U.S. patent application number 09/107010 was filed with the patent office on 2001-08-30 for method for assembling a magnetic head assembly and magnetic disk drive using bonding balls connecting magnetic head terminals to wiring terminals.
Invention is credited to AMEMIYA, TAKUYA, HARADA, KAZUHIKO, MIYAZAKI, YUKIO, MIZOSHITA, YOSHIFUMI, OHWE, TAKESHI.
Application Number | 20010016975 09/107010 |
Document ID | / |
Family ID | 27580135 |
Filed Date | 2001-08-30 |
United States Patent
Application |
20010016975 |
Kind Code |
A1 |
AMEMIYA, TAKUYA ; et
al. |
August 30, 2001 |
METHOD FOR ASSEMBLING A MAGNETIC HEAD ASSEMBLY AND MAGNETIC DISK
DRIVE USING BONDING BALLS CONNECTING MAGNETIC HEAD TERMINALS TO
WIRING TERMINALS
Abstract
A method for assembling a magnetic head assembly with a slider
and a magnetic head including forming, on a slider supporting
member, a terminal connected to a magnetic head terminal. In
addition, the method includes fixing a head slider on the slider
supporting member so that the head terminal faces the terminal of
the slider supporting member and contacting a conductive ball
member to both of the head terminal and the terminal of the slider
supporting member. Furthermore, the method includes pressing the
ball member to bond the head terminal with the terminal of the
slider supporting member so that the ball member connects the
terminals electrically and mechanically.
Inventors: |
AMEMIYA, TAKUYA;
(KAWASAKI-SHI, JP) ; HARADA, KAZUHIKO;
(KWASAKI-SHI, JP) ; MIYAZAKI, YUKIO;
(KAWASAKI-SHI, JP) ; OHWE, TAKESHI; (KAWASAKI-SHI,
JP) ; MIZOSHITA, YOSHIFUMI; (KAWASAKI-SHI,
JP) |
Correspondence
Address: |
GREER, BURNS & CRAIN
300 S WACKER DR
25TH FLOOR
CHICAGO
IL
60606
US
|
Family ID: |
27580135 |
Appl. No.: |
09/107010 |
Filed: |
June 30, 1998 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09107010 |
Jun 30, 1998 |
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08774554 |
Dec 30, 1996 |
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08774554 |
Dec 30, 1996 |
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08896435 |
Jul 18, 1997 |
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6002550 |
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Current U.S.
Class: |
29/603.03 ;
29/603.04; 29/603.07; G9B/21.023; G9B/5.024; G9B/5.044; G9B/5.078;
G9B/5.151; G9B/5.152; G9B/5.153; G9B/5.154; G9B/5.155; G9B/5.157;
G9B/5.23; G9B/5.231 |
Current CPC
Class: |
G11B 5/6005 20130101;
G11B 5/1278 20130101; G11B 5/4833 20130101; Y10T 29/49032 20150115;
G11B 5/4853 20130101; G11B 5/486 20130101; Y10T 29/4903 20150115;
G11B 5/4826 20130101; G11B 5/484 20130101; Y10T 29/49027 20150115;
Y10T 29/49025 20150115; G11B 5/4886 20130101; G11B 5/012 20130101;
G11B 21/16 20130101; G11B 5/3103 20130101 |
Class at
Publication: |
29/603.03 ;
29/603.04; 29/603.07 |
International
Class: |
G11B 005/127 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 31, 1992 |
JP |
4-231184 |
Nov 27, 1992 |
JP |
4-318846 |
Apr 8, 1993 |
JP |
5-82110 |
Aug 10, 1993 |
JP |
5-198673 |
Claims
What is claimed is:
1. A method for assembling a recording/reproducing head assembly
which comprises a slider and a slider supporting member, the slider
having a head element and a head terminal connected to the head
element, said method comprising the steps of: forming on the slider
supporting member a terminal to be connected to the head terminal;
fixing the head slider on the slider supporting member so that the
head terminal faces the terminal of the slider supporting member;
contacting a conductive ball member to both of the head terminal
and the terminal of the slider supporting member; and pressing the
ball member to bond the head terminal and the terminal of the
slider supporting member, whereby the ball member electrically and
mechanically connects both terminals.
2. The method as claimed in claim 1, wherein both the terminals
face at right angles to each other.
3. The method as claimed in claim 1, further comprising a step of
irradiating ultrasonic waves during pressing the ball member.
4. The method as claimed in claim 1, wherein the ball member is
made of gold.
5. The method as claimed in claim 1, further comprising a step of
plating both the terminals with gold before contacting the ball
member.
6. The method as claimed in claim 5 wherein the ball is made of
gold.
7. The method as claimed in claim 6, further comprising a radiating
ultrasonic waves during pressing the ball member.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a magnetic head assembly
having a thin-film or MR type magnetic head used for a magnetic
disk drive.
[0003] 2. Description of the Related Art
[0004] Recently, in conventional magnetic disk drives, monolithic
type magnetic heads have been replaced with thin-film or MR type
magnetic heads.
[0005] FIG. 1A is an exploded view of an example of a magnetic head
assembly (which can also be referred to as a magnetic head
suspension unit) having a thin-film type magnetic head used for the
conventional magnetic disk drives. FIG. 1B is an exploded view of a
part of the magnetic head suspension unit shown in FIG. 1A. In the
present specification, the magnetic head suspension unit refers to
an assembly of a spring arm having a magnetic head mounted on an
end of the spring arm. The other end of the spring arm is adapted
to be mounted on a member of a magnetic head positioning
mechanism.
[0006] Referring now to FIG. 1A, one end (a base portion 1a) of a
spring arm (suspension) 1 formed of an elastic plate is mounted to
a member of a magnetic head positioning mechanism (not shown in the
figure) via a plate-like spacer 2. A gimbal 3 is mounted on another
end 1b of the spring arm 1. The gimbal 3 is mounted, as shown in
FIG. 1B, on the spring arm 1 by means of laser welding at positions
indicated by x. A core slider (head slider) 4 of a magnetic head h
is mounted by adhesive on the gimbal 3.
[0007] Two magnetic head elements 5 are formed on a rear side
surface of the magnetic head, the magnetic head elements 5 being
connected by lead wires 6 which lead to a read wire 8 covered with
an insulating tube 7 fixed to the spring arm 1. The lead wire 8 is
lead to a recording/reproducing circuit 9 shown in FIG. 2.
[0008] The spring arm 1 is slightly bent near the base portion 1a
so that a bent portion 1c is formed so as to generate a spring
force.
[0009] FIG. 2 is an exploded view of a conventional magnetic disk
drive in which two magnetic head suspension units shown in FIG. 1A
are used.
[0010] Two magnetic head suspension units are mounted on a driving
arm 13 which pivots about an axis 12 so that a magnetic disk 10
accommodated inside the magnetic head drive is sandwiched between
two of the core sliders 4 mounted on the respective spring arms 1.
Each of the core sliders 4 is pressed to a respective surface of
the magnetic disk 10 by the spring force generated by the bent
portion 1c.
[0011] When the magnetic disk 10 is rotated at a high speed, the
magnetic heads h float, if the magnetic heads h are of the floating
type, on the respective surface of the magnetic disk 10 due to an
air flow generated by the rotation of the magnetic disk 10. If the
magnetic heads h are contact type magnetic heads, the magnetic
heads h do not float, but instead slide on the respective surfaces
of the magnetic disk 10. The magnetic heads h are moved to
respective target tracks on the surfaces of the magnetic disk 10 by
pivoting the spring arms about the axis 12.
[0012] FIG. 3 is a perspective view of a thin-film type magnetic
head. FIG. 4 is an enlarged cross sectional view of the thin-film
type magnetic head shown in FIG. 3 taken along a line A-A of FIG.
3.
[0013] The thin-film type magnetic head shown in FIG. 3 comprises
the slider 4 and head elements 5. The head elements 5 are formed by
means of a film deposition technique and lithography. Terminals 15a
and 15b for recording/reproducing coils are provided near the head
elements 5.
[0014] Each of the head elements 5 comprises a lower magnetic pole
16, an upper magnetic pole 17 and a thin-film coil 19 wound around
a connecting portion 18 between the lower magnetic pole 16 and the
upper magnetic pole 17. A gap insulating layer 20 is provided
between the lower magnetic pole 16 and the upper magnetic pole 17
so that a gap G having a predetermined width is formed between the
two poles. The gap G faces the surface of the magnetic disk 10 to
perform an magnetic recording/reproducing operation.
[0015] In the construction of the magnetic head suspension unit
shown in FIG. 1 in which the lead wire 8 is covered with the
insulating tube 7, the insulating tube 7 occupies a relatively
large space to prevent miniaturization of the magnetic disk drive.
Additionally, the insulating tube 7 makes an assembling operation
difficult, particularly an automated assembling operation. Further,
there is a strong possibility that the lead wire 8 will pick up
noises, resulting in degradation of an S/N ratio of a signal sent
via the lead wire 8.
[0016] In order to eliminate the above-mentioned problems, a method
for forming a signal transmitting line on a spring arm is suggested
in Japanese Laid-Open Patent Application No.4-21918. In the method,
a signal line is formed of a pattern of a conductive layer on an
insulating layer formed on the spring arm. However, the method has
a problem in that the signal transmitting line formed of the
conductive layer is easily damaged or broken during a process for
forming the bent portion 1c shown in FIG. 1A.
[0017] Japanese Laid-Open Patent Application No.4-111217 discloses
a magnetic head suspension unit in which a flexible printed circuit
board is attached to a spring arm, and a portion of the flexible
circuit board corresponding to the above of the spring arm bent
portion is not adhered to the spring arm. Instead, in this
construction, the portion of the flexible printed circuit board
corresponding to the bent portion of the spring arm is free, and
thus the there is no bending stress applied to the flexible printed
circuit board. However, this construction cannot be applied to a
highly miniaturized spring arm such as a spring arm having a
thickness of a few microns and a 4.6 mm width.
[0018] There is another problem in that ability of the insulating
layers 21 and 22 of the magnetic head element 5 t withstand
dielectric voltage is very low because they each have a thickness
of only 1 to a few microns. Accordingly, if a relatively high
voltage of about 100V or more is applied between the thin-film coil
19 and the poles 16 and 17 due to a generation of static
electricity, the insulating layers 21 and 22 may be easily damaged
due to electric discharge.
[0019] If the insulation between the thin-film coil 19 and the
poles 16 or 17 is damaged, an electric discharge may occur between
the core slider, which is made of a conductive material such as
Al.sub.2O.sub.3TiC, and the magnetic poles 16 or 17, resulting in
the gap G or the floating surface of the core slider 4 being
damaged. Additionally, when the magnetic disk drive is in
operation, an electric discharge may occur between the magnetic
disk 10 and the magnetic poles 16 or 17, resulting in the magnetic
gap G being damaged. When the core slider 4 is damaged, the
floating characteristic of the magnetic head is deteriorated, which
condition causes a generation of noises in the
recording/reproducing signal. If the magnetic head is a contact
type head, the damaged surface of the magnetic head may scratch the
magnetic disk 10.
