3:15 PM - 3:30 PM
▲ [25p-E307-8] High Strength Electrodeposited Ni-B alloys and Their Thermal Stability
Keywords:semiconductor
Nickel electrodeposits have been widely applied in miniaturized electronic devices due to excellent magnetic and mechanical properties, but they typically exhibit low thermal stability. They start recrystallizing rapidly and lose their mechanical properties at relatively low temperatures. Poor thermal stability is a major limitation when applying nanocrystalline Ni to MEMS devices. It has been reported that the incorporation of boron significantly enhances the mechanical strength, corrosion resistance and thermal characteristic of Nickel.
Electrodeposition method is widely used in Ni-B alloy deposition. Comparing with the electroless plating, electrodeposition method offers several advantages, such as high deposition rate, uniform distribution of B in the deposit and ease control of the process. In addition, the average grain size and composition can be easily controlled by the electrodeposition condition, such as the current density. Ni-B alloys were prepared by electrodeposition with a Watt’s bath. The B content varied from 2.8 to 14.3 at.% as the current density decreased from 4 to 1 A/dm2. Crystalline structure of the Ni-B alloys was characterized by X-ray diffraction (XRD). Thermal stability test of Ni-B alloys were conducted to evaluate their mechanical performance after heat treatment at 250 °C. The mechanical property in micro-scale were evaluated by micro-compression test using micro-pillar type specimens fabricated by focused ion beam system. B content in the Ni-B alloy deposits reduced and micro-hardness increased as the current density increased as shown in Fig. 1. The compressive strength of the Ni-B alloy having the cobalt content of 3 at.% reached a maximum of 5.67 GPa after 4 h heat treatment.
Electrodeposition method is widely used in Ni-B alloy deposition. Comparing with the electroless plating, electrodeposition method offers several advantages, such as high deposition rate, uniform distribution of B in the deposit and ease control of the process. In addition, the average grain size and composition can be easily controlled by the electrodeposition condition, such as the current density. Ni-B alloys were prepared by electrodeposition with a Watt’s bath. The B content varied from 2.8 to 14.3 at.% as the current density decreased from 4 to 1 A/dm2. Crystalline structure of the Ni-B alloys was characterized by X-ray diffraction (XRD). Thermal stability test of Ni-B alloys were conducted to evaluate their mechanical performance after heat treatment at 250 °C. The mechanical property in micro-scale were evaluated by micro-compression test using micro-pillar type specimens fabricated by focused ion beam system. B content in the Ni-B alloy deposits reduced and micro-hardness increased as the current density increased as shown in Fig. 1. The compressive strength of the Ni-B alloy having the cobalt content of 3 at.% reached a maximum of 5.67 GPa after 4 h heat treatment.