SIST EN 62005-2:2002
(Main)Reliability of fibre optic interconnecting devices and passive components -- Part 2: Quantitative assessment of reliability based on accelerated ageing tests - Temperature and humidity; steady state
Reliability of fibre optic interconnecting devices and passive components -- Part 2: Quantitative assessment of reliability based on accelerated ageing tests - Temperature and humidity; steady state
Defines a basis for reliability tests for passive optical components. It provides advice on life testing procedures, the calculation of failure rates and presentation of results. A worked example illustrates the method of calculating the instantaneous failure rate for a device during its service lifetime, based on accelerated life tests.
Zuverlässigkeit von LWL-Verbindungselementen und passiven Bauelementen -- Teil 2: Quantitative Beurteilung der Zuverlässigkeit auf der Basis von beschleunigten Alterungsprüfungen - Temperatur und Feuchte; konstant
Fiabilité des dispositifs d'interconnexion et des composants passifs à fibres optiques -- Partie 2: Evaluation quantitative de la fiabilité en fonction d'essais de viellissement accélérés - Température et humidité, régimes continus
Definit la base pour des essais de fiabilité des composants optiques passifs. Il fournit des conseils sur les procédures d'essai de durée de vie, les calculs des taux de défaillance et la présentation des résultats. Un exemple partique presente la méthode de caldul des taux de défaillance instantanée pour un dispositif au cours de sa durée de vie en service en fonction d'essais de durée de vie accélérée.
Reliability of fibre optic interconnecting devices and passive components - Part 2: Quantitative assessment of reliability based on accelerated ageing tests - Temperature and humidity, steady state (IEC 62005-2:2001)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 62005-2:2002
01-september-2002
Reliability of fibre optic interconnecting devices and passive components - Part 2:
Quantitative assessment of reliability based on accelerated ageing tests -
Temperature and humidity, steady state (IEC 62005-2:2001)
Reliability of fibre optic interconnecting devices and passive components -- Part 2:
Quantitative assessment of reliability based on accelerated ageing tests - Temperature
and humidity; steady state
Zuverlässigkeit von LWL-Verbindungselementen und passiven Bauelementen -- Teil 2:
Quantitative Beurteilung der Zuverlässigkeit auf der Basis von beschleunigten
Alterungsprüfungen - Temperatur und Feuchte; konstant
Fiabilité des dispositifs d'interconnexion et des composants passifs à fibres optiques --
Partie 2: Evaluation quantitative de la fiabilité en fonction d'essais de viellissement
accélérés - Température et humidité, régimes continus
Ta slovenski standard je istoveten z: EN 62005-2:2001
ICS:
33.180.20 3RYH]RYDOQHQDSUDYH]D Fibre optic interconnecting
RSWLþQDYODNQD devices
SIST EN 62005-2:2002 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN 62005-2:2002
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SIST EN 62005-2:2002
EUROPEAN STANDARD EN 62005-2
NORME EUROPÉENNE
EUROPÄISCHE NORM June 2001
ICS 33.180.20
English version
Reliability of fibre optic interconnecting devices and passive components
Part 2: Quantitative assessment of reliability based on
accelerated ageing tests -
Temperature and humidity; steady state
(IEC 62005-2:2001)
Fiabilité des dispositifs d'interconnexion et Zuverlässigkeit von LWL-
des composants passifs à fibres optiques Verbindungselementen und passiven
Partie 2: Evaluation quantitative de la Bauelementen
fiabilité en fonction d'essais de Teil 2: Quantitative Beurteilung der
viellissement accélérés - Zuverlässigkeit auf der Basis von
Température et humidité, régimes beschleunigten Alterungsprüfungen -
continus Temperatur und Feuchte; konstant
(CEI 62005-2:2001) (IEC 62005-2:2001)
This European Standard was approved by CENELEC on 2001-05-01. CENELEC members are bound to
comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and
notified to the Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic,
Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway,
Portugal, Spain, Sweden, Switzerland and United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2001 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 62005-2:2001 E
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SIST EN 62005-2:2002
EN 62005-2:2001 - 2 -
Foreword
The text of document 86B/1438/FDIS, future edition 1 of IEC 62005-2, prepared by SC 86B, Fibre
optic interconnecting devices and passive components, of IEC TC 86, Fibre optics, was submitted to
the IEC-CENELEC parallel vote and was approved by CENELEC as EN 62005-2 on 2001-05-01.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2002-02-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2004-05-01
Annexes designated "normative" are part of the body of the standard.
