IEC 62396-2:2017

IEC 62396-2 ®
Edition 2.0 2017-12
INTERNATIONAL
STANDARD
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Process management for avionics – Atmospheric radiation effects –
Part 2: Guidelines for single event effects testing for avionics systems
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IEC 62396-2 ®
Edition 2.0 2017-12
INTERNATIONAL
STANDARD
colour
inside
Process management for avionics – Atmospheric radiation effects –

Part 2: Guidelines for single event effects testing for avionics systems

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 03.100.50; 31.020; 49.060 ISBN 978-2-8322-5098-3

– 2 – IEC 62396-2:2017 © IEC 2017
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Abbreviated terms . 7
5 Obtaining SEE data . 9
5.1 Types of SEE data . 9
5.2 Use of existing SEE data . 9
5.2.1 General . 9
5.2.2 Heavy ion data . 10
5.2.3 High energy neutron and proton data . 10
5.2.4 Thermal neutron data . 11
5.3 Deciding to perform dedicated SEE tests . 11
6 Availability of existing SEE data for avionics applications . 11
6.1 Variability of SEE data . 11
6.2 Types of existing SEE data that may be used . 11
6.2.1 General . 11
6.2.2 Sources of data, proprietary versus published data . 13
6.2.3 Data based on the use of different sources . 14
6.2.4 Ground level versus avionics applications . 19
6.3 Sources of existing data . 19
7 Considerations for SEE testing . 22
7.1 General . 22
7.2 Selection of hardware to be tested . 22
7.3 Selection of test method . 22
7.4 Selection of facility providing energetic particles . 23
7.4.1 Radiation sources . 23
7.4.2 Spallation neutron sources . 24
7.4.3 Monoenergetic and quasi-monoenergetic beam sources . 25
7.4.4 Thermal neutron sources . 26
7.4.5 Whole system and equipment testing . 27
8 Converting test results to avionics SEE rates . 28
8.1 General . 28
8.2 Use of spallation neutron source . 28
8.3 Use of SEU cross-section curve over energy . 29
8.4 Measured SEU rates for different accelerator-based neutron sources . 32
8.5 Influence of upper neutron energy on the accuracy of calculated SEE rates –

Verification and compensation . 32
Annex A (informative) Sources of SEE data published before the year 2000 . 34
Bibliography . 35

Figure 1 – Comparison of Los Alamos, TRIUMF and ANITA neutron spectra with
terrestrial/avionics neutron spectra (JESD89A and IEC 62396-1) . 15

Figure 2 – Variation of high energy neutron SEU cross-section per bit as a function of
electronic component feature size for SRAM and SRAM arrays in FPGA and
microprocessors . 17
Figure 3 – Percentage fraction of SEU rate from atmospheric neutrons contributed by
neutrons with E < 10 MeV . 18
Figure 4 – Comparison of monoenergetic SEU cross-sections with Weibull and piece-
wise linear fits . 31

Table 1 – Sources of existing data (published after 2000) . 20
Table 2 – Spectral distribution of neutron energies . 32
Table A.1 – Sources of existing SEE data published before the year 2000 . 34

– 4 – IEC 62396-2:2017 © IEC 2017
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PROCESS MANAGEMENT FOR AVIONICS –
ATMOSPHERIC RADIATION EFFECTS –

Part 2: Guidelines for single event effects
testing for avionics systems
FOREWORD
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International Standard IEC 62396-2 has been prepared by IEC technical committee 107:
Process management for avionics.
This second edition cancels and replaces the first edition published in 2012. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition.
a) improvements and changes to test facilities have been added in Clause 7, which includes
new facilities at TSL, TRIUMF and ChipIr,
b) links with IEC 60749-38 and IEC 60749-44 are made in 7.1.

