A study on Nano-mechanical properties and nano-tribology for ultra-thin Pt-coated 4N copper wire

Electronic Submission Nano-mechanical properties of ultra-thin copper wire (ψ =0.6mil) and nano-tribology along the interfacial between free air ball (FAB) and aluminum bond pad were carefully investigated in this paper. For comparison, commercial product Pt-coated 99.99% (4N) Cu wire and pure 4N Cu wire are selected as test materials. Bonding temperature effects were taken into account for all case studies. Tensile mechanical properties were conducted through self-designed wire pull test fixture. Nono-indentation instrument was applied to obtained thin surface elastic modulus on FAB. Nanotribology and interfacial frictional behavior along smashed FAB and bond pad were measured by Atomic Force Microscopy (AFM). AFM force-displacement curve is utilized to determine the nanotribology properties. The interfacial coefficient of frictional force can be derived from a serial of calculations. A well-defined contact area is measured to study the frictional force and friction stress. The roughness of contact surface influences the contact between friction and surface forces. The study of roughness parameters corresponds to evaluate the friction and the interfacial strengths. Local variation in micro/nano tribology is also measured.