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Thermal characteristics for chip on metal package of LED lighting module
Materials Science in Semiconductor Processing ] (]]]]) ]]]–]]]
Contents lists available at ScienceDirect
Materials Science in Semiconductor Processing journal homepage: www.elsevier.com/locate/mssp
Thermal characteristics for chip on metal package of LED lighting module Seung-Ryol Maeng, Seok-Cheol Ko n Industry–University Cooperation Foundation, Kongju National University, Chungnam 314-701, Republic of Korea
a r t i c l e i n f o
Keywords: Chip on board Chip on metal Thermal resistance LED package
abstract The insulator of the metal printed circuit board (PCB) area layer, where a chip is packaged in the metal PCB structure of the chip on board (COB) package, is removed in order to propose a chip on metal (COM) package that allows the direct packaging of the chip to the PCB metal layer. In order to analyze the thermal characteristics from the chip, both COB and COM packages were fabricated during the operation to measure the chip junction temperatures (Tj) and thermal resistances of both specimens. According to the Tj measurement result, Tj ¼34.64 1C for the COM package with the removed insulator and Tj ¼45.28 1C for the COB package, showing that the COM package had an approximately 10 1C less thermal distribution. Similarly, the thermal resistance of the COM package was 0.7 1C/W, which was about 1 1C/W less than the COB package thermal resistance of 1.67 1C/W. Also, by comparatively analyzing the changes in the spectrum, color coordinates, and speed of light according to the driving time, it was found that luminous color stabilization may have contributed to the luminescence properties of the COM package, which has lower thermal resistance, and the degradation of the chip and packaging material can be minimized. & 2014 Elsevier Ltd. All rights reserved.
1. Introduction The commercialization of light emitting diodes (LED) with their application to general lighting has led to an increase in demand for high power LED packages. The basic conditions that need to be met by LED packages include excellent light extraction efficiency [1] and a heat dissipation structure for the package, which releases the heat created from the chip die during operation to outside the package [2,3]. As the light extraction efficiency and heat dissipation structure are not independent of each other, photons and heat are produced from the chip active area when power is supplied to the LED package. Except for some photons that are extracted outside
n Corresponding author. Postal address: Industry-University Cooperation Foundation, Kongju National University, 56 Gongjudaehak-Ro, Gongju-Si, Chungnam, 314-701, Republic of Korea. Tel.: þ 82 41 850 0528; fax: þ82 41 850 0544. E-mail address: [email protected] (S.-C. Ko).
the package, most photons are dissipated as heat. Thus, effectively expelled heat produced from the chip enhances the extraction efficiency and reliability of the LED package. Conventional LED lighting modules can be categorized into a structure where the LED package is attached to the printed circuit board (PCB) using the surface mount technology (SMT) process and a chip on board (COB) structure where the LED device is attached directly to the PCB board [4–6]. The LED light source module applied to the SMT process has numerous thermal nodes that are structurally complex. Therefore, an increase in the thermal resistance of each thermal node is inevitable in order to release the heat produced by the chip to the surrounding air. Although the COB structure has less thermal nodes in comparison to the LED light source module with the SMT process applied, the thermal resistance of the insulating layer was installed in the PCB structure where the LED die is located. This resistance increase hinders the release of heat caused by the LED die. Previous studies reported up to now the LED junction temperature, which is directly related to
http://dx.doi.org/10.1016/j.mssp.2014.11.025 1369-8001/& 2014 Elsevier Ltd. All rights reserved.
Please cite this article as: S.-R. Maeng, S.-C. Ko, Materials Science in Semiconductor Processing (2014), http://dx.doi.org/ 10.1016/j.mssp.2014.11.025i
S.-R. Maeng, S.-C. Ko / Materials Science in Semiconductor Processing ] (]]]]) ]]]–]]]
2
the optical characteristics of the LED package [7–10]. However, studies on heat dissipation structures, where the insulating layer between the LED device and the base metal of the board is partially removed, as well as an analysis of the thermal characteristics of this kind of structure have yet to be published. In this paper, after removing the insulator of the PCB area layer where the chip was packaged to minimize the thermal nodes, and directly packaging the chip to the PCB metal layer, a chip on metal (COM) package heat dissipation structure is proposed in order to effectively dissipate the heat produced by the chip during operation. Both COB and COM package types were fabricated to analyze the thermal characteristics of the proposed COM package. The chip junction temperature and thermal resistance for each specimen were measured. Furthermore, the change in spectrum, color coordinates, and speed of light were comparatively analyzed according to the driving time.
