Heat Dissipation Design Standard Type Ver.3 CLU024,CLU034,CLU044,CLU054 Heat dissipation design is a precondition in order to maximize the performance of the LED. In this document, the data that is deemed necessary in the detailed heat dissipation structure of the products and the heat dissipation design of the lighting apparatus is provided as a reference for the appropriate thermal design. CONTENTS 1. Introduction P.2 2. Package structure and thermal resistance P.2 3. Thermal design outside the package P.3 4. Simulation P.4 Appendix CLU024-1201,CLU024-1202 P.5 CLU024-1203,CLU024-1204 P.6 CLU034-1205,CLU034-1206 P.7 CLU034-1208,CLU044-1212 P.8 CLU044-1812,CLU044-1818 P.9 CLU054-1825 P.10 CITIZEN ELECTRONICS CO., LTD. 1-23-1, Kamikurechi, Fujiyoshida-shi, Yamanashi, 403-0001, Japan Tel. +81-555-23-4121 http://ce.citizen.co.jp Copyright © 2014 CITIZEN ELECTRONICS CO., LTD. All Rights reserved. Ref.CE-P2752 07/14_R1(0714) Heat Dissipation Design Standard Type Ver.3 Heat dissipation structure that can conduct heat radiated from LEDs efficiently 1. Introduction Significance of the heat dissipation structure The light-emitting diode of an LED package radiates light and heat according to the input power. However, the surface area of an LED package is quite small, and the package itself is expected to release little heat into the atmosphere. An external radiator such as a heat sink is thus required. The heat dissipation structure up to the connection portion of the external radiator uses mainly heat conduction. Regarding LED packages, to control the junction temperature of the light-emitting diode Tj is important. The Tj must be kept from exceeding the absolute maximum rating in the specifications under any conditions. As direct measurement of the junction temperature of a light-emitting diode inside a package is difficult, the temperature of a particular part on the external 2. package ( the case temperature ) Tc [°C] is normally measured. Tj [°C] is calculated using the thermal resistance between the junction and the case Rj-c [°C/W], and the emitted heat amount that is nearly equal to the input power Pi [W]. The heat generated at the light-emitting diode can be conducted to the external radiator efficiently because the package structure for the COB LED package minimizes the thermal resistance Rj-c. This document describes the detailed heat dissipation structure of the COB LED package and provides data necessary for thermal design of the lighting apparatus to maximize LED performance. Package structure and thermal resistance Understanding the junction temperature The cross-sectional structure example, where the package of the COB LED package is connected to an external heat sink, is shown in Figure-1 ( a ). The package has a laminated structure of an aluminum substrate, insulating layers and conductive copper foil patterns. A distinctive point is that the light-emitting diode is mounted directly on the well conductive aluminum substrate not on the insulating layer, which has low thermal conductivity. Thus, the heat generated at the light-emitting diode can be efficiently conducted to the outside of the package. The aluminum substrate side of the package outer shell is thermally connected to the heat sink via the TIM(Thermal interface material). As described above, the heat generated in the junction section of the light-emitting diode is transferred mainly to the heat sink using heat conduction, through the light-emitting diode to the adhesive for die-mounting