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
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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