2. Experimental method The fabrication: The COB package has a structure where the chip is packaged to the metal PCB. The COB package also has five thermal nodes in order to simplify the complicated manufacturing process, reduce costs, and simplify the complex heat dissipation structure of SMT type LED modules. However, the metal PCB structure of COB includes a dielectric layer between the Cu layer where the chip is packaged and an aluminum plate, as shown in Fig. 1. This causes a thermal resistance increase due to the low thermal conductivity of the insulating layer. Thus, the structure hinders the dissipation of heat from the chip. The proposed COM package, as shown in Fig. 2, has the dielectric layer of the COB package metal PCB removed to directly install the chip to the aluminum metal base surface. This is so the heat produced from the chip can be directly absorbed by the aluminum metal base. The package
configuration is a low thermal resistance LED package structure with the simplest configuration of three thermal nodes. The test specimens used in this research were the COB and COM packages that were fabricated in the same conditions. The chips for the COB and COM packages were of InGaN/Sapphire type 1.1 mm 1.1 mm and 1 W and 16 chips were arranged in a multi array structure with 4 in parallel position and 4 in serial position. For the metal PCB, 2 types of COB PCB and COM PCB were fabricated as shown in Fig. 3. The chip was directly installed on the Cu layer for the COB and on the aluminum plate for the COM. The adhesive used between the PCB and the chip was Ag epoxy, which has a thermal conductivity of 20 W/mK. Table 1 organizes the properties of the material used in the manufacture of the LED. Fig. 4 shows the COM package assembly process.
3. Results and discussion For the fabricated COB and COM packages, the chip junction temperature and thermal resistance of the 2 LED package types were measured. The parameters during the measurement were as shown in Table 2 where the input current was 1 A. For the COM package, the forward voltage was 12.13 V, the input power dissipation was 12.13 W, and the COM package chip junction temperature was 34.65 1C when the ambient temperature was 26.25 1C. A temperature difference of 8.4 1C between the ambient temperature and chip junction temperature was observed. For the COB
Fig. 3. Comparison of COB PCB and COM PCB structure.
Fig. 1. COB type thermal node.
Fig. 2. COM type thermal node.
Please cite this article as: S.-R. Maeng, S.-C. Ko, Materials Science in Semiconductor Processing (2014), http://dx.doi.org/ 10.1016/j.mssp.2014.11.025i
S.-R. Maeng, S.-C. Ko / Materials Science in Semiconductor Processing ] (]]]]) ]]]–]]]
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Table 1 LED material properties. Material
Encapsulant Chip Die adhesion Cu layer Dielectric layer Al plate
COB package
COM package
Thickness (mm)
Size (mm)
Thermal conductivity (W/mK)
Thickness (mm)
Size (mm)
Thermal conductivity (W/mK)
700 150 5–10 30 100 800
15 15 1.1 1.1 1.5 1.5 24 24 24 24 24 24
0.2 30 20 400 1.5 200
800 150 5–10 – – 700
15 15 1.1 1.1 1.5 1.5 – – 24 24
0.2 30 20 – – 200
Fig. 4. Assembly process: (a) adhesion bond on metal PCB (silver epoxy), (b) chip mount and wire bonding, (c) damping for en-capsulation material (silicone), (d) en-capsulation (mixed phosphor silicone), and (e) operating.