[0020] Problems similar to the above-mentioned problems may occur
when the core slider is miniaturized. That is, when the magnetic
head is heated, the magnetic head tends to expand due to the
thermal expansion, but a portion of the core slider attached to the
gimbal or the spring arm by adhesive cannot expand in accordance
with the expansion of the magnetic head. This creates bending of
the core slider, and thus the floating characteristic of the
magnetic head may be deteriorated.
SUMMARY OF THE INVENTION
[0021] It is a general object of the present invention to provide
an improved and useful magnetic head assembly and a magnetic disk
drive having such a magnetic head suspension unit in which the
above-mentioned disadvantages are eliminated.
[0022] A more specific object of the present invention is to
provide a magnetic head assembly and a magnetic disk drive in which
damaging of a conductive-pattern layer formed on a spring arm
during a process of bending the spring arm can be prevented.
[0023] Another object of the present invention is to provide a
magnetic head assembly and a magnetic disk drive in which no
insulation breakage occurs due to generation of static
electricity.
[0024] Another object of the present invention is to provide a
magnetic head assembly and a magnetic disk drive in which thermal
deformation of a slider core is prevented.
[0025] In order to achieve the above-mentioned objects, there is
provided according to the present invention, a magnetic head
assembly comprising:
[0026] a slider on which a magnetic head is mounted, the slider
having terminals of the magnetic head;
[0027] a gimbal portion on which the slider is mounted;
[0028] terminals of wiring lines; and
[0029] balls bonding the terminals of the wiring lines and the
terminals of the slider.
[0030] The magnetic head assembly may be configured so that the
balls are made of gold.
[0031] The magnetic head assembly may be configured so that the
terminals of the wiring lines are provided on the gimbal
portion.
[0032] The magnetic head assembly may be configured so that the
wiring lines are formed by a wiring pattern.
[0033] The magnetic head assembly may be configured so that the
slider is provided on a surface of the gimbal portion on which the
wiring lines are provided.
[0034] The magnetic head assembly may be configured so that the
slider is provided on the gimbal portion so that the terminals of
the wiring pattern and the terminals of the slider face each other
in an orthogonal formation.
[0035] The magnetic head assembly may be configured so that the
gimbal portion is a part of a suspension so that the gimbal portion
is integrally formed with the suspension.
[0036] The magnetic head assembly may be configured so that the
wiring lines are formed by a wiring pattern formed on the
suspension.
[0037] The magnetic head assembly may be configured so that the
slider is provided on a surface of the gimbal portion on which the
wiring lines are provided.
[0038] The magnetic head assembly may be configured so that the
slider is provided on the gimbal portion so that the terminals of
the wiring pattern and the terminals of the slider face each other
in an orthogonal formation.
[0039] The above objects of the present invention are also achieved
by a magnetic disk drive comprising:
[0040] an enclosure;
[0041] a magnetic disk provided in the enclosure;
[0042] a magnetic head assembly provided in the enclosure; and
[0043] an actuator to which the magnetic head suspension unit is
fixed, the actuator moving the magnetic head assembly above the
magnetic disk, wherein the magnetic head assembly is configured as
described above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0044] The other objects, features and advantages of the present
invention will be apparent from the following detailed description
when read in conjunction with the accompanying drawings, in
which:
[0045] FIG. 1A is an exploded view of an example of a magnetic head
assembly having the thin-film type magnetic head used for the
conventional magnetic disk drives;
[0046] FIG. 1B is an exploded view of a part of the magnetic head
assembly shown in FIG. 1A;
[0047] FIG. 2 is an exploded view of a conventional magnetic disk
drive in which two magnetic head assemblies shown in FIG. 1A are
used;
[0048] FIG. 3 is a perspective view of a thin-film type magnetic
head;
[0049] FIG. 4 is an enlarged cross sectional view of the thin-film
type magnetic head shown in FIG. 3 taken along a line A-A of FIG.
3;
[0050] FIG. 5A is a perspective view of a first embodiment of a
magnetic head assembly according to the present invention;
[0051] FIG. 5B is an enlarged cross sectional view taken along a
line b-b of FIG. 5A;
[0052] FIG. 6A is a perspective view of the spring arm shown in
FIG. 5A in a state where a magnetic head has not been mounted on a
gimbal;
[0053] FIG. 6B is an illustration showing a process for forming
conductive-pattern layers on the spring arm;
[0054] FIGS. 7A through 7C are illustrations showing a process for
bending the bent portions shown in FIG. 6A;
[0055] FIG. 8A is a perspective view of a second embodiment of a
magnetic head assembly according to the present invention;
[0056] FIG. 8B is an enlarged partial cross sectional view taken
along a line b-b of FIG. 8A;
[0057] FIG. 8C is an enlarged partial cross sectional view taken
along a line c-c of FIG. 8A;
[0058] FIG. 8D is a partial cross sectional view of a variation of
the spring arm shown in FIG. 8A;
[0059] FIG. 9A is a perspective view of a third embodiment of a
magnetic head assembly according to the present invention;
[0060] FIG. 9B is a cross sectional view taken along a line b-b of
FIG. 9A;
[0061] FIG. 10 is a perspective view of a fourth embodiment of a
magnetic head assembly according to the present invention;
[0062] FIG. 11A is a perspective view of a fifth embodiment of a
magnetic head assembly according to the present invention;
[0063] FIG. 11B is an enlarged partial cross sectional view taken
along a line b-b of FIG. 11A.
[0064] FIG. 12A is a perspective view of a sixth embodiment of a
magnetic head assembly according to the preset invention;
[0065] FIG. 12B is an enlarged partial cross sectional view taken
along a line b-b of FIG. 12A;
[0066] FIG. 12C is an enlarged partial cross sectional view taken
along a line c-c of FIG. 12C;
[0067] FIG. 13A is a perspective view of a seventh embodiment of a
magnetic head assembly according to the present invention;
[0068] FIG. 13B is a variation of the embodiment shown in FIG.
13A;
[0069] FIG. 14 is a perspective view of an eighth embodiment of a
magnetic head assembly according to the present invention;
[0070] FIG. 15A is a perspective view of the magnetic head shown in
FIG. 14;
[0071] FIG. 15B is a cross sectional view taken along a line b-b of
FIG. 15A;
[0072] FIG. 16 is an exploded view of an essential part of a ninth
embodiment of a magnetic head assembly according to the present
invention;
[0073] FIG. 17 is an exploded view of an essential part of a
variation of the ninth embodiment shown in FIG. 16;
[0074] FIG. 18 is a perspective view of an essential part of a
tenth embodiment of a magnetic head assembly according to the
present invention;
[0075] FIG. 19 is an exploded view of an eleventh embodiment of a
magnetic head assembly according to the present invention;
[0076] FIG. 20A is a perspective view of a spring arm of a twelfth
embodiment of a magnetic head assembly according to the present
invention;
[0077] FIG. 20B is an enlarged cross sectional view of a mounting
structure of the core slider shown in FIG. 20A;
[0078] FIGS. 21A through 21F are illustrations of variations of the
hole shown in FIG. 20A; and
[0079] FIG. 22A is a perspective view of a spring arm of a
thirteenth embodiment of a magnetic head assembly according to the
present invention;
[0080] FIG. 22B is an enlarged cross sectional view of a mounting
structure of the core slider shown in FIG. 22A;
[0081] FIG. 22C is an enlarged cross sectional view showing a
variation of the mounting structure shown in FIG. 22B;
[0082] FIG. 23 is a perspective view of a magnetic head assembly
according to a fourteenth embodiment of the present invention;
[0083] FIG. 24 is a plan view of a 3.5-inch magnetic disk drive to
which the magnetic head assembly shown in FIG. 23 is applied;
[0084] FIG. 25 is a perspective view of a first-order bend state of
a suspension shown in FIG. 23;
[0085] FIG. 26 is a perspective view of a first-order twist state
of the suspension shown in FIG. 23;
[0086] FIG. 27 is a perspective view of the upper side of the
magnetic head assembly shown in FIG. 23;
[0087] FIG. 28 is a side view of the magnetic head assembly shown
in FIG. 23;
[0088] FIG. 29 is a perspective view of a magnetic head assembly
according to a fifteenth embodiment of the present invention;
[0089] FIG. 30 is a perspective view of a magnetic head assembly
according to a sixteenth embodiment of the present invention;
[0090] FIG. 31 is a perspective view of a magnetic head assembly
according to the twelfth embodiment of the present invention;
[0091] FIG. 32 is a side view of the mechanism shown in FIG.
31;
[0092] FIG. 33 is a perspective view of a magnetic head assembly
according to an eighteenth embodiment of the present invention;
[0093] FIG. 34 is a perspective view of a magnetic head assembly
according to a nineteenth embodiment of the present invention;
[0094] FIG. 35 is a plan view of a free-end part of a suspension
shown in FIG. 34;
[0095] FIG. 36 is a sectional-view taken along a line XIV-XIV shown
in FIG. 34;
[0096] FIG. 37 is a perspective view of a magnetic head slider
shown in FIG. 34;
[0097] FIG. 38 is a flowchart of a production process for the
suspension shown in FIG. 34;
[0098] FIG. 39 is a plan view of a plate obtained after an etching
step shown in FIG. 38 is carried out;
[0099] FIG. 40 is a flowchart of another production process for the
suspension shown in FIG. 34;
[0100] FIG. 41 is a perspective view of a variation of the
nineteenth embodiment of the present invention;
[0101] FIG. 42 is a perspective view of a magnetic head assembly
according to a twelfth embodiment of the present invention;
[0102] FIG. 43 is a plan view of a magnetic disk drive to which the
magnetic head assembly shown in FIG. 42 is applied;
[0103] FIGS. 44A and 44B are respectively plan and side views of
the magnetic head assembly shown in FIG. 42;
[0104] FIG. 45 is a side view of a state observed when the magnetic
head assembly shown in FIG. 42 is provided in the magnetic disk
drive;
[0105] FIG. 46 is an emphasized view of the state in FIG. 45;
[0106] FIG. 47 is a side view of a first-order bend state of a
suspension used in the twelfth embodiment of the present
invention;
[0107] FIG. 48 is a side view of a first-order twist state of the
suspension used in the twelfth embodiment of the present
invention;
[0108] FIG. 49 is a plan view of a first variation of a gimbal of
the suspension used in the twelfth embodiment of the present
invention;
[0109] FIG. 50 is a plan view of a second variation of the gimbal
of the suspension used in the twelfth embodiment of the present
invention;
[0110] FIG. 51 is a plan view of a third variation of the gimbal of
the suspension used in the twelfth embodiment of the present
invention;
[0111] FIG. 52 is a plan view of a fourth variation of the gimbal
of the suspension used in the twelfth embodiment of the present
invention;
[0112] FIG. 53 is a plan view of a fifth variation of the gimbal of
the suspension used in the twelfth embodiment of the present
invention; and
[0113] FIG. 54 is a side view of a variation of the twelfth
embodiment of the present invention.
