IEC 60068-2-21
Edition 7.0 2021-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Environmental testing –
Part 2-21: Tests – Test U: Robustness of terminations and integral mounting
devices
Essais d’environnement –
Partie 2-21: Essais – Essai U: Robustesse des sorties et des dispositifs de
montage incorporés
IEC 60068-2-21:2021-07(en-fr)
®
IEC 60068-2-21
Edition 7.0 2021-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Environmental testing –
Part 2-21: Tests – Test U: Robustness of terminations and integral mounting
devices
Essais d’environnement –
Partie 2-21: Essais – Essai U: Robustesse des sorties et des dispositifs de
montage incorporés
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 19.040; 31.190
ISBN 978-2-8322-9999-9
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
®
Warning! Make sure that you obtained this publication from an authorized distributor.
Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.
– 2 – IEC 60068-2-21:2021 © IEC 2021
CONTENTS
FOREWORD ........................................................................................................................... 5
1 Scope .............................................................................................................................. 7
2 Normative references ...................................................................................................... 7
3 Terms and definitions ...................................................................................................... 8
4 Tests Ua: Robustness of terminals against axial stresses ................................................ 8
4.1 Object ..................................................................................................................... 8
4.2 Application .............................................................................................................. 8
4.3 General description ................................................................................................. 8
4.4 Preconditioning ....................................................................................................... 8
4.5 Initial measurements ............................................................................................... 8
4.6 Test procedures ...................................................................................................... 9
4.6.1 Test Ua
1
: Tensile ............................................................................................. 9
4.6.2 Test Ua
2
: Thrust ............................................................................................ 10
4.7 Final measurements .............................................................................................. 11
4.8 Information to be given in the relevant specification .............................................. 11
5 Tests Ub: Robustness of terminals against bending stresses ......................................... 11
5.1 Object ................................................................................................................... 11
5.2 Application ............................................................................................................ 12
5.2.1 General ......................................................................................................... 12
5.2.2 Pliable terminations ....................................................................................... 12
5.2.3 Rigid and all other terminations ..................................................................... 12
5.3 General description ............................................................................................... 13
5.4 Preconditioning ..................................................................................................... 14
5.5 Initial measurements ............................................................................................. 14
5.6 Test procedures .................................................................................................... 14
5.6.1 Test Ub
1
(for wire and strip terminations)....................................................... 14
5.6.2 Test Ub
2
(for tag terminations) ....................................................................... 16
5.6.3 Test Ub
3
Simultaneous bending ..................................................................... 17
5.7 Final measurements .............................................................................................. 17
5.8 Information to be given in the relevant specification .............................................. 17
6 Test Uc: Torsion ............................................................................................................ 18
6.1 Object ................................................................................................................... 18
6.2 Application ............................................................................................................ 18
6.3 General description ............................................................................................... 18
6.4 Preparation of the specimen ................................................................................. 18
6.5 Initial measurements ............................................................................................. 18
6.6 Test procedure ...................................................................................................... 19
6.7 Final measurements .............................................................................................. 20
6.8 Information to be given in the relevant specification .............................................. 20
7 Test Ud: Torque ............................................................................................................ 20
7.1 Object ................................................................................................................... 20
7.2 Application ............................................................................................................ 20
7.3 General description ............................................................................................... 21
7.4 Preconditioning ..................................................................................................... 21
7.5 Initial measurements ............................................................................................. 21
IEC 60068-2-21:2021 © IEC 2021 – 3 –
7.6
Test procedure ...................................................................................................... 21
7.6.1 Terminations with threaded studs or screws .................................................. 21
7.6.2 Other test configurations................................................................................ 23
7.7 Final measurements .............................................................................................. 23
7.8 Information to be given in the relevant specification .............................................. 23
8 Test Ue: Robustness of terminations for SMD in the mounted state ............................... 24
8.1 Object ................................................................................................................... 24
8.2 Application ............................................................................................................ 24
8.3 Substrate for test method Ue ................................................................................ 24
8.4 Mounting ............................................................................................................... 26
8.4.1 Dimensions .................................................................................................... 26