to the aluminum substrate to the TIM. The thermal resistance between the junction section of the light-emitting diode and ■Figure-1 ( a ) COB LED package Cross-section diagram LED die TJ Aluminum TIM Heatsink the aluminum substrate side of the package outer shell is Rj-c, and the specific thermal resistance value of the package. Therefore, the following formula is used Tj = Rj-c・Pi + Tc In addition, the thermal resistance of the TIM outside the package is R-TIM[°C/W], the thermal resistance with the heat sink is Rh [°C/W], and the ambient temperature is Ta [°C]. Figure-1 ( b ) indicates the equivalent thermal resistance along the cross-sectional diagram in Figure-1 ( a ). ■Figure-1 ( b ) Thermal Resistance As indicated, the thermal resistances Connection Rj-c, Rb, and Rh are connected in series between the junction temperature Tj and Tj Tj the ambient temperature Ta. The thermal resistances outside the package Rj-c Rj-c R-TIM and Rh can be integrated into Tc Tc the thermal resistance Rc-a at this point. R-TIM Rc-a Thus, the following formula is also Rh used: Tc Rj-c R-TIM Ta Tj = ( Rj-c + Rc-a )・Pi + Ta Rh Ta Ta 2 Copyright © 2014 CITIZEN ELECTRONICS CO., LTD. All Rights reserved. CITIZEN ELECTRONICS CO., LTD. 1-23-1, Kamikurechi, Fujiyoshida-shi, Yamanashi, 403-0001, Japan Tel. +81-555-23-4121 http://ce.citizen.co.jp Ref.CE-P2752 07/14_R1(0714) Heat Dissipation Design Standard Type Ver.3 Use the correlation between the thermal resistance and the ambient temperature for design of the external heat dissipation mechanism 3. Thermal design of the outside the package Point of the external heat dissipation mechanism COB LED package.( As an example, the data of CLU0341205B8 is showing below.) The higher the ambient temperature Ta and the larger the driving current, the smaller the allowable thermal resistance outside the package Rc-a = R-TIM + Rh. In brief, the TIM and the heat sink, with smaller thermal resistance ( this means better heat dissipation ) , are required in order to keep Tj from exceeding, the absolute maximum rating in the specifications, if the ambient temperature becomes higher and/or the driving current is larger. Therefore, use Figure-2 as a guide when selecting the external heat dissipation parts, and ultimately conduct thermal verification on actual devices. The equivalent charts for each package is showing in the last part of this document. The thermal resistance outside the package Rc-a [°C/W], which is the combination of the heat-dissipation the TIM and the heat sink, is limited by the input power Pd [W], the ambient temperature Ta [°C], and the thermal resistance of the package Rj-c [°C/W], i.e., Tj = ( Rj-c + Rc-a )・Pi + Ta Rc-a = ( Tj - Ta ) / Pi - Rj-c Ta function converted from the above formula is Rc-a = -Ta / Pi + Tj / Pi - Rj-c and it is a straight line with the slope of -1 / Pi and the intercept of Tj / Pi - Rj-c. Figure-2 is the chart showing the relationship between the ambient temperature Ta and the thermal resistance outside the package Rc-a indicated by driving current, where Tj is assumed to be the absolute maximum rating value in the specifications for the ■Figure-2 Ta - Rc-a（ CLU034-1205 B8 ） (°C/W) 15 Rj-c=1.1(°C/W) 900mA 600mA 450mA 300mA Rc-a 10 5 0 0 20 40 60 Ta 3 80 (°C) Copyright © 2014 CITIZEN ELECTRONICS CO., LTD. All Rights reserved. CITIZEN ELECTRONICS CO., LTD. 1-23-1, Kamikurechi, Fujiyoshida-shi, Yamanashi, 403-0001, Japan Tel. +81-555-23-4121 http://ce.citizen.co.jp Ref.CE-P2752 07/14_R1(0714) Heat Dissipation Design Standard Type Ver.3 4. Simulation Structure figure of analytical model For efficient thermal design Tc point(Cathode) A simulation is an effective procedure with regard to the COB LED package thermal design. Simulation results from when COB LED Thermal conductive sheet package was connected to the heat sink with a heat conductive sheet are shown in Fig.3 ( a ), ( b ).