[0114] FIG. 55 is a top view of another embodiment of a magnetic
disk apparatus of the present invention;
[0115] FIG. 56 is a cross section of the magnetic disk apparatus in
FIG. 55;
[0116] FIG. 57 is a top view of an actuator in FIG. 55;
[0117] FIG. 58 is a perspective view of a magnetic head assembly
according to a further embodiment of the present invention;
[0118] FIG. 59 illustrates another connecting mechanism of the
magnetic head assembly in FIG. 58;
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0119] A description will now be given, with reference to FIGS. 5A
and 5B, of a first embodiment of the present invention. FIG. 5A is
a perspective view of a first embodiment of a magnetic head
assembly according to the present invention, and FIG. 5B is an
enlarged cross sectional view taken along a line b-b of FIG. 5A.
Hereinafter, the magnetic head assembly is also referred to a
magnetic head suspension unit or merely suspension unit. In FIGS.
5A and 5B, parts that are the same as the parts shown in FIG. 1A
are given the same reference numerals, and descriptions thereof
will be omitted.
[0120] The first embodiment according to the present invention
comprises the spring arm 1 and the slider core 4 of the magnetic
head. A gimbal 24 supported by bridge portions 23a and 23b is
formed on the end 1b of the spring arm 1. The core slider (head
slider) 4 of the magnetic head is mounted on the gimbal 24 by an
adhesive which has an insulation effect and can be an insulation
adhesive or an adhesive containing an insulator. The insulation
adhesive is an insulator in which the insulator itself has the
insulation effect.
[0121] The base portion (attachment portion) 1a of the spring arm 1
is fixed to a member of a magnetic head positioning mechanism.
Conductive-pattern layers 25 run from the base portion la to the
gimbal 24 so as to transmit signals to/from the magnetic head.
[0122] FIG. 6A is a perspective view of the spring arm 1 shown in
FIG. 5A in a state where the magnetic head has not been mounted on
the gimbal 24. In FIG. 6A, a portion of the core slider 4 is also
shown to explain electrical connection between the magnetic head
and the conductive-pattern layers 25. A pad 25a is formed at the
end of each of the two conductive-pattern layers 25. The core
slider of the magnetic head is also provided with pads 26. When the
core slider 4 is mounted on the gimbal 24, the pads 26 make contact
with the respective pads 25a. The pads 26 and the pads 25a are then
soldered together to assure an electric connection. It should be
noted that the core slider 4 in FIG. 6A is viewed from a direction
indicated by an arrow B of FIG. 5A.
[0123] The conductive-pattern layers 25 on the spring arm 1 are
formed by a process shown in FIG. 6B. As shown by FIG. 6B-2, an
insulating layer 27 is formed on the spring arm 1 by applying a
polyimide resin over the spring arm 1 made of stainless steel. The
thickness of the spring arm 1 is about 25 .mu.m, and the thickness
of the insulating layer 27 is 3-4.mu.m. A base layer 28 is then
formed on the insulating layer 27, as shown in FIG. 6B-3, by
sputtering copper (Cu) onto the insulating layer 27. The base layer
28 may instead be formed by vapor deposition or chemical
plating.
[0124] Using the base layer 28, electro plating is performed to
form a copper layer 29 on the base layer 28, as shown in FIG. 6B-4.
As shown in FIG. 6B-5, the base layer 28 and the copper layer 29
are etched so that the conductive-pattern layers 25 remain on the
spring arm 1. Lastly, polyimide resin is applied over the
conductive-pattern layers 25 so as to form an insulating film 30
which covers the conductive-pattern layers 25 to protect them.
[0125] If a bending process is performed by applying a pressing
force to the conductive-pattern layers 25 formed on the spring arm
1, the conductive-pattern layers 25 may be damaged or destroyed. In
order to eliminate this problem, in the first embodiment of the
present invention, rectangular holes 31a and 31b are formed on the
spring arm 1, as shown in FIG. 5A, on either side of the
conductive-pattern layers 25. The rectangular holes 31a and 31b
separate a portion of the spring arm 1, on which the
conductive-pattern layers 25 are formed, from bent portions 33a and
33b to which a pressing force is applied to bend the spring arm 1.
The rectangular holes 31a and 31b may instead be slits 32a and 32b
as shown in FIG. 6A.
[0126] FIGS. 7A through 7C are illustrations showing a process for
bending the bent portions 33a and 33b. As shown in FIG. 7A, first a
roller 34 having larger diameter portions 35a and 35b is prepared.
The larger diameter portions 35a and 35b bends the corresponding
bent portions 33a and 33b. The bent portions 33a and 33b, which are
formed as an elastic portion R generating an elastic force, of
spring arm 1 are placed on a rubber table 36. The roller 34 is then
rolled, as shown in FIG. 7B, on the bent portion 33a and 33b while
it is being pressed. As a result, only the bent portions 33a and
33b are permanently deformed into an arc-like shape, while the
portion of the spring arm 1, on which portion the
conductive-pattern layers are formed, between the bent portions 33a
and 33b is elastically deformed.
[0127] According to the present embodiment, the roller 34 is not
pressed on the portion where the conductive-pattern layers 25 have
been formed, and thus no damage to the conductive-pattern layers 25
occurs.
[0128] A description will now be given, with reference to FIGS. 8A
through 8D, of a second embodiment according to the present
invention. FIG. 8A is a perspective view of a second embodiment of
a magnetic head suspension unit according to the present invention;
FIG. 8B is an enlarged partial cross sectional view taken along a
line b-b of FIG. 8A; FIG. 8C is an enlarged partial cross sectional
view taken along a line c-c of FIG. 8A. FIG. 8D is a partial cross
sectional view of a variation of the spring arm shown in FIG.
8A.
[0129] In the present embodiment, a recessed portion 39 is formed
in the elastic portion R where an elastic force is generated. The
conductive-pattern layers 25 are formed in the recessed portion 39.
The recessed portion 39 covers an entire length C of the elastic
portion R and a width B so as to cover the portions of the
conductive-pattern layers 25 located in the elastic portion R of
the spring arm 1.
[0130] In this embodiment, a portion of the insulating layer 27
shown in FIG. 6B-2 is formed also inside the recessed portion 39.
The base layer 28 and the copper layer 29 are then formed on the
entire surface of the insulating layer 27 including the portion
thereof inside the recessed portion 39 so as to form the
conductive-pattern layers 25. Lastly, the insulating layer 30 is
formed on the conductive-pattern layers 25 so that a top surface of
the insulating layer 30 located inside the recessed portion 39 is
below the surface of the spring arm 1 as shown in FIG. 8B.
[0131] In the present invention, since the portion inside the
recessed portion 39 do not come into contact with the roller for
forming the bent portions even though the roller has a straight
cylindrical surface, no damage occurs to the conductive-pattern
layers 25, the same as in the case of the above-mentioned first
embodiment.
[0132] Although in the above embodiment the recessed portion 39 is
formed by means of etching, the recessed portion 39 may instead be
formed by means of press forming as shown in FIG. 8D. By using
press forming, the recessed portion 39 can be formed even if the
thickness of the spring arm 1 is very slight or the total thickness
of the insulating layers 27 and 30 and the conductive-pattern
layers 25 is great. The recessed portion 39 may be formed so that
an entire length 25L of straight portions of the conductive-pattern
layers 25 is embedded in the recessed portion 39.
[0133] A description will now be given, with reference to FIGS. 9A
and 9B, of a third embodiment according to the present invention.
FIG. 9A is a perspective view of a third embodiment of a magnetic
head suspension unit according to the present invention; FIG. 9B is
a cross sectional view taken along a line b-b of FIG. 9A.
[0134] In the present embodiment, portions 25r of the
conductive-pattern layers 25, corresponding to the elastic portion
R which generates an elastic force, are wider than other portions
of the conductive-pattern layers 25. That is, a width C.sub.1 of
each of the portion 25r of the conductive-pattern layers 25 within
the elastic portion R is widened over a length L corresponding to
the elastic portion R. The total thickness of the
conductive-pattern layers 25 and insulating layers 27 and 30 is
uniform over the entire width of the widened portions 25r of the
conductive-pattern layers 25. A roller 35 having a straight
cylindrical surface is pressed over the entire width of the elastic
portion R so as to bend the elastic portion R.
[0135] If the conductive-pattern layers 25 or the insulating layer
30 in the elastic portion R are protruded as shown in FIG. 6B, the
pressing force exerted by the roller 35 is concentrated onto the
conductive-pattern layers 25. However, in the present embodiment,
the pressing force is dispersed onto the entire width of the
widened conductive-pattern layers 25, and thus damage or breakage
of the conductive-pattern layers 25 is prevented. Additionally,
even if damage such as a cracking of portions of the
conductive-pattern layers 25 occurs, other portions of the layers
25 which are not damaged, resulting in reliable electric
continuity. In the present embodiment, the width c1 of each of the
portion 25r of the conductive-pattern layers 25 is 2.0 mm, and the
length L is 1.5 mm.
[0136] A description will now be given, with reference to FIG. 10,
of a fourth embodiment according to the present invention. FIG. 10
is a perspective view of a fourth embodiment of a magnetic head
suspension unit according to the present invention.
[0137] In the present embodiment, zigzagging conductive-pattern
portions 25z of the conductive-pattern layers 25 within the elastic
portion R are formed to extend in a direction oblique to a
direction in which other portions of the conductive-pattern layers
25 extend. Preferably, U-turn portions 25c are formed with a width
greater than other portions. As a result, in the present
embodiment, pressing force is dispersed over the contacting area of
the roller to be pressed, thus reducing damaging and breakage of
the conductive-pattern layers 25.
[0138] A description will now be given, with reference to FIGS. 11A
and 11B, of a fifth embodiment of the present invention. FIG. 11A
is a perspective view of a fourth embodiment of a magnetic head
suspension unit according to the present invention; FIG. 11B is an
enlarged partial cross sectional view taken along a line b-b of
FIG. 11A.
[0139] In the present embodiment, a plurality of dummy patterns 25d
are formed within the elastic portion R. The dummy patterns 25d
have the same construction as the conductive-pattern layers 25.
When the elastic portion R is pressed by the roller 35 as shown in
FIG. 11B, the pressing force is dispersed onto the dummy patterns
25d, and thus damage and breakage of the conductive-pattern layers
25 is prevented unlike in the case of the conventional
conductive-pattern layers in which the pressing force is
concentrated onto the conductive-pattern layers.
