![]() ![]() Years ago we didn’t have to deal with lead vs. Indicating this on the drawing package assists with the technical review process both at the quote phase as well as during assembly production. 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. 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. 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. Class 3 Classification for fabrication and assembly 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. A common mistake we see is that ITAR is specified on the PO issued at order placement, but not on the actual files themselves. To ensure data is handled properly, ITAR must be specified on both the PCB fabrication drawing and circuit card assembly drawing. person” With the globalization of the electronics manufacturing services industry, several aspects of its supply chain is often sourced off-shore, including PCB fabrication. 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. Here are a few of the most commonly missed notes and why it’s important to include these in your manufacturing data package: 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. 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. Your PCB with placed polygons for nets VCC3 and VCC5 nets should look like the figure below.Garret Maxson, Manager of Engineering ServicesĪs ACDi’s Engineering Services Manager, I see many of our clients’ documentation packages for their PCB design project or circuit card assembly build. For example, a conductor with 0.5mm width, made of 18um copper foil and plated with 35um finish coating with a board thickness of 1.5mm and the distance to the reference range 0.15mm can withstand 3 amperes without any problems. However, on the outer layers, the copper thickness is higher due to the finish coating, so the conductors on the outer layers are able to withstand much higher current. ![]() Sharp corners may increase current density that can lead to overheating of the PCB and possible copper burnout. It is also recommended to place faces of polygons at an angle of 45 degrees to each other. Conductors with a width of 0.3mm in the same configuration can withstand 1.2 amperes and a 0.5mm conductor can withstand 1.8 amperes. This conductor is able to withstand a current of ~0.88 amperes. For example, there is a conductor with a width of 0.2 mm located in the inner layer of the PCB with a thickness of 1.5mm and a distance of 0.15mm to the reference plane. You can calculate the current threshold for a given polygon width using the IPC-2152 standard. Always remember that the wider the polygon, the more current it will hold and the more reliable the printed circuit board will be. You can modify the polygon border of a polygon at any time by moving the handles that appear when a polygon is selected. Using this approach for polygon creation, create polygons for nets VCC3 and VCC5 on all layers where those nets are present. ![]()
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