Relationship between Current Density, Crystal Grain Size, Composition and Hardness in Electrodeposited Ni-Co Alloys

摘要

Nickel, cobalt, and their alloys are important engineering materials in many applications because of theirunique properties, such as magnetic, heat-conductive and high hardness. Their alloy films have attractedmuch attention and are widely used in micro-electrical-mechanical systems (MEMS) devices due toexcellent electrical and mechanical properties. Pure Ni films are known for high hardness property, and themechanical strength can be further improved by solid solution strengthening. Electroplating (EP) is oftenused in preparation of Ni-Co alloy films because the morphology, crystal structure, and deposition rate ofthe deposited materials can be facilely controlled by varying the EP parameters [1], such as the currentdensity, bath composition, and temperature [2]. Reliability of electronic components is highly dependent onthe mechanical property, which is closely related to its average grain size according to the Hall-Petchrelationship [3]. Therefore, in this study, the effects of applied current density on average grain size,Vickers hardness, and micro-mechanical properties of electrodepositedNi-Co films are evaluated for fabrication of micro-components inelectronic devices.