Browse Prior Art Database

Rework of Chips on Flexible Circuit Boards

IP.com Disclosure Number: IPCOM000103356D
Original Publication Date: 1990-Oct-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 37K

Publishing Venue

IBM

Related People

Christenson, DE: AUTHOR [+4]

Abstract

Described is a technique for the removal of die (chips) that have been adhesively bonded to a substrate and then wire bonded.

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This is the abbreviated version, containing approximately 100% of the total text.

Rework of Chips on Flexible Circuit Boards

      Described is a technique for the removal of die (chips) that
have been adhesively bonded to a substrate and then wire bonded.

      The substrate 1 (see the figure), which consists of the
stiffener 6 and flex 9, with the die 2 to be removed, is mounted to
the fixture base 3.  All wire bonds 4 are removed.

      Heat is applied to the die adhesive through the stiffener 6 by
the heater 7.  The amount of heat applied to the flex adhesive 5 by
the heater 7 should be less than the glass transition (Tg) of the die
adhesive 5 or any lessor (Tg) (i.e., flex adhesive 8 or flex 9) in
close proximity to the die 2 to be removed.

      A collet 10 is placed over the die 2, which incorporates a die
cavity 11, vacuum 12, and heating element 13.

      Heat greater than the die adhesive 5 (Tg) is applied through
the collet 10 at the same time vacuum 12 and a slight twisting
pressure is applied.

      The die adhesive 5 will shear cleanly once the (Tg) of the die
adhesive 5 is exceeded.  The die 2 is held by the vacuum 12 for
removal when the collet 10 encasing the die 2 is separated from the
substrate 1.

      Disclosed anonymously.