( As an example, the data of CLU034-1205B8 is showing below.) The results of the simulation for each package is showing in the last part of this document. Boundary conditions L W ( Variable ) Environmental conditions : Ta = 25°C Analysis space : 400mm×400mm×(350+L)mm Wall condition : Top=Open, Others=25°C H Heat dispersion conditions : Natural convection Model conditions Thermal conductivirity of Thermal conductive sheet : 4.5W/m.K Thickness of the heat conductive sheet : t=0.12mm Material of the heat sink : Aluminum ( Number of the fin : 6 ) Outline dimensions of the heat sink : W 64mm x H 40mm *Note : sectional area 1108mm2, Dimension“L” is variable ■Figure-3 ( a ) Junction temperature Tj 110 Input Power : 16.1W 100 90 80 70 60 50 40 Input power - junction temperature Tj (CLU034-1205B8) (°C) 120 120 Junction Temperature Tj (°C) ■Figure-3 ( b ) Heat sink surface area - junction temperature Tj (CLU034-1205B8) 0 50,000 100,000 150,000 200,000 250,000 Surface area of the heatsink 100 80 60 40 0 300,000 S = 200,000mm2 20 0 5 10 15 20 Input power (mm2) 25 30 35 (W) * Above data represents simulation values and is not guaranteed to represent actual measurement values. Evaluation and verification shall be conducted under the conditions of actual use. 4 Copyright © 2014 CITIZEN ELECTRONICS CO., LTD. All Rights reserved. CITIZEN ELECTRONICS CO., LTD. 1-23-1, Kamikurechi, Fujiyoshida-shi, Yamanashi, 403-0001, Japan Tel. +81-555-23-4121 http://ce.citizen.co.jp Ref.CE-P2752 07/14_R1(0714) Heat Dissipation Design Standard Type Ver.3 Appendix CLU024-1201B8 ■Figure2-1 Ta - Rc-a（CLU024-1201B8） (°C/W) Rj-c=4.2(°C/W) 80 Rc-a 60 180mA 90mA 120mA 60mA 40 20 0 ■Figure3（a）-1 Heat sink surface area - junction temperature Tj （CLU024-1201B8） (°C) 40 60 Ta 80 (°C) (°C) 80 58 70 Junction Temperature Tj Input Power : 3.2W 56 Junction temperature Tj 20 ■Figure3（b）-1 Input power - junction temperature Tj （CLU024-1201B8） 60 54 52 50 48 46 44 60 50 40 30 S = 200,000mm2 20 10 42 40 0 0 50,000 100,000 150,000 200,000 250,000 Surface area of the heatsink 0 300,000 0 1 2 3 4 5 6 CLU024-1202B8 7 (W) Input power (mm ) 2 ■Figure2-2 Ta - Rc-a（CLU024-1202B8） (°C/W) Rj-c=2.4(°C/W) 60 360mA 180mA 240mA 90mA Rc-a 40 20 0 0 20 40 60 80 Ta ■Figure3（b）-2 Input power - junction temperature Tj （CLU024-1202B8） ■Figure3（a）-2 Heat sink surface area - junction temperature Tj （CLU024-1202B8） (°C) 90 80 80 Junction temperature Tj 75 Input Power : 6.4W 70 Junction Temperature Tj (°C) 65 60 55 50 45 40 (°C) 70 60 50 40 30 S = 200,000mm2 20 10 0 50,000 100,000 150,000 200,000 250,000 Surface area of the heatsink 0 300,000 0 2 4 6 8 Input power (mm2) 5 10 12 14 (W) Copyright © 2014 CITIZEN ELECTRONICS CO., LTD. All Rights reserved. CITIZEN ELECTRONICS CO., LTD. 1-23-1, Kamikurechi, Fujiyoshida-shi, Yamanashi, 403-0001, Japan Tel. +81-555-23-4121 http://ce.citizen.co.jp Ref.CE-P2752 07/14_R1(0714) Heat Dissipation Design Standard Type Ver.3 CLU024-1203B8 ■Figure2-3 Ta - Rc-a（CLU024-1203B8） (°C/W) Rj-c=1.7(°C/W) 30 540mA 270mA 360mA 150mA Rc-a 20 10 0 ■Figure3（a）-3 Heat sink surface area - junction temperature Tj （CLU024-1203B8） (°C) 