Table 2 Thermal resistance measurement parameters and the result. Parameter
COM package
COB package
K-factor (mk/W) Junction temperature (1C) Thermal resistance (1C/W) Input current (A) Ambient temperature (1C) Forward voltage VF (V) Power dissipation (W)
6.047 34.65 0.699 1.0 26.25 12.13 12.13
5.785 45.28 1.665 1.0 25.83 11.79 11.79
Fig. 5. Thermal resistance of COB and COM packages.
package, the forward voltage was 11.79 V, the input power dissipation was 11.79 W, and the COB package chip junction temperature (Tj) was 45.28 1C when the ambient temperature was 25.83 1C. A temperature difference of 17.7 1C was observed between the ambient temperature and the chip junction temperature. With regard to the chip junction
temperature of the 2 package types, it was observed that the COM package Tj ¼34.64 1CoCOB package Tj ¼45.28 1C. Thus, the COM package chip junction temperature was approximately 10 1C lower. Fig. 5 shows the thermal resistance (T3ster, Mentor Graphics Corp., USA) variation plot of the 2 package types. In order to compare the thermal distribution of the 2 LED package types, the COM and COB packages were set inside a 150 150 mm2 aluminum heat-sink, as shown in Fig. 6(a), and a uniform 1 A current input. The illuminated state of the LED was then captured through a thermal imaging camera to examine the temperature distribution of each package. The light emitting area maximum temperature (spot 1) of the COB package, shown on the left of Fig. 6(b), was 120 1C, while the COM package central area maximum temperature shown on the right was 97.6 1C. This shows that the COM package was about 22 1C less distributed in comparison to the COB package. To compare the optical characteristics of the COM and COB package type specimens, an input current of 1 A was applied and the variation in spectrum and color coordinates according to the driving time was compared. As shown in Fig. 7, although the spectrums at the initial stages of the input current application are similar, it was found that the spectrum change with the duration of driving time was greater for the COB package. A spectrum change implies a change in the illuminated color during the LED operation. Fig. 8 shows the change in the illuminated color according to the 2 LED package types operation time in the CIE color space. It was observed that the COB package with the insulating layer had a greater color coordinate change and the LED illuminated color is related to the temperature change. Fig. 9 shows the speed of light degradation rate according to the driving time change, assuming that the initially measured speed of light is 100% for both the COM
Please cite this article as: S.-R. Maeng, S.-C. Ko, Materials Science in Semiconductor Processing (2014), http://dx.doi.org/ 10.1016/j.mssp.2014.11.025i
S.-R. Maeng, S.-C. Ko / Materials Science in Semiconductor Processing ] (]]]]) ]]]–]]]
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Fig. 6. The LED package temperature distribution of the application of the input current: (a) LED set and (b) thermal distribution during LED operation (thermal imaging camera).
Fig. 7. Spectrum variation according to the driving time: (a) COM package spectrum and (b) COB package spectrum.
Fig. 8. LED color shift according to the driving time. Fig. 9. Speed of light variation according to the driving time.
and COB packages. The input currents for both package types were 1 A and the speed of light variation was compared until the total driving time reached 100 min. As a result, the COM package speed of light degradation rate was saturated and stabilized at 95% after 60 min while the COB package speed of light degradation rate was at 84% after 100 min and the degradation continued. 4. Conclusions The COB package metal PCB layer configuration includes an insulating layer on the aluminum plate and the Cu layer on the insulating layer is plated with Ag where the chip is
packaged. The insulating layer of the COB metal PCB layer has a low thermal conductivity of 1.5 W/mK, which acts as a thermal barrier that hinders the dissipation of heat produced by the chip due to the increased thermal resistance. In this study, the insulating layer where the chip is installed in the COB package metal PCB structure was removed. A COM package where the chip can be directly attached to the metal PCB aluminum base was proposed. The chip Tj measurements of the 2 package types showed that the COM package with the removed insulating layer had Tj ¼34.64 1C and the COB package had Tj ¼45.28 1C. Thus, the COM package was about 10 1C lower in distribution. Similarly, for the thermal
Please cite this article as: S.-R. Maeng, S.-C. Ko, Materials Science in Semiconductor Processing (2014), http://dx.doi.org/ 10.1016/j.mssp.2014.11.025i
S.-R. Maeng, S.-C. Ko / Materials Science in Semiconductor Processing ] (]]]]) ]]]–]]]
resistance, the COM package thermal resistance was 0.7 1C/W, which was about 1 1C/W lower than the 1.67 1C/W thermal resistance of the COB package. Furthermore, the COM package with a low thermal resistance had a heat dissipation structure, which allowed for the stabilization of the illuminating color and minimization of the chip and packaging material degradation. Such characteristics reveal that the COM package can be applied as an LED illumination light source with a long lifespan.