[0140] FIG. 12A is a perspective view of a sixth embodiment of a
magnetic head suspension unit according to the preset invention;
FIG. 12B is an enlarged partial cross sectional view taken along a
line b-b of FIG. 12A; FIG. 12C is an enlarged partial cross
sectional view taken along a line c-c of FIG. 12C. In the sixth
embodiment, a protecting layer is formed over portions of the
conductive-pattern layers 25 in the elastic portion R. The
protecting layer comprises a conducting layer 37 and an insulating
layer 38.
[0141] In order to make the present embodiment, a copper base layer
is formed on the insulating layer 30 in the process shown in FIG.
6B-3-6. The conductive layer 37 made of copper is then formed by
means of electro plating, and the layer 37 is patterned. Polyimide
resin is coated over the conductive layer 37 so as to form the
insulating layer 38. Preferably, the insulating layer 30 formed
over the conductive-pattern layers 25 is formed with a relatively
great thickness so that the insulating layer 30 can be flattened
and smoothed by means of surface polishing. The conductive layer 37
has a relatively large width B to cover the conductive-pattern
layers 25, and has a length C which covers the length of the
elastic portion R as shown in FIG. 12A.
[0142] In the present embodiment, the roller 35 exerts a pressing
force onto the conductive layer 37 which has a relatively high
strength, and thus the pressing force is uniformly dispersed onto
the conductive layer 37. Accordingly, damage to the
conductive-pattern layers 25 is prevented when the spring arm 1 is
bent by the roller 35.
[0143] FIG. 13A is a perspective view of a seventh embodiment of a
magnetic head suspension unit according to the present invention.
In the seventh embodiment, extra conductive-pattern layers 25s are
formed. The extra conductive-pattern layers 25s are formed along
each of the conductive layers 25. Both ends of each of the
additional conductive-pattern layers 25s are connected to the ends
of the respective conductive-pattern layers 25 at corresponding
connection parts 40 and 41. Accordingly, if one of the
conductive-pattern layers 25 is damaged to lose continuity, the
corresponding extra conductive-pattern layer 25s serves the same
function as the damaged conductive-pattern layer 25. Therefore, a
reliable connection can be realized.
[0144] FIG. 13B is a variation of the seventh embodiment according
to the present invention. In this variation, each of the
conductive-pattern layers 25 has two paths along the straight
portion thereof within the elastic portion R. One of the paths
serves as the extra conductive-pattern layer 25s.
[0145] In all the above-mentioned embodiments and variations
thereof, although the bent portions are formed by a press method
using a roller, other method using a mold press or laser may be
used.
[0146] Since the spring arm 1 according to the above-mentioned
embodiments is mounted on a member of the magnetic head positioning
mechanism, as shown in FIG. 2, the magnetic disk drive can reliably
transmit recording/reproducing signals through the spring arm.
[0147] A description will now be given, with reference to FIG. 14
and FIG. 15A and 15B, of an eighth embodiment according to the
present invention. FIG. 14 is a perspective view of the eighth
embodiment of a magnetic head suspension unit according to the
present invention. In FIG. 14, parts that are the same as the parts
shown in FIG. 1A are given the same reference numerals, and
descriptions thereof will be omitted. FIG. 15A is a perspective
view of the magnetic head h shown in FIG. 14; FIG. 15B is a cross
sectional view taken along a line b-b of FIG. 15A.
[0148] In the eighth embodiment according to the present invention,
the core slider 4 is mounted on the gimbal 3 by adhesive 42 having
a high insulating effect. The core slider 4 may instead be directly
mounted on the end 1b of the spring arm 1. Although, in the prior
art, the core slider is also mounted by adhesive having an
insulating effect, the electric resistance between the core slider
4 and the gimbal 3 is low because the adhesive layer is very thin.
Accordingly, the core slider 4 may be at the same potential, that
is a ground potential, as the spring arm 1 because the spring arm 1
is grounded. If a high voltage static electricity is generated in
the thin-film coil of the magnetic head element 5, the insulating
layer between the thin-film coil and the magnetic pole is damaged,
resulting in electric discharge between the thin-film coil and the
core slider.
[0149] In the eighth embodiment, in order to obtain a high
resistance between the core slider and the gimbal 3, a thick layer
of the adhesive 42 is provided. It is preferable that the adhesive
42 be a UV cure resin (ultra-violet cure type adhesive).
Alternatively, epoxy resin may be used. In the present embodiment,
as shown in FIG. 15A, the adhesive 42 comprises an insulating
material powder 42b mixed in adhesive medium 42a. Accordingly, the
adhesive 42 can have a high electric resistance, and is formed with
a relatively great thickness, and thus the insulation between the
core slider 4 and the gimbal 3 is improved.
[0150] FIG. 16 is an exploded view of an essential part of a ninth
embodiment of a magnetic head suspension unit according to the
present invention. In the ninth embodiment, the core slider 4 is
mounted on the gimbal 3 or the end 1b of the spring arm 1 via an
insulator 43. In the present embodiment, the insulator 43 is formed
by applying insulating resin such as a photoresist onto a surface
of the core slider 4. The core slider is mounted on the gimbal 3 by
applying adhesive 44 onto the insulator 43. Alternatively, as shown
in FIG. 17, the insulator 43 may be applied onto a mounting surface
of the gimbal 3.
[0151] FIG. 18 is a perspective view of an essential part of a
tenth embodiment according to the present invention. In FIG. 18, a
magnetic head comprising the magnetic head elements 5 and a core
slider 4i is shown. Unlike the conventional magnetic head, the core
slider 4i is made of an insulating material such as SiO.sub.2.
Accordingly, the discharge as described in relation to the
conventional magnetic head can be eliminated.
[0152] FIG. 19 is an exploded view of an eleventh embodiment of a
magnetic head suspension unit according to the present invention. I
the present embodiment, the magnetic head suspension unit is
mounted on a driving arm 13 of the magnetic head driving mechanism
via an insulating member 45. The insulating member has screw holes
46 into which screws for fastening the magnetic head suspension
unit to the driving arm 13 are inserted. The screws are made of
synthetic resin or metal screws covered with synthetic resin.
Accordingly, the spring arm 1 is insulated from the driving arm 13,
which may be grounded. Alternatively, the spacer 2 may be made of
an insulating material.
[0153] In the present embodiment, since the spring arm is not
electrically connected to the driving arm 13, which may be
grounded, no electric discharge occurs between the core slider 4
and the magnetic pole.
[0154] FIG. 20A is a perspective view of a spring arm of a twelfth
embodiment of a magnetic head suspension unit according to the
present invention; FIG. 20B is an enlarged cross sectional view
showing a mounting structure of the core slider shown in FIG. 20A.
In the present embodiment, a gimbal 24 formed on the spring arm 1
has a hole 47 in the center thereof. As shown in FIG. 20B, the core
slider 4 is mounted on the gimbal 24 by adhesive 48 so that the
hole 47 is filled with the adhesive 48. Since the hole is formed in
the gimbal 24, the gimbal can be easily bent, if bending stress is
applied to the gimbal 24 due to a difference in thermal expansion
between the core slider and the gimbal 24. Accordingly, bending
stress applied to the core slider 4 is reduced since the gimbal 24
is bent instead of the core slider 4. This feature is important
when a thin and miniaturized core slider is used.
[0155] Variations of the hole 47 are shown in FIGS. 21A through
21F. A plurality of holes 47 may be provided, and each hole may
have a rectangular shape.
[0156] In the present embodiment, the hole 47 is filled with a part
of the adhesive applied between the core slider 4 and the gimbal
24, so that the strength of the adhesion between the core slider 4
and the gimbal 24 is increased. Additionally, if the UV cure resin
is used, an ultra-violet beam can be irradiated through the hole
47, which effectively cures the UV cure resin, and thus the
strength of the cured UV cure resin can be improved.
[0157] It should be noted that although the gimbal 24 is integrally
formed with the spring arm 1, the gimbal 24 may be formed
separately from the spring arm 1; that is, it may be fixed to the
spring arm 1 by means of welding described in regard to the
conventional magnetic head suspension unit shown in FIG. 1B.
[0158] FIG. 22A is a perspective view of a spring arm of a
thirteenth embodiment of a magnetic head suspension unit according
to the present invention; FIG. 22B is an enlarged cross sectional
view of a mounting structure of the core slider shown in FIG. 22A;
FIG. 22C is an enlarged cross sectional view showing a variation of
the mounting structure shown in FIG. 22B. In the present
embodiment, an opening 49 is provided in the gimbal 24, into which
opening the core slider is inserted. The opening 49 is slightly
larger than the outer dimension of the core slider 4.
[0159] The core slider 4 is mounted in a state where side faces of
the slider core 4 is fixed, as shown in FIG. 22B, by adhesive 50 to
the outer edge of the opening 49. Alternatively, as shown in FIG.
22C, the core slider 4 may be formed to have a step in its side
surface so that dimension L.sub.2 is larger than dimension L.sub.1.
The dimension of the opening is determined to be a value between
L.sub.1 and L.sub.2. The adhesive such as UV cure resin is applied
to the outer edge of the opening after the core slider 4 is
inserted into the opening 49. An ultra-violet beam is, then
irradiated from a direction indicated by an arrow in FIG. 22C so as
to cure the UV cure resin.
[0160] In the present embodiment, since the core slider 4 is
supported at the side surfaces thereof, stress generated by thermal
expansion of the gimbal 24 is lessened. Accordingly, deformation of
the core slider 4 due to the thermal expansion of the gimbal can be
efficiently prevented.
[0161] It should be noted that the magnetic heads shown in FIGS.
20A and 22A are formed with an MR element formed by means of
thin-film technology. Thin-film type magnetic head elements are
formed on the MR element. However, the present invention is not
limited to the specific magnetic head, and a conventional thin-film
type magnetic head or a monolithic type magnetic head may be
used.
[0162] A description will now be given, with reference to FIG. 23,
of a magnetic head suspension unit 120 according to a fourteenth
embodiment of the present invention.
[0163] FIG. 24 shows a 3.5-inch type magnetic disk drive 1220 to
which the magnetic head suspension unit 120 is applied. The
magnetic disk drive 1220 has an enclosure 1221 in which a 3.5-inch
magnetic disk 1222, a head positioning actuator 1223 and other
parts are housed.
[0164] A suspension (load beam) 121 made of stainless steel is
fixed to an arm 122 of the actuator 223. The suspension 121 has a
curved bent portion 123 generating elasticity. In this regard, the
curved portion 123 of the suspension 121 is also referred to as an
elastic portion 123 in the following description. The suspension
121 has a stiffness portion 24 extending from the elastic portion
123, and ribs 121a. The elastic portion 123 provides a magnetic
head slider (core slider) 135 with a load in a direction in which
the magnetic head slider 135 moves and comes into contact with a
magnetic disk 1222. The suspension 121 has a uniform thickness of,
for example, approximately 25 .mu.m, which is equal to one-third of
the thickness of a suspension of a 3380-type (IBM) head suspension
unit.
