Browse Prior Art Database

High I/O Flex Interconnection Technique

IP.com Disclosure Number: IPCOM000103124D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 39K

Publishing Venue

IBM

Related People

Graham, T: AUTHOR [+9]

Abstract

Disclosed is a solder-reflow approach to reliably interconnect two electrically functional substrates using a flexible foil edge connector (Flex) containing a high number of I/O's, and a solder deposited on either the substrate and/or the Flex via, for instance, wave soldering.

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High I/O Flex Interconnection Technique

      Disclosed is a solder-reflow approach to reliably interconnect
two electrically functional substrates using a flexible foil edge
connector (Flex) containing a high number of I/O's, and a solder
deposited on either the substrate and/or the Flex via, for instance,
wave soldering.

      In this approach, the circuits on the Flex are coated with
photoimageable solder dam except the I/O areas for solder joining.
The joining of the Flex to the substrate (or substrates) proceeds as
follows:
   -Glue a glass backbone to the back (non-circuitized) side of the
Flex
      -Align the Flex with respect to the substrate with the help of
the glass backbone and a microscope
      -(optional) Insert a spacer between the Flex and the substrate
for solder height control during reflow
   -Use a fixture to hold the Flex against the substrate to preserve
the alignment during solder reflow
      -Apply a low-viscosity flux, X-32 (Trademark of Multicore
Corporation) to the joining areas between the Flex and the substrate
      -Place the Flex/substrate assembly in a vapor-phase
fluorocarbon bath to reflow the solder

      Because of the use of the vapor-phase reflow process which
allows fast and uniform solder reflow over large areas and a flux
which does not require post-reflow cleaning, this approach is well
suited for Flex solder joining over large areas.

      Disclosed anonymously.