The text of this International Standard is based on the following documents:
FDIS Report on voting
107/316/FDIS 107/318/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 62396 series, published under the general title Process
management for avionics – Atmospheric radiation effects, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
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– 6 – IEC 62396-2:2017 © IEC 2017
INTRODUCTION
This industry-wide international standard provides additional guidance to avionics systems
designers, electronic equipment manufacturers and their customers for determining the
susceptibility of electronic components to single event effects. It expands on the information
and guidance provided in IEC 62396-1:2016.
Guidance is provided on the use of existing single event effects (SEE) data, sources of data
and the types of accelerated radiation sources used. Where SEE data is not available
considerations for testing are introduced, including suitable radiation sources for providing
avionics SEE data. The conversion of data obtained from differing radiation sources into
avionics SEE rates is detailed.

PROCESS MANAGEMENT FOR AVIONICS –
ATMOSPHERIC RADIATION EFFECTS –

Part 2: Guidelines for single event effects
testing for avionics systems
1 Scope
This part of IEC 62396 aims to provide guidance related to the testing of electronic
components for purposes of measuring their susceptibility to single event effects (SEE)
induced by neutrons generated by cosmic ray interactions in the Earth’s atmosphere
(atmospheric neutrons). Since the testing can be performed in a number of different ways,
using different kinds of radiation sources, it also shows how the test data can be used to
estimate the SEE rate of electronic components and boards due to atmospheric neutrons at
aircraft altitudes.
Although developed for the avionics industry, this process can be applied by other industrial
sectors.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 62396-1:2016, Process management for avionics – Atmospheric radiation effects – Part 1:
Accommodation of atmospheric radiation effects via single event effects within avionics
electronic equipment
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 62396-1 apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
4 Abbreviated terms
ANITA Atmospheric-like Neutrons from thIck TArget (TSL, Sweden)
BL1A, BL1B, BL2C beam line designations at the TRIUMF facility (Canada)
BPSG borophosphosilicate glass
ChipIr beam line at the ISIS neutron source facility (Rutherford Appleton
Laboratory, UK)
CIAE China Institute of Atomic Energy
CMOS complementary metal oxide semiconductor
COTS commercial off-the-shelf
– 8 – IEC 62396-2:2017 © IEC 2017
CUP close user position, neutron beam facility (TSL, Sweden)
CYRIC CYclotron and Radio Isotope Center (Tohoku University, Japan)
D-D deuterium-deuterium
DRAM dynamic random access memory
D-T deuterium-tritium
DUT device under test
E energy
EEPROM electrically erasable programmable read only memory
EMC electromagnetic compatibility
EPROM electrically programmable read only memory
ESA European Space Agency
eV electron volt
FinFET fin field effect transistor
FIT failures in time (failures in 10 h)
FPGA field programmable gate array
GeV giga electron volt
GNEIS Gatchina Neutron Spectrometer (Russia)
GSFC Goddard Space Flight Center
GV giga volt (rigidity unit)
IBM International Business Machines
IC integrated circuit
ICE Irradiation of Chips and Electronics
IEEE Trans. Nucl. Sci. IEEE Transactions on Nuclear Science
ISIS neutron beam source (Rutherford Appleton Laboratory, UK)
IUCF Indiana University Cyclotron Facility (USA)
JEDEC JEDEC Solid State Technology Association
JESD JEDEC standard
JPL Jet Propulsion Laboratory
LANSCE Los Alamos Neutron Science Center (USA)
LET linear energy transfer
LETth linear energy transfer threshold
MBU multiple bit upset (in the same word)
MCU multiple cell upset
MeV mega electron volt
NASA National Aeronautical and Space Agency
PCN product change notification
PIF Proton Irradiation Facility (TRIUMF, Canada)
PNPI Petersburg Nuclear Physics Institute (Russia)
PSG phosphosilicate glass
QMN quasi-monoenergetic neutron
RADECS RADiations, Effects on Components and Systems
RAL Rutherford Appleton Laboratory (UK)
RAM random access memory
RCNP Research Center of Nuclear Physics (Osaka, Japan)
SBU single bit upset
SDRAM synchronous dynamic random access memory
SEB single event burn-out
SEE single event effect
SEFI single event functional interrupt
SEGR single event gate rupture
SEL single event latchup
SEP solar energetic particles
SER soft error rate
SET single event transient
SEU single event upset
SHE single event induced hard error
SRAM static random access memory
SW software
TID total ionizing dose
TNF TRIUMF neutron facility (TRIUMF, Canada)
TRIUMF neutron beam source (Vancouver, Canada)
TSL Theodor Svedberg Laboratory (Uppsala, Sweden)
WNR Weapons Nuclear Research (Los Alamos, USA)
5 Obtaining SEE data
5.1 Types of SEE data
The type of SEE data available can be viewed from many different perspectives. As indicated,
the SEE testing can be performed using a variety of radiation sources, all of which can induce
single event effects in electronic components. In addition, many tests are performed on
individual electronic components, but some tests expose an entire single board computer to
radiation fields that can induce SEE. However, a key discriminator is deciding on whether
existing SEE data that may be used is available, or whether there really is no existing data
and therefore a SEE test on the electronic component or board of interest has to be carried
