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Laser Process and Tool for Cleaning or Reworking Epoxy on a Slider

IP.com Disclosure Number: IPCOM000105718D
Original Publication Date: 1993-Sep-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 69K

Publishing Venue

IBM

Related People

Bachi, P: AUTHOR [+5]

Abstract

Removal of sliders from suspension during rework is conventionally done by tedious manual mechanical means. The work becomes increasingly more difficult with reduction of the slider sizes. We describe here a method of using laser ablation to remove the epoxies. By proper use of fluence, wavelength, and number of pulses using an end-point detection control scheme, the slider can be cleanly removed without damage to the head element.

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Laser Process and Tool for Cleaning or Reworking Epoxy on a Slider

      Removal of sliders from suspension during rework is
conventionally done by tedious manual mechanical means.  The work
becomes increasingly more difficult with reduction of the slider
sizes.  We describe here a method of using laser ablation to remove
the epoxies.  By proper use of fluence, wavelength, and number of
pulses using an end-point detection control scheme, the slider can be
cleanly removed without damage to the head element.

      Our method utilizes laser ablation of epoxy using, e.g., KrF
(248 nm) excimer lasers.  For a red-dyed epoxy, we found that
XeClexcimer laser radiation (308 nm) does ablate as well.  We
typically used fluences of 250  mJ/cm sup 2 in our experiments under
normal incidence, and found that the residual epoxy material of
thickness up to some 60 micrometer could be ablated within typically
1500 laser pulses.

      For removing the epoxy from the gold studs there are several
choices.  First, one can project onto the slider back side, so as
only to irradiate the gold studs, or to use a full field irradiation
which irradiates the read/write element as well.  In our experiments
we used both KrF- and XeC1 excimer lasers at 250  mJ/cm sup 2 and 300
mJ/cm sup 2, respectively, to ablate the red-dyed epoxy from the gold
studs.  Inspection of the irradiated magnetic heads showed clean,
undamaged surfaces both at the slider body and the gold studs.

      The selection of properly dyed epoxy used for bonding gives us
a simple method for detection of residual epoxy.  In the top surface
region of the epoxy the laser light intensity is above-threshold for
ablation.  The epoxy and the dye material within this ablated volume
are ejected and cracked.  The dye chromophores are unstable under
these conditions, so that no light fluorescence will emerge from t...