Issue link: https://iconnect007.uberflip.com/i/1527952
64 PCB007 MAGAZINE I OCTOBER 2024 to control that line width as you go on. at line width is really controlled by the photoli- thography process, not by an etching process. So, you can do 50-ohm impedance with closer to ±3% tolerance vs. the normal ±10% toler- ance window. You still have the dielectric and all those variants to be concerned with, but in my experience, we've held it very tight. Nolan: How does the cost compare for running LMI vs. traditional electroless? I cannot discuss cost in detail, but any cost increase should be balanced by performance, reliability, and yield far beyond what you can obtain using standard metallization processes. Smaller densities translate to running more parts per panel and may also allow for a reduc- tion in layer count, so that you get a reliability benefit with fewer microvia structures. If some- thing that might have been a 12-layer board can be redesigned to six layers, and with higher reliability and better yields, the additional cost to run the liquid ink processes becomes pretty moot. By contrast, if you were to take a board that is 6 x 8 inches, and you need to build to finer line widths with tighter tolerances with- out changing the size, your cost to manufacture will be significantly higher using your standard processes. is is a primary example of using the benefits that the technology can provide to everyone's best advantage. Andy Shaughnessy: What do PCB designers need to know about LMI technology? Would a designer do anything differently from a DFM perspective? When you look at the technology of ultra-fine lines, there are so many tools in a designer's toolkit today, though there are some that don't play well together when you have via-in-pad plated over. is is not really something that is specified in for ultra-fine lines because you're plating up, and you're filling holes with resin. en you're planarizing through basically a sanding machine. It's a little more sophisticated than that, but I liken it to a hammer and tongs approach to making a circuit board which is really a brutal way to treat the outer surface of that board. When you use traditional technol- ogy, even with sub-assemblies where you're trying to fill those vias and using different mate- rial types, your registration can stretch all over the place. It changes your dimensional registra- tion from layer to layer. It creates a lot of head- aches for a board manufacturer. But when you look at the ultra-fine lines, if you can put them on the second level down and make your connection using a microvia to 25-micron lines and space and 50-micron lines and spaces.