Issue link: https://iconnect007.uberflip.com/i/1481368
OCTOBER 2022 I DESIGN007 MAGAZINE 17 Snogren: When you look at printed circuit boards on the high-end cellphones, watches, and things like that, almost all of that is mSAP. e semi-additive process really is being used more on the packaging substrates, and they're using either electroless copper or vacuum- deposited copper on those products. I don't know that many circuit board manufactur- ers are trying to use semi-additive process- ing in volume anyway. But with Averatek, the licensed companies are starting to use that. It's certainly a viable way to approach it. Shaughnessy: You mentioned that our process, our technologies, should learn to be more like the semiconductor industry, that we should learn from them. What are some things that we should take away from the way semi- conductor manufacturers have been doing it? Snogren: When they design a factory, it's around a capability. ey deal with a process node and tech- nology node, and if you're a semiconductor designer, you design into that node, you design into that fac- tory. ey don't just accept any design. ey give you the design criteria in a file and you must follow that criterion. If you don't, they don't build it. Shaughnessy: We had a magazine focused on design rules several months ago. With ultra HDI, will we need to have some uniform design rules and constraints? Snogren: We need some general ones, and my IPC committee is working to develop those guidelines. We are developing a general guide- line so designers know when they need to diverge from IPC-222x and IPC 60xx standards. We're trying to make it process agnostic as much as possible. We want it to be more general, sug- gesting that the designers talk to and work with their suppliers more closely on the design because they may use multiple techniques to fabricate the job. We haven't even talked about fully additive with inkjet printing conductors. Johnson: When we start talking about UHDI, do you see that as the tipping point where cleanroom technology needs to happen? Is UHDI where we move to just greenfield facili- ties? Snogren: For volume, yes. If you want to do volume and repetition, and do things with good yields, there's no doubt in my mind that's the case. For small companies in the U.S. that want to offer that as a capability, I don't really know where we start to run into the hurdles. I've been running some test- ing on 25-micron lines and spaces here and I haven't gotten to the point where it's become an issue, but we haven't really done a lot of volume. A dedicated facility is the way I would go for high volume. For an existing HDI factory, I believe one can produce small quantities of UHDI product with a decent cleanroom for the imaging pro- cesses and good filtration in electroless copper and electrolytic copper plating. Johnson: Now it starts to feel like integrated circuits where, as you were saying, you build the factory around a particular technology. It feels like we're on the cusp here of having the cutting-edge printed circuit board fabrication philosophy start to look like IC.