Reliability stress screening - Part 1: Repairable assemblies manufactured in lots

This part of IEC 61163 describes particular methods to apply and optimize reliability stress screening processes for lots of repairable hardware assemblies, in cases where the assemblies have an unacceptably low reliability in the early failure period, and when other methods, such as reliability growth programmes and quality control techniques, are not applicable.

Zuverlässigkeitsvorbehandlung durch Beanspruchung - Teil 1: Instandsetzbare Baugruppen, losweise gefertigt

Déverminage sous contraintes - Partie 1: Assemblages réparables fabriqués en lots

La présente partie de la CEI 61163 décrit les méthodes à suivre pour appliquer et optimiser des processus de déverminage sous contraintes de lots d'assemblages réparables, lorsque le niveau de fiabilité de ces assemblages est trop faible et inacceptable pendant la période de défaillances précoces et que d'autres méthodes telles que les programmes de croissance de fiabilité et techniques de maîtrise de la qualité ne sont pas applicables

Presejalno preskušanje glede zanesljivosti - 1. del: Popravljivi sestavi, izdelani v lotih (IEC 61163-1:2006)

General Information

Status
Published
Publication Date
30-Nov-2006
Technical Committee
Drafting Committee
Parallel Committee
Current Stage
6060 - Document made available
Due Date
01-Dec-2006
Completion Date
01-Dec-2006

Buy Standard

Standard
EN 61163-1:2008 - natisnjeno za čitalnico
English language
84 pages
sale 10% off
Preview
sale 10% off
Preview

e-Library read for
1 day

Standards Content (sample)

SLOVENSKI STANDARD
SIST EN 61163-1:2008
01-februar-2008

Presejalno preskušanje glede zanesljivosti - 1. del: Popravljivi sestavi, izdelani v

lotih (IEC 61163-1:2006)

Reliability stress screening - Part 1: Repairable assemblies manufactured in lots (IEC

61163-1:2006)
Zuverlässigkeitsvorbehandlung durch Beanspruchung - Teil 1: Instandsetzbare
Baugruppen, losweise gefertigt (IEC 61163-1:2006)

Déverminage sous contraintes - Partie 1: Assemblages réparables fabriqués en lots (IEC

61163-1:2006)
Ta slovenski standard je istoveten z: EN 61163-1:2006
ICS:
03.120.01
21.020
SIST EN 61163-1:2008 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
EUROPEAN STANDARD
EN 61163-1
NORME EUROPÉENNE
December 2006
EUROPÄISCHE NORM
ICS 03.120.01; 03.120.30; 21.020
English version
Reliability stress screening
Part 1: Repairable assemblies manufactured in lots
(IEC 61163-1:2006)
Déverminage sous contraintes Zuverlässigkeitsvorbehandlung
Partie 1: Assemblages réparables durch Beanspruchung
fabriqués en lots Teil 1: Instandsetzbare Baugruppen,
(CEI 61163-1:2006) losweise gefertigt
(IEC 61163-1:2006)

This European Standard was approved by CENELEC on 2006-11-01. 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, Cyprus, the Czech

Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,

Sweden, Switzerland and the 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

© 2006 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 61163-1:2006 E
---------------------- Page: 2 ----------------------
EN 61163-1:2006 - 2 -
Foreword

The text of document 56/1102/FDIS, future edition 2 of IEC 61163-1, prepared by IEC TC 56,

Dependability, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as

EN 61163-1 on 2006-11-01.
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) 2007-08-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2009-11-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice

The text of the International Standard IEC 61163-1:2006 was approved by CENELEC as a European

Standard without any modification.

In the official version, for Bibliography, the following notes have to be added for the standards indicated:

IEC 60068 NOTE Harmonized as EN 60068 (series) (not modified).
IEC 61014 NOTE Harmonized as EN 61014:2003 (not modified).
__________
---------------------- Page: 3 ----------------------
- 3 - EN 61163-1:2006
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following referenced documents are indispensable for the application 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.

