JPH10134529A - Flexible printed circuit with damping sheet and disk device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a disk device in which the vibration of a flexible printed circuit(FPC) can be suppressed by a damping sheet, which realizes the FPC having the long bending life of a conductor pattern and which suppresses the vibration of an actuator. SOLUTION: In this disk device, a cover film 15 which is bonded, by a second adhesive 14, to the surface of a conductor pattern 13 which is bonded, by a first adhesive 12, to one face of a base film 11 is used, and an FPC which is bonded to the other face of the base film 11 or to the surface of the cover film 15 and which is provided with a damping sheet 17 is used. The thickness of the base film 11, that of the cover film 15 and that of the damping sheet 17 are selected in such a way that the conductor pattern 13 is situated in the center of their thickness direction. Thereby, a neutral face N is situated at the inside of the conductor pattern 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base film, a conductor pattern adhered to one surface of the base film by a first adhesive, and a cover adhered to the surface of the conductor pattern by a second adhesive. The present invention relates to a flexible printed circuit having a film and a vibration damping sheet adhered to at least one of the other surface of the base film or the surface of the cover film.

Further, the present invention provides a disk, a disk drive for driving the disk, a head for reading / writing data from / to a recording surface of the disk, and an actuator having an arm for supporting the head. One end is supported on the actuator side to electrically connect an actuator drive unit for driving the actuator and a circuit unit on the device main body side to the head so that the head moves in a direction crossing the track of the disk. The present invention relates to a disk device having a flexible printed circuit, the other end of which is supported by the device main body, and which bends in accordance with the swing of an actuator.

In recent years, as the applications of personal computers and the like have expanded, disk devices such as magnetic disk devices mounted on these devices have been required to be smaller and thinner in shape, and larger in storage capacity. Is required.

For this reason, higher recording density has been promoted, and it has been demanded that the movement of the head by the actuator be performed with high accuracy and without vibration. Accordingly, it has become necessary to suppress the vibration of a flexible printed circuit (hereinafter, referred to as FPC) that bends in response to the swing of the actuator by using an FPC with a vibration damping sheet.

[0005]

2. Description of the Related Art FIG. 9 is a sectional view showing an example (longitudinal section) of an FPC with a vibration damping sheet used in a conventional magnetic disk drive. In this figure, the base film 1 is X
Has a strip-shaped planar shape that is long in the direction, and has a conductive pattern 3
Is glued. Further, a cover film 5 is adhered to the surface of the conductor pattern 3 with a second adhesive 4.

The base film 1, the first adhesive 2, the conductor pattern 3, the second adhesive 4, and the cover film 5 constitute a main body (hereinafter, referred to as an FPC main body) 6 of the FPC.

[0007] A vibration damping sheet 7 for damping vibration is adhered to the other surface (back surface) of the FPC body 6, specifically, the base film 1. This damping sheet 7
Is obtained by laminating a viscoelastic material 7b on a sheet-like support 7a, and the viscoelastic material 7b is adhered to the base film 1.

[0008] The viscoelastic material is, for example, a polymer material having a dynamic behavior having both the viscosity of a fluid and the elasticity of a spring. When the material is pulled and released, it slowly returns to its original shape due to viscous resistance. It returns to its shape.

FIGS. 10 and 11 are sectional views showing a state (longitudinal section) in which the FPC shown in FIG. 9 is bent so that the cover film side becomes convex and concave, respectively. When the FPC is bent, the outer part of the bend expands and the inner part of the bend shrinks, but there is a surface that does not expand or contract in the middle. This plane is called the neutral plane, and the line of intersection between the neutral plane and the cross section is called the neutral axis. 9 to 11, the position of the neutral plane N is indicated by a dashed line.

When manufacturing an FPC with a vibration damping sheet,
The FPC body 6 and the vibration damping sheet 7 manufactured independently of each other are purchased and combined. In this combined configuration, no study has been made on where the neutral plane N is located or where it should be located.

