It is generally accepted within the reliability discipline that component failures occur when the strength of the component ie less than the stresses imposed. Due to the unavoidable variations in processing and materials, it will not be unusul to find component or product strength distributions that are bimodal in nature, consisting of a mixture of two Weibull distributions (i.e. weak and strong component distributions). This paper presents an analysis of both field performance and burn‐in data collated over a period of time on one particular type of display unit which clearly exhibits some form of bimodality. The text also explains in detail the manner in which optimum burn‐in duration can be computed via a Weibull plotting technique or by applying the sequential burn‐in procedure. Copyright © 1987 John Wiley & Sons, Ltd.