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14 DESIGN007 MAGAZINE I DECEMBER 2024 Are Our Stackup Rules No Longer Valid? Feature Article by Cherie Litson EPTAC MIT CID/CID+ Are the stackup rules we used to follow no longer valid? It depends on what you're design- ing. Electrical rules change depending on your circuit. Fabrication rules change depending on which fabricator you're working with. Today, we just have more options, and sometimes, cost is a bigger rule than anything else. If you search online for information about layer stackups, trace widths, and hole sizes in PCBs, you'll find a variety of resources. e trick is to first define your electrical and mechanical requirements, then work with your fabricator to find the savings (i.e., profits) for both the customer and fabricator. So, how do you navigate all the rules? First, keep learning. Get certified through the CID and CID+ exams. Go to conferences such as IPC APEX EXPO, SMTAI, and PCB West. Stay up to date through trade publications, such as Design007 and PCB007 Magazine. If cost is not an issue, and you have an in- house fabrication and assembly shop, you can experiment with all kinds of options. Just be sure to research the physics so you don't hurt yourself or others. If cost is a factor (as it is for most of us) and you are sending the design out to find the low- est cost for fab and assembly, you may need to follow the guidelines a bit more diligently. You can still be creative but understand the tradeoffs for what you want to do. Work with the fabricator(s) you select and find out what's possible within your budget. Use the IPC-1730 and IPC-1720 specifications to be sure you've