Title: Magnetic head assembly having thin-film dummy patterns provided on surface of gimbal spring
Abstract: A magnetic head assembly equipped with a slider having a magnetic head and a gimbal spring on which the slider is mounted with an adhesive. The gimbal spring is supported by beam portions of a load beam. A thin-film wiring pattern formed on the load beam extends to a surface of the gimbal spring. A tip of the wiring pattern acts as a terminal portion that is connected to input/output terminals integrally formed on the slider. The slider is locked on the gimbal spring by electrically conducting bonding and an adhesive. A plurality of dummy patterns having the same height as the wiring pattern are provided at a position corresponding to where the adhesive is dropped on the surface of the gimbal spring. The adhesive is placed in an area sandwiched by the dummy patterns on the gimbal spring.
Patent Number: 6,940,694 Issued on 09/06/2005 to Ohwe, et al.
| Inventors:
|
Ohwe; Takeshi (Kawasaki, JP);
Watanabe; Toru (Kawasaki, JP);
Koishi; Ryosuke (Kawasaki, JP);
Yoneoka; Seizi (Kawasaki, JP)
|
| Assignee:
|
Fujitsu Limited (Kawasaki, JP)
|
| Appl. No.:
|
901063 |
| Filed:
|
July 29, 2004 |
Foreign Application Priority Data
| Current U.S. Class: |
360/234.6; 360/245.3; 360/245.8 |
| Intern'l Class: |
G11B 005/48 |
| Field of Search: |
360/2346,245.3,245.5,245.8,245.6
|
References Cited [Referenced By]
U.S. Patent Documents
| 4700250 | Oct., 1987 | Kuriyama.
| |
| 4761699 | Aug., 1988 | Ainslie et al.
| |
| 5003419 | Mar., 1991 | Takekado.
| |
| 5027238 | Jun., 1991 | Konishi et al.
| |
| 5161076 | Nov., 1992 | Inumochi et al.
| |
| 5282102 | Jan., 1994 | Christianson.
| |
| 5299080 | Mar., 1994 | Mizuno et al.
| |
| 5299081 | Mar., 1994 | Hatch et al.
| |
| 5377064 | Dec., 1994 | Yaginuma et al.
| |
| 5381289 | Jan., 1995 | Fiedler.
| |
| 5467236 | Nov., 1995 | Hatanai et al.
| |
| H1573 | Aug., 1996 | Budde.
| |
| 5550694 | Aug., 1996 | Hyde.
| |
| 5638234 | Jun., 1997 | Hagen.
| |
| 5696651 | Dec., 1997 | Endo et al.
| |
| 5719727 | Feb., 1998 | Budde.
| |
| 5786964 | Jul., 1998 | Sone et al.
| |
| 5864446 | Jan., 1999 | Endo et al.
| |
| 5901014 | May., 1999 | Hiraoka et al.
| |
| Foreign Patent Documents |
| 2-18770 | Jan., 1990 | JP.
| |
| 2-91867 | Mar., 1990 | JP.
| |
| 2-135914 | Nov., 1990 | JP.
| |
| 03-230315 | Oct., 1991 | JP.
| |
| 04-305877 | Oct., 1992 | JP.
| |
| 05-128771 | May., 1993 | JP.
| |
| 5-128772 | May., 1993 | JP.
| |
| 5-79764 | Oct., 1993 | JP.
| |
| 5-303856 | Nov., 1993 | JP.
| |
| WO 83/0186/2 | May., 1983 | WO.
| |
Other References
Hutchinson Technology, Inc., "Type 1650 Product Summary", Sep. 14, 1992, pp. 1-9.
Patent Abstracts of Japan for Publication No. 05-128771, Published May 25, 1993;
Pub. No. 04-305877, Published Oct. 28, 1992, and Pub. No. 03-230315, Published
Oct. 14, 1991.
|
Primary Examiner: Renner; Craig A.
Attorney, Agent or Firm: Arent Fox PLLX
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This is a Division of application Ser. No. 08/901,940 filed Jul. 29, 1997, now
U.S. Pat. No. 6,801,398, which in turn is a Continuation Application of Parent
Application No. 08/352,926 filed Dec. 9, 1994 now abandoned. The disclosures of
the prior applications are hereby incorporated by reference herein in their entirety.
Claims
1. A magnetic head assembly comprising a slider having a magnetic head for reading
data from, and writing data onto, a magnetic recording medium, and a gimbal spring
on which said slider is mounted with an adhesive agent, wherein:
said gimbal spring is formed integrally with a load beam, and is supported by
said load beam via beam portions;
a thin-film wiring pattern formed on said load beam is extended to a surface
of said gimbal spring via said beam portions and is formed on said surface, the
tip of said wiring pattern serves as a terminal portion corresponding to the position
of input/output terminals of the magnetic head that is integrally formed on the
tip of said slider, the input/output terminals of said slider and the terminal
portion of said wiring pattern are connected together by electrically conducting
bonding, and said slider is locked on said gimbal spring at two points by the electrically
conducting bonding and by said adhesive agent; and
a plurality of thin-film dummy patterns having the same height as the height
of said wiring pattern are provided at a position where said adhesive agent will
be dropped on said surface of said gimbal spring, and said adhesive agent is dropped
in the area sandwiched by said thin-film dummy patterns on said gimbal spring.
2. A magnetic head assembly according to claim 1, wherein the material of said
gimbal spring is SUS, and the Young's modulus after hardening of the adhesive agent
is smaller than about 1/3000 of the Young's modulus of the gimbal spring material.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic head assembly. More particularly,
the invention relates to a magnetic head assembly which is used for a magnetic
disk drive, and is made up of a slider having a magnetic head for reading data
from, and writing data onto, a magnetic disk, the slider being mounted on a gimbal
spring with an adhesive agent.
