微尺度金属薄膜屈曲稳定性的实验研究

Experimental Study of Buckling Instability of Micro-Scale Metal Thin Film

微尺度金属薄膜的脱粘和屈曲严重影响着膜基结构的性能和使用寿命。本文对微尺度的金属铜薄膜在残余应力和外部压力共同作用下的脱粘屈曲和后屈曲模式进行了研究,用自行设计的单轴对称加载装置进行压力加载,用一台光学显微镜观察薄膜表面的屈曲形貌。在外力作用下薄膜会出现垂直于加载方向的直线型屈曲,但在外力卸载过程中该屈曲并不稳定,会演化成电话线型屈曲,完全卸载后形成泡状屈曲。再次加载后,恢复到直线型屈曲。研究表明:直线型屈曲的不稳定现象主要与薄膜的残余应力、基底的泊松比以及薄膜沿纵向与横向的应力比有关。

Performance and service life of membrane-based structure are severely affected by buckling and debonding of micro-scale metal thin film.Debonding buckling and post-buckling mode of micro-scale metallic copper thin film subjected to combined actions of residual stress and external compression were experimentally studied.The pressure loading is achieved based on a self-designed uniaxial symmetrical loading device;the film surface buckling morphology is observed by an optical microscope.Thin film may produce straight-line type buckling along the direction perpendicular to external force loading.However,during the unloading process,the straight-line type buckling becomes unstable and evolves first into telephone-code type buckling,then into bubble type buckling after completely unloading.After loading again,the buckling returns to straight-line type.Results indicate that the instability of straight-line type buckling is related with the film residual stress,Poisson’s ratio of substrate and the stress ratio of longitudinal component and transversal component.