Issue link: https://iconnect007.uberflip.com/i/1533085
60 DESIGN007 MAGAZINE I MARCH 2025 have you built this type of product before?" If he tells you once, maybe he's not the right fab- ricator. You'll likely get what you paid for. One thing that used to annoy me about designers was the comment, "You're always asking me lots of technical questions. e other guy never asks questions." I would say, "Go with the other guy, but come back and see us when the boards don't work. We'll see you in another couple of months. He will have changed your design, and you have no control over that." I've seen that happen during my time in aerospace and defense. Twenty to 30 years ago, changes just got made without any documentation. en I would go to another fabricator, and they'd say, "Wait a minute. I can't build this the way it is. We need to make changes." at's because the original changes were made over a phone call and the docu- mentation was never updated. Dack: I have a feeling some of our prototype suppliers might be feeding the monster by say- ing that they can do anything and then doing exactly that. We've accused some prototype suppliers of building things electron by electron. They will deliver anything and make it work for two or three pieces and say that the process is dialed in. But then they send it through pro- duction expecting to build tens of thousands of them offshore, and it doesn't work. e most famous saying from a designer is, "I will fix it in rev 2." I've seen that happen. One board we built was basically a one-up. We told the designer, "If you can shave 150 mils off one dimension, we can make this a two-up." e designer said, "I'll do it on rev 2." By rev 6, thousands of panels later, at $17,000 a panel, we finally went to the two-up, so it's not a set form factor. I tell designers to talk to every stakeholder who's involved. It matters how many we can fit on a panel, and that's what you're paying for the product. But on prototypes, we would do a yield cal- culation. We would plug in all the attributes and then come back with, "We're estimating about an 80–85% yield. You probably know where you want to go for production. Change this, change that, and we could probably get the 90–95% yield." A prototype shop can build one or two of anything but they may build 10 to give you two. at yield may be 10-20%, but the proto fab won't mind because they're going to charge you for it. Dack: Is your DFM tool a third-party tool or have you developed a tool? I used to use Frontline Genesis. ey had a really good front-end tool. All our application engineers used it, which allowed me to do a complete front-end tooling. We developed a DFM report for the designer with recom-