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.<\/p>\n
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| 2<\/td>\n | undefined <\/td>\n<\/tr>\n | ||||||
| 4<\/td>\n | CONTENTS <\/td>\n<\/tr>\n | ||||||
| 9<\/td>\n | FOREWORD <\/td>\n<\/tr>\n | ||||||
| 11<\/td>\n | INTRODUCTION <\/td>\n<\/tr>\n | ||||||
| 12<\/td>\n | 1 Scope 2 Normative references 3 Terms and definitions <\/td>\n<\/tr>\n | ||||||
| 13<\/td>\n | 4 Study for the derating curve of surface mount fixed resistors 4.1 General <\/td>\n<\/tr>\n | ||||||
| 14<\/td>\n | 4.2 Using the derating curve based on the terminal part temperature Figures Figure 1 \u2013 Existing derating curve based on ambient temperature Figure 2 \u2013 Suggested derating curve based on terminal temperature <\/td>\n<\/tr>\n | ||||||
| 15<\/td>\n | 4.3 Measuring method of the terminal part temperature of the SMD resistor Figure 3 \u2013 Attachment position of the thermocouple when measuring the temperature of the terminal part <\/td>\n<\/tr>\n | ||||||
| 16<\/td>\n | Figure 4 \u2013 Attaching type K thermocouples <\/td>\n<\/tr>\n | ||||||
| 17<\/td>\n | Figure 5 \u2013 Wiring routing of the thermocouple <\/td>\n<\/tr>\n | ||||||
| 18<\/td>\n | Figure 6 \u2013 The true value and the actual measured value of the terminal part temperature <\/td>\n<\/tr>\n | ||||||
| 19<\/td>\n | Figure 7 \u2013 Thermal resistance Rth eq of the FR4 single side board (thickness 1,6 mm) <\/td>\n<\/tr>\n | ||||||
| 20<\/td>\n | Figure 8 \u2013 Length that cause the heat dissipation and the thermal resistance of the type-K thermocouple (calculated) <\/td>\n<\/tr>\n | ||||||
| 21<\/td>\n | 4.4 Measuring method of the thermal resistance Rth shs-t from the terminal part to the surface hotspot Figure 9 \u2013 Example of calculation of the measurement error \u2206T caused by the heat dissipation of the thermocouple <\/td>\n<\/tr>\n | ||||||
| 22<\/td>\n | Figure 10 \u2013 Recommended measurement system of Tshs and Tt for calculating Rth shs-t <\/td>\n<\/tr>\n | ||||||
| 23<\/td>\n | 4.5 Conclusions <\/td>\n<\/tr>\n | ||||||
| 24<\/td>\n | 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 \u2013 Wired in the air using the lug terminal <\/td>\n<\/tr>\n | ||||||
| 25<\/td>\n | Figure A.2 \u2013 Heat path when wired in the air using the lug terminal <\/td>\n<\/tr>\n | ||||||
| 26<\/td>\n | A.2 How to establish the high temperature slope part of the derating curve A.2.1 General Figure A.3 \u2013 Test condition for resistors with category power 0 W <\/td>\n<\/tr>\n | ||||||
| 27<\/td>\n | Figure A.4 \u2013 Test condition for resistors with category power other than 0 W <\/td>\n<\/tr>\n | ||||||
| 28<\/td>\n | A.2.2 Derating curve for the semiconductors Figure A.5 \u2013 Example of reviewing the derating curve <\/td>\n<\/tr>\n | ||||||
| 29<\/td>\n | Figure A.6 \u2013 Tj, Tc and Rth j-c of transistors <\/td>\n<\/tr>\n | ||||||
| 30<\/td>\n | Figure A.7 \u2013 Derating curves for transistors <\/td>\n<\/tr>\n | ||||||
| 31<\/td>\n | A.2.3 Derating curve for resistors Figure A.8 \u2013 Trajectory of Tj when P is reduced according to the derating curve <\/td>\n<\/tr>\n | ||||||
| 32<\/td>\n | Figure A.9 \u2013 Leaded resistors with small temperature rise <\/td>\n<\/tr>\n | ||||||
