Thermal management is one of the key technologies for high-power Light emitting diode(LED)entering into the general illuminating field.Successful thermal management depends on optimal packaging structure and selected ...Thermal management is one of the key technologies for high-power Light emitting diode(LED)entering into the general illuminating field.Successful thermal management depends on optimal packaging structure and selected packaging materials.In this paper,the aluminum is employed as a substrate of LED,3×3 array chips are placed on the substrate,heat dissipation performance is simulated using finite element analysis(FEA)software,analyzed are the influences on the temperature of the chip with different convection coefficient,and optical properties are simulated using optical analysis software.The results show that the packaging structure can not only effectually improve the thermal performance of high-power LED array but also increase the light extraction efficiency.展开更多
In order to study the role of printed circuit board(PCB)in high-power LED heat dissipation,a simple model of high-power LED lamp was designed.According to this lamp model,some thermal performances such as thermal resi...In order to study the role of printed circuit board(PCB)in high-power LED heat dissipation,a simple model of high-power LED lamp was designed.According to this lamp model,some thermal performances such as thermal resistances of four types of PCB and the changes of LED junction temperature were tested under three different working currents.The obtained results indicate that LED junction temperature can not be lowered significantly with the decreasing thermal resistance of PCB.However,PCB with low thermal resistance can be matched with smaller volume heat sink,so it is hopeful to reduce the size,weight and cost of LED lamp.展开更多
Light emitting diodes(LEDs)have accounted for most of the lighting market as the technology matures and costs continue to reduce.As a new type of e-waste,LED is a double-edged sword,as it contains not only precious an...Light emitting diodes(LEDs)have accounted for most of the lighting market as the technology matures and costs continue to reduce.As a new type of e-waste,LED is a double-edged sword,as it contains not only precious and rare metals but also organic packaging materials.In previous studies,LED recycling focused on recovering precious and strategic metals while ignoring harmful substances such as organic packaging materials.Unlike crushing and other traditional methods,hydrothermal treatment can provide an environment-friendly process for decomposing packaging materials.This work developed a closed reaction vessel,where the degradation rate of plastic polyphthalamide(PPA)was close to 100%,with nano-TiO_(2)encapsulated in plastic PPA being efficiently recovered,while metals contained in LED were also recycled efficiently.Besides,the role of water in plastic PPA degradation that has been overlooked in current studies was explored and speculated in detail in this work.Environmental impact assessment revealed that the proposed recycling route for waste LED could significantly reduce the overall environmental impact compared to the currently published processes.Especially the developed method could reduce more than half the impact of global warming.Furthermore,this research provides a theoretical basis and a promising method for recycling other plastic-packaged e-waste devices,such as integrated circuits.展开更多
As the blue and yellow lights are complementary colors, a blue InGaN LED chip is coated hy a yellow phosphor film to generate white light based on luminescence conversion mechanism. The emitted light of a blue LED is ...As the blue and yellow lights are complementary colors, a blue InGaN LED chip is coated hy a yellow phosphor film to generate white light based on luminescence conversion mechanism. The emitted light of a blue LED is used as the primary source for exciting fluorescent material such as cerium doped yttrium aluminum garnet with the formula Y3Al2O12 : Ce^3+ (in short: YAG : Ce^3+ ). The matching of the spectrum of the blue LED chips and the YAG : Ce^3+ yellow phosphor is studied to improve the conversion efficiency. The packaging methods and manufacturing processes for high power single chip-white LEDs are introduced. The uniformity of the output white light is investigated. Based on the characteristics of the high power white LEDs, some approaches and processes are suggested to improve the light uniformity when they are fabricated. The effectiveness of those approaches on the improvement of LEDs is discussed in detail and some interesting conclusions are also presented.展开更多
To improve the heat dissipation of high-power light-emitting diodes (LEDs), a cooling system with a fan is proposed. In the experiment, the LEDs array of 18 W composed of 6 LEDs of 3 W is used and the room temperature...To improve the heat dissipation of high-power light-emitting diodes (LEDs), a cooling system with a fan is proposed. In the experiment, the LEDs array of 18 W composed of 6 LEDs of 3 W is used and the room temperature is 26oC. Results show that the temperature of the substrate of LEDs reaches 62oC without the fan, however, it reaches only 32oC when the best cooling condition appears. The temperature of the LEDs decreases by 30oC since the heat produced by LEDs is transferred rapidly by the fan. The experiment demonstrates that the cooling system with the fan has good performance.展开更多