out.
5.2 Use of existing SEE data
5.2.1 General
The simplest solution is to find previous SEE data on a specific electronic component. Data
may be available on SEE caused by heavy ions, protons, high energy neutrons, or thermal
neutrons. Heavy ion data is normally only applicable to space applications, where direct
ionization by the primary cosmic ray flux is of concern. However, heavy ion data can be useful
for screening purposes, as described in 5.2.2. Proton data is usually also gathered for space
applications, where primary cosmic rays and trapped particles are of concern. However, high
energy protons provide a good proxy for neutrons in SEE measurements, as they undergo
very similar nuclear interactions with electronic component materials. Therefore, both existing
neutron data and existing proton data may be applicable to the evaluation of SEE rates in a
device of interest, as described in 5.2.3. Low-energy (“thermal”) neutrons can also cause SEE
in some electronic components but such data is only available on a very small number of
electronic components (see 5.2.4) and it involves neutron interactions with boron-10 rather
than silicon.
– 10 – IEC 62396-2:2017 © IEC 2017
Electronic components are constantly changing. In some cases, electronic components which
had been tested become obsolete and are replaced by new electronic components which
have not been tested. The fact that an electronic component is made by the same vendor and
is of the same type as the one it replaced does not mean that the SEE data measured in the
first electronic component applies directly to the newer electronic component. In some cases,
small changes in the electronic component design or manufacturing process can have a large
effect in altering its SEE response. In addition, electronic component manufacturers typically
follow JESD46 [1] for product change notices (PCNs) to inform customers of component
design changes. JESD46 [1] recommends a part number change when a die shrink or die
foundry or die process change occurs but not when the die metallisation layout is altered,
which can also lead to different SEE results. All SEE test data published therefore should
refer to the specific manufacturer, the specific die geometry and full component part number.
5.2.2 Heavy ion data
An important resource that can be utilized to eliminate electronic components are the results
from heavy ion SEE testing carried out to support space programs (~80 % of the electronic
components tested for space applications are tested only with heavy ions). This heavy ion
SEE data can be used to calculate SEE data from high energy neutrons and protons by
utilizing a number of different calculation methods, but this requires the active involvement of
a radiation effects expert in the process. Heavy ion testing is characterized by the LET (linear
energy transfer) of the ions to which the ICs are exposed. The LET is the energy that can be
deposited per unit path length, divided by the density (units of MeV·cm /mg). With neutron
SEE, secondary particles or recoils created by the neutron interactions act as heavy ions, and
the highest possible LET of neutron-induced recoils in silicon is ~15 MeV·cm /mg [1, 2]. Thus,
any electronic component tested with heavy ions that has a LET threshold > 15 MeV·cm /mg
will be immune from neutron-induced SEE. In a recent paper summarizing SEE testing at
NASA-GSFC [3], twenty-one ICs of various types were tested with only heavy ions and eight
of them (~40 %) had LET thresholds > 15 MeV·cm /mg for diverse SEE effects.
However, for the rare commercial SRAMs that are susceptible to SEL from heavy ions [4], this
susceptibility can be increased due to the presence of small amounts of high Z materials
within the IC, for example tungsten plugs, because higher Z recoils are created which can
cause SEE reactions due to their higher values of LET. The high Z materials also lead to
higher proton and neutron SEL cross-sections due to the neutron/proton reactions producing
these recoils with higher LET and energy. Therefore heavy ion SEL cross-sections need to be
examined carefully for applicability to proton-neutron SEL susceptibility caused by embedded
high Z materials in the SRAMs. A suggested conservative value of LET threshold above which
an electronic component can be considered immune from SEL induced by neutrons is
40 MeV·cm /mg [4]. However, this caution does not apply to the primary rationale given
above for eliminating some electronic components from consideration for neutron SEE
sensitivity based on heavy ion SEE testing, since only some electronic components
incorporate these higher Z materials and the limitation applies to SEL.
Heavy ion SEE data should not be used for application to the atmospheric neutron
environment for calculation of neutron cross-section, except by scientists and engineers who
have extensive experience in using this kind of data. Unless otherwise stated explicitly, when
SEE data is discussed in the remainder of this document, it refers only to single event testing
using a neutron or proton source, not to the results from testing with heavy ions.
NOTE IEC 62396-1:2016, B.3.2, provides an approach to transforming heavy ions data into proton/neutron SEE
cross-sections.
5.2.3 High energy neutron and proton data
If SEE data on an electronic component of interest is found from SEE tests using high energy
neutrons (for example ground level testing as per JESD89A [10]) or protons, it will still require
expertise regarding how the data is to be utilized in order to calculate a SEE rate at aircraft
___________
Numbers in square brackets refer to the Bibliography.