| 33<\/td>\n | Figure A.10 \u2013 Leaded resistors with large temperature rise Figure A.11 \u2013 Trajectory of Ths for the lead wire resistors with small temperature rise <\/td>\n<\/tr>\n | ||||||
| 35<\/td>\n | Figure A.12 \u2013 Trajectory of Ths for the lead wire resistors with large temperature rise <\/td>\n<\/tr>\n | ||||||
| 36<\/td>\n | Figure A.13 \u2013 Trajectory of Ths for resistors with category power other than 0 W <\/td>\n<\/tr>\n | ||||||
| 37<\/td>\n | Figure A.14 \u2013 Tsp and MAT for lead wire resistors with large temperature rise <\/td>\n<\/tr>\n | ||||||
| 38<\/td>\n | Figure A.15 \u2013 Tsp and MAT for lead wire resistors with small temperature rise <\/td>\n<\/tr>\n | ||||||
| 39<\/td>\n | Figure A.16 \u2013 Resistors for which the hotspot is the thermally sensitive point <\/td>\n<\/tr>\n | ||||||
| 40<\/td>\n | Figure A.17 \u2013 Resistor that have derating curve similar to the semiconductor <\/td>\n<\/tr>\n | ||||||
| 42<\/td>\n | Annex B (informative) The temperature rise of SMD resistors and the influence of the printed circuit board B.1 Temperature rise of SMD resistors <\/td>\n<\/tr>\n | ||||||
| 43<\/td>\n | Figure B.1 \u2013 Temperature distribution of the SMD resistors mounted on the board <\/td>\n<\/tr>\n | ||||||
| 44<\/td>\n | Figure B.2 \u2013 Temperature rise of the SMD resistors from the ambient temperature <\/td>\n<\/tr>\n | ||||||
| 45<\/td>\n | Figure B.3 \u2013 Measurement system layout and board dimension <\/td>\n<\/tr>\n | ||||||
| 46<\/td>\n | Figure B.4 \u2013 Temperature rise of RR2012M (thickness 35 \u03bcm, 0,25 W applied) <\/td>\n<\/tr>\n | ||||||
| 47<\/td>\n | B.2 The influence of the printed circuit boards Figure B.5 \u2013 Temperature rise of RR2012M (thickness 70 \u03bcm, 0,25 W applied) <\/td>\n<\/tr>\n | ||||||
| 48<\/td>\n | Figure B.6 \u2013 Trajectory of the terminal part and hotspot temperature of the SMD resistors <\/td>\n<\/tr>\n | ||||||
| 49<\/td>\n | Figure B.7 \u2013 Operating temperature of the resistor on the board with narrow patterns <\/td>\n<\/tr>\n | ||||||
| 51<\/td>\n | 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 <\/td>\n<\/tr>\n | ||||||
| 52<\/td>\n | Figure C.1 \u2013 Test board compliant with the IEC standard for RR1608M Figure C.2 \u2013 Relation between the number of samples and the surface hotspot temperature rise <\/td>\n<\/tr>\n | ||||||
| 53<\/td>\n | C.3 The delay of correspondence for current products with nonstandard dimensions Figure C.3 \u2013 Infrared thermograph image in the same scale whenpower is applied to 5 samples and 20 samples <\/td>\n<\/tr>\n | ||||||
| 54<\/td>\n | Annex D (informative) Influence of the air flow in the test chamber D.1 General D.2 Influence of the wind speed <\/td>\n<\/tr>\n | ||||||
| 55<\/td>\n | Figure D.1 \u2013 Wind speed and the terminal part temperature rise of the RR6332M Figure D.2 \u2013 Test system for the natural convection flow <\/td>\n<\/tr>\n | ||||||
| 56<\/td>\n | Tables Table D.1 \u2013 Number of samples mounted and the applied power <\/td>\n<\/tr>\n | ||||||
| 57<\/td>\n | Figure D.3 \u2013 Observing the influence of the agitation wind in the test chamber <\/td>\n<\/tr>\n | ||||||
| 58<\/td>\n | Figure D.4 \u2013 Wind speed and the terminal part temperature rise of the RR5025M Figure D.5 \u2013 Wind speed and the terminal part temperature rise of the RR3225M <\/td>\n<\/tr>\n | ||||||