In the conventional FPC body 6, since the base film 1 and the cover film 5 having the same thickness are arranged so as to sandwich the conductor pattern 3, the conductor pattern 3
Is located at the center of the FPC body 6. For this reason, the base film 1 is located substantially at the center in the thickness direction of the entire FPC with the vibration damping sheet having the vibration damping sheet 7 adhered to the back surface of the base film 1.

The layers constituting the FPC with the vibration-damping sheet have different longitudinal elastic coefficients, and particularly, the conductor pattern 3 made of metal has a large longitudinal elastic coefficient. For this reason, the neutral plane N as the whole FPC with the vibration damping sheet is closer to the conductor pattern 3 than the center position in the thickness direction, but still has the base film 1 as shown in FIGS. Exist inside.

On the other hand, contrary to the case of FIGS.
When the damping sheet 7 is adhered to the surface of the cover film 5 constituting the C body 6, the neutral surface N of the whole FPC with the damping sheet exists at a position near the conductor pattern 3 inside the cover film 7. I do.

In the magnetic disk drive having the above-mentioned FPC with vibration damping sheet, the FPC with vibration damping sheet is used to electrically connect the circuit section of the apparatus body and the head.
, One end of which is supported on the actuator side and the other end is supported on the device body side, and is bent in accordance with the swing of the actuator.

[0015]

In the conventional FPC with a vibration damping sheet, the neutral plane N is located inside the base film 1 or inside the cover film 7. In other words, the conductor pattern 3 exists at a position away from the neutral plane N.

When the conductor pattern 3 is separated from the neutral plane N, for example, in the bent state shown in FIG. 10, a tensile force acts on the conductor pattern 3 according to the degree of bending. That is, a greater tensile force acts on a position farther from the neutral plane N, and a greater tensile stress is generated inside the conductor pattern 3.
Conversely, in the bent state shown in FIG. 11, a compressive force acts on the conductive pattern 3 in accordance with the degree of bending, and a large compressive stress is generated inside the conductive pattern 3.

In an operating environment in which one end of the FPC with the vibration damping sheet is attached to the movable portion and the degree of bending varies, a stress is repeatedly applied to the bent portion of the conductive pattern 3 made of metal. In this case, if the amplitude of the repetitive stress is large, the fatigue progresses quickly and the fatigue failure of the conductor pattern 3 occurs early. On the other hand, if the stress amplitude is small, the progress of fatigue is slowed down, and the number of repetitions up to fatigue failure is significantly increased. Further, if the stress amplitude is less than a certain value (fatigue limit), the fatigue fracture of the conductor pattern 3 due to the repeated stress is reduced. Will not occur. The fatigue limit also changes depending on the average value (average stress) of the upper limit value and the lower limit value of the repeated stress.

As described above, when a repetitive load is applied to the conductor pattern 3 due to a change in bending, if the repetitive load exceeds a certain value, excessive repetitive stress acts on the conductor pattern 3 and the conductor pattern 3 is broken by fatigue. become.
In particular, the neutral surface N
Is present inside the base film 1 or inside the cover film 7 and the conductor pattern 3 is separated from the neutral plane N, the repetitive load applied to the conductor pattern 3 and thus the repetitive stress become large, and fatigue fracture is reached. Time (flexing life) sharply decreases.

In a conventional disk drive using the above-mentioned FPC with a vibration-damping sheet for electrically connecting the circuit section on the apparatus body side and the head, the above-mentioned FPC with a vibration-damping sheet is provided in accordance with the swing of the actuator. The FPC is bent, and a large repetitive load is applied to the conductor pattern in the FPC with the vibration damping sheet. Also in this case, excessive repetitive stress acts on the conductor pattern, and the conductor pattern will be fatigue-ruptured early.

Fatigue destruction of the conductor pattern means disconnection in the FPC with the vibration damping sheet, and cuts off the electrical connection between the circuit section on the apparatus body side and the head. Therefore, the conventional disk device using the FPC with the vibration damping sheet suppresses the vibration of the actuator by the function of the vibration damping sheet.
Although the movement of the head by the actuator can be performed with high accuracy, the disconnection of the FPC with the vibration damping sheet occurs at an early stage, so that there is a problem that the reliability of the disk device is low.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to realize an FPC with a vibration damping sheet which can suppress the vibration of the FPC by the vibration damping sheet and has a long flex life of the conductor pattern. It is another object of the present invention to provide a disk device that suppresses the vibration of an actuator by using an FPC with a vibration damping sheet, wherein the occurrence of disconnection of the FPC with a vibration damping sheet is suppressed and the reliability is improved.

