1、 IEC TR 63091 Edition 1.0 2017-05 TECHNICA L REPOR T Study for the derating curv e of surface mount fixed resistors Derating curv es based on terminal part temperature IEC TR 63091:2017-05(en)THIS PUBLICA TION IS COPYRIGHT PROTECTED Copyright 2017 IEC,Geneva,Switzerland All rights reserved.Unless ot
2、herwise specified,no par t of this publication may be reproduced or utilized in any for m or by any means,electronic or mechanical,including photocopying and microfilm,without per mission in writing fr om either IEC or IECs member National Committee in the country of the requester.If you have any qu
3、estions about IEC copyright or have an enquiry about obtaining additional r ights to this publication,please contact the address below or your local IEC member National Committee for further infor mation.IEC Centr al Office Tel.:+41 22 919 02 11 3,rue de Varemb Fax:+41 22 919 03 00 CH-1211 Geneva 20
4、 infoiec.ch Switzerland www.iec.ch About t he IEC The International Electr otechnical Commission(IEC)is the leading global organization that prepar es and publishes Inter national Standards for all electr ical,electronic and related technologies.A bout IEC publications The technical content of IEC p
5、ublications is kept under constant review by the IEC.Please make sur e that you have the latest edition,a cor rigenda or an amendment might have been published.IEC Cat alogue-webstore.iec.ch/cat alogue The stand-alone application for consulting the entire bibliographical information on IEC Internati
6、onal Standards,Technical Specifications,Technical R eports and other documents.A v ailable for PC,Mac OS,A ndroid Tablets and iPad.IEC publications search-w w w.iec.ch/searchpub The adv anced search enables to find IEC publications by a variety of criteria(reference number,text,technical committee,)
7、.It also gives information on projec ts,replaced and withdrawn publications.IEC Just Published-webstore.iec.ch/justpublished Stay up to date on all new IEC publications.Just Published details all new publications released.A v ailable online and also once a month by email.Elect ropedia-w w w.elect ro
8、pedia.org The worlds leading online dic tionary of elec tronic and electrical terms containing 20 000 terms and definitions in English and French,with equiv alent terms in 16 additional languages.Also known as the International Electrotechnical Vocabulary (IEV)online.IEC Glossar y-st d.iec.ch/glossa
9、ry 65 000 elec trotechnical terminology entries in English and French extracted from the Terms and Definitions clause of IEC publications issued since 2002.Some entries hav e been collected from earlier publications of IEC TC 37,77,86 and CISPR.IEC Customer Service Cent re-webstore.iec.ch/csc If y o
10、u wish to giv e us y our feedback on this publication or need further assistance,please contact the Customer Serv ice Centre:csciec.ch.IEC TR 63091 Edit ion 1.0 2017-05 TECHNICA L R EPOR T Study for the derating curv e of surface mount fixed resistors Derating curv es based on terminal part temperat
11、ure INTERNATIONAL ELECTROTECHNICAL COMMISSION ICS 31.040.10 ISBN 978-2-8322-4368-8 R egist er ed tr ademar k of t he Int er national Electr ot echnical Commission W arning!Make sure that y ou obtained this publication from an authorized distributor.2 IEC TR 63091:2017 IEC 2017 CONTENTS FOREWORD.7 IN
12、TRODUCTION.9 1 Scope.10 2 Normative references.10 3 Terms and definitions.10 4 Study for the derating curve of surface mount fixed resistors.11 4.1 General.11 4.2 Using the derating curve based on the terminal part temperature.12 4.3 Measuring method of the terminal part temperature of the SMD resis
13、tor.13 4.4 Measuring method of the thermal resistance Rth shs-t from the terminal part to the surface hotspot.19 4.5 Conclusions.21 Annex A(informative)Background of the establishment of the derating curve based on ambient temperature.22 A.1 Tracing the history of the mounting and heat dissipation f
14、iguration of resistors.22 A.2 How to establish the high temperature slope part of the derating curve.24 A.2.1 General.24 A.2.2 Derating curve for the semiconductors.26 A.2.3 Derating curve for resistors.29 Annex B(informative)The temperature rise of SMD resistors and the influence of the printed cir
15、cuit board.40 B.1 Temperature rise of SMD resistors.40 B.2 The influence of the printed circuit boards.45 Annex C(informative)The influence of the number of resistors mounted on the test board.49 C.1 General.49 C.2 The influence of the number of resistors mounted on the test board.49 C.3 The delay o
16、f correspondence for current products with nonstandard dimensions.51 Annex D(informative)Influence of the air flow in the test chamber.52 D.1 General.52 D.2 Influence of the wind speed.52 Annex E(informative)Validity of the new derating curve.60 E.1 Suggestion for establishing the derating curve based on the terminal part temperature.60 E.2 Conclusion.65 Annex F(informative)The thermal resistance of SMD resistors.67 Annex G(informative)How to measure the surface hotspot temperature.72 G.1 Target
