Research On Preparation And Performance Of Conductive Silicone Rubber For High-power LED Heat Dissipation

In this article，we studied the LED heat dissipation problem by applying theconductive silicone rubber to LED. The mechanism of conductive silicone rubber andthe effect of surface treatment on the thermal conductivity have been researched, what’smore, under the guidance of the theory we have prepared some kinds of conductivesilicone rubber, such as Al2O3and AlN conductive silicone rubber under Silanecoupling agent surface treatment,various grease thermal (including Graphite, AlN, Cu,Al2O3, Al), various filler sizes of conductive rubber and the binary mixture filledconductive silicone rubber. By researching the effects of surface treatment craft on thethermal conductivity, surface managment of the filler, the filler type, and the amount ofreinforcing agent, filler loading, particle size in the pure grease thermal and the mainfiller, radiating filler of conductive silicone rubber on the binary mixture conductivesilicone rubber, the following conclusions:①After the thermal conductivity of thermally conductive silicone rubber surfacetreated filler material is higher than the overall surface without reasonable andλλAl>λAlN>λC> λCu>λAl2O3, Al conductive silicone rubber has a highest thermalconductivity that reaching0.52W/(m K), Al2O3conductive silicone rubber hasminimum0.36W/(m K). Description of the surface treatment of the filler increases thedegree of compatibility and bonding between the thermally conductive filler and thesilicone rubber matrix, which is contributing to the thermal conductivity of the mixedmaterial;②The amount of fumed silica reinforcing agent reinforce the silicone rubberbeneficial activity, and it can improve the thermal conductivity of silicone rubber;③The thermal conductivity of silicone rubber increeeases with the increasingamount of the thermal conductive filler. The thermal conductivity of silicone rubberfilled with AlN is preferable to that of the filler of Al2O3when the two fillers wereadded at the sanme amount. At the low amount of the filler, the thermal conductivity ofthe mixed rubber is dominated by the stacking morphology of the particle in the system,whereas at the large amount of the filler, the thermal conductivity of the mixed rubber isdetermined by both of the accumulating morphology of the particles and the thermalconductivity of thermal particles themselves in the system;④The relationship between the thermal conductivity of Al thermal conductive silicone rubber with grain diameter and the particle size shows:The particle size have agreat influence on the thermal conductivity. When the Al particle size is50μm, thehighest thermal conductivity is0.70W/(m K);⑤In systerm of thermal conductive the binary mixture silicone rubber, thethermal conductive silicone rubber prepared by the Al (50μm) filled with thereinforcingfillerof Al (1μm) particle has a high thermal conductivity of0.63W/(m K). When twokinds of filler particles with different diameter are mixedand filled into the thermalconductive silicone rubber, the thermal conductivity of silicone rubber increases withthe increasing proportion of the grain diameter of the larg partical and small particalwithin the scope of the study;⑥When the thermal silicone grease was applied for1W,3W,5W LED lamp, theactual results of heat dissipation show: the junction temperature of the LEDencapsulated by the conductive silicone rubber which is filled with AlN is slightly lowerthan that of the LED encapsulated by market products of cooling pad purchased byShenzhen Hong company,and the minimum temperature difference is only2.3℃. On thecondition of high temperature, the thermal stability of LED encapsulated by theconductive silicone rubber which is filled with AlN is better and the thermal resistanceof it is with a great dicrepence than that of the market products, whereas when the LEDis at high temperature, the thermal resistance of the LED managed with ourexperimental products and market products is almost no difference, so the experimentalproducts can meet the market’s demands;⑦The LED temperature field simulation is discussed with the help ofmulti-physics simulation software, the simulation results consistent with theexperimental measured junction temperature, substrate temperature, the basiccompliance, reflecting the multi-physics simulation in the thermal simulation of LEDpracticality.This thesis is to provide research basis for the high-brightness lighting LED heatdissipation material, device and package, and the results promote the development ofhigh-brightness LED to save energy, protect the environment, reduce costs, increaselamp life effectively.