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Via Fill With Molten Solder

IP.com Disclosure Number: IPCOM000120546D
Original Publication Date: 1991-May-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 65K

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Disclosed is a new method to fill the via holes in a circuit board with molten solder.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Via Fill With Molten Solder

      Disclosed is a new method to fill the via holes in a
circuit board with molten solder.

      In Fig. 1 the solder balls 2 can be connected directly to
solder-filled vias 4.  The via-filled connection provides a more
reliable solder joint, as well as improvements in electrical
performance and wireability.

      The process disclosed here uses a solder deposition tool, such
as is shown in Fig. 2, to deposit molten solder to fill the vias. The
molten solder 6 is formed by feeding solder wire 8 by a stepper motor
10 to contact the solder iron 12  The solder iron is mounted
concentrically inside a cylindrically-shaped housing 14.  Nitrogen
flows out through twin nozzles 16 to blanket the spot where molten
solder is filling the vias.  The amount of solder deposited can be
controlled by the amount of solder wire fed by stepper motor.

      Prior filling vias, a heat pad is placed underneath the site to
pre-heat the bottom of panel.  A generous amount of flux is then
applied to the via-hole site on both sides.

      This solder-via fill process provides the advantage for
"localized area via fill" capability as compared to other potential
via fill processes.