| 59<\/td>\n | Figure D.6 \u2013 Wind speed and the terminal part temperature rise of the RR3216M Figure D.7 \u2013 Wind speed and the terminal part temperature rise of the RR2012M <\/td>\n<\/tr>\n | ||||||
| 60<\/td>\n | Figure D.8 \u2013 Wind speed and the terminal part temperature rise of the RR1608M Figure D.9 \u2013 Wind speed and the terminal part temperature rise of the RR1005M <\/td>\n<\/tr>\n | ||||||
| 62<\/td>\n | 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 \u2013 Derating conditions of SMD resistors on the resistor manufacturer test board <\/td>\n<\/tr>\n | ||||||
| 65<\/td>\n | Figure E.2 \u2013 New derating curve provided by the resistor manufacturer to the electric\/electronic designers <\/td>\n<\/tr>\n | ||||||
| 66<\/td>\n | Figure E.3 \u2013 Derating curve based on the terminal part temperature <\/td>\n<\/tr>\n | ||||||
| 67<\/td>\n | E.2 Conclusion Figure E.4 \u2013 Derating curve based on the terminal part temperature <\/td>\n<\/tr>\n | ||||||
| 69<\/td>\n | Annex F (informative) The thermal resistance of SMD resistors <\/td>\n<\/tr>\n | ||||||
| 70<\/td>\n | Figure F.1 \u2013 Definition of the thermal resistance in a strict sense <\/td>\n<\/tr>\n | ||||||
| 71<\/td>\n | Figure F.2 \u2013 Thermal resistance of the resistor <\/td>\n<\/tr>\n | ||||||
| 74<\/td>\n | 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 <\/td>\n<\/tr>\n | ||||||
| 75<\/td>\n | G.3.2 Spatial resolution and accuracy of peak temperature measurement <\/td>\n<\/tr>\n | ||||||
| 76<\/td>\n | Figure G.1 \u2013 Difference of the measured hotspot temperature caused by the spatial resolution <\/td>\n<\/tr>\n | ||||||
| 77<\/td>\n | G.3.3 Influence of the angle of the measurement target normal line and the infrared thermograph light axis <\/td>\n<\/tr>\n | ||||||
| 78<\/td>\n | Figure G.2 \u2013 Measuring system for the error caused by the angle <\/td>\n<\/tr>\n | ||||||
| 79<\/td>\n | Figure G.3 \u2013 Error caused by the angle of the optical axisand the target surface (natural convection) Figure G.4 \u2013 Error caused by the angle of the optical axisand the target surface (0,3 m\/s air ventilation from the side) <\/td>\n<\/tr>\n | ||||||
| 81<\/td>\n | Annex H (informative) How the resistor manufacturers measure the thermal resistance of resistors H.1 The measuring system <\/td>\n<\/tr>\n | ||||||
| 82<\/td>\n | H.2 Definition of the two kinds of temperatures Figure H.1 \u2013 Measuring system for calculating the thermal resistance between the surface hotspot and the terminal part <\/td>\n<\/tr>\n | ||||||
| 83<\/td>\n | Figure H.2 \u2013 Simulation model <\/td>\n<\/tr>\n | ||||||
| 84<\/td>\n | Table H.1 \u2013 Results of the fillet part temperature simulation (calculated value) Table H.2 \u2013 Simulation result of the fillet part’s temperature where it is measurable (calculated value) <\/td>\n<\/tr>\n | ||||||
| 85<\/td>\n | H.3 Errors in the measurement Table H.3 \u2013 Simulation result of the fillet part’s temperature where it is measurable (calculated value) <\/td>\n<\/tr>\n | ||||||
| 86<\/td>\n | Figure H.3 \u2013 Temperature distribution of the copper block surface (calculated) <\/td>\n<\/tr>\n | ||||||
| 87<\/td>\n | Table H.4 \u2013 Thermal resistance simulation results between the surface hotspot and the terminal part based on the copper block temperature (calculated value) <\/td>\n<\/tr>\n | ||||||