In this standard, annex ZA is normative.
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 62005-2:2001 was approved by CENELEC as a European
Standard without any modification.
__________
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SIST EN 62005-2:2002
- 3 - EN 62005-2:2001
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
This European Standard incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions of any
of these publications apply to this European Standard only when incorporated in it by amendment or
revision. For undated references the latest edition of the publication referred to applies (including
amendments).
NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
Publication Year Title EN/HD Year
IEC 62005-4 1999 Reliability of fibre optic interconnecting EN 62005-4 1999
devices and passive optical components
Part 4: Product screening
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SIST EN 62005-2:2002
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SIST EN 62005-2:2002
NORME
CEI
INTERNATIONALE IEC
62005-2
INTERNATIONAL
Première édition
STANDARD
First edition
2001-03
Fiabilité des dispositifs d'interconnexion
et des composants passifs à fibres optiques –
Partie 2:
Evaluation quantitative de la fiabilité en fonction
d'essais de vieillissement accélérés –
Température et humidité; régimes continus
Reliability of fibre optic interconnecting devices
and passive components –
Part 2:
Quantitative assessment of reliability
based on accelerated ageing tests –
Temperature and humidity; steady state
© IEC 2001 Droits de reproduction réservés ⎯ Copyright - all rights reserved
Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in
utilisée sous quelque forme que ce soit et par aucun procédé, any form or by any means, electronic or mechanical,
électronique ou mécanique, y compris la photocopie et les including photocopying and microfilm, without permission in
microfilms, sans l'accord écrit de l'éditeur. writing from the publisher.
International Electrotechnical Commission 3, rue de Varembé Geneva, Switzerland
Telefax: +41 22 919 0300 e-mail: inmail@iec.ch IEC web site http://www.iec.ch
CODE PRIX
Commission Electrotechnique Internationale
S
PRICE CODE
International Electrotechnical Commission
Pour prix, voir catalogue en vigueur
For price, see current catalogue
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SIST EN 62005-2:2002
62005-2 © IEC:2001 – 3 –
CONTENTS
Page
FOREWORD . 5
INTRODUCTION .9
Clause
1 Scope . 11
2 Normative references . 11
3 Guidance on testing for wear out failures . 11
3.1 Failure distribution . 11
3.2 Median time to failure (MTF) . 13
4 Life test matrix .15
5 Worked example . 19
5.1 Test condition matrix. 19
5.2 Analysis of results . 19
5.3 Calculating median time to failure. 23
5.4 Calculation of temperature acceleration factor . 29
5.5 Calculation of humidity acceleration factor. 31
5.6 Extrapolation to service conditions . 33
5.7 Calculation of failure rate . 35
6 Random failure rate calculations. 39
7 Implications for system reliability . 41
Figure 1 – Extrapolation of results to determine time to failure . 21
Figure 2 – Log-normal plot for devices in test condition C. 27
Figure 3 – Log-normal plot for devices in test condition E. 27
Figure 4 – Exponential curve fit for MTF versus 1/T . 31
2
Figure 5 – Exponential curve fit for MTF versus H . 33
R
Figure 6 – Component reliability in service . 37
Table 1 – Relative humidity (%) at various temperature and absolute humidity conditions . 17
Table 2 – Matrix of test conditions . 19
Table 3 – Times to failure (TTF) for devices in two life test conditions . 25
Table 4 – Median times to failure for three temperatures at 85 % H . 29
R
Table 5 – Median times to failure for three humidity levels at 85 °C . 31
Table 6 – Median times to failure in different conditions based on worked example data. 35
Table 7 – Calculated failure rates at 25 °C/85 % H . 37
R
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SIST EN 62005-2:2002
62005-2 © IEC:2001 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
RELIABILITY OF FIBRE OPTIC INTERCONNECTING DEVICES
AND PASSIVE COMPONENTS –
Part 2: Quantitative assessment of reliability
based on accelerated ageing tests –
Temperature and humidity; steady state
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, the IEC publishes International Standards. Their preparation is
entrusted to technical committees; any IEC National Committee interested in the subject dealt with may
participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. The IEC collaborates closely with the International Organization
for Standardization (ISO) in accordance with conditions determined by agreement between the two
organizations.
