Study On Preparation And Performance Of Aluminum Substrate For Heat Dissipation Of High-power LED

As an excellent semiconductor optoelectronic device, LED(Light Emitting Diode) have advantages like small size, low electricity consuming, long lifetime, and environmental protecting, it will hopefully becomes a new generation of ideal solid-state light sourse in the coming ten to twenty years.With the development towards to high lumens and high power, the problem of heat dissipation for high-power LED becomes more and more important. As the effect of heat dissipation influence the light output character of LED and its lifetime, the problem of heat dissipation becomes a critical problem in the packaging of the high-power LED.Aiming at the heat dissipation problem of high-power LED, insulated aluminum substrate used for LED packaging is prefered to research in this paper. Firstly, the method of AlN/Al substrate prepared by magnetron sputtering or Al2O3/Al substrate prepared by anodic oxidation and electrode preparing method of electroless copper plating or copper plating by sputtering are explored, and then the method of anodized aluminum substrate and copper electrode prepared by magnetron sputtering are chosen for preparing Aluminum substrate, and the cooling effect of applying it onto the LED is observed finally.Optimized technological parameter of anodized aluminum substrate is searched by Orthogonal Experimental design, and the thermal, electrical, and mechanical performence is tested and analysed, the results indicate that: the thermal resistance of anodized aluminum substrate is in inverse ratio to thickness of anodized oxidation film approximately, and besides it is effected by porosity; the lower the current density is, the lower the sulfuric acid concentration is, the shorter the oxidation time is, the thinner the oxidation film is, so is the thermal resistance; the higher the temperature is, the thinner the film is, but the porosity is higher as the temperature grows high, so the thermal resistance is lowest at 15℃. The thermal resistence is lowest when the current density is 2 A/dm2, the temperature is 15℃,concentration of H2SO4 is 160g/L, oxidation time is 15min, and the thermal resistences of anodized substrates have basically achieved GJB1651 criterion; the insulation resistivities of anodized aluminum substrates are higher than 1011?·m; the adhesive force of the anodized aluminum substrate between oxidation film and aluminum is 14.5N, which is better than the aluminum substrate of Shenzhen dazheng technology Co., Ltd. The anodized aluminum substrate is applied in 1W, 3W, 5W LED of red, blue, green in each power level, in total 9 kinds of LEDs, it is found that the temperature of the green LEDs rises the fastest; comparing with the current aluminum substrate product, the temperature rise rate and the steady temperature of 1W, 3W blue LED with the self-made aluminum substrate are lower obviously, and those of 5W LEDs of three colors with the self-made aluminum substrate are much lower obviously. The test results show that the effect of heat dissipation of the self-made aluminum is better than the current aluminum substrate product, and the anodized aluminum substrate is hopefully applied in high power LEDs of 5W level.Heat pipe heat dissipation technology and semiconductor cooling technology are explored in preliminary in addition, heat pipe technology can make the junction temperature of the 5W LED down to 32.8℃, the temperature rise is only 7.8℃; the structure of semiconductor cooling plate with heat pipe under it can make the junction temperature of the 5W LED down to 29℃, the temperature rise is merely 4℃, which reduced the failure probability of high power LED dramatically.