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18 The PCB Magazine • August 2017 and it can be kept extra clean and conditioned. Also, you have a concept of no fume scrubbers. I think one time you wrote that, wherever pos- sible, you've elevated the temperature to facili- tate evaporation, which is one of the ways of re- cycling the chemicals. Stepinski: Yes, thermal energy instead of chem- ical energy. Goldman: Is the copper that you produce from etching usable in your copper plating process? Stepinski: Yes. It's been qualified but we don't put it in there right now. The concern is that in the theoretical world, it works fine. The con- cern is that someday, somebody is going to put in some copper that still has some ammonia on it or something like that, on fifth shift or something like this. I have this nightmare—this nightmare that has never happened to us, but it pops into my head in the middle of the night. We get paid 95% of the anode price anyway, so we're covering the cost basically. For 5% more, I avoid a lot of potential risk. But it has been cer- tified by Atotech to be reused. They don't do that lightly. Goldman: It's an insurance policy. Holden: The conductive polymer that replaces electroless copper—what are the trade-offs be- tween the two? Stepinski: Electroless copper is more expensive to maintain and analyze in a conventional fac- tory. It's also an environmental liability. We've done a lot of work to develop countermeasures so it's not an environmental liability in our factory. Goldman: How has it been working in the line? Has it been 100% reliable? Right now, I know you're mostly doing single- and double-sided. Stepinski: The conductive polymer is working fine. It's a no-brainer. I don't know of any is- sues. We do a low percentage of multilayer but have had no issues. It's an extremely reliable process. Holden: What is the mechanism of the conduc- tive polymer? Stepinski: The conductive polymer mechanism is putting down the permanganate, and the conductive polymer is an acid permanganate. You're actually precipitating manganese diox- ide onto the dielectric surface, and then the conductive polymer absorbs onto it and gets conductive enough to galvanically plate it up. Goldman: Because you're going right to panel plating in the acid copper, with just a few rinse steps. I suppose that helps. Stepinski: Yes, and the conductive polymer it- self has a pH of 1.9. The whole line is acidic permanganate polymer and galvanic copper. The conditioner on the front of the line is alka- line; it's just a wetting step. The only limitation with the conductive polymer process is that on more exotic materials it doesn't absorb as well. In those cases, you're in the electroless arena. Goldman: You mean anything beyond FR-4? Like polyimide or flex? Stepinski: No, we were able to do polyimide. We have flex and it's not been a problem. As long as there is no acrylic through the process. If you expose acrylic in the hole wall it will chew up the acrylic because of the high temperature of the acid permanganate which is at 90°C (the first step of the conductive polymer process). WHELEN ENGINEERING, TWO YEARS LATER Figure 5: Horizontal conductive polymer process.