Browse Prior Art Database

Three Layer Former Flex

IP.com Disclosure Number: IPCOM000103382D
Original Publication Date: 1990-Oct-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 38K

Publishing Venue

IBM

Related People

Horton, RR: AUTHOR [+3]

Abstract

It has been learned that for flex interconnects that have leads on extremely tight pitch there exists a possibility of forming a dendrite when an electrolyte is present with operating DC potentials. An accepted remedy for this existing problem is to coat the affected area with a material to exclude the conditions for dendrite formation, thus, eliminating a shorting path. The proposal presented here is an alternative to coating and will double the space between adjacent leads plus the lead width.

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Three Layer Former Flex

      It has been learned that for flex interconnects that have leads
on extremely tight pitch there exists a possibility of forming a
dendrite when an electrolyte is present with operating DC potentials.
An accepted remedy for this existing problem is to coat the affected
area with a material to exclude the conditions for dendrite
formation, thus, eliminating a shorting path.  The proposal presented
here is an alternative to coating and will double the space between
adjacent leads plus the lead width.

      The proposed invention will place leads on opposite sides of an
insulating film at a spacing which prevents dendrite formation.
Industry standard processing procedures will permit the leads to then
be plated through holes or vias in the polyimide film to facilitate
OLB joint formation. This concept of bringing the leads to one side
of the polyimide is not entirely necessary as the OLB area could be
formed to put the leads in a planar manner.

      The ILB area of the flex usually would have the tightest center
to center spacing and would then protrude from the polyimide carrier
film on opposite sides. This situation would then place the bonding
surface of the leads to be out of plane by the thickness of one lead
plus the carrier film thickness.  A forming tool would then be used
to bend the leads and allow the leads to be put in one plane for
successful inner lead bonding.

      Disclosed anonymously.