The Analysis Of 8W White MCM-LED

High power LED is the representative of semiconductor illumination and its $/Lumen is becoming lower and lower. Thus it can be expected soon that high power LED will become the fourth generation lighting source replacing incandescent, fluorescent and high intensity discharge lamp. An important way to get high power white LED is based on multi-chips integrated, namely MCM-LED. For the high power density of MCM-LED and the low conversion rate of electricity-photo, thermal challenges must be resolved. This thesis focus on the thermal analysis of a kind of 8W white LED multi-chips module which is used as road lamp. We study the problems such as junction temperature, thermal resistance, thermal coupling and thermal filed distribution by three ways: theoretic analysis, simulation and experimentation.Fist, we discussed the produce of thermal, the character of thermal in LED and the thermal management. Meanwhile, MCM-LED is brought forward and its thermal problem is introduced. Then the methods that are used to analyze thermal problem are discussed, especially the ANSYS FE software. We established a thermal model for our object. Inner thermal resistance is 0.214K/W, the outer is 2.407K/W and the total is 2.621K/W.The fin efficiency of the heat sink is 0.92.Heat distribution of the package at steady condition is showed by simulating. We get the result of thermal resistance, heat flow density vector and temperature grads. Inner resistance is 0.269K/W, which is closed to the result that theoretic analyzed. The influence of die bonding materials and technology on LED thermal are stressed. Simulating at various conditions, we get the relation of thermal resistance and the thermal conductive of die bonding materials by fit hypothesis, finding that the relation is reciprocal. The limit of the inner resistance is 0.238K/W .Meanwhile, we find that pursing high conductive die bonding blindly is not a wise action. Different temperature between chips and thermal coupling are studied. Choosing a right die bonding material is favorable for resistance cutting and thermal coupling decreasing. Finally, as a try, we simulated the whole system, heat sink included.At the end of this paper, a simple experiment to test the temperature is carried out and the results are compared with that of simulation. We conclude an indicative method to deal with the thermal in MCM-LED: get a character temperature by a simple method, then combined it with the relations that concluded by simulating, at last, junction temperature and thermal resistance are gained.