It was the end of May, which among other things, meant that the Major League Baseball season was once again in full swing (pun intended). While my wife was happily settled into the couch with her Seattle Mariners cap, T-shirt, blanket, and coffee mug cheering on J.P Crawford and the rest of the team, I turned on a movie instead. So, to keep with the spirit of the season, I re-watched “Field of Dreams,” and was again mesmerized by the voice that speaks to Kevin Costner’s character: “If you build it, they will come.”
As circuit board designers, it’s probably not all that unusual to hear similar voices speaking to us, especially after staring at a layout for hours, and hours, and hours. But in our case, the message is typically a little different, and sounds more like, “If you document it correctly, they will build it.”
Yes, I’m talking about PCB documentation, and the importance of creating clear and understandable instructions for building the circuit board that you’ve just designed. To illustrate how essential this is, let me tell you about my latest project: the trike. The month of May isn’t just about baseball in our house, it is also my wife’s birthday. This year I gave her an adult-sized trike for cruising around the neighborhood and exploring campgrounds during our vacations. This trike promises to be a lot of fun and she is really looking forward to riding it, but first we have to put it together and that is where the problem comes in. The assembly manual for the trike must be the absolute worst set of documentation that I’ve ever seen.
Not only is this document filled with translation errors from the language it was initially written in, but there are plenty of other spelling and grammatical errors as well. The manual appears to have been written for a different model of trike than what we have, as the pictures don’t match and it isn’t laid out sequentially from one step to the next as you would expect. For instance, step one shows some pre-mounted bolts in different locations than where they actually were installed at the factory. Step two describes how to mount the rear axis (and I’m guessing they really meant “axle” here instead) to the frame with a picture showing the wheels already mounted on the axle. Step three then instructs you how to mount those wheels to the axle even though the previous step already had them in place. Trying to make sense of it all requires a lot of detective work, and I’m constantly going back and forth between the manual and online videos to reverse engineer this mess and figure out what really needs to be done. However, I must confess, in spite of the extra effort taking up far more time than it should, I’m actually loving the technical challenge of it all.
This experience has given me a greater appreciation than ever before for the necessity of creating clear and concise manufacturing instructions when I design a printed circuit board. After all, if the rear wheels fall off the trike because I didn’t mount them correctly to the “axis,” then there is the very real potential for embarrassment or injury, neither of which is a desirable situation. Likewise, unclear fabrication and assembly documentation could also result in some negative consequences due to lost time and revenue from un-manufacturable circuit boards. To avoid problems like these, and many others as well, here are some ideas I try to keep in mind while documenting a PCB design:
1. Find out what your manufacturer needs and expects.
Many manufacturers end up spending unexpected time conferring with their customers over missing or unclear details in their build instructions. If the information isn’t clear from the documentation, or is different than what was already agreed on, the manufacturer must resolve the differences before they can proceed with circuit board production. This lost time can increase the overall production cost or delay the build, but it can be easily avoided by talking first with the manufacturer and finding out exactly what they need. Some manufacturers have even told me that they end up correcting and regenerating their clients’ prototype documentation to help them transition more efficiently into full production. If this documentation was created clearly to begin with, a lot of time and effort could have been saved.
2. Don’t skimp on the details.
Manufacturing drawings and other build instructions usually end up with a lot of data and information in them. And although it is good to cut back on superfluous data for overall clarity in the documentation, designers need to avoid the temptation to cut back too much. Be sure to include adequate views, notes, and other details that specify how your design is to be fabricated and assembled. Also, be careful when using “standard” notes and other drawing elements stored in your PCB libraries. Stock drawing elements like these are great time savers, but they must be closely examined first to see if they need updates to match the specific requirements of the design. Minute details such as tolerances or surface finishes may be incorrect and can easily be overlooked.
3. Leverage the power of your design tools.
PCB design tools today have some incredible features within them to help with the creation of drawings and other manufacturing documentation, but these tools don’t always get used. Often designers face some serious time challenges when getting a design out the door, and typically the drawings are one of the last pieces to the puzzle to be worked on. Therefore, many designers will avoid experimenting with new CAD features and simply go with what has always worked in the past. One of the biggest favors you can do for yourself is to invest some time (before crunch time) and find out what kind of unique features your design tools might have that you aren’t aware of. View generators, table and chart wizards, automated dimensioning, and other advanced CAD features could end up saving you a lot of additional time and effort in the future.
4. During review, ask yourself, “Could I build what I just documented?”
I think that everyone is used to reviewing their work for completeness and accuracy, but have you ever looked at a drawing and asked yourself, “Could I build that?” I know that we are PCB designers and not manufacturers, but we are the ones creating the documentation for fabrication and assembly shops to build our designs. We should be able to tell if the manufacturers can do the job based on the documents we are sending them. If you are unfamiliar with the fab and assembly processes, spend some time with your vendors to better understand what they do and what they need from you to do it. As a designer, it is extremely interesting to tour the manufacturing facilities you are using, and see exactly how your design is being brought to life. After all, the more we know about what we are telling our vendors to do, the better the final product will be.
These are some of the ideas that run through my head when I’m preparing manufacturing documentation, and I hope that they will help you too. And with that, it’s time for me to transition back out to the garage and pick up where I left off. I think that I’m ready to start step four of the great trike project, and I’m looking forward to it. Oh, and a quick note to self: first check and confirm that those rear wheels really are as tightly mounted as they should be. Until next time, then, everyone, keep on designing.
This column originally appeared in the July 2022 issue of Design007 Magazine.