BSI PD IEC/TR 63091:2017
$215.11
Study for the derating curve of surface mount fixed resistors. Derating curves based on terminal part temperature
| Published By | Publication Date | Number of Pages |
| BSI | 2017 | 126 |
This Technical Report is applicable to SMD resistors with sizes equal or smaller than the RR6332M, including the typical rectangular and cylindrical SMD resistors mentioned in IEC 60115-8.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 2 | National foreword |
| 4 | CONTENTS |
| 9 | FOREWORD |
| 11 | INTRODUCTION |
| 12 | 1 Scope 2 Normative references 3 Terms and definitions |
| 13 | 4 Study for the derating curve of surface mount fixed resistors 4.1 General |
| 14 | 4.2 Using the derating curve based on the terminal part temperature Figures Figure 1 โ Existing derating curve based on ambient temperature Figure 2 โ Suggested derating curve based on terminal temperature |
| 15 | 4.3 Measuring method of the terminal part temperature of the SMD resistor Figure 3 โ Attachment position of the thermocouple when measuring the temperature of the terminal part |
| 16 | Figure 4 โ Attaching type K thermocouples |
| 17 | Figure 5 โ Wiring routing of the thermocouple |
| 18 | Figure 6 โ The true value and the actual measured value of the terminal part temperature |
| 19 | Figure 7 โ Thermal resistance Rth eq of the FR4 single side board (thickness 1,6 mm) |
| 20 | Figure 8 โ Length that cause the heat dissipation and the thermal resistance of the type-K thermocouple (calculated) |
| 21 | 4.4 Measuring method of the thermal resistance Rth shs-t from the terminal part to the surface hotspot Figure 9 โ Example of calculation of the measurement error โT caused by the heat dissipation of the thermocouple |
| 22 | Figure 10 โ Recommended measurement system of Tshs and Tt for calculating Rth shs-t |
| 23 | 4.5 Conclusions |
| 24 | Annex A (informative) Background of the establishment of the derating curve based on ambient temperature A.1 Tracing the history of the mounting and heat dissipation figuration of resistors Figure A.1 โ Wired in the air using the lug terminal |
| 25 | Figure A.2 โ Heat path when wired in the air using the lug terminal |
| 26 | A.2 How to establish the high temperature slope part of the derating curve A.2.1 General Figure A.3 โ Test condition for resistors with category power 0 W |
| 27 | Figure A.4 โ Test condition for resistors with category power other than 0 W |
| 28 | A.2.2 Derating curve for the semiconductors Figure A.5 โ Example of reviewing the derating curve |
| 29 | Figure A.6 โ Tj, Tc and Rth j-c of transistors |
| 30 | Figure A.7 โ Derating curves for transistors |
| 31 | A.2.3 Derating curve for resistors Figure A.8 โ Trajectory of Tj when P is reduced according to the derating curve |
| 32 | Figure A.9 โ Leaded resistors with small temperature rise |
| 33 | Figure A.10 โ Leaded resistors with large temperature rise Figure A.11 โ Trajectory of Ths for the lead wire resistors with small temperature rise |
| 35 | Figure A.12 โ Trajectory of Ths for the lead wire resistors with large temperature rise |
| 36 | Figure A.13 โ Trajectory of Ths for resistors with category power other than 0 W |
| 37 | Figure A.14 โ Tsp and MAT for lead wire resistors with large temperature rise |
| 38 | Figure A.15 โ Tsp and MAT for lead wire resistors with small temperature rise |
| 39 | Figure A.16 โ Resistors for which the hotspot is the thermally sensitive point |
| 40 | Figure A.17 โ Resistor that have derating curve similar to the semiconductor |
| 42 | Annex B (informative) The temperature rise of SMD resistors and the influence of the printed circuit board B.1 Temperature rise of SMD resistors |
| 43 | Figure B.1 โ Temperature distribution of the SMD resistors mounted on the board |
| 44 | Figure B.2 โ Temperature rise of the SMD resistors from the ambient temperature |
| 45 | Figure B.3 โ Measurement system layout and board dimension |
| 46 | Figure B.4 โ Temperature rise of RR2012M (thickness 35 ฮผm, 0,25 W applied) |
| 47 | B.2 The influence of the printed circuit boards Figure B.5 โ Temperature rise of RR2012M (thickness 70 ฮผm, 0,25 W applied) |
| 48 | Figure B.6 โ Trajectory of the terminal part and hotspot temperature of the SMD resistors |
| 49 | Figure B.7 โ Operating temperature of the resistor on the board with narrow patterns |
| 51 | Annex C (informative) The influence of the number of resistors mounted on the test board C.1 General C.2 The influence of the number of resistors mounted on the test board |
| 52 | Figure C.1 โ Test board compliant with the IEC standard for RR1608M Figure C.2 โ Relation between the number of samples and the surface hotspot temperature rise |
