Hidden (and Obvious) Design Mishaps With Big Cost Impacts

Estimated reading time: 2 minutes

At Monsoon Solutions, we provide PCB layout services for the full lifecycle of products, from one-off prototypes to items manufactured in production volume. We also manage manufacturing and assembly for prototype and smaller production runs for both customer-produced and in-house layouts. As a result, we see various manufacturing data packages and work with many different manufacturers. I asked our PCB design engineers and program managers to share the cost adders and cost savers that designers can affect, and it was interesting to see that in addition to more technical responses, some of the biggest culprits were rather simple.

Fabrication Note Errors

Starting with PCB fabrication, one of the most obvious and simplest cost adders is incorrect or missing fabrication notes. As designers, we all like to have a starting point for a layout rather than having to start from scratch, and that often means starting from a similar board, which comes with existing fabrication notes. As a service bureau, we also often work on revisions of designs, and thus we inherit fabrication notes from the previous design. A common mistake I see from designers is when they leave notes the new designer doesn’t understand or know if they are required. I will often see them ask the customer about the notes, and it’s not uncommon for the customer to not know if they apply either. Rather than removing them, they commonly remain “just to be safe.” This often leads to extra processes like via fill, planarize, and plate. It may lead to building to Class 3 vs. Class 2 or extra testing and paperwork requirements. It may lead to adding hard gold vs. just ENIG. It may lead to ordering more exotic materials where standard FR-4 was fine. It also can lead to back-and-forth DFM questions as the fabricator must confirm what does or doesn’t apply, and with which offshore vendors can mean delays of multiple days.

Similarly, if there are no fabrication notes, the fabrication vendor is left guessing and may choose processes or materials that are more expensive or not absolutely needed, or they may miss important aspects of the design, like controlled impedances or that a specific thickness is needed for edge connectors. Make sure to review your notes for clarity and correctness before sending them to the fabrication shop. If you are unsure how to specify your requirements, talk to your fabricator.

To read the entire article, which originally appeared in the August 2024 Design007 Magazine, click here.