JP2002237016A - Head gimbals assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the HGA of an FSA structure capable of more effectively radiating heat from an IC chip. SOLUTION: The head gimbals assembly is provided with a magnetic head slider having at least one thin-film magnetic head element, an elastic stainless steel flexure having the magnetic head slider secured thereto, a stainless steel load beam for supporting the flexure and applying a specified load to the magnetic head slider, and IC chip having a circuit mounted thereon for the thin-film magnetic head element, an FPC having the IC chip mounted thereon, and a plate member having thermal conductivity higher than that of stainless steel which is secured to the backside of the FPC in an area including at least a part having the IC chip mounted thereon. In this case, the portion of the load beam corresponding to the plate member is partially eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head gimbal assembly (HGA) having a suspension for mounting an IC chip for a thin-film magnetic head element for use in, for example, a magnetic disk drive (HDD).

[0002]

2. Description of the Related Art In an HDD, a magnetic head slider attached to the tip of a suspension is levitated from the surface of a rotating magnetic disk. In this state, the magnetic disk slider is mounted on a thin-film magnetic head element mounted on the magnetic head slider. And / or reproduction from the magnetic disk.

[0003] With the recent increase in capacity and recording density of HDDs, the recording frequency has been increasing. One of the means for realizing this has been proposed for magnetic head elements. This is a structure (a chip-on-suspension structure) in which a part of the drive circuit is formed into an IC chip and mounted on a suspension. By adopting this structure, the wiring distance from the drive circuit to the magnetic head element is shortened, so that unnecessary noise added to the head drive signal can be reduced, and as a result, the recording characteristics in the high frequency region are improved. I do. In addition, the magnetoresistance effect (M
R) A weak signal output from the read head element can be amplified closer to the MR head element.

The size of the IC chip used in such a chip-on-suspension structure needs to be extremely small due to its mounting structure. However, when the size is reduced, the surface area is correspondingly reduced, and heat dissipation is considerably insufficient. Become. In addition, the IC chip must be mounted on a suspension with a small space, and in a high-frequency region near 500 MHz, the capacitance of a lead frame that becomes a terminal when packaged becomes noise and adversely affects the electrical characteristics. Need to be bare chip. For this reason, the heat radiation of the IC chip deteriorates, and the chip temperature rises. In addition, since an extremely large current flows through the IC chip during recording, heat generation becomes extremely large, so that insufficient heat dissipation is a serious problem.

On the other hand, a structure that does not use a lead wire as a wiring member for an IC chip and a magnetic head element has become widespread. That is, a structure (FSA (FSA) using a wireless suspension or a flexible printed circuit (FPC)
lex Suspension Assembly).

[0006] The wireless suspension is formed by directly forming a lead pattern in which a resin layer, a lead conductor layer and a resin layer are sequentially laminated as a wiring member on the suspension, or a resin on a stainless thin plate separate from the suspension. Layer, lead conductor layer and resin layer are sequentially laminated,
This is adhered on a suspension and configured.

In the FSA structure, a lead conductor is formed on a resin layer, and a resin coating layer is formed thereon to form an FPC, and the FPC is bonded to a suspension having no wiring member. . With the FSA structure, the cost of manufacturing the HGA is lower than with a structure using a wireless suspension.

Particularly, in a suspension having a chip-on-suspension structure, adopting such an FSA structure not only simplifies the mounting process because the IC chip can be mounted on the FPC in a sheet state, but also allows the mounting of the IC chip. Since the IC mounting can be evaluated at the FPC stage, even if there is a defect in the IC mounting,
Since the suspension, which is becoming very expensive, is not wasted, it is very advantageous in terms of reducing the manufacturing cost.

[0009]

However, as described above, the IC chip used in the chip-on-suspension structure generates extremely large heat due to its structure. Generally, the FPC has a very low thermal conductivity and is formed based on a resin layer of polyimide or the like that acts like a heat insulating material. Therefore, if the FPC has an FSA structure, it is difficult to radiate heat generated from the IC chip. .

Further, a leaf spring made of stainless steel is usually used as a spring member of the suspension.
Since stainless steel has a low thermal conductivity and is extremely thin as a metal material, heat dissipation from the suspension cannot be expected much when a chip-on-suspension structure is adopted.

As described above, when the chip-on-suspension structure and the FSA structure are used, the conventional HGA has the following (1)
Since the IC chip is very thin and small, it has a small surface area, and it is difficult to effectively take measures against heat generation. (2) FP
Since C is formed on the basis of a resin layer of polyimide or the like having a very low thermal conductivity, it is difficult to dissipate heat. (3) Since stainless steel used as a spring member of the suspension has a low thermal conductivity and is very thin, (4) I can not radiate enough heat with a normal chip-on-suspension structure
Since the C chip is mounted on the suspension on the side facing the magnetic medium, there is a problem that it is difficult to directly attach the heat dissipation structure to the IC chip itself.

