Electrodeposition of Ni–B Alloy Film: Effect of Current Density and Heat Treatment on Micro-Mechanical Property

Abstract

Ni–B alloy films are prepared by electrodeposition with a Watt’s bath-based electrolyte. The B content decreases from 14.3 at% to 2.8 at% as the current density increases from 1 A dm−2 to 4 A dm−2. For applications in miniaturized electronics, the micro-scale mechanical property is evaluated by micro-compression test using micro-pillar type specimens. As-deposited Ni–B alloy films exhibit high mechanical strengths and ductility. The Ni–B alloy films are heat treated to evaluate the thermal stability. After the heat treatment, strengthening and formation of an intermetallic compound, Ni3B, are confirmed. The deformation behavior of the micro-pillars changes from ductile to brittle after the 250 °C heat treatment, and the compressive strength of the Ni–B alloy film having the B content of 2.8 at% reaches 5.52 GPa due to the precipitation strengthening mechanism by the Ni3B.