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Browse Prior Art Database

Non-destructive, Chip Removal Process And Apparatus

IP.com Disclosure Number: IPCOM000100405D
Original Publication Date: 1990-Apr-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

Granier, G: AUTHOR [+2]

Abstract

When mechanically removing solder-bonded chips from their supporting substrate, it is desired that the solder bonds be cleanly fractured and that no chip insulation material residues be left on the substrate. Such residues, if present on the substrate, may not be completely eliminated during chip site dressing and may stay imbedded in the C-4 connection after chip replacement, thus weakening the C-4 connection.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 66% of the total text.

Non-destructive, Chip Removal Process And Apparatus

       When mechanically removing solder-bonded chips from their
supporting substrate, it is desired that the solder bonds be cleanly
fractured and that no chip insulation material residues be left on
the substrate.  Such residues, if present on the substrate, may not
be completely eliminated during chip site dressing and may stay
imbedded in the C-4 connection after chip replacement, thus weakening
the C-4 connection.

      These goals are met by means of a process which consists of:
   - preheating the chip-supporting substrate at a suitable
temperature less than the melting point of the solder, so as to
reduce the shear strength of the solder, and
   - subjecting the chip to torsional cycles of gradually increasing
amplitude, so as to progressively strain the solder bonds, until full
severance thereof is obtained.

      Referring to the figure, the apparatus which uses the above
process includes a support for holding the chip supporting substrate
in a fixed position, with the chips 10 facing upwardly. A substrate
heater is located beneath and in contact with the substrate. A
torquing head 11, mounted for rotation about a vertical axis 12, fits
over the chip 10 to be removed.

      A motor 13, whose mounting frame 14 is pivotable about a
horizontal axle 15, rotates a pulley 16 and a plate 17 rigidly
connected to, or integral with, pulley 16. Plate 17 is drivingly
coupled through a universal joint...