Micro fabrication molding process

Abstract

Identical half-section shells of microscopic size, such as hemispherical shells from which spherical laser fusion targets can be made are capable of mass production by micro fabrication molding techniques. A body (preferably a hollow glass microsphere which is called a glass microballoon) provides a pattern for the hemispherical shells, and is used to produce an original mold section. One or more master molds are formed from this original mold section by replication. Many identical replica molds are made by casting soluble material onto the master mold and removing them therefrom. The replica molds are coated with one or more layers which will form the hemispherical shell wall. The material coating the flat background around the hemispherical cavity is referred to as the flange and is removed to form free standing shells. In order to remove the flange material, the coated replica molds are overcoated with a soluble material which is etched away to the level of the flange. The remaining soluble material acts as a mask for the shell material when the flange material is etched away. The replica mold and overcoating body remain as a protective mask and are dissolved away to release the identical shell sections. These sections can be assembled to provide closed shells. Overlapping lips can be formed during flange removal so as to facilitate the assembly of the sections into the closed shells.