Browse Prior Art Database

Method for Solder Deposition On Tab Outer Leads

IP.com Disclosure Number: IPCOM000119637D
Original Publication Date: 1991-Feb-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 39K

Publishing Venue

IBM

Related People

Nguyen, DQ: AUTHOR [+2]

Abstract

Disclosed is a method that supplements the low solder volume on the carrier pads that are normally achievable (0.007" or 0.010" wide pads) for Tape Automated Bonding (TAB) applications.

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

Method for Solder Deposition On Tab Outer Leads

      Disclosed is a method that supplements the low solder
volume on the carrier pads that are normally achievable (0.007" or
0.010" wide pads) for Tape Automated Bonding (TAB) applications.

      A solder deposition tool, such as in [*], may be used to
selectively deposit solder on outer leads of TAB devices via
selective masking of the signal side of the tape.  No bridging of
solder occurred.

      Referring to the figure, TAB tape 2 is mechanically masked (4)
on the signal side to prevent solder from flowing into the sensitive
regions such as the inner leads 6 and chip 8.  The solder apply tool
10, with a small nozzle, travels along the outer lead regions 12 to
deposit molten eutectic solder 14.  Wetting action between the solder
and gold-plated outer lead, as shown at 16, occurs.  The deposited
layer will freeze to form a solder layer.

      This method supplements solder volume requirements for reliable
bonding of TAB devices.  The process circumvents the need for
subjecting the tape to harsh chemical baths that is otherwise needed
to electroplate tin-lead on the outer leads of the tape.  The
technique is especially attractive for rework, since the pads on the
carrier need not be redressed heavily for reattachment because the
new device, by definition, is available with coated solder.

      Reference
(*) U.S. Patent 4,898,117.