Browse Prior Art Database

Progressive Lead Width from Chip Center to Provide Lead Strength

IP.com Disclosure Number: IPCOM000103380D
Original Publication Date: 1990-Oct-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 33K

Publishing Venue

IBM

Related People

Horton, RR: AUTHOR [+4]

Abstract

TCE mismatches between large silicon packages and the flex structures used as connectors can cause lead bending as the distance from the center line increases. To help alleviate this inherent problem the following approach is advanced. At prescribed intervals the interconnecting lead width will be increased as one moves from the carrier centerline to the extreme edge of the flex. Mating pads will also increase in width to accommodate the wider lands. At all times the flex manufacturer's lead spacing minimum will be maintained and the necessary real estate to accomplish this will be gained around the carrier centerline, that is to say, that this lead width can be reduced without reflecting reduced joint integrity.

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Progressive Lead Width from Chip Center to Provide Lead Strength

      TCE mismatches between large silicon packages and the flex
structures used as connectors can cause lead bending as the distance
from the center line increases.  To help alleviate this inherent
problem the following approach is advanced. At prescribed intervals
the interconnecting lead width will be increased as one moves from
the carrier centerline to the extreme edge of the flex.  Mating pads
will also increase in width to accommodate the wider lands.  At all
times the flex manufacturer's lead spacing minimum will be maintained
and the necessary real estate to accomplish this will be gained
around the carrier centerline, that is to say, that this lead width
can be reduced without reflecting reduced joint integrity.

      As I/O pads increase in number and a staggered row of pads is
to be used, a variation of this concept is also proposed.  When
approaching the leads furthest from the chip centerline it would be
beneficial to provide a few wider leads on the outer row of I/O for
structural integrity while still reducing the width of the inner row
beam's corresponding pad.

      Disclosed anonymously.