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Bumped Tape Structure Produced by Laser Melting

IP.com Disclosure Number: IPCOM000101330D
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Gupta, A: AUTHOR [+2]

Abstract

Disclosed is a new interconnection structure for tape automated bonding (TAB). Bumped tape structure is a preferred format compared to bumped chip structure in the applications of TAB. Bumped tape structure can be produced by either etching off a thicker copper beam tape or by electroplating bumps onto a copper beam tape.

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Bumped Tape Structure Produced by Laser Melting

       Disclosed is a new interconnection structure for tape
automated bonding (TAB).  Bumped tape structure is a preferred format
compared to bumped chip structure in the applications of TAB.  Bumped
tape structure can be produced by either etching off a thicker copper
beam tape or by electroplating bumps onto a copper beam tape.

      In the present disclosure, a new bump structure, semi-spherical
shape is produced by using an argon ion laser in a controlled
operation.  Figure 1 shows schematically the laser melting process
and the resultant bump structure formed on a beam tape.  A
semi-spherical bump is limited to the width of the rectangular beam.
This semi-spherical bump structure is obtained by melting either bare
copper beams or gold-plated copper beams.

      The laser-melted bump is found to be softer than the original
copper beam.  Therefore, thermocompression bonding to other clean
metal surfaces can be easily accomplished. One advantage of having
the semi-spherical bump structure rather than the spherical bump one
is to avoid excessive bump deformation of the lower half of the
spherical bump in thermocompression bonding.  Another advantage of
forming a semi-spherical bump is such that upon melting of a same
amount of beam, the bump height is higher for the case of the
semi-spherical bump compared to the case of the spherical bump.