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Inner Lead Guard Punch for TAB Chip Carriers

IP.com Disclosure Number: IPCOM000121085D
Original Publication Date: 1991-Jul-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 2 page(s) / 78K

Publishing Venue

IBM

Related People

Barbosa, JA: AUTHOR [+4]

Abstract

High lead count, fine pitch TAB chip carriers utilize an "inner lead guard" to protect the fragile cantilever beams used as inner leads. The inner leads are typically extended to a pad or ring which supports the ends of the leads. Some configurations of TAB require removal of this guard before the chip bonding process. An excise punch and die system can be used for this removal operation. A sectioned rectangular zero clearance compound die set which pilots on the area for guard ring removal can be used if all the inner leads are to be cut to the same length. A more complex zero clearance compound die set is required to excise the leads to different lengths. Fig. 1 shows a schematic of such a punch and die set, Figs. 2 and 3 show the detail of an actual set used to clip leads to two alternating lengths.

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Inner Lead Guard Punch for TAB Chip Carriers

      High lead count, fine pitch TAB chip carriers utilize an
"inner lead guard" to protect the fragile cantilever beams used as
inner leads.  The inner leads are typically extended to a pad or ring
which supports the ends of the leads.  Some configurations of TAB
require removal of this guard before the chip bonding process.  An
excise punch and die system can be used for this removal operation.
A sectioned rectangular zero clearance compound die set which pilots
on the area for guard ring removal can be used if all the inner leads
are to be cut to the same length.  A more complex zero clearance
compound die set is required to excise the leads to different
lengths.  Fig. 1 shows a schematic of such a punch and die set, Figs.
2 and 3 show the detail of an actual set used to clip leads to
two alternating lengths. The leads cut by this punch and die set were
0.0025 inches wide and 0.0014 inches thick.