Issue link: https://iconnect007.uberflip.com/i/1520701
MAY 2024 I DESIGN007 MAGAZINE 29 I think the more producibility you put up front, the better your design will turn out. got to learn how to do certain things, meet certain requirements, and understand how to design a board. Board routing is one of those things. If you learn how to do boards, then you can get into electrical, mechanical, and sys- tems. It better defines your career. Dack: Let's get back to material constrain- ing. There's been a push to automate and make board stackups and selection of mate- rials easier. It's a double-edged sword, in my opinion, and I'm wondering if you agree that without training, these tools are making it too easy for material selection to become a problem. For example, at my EMS company, we get customer designs all the time where the designer has been led to the selection of material laminates that are outside the scope of availability. In other words, they'll pick a three-core or four-core material and select the prepreg materials, which go against DFM in many cases. Conse- quently, we'll get push- back from our suppliers who have to build this .0682257" thick board, asking us, "Can we use different laminate materials?" I've worked at some major companies, and they prefer that the electrical engineers pick the material types. ey have compartmentalized this whole process in the bigger companies. ey don't have us picking materials; somebody else, especially if it's RF, will pick the mate- rials they want. ey figure out the size and depth with all that volume. en we talk to the mechanical guy and ask, "How tall can we make the board in your housing?" I really don't get involved with picking materials anymore. But I know enough that when I see something, I'll say, "Are you sure about that?" It's because, over the years, you see things—and I have a long memory. Dack: A major problem that we've identified is that a designer often does not know where the board will be produced and, therefore, doesn't know which materials are available unless it's highly constrained and specified with a supplier part number. But in volume, a lot of times, it's not available, and the job stops. Do we want producibility to tell us what we can and can't do? Yes, and the company has bought into it. Now, any board that will be designed and sent out has to have a produc- ibility standard. Dack: So, there's a producibility audit before the design starts? Yes. Our producibility people have learned on the job, and they've come from board houses, and they know all about the materials and fab- rication lamination processes as well, so we're a step ahead. I think the more producibil- ity you put up front, the better your design will turn out. Dack: One quick story about an area where we fail in the EMS quoting scenario: We have cus- tomers who have a stackup defined but don't do a produc- ibility study. We'll go to our offshore suppliers and get a quote. Everything's good, so off we go to pro- duction. Three months later, we get an engineering query (EQ) from someone who says, "By the way, we need to substitute this material because it's not available. May we substitute this? We can't drill this hole diameter. Can we use that diameter?" It makes you wonder: Where did they get that stackup? Did they Google it (laughs)? Dack: So, Fil, what can be done? We use Polar Instruments for stackup set-up. I meet with my colleague Mark, our producibil-