2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, an
international consensus of opinion on the relevant subjects since each technical committee has representation
from all interested National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, technical reports or guides and they are accepted by the National
Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62005-2 has been prepared by subcommittee 86B: Fibre optic
interconnecting devices and passive components, of IEC technical committee 86: Fibre optics.
The text of this standard is based on the following documents:
FDIS Report on voting
86B/1438/FDIS 86B/1497/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 3.
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SIST EN 62005-2:2002
62005-2 © IEC:2001 – 7 –
IEC 62005 consists of the following parts, under the general title Reliability of fibre optic
interconnecting devices and passive components
– Part 1: Introductory guide and definitions
– Part 2: Quantitative assessment of reliability based on accelerated ageing tests –
Temperature and humidity; steady state
– Part 3: Relevant tests for evaluating failure modes and failure mechanisms for passive
components
– Part 4: Product screening
1)
– Part 5: Reliability accelerated tests to standardized service environments
1)
– Part 6: Use of field data to determine, specify and improve component reliability
1)
– Part 7: Life stress modelling
The committee has decided that the contents of this publication will remain unchanged until
2006. At this date, the publication will be
reconfirmed;
withdrawn;
replaced by a revised edition, or
amended.
___________
1)
Under consideration.
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SIST EN 62005-2:2002
62005-2 © IEC:2001 – 9 –
INTRODUCTION
Investigations carried out on optical passive devices such as splitters indicate that their failure
mechanisms accelerate with both temperature and humidity. In many of the proposed
applications, particularly in the telecommunications local loop, devices are located in
environments that are subject to both high temperature and potentially high humidity.
Information about the accelerating effect of both temperature and humidity is therefore
essential to ensure that the devices are fit for use.
A system designer has an overall target reliability for a system that can be divided into target
reliabilities that cover all components in the system. The location of a particular component in
a network will influence the target reliability. If a fault in a component does not cause loss of
service, for example if the service switches to a back-up, the target reliability of that
component may not be so stringent. There is however a second consideration, besides
continuity of service provision, and that is the "maintenance burden". This is a measure of the
time spent repairing a network and a service provider needs to ensure that this does not
become economically non-viable. The allocation of target reliability to particular components is
a process that requires experience of the behaviour of the components in particular
environments. Failure of passive optical components appears to be dominated by wear out
mechanisms; therefore, the failure rate is not constant with time. This means that information
is required not only to provide the median time to failure (MTF) but also for the distribution of
the failure rate with time.
A worked example which focuses on temperature and humidity is given but it should be
remembered that other factors such as vibration or the presence of organic solvents may also
reduce the time to failure. The choice of suitable life tests should be based on an
understanding of the conditions in which the devices are deployed, together with knowledge of
the potential failure mechanisms of the device. There may be some failure mechanisms that
are not readily accelerated by typical stress conditions. In establishing standards, this part of
IEC 62005 sets out the minimum requirements, while other standards to be published should
be used to establish whether additional stress testing is required.
A further complication is random failure. These are failures that cannot be attributed to a wear-
out mechanism. Random failures consequently occur at a constant rate in a population of
devices and are often referred to as steady-state failures.
It should be noted that the life test programme defined by this standard has been found to be
applicable to passive devices operating in conditions where the ambient temperature does not
vary by more than ±15 °C from the mean value. It is only applicable to devices that have been
specified according to the appropriate performance specification for the intended service
conditions.
Devices that have dematable components or components that contain parts that rely on
mechanical movement to perform correctly need additional life testing to ensure that the
mechanical operation of the components remains correct throughout the lifetime of the
component. The life test programme defined in this part of IEC 62005 still represents a
significant part of the reliability information required for these components.
Components subjected to wider ranges of temperature variation or to other additional stresses
such as vibration will also require additional life tests.
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SIST EN 62005-2:2002
62005-2 © IEC:2001 – 11 –
RELIABILITY OF FIBRE OPTIC INTERCONNECTING DEVICES
AND PASSIVE COMPONENTS –
Part 2: Quantitative assessment of reliability
based on accelerated ageing tests –
Temperature and humidity; steady state
1 Scope
This part of IEC 62005 provides a basis for defining reliability tests for passive optical
components. It provides advice on life testing procedures, the calculation of failure rates and
the presentation of results. In addition to such general guidance, a worked example illustrates
the method of calculating the instantaneous failure rate for a device during its service lifetime,
based on accelerated life tests.