2. Description of the Related Art
In recent years, magnetic disk drives have been realized in ever smaller sizes
and in ever lighter weights having both decreased volume and decreased height.
In order to place many disks and heads in such a compact device, attempts have
been made to reduce the gap among the disks and to fabricate a magnetic head-support
mechanism in a small size and in a reduced thickness. Therefore, a slider for mounting
the magnetic head has a decreased size in outer diameter and a decreased thickness.
At present, the slider has a length, width and thickness which are all nearly halved
and has a volume which is about one-eighth compared with that of sliders of ten
years ago.
Even in a small and light magnetic disk drive, it has been demanded to increase
the recording density of the disk accompanying an increase in the amount of data
to be stored. This fact requires the gap to be narrowed between the slider mounting
the magnetic head and the slider. Therefore, it has been desired to provide a slider
having stabilized flying performance and, hence, to provide a slider having a more
accurate shape that is little deformed by a change in the ambient temperature.
In a conventional magnetic disk drive, a magnetic disk having a diameter of,
for
example, 3.5 inches and a head-positioning actuator are incorporated in an enclosure.
The actuator is provided with a swinging arm, and a magnetic head assembly is mounted
on the tip of the arm. The magnetic head assembly is constituted by a load beam
made of a stainless steel, a slider incorporating a magnetic head, and a gimbal
spring interposed between the slider and the load beam.
The gimbal spring may often be provided in a tip portion of the load beam integrally
therewith. In such a case, the gimbal spring is integrally formed in the load beam
being partitioned by two opposing U-shaped holes formed in the tip portion of the
load beam. That is, the gimbal spring is supported by the load beam via a pair
of beam portions formed between the opposing ends of U-shaped holes.
The slider is mounted on the gimbal spring using an adhesive agent. By using
a dispenser, the adhesive agent is dropwisely applied to the gimbal spring and,
then, the slider is mounted being forced into contact with the adhesive agent.
As the slider is realized in a small size to safisfy the tendency toward decreasing
the size and weight of the magnetic disk drive and increasing the reliability,
however, the adhesion area becomes very small between the slider and the gimbal
spring. This makes it difficult to accurately control the amount of the adhesive
agent applied by using the dispenser. If the amount of the adhesive agent happens
to become large, therefore, the adhesive agent applied to the adhesion surface
of the gimbal spring spreads between the gimbal spring and the adhesion surface
of the slider when the slider is adhered thereto with a pushing force. As a result,
the slider is adhered to the gimbal spring over an increased area and is deformed,
when the adhesive agent is hardened.
SUMMARY OF THE INVENTION
The object of the present invention therefore is to provide a magnetic head assembly
which is capable of confining the warping amount which is one of the shaping parameters
of the slider that affects the floating performance within an allowable range despite
a change in the temperature around the slider, in order to stabilize the floating
performance of the slider.
According to a first aspect of the present invention, there is provided
a magnetic head assembly comprising a slider with a magnetic head and a gimbal
spring on which the slider is mounted with an adhesive agent, wherein at least
a slit is formed in a slider-mounting portion of the gimbal spring opposing the
adhesion surface of the slider.
In the magnetic head assembly according to the first aspect, the gimbal spring
is formed integrally with the load beam or is attached to a tip portion of the
load beam. When the gimbal spring is formed integrally with the load beam, the
slider-mounting portion is supported by the load beam via a pair of beam portions.
When the gimbal spring is attached to the tip portion of the load beam, the gimbal
spring is constituted by an outer plate portion and a tongue-shaped inner plate
portion surrounded by a U-shaped hole.
Depending upon the shape of the slit formed in the gimbal spring, the amount
of the adhesive agent dropping on the gimbal spring can be controlled, so that
the slider is suitably adhered onto the gimbal spring.
According to a second aspect of the present invention, there is provided
a magnetic head assembly comprising a slider with a magnetic head and a gimbal
spring on which the slider is mounted with an adhesive agent, wherein the adhesive
agent applied onto the adhesion surface of the slider after hardened has a Young's
modulus which is smaller than about 1/13000 the Young's modulus of the slider material
or smaller than about 1/13000 the Young's modulus of the gimbal spring material.
In this case, the Young's modulus of the slider material may be nearly the same
as the Young's modulus of the gimbal spring material.
In the magnetic head assembly according to the first aspect of the present invention,
the adhesive agent applied onto the gimbal spring from the dispenser is prevented
from spreading beyond the slit at least one of which is formed in the gimbal spring,
when the slider is adhered with pushing force and, hence, the area on which the
adhesive agent is applied is limited. As a result, even when the slider and the
gimbal spring have different coefficients of linear expansion, the warping amount
of the slider caused by a change in the temperature can be suppressed to lie within
a predetermined range since the contact area is small between the slider and the
gimbal spring, and the flying height of the slider can be stabilized.
In the magnetic head assembly according to the second aspect of the present invention,
the adhesive agent adhering to the slider and the gimbal spring together exhibits
a very small Young's modulus after it is hardened. Therefore, the warping amount
of the slider is suppressed to a small value irrespective of a change in the temperature
around the slider, and the flying height of the slider due to a change in the temperature
can be stabilized.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be more clearly understood from the description as
set forth below with reference to the accompanying drawings, wherein:
FIG. 1 is a plan view illustrating the whole constitution of a conventional
magnetic disk drive;
FIG. 2A is a perspective view of an assembly explaining how to mount a slider
on a load beam shown in FIG. 1;
FIG. 2B is a sectional view along the line P—P in FIG. 2A;
FIG. 3A is a perspective view illustrating the state where the slider of FIG.
