Method of forming fiducials, and stencils containing such fiducials

摘要

A method of forming a fiducial in a stencil for screen printing and the stencil so formed is described. A target fiducial thru- hole of a first size is formed in the stencil, the surface of the stencil in an area around and larger than the size of the target thru-hole is electrochemically etched, and the target fiducial thru-hole is filled with a filling material. The target fiducial thru-hole, included as part of the stencil pattern, is used as a target to which the fiducial mask, used in the electrochemical etching, can be aligned to. The target fiducial thru-hole may be made smaller than previously feasible because the fiducial is electrochemically etched, which means that it cannot fall out of the stencil. The filling in the target fiducial thru-hole is less likely to fail since it has a drastically decreased surface area to wall thickness area ratio compared to conventionally formed fiducials.