Test methods for electrical materials, printed boards and other interconnection structures and assemblies - Part 3-914: Test method for thermal conductivity of printed circuit boards for high-brightness LEDs - Guidelines

IEC TR 61189-3-914:2017(E) specifies the detailed procedures and precautions for IEC 61189-3-913.

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Status
Published
Publication Date
16-Mar-2017
Current Stage
PPUB - Publication issued
Start Date
17-Mar-2017
Completion Date
17-Mar-2017
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IEC TR 61189-3-914:2017 - Test methods for electrical materials, printed boards and other interconnection structures and assemblies - Part 3-914: Test method for thermal conductivity of printed circuit boards for high-brightness LEDs - Guidelines
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IEC TR 61189-3-914
Edition 1.0 2017-03
TECHNICAL
REPORT
colour
inside
Test methods for electrical materials, printed boards and other interconnection
structures and assemblies –
Part 3-914: Test method for thermal conductivity of printed circuit boards for
high-brightness LEDs – Guidelines
IEC TR 61189-3-914:2017-03(en)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC TR 61189-3-914
Edition 1.0 2017-03
TECHNICAL
REPORT
colour
inside
Test methods for electrical materials, printed boards and other interconnection
structures and assemblies –
Part 3-914: Test method for thermal conductivity of printed circuit boards for
high-brightness LEDs – Guidelines
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.180 ISBN 978-2-8322-4110-3

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

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC TR 61189-3-914:2017 © IEC 2017
CONTENTS

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

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

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

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

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

4 Test condition .................................................................................................................. 7

4.1 Standard condition .................................................................................................. 7

4.2 Specified condition .................................................................................................. 8

5 Pre-condition ................................................................................................................... 8

6 Heat dissipation characteristics ....................................................................................... 8

6.1 General ................................................................................................................... 8

6.2 Measurement of thermal resistance on the plane .................................................... 9

6.3 Thermal resistance across the thickness ............................................................... 12

6.4 Thermal resistance measurement procedures and precautions ............................. 14

6.4.1 General ......................................................................................................... 14

6.4.2 Die attach ...................................................................................................... 14

6.4.3 Wire bonding ................................................................................................. 14

6.4.4 Temperature measuring sensor (calibration) .................................................. 14

6.4.5 Measurement of thermal resistance on the plane ........................................... 14

6.4.6 Thermal resistance across the thickness using cold plate .............................. 16

Annex A (informative) Classification and class of the PCB ................................................... 19

Annex B (informative) Measurement comparison between companies (plane) ...................... 22

Figure 1 – Example of PCB with large thermal conductivity ..................................................... 9

Figure 2 – Examples of PCBs with large heat transfer coefficients .......................................... 9

Figure 3 – Illustration of thermal resistance test (for information) .......................................... 10

Figure 4 – Layout of the specimen surface for the thermal resistance test ............................ 11

Figure 5 –Test equipment for thermal resistance across the thickness .................................. 12

Figure 6 – Example of attachment of the specimen ............................................................... 15

Figure 7 – Example of measurement of the thermal resistance on the plane ......................... 16

Figure 8 – Use of the silicone grease .................................................................................... 17

Figure 9 – Test equipment for thermal resistance across the thickness (running water

tank specification) ................................................................................................................. 17

Figure 10 – Test equipment for thermal resistance across the thickness (cold plate) ............ 17

Figure A.1 – Example of classification and their application by base materials, PCBs

and final products ................................................................................................................. 20

Figure A.2 – The relation between thermal conductive parameter (W/(mK)) and heat

transfer coefficient parameter (mapping by substrate) ........................................................... 21

Table 1 – Load heat (W) corresponding to range of thermal resistance on the plane

(K/W) .................................................................................................................................... 12

Table 2 – Load heat (W) corresponding to range of thermal resistance to the direction

of the thickness (K/W) ........................................................................................................... 13

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IEC TR 61189-3-914:2017 © IEC 2017 – 3 –

Table A.1 – Application and classification ............................................................................. 19

Table A.2 – The relation between thermal conductive parameter (W/(mK)) and heat

transfer coefficient parameter (mapping by zone) .................................................................. 21

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– 4 – IEC TR 61189-3-914:2017 © IEC 2017
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
TEST METHODS FOR ELECTRICAL MATERIALS, PRINTED BOARDS
AND OTHER INTERCONNECTION STRUCTURES AND ASSEMBLIES –
Part 3-914: Test method for thermal conductivity of printed
circuit boards for high-brightness LEDs – Guidelines
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

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The main task of IEC technical committees is to prepare International Standards. However, a

technical committee may propose the publication of a technical report when it has collected

data of a different kind from that which is normally published as an International Standard, for

example "state of the art".

