Evaluation of Transistor Life Data

The purpose of evaluating transistor life data is to make possible proper application, specification and design of transistors. There are many methods of testing and analyzing life characteristics. These methods are reviewed and discussed here from the standpoint of the user, with emphasis on a particular statistical approach. Components are iritially evaluated at different temperatures to determine such general characteristics as current gain and leakage currents in the collector and emittor cutoff region. Samples are also submitted to mechanical and environmental tests. Life tests are conducted at various temperature and power levels. As a control feature, shelf life tests are usually performed simultaneously. Data collected from life tests are recorded on punched cards. Each card contains all the data for a given transistor at a particular time during the life test. This information is used as the input for an electronic calculator by means of which statistical summaries can be computed. The use of calculators accelerates the evaluation period and therefore allows more data to be analyzed efficiently. This method permits either individual or group. evaluation procedures. The results are presented on curves and charts.