For efficient PCB assembly, it’s important to clearly document which component goes where. The traditional way is to write a unique identifier next to each component on the silk screen overlay. In this post, we share an alternative workflow that enables us to design and assemble prototype boards faster.
The traditional way to identify components is the silk screen overlay. This is the white text you commonly see on circuit boards. Apart from component identifiers such as
R79, a good design will also clearly indicate the footprint shape and component rotation.
This is really important, as chips tend to let out some ‘magic smoke’ if you mix them up or solder them the wrong way around…
Sometimes silkscreen is not an option. With high-density layouts, the silkscreen text simply takes up too much board area. For example, the designator text for a 0402 resistor will be much larger than the component itself! Another reason to leave out the designators is rapid prototyping: a neat silkscreen design takes time!
The OperationAir PCB (shown above) is a good example. We designed this board as part of Operation Air: a cooperation with the Delft University to build an emergency ventilator for corona patients. As the first wave of corona threatened to overload hospital capacity, this project had extreme time constraints. For the first revision, we skipped silkscreen altogether. This made the design process quicker and even shaved time off PCB manufacturing. In less than four weeks of time, the second revision was already taken into mass production.
We use KiCad for PCB design. This open-source tool is very flexible and extendable with scripts and plugins. One of our favorite plugins is the Interactive BOM plugin. This generates an interactive BOM that is very handy during manual assembly. Try clicking the image below!
After using this for a while during prototype assembly, I noticed that I didn’t really need the silkscreen designators any more. It is much faster to click a BOM row, and simply remembering the highlighted component locations. It even clearly marks the pin-1 location! Below is the BOM for the Operation Air board as an example. Try to click it: it is interactive!
If you are already using KiCad, definitely give this plugin a try! Do you have another workflow you want to share? Or are you curious if we can deliver a super quick prototype design? Feel free to contact me at firstname.lastname@example.org.