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PD IEC/TR 63091:2017 Study for the derating curve of surface mount fixed resistors. Derating curves based on terminal part temperature, 2017
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- CONTENTS
- FOREWORD
- INTRODUCTION
- 1 Scope
- 2 Normative references
- 3 Terms and definitions
- 4 Study for the derating curve of surface mount fixed resistors [Go to Page]
- 4.1 General
- 4.2 Using the derating curve based on the terminal part temperature
- Figures [Go to Page]
- Figure 1 – Existing derating curve based on ambient temperature
- Figure 2 – Suggested derating curve based on terminal temperature
- 4.3 Measuring method of the terminal part temperature of the SMD resistor
- Figure 3 – Attachment position of the thermocouple when measuring the temperature of the terminal part
- Figure 4 – Attaching type K thermocouples
- Figure 5 – Wiring routing of the thermocouple
- Figure 6 – The true value and the actual measured value of the terminal part temperature
- Figure 7 – Thermal resistance Rth eq of the FR4 single side board (thickness 1,6 mm)
- Figure 8 – Length that cause the heat dissipation and the thermal resistance of the type-K thermocouple (calculated)
- 4.4 Measuring method of the thermal resistance Rth shs-t from the terminal part to the surface hotspot
- Figure 9 – Example of calculation of the measurement error ∆T caused by the heat dissipation of the thermocouple
- Figure 10 – Recommended measurement system of Tshs and Tt for calculating Rth shs-t
- 4.5 Conclusions
- Annex A (informative) Background of the establishment of the derating curve based on ambient temperature [Go to Page]
- A.1 Tracing the history of the mounting and heat dissipation figuration of resistors
- Figure A.1 – Wired in the air using the lug terminal
- Figure A.2 – Heat path when wired in the air using the lug terminal
- A.2 How to establish the high temperature slope part of the derating curve [Go to Page]
- A.2.1 General
- Figure A.3 – Test condition for resistors with category power 0 W
- Figure A.4 – Test condition for resistors with category power other than 0 W [Go to Page]
- A.2.2 Derating curve for the semiconductors
- Figure A.5 – Example of reviewing the derating curve
- Figure A.6 – Tj, Tc and Rth j-c of transistors
- Figure A.7 – Derating curves for transistors [Go to Page]
- A.2.3 Derating curve for resistors
- Figure A.8 – Trajectory of Tj when P is reduced according to the derating curve
- Figure A.9 – Leaded resistors with small temperature rise
- Figure A.10 – Leaded resistors with large temperature rise
- Figure A.11 – Trajectory of Ths for the lead wire resistors with small temperature rise
- Figure A.12 – Trajectory of Ths for the lead wire resistors with large temperature rise
- Figure A.13 – Trajectory of Ths for resistors with category power other than 0 W
- Figure A.14 – Tsp and MAT for lead wire resistors with large temperature rise
- Figure A.15 – Tsp and MAT for lead wire resistors with small temperature rise
- Figure A.16 – Resistors for which the hotspot is the thermally sensitive point
- Figure A.17 – Resistor that have derating curve similar to the semiconductor
- Annex B (informative) The temperature rise of SMD resistors and the influence of the printed circuit board [Go to Page]
- B.1 Temperature rise of SMD resistors
- Figure B.1 – Temperature distribution of the SMD resistors mounted on the board
- Figure B.2 – Temperature rise of the SMD resistors from the ambient temperature
- Figure B.3 – Measurement system layout and board dimension
- Figure B.4 – Temperature rise of RR2012M (thickness 35 μm, 0,25 W applied)
- B.2 The influence of the printed circuit boards
- Figure B.5 – Temperature rise of RR2012M (thickness 70 μm, 0,25 W applied)
- Figure B.6 – Trajectory of the terminal part and hotspot temperature of the SMD resistors
- Figure B.7 – Operating temperature of the resistor on the board with narrow patterns
- Annex C (informative) The influence of the number of resistors mounted on the test board [Go to Page]
- C.1 General
- C.2 The influence of the number of resistors mounted on the test board
- Figure C.1 – Test board compliant with the IEC standard for RR1608M
- Figure C.2 – Relation between the number of samples and the surface hotspot temperature rise
