Analysis of high power LED LED lighting technology
High-brightness light-emitting diodes (LEDs) are becoming a new generation of light sources for upgrading the traditional lighting industry because of their low power consumption, long life, fast response, no stroboscopic, small size, no pollution, and easy integration. Today, with the focus on energy conservation, emission reduction and environmental protection, semiconductor lighting has become a new economic growth point, and it has been highly valued by governments, science and technology and industry around the world. So far, the United States, Japan, Europe, China and Taiwan have launched their own semiconductor lighting plans, and the high-power LED lighting industry has become one of the most eye-catching industries. It is worth noting that up to now, the upstream epitaxial chip technology has been basically mature and stereotyped, and the cheap and good LED chip has been able to meet the lighting demand. Now the pricing power is shifting and developing in the midstream packaging and downstream application terminal market. This means that who can apply the chip and manufacture long-life, high-efficiency high-power LED lighting products, who is likely to become the ultimate winner of the LED industry. The problems of high-power LED lighting package and application are highlighted. The most important part is how to solve the heat-dissipation problem of high-power LED lighting. This is not only a technical problem in structural design and engineering applications, but also a thermal management mode. And scientific issues such as fluid mechanics. It is completely different from the existing "chip-aluminum substrate-heat-dissipating three-layer structure" high-power LED series lighting technology. We developed the "chip-heat-distribution integration (two-layer structure) integrated high-power LED lighting series lamps", in the technical route The aspect may be revolutionary and subversive, and will become a new development direction for the high-power LED lighting industry. 1. Status of high-power LED lighting products At present, the luminous efficiency of LEDs can convert about 30% of electrical energy into light, and the remaining 70% of electrical energy is almost converted into thermal energy, which causes the temperature of the LED to rise. Because of its very small heat, low-power LEDs can be used without any heat-dissipation measures, such as instrument lights, signal lights, and small-size LCD screen backlights. However, for high-power LEDs, when applied to lighting fields such as commercial buildings, roads, tunnels, industrial and mining, etc., heat dissipation is a big problem. If the heat of the LED chip cannot be dissipated, it will accelerate the aging of the chip, light decay, color shift, and shorten the life of the LED. Therefore, the structural mode and thermal management design of high-power LED lighting systems are very important. Now all high-power LED lighting fixtures on the market use "chip-aluminum substrate-heatsink three-layer structure mode", that is, the chip is first packaged on an aluminum substrate to form an LED light source module, and then the light source module is placed on the heat sink to be manufactured. High-power LED lighting fixtures. It should be noted that the current thermal management system for high-power LEDs still uses LEDs for early use in indicator lights and display lights, and is a thermal management mode for low-power LEDs. The high-power LED illumination is prepared by using the "chip-aluminum substrate-heatsink three-layer structure mode", and there are obviously unreasonable places in the system structure, such as the contact thermal resistance between the structures, the junction temperature is high, and the heat dissipation efficiency is low, so the chip The released heat cannot be effectively exported and dissipated, resulting in low luminous efficacy, large light decay, and short life of the LED lighting fixture, which cannot meet the lighting demand. How to improve the heat dissipation capability of the package is one of the key technologies to be solved in the current stage of high-power LED. The development direction and key points of LED lighting products are: high power, low thermal resistance, high light output, low light decay, small size and light weight, which makes the heat dissipation efficiency of LEDs higher and higher. However, due to many factors such as structure, cost and power consumption, high-power LED lighting is difficult to adopt active heat dissipation mechanism, but only passive heat dissipation mechanism is adopted, but passive heat dissipation has greater limitations; and LED energy conversion efficiency is higher. Low, about 70% of the current conversion to heat, even if the luminous efficiency is doubled, 40% of the energy is converted into heat. In other words, it is difficult to increase the degree of heat dissipation, so in the long run, the heat dissipation problem of high-power LED lighting will be a long-standing problem. Nowadays, the time for applying high-power LEDs to lighting has matured, and the development of efficient and natural heat-dissipating thermal management system has become a prerequisite and a key factor for the industrialization of high-power LED lighting. Therefore, a new technical route and system structure are needed to completely solve the problem of heat dissipation of high-power LED lighting. 123 Show remaining content on this page 2. New technical route for high-power LED lighting industry In view of the existing high-power LED lighting and heat dissipation technology, there are many problems of low thermal resistance and low heat dissipation. We try to solve the problem of low light efficiency, serious light decay and cost by high-power LED illumination through the "chip-heat dissipation integration (two-layer structure) mode". Higher series of questions. 2.1 Technical route "Chip-heat-dissipation integration (two-layer structure) mode" not only removes the aluminum substrate structure, but also places a plurality of chips directly on the heat sink to form a single-source multi-chip module, and prepares an integrated high-power LED. The luminaire and the light source are single, and are a surface light source or a cluster light source. 2.2 Technology key How to enhance the thermal conductivity of the chip and reduce the thermal resistance interface layer, which involves thermal management system structural mode, fluid mechanics and engineering applications of super-thermal materials; how to effectively control the heat storage of the heat-dissipating matrix, plan the convective heat dissipation path, and establish efficient The natural convection cooling system starts with the design of the luminaire structure. 