edfas.org ELECTRONIC DEVICE FAILURE ANALYSIS | VOLUME 28 NO. 3 14 SSC over time. Over a hundred sample tests were analyzed as the proper sampling parameters and sequences were determined. Environmental and aging effects were assessed and storage conditions were also identified. The net result was that RGA sample data recorded from this sample source during any testing scenario had a precision of ±1.5% (i.e., ±75 ppm(v)). Having demonstrated that the SSC could deliver multiple samples with the same composition, the next phase of developing the standard was to test it at other laboratories. After one final series of analyses, the SSC was shipped to other certified laboratories. Each lab performed the required daily internal calibrations before taking sample tests from the SSC. A problem occurred when the SSC arrived at one facility with one of the valves broken off at the tank interface. NASA agreed to having the SSC repaired and to perform a recharge process using the same techniques used during the initial charging. Testing then continued and the final RGA assay at the originating lab once again yielded a precision of ±1.5%. Unfortunately, NASA was suddenly faced with a mandate to cease all R&D efforts. Funding was stopped, the SSC was put into storage, and the data was never assembled into a final report. Approximately seven years later, the Dept. of Energy (DOE) expressed interest in the effort and was willing to fund another series of SSC tests. Hence, the SSC was taken out of hibernation and was once again tested and retested. The performance was as before, i.e., no discernible change in the composition of the SSC contents. Even the argon content had barely shifted after years in storage. So again, after one final set of analyses, the SSC was transported (i.e., hand carried for “eyes on” purposes this time) to the various laboratories for RGA analysis. Even after long-term storage, newly performed RGA measurements demonstrated a precision of ±1.5%. A final report of the results was completed and forwarded to the DOE for their dissemination. In the 2024 Minnowbrook Conference, an overview of the results from this most recent SSC data was presented and compared in detail to the results of the previous two studies. Because discussions at Minnowbrook are open, but never published or released in any manner, a request was made by NASA/JPL to combine all the data from the three studies done over the twenty years into one report. That report is one of the references cited in the Suggested References. It summarizes the years of effort expended by a host of technologists in an effort to create a consensus standard for the RGA testing of moisture in microelectronic devices. CONCLUSION This article is a very simplified account of how Test Method 1018 for the determination of moisture in microelectronic devices evolved. The method has been demonstrated as reliable and provides a means by which different test laboratories can demonstrate their measurement capabilities using the same sample source. It should be noted that a large amount of additional historical information and details were intentionally set aside in this telling to keep things brief. Although references were not noted in the text, a few select citations listed below provide greater detail and insight into some of the above discussions for the interested reader. SUGGESTED REFERENCES 1. Test Methods and Procedures for Microelectronics, MIL-STD-883, U.S. Department of Defense. 2. P. wh Schuessler: “Moisture in Microelectronics: Physics and Chemistry of Volatile Species in Hermetic Electronic Devices,” Lulu Press, 2017. 3. J.E. Shelby: “Handbook of Gas Diffusion in Solids and Melts,” ASM International, 1996. 4. P. wh Schuessler and S.M. Sierzant: “The Development of a Consensus Standard for Moisture,” Microelectronic Devices, NASA Contract: 80NM0018D0004, Jan 2025. 5. T.J. Green and R. Lowry: “Why Three Monolayers of Moisture are Important,” TJ Green Associates LLC, white paper, 2016. ABOUT THE AUTHOR Philipp wh Schuessler did his undergraduate and graduate studies at the Rochester Institute of Technology. He started his career at IBM/FSD in 1963 and remained in that division until retirement 1996. Thirty years of consulting followed in the arena of failure analysis of microelectronic devices. His years of research and development, failure analysis, and materials analysis have essentially been centered around the effects of moisture in and on micro and macro devices. Schuessler served as chair of the Minnowbrook Microelectronics Conference for 42 years before retiring.
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