- C.3 The delay of correspondence for current products with nonstandard dimensions
- Figure C.3 – Infrared thermograph image in the same scale whenpower is applied to 5 samples and 20 samples
- Annex D (informative) Influence of the air flow in the test chamber [Go to Page]
- D.1 General
- D.2 Influence of the wind speed
- Figure D.1 – Wind speed and the terminal part temperature rise of the RR6332M
- Figure D.2 – Test system for the natural convection flow
- Tables [Go to Page]
- Table D.1 – Number of samples mounted and the applied power
- Figure D.3 – Observing the influence of the agitation wind in the test chamber
- Figure D.4 – Wind speed and the terminal part temperature rise of the RR5025M
- Figure D.5 – Wind speed and the terminal part temperature rise of the RR3225M
- Figure D.6 – Wind speed and the terminal part temperature rise of the RR3216M
- Figure D.7 – Wind speed and the terminal part temperature rise of the RR2012M
- Figure D.8 – Wind speed and the terminal part temperature rise of the RR1608M
- Figure D.9 – Wind speed and the terminal part temperature rise of the RR1005M
- Annex E (informative) Validity of the new derating curve [Go to Page]
- E.1 Suggestion for establishing the derating curve based on the terminal part temperature
- Figure E.1 – Derating conditions of SMD resistors on the resistor manufacturer test board
- Figure E.2 – New derating curve provided by the resistor manufacturer to the electric/electronic designers
- Figure E.3 – Derating curve based on the terminal part temperature
- E.2 Conclusion
- Figure E.4 – Derating curve based on the terminal part temperature
- Annex F (informative) The thermal resistance of SMD resistors [Go to Page]
- Figure F.1 – Definition of the thermal resistance in a strict sense
- Figure F.2 – Thermal resistance of the resistor
- Annex G (informative) How to measure the surface hotspot temperature [Go to Page]
- 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 [Go to Page]
- G.3.1 General
- G.3.2 Spatial resolution and accuracy of peak temperature measurement
- Figure G.1 – Difference of the measured hotspot temperature caused by the spatial resolution [Go to Page]
- G.3.3 Influence of the angle of the measurement target normal line and the infrared thermograph light axis
- Figure G.2 – Measuring system for the error caused by the angle
- Figure G.3 – Error caused by the angle of the optical axisand the target surface (natural convection)
- Figure G.4 – Error caused by the angle of the optical axisand the target surface (0,3 m/s air ventilation from the side)
- Annex H (informative) How the resistor manufacturers measure the thermal resistance of resistors [Go to Page]
- H.1 The measuring system
- H.2 Definition of the two kinds of temperatures
- Figure H.1 – Measuring system for calculating the thermal resistance between the surface hotspot and the terminal part
- Figure H.2 – Simulation model
- Table H.1 – Results of the fillet part temperature simulation (calculated value)
- Table H.2 – Simulation result of the fillet part's temperature where it is measurable (calculated value)
- H.3 Errors in the measurement
- Table H.3 – Simulation result of the fillet part's temperature where it is measurable (calculated value)
- Figure H.3 – Temperature distribution of the copper block surface (calculated)
- Table H.4 – Thermal resistance simulation results between the surface hotspot and the terminal part based on the copper block temperature (calculated value)
- Figure H.4 – Isothermal line of the fillet part (calculated)
- Annex I (informative) Measurement method of the terminal part temperature of the SMD resistors [Go to Page]
- I.1 Measuring method using an infrared thermograph
- I.2 Measuring method using the thermocouple
- Figure I.1 – Temperature drop caused by the attached thermocouple
- I.3 Estimating the error range of the temperature measurement using the thermal resistance of the thermocouple [Go to Page]
- I.3.1 General
- Figure I.2 – Example of the printed board
- Figure I.3 – Printed board shown with the thermal network
- Figure I.4 – Equivalent circuit of the printed board shown with the thermal network
- Figure I.5 – Equivalent circuit when the thermocouple is connected
- Figure I.6 – Ambient temperature and the space need for the heat dissipation of the thermocouple
