Galvanoplasty has been used and known for a long time. LIGA type methods (a well know abbreviation for the German term “rontgenLIthographie, Galvanoformung & Abformung”) are more recent. They consist in forming a mould by photolithography using a photosensitive resin, and then, by galvanoplasty, growing a metal deposition, such as nickel, therein. The precision of LIGA techniques is much better than that of a conventional mould, obtained, for example, by machining. This precision thus allows the fabrication of micromechanical parts, particularly for timepiece movements, which could not have been envisaged before.
However, these methods are not suitable for micromechanical parts with a high slenderness ratio, such as a coaxial escape wheel made of nickel-phosphorus containing, for example 12% phosphorus. Electrolytic depositions of this type of part delaminate during plating, because of internal stresses in the plated nickel-phosphorus, which cause it to split away at the interface with the substrate.
USPTO Backgrounds
USPTO Backgrounds