At present, the biggest technical problem of LED lighting fixtures is the heat dissipation problem, poor heat dissipation leads to LED driver power supply, and electrolytic capacitors have become a shortboard for the further development of LED lighting fixtures, the cause of premature failure of the LED light source.
In the use of LV LED light source lamps and lanterns program, due to the LED light source working at low voltage (VF = 3.2V), high current (IF = 300 ~ 700mA) working state, heat is very strong, the traditional lamps and lanterns of the space are small, small area of the radiator is difficult to export the heat quickly. Despite the use of a variety of thermal solutions, the results are unsatisfactory, LED lighting fixtures have become an insoluble problem. Looking for easy-to-use, good thermal conductivity and low-cost heat dissipation materials is always in the effort.
LED light source in the current power, about 30% of the electrical energy into light energy, the rest into heat energy. Therefore, exporting so much heat energy as soon as possible is the key technology of the LED lamp structure design, heat energy needs to be through heat conduction, heat convection, and heat radiation to disseminate. Only as soon as possible to export heat to effectively reduce the cavity temperature within the LED lamps and lanterns, to protect the power supply that does not work in a long-lasting high-temperature environment, and to avoid the LED light source due to long-term high-temperature work and premature failure.
LED Lighting Fixtures Heat Dissipation Path
Because the LED light source itself does not have infrared, or ultraviolet, the LED light source itself does not radiate heat function, LED lighting fixtures and heat dissipation path can only be through the close combination of LED lamp bead plate heat sink to export heat. Heat sinks must have heat conduction, heat convection, and heat radiation.
Any radiator, in addition to quickly conducting heat from the heat source to the surface of the radiator, the main thing is still to rely on convection and radiation to emit heat into the air. Thermal conduction only solves the way of heat transfer, and thermal convection is the main function of the radiator, heat dissipation performance is mainly determined by the ability of the heat dissipation area, shape, and natural convection strength, thermal radiation is only an auxiliary role.
Generally speaking, if the heat from the heat source to the surface of the heat sink distance is less than 5mm, then as long as the material thermal conductivity is greater than 5, the heat can be exported, and the rest of the heat dissipation must be dominated by thermal convection.
Most of the LED lighting sources still use low voltage (VF = 3.2V), high current (IF = 200 ~ 700mA) LED lamp beads, due to the high heat when working, must use a higher thermal conductivity of aluminum alloy. Usually, there are die-casting aluminum heat sinks, extruded aluminum heat sinks, and stamped aluminum heat sinks. Die-casting aluminum radiator is a pressure casting parts technology, the liquid zinc-copper-aluminum alloy is poured into the inlet of the die-casting machine, the die-casting machine by die-casting, casting a pre-designed mold limited to the shape of the radiator.
Die-cast Aluminum Radiator
Production costs can be controlled, the heat sink wing can not be made thin, and it is difficult to make the heat dissipation area large. LED lamps and lantern radiators commonly used die-casting materials for ADC10 and ADC12.
Extruded Aluminum Heat Sink
Liquid aluminum is extruded through a fixed die, and then the bar is cut into the desired shape of the radiator through machining, and the post-processing cost is high. The heat sink wings can be made much thinner and thinner to maximize the expansion of the heat dissipation area. The heat sink wings automatically form air convection to diffuse the heat when they are working, which has a better heat dissipation effect. Commonly used materials are AL6061 and AL6063.
Stamped Aluminum Radiator
Through the press and die on the steel, aluminum alloy sheet stamping, pulling up, so that it becomes a cup and tube type radiator, stamping formed radiator inside and outside the periphery of the smooth, due to the lack of wings and the limited area of heat dissipation. Commonly used aluminum alloy materials are 5052, 6061, 6063. stamped parts are very small in mass, have high material utilization, a low-cost solution.
Aluminum alloy heat sink thermal conductivity is ideal, and more suitable for isolated switching constant current power supply. For non-isolated switching constant current power supply, it is necessary to do a good job of isolation of AC and DC, high voltage, and low voltage power supply through the structural design of lamps and lanterns to pass CE or UL certification.