altitudes. Data obtained by electronic component vendors for their standard application to
ground level systems is often expressed in totally different units, FIT units, where one FIT is
one error in 10 electronic components hours, which is taken to apply at ground level.
5.2.4 Thermal neutron data
There is little data on thermal neutron cross-section. However a number of the spallation
neutron sources including TRIUMF, TSL and ISIS (Vesuvio) contain a substantial percentage
of thermal neutrons within the high energy beam. Using thermal neutron filters or time of flight
it is possible at such sources to determine thermal neutron cross-section. In addition there are
a number of dedicated thermal neutron sources and these are listed in IEC 62396-1.
A continuing problem with the existing SEE data is that there is no single database that
contains all of the neutron or proton SEE data. Instead, portions of this kind of SEE data can
be found published in many diverse sources. The SEE data in the larger databases is mainly
on much older electronic components, dating from the 1990s and even 1980s, and is primarily
from heavy ion tests that were performed for space applications and not from testing with
protons and neutrons.
5.3 Deciding to perform dedicated SEE tests
If existing SEE data is not available, for any one of the many reasons discussed above and
which will be further expanded upon below, then one should refer to IEC 62396-1 for the other
alternatives; in case there is no real alternative, SEE testing can be considered. The
advantage of such a test is that it pertains to the specific electronic component or board that
is of interest, but the disadvantage is that it entails making a number of important decisions
on how the testing is to be carried out. These pertain to selecting the most useful test article
(single chip or entire board), the nature of the test (static or dynamic (mainly applicable to
board testing)), assembling a test team, choosing the facility that provides the best source of
neutrons or protons for testing, scheduling and performing the test, coping with uncertainties
that appear during the test and, finally, using the test results to calculate the desired SEE rate
for avionics. Many of these issues will be discussed in Clauses 6 and 7.
6 Availability of existing SEE data for avionics applications
6.1 Variability of SEE data
Because of the diverse ways that SEE testing is carried out, and the multitude of venues for
how and where such data is published, the availability of SEE data for avionics applications is
not a simple matter.
6.2 Types of existing SEE data that may be used
6.2.1 General
SEE data can be derived from a number of different kinds of tests, and all of the differences
between these tests need to be understood in order to make comparisons meaningful.
Although there are many different types of single event effects, for the purposes of this
document, the focus is on three of them: single event upset (SEU), single event functional
interrupt (SEFI) and single event latchup (SEL). SEU pertains to the energy deposited by an
energetic particle leading to a single bit being flipped in its logic state. The main types of
electronic components that are susceptible to SEU are random access memories (RAMs, both
SRAMs and DRAMs), field programmable gate arrays (FPGAs, especially those using SRAM-
based configuration) and microprocessors (the cache memory and register portions). A SEFI
refers to a bit flip in a complex electronic component that results in the electronic component
itself or the board on which it is operating not functioning properly. A typical example is an
SEU in a control register, which can affect the electronic component itself, but can also be
propagated to another electronic component on the board, leading to board malfunction. SEL
refers to the energy deposited in a CMOS device that leads to the turning on of a parasitic p-
n-p-n structure, which usually results in a high current in the device and a non-functioning

