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Unique DASD Flex Cable

IP.com Disclosure Number: IPCOM000037777D
Original Publication Date: 1989-Jun-01
Included in the Prior Art Database: 2005-Jan-30
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Bickford, HR: AUTHOR [+9]

Abstract

The goal for high-volume DASD access cables is to improve machine performance and lower costs. Present practice calls for mounting servo and data chips enclosed in plastic packages or TAB packages onto the cables by means of standard surface mount techniques. The problem posed is to find a method to attach the chips directly to flex and to discover a cable format that makes direct chip attach manufacturing possible. Direct attach reduces the length of interconnections which in turn lowers inductance and electrical resistance, as well as reducing thermal resistance. One difficulty which must be overcome is that of the thermal mismatch between the chip and the substrate. The solution must be low cost for low-end applications.

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Unique DASD Flex Cable

The goal for high-volume DASD access cables is to improve machine performance and lower costs. Present practice calls for mounting servo and data chips enclosed in plastic packages or TAB packages onto the cables by means of standard surface mount techniques. The problem posed is to find a method to attach the chips directly to flex and to discover a cable format that makes direct chip attach manufacturing possible. Direct attach reduces the length of interconnections which in turn lowers inductance and electrical resistance, as well as reducing thermal resistance. One difficulty which must be overcome is that of the thermal mismatch between the chip and the substrate. The solution must be low cost for low-end applications.

The flexible cables are manufactured with free standing copper beams provided within windows in the substrate material and are designed to fit within TAB tape format. The free- standing copper beams, plated with suitable metals (e.g., gold, tin, solder, etc.) are used to make connections to chips. The connections are made by means of thermocompression bonding or solder reflow. Thermal strain relief is obtained by bending the leads in either the plane of the substrate or offsetting the leads out of the plane of the substrate. The flex cable designed in a compact manner to fit within a tape format makes possible reel-to- reel bonding of the chips to the cable using automated manufacturing tools.

Disclosed anonymously.

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