IEC 62396-5:2014

Overview

IEC 62396-5:2014 - Process management for avionics: Atmospheric radiation effects - Part 5 provides a focused, standardized assessment of the threat posed by thermal neutrons to avionics electronics. The standard defines how thermal neutron fluxes inside airliners and the single event upset (SEU) cross-sections for microelectronic devices (notably SRAMs) should be evaluated so that thermal-neutron-induced single event effects (SEE) can be quantified and managed in avionics systems.

Key topics

• Thermal neutron definition and measurement: Review and processing of in-flight measurements and calculational approaches to estimate thermal neutron fluxes within typical commercial airliners.
• SEU cross-section compilation: An enhanced compilation of measured thermal neutron SEU cross-sections for currently available SRAM devices (more than 20 devices), enabling comparison with high-energy neutron effects.
• Two critical ratios:
  • Ratio‑1 - thermal neutron flux relative to high-energy (>10 MeV) neutron flux inside an aircraft.
  • Ratio‑2 - thermal neutron SEU cross-section relative to high-energy neutron SEU cross-section. (This edition updates Ratio‑2 data; the reported average was revised from 2.77 to 2.42.)
• Procedures for estimating SEE rates: A method to derive thermal-neutron SEU rates by multiplying established high-energy neutron SEU rates by Ratio‑1 and Ratio‑2, and guidance on conservative estimation where test data are lacking.
• Device and system recommendations: Guidance on demonstrating thermal neutron immunity (including thermal neutron testing and consideration of boron‑10 content), special attention to small geometry devices, and a section on thermal neutron single event burn-out risks in high-voltage devices.
• Standards evolution: This edition upgrades the previous technical specification to an IEC International Standard and includes updated references and bibliography.

Applications

IEC 62396-5 is used to:

• Calculate and include thermal-neutron-induced SEU contributions in avionics system reliability and safety assessments.
• Inform radiation-hardened design and selection of SRAM and other microelectronic components for aircraft systems.
• Guide test laboratories and certification bodies in demonstrating thermal neutron immunity and estimating SEE rates for equipment qualification.
• Support system architects, avionics engineers, radiation-effects specialists, and component manufacturers in risk assessment and mitigation planning.

Related standards

• IEC 62396-1: atmospheric radiation effects - accommodation of SEEs within avionics equipment.
• IEC 62396-4: design of high-voltage aircraft electronics managing potential SEEs.
• JESD89A: ground-based microelectronics neutron testing guidance.

Keywords: IEC 62396-5:2014, thermal neutron flux, single event upset (SEU), SEU cross-section, avionics systems, atmospheric radiation effects, SRAM, Ratio-1, Ratio-2, thermal neutron immunity.