Easy Prediction of Degradation in Transistor Current Gain over Large Ranges of Operating Current

The neutron damage factor varies greatly with emitter current density. An easy formulation is given to predict this factor for any current using two intercept parameters and three almost constant slope parameters. The intercept parameters may be determined from measurements of DC current gain, hFE, made initially and after a neutron exposure at two chosen currents. This damage factor equation, initial minimum hFE specifications, and statistical weighting factors can be used to determine worst case hFE values over a large range of operating currents after neutron exposure. Confirming test results on many examples of popular transistors are tabulated.