[0022]

According to the first aspect of the present invention, there is provided an FPC with a vibration damping sheet, comprising: a base film 11; The conductive pattern 13 adhered by the adhesive 12 and the second adhesive 1 on the surface of the conductive pattern 13.
4 and a vibration damping sheet 17 adhered to the other surface of the base film 11. Alternatively, as shown in FIG. 2, a base film 11, a conductor pattern 13 adhered to one surface of the base film 11 with a first adhesive 12, and a second adhesive 14 attached to the surface of the conductor pattern 13. It has a cover film 15 adhered and a vibration damping sheet 17 adhered to the surface of the cover film 15.

1 and 2, the relationship between the thickness of the cover film 15, the thickness of the base film 11, and the thickness of the vibration damping sheet 17 is such that the neutral plane N is located inside the conductor pattern 13. You have been selected to.

According to this configuration, since the neutral plane N exists inside the conductor pattern 13, for example, one end of the FPC with the vibration damping sheet is attached to the movable portion, and the use is performed in a usage environment in which the degree of bending varies. Even in this case, the repeated load applied to the bent portion of the conductor pattern 13 is small, and the occurrence of fatigue fracture can be suppressed or prevented. Therefore, the flex life becomes longer. Of course, in this configuration, the vibration damping sheet 17 sufficiently exhibits its function.

According to a second aspect of the present invention, there is provided an FPC with a vibration damping sheet, wherein the thickness H1 of the cover film 15 is equal to the thickness of the base film 11 and the thickness of the vibration damping sheet 17 in the configuration shown in FIG. The thickness H2 is selected to be equal to the total thickness H2.

According to this configuration, since the neutral plane N exists substantially inside the conductor pattern 13, for example, one end of the FPC with the vibration damping sheet is attached to the movable part, and in a use environment where the degree of bending varies. Even in this case, the repeated load applied to the bent portion of the conductor pattern 13 is small, and the occurrence of fatigue fracture can be suppressed or prevented. Therefore, the flex life becomes longer. Of course, in this configuration, the vibration damping sheet 17 sufficiently exhibits its function.

According to a third aspect of the present invention, there is provided an FPC with a vibration damping sheet, wherein the thickness H3 of the base film 11 is equal to the thickness of the cover film 15 and the thickness of the vibration damping sheet 17 in the configuration shown in FIG. The thickness is selected to be equal to the thickness H4.

Also in this configuration, since the neutral surface N exists substantially inside the conductor pattern 13, for example, one end of the FPC with the vibration damping sheet is attached to the movable portion, and in a use environment where the degree of bending varies. Even so, the repeated load applied to the bent portion of the conductor pattern 13 is small, and the occurrence of fatigue fracture can be suppressed or prevented. Therefore, the flex life becomes longer. Of course, also in this configuration, the vibration damping sheet 17 sufficiently exhibits its function.

According to a fourth aspect of the present invention, there is provided a disk drive, comprising: a disk; a disk drive unit for rotating the disk; and a head for reading / writing data from / to a recording surface of the disk. An actuator having an arm for supporting the head, an actuator driving unit for driving the actuator so that the head moves in a direction traversing the track of the disk, and an electrical connection between the circuit unit on the apparatus body side and the head. An FPC, one end of which is supported on the actuator side and the other end of which is supported on the device main body side, and which bends in response to the swing of the actuator, wherein the FPC with the vibration damping sheet according to the invention of claim 2 is provided as the FPC. It is characterized by using.

In this disk device, even in a use environment in which the degree of bending varies, an excessive repetitive stress does not act on the conductor pattern. Therefore, disconnection of the FPC with the vibration damping sheet hardly occurs. High reliability.
In addition, since the vibration of the actuator is suppressed by the function of the vibration damping sheet as in the conventional disk device, the head can be moved by the actuator with high accuracy.