2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this part of IEC 62005. For dated references, subsequent amendments
to, or revisions of, any of these publications do not apply. However, parties to agreements
based on this part of IEC 62005 are encouraged to investigate the possibility of applying the
most recent editions of the normative documents indicated below. For undated references, the
latest edition of the normative document referred to applies. Members of IEC and ISO maintain
registers of currently valid International Standards.
IEC 62005-4:1999, Reliability of fibre optic interconnecting devices and passive components –
Part 4: Product screening
3 Guidance on testing for wear out failures
3.1 Failure distribution
Experience has shown that a log-normal distribution of times to failure can often be assumed
to apply for wear-out failures of passive optical devices. That is to say that the log to the base
e of the times to failure will have a normal (Gaussian) distribution. The dispersion parameter,
σ, is the standard deviation of the logarithm to the base e of the times to failure. The log-
normal distribution is the basis of the calculations shown in this standard.
The probability distribution function for a log-normal distribution is given by equation (1).
2
⎡ ⎤
⎧ ln()t t ⎫
1 1
m
⎢ ⎥
()
f t = exp − (1)
⎨ ⎬
⎢ ⎥
2 σ
tσ 2 π ⎩ ⎭
⎣ ⎦
where
t = t is the median time to failure (MTF), taken for 50 % of samples to fail;
m 50
σ is the standard deviation of ln(t).
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SIST EN 62005-2:2002
62005-2 © IEC:2001 – 13 –
In some cases, a Weibull distribution may provide a better representation of the failure
distribution. The principles outlined in this clause are still valid, but the calculation involved in
determining wear-out failure rates will be different. Where experimental results indicate that
there is more than one significant failure mechanism, the median time to failure and dispersion
should be reported in each case.
Information shall be provided to justify extrapolation models and activation energies used in
reliability predictions. Field feedback shall be collated to support the basis for the accelerated
ageing tests. Where feedback suggests that failure rates are very different to those predicted,
failure analysis shall be carried out to allow the accelerated ageing programme to be modified
appropriately.
Throughout this standard, failure rates are expressed in FITs, where one FIT is defined as one
9
failure in 10 device-hours. This expression of failure rate is of more value in the assessment
of system reliability than the MTF figure. From a system perspective, it is the early failures that
are critical. The MTF refers to a time by which half of the components will have failed, which
on its own is of no value in calculating the reliability of a system.
3.2 Median time to failure (MTF)
Accelerated testing is required to demonstrate the long-term reliability of optical passive
devices. High temperature and humidity life testing is the most widely used method of
providing reliability data in a test of reasonable duration.
For thermal over-stress, the association between lifetime and temperature is derived from the
Arrhenius relationship:
t = R exp (–E /kT)(2)
50 0 A
where
t is the median time to failure (MTF), taken for 50 % of samples to fail;
50
R is the coefficient;
0
–5
k is Boltzmann's constant (8,6 × 10 eV/K);
T is the temperature, in kelvins (K);
E is the activation energy, expressed in electronvolts (eV).
A
There is no universally accepted relationship between lifetime and humidity. Unless there is
evidence to the contrary, the following expression may be used:
2
t = R exp [–ηH](3)
50 0 R
where
η is the humidity activation parameter;
H is the relative humidity, in per cent (%).
R
When the acceleration rates are known, the median time to failure can be calculated at any
operating temperature and humidity. The failure rate as a function of time may then be
calculated provided that the standard deviation of the log-normal distribution is known.
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SIST EN 62005-2:2002
62005-2 © IEC:2001 – 15 –
The sample size should be chosen to allow the distribution of wear out lifetimes to be
determined with sufficient accuracy. A minimum of 25 components for each life test condition
is recommended and random sampling techniques shall be used to eliminate any batch
dependency of the result.
The sample size of 25 components in each test condition is regarded as the minimum needed
to obtain meaningful results. The relationship between the confidence level and the sample
size is complex and 25 is a suggestion based on experience gained in this field for typical
devices intended for telecommunications service environments. This number would not be
adequate for extreme reliability devices intended for satellite or submarine applications where
a test sample size of 200 devices would be more appropriate. The confidence level is affected
not only by sample size but also by factors such as the duration of the test, the fit of the
extrapolation to failure and the intended service life of the devices.
It is possible that two factors that accelerate ageing, when applied together, may result in a
different lifetime to that which would be expected from calculations based on each parameter
alone. This can arise through interactions between the different degradation mechanisms. In
the example given above, it may be found that η is not constant with respect to T. In this
situation, a greater number of test conditions must be chosen in order to gain a full
understanding of the interaction.