[0165] It is desirable that the width W1 of the suspension 121 is
made as small as possible, desirably 4 mm or less. This is because
the resonance frequency of vibration of the suspension 121 is
prevented from lowering.
[0166] A gimbal 125 is integrally formed in the suspension 121 so
that the suspension 121 and the gimbal has a one-piece construction
which uses a plate. The gimbal 125 includes a pair of C-shaped
openings 126 and 126 facing each other in the longitudinal
direction of the suspension 121. Two slits 128 and 129 are formed
in the suspension 121 along respective sides of the suspension
121.
[0167] The gimbal 125 includes a magnetic slider fixing portion
130, a first pair of beam portions 131 and 132, and a second pair
of beam portions 133 and 134. The magnetic head slider fixing
portion 130 has large surface dimensions enough to fix the magnetic
head slider 135 thereon, and has the same dimensions as the
magnetic head slider 135 (a=1.6 mm, b=2.0 mm). However, it is
possible for the slider fixing portion 130 to have an area less
than the magnetic head slider 135 when a sufficient adhesive
strength can be obtained.
[0168] The magnetic head slider 135 is a light weight structure
type slider, which has been proposed in Japanese Patent Laid-Open
Application No. 4-228157. The proposed slider has a flat back
surface opposite to a disk facing surface. The flat back surface of
the slider is fixed to the fixing portion 130 by means of an
adhesive, which can be an insulation adhesive or an adhesive
including an insulator (for example, insulator power). In this
case, the slider 135 is located so that the center thereof
corresponds to the center of the fixing portion 130. It is also
possible to use other types of sliders.
[0169] The beam portions 131 and 132 extend outwardly from the
respective sides of the fixing portion 130 along a line (suspension
width direction line) 138, which passes through the center of the
fixing portion 130 (the above center is also the center of the
slider 135), and crosses a longitudinal center line 137 of the
suspension 121 at a right angle. Each of the beam portions 131 and
132 has a length 11.
[0170] The beam portion 133 extends from the beam portion 131
towards the respective sides of the beam portion 131 so that the
beam portion 133 crosses the beam portion 131 at a right angle and
extends parallel to the line 137. Similarly, the beam portion 134
extends from the beam portion 132 towards the respective sides of
the beam portion 132 so that the beam portion 134 crosses the beam
portion 132 at a right angle and extends in parallel with the line
137. The beam portion 133 is joined to portions 140 and 141 of the
suspension 121 in the periphery of the gimbal 125. Similarly, the
beam portion 134 is joined to portions 142 and 143 of the
suspension 121 in the periphery of the gimbal 125. In other words,
the beam portion 133 extends from the portions 140 and 141 of the
gimbal 125, and the beam portion 134 extends from the portions 142
and 143 of the gimbal 125. The distance between the center of the
beam portion 133 and one of the two ends thereof is 1.sub.2.
Similarly, the distance between the center of the beam portion 134
and one of the two ends thereof is also 1.sub.2.
[0171] The beam portion 133 and the beam portion 131 form a
T-shaped beam 139A. Similarly, the beam portion 134 and the beam
portion 132 form a T-shaped beam 139B. The beam portions 131, 132,
133 and 134 form an H-shaped beam. It will be noted that the fixing
portion 130, the first pair of beams 131 and 132, and the second
pair of beams 133 and 134 are portions of the suspension 121.
[0172] The length 1.sub.1 of the first pair of beams 131 and 132 is
limited by the width W1 of the suspension 121. As the width W1 of
the suspension 121 is increased, the resonance frequency of a bend
and twist of the suspension 121 becomes lower, and the flying
characteristics of the slider 135 are degraded. For these reasons,
the width W1 cannot be increased. However, according to the
fourteenth embodiment of the present invention, it is possible to
increase the length 1.sub.2 of the second pair of beams 133 and 134
without being limited by the width W1 of the suspension 121. The
second pair of beams 133 and 134 is formed so that
1.sub.2>l.sub.1. That is, each of the T-shaped beams 39A and 39B
has a leg portion and an arm portion longer than the leg
portion.
[0173] When a waviness of the magnetic disk being rotated is
present or dust adheres to the magnetic disk, the magnetic head
slider 135 is rotated in a pitching direction indicated by an arrow
144 in a state in which the first pair of beams 131 and 132 and the
second pair of beams 133 and 134 are bent. At this time, a twist
deformation occurs in the first pair of beams 131 and 132 of the
gimbal 125, and a bend deformation occurs in the second pair of
beams 133 and 134.
[0174] As indicated by an arrow 145, the magnetic head slider 135
is rotated in a rolling direction also. At this time, bend
deformations occur in the beams 131 and 132 in the respective
directions opposite to each other, and bend deformations occur in
the beams 133 and 134 in the respective directions opposite to each
other.
[0175] FIG. 25 shows a resonance mode of the first-order bend. A
deformation occurs in the elastic portion 123 formed at the root of
the suspension 121, and the first pair of beams 131 and 132 and the
second pair of beams 133 and 134 are deformed in the same
direction.
[0176] FIG. 26 shows a resonance mode of the first-order twist. A
twist deformation occurs in the elastic portion 123 formed at the
root of the suspension 121 in such a manner so the right and left
portions of the elastic portion 123 have different heights. The
beam located on the right side of the gimbal 125 is deformed so as
to be formed into a convex shape facing upwards. The beam located
on the left side of the gimbal 125 is deformed so as to be shaped
into a convex facing downwards. When the lengths 1.sub.1 and
1.sub.2 are selected so that the length 1.sub.2 is equal to three
or four times the length 1.sub.1, the rotation stiffness responses
of the slider in the pitching and rolling directions become
sufficiently soft and are almost the same as each other.
[0177] As shown in FIG. 23, a composite type magnetic head 148 and
four terminals 1100A, 1100B, 1100C and 1100D are provided in the
magnetic head slider 135. The magnetic head 148 includes an MR head
for reproduction and an interactive type head for recording, these
heads being integrated with each other. The magnetic head 148 is
located at a rear end surface of the magnetic head slider 135 in a
relative movement direction 146 with respect to the magnetic disk
1222.
[0178] As shown in FIGS. 27 and 28, lead wires 115A, 115B, 115C and
115D are connected to the terminals 1100A, 1100B, 1100C and 1100D,
respectively. Each of the lead wires 115A through 115D has a
diameter of, for example, 30 .mu.m. The lead wires 115A-115D are
laid on the side opposite to the side on which the magnetic head
slider 135 is mounted, and are attached to a center portion 36 of
the fixing portion 130 by means of an adhesive 116, which can be an
insulation adhesive or an insulator containing an insulator.
Further, the lead wires 115A-115D extend along the longitudinal
center line 137 of the suspension 121 towards the base portion of
the suspension 121, and are fixed thereto at two points by means of
the adhesive 116.
[0179] Reference numbers 117.sub.-1, 117.sub.-2 and 117.sub.-3
respectively indicate a first fixing point, a second fixing point
and a third fixing point at which the lead wires 115A through 115D
are fixed by means of the adhesive 116. The first fixing point
117.sub.-1 moves in accordance with movement of the magnetic head
slider 135. Hence, it is unnecessary to be concerned about the
stiffness of portions of lead wires 115A through 115D between the
terminals 1100A-1100D and the first fixing point 117.sub.-1 and to
provide additional lengths of the lead wires 115A-115D. In FIG. 27,
such additional lengths of the lead wires 115A-115D are not
provided. The distance between the first fixing point 117.sub.-1
and the second fixing point 117.sub.-2 is long, and the stiffness
of the lead wires 115A-115B between the fixing points 117.sub.-1
and 117.sub.-2 little affects the rotation stiffness of the gimbal
125.
[0180] The magnetic head suspension unit 120 has the following
features. First, the rotation stiffness of the gimbal 125 is
considerably small because of the characteristics of the T-shaped
beams. Second, the gimbal 125 is supported at the four points
140-143, and hence, the resonance frequency of vibration of the
gimbal 125 is high even when the second pair of beams 133 and 134
is long. Third, the end of the suspension 121 can be formed so that
it has a small width W1, and hence the resonance frequency of
vibration of the suspension 121 is high. Fourth, the flying
stability of the magnetic head slider 135 is excellent due to the
above first, second and third features. The fifth feature of the
mechanism 120 is such that the first pair of beams 131 and 132 has
a short length l.sub.1 and is formed in the same plane. Hence, the
first pair of beams 131 and 132 has a large strength with respect
to force received in the contact start/stop operation, and a shear
failure does not easily occur in the beams 131 and 132. The sixth
feature of the mechanism 120 is such that the stiffness of the lead
wires 115A-115D does not affect the rotation stiffness of the
gimbal 125.
[0181] As has been described above, the gimbal 125 is formed so
that a pair of T-shaped beams (which form an H-shaped beam) is
provided with respect to the center of the gimbal 125, and hence a
low rotation stiffness and a high resonance frequency are achieved.
More specifically, the rotation stiffness of the mechanism 120
becomes one-third of that of the aforementioned IBM 3380 type head
suspension unit, while the resonance frequency of the mechanism 120
is as high as that of the IBM 3380 type head suspension unit. As a
result, it becomes possible to stably fly a compact slider having a
low airbearing stiffness.
[0182] Tables 1 and 2 show characteristics of the head suspension
unit 120 according to the fourteenth embodiment of the present
invention supporting a 2 mm-length slider, and the IBM 3380 type
head suspension unit supporting which a 3.2 mm-length slider.
1TABLE 1 COMPARISON OF STIFFNESS (static characteristics by
computer simulation) Stiffness 1st embodiment 3380 type pitch
stiffness 1.5 grf cm/rad 9.4 grf cm/rad roll stiffness 1.5 grf
cm/rad 5.1 grf cm/rad up/down stiffness 0.55 grf/mm 2.4 grf/mm
equivalent weight ratio 0.74 0.72
[0183]
2TABLE 2 COMPARISON OF RESONANCE FREQUENCY (dynamic characteristic
by computer simulation) Stiffness 1st embodiment 3380 type 1st bend
2.1 kHz 2.1 kHz 1st twist 2.3 kHz 2.6 kHz in-plane 8.5 kHz 5.7
kHz
[0184] In order to make the equivalent weight ratio ((supporting
spring equivalent weight)/(slider weight) of the fourteenth
embodiment equal to that of the IBM 3380 type mechanism, the total
length of the suspension unit is short (10 mm), which is
approximately half of that of the IBM 3380 type mechanism. Further,
the thickness of the suspension 121 of the fourteenth embodiment is
25 .mu.m, which is approximately one-third of that of the IBM 3380
type mechanism.
