The difference between the LED finite element model and its real device in the finite element thermal analysis method is verified by experiments. It is proved that the finite element thermal analysis method is accurate and feasible within the error tolerance. In the simulation, it is assumed that the heat radiated upward through the phosphor and the lens is ignored, and the contact thermal resistance between the packaging processes is not considered.
The maximum temperature of the plastic heat sink without substrate COB package is 297.98K, and the thermal resistance is 5.75K/W. When the thickness of the heat dissipating material is 5 mm, since the thickness of the heat sink is small, the main factor limiting the heat dissipation effect at this time is the size of the natural convection coefficient, although the thermal conductivity of the aluminum heat sink is 237 W/(mK), the plastic heat sink The thermal conductivity is 20W/(mK), but the effect on the junction temperature is also small. The packaging method using the plastic heat sink has the advantages of simpler structure and lower cost production processing technology than the ceramic substrate COB packaging method, and exhibits an absolute advantage.
Further simulations show that when the thermal conductivity of the plastic heat sink continues to increase, the junction temperature will continue to drop, achieving a better heat dissipation effect than the ceramic substrate COB package. However, in general, the electrical conductivity of the material increases with the increase of the thermal conductivity. Therefore, the thermal conductivity of the plastic heat sink is limited by the insulating ability of the plastic heat sink, and cannot be increased indefinitely by filling a heat conductive material such as graphite. A heat-conducting plastic with a thermal conductivity of about 10 to 20 W/(mK) can meet the heat dissipation requirements. Discussion on the factors affecting the heat dissipation effect of plastic radiators The main factors affecting the heat dissipation effect of plastic radiators are the thermal conductivity of plastic radiators, the convection coefficient between the surface of the radiator and the air, the thickness of the plastic radiator, and the surface and air of the plastic radiator. The heat sink area of ​​the contact.
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