40 60 Ta 80 (°C) (°C) 100 90 85 Junction Temperature Tj Input Power : 9.6W 80 Junction temperature Tj 20 ■Figure3（b）-3 Input power - junction temperature Tj （CLU024-1203B8） 90 75 70 65 60 55 50 80 70 60 50 40 30 S = 200,000mm2 20 10 45 40 0 0 50,000 100,000 150,000 200,000 250,000 Surface area of the heatsink 0 300,000 0 5 10 15 20 (W) Input power (mm ) 2 CLU024-1204B8 ■Figure2-4 Ta - Rc-a（CLU024-1204B8） (°C/W) Rj-c=1.4(°C/W) 30 720mA 360mA 480mA 200mA Rc-a 20 10 0 Input Power : 12.9W Junction Temperature Tj Junction temperature Tj 40 60 Ta 80 (°C) (°C) 120 110 100 90 80 70 60 50 40 20 ■Figure3（b）-4 Input power - junction temperature Tj （CLU024-1204B8） ■Figure3（a）-4 Heat sink surface area - junction temperature Tj （CLU024-1204B8） (°C) 0 0 50,000 100,000 150,000 200,000 250,000 Surface area of the heatsink 100 80 60 40 0 300,000 S = 200,000mm2 20 0 5 10 15 Input power (mm2) 6 20 25 30 (W) Copyright © 2014 CITIZEN ELECTRONICS CO., LTD. All Rights reserved. CITIZEN ELECTRONICS CO., LTD. 1-23-1, Kamikurechi, Fujiyoshida-shi, Yamanashi, 403-0001, Japan Tel. +81-555-23-4121 http://ce.citizen.co.jp Ref.CE-P2752 07/14_R1(0714) Heat Dissipation Design Standard Type Ver.3 CLU034-1205B8 ■Figure2-5 Ta - Rc-a（CLU034-1205B8） (°C/W) Rj-c=1.1(°C/W) 15 900mA 450mA 600mA 300mA Rc-a 10 5 0 0 20 40 60 80 Ta ■Figure3（a）-5 Heat sink surface area - junction temperature Tj （CLU034-1205B8） (°C) 120 120 110 Junction temperature Tj ■Figure3（b）-5 Input power - junction temperature Tj （CLU034-1205B8） Input Power : 16.1W 100 Junction Temperature Tj (°C) 90 80 70 60 50 40 (°C) 0 50,000 100,000 150,000 200,000 250,000 Surface area of the heatsink 100 80 60 40 0 300,000 S = 200,000mm2 20 0 5 10 15 20 25 30 35 (W) Input power (mm ) 2 CLU034-1206B8 ■Figure2-6 Ta - Rc-a（CLU034-1206B8） (°C/W) Rj-c=0.98(°C/W) 12 10 1080mA 540mA 720mA 360mA Rc-a 8 6 4 2 0 120 60 80 (°C) 120 Input Power : 19.3W 110 Junction Temperature Tj Junction temperature Tj 40 Ta (°C) 140 130 100 90 80 70 60 50 40 20 ■Figure3（b）-6 Input power - junction temperature Tj （CLU034-1206B8） ■Figure3（a）-6 Heat sink surface area - junction temperature Tj （CLU034-1206B8） (°C) 0 0 50,000 100,000 150,000 200,000 250,000 Surface area of the heatsink 100 80 60 40 0 300,000 S = 200,000mm2 20 0 5 10 15 20 25 Input power (mm2) 7 30 35 40 45 (W) Copyright © 2014 CITIZEN ELECTRONICS CO., LTD. All Rights reserved. CITIZEN ELECTRONICS CO., LTD. 1-23-1, Kamikurechi, Fujiyoshida-shi, Yamanashi, 403-0001, Japan Tel. +81-555-23-4121 http://ce.citizen.co.jp Ref.CE-P2752 07/14_R1(0714) Heat Dissipation Design Standard Type Ver.3 CLU034-1208B8 ■Figure2-7 Ta - Rc-a（CLU034-1208B8） (°C/W) Rj-c=0.78(°C/W) 10 8 1440mA 720mA 960mA 480mA Rc-a 6 4 2 0 0 20 40 60 80 Ta ■Figure3（a）-7 Heat sink surface area - junction temperature Tj （CLU034-1208B8） (°C) 160 160 140 Junction temperature Tj ■Figure3（b）-7 Input power - junction temperature Tj （CLU034-1208B8） 140 Input Power : 25.7W Junction Temperature Tj (°C) 120 100 80 60 40 (°C) 120 100 80 60 40 S = 200,000mm2 20 0 50,000 100,000 150,000 200,000 250,000 Surface area of the heatsink 0 300,000 0 10 20 30 40 50 60 (W) Input power (mm ) 2 CLU044-1212B8 ■Figure2-8 Ta - Rc-a（CLU044-1212B8） (°C/W) Rj-c=0.52(°C/W) 6 2160mA 1080mA 1440mA 720mA Rc-a 4 2 0 0 20 40 60 80 Ta ■Figure3（b）-8 Input power - junction temperature Tj （CLU044-1212B8） ■Figure3（a）-8 Heat sink surface area - junction temperature Tj （CLU044-1212B8） (°C) 160 160 Junction temperature Tj 140 140 Input Power : 38.6W Junction Temperature Tj (°C) 120 