[0185] Table 1 shows data obtained by computer simulation. More
specifically, Table 1 shows the pitch stiffness and roll stiffness
of the gimbal 125 of the fourteenth embodiment, and the up/down
stiffness of the suspension 121 thereof. Further, Table 1 shows the
pitch stiffness and the roll stiffness of the gimbal of the IBM
3380 type mechanism, and the up/down stiffness of the suspension
thereof. It can be seen from Table 1 that the rotation stiffness
equal to one-third of the gimbal of the IBM 3380 type mechanism can
be obtained by optimizing the width and length of the grooves in
the gimbal 125.
[0186] Table 2 shows the resonance frequencies of the fourteenth
embodiment and the conventional IBM 3380 type mechanism obtained by
a computer simulation. The resonance frequencies of the fourteenth
embodiment are similar to those of the IBM 3380 type mechanism.
[0187] As will be seen from the above, the magnetic head suspension
unit according to the fourteenth embodiment of the present
invention has a low stiffness and a high resonance frequency.
[0188] A description will now be given of a fifteenth embodiment of
the present invention. In the following description, parts that are
the same as those shown in FIG. 23 are given the same reference
numbers.
[0189] FIG. 29 shows a magnetic head suspension unit 150 according
to the fifteenth embodiment of the present invention. The mechanism
150 includes a gimbal 151. The gimbal 151 is formed so that the
gimbal 125 shown in FIG. 23 is rotated about the center 136 by
90.degree.. Two T-shaped beams 152 and 153 are arranged in the
longitudinal direction of the suspension 121.
[0190] FIG. 30 shows a magnetic head suspension unit 160 having a
gimbal 161 according to a sixteenth embodiment of the present
invention. The gimbal 161 has the aforementioned first pair of
beams 131 and 132, and a second pair of beams 33A and 34A. The beam
133A and the beam 131 form an acute angle .alpha.. Similarly, the
beam 134A and the beam 132 form an acute angle equal to the acute
angle .alpha.. With the above structure, it becomes possible to
form, without increasing the width W1 of the suspension 121, the
second pair of beams 133A and 134A so that the length
2.times.1.sub.2a thereof is greater than the length 2.times.1.sub.2
of the second pair of beams 133 and 134 shown in FIG. 23. Further,
it is possible to narrow the end of the suspension 121. Hence, the
rotation stiffness of the gimbal 161 is less than that of the
gimbal 125 shown in FIG. 123. Thus, the magnetic head slider 135 in
the sixteenth embodiment can be more stably flied than that in the
fourteenth embodiment shown in FIG. 23.
[0191] FIG. 31 shows a magnetic head suspension unit 170 having a
gimbal 171 according to a seventeenth embodiment of the present
invention. A magnetic head slider 135A of the mechanism 170
includes flanges 172 and 173 formed on the respective sides of the
slider 35A. A magnetic head slider fixing portion 130A of the
gimbal 171 includes an opening 174 having a size corresponding to
the magnetic head slider 135A. The opening 174 is of a rectangular
shape defined by a rectangular frame 176. As shown in FIG. 31, the
magnetic head slider 135A engages the opening 174, and the flanges
172 and 173 are made to adhere to the frame 176 by means of an
insulation adhesive or an adhesive containing an insulator. In this
manner, the magnetic head slider 135A is fixed to the magnetic head
slider fixing portion 130A.
[0192] As shown in FIG. 32, the center G of gravity of the magnetic
head slider 135A is substantially located on the surface of the
suspension 121. Hence, in a seek operation, the magnetic head
slider 135A is moved by exerting a force on the center G of
gravity. Thus, an unnecessary rotation force about the center G of
gravity of the magnetic head slider 135A does not occur, and the
unbalance of the magnetic head slider 135A is reduced. As a result,
the magnetic head slider 135A can stably fly in the seek
operation.
[0193] Further, the height of the magnetic head assembly can be
reduced. Hence, it is possible to laminate layers of the head at
reduced intervals and to provide an increased number of disks per
unit length. As a result, it is possible to increase the volume
storage density of the magnetic disk drive and hence the storage
density.
[0194] FIG. 33 shows a magnetic head suspension unit 180 having a
magnetic head slider 135B according to an eighteenth embodiment of
the present invention. The magnetic head slider 135B has a flange
181 formed around the circumference thereof. The magnetic head
slider 135B engages the opening 174, and the flange 181 is adhered
to the magnetic head slider fixing portion 130A by means of an
adhesive which can be an insulation adhesive or an adhesive
containing an insulator. That is, the eighteenth embodiment of the
present invention differs from the seventeenth embodiment thereof
in that the whole circumference of the magnetic head slider 135B is
made to adhere to the fixing portion 130A. Hence, the adhesive
strength is increased and the reliability of the magnetic head
suspension unit is improved.
[0195] FIG. 34 shows a magnetic head suspension unit 190 according
to a nineteenth embodiment of the present invention. FIG. 35 shows
a free end of a suspension of the magnetic head suspension unit
190. The mechanism 190 is designed so that it does not have any
influence of the stiffness of lead wires, which affect flying of
the slider having a low airbearing stiffness. For example, when, in
the case where four lead wires are connected between the slider and
the suspension (see FIG. 27), each of the lead wires has a diameter
of 30 .mu.m and has an additional length (free length) of 1 mm, the
rotation stiffness of the gimbal is approximately five times that
of the gimbal in which there is no lead wire. This degrades the
flying stability of the slider.
[0196] The magnetic head suspension unit 190 has wiring patterns
191, 192, 193 and 194, which are formed by patterning a copper thin
film formed by, for example, plating by means of the
photolithography technique. The wiring patterns 191-194 extend on a
central portion of the lower surface of the suspension 121 in the
longitudinal direction. Each of the wiring patterns 191-194 is
approximately 5 .mu.m thick and 50 .mu.m wide. The thickness and
width of the wiring patterns depend on the resistance of the
conductive pattern and the capacity of the suspension 121.
[0197] Terminals 195A-195D made of copper are formed on the base
portion of the suspension 121. Further, terminals 196A-196D are
formed in a terminal area 130a of the magnetic head slider fixing
portion 130 of the gimbal 125. The tops of the terminals 195A-195D
and 196A-196D are plated by, for example, Au. This plating
contributes to preventing exposure of copper and improving the
bonding performance. Ends of the wiring patterns 191, 192, 193 and
194 are respectively connected to the terminals 195A, 195B, 195C
and 195D. The other ends of the two wiring patterns 191 and 192
extend along the beams 133A and 131, and are connected to the
terminals 196A and 196B, respectively. The other ends of the wiring
patterns 193 and 194 extend along the beams 134A and 132 and are
connected to the terminals 196C and 196D, respectively.
[0198] As shown in FIG. 36, the wiring patterns 191, 192, 193 and
194 are electrically insulated from the suspension 121 by means of
an insulating film 197, and are covered by a protection film 198.
The insulating film 197 and the protection film 198 are made of
photosensitive polyimide and are grown to a thickness of
approximately 5 .mu.m. The insulating film 197 and the protection
film 198 are respectively patterned by the photolithography
technique. The thickness of the insulating film 197 is determined
on the basis of a capacitance between the conductive pattern (made
of Cu) and the suspension (made of stainless steel).
[0199] As will be described later, polyimide has heat-resistance
enough for an annealing process. Since polyimide has
photosensitivity, it can be easily patterned. Further, the
polyimide films 197 and 198 have corrosion resistance, and
excellent reliability.
[0200] It is likely that the terminals 195A-195D and 196A-196D are
etched because these terminals are not covered by the protection
film 198. In order to prevent the terminals 195A-195D and 196A-196D
from being etched, the surfaces of these terminals are covered by
an Au film (not shown) having a thickness of approximately 1 .mu.m
formed by plating or vapor deposition.
[0201] As shown in FIG. 37, the magnetic head slider 135 is made to
adhere to the fixing portion 130 by means of an adhesive which can
be an insulation adhesive or an adhesive containing an insulator.
The terminals 196A-196D are located at a right angle with respect
to terminals 1100A-1100D of the magnetic head 148 formed on the end
surface of the magnetic head slider 135, and are respectively
connected to the terminals 1100A-1100D by means of Au balls
1101A-1101D. The Au balls 1101A-1101D are formed by means of, for
example, a gold ball bonding device. In order to facilitate
bonding, the terminals 196A-196D and terminals 1100A-1100D are
located as shown in FIG. 37. In order to facilitate a crimp
operation on the Au balls 1101A-1101D, the terminals 1100A-1100D
are long in the direction of the height of the magnetic head slider
135 and are located so that these terminals 1100A-1100D face the
terminals 196A-196D in the state where the head slider 135 is fixed
to the fixing portion 130.
[0202] In addition to FIG. 37, FIGS. 55-59 illustrate an embodiment
with a bonding ball connection in more detail.
[0203] FIG. 55 is a structural diagram of a magnetic disk apparatus
to which another embodiment of the present invention directed to
bonding balls is adapted, FIG. 56 is a cross section of the
structure in FIG. 55, FIG. 57 is a front view of an actuator in
FIG. 55, FIG. 58 is an explanatory diagram of the seventeenth
embodiment of this invention in FIG. 55, and FIG. 59 is a diagram
for explaining how to connect the embodiment.
[0204] FIG. 55 illustrates a magnetic disk apparatus which allows a
head to float onto a magnetic disk to execute magnetic
recording.
[0205] Provided on a base 60-1 of the apparatus are a 3.5-in
magnetic disk 5-1, which rotates around a spindle shaft 64-1, and a
magnetic circuit 63-1. An actuator 4-1 is mounted rotatable around
a rotary shaft 62-1.
[0206] A coil 41-1 is provided at the rear portion of this actuator
4-1, as shown in FIGS. 59, 56 and 57, and the coil 41-1 is located
in the magnetic circuit 63-1.
[0207] As shown in FIG. 56, nine arms 3-1 are formed at the front
portion of the actuator 4-1, each arm 3-1 are formed at the front
portion of the actuator 4-1, each arm 3-1 provided with support
plate (suspension) 7-1 which has a magnetic head core (core slider)
8-1 provided at the distal end.
[0208] This actuator 4-1, together with the coil 41-1 and magnetic
circuit 63-1, form a linear actuator. When current flow through the
coil 41-1, the actuator 4-1 rotates around the rotary shalt 62-1 to
move the magnetic head core 8-1 for a seek operation in a direction
perpendicular to the tracks of the magnetic disk 5-1 (radial
direction).
[0209] In FIG. 58, "7-1" is a support plate (suspension) made of
metal having a spring property, such as stainless. An insulating
layer is coated on the support plate, and a pair of wiring patterns
71-1 and suspension connector terminals 72-1 are formed thereon by
a copper pattern. The support plate 7-1 has its one end fixed to
the arm 3-1 by laser spot welding or the like.