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 60050-191 - International Electrotechnical Vocabulary - -
(IEV)
Chapter 191: Dependability and quality of
service
1) 2)
IEC 60068-2-2 - Environmental testing EN 60068-2-2 1993
Part 2: Tests - Tests B: Dry heat
1) 2)
IEC 60068-2-6 - Environmental testing EN 60068-2-6 1995
Part 2: Tests - Test Fc: Vibration (sinusoidal)
1) 2)
IEC 60068-2-14 - Environmental testing EN 60068-2-14 1999
Part 2: Tests - Test N: Change of temperature
1) 2)
IEC 60068-2-29 - Environmental testing EN 60068-2-29 1993
Part 2: Tests - Test Eb and guidance: Bump
1) 2)
IEC 60068-2-30 - Environmental testing EN 60068-2-30 2005
Part 2-30: Tests - Test Db: Damp heat, cyclic
(12 h + 12 h cycle)
1) 2)
IEC 60068-2-64 - Environmental testing EN 60068-2-64 1994
Part 2: Test methods - Test Fh: Vibration,
broad-band random (digital control) and
guidance
1) 2)
IEC 60068-2-78 - Environmental testing EN 60068-2-78 2001
Part 2-78: Tests - Test Cab: Damp heat,
steady state
1) 2)
IEC 60300-2 - Dependability management EN 60300-2 2004
Part 2: Guidelines for dependability
management
1) 2)
IEC 61165 - Application of Markov techniques EN 61165 2006
IEC 61649 - Goodness-of-fit tests, confidence intervals - -
and lower confidence limits for Weibull
distributed data
ISO 2041 - Vibration and shock - Vocabulary - -
Undated reference.
Valid edition at date of issue.
---------------------- Page: 4 ----------------------
NORME CEI
INTERNATIONALE
IEC
61163-1
INTERNATIONAL
Deuxième édition
STANDARD
Second edition
2006-06
Déverminage sous contraintes –
Partie 1:
Assemblages réparables fabriqués en lots
Reliability stress screening –
Part 1:
Repairable assemblies manufactured in lots
 IEC 2006 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 any

utilisée sous quelque forme que ce soit et par aucun procédé, form or by any means, electronic or mechanical, including

électronique ou mécanique, y compris la photocopie et les photocopying and microfilm, without permission in writing from

microfilms, sans l'accord écrit de l'éditeur. the publisher.

International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland

Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch Web: www.iec.ch

CODE PRIX
PRICE CODE
Commission Electrotechnique Internationale
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
Pour prix, voir catalogue en vigueur
For price, see current catalogue
---------------------- Page: 5 ----------------------
61163-1  IEC:2006 – 3 –
CONTENTS

FOREWORD...........................................................................................................................9

INTRODUCTION...................................................................................................................13

1 Scope.............................................................................................................................19

2 Normative references .....................................................................................................19

3 Terms and definitions .....................................................................................................23

4 Symbols .........................................................................................................................27

5 General description ........................................................................................................27

5.1 The reliability stress screening principle ................................................................27

5.2 Failure categories..................................................................................................31

5.3 Time of occurrence of failures ...............................................................................33

6 Planning .........................................................................................................................33

6.1 Stress conditioning................................................................................................33

6.2 Evaluation of the failure-free period T .................................................................37

6.3 Time graphs for determination of the failure-free period ........................................41

7 Pilot-production screening ..............................................................................................51

7.1 General .................................................................................................................51

7.2 Collection of information........................................................................................51

7.3 Evaluation of information.......................................................................................51

7.4 Re-evaluating the failure-free period T ................................................................53

8 Mature production screening ..........................................................................................55

8.1 General .................................................................................................................55

8.2 Collection of information........................................................................................55

8.3 Evaluation of information.......................................................................................55

8.4 Dealing with discrepancies ....................................................................................55

8.5 Eliminating reliability stress screening ...................................................................59

Annex A (informative) Stress conditions – General information ............................................61

Annex B (informative) Stress conditions – Temperature .......................................................67