| 88<\/td>\n | Figure H.4 \u2013 Isothermal line of the fillet part (calculated) <\/td>\n<\/tr>\n | ||||||
| 90<\/td>\n | Annex I (informative) Measurement method of the terminal part temperature of the SMD resistors I.1 Measuring method using an infrared thermograph <\/td>\n<\/tr>\n | ||||||
| 91<\/td>\n | I.2 Measuring method using the thermocouple Figure I.1 \u2013 Temperature drop caused by the attached thermocouple <\/td>\n<\/tr>\n | ||||||
| 92<\/td>\n | I.3 Estimating the error range of the temperature measurement using the thermal resistance of the thermocouple I.3.1 General Figure I.2 \u2013 Example of the printed board <\/td>\n<\/tr>\n | ||||||
| 93<\/td>\n | Figure I.3 \u2013 Printed board shown with the thermal network <\/td>\n<\/tr>\n | ||||||
| 94<\/td>\n | Figure I.4 \u2013 Equivalent circuit of the printed board shown with the thermal network <\/td>\n<\/tr>\n | ||||||
| 95<\/td>\n | Figure I.5 \u2013 Equivalent circuit when the thermocouple is connected <\/td>\n<\/tr>\n | ||||||
| 96<\/td>\n | Figure I.6 \u2013 Ambient temperature and the space need for the heat dissipation of the thermocouple <\/td>\n<\/tr>\n | ||||||
| 97<\/td>\n | Figure I.7 \u2013 Equivalent circuit when the thermocouple is connected <\/td>\n<\/tr>\n | ||||||
| 98<\/td>\n | Figure I.8 \u2013 Length that causes the heat dissipation and the thermal resistance of the type K thermocouple (calculated) <\/td>\n<\/tr>\n | ||||||
| 99<\/td>\n | I.3.2 When using the type T thermocouples I.4 Thermal resistance of the board Figure I.9 \u2013 Length that cause the heat dissipation and the thermal resistance of the type T thermocouple (calculated) <\/td>\n<\/tr>\n | ||||||
| 100<\/td>\n | Figure I.10 \u2013 Thermal resistance Rth eq of the FR4 single side board (thickness 1,6 mm) <\/td>\n<\/tr>\n | ||||||
| 101<\/td>\n | Figure I.11 \u2013 Calculating the thermal resistance of the board from the fillet side <\/td>\n<\/tr>\n | ||||||
| 102<\/td>\n | I.5 Conclusion of this annex <\/td>\n<\/tr>\n | ||||||
| 103<\/td>\n | 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 \u2013 Simulation model of the lead wire resistors wired in the air <\/td>\n<\/tr>\n | ||||||
| 104<\/td>\n | J.2 Heat dissipation ratio of SMD resistors mounted on the board Figure J.2 \u2013 Heat dissipation ratio of the leaded cylindrical resistors (calculated) <\/td>\n<\/tr>\n | ||||||
| 105<\/td>\n | Figure J.3 \u2013 Measurement system of the heat dissipation ratio of SMD resistors mounted on the board <\/td>\n<\/tr>\n | ||||||
| 106<\/td>\n | J.3 Heat dissipation ratio of the cylindrical resistors mounted on the through-hole printed board Table J.1 \u2013 Analysis result of the heat dissipation ratio of SMD resistors (calculated value and value actually measured) <\/td>\n<\/tr>\n | ||||||
| 107<\/td>\n | Annex K (informative) Influence of airflow on SMD resistors K.1 General K.2 Measurement system <\/td>\n<\/tr>\n | ||||||
| 108<\/td>\n | K.3 Test results (orthogonal) Figure K.1 \u2013 Measurement system <\/td>\n<\/tr>\n | ||||||
| 109<\/td>\n | Figure K.2 \u2013 Relationship between the terminal part temperature rise and the wind speed for the RR6332M (orthogonal) Figure K.3 \u2013 Relationship between the terminal part temperature rise and the wind speed for the RR5025M (orthogonal) <\/td>\n<\/tr>\n | ||||||
