Effects Of Adhesive Layer Composites On Junction Temperature Distribution In The Packing Of LED

Solid state lighting white LED has become a trend with the improvement lightemitting diode(LED) luminous efficiency and high power LED chip successfullymade.Especially with the integration of energy-saving power supply,such as, the futuresolar cells, the white LED will become one of the green solid state lighting choices inthe future.However, the power LED is facing new challenges because of preventingdevice overheating will affect their life and luminous efficiency.Currently, heatdissipation has become the greatest obstacle of LED development.In the high-power LED thermal issues, this paper selected adhesive layer of highpower LED for the study.The first, Using the finite element analysis software COMSOLMetaphysics for1W,2W and3W, respectively, input power LED temperature field toperform simulation.The influence on heat conduction performance of the adhesive layerthickness and adhesive materials on the junction temperature as the focus. Preparationof the boron carbide and alumina epoxy composites, which are based on the mechanismof thermal factors, thermal conductivity, etc., And the thermal conductivity ofcomposites for LED simulation, examine its temperature distribution and junctiontemperature effects.Finally,Comprehensive consideration the thermal conductivity andthe adhesive properties of obtained by simulation and experimental test, get the bestthickness of adhesive layer, the most suitable ratio of adhesive composite materials. Themain contents of the thesis are as follows:①High-power LED thermal finite element simulation to obtain the temperaturedistribution of the LED package, changes in the thickness of the adhesive layer and athermal conductivity of the adhesive material to see their influence on the junctiontemperature. Simulation results show that: LED adhesive layer thickness and thethermal conductivity has a great influence on the junction temperature; With increasingthickness of the adhesive layer, the junction temperature will rise. Increase the thermalconductivity of the adhesive layer, the junction temperature showed slow down after thespeed gradually reduced, when the thermal conductivity increases to a certain value, thejunction temperature will not change.②epoxy resin mixed with micron alumina and boron carbide method to improvethe thermal conductivity and adhesion properties,preparation of the high thermalconductivity of epoxy composites. Using the scanning electron microscope on the surface after ultrasonic treatment of the powders to characterize, the results showed thatultrasonic treatment method can be better dispersed particles. Steady-state thermal testresults show that the thermal conductivity of the composite λincreases as the amount offiller particles is significantly improved.Compared to the thermal conductivity of0.20W/m·Kpure epoxy, if micron boron carbide and alumina mass fraction of50%, thethermal conductivity of the composite material has been greatly improved, they are1.4W/m·K and0.94W/m·K, respectively. Scanning electron microscopy also showed thatthe thermal particles can be well dispersed in the epoxy resin to form a good heatconducting meshand between the particles and the epoxy resin can be combined witheach other, no clear separation.③This article also measured the adhesive layer thickness and particle dopingcontent effect on adhesive properties. The results showed that shear and tensile strengthof aluminum increases with the thickness of the first adhesive layer is increased, thendecreased. Peak appears in the adhesive strength of alumina and boron carbide contentof30~40wt%.④High-power LED seeking the best ratio in the adhesive layer and the bestthickness of the composite material according the results.