Micro Electroformed Ni-P Alloy Parts by extended UV-LIGA Technology

Abstract

In recent years an increasing interest has grown in using Micro Electro Mechanical System (MEMS) fabrication technology in mechanical timepieces. The UV-LIGA process which combines ultraviolet lithography and electroforming is among micro-production technologies providing exciting possibilities. It has been established as industrial viable for the fabrication of various micromechanical components. Current limitations are that the technology is restricted to the use of nickel. It is too soft (~ 300HV) and has magnetic properties. It is not perfect for the movement of timepieces. However, by adding other materials, e.g. phosphor-Nickel (Ni-P), these alloys have their attractions, being stainless, non-magnetic and very high hardness. As a new technique, details are still being perfected. In this work, the process of Ni-P micro electroforming has been developed to extend UV-LIGA technology. And attempt has been made to investigate the magnetic properties and the hardness of the manufactured Ni-P alloy components. The results showed that the phosphor content can be controlled by different concentration of phosphorous acid (H3PO3) in the electrolyte solution. Corresponding properties have been analyzed which shows good hardness and lower magnetic properties. When the phosphorous content reaches over 12 wt%, the Ni-P alloy is with non-magnetic properties while pure nickel is ferromagnetic material. And the hardness of electroformed Ni-P alloy is about 600 HV and can be above 1000 HV after special heat treatment.