Soldering is expected to become an increasingly important process as supportability concepts are developed as part of NASA’s new exploration initiative. Avionics repair at the component level offers the potential for substantial reductions in the mass and volume requirements required for spares. Soldering will be an enabling capability for this approach.

Since 2001, the National Center for Microgravity Research, NASA’s Johnson Space Center, and NASA’s Glenn Research Center have engaged in a collaborative effort to study influences of reduced-gravity environments on the soldering process. Extensive reduced-gravity experiments have been conducted onboard NASA’s KC-135 reduced gravity research aircraft. These experiments have focused on nominally 0-g conditions but have included a limited number of tests under partial-g conditions representative of lunar and Martian environments and some intermediate acceleration values. These tests have shown that acceleration values have a distinct influence on internal porosity and external solder joint geometry. Tests have also been conducted to explore alternative process protocols to address some of the less desirable effects.

While activities utilizing the research aircraft continue, a limited test in support of this effort was performed onboard the International Space Station (ISS) during Expedition 6. Analysis of the samples produced in this test must wait until their return upon resumption of Shuttle flights to ISS. Also, a more extensive test to be performed on ISS is in preparation.