Reliability stress screening - Part 2: Components

IEC 61163-2:2020 provides guidance on RSS techniques and procedures for electrical, electronic, and mechanical components. This document is procedural in nature and is not, and cannot be, exhaustive with respect to component technologies due to the rapid rate of developments in the component industry. This document is:
a) intended for component manufacturers as a guideline;
b) intended for component users as a guideline to negotiate with component manufacturers on RSS requirements;
c) intended to allow the planning of an RSS process in house to meet reliability requirements or to allow the re-qualification of components for specific, upgraded, environments;
d) intended as a guideline to sub-contractors who provide RSS as a service.
This document is not intended to provide test plans for specific components or for delivery of certificates of conformance for batches of components. The use of bi-modal Weibull analysis to select and optimize an RSS process without having to estimate the reliability and life time of all items is described. This second edition cancels and replaces the first edition published in 1998. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
a) this version of the document is a complete rewrite and restructure from the previous version.

Déverminage sous contraintes - Partie 2: Composants

IEC 61163-2:2020 fournit des recommandations relatives aux techniques et procédures de RSS pour composants électriques, électroniques et mécaniques. Le présent document est de nature procédurale. En raison de l'évolution rapide de l'industrie des composants, elle n'est pas, ni ne peut être, exhaustive au regard de la technologie des composants. Le présent document est prévu pour:
a) les fabricants de composants, en tant que ligne directrice;
b) les utilisateurs de composants, en tant que ligne directrice pour la négociation relative aux exigences de RSS avec les fabricants de composants;
c) permettre la planification d'un processus de RSS interne, destiné à satisfaire aux exigences de fiabilité, ou pour admettre la requalification des composants pour des environnements spécifiques mis à niveau;
d) les sous-traitants qui proposent le RSS comme un service, en tant que ligne directrice.
Le présent document n'a pas pour but de fournir des plans d'essai pour soumettre des composants spécifiques à l'essai ni de délivrer des certificats de conformité pour des lots de composants. L'usage d'une analyse bimodale de Weibull visant à choisir et optimiser un processus de RSS, sans avoir à évaluer la fiabilité ni la durée de vie de toutes les entités, fait l'objet d'une description. Cette deuxième édition annule et remplace la première édition parue en 1998. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) cette version du document a fait l'objet d'une refonte intégrale et a été réorganisée par rapport à la version précédente.

General Information

Status
Published
Publication Date
10-Mar-2020
Technical Committee
Current Stage
PPUB - Publication issued
Completion Date
11-Mar-2020
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IEC 61163-2
Edition 2.0 2020-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Reliability stress screening –
Part 2: Components
Déverminage sous contraintes –
Partie 2: Composants
IEC 61163-2:2020-03(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 61163-2
Edition 2.0 2020-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Reliability stress screening –
Part 2: Components
Déverminage sous contraintes –
Partie 2: Composants
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 03.120.01; 31.020 ISBN 978-2-8322-7910-6

Warning! Make sure that you obtained this publication from an authorized distributor.

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® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – IEC 61163-2:2020 © IEC 2020
CONTENTS

FOREWORD ........................................................................................................................... 4

INTRODUCTION ..................................................................................................................... 6

1 Scope .............................................................................................................................. 7

2 Normative references ...................................................................................................... 7

3 Terms and definitions ...................................................................................................... 7

4 Description of reliability stress screening (RSS) .............................................................. 8

5 Types of RSS ................................................................................................................ 10

5.1 General ................................................................................................................. 10

5.2 Constant stress screening ..................................................................................... 10

5.3 Step stress screening ........................................................................................... 10

5.4 Highly accelerated stress screening (HASS) ......................................................... 10

6 Managing RSS .............................................................................................................. 11

6.1 Planning ............................................................................................................... 11

6.2 Termination of RSS ............................................................................................... 12

7 Design of RSS ............................................................................................................... 12

7.1 General ................................................................................................................. 12

7.2 Physics of failure .................................................................................................. 12

