Process for Producing High-Resolution Screening Masks Using Polyimide Membranes for Metallization Layers on Green or Sintered Multilayer Ceramic Substrates
Original Publication Date: 1986-Nov-01
Included in the Prior Art Database: 2005-Mar-09
This process is used to fill throughholes, to screen-print conductors, power and/or voltage layers, and to apply contact or soldering paste to the surface of sintered substrates. The masks hitherto employed for that purpose have been ETMs (etch metal masks) and EFMs (electro-formed masks). The problem with either mask is that the edges of the holes in the mask pattern are non-vertical or oblique. Therefore, a process is described in which a screening mask is produced by reactive ion etching, and in which the edge profiles of the mask pattern are vertical or oblique and thus well defined. The starting material of the mask may be a commercially available polyimide foil of 20 to 120 mm or polyimide layers spun and polymerized on a substrate that is subsequently removed except for a residual frame.