PRODUCTS FINISHING — PFonline.com
17
Shaving the Whisker Problem
Reducing tin and zinc whiskers on finishes are a major
issue for electronics. short.PFonline.com/whisker
TABLE 3: Results of ASTM B117 Salt Spray Testing, Hours Passed
SALT SPRAY RESISTANCE
(HOURS PASSED) BY ALLOY
METALAST TCP HF SURTEC 650V BONDERITE M-NT 65000
MAP SILICO
{3-5 UM}
2024-T3 0 504
*
0 0
2024-T8 0 0 0 0
6061-T6 672 672 672 168
7075-T6 168 672 504 168
7075-T73 336 672 504 168
* 2 of 3 panels passed at 504; 1 panel was still passing at 672
Coatings – Surface Treatments Screening Test Report." In general,
NASA and ESA saw similar results for salt spray testing.
Next Steps
NASA and ESA will continue working together to develop
hexavalent chrome-free coating systems for spaceflight appli-
cations. Next steps include testing of full coating systems;
including pretreatments with primers and pretreatments with
primers and topcoats. The test plan for continued testing is
being finalized and expected to start in the summer of 2016.
Previous screening-level testing of pretreatments with
primers was performed and is reported in "NASA and
ESA Collaboration on Hexavalent Chrome Alternatives –
Pretreatments and Primers Screening Final Test Report." There
is also interest in evaluating materials stored in cleanrooms
and other longterm storage facilities.
Kurt Kessel is with ITB Inc., and works at the NASA Principal
Center for Technology Evaluation for Environmental Risk
Mitigation at the Kennedy Space Center in Florida. He can be
reached at kurt.r.kessel@nasa.gov. The author thanks Thomas
Rohr with ESA ESTEC, Fatema Janjali for coordination and
testing support at ESA ESTEC, Jerry Curran for coordination and
oversight of the KSC Corrosion Technology Laboratory and the
KSC Beachside Atmospheric Test, and Teddy Back for test panel
preparation and coating application at KSC.
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