2A is mounted on the load beam;
FIG. 3B is a sectional view along the line Q—Q in FIG. 3A;
FIG. 4A is a diagram explaining an example of warping by the bimetal effect
of a head assembly;
FIG. 4B is a diagram explaining another example of warping by the bimetal effect
of the head assembly;
FIG. 4C is a diagram illustrating a relationship between the adhesion area and
the initial warping amount of the slider;
FIG. 5 is a diagram illustrating changes in the warping amount and in the flying
height of the slider in the head assembly;
FIG. 6A is a perspective view of a fundamental constitution of the head assembly
according to a first aspect;
FIG. 6B is a sectional view along the line A—A of FIG. 6A;
FIG. 7 is a plan view of a first embodiment of the shape of a slit according
to the first aspect;
FIG. 8 is a diagram showing a relationship between the adhesion area of the
slider and the initial flying height of the slider;
FIG. 9A is a diagram illustrating a second embodiment of the shape of a slit
formed in the gimbal spring;
FIG. 9B is a diagram illustrating a third embodiment of the shape of a slit
formed in the gimbal spring;
FIG. 9C is a diagram illustrating a fourth embodiment of the shape of a slit
formed in the gimbal spring;
FIG. 9D is a diagram illustrating a fifth embodiment of the shape of a slit
formed in the gimbal spring;
FIG. 9E is a diagram illustrating a sixth embodiment of the shape of a slit
formed in the gimbal spring;
FIG. 9F is a diagram illustrating a seventh embodiment of the shape of a slit
formed in the gimbal spring;
FIG. 9G is a diagram illustrating an eighth embodiment of the shape of a slit
formed in the gimbal spring;
FIG. 9H is a diagram illustrating a ninth embodiment of the shape of a slit
formed in the gimbal spring;
FIG. 9I is a diagram illustrating a tenth embodiment of the shape of a slit
formed in the gimbal spring;
FIG. 9J is a diagram illustrating an eleventh embodiment of the shape of a slit
formed in the gimbal spring;
FIG. 9K is a diagram illustrating a twelfth embodiment of the shape of a slit
formed in the gimbal spring;
FIG. 9L is a diagram illustrating a thirteenth embodiment of the shape of a
slit formed in the gimbal spring;
FIG. 9M is a diagram illustrating a fourteenth embodiment of the shape of a
slit formed in the gimbal spring;
FIG. 9N is a diagram illustrating a fifteenth embodiment of the shape of a slit
formed in the gimbal spring;
FIG. 10A is a perspective view illustrating a modified embodiment of the constitution
of the head assembly according to the first aspect;
FIG. 10B is a sectional view along the line B—B of FIG. 10A;
FIG. 11A is a diagram illustrating a shape of a slit which is a modification
from the first embodiment of the first aspect;
FIG. 11B is a diagram illustrating a shape of a slit which is a modification
from the second embodiment of the first aspect;
FIG. 11C is a diagram illustrating a shape of a slit which is a modification
from the third embodiment of the first aspect;
FIG. 11D is a diagram illustrating a shape of a slit which is a modification
from the fourth embodiment of the first aspect;
FIG. 11E is a diagram illustrating a shape of a slit which is a modification
from the fifth embodiment of the first aspect;
FIG. 11F is a diagram illustrating a shape of a slit which is a modification
from the sixth embodiment of the first aspect;
FIG. 11G is a diagram illustrating a shape of a slit which is a modification
from the seventh embodiment of the first aspect;
FIG. 12A is a plan view of the load beam in the head assembly according to a
second aspect;
FIG. 12B is a side view illustrating the state where the adhesive agent is applied
between the gimbal spring and the head of FIG. 12A;
FIG. 13A is a diagram of characteristics showing Young's modulus after hardening
of the adhesive agent used in the second aspect of the present invention and warping
amount of the slider;
FIG. 13B is a diagram of characteristics showing a relationship between the
warping amount of the slider and the flying height of the slider;
FIG. 14 is a perspective view illustrating the constitution of the existing
head assembly to which the present invention is adapted;
FIG. 15 is a diagram illustrating a first example in which the first aspect
of the present invention is adapted to the head assembly of FIG. 14;
FIG. 16 is a diagram illustrating a second example in which the first aspect
of the present invention is adapted to the head assembly of FIG. 14;
FIG. 17 is a diagram illustrating a third example in which the first aspect
of the present invention is adapted to the head assembly of FIG. 14;
FIG. 18 is a diagram illustrating an example in which the first aspect of the
present invention is adapted to the head assembly which is constituted by mounting
an independent cantilevered gimbal spring on the tip portion of the load beam;
FIG. 19 is a sectional view of the magnetic head assembly along the line C—C
in FIG. 18; and
FIG. 20 is a perspective view illustrating the other constitution of the existing
head assembly to which the present invention is adapted wherein the gimbal spring
is provided in a tip portion of the load beam integrally therewith.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Before describing the preferred embodiments, an explanation will be given
of the conventional magnetic head assembly of a magnetic disk drive shown in FIGS.
1 to
5.
FIG. 1 illustrates the constitution of a conventional magnetic disk drive
220
which includes a magnetic disk
222 of a diameter of, for example, 3.5 inches
and a head-positioning actuator
223 that are contained in an enclosure
221.
The actuator
223 is provided with a swing arm
224 which has a magnetic
head assembly
225 mounted on a tip portion thereof. The magnetic head assembly
225 is constituted by a load beam
226 made of a stainless steel,
a slider
227 in which a magnetic head is incorporated, and a gimbal spring
228 interposed between the slider
227 and the load beam
226.
FIG. 2A illustrates the constitution of the magnetic head assembly
225
shown in FIG.
1. In this example, the gimbal spring
228 is provided
in a tip portion of the load beam
226 integrally therewith. That is, the
gimbal spring
228 is formed integrally with the load beam
226 being
partitioned by two opposing U-shaped holes
226a and
226b
that are formed in the tip portion of the load beam
226. A pair of beam
portions
228a and
228b are formed between the opposing
ends of the U-shaped holes
226a and
226b, and the gimbal
spring
226 is supported by the load beam
226 via the pair of beam
portions
228a and
228b.
