Improved Surge Step Stress Testing of Tantalum Capacitors 1. For Ta capacitor manufacturer: Selection of tantalum capacitors with different types and constructions such as MnO 2 -based, reactive-polymerized, and pre-polymerized. For the purpose of simplicity and consistency with previous testing results, 6.3V rated capacitors are preferred; up to 10 V rated may be used. Only pre-polymerized polymer Ta capacitors rated at 25V will be used for SSST (availability issue). All Ta capacitor samples should be in D case (EIA 7343 footprint) with same or similar capacitance values. All Ta capacitors should be solder reflowed on a testing board by following MIL-PRF-55635, paragraph Three groups of testing boards will be populated for SSST under three different transient patterns, i.e., underdamped, critically damped, and overdamped, with no more 10% overshoot, or undershoot. 2. For NEPP study at GSFC: One hundred (100), minimum, different capacitor samples will be tested under the three different transient conditions identified bullet above, for a total of three hundred (300). The SSST conditions to attain the three (3) different transient patterns will be achieved by changing the test circuit parameters, as well as the capacitor bank values (between times the values of the capacitor under test). Transients during charge and discharge are to be monitored using an oscilloscope to confirm the achievement of desired transient patterns. Description:FY12 Plans: Schedule Lead Center/PI: GSFC, David (Donhang) Liu NASA and Non-NASA Organizations/Procurements: All electrical testing will be performed at Code 562 Electrical Testing Laboratory. All testing samples will be pre-screened, selected, and populated on testing boards by the manufacturer. Deliverables: This study represents a proposed collaboration with a tantalum capacitor manufacturer to address shortcomings in surge current testing of tantalum capacitors. The three main proposed collaboration study elements are summarized below: (1). Use of the Surge Step Stress Test (SSST) method to characterize the capacitor failure mechanism under time varying stresses (time- to-failure) and to differentiate the performance of different capacitor technologies; (2). Re-test various tantalum capacitors under different transient conditions (including slightly underdamped) to verify SSST testing results of tantalum capacitors performed last year for NEPP. The results have caused some controversy when presented at CARTS 2011 conference; (3). Incorporate modifications from the current MIL-PRF for surge current test into previous year’s SSST protocol. This study will attempt to determine the physics of highly rated voltage Ta capacitors failing in low voltage applications. It will also reveal the surge breakdown capabilities of recently developed pre-polymerized Ta capacitors. The results will leverage both manufacturer and the end user like GSFC on how to screen and select Ta capacitors for better reliability and performance. The results will provide a characterization of surge current breakdown of Ta capacitors. Attempt to explain the physics of failure of highly rated Ta capacitors under low operating voltages. Address the concerns on the use of SSST for characterization of Ta capacitors.