Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2001-05-29
2004-10-26
Tugbang, A. Dexter (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S603010, C029S603070, C029S603100, C029S603150, C029S603120, C029S412000, C029S414000, C029S415000, C029S417000
Reexamination Certificate
active
06807722
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin-film magnetic head material including a detection element for detecting an amount of processing and a method of manufacturing such a head material and to a method of manufacturing thin-film magnetic heads through the use of a detection element.
2. Description of the Related Art
A flying-type thin-film magnetic head used for a magnetic disk device and so on is generally made up of a thin-film magnetic head slider (that may be simply called a slider) having a thin-film magnetic head element provided at the trailing edge of the slider. The slider generally comprises a rail whose surface functions as a medium facing surface (an air bearing surface) and a tapered section or a step near the end on the air inflow side. The rail flies slightly above the surface of a recording medium such as a magnetic disk by means of air flow from the tapered section or step.
A thin-film magnetic head element generally used is a composite-type element made up of layers of an induction magnetic transducer for writing and a magnetoresistive (MR) element for reading.
In general, such thin-film magnetic head sliders are formed through cutting a wafer in one direction in which sections to be sliders (called slider sections in the following description) each including a thin-film magnetic head element are arranged in a plurality of rows. A block called a bar in which the slider sections are arranged in a row is thereby formed. Rails are then formed in the bar and the bar is cut into the sliders.
The manufacturing process of the sliders includes a step of processing the medium facing surface of the bar, that is, grinding or lapping the medium facing surface and a step of cutting the wafer into the bars. The order of the step of processing the medium facing surface and the step of cutting the wafer into the bars depends on methods of processing the medium facing surface and cutting the wafer, as described later.
In the step of processing the medium facing surface, it is required that the MR height and the throat height of the thin-film magnetic head element formed in the bar each fall within a tolerance range and that processing accuracy of the surface processed falls within a tolerance range. The MR height is the length (height) between the end of the MR element close to the medium facing surface and the opposite end. The throat height is the length (height) of the magnetic pole of an induction magnetic transducer.
In the step of processing the medium facing surface, in order to precisely control the MR height and throat height of each thin-film magnetic head element included in a bar, one of the methods taken is to form a detection element (that may be called a lapping guide) in a wafer in advance for detecting an amount of processing. A signal outputted from the detection element is monitored during the step of processing the medium facing surface and the processing is controlled with high accuracy, in response to the output signal. The detection element may be a resistance element whose resistance value changes in response to its dimensions.
To monitor a signal outputted from the detection element in the step of processing the medium facing surface, it is required to form an electrode for monitoring and a lead (conductor) for monitoring in the wafer in advance, in addition to the detection element. The electrode is used for electrically connecting the detection element to a controller of an external processing apparatus. The lead is used for electrically connecting the electrode to the detection element.
FIG. 13
shows an example of arrangement of detection elements, and electrodes and leads for monitoring in a wafer used for manufacturing thin-film magnetic heads of related art. In this example, thin-film magnetic head elements
101
are aligned in a plurality of rows in the wafer
100
. The head elements
101
each include: an element section
102
including an induction-type magnetic transducer and an MR element; and a plurality of electrodes
103
for electrically connecting the element section
102
to an external device. In the wafer
100
in the example shown in
FIG. 13
, between every adjacent head elements
101
in each row, there are a detection element
111
for detecting an amount of processing, two electrodes
112
a
and
112
b
for monitoring, and two leads
113
a
and
113
b
for monitoring that electrically connect the electrodes
112
a
and
112
b
to each other.
FIG. 14
shows another example of arrangement of detection elements, and electrodes and leads for monitoring in a wafer used for manufacturing thin-film magnetic heads of related art. This example may be the one disclosed in Japanese Patent Application Laid-open Hei 8-287424 (1996). In this example, as in the example shown in
FIG. 13
, the detection element
111
, the two electrodes
112
a
and
112
b
for monitoring, and the two leads
113
a
and
113
b
for monitoring are placed between every adjacent head elements
101
in each row in the wafer
100
. One of the electrodes
112
a
is used for grounding and functions as one of the electrodes
103
of the head element
101
as well.
In the example shown in
FIG. 13
, the detection element
111
, the electrodes
112
a
and
112
b
, and the leads
113
a
and
113
b
are placed between every adjacent head elements
101
in each row. As a result, the pitch of the head elements
101
in each row is increase by the space occupied by the detection element, the electrodes and the leads, compared to a case where none of these is placed between every adjacent head elements. Consequently, the number of thin-film magnetic head elements obtained from a given length of bar is reduced.
In the example shown in
FIG. 14
, compared to the one shown in
FIG. 13
, the pitch of the head elements
101
in each row is reduced and the number of thin-film magnetic head elements obtained from a given length of bar is thereby increased. However, in this example, too, the electrode
112
b
is additionally provided between every adjacent head elements
101
in each row. Therefore, the pitch of the head elements
101
in each row is still greater, and the number of head elements obtained from a given length of bar is reduced, compared to a case where the electrode
112
b
is not placed. In particular, since the electrode such as the electrode
112
b
is required to be connected to a bonding wire, it is necessary to maintain the electrode at a certain size. The pitch is therefore further required to be increased. For example, if the diameter of the bonding wire is about 30 &mgr;m, the length of one side of the electrode
112
b
is required to be about 100 &mgr;m.
In the example shown in
FIG. 14
, the electrode
112
a
functions as one of the electrodes
103
of the thin-film magnetic head element
101
, too. As a result, if the bar is cut at the detection element
111
for dividing the bar into head elements (sliders), part of the lead for monitoring remains exposed outside. The part of the lead may catch noises and cause static damage.
SUMMARY OF THE INVENTION
It is a first object of the invention to provide a thin-film magnetic head material and a method of manufacturing the same and a method of manufacturing thin-film magnetic heads to increase the number of thin-film magnetic heads to obtain.
It is a second object of the invention to provide a thin-film magnetic head material and a method of manufacturing the same and a method of manufacturing thin-film magnetic heads to fabricate thin-film magnetic heads in which no conductors connected to elements for detecting an amount of processing remain.
A thin-film magnetic head material of the invention includes: a plurality of rows of head-to-be sections to be thin-film magnetic heads; an inter-row cutting section provided to be a position at which adjacent ones of the rows are to be separated; and an intra-row cutting section provided to be a position at which adjacent ones of the head-to-be sections in each of the rows are to be separated. The head material compr
Itoh Hiroyuki
Sasaki Yoshitaka
Nguyen Tai Van
Oliff & Berridg,e PLC
TDK Corporation
Tugbang A. Dexter
LandOfFree
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