PCB Design: Top Three Commonly Missed PCB Documentation Notes

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Garret

Garret Maxson,                           Manager of Engineering Services

As ACDi’s Engineering Services Manager, I see many of our clients’ documentation packages for their PCB design project or circuit card assembly build. I often notice gaps in what clients specify in what I would consider a complete manufacturing data package, especially at the NPI and prototyping level. Even at these earlier production stages, there are some very basic, often-missed notes and instructions that should be included in manufacturing documentation packages to avoid delays or mistakes during the build process. Here are a few of the most commonly missed notes and why it’s important to include these in your manufacturing data package:

  • ITAR

Why it matters:

If your product is subject to ITAR requirements you already know why it matters – because you could get in big trouble with the government if data is sent off-shore or handled by a “non-U.S. person” With the globalization of the electronics manufacturing services industry, several aspects of its supply chain is often sourced off-shore, including PCB fabrication. To ensure data is handled properly, ITAR must be specified on both the PCB fabrication drawing and circuit card assembly drawing. A common mistake we see is that ITAR is specified on the PO issued at order placement, but not on the actual files themselves. This is dangerous no matter how robust your contract manufacturer’s contract flow down process is – don’t put them or yourselves at risk for inadvertently mishandling ITAR sensitive data.

  • IPC Class 2 vs. Class 3 Classification for fabrication and assembly

Why it matters:

 While Class 2 is often the industry default unless otherwise indicated on the drawing, it’s best practice to call out your desired build standards of either Class 2 or Class 3 on both the PCB fabrication and circuit card assembly drawings. It’s also especially important to indicate if there are any preferences regarding specific components on the assembly that need to be treated differently than what the drawing specifies. For example, I have seen clients with a Class 2 assembly have a preference for Class 3 solder fillets for one or two through-hole placements on their project. Indicating this on the drawing package assists with the technical review process both at the quote phase as well as during assembly production.

  • Solder Specification

Why it matters:

Years ago we didn’t have to deal with lead vs. lead-free solder types. With the introduction of RoHS requirements into the electronics industry in 2004, contract manufacturers have since had to support multiple solder/flux combinations. RoHS used to be the exception and thus it made sense that only RoHS would be indicated as a requirement on documentation. However, RoHS is now widely used and depending on the industry leaded is becoming more and more the exception vs. the standard. Despite this trend, we still commonly see RoHS indicated on documentation packages while non-RoHS is not marked. Marking both the fabrication and assembly drawings in the manufacturing data package with either RoHS or non-RoHS assists with proper identification of the required processing.

Avoid confusion and delays in the manufacturing cycle by adding these simple notes to all your PCB fabrication and assembly drawings. Your contract manufacturer will thank you.

Source:

http://www.ecfr.gov/cgi-bin/text-idx?SID=86008bdffd1fb2e79cc5df41a180750a&node=22:1.0.1.13.57&rgn=div5#se22.1.120_115

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