7.3 Common screening procedures ............................................................................. 13

7.4 Characteristics of a well-designed screening procedure ........................................ 14

7.5 Screening evaluation ............................................................................................ 14

7.6 Selection of samples ............................................................................................. 14

7.7 Setting the duration of RSS ................................................................................... 15

8 Managing an RSS programme ....................................................................................... 15

8.1 Resources ............................................................................................................ 15

8.2 Monitoring during RSS .......................................................................................... 16

9 Analysis for RSS ........................................................................................................... 16

9.1 General ................................................................................................................. 16

9.2 Cost benefit analysis ............................................................................................. 16

9.3 Identifying early failures ........................................................................................ 16

9.4 Analysis of the outputs of RSS .............................................................................. 17

Annex A (informative) Data analysis .................................................................................... 18

A.1 Symbols ................................................................................................................ 18

A.2 Weibull analysis .................................................................................................... 18

A.3 Design of a reliability stress screening .................................................................. 19

Annex B (informative) Examples of applications of reliability stress screening

processes ............................................................................................................................. 23

B.1 General ................................................................................................................. 23

B.2 Transformers ........................................................................................................ 23

B.3 Connectors ........................................................................................................... 25

Bibliography .......................................................................................................................... 28

Figure A.1 – Estimation of η and β ........................................................................................ 18

Figure A.2 – Nomograph of the cumulative binomial distribution (Larson) ............................. 20

Figure A.3 – Example of a Weibull plot ................................................................................. 21

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IEC 61163-2:2020 © IEC 2020 – 3 –

Figure B.1 – Weibull plot of the bump screening ................................................................... 25

Figure B.2 – Weibull plot of the pull test ................................................................................ 27

Table 1 – Common screening types and typical defect types precipitated by RSS ................. 13

Table A.1 – RSS test results ................................................................................................. 21

Table A.2 – Screening results for weak populations .............................................................. 22

---------------------- Page: 5 ----------------------
– 4 – IEC 61163-2:2020 © IEC 2020
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
RELIABILITY STRESS SCREENING –
Part 2: Components
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,

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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 61163-2 has been prepared by IEC technical committee 56:

Dependability.

This second edition cancels and replaces the first edition published in 1998. This edition

constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:

a) this version of the document is a complete rewrite and restructure from the previous version.

The text of this International Standard is based on the following documents:
FDIS Report on voting
56/1875/FDIS 56/1887/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.
---------------------- Page: 6 ----------------------
IEC 61163-2:2020 © IEC 2020 – 5 –

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

A list of all parts in the IEC 61163 series, published under the general title Reliability stress

screening, 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.
---------------------- Page: 7 ----------------------
– 6 – IEC 61163-2:2020 © IEC 2020
INTRODUCTION

Although first developed to stabilize the parameters of manufactured components (burn-in),

reliability stress screening (RSS) can be used to remove from a component population the

weaker components. This can be done at times where the manufacturing processes for

components are difficult to control or for other reasons such as where the components need to

be selected (re-qualified) to operate in harsher than usual operating conditions. This is also

done where more narrow specifications are required for the application and no alternative

courses of action are available.

The use of RSS is normally only a temporary measure when early failures need to be avoided

under a specific set of conditions as outlined above.

RSS is an effective tool in identifying and removing flaws due to poor component design and

manufacturing deficiencies.
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IEC 61163-2:2020 © IEC 2020 – 7 –
RELIABILITY STRESS SCREENING –
Part 2: Components
1 Scope

This part of IEC 61163 provides guidance on RSS techniques and procedures for electrical,

electronic, and mechanical components. This document is procedural in nature and is not, and

cannot be, exhaustive with respect to component technologies due to the rapid rate of

developments in the component industry.
This document is:
a) intended for component manufacturers as a guideline;

b) intended for component users as a guideline to negotiate with component manufacturers on

RSS requirements;

c) intended to allow the planning of an RSS process in house to meet reliability requirements

or to allow the re-qualification of components for specific, upgraded, environments;

d) intended as a guideline to sub-contractors who provide RSS as a service.

This document is not intended to provide test plans for specific components or for delivery of

certificates of conformance for batches of components.