The slider
227 is mounted on the gimbal spring
228 by using an
adhesive agent
229. As shown in FIG. 2B, the adhesive agent
229 is
permitted to drop from a dispenser that is not shown on the gimbal spring
228
and is applied thereto. The slider
227 is contacted to the gimbal spring
228 with a pushing force via the adhesive agent
229 and is mounted thereon.
FIGS. 3A and 3B illustrate a state where the slider
227 is mounted on
the gimbal spring
228 in a manner as shown in FIGS. 2A and 2B. This example
illustrates a case where a wiring pattern is formed on the gimbal spring
228
integrally therewith by a thin film-forming method or a similar method. A thin-film
wiring pattern is formed on the gimbal spring
228 in order to electrically/mechanically
connect the wiring pattern to the input/output terminals of the magnetic head of
the slider
227. Moreover, the gold-ball bonding (hereinafter referred to
as gold ball)
230 is applied to an end portion on the flow-out side of the
slider
227.
However, as the slider
227 is realized in a small size, with the
trend toward fabricating magnetic disk drives in a small size and in a light weight
as well as toward realizing improved reliability, the adhesion area becomes very
small between the slider
227 and the gimbal spring
228. The amount
of the adhesive agent cannot be precisely controlled by the dispenser. When the
adhesive agent
229 is applied in a large amount on a small adhesion area,
therefore, the adhesive agent
229 applied onto the adhesion surface of the
gimbal spring
227 spreads on the gimbal spring
228 when the slider
227 is mounted thereon with the application of pushing force. Then, the
adhesion area of the slider
227 increases with respect to the gimbal spring
228, and the slider undergoes deformation accompanying a change in the temperature.
This problem will be described below in further detail.
Described below is a case where the slider
227 is made, for example,
of altic (Al
2O
3TiC) and the gimbal spring
228 is made,
for example, of SUS, the two having large adhesion areas. In this case, when the
temperature of the drive rises as it is being operated, the bimetal effect is exhibited
due to a difference in the coefficient of linear expansion between the slider
227
and the gimbal spring
228, and the slider warps. When the gold ball
230
has been applied to the slider
227, furthermore, a change in the warping
amount due to the bimetal effect becomes more conspicuous since the slider
227
and the gimbal spring
228 are locked together not only by the adhesive agent
229 but also by the gold ball
230. FIGS. 4A and 4B illustrate warping
amounts due to the bimetal effect.
As shown in FIG. 4C, the warping amount varies depending upon the adhesion area
between the slider
227 and the gimbal spring
228 and upon the presence
or absence of the gold ball
230. A change in the warping amount and particularly
in the warping amount in the lengthwise direction of the slider affects the flying
heights at the flow-in end and flow-out end of the slider
227 as shown in
FIG.
5. This adversely affects the reading of data or writing of data by
the magnetic head. Accordingly, it is necessary to reduce the change in the warping
amount of the slider caused by a change in the temperature.
FIG. 6A illustrates the constitution of the magnetic head assembly
10
according to a first aspect of the present invention. In this embodiment, the gimbal
spring
1 is formed in a tip portion of the load beam
2 integrally
therewith. That is, the gimbal spring
1 is formed in the load beam
2
integrally therewith being partitioned by two opposing U-shaped holes
4
and
5 that are formed in the tip portion of the load beam
2. The
gimbal spring
1 is supported by the load beam
2 via a pair of beam
portions
6 and
7 formed between the opposing ends of the U-shaped
holes
4 and
5. Two slits
11 are formed in the gimbal spring
1 in such a manner as to divide the gimbal spring
1 into three equal
portions in the axial direction of the load beam
2.
The two slits
11 work to control the adhesion area between the gimbal
spring
1 and the slider
3 mounted on the gimbal spring
1.
That is, the two slits
11 reduce a difference in the thermal expansion and
contraction between the gimbal spring
1 and the slider
3 in the lengthwise
direction of the slider and suppress the occurrence of the bimetal effect. Therefore,
the slits
11 are arranged to be elongated in the transverse direction of
the slider
3 that is adhered onto the gimbal spring
1 such that the
adhesive agent-applied area of the gimbal spring
1 becomes smaller than
the adhesion surface of the slider
3 against which it is opposed. This embodiment
deals with the case where the gimbal spring
1 opposed to the adhesion surface
of the slider
3 has an adhesion area which is larger than the adhesion area
of the slider
3.
An adhesive agent
8 is used for mounting the slider
3 on the gimbal
spring
1. FIG. 6B is a sectional view of when the cross section of FIG.
6A along the line A—A is viewed from the direction of arrow. As shown in
FIG. 6B, the adhesive agent
8 is applied by using a dispenser that is not
shown onto a region between the two slits
11 formed in the gimbal spring
1, and the slider
3 is pushed onto the adhesive agent
8 and
is mounted. FIG. 6B shows a gold ball
9 at an end of the slider
3.
The gold ball
9 is necessary in the embodiments described later with reference
to FIG.
14 and subsequent drawings, but is not particularly needed in the
embodiments of from FIGS. 6A to
13B and is not described here in detail.
FIG. 7 is a plan view of the tip portion of the load beam
2 on an enlarged
scale showing a first embodiment of the arrangement of slits
11 in the gimbal
spring
1 that was explained with reference to FIGS. 6A and 6B. In this embodiment,
the same constituent members as those of FIGS. 6A and 6B are denoted by the same
reference numerals. That is, reference numeral
1 denotes the gimbal spring,
2 denotes the load beam,
4 and
5 denote U-shaped holes, and
6 and
7 denote the pair of beam portions. In this embodiment, V-shaped
holes
21 and
22 are formed on the outsides of the opposing U-shaped
holes
4 and
5, and the beam portions
6 and
7 are formed
nearly in a T-shape. Both ends of the transverse bars of the nearly T-shaped beam
portions
6 and
7 are connected to the load beam
2, and lower
ends of longitudinal bars of T are connected to the gimbal spring
1. The
nearly T-shaped beam portions
6 and
7 are formed such that the slider-mounting
portion is reliably displaced in the rolling direction and in the pitching direction.
