Issue link: https://iconnect007.uberflip.com/i/1470111
JUNE 2022 I DESIGN007 MAGAZINE 13 can knock 20% off the thickness of that Mylar sheet, that's a significant cost reduction." We were building hundreds of millions of square feet of dry film a year. It was a big deal. Korf: Sometimes, purchasing will require you to swap out one resist for another because it's cheaper, and the yields go south. You've got to understand the process impacts before you change. Shaughnessy: Dana, in our last issue, we focused on designing in a vacuum, and how DWM could help designers "get out of the vacuum," as we say. Many of our design readers, and even process engineers in fab and assembly, say that they feel like they're basically work- ing by themselves much of the time. You were working at a high-volume level in China. Did your team ever have to make do without all the information you needed? Korf: at's a very good question. Actually, I'm working with a large OEM right now who wants to improve their documentation pack- age so they will stop getting all these questions back. I was going through their prints and ask- ing, "Do you know what this note means?" e response was, "No, I don't even know what it means. What do you think it means?" en I talked to the fabricator. I said, "You don't seem to ask a lot of questions about the prints. Why don't you?" He said, "Well, we assume..." If you're a front-end person, the second you assume, you assume wrong. In a this stuff is just absorbed. ey budget in the money, resources, and time on respins. Korf: I think it's just an acceptance of our indus- try. In the IC industry, if they design an IC, it gets built. ey don't go back and forth and do three or four versions, because they can't afford it. But our industry, unfortunately, has accepted—and I hate to use the phrase—send- ing bad data to be built. If every manufacturer just built exactly what they were sent and the designer's company had to pay for the result, I think it would get fixed really fast. I used to tell customers, "You're paying us for a three-day turn to make your board in three days, but we spend seven days trying to get the data right. You just spent three-day turn money on a 10-day turn." It would usually catch someone's attention and they'd say, "Oh, yeah, you're right." Feinberg: Do you ever get asked to redesign something for lower costs, for example, or bet- ter reliability? Korf: Yes, and it's more common than you think. e product would fail during develop- ment testing. e electrical noise was too high, something mechanical, or something thermal. "Can you adjust something in the design data a little bit?" To reduce costs, what can a fabrica- tor do aer a design is completed? It's usually adjusting the materials. You can't go in and say, "Please re-layout this whole section or reduce two layers." We'd oen say, "If you want to reduce costs, take two layers out. Take four layers out. But you have to do that; we can't." Usually, it involves just tweaking material sets. A lot of customers come in, and every three months they've got to reduce the price by X percent. Feinberg: It's not just the design of a circuit board. When we were designing new pho- toresists, when we were designing new dry films, we could look at it and say, "Gee, if we Sometimes, purchasing will require you to swap out one resist for another because it's cheaper, and the yields go south.