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50 DESIGN007 MAGAZINE I DECEMBER 2023 Is it a special process? Can board shops use their existing process- ing equipment and tanks, or do they have to put anything special in place? at's the interesting thing with this technology; there are very few tanks put in place to get it set up, and very few additional lines to be run. You can use existing lines for flash etching. For exam- ple, we use our inner layer clean line—with a micro etch—to do the flash and it functions quite well. But the whole process is just using different photoresists that have the reso- lution capability down in the 25-micron range. As long as you have something that can resolve to that range and make the narrow lines, you're golden. So, it's not quite a drop-in, but pretty close? Yes, it's pretty close. In fact, we have some examples of product we put in for the U.S. Navy, which has been one of the early adopt- ers. Within two weeks we were running panels there that had 25-micron line and space, and the capability with their photolithography to get down further. A few weeks aer that, we were running 15-micron, down to 12.5-micron (0.5 mil) line and space. Let me tell you, as someone who has been in this industry a long time, it brought tears to my eyes. It's just beau- tiful; that spiral pattern was just awesome. It was zero shorts and zero opens. It's just a really good process. In Figure 2, we have a comparison between the A-SAP process and the ultra-thin foil pro- cesses that are sometimes called mSAP in Asia. e older mSAP processes started out with a 5-micron foil, an eighth-ounce copper as we would call it in the older days. Now there are foils that are 2-micron and even as thin as a 1.5-micron. So, even with these copper weights, you're still dealing with a fairly thick base foil that you have to etch. But when you etch something that is only two-tenths of a micron base, it etches very quickly and doesn't touch the electroplated sidewalls. Please talk about your straight edges. This is incredible. It's really staggering to look at how straight those trace sidewalls are. On the le, you see the trace that's been plated. It still shows the electroless down at the base and you can see how thin it is. is trace here is 11 microns wide and it's about 27 microns high, I believe. When you do the flash etch, you look at that trace and it's like it hasn't been touched. It's really amazing; it's hard to beat that sidewall. That's just phenomenal. All those rules from way back are now out the door with aspect ratio and surface-to-hole plating. This really is a game changer. Look for Part 3 of this interview in the Janu- ary 2024 issue of Design007 Magazine. DESIGN007 Steve Williams is president of The Right Approach Consulting. He is also an independent certi- fied coach, trainer, and speaker with the John Maxwell team. To read past columns, click here. Figure 2: A comparison between the A-SAP traces before and after etching.