It is important that the mechanism of failure is understood. IEC 62005-3 lists the typical modes
of failure for a range of passive optical devices and states the mechanism of failure that is
usually associated with the observed mode of failure. It also gives details of tests that may be
used to induce these types of failure. This information is of value in designing experiments that
allow investigation of failure mechanisms. When the key failure mechanisms are understood, a
more restricted range of tests may be chosen for extended life testing. In this standard, it has
been assumed that the dominant failure mechanisms have been identified and that these have
been observed to be accelerated by high temperature and high humidity.
4 Life test matrix
Table 1 shows the relationship between relative humidity and absolute humidity as a function
of temperature. The choice of test conditions will be influenced by knowledge of whether
relative or absolute humidity is the failure-accelerating factor. Test conditions shall be chosen
so that at least two conditions have humidity as a constant and at least two conditions have
temperature as a constant. This will require a minimum of three conditions.
It should be noted that table 1 is not intended to show all possible temperature and humidity
combinations that may be used for testing. Other values of temperature and humidity may be
chosen. The following equation may be used to calculate values of relative humidity at different
temperature and absolute humidity levels:
( 273 T )
+
(4)
H = H × 100 %
R A
⎛
⎞
7,5 T
⎜
⎟
+0 ,785 71
⎟
⎜
237,3 + T
⎠
⎝
217 × 10
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SIST EN 62005-2:2002
62005-2 © IEC:2001 – 17 –
where
H is the relative humidity, in per cent (%);
R
3
H is the absolute humidity, in grams per cubic metre (g/m );
A
T is the temperature, in degrees Celsius (°C).
The constants 7,5, 237,3 and 0,785 71 are derived from the "Magnus formula" giving
saturation vapour pressure over liquid water. Different constants apply over ice.
It will normally be necessary to choose more than three test conditions to obtain an accurate
basis for a lifetime acceleration model. The use of three test conditions, as highlighted in the
test matrix, is only acceptable if the acceleration of the failure rate follows the relationships to
temperature and humidity that are described in clause 5.
If the relationship does not fit this model, it is possible that failure mechanisms be introduced
which are not dominant at the normal operation conditions of the device. The only solution is to
use lower test temperatures but this inevitably means that the test duration will be much
longer. It may be necessary to avoid using a temperature that is higher than the maximum
permitted temperature for the fibre or cable. However, higher temperatures can be used,
provided that tests are carried out to determine the effect on the cable to check that this does
not influence the result.
Table 1 – Relative humidity (%) at various temperature and absolute humidity conditions
Temperature
°C
25 40 45 55 65 75 85 95
19,6 85383019 12 8 6 4
21,5 93423321 13 9 6 4
43,5 856742 271812 9
47,6 937346 302014 9
55,6 8553 35231611
60,8 9358 38251712
88,5 85 55372518
Absolute
humidity 96,8 93 60402819
3
g/m
136,6 85 57 39 27
149,4 93 62 42 30
204,8 85 58 41
224,0 93 64 45
299,0 85 60
327,0 93 65
426,4 85
466,4 93
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SIST EN 62005-2:2002
62005-2 © IEC:2001 – 19 –
5 Worked example
The values derived in this worked example are for illustration only. Experience has shown for
example, that wide variation between the activation energies of different failure mechanisms is
common. Values of between 0,4 eV and 1,2 eV have been seen for passive device failure
mechanisms and values outside this range are possible.
This worked example demonstrates how a matrix of tests can be used to determine the
acceleration factors resulting from temperature and relative humidity. Using these factors, the
example shows how failure rate, as a function of time, can be calculated at any defined service
condition. Throughout this worked example, it is assumed that there is just one wear-out failure
mechanism and that it can be modelled with a log-normal failure probability distribution.
5.1 Test condition matrix
The matrix of steady-state tests shown in table 2 serves as an example. The first three tests
investigate the effect of relative humidity at constant temperature while the last three
investigate the effect of temperature at constant relative humidity.
Table 2 – Matrix of test conditions
Temperature Relative humidity Samples Condition
°C % identification
85 45 25 A
85 65 25 B
85 85 25 C
75 85 25 D
65 85 25 E
5.2 Analysis of results
It is necessary to select appropriate failure criteria, based on system requirements. In the
following example, a single failure
...
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