According to a fifth aspect of the present invention, there is provided a disk drive, comprising: a disk; a disk drive unit for rotating the disk; and a head for reading / writing data from / to a recording surface of the disk. An actuator having an arm for supporting the head, an actuator driving unit for driving the actuator so that the head moves in a direction traversing the track of the disk, and an electrical connection between the circuit unit on the apparatus body side and the head. An FPC, one end of which is supported on the actuator side and the other end is supported on the apparatus main body side, and which bends in response to the swing of the actuator, wherein the FPC with the vibration damping sheet according to the invention of claim 3 is provided as the FPC. It is characterized by using.

Also in this disk device, even in a use environment in which the degree of bending varies, an excessive repetitive stress does not act on the conductor pattern.
Disconnection of C hardly occurs, and the reliability as a disk device is high. Moreover, since the vibration of the actuator is suppressed by the function of the vibration damping sheet as in the conventional disk device,
The head can be moved by the actuator with high accuracy.

[0033]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) A first embodiment is a common embodiment of the FPC with a vibration damping sheet according to the first and second aspects of the present invention and the disk device according to the fourth aspect of the invention, that is, the vibration damping. 1 is an example of a form relating to a disk device having an FPC with a sheet.

FIG. 3 is a perspective view showing an embodiment of a magnetic disk drive provided with an FPC with a vibration damping sheet, with a cover removed, and FIG. 4 is a partial view showing the configuration of the actuator and its periphery in FIG. It is a fracture | rupture perspective view. FIG. 5 is a sectional view showing the configuration (longitudinal section) of the FPC with a vibration damping sheet in FIG.

In these figures, a disk (magnetic disk) 21 is coaxially stacked at a certain interval in a direction perpendicular to the recording surface thereof, and is rotated by a spindle motor 22 as a disk drive. Has become. On the other hand, the actuator 23 is rotatably supported on the base plate 30 by a shaft 24 provided near the outer peripheral portion of the disk 21.

The actuator 2 has a disk 2
In order to support a magnetic head for reading / writing data on the first recording surface, an arm 25 extends above the recording surface of the disk 21, and a suspension 27 is attached to a tip end of the arm 25. A magnetic head (more precisely, a slider with a magnetic head) as the head for reading / writing data
28 are attached.

In this embodiment, one magnetic head 28 faces one recording surface of the disk 21.
Therefore, only one suspension 27 is attached to the arm 25 at the uppermost position and the lowermost position, and two suspensions 27 are attached to the arm 25 at the intermediate position.

The actuator driving section 3 is located at a position opposite to the direction in which the arm 25 extends in the actuator 23.
1 is provided. The actuator driving section 31 drives the actuator 23 so that the magnetic head 28 moves in a direction crossing the track of the disk 21.

The actuator driving section 31 is composed of a moving coil type linear motor (VCM: voice coil motor), and includes a coil 32 fixed to a holding frame 26 at a rotating end of the actuator 23, A magnetic circuit 33 is provided on the base plate 30 and arranges the coil 32 in the magnetic gap.

The magnetic circuit 33 of this embodiment includes an upper yoke 34 and a lower yoke 37 facing each other, an upper magnet 35 and a lower magnet 36 fixed to the inner surfaces of the upper yoke 34 and the lower yoke 37, respectively. It is composed of side yokes 38 and 39 sandwiched between lower yokes 37, and is fixed on the base plate 30 by screws 40. The coil 32 is arranged in a magnetic gap between the upper magnet 35 and the lower magnet 36.

An FPC 60 with a damping sheet is provided to electrically connect a circuit section (not shown) on the apparatus main body side to the magnetic head 28. This FPC 60 is shown in FIG.
As shown in the figure, the FPC body 66 and the FPC body 66
And a vibration damping sheet 67 adhered to.

Here, the FPC body 66 has a thickness of, for example, 2
Base film 6 made of 5 μm polyimide film, etc.
1 and a thickness of 20 on one surface of the base film 61, for example.
For example, a thickness of 3 μm bonded by the first adhesive 62 of μm
A conductor pattern 63 made of a copper foil pattern of 5 μm or the like, and a cover film 65 made of a polyimide film or the like having a thickness of 100 μm adhered to the surface of the conductor pattern 63 by a second adhesive 64 having a thickness of 20 μm, for example. Have been.