IEC TR 61189-3-914, which is a technical report, has been prepared by IEC technical

committee 91: Electronics assembly technology.
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IEC TR 61189-3-914:2017 © IEC 2017 – 5 –
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
91/1378/DTR 91/1403/RVC

Full information on the voting for the approval of this technical report can be found in the

report on voting indicated in the above table.

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

A list of all parts in the IEC 61189 series, published under the general title Test methods for

electrical materials, printed boards and other interconnection structures and assemblies, 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.
A bilingual version of this publication may be issued at a later date.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates

that it contains colours which are considered to be useful for the correct

understanding of its contents. Users should therefore print this document using a

colour printer.
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– 6 – IEC TR 61189-3-914:2017 © IEC 2017
INTRODUCTION

Development of this technical report has been discussed at TC 91 Plenary meeting in

Dongguan, China, October 30, 2015 as per 91/1343A/RM dated on January 22, 2016.
This document was developed as a supplementary document to the IEC 61189-3-913.
Therefore, this document has been developed as technical report.
This document is given for information only.
---------------------- Page: 8 ----------------------
IEC TR 61189-3-914:2017 © IEC 2017 – 7 –
TEST METHODS FOR ELECTRICAL MATERIALS, PRINTED BOARDS
AND OTHER INTERCONNECTION STRUCTURES AND ASSEMBLIES –
Part 3-914: Test method for thermal conductivity of printed
circuit boards for high-brightness LEDs – Guidelines
1 Scope

This document specifies the detailed procedures and precautions for IEC 61189-3-913.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their

content constitutes requirements 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 60194, Printed board design, manufacture and assembly – Terms and definitions

IEC 60068-1:2013, Environmental testing – Part 1: General and guidance
IEC 61189-3-913, Test methods for electrical materials, printed boards and other

interconnection structures and assemblies – Part 3-913: Test method for thermal conductivity

of electronic circuit boards for high-brightness LEDs

EIA/JEDEC STD 51-2, Integrated circuits thermal test method – Environmental conditions –

Natural convection (still air)
3 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC 60194 apply, unless

otherwise specified.

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
4 Test condition
4.1 Standard condition

Unless otherwise specified, tests should all be operated under the following standardized

conditions in accordance with the IEC 60068-1:2013, Clause 4:
• temperature: 15 °C to 35 °C;
• relative humidity: 25 % to 75 %;
• atmospheric pressure: 86 kPa to 106 kPa.
---------------------- Page: 9 ----------------------
– 8 – IEC TR 61189-3-914:2017 © IEC 2017

If there is any doubt concerning the testing results under standardized condition, or upon a

request to check the atmospheric condition, the re-examination should be operated under

atmosphere in accordance with IEC 60068-1:2013.

If the standardized atmosphere is difficult to provide, testing under non-standardized

atmosphere is acceptable as long as the atmospheric condition does not affect the testing

results.
4.2 Specified condition

The specified condition should be in accordance with the condition specified in IEC 60068-

1:2013, Clause 4:
• temperature: 20 °C ± 2 °C;
• relative humidity: 60 % to 70 %;
• atmospheric pressure: 86 kPa to 106 kPa.
5 Pre-condition
Pre-conditioning should be in accordance with a) or b) below:
a) leave the specimen for 24 h in the standard condition;

b) leave the specimen for 60 min in a thermostat chamber at 85 °C ± 2 °C and then leave the

specimen for 24 h ± 4 h in the standard atmospheric condition.

NOTE This test element group (hereafter, referred to as TEG) chip includes a heater with a temperature

measuring sensor. In this document, the TEG chip indicates a chip with a temperature measuring sensor.

6 Heat dissipation characteristics
6.1 General

For the test method for thermal conductivity of a printed circuit board (hereafter referred to as

PCB) for high-brightness LEDs, the following factors are considered.

• The test method is applied to evaluate the relativity of both heat transfer and thermal

conductivity of PCBs consist of heterogeneous materials as shown in Figure A.2 in Annex

A which describes the heat transfer coefficient parameter as X-axis and thermal
conductivity parameter as Y-axis.

• The IEC 61189-3-913 employs a TEG chip as the heat source to replicate the heat

generated by LED chips.

• Heat dissipation characteristics of PCBs depend not only on the thermal conductivity of

the material properties, but also on the structure.

• In addition, convection and radiation from the specimen surface should be considered as

factors to affect the testing results.

• Considering the anisotropic nature of the heat dissipation of PCBs, different test methods

are employed for the plane (horizontal) and across the thickness (vertical) direction. The

combination of these tests should replicate a realistic environment.
• A TEG chip is employed with following considerations:
– measuring a small heat source such as an LED with thermocouples;
– ac
...

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