1、JEDEC STANDARD Implementation of the Electrical Test Method for the Measurement of Real Thermal Resistance and Impedance of Light-Emitting Diodes with Exposed Cooling JESD51-51 APRIL 2012 JEDEC SOLID STATE TECHNOLOGY ASSOCIATION NOTICE JEDEC standards and publications contain material that has been
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10、cuments for alternative contact information. JEDEC Standard No. 51-51 -i- IMPLEMENTATION OF THE ELECTRICAL TEST METHOD FOR THE MEASUREMENT OF REAL THERMAL RESISTANCE AND IMPEDANCE OF LIGHT-EMITTING DIODES WITH EXPOSED COOLING SURFACE CONTENTS Foreword.ii Introduction.ii 1 Scope1 2 Normative referenc
11、es.2 3 Terms and definitions, notations2 3.1 Symbols and terms.3 3.2 Definition of LEDs 4 4 Junction temperature, thermal resistance/impedance.6 5 Measurement procedures recommended for LEDs7 5.1 Measurement of LEDss thermal resistance and junction temperature 7 5.1.1 The electrical connections and
12、test waveforms7 5.1.2 Measuring LEDss thermal resistance / impedance using the electrical test method.9 5.1.3 Measurement delay and measurement current selection, data correction11 5.1.4 Length of the measurement window, heating time 12 5.1.5 Real heating power of LEDs13 5.1.6 Real thermal resistanc
13、e / thermal impedance of LEDs 14 5.1.7 Calculation of LEDss real steady-state junction temperature .16 5.2 Procedure for the measurement of Rth/ Zthof LEDs .17 5.2.1 The recommended test procedure 17 5.2.2 The test apparatus 18 5.3 Forward voltage stability and K-factor calibration of LEDs .18 6 Bib
14、liography 23 JEDEC Standard No. 51-51 -ii- IMPLEMENTATION OF THE ELECTRICAL TEST METHOD FOR THE MEASUREMENT OF REAL THERMAL RESISTANCE AND IMPEDANCE OF LIGHT-EMITTING DIODES WITH EXPOSED COOLING SURFACE Foreword This document has been prepared by the JEDEC JC-15 Committee on Thermal Characterization
15、. It specifies the details and provisions of physically meaningful thermal characterization of power LEDs. Introduction The purpose of this document is to specify, how LEDss thermal metrics and other thermally-related data are best identified by physical measurements using well established testing p
16、rocedures defined for thermal testing of packaged semiconductor devices (published and maintained by JEDEC) and defined for characterization of light sources (published and maintained by CIE the International Commission on Illumination). This document focuses on thermal characterization of LEDs as s
17、pecial, packaged discrete semiconductor devices. However, whenever needed, reference to light measurement is also made where terms, definitions and symbols specified and used in the relevant document of the International Commission on Illumination (CIE), (CIE 127:2007) will be used or referred to. F
18、igure 1 The mutual dependence of LEDss light output and different (macroscopic) quantities characteristic to the LEDs operating conditions LED specific aspects of thermal testing procedures are defined in a generic way which means, that whenever possible, no distinction is made between steady-state
19、and dynamic (transient) thermal measurements. Thus, this document belongs to the JESD51-50 through JESD51-53 series of standards. The overview of these standards is provided in the JESD51-50 document, (Overview of Methodologies for the Thermal Measurement of Single- and Multi-Chip, Single- and Multi
20、-PN-Junction Light-Emitting Diodes (LEDs). This document should also be used in conjunction with the JESD51 series of standards, especially with JESD51-1 (Integrated Circuit Thermal Measurement Method - Electrical Test Method) and JESD51-14 standard about junction-to-case thermal resistance measurem
21、ent (Transient Dual Interface Test Method for the Measurement of Thermal Resistance Junction-to-Case of Semiconductor Devices with Heat Flow through a Single Path). : Light output IF: Forward current VF: Forward voltage PH: Dissipated heating powerTJ: Junction temperature JEDEC Standard No. 51-51 -i
22、ii- Introduction (contd) 2a) 2b) Figure 2 Temperature and forward current dependence of the energy conversion efficiency (also known as radiant efficiency) of two different power LEDs The reason why these guidelines are provided specifically for LEDs is that the physics determining their thermal beh
