a. The use of component test data used in conjunction with total ionising dose results to predict degradation shall be agreed with the customer.
NOTE The objective is that these data are produced from irradiations performed using particles with sufficient energies to traverse the sensitive part of the device and doses defined through application of the methods defined in the clauses of ECSS-Q-ST-60 relevant to “Radiation hardness”. It is important that the testing conditions are appropriate to the final operating conditions, for example:
• That the electrical and environmental test conditions (e.g. voltage bias, temperature) are equivalent to the expected operating environment for the device, or be such as to give rise to more severe TID effects.
• That the time period over which the radiation dose is delivered is considered when comparing the dose received in the operational environment and under test conditions. Some bipolar devices (e.g. bipolar linear integrated circuits) exhibit greater radiation sensitivity when exposed to ionising radiation at lower TID rates, whilst others such as MOS-based devices suffer lower radiation effects if exposure takes place over a longer time.
• That the irradiation by different radiation types is equivalent. For example, dose enhancement effects can be experienced in the shielded bremsstrahlung field in electron-rich orbits due to presence of high-Z materials close to sensitive volumes, whereas these are not represented in a proton or 60Co irradiation.