AlN陶瓷/Cu异质材料低温过渡液相扩散连接

AlN ceramic/Cu heterogeneous materials low-temperature transition liquid phase diffusion bonding

为了实现AlN陶瓷与Cu的低温连接、高温服役的目标,满足高温功率器件的服役需求,设计了一种连接方法,在350℃的大气环境下采用超声辅助熔焊的方式在AlN陶瓷表面熔覆了Sn-Al-Cu活性钎料层,之后将熔覆活性钎料的AlN陶瓷与Cu在保温温度300℃下进行过渡液相(transient liquid phase,TLP)扩散连接;利用扫描电子显微镜、能谱仪以及透射电子显微镜对显微组织及相结构进行分析;采用万能材料试验机对试样进行力学性能测试.结果表明,熔覆时间180 s时的活性钎料与AlN陶瓷实现了良好的结合,在AlN陶瓷/活性钎料界面处观察到一层由超声作用下吸附在AlN陶瓷表面的Al被氧化,并在较大的过冷度下形成厚度约为20 nm的非晶Al;O;层;保温时间60 min时焊缝中的Sn全部转变为Cu;Sn与Cu6Sn5;保温时间为240 min时形成焊缝全部由Cu;Sn构成的接头.AlN陶瓷/Cu接头抗剪强度随保温时间的延长而下降,全部由Cu;Sn构成的接头的抗剪强度约为31 MPa,断裂发生在Cu;Sn/AlN陶瓷界面处,形成了全金属间化合物的AlN陶瓷/Cu接头.

A connection method is designed to connect AlN ceramic and Cu at low-temperature while used in high-temperature environment in high-temperature power devices.The SnAl-Cu active solder layer was plated on the surface of AlN ceramic by ultrasonic-assisted fusion welding in the atmospheric environment of 350℃,and then the Al N ceramic coated with active solder and Cu were connected by transition liquid phase diffusion bonding at holding temperature 300℃.The microstructure and phase structure were analyzed by scanning electron microscope,energy spectrometer and transmission electron microscope.The mechanical properties of the samples were tested by universal mechanical testing machine.The results show that the active solder and AlN ceramic have achieved good bonding when the cladding time is 180 s.A layer of Al adsorbed on the surface of Al N ceramic under the action of ultrasound is observed to be oxidized at the Al N ceramic/active solder interface,and the amorphous Al;O;layer with a thickness of about 20 nm is formed under large undercooling degree.When the holding time is 60 min,all the Sn in the weld is transformed into Cu;Sn and Cu;Sn;when the holding time is240 min,the interconnected joints in which all the welds are composed of Cu;Sn are formed.The shear strength of Al N ceramic/Cu decreases with the prolongation of holding time.The shear strength of the all-Cu;Sn joint is about 31 MPa.The fracture occurs at the Cu;Sn/Al N interface,forming an all-intermetallic Al N ceramic/Cu interconnection joint.