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K.J. Karcich, A. Buck, J. Wyatt, D. Shire, M.D. Gingerich, C. Scholz, J. Rizzo; A System for Leakage Testing Of Flexible Electronic Components . Invest. Ophthalmol. Vis. Sci. 2004;45(13):4183.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Develop a "soak testing" system capable of measuring small leakage currents to test the efficacy of various encapsulants as hermetic sealants of microelectronic components in thin film substrates. Methods: A "soak testing" system was developed building on our earlier work (J. Wyatt; D. Edell). The Keithley 6514 electrometer and Keithley 7001 switch system was used, controlled by an IEEE interface equipped Dell Dimension PC. Control software was developed in the MatLab programming language that initialized the Keithley hardware, controlled the settling interval, switched between test components and cycled thru leakage measurements for a predetermined number of test cycles. One hour settling time was used between subsequent switching and measurements. Connections between the switch/electrometer and the device were conductive epoxy or a circuit board "sandwich" which clamped the array connector paddle. Flexible micro electronic components ( FAB: D. Shire; Coated: S. Cogan) were placed in a grounded Faraday cage. The flexible components were polyimide, coated with several test coatings. Results: The systems were able to repeatedly measure leakage currents to fractions of picoamps. Environmental conditions within the Faraday cage impacted leakage. High humidity levels in the cage increased the leakage on the "sandwich" connector, but had minimal effect on the conductive epoxy connectors. Since the "sandwich" type connector was preferred, the decision was made to flush the Faraday cage with dry nitrogen gas to eliminate humidity. Nearby electromagnetic fields made some locations unsuitable for leakage testing due to noise; the sensitivity of our system system could only be realized in quiet electromagnetic zones. Conclusions: An automated soak testing system has been developed that can easily and automatically measure leakage currents in the fractional picoamp range. Environmental influences must be carefully assessed if the system is to be stable and reliable.
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