| 53 | C.3 The delay of correspondence for current products with nonstandard dimensions Figure C.3 โ Infrared thermograph image in the same scale whenpower is applied to 5 samples and 20 samples |
| 54 | Annex D (informative) Influence of the air flow in the test chamber D.1 General D.2 Influence of the wind speed |
| 55 | Figure D.1 โ Wind speed and the terminal part temperature rise of the RR6332M Figure D.2 โ Test system for the natural convection flow |
| 56 | Tables Table D.1 โ Number of samples mounted and the applied power |
| 57 | Figure D.3 โ Observing the influence of the agitation wind in the test chamber |
| 58 | Figure D.4 โ Wind speed and the terminal part temperature rise of the RR5025M Figure D.5 โ Wind speed and the terminal part temperature rise of the RR3225M |
| 59 | Figure D.6 โ Wind speed and the terminal part temperature rise of the RR3216M Figure D.7 โ Wind speed and the terminal part temperature rise of the RR2012M |
| 60 | Figure D.8 โ Wind speed and the terminal part temperature rise of the RR1608M Figure D.9 โ Wind speed and the terminal part temperature rise of the RR1005M |
| 62 | Annex E (informative) Validity of the new derating curve E.1 Suggestion for establishing the derating curve based on the terminal part temperature Figure E.1 โ Derating conditions of SMD resistors on the resistor manufacturer test board |
| 65 | Figure E.2 โ New derating curve provided by the resistor manufacturer to the electric/electronic designers |
| 66 | Figure E.3 โ Derating curve based on the terminal part temperature |
| 67 | E.2 Conclusion Figure E.4 โ Derating curve based on the terminal part temperature |
| 69 | Annex F (informative) The thermal resistance of SMD resistors |
| 70 | Figure F.1 โ Definition of the thermal resistance in a strict sense |
| 71 | Figure F.2 โ Thermal resistance of the resistor |
| 74 | Annex G (informative) How to measure the surface hotspot temperature G.1 Target of the measurement G.2 Recommended measuring equipment G.3 Points to be careful when measuring the surface hotspot of the resistor with an infrared thermograph G.3.1 General |
| 75 | G.3.2 Spatial resolution and accuracy of peak temperature measurement |
| 76 | Figure G.1 โ Difference of the measured hotspot temperature caused by the spatial resolution |
| 77 | G.3.3 Influence of the angle of the measurement target normal line and the infrared thermograph light axis |
| 78 | Figure G.2 โ Measuring system for the error caused by the angle |
| 79 | Figure G.3 โ Error caused by the angle of the optical axisand the target surface (natural convection) Figure G.4 โ Error caused by the angle of the optical axisand the target surface (0,3 m/s air ventilation from the side) |
| 81 | Annex H (informative) How the resistor manufacturers measure the thermal resistance of resistors H.1 The measuring system |
| 82 | H.2 Definition of the two kinds of temperatures Figure H.1 โ Measuring system for calculating the thermal resistance between the surface hotspot and the terminal part |
| 83 | Figure H.2 โ Simulation model |
| 84 | Table H.1 โ Results of the fillet part temperature simulation (calculated value) Table H.2 โ Simulation result of the fillet part’s temperature where it is measurable (calculated value) |
| 85 | H.3 Errors in the measurement Table H.3 โ Simulation result of the fillet part’s temperature where it is measurable (calculated value) |
| 86 | Figure H.3 โ Temperature distribution of the copper block surface (calculated) |
| 87 | Table H.4 โ Thermal resistance simulation results between the surface hotspot and the terminal part based on the copper block temperature (calculated value) |
| 88 | Figure H.4 โ Isothermal line of the fillet part (calculated) |
| 90 | Annex I (informative) Measurement method of the terminal part temperature of the SMD resistors I.1 Measuring method using an infrared thermograph |
| 91 | I.2 Measuring method using the thermocouple Figure I.1 โ Temperature drop caused by the attached thermocouple |
| 92 | I.3 Estimating the error range of the temperature measurement using the thermal resistance of the thermocouple I.3.1 General Figure I.2 โ Example of the printed board |
| 93 | Figure I.3 โ Printed board shown with the thermal network |
| 94 | Figure I.4 โ Equivalent circuit of the printed board shown with the thermal network |
| 95 | Figure I.5 โ Equivalent circuit when the thermocouple is connected |
| 96 | Figure I.6 โ Ambient temperature and the space need for the heat dissipation of the thermocouple |
| 97 | Figure I.7 โ Equivalent circuit when the thermocouple is connected |
| 98 | Figure I.8 โ Length that causes the heat dissipation and the thermal resistance of the type K thermocouple (calculated) |