23、avior is more complex than in case of conventional semiconductor devices which are not aimed at emitting any kind of electro-magnetic radiation like visible light. 1000 IFforward current mA100 200 400 500 700 80010 15 20 25 30 eradiant efficiency %Tref= 15oC Tref= 25oC Tref= 35oC Tref= 45oC Tref= 55
24、oC Tref= 65oC 300 600 900 (Popt/Pel emitted optical power / electrical 50 100 150 200 250 300 350 eradiant efficiency %18 20 22 24 28 26 IFforward current mATref = 15oC Tref = 25oC Tref = 35oC Tref = 45oC Tref = 55oC Tref = 65oC (Popt/Pel emitted optical power / electrical JEDEC Standard No. 51-51 -
25、iv- Introduction (contd) Thermal characterization of LEDs is a special case of thermal characterization of semiconductor diodes. The need for measurement guidelines for LEDs has arisen when light-emitting diodes with high power and high energy conversion efficiency emerged. This complexity in the ph
26、ysics as illustrated by Figure 1 becomes manifest in the following: The electric to light energy conversion efficiency is determined by the operating conditions of the LED: the junction temperature and the applied forward current. This efficiency is not a single number since it depends both on the L
27、EDs junction temperature and forward current as shown in Figure 2a and 2b. The power dissipated at the active region of a LED is thus determined by the difference of the supplied total electrical energy (VF IF) and the total energy emitted as optical radiation (e emitted total radiant flux, also den
28、oted as Popt): PH= VF IF e(1) This power together with the thermal resistance of the LED determines the junction temperature. In some cases it is recommended to add another loss term, Ploss, that describes extra losses such as light absorption in the lens (ideally it is negligible) and energy loss i
29、n the phosphor (in case of white LEDs). In practical cases these hardly can be measured separately, therefore are not accounted for. JEDEC Standard No. 51-51 Page 1 IMPLEMENTATION OF THE ELECTRICAL TEST METHOD FOR THE MEASUREMENT OF REAL THERMAL RESISTANCE AND IMPEDANCE OF LIGHT-EMITTING DIODES WITH
30、 EXPOSED COOLING SURFACE (From JEDEC Board Ballot JCB-12-08, formulated under the cognizance of the JC-15 Committee on Thermal Characterization.) 1 Scope This document specifies thermal testing procedures for power light-emitting diodes (power LEDs) and/or high brightness light-emitting diodes (HB L
31、EDs) in the following referred to as LEDs which are typically used in the operating regime of the forward current of 100mA and above, and emit visible light1). The application of these measurement guidelines is recommended for packaged LEDs, 1) with a total electrical power consumption above 0.5 W,
32、2) which have energy conversion efficiency above 5%, and 3) that are powered by steady DC power (typically with forced constant forward current), regardless whether the LED device inside the package is realized as single chip or multi chip device. Further details of the definition of term LED or LED
33、 device used in this document are given in section 0. This document does not deal with laser diodes. When speaking about thermal testing, one can distinguish between laboratory testing and bulk testing. The scope of this document is laboratory testing of power LEDs. Recommendations given in this doc
34、ument are valid for both steady-state and dynamic (transient) thermal measurements of LEDs, both relying on JEDEC JESD51-1 electrical test method. For steady-state thermal metrics both the static and dynamic test methods defined in JESD51-1 can be used. Regarding the heating power, this document is
35、aimed as an LED specific extension of the JEDEC JESD51-14, Transient Dual Interface Test Method for the Measurement of Thermal Resistance Junction-to-Case of Semiconductor Devices with Heat Flow through a Single Path document, applicable for DC driven LEDs only. Further LED specific additions to JES
