Reliability Demonstration and Field Analysis of a Communications Controller

This paper sets out to demonstrate the suitability of reliability growth models for reliability prediction during reliability demonstration and in the field for a communications controller.The paper describes reliability demonstration tests, a failure review process, reliability prediction and follow up field reliability analysis for the communications controller. The reliability was demonstrated by simulating the product early life through two types of tests. One sample was run at ambient conditions and the other sample at accelerated conditions. In order to corroborate the demonstrated reliability, field failure data of a product sample was collated and analysed. A good correlation in reliability measures between the demonstrated and field observations was achieved.In both test samples similar failure modes were observed. The acceleration factor of the stressed sample was estimated by modeling time to first failures using the Weibull model. This enabled combination of both test data. Through the ‘test analyse and fix’ process steered by a failure review board, a number of modifications were introduced to eliminate recurring failures. As a result, the demonstrated reliability of the product improved significantly. Weibull process model was applied to model the combined test data for reliability prediction.The field performance of a sample of products was monitored for approximately one year. These systems also exhibited reliability growth. This was mainly due to natural screening. Weibull process and IBM models were applied to this data. Good agreement in reliability measures, demonstrated with field observations was observed.The failure review board was seen as an effective vehicle to instigate corrective actions in the reliability demonstration program. The Weibull process and IBM models were suitable to model repairable systems failure data in the presence of reliability growth.