含曲线型膜基界面的高分子基金属薄膜延展性能

DUCTILITY OF POLYMER-SUPPORTED METAL FILMS WITH CURVED INTERFACES

柔性电子系统中联接电子元器件的互联金属导线多以附着在高分子基底上的薄膜形式存在.该文首先实验研究了在含糙化表面的聚酰亚胺基底上附着Cu膜的延展性能,结果显示,提高基底表面粗糙度能够显著降低Cu膜在拉伸条件下的裂纹密度.然后采用有限元方法模拟计算了基底表面糙化处理后,金属薄膜在拉伸状态下的应力分布,结果表明曲线型界面可显著改变金属薄膜在拉伸状态下的表面正应力分布,从而达到抑制金属表面裂纹的扩展以及降低裂纹密度的作用.最后,采用内聚力模型模拟膜基界面,研究了在拉伸条件下曲线型界面的损伤分布情况.结果表明,相对于平直界面,曲线型界面不易发生界面破坏.

Electronic components in modern flexible electronics are connected by interconnects, having typically the form of metal films on polymer substrates. Firstly, this paper studies experimentally the ductility of a polyimide-supported Cu film with rough interface （due to sandblasting treatment） and show that, upon tensile loading along the direction of film surface, the density of surface cracks can be reduced by increasing the substrate surface roughness. The distribution of tensile stresses in the film and their effects on film cracking （initiation and propagation） are subsequently studied using the method of finite el- ements. It is found that a rough （curved） interface can reduce the tensile stresses along the film surface so as to restrain the cracking of the film. Finally, we employ the cohesive zone model to study the initiation and spreading of damage in the film and interracial cracking of the curved interface. It is demonstrated that both the damage and length of interracial crack are reduced due to interface roughening.