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Browse Prior Art Database

Spiral ILB to Allow Closely Packed I/O for TAB

IP.com Disclosure Number: IPCOM000103381D
Original Publication Date: 1990-Oct-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 32K

Publishing Venue

IBM

Related People

Horton, RR: AUTHOR [+3]

Abstract

A common approach to increase the number of pads in a perimeter layout of a microchip is to provide two rows that are staggered in the center to center spacing. The pads can be overlapping in the X direction as this will allow closer packing, a larger target for the mating beam, or a combination of these factors. A potential problem with this approach will occur when the longer leads in this double row pass between the outer pads of the silicon chip. If there is a slight misalignment or if there is not good control of the beam widths there can be some shorting of the longer leads and the outer pads.

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Spiral ILB to Allow Closely Packed I/O for TAB

      A common approach to increase the number of pads in a perimeter
layout of a microchip is to provide two rows that are staggered in
the center to center spacing. The pads can be overlapping in the X
direction as this will allow closer packing, a larger target for the
mating beam, or a combination of these factors. A potential problem
with this approach will occur when the longer leads in this double
row pass between the outer pads of the silicon chip. If there is a
slight misalignment or if there is not good control of the beam
widths there can be some shorting of the longer leads and the outer
pads.

      A TAB or flex is fabricated in a standard industry process
through the final plating step at which time the longer leads of this
staggered row design will receive an additional process step which
consists of rotating the outer leads 180 degrees around their own
axis. This rotation will then take the effective beam width from the
stated width to the beam thickness. By clamping the fixed end at a
prescribed distance, this area of minimum width can be tailored to
the pad location.

      Disclosed anonymously.