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16 The PCB Magazine • August 2017 is an unnecessary process, it's non-value added. It was originally designed as a subtractive etch process. We were able to modulate the plating recipes to pulse the right amount of roughness on at the last anodes, and we were able to elimi- nate the subtractive etch with the roughness or stripping process after inkjet so it would in ef- fect strip it and do tin plating and handle sur- face treatment because we're plating it in. Even though it's there, we're not using it. I didn't know we'd be able to get that good. Holden: Is anyone else using a horizontal pulse plater to improve the resist adhesion? Stepinski: It was recommended to us by Atotech. They said they had a handful of accounts that had been able to achieve it. What we had to do was do the DOE to see what roughness worked best with the inkjet ink. The inkjet ink has ex- tremely good adhesion, and you can't make it too rough. The product is so thin that when it hits the surface, it penetrates every crack, every nook and cranny in the crystal structure, unlike a dry film, which is extremely viscous, and you have to push it in. Holden: Is that UV-cured or thermally cured? Stepinski: This is a UV-cured product. It gets a dose of 900 millijoules. Holden: And that machine has a built-in AOI. Is there anything else built-in? Stepinski: No, that's basically it. It's the AOI, and cure and coating. Holden: And the pinless lamination saves a lot of process steps. Since you're not using pins, you don't have the messy caul-plates to deal with. Stepinski: Or maintenance program, yes. Holden: It's an optical alignment, and then kind of a welding of the layers together. Goldman: How well does that work? Stepinski: For our technology, it's fine. Holden: I noticed the rotary oxygen plasma etch replaces all the permanganate desmear. Does that have sufficient throughput? Stepinski: Yes. Goldman: The rotary plasma etch, though, that's really a batch process. How automated can you make that? Somebody has to load and unload right? Stepinski: Yes, and the plasma machine is a lim- iting factor with higher volume. You're not go- ing to get 100 plasma machines by a chemical desmear line. For us, the rotary plasma machine makes sense. Holden: Because of the high level of automation and the minimum of any kind of delay, there's an elimination, a lot of outer layer and inner- layer pre-etch, acids, and things like that that people have because panels are sitting around. Stepinski: Fingerprints. Holden: Those all have to be eliminated. If it's not touched by people then there's no chance. Plus, your equipment is really designed under the concept of a microclimate. The building is not specifically climate-controlled because there's a microclimate inside of the process area Figure 4: Horizontal pulse plater. WHELEN ENGINEERING, TWO YEARS LATER