In this paper, we conduct theoretical research on design and implementation on wind and light complementary LED lighting controller based on the novel base board packaging technology. LED, as a kind of device can conv...In this paper, we conduct theoretical research on design and implementation on wind and light complementary LED lighting controller based on the novel base board packaging technology. LED, as a kind of device can convert electric power into visible light directly the homomorphism of semiconductor devices, with high efficiency and small energy consumption, good light quality, use safety, long service life, green environmental protection, flexible control as this is common lamps and lanterns is incomparable advantage. Therefore, it is considered to be 21 century of a new generation of lighting source. Based on the superiority of LED, it is widely applied in many fields of lighting. To enhance the traditional solar based pure LED system, we enhance it with the combination of the wind power and the optimized controller that holds specific meaning.展开更多
Thermal property is one of the most important properties of light-emitting diode (LED). Thermal property of LED packaging material determines the heat dissipations of the phosphor and the chip surface, accordingly h...Thermal property is one of the most important properties of light-emitting diode (LED). Thermal property of LED packaging material determines the heat dissipations of the phosphor and the chip surface, accordingly having an influence on the light-emitting efficiency and the life-span of the device. In this paper, photoacoustic piezoelectric (PAPE) technique has been employed to investigate the thermal properties of polyvinyl alcohol (]?VA) and silicon dioxide, which are the new and the traditional packaging materials in white LED, respectively. Firstly, the theory of PAPE technique has been developed for two-layer model in order to investigate soft materials; secondly, the experimental system has been set up and adjusted by measuring the reference sample; thirdly, the thermal diffusivities of PVA and silicon dioxide are measured and analysed. The experimental results show that PVA has a higher thermal diffusivity than silicon dioxide and is a better packaging material in the sense of thermal diffusivity for white LED.展开更多
Achieving a high color rendering index(CRI)and luminous stability in single-structured Ce:Y_(3)Al_(5)O_(12)(Ce:YAG)phosphor ceramics(PCs)is crucial for high-power white light-emitting diodes or laser diodes(LEDs/LDs)....Achieving a high color rendering index(CRI)and luminous stability in single-structured Ce:Y_(3)Al_(5)O_(12)(Ce:YAG)phosphor ceramics(PCs)is crucial for high-power white light-emitting diodes or laser diodes(LEDs/LDs).However,cyan valleys and insufficient amounts of the red component in the Ce:YAG emission spectra significantly limit their real applications.In this work,a series of Ce,Mn:Y_(3)(Al,Sc)_(2)Al_(3)O_(12)(Ce,Mn:YSAG)PCs were fabricated by vacuum sintering,and efficient spectral regulation was realized for full-color lighting.The cyan valley was filled by the blueshifted emission peak of Ce^(3+)via Sc^(3+)doping.The orange‒red emission at approximately 580 nm was effectively supplemented via Mn^(2+)doping.In particular,CRI of Ce,Mn:YSAG increased from 56.4 to 85.8,a 52%increase compared with that of Ce:YAG under high-power LED excitation,and the operating temperature was stable at approximately 50℃for long working time.Moreover,CRI of 80.9 could still be obtained for PC-based white LDs.These results indicated that Ce,Mn:YSAG PC,which has excellent CRI and luminous stability,is an extremely promising color convertor for high-power white LEDs/LDs.展开更多
基金Key Scientific and Technological Research Projects of Henan Province(072102240027)Dr Foundation of Henan Polytechnic University(648602)Postgraduate Degree Thesis Innovation Foundation of Henan Polytechnic University(644005)
文摘Thermal management is one of the key technologies for high-power Light emitting diode(LED)entering into the general illuminating field.Successful thermal management depends on optimal packaging structure and selected packaging materials.In this paper,the aluminum is employed as a substrate of LED,3×3 array chips are placed on the substrate,heat dissipation performance is simulated using finite element analysis(FEA)software,analyzed are the influences on the temperature of the chip with different convection coefficient,and optical properties are simulated using optical analysis software.The results show that the packaging structure can not only effectually improve the thermal performance of high-power LED array but also increase the light extraction efficiency.
