Issue link: https://iconnect007.uberflip.com/i/1464168
APRIL 2022 I DESIGN007 MAGAZINE 19 do certain workarounds for this, or is it fairly intuitive? Torp: I'd say it's fairly intuitive. e same laws of physics apply, and they just get more accentu- ated when you start to get into finer lines and spaces. Eventually, you reach a signal integrity barrier that is hard to design around, espe- cially when everything gets tighter and tighter together. You start to look at the edge effects, or the skin effects, that the copper has. You can't have any imperfections in the side walls of the copper, and the surface topography of the cop- per must be pretty consistent in order to get the signal integrity right, and to be able to model it. Shaughnessy: I know the designers will like the straight walls of the traces. But is there any downside to the straight walls. I'm sure it has an effect on impedance, right? Torp: Yes. Obviously, the conductor has a sig- nificant influence on the impedance and the signal integrity. You don't want variations in that conductor width as you move the signal through the conductors. e surface rough- ness also has some influence over the high-fre- quency applications. Matties: What advice are you giving designers who are considering additive or moving into additive? Torp: From the design perspective, my words of wisdom are to look at what's realistic in terms of registration. As you go through the lamina- tion process, materials move. Each layer moves in relationship to each other so getting your registration right and making sure that you can actually align layer to layer to layer, the way you intended it to. It has to do with the signal integ- rity. Registration, at least with the manufactur- ing piece of it, is one of the biggest challenges to overcome. Make sure the board fabricator, or the substrate fabricator, can achieve those levels of registration. Matties: You say this market is growing. What year-on-year percentage increase are you see- ing in additive? Torp: At this point, the percentage increase is in the double digits CAGR on year-on-year. I think we will reach an inflection point, prob- ably in 2023-24, where it really sets up in sig- nificant volume. Right now, very few manufac- turers are capable of the types of technology that the industry would like to move forward into as more fabricators and more manufactur- ing capabilities exist, particularly within the U.S. footprint. You're going to see an inflec- tion point that goes from what is state-of-art to what is a revenue center of gravity. I anticipate that occurring sometime between the end of 2023 and end of 2024. Matties: For designers who are doing high-speed and RF, over the next several years they will probably need learn additive designs, correct? Torp: Yes, I would say within the next two and a half years, they must be a step toward additive and semi-additive processes, and a step away from that fully subtractive technology. Matties: Aside from spacing and finer features, are there any other reasons somebody would go to additive?