Annex C (informative) Stress conditions – Vibration and bump ............................................75

Annex D (informative) Stress conditions – Humidity .............................................................87

Annex E (informative) Stress conditions – Operational stress ..............................................93

Annex F (informative) Voltage stress ...................................................................................97

Annex G (informative) Highly accelerated stress screening..................................................99

Annex H (informative) Bimodal distributions – Weibull plotting and analysis.......................101

Annex I (informative) Evaluation of the failure-free period and the average screening

duration........................................................................................................................113

Annex J (informative) Worked example ..............................................................................133

Bibliography........................................................................................................................161

---------------------- Page: 6 ----------------------
61163-1  IEC:2006 – 5 –

Figure 1 – Conceptual difference between reliability screening and growth ...........................15

Figure 2 – Typical flow for the design and modifications of reliability stress screening

processes for repairable assemblies .....................................................................................17

Figure 3 – Typical flow of hardware assemblies from the component manufacturer to

the end user .........................................................................................................................21

Figure 4 – Reliability stress screening of repairable assemblies............................................29

Figure 5 – Dependency of categories of failures ...................................................................33

Figure 6 – Elements of stress conditioning............................................................................33

Figure 7 – Assembly showing screening duration..................................................................37

Figure 8 – Time graphs for the determination of the failure free period ................................43

Figure 9 – Example of an experimentally determined Weibull curve that is levelling off

at p % failures.......................................................................................................................53

1,5
 
 
 

Figure H.1 – The S-curve for a bimodal Weibull distribution mixed by F (t) = 1− e

1,5
 t 
 
 
60 000
 

and F (t) = 1− e in the proportions 15 % and 85 %, respectively ..........................103

Figure H.2 – Estimation of p, β and η for the purpose of reliability screening
1 1

optimization ........................................................................................................................105

Figure H.3 – The c.d.f. curves for bimodal exponential distribution......................................109

Figure H.4 – The hazard rate function for bimodal exponential distribution..........................111

Figure I.1 – The basic system .............................................................................................113

Figure I.2 – An assembly surviving the screening period T with n remaining

weak components ...............................................................................................................117

Figure I.3 – Possible states when a component fails during the stress screening ................117

Figure I.4 – Assembly states after failure and repair ...........................................................117

Figure I.5 – Time graph for evaluation of the failure-free screening period ..........................121

Figures I.6a and I.6b – Average screening duration versus the normalized failure-free

period – p = 0,000 5 and p = 0,001 .........................................................................125

c c

Figures I.6c and I.6d – Average screening duration versus the normalized failure-free

period – p = 0,002 and p = 0,005 ..........................................................................127

c c

Figures I.6e and I.6f – Average screening duration versus the normalized failure-free

period – p = 0,015 and p = 0,02 ...............................................................................129

c c

Figures I.6g and I.6h – Average screening duration versus the normalized failure-free

period – p = 0,03 and p = 0,04................................................................................131

c c

Figure J.1 – Derivation of the failure-free period T ...........................................................139

Figure J.2 – Derivation of the average screening duration...................................................143

Figure J.3 – Weibull plot of the observed and predicted failure pattern for the pilot

production PBAs .................................................................................................................149

---------------------- Page: 7 ----------------------
61163-1  IEC:2006 – 7 –

Figure J.4 – Weibull plot of relevant failures and predicted S-curve for the pilot

production screening ..........................................................................................................153

Figure J.5 – Time graph (corrected) for determination of the failure-free period ..................155

Figure J.6 – Time graph (corrected) for evaluation of the screening duration ......................157

Table A.1 – Stress types – Indication of cost of application...................................................63

Table J.1 – Relation between sensitivity of flaws and stresses............................................137

Table J.2 – Observed failure ranks and times to first failure for the pilot production ............145

Table J.3 – Revised rank values .........................................................................................151

---------------------- Page: 8 ----------------------
61163-1  IEC:2006 – 9 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
RELIABILITY STRESS SCREENING –
Part 1: Repairable assemblies manufactured in lots
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of 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, IEC publishes International Standards, Technical Specifications,

Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC

Publication(s)”). 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. 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 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 IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

misinterpretation by any end user.

