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INTEGRAL DIE SUPPORT AND DOWNSET FIXTURE FOR TAB INNER LEAD

IP.com Disclosure Number: IPCOM000006996D
Original Publication Date: 1993-Oct-01
Included in the Prior Art Database: 2002-Feb-15
Document File: 2 page(s) / 128K

Publishing Venue

Motorola

Related People

Peter Cole: AUTHOR

Abstract

The use of Tape Automated Bonding (TAB) is a packaging alternative which is finding increasing application for high density/fine pad pitch devices. TAB packaging consists of a leadframe on a plastic substrate (such as kapton) which is bonded to a die using either a "gang" or "single point" bonding proc- ess (Figure 1).

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MOTOROLA INC. Technical Developments Volume20 October 1993

INTEGRAL DIE SUPPORT AND DOWNSET FIXTURE FOR TAB INNER LEAD

by Peter Cole

  The use of Tape Automated Bonding (TAB) is a packaging alternative which is finding increasing application for high density/fine pad pitch devices. TAB packaging consists of a leadframe on a plastic substrate (such as kapton) which is bonded to a die using either a "gang" or "single point" bonding proc- ess (Figure 1).

  Electrical shorts between the inner lead and the substrate is a problem that can occur during inner lead bonding (ILB) (Figure 2). This problem can be caused in several ways, primarily: lead distortion due to the heat of bonding, metallization that has been displaced during the sawing process, or variations in planarity of the TAB tape relative to the top sur- face of the die.

  This problem has been addressed in the past through the use of a "Downset" process, which con- sists of deforming the leads after bonding to create clearance between the lead and the substrate and/or metallization (Figure 3). A critical aspect of the downset process is achieving precise alignment between the die and the bumps to insure that the lead will be lifted over the scribe grid while mini- mizing stress on the lead/bump interface. Excessive stress on the bond may pull the lead off ofthe bump, or weaken the bond sufficiently to cause failure at a later time.

  A solution to this problem is to incorporate the mandrel of the downsetting proces...