- Figure I.7 – Equivalent circuit when the thermocouple is connected
- Figure I.8 – Length that causes the heat dissipation and the thermal resistance of the type K thermocouple (calculated) [Go to Page]
- I.3.2 When using the type T thermocouples
- I.4 Thermal resistance of the board
- Figure I.9 – Length that cause the heat dissipation and the thermal resistance of the type T thermocouple (calculated)
- Figure I.10 – Thermal resistance Rth eq of the FR4 single side board (thickness 1,6 mm)
- Figure I.11 – Calculating the thermal resistance of the board from the fillet side
- I.5 Conclusion of this annex
- Annex J (informative) The variation of the heat dissipation fraction caused by the difference between the resistor and its mounting configuration [Go to Page]
- J.1 Heat dissipation ratio of cylindrical resistors wired in the air
- Figure J.1 – Simulation model of the lead wire resistors wired in the air
- J.2 Heat dissipation ratio of SMD resistors mounted on the board
- Figure J.2 – Heat dissipation ratio of the leaded cylindrical resistors (calculated)
- Figure J.3 – Measurement system of the heat dissipation ratio of SMD resistors mounted on the board
- J.3 Heat dissipation ratio of the cylindrical resistors mounted on the through-hole printed board
- Table J.1 – Analysis result of the heat dissipation ratio of SMD resistors (calculated value and value actually measured)
- Annex K (informative) Influence of airflow on SMD resistors [Go to Page]
- K.1 General
- K.2 Measurement system
- K.3 Test results (orthogonal)
- Figure K.1 – Measurement system
- Figure K.2 – Relationship between the terminal part temperature rise and the wind speed for the RR6332M (orthogonal)
- Figure K.3 – Relationship between the terminal part temperature rise and the wind speed for the RR5025M (orthogonal)
- Figure K.4 – Relationship between the terminal part temperature rise and the wind speed for the RR3225M (orthogonal)
- Figure K.5 – Relationship between the terminal part temperature rise and the wind speed for the RR3216M (orthogonal)
- Figure K.6 – Relationship between the terminal part temperature rise and the wind speed for the RR2012M (orthogonal)
- Figure K.7 – Relationship between the terminal part temperature rise and the wind speed for the RR1608M (orthogonal)
- K.4 Test results (parallel)
- Figure K.8 – Relationship between the terminal part temperature rise and the wind speed for the RR1005M (orthogonal)
- Figure K.9 – Relationship between the terminal part temperature rise and the wind speed for the RR6332M (parallel)
- Figure K.10 – Relationship between the terminal part temperature rise and the wind speed for the RR5025M (parallel)
- Figure K.11 – Relationship between the terminal part temperature rise and the wind speed for the RR3225M (parallel)
- Figure K.12 – Relationship between the terminal part temperature rise and the wind speed for the RR3216M (parallel)
- Figure K.13 – Relationship between the terminal part temperature rise and the wind speed for the RR2012M (parallel)
- Figure K.14 – Relationship between the terminal part temperature rise and the wind speed for the RR1608M (parallel)
- Figure K.15 – Relationship between the terminal part temperature rise and the wind speed for the RR1005M (parallel)
- Figure K.16 – Terminal part temperature rise of RR6332M, difference between the windward and leeward sides when placed parallel
- Annex L (informative) The influence of the spatial resolution of the thermograph [Go to Page]
- 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
- Figure L.1 – Step response of the Gaussian filter of the various cut-off spatial frequencies (calculated)
- Figure L.2 – Temperature distribution (cross-section) when measuring the object that becomes high temperature only in the range of 0,2 mm in diameter
- Figure L.3 – Measuring system of spatial frequency filter of the infrared thermograph
- Figure L.4 – Actual measured value of the step response of various magnifier lenses
- L.3 Example of the RR1608M SMD resistor hotspot's actual measurement
- Figure L.5 – Comparison of the actual measured value and the calculated value (step response)
- L.4 Conclusion
- Figure L.6 – Comparison of the actual measured value and the calculated value (surface hotspot of the resistor)
- Annex M (informative) Future subjects
- Bibliography [Go to Page]
