BS IEC 62396-5:2014

FOREWORD
1 Scope
2 Normative references
3 Terms and definitions
4 Overview of thermal neutron single event rate
  calculation
5 Thermal neutron flux inside an airliner
6 Thermal neutron SEU cross-sections
7 Recommendation for devices in avionics at the
  present time
8 Determining thermal neutron SEE rates for use in
  equipment assessments
9 Single event burn out in high voltage devices due to
  thermal neutrons
Bibliography

Gives a more precise definition of the threat that thermal neutrons pose to avionics as a second mechanism for inducing single event upset (SEU) in microelectronics.

The purpose of this part of IEC62396 is to provide a more precise definition of the threat that thermal neutrons pose to avionics as a second mechanism for inducing single event upset (SEU) in microelectronics. There are two main points that will be addressed in this part of IEC62396 : a detailed evaluation of the existing literature on measurements of the thermal flux inside of airliners, and an enhanced compilation of the thermal neutron SEU cross-section in currently available SRAM devices (more than 20 different devices). The net result of the reviews of these two different sets of data will be two ratios that are considered to be very important for leading to the ultimate objective of how large a threat is the SEU rate from thermal neutrons compared to the SEU threat from the high energy neutrons ( E>10MeV). The threat from the high energy neutrons has been dealt with extensively in the literature and has been addressed by two standards ( IEC62396‑1 in avionics and JESD89A [1] 1 in microelectronics on the ground). Neutrons with E>1MeV are considered for parts with geometries below 150nm. NOTE Reference is made to IEC62396‑1:2012, 5.3.2, for smaller geometry parts below 150nm which provides the neutron flux for energies above 1MeV.