Issue link: https://iconnect007.uberflip.com/i/1449048
40 DESIGN007 MAGAZINE I FEBRUARY 2022 Tise: ere's a whole lot of stuff that you must have defined up-front as design rules, writ- ten in stone before you ever start. DFM is not something that you necessarily have to use as a design input. It's just something that must be in place and written in stone and part of your culture, or you're going to build things that can't be built. at starts at the library creation and design rules creation, in the partnership between the designer and the fabricator. You bet- ter know where your fab shop's at, or you're going to send them something half-built, or they're going to really charge you for it. Also, you must worry about assembly as well, so that your boards can be built to the end. Dack: Yes. at's back to stakeholder awareness. We must remember the five Ws: who, what, when, where, why, and maybe how. Who is going to be building this? We must know their constraints. Again, that could be considered a milestone. I have an old friend from back in the '80s, when I was starting out. His unforgettable quote to me was, "Kelly, never design anything that can't be built." I cite this quote oen because it happens. It continues to happen over and over. We're working with suppliers who may use an addi- tive process because the product can be built at their facility. But then purchasing gets a lower quote from a supplier using a common subtractive process who ends up not being able to build the board. at would certainly add to the timeline, and probably shoot all the project milestones for miles down the road. Tise: When I was at Sunstone, it had to be some- thing that could be built. Otherwise, we'd say, "You've gone beyond the lines of what could be done in the normal circuit board manufac- turing process. Maybe there's somebody out there that can build this, but it's not me." You get down to the below a 0.3-millimeter BGA, and you're in trouble. Maybe they could use 3D printing to do the circuit board, but that gets outside of normal design constraints. Don't say, "I drew it, so you should be able to make it." You should start out saying, "What can your fab shop and your assembly shop do using nominal processes and nominal costs?" Rather than, "What's your highest level of technology?" Dack: Because of time-to-market issues, we're forced to ask, "Can we speed up the design cycle by concurrent engineering?" Matties: I get what you're saying, but there are still milestones in that, whether you're doing it concurrently or independently, you still need to have all the information. You still need the parameters. You still need the supply line, and you still need to know the fabricator. ese are all milestones. I think that's what you're say- ing, it's going to come, perhaps you'll know the fabricator at the end, in some processes, and others, you may know at the beginning, but it's still a milestone. Dack: It is. It's important to note that tradi- tional milestones are sequential. e story I Bob Tise