PRODUCTION ENGINEERING MEASURE FOR IMPROVED RELIABILITY OF SOLID TANTALUM ELECTROLYTIC CAPACITORS.

Approximately 1,400 22 microforads, 50 volt capacitors meeting all quality requirements of MIL-C-39003 Group A acceptance inspection and also exhibiting a failure rate less than 0.001 per thousand hours were made in the Production Run. Ability to achieve the failure rate goal while using tantalum powder from several sources was demonstrated. All such capacitors showed acceptable parametric values, although some differences among sources were evident. Meticulous care in performance of every process step was found to be an important ingredient in uniform production of high-reliability capacitors. Small errors might have only a marginal effect on performance when failure rate is not a prime consideration, but the same errors can lead to catastrophes when low failure rates are needed. The value of accelerated life testing was demonstrated in that each batch of capacitors, even though relatively small in size, could be tested for failure rate within two weeks time and thus provide rapid feedback for proper adjustment of process conditions. Author