Issue link: https://iconnect007.uberflip.com/i/1484263
32 PCB007 MAGAZINE I NOVEMBER 2022 differently in that space. e basic tools that you have, the direct imaging, and the really tight registration of your layers are all impor- tant. But then you start getting into etch factor adjustments in different areas, like the horns or making sharper square pads, and extreme reduction of copper on the surface becomes very important. Johnson: Do you need clean room facilities? Patel: Most board shops use a clean room already or at least the ones I've seen; we all have a clean room. On the imaging side, that's very important, but it's more than that. It's a whole new ball game. We've done the sequen- tial blind vias, but how do we plate those areas but also limit the copper surface and make sure the etching is still perfect every time for every layer set? e processes are very involved now. You need someone who can look at the data. Based on experience, you know how things are going to etch in that sub-2-mil space and adjust here and there. Johnson: Is there more custom tuning to get that ready to go? Patel: Yes, and everyone in that space is expe- rienced with semiconductor-level tolerances. ere seems to be a big learning curve for those designers because they're usually design- ing with that in mind. ere seems to be a bit of a knowledge gap on learning how a cir- cuit board factory works and the limitations of it all. Johnson: Yes, the dimensions on the sili- con 20 years ago weren't much smaller than the dimensions we're putting on the boards now. At that point for ICs, we were doing sil- icon in clean room environments and a great deal of standardization and process work and precision in that which doesn't seem to have migrated over into the printed circuit board manufacturing industry until now. How close are we to needing to have a clean room envi- ronment throughout the facility? Patel: I'm not entirely sure if we need a clean room for every system. But we need more control. Obviously, the imaging has always been a clean room setup, but the control of the plating and the control of the drilling becomes so much more critical. ere doesn't neces- sarily need to be a clean room throughout the whole department. For example, with a laser drill you need that vacuum system and the enclosed ventilation system in that kind of equipment whenever you're doing the actual process. With plating, it becomes more about chem- istry control. e fluid dynamics must be fine- tuned to make sure that you're even across the panel. at's what people are transition- ing toward, like the knife edge movement vs. the traditional rack movement of plating, enclosed vertical plating lines. So, the systems are becoming more controlled. I don't know if the whole line must be in a clean room, but it has to be less open to the environment. Sunny Patel