It is well known that the electrical energy added by the LED under working conditions is not completely converted into light energy, but a part is converted into heat energy. As the fourth generation of light source, LED has great development prospects due to its advantages of energy saving, environmental protection and long life. However, the LED is extremely sensitive to temperature, and the junction temperature rise will affect the LED life, light efficiency, light color (wavelength), color temperature, light shape (light distribution), and forward voltage, maximum injection current, luminosity, color, and electrical parameters. And reliability, etc.
First, too high a temperature can cause permanent damage to the LED. When the LED temperature exceeds the carrying temperature of the chip, the luminous efficiency of the LED will be rapidly reduced, resulting in significant light decay and damage. In addition, LEDs are mostly encapsulated in transparent epoxy. If the junction temperature exceeds the solid phase transition temperature (usually 125 ° C), the packaging material will change to a rubbery state and the thermal expansion coefficient will rise sharply, resulting in LED open circuit and failure.
Second, an increase in temperature will shorten the life of the LED. The life of an LED is manifested by its light decay, which means that the time is long and the brightness is getting lower and lower until it is finally extinguished. It is usually defined that the LED light flux is attenuated by 30% of its life. The defects existing in the LED chip material will rapidly proliferate and multiply at higher temperatures until invading the illuminating region, forming a large number of non-radiative recombination centers, which seriously reduce the luminous efficiency of the LED.
In addition, under high temperature conditions, micro-defects in the material and fast-expanding impurities from the interface and the electric plate are also introduced into the light-emitting region, forming a large number of deep levels, which also accelerates the light decay of the LED device. At the same time, at high temperature, the transparent epoxy resin will be denatured and yellow, which will affect its light transmission performance. The higher the working temperature, the faster the process will proceed, which is another major cause of LED light decay. In addition, the light decay of the phosphor is also a major cause of the LED light decay, because the phosphor's attenuation at high temperatures is very serious.
The problem of heat dissipation is a major obstacle in the development of LEDs for use as lighting objects. Therefore, reducing the temperature of LEDs by various means has become a problem discussed by major manufacturers. Since the heat dissipation of LEDs is now more and more important to people, various heat dissipation technologies have also been applied to LED lighting technology!
Since the LED light source itself has no radiation heat dissipation function, the heat dissipation path of the LED lighting fixture can only derive heat through a heat sink closely combined with the LED lamp bead. Any radiator, in addition to being able to quickly transfer heat from the heat source to the surface of the radiator, the most important thing is to rely on convection and radiation to dissipate heat into the air. Thermal conduction only solves the heat transfer path, and thermal convection is the main function of the heat sink. The heat dissipation performance is mainly determined by the heat dissipation area, shape, and natural convection strength. Thermal radiation is only an auxiliary function.
Radiator, as a common way of cooling LED lamps, its shape and material have undergone repeated changes. At present, there are several types of LED heat sinks on the market: die-cast aluminum radiators, extruded aluminum radiators, stamped aluminum radiators, plastic-coated aluminum radiators, and high-heat-conducting plastic radiators.
The production cost of the die-cast aluminum radiator is controllable, the heat-dissipating fin cannot be made thin, and it is difficult to maximize the heat-dissipating area. The heat dissipating fins of the extruded aluminum radiator can be made a lot of thin, and the heat dissipating area is maximized. When the cooling fins work, the air convection heat is automatically formed, and the heat dissipating effect is better, but the processing cost is higher.
The stamped aluminum radiator is stamped and pulled up by the punching machine and the die for the steel and aluminum alloy, so that it becomes a cup-type radiator. The inner and outer periphery of the stamped heat sink is smooth, and the heat-dissipating area is limited due to the wingless. The heat-conducting plastic used in the plastic-coated aluminum radiator is a thermoplastic material. The fluidity, density, toughness and strength of the material are easy to be injection-molded. It has good resistance to cold and heat shock cycles, excellent insulation performance, and all-aluminum radiator. Compared with the processing cost is low, the processing cycle is short, the processing temperature is low; the finished product is not easy to be broken; the customer-supplied injection molding machine can carry out the differential shape design and production of the lamp, and the plastic-coated aluminum radiator has good insulation performance and is easy to pass the safety regulation.
High thermal conductivity plastic radiator, high thermal conductivity plastic radiator An all-plastic radiator, its thermal conductivity is several times higher than ordinary plastic, with excellent heat conduction and heat radiation capability; it can be applied to new insulation of various power lamps. Heat sink material.
Company Introduction:
Dongfeng Motor Corporation is one of the largest automobile manufacturers in China. The company has a history of more than 50 years and is headquartered in Wuhan, Hubei Province. Dongfeng Motor Corporation has a strong presence in the Chinese automobile market and has partnerships with several international automobile manufacturers, including Nissan, Honda, and PSA Peugeot Citroen. The company has a global workforce of more than 180,000 employees and operates in more than 100 countries worldwide. Dongfeng Motor Corporation is committed to producing high-quality vehicles that meet the needs of its customers while also promoting sustainable development and environmental protection.
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