Measurement of mechanical properties of electronic materials at temperatures down to 4.2 K

Operating temperatures of spacecraft components in the ‘subzero’ range are encountered during solar eclipse periods or when voyaging on deep-space missions. Moreover some spacecraft instruments or parts of them, e.g. sensors, have to be cooled to obtain an improved performance, e.g. in spacecraft missions like the infrared space observatory (ISO) and CryoSat. Materials utilized in the assembly of electronic circuits can be subjected to mechanical loading at cryogenic temperatures. [Semerad E, Scholze P, Schmidt M, Wendrinsky W. Effect of new cleaning liquids on electronic materials and parts. ESA metallurgy report no. 3275; January 2002, [1]].Within the present work the mechanical properties of electronic materials at cryogenic temperatures down to liquid helium temperature were analysed. Specifically the tensile properties of solders (63Sn37Pb, 62Sn36Pb2Ag, 60Sn40Pb, 96Sn4Ag, 50In50Pb, 70Pb30In, 96.8Pb1.5Ag1.7Sn, 96.5Sn3Ag0.5Cu), PC boards (MLB polyimide glass fibre, MLB epoxy glass fibre, MLB Thermount), conformal coatings (Arathane 5750, Sylgard 184, Scotchcast 280, Solithane 113, CV-1144-0, Mapsil 213, Conathane EN4/EN11) as well as OFE Cu were characterised at room temperature, at liquid nitrogen and at liquid helium temperature by tensile tests.The fracture surface of tested samples was examined by means of optical microscope and if necessary with scanning electron microscope.