we see an exemplary road drawing. As you can see, it will be to your advantage to make the corners of the roads as sharp as possible. Of course, there are a lot of parameters that we need to consider in this situation. It will be much better for us to write a separate article about this in the future.
Finally, let's talk about the general rules.
Road Drawing Rules for Modern PCBs
Even those who use a simple MCU and low power system today need to know some road design and routing rules to ensure signal integrity. Designers need to determine path geometry requirements to ensure reliability and signal integrity.
- Determine the existing requirements on a specific path; Power circuits in pcb can be used for routing, high current portability, etc.
- If the current is going to be too low (less than 1 A), look at your component datasheets or signaling standard to determine whether impedance control is required.
- If impedance control is required, calculate the width of the path required to reach your impedance target.
- Also calculate the required path range if differential pairs are needed.
If impedance control is required, a routing topology will probably be applied with single-ended or differential pairs.
Be sure to check your signaling standards to determine your routing requirements, which will include things like the amount of loss (determines the total length), impedance requirements, and the given length mismatch of the path in differential pairs or a parallel bus.
In fact, in general, it is as simple as to make way for Alitum Designer. Just as we know, there is some important information that we should pay attention to. The more experience we have in this business, the easier it will be for them.