基金Special Fund Project of Science and Technology Innovation of Dongli District(21090302)Research Projectof Applied Basic and Front Technologies of Tianjin(10JCZDJC15400)
文摘In order to study the role of printed circuit board(PCB)in high-power LED heat dissipation,a simple model of high-power LED lamp was designed.According to this lamp model,some thermal performances such as thermal resistances of four types of PCB and the changes of LED junction temperature were tested under three different working currents.The obtained results indicate that LED junction temperature can not be lowered significantly with the decreasing thermal resistance of PCB.However,PCB with low thermal resistance can be matched with smaller volume heat sink,so it is hopeful to reduce the size,weight and cost of LED lamp.
基金supported by the National Natural Science Foundation of China(52270132).
文摘Light emitting diodes(LEDs)have accounted for most of the lighting market as the technology matures and costs continue to reduce.As a new type of e-waste,LED is a double-edged sword,as it contains not only precious and rare metals but also organic packaging materials.In previous studies,LED recycling focused on recovering precious and strategic metals while ignoring harmful substances such as organic packaging materials.Unlike crushing and other traditional methods,hydrothermal treatment can provide an environment-friendly process for decomposing packaging materials.This work developed a closed reaction vessel,where the degradation rate of plastic polyphthalamide(PPA)was close to 100%,with nano-TiO_(2)encapsulated in plastic PPA being efficiently recovered,while metals contained in LED were also recycled efficiently.Besides,the role of water in plastic PPA degradation that has been overlooked in current studies was explored and speculated in detail in this work.Environmental impact assessment revealed that the proposed recycling route for waste LED could significantly reduce the overall environmental impact compared to the currently published processes.Especially the developed method could reduce more than half the impact of global warming.Furthermore,this research provides a theoretical basis and a promising method for recycling other plastic-packaged e-waste devices,such as integrated circuits.
基金"863"Project from Ministry of Science & Technology of China(2006AA03A116)
文摘As the blue and yellow lights are complementary colors, a blue InGaN LED chip is coated hy a yellow phosphor film to generate white light based on luminescence conversion mechanism. The emitted light of a blue LED is used as the primary source for exciting fluorescent material such as cerium doped yttrium aluminum garnet with the formula Y3Al2O12 : Ce^3+ (in short: YAG : Ce^3+ ). The matching of the spectrum of the blue LED chips and the YAG : Ce^3+ yellow phosphor is studied to improve the conversion efficiency. The packaging methods and manufacturing processes for high power single chip-white LEDs are introduced. The uniformity of the output white light is investigated. Based on the characteristics of the high power white LEDs, some approaches and processes are suggested to improve the light uniformity when they are fabricated. The effectiveness of those approaches on the improvement of LEDs is discussed in detail and some interesting conclusions are also presented.
文摘To improve the heat dissipation of high-power light-emitting diodes (LEDs), a cooling system with a fan is proposed. In the experiment, the LEDs array of 18 W composed of 6 LEDs of 3 W is used and the room temperature is 26oC. Results show that the temperature of the substrate of LEDs reaches 62oC without the fan, however, it reaches only 32oC when the best cooling condition appears. The temperature of the LEDs decreases by 30oC since the heat produced by LEDs is transferred rapidly by the fan. The experiment demonstrates that the cooling system with the fan has good performance.
