Method and stencil for extruding material on a substrate

Abstract

A stencil for use in fabricating semiconductor devices is disclosed that has an aperture having a first portion extending from a first side thereof and a second portion extending from a second side thereof to minimize the shear stress between the material extruded therethrough and the stencil. The stencil allows for material to be extruded through the top of the stencil to the surface of the substrate and not contact the wall of the second portion of the aperture of the stencil. Since the material only contacts a small area of the first portion of the aperture near the top of the stencil, the material remains on the substrate and not in the aperture of the stencil.

1 . A stencil for applying a printed material to a substrate, comprising: 
 a first surface having at least one aperture of a first dimension;    a second surface formed on the first surface and having a second aperture conforming to the first dimension of the at least one aperture in the first surface and being larger than the one aperture thereby forming a recessed area.    
   
   
       2 . The stencil according to  claim 1  wherein the second aperture ranges from 0.1 to 10 times the width of the one aperture.  
   
   
       3 . The stencil according to  claim 1  wherein the stencil has a thickness that ranges from 0.1 to 10 times the first dimension.  
   
   
       4 . The stencil according to  claim 1  wherein the stencil has a thickness twice that of the first dimension.  
   
   
       5 . The stencil according to  claim 1  wherein the stencil is formed from stainless steel.  
   
   
       6 . The stencil according to  claim 1  wherein the stencil is formed from a rigid plastic.  
   
   
       7 . The apparatus of the stencil according to  claim 1  wherein the aperture further includes at least one shoulder between the first wall and the second wall, the shoulder being sloped from the first wall to the second wall.