2.3 technical solutions Reduce the thermal resistance layer by changing the LED light source package structure, heat dissipation structure and lamp structure mode; apply super-thermal conductivity material to increase the thermal conductivity of the chip heat source; optimize the thermal management system based on the "chip-heat dissipation integrated two-layer structure", increase The flow of air forms a natural convection heat. 2.4 design ideas The high-power LED lamps are prepared in a modular manner. The light source, heat dissipation, and external structure are packaged into one integral module, and the modules are independent of each other. Any one module can be replaced separately. When one part fails, only the faulty module needs to be replaced, without You can continue to work normally by replacing other modules or replacing them as a whole. All module parts of the luminaire can be disassembled by hand to achieve convenient, fast and low-cost maintenance. 2.5 design points Modularization of the system, in addition to meeting the heat dissipation and replacement requirements of the luminaire, must also meet the optical (optical efficiency) requirements and modeling (market) requirements of the LED lighting fixture. 123 Show remaining content on this page 3, chip-heat dissipation integrated structure "Chip-heat dissipation integration (two-layer structure) mode" is a new type of LED light source package mode, structure mode and thermal management system mode. The high-power LED lighting fixtures prepared by using this technology mode not only completely solve the heat dissipation problem, but also effectively solve problems such as light distribution, light efficiency, life and maintenance, and have developed long life and high light efficiency. High-power LED series products, such as street lamps, downlights, tunnel lights, mining lamps, car headlights, landscape lights and other lighting equipment. 3.1 Technical characteristics 3.1.1 The chip and the aluminum alloy + super-thermal conductive material composite substrate (heat sink) are connected as one body, and the unique high-power LED packaging technology is applied to directly package the plurality of chips directly on the heat dissipation substrate, so that the chip and the heat dissipation substrate are The thermal resistance between the two is smaller, and the entire heat sink base is a complete luminaire that forms an integrated high-power LED lighting component. 3.1.2 Based on the principle of bionics, the thermal management system is designed, and the thermal resistance model of chip-heat dissipation integrated two-layer structure is established. The junction temperature calculation and life prediction are carried out. The heat-distributing integrated two-layer structure of the chip is characterized in that the heat source chip is directly packaged on the heat sink. As the temperature of the heat source increases, the air flows in the porous heat sink, and the porous provides a flow channel for air convection, and the heat is Automatically emitted to ensure that the chip works properly within the safe operating temperature range. Advanced thermal and thermal convection systems ensure good heat dissipation and further increase the luminous efficiency of the chip. 3.1.3 The chip (45mil×45mi1) is packaged in an integrated package (the chip is concentrated in a small area), and the surface light source with high light efficiency is obtained, which has the characteristics of high luminous flux density, high total luminous flux and low glare. At present, the use of the above technology has produced a "chip-heat-dissipation integrated (two-layer structure) mode" high-power LED lighting fixtures, such as street lights, tunnel lights, downlights, spotlights and so on. In addition, at present, high-power LED car headlights require electric fans to enhance heat dissipation, which is difficult to meet the needs of market applications. The cluster-type high-power LED car headlights made of two-layer structure have solved the current LED light source in the automotive lamp industry. Limitations of manufacturing headlights for automobiles 3.2 Product technical indicators and advantages (1) Efficient heat dissipation: Adopt natural heat dissipation method to completely solve the problem of high-power LED heat dissipation (temperature difference <4°C, heat sink temperature <60°C, measured under the condition of ambient temperature 35°C); (2) Large current: the rated current supplied to the chip is 400-450 mA per piece; (3) High luminous efficiency: the whole lighting effect reached 90.9 lm/W; (4) Long life: 50000h; (5) Low light decay: The test results of the National Lighting Quality Supervision and Inspection Center are: 1000h life test without light decay; (6) Integrated: The integrated type is COR (ChipOnRadiator), that is, the chip integration is directly bonded to the heat sink, which is completely different from the integrated COB (ChipOnBoard) integrated on the aluminum substrate. Integrated chip is single, surface light source, single light source or cluster The light source (mounted glass lens) is fired; (7) The lighting effect is the same as the traditional non-LED light source, and does not change the habit of human light; (8) Simple structure: easy to maintain, no need to replace it. 4. High-tech LED lighting industry technology development direction At present, for the technical route of the high-power LED lighting industry, we believe that there are two ways to choose: one road is to continue along the "chip-aluminum substrate-heatsink (three-layer structure) mode" technology route; the other road is Develop a "chip-heat dissipation integration (two-layer structure) mode" technical route. "Chip-heat-dissipation integrated structure" is an emerging technology. In this structure, except for the chip, everything is completely new, including chip-heat dissipation integration, packaging, power supply, complete equipment, testing, and even standards. It makes high-power LED lighting products have obvious advantages in terms of life, light efficiency, quality, design, controllability, cost, etc., compared with the "chip-aluminum substrate-heatsink three-layer structure mode", which is high-power and efficient in China. Semiconductor solid-state lighting research, application and industrialization can be a new field of great potential. (Author: Hank McKinnell, etc.) Casual Hats,Women'S Casual Hat,Wool Church Hat,Winter Faux Fur Hat SHAOXING YONGJING FASHION HATS & ACCESSORY CO.,LTD. , https://www.yongjingchurchhat.com