A method for probing the effects of conformal nanoscale coatings on fatigue crack initiation in electroplated Ni films

作者：Straub T; Baumert E K; Eberl C; Pierron O N^*

来源：Thin Solid Films, 2012, 526: 176-182.

DOI：10.1016/j.tsf.2012.11.011

• Fatigue
• Atomic layer deposition
• LIGA
• Nickel
• Alumina
• Thin films

This paper describes an experimental technique to identify robust nanoscale coatings for improving the long-term reliability of metallic microelectromechanical systems. More specifically, the influence of nanoscale alumina coatings on the fatigue crack initiation process in 20 mu m thick electrodeposited Ni films was investigated in a mild (30 degrees C, 50% RH) and harsh (80 degrees C, 90% RH) environment. Atomic-layer-deposited alumina layers, with thicknesses of 5 and 25 nm, were coated on Ni fatigue micro-resonators, and the fatigue degradation behavior in the very high cycle fatigue regime was compared to that of uncoated structures. Evidence based on post-test scanning electron microscopy and resonant frequency evolution plots shows that the coatings do not prevent the formation of fatigue extrusions and micro-cracks. However, their formation is likely delayed for the 25 nm thick alumina-coated Ni films.

• 出版日期2012-12-30