| 99 | I.3.2 When using the type T thermocouples I.4 Thermal resistance of the board Figure I.9 โ Length that cause the heat dissipation and the thermal resistance of the type T thermocouple (calculated) |
| 100 | Figure I.10 โ Thermal resistance Rth eq of the FR4 single side board (thickness 1,6 mm) |
| 101 | Figure I.11 โ Calculating the thermal resistance of the board from the fillet side |
| 102 | I.5 Conclusion of this annex |
| 103 | Annex J (informative) The variation of the heat dissipation fraction caused by the difference between the resistor and its mounting configuration J.1 Heat dissipation ratio of cylindrical resistors wired in the air Figure J.1 โ Simulation model of the lead wire resistors wired in the air |
| 104 | J.2 Heat dissipation ratio of SMD resistors mounted on the board Figure J.2 โ Heat dissipation ratio of the leaded cylindrical resistors (calculated) |
| 105 | Figure J.3 โ Measurement system of the heat dissipation ratio of SMD resistors mounted on the board |
| 106 | J.3 Heat dissipation ratio of the cylindrical resistors mounted on the through-hole printed board Table J.1 โ Analysis result of the heat dissipation ratio of SMD resistors (calculated value and value actually measured) |
| 107 | Annex K (informative) Influence of airflow on SMD resistors K.1 General K.2 Measurement system |
| 108 | K.3 Test results (orthogonal) Figure K.1 โ Measurement system |
| 109 | Figure K.2 โ Relationship between the terminal part temperature rise and the wind speed for the RR6332M (orthogonal) Figure K.3 โ Relationship between the terminal part temperature rise and the wind speed for the RR5025M (orthogonal) |
| 110 | Figure K.4 โ Relationship between the terminal part temperature rise and the wind speed for the RR3225M (orthogonal) Figure K.5 โ Relationship between the terminal part temperature rise and the wind speed for the RR3216M (orthogonal) |
| 111 | Figure K.6 โ Relationship between the terminal part temperature rise and the wind speed for the RR2012M (orthogonal) Figure K.7 โ Relationship between the terminal part temperature rise and the wind speed for the RR1608M (orthogonal) |
| 112 | K.4 Test results (parallel) Figure K.8 โ Relationship between the terminal part temperature rise and the wind speed for the RR1005M (orthogonal) |
| 113 | Figure K.9 โ Relationship between the terminal part temperature rise and the wind speed for the RR6332M (parallel) Figure K.10 โ Relationship between the terminal part temperature rise and the wind speed for the RR5025M (parallel) |
| 114 | Figure K.11 โ Relationship between the terminal part temperature rise and the wind speed for the RR3225M (parallel) Figure K.12 โ Relationship between the terminal part temperature rise and the wind speed for the RR3216M (parallel) |
| 115 | Figure K.13 โ Relationship between the terminal part temperature rise and the wind speed for the RR2012M (parallel) Figure K.14 โ Relationship between the terminal part temperature rise and the wind speed for the RR1608M (parallel) |
| 116 | Figure K.15 โ Relationship between the terminal part temperature rise and the wind speed for the RR1005M (parallel) Figure K.16 โ Terminal part temperature rise of RR6332M, difference between the windward and leeward sides when placed parallel |
| 117 | Annex L (informative) The influence of the spatial resolution of the thermograph L.1 The application for using the thermograph when measuring the temperature of the SMD resistor L.2 The relation between the minimum area that the accurate temperature could be measured and the pixel magnification percentage |
| 118 | Figure L.1 โ Step response of the Gaussian filter of the various cut-off spatial frequencies (calculated) |
| 119 | Figure L.2 โ Temperature distribution (cross-section) when measuring the object that becomes high temperature only in the range of 0,2 mm in diameter |
| 120 | Figure L.3 โ Measuring system of spatial frequency filter of the infrared thermograph |
| 121 | Figure L.4 โ Actual measured value of the step response of various magnifier lenses |
| 122 | L.3 Example of the RR1608M SMD resistor hotspot’s actual measurement Figure L.5 โ Comparison of the actual measured value and the calculated value (step response) |
| 123 | L.4 Conclusion Figure L.6 โ Comparison of the actual measured value and the calculated value (surface hotspot of the resistor) |
| 124 | Annex M (informative) Future subjects |
| 125 | Bibliography |
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BSI PD IEC/TR 63091:2017
Study for the derating curve of surface mount fixed resistors. Derating curves based on terminalโฆ