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

transparently to the maximum extent possible in their national and regional publications. Any divergence

between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in

the latter.

5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any

equipment declared to be in conformity with an IEC Publication.

6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

members of its technical committees and IEC National Committees for any personal injury, property damage or

other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

Publications.

8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 61163-1 has been prepared by IEC technical committee 56:

Dependability.
This second edition cancels and replaces the first edition published in 1995.
The main changes with respect to the previous edition are as follows:

– alignment of terminology on Weibull distribution with the future (second) edition of

IEC 61649 (currently a Committee Draft);

– inclusion of a procedure for starting an RSS process without previous information;

– inclusion of highly accelerated stress screening; and
– inclusion of combinations of stresses.
---------------------- Page: 9 ----------------------
61163-1  IEC:2006 – 11 –
The text of this standard is based on the following documents:
FDIS Report on voting
56/1102/FDIS 56/1118/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 2.

The committee has decided that the contents of this publication will remain unchanged until

the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in

the data related to the specific publication. At this date, the publication will be

• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
---------------------- Page: 10 ----------------------
61163-1  IEC:2006 – 13 –
INTRODUCTION

Quality control and good design are prerequisites for reliability. However, in cases where an

assembly has an unacceptably low reliability in the early failure period, a reliability screening

process may be necessary.

An unacceptably low reliability level can be different from one customer to another, or can be

based on general market requirements.
Reliability stress screening (RSS) and reliability growth programmes both aim at

improvements in the reliability found by the user. However, the two methods are different in

principle:

– a reliability growth programme is a development activity, the purpose of which is to

improve the inherent reliability performance of the assemblies by effecting changes to the

design (see IEC 61014 and IEC 61164);

– the purpose of reliability stress screening is to detect and remove flaws; it is part of the

production process, and should not be relied upon to reveal inadequacies in design.

Furthermore, the two methods affect the reliability performance differently. This is illustrated

in Figure 1. In principle, a reliability screening programme "cuts away" the early failure period

(or part thereof), while a reliability growth programme reduces the overall failure rate level. A

reliability growth programme may affect the need for a reliability screening programme if the

flaws are of such a nature that they can be prevented from being present at all.

The user of this standard should be aware that reliability stress screening does not improve

the intrinsic reliability of the assemblies under consideration and, where possible, should be

made unnecessary by reliability growth programmes and/or quality control.

In this standard the term “Item” is used when it is not necessary to distinguish between

components, assemblies and system(s).

The specific purpose of carrying out a reliability screening process is to detect and remove

flaws in hardware assemblies before they reach the customer, or are assembled into higher-

level products. This means that, in principle, every hardware assembly under consideration

should be included when a reliability screening process is introduced into a production

process.

Reliability screening may cover hardware assemblies of different types and at different levels

of the manufacturing process. This standard covers composite items – assemblies which are

intended to be repaired. Once the allowable fraction of weak assemblies has been specified,

the methods in this standard lead to the most economical screening process for assemblies

that are manufactured in lots. This is because not all types of assemblies need to be

subjected to a reliability screening process. Only the types of assemblies likely to contain

flaws should be included. Furthermore, the extent (stress conditions, duration, etc.) to which

these selected assembly types will be subjected to screening needs to be minimized.

In reliability stress screening the flaws are precipitated into failures by exposure of the

assemblies to a suitable stress, for example environmental stress, operational stress, or a

combination of these. Reliability stress screening is often called environmental stress

screening (ESS).
---------------------- Page: 11 ----------------------
61163-1  IEC:2006 – 15 –
If rogue components are known about and proved to originate in the component

manufacturing process, it is much more effective to use screening e.g. burn-in of the rogue

components in question instead of the assembly. However screening a component cannot

remove flaws introduced in the assembly process (e.g. soldering, handling (ESD) etc.).

The typical steps in a reliability stress screening process are illustrated in Figure 2.

