Browse Prior Art Database

TAB Bumping Technique

IP.com Disclosure Number: IPCOM000108158D
Original Publication Date: 1992-Apr-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 1 page(s) / 60K

Publishing Venue

IBM

Related People

Carden, GR: AUTHOR [+4]

Abstract

Disclosed is a technique for creating planar contact pads called bumps for TAB (tape automated bonding) applications.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 81% of the total text.

TAB Bumping Technique

      Disclosed is a technique for creating planar contact pads
called bumps for TAB (tape automated bonding) applications.

      The thermo-sonic or thermo-compression ball bonding formation
of such contact pads, as is commonly practiced, is shown in Fig. 1.
Note the tail remaining on the top of the pad due to breaking the
wire once a ball is bonded to the lead surface.  In addition to
leaving the tail, the process does not uniformly control the height
of the ball.  This inherent lack of control results in several
related problems.  For example, the tail can cause the mating TAB
lead to move off location during TAB compression bonding and may
result in an electrical short between adjacent TAB leads.

      Gang thermo-compression bonding, where many TAB leads are
bonded by a single thermode, requires the bond pads be of uniform
height for all leads to bond reliably.  In some package
configurations it is desirable to place a second ball on top of the
first to increase the height of the pad. Here also, the wire tail
interferes with the placement of the second ball and height
variability is doubled.

      The disclosed invention eliminates both the tail and the height
variability and eliminates the above problems.

      After forming a ball in a conventional manner, steps are added
that planarize the pad with a forming cavity offset from the ball
forming tool.  This is shown in Fig. 2 along with the resulting
flat-topped bondi...