Etching a substrate: processes – Forming or treating article containing magnetically...
Reexamination Certificate
2002-10-23
2004-01-06
Mills, Gregory (Department: 1763)
Etching a substrate: processes
Forming or treating article containing magnetically...
C360S244000, C360S244100, C360S244200, C360S244300
Reexamination Certificate
active
06673256
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
2. Discussion of the Background
FIGS. 9 and 10
are respectively a perspective view and an exploded perspective view of a magnetic head suspension of a conventional type. As illustrated in these figures, a magnetic head suspension
100
of the conventional type includes, a flexure
110
having a stainless-steel substrate
111
for mounting a magnetic head slider (not illustrated) thereon and a wiring structure
112
integrally formed on the said stainless-steel substrate
111
, a load beam
120
with a load-bent portion for generating a force to press the magnetic head slider against a magnetic disk, and a base plate
130
for securing the magnetic head suspension to an arm (not illustrated), in which these component parts are welded together.
The wiring structure
112
of the flexure
110
includes a terminal pad
113
closer to the slider positioned at a distal end portion of the flexure wiring, a terminal pad
115
closer to the base plate positioned at a proximal end portion of the flexure, and a signal line portion
114
extending between said terminal pads closer to the slider and the base plate. While the terminal pad
113
closer to the slider is connected to a terminal of the magnetic head slider, the terminal pad
115
closer to the base plate is connected to a terminal of a relay FPC
140
that is, in turn, connected to a preamplifier IC.
In the recent tendency towards application of a MR head to a magnetic head, an MR device is used as a reading device, and an inductive device is used as a writing device. This arrangement usually needs the flexure wiring
120
with four wires (two for reading and two for writing).
FIGS.
11
(
a
) and
11
(
b
) are respectively vertical cross sections of a wiring integrated flexure of a general type, the former being a cross section of the signal line portion
114
of the wiring structure
112
of the flexure, the latter a cross section of the terminal pad
113
or
115
of the wiring structure
112
.
As illustrated in FIG.
11
(
a
), a portion of the flexure
110
corresponding to the signal line portion
114
includes a stainless-steel substrate
111
, a polyimide insulating layer
116
laminated on the said stainless-steel substrate
111
, a Cu-wiring-conductor layer
117
laminated on the said insulating layer, and a polyimide protection layer
118
covering the said wiring conductor layer. Usually, the polyimide insulating layer
116
and the Cu-wiring-conductor layer
117
respectively have a thickness of 5 to 10 &mgr;m and a thickness of 5 to 10 &mgr;m, while the polyimide protection layer
118
has a thickness of 1 to 3 &mgr;m on the wiring conductor layer. On the other hand, the terminal pads
113
and
115
of the wiring structure
112
of the flexure each define an opening
118
a
in the polyimide insulating layer
118
, through which the wiring conductor layer
117
is exposed.
In the above arrangement, polyimide used for the insulating layer
116
and the protection layer
118
has a different coefficient of thermal expansion from stainless steel. In addition, polyimide exhibits a moisture-absorption property. These factors may cause the variation of the mechanical characteristic, specifically the variation of the angle or the attitude angle of a slider-mounting region
111
b
of a gimbal portion
111
a
with regard to the load beam (see FIGS.
9
and
10
). Therefore, the thinner polyimide insulating layer and polyimide protection layer can stabilize the mechanical characteristics of the flexure.
On the other hand, when giving consideration to the electrical characteristics of the wiring structure, the thinner polyimide insulating layer is likely to be influenced by Eddy current flowing through the stainless-steel substrate, thereby disadvantageously increasing the resistance in the wiring structure. This increase in resistance of the wiring structure becomes more remarkable as the signal frequency becomes higher. The increase in the resistance of the wiring structure causes signals transmitting through the wiring structure to further decay, thereby hardly accomplishing a high-speed data transmission. In addition, the thinner polyimide insulating layer increases the capacitance between the wiring structure and the stainless-steel substrate. Such an increase in capacitance lowers the resonance frequency of a circuit system including a wiring structure and a magnetic head, where the length of the wiring structure is sufficiently short with regard to the signal wavelength. As a result, it is hard to read high-speed signals from and write the same to the magnetic disk.
Such increases in resistance and capacitance of the wiring structure accompanied by the thinner polyimide insulating layer can effectively be limited by selectively removing the portions of the stainless-steel substrate present below the wiring structure. Specifically, the capacitance in the wiring structure can be reduced by arranging opening portions below the wiring structure in the stainless-steel substrate. However, such opening portions greatly deteriorate the flexibility in mechanical designing of the flexure.
U.S. Pat. No. 5,739,982 discloses a flexure with the wiring conductor partly positioned sidewards of the stainless-steel substrate so as to limit the increase in resistance and capacitance of the wiring structure. This arrangement, however, poses a problem that the portion of the wiring conductor sidewards of the stainless-steel substrate is likely to be damaged or deformed by any other parts or matters, which are easily accessible to the wiring conductor sideways. As an additional problem in the flexure disclosed in the said U.S. patent publication, protrusions extending sidewards from the stainless-steel substrate for supporting the wiring conductor positioned sidewards of the stainless-steel substrate may deteriorate the flexibility in mechanical designing of the flexure.
The present invention has been conceived to solve these problems. It is an object of the invention to provide a wiring integrated flexure that is capable of avoiding deterioration of the flexibility in mechanical designing of the flexure, decreasing influences of the insulating layer over the mechanical characteristics of the flexure, and reducing resistance and capacitance of the wiring structure.
It is another object of the invention to provide a method of manufacturing such a wiring integrated flexure.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a wiring integrated flexure including a stainless-steel substrate for supporting a magnetic head slider thereon, a wiring conductor formed on the said stainless-steel substrate, posts made of a flexible resin and interposed between the stainless-steel substrate and the wiring conductor for electrically isolating the wiring conductor from the stainless-steel substrate, and the posts disposed along the lengthwise direction of the wiring conductor with spacing from each other.
The wiring integrated flexure of the above arrangement can achieve a reduction in capacitance in the wiring structure, prevention of the increase in resistance of the wiring structure in a high frequency signal region. In addition, the contacting area between the flexible resin and the stainless-steel substrate can be reduced so that the mechanical characteristics of the flexure is unlikely to be deteriorated, thereby providing an wiring integrated flexure having stabilized mechanical characteristics. Those effects are obtainable without defining openings in a region of the stainless-steel substrate below the wiring conductor, so that the flexibility in mechanical designing of the flexure is unlikely to be deteriorated. Further, the wiring conductor is not located sidewards of the stainless-steel substrate, but located within the stainless-steel substrate, so that any other parts or matters are unlikely to contact the wiring conductor from the lateral side or the lower side. Therefore, it is possible to effectively prevent the wiring conductor from being damaged or d
Culbert Roberts P
Mills Gregory
Perkins Coie LLP
Suncall Corporation
LandOfFree
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