Plastic Clad Aluminum Heat Sink
It is a kind of heat sink with an aluminum core in a thermally conductive plastic shell. Thermally conductive plastic and aluminum heat sink core in the injection molding machine in a single molding, aluminum heat sink core to do buried parts, need to be pre-machined. heat from the LED lamp bead through the aluminum heat sink core rapid conduction to the thermally conductive plastic, the thermal conductivity of the plastic to use its multi-wing formation of air convection heat dissipation, the use of its surface to radiate part of the heat.
Plastic-coated aluminum radiators generally use the original color of thermally conductive plastic white and black, black plastic plastic-coated aluminum radiator radiation heat dissipation effect is a little better. Thermally conductive plastic a thermoplastic material, material fluidity, density, toughness, and strength are easy to injection molding, with good resistance to cold and thermal shock cycle characteristics, and excellent insulation properties. Thermally conductive plastic radiation coefficient is better than ordinary metal materials. Thermally conductive plastic density than die-casting aluminum and ceramic 40% smaller than the same shape of the radiator, plastic-coated aluminum weight can be reduced by nearly one-third; compared with the all-aluminum radiator processing costs are low, the processing cycle is short, the processing temperature is low; the finished product is not fragile; the customer's injection molding machine can be used for lamps and lanterns to differentiate the shape of the design and production. Plastic-clad aluminum radiator with good insulation performance, easy to pass the safety regulations.
High thermal conductivity plastic radiator
High thermal conductivity plastic radiator recently developed very quickly, high thermal conductivity plastic radiator is an all-plastic radiator, and its thermal conductivity is dozens of times higher than ordinary plastics, up to 2-9w/mk, with excellent thermal conductivity, and heat radiation capabilities; can be applied to a variety of power lamps and lanterns of the new insulation and heat dissipation materials, can be widely used in 1W ~ 200W of various types of LED lamps and lanterns.
High thermal conductivity plastic voltage resistance level up to 6000V AC, suitable for the use of non-isolated switching constant current power supply, high-voltage linear constant current power supply for HVLED. This kind of LED lighting fixture is easy to pass CE, TUV, UL, and other strict safety testing. HVLED adopts high voltage (VF = 35-280VDC), small current (IF = 20-60mA) working state, HVLED bead board heat generation is therefore reduced. High thermal conductivity plastic heat sinks using traditional injection molding, and extrusion machines are available. One-time molding, high finish finish. Significantly improving the efficiency of production, and molding design flexibility can give full play to the designer's design concept. High thermal conductivity plastic radiator is made of PLA (corn starch) polymerization, full degradation, no residue, and no chemical pollution, the production process is free of any heavy metal pollution, no sewage, no exhaust gas, in line with global environmental protection requirements.
High thermal conductivity plastic heat sink internal PLA molecules are densely packed with nanoscale metal ions, which can move quickly at high temperatures to increase the thermal radiation energy. Its vitality is better than the metal material heat sink. High thermal conductivity plastic heat sink high-temperature resistance, 150 ℃ for five hours without rupture, no deformation, with high-voltage linear constant current IC drive program applications, without electrolytic capacitors and large volume inductors, significantly improve the life of the LED whole lamp, non-isolated power supply program, high efficiency, low cost. Especially suitable for fluorescent tubes, and high-power industrial and mining lamps.
High thermal conductivity plastic heat sink can be designed with a lot of precision heat sink wings, the heat sink wings can be made very thin, the heat sink area is maximized, the heat sink wings work automatically form air convection-diffusion of heat, heat dissipation effect is better. the heat of the LED lamp beads through the high thermal conductivity plastic directly to the heat sink wings, through the air convection and surface radiation to quickly dissipate heat.
High thermal conductivity plastic radiator density is lighter than aluminum. Aluminum density is 2700kg/m3, while the density of plastic is 1420kg/m3, almost half of aluminum, so the same shape as the radiator, plastic radiator weight is only 1/2 of the aluminum. and processing is simple, its molding cycle can be shortened by 20-50%, which also reduces the cost of power.
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