Reliability Testing for Hostile Environments

To insure the reliable operation of electronic components under the different environmental conditions encountered in the field, IBM has established an environmental reliability program. The intent of this program is to first simulate field conditions and then to develop. accelerating laboratory conditions. This paper deals with the required hostile environment engineering. Emphasis is placed on simulation techniques, environmental guidelines and types of degradation mechanisms which could result in equipment malfunction. The experimental dosages are based on the concentration range of gases and particulates which are present in polluted city atmospheres. The requirements. and considerations used in designing and choosing simulation systems will be briefly discussed. The requirements include the ability to vary the dosing concentration by at least three orders of magnitude in the parts per million-parts per billion range, and to use ´in situ´ pure gas dilution rather than prediluted gas mixtures. An additional requirement is to use as many as six or more dopant gases. These requirements and the difficulties inherent in simulation systems have caused us to adopt certain design criteria. These include dynamic mode of operation rather than a static mode, as well as a modular dosing technique. This dynamic mode of operation permits on-line concentration adjustments and periodic or semi-continuous automatic monitoring. The dosing technique used allows us to use two dosing devices - permeation tubes and a dynamic serial dilution device as building blocks for achieving multi-gas dilution over a wide concentration range.