The vibration damping sheet 67 has a thickness of, for example, 25 μm.
A viscoelastic material 67b having a thickness of, for example, 50 μm is laminated on a sheet-like support 67a such as a polyimide film having a thickness of 50 m, and the viscoelastic material 67b is adhered to the other surface (back surface) of the base film 61. In addition, this damping sheet 6
7, the base film 61 and the cover film 65 are all non-metallic, and their longitudinal elastic modulus is smaller than that of the conductive pattern 3 made of metal.

In the FPC 60, the thickness H 1 (100 μm) of the cover film 65 is different from that of the base film 61.
Thickness (25 μm) and the thickness of the damping sheet 67 (75 μm)
m) and the thickness H2 (100 μm).

In this embodiment, one end of the FPC 60 is supported on a side surface near the rotation center of the actuator 23.
Although not shown, for example, an integrated circuit (head IC) for switching the magnetic head 28 and amplifying a read signal, etc., near the end of the FPC 60 on the actuator 23 side,
An integrated circuit for positioning the magnetic head 28 (servo I
C) are mounted, and these integrated circuits and the magnetic head 28 are electrically connected via a lead wire or a relay FPC.

The other end of the FPC 60 is locked to a support member 70 on the base plate 30 so that the entire FPC 60 keeps a state of being curved in an arc shape. Therefore, FP
The intermediate portion of C60 bends according to the swing of the actuator 23, and the degree of curvature changes according to the position of the arm 25.

The end of the FPC 60 locked to the support member 70 on the apparatus main body side is electrically connected to the connector 50 fixed to the base plate 30. Here, the connector 50 is connected to the disk enclosure (base plate 3).
0 is a part for exchanging signals between the inside and the outside, that is, exchanging signals between the above-described integrated circuit and the circuit section of the apparatus main body.

The lines of the FPC 60 include a line for supplying power to each integrated circuit, a line for supplying a chip select signal indicating which one of the plurality of integrated circuits is to be selected, and a line for supplying a plurality of magnetic heads 28 which each integrated circuit handles. Supply line for a head select signal indicating which one to select, magnetic head 28
And a signal line for switching between read / write modes.

Next, the operation of the above embodiment will be described. When the disk 21 is driven by the spindle motor 22 and is rotating at high speed, the slider receives an airflow associated with the rotation, so that the magnetic head 28 floats a minute amount above the disk surface. When the actuator driving unit 31 drives the actuator 23 in this state, the actuator 23 swings. As a result, the magnetic head 28 can be moved to a target track on the disk 21 and data can be read from or written to the disk 21.

The middle portion of the FPC 60 also bends in accordance with the swing of the actuator 23 when reading / writing data, and the degree of curvature changes according to the position of the arm 25.
A signal for selecting which disk 21 to read / write data from is sent from a circuit unit of the apparatus main body to the FPC 60.
Is sent to the above-described integrated circuit, and the integrated circuit that receives the signal drives the desired magnetic head 28 and
Data read / write to 1 is performed. Magnetic head 28
Is amplified by the above-described integrated circuit, and
It is sent to the circuit section of the apparatus main body through 60.

If the FPC 60 is made of one material, the neutral plane passes through the center of the FPC 60 in the thickness direction. However, as in the present embodiment, the FPC 60 is made of the base film 61, the first adhesive, and the like. 62, conductor pattern 63, second adhesive 64, cover film 65, sheet-like support 67
a, the neutral surface N is accurately formed by stacking films having different longitudinal elastic coefficients such as the viscoelastic material 67b.
It does not pass through the center position in the thickness direction of C60.

However, the conductor pattern 63 having a large longitudinal elastic modulus is centered, and the cover film 65 is provided on one side thereof.
(Thickness H1) and the base film 61 on the other side.
Since the damping sheet 67 (total thickness H2 = H1) is arranged, the neutral plane N does not largely deviate from the center position in the thickness direction of the FPC 60, that is, the center position in the thickness direction of the conductor pattern 63, and is substantially It exists inside the conductor pattern 63.