36、D51-14 may also be published in the future which would deal with practical aspects of the differences between power LED packages and other power semiconductor device packages. 1)Strictly speaking, the term LED should only be applied to those diodes which emit visible light. Those, which emit infra-r
37、ed or UV radiation, should be referred to as IR LEDs or UV LEDs. JEDEC Standard No. 51-51 Page 2 2 Normative references The following normative documents contain provisions that, through reference in this text, constitute provisions of this guideline. For dated references, subsequent amendments to,
38、or revisions of, any of these publications do not apply. However, parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative do
39、cument referred to applies. JESD51, Methodology for the Thermal Measurement of Component Packages (Single Semiconductor Devices). JESD51-1, Integrated Circuit Thermal Measurement Method - Electrical Test Method. JESD51-12, Guidelines for Reporting and Using Electronic Package Thermal Information. JE
40、SD51-13, Glossary of Thermal Measurement Terms and Definitions. JESD51-14, Transient Dual Interface Test Method for the Measurement of Thermal Resistance Junction-to-Case of Semiconductor Devices with Heat Flow through a Single Path. JESD51-50, Overview of Methodologies for the Thermal Measurement o
41、f Single- and Multi-Chip, Single- and Multi-PN-Junction Light-Emitting Diodes (LEDs). JESD51-52, Guidelines for Combining CIE 127-2007 Total Flux Measurements with Thermal Measurements of LEDs with Exposed Cooling Surface. JESD51-53, Terms, Definitions and Units Glossary for LED Thermal Testing. CIE
42、 S 017/E:2011 ILV, International Lighting Vocabulary. CIE 127:2007 Technical Report, Measurement of LEDs, ISBN 978 3 901 906 58 9. MIL-STD-750D METHOD 3101.3, Thermal Impedance (Response) Testing of Diodes. ANSI/IESNA IES Nomenclature Committee, IES RP-16-10, Nomenclature and Definitions of for Illu
43、minating Engineering, ISBN 978-0-87995-208-2 ANSI/IESNA IES-LM-80, Approved Method for Measuring Lumen Maintenance of LED Light Sources, ISBN 978-0-87995-227-3. JEDEC Standard No. 51-51 Page 3 3 Terms and definitions, notations 3.1 Symbols and terms In this document the notations employed in the JES
44、D51, JESD51-1, JESD51-12, JESD51-13 and JESD51-14 are used. Generic terms and quantities related to light output measurement are used as defined in the International Lighting Vocabulary, CIE S 017/E:2011 ILV; LED specific terms of photometry and radiometry given in CIE 127:2007 are used. The most im
45、portant terms and notations referred to in this document are listed in Table 1. Comprehensive descriptions of terms, definitions and units used in conjunction with LEDs are provided in JESD51-53. For terms and definitions not listed there refer to JESD51-13, CIE S 017/E:2011 ILV and ANSI/IESNA RP-16
46、-10. Table 1 Symbols used in this document Symbol Unit of measure Name, description TJoC junction temperature (see JESD51-1) of the LED, denoted and referred to as TC, the chip temperature, in CIE 127:2007. (In the temperature range of interest, the usage of oC is more common.) TJoC or K change of j
47、unction temperature (see JESD51-1, JESD51-50). For temperature differences oC is commonly used. RJX, RthJXK/W junction-to-specific environment thermal resistance (see JESD51-1, JESD51-50) where x refers to the environment in question. JXK/W alternate symbol to RJX(see JESD51-1, JESD51-50). JXK/W jun
48、ction-to-X thermal characterization parameter, (see JESD51-13). VFV junction forward voltage IFA junction forward current PHW heat dissipated at the junction of the LED (see JESD51-50), also denoted as PHand referred to as heating power in (see JESD51-1, JESD51-14 and MIL-STD-750D METHOD 3101.3) . P
49、optW emitted optical power of the LED referred to as total radiant flux and denoted as ein CIE S 017/E:2011 ILV. It is also called radiant power. PelW electrical power supplied to the LED which is equal to the product of the forward voltage and the forward current: Pel= VF IF. This quantity is denoted as P in CIE 127:2007. eW emitted optical power of the LED, alternate notation to Poptas defined and referred to as total radiant flux or radiant power (see CIE S 017/E:2011 ILV). e, WPE % radiant efficien