| 110<\/td>\n | Figure K.4 \u2013 Relationship between the terminal part temperature rise and the wind speed for the RR3225M (orthogonal) Figure K.5 \u2013 Relationship between the terminal part temperature rise and the wind speed for the RR3216M (orthogonal) <\/td>\n<\/tr>\n | ||||||
| 111<\/td>\n | Figure K.6 \u2013 Relationship between the terminal part temperature rise and the wind speed for the RR2012M (orthogonal) Figure K.7 \u2013 Relationship between the terminal part temperature rise and the wind speed for the RR1608M (orthogonal) <\/td>\n<\/tr>\n | ||||||
| 112<\/td>\n | K.4 Test results (parallel) Figure K.8 \u2013 Relationship between the terminal part temperature rise and the wind speed for the RR1005M (orthogonal) <\/td>\n<\/tr>\n | ||||||
| 113<\/td>\n | Figure K.9 \u2013 Relationship between the terminal part temperature rise and the wind speed for the RR6332M (parallel) Figure K.10 \u2013 Relationship between the terminal part temperature rise and the wind speed for the RR5025M (parallel) <\/td>\n<\/tr>\n | ||||||
| 114<\/td>\n | Figure K.11 \u2013 Relationship between the terminal part temperature rise and the wind speed for the RR3225M (parallel) Figure K.12 \u2013 Relationship between the terminal part temperature rise and the wind speed for the RR3216M (parallel) <\/td>\n<\/tr>\n | ||||||
| 115<\/td>\n | Figure K.13 \u2013 Relationship between the terminal part temperature rise and the wind speed for the RR2012M (parallel) Figure K.14 \u2013 Relationship between the terminal part temperature rise and the wind speed for the RR1608M (parallel) <\/td>\n<\/tr>\n | ||||||
| 116<\/td>\n | Figure K.15 \u2013 Relationship between the terminal part temperature rise and the wind speed for the RR1005M (parallel) Figure K.16 \u2013 Terminal part temperature rise of RR6332M, difference between the windward and leeward sides when placed parallel <\/td>\n<\/tr>\n | ||||||
| 117<\/td>\n | 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 <\/td>\n<\/tr>\n | ||||||
| 118<\/td>\n | Figure L.1 \u2013 Step response of the Gaussian filter of the various cut-off spatial frequencies (calculated) <\/td>\n<\/tr>\n | ||||||
| 119<\/td>\n | Figure L.2 \u2013 Temperature distribution (cross-section) when measuring the object that becomes high temperature only in the range of 0,2 mm in diameter <\/td>\n<\/tr>\n | ||||||
| 120<\/td>\n | Figure L.3 \u2013 Measuring system of spatial frequency filter of the infrared thermograph <\/td>\n<\/tr>\n | ||||||
| 121<\/td>\n | Figure L.4 \u2013 Actual measured value of the step response of various magnifier lenses <\/td>\n<\/tr>\n | ||||||
| 122<\/td>\n | L.3 Example of the RR1608M SMD resistor hotspot’s actual measurement Figure L.5 \u2013 Comparison of the actual measured value and the calculated value (step response) <\/td>\n<\/tr>\n | ||||||
| 123<\/td>\n | L.4 Conclusion Figure L.6 \u2013 Comparison of the actual measured value and the calculated value (surface hotspot of the resistor) <\/td>\n<\/tr>\n | ||||||
| 124<\/td>\n | Annex M (informative) Future subjects <\/td>\n<\/tr>\n | ||||||
| 125<\/td>\n | Bibliography <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" Study for the derating curve of surface mount fixed resistors. Derating curves based on terminal part temperature<\/b><\/p>\n |