Issue link: https://iconnect007.uberflip.com/i/1470111
12 DESIGN007 MAGAZINE I JUNE 2022 I did design review a couple of years ago with a tier one soware supplier. I found that even if they were provided all the fabricator design rules electronically, they'd still have to per- form a lot of scripting to incorporate most of the provided DFM rules. A common example I give is the minimum space between a conduc- tor to the edge of a board. Is the edge scored? Is it routed? Is it punched? How are you mak- ing this? ese have different sets of rules, most likely, and the design doesn't necessarily have the right rules because the design system doesn't have knowledge of how the edge will be created. Over the years, we've just accepted this problem. In the '70s when I first got into this, we hand-taped artwork on Mylar. ey photo- graphically reduced it down to the proper size, and they built it. It was pretty simple. en we invented CAM tools. at was where we went downhill, along with the first manufacturer who said, "I'll fix your design for free." at's when design data quality went downhill. Happy Holden: Yes. I'm not sure that DWM is actually real, because who in manufacturing has that kind of time to devote to a customer? Dan Feinberg: My first thought is: Do you design for manufacturing, or do you design for the performance of the device? What comes first when you have to make a choice between cost and reliability? Korf: Right. ere are two problems for me. One is that board fabricators may not be selected until aer the design is done, and they're selected by procurement or the EMS company. ey go out, source it, then select the suppliers at the end of the layout. You don't know who you're designing for. I teach a DFM class for IPC, and one of the things I teach is the IPC definition of DFM. It's something along the lines of, "Design for optimum cost to manufacturability," and I add, "and meets the design intent." To your comment, Dan, you're really trying to make the board work first and then ensure it's producible. Cost is actually third, because if they all come back and they don't work, you've lost all your money anyway. I teach stu- dents that if you're going to design for a manu- facturer, figure out whether it's the right one for you. Not every fabricator can build every capability, and not everyone has the same set of design rules for a given technology. at's part of the problem, too. We're chasing cost/ price along with quality and performance. It's a triangle; the old saying is that you can only get two out of three of those. Shaughnessy: It sounds like a lot of these issues arose out of outsourcing. None of this hap- pened during the time of captives. Korf: at's right. When you had in-house manufacturing, the factory could be tuned toward the product and everything was opti- mized. You had a lot less variability, a lot better chance of getting good designs out, and get- ting them right the first time. But, even then, they still had data errors. Shaughnessy: Right. It sounds like a lot of Dana Korf