– 12 – IEC 62396-2:2017 © IEC 2017
state. High energy neutrons in the atmosphere can induce all of these effects: SEU, SEFI and
SEL. Where electronic components are operated at high voltage stress (200 V and above)
they can be subject to single event burn-out, SEB, or single event gate rupture, SEGR; these
effects are covered in detail in IEC 62396-4.
One of the important simplifying assumptions to be used in this document is that, for single
event effects, including SEU, SEFI and SEL, the response from high energy protons, i.e.,
those with E > 100 MeV, is the same as that from high energy neutrons of the same energy.
The SEE response is generally measured in terms of a cross-section (cm ), which is the
number of errors of a given type divided by the fluence of particles to which the electronic
component was exposed. Therefore, for the SEU, SEFI and SEL, cross-sections determined
by measurements made with high energy protons can be used as the cross-sections for high
energy atmospheric neutrons so long as the proton beam test uses the same energy range.
This is far more than an assumption, since it has been demonstrated by direct measurement
in many different electronic components, see [5, 6, 7, 8, 9] and IEC 62396-1. In these
references, SEU was measured in the same electronic components using monoenergetic
proton beams and using the neutron beam from the ICE facility at WNR, Los Alamos National
Laboratory. The energy spectrum of the neutrons in the ICE facility is almost identical to the
spectrum of neutrons in the atmosphere. An estimate of the SEE rate at aircraft altitudes in an
electronic component can be obtained by the simplified formula:
2.
SEE rate per electronic component = 6 000 [neutron/cm h]
× avionics SEE cross-section [cm /electronic component] (1)
Here, the integral neutron flux in the atmosphere, E >10 MeV, is taken to be
2.
6 000 neutron/cm h, the approximate flux at 40 000 ft (12,2 km) and 45° latitude as in
IEC 62396-1; this approximation is suitable for electronic components with feature size above
150 nm. This shows the importance of the SEE cross-section. As indicated above, the
avionics SEE cross-section is taken to be the SEE cross-section obtained from SEE tests with
a spallation neutron source such as the WNR, and also with a proton or neutron beam at
energies > 100 MeV. The simplified approach of Formula (1) is used in IEC 62396-1 and is the
nominal flux under the above conditions. For electronic components with feature size below
2.
150 nm the relevant neutron flux will be higher than 6 000 neutron/cm h because the
threshold energy will be lower than 10 MeV, therefore the threshold energy (and flux) used for
estimation should be clearly shown and validation demonstrated (see IEC 62396-1). The
failure rate is the integral over all energies of the neutron flux multiplied by the SEE cross-
section: ∫Φ(E)σ(E)dE. Here the integral is replaced by an average flux multiplied by an
average SEE cross-section with assumed limits of integration.
A more elaborate approach for calculating the SEE rate is to utilize a number of
measurements of the SEE cross-section as a function of neutron or proton energy, and
integrate the curve of the SEE cross-section over energy with the differential neutron flux. The
details for this approach are given in the standard JESD89A [10], although the neutron flux
given in this standard is at ground level and would have to be multiplied by approximately a
factor of 300 to make it relevant to avionics applications (see 6.2.3).
Thus the data that is most valuable for estimating the SEE rate in avionics is from SEE
cross-section measurements made with: a) a spallation neutron source such as the WNR, b) a
monoenergetic proton beam and c) a quasi-monoenergetic neutron (QMN) beam. Other SEE
data that is also valuable are SEU cross-sections made with a monoenergetic 14 MeV neutron
beam. Based on comparisons of SEU cross-section measurements with a 14 MeV neutron
beam and the WNR, the WNR SEU cross-section is approximately a factor of 1,5 to 2 higher
than the 14 MeV SEU cross-section for relatively recent electronic components [7], (feature
size < 0,5 µm), and a factor of 4 times higher for older electronic components [8]. For some of
the very latest electronic components, the factor is close to 1. In general, there are a number
of spallation neutron facilities around the world for neutron soft error rate testing; the
accuracy of these is considered in references [11, 12]. Calculation of soft error rate depends
largely on the combination of the electronic component and the facility to be used. There does
need to be some kind of practical threshold energy to determine the neutron flux, but the