5
[3] S.J. Lee, Opt. Eng. 45 (2006). (014601-1-014601-6). [4] Y.-B. Yoon, J.-W. Park, IEEE Trans. Compon. Packag. Technol. 32 (2009) 825–831. [5] R. Huber, “Thermal Management of Golden DRAGON LED” Application Note. OSRAM Opto Semiconductors, , 2008, 1–11. [6] M. Ha, S. Graham, Microelectron. Reliab. 52 (2012) 836–844. [7] J. Park, M. Shin, C.C. Lee, Opt. Lett. 29 (2004) 2656–2658. [8] S.L. Chuang, J. IEEE, Quantum Electron. 33 (1997) 970–979. [9] Z. Chuluunbaatar, C. Wang, E.S. Kim, N.Y. Kim, Int. J. Therm. Sci. 86 (2014) 307–313. [10] E. Juntunen, Olli Tapaninen, Aila Sitomaniemi, V. Heikkinen, IEEE Trans. Compon. Package. Manuf. Technol. 3 (2013) 1148–1154.
References [1] Hong Eugene and Nadarajah, Proc. Soc. Photo-Opt. Instrum. Eng. 5187 (2004) 93–99. [2] Hu. Jianzheng, Yang Lianqiao, Shin Moo Whan, Microelectron. J. 38 (2007) 148–154.
Please cite this article as: S.-R. Maeng, S.-C. Ko, Materials Science in Semiconductor Processing (2014), http://dx.doi.org/ 10.1016/j.mssp.2014.11.025i
Contents lists available at ScienceDirect
Materials Science in Semiconductor Processing journal homepage: www.elsevier.com/locate/mssp
Thermal characteristics for chip on metal package of LED lighting module Seung-Ryol Maeng, Seok-Cheol Ko n Industry–University Cooperation Foundation, Kongju National University, Chungnam 314-701, Republic of Korea
a r t i c l e i n f o
Keywords: Chip on board Chip on metal Thermal resistance LED package
abstract The insulator of the metal printed circuit board (PCB) area layer, where a chip is packaged in the metal PCB structure of the chip on board (COB) package, is removed in order to propose a chip on metal (COM) package that allows the direct packaging of the chip to the PCB metal layer. In order to analyze the thermal characteristics from the chip, both COB and COM packages were fabricated during the operation to measure the chip junction temperatures (Tj) and thermal resistances of both specimens. According to the Tj measurement result, Tj ¼34.64 1C for the COM package with the removed insulator and Tj ¼45.28 1C for the COB package, showing that the COM package had an approximately 10 1C less thermal distribution. Similarly, the thermal resistance of the COM package was 0.7 1C/W, which was about 1 1C/W less than the COB package thermal resistance of 1.67 1C/W. Also, by comparatively analyzing the changes in the spectrum, color coordinates, and speed of light according to the driving time, it was found that luminous color stabilization may have contributed to the luminescence properties of the COM package, which has lower thermal resistance, and the degradation of the chip and packaging material can be minimized. & 2014 Elsevier Ltd. All rights reserved.