[0210] "8-1" is a magnetic head core (core slider) which has a pair
of core slider connector terminals 82-1 and a thin-film magnetic
head 81-1 provided on the sides.
[0211] When the magnetic head core 8-1 is mounted on the support
plate 7-1, the connector terminals 72-1 of the support plate 7-1
and the connector terminals 82-1 of the magnetic head core 8-1 are
fixed with the positional relationship as shown in FIG. 58(B) and
59(A), and gold balls W about 0.1 mm in diameter are made to
contact both gold-plated connector terminals 82-1 and 72-1 and are
subjected to pressure bonding an ultrasonic bonding by a ball
bonder, the connector terminals 82-1 and 72-1 are electrically and
mechanically connected via the gold balls W due to intermetal
bonding. In this example, the magnetic disk 5-1 is located upward
of the diagram.
[0212] When the support plate 7-1 is provided with the wiring
patterns 71-1 and connector terminals 72-1 while the magnetic head
core 8-1 is provided with eh connector terminals 82-1, they can be
connected by gold ball bonding. Therefor, even the minute magnetic
head core 8 can easily be connected, thus accomplishing the
miniaturization of the magnetic head assembly.
[0213] Further, unlike lead wires, wiring is not necessary, so that
difficult wiring at the minute suspension is unnecessary, further
facilitating the assembling.
[0214] Furthermore, the number of components is reduced to make the
assembling easier and accomplish a small magnetic head
assembly.
[0215] FIG. 59(b) shows a modification of the seventeenth
embodiment in which a dummy terminal 83-1 is provided at the
flow-in side of the magnetic head core 8-1, and a dummy terminal
73-1 is provided on the wiring pattern 71-1 of the support plate
7-1 accordingly. With gold balls W about 0.1 mm in diameter in
contact with both gold-plated connector terminals 83-1 and 73-1,
pressure bonding and ultrasonic bonding are performed by a ball
bonder, those connector terminals 83-1 and 73-1 are connected
together via the gold balls W due to intermetal bonding.
[0216] Accordingly, the magnetic head core 8-1 has both ends
connected by the gold balls W to the support plate 7-1, so that
adhesion of the magnetic head core 8-1 to the support plate 7-1 is
unnecessary and the connection can be made by the ball bonding step
alone, further facilitating the assembly.
[0217] Although the lead wires are connected to the arm side
terminals (see FIG. 58(A)) of the wiring patterns 71-1 of the
support plate 7-1 before connecting to the arm 3-1 in this example,
this wiring is easy because the arm 3-1 is relatively large.
[0218] The wiring patterns 191-194 bypass holes 1102A, 1102B and
1102C, as shown in FIG. 34 and extend up to an area close to the
head slider 135. The hole 1102c is used to fix the suspension 121
to the arm 122 (not shown in FIG. 34). The holes 1102A, 110B and
1102C are sized such that a tool can be inserted therein.
[0219] As shown in FIGS. 34 and 35, dummy patterns 1103A-1103D and
1104A-1104D are provided so that these dummy patterns are
symmetrical to the bypassing portions of the wiring patterns
191-194 with respect to the holes 1102A and 1102B. The insulating
film 197 and the protection film 198 are provided for the dummy
patterns 1103A-1103D and 1104A-1104D in the same manner as the
wiring patterns 191-194. The dummy patterns 1103A-1103D and
1104A-1104D are provided in order to balance the mechanical
stiffness of the suspension 121 in the direction of the width of
the suspension 121.
[0220] As shown in FIG. 35, the wiring patterns 191-194 are
arranged so that these patterns form a loop. This loop functions as
an antenna, which receives noise components contained in the head
signals. As the size of the loop is increased, the degree of the
noise components is increased. In order to reduce the size of the
loop, the wiring patterns 191 and 192 respectively connected to the
terminals 196A and 196B are arranged between the hole 1102A and the
magnetic head slider 135, and all the wiring patterns 191-194 are
gathered in the vicinity of the hole 1102A. In order to balance the
stiffness in the direction of the width of the suspension, the
dummy patterns 1104A-1104D are formed. For the same reason as
above, the dummy patterns 1103A-1103D are formed in the vicinity of
the hole 1102B.
[0221] As shown in FIG. 35, auxiliary films 1106 and 1107 having a
belt shape are formed along the right and left ends of the
suspension 121. The auxiliary films 1106 and 1107 are provided in
order to receive a clamping force generated when the suspension 121
is clamped in a bending process which will be described later. Such
a clamping force is also received by the wiring patterns 191-194.
The clamping force is distributed so that the clamping force is
exerted on not only the wiring patterns 191-194 but also the
auxiliary films 1106 and 1107. Hence, it is possible to prevent the
wiring patterns 191-194 from being damaged.
[0222] As shown in FIGS. 34 and 35, a convex dummy pattern 1108 is
provided in order to prevent an adhesive from flowing from the
fixing portion 130 when the slider 135 is fixed to the fixing
portion 130 and to prevent the slider 135 from being tilted due to
the thickness of the wiring patterns. More particularly, the convex
pattern 1108 is used to form a groove in which an insulation
adhesive used to fix the slider 135 is saved between the pattern
1108 and the terminals 196A-196D. Further, the convex pattern 1108
is designed to have the same height as the patterns having the
terminals 196A-196D. If the dummy pattern 1108 is not used, the
slider 135 will be inclined with respect to the fixing portion 130
due to the height of the terminals 194A-194D. This degrades the
flying stability of the heads. Further, the use of the convex dummy
pattern 1108 increases the height of the adhesive to thus improve
the insulation performance. The convex pattern 1108 can be formed
by a cooper-plated thin film similar to the wiring patterns
191-194. The protection film 198 covers the convex pattern 1108.
The adhesive is provided on a step part between the wiring patterns
and the convex pattern 1108.
[0223] The suspension 121 is produced by a process shown in FIG.
38. First, a pattern formation step 1110 is performed. More
particularly, photosensitive polyimide is coated on a stainless
plate. The insulating film 197 is formed by the photolithography
technique. A copper film is formed by the plating process, the
vapor deposition process or the like, and is patterned into the
wiring patterns 191-194 by the photolithography technique.
Thereafter, photosensitive polyimide is coated and is patterned
into the protection film 198 and the auxiliary films 1106 and 1107
by the photolithography technique. Polyimide can be coated by a
spin-coat process, and is patterned and etched. A thin film, such
as a Cr film, can be formed in order to improve the adhesiveness
between the insulating film and the Cu film and between the Cu film
and the protection film and to improve the reliability of the
adhesion.
[0224] Next, an etching step 111 is performed in order to form the
openings 126-129 and the holes 1102A-1102C and the outward form of
the suspension in the stainless plate. FIG. 39 shows suspensions
1202 before punching for cutting off bridge portions (not shown) to
provide pieces, so that the suspensions 1202 are formed in a
stainless plate 1201 and arranged in rows and columns.
[0225] Then, a bending step 1112 is performed by bending the
respective ends of each of the suspensions 1202 formed in the
stainless plate 1201, so that ribs 121a are formed. The bending
step 1112 can be performed by press so that the suspensions 1202
are processed at the same time.
[0226] Finally, an annealing step 1113 is performed at a
temperature of approximately 400.degree. C., so that internal
stress can be removed. Further, a slider adhering step and an Au
bonding step can be automatically carried out before the
suspensions 1202 are punched. Hence, it is possible to
automatically perform the production process shown in FIG. 38 and
reduce the number of steps and the cost thereof.
[0227] The suspension 121 can be produced without performing the
annealing step 1113. In this case, as is shown in FIG. 40, the
pattern formation step 1110 and the etching step 1111 are
performed, and subsequently the slider adhering step and the Au
bonding step are carried out. Thereafter, the bending step 1112 is
carried out to form the ribs 121a.
[0228] As shown in FIG. 41, when interactive type heads 148A and
148B for recording and reproduction are used as magnetic heads, the
magnetic head slider 135 has the aforementioned two terminals 1100A
and 1100B. In the gimbal 125, the two wiring patterns 191A and 192A
are provided so that these wiring patterns extend on only the beams
132 and 134A, while two dummy patterns 1210 and 1211 are provided
so as to extend on the beam 131 and 133A in order to balance the
mechanical stiffness of the suspension 121 in the direction of the
width of the suspension 121.
[0229] The magnetic head suspension unit 190 has the following
features.
[0230] First, since the wiring patterns 191-194 are formed on the
suspension 121, it is not necessary to provide tubes for passing
the lead wires through the suspension 121. Hence, it is possible to
prevent unbalanced force caused by the lead wires and tubes from
being exerted on the magnetic head slider 135 and to stably fly the
magnetic head slider 135.
[0231] Second, due to use of the dummy patterns 1103A-1103D and
1104A-1104D, the rotation stiffness of the suspension 121 does not
have polarity. Hence, the magnetic head slider can fly stably.
[0232] Third, the crimp connection using the Au balls 1101A-1101D
enables automatic assembly and non-wire bonding between head
terminals and pattern terminals.
[0233] In the aforementioned embodiments of the present invention,
the beams may be curved.
[0234] A description will now be given of a magnetic head
suspension unit suitable for a more compact magnetic disk drive
according to a twelfth embodiment of the present invention.
[0235] FIG. 42 shows a back surface of a magnetic head suspension
unit 1230 according to the twelfth embodiment of the present
invention. FIG. 43 shows a 1.8-inch-type magnetic disk drive 1231
to which the magnetic head suspension unit 1230 is applied.
[0236] The magnetic disk drive 1231 has an enclosure 1232 having
almost the same dimensions as those of an IC memory card. In the
enclosure 1232, provided are a magnetic disk 1233 having a diameter
of 1.8 inches, and an actuator to which two sets of magnetic head
suspension units are attached. The magnetic disk drive 1231 is more
compact than the magnetic disk drive 1220 shown in FIG. 3.
[0237] A magnetic head slider 135C is made compact in accordance
with light-sizing of the magnetic disk drive 1231. More
particularly, dimensions a.times.b of the magnetic head slider 135C
are 0.8 mm.times.1.0 mm, and are approximately one-quarter the area
of the magnetic head slider 135 shown in FIG. 23. In order to
stably fly the compact magnetic head slider 135C, it is necessary
to considerably reduce the stiffness without decreasing the
resonance frequency, as compared with the magnetic head suspension
unit 130.
[0238] A suspension 1235 shown in FIG. 42 is made of stainless, and
has a base portion fixed to an arm 1236 of the actuator 1234 (see
FIG. 43). The suspension 1235 has a width W2 of approximately 2 mm,
a length L of approximately 9 mm, and a thickness to of
approximately 25 .mu.m, and is approximately a half of the volume
of the suspension 121 shown in FIG. 23. The suspension 1235 is
diminished, and hence the resonance frequency of bending which will
be described later is high.
[0239] The suspension 1235 is a sheet-shaped piece, and a flat
plate piece to which a bending process has not been subjected.
