Fabrication And Properties Of Metal/alumina Composite Heat Dissipation Substrate

The LED lamp has advantages of energy saving and environmental protection,it has been widely used.However,LED’s development is limited due to the heat radiation problem,especially the high power LED components.One of the solutions to the problem of heat dissipation is the choice of packaging materials.The packaging material with good heat dissipation is beneficial to the export of LED chip heat.The substrate packaging materials shall have thermal expansion coefficient matched with chip,electrical insulation,and satisfy the high thermal conductivity.Alumina ceramics cannot fully meet the requirements.However,the metal-alumina composite substrate not only meet the requirements of thermal expansion coefficient and electrical insulation but also increase thermal conductivity combining with the characteristics of the metal itself,improving the heat dissipation capability.Thermally conductive chains are formed because of the addition of high thermal conductivity,which to improve the thermal conductivity and heat dissipation capability of materials.It is accord with the requirements of miniaturization and high power of electronic devices.Metal alumina composite radiating substrate was prepared by combining the tape casting and vacuum sintering process.Also study on its thermal density,conductivity,bending strength.In addition,The breakdown strength and heat dissipation performance of several kinds of substrates were evaluated.The results of the study are as follows:（1）The thermal conductivity of Ni-Al₂O₃ composite substrate is higher than that of other Me-Al₂O₃ composite substrates.The thermal conductivity,density,bending strength of Ni-Al₂O₃ composite are higher than Al₂O₃ substrate.The thermal conductivity and density of the Ni-Al₂O₃ composite substrate are increased gradually in nickel content of 0vol.%-10 vol.%;However,the thermal conductivity and density of Ni-Al₂O₃ composite substrate decreased gradually in nickel content of 10 vol.%-15 vol.%.For gradient Ni-Al₂O₃ composite substrate,the thermal conductivity of the gradient 5vol.%-10 vol.%-15 vol.%-10 vol.%-5vol.% composite substrate is the largest.（2）The thermal conductivity of Ni_F-Al₂O₃ composite substrate is higher than Al₂O₃ substrate.When the nickel content is 10 vol.%,the thermal conductivity of the 5mm Ni_F-Ni-Al₂O₃ composite substrate is largest.And it is higher than Ni-Al₂O₃ composite substrate in the thermal conductivity and bending strength.（3）Under the condition of the same power LED and the same array of LED,through the ANSYS simulation of several composite substrates,the heat dissipation performance of the composite substrate is as follows:Ni_F-Ni-Al₂O₃ composite substrate>Ni-Al₂O₃ composite substrate gradient Ni-Al₂O₃ composite substrate Al₂O₃ substrate.（4）The breakdown voltage of several kinds of substrate conform to the provisions.Heat dissipation capability of composite substrates were characterized by junction temperature,temperature rise and the system thermal resistance,the heat dissipation capability is: Ni_F-Ni-Al₂O₃ composite substrate Ni-Al₂O₃ composite substrate gradient Ni-Al₂O₃ composite substrate Al₂O₃ substrate.It is beneficial to improve the heat dissipation capability of substrate,adding metal powder or metal fiber.