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History & Future of Resistivity Of Solvent Extract (ROSE) Testing

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  • Brook Sandy-Smith: So a really hot topic nowadays is the J Standard One from IPC planning the ops lessons of the ROSE test method. Could you give us a little bit of history behind the ROSE test method.
    Phil Zarrow: Sure. The ROSE or Resistivity of Solvent Extract test is basically ancient. We actually go back to late 50's, early 60's with this particular test, and one of the interesting things about it is it's essentially very empirical. The ideas is, yes seemed to indicate cleanliness, if it doesn't meet this, it doesn't, so what are you actually testing there. But bear in mind also, that going back then, those were simpler times. Circuit boards were so much simpler. First of all they were through-hole, when it was adapted, second of all, we had very high resin resin content fluxes, 50% plus and we had now banned substances that we can clean them with, Freon and trichloric, so those were simpler times.
    Brook Sandy-Smith: Mm-hmm. And now, 70 years later ...
    Phil Zarrow: 70 years, yeah.
    Brook Sandy-Smith: The components are smaller, everything is closer together, you have different flux technology that doesn't just use one resin, it might use modified resin and lots of other things and on top of that, we have these bottom termination components and other low stand off components that are very difficult to clean under.
    Phil Zarrow: Right. So the time has come, the walrus said, to find it as something more, shall we say, apropos, much more, and I would say scientific as well as far as testing. This is 70 year old technology. It's amazing it's gone on this long, but now it is the focus of finding a replacement methodologies.
    Brook Sandy-Smith: in the J Standard One, it's really pertaining to how do you measure the cleanliness of your cleaned assemblies. But you can see people also using this in no clean processes to try and figure out how much ionic residue they are leaving behind from a no clean flux, which kind of doesn't make sense either.
    Phil Zarrow: No, it doesn't. It doesn't.
    Brook Sandy-Smith: Especially to use one limit.
    Phil Zarrow: Right. Well that was the other thing, it's been long recognized that for the most part in the industry, there is not one test, one panacea, if you will, for determining cleanliness, so you're right. We need to probably look at it from multiple perspectives, if you will. And what exactly are these that we want to do, but it certainly isn't ROSE.
    Brook Sandy-Smith: Right. Well if you were looking for more information on upcoming test methods, we have other videos in this electric chemical migration series that might be interesting for you, or as always you can contact me directly at Thanks, Phil.
    Phil Zarrow: Brook, always a pleasure. Thank you.