Analysis of heat dissipation of LED automobile headlights

For a long time, the LED heat problem has plagued the whole industry, and in the face of a high growth car headlamp market, I don't want to miss it. Next, we will discuss how to overcome the heat dissipation problem in the small space of the headlamp, so as to achieve the national standard of the lamp at the ambient temperature of 50 ℃, and the higher junction temperature can not exceed 80 ℃.

At present, the design power of automobile low beam and high beam lamps is concentrated between 40 ~ 60W, while the automobile reaches more than 80W. In addition, the heat energy generated under high power, such as side marker lamp and direction lamp, is not easy to exceed 80 ℃, so it will be a difficult problem for engineers to solve the problem of heat dissipation.

Heat and space are inseparable. Under the condition of large space, you can choose a cheaper heat dissipation solution. For example, the street lamp can be easily solved by increasing the heat dissipation aluminum seat, but if the mobile phone is increased, no one may want it. If it is not solved, it will be like holding a hot potato. Therefore, the artificial graphite heat sink is used to disperse the heat to form a heat source and homogenize the surrounding temperature.

With the concept of space, we can understand the heat source and the required upper limit temperature. The heat source transmits the temperature to the surface and then to the gas through solid heat conduction. The gas convection is slow and passive, so it is particularly important to solve the overall packaging material and heat source first.

It is well known that led chips are converted from electricity to light. Generally, the efficiency is only 30%, and the other 70% become heat. If the heat is not dissipated in time, the light efficiency will be reduced. The CSP structure adopted by automobile headlights is related to the number of watts and the amount of heat generated; Second, the thermal conductivity of upper and lower materials, which affects the overall temperature uniformity; The thickness of these materials is three. Table 1 shows the thermal conductivity of various materials. With these concepts, we can start to solve the problem of heat dissipation.