文摘In this paper, we conduct theoretical research on design and implementation on wind and light complementary LED lighting controller based on the novel base board packaging technology. LED, as a kind of device can convert electric power into visible light directly the homomorphism of semiconductor devices, with high efficiency and small energy consumption, good light quality, use safety, long service life, green environmental protection, flexible control as this is common lamps and lanterns is incomparable advantage. Therefore, it is considered to be 21 century of a new generation of lighting source. Based on the superiority of LED, it is widely applied in many fields of lighting. To enhance the traditional solar based pure LED system, we enhance it with the combination of the wind power and the optimized controller that holds specific meaning.
基金Project supported by the National Nature Science Foundation of China (Grant No. 50506006)the National High Technology Research and Development Program of China (Grant No. 2006AA03A116)the Youth Foundation of University of Electronic Science and Technology of China (Grant No. JX05024)
文摘Thermal property is one of the most important properties of light-emitting diode (LED). Thermal property of LED packaging material determines the heat dissipations of the phosphor and the chip surface, accordingly having an influence on the light-emitting efficiency and the life-span of the device. In this paper, photoacoustic piezoelectric (PAPE) technique has been employed to investigate the thermal properties of polyvinyl alcohol (]?VA) and silicon dioxide, which are the new and the traditional packaging materials in white LED, respectively. Firstly, the theory of PAPE technique has been developed for two-layer model in order to investigate soft materials; secondly, the experimental system has been set up and adjusted by measuring the reference sample; thirdly, the thermal diffusivities of PVA and silicon dioxide are measured and analysed. The experimental results show that PVA has a higher thermal diffusivity than silicon dioxide and is a better packaging material in the sense of thermal diffusivity for white LED.
基金financially supported by the National Key R&D Program of China(No.2021YFB3501700)the National Natural Science Foundation of China(Nos.52202135,61975070,and 52302141)+4 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),the International S&T Cooperation Program of Jiangsu Province(No.BZ2023007)the Key R&D Project of Jiangsu Province(Nos.BE2023050 and BE2021040)Natural Science Foundation of Jiangsu Province(No.BK20221226)the Special Project for Technology Innovation of Xuzhou City(Nos.KC23380,KC21379,KC22461,and KC22497)the Open Project of State Key Laboratory of Crystal Materials(No.KF2205).
文摘Achieving a high color rendering index(CRI)and luminous stability in single-structured Ce:Y_(3)Al_(5)O_(12)(Ce:YAG)phosphor ceramics(PCs)is crucial for high-power white light-emitting diodes or laser diodes(LEDs/LDs).However,cyan valleys and insufficient amounts of the red component in the Ce:YAG emission spectra significantly limit their real applications.In this work,a series of Ce,Mn:Y_(3)(Al,Sc)_(2)Al_(3)O_(12)(Ce,Mn:YSAG)PCs were fabricated by vacuum sintering,and efficient spectral regulation was realized for full-color lighting.The cyan valley was filled by the blueshifted emission peak of Ce^(3+)via Sc^(3+)doping.The orange‒red emission at approximately 580 nm was effectively supplemented via Mn^(2+)doping.In particular,CRI of Ce,Mn:YSAG increased from 56.4 to 85.8,a 52%increase compared with that of Ce:YAG under high-power LED excitation,and the operating temperature was stable at approximately 50℃for long working time.Moreover,CRI of 80.9 could still be obtained for PC-based white LDs.These results indicated that Ce,Mn:YSAG PC,which has excellent CRI and luminous stability,is an extremely promising color convertor for high-power white LEDs/LDs.
基金Project supported by Technology-Innovation and Results-transformation of Jiangsu Province(BA2008049)The State Key Laboratory of Materialsoriented Chemical Engineering(KL09-11)~~