Healing Fatigue Damage Of Copper Film By Laser Irradiation

More recently, the size of micro-components based on metal or silicon substratehas a clear trend to the scale of micron or even nanometer in the microelectro-mechanical system devices. These small size specimens are usually subjectedto cyclic loading in servicing process, so the issues on their failure and reliability arebecoming even more essential.Firstly，in this investigation, the notched specimens with thickness of25μm forpolycrystalline copper film were fabricated by the way of high-precision stampingprocess. The S-N curve of the original specimens was obtained from fatigue test data,and the fatigue properties of copper film were studied through the MMT system.Secondly，the optimal laser parameters will be obtained by the relationship betweenthe laser parameters with no-damaged specimens and damaged degree50%specimensin the fatigue life increasing. The mechanism of the fatigue life increasing is analyzedby comparing the surface microstructure for copper film fracture morphology beforeand after laser irradiation.Thirdly，the opporunity for optimal healing and its mechanism were obtained bythe relationship between healing effect and fatigue damage. The fatigue properties ofcopper film under laser irradiation twice condition was also studied. In order to get thedifference between two conditions about the laser irradiation twice of copper film, wecompared the increased fatigue life under two conditions. The results found that thetotal life of copper film was increased.Finally，the expressions between healing damage degree and fatigue damage aswell as applied stresse were fitted, which were converted to obtain the expression ofresidual life prediction after healing fatigue damage by laser irradiation for copperfilm. The obtain expression of residual life prediction was verified by the copper filmspecimens with different fatigue damage degrees.