Abnormal Increase in the Conductivity of Polyimide Substrates Used for Flexible Printed Circuit Boards at High Accumulated Radiation Doses
Experimental studies of the electrical conductivity of polyimide films used as substrates for flexible printed circuit boards for spacecraft applications have been irradiated with electrons in vacuum to high accumulated doses (>1 MGy). It has been shown that the electrical conductivity of polyimide under irradiation increases significantly and at high accumulated doses can exceed the limit specified by GOST for the minimum resistance between printed conductors. This effect does not manifest itself in near-Earth orbits but can play a negative role when using such printed circuit boards, for example, in a spacecraft planned to launch in 2026 to Jupiter, in whose orbit the radiation exceeds the near-Earth by hundreds of times. A model of conductivity growth is proposed, and based on this model, a criterion is defined, and an engineering technique is developed for predicting the durability of polyimide substrates of flexible printed circuit boards for spacecraft applications based on electrophysical parameters at high radiation levels.