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Browse Prior Art Database

Solder Stencil Printing of Three-Dimensional Substrates

IP.com Disclosure Number: IPCOM000105761D
Original Publication Date: 1993-Sep-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Britton, K: AUTHOR

Abstract

Disclosed is a method which enables solder stencil screen printing of circuit substrates at two different levels in one pass. It is simple and removes the need for a secondary operation in the manufacture of SMT circuits.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 95% of the total text.

Solder Stencil Printing of Three-Dimensional Substrates

      Disclosed is a method which enables solder stencil screen
printing of circuit substrates at two different levels in one pass.
It is simple and removes the need for a secondary operation in the
manufacture of SMT circuits.

      The method allows a departure from traditional surface mounting
technology (SMT) printing, should the final substrate require a
3-dimensional nature such as raised heatsinks on flex assemblies.
Traditional solder stencil printing has been carried out on 'flat'
2-dimensional substrates only.

      By an effective pitch reduction of the substrate on a solder
printer workholder, to allow for the 3-dimensional nature, a pitch-
reduced stencil artwork can be produced which includes apertures to
allow the raised portions of the substrate to protrude through the
stencil.  The passage of solder paste down to these raised areas is
prevented by attaching a polyester or similar material blocked mesh
to the aperture.  The rubber printing squeegee is cut in areas
corresponding to the raised portions of the substrate,to allow the
entire substrate to be printed for SMT assembly.

      The figure illustrates the process in cross section upon a
flexible circuit substrate 1.  The solder stencil 2 with a polyester
mesh blocking aperture 3 is positioned beneath the rubber printing
squeegee 4 so that a channel 5 cut in the squeegee 4 is coincident
with the position of the required 3D subs...