This function has been described in detail in a prior application (U.S. Ser. No.
08/110,771) and is not described here in detail.
FIG. 8 is a diagram illustrating a relationship between the adhesion area of
the slider
3 and a change from the initial flying height. From FIG. 8, it
is desired that the areas of the two slits
11 formed in the gimbal spring
1 are smaller than 60% and, preferably, smaller than about 30% of a suitable
bonding area between the slider
3 and the gimbal spring
1, e.g.,
of the adhesion area of the slider.
Even in the gimbal spring
1 shown in FIG. 7, the adhesive agent is dropwisely
applied onto a region between the two slits
11 from the dispenser and, then,
the slider
3 is contacted with a pushing force and is bonded to the gimbal
spring
1. In this case, the adhesive agent spreads between the slider
3
and the gimbal spring
1. Even when the adhesive agent is applied in a large
amount, however, the adhesive agent is prevented from spreading by the slits
11
and does not spread any more.
As the adhesive agent is hardened in this state, the adhesion area is suppressed
to be small between the gimbal spring
1 and the slider
3. Even when
the gimbal spring
1 and the slider
3 contract by different lengths
due to a change in the temperature, this difference is reduced by the adhesive
agent of a small area. As a result, no large change occurs in the warping amount
of the slider
3.
FIGS. 9A to
9N illustrate shapes of at least one slit
11 formed
in the gimbal spring
1 of FIG. 7 according to second to fifteenth embodiments.
The slit
11 need not be formed at a central portion of the gimbal spring
1 but may be so formed as to bite from the side portions of the gimbal spring
1. Moreover, the slit
11 need not be of a linear shape but may be
folded at any point thereof or may be curved.
FIG. 9A illustrates an example in which a linear slit
11 is formed on
the front side of the gimbal spring
1 and slits
11A are formed on
the rear side of the gimbal spring
1 biting therein from the side ends thereof.
FIG. 9B illustrates an example in which slits
11A are formed on both the
front side and the rear side of the gimbal spring
1 biting therein from
the side ends thereof. FIG. 9C illustrates an example in which a linear slit
11
is formed on the rear side of the gimbal spring
1 and slits
11A are
formed on the front side of the gimbal spring
1 biting therein from the
side ends thereof. FIG. 9D illustrates an example in which two parallel slits
11B
are formed in the gimbal spring
1 running in an oblique direction. FIG.
9E illustrates an example in which two curved slits
11C are formed in the
gimbal spring
1. FIG. 9F illustrates an example in which U-shaped slits
11D are formed in the gimbal spring
1 with their vertexes opposed
to each other.
FIGS. 9G and 9H illustrate examples in which slits
11E are formed in
the gimbal spring
1 being slanted in the back-and-forth direction. FIG.
9I illustrates an example in which semicircular slits
11F are formed being
opposed to each other. FIG. 9J illustrates an example in which three short and
arcuate slits
11G are formed. FIGS. 9K to
9N illustrate examples
illustrating combinations of three short and linear slits
11H.
In the foregoing were described various arrangements of slits
11 formed
in the gimbal spring
1. The slits
11, however, can be arranged in
a variety of other ways in addition to the aforementioned embodiments, and the
present invention is in no way limited to these embodiments only.
FIG. 10A illustrates a constitution of the magnetic head assembly
10
which is a modification from the first embodiment of the present invention shown
in FIG.
6A. Even in this embodiment, the gimbal spring
1 is formed
in the load beam
2 integrally therewith being partitioned by two opposing
U-shaped holes
4 and
5 formed in the tip portion of the load beam
2, and is supported by the load beam
2 via a pair of beam portions
6 and
7 formed between the opposing ends of the U-shaped holes
4
and
5. What makes this embodiment different from the embodiment of FIG.
6A is the size of the gimbal spring
1 with respect to the slider
3.
In the embodiment of FIGS. 6A and 6B, the adhesion surface of the gimbal spring
1 opposing the adhesion surface of the slider has an area larger than the
area of the adhesion surface of the slider
3. In the embodiment of FIGS.
10A and 10B, on the other hand, the area of the adhesion surface of the gimbal
spring
1 opposing the adhesion surface of the slider
3 is smaller
than the area of the adhesion surface of the slider
3. In this embodiment,
furthermore, a slit
11 is formed in the gimbal spring
1 in a direction
at right angles to the axial direction of the load beam
2.
In the case of this embodiment, the gimbal spring
1 is cut on the side
of the base portion of load beam
2 with respect to the pair of beam portions
6 and
7. The gimbal spring
1 is cut roughly at a portion of
the slit
11 on the side of the base portion of load beam
2 shown
in FIG.
6A. FIG. 10B is a sectional view of when the cross section along
the line B—B of FIG. 10A is viewed from the direction of arrow. The adhesive
agent
8 is allowed to drop from the dispenser onto a region between the
slit formed in the gimbal spring
1 and the end on the cut side of the gimbal
spring
1 as shown in FIG.
10B. The slider
3 is contacted with
a pushing force to the gimbal spring
1 via the adhesive agent
8 and
is mounted thereon. FIG. 10B also shows the gold ball
9 at an end on the
front side of the slider
3. As described earlier, however, the gold ball
9 is not particularly needed in this embodiment and is not described here
in detail.