100 80 60 40 (°C) 120 100 80 60 40 S = 200,000mm2 20 0 50,000 100,000 150,000 200,000 250,000 Surface area of the heatsink 0 300,000 0 10 20 30 40 Input power (mm2) 8 50 60 70 (W) Copyright © 2014 CITIZEN ELECTRONICS CO., LTD. All Rights reserved. CITIZEN ELECTRONICS CO., LTD. 1-23-1, Kamikurechi, Fujiyoshida-shi, Yamanashi, 403-0001, Japan Tel. +81-555-23-4121 http://ce.citizen.co.jp Ref.CE-P2752 07/14_R1(0714) Heat Dissipation Design Standard Type Ver.3 CLU044-1812B8 ■Figure2-9 Ta - Rc-a（CLU044-1812B8） (°C/W) Rj-c=0.39(°C/W) 4 Rc-a 3 2160mA 1080mA 1440mA 720mA 2 1 0 0 20 40 60 80 Ta ■Figure3（a）-9 Heat sink surface area - junction temperature Tj （CLU044-1812B8） (°C) 160 160 140 Junction temperature Tj ■Figure3（b）-9 Input power - junction temperature Tj （CLU044-1812B8） 140 Input Power : 53.6W Junction Temperature Tj (°C) 120 100 80 60 40 (°C) 120 100 80 60 40 S = 200,000mm2 20 0 100,000 200,000 300,000 400,000 500,000 Surface area of the heatsink 0 600,000 0 10 20 30 40 50 60 70 CLU044-1818B8 80 (W) Input power (mm ) 2 ■Figure2-10 Ta - Rc-a（CLU044-1818B8） (°C/W) Rj-c=0.26(°C/W) 4 Rc-a 3 2160mA 1080mA 1620mA 720mA 2 1 0 0 20 40 60 80 Ta ■Figure3（b）-10 Input power - junction temperature Tj （CLU044-1818B8） ■Figure3（a）-10 Heat sink surface area - junction temperature Tj （CLU044-1818B8） (°C) 160 180 Junction temperature Tj 160 140 Input Power : 86.8W Junction Temperature Tj (°C) 140 120 100 80 60 40 (°C) 120 100 80 60 40 S = 400,000mm2 20 0 250,000 500,000 750,000 1,000,000 Surface area of the heatsink 0 1,250,000 0 20 40 Input power (mm2) 9 60 80 100 (W) Copyright © 2014 CITIZEN ELECTRONICS CO., LTD. All Rights reserved. CITIZEN ELECTRONICS CO., LTD. 1-23-1, Kamikurechi, Fujiyoshida-shi, Yamanashi, 403-0001, Japan Tel. +81-555-23-4121 http://ce.citizen.co.jp Ref.CE-P2752 07/14_R1(0714) Heat Dissipation Design Standard Type Ver.3 CLU054-1825B8 ■Figure2-11 Ta - Rc-a（CLU054-1825B8） (°C/W) Rj-c=0.25(°C/W) 3 3000mA 1500mA 2250mA 1000mA Rc-a 2 1 0 0 20 40 60 80 Ta ■Figure3（a）-11 Heat sink surface area - junction temperature Tj （CLU054-1825B8） (°C) 160 180 160 Junction temperature Tj ■Figure3（b）-11 Input power - junction temperature Tj （CLU054-1825B8） 140 Input Power : 120.1W Junction Temperature Tj (°C) 140 120 100 80 60 40 (°C) 120 100 80 60 40 S = 940,000mm2 20 0 500,000 1,000,000 1,500,000 2,000,000 Surface area of the heatsink 0 2,500,000 0 20 40 60 80 Input power (mm ) 2 10 100 120 140 (W) Copyright © 2014 CITIZEN ELECTRONICS CO., LTD. All Rights reserved. CITIZEN ELECTRONICS CO., LTD. 1-23-1, Kamikurechi, Fujiyoshida-shi, Yamanashi, 403-0001, Japan Tel. +81-555-23-4121 http://ce.citizen.co.jp Ref.CE-P2752 07/14_R1(0714) ● CITIZEN ELECTRONICS CO., LTD. shall not be liable for any disadvantages or damages resulting from the use of technical information or data included in this document or the impossibility of download and use, responsibility for the cause of lawsuit or any other damages or losses. ● This technical information or data shall be provided ‘as is’ to users and CITIZEN ELECTRONICS CO., LTD. does not guarantee the absence of error or other defects in this technical information or data, conformance of this technical information or data to specific purpose, this technical information or data or its use will not infringe the rights of users or third parties or any other content. ● CITIZEN ELECTRONICS CO., LTD. reserves the right to make changes to technical information or data without notification. 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