Issue link: https://iconnect007.uberflip.com/i/1533085
MARCH 2025 I DESIGN007 MAGAZINE 61 mendations. I would tell them to run the DFM early in the design. Don't wait until the purchase order is placed because we're probably going to ask for some changes, and that'll delay the whole process. Dack: I imagine that your DFM audit process works because you've set the constraints within the tool to your known capabilities. Correct. Now, if you're doing that audit process with the same designer all the time, he's learning. e next time he does a design, he remembers what he can and cannot do. He'll get the stackup first before even laying it out. He'll lay out the most complex part of the design, and then run a DFM. You're helping him become a better designer. e last thing a designer needs is for you to come by and say, "You have to redesign this board because it's going to be a low-yield or problematic." ey like to think the fabricator is an expert on materials and CTEs. I try to explain that the fab is not; he doesn't know about material science. He just looks over the slash sheets, picks a material and off he goes. Unless you tell him, he doesn't know where your board is going; he doesn't know the environment it's going into. LaRont: At your UHDI Symposium presenta- tion in Phoenix, someone mentioned that their project was going up in the air, and that every- thing had failed due to moisture. They won't tell you the actual application sometimes, but they should at least describe the environment. Right. You don't have to tell us exactly what it is, but you have to at least imagine some conditions. For example, let's say it's an engine controller in an aircra and the environment will see -50ºF in the air to 120ºF on the ground in Arizona every day. You want that board to last 20 years. Material selection has to be well thought through. Luckily, most of the mil-aero guys have experts who will test the material. But it's a challenge. Shaughnessy: This has been great, Paul. Thanks for speaking with us. ank you all. DESIGN007 by Martyn Gaudion, Polar Instruments Introduction: This is a guide for those invo- lved in the procurement, design, or fabrication of high-speed impedance or insertion loss- controlled PCBs and complex HDI PCBs requir- ing detailed documentation. While a follow-up to The Printed Circuit Designer's Guide to Secrets of High-speed PCBs, Part 1 and Part 2, this book stands on its own. Here, I introduce new topics but have also included some of the previous content where updates in technology have enabled different approaches to design, measurement, documentation, and modelling. Whilst the laws of physics haven't changed since writing the first two books, the capability of material suppliers to better tailor base mate- rials to applications, developments in via filling, and more com- plex stackups, mixed with improvements in precision depth drilling, mean more tools are available for designers to duck some of the chal- lenges, and to model behaviours that were complex and challenging a decade ago. I wrote this book in a way that will benefit PCB designers, engineers, and procurement teams with electrical, process, or mechanical backgrounds, or anyone who wants to learn more about what can and can't be achieved when a suite of CAD layout data and its asso- ciated stackup are submitted to the fabrica- tion process. Continue reading... BOOK EXCERPT The Printed Circuit Designer's Guide to... More Secrets of High- Speed PCBs