If the temperature of the IC chip becomes high due to heat generation and little heat radiation, not only the operation of the IC becomes unstable but also the suspension may be thermally deformed.

Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide an HGA having an FSA structure capable of more effectively dissipating heat from an IC chip.

[0014]

According to the present invention, there is provided a magnetic head slider having at least one thin-film magnetic head element, a flexure made of stainless steel having elasticity for fixing the magnetic head slider, and a flexure supporting the flexure. A load beam made of stainless steel for applying a predetermined load to the magnetic head slider, an IC chip mounted with a circuit for a thin film magnetic head element, an FPC mounted with the IC chip, and an IC chip mounted thereon Affixed to the back surface of the FPC in a region including at least the portion;
A plate member having a higher thermal conductivity than stainless steel is provided, and an HGA in which a portion corresponding to the plate member of the load beam is partially removed is provided.

Since the plate member having a higher thermal conductivity than stainless steel is fixed to the back surface of the FPC at least in a region including the portion where the IC chip is mounted, not only the heat capacity of the portion is increased, but also the heat capacity is increased. Since the heat generated by the member with high conductivity can be diffused and cooled over a wide area, the temperature of the IC chip itself can be reduced and the local thermal load on the surrounding suspension can be reduced. can do. In addition, since a portion of the load beam corresponding to the plate member is partially removed, it is possible to add a plate member having a larger thickness and therefore a large heat capacity, and it is possible to further reduce the temperature of the IC chip. Become like As a result, FSA
Even in the case of a structure, the operation of the IC circuit can be stabilized, the thermal deformation of the suspension can be prevented, and further, the adverse effect of heat on the thin-film magnetic head element can be prevented.

It is preferable that a through hole or a concave portion is formed in a portion corresponding to the plate member of the load beam.

[0017] It is preferable that the apparatus further comprises a base plate fixed to the base of the load beam.

It is preferable that the plate member having higher thermal conductivity than stainless steel is a metal plate member containing one selected from Al, Cu, Mg, Al alloy, Cu alloy and Mg alloy.

[0019]

FIG. 1 is a perspective view showing a schematic structure of an HGA according to an embodiment of the present invention, and FIG.
FIG. 3 is a side view of the HGA viewed from the lateral direction, and FIG. 4 is an exploded side view of the HGA.

As shown in these figures, the HGA has a magnetic head slider 11 having at least one thin-film magnetic head element fixed to a tip end of a suspension 10 and a head drive and readout at an intermediate position of the suspension 10. It is configured by mounting an IC chip 12 for signal amplification. The magnetic head slider 11 and the IC chip 12
The suspension 10 is mounted on the surface of the suspension 10 facing the magnetic disk medium so as to face the surface of the magnetic disk medium.

The suspension 10 has an elastic flexure 13 for supporting the magnetic head slider 11 at the end.
, A flexure 13 supported and fixed at the distal end thereof, which is also elastic, a load beam 14, a base plate 15 provided at the base of the load beam 14,
2 is supported at an intermediate portion thereof, and a magnetic head slider 1 is supported.
Flexible printed circuit (F) having lead conductors and connection pads electrically connected to IC chip 12 and IC chip 12.
PC 16).

The magnetic head slider 11 has at least one thin-film magnetic head element formed by a write head element and an MR read head element. The size of the magnetic head slider 11 is merely an example, but it is 1.25.
mm × 1.0 mm × 0.3 mm.

In the IC chip 12, a drive circuit as a head amplifier and a read signal amplifying circuit are mounted as ICs. Although the size of the IC chip 12 is merely an example, it is 1.4 mm × 1.0 mm × 0.13 mm. Thus, the IC chip 12 has a very small and thin shape.

The flexure 13 has a soft tongue 1 centered on a dimple provided between the flexure 13 and the load beam 14.
3a, and the magnetic head slider 11 is
It has elasticity to flexibly support and stabilize the floating posture. In this embodiment, the flexure 13 is made of a stainless steel plate having a thickness of about 25 μm (for example, SUS304T).
A) and has a substantially uniform width. The flexure 13 is fixed to the tip of the load beam 14 by spot welding using a laser beam or the like.

The FPC 16 is formed by forming a lead conductor and a connection pad as a wiring member on a resin layer, and forming a resin coating layer on the lead conductor. Is fixed with an adhesive. The FPC 16 has a structure floating in a space behind the base plate 15.

