The bonding strength of deposited metallic films or strips on a hard substrate is investigated through micro-strength tests and micro-mechanics analyses. The combination of Ti:W-Au/Cu deposited directly on SiO2/Si substrate was taken as an example in the experiments conducted. Investigations and analyses resulted in a general model concerning the separation mechanism of thin ductile films from a hard brittle substrate. This separation model leads to some systematic methods of improving strip-substrate interconnection strength. Instead of strip-substrate adhesion, strip stiffness turns out to be a key factor for the bonding strength of such a system. Hardening processes such as post-deposition heat treatment and work-hardening are effective in strengthening the strips. These investigations also reveal a fundamental principle of mechanical compatibility concerning interface micro-deformation. This new understanding will help to improve common bonding strength problems of various interconnection structures and materials combinations in manufacturing technologies.