IEC 61191-6:2010

Printed board assemblies - Part 6: Evaluation criteria for voids in soldered joints of BGA and LGA and measurement method

IEC 61191-6:2010 specifies the evaluation criteria for voids on the scale of the thermal cycle life, and the measurement method of voids using X-ray observation. This part of IEC 61191 is applicable to the voids generated in the solder joints of BGA and LGA soldered on a board. This part of IEC 61191 is not applicable to the BGA package itself before it is assembled on a board. This standard is applicable also to devices having joints made by melt and re-solidification, such as flip chip devices and multi-chip modules, in addition to BGA and LGA. This standard is not applicable to joints with under-fill between a device and a board, or to solder joints within a device package. This standard is applicable to macrovoids of the sizes of from 10 µm to several hundred micrometres generated in a soldered joint, but is not applicable to smaller voids (typically, planar microvoids) with a size of smaller than 10 µm in diameter. This standard is intended for evaluation purposes and is applicable to research studies, off-line production process control and reliability assessment of assembly.

Ensembles de cartes imprimées - Partie 6: Critères d'évaluation des vides dans les joints brasés des boîtiers BGA et LGA et méthode de mesure

La CEI 61191-6:2010 spécifie les critères d'évaluation pour les vides à l'échelle de la durée de vie du cycle thermique et la méthode de mesure des vides au moyen d'observations aux rayons X. La présente partie de la CEI 61191 s'applique aux vides générés dans les joints de brasure des boîtiers BGA et LGA brasés sur une carte. La présente partie de la CEI 61191 ne s'applique pas au boîtier BGA lui-même avant qu'il ne soit assemblé sur une carte. La présente norme s'applique également aux dispositifs dont les joints sont réalisés par fusion et resolidification, tels que les dispositifs à puce retournée (flip chip) et les modules multipuce, en plus des BGA et des LGA. La présente norme ne s'applique pas aux joints présentant un manque de métal entre un dispositif et une carte ni aux joints de brasure à l'intérieur d'un boîtier de dispositif. La présente norme s'applique aux macrovides de tailles compris entre 10 µm et plusieurs centaines de micromètres se produisant dans un joint brasé, mais elle ne s'applique pas aux vides plus petits (typiquement, microvides planaires) dont le diamètre est inférieur à 10 µm. La présente norme est destinée à l'évaluation et s'applique aux études de recherche, contrôle du processus de fabrication hors ligne et évaluation de la fiabilité de l'assemblage.

General Information

• Status: Published
• Publication Date: 13-Jan-2010
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 31.180 - Printed circuits and boards
• Technical Committee: TC 91 - Electronics assembly technology
• Drafting Committee: WG 2 - TC 91/WG 2
• Current Stage: PPUB - Publication issued
• Start Date: 31-Jan-2010
• Completion Date: 14-Jan-2010

Standards Content (Sample)

IEC 61191-6 ®
Edition 1.0 2010-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Printed board assemblies –
Part 6: Evaluation criteria for voids in soldered joints of BGA and LGA and
measurement method
Ensembles de cartes imprimées –
Partie 6: Critères d’évaluation des vides dans les joints brasés des boîtiers BGA
et LGA et méthode de mesure
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IEC 61191-6 ®
Edition 1.0 2010-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Printed board assemblies –
Part 6: Evaluation criteria for voids in soldered joints of BGA and LGA and
measurement method
Ensembles de cartes imprimées –
Partie 6: Critères d’évaluation des vides dans les joints brasés des boîtiers BGA
et LGA et méthode de mesure
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
W
CODE PRIX
ICS 31.180 ISBN 978-2-88910-439-0
– 2 – 61191-6 © IEC:2010
CONTENTS
FOREWORD.4
INTRODUCTION.6
1 Scope.7
2 Normative references .7
3 Terms and definitions .7
4 Voids in solder joints .8
4.1 General .8
4.2 Sources of voids.8
4.3 Impact of voids .9
4.4 Void detection .9
4.5 Void classification .9
5 Measurement .10
5.1 X-ray transmission equipment .10
5.2 Measuring environment .10
5.3 Measurement procedure.10
5.4 Record of the measured value.11
5.5 Considerations on measurement .11
5.5.1 X-ray intensity for void detection.11
5.5.2 Detection of real edge .11
5.5.3 Verification of measurement results.11
6 Void occupancy .11
6.1 Calculation of void occupancy .11
6.2 Void occupancy for multiple voids.14
7 Evaluation .14
7.1 Soldered joints to be evaluated .14
7.2 Evaluation of thermal life cycle decreased due to voids .14
7.3 Evaluation criteria for voids .15
Annex A (informative) Experimental results and simulation of voids and decrease of
life due to thermal stress.16
Annex B (informative) X-ray transmission equipment .20
Annex C (informative) Voids in BGA solder ball .22
Annex D (informative) Measurement using X-ray transmission imaging.34
Bibliography.38

Figure 1 – Void occupancy.13
Figure 2 – Voids in a soldered joint.15
Figure A.1 – BGA soldered joint, Sn-Ag-Cu.17
Figure A.2 – BGA soldered joint, Sn-Zn .17
Figure A.3 – LGA soldered joint .18
Figure B.1 – Construction of the equipment .20
Figure C.1 – Small voids clustered in mass at the ball-to-land interface .26
Figure C.2 – X-ray image of solder balls with voids.27
Figure C.3 – Example of voided area at land and board interface .27
Figure C.4 – Voids in BGAs with crack started at corner lead.31

61191-6 © IEC:2010 – 3 –
Figure D.1 – X-ray transmission imaging.35
Figure D.2 – X-ray transmission imaging of solder joint.36
Figure D.3 – Typical X-ray transmission images of solder joint.36

Table 1 – Void classification .9
Table 2 – Examples of Cross-section of joint and void occupancy.14
Table A.1 – Fatigue life reduced by voids in soldered joint of BGA.17
Table A.2 – Fatigue life reduced by voids in soldered joint of LGA .18
Table A.3 – Voids evaluation criteria for soldered joints of BGA.19
Table A.4 – Voids evaluation criteria for soldered joints of LGA .19
Table C.1 – Void classification .27
Table C.2 – Corrective action indicator for lands used with 1,5 mm, 1,27 mm or
1,0 mm pitch .28
Table C.3 – Corrective action indicator for lands used with 0,8 mm, 0,65 mm or 0,5 mm
pitch .30
Table C.4 – Corrective action indicator for micro-via in-pad lands used with 0,5 mm,
0,4 mm or 0,3 mm pitch .32
Table C.5 – Ball-to-void size image comparison for common ball contact diameters .33
Table C.6 – C = 0 sampling plan (sample size for specific index value).33

– 4 – 61191-6 © IEC:2010
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PRINTED BOARD ASSEMBLIES –
Part 6: Evaluation criteria for voids in soldered joints of BGA
and LGA and measurement method

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