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Manufacturable Magnetoresistive Slider Electrical Overstress Protector

IP.com Disclosure Number: IPCOM000114707D
Original Publication Date: 1995-Jan-01
Included in the Prior Art Database: 2005-Mar-29
Document File: 4 page(s) / 156K

Publishing Venue

IBM

Related People

Brooks, WW: AUTHOR

Abstract

Disclosed is an idea for an easily applied and easily removed solder link for protecting advanced (i.e., extremely electrical overstress (EOS) and electrostatic discharge (ESD) fragile) Magnetoresistive (MR) sliders from damage during head/suspension assembly and actuator manufacturing processes.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Manufacturable Magnetoresistive Slider Electrical Overstress Protector

      Disclosed is an idea for an easily applied and easily removed
solder link for protecting advanced (i.e., extremely electrical
overstress (EOS) and electrostatic discharge (ESD) fragile)
Magnetoresistive (MR) sliders from damage during head/suspension
assembly and actuator manufacturing processes.

      The first generation MR sliders had very thin film MR elements
which were capable of withstanding about 100 volts of static
discharge without appreciable EOS/ESD damage.  However, the latest MR
sliders use much smaller MR element cross-sections, so their damage
thresh-holds are at 10 volts or less, a figure that is too low for
even stringent ESD precautions to prevent some sliders from being
damaged in process.

      The solution to the problem is to use a low temperature solder
to bridge between two adjacent pads connected to either side of the
MR stripe.  This will protect the element from EOS/ESD damage, but by
itself this is no solution since it must be removed before the head
will become functional.  Ideally, for maximum protection, one would
want to open this shorting solder element after the file was closed
up on the line.  Practically, with the disclosed invention, the
shorting elements can be removed on the file line, at or just before
actuator merge to the file.

      The key is to provide the proper geometry of the shorting pads,
coupled with the proper volume and shape of low temperature solder,
such that upon reheating with a very simple, wide angle heat source,
the solder will reflow and surface tension will open the shorting
link.  The solder would remain on the slider so that the extremely
difficult operation of solder removal at actuator level would not
need
to be done.  The means of accomplishing this is now described in
detail.

      The slider magnetic structure is created on the surface of a
large N58 ceramic wafer by way of a multi-step deposition process.  A
portion of such a wafer is shown in Fig. 1.  The succeeding process
steps of slicing, air bearing surface creation and dicing are shown
schematically by phantom lines in this Figure.  The saw cuts which
define the top surface of each slider are also used in creating the
proper shape for the solder fuse links as will be seen shortly.

      Following the creation of all of the normal slider magnetic
structure on the wafer, solder paste would be silk-screened onto the
head wafers to cover the copper pads which define either half of each
shorting link.

      In order to find room on the slider end for the fuse links,
there will need to be some rearrangement of the pad locations and
probably also of the pad order.  Our current pad layout has the two
inductive element pads being on either end of the back of the slider,
while t...