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Browse Prior Art Database

Flex Adapter for a Pad on Pad Demountable Package

IP.com Disclosure Number: IPCOM000110330D
Original Publication Date: 1992-Nov-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 2 page(s) / 67K

Publishing Venue

IBM

Related People

Lanzetta, AP: AUTHOR [+2]

Abstract

The manufacture of a pad on pad demountable multichip module (MCM) is complicated by the problem of applying a gold coating to the bonding pads on the motherboard. A gold surface is necessary for pad on pad interconnection, but standard circuit board pads are tin-lead on copper, and selective gold plating is prohibitively expensive. In order to make this demountable package feasible as quickly as possible, a way must be found to bridge the gap between available technology and the new structure required.

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This is the abbreviated version, containing approximately 100% of the total text.

Flex Adapter for a Pad on Pad Demountable Package

       The manufacture of a pad on pad demountable multichip
module (MCM) is complicated by the problem of applying a gold coating
to the bonding pads on the motherboard.  A gold surface is necessary
for pad on pad interconnection, but standard circuit board pads are
tin-lead on copper, and selective gold plating is prohibitively
expensive.  In order to make this demountable package feasible as
quickly as possible, a way must be found to bridge the gap between
available technology and the new structure required.

      Disclosed is a method for disposing an adapter flex between a
card and an MCM flex.  The adapter is gold-plated, and allows solder
connections to the card and POP to the MCM flex.  Figure 1 shows the
adapter design.  It consists of straight signal lines between two
sets of pads.  During assembly, a solid supporting frame is inserted
underneath it to aid forming and improve mechanical robustness.  This
is shown in Figure 2.  The soldered OLBs at the card, then, form a
permanent connection, and the demountable module is separated at the
POP connection.

      The concept of an adapter flex would be universally useful for
going between two disparate connector requirements.  It serves as an
immediately manufacturable means of making a demountable package,
using existing technology.  This would allow more time for
development of the new technology.