热处理对氮化铝化学镀铜组织性能的影响

目的优化化学镀铜氮化铝(AlN)基板的综合性能,掌握热处理对其镀层致密度、界面结合强度和热导率的作用机理,并对划痕膜层失效行为进行分析。方法采用化学镀铜法实现AlN陶瓷基板表面金属化,对其进行200~500℃热处理。利用X射线衍射仪、扫描电镜、激光导热仪,对Cu-AlN基板的物相结构、显微形貌、热学性能进行分析。采用划痕法对镀层结合力进行评价,并通过划痕形貌对膜层失效行为进行分析。结果未热处理的Cu-AlN基板表面存在鼓泡现象,结合强度为24.7 N,热导率为156.8 W/(m K)。热处理消除了Cu-AlN基板的鼓泡现象,300℃热处理的Cu-AlN基板综合性能优异,表面Cu颗粒分布均匀,结构较为致密,结合强度为32.6 N,热导率达163.8 W/(m K);当500℃热处理时,Cu-AlN基板表面存在氧化现象,形成CuO,结合强度急剧降低为18.5 N,热导率为161.2 W/(m K)。Cu-AlN基板的基膜失效方式为点剥离,随着载荷的增加,点剥离增多,膜层开裂,AlN逐渐裸露,Cu膜层磨损形貌宏观上表现为由塑性变形引起的犁沟磨损,芯部发生拉伸变形,边界呈现卷曲变形。结论对Cu-AlN进行合理热处理,可改善镀层表面组织与致密度,提高结合强度和导热性能。

Influence of Heat Treatment on the Microstructure and Properties of Electroless Copper Plating on AlN Substrate

The work aims to optimize the comprehensive performance of electroless copper-plated aluminum nitride(AlN)substrate,master the effect of heat treatment on its coating density,interfacial bonding strength and thermal conductivity,and analyze the failure of scratching layer.The surface of AlN substrate was metallized by electroless copper plating and treated thermally at 300~500℃.The phase,microstructure and thermal properties of the Cu-AlN substrate were analyzed by X-ray diffraction(XRD),scanning electron microscope(SEM)and laser thermal conductivity measurement.The adhesion of the coating was investigated by the scratch method,and the failure behavior of the coating was analyzed by the scratch morphology.The surface of the Cu-AlN substrate not treated thermally was bubbling with a bonding strength of 24.7 N and a thermal conductivity of 156.8 W/(m·K).The heat treatment eliminated the bubbling phenomenon of the Cu-AlN substrate.The Cu-AlN substrate treated thermally at 300℃had excellent comprehensive properties with uniform distribution of Cu particles on the surface.The microstructure was relatively compacted with 32.6 N bonding strength and 163.8 W/(m·K)thermal conductivity.The surface of the Cu-AlN substrate treated thermally at 500℃was oxidized to form CuO,and the bonding strength was sharply reduced to 18.5 N with 161.2 W/(m·K)thermal conductivity.The failure mode of Cu-AlN substrate was point peeling.With increasing scratch loading,the point peeling increased,the Cu coating cracked and the AlN base layer appeared to gradually expose.The macroscopic failure of Cu coating exhibited plough trenches caused by plastic deformation.The core of the wear profile was stretched and the boundary was crimped.The reasonable heat treatment of Cu-AlN can optimize its surface microstructure and density of the coating,resulting in the improvement of the bonding strength and thermal conductivity.