In this case, the area of the gimbal spring
1 on the cut side up to the
slit
11 should be smaller than 60% (preferably, about 30%) of a suitable
bonding area between the slider
3 and the gimbal spring
1, i.e.,
of the adhesion area of the slider. The adhesive agent
8 is dropwisely applied
from the dispenser onto this portion and, then, the slider
3 and the gimbal
spring
1 are bonded together. Though the adhesive agent
8 spreads
between the slider
3 and the gimbal spring
1, spread of the adhesive
agent
8 heading toward the slit
11 is blocked by the slit
11
and does not spread any more toward the front side. Accordingly, the adhesion area
can be controlled by cutting the gimbal spring
1 with the slit
11
formed in the gimbal spring
1 as a boundary.
FIG. 11A is a plan view of the tip portion of the load beam
2 on an enlarged
scale illustrating an embodiment of the arrangement of the slit
11 in the
gimbal spring
1 that is explained with reference to FIGS. 10A and 10B. In
this embodiment, the same constituent members as those of FIGS. 10A and 10B are
denoted by the same reference numerals. That is, reference numeral
1 denotes
the gimbal spring,
2 denotes the load beam,
4 and
5 denote
U-shaped holes, and
6 and
7 denote the pair of beam portions. Even
in this embodiment, V-shaped holes
21,
22 are formed on the outsides
of the opposing U-shaped holes
4 and
5, and the beam portions
6
and
7 are formed nearly in a T-shape. Both ends of the transverse bars of
the nearly T-shaped beam portions
6 and
7 are connected to the load
beam
2, and lower ends of longitudinal bars of T are connected to the gimbal
spring
1. The nearly T-shaped beam portions
6 and
7 are formed
such that the slider-mounting portion is reliably displaced in the rolling direction
and in the pitching direction as described earlier.
Even in the gimbal spring
1 shown in FIG. 11A, the adhesive agent is
dropwisely applied from the dispenser onto a portion of the gimbal spring
1
on the side of the base portion of load beam
2 up to the slit
11
and, then, the slider
3 is contacted with a pushing force and is bonded
to the gimbal spring
1. In this case, the adhesive agent spreads between
the slider
3 and the gimbal spring
1. Even when the adhesive agent
is applied in a large amount, however, the adhesive agent is prevented from spreading
at the position of slit
11 and does not spread any further.
As the adhesive agent is hardened in this state, the adhesion area is suppressed
to be small between the gimbal spring
1 and the slider
3. Even when
the gimbal spring
1 and the slider
3 contract by different lengths
due to a change in the temperature, this difference does not effect each other.
Therefore, no large change occurs in the warping amount of the slider
3.
FIGS. 11B to
11G illustrates shapes of at least one slit
11 formed
in the gimbal spring
1 shown in FIG. 11A according to second to seventh
embodiments. The slit
11 needs not be formed at the central portion of the
gimbal spring
1 but may be formed to bite into the gimbal spring
1
from the side edges thereof. Moreover, the slit
11 needs not be of a linear
shape but may be folded at anywhere thereof or may be curved.
FIG. 11B illustrates an example in which slits
11A are formed biting
into the gimbal spring
1 from the side ends thereof. FIG. 11C illustrates
an example in which a linear slit
11 is formed on the front side of the
gimbal spring
1 in addition to slits
11A of FIG.
11B. FIGS.
11C to
11G illustrate a variety of examples in which two slits
11
are formed in the gimbal spring
1. FIG. 11D illustrates an example in which
slits
11A are formed biting on the front side in addition to the slit
11
of FIG.
11A. FIG. 11E illustrates an example having a linear and short slit
11H which is a linear and long slit
11 of FIG.
11D and slits
11A that deeply bite into the gimbal spring
1 from side ends thereof
on the front side. FIG. 11F illustrates an example in which the slits
11A
and
11H are arranged in a manner opposite to FIG. 11E, and FIG. 11G illustrates
an example in which two long slits
11A′ are formed biting deeply
from the side edges thereof nearly to the opposite side edges thereof.
In any one of the above-mentioned embodiments, the adhesion area between the
slider
3 and the gimbal spring
1 can be controlled by cutting the gimbal
spring
1 by an area which is smaller than 60% of a suitable bonding area
between the slider
3 and the gimbal spring
1, i.e., smaller than
60% of the adhesion area of the slider with the slide
11 in the gimbal spring
1 on the side of the load beam
2 as a boundary. This makes it possible
to reduce a difference in the expansion or contraction caused by the thermal expansion
of the slider
3 and the gimbal spring
1. The adhesion area between
the slider
3 and the gimbal spring
1 can be further controlled by
bringing the position of the slit toward the cut side in a state where the gimbal
spring
1 is cut.
FIGS. 12A and 12B illustrate a magnetic head assembly
20 of an embodiment
according to the second aspect of the present invention, wherein FIG. 12A illustrates
the constitution of the gimbal spring
1 and the load beam
2 of the
second aspect. Even in this embodiment, the same constituent members as those of
FIGS. 6A and 6B are denoted by the same reference numerals. That is, reference
numeral
1 denotes the gimbal spring,
2 denotes the load beam,
4
and
5 denote U-shaped holes, and
6 and
7 denote the pair of
beam portions. Even in this embodiment, V-shaped holes are formed on the outsides
of the opposing U-shaped holes
4 and
5, and the beam portions
6
and
7 are formed nearly in a T-shape. Both ends of the transverse bars of
the nearly T-shaped beam portions
6 and
7 are connected to the load
beam
2, and lower ends of longitudinal bars of T are connected to the gimbal
spring
1. The nearly T-shaped beam portions
6 and
7 are formed
such that the slider-mounting portion is reliably displaced in the rolling direction
and in the pitching direction as described earlier.
In this embodiment, the slider
3 is made of generally used Al
2O
3TiC
and the gimbal spring
1 is made of generally used SUS. In order to fasten
them together, this embodiment uses an adhesive agent which after hardened exhibits
a Young's modulus of, for example, about 9.8×10
3 mN/mm
2.
As shown in FIG. 12B, the adhesive agent is applied between the head
3 and
the gimbal spring
1. The thickness of the adhesive agent
8 is about
5 μm when they are fastened together. The slider
3 that is used has
a length of about 2 mm, a width of 1.6 mm and a thickness of 0.43 mm.