1. Introduction The commercialization of light emitting diodes (LED) with their application to general lighting has led to an increase in demand for high power LED packages. The basic conditions that need to be met by LED packages include excellent light extraction efficiency [1] and a heat dissipation structure for the package, which releases the heat created from the chip die during operation to outside the package [2,3]. As the light extraction efficiency and heat dissipation structure are not independent of each other, photons and heat are produced from the chip active area when power is supplied to the LED package. Except for some photons that are extracted outside
n Corresponding author. Postal address: Industry-University Cooperation Foundation, Kongju National University, 56 Gongjudaehak-Ro, Gongju-Si, Chungnam, 314-701, Republic of Korea. Tel.: þ 82 41 850 0528; fax: þ82 41 850 0544. E-mail address: [email protected] (S.-C. Ko).
the package, most photons are dissipated as heat. Thus, effectively expelled heat produced from the chip enhances the extraction efficiency and reliability of the LED package. Conventional LED lighting modules can be categorized into a structure where the LED package is attached to the printed circuit board (PCB) using the surface mount technology (SMT) process and a chip on board (COB) structure where the LED device is attached directly to the PCB board [4–6]. The LED light source module applied to the SMT process has numerous thermal nodes that are structurally complex. Therefore, an increase in the thermal resistance of each thermal node is inevitable in order to release the heat produced by the chip to the surrounding air. Although the COB structure has less thermal nodes in comparison to the LED light source module with the SMT process applied, the thermal resistance of the insulating layer was installed in the PCB structure where the LED die is located. This resistance increase hinders the release of heat caused by the LED die. Previous studies reported up to now the LED junction temperature, which is directly related to
http://dx.doi.org/10.1016/j.mssp.2014.11.025 1369-8001/& 2014 Elsevier Ltd. All rights reserved.
Please cite this article as: S.-R. Maeng, S.-C. Ko, Materials Science in Semiconductor Processing (2014), http://dx.doi.org/ 10.1016/j.mssp.2014.11.025i
S.-R. Maeng, S.-C. Ko / Materials Science in Semiconductor Processing ] (]]]]) ]]]–]]]
2
the optical characteristics of the LED package [7–10]. However, studies on heat dissipation structures, where the insulating layer between the LED device and the base metal of the board is partially removed, as well as an analysis of the thermal characteristics of this kind of structure have yet to be published. In this paper, after removing the insulator of the PCB area layer where the chip was packaged to minimize the thermal nodes, and directly packaging the chip to the PCB metal layer, a chip on metal (COM) package heat dissipation structure is proposed in order to effectively dissipate the heat produced by the chip during operation. Both COB and COM package types were fabricated to analyze the thermal characteristics of the proposed COM package. The chip junction temperature and thermal resistance for each specimen were measured. Furthermore, the change in spectrum, color coordinates, and speed of light were comparatively analyzed according to the driving time.
2. Experimental method The fabrication: The COB package has a structure where the chip is packaged to the metal PCB. The COB package also has five thermal nodes in order to simplify the complicated manufacturing process, reduce costs, and simplify the complex heat dissipation structure of SMT type LED modules. However, the metal PCB structure of COB includes a dielectric layer between the Cu layer where the chip is packaged and an aluminum plate, as shown in Fig. 1. This causes a thermal resistance increase due to the low thermal conductivity of the insulating layer. Thus, the structure hinders the dissipation of heat from the chip. The proposed COM package, as shown in Fig. 2, has the dielectric layer of the COB package metal PCB removed to directly install the chip to the aluminum metal base surface. This is so the heat produced from the chip can be directly absorbed by the aluminum metal base. The package
configuration is a low thermal resistance LED package structure with the simplest configuration of three thermal nodes. The test specimens used in this research were the COB and COM packages that were fabricated in the same conditions. The chips for the COB and COM packages were of InGaN/Sapphire type 1.1 mm 1.1 mm and 1 W and 16 chips were arranged in a multi array structure with 4 in parallel position and 4 in serial position. For the metal PCB, 2 types of COB PCB and COM PCB were fabricated as shown in Fig. 3. The chip was directly installed on the Cu layer for the COB and on the aluminum plate for the COM. The adhesive used between the PCB and the chip was Ag epoxy, which has a thermal conductivity of 20 W/mK. Table 1 organizes the properties of the material used in the manufacture of the LED. Fig. 4 shows the COM package assembly process.
