Circuits Assembly Online Magazine - NASA Tests Find Novel Cleaning Fluid Best Alternative to nPB

WASHINGTON, DC – The US National Air and Space Agency recently compared trials on a variety of products to see if its demanding standards could be achieved with newer alternatives to cleaning with normal propyl bromide.

At the time of the test, NASA was using nPB in critical cleaning applications. The study by Mark Mitchell of the Marshall Space Center and Nikki Lowery of Jacobs Technology compared alternatives to nPB1. The tests compared the effectiveness of three new alternatives, including Chemours (ex-Dupont) Vertrel SDG specialty fluid.

The tests were strictly controlled. Test coupons were prepared, made from a steel alloy, magnesium and aluminum. The contamination was a mix of aircraft grease, a synthetic hydraulic fluid and a small quantity of carbon black. The contaminant was applied to the test coupons, baked for two hours at 55˚C and aged for seven days. For the cleaning tests, the coupons were immersed in boiling solvent for 30 min., observed and weighed.

As a benchmark, the test showed nPB removed 96% of the contamination. All of the others did “in the range of or better than” nPB. When tested on a roughened coupon instead of a smooth polished metal surface, all three products surpassed nPB.

While the authors cautioned their results are not to be considered any sort of a commercial endorsement, they concluded the Vertrel SDG fluid “cleaned the most consistently.” Additionally, “all but Vertrel SDG showed reduced cleaning effectiveness on aged contamination.”

The authors cautioned additional operational, commercial and toxicity factors should be considered before finalizing a solvent selection.

“The requirement for safer and greener alternatives for critical cleaning is becoming a number one priority for companies,” said David Ferguson, product manager for Precision Cleaning Products at MicroCare. “As we can see from the test results from NASA, it is clear there is no longer any need to use nPB-based cleaners today. There are viable choices on the market that are substantially safer than nPB.”