Browse Prior Art Database

Solder Filled Vias in Pad for Surface Solder Applications

IP.com Disclosure Number: IPCOM000122505D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 3 page(s) / 80K

Publishing Venue

IBM

Related People

Hart, PJ: AUTHOR [+3]

Abstract

The attachment of various first level components to printed circuit card designs requires a variety of soldering operations to accomplish that goal. Disclosed is a technique using PVA (Poly Vinyl Alcohol) tape as a water-soluble solder mask prior to wave solder or any other solder operation. The PVA serves as a mask to eliminate additional reflow of existing joints by preventing wave contact. The PVA tape can be used at various points in the assembly process to obtain the desired masking results on any design type or assembly operation.

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Solder Filled Vias in Pad for Surface Solder Applications

      The attachment of various first level components to
printed circuit card designs requires a variety of soldering
operations to accomplish that goal.  Disclosed is a technique using
PVA (Poly Vinyl Alcohol) tape as a water-soluble solder mask prior to
wave solder or any other solder operation.  The PVA serves as a mask
to eliminate additional reflow of existing joints by preventing wave
contact.  The PVA tape can be used at various points in the assembly
process to obtain the desired masking results on any design type or
assembly operation.

      The surface solder application technology for future programs
requires a PTH (Plated Through Hole) directly under each solder ball
connection of the module.  To assure a reliable solder joint
connection both physically and electrically between the module and
card circuitry, a PTH fill technique for 12-mil vias is needed.  Once
the PTH via is filled it must stay filled, and free of voids which
would cause fails both physically and electrically.  The disclosed
invention allows both 100% PTH hole fill and eliminates the voids
caused by additional wave solder contact.

      An example would be to take a printed circuit card with copper
PTHs plus SMT devices and eventually add the surface solder
technology.  Figure A shows the PTH filled with solder.  Figure B
shows the surface solder depletion caused by additional reflows of
the PTH.  Figure C shows t...