Hence, there is no problem of a bending process error which
degrades the flying stability of the magnetic head slider. The
suspension 1235 includes a suspension main body 1237 and a gimbal
1238 located on the end side of the suspension 1235. The gimbal
1238 has a substantially U-shaped opening (through hole) 1239
formed in the suspension 1235. The gimbal 1238 includes a magnetic
head slider fixing portion 1240, a first beam 1241, a second beam
1242, a third beam 1244, and a connecting portion 1243.
[0240] The magnetic head slider fixing portion 1240 has a size
corresponding to the magnetic head slider 135C. The first beam 1241
and the second beam 1242 extend along respective longitudinal ends
of the suspension 1235 from the end thereof. The connecting portion
1243 extends in the direction of the width of the suspension 1235,
and connects the first beam 1241 and the second beam 1242 together.
The third beam 1244 extends from the connecting portion 1243 to the
magnetic head slider fixing portion 1240 in the longitudinal
direction of the suspension 1235. The magnetic head slider fixing
portion 1240 is connected to the main body 1237 of the suspension
1235 via the third beam 1244, the connecting portion 1243 and the
first and second beams 1241 and 1242. Hence, the rotation stiffness
of the suspension 1230 can be reduced to a small value due to
bending of the entire beams.
[0241] As shown in FIG. 42, holes 1245, 1246 and 1247 with which a
tool is engaged, and a pair of slits 1248 and 1249 are formed in
the main body 1237 of the suspension 1235. Adjustment slits 1248
and 1249 are used to reduce the rotation stiffness of the
suspension. The holes 1245, 1246 and 1247 and the slits 1248 and
1249 are formed by etching. The connectors 195A-195D, 196A-196D and
the wiring patterns 191-194 are formed symmetrically with respect
to the longitudinal direction of the suspension 1235. The magnetic
head slider 135C is made to adhere to the fixing portion 1240, and
the terminals 196A-196D and 1100A-1100D are respectively connected
to each other by means of Au balls, as in the case shown in FIG.
37.
[0242] The structure shown in FIG. 42 does not use dummy patterns
because the length and the width of the suspension 1235 are less
than those of the suspension shown in FIG. 34 and the loop formed
by the wiring patterns is smaller than that shown in FIG. 34.
However, it is preferable to arrange the wiring patterns and
provide the dummy patterns as shown in FIGS. 34 and 35 in order to
reduce the noise from the heads.
[0243] As shown in FIGS. 44A and 44B, the free end of the arm 1236
is bent so that a substantially V-shaped cross section of the arm
1236 is formed in which the "V" is inverted. The free end of the
arm 1236 has an upward slant portion 1236a and a downward slant
portion 1236b declined at an angle .theta. with respect to the
horizontal direction.
[0244] The magnetic disk drive 1231 uses two magnetic head
suspension units 1230 so that the single magnetic disk 1233 is
sandwiched between the mechanisms 1230. As shown in FIG. 45, the
suspension 1235 causes the magnetic head slider 135C to come into
contact with the magnetic disk 1233 when the magnetic disk 1233 is
not being rotated. At this time, the main body 1237 of the
suspension 1235 is caused to be bent and elastically deformed. The
elastic force stored in the main body 1237 of the suspension 1235
generates a load F1, which urges the magnetic head slider 35C
towards the magnetic disk 1233.
[0245] Since the arm 1236 is bent in the form of the inverted "V",
a wide gap 1250 can be formed between an end 1236c of the arm 1236
and the magnetic disk 1233, as compared with a case indicated by a
two-dot chained line in which the arm 1236 is simply bent
downwards.
[0246] A description will now be given of a moment exerted on the
magnetic head slider 135C by means of the suspension 1235 when the
suspension is loaded on the disk. As shown in FIG. 46, the main
body 1237 of the suspension 1235 and the third beam 1244 are bent.
Hence, a moment is exerted by a center 1251 of the magnetic head
slider 35C. A moment M1 directed counterclockwise is exerted by the
suspension main body 1237 and the first and second beams 1241 and
1242. A moment M2 directed clockwise is exerted on the third beam
1244. The dimensions of the suspension 1235 are selected so that
the moments M1 and M2 are balanced. For example, the suspension
1235 is 9 mm long, and the gimbal 1238 is 2.5 mm long. Further, the
length and width of the main body 1235 of the suspension 1237 are
5.7 mm and 2 mm, respectively. With the above structure, it is
possible to stably fly the magnetic head slider 135C.
[0247] A description will now be given, with reference to FIG. 42,
of pitching and rolling of the magnetic head slider 135C.
[0248] (1) Pitching
[0249] The magnetic head slider 135C is rotated in the pitching
direction indicated by arrow 144 in such a manner that the first,
second and third beams 1241, 1242 and 1244 and the suspension main
body 1237 are bent. At this time, all the beams 1241, 1242 and 1244
are bent so as to be deformed in the form of arch shapes. The
gimbal 1238 is bent and hence the suspension main body 1237 is
bent. Hence, the pitch stiffness can be greatly reduced.
[0250] (2) Rolling
[0251] The magnetic head slider 135C is rotated in the rolling
direction indicated by arrow 145 in such a manner that the first
and second beams 1241 and 1242 are respectively bent in the
opposite directions and the suspension main body 1237 is twisted.
At this time, the gimbal 1238 is bent and hence the suspension main
body 1237 is bent. Hence, the rolling stiffness can be greatly
reduced.
[0252] A description will now be given of the first-order bend and
the first-order twist of the magnetic head suspension unit 1230
obtained when the suspension is vibrated.
[0253] (1) First-order bend
[0254] The suspension 1235 is bent and deformed, as shown in FIG.
47. More specifically, the suspension main body 1237, and the
first, second and third beams 1241, 1242 and 1244 of the gimbal
1238 are bent as shown in FIG. 45. The overall suspension 1235 is
formed flexibly, but the resonance frequency of the first-order
bend is high, while the stiffness is small.
[0255] (2) First-order twist
[0256] The suspension 1235 is twisted as shown in FIG. 48. The
gimbal 1238 is deformed and hence the suspension m body 1237 is
deformed. Hence, the overall suspension 1235 is flexibly formed,
but the resonance frequency of the first-order twist is high while
the stiffness thereof is low.
[0257] Tables 3 and 4 show characteristics of the magnetic head
support mechanism 1230 according to the twelfth embodiment of the
present invention and the magnetic head suspension unit 130 of the
fourteenth embodiment thereof shown in FIG. 23.
3TABLE 3 COMPARISON OF STIFFNESS (static characteristics by
computer simulation) Stiffness 7th embodiment 1st embodiment pitch
stiffness 0.44 grf cm/rad 1.5 grf cm/rad roll stiffness 0.24 grf
cm/rad 1.5 grf cm/rad up/down stiffness 0.36 grf/mm 0.55 grf/mm
equivalent weight ratio 0.76 0.74
[0258]
4TABLE 4 COMPARISON OF RESONANCE FREQUENCY (dynamic characteristics
by computer simulation) Stiffness 7th embodiment 1st embodiment 1st
bend 1.6 kHz 2.1 kHz 1st twist 4.4 kHz 2.3 kHz in-plane 7.1 kHz 8.5
kHz
[0259] More particularly, Table 3 the pitch stiffness, the roll
stiffness, and the up/down stiffness of the suspension 1235
obtained by means of a computer simulation. It can be from Table 3
that the pitch stiffness and the roll stiffness of the twelfth
embodiment of the present invention are approximately one-quarter
of those of the fourteenth embodiment thereof.
[0260] Table 4 shows the resonance frequencies of the fourteenth
and twelfth embodiments of the present invention obtained by a
computer simulation. It can be seen from Table 4 that the
first-order bend resonance frequency, the first-order twist
resonance frequency and the lateral resonance frequency are kept
very high.
[0261] It can be seen from Tables 3 and 4 that the magnetic head
suspension unit 1230 according to the twelfth embodiment of the
present invention has a resonance frequency as high as that of the
magnetic head suspension unit 130 according to the fourteenth
embodiment, and stiffness much less than that of the mechanism 130.
Hence, the compact magnetic head slider 135C can be stably
flied.
[0262] In an alternative of the suspension, the base portion of the
suspension 1237 is bent, so that the suspension is supported in the
same manner as shown in FIG. 23 and the load F1 shown in FIG. 45 is
obtained. In this case, only portions 1255 and 1256 outside of the
slits 1248 and 1249 are bent. Hence, unnecessary strain is not
exerted on the wiring patterns 191-194 located between the slits
1248 and 1249.
[0263] A first variation of the gimbal 1238 of the suspension 1235
will be described. A gimbal 1238.sub.-1 shown in FIG. 49 has a
first beam 1244.sub.-1 having a long width A, and an opening
1239.sub.-1 having a long length B. First and second beams
1241.sub.-1 and 1242.sub.-1 are long.
[0264] FIG. 50 shows a second variation 1238.sub.-2 of the gimbal
1238. The gimbal 1238.sub.-2 has first and second beams 1241.sub.-2
and 1242.sub.-2 each having a small width C.
[0265] FIG. 51 shows a third variation 1238.sub.-3 of the gimbal
1238. The gimbal 1238.sub.-3 has first and second variations
1241.sub.-3 and 1242.sub.-3 having a large width D.
[0266] FIG. 52 shows a fourth variation 1238.sub.-4 of the gimbal
1238. The gimbal 1238.sub.-4 has a fourth beam 1260 connecting the
center of the end of the magnetic head slider fixing portion 1240
and the suspension main body 1237 together. The fourth beam 1260
functions to prevent a deformation of the magnetic head slider
fixing portion 1240, but increases the rotation stiffness. Hence,
it is desired that the width of the fourth beam 1260 be as small as
possible and the length thereof are as long as possible.
[0267] FIG. 53 shows a fifth variation 1238.sub.-5 of the gimbal
1238. The gimbal 1238.sub.-5 has first and second arch-shaped beams
1241.sub.-5 and 1242.sub.-5.
[0268] As shown in FIG. 54, a bent connecting plate 1261 is fixed
to an arm 1236A, and the suspension 1235 is fixed to the connecting
plate 1261. Hence, it is not necessary to subject the arm 1236A to
bending stresses.
[0269] In the variations shown in FIG. 49 through 132, it can be
said that the third beam 1244 shown in FIG. 42 has the same width
as the fixing portion 1240 and is integrated with the fixing
portion 1240.
[0270] In the fourteenth through nineteenth embodiments, the load
applied to the magnetic head slider is generated by bending the
spring portion of the suspension. Alternatively, it is possible to
employ the arm fixing structure used in the twelfth embodiment of
the present invention in which the spring portion is kept flat.
[0271] The present invention is not limited to the specifically
disclosed embodiments and variations, and other variations and
modifications may be made without departing from the scope of the
present invention.
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