Study On Ceramic Copper Cladding Based On High Power LED

High-power LED is a very promising green technology in the world.According to the "2017 Global Sapphire and LED chip market report",in 2016,the global LED chip market size has been more than 44.7 billion yuan.However,with the power growing,the heat problem has become a major problem plaguing the industry,hindering the development of LED lighting technology.At present,to solve the LED's heat problem,it is a great aspect to find the right material as a cooling substrate.Alumina ceramics is currently the most widely used ceramic substrate material,while aluminum nitride ceramic has a high thermal conductivity,low dielectric constant,excellent chemical properties and other advantages,is expected to become the mainstream in the future substrate materials.The main goal of this project is to propose a new process idea on the basis of the existing magnetron sputtering metallization method,to find a new metallization process for alumina ceramics,at the same time the metallization process of aluminum nitride ceramics technology has been studied and discussed.The following results are obtained:(1)The thermal characteristics of the high power LEDs are analyzed theoretically,and the heat dissipation model of the LED is established.The thermal steady state simulation is also carried out by the large-scale finite element analysis software ANSYS.It is proved that aluminum nitride ceramic substrate has obvious heat dissipating advantages compared with alumina ceramic substrate and epoxy resin substrate,and alumina ceramic substrate has certain use value under middle and small power LED.(2)A new technique of preparing alumina-based copper clad laminate is proposed.Firstly,low-pressure and high-energy sputter deposition of the bottom copper layer,and then high-pressure sputtering deposited thicker copper layer.XPS and other analytical tests show that the initial deposition of the bottom copper layer and the ceramic interface there is a clear electron exchange.A layer of copper oxide transition layer is formed.It is this transition layer whom matches the metal and ceramic,and greatly improved the copper layer and ceramic bonding strength,while the deposition of high pressure copper layer fine grain dense arrangement lead to low resistivity.The results show that the thermal resistance of the alumina-based copper clad laminate is 1.38?/W,and the pull-off strength is 6.2MPa,which is better than that of the commercially available DBC board of 1.880C/W and 2.4MPa.Lithography lines clear,compatible with conventional lithography process.This process provides a new method for the preparation of ceramic copper clad laminate,which has great value and industrialization prospects.(3)Aluminum nitride ceramic with high thermal conductivity,good chemical stability and other advantages,is the future of high thermal conductivity ceramic CCL ideal material.But its metallization problem has not been resolved,seriously hampered its application.This paper systematically studies the metallization process of aluminum nitride ceramics,and proposes a new process for laser re-metallization of activated surface and has successfully applied for related patents.The results show that the thermal resistance of the alumina-based CCL is only 0.25?/W,the pull-off strength of the copper layer is 4.2MPa,and the conventional lithography process can be used without the need of secondary lithography fine lines,which for the aluminum nitride ceramic CCL in the field of high thermal conductivity to promote the application of laying a good foundation.