Method for the fabrication of isometric mesh on the concave of a spherical substrate

Abstract

Metallic mesh has been widely used in electromagnetic interference windows. While the duty ratio of curved mesh equals to planar mesh', the theory of planar mesh may be applied to curved mesh according to equivalent-circuit model. So the idea that latitude lines intersect latitude lines to form isometric mesh on the concave of a sphere is put forward, and the method of fabricating the mesh by concentric optical scan is introduced. The movement parts of equipment consist of an erection turning, a horizontal dividing and a pitching dividing spindle. Firstly, a spherical substrate is fixed on the horizontal dividing spindle that has been set horizontally on the erect turning spindle, the substrate revolves around the axis of the erect spindle, the tube of object lens that is fixed on the pitching dividing spindle steps at pitching direction, and a revolving circuit of the substrate corresponds to a step of the tube. Gradually, a set of latitude lines is attained. Afterward, the substrate makes a quarter turn around the horizontal spindle, another orientation latitude lines are also gained. Thus, the isometric mesh on the concave of a spherical substrate is gained. The process comprises surface cleaning, coating photoresist, laser direct writing, development, evaporated film, dissolving photoresist and plating. The fabricated spherical mesh has a line width of 7μm and a period of 600μm. Experiment shows that infrared transmission and electromagnetism shield efficiency of the metallic mesh are relatively consistent with theoretical value.