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Attaching Tape Automated Bonding Leads to Bumped Chip without Partial or Total Removal of Polyimide Layer Covering Leads for Support

IP.com Disclosure Number: IPCOM000118438D
Original Publication Date: 1997-Feb-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Anderson, SW: AUTHOR [+6]

Abstract

Tape Automated Bonding (TAB) is a widely used technology in all areas of electronic packaging. Inner Lead Bonding (ILB) of TAB structures to gold-bumped chips requires direct contact on the leads by the thermode used for thermocompression bonding. In the case where the lead count is very high and the leads are long and fragile, a common problem is the bending of the leads due to a lack of a support structure. During manufacture of the TAB tape, a metallic ring is used around the leads to provide support. However, this support ring is removed prior to bonding, leaving the leads without support. Inner TAB leads bend easily after metallic guard ring is removed.

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Attaching Tape Automated Bonding Leads to Bumped Chip without Partial
or Total Removal of Polyimide Layer Covering Leads for Support

      Tape Automated Bonding (TAB) is a widely used technology in all
areas of electronic packaging.  Inner Lead Bonding (ILB) of TAB
structures to gold-bumped chips requires direct contact on the leads
by the thermode used for thermocompression bonding.  In the case
where the lead count is very high and the leads are long and fragile,
a common problem is the bending of the leads due to a lack of a
support structure.  During manufacture of the TAB tape, a metallic
ring is used  around the leads to provide support.  However, this
support ring is removed prior to bonding, leaving the leads without
support.  Inner TAB  leads bend easily after metallic guard ring is
removed.

      A solution to the problem is the laser excising of the guard
ring after thermocompression bonding as shown in the Figure.  The
procedure is as follows:
  1.  The chip is covered with a laser-reflective layer, such as
       TiN, which is deposited over the top passivation layer on
       the chip.  This is done by vapor deposition at the wafer
       level.  The bonding bumps on the chip are protected by a
       mask in order to prevent deposition on these areas.
  2.  The TAB leads are attached to the chip by thermocompression
       bonding of the leads to the bumps on the chips.  The guard
       ring suppor...