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Process for Manufacturing a Double Dense TAB Package Using Solder

IP.com Disclosure Number: IPCOM000102140D
Original Publication Date: 1990-Oct-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 64K

Publishing Venue

IBM

Related People

Ameen, JG: AUTHOR [+5]

Abstract

For standard TAB chips that have been thermocompression bonded to TAB tape, one of two families of encapsulants (for the chip) may be used - epoxies or silicones. A silicone is preferred due to its low Young's modulus which provides for low stresses impressed upon the chip and inner lead bonds.

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Process for Manufacturing a Double Dense TAB Package Using Solder

       For standard TAB chips that have been thermocompression
bonded to TAB tape, one of two families of encapsulants (for the
chip) may be used - epoxies or silicones.  A silicone is preferred
due to its low Young's modulus which provides for low stresses
impressed upon the chip and inner lead bonds.

      When solder is employed to attach the chip, the encapsulants
are restricted to epoxies because of their ability to hold solder in
compression enhancing its reliability.

      To reliably encapsulate this product and to double the circuit
density, the following process is proposed:
1)   Using hot air and a redesigned tape that employs the use of a
           polyimide retaining "ring", solder attach the
           smaller of two chips to the tape.  (See Fig. 1)
           (Either gold or tin-lead plated tape may be used.)
           The polyimide ring keeps the inner leads parallel
           and in the same plane.
      2)   Inspect the attached chip for defects.
      3)   Using the same process, attach the second larger chip of
the
           set to the same inner leads as the first chip (see
           Fig. 2).
      4)   Inspect the second chip.  Since this chip is larger, the
           second set of ILBs are inspectable.
      5)   Dispense an epoxy encapsulant of sufficien...