threshold cannot be a fixed value and generally decreases as the scaling of the device
proceeds. The value of “10MeV” threshold has been used for electronic components with
geometry above 100 nm, however the threshold energy used for neutron flux determination
should be clearly shown and should be validated with reference to the electronic component
technology.
6.2.2 Sources of data, proprietary versus published data
As indicated above, SEE cross-section measurements that are relevant to avionics SEE rates
are being made by a variety of different groups. These include:
a) space organizations that use only monoenergetic proton beams for their SEE testing as in
space where there are few neutrons but many protons;
b) electronic component vendors who use neutron sources to measure the upset rate at
ground level (which they refer to as the soft error rate (SER), rather than the SEU rate,
although the terms have the same meaning);
c) avionics vendors who use neutron sources to measure the upset rate at aircraft levels.
Generally, SEE data taken and reported by government agencies contains most if not all of
the relevant information, including identifying the specific electronic components tested and
providing the measured SEU cross-sections in unambiguous units. This applies to most of the
proton data taken and reported by NASA in the open literature by the NASA centres at GSFC
and JPL. GSFC and JPL invariably publish almost all of the proton SEE data that they take.
However, even though they disseminate essentially all of the results from the proton SEE
testing that they carry out, this is data that is usually reported in the open literature in an
inclusive compilation that contains results from SEE testing with both heavy ions and protons,
thus the proton SEE data has to be carefully sought out. Examples of NASA-GSFC
compilations of SEE testing containing proton SEE test results are given in [13, 14, 15, 16],
and examples of JPL reports of SEE testing containing proton SEE test results are given in
[17, 18, 19]. Other governmental agencies do not necessarily publish the results from all of
the proton SEE tests that they perform.
Data from the other sources, primarily private companies, is not nearly as accessible.
Electronic component vendors perform a large number of tests. Such testing is performed in
accordance with industry standard JESD89 [10] and its addendum JESD89-3 [105], or to
IEC 60749-38 and IEC 60749-44. Much of this data remains proprietary and is not published
openly. Where such data is available it is important to note that it is specific to the
manufacturer, design geometry, and full part number. Unfortunately, when SEE data from
electronic component vendors is published, the results are often disguised, so that the identity
of the electronic components tested is hidden by using an arbitrary designation and the
results are expressed in units that are of little use quantitatively.
Where the data is expressed in FIT units, which means errors per 10 electronic component
hours, this can be converted into a SEE cross-section by using the FIT definition and dividing
by 13 (13 neutron/cm ∙h is the flux of high energy neutrons (E > 10 MeV) at ground level in
New York City, which is the value recommended by the JESD89A standard [10] and so most
–9 2
often used.) Thus, FIT × 10 /13 gives the SEE cross-section in cm /electronic component.
Some reports give the SER rate in units of FIT/Mbit, which allows the SEE cross-section per
–15
bit to be calculated by multiplying as follows: (FIT/Mbit) × 10 /13 to obtain the SEE
cross-section in cm /bit. Other papers report the FIT value in arbitrary units which allows the
authors to show how the FIT rate varies with a particular parameter (for example, applied
voltage), but it allows no quantitative assessment to be made of the SEE cross-section.
Examples of such reports using FIT rates are given in [6], [20, 21, 22, 23].
Most of the SEE data that has been discussed comes from the SEE testing of individual
electronic components, placing those electronic components in a beam of neutrons or protons
and monitoring changes in the status of the electronic component for errors. A typical
procedure is to fill a portion of memory in a RAM with a specified bit pattern and monitor that

