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Are the stackup rules we used to follow no longer valid? It depends on what you’re designing. 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. The 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 magazines.
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 lowest 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 asked the fabricator and assembler all the right questions. The things that are called out are somewhat customizable per fabricator, and using these specs will help you get consistent answers and fabrication price quotes.
Hole sizes and aspect ratios, component pin spacing, and product sizes are getting smaller all the time. How can we navigate the demands of these conditions with the existing manufacturing processes that exist out there?
To read this entire article, which appeared in the December 2024 issue of Design007 Magazine, click here.