Failure rate
Equipment version A
Failure pattern before
reliability improvements
are introduced
0 Time to first failure
Reliability screening IEC 61163 series Reliability growth IEC 61014
Applicable to hardware and
software containing
Applicable to hardware
systematic weaknesses
containing flaws
Failure rate Failure rate Equipment version B
Equipment version A
Failure pattern after
Failure pattern before
reliability screening
reliability improvements
are introduced
Remaining failures are caused
Remaining failures are
by remaining flaws and
caused by residual weakness
systematic weaknesses
(including flaws)
Part "cut" away
Overall level reduced
by reliability
by reliability growth
screening
0 Time to first failure 0 Time to first failure
IEC 1026/06

NOTE This standard addresses reliability screening only. For reliability growth see IEC 61014 and IEC 61164.

Figure 1 – Conceptual difference between reliability screening and growth
---------------------- Page: 12 ----------------------
61163-1  IEC:2006 – 17 –
Start
Perform the reliability stress
Specify the maximum
screening, collect and analyse
allowable fraction of weak
the failure information
assemblies
generated 1)
J.2 step 1
6.3, 7, 8 and J.3
Evaluate the actual
fraction of weak
Design of modify (if necessary)
assemblies
the reliability stress
J.2 step 2
screening
6.2 and J.2 step 3 to step 5
Is the actual fraction
Reliability stress
of weak assemblies
screening is necessary
equal to or lower than the
J.2 step 2
specified value?
Yes
Reliability stress
srceening is not
necessary
8.5 and J.2 step 2
Stop
IEC 1027/06

The result of the analysis of the failure causes may be used in a reliability growth and quality control

programme.

Figure 2 – Typical flow for the design and modifications of reliability stress screening

processes for repairable assemblies
---------------------- Page: 13 ----------------------
61163-1  IEC:2006 – 19 –
RELIABILITY STRESS SCREENING –
Part 1: Repairable assemblies manufactured in lots
1 Scope

This part of IEC 61163 describes particular methods to apply and optimize reliability stress

screening processes for lots of repairable hardware assemblies, in cases where the

assemblies have an unacceptably low reliability in the early failure period, and when other

methods, such as reliability growth programmes and quality control techniques, are not

applicable. The reasons for using reliability stress screening may be time constraints and/or

the very nature of the deficiencies that the reliability stress screening is designed to catch.

The processes apply to any stage of a series production of repairable assemblies (see

Figure 3). The methods for setting up a process can be used during production planning,

during pilot-production, as well as during well-established running production.

A prerequisite for the application of the methods is that a certain level of flaws remaining in

the outgoing assembly can be specified.

The processes described are general processes for reliability stress screening in cases where

no specific process is described in a product standard. They are also intended for use by IEC

committees in connection with preparation of product standards. A reliability stress screening

process can form part of an overall reliability programme (see IEC 60300-2).
2 Normative references

The following referenced documents are indispensable for the application 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 60050(191): International Electrotechnical Vocabulary (IEV) – Chapter 191: Dependability

and quality of service
IEC 60068-2-2: Environmental testing – Part 2-2: Tests – Test B: Dry heat

IEC 60068-2-6: Environmental testing – Part 2-6: Tests – Test Fc: Vibration (sinusoidal)

IEC 60068-2-14: Environmental testing – Part 2-14: Tests – Test N: Change of temperature

IEC 60068-2-29: Environmental testing – Part 2-29: Tests – Test Eb and guidance: Bump

IEC 60068-2-30: Environmental testing – Part 2-30: Tests – Test Db: Damp heat, cyclic

(12 h + 12 h cycle)

IEC 60068-2-64: Environmental testing – Part 2-64: Test methods – Test Fh: Vibration, broad-

band random (digital control) and guidance

IEC 60068-2-78: Environmental testing – Part 2-78: Tests – Test Cab: Damp heat, steady

state
---------------------- Page: 14 ----------------------
61163-1  IEC:2006 – 21 –
IEC 60300-2: Dependability management – Part 2: Guidel
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.