On the other hand, there has heretofore been used an adhesive agent
8
which
after hardening exhibits a Young's modulus of about 9.8×10
4 mN/mm
2
for the combination of the gimbal spring
1 and the slider
3
of the same sizes and of the same materials.
By using the adhesive agent used in the second aspect of the present invention
and the conventional adhesive agent, the warping amount of the slider was simulated
under the conditions in which the temperature of the magnetic disk drive was changed
by 50° C., and the following results were obtained.
(1) The warping amount was 43 nm when there was used the adhesive agent which
after hardened exhibited a Young's modulus of 9.8×10
4 mN/mm
2.
(2) The warping amount was 6 nm when there was used the adhesive agent which
after hardened exhibited a Young's modulus of 9.8×10
3 mN/mm
2.
Here, a change in the temperature was set to be 50° C. to represent a
difference between normal temperature and a maximum temperature for which the magnetic
disk drive is guaranteed. Moreover, the warping amount is defined to be a difference
between a height at a central position of the slider
3 and a height at the
slider edge.
FIG. 13A is a diagram illustrating the simulated results of changes in the warping
amount of the slider with the Young's modulus of the adhesive agent after hardening
as a parameter, and FIG. 13B is a diagram illustrating the simulated results of
changes in the flying height of the slider with the warping amount on the rail
surface of the slider as a parameter. It will be understood from these drawings
that the warping amount of the slider increases with an increase in the Young's
modulus of the adhesive agent after hardened, i.e., warping of the slider is very
much dependent upon the Young's modulus of the adhesive agent after hardening.
It will further be understood that the flying height of the slider is very much
dependent upon the warping of the slider.
From the standpoint of reading and writing characteristics of the magnetic head
and of designing floating performance maintaining reliability, a change in the
flying height must be suppressed to be within 5% when the temperature of the slider
has changed. For this purpose, the warping amount of the slider must be suppressed
to be within 10 nm from FIG.
13B. From FIG. 13A, furthermore, the slider
and the gimbal spring must be fastened together by using the adhesive agent which
after hardening exhibits a Young's modulus of not larger than 1.6×10
4
mN/mm
2 in order to suppress the warping amount of the slider within
10 nm. This value is about 1/13000 of the Young's modulus of SUS forming the gimbal
spring which is smaller than the Young's modulus of altic which forms the slider.
Thus, by selecting the Young's modulus of the adhesive agent after hardening
to be smaller than about 1/13000 the Young's modulus of the slider material or
the gimbal spring material whichever is smaller, the warping amount of the slider
can be suppressed to be smaller than a desired value of about 10 nm, and a change
in the flying height of the slider can be suppressed to be within 5%.
By selecting the slider material and the gimbal spring material having nearly
the same coefficient of linear expansion, furthermore, the slider is prevented
from warping despite the fact that the temperature is changed. In general, the
material of the gimbal spring must have resiliency and, hence, SUS or the like
is usually used. By taking the coefficient of linear expansion of SUS into account,
therefore, zirconia or the like is suitable for forming the slider.
FIG. 14 illustrates the constitution of a magnetic head assembly
30 disclosed
in Japanese Patent Application No. 82110/1993 (U.S. Ser. No. 08/110,771). Even
in this constitution, the same constituent members as those of the aforementioned
embodiment are denoted by the same reference numerals. That is, reference numeral
1 denotes the gimbal spring,
2 denotes the load beam,
3 denotes
the slider,
4 and
5 denote U-shaped holes, and
6 and
7
denote the pair of beam portions. Even in this embodiment, V-shaped holes are formed
on the outsides of the opposing U-shaped holes
4 and
5, and the beam
portions
6 and
7 are formed nearly in a T-shape. Both ends of the
transverse bars of the nearly T-shaped beam portions
6 and
7 are
connected to the load beam
2, and lower ends of longitudinal bars of T are
connected to the gimbal spring
1. The nearly T-shaped beam portions
6
and
7 are formed such that the slider-mounting portion is reliably displaced
in the rolling direction and in the pitching direction as described earlier. In
this constitution, furthermore, reference numerals
31 and
32 denote
holes for mounting jigs, and
33 denote a hole for fastening the load beam
2.
What makes the magnetic head assembly
30 of this constitution different
from the above-mentioned magnetic head assembles
10 and
20 is that
a wiring pattern
12 is formed on the surface of the load beam
2.
The wiring pattern
12 is provided to take out signals from the magnetic
head
3A provided in the slider
3. One end of the wiring pattern
12
is connected to terminals
13 provided at an end of the gimbal spring
1
and the other end thereof is connected to output terminals
14 provided near
the base portion of the load beam
2. The wiring pattern
12 runs from
the connection terminals
13 onto the load beam
2 passing through
the beam portions
6 and
7, and arrives at the output terminals
14
detouring the holes
31 and
32.
The connection terminals
13 provided at the end of the gimbal spring
1
correspond to terminals
3B provided at an end of the slider
3, and
are made contiguous to the terminals
3B when the slider
3 is mounted
on the gimbal spring
1. In a state in which the slider
3 is mounted
on the gimbal spring
1, the terminals
3B of the slider and the connection
terminals on the gimbal spring
1 are connected together by the gold ball
9 shown in FIG.
6B.
The wiring pattern
12 is formed by, for example, patterning a plated thin
copper film by photolithography, and has a thickness of about 5 μm and a
width of about 50 μm. The thickness and width of the wiring pattern are determined
by the resistance of the conductor pattern and by the capacity of the load beam
2.
With the wiring pattern
12 being formed on the tip portion of the gimbal
spring
1, the slider
3 mounted on the gimbal spring
1 is tilted
by the thickness of the wiring pattern
12. In order to prevent this, in
general, a dummy thin-film pattern
15 having the same height as the wiring
pattern
12 is formed on the rear end side of the gimbal spring
1.
