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Integrated PTFE-Based Flex Cable with Improved Tear Resistance

IP.com Disclosure Number: IPCOM000115918D
Original Publication Date: 1995-Jul-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 62K

Publishing Venue

IBM

Related People

Brodsky, W: AUTHOR [+3]

Abstract

High performance printed wiring board and cables of PTFE-based materials having thin cross-sections are at risk of tearing. The cross section of these cables must satisfy many design requirements, primarily for electrical performance and reliability in thermal cycling. Accordingly, the cable includes a so-called compensator at its core, constructed entirely of Copper-Invar-Copper (CIC) to provide a low thermal expansion to match components that may be mounted on the board/cable. Since CIC is a relatively weak and brittle material this can result in a flex cable that is sensitive to handling, and may tear.

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Integrated PTFE-Based Flex Cable with Improved Tear Resistance

      High performance printed wiring board and cables of PTFE-based
materials having thin cross-sections are at risk of tearing.  The
cross section of these cables must satisfy many design requirements,
primarily for electrical performance and reliability in thermal
cycling.  Accordingly, the cable includes a so-called compensator at
its core, constructed entirely of Copper-Invar-Copper (CIC) to
provide a low thermal expansion to match components that may be
mounted on the board/cable.  Since CIC is a relatively weak and
brittle material this can result in a flex cable that is sensitive to
handling, and may tear.

      The obvious suggestions to reinforcing the cross-section all
have had some drawback when considering the electric and mechanical
requirements for the cable.  For example, reinforcing the cable with
an additional layer of a polyimide has the disadvantage of changing
the electrical properties, and changing the compliance of the
cross-section which can be critical where connectors attach.
Furthermore, polyimides have been found to be restricted to lower
laminating pressures and temperatures than what may be required in
the construction of the various cross-sections, namely, 700F and 1700
psi.  Substituting a less brittle, or tougher conductor in place of
CIC has the disadvantage of not providing the very low thermal
expansion of CIC.

      This has been solved by creating a new cross-s...