Screens And Electroformed Accuscreens For Solar Printing Applications
Authors: William E. Coleman, Ph.D. Company: Photo Stencil Date Published: 10/16/2011
Abstract: Thick Film Screens have been the workhorse for printing Solar cell patterns. However, as the size of solar cell panels become larger and collector finger electrodes become smaller, screens run into some limitations. When the collector finger electrode widths approach 50 to 75 microns the wire diameter of screens become an issue in line definition. As the area of the printed image gets larger trampoline screens are required, requiring precise mounting and uniform tension. In addition this type screen is very expensive and prone to distortion during the printing life cycle. This presentation will review screen applications for solar printing and will introduce a new product for solar printing. AccuScreen that is manufactured using an electroforming process. The electroform screen and a Nickel layer define the finger trace that can be as thick as 75 to 100 microns. A mesh pattern is also electroformed to define the mesh pattern over the open finger traces. In Addition AccuScreen + is an electroform product where support bars are formed across the fingers allowing 90% open print area with electroformed mesh for the wider buss bar connectors. A second layer of electroformed Nickel is plated up to form the buss and finger traces. Finally AccuScreen ++ is similar to AccuScreen + except that an additional emulsion layer defining the finger and buss traces is added. All of the AccuScreen configurations will be described in detail with examples of prints for finger widths down to 50 micron.