Preparation Of High-power LED Aluminum Ceramic Heat Dissipation Substrate

In the paper, different metal(Ti, Al, Ti/Al) transition layer and Cu are grown on AIN ceramic by vacuum evaporation and DC magnetron sputtering, and realizes the metalized on the surface of AIN ceramic substrate. The high thermal conductivity AIN substrate that we obtain can be used in the LED package. The microstructure and composition of the surface and section of specimens are observed and analyzed by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The phase structure of samples are analyzed by X-ray diffraction(XRD). The electrical performance is tested and analyzed by four-point probe; the thermal performance is tested and analyzed by forward voltage method. The results show:1) The transition metal layer promotes the wetting between Cu and AlN surface, and increases the density of the metal layer of substrate. The density is proportional to the number of metal interlayer. If there is the same number of metal interlayer, the density is inversely proportional to metal’s atomic radius.2) There are different bonding mechanisms between the transition metal layer and AlN. Bonding mechanisms between Ti and AlN is chemical bonding, and the reaction products are TiN and Al3Ti.Bonding mechanisms between Al or Cu and AIN is physical bonding.3) In these substrates, the resistivity of the Cu/Al/AIN substrate is the lowest (ρcu/Al/AlN≈1.7×10-7Ω·m), and thermal conductivity is better than several other substrates. According to all properties, Cu/Al/AlN substrate is optimal in these substrates.In addition, the paper uses wet etching method to prepare LED-samples to meet the conditions of secondary ion mass spectrometry(SIMS) test sample. A single LED can’t be directly tested by SIMS, because its size is too small and covered by layers of different materials. After doing some experiments, we obtain the sample preparation conditions, and also to meet the special requirements of the SIMS test.