Issue link: https://iconnect007.uberflip.com/i/1533085
56 DESIGN007 MAGAZINE I MARCH 2025 Paul Cooke: I'm trying to teach a three-day course in one day. We go through the whole fab- rication process, focusing on how the design is affected by fabrication. e scary thing is that 80–85% percent of designers have never been to a board shop. It's not even about communi- cation and language; it's about not understand- ing fabrication. When I talked to them about a drill or aspect ratio, some asked, "What's that?" When I was teaching a design class about two months ago, I asked, "How many of you have read the design spec IPC-2221?" Only one designer raised his hand, and that was an "Oh, wow" moment for me. So, never mind about language; many designers really don't understand the whole process of fab. When I teach, my objective is to get all of my fab knowledge into their heads so that they understand what's highly affected and what's not. I want them to understand annular ring and material selection. ey need that knowledge so they can do a better job of getting the fabricators involved. Shaughnessy: Are these attendees long-time designers? Not always. You have to understand how designers are made. Oen, someone is work- ing for a company as an electrical engineer, and the company needs to do a layout. e manager thinks about the engineer and says, "Hey, you should be able to do that. It's only a four-layer, double-sided board." Five years later, he's the layout guy, and he rarely talks to the fabrica- tor. He does his design and throws it over the wall. When I was in field applications, I would sometimes report that we couldn't build a customer's board, and they would ask, "What do you mean?" I'd answer that their lines and spaces were wrong and explain that when we select materials, we select them to match the impedance. If we can't match it, we have to look at changing trace widths or spacing. Sometimes fabs will make changes that remove the non-functionals. When we tell them we can do 4 mils spacing, they will run the copper 4 mils away from the hole, and we tell them why that won't work due to CAF con- cerns. It sounds like simple stuff, but not every- one fully understands it, and the last thing you want is to go back and tell designers they have to redesign the board they've just spent three months designing. Kelly Dack: Paul, what is the biggest area of concern for designers, and what do they need to understand most? For example, we've had customers with designs specifying 2-ounce base copper, and they put 3-mil lines in the design. How do we stop that? Paul Cooke