One end of each of the plurality of lead conductors formed on the FPC 16 is connected to a head connection pad 17 formed on one end (tip) of the FPC 16 which is connected to a terminal electrode of the magnetic head slider 11. And the other end is FP
It is connected to an external circuit connection pad 18 formed on the other end (rear end) of C16. An IC chip connection pad 19 to which the mounted IC chip 12 is electrically connected is formed in the middle of the lead conductor.

On the back surface of the FPC 16 corresponding to the position where the IC chip 12 is mounted, a plate member 20 having a higher thermal conductivity than stainless steel is provided over a region including at least the portion where the IC chip 12 is mounted. Closely adhered.

In this embodiment, A is used as the plate member 20.
One plate is used. The size of the Al plate 20 is merely an example, but is approximately 5.0 mm × 2.0 mm × 0.15 m
m. The Al plate has high thermal conductivity, is lightweight and is most preferable in terms of corrosion resistance, but is not limited to this, and is selected from Al, Cu, Mg, Al alloy, Cu alloy, and Mg alloy. It is possible to use a metal plate member including one of the above.

The load beam 14 has elasticity for pressing the magnetic head slider 11 in the direction of the magnetic disk to stabilize the flying height. This load beam 14
Is formed of an approximately 60-65 μm thick elastic stainless steel plate having a through hole 14a on the inner side, and has a flexure 13 at its distal end and an FPC 16 at its distal end. It is supported at the rear end. The through hole 14a is provided at a position corresponding to the plate member 20, and has a size and a shape in which the plate member 20 is accommodated in the hole with a gap. This allows
Even when the thickness of the plate member 20 is increased, the inconvenience of generating a gap between the FPC 16 and the load beam 14 is eliminated. In other words, the thickness of the plate member 20 can be increased and the heat capacity thereof can be increased without generating a gap between the two. Obviously, a recess may be provided instead of the through hole.

As in the present embodiment, the flexure 1
In a three-piece suspension in which the load beam 3 and the load beam 14 are independent components, the rigidity of the load beam 14 is higher than the rigidity of the flexure 13. The flexure 13 and the load beam 14 may not be separately provided, and may be a two-piece suspension of a base plate and a flexure load beam.

The base plate 15 is provided with the load beam 14
It is made of thicker stainless steel and is fixed to the base of the load beam 14 by spot welding using a laser beam or the like. The HGA is mounted on the support arm by mechanically caulking the mounting portion 15a of the base plate 15 to a support arm (not shown).

The IC chip 12 is a bare chip.
For example, a gold ball 21 is connected to a connection pad provided on the PC 16.
Flip-chip mounting. IC chip 1
The gap between the bottom surface of the substrate 2 and the thin film pattern is filled with an underfill layer for improving heat radiation characteristics, improving mechanical strength, and covering the IC chip 12.

As described above, although the IC chip 12 is very small and thin, it has several tens mA.
A large amount of heat is generated in order to allow the writing current to flow. In the suspension of the conventional structure, this heat not only affects the IC chip itself, but also affects the MR head element and locally applies the stainless steel constituting the flexure and load beam which are spring members of the suspension. Heating problem. In particular, in an HGA having an FSA structure, it is very difficult to radiate heat generated from an IC chip because the thermal conductivity of the FPC is extremely low. Although the IC chip can be somewhat cooled by the air cooling effect by the rotation of the magnetic disk, the air cooling effect cannot be expected so much because the IC chip itself has a very small surface area. In addition, since the clearance between the IC chip and the surface of the magnetic disk is very small, it is difficult to take measures to further enhance the air cooling effect on the IC chip side of the suspension, which means that contact with the surface of the magnetic disk is completely suppressed.

Therefore, in the suspension having the conventional structure, heat is hardly transmitted in the FPC and the suspension having low thermal conductivity, so that heat is hardly dissipated, and the IC is hardly dissipated.
The chip itself and the IC chip mounting portion of the suspension locally become hot.

On the other hand, in the present embodiment, as is clear from FIGS. 3 and 4, the IC chip 12 is mounted on the back surface of the FPC 16 corresponding to the position where the IC chip 12 is mounted. A plate member having higher thermal conductivity than stainless steel, at least over a region including the portion, that is, A
Since the 1 plate 20 is adhered, the heat generated in the IC chip 12 is conducted throughout the Al plate 20 and diffused over a wide area, so that the IC chip 12 can be cooled effectively. . Further, since the heat capacity of the suspension is increased by the Al plate 20 itself acting as a heat sink, the cooling of the IC chip 12 is promoted in that sense.

