Healing fatigue damage by laser shock peening for copper film

• Optimum parameters of LSP are obtained for healing fatigue damage of copper film.
• Two basic mechanisms, enhanced effect and healing effect, are defined.
• Improvement in fatigue life by LSP is analyzed by the enhanced and healing effects.

A repair method for fatigue damage was studied by laser shock peening (LSP) with excimer laser for polycrystalline copper film. Two basic effects were defined. One is the enhanced effect, which improves the fatigue life for the non-damaged specimen by LSP, and the other is the healing effect, which has a further improvement for the damaged specimens. The results showed that, in most cases, LSP has a pure healing effect in addition to an enhanced effect for the damaged specimens. The energy analysis revealed the work hardening due to LSP is the main reason for the improvement of residual fatigue lives for the damaged specimens.