AlN/Cu复合导热基板的界面结合特性及显微结构

Interface Bonding Properties and Microstructure of AlN/Cu Composite Substrate

对热压法与直接敷铜(direct bonded copper,DBC)法制备的2种不同界面状态的AlN/Cu基板进行了物相、形貌和成分及结合力(剥离强度)测试。结果表明:热压法所得复合基板在AlN陶瓷表面有一层约2μm厚的Ti中间层,Ti不仅能与AlN反应生成Ti_2N与Ti_9Al_(23),又能与Cu形成Cu_4Ti_3合金,且Ti与AlN的结合力低于Ti与Cu的结合力;DBC法在AlN陶瓷表面氧化形成一层约2μm厚的Al_2O_3层,Al_2O_3与Cu–O通过共晶液相反应形成CuAlO_2,达到牢固结合,但由于Al_2O_3与AlN的热膨胀系数不匹配,Al_2O_3与AlN的结合力低于Al_2O_3与Cu的结合力;采用DBC法制备的AlN/Cu基板剥离强度(7.94 N/mm)较热压法(2.03 N/mm)高,约是热压法的4倍,且在使用过程中不易失效,适合于苛刻使用条件下的长期应用。

AlN/Cu thermal conductive substrates were prepared via a hot-pressing method and a direct bonded copper （DBC） method,respectively. The crystal phase, morphology, composition and interface bonding （peel strength test） were characterized. The results show that in the hot -pressing method, there is a Ti layer with a thickness of 2 μm on the surface of AlN, Ti can react with AlN to generate Ti2N and Ti9Al23 and then react with Cu to generate Cu4Ti3 alloy. The adhesion strength between Ti and AlN is lower than that between Ti and Cu. In the DBC method, AlN is oxidized to form an Al2O3 layer with a thickness of 2 μm. The Al2O3 layer reacts with Cu-O eutectic liquid to generate CuAlO2, forming the strong combination. However, the bonding strength of Al2O3 and AlN is lower than that of Al2O3 and Cu due to the mismatch of thermal expansion between Al2O3 and AlN. AlN/Cu composite substrate prepared by the DBC method presents a peeling strength of 7.94 N/mm, which is approximately 4 times greater than that by the hot-pressing method （i.e., 2.03 N/mm） and is more suitable for the prolonged use.