The use of bi-modal Weibull analysis to select and optimize an RSS process without having to

estimate the reliability and life time of all items is described.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
3.1
screen

conditions, for example stress level and duration, used for the removal of non-conforming items

from a population
3.2
screening

process carried out to detect and remove non-conforming items, or those susceptible to early

life failure
Note 1 to entry: Screening may employ representative or elevated stresses.
---------------------- Page: 9 ----------------------
– 8 – IEC 61163-2:2020 © IEC 2020

[SOURCE: IEC 60050-192:2015, 192-09-11, modified – Deletion of “test” in the term,

replacement of “test” with "process" in the definition and replacement of “The test” with

"Screening" in the Note 1 to entry.]
3.3
RSS
reliability stress screening

process for detecting flaws by applying environmental and/or operational stresses to precipitate

them as detectable failures

Note 1 to entry: RSS is designed with the intention of precipitating flaws into detectable failures. An ageing process

designed specifically with the intention of stabilizing parameters is not an RSS process and is therefore outside the

scope of this document.
Note 2 to entry: This note applies to the French language only.
[SOURCE: IEC 60050-192:2015, 192-09-19, modified – Addition of Note 1 to entry.]
3.4
flaw
imperfection that could result in failure

Note 1 to entry: An imperfection in this case is a physical characteristic of the component that leads to a failure to

perform in a required way.
[SOURCE: IEC 60050-192:2015, 192-04-03, modified – Addition of Note 1 to entry.]
3.5
early life failure period
infant mortality period

time interval of early life during which the instantaneous failure intensity of a repairable item,

or the instantaneous failure rate of a non-repairable item, decreases significantly with time

Note 1 to entry: What is considered “significant” will depend upon the application.

[SOURCE: IEC 60050-192:2015, 192-02-28]
3.6
weak item

item which has a high probability of failure in the early life period due to a flaw

3.7
weak population
subset of the total population of items made up of only weak items
3.8
strong population
subset of the total population of items made up of non-weak items
4 Description of reliability stress screening (RSS)

The process of RSS is used to detect flaws in a population of items, usually components,

leading to the subsequent removal of these flawed items from the population. The removal of

such components facilitates rapid achievement of the reliability level expected for the population

over the useful life.

This can often happen when problems with items are identified and it takes time to fix the design

or the production process for the item but the existing items need to be used immediately. This

is typically a sorting exercise where the RSS is used to fail the items with problems so they can

be identified in the population or batches.
---------------------- Page: 10 ----------------------
IEC 61163-2:2020 © IEC 2020 – 9 –

RSS can also be used to sort items to meet specific operating conditions or functional

parameters where it is used to select items that meet a requirement higher than what was

originally specified from a batch that was lower than what was originally specified, for example

screening components for temperature stability or other factors that affect reliability.

Typically RSS is initiated in response to one or more of the following situations:

– customer requirements specify the use of screening;
– field performance identifies an issue with early product failures;
– the production process generates a concern for latent defects;
– to reduce the uncertainty with the introduction of a new product or process;

– to select, from a selection of different components performing the same function but with

different technologies/techniques;
– some items need to be screened to meet a tighter or increased specification.

The RSS method is achieved by applying specific environmental or operating conditions to

stress the population of items. This applied stress, or combination of stresses, will often have

environmental and operating conditions in excess of the stress at normal operating conditions.

The stresses usually used are temperature, humidity, vibration, acceleration, electrical stress

and similar conditions. A screening may have one or more conditions set at higher than normal

levels.

The screening takes places at the item level, which is usually at component level but may

include some large packages containing multiple components. RSS of products is covered by

[1] .

The screening will cause flawed components to fail quickly and so be identified in the

population. These components are then removed from the population. The remaining

components are then referred to as having been screened and the process is similar to sorting,

where the RSS is used to split the population into two distinct sets, one that has been failed by

the screening and one that has not. In some cases, a sample from a batch is screened to

determine whether a lot contains weak components.

