High Power LED Thermal Design
Although high-power LED has many advantages such as energy saving and environmental protection, at the same time, because of its high power, a large amount of heat generated is easy to cause the decline of light source because it can not be dissipated in time, and the service life is greatly shortened due to chip overheating, which has been perplexing the engineers of high-power LED lamps.
The thermal management of high-power LED lamps mainly includes three aspects: chip level, packaging level and system integration heat dissipation level. Among them, the chip is the main heating component, its quantum efficiency determines the heating efficiency, and the substrate material determines the outward heat transfer efficiency of the chip; For packaging, packaging structure, material and process directly affect the heat dissipation efficiency; The system integrated heat dissipation level is the so-called external heatsink, which mainly includes aluminum extrusion, heat pipe, fan, vapor chamber, etc.
The main thermal technologies of high-power LED include extrusion heat sink, heat pipe heatsink, vapor chamber , thermal PAD , thermal grease, etc. In the heat dissipation structure design of high-power LED lamps, a good heat conduction channel should be to reduce the thermal resistance between PCB, heat conduction medium and heat sink, increase the effective contact surface between them, select appropriate thermal conductivity and higher heat conduction medium to accelerate the efficiency of heat conduction.
The natural convection heat dissipation mode of high-power LED also requires effective heat dissipation area. Therefore, the heat exchange area of the outer wall of the heat sink shall be appropriately increased. In addition, when spraying different colors of paint, the spraying thickness and the thermal conductivity and thermal radiation performance of this kind of color paint shall be considered. Generally, in order to increase the heat dissipation area of the radiator, we use the fin structure.
The power supply will also generate heat, because the power supply of bulb and spotlight is generally placed inside the lamp cavity. Thermal conductive PAD or thermal grease can be used to cool down the power supply.
In addition, thermal radiation is a kind of heat transfer carried out by all objects at any time, and the radiation intensity of different materials is different. Generally, the radiation intensity of cold objects is lower than that of warm objects, and that of rough objects is greater than that of smooth objects. The radiation heat transfer of bulb and spotlight is small and can be approximately ignored.
From the above introduction, it can be seen that the heat dissipation of high-power LED lamps should not only have reasonable heat dissipation structure design, but also select appropriate heat conduction interface materials for different power, different structures and different lamps.
