If you’ve talked to any PCB designers or read about designing a PCB, it quickly becomes apparent that the process of building a board from scratch leaves little room for error. Even the smallest design mistake can make your board non-functional, or worse, non-manufacturable. With the need for such accuracy and meticulous planning, the design process can be quite intimidating.
Thankfully, you can learn from mistakes that others have made in the past. Today, we’ll walk through 5 of the most common mistakes that printed circuit board designers make to help you get on your way to error-free files and reduce your estimated PCB cost.
1. Don’t skimp on trace width
It’s tempting to make the traces on your board as narrow as possible to maximize the surface area of your board. That’s doubly true when you’re working on a small printed circuit board, where every millimeter counts.
However, if you have components that require currents higher than 500 mA, you’ll need to think twice about how much width you shave off your wiring. Narrow traces can overheat when carrying a lot of current, ultimately preventing your printed circuit board from doing its job.
Calculating how wide your traces need to be can be very time consuming, but you can skip the equations by using a trace width calculator. We recommend using this calculator, which allows you to input your board’s current, the maximum allowable temperature rise, and the trace thickness. Using all this information, the calculator will determine exactly how wide your traces need to be.
2. Get the right antenna impedance
If your circuit board needs to receive wireless signals, either from a WiFi router or a remote controller, you’ll need a wireless antenna. Unfortunately, adding a wireless antenna to your PCB is more complicated than it might seem. If you design your antenna incorrectly, it may not be able to receive a signal.
The key to placing a wireless antenna is getting the impedance right. Impedance depends on the electrical properties of your board and your transceiver, and it plays a significant role in determining whether your antenna will consistently receive a high-quality WiFi signal.
Adding a microstrip to your board allows you to modify the impedance going to your antenna. The width of the microstrip you need depends on the dielectric properties of your board, which you can determine using a calculator (we recommend this one). With the right microstrip in place, your board will receive a much more consistent wireless signal.
3. Double-check your decoupling capacitors
Decoupling capacitors provide sensitive components with stable voltage. They are required on most PCBs that include an integrated circuit, which can be damaged by voltage fluctuations.
For decoupling capacitors to work properly, they must be placed as close as possible to the components they are meant to serve. Unfortunately, that can create some routing headaches, which makes it tempting to bypass the decoupling capacitors and connect your power source directly to the sensitive component.
To avoid any problems, always connect your power supply to the decoupling capacitors first, before routing it to the component. If you route directly from the power supply to the component, the capacitors can’t do their job. Components need stable voltage to perform effectively and routing through a decoupling capacitor provides that stability.
4. Choose your vias carefully
Vias are copper-lined holes in your printed circuit board that you can use to connect multiple layers of components. We love vias because they enable you to create more effective space for components on a small board.
If you’re using vias, which go through all the layers of your board, you might not have to worry about making a design mistake. Since these vias are drilled through your entire board, they can almost always be manufactured.
Blind and buried vias, however, are another story. Blind vias connect an external layer to an internal layer, whereas buried vias connect two internal layers. If these vias aren’t designed correctly, they can cause problems with the functionality of your board or even make it difficult to manufacture. For example, if you put a buried via that requires drilling through a component, your manufacturer may accidentally destroy that component while building your board.
Unfortunately, your design software might allow you to create these troublemaking vias even if they ultimately may not be functional. The best solution is to avoid blind and buried vias whenever possible. In many cases, a through via can work just as effectively. If you must have blind and buried vias in your board, don’t rely on your software to identify problematic layouts. Instead, manually inspect each via to make sure that drilling it won’t interfere with other components.
5. Make sure your landing patterns match your components
Every component you place on your board has a footprint, which must be matched by a landing pattern on your board. When the footprint and the landing pattern match, your component can be attached to the board seamlessly.
In most cases, you won’t even have to think about this. When buying circuit boards the majority of printed circuit board design software automatically adds the required landing pattern for a component when you add elements to your board.
However, if you add components from outside your software’s library, you may run into complications. Your software will not automatically add landing patterns for these external components. Instead, you will need to manually design the patterns yourself.
It is very important that the landing pattern design is flawless. Even just a one millimeter mismatch between your pattern and the component can make it difficult to solder the component onto the board. Just be sure to double-check your design to be certain that you won’t run into any attachment issues down the road.