SMT007 Magazine

SMT-Aug2018

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62 SMT007 MAGAZINE I AUGUST 2018 Feature by Joe Russeau PRECISION ANALYTICAL LABORATORY, and Mark Northrup IEC ELECTRONICS In a previous article, "It's Time to Retire ROSE Testing," we discussed the basis for why ROSE testing should be retired as an industry cleanliness or process control test. In this article, we reemphasize our position by highlighting some work we presented at the 2017 SMTA International Conference comparing component cleanliness results from the Resistivity of Solvent Extract (ROSE) against Ion Chromatography (IC) results. For those of you interested in reviewing that body of work, the working title was "PCBA Component Cleanliness Specifications Limits are Lacking." [1] The ROSE test has been used in the electronics industry since the early 1970s. It was originally developed to estimate the amount of residual rosin flux remaining on a printed board. The predominant flux from that era contained greater than 30% rosin. So, it should go without saying that modern day flux technology and circuit designs are vastly different from those 70s-era predecessors. By that same token, our methods for assessing the ionic cleanliness of printed board assemblies are vastly different as well, right? Well, not exactly. The ROSE test is still the most predominantly used ionic cleanliness test in our industry and in truth, it has not been modified or changed since the early 1980s. In addition, ROSE testing is not only used for determining the ionic cleanliness of printed boards and printed board assemblies, but it is also being used for evaluating the cleanliness of components [2] . In the previous article, Mark and I indicated that there were two important attributes necessary for evaluating the ionic cleanliness of PCBs and PCBAs. These attributes would be considerably more crucial for evaluating components. We said that those two attributes were selectivity and sensitivity. To properly evaluate ionic cleanliness, it is important to use as little extraction solvent as possible (to concentrate the residues to the area being evaluated) and to have a system that can Is Component Testing Using ROSE Practical?

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