Even around the holes
31 and
32 of the load beam
2, dummy
patterns
16 and
17 are formed symmetrically to the wiring pattern
12 in order to maintain balance in the mechanical strength in the direction
of width of the load beam
2.
Described below is an example in which the present invention is adapted
to the thus constituted magnetic head assembly
30.
FIG. 15 is a plan view illustrating, on an enlarged scale, major portions of
the gimbal spring
1 and of the load beam
2 of FIG.
14. The
same constituent members as those of FIG. 14 are denoted by the same reference
numerals. In the embodiment of FIG. 15, a slit
11 is formed in a region
between the wiring pattern
12 and the dummy thin-film pattern
15
formed on the gimbal spring
1. In this case, the adhesive agent is permitted
to drop from the dispenser onto the region between the slit
11 and the dummy
thin-film pattern
15. When the slider
3 is mounted, therefore, the
adhesive agent is restricted from spreading by the slit
11 and by the dummy
thin-film pattern
15.
In the magnetic head assembly of this embodiment, the slider
3 is adhered
to the gimbal spring
1 with the adhesive agent
8, and the terminals
3B of the slider and the connection terminals on the gimbal spring
1
are connected together by the gold ball
9 shown in FIG. 6B in a state in
which the slider
3 is mounted on the gimbal spring
1. In the magnetic
head assembly of this embodiment, therefore, the slider
3 and the gimbal
spring
1 are locked at two points by the gold ball
9 and by the adhesive
agent
8. In this embodiment, however, a slit
11 exists between the
portion bonded by the gold ball
9 and the portion bonded by the adhesive
agent
8. This helps reduce the difference in the expansion or contraction
due to thermal expansion between the slider
3 and the gimbal spring
1
and reduce the effect by two locking points based upon the gold ball and the adhesive
agent. As a result, the slider warps a small amount with a change in the temperature.
FIG. 16 illustrates a modified example of the embodiment of FIG. 15, and wherein
dummy thin-film patterns
15 are provided on both sides of a portion of the
gimbal spring
1 on which the adhesive agent will be dropped. In this case,
a slit
11 is formed between the wiring pattern
12 and the dummy thin-film
pattern
15 of the side close to the wiring pattern
12. When the slider
3 is mounted on the gimbal spring
1 according to this embodiment,
the adhesive agent is restricted from spreading by the two dummy thin-film patterns
15. Moreover, the adhesive agent that spreads beyond the dummy thin-film
pattern
15 is prevented by the slit
11 from entering into the side
of the wiring pattern
12.
Even in this embodiment, the terminals
3B of the slider and the connection
terminals on the gimbal spring
1 are connected together by the gold ball
9 shown in FIG. 6B in a state where the slider
3 is mounted on the
gimbal spring
1. Even in the magnetic head assembly of this embodiment,
therefore, the slider
3 and the gimbal spring
1 are locked at two
points. In the magnetic head assembly of this embodiment, however, the slit
11
formed between the portion coupled by the gold ball
9 and the portion coupled
by the adhesive agent
8 works to reduce the difference in the contraction
or expansion due to the thermal expansion between the slider
3 and the gimbal
spring
1. As a result, a reduced effect is exhibited by the two locking
points based on the gold ball and the adhesive agent, and the slider warps in a
reduced amount with a change in the temperature.
FIG. 17 is a modified example from FIG. 16, and in which the gimbal spring
1
shown in FIG. 14 on the side of the load beam
2 is cut short. Even in this
embodiment, the terminals
3B of the slider and the connection terminals
on the gimbal spring
1 are connected together by the gold ball
9
shown in FIG. 6B in a state where the slider
3 is mounted on the gimbal
spring
1. The slit
11 that exists between the portion coupled by
the gold ball
9 and the portion coupled by the adhesive agent
8 works
to reduce a difference in the contraction or expansion due to thermal expansion
between the slider
3 and the gimbal spring
1. As a result, a reduced
effect is exhibited by the two locking points based on the gold ball and the adhesive
agent, and the slider
3 warps a small amount with a change in the temperature,
which are the same effects as those obtained with the magnetic head assembly
30
shown in FIG.
16.
As described above, the magnetic head assembly according to the first aspect
of
the present invention can be adapted even to the magnetic head assembly
30
disclosed in Japanese Patent Application No. 82110/1993 (U.S. Ser. No. 08/110,771).
Even in this case, use of the adhesive agent explained in conjunction with the
second aspect of the invention helps further suppress the slider
3 from deforming.
The gimbal spring
1 in the aforementioned embodiments are provided with
the pair of beam portions
4,
5 and the head-mounting portion, and
is formed in the tip portion of the load beam
2 integrally therewith. However,
the gimbal spring
1 according to the present invention can be adapted even
to a magnetic head assembly
40 which has a gimbal spring
1 that is
separately mounted on the tip portion of the load beam
2. In the embodiment
described here, the constituent members which are substantially the same as those
of the aforementioned embodiments are denoted by the same reference numerals.
FIG. 18 illustrates the constitution of the magnetic head assembly
40
in which a separate gimbal spring is mounted on the load beam. A gimbal spring
18 is secured to the tip portion of the load beam
2 by spot-welding
or a similar means. In this embodiment, a tongue-shaped inner plate
18B
surrounded by a U-shaped hole
19 with the tip side of the gimbal spring
18 as a vertex serves as an inner plate portion of the gimbal spring that
includes a slider-mounting portion on which the slider
3 will be mounted,
and the other portion
18A serves as an outer plate portion of the gimbal
spring. In FIG. 18, reference numeral
2A denotes a beam that is folded at
both ends of the load beam
2 to impart strength to the load beam
2.
A protrusion
17 is provided at a required portion on a surface opposed to
the load beam
2 on the side of t
