PCB Assembly 101 – Designing Printed Circuit Boards

There are quite a couple rules of thumb when it comes to designing circuit boards and in completing PCB assembly. As there are dozens of tools out there, it is still vital to know some tips, especially for beginners, in order to create an optimized printed circuit board. I hope the points below can provide generic overview and explain briefly how to position components to a circuit board and even how to wire them together.

Generally speaking, in PCB assembly, it is always best to place parts on the top side of your board only. And when you do this, you have to make sure that the snap-to-grid is turned on. A value of 0.05” would do wonders.

componentsNow, ready all your components, all your connectors, switches, LEDs, mounting holes, heat sinks, and everything else that mounts to an external location. Place them in their specific locations. Remember to give careful thought when laying out your components. It is important to minimize trace lengths. As much as possible, put directly connected parts next to each other. An optimal layout design will help you lay the traces out with much ease.

Your ICs should be arranged in only one or two orientations, either up or down, and, left or right. Align them in such a way that pin one will be in the same place for each orientation. If you want to save a lot of time, leave reasonably generous spaces between these ICs for traces. You can leave around 0.35” up to 0.5” in between normal sized ICs, and even more for those larger ones.

The polarized parts, such as diodes and electrolytic caps, we recommend, to be positioned with the positive lead having the same orientation.

As soon as you laid out all the components you need, print the copy of the layout. You can place the actual components on top of the layout to verify if you have given them enough space to rest without touching one another.

Now the next step would be lay the power and ground traces. This is crucial if you work with ICs to have solid power and ground lines. As with anything related or involving PCB assembly, avoid snaking the power lines from part to part.

After then, place the signal traces. It is nice to make it a habit to make them as short and direct as possible. Use bias, or a pad with a plated-through hole, in moving signals from one layer to another. The best you can do is to lay out a board with vertical traces on one side and horizontal ones on the other. Then add a via where you need to connect a horizontal trace to a vertical trace on the opposite side. A good trace width is normally 0.010” for low current signals, both digital and analog.

Circuit BoardWhen all the traces are placed, make sure to double check the routing of every signal. This way, you are assured that nothing is missing or even incorrectly wired. Just run through your schematic one wire at a time. Follow the path of each trace on the layout. When all is confirmed, and verified correct and valid, mark it. Inspect your actual layout, top and bottom, ensure the gaps between the components are reasonable, approximately 0.007” and above recommended. Check for vias, make sure nothing is missing. Check all your traces and make sure none crosses another.

These are just a few tips you can use when you are just starting working on printed circuit boards and doing your own PCB assembly. You can use them and apply them with whatever tool you are using. However doable this may sound, you are most likely to miss a step. And while it could be of great consequence when you do so, you can always go to professionals for designing your printed circuit board. Imagineering Inc. provide online services that can deliver your board in a very timely manner – and with utmost quality.

For High quality Printed Circuit Board fabrication and PCB assembly, contact www.pcbnet.com.