3. Results and discussion For the fabricated COB and COM packages, the chip junction temperature and thermal resistance of the 2 LED package types were measured. The parameters during the measurement were as shown in Table 2 where the input current was 1 A. For the COM package, the forward voltage was 12.13 V, the input power dissipation was 12.13 W, and the COM package chip junction temperature was 34.65 1C when the ambient temperature was 26.25 1C. A temperature difference of 8.4 1C between the ambient temperature and chip junction temperature was observed. For the COB
Fig. 3. Comparison of COB PCB and COM PCB structure.
Fig. 1. COB type thermal node.
Fig. 2. COM type thermal node.
Please cite this article as: S.-R. Maeng, S.-C. Ko, Materials Science in Semiconductor Processing (2014), http://dx.doi.org/ 10.1016/j.mssp.2014.11.025i
S.-R. Maeng, S.-C. Ko / Materials Science in Semiconductor Processing ] (]]]]) ]]]–]]]
3
Table 1 LED material properties. Material
Encapsulant Chip Die adhesion Cu layer Dielectric layer Al plate
COB package
COM package
Thickness (mm)
Size (mm)
Thermal conductivity (W/mK)
Thickness (mm)
Size (mm)
Thermal conductivity (W/mK)
700 150 5–10 30 100 800
15 15 1.1 1.1 1.5 1.5 24 24 24 24 24 24
0.2 30 20 400 1.5 200
800 150 5–10 – – 700
15 15 1.1 1.1 1.5 1.5 – – 24 24
0.2 30 20 – – 200
Fig. 4. Assembly process: (a) adhesion bond on metal PCB (silver epoxy), (b) chip mount and wire bonding, (c) damping for en-capsulation material (silicone), (d) en-capsulation (mixed phosphor silicone), and (e) operating.
Table 2 Thermal resistance measurement parameters and the result. Parameter
COM package
COB package
K-factor (mk/W) Junction temperature (1C) Thermal resistance (1C/W) Input current (A) Ambient temperature (1C) Forward voltage VF (V) Power dissipation (W)
6.047 34.65 0.699 1.0 26.25 12.13 12.13
5.785 45.28 1.665 1.0 25.83 11.79 11.79
Fig. 5. Thermal resistance of COB and COM packages.
package, the forward voltage was 11.79 V, the input power dissipation was 11.79 W, and the COB package chip junction temperature (Tj) was 45.28 1C when the ambient temperature was 25.83 1C. A temperature difference of 17.7 1C was observed between the ambient temperature and the chip junction temperature. With regard to the chip junction
temperature of the 2 package types, it was observed that the COM package Tj ¼34.64 1CoCOB package Tj ¼45.28 1C. Thus, the COM package chip junction temperature was approximately 10 1C lower. Fig. 5 shows the thermal resistance (T3ster, Mentor Graphics Corp., USA) variation plot of the 2 package types. In order to compare the thermal distribution of the 2 LED package types, the COM and COB packages were set inside a 150 150 mm2 aluminum heat-sink, as shown in Fig. 6(a), and a uniform 1 A current input. The illuminated state of the LED was then captured through a thermal imaging camera to examine the temperature distribution of each package. The light emitting area maximum temperature (spot 1) of the COB package, shown on the left of Fig. 6(b), was 120 1C, while the COM package central area maximum temperature shown on the right was 97.6 1C. This shows that the COM package was about 22 1C less distributed in comparison to the COB package. To compare the optical characteristics of the COM and COB package type specimens, an input current of 1 A was applied and the variation in spectrum and color coordinates according to the driving time was compared. As shown in Fig. 7, although the spectrums at the initial stages of the input current application are similar, it was found that the spectrum change with the duration of driving time was greater for the COB package. A spectrum change implies a change in the illuminated color during the LED operation. Fig. 8 shows the change in the illuminated color according to the 2 LED package types operation time in the CIE color space. It was observed that the COB package with the insulating layer had a greater color coordinate change and the LED illuminated color is related to the temperature change. Fig. 9 shows the speed of light degradation rate according to the driving time change, assuming that the initially measured speed of light is 100% for both the COM
Please cite this article as: S.-R. Maeng, S.-C. Ko, Materials Science in Semiconductor Processing (2014), http://dx.doi.org/ 10.1016/j.mssp.2014.11.025i
S.-R. Maeng, S.-C. Ko / Materials Science in Semiconductor Processing ] (]]]]) ]]]–]]]
4
Fig. 6. The LED package temperature distribution of the application of the input current: (a) LED set and (b) thermal distribution during LED operation (thermal imaging camera).
