IEC TR 62866:2014

IEC TR 62866 ®
Edition 1.0 2014-05
TECHNICAL
REPORT
RAPPORT
TECHNIQUE
colour
inside
Electrochemical migration in printed wiring boards
and assemblies – Mechanisms and testing

Migration électrochimique dans les cartes a circuits imprimés et assemblages –
Mécanismes et essais
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IEC TR 62866 ®
Edition 1.0 2014-05
TECHNICAL
REPORT
RAPPORT
TECHNIQUE
colour
inside
Electrochemical migration in printed wiring boards

and assemblies – Mechanisms and testing

Migration électrochimique dans les cartes a circuits imprimés et assemblages –

Mécanismes et essais
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XD
ICS 31.180 ISBN 978-2-8322-1559-3

– 2 – IEC TR 62866:2014 © IEC 2014
CONTENTS
FOREWORD . 7
INTRODUCTION . 9
1 Scope . 10
2 Electrochemical migration . 10
2.1 Operation failure of electronic and electric equipment . 10
2.2 Name change of migration causing insulation degradation and nature of the
degradation. 11
2.2.1 History of naming with migration causing insulation degradation . 11
2.2.2 Process of degradation by migration . 11
2.3 Generation patterns of migration . 11
3 Test conditions and specimens . 13
3.1 Typical test methods . 13
3.2 Specimens in migration tests . 14
3.2.1 Design of test specimens . 14
3.2.2 Specifications and selection of specimen materials . 19
3.2.3 Remarks on the preparation of specimens . 20
3.2.4 Storing of specimens . 20
3.2.5 Pretreatment of the specimen (baking and cleaning) . 20
3.2.6 Care to be taken in handling specimens . 21
3.3 Number of specimens required in a test . 21
3.3.1 Specifications given in JPCA ET 01 . 21
3.3.2 Number of specimens in a test . 22
3.3.3 Number of specimens for the different evaluation purposes of a test. 22
4 Test methods . 23
4.1 General . 23
4.2 Steady state temperature and humidity test and temperature-humidity cyclic
test . 23
4.2.1 Purpose and outline of the test . 23
4.2.2 Test profile . 24
4.2.3 Test equipment . 27
4.2.4 Remarks on testing . 28
4.3 Unsaturated pressurized vapour test or HAST (highly accelerated temperature
and humidity stress test) . 30
4.3.1 Purpose and outline of the test . 30
4.3.2 Temperature-humidity-pressure profile . 31
4.3.3 Structure of and remarks on the test equipment . 32
4.3.4 Remarks on performing HAST . 34
4.4 Saturated and pressurized vapour test . 36
4.4.1 Purpose and outline of the test . 36
4.4.2 Test profile . 36
4.4.3 Remarks on test performing . 36
4.5 Dew cyclic test . 37
4.5.1 Purpose and outline of the test . 37
4.5.2 Dew cycle test temperature-humidity profile . 37
4.5.3 Structure of the test equipment . 38
4.5.4 Remarks on the test method . 38

4.5.5 An example of migration in the solder flux from the dew cycle test . 41
4.6 Simplified ion migration tests . 43
4.6.1 General . 43
4.6.2 De-ionized water drop method . 43
4.6.3 Diluted solution method . 45
4.7 Items to be noted in migration tests . 46
5 Electrical tests . 49
5.1 Insulation resistance measurement . 49
5.1.1 Standards of insulation resistance measurement . 49
5.1.2 Measurement method of insulation resistance . 49
5.1.3 Special remarks on insulation resistance measurement . 52
5.2 Measurement of dielectric characteristics . 55
5.2.1 General . 55
5.2.2 Dielectric characteristics of board surface . 55
5.2.3 Migration and dielectric characteristics of the printed wiring board surface
5.2.4 Evaluation of migration by AC impedance measurement . 59
6 Evaluation of failures and analysis . 60
6.1 Criteria for failures . 60
6.2 Data analysis . 61
6.2.1 Analysis of experimental data . 61
6.2.2 Relationship of the parameters in the experimental data and an example
of the analysis . 63
6.2.3 Electric field strength distribution . 64
6.3 Analysis of specimen with a failure, methods of analysis and case study . 65
6.3.1 General . 65
6.3.2 Cross section.
...