As described above, the temperature of the IC chip itself can be reduced, and the local thermal load on the surrounding suspension can be reduced. As a result, I
This makes it possible to stabilize the operation of the C circuit, prevent thermal deformation of the suspension, and prevent the thin-film magnetic head element from being adversely affected by heat. And HGA
It does not hinder the space between the disk and the magnetic disk.

The Al plate 20 is provided with
Although the temperature of the C chip 12 decreases, as the thickness increases, the heat capacity increases and the thermal conductivity can be increased by employing Al, so that the heat dissipation improves. In particular, in the present invention, since the through holes 14a are formed at the corresponding positions of the load beam 14, even if the Al plate 20 is thickened to increase the heat capacity, the problem that the FPC 16 rises does not occur. However, if the Al plate 20 is too thick, the mechanical properties of the suspension deteriorate due to the increase in weight. Therefore, the upper limit of the thickness is about 500 μm.

The larger the area of the Al plate 20, the larger the heat capacity and the larger the surface area exposed to the air, so that the heat radiation becomes better. However,
Since it is better not to transmit heat to the magnetic head slider 11,
It is desirable that the Al plate 20 be shaped so as to extend from the portion where the IC chip 12 is mounted to the base plate 15 side.

If the plate member 20 is provided on the back surface of the FPC 16 on which the IC chip 12 is mounted, ultrasonic waves can be efficiently applied to the bonding portion when the IC chip 12 is subjected to ultrasonic bonding. The stability of chip mounting is improved.

The embodiments described above all show the present invention by way of example and not by way of limitation, and the present invention can be embodied in other various modifications and alterations. Therefore, the scope of the present invention is defined only by the appended claims and their equivalents.

[0041]

As described above in detail, according to the present invention, the plate member having a higher thermal conductivity than stainless steel can be used in the region including at least the portion where the IC chip is mounted.
Since it is fixed to the back surface of the PC, not only does the heat capacity of that portion increase, but also the heat generated by the member having high thermal conductivity can be diffused over a wide area and cooled, so that the IC chip itself can be cooled. Temperature can be reduced, and the local thermal load on the surrounding suspension can be reduced. In addition, since a portion of the load beam corresponding to the plate member is partially removed, it is possible to add a plate member having a larger thickness and therefore a large heat capacity, and it is possible to further reduce the temperature of the IC chip. Become like As a result, even in the case of the FSA structure, the operation of the IC circuit can be stabilized, the thermal deformation of the suspension can be prevented, and further, the adverse effect of heat on the thin-film magnetic head element can be prevented.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic structure of an HGA according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of the HGA in the embodiment of FIG.

FIG. 3 is a side view of the HGA in the embodiment of FIG. 1 as viewed from a lateral direction.

FIG. 4 is an exploded side view of the HGA in the embodiment of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Suspension 11 Magnetic head slider 12 IC chip 13 Flexure 13a Tongue 14 Load beam 15 Base plate 15a Attachment part 16 FPC 17 Head connection pad 18 External circuit connection pad 19 IC chip connection pad 20 High thermal conductivity plate member, Al plate 21 Gold Ball

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ken Wada 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Corporation (72) Inventor Norioka Ota 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Co., Ltd. (72) Inventor Kazumasa Shiraishi No. 38-42, Hong Kong Shinkai Aoi Sakurai Fukuoka F-term (Reference) 5D042 NA02 PA01 PA09 TA07 TA09 5D059 AA01 BA01 CA26 CA29 DA26 DA33 DA36 EA08

Claims (5)

[Claims] 1. A magnetic head slider having at least one thin-film magnetic head element, a flexure made of elastic stainless steel for fixing the magnetic head slider, and supporting the flexure. A load beam made of stainless steel for applying a predetermined load, an IC chip on which a circuit for the thin-film magnetic head element is mounted, and an FPC on which the IC chip is mounted
And a plate member having a higher thermal conductivity than stainless steel fixed to the back surface of the FPC in a region including at least a portion where the IC chip is mounted, and corresponds to the plate member of the load beam. A head gimbal assembly, wherein a portion is partially removed. 2. The head gimbal assembly according to claim 1, wherein a through hole is formed in a portion of the load beam corresponding to the plate member. 3. The head gimbal assembly according to claim 1, wherein a concave portion is formed in a portion of the load beam corresponding to the plate member. 4. The apparatus according to claim 1, further comprising a base plate fixed to a base of the load beam.
The head gimbal assembly according to any one of claims 1 to 3. 5. A plate member having a higher thermal conductivity than the stainless steel is made of Al, Cu, Mg, an Al alloy, a Cu alloy and M
The head gimbal assembly according to any one of claims 1 to 4, wherein the head gimbal assembly is a metal plate member including one selected from g alloys.