Issue link: https://iconnect007.uberflip.com/i/1479191
42 PCB007 MAGAZINE I SEPTEMBER 2022 that even if you get the losses down to that level, it's still not good enough. ere's analysis about whether the loss-budget gains you get vs. the cost will be worth it or even possible. at's what most of the large material folks are working on now. In the RF space, they're pretty much just working on better con- trolled RF materials to get the cost down. Korf: When I was working in C h i n a , I w a s s e e i n g d i g i t a l designers looking at RF materials to get their losses down. e RF folks were looking at digi- tal performance materials to get the cost down, and that's still going on. I see that most of the material development work is primarily being driven to reduce the loss, Df, primarily in the digital space. ere are umpteen varieties of FR-4, so they seem to be covering the market well; the high voltage for automotive is stress- ing the specs a little bit, but not too much. What's interesting on the material side is we're starting to look at non-glass alternatives. As John mentioned, we're looking at quartz again, like we did in the 1980s. e problem with quartz glass is that when you hit it with a laser, it melts and balls up. It doesn't evapo- rate away. at was a challenge many years ago when we tried it. Johnson: at makes it tough for laser applica- tions. Korf: It does make it interesting. Johnson: What are some of the nontraditional materials being evaluated? Strubbe: We can talk about the coppers getting down to zero roughness, what's going on there, and limitations. Does it stick to the resin at the end of the day? Like a lot of technologies, they tend to cycle every 20 or 30 years, and improve with every cycle. Fundamentally, it's stuff that's been looked at before. Johnson: What's going on with FR-4 and are there other mate- rials being looked at? It seems a lot like Moore's law in ICs: We're on the verge of making it fail, and now what that we've made it fail? Korf: I made a presentation last month on materials technol- ogy and attendees asked, "Why do we have all these different materials for low loss?" I said, "It's a result of how it was invented. We could only go this far, so we did. en the next year we reduced the loss a little lower based on available material technology. en we went a little lower. But as we achieved lower loss, the earlier materials suddenly became more attractive because they were less expensive than the newer low loss materials." Manufac- turers could adjust the composition and it was still usable. We would have gone straight from A to Z if we could have, but we couldn't. e interim versions tend to hang around because they found niche applications for lower costs. Johnson: What are your thoughts on a materi- als pivot? Korf: e goal is to not go into fiber optics. e industry is trying to keep away from fiber optics as much as they possibly can. e battle cry is, "Stay on copper." Johnson: How does this address materials, material choices, in general, for designers? We were just having a conversation about additive and if you redesign to what's available in addi- tive, you can oen eliminate multiple layers from your design, from 16 down to eight, for example. Dana Korf