Fabrication And Properties Of Alumina/copper Heat Dissipation Substrate Applied To High Power LED

With the rapid development of high power LED,the heat dissipation substrates with high radiating performance and low thermal expansion properties were required.Metal/ceramic composite materials ideally combined the high thermal conductivity of metal with low coefficients of thermal expansion of ceramic,getting excellent comprehensive performance.Al₂O₃/Cu composite materials were prepared by two steps in this experiment: firstly,Al₂O₃ ceramic substrates with highly aligned pore structure were prepared by freeze-tape-casting,secondly,Cu were infiltrated into the pore of Al₂O₃ ceramic substrates by vacuum pressureless infiltration.Surface chemical copper plating and adding the active element Ti were used to improve the wettability between Al₂O₃ and Cu.The parameters of pressureless infiltration process such as infiltration temperature and holding time were optimized by Cu infiltration rate.The microstructure and element distribution of composites were also characterized.The thermal conductivity,coefficient of thermal expansion and the heat dissipation performance in LED of composite materials were tested.The results show that:?1?The porosity of Al₂O₃ porous ceramic substrates with highly aligned pore structure gradually decreased with the increasing of solid content and the pore size gradually decreased with the decreasing of freezing temperature.?2?The surface copper plating treatment had no significant effect on improving the wettability between Al₂O₃ and Cu,but the adding of active element Ti to Al₂O₃ substrates,which involved in reaction with Al₂O₃ at the Al₂O₃/Cu interface and formation of Cu3TiO4,could reduce the contact angle of Al₂O₃ and Cu,thus enhancing the wettability.And increaseding Ti content,improving the temperature,extending the holding time,could promote the Cu infiltration rate.?3?With the increasing of Al₂O₃ content,the thermal conductivity and thermal expansion coefficient of Al₂O₃/Cu composites decreased.The composite materials were used as heat dissipation substrate in the LED can reduce the LED junction temperature,the thermal resistance of the composites increased with the increasing of Cu infiltration rate.