– 14 – IEC 62396-2:2017 © IEC 2017
memory for bit flips in one or more addresses. However, some tests are done using an entire
board to monitor when an error has occurred. In this case, the malfunction of the board is an
indication that an error has occurred, and such an error is referred to as a SEFI, but the
functional interruption is in the board rather than the actual electronic component being
irradiated. If the beam is collimated such that only one or two electronic components are
exposed to the particles in the beam during each test, the likely source of error is a SEE in
those electronic components. However, this is a dynamic type of test and it can be that the
electronic component in the beam experienced the initial error which was propagated to
another electronic component on the board, and faulty performance of the latter electronic
component is what led to the board malfunctioning.
There are some reports of such board level tests in the open literature, but they are less
common. NASA-JSC has a requirement to perform such testing on all electronic boards that
will be used on manned space missions. This testing is carried out with a beam of protons
representative of space environment, and while it is recorded in NASA-JSC reports, these
reports are not widely available; examples are given in [24, 25, 26]. The main purpose of the
test is to screen all of the electronic components for the potential of a hard error induced by
the protons, such as a single event latchup, so recoverable errors are not analysed in great
detail in these reports. Other government agency groups also perform such board level SEE
testing, and the results of these tests are often reported in the literature, but are not included
in any organized database. In addition, private companies carry out such board level testing,
often for the benefit of specific programs for avionics applications (neutron tests for avionics
vendors) or space applications (proton tests for low earth orbit spacecraft contractors), and
this data is rarely reported in the open literature. By 2005 the number of user groups had
grown to more than 25, but the ratio of test groups that published their results had not
changed much.
6.2.3 Data based on the use of different sources
6.2.3.1 Obtaining SEE data using radiation sources
In general, all SEE testing is carried out using an accelerator-based source of neutrons or
protons, meaning that the electronic component or board to be tested will receive a larger
fluence of particles over a given period of time in the test environment compared to the
fluence it would receive during that same time period in the intended vehicle in the
atmosphere or space. In the past, testing was usually carried out with only one type of source,
but in recent times, some engineering groups have been exposing electronic components to
more than one type of particle environment and comparing the SEE responses. Two main
types of sources have been used for this SEE testing for avionics applications, neutrons and
protons, although there are a variety of different kinds of neutron sources that have been
used, as will be discussed in 6.2.3.2 and 6.2.3.3.
6.2.3.2 Data obtained using neutron sources
Single event effects, in particular single event upset, can be induced by neutrons in two
distinct energy ranges, at high energies (> 1 MeV) and at very low energies (thermal or
epi-thermal neutron energy, > 0,025 eV). High energy neutrons cause SEU by nuclear
reactions with device materials, causing energetic ions to be emitted. It is the energy from
these ions which causes ionization in the semiconductor lattice, leading to the upset.
Neutrons with energies above about 10 MeV are of the greatest concern. This is because
many of the interactions which lead to SEE have threshold energies in the region between
2 MeV and 10 MeV in silicon, oxygen and other typical device materials [27, 28, 29] and
because elastic interactions (which have no threshold energy) are more effective at higher
energies [30, 31, 32, 33]. Nonethe
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