8.4.2 Possible mounting methods ........................................................................... 26
8.4.3 Mounting method for substrate bending, pull-off, push-off and shear ............. 26
8.5 Preconditioning ..................................................................................................... 27
8.6 Initial measurements ............................................................................................. 27
8.7 Test methods ........................................................................................................ 27
8.7.1 Test Ue
1
: Substrate bending test ................................................................... 27
8.7.2 Test Ue
2
: Pull-off and push-off test ................................................................ 28
8.7.3 Test Ue
3
: Shear test ...................................................................................... 30
8.8 Final measurements .............................................................................................. 32
8.8.1 Recovery ....................................................................................................... 32
8.8.2 Visual examination of terminations ................................................................ 32
8.8.3 Electrical characteristics ................................................................................ 32
8.8.4 Hidden defect ................................................................................................ 32
8.9 Information to be given in the relevant specification .............................................. 32
9 Test Uf: Robustness of component body ........................................................................ 34
9.1 Object ................................................................................................................... 34
9.2 Application ............................................................................................................ 34
9.3 General description ............................................................................................... 34
9.4 Preconditioning ..................................................................................................... 34
9.5 Initial measurement .............................................................................................. 34
9.6 Test procedure ...................................................................................................... 34
9.6.1 Test Uf
1
: Body strength ................................................................................. 34
9.6.2 Test Uf
2
: Impact shock .................................................................................. 36
9.7 Final measurements .............................................................................................. 38
9.7.1 Recovery ....................................................................................................... 38
9.7.2 Visual examination ........................................................................................ 39
9.7.3 Electrical characteristics ................................................................................ 39
9.7.4 Hidden defect ................................................................................................ 39
9.8 Information to be given in the relevant specification .............................................. 39
Annex X (informative) Cross-reference for references to the previous editions of this
document .............................................................................................................................. 40
X.1 Cross-reference for references to the previous edition of IEC 60068‑2‑21 ............. 40
X.2 Cross-reference for references to the last edition of IEC 60068‑2‑77 .................... 41
Bibliography .......................................................................................................................... 43
Figure 1 – Direction of the applied pull force F
p
in test Ua
1
..................................................... 9
– 4 – IEC 60068-2-21:2021 © IEC 2021
Figure 2 – Direction of the applied thrust F
t
in test Ua
2
......................................................... 10
Figure 3 – Displacement of pliable lead wires in test Ub ....................................................... 12
Figure 4 – Bending force applied to a specimen with non-pliable terminations ...................... 13
Figure 5 – Sequential test procedure of test Ub, Method 1 .................................................... 15
Figure 6 – Sequential test procedure of test Ub, Methods 2 and 3......................................... 16
Figure 7 – Clamp for the testing of short terminations ........................................................... 17
Figure 8 – Preparatory bending of a lead wire for test Uc ...................................................... 18
Figure 9 – Torsion test method 1: Rotation of clamped specimen body ................................. 19
Figure 10 – Torsion test method 2: Rotation of clamped other lead wire................................ 20
Figure 11 – Assembly for the torque test applied to a threaded stud ..................................... 22
Figure 12 – Preparation of a threaded termination for the torque test .................................... 22
Figure 13 – Assembly for the torque test applied to an embedded nut ................................... 23
Figure 14 – Example of substrate for test method Ue ............................................................ 25
Figure 15 – Substrate bending test ....................................................................................... 28
Figure 16 – Test Ue
2
, pull-off test ......................................................................................... 29
Figure 17 – Test Ue
2
, push-off test ....................................................................................... 30
Figure 18 – Test Ue
3
, shear test ........................................................................................... 31
Figure 19 – SMD Body strength test Uf
1
applied to a rectangular specimen .......................... 35
Figure 20 – SMD Body strength test Uf
1
applied to a MELF specimen .................................. 36
Figure 21 – Example of an apparatus for test Uf
2
.................................................................. 37
Figure 22 – Example of a piston ............................................................................................ 37
Figure 23 – Examples of the application of the SMD Body impact shock test Uf
2
.................. 38
Table 1 – Selection of test methods suitable for specific terminations/leads ............................ 7
Table 2 – Value of applied pull force for test Ua
1
.................................................................. 10
Table 3 – Value of applied thrust for test Ua
2
........................................................................ 11
Table 4 – Value of applied force for test Ub .......................................................................... 13
Table 5 – Torque severity ..................................................................................................... 21
Table X.1 – Cross-reference to clauses ................................................................................ 40
Table X.2 – Cross-reference to figures .................................................................................. 41
Table X.3 – Cross reference to tables ................................................................................... 41
Table X.4 – Cross-reference to clauses ................................................................................ 42
Table X.5 – Cross-reference to figures .................................................................................. 42
