| Summary: | The threshold logic method used for electronic products when assessing their reliability in the form of predicting the performance class of products for a given operating time (K1 is a class of operable ones, K0 is a class of inoperable copies) provides for the transformation into a binary code of informative parameters obtained at the initial moment of time, and allows to build a forecasting model in the form of a table showing which code combinations correspond to the instances of the K1 class. The use of a binary transformation simplifies the forecasting procedure, but the reliability of the predictions is slightly reduced. It is relevant to obtain a forecasting model that has the simplicity of its application and provides a higher reliability of forecasting a class of products than with a binary transformation of parameters. On the example of bipolar transistors of the KT872A type, the regularities of electrical parameters used as informative ones are established, and for their transformation into a code, it is proposed to consider three areas of parameter change: the first area is the range of values between the mathematical expectations obtained separately for instances of the classes K1 and K0; the other two areas are the parameter values to the left and right of this range. Parameter values falling within the range are assigned the R code (from the word Range), outside the specified range - the code 1 (one) or 0 (zero), depending on the pattern of the informative parameter. It is explained how to convert parameters to codes 1, 0 and R and get a prediction model in the form of a logical table built from these codes. Basing on the example of the investigated transistors, it is shown that the proposed heuristic model provides the best forecasting results, practically keeping the simplicity of the basic method of threshold logic.
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