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Proceedings Paper

Use of design of experiments techniques to investigate resistance change of chip resistors in MESSENGER
Author(s): Manny Uy; Ronald Hardesty; Johnny Fogle; Andrew Moor
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Paper Abstract

A 25 full factorial designed experiment was performed in order to investigate the cause of the increase in resistance of various precision resistors used in the MESSENGER spacecraft. Even though the largest increase was less than 5 %, it was troubling because the cause of the resistance change had not been determined other than the usual suspects of ESD, solder tip temperature, environmental stress screening (ESS) or corrosion (disputed by the commercial manufacturer). Because of the need to quickly resolve the root cause of this change, it was decided to study all the variables simultaneously by the use of Design of Experiments (DOE). The five variables studied were the different resistor types, operating voltages, solder tip temperatures, temperature cycling, and the highly accelerated stress test (HAST). The statistically significant findings are: 1) The most probable cause of the increase in resistance is moisture ingress through the old passivation layer inherent with only one chip resistor type. The old passivation coating is not as impervious to moisture as the new passivation coating on the other resistor type. The failure mechanism is therefore a chemical reaction, most probably the oxidation of chromium present in the nichrome resistor element to form a non-conductive chromium sub-oxide. 2) To a much less significant extent, the higher solder tip temperature of 700 F and the higher test voltage (e.g. 40 volts) contribute to a higher resistance change. Materials analyses of the coatings explain the difference in moisture permeation rates.

Paper Details

Date Published: 7 September 2006
PDF: 11 pages
Proc. SPIE 6291, Optical Systems Degradation, Contamination, and Stray Light: Effects, Measurements, and Control II, 629102 (7 September 2006); doi: 10.1117/12.678542
Show Author Affiliations
Manny Uy, Johns Hopkins Univ. (United States)
Ronald Hardesty, Johns Hopkins Univ. (United States)
Johnny Fogle, Johns Hopkins Univ. (United States)
Andrew Moor, Johns Hopkins Univ. (United States)


Published in SPIE Proceedings Vol. 6291:
Optical Systems Degradation, Contamination, and Stray Light: Effects, Measurements, and Control II
O. Manuel Uy; John C. Fleming; Michael G. Dittman, Editor(s)

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