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Analysis of the heat dissipation problem of LED car headlights
2021-04-26 08:56:48
For a long time, LED thermal problems have plagued the entire industry, and in the face of a high-growth car headlight market, I don't want to miss it. Next, we will discuss together how to overcome the heat dissipation problem in the small space of car headlights, and then reach the national standard of car lights at an ambient temperature of 50°C, and the higher junction temperature should not exceed 80°C.
At present, the design power of the low beam and high beam of the car is concentrated between 40~60W, and the car reaches 80W or more, plus the heat energy generated by the high power of the width indicator light, the direction light, etc., think It is not easy to do not exceed 80℃, so it will be a difficult problem for engineers to solve the heat dissipation problem.
Heat and space are inseparable. Under the condition of large space, a cheaper heat dissipation solution can be selected. For example, street lights can be easily solved by increasing the heat dissipation aluminum base, but if the mobile phone is enlarged, no one may want it. If it is not solved, it will be like taking a piece of hot potato, so the artificial graphite heat sink is used to disperse the heat. The peripheral temperature of the heat source is homogenized.
After having the concept of space, we can understand the heating source and the required upper limit temperature. The heat source is to transfer the temperature to the surface through solid heat conduction and then to the gas. The gas convection is slow and passive, so it is particularly important to solve the overall packaging material and heat source first.
Everyone knows that LED chips convert electricity into light. The efficiency is generally only 30%, and the remaining 70% becomes heat. If the heat is not released in time, the light efficiency will decrease. The CSP structure used in car headlights is related to this structure. One is how much heat is generated by the wattage; the second is the thermal conductivity of the upper and lower materials, which affects the overall temperature uniformity; and the third is the thickness of these materials. Table 1 shows the thermal conductivity of various materials. With these concepts, the heat dissipation problem can be solved.