NOTE 1 If a screening strength is too high then non-flawed components can also fail and in fact an extremely strong

screening could fail the entire population. It can also degrade them without failure but reduce their useful life. For

this reason, it is important that a screening procedure is carefully designed according to the physics and materials

of the components undergoing the screening and the reasons for the screening.

RSS should not be used as a normal procedure to assure the reliability of individual

components. The RSS method can, however, improve the actual reliability of a population or

system by removing flawed components that are more likely to cause failure.

The cost of performing RSS should be carefully evaluated and the screening only undertaken

if the potential benefits outweigh the cost.

If early failures are caused by the assembly processes for the finished item including the

component, and its handling (ESD damage, contamination, etc.) RSS will not be effective and

so should not be done. However, it may be possible to perform RSS of the finished item [1].

NOTE 2 The use of RSS is inappropriate if there are no early failures. The failures can be reduced if needed using

other methods like design changes [5]. Early failures can be identified using the techniques in [6].

NOTE 3 The use of RSS is inappropriate if the relevant failures can be detected without operating the item over

time. Failure detection at zero operating time is carried out by parametric measurement or the use of non-invasive

techniques like X-ray, scanning acoustic microscope (SAM) and similar methods.
_____________
Numbers in square brackets refer to the Bibliography.
---------------------- Page: 11 ----------------------
– 10 – IEC 61163-2:2020 © IEC 2020

NOTE 4 Using RSS to upgrade component population specifications can lead to problems, for example a logistical

problem can occur when similarly screened components are not available at a later date. This can be mitigated by

performing RSS on enough components for the repair of the system over its entire service life or by ensuring that

the system documentation is sufficient to control component procurement so that all replacement components be

similarly screened (see [7]).

Sometimes it is necessary to carry out other actions beyond RSS in order to meet the

requirements and many of the principles of reliability growth described in [5] apply. Typically,

changes in the design, the manufacturing processes or in the components' use may have to be

made. It also may be necessary to adopt a failure mode avoidance strategy that can remove

the causes of the failures or at least deal with them when they occur, for example via

redundancy.

In some cases, the stress screening will not give the results that are expected and in those

cases, further investigation is required to understand what has happened. This can happen

when a stress applied has effects that were not predicted in the initial physics of failure analysis

(see 7.2). In these cases, a redesign of the stresses applied to be more specific will be

necessary.
Some examples of the application of RSS are given in Annex B.
5 Types of RSS
5.1 General

There are a number of types of RSS: constant stress screening, step stress screening, and

highly accelerated stress screening (HASS).

The purpose of all of these screening types is to cause relevant failures to occur in the item.

Such relevant failures are those that would have prevented the item from achieving its reliability

requirements in service.
5.2 Constant stress screening

A constant stress screening is a screening procedure where a constant environmental and/or

operational stress is used for the duration of the process.
5.3 Step stress screening

Step stress screening is a screening procedure where environmental and/or operational

stresses are changed at planned intervals, usually increasing in strength for the duration of the

process.

Step stress screening is often used to shorten process times, and to give some idea of likely

failures rates at different stress levels. For this reason it is sometimes used in the RSS planning

phase to select those levels.
5.4 Highly accelerated stress screening (HASS)

Highly accelerated stress screening (HASS) is a screening procedure used in conjunction with

a highly accelerated limit test (HALT, see IEC 62506 [2], [3]). A HALT is needed before a HASS

screening procedure can be started.

NOTE HALT uses very high stress levels, typically high and low temperature, rapid temperature change and

mechanical vibration or mechanical shock. HALT is performed on a small sample of items. The output of the HALT

is typically the high and low operational limits for example the temperatures when the item stops functioning, but

recovers function once the item is brought back to normal operating temperature. Further, the HALT identifies the

destruction limits, the temperatures where the item fails permanently i.e. it does not recover as the temperature is

brought back to normal. In some cases, the limits cannot be found within the temperature range relevant for the

technology of the item. This limit information is used as the basis for setting up a HASS procedure.

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IEC 61163-2:2020 © IEC 2020 – 11 –
HASS, unlike HALT, is intended to be an on-going process ei
...

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