Fig. 7. Spectrum variation according to the driving time: (a) COM package spectrum and (b) COB package spectrum.
Fig. 8. LED color shift according to the driving time. Fig. 9. Speed of light variation according to the driving time.
and COB packages. The input currents for both package types were 1 A and the speed of light variation was compared until the total driving time reached 100 min. As a result, the COM package speed of light degradation rate was saturated and stabilized at 95% after 60 min while the COB package speed of light degradation rate was at 84% after 100 min and the degradation continued. 4. Conclusions The COB package metal PCB layer configuration includes an insulating layer on the aluminum plate and the Cu layer on the insulating layer is plated with Ag where the chip is
packaged. The insulating layer of the COB metal PCB layer has a low thermal conductivity of 1.5 W/mK, which acts as a thermal barrier that hinders the dissipation of heat produced by the chip due to the increased thermal resistance. In this study, the insulating layer where the chip is installed in the COB package metal PCB structure was removed. A COM package where the chip can be directly attached to the metal PCB aluminum base was proposed. The chip Tj measurements of the 2 package types showed that the COM package with the removed insulating layer had Tj ¼34.64 1C and the COB package had Tj ¼45.28 1C. Thus, the COM package was about 10 1C lower in distribution. Similarly, for the thermal
Please cite this article as: S.-R. Maeng, S.-C. Ko, Materials Science in Semiconductor Processing (2014), http://dx.doi.org/ 10.1016/j.mssp.2014.11.025i
S.-R. Maeng, S.-C. Ko / Materials Science in Semiconductor Processing ] (]]]]) ]]]–]]]
resistance, the COM package thermal resistance was 0.7 1C/W, which was about 1 1C/W lower than the 1.67 1C/W thermal resistance of the COB package. Furthermore, the COM package with a low thermal resistance had a heat dissipation structure, which allowed for the stabilization of the illuminating color and minimization of the chip and packaging material degradation. Such characteristics reveal that the COM package can be applied as an LED illumination light source with a long lifespan.
5
[3] S.J. Lee, Opt. Eng. 45 (2006). (014601-1-014601-6). [4] Y.-B. Yoon, J.-W. Park, IEEE Trans. Compon. Packag. Technol. 32 (2009) 825–831. [5] R. Huber, “Thermal Management of Golden DRAGON LED” Application Note. OSRAM Opto Semiconductors, , 2008, 1–11. [6] M. Ha, S. Graham, Microelectron. Reliab. 52 (2012) 836–844. [7] J. Park, M. Shin, C.C. Lee, Opt. Lett. 29 (2004) 2656–2658. [8] S.L. Chuang, J. IEEE, Quantum Electron. 33 (1997) 970–979. [9] Z. Chuluunbaatar, C. Wang, E.S. Kim, N.Y. Kim, Int. J. Therm. Sci. 86 (2014) 307–313. [10] E. Juntunen, Olli Tapaninen, Aila Sitomaniemi, V. Heikkinen, IEEE Trans. Compon. Package. Manuf. Technol. 3 (2013) 1148–1154.
References [1] Hong Eugene and Nadarajah, Proc. Soc. Photo-Opt. Instrum. Eng. 5187 (2004) 93–99. [2] Hu. Jianzheng, Yang Lianqiao, Shin Moo Whan, Microelectron. J. 38 (2007) 148–154.
Please cite this article as: S.-R. Maeng, S.-C. Ko, Materials Science in Semiconductor Processing (2014), http://dx.doi.org/ 10.1016/j.mssp.2014.11.025i