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August 2016 • SMT Magazine 91 7TH ELECTRONIC MATERIALS AND PROCESSES FOR SPACE WORKSHOP sion; this provides for a simple design resulting in a high reliability with ultimately lower costs. The recent designs are very suitable for use on- board the many hundreds of solar powered small/cube satellites being built by universities and institutes. Sarinova Simandjuntak, (University of Portsmouth), then reviewed the performance of sensors that have the potential to be used for the detection of corrosion or damage within electronic cables and connections. Spacecraft launch sites are frequently located in marine environments (e.g., the Kennedy Spaceflight Centre in Florida and the Kourou Spaceport in French Guiana). The proposed sensor designs are expected to detect degradation of both pow- er cables and communication cables between launch complexes and on-site command cen- ters. This technology is certainly of value to the wind power industry where turbines are located off-shore and where such saline environments have caused costly failures to power lines. Area Grid Arrays are usually terminated with solder balls or solder columns. Wilfried Akalmavo from HCM- Systel, France, described how such terminations can be removed and then replaced by far more robust columns of solder that are reinforced with very fine copper tape. Advanced electronic packages support- ing the reinforced copper-SnPb columns have been evaluated to an "ESA-ECSS capability and verification test plan". The extensive program described in detail by Akalmavo, demonstrated that the refurbished AGAs have passed environ- mental testing (comprised of thermal shocks, 1,500 thermal cycles and vibration) with flying colors. Rajan Bedi (Spacechips Ltd) ended this session with a talk that described selected tech- nical requirements for the next generation for spacecraft electronics. The final workshop session, entitled Inter- connection materials, was kicked off by Dong Junking of the Chinese Academy of Space Tech- nology (CAST). She presented an overview of spacecraft assembly capabilities in China and described their visual inspection and x-ray re- quirements for column grid array packages. Typical defects were illustrated and an account given as to how they could be minimized dur- ing processing. Her second presentation was a review of the development and challenges asso- ciated with RF-MEMS packages for integration into spacecraft. Known good die (KGD) testing for best electrical properties is seen in Figure 7. RF-MEMS packages are considered more critical than IC packages, especially for space applica- tions. This is due to effects of both radiation and RF loss – caused by miniaturized designs and exposure to thermal-mechanical stresses during operation. An extensive overview of the work per- formed under ESA contract by Aerospace & Ad- vanced Composites GmbH (Austria), was pre- sented by Michael Scheerer. He discussed the results of testing the electrical resistance, mi- crostructure and mechanical performance of a wide range of solder alloys. These included the SnPb, SAC and InPb solders prescribed by ECSS Q-ST-70-08 for specific applications. Properties were assessed from cryogenic, to room- and el- evated-temperature environments. Microstruc- ture features were equated to creep resistance, mechanical properties and modes of failure. The influence of grain boundaries on electrical resistance could be verified (smaller grains lead to higher electrical resistance). The presence of voids in solder joints have been a focal point for electronic manufactur- ing engineers since the start of the Space Age. Until 1997, internal voids were not consid- Figure 7: KGD testing during MEMS assembly for a satellite light phased array antenna (Courtesy of CAST).