For this reason, one end of the FPC 60 is attached to the actuator 23, which is a movable part, and even if the FPC 60 is set in a curved state as shown in FIG. The repetitive stress acting on the bent portion 63 is small, and the occurrence of fatigue fracture can be suppressed or prevented. Therefore, the flex life of the FPC 60 is prolonged. Specifically, compared to the conventional configuration, the present invention can reduce the repetitive stress acting on the bent portion of the conductor pattern 63 if the bending state is the same, and can reduce the fatigue in the conventional configuration. Even so, with the configuration of the present invention, fatigue failure can be avoided or the number of flexures until fatigue failure can be greatly increased.

Since the disconnection of the FPC 60 is less likely to occur, the reliability of the disk device is improved. Moreover,
Since the damping sheet 67 fully demonstrates its function,
Since the vibration of the actuator 23 is suppressed by the function of the vibration damping sheet 67 as in the conventional disk device, the movement of the magnetic head 28 by the actuator 23 can be performed with high accuracy.

The viscoelastic material 67b in the vibration damping sheet 67
Is usually much smaller than the longitudinal elastic coefficient of the sheet-like support 67a in the vibration damping sheet 67. In this case, the thickness of the vibration-damping sheet 67 is
The thickness of a is used. By doing so, the neutral plane N can be brought closer to the center position in the thickness direction of the FPC 60, that is, the center position in the thickness direction of the conductor pattern 63.

In order to more accurately match the neutral plane N with the center position of the FPC 60 in the thickness direction, the following formula for calculating the position of the neutral axis in the combination beam is used to obtain the base film 61, the first film Adhesive 62, conductor pattern 63, second
Adhesive 64, cover film 65, sheet-like support 6
These thicknesses may be determined based on the longitudinal elastic coefficients of the viscoelastic material 7a and the viscoelastic material 67b.

[0057]

(Equation 1)

[0058] Here, Y; beam of the upper end distance E _m from (the cover surface of the film) to the neutral axis; longitudinal elastic coefficient of the m th member when the beam is of n members (layers) y _z ; distance a _m from the upper end of the beam to an arbitrary position; sectional area of the m-th member (cross-sectional area) in addition, with regard to the structure and arrangement of the FPC 60, there are various kinds of, the present invention is limited to the above embodiments It is not something to be done. For example, even if the bending direction of the FPC 60 is reversed as shown in FIG.
The repeated load applied to the bent portion 3 is small, and the occurrence of fatigue fracture can be suppressed or prevented. Therefore, FPC60
Has a longer flexing life and higher reliability as a disk device.

(Second Embodiment) FIG. 8 is a view showing an embodiment relating to an FPC with a vibration damping sheet according to the first and third aspects of the invention and an FPC in a disk device according to the fifth aspect of the invention. In the figure, portions corresponding to those in FIG. 5 are denoted by the same reference numerals, and description thereof is omitted.

The FPC 60 in this embodiment is also an FPC
It is composed of a main body 66 and a vibration damping sheet 67 adhered to the FPC main body 66. Here, the FPC body 66
As in the first embodiment, a base film 61, a conductor pattern 63 adhered to one surface of the base film 61 with a first adhesive 62, and a second adhesive 64 on the surface of the conductor pattern 63. Bonded cover film 65
It is composed of

The damping sheet 67 is also made of the sheet-like support 6.
What laminated | stacked the viscoelastic material 67b on 7a is used. However, the viscoelastic material 67b is adhered to the surface of the cover film 65.

In the FPC 60, the thickness H3 of the base film 61 is selected to be equal to the thickness H4 of the thickness of the cover film 65 and the thickness of the vibration damping sheet 67.

Therefore, also in this configuration, the neutral plane N exists substantially inside the conductor pattern 63. Therefore, FP
One end of the C60 is attached to the actuator 23 which is a movable part, and even under the use environment where the FPC 60 is curved and its degree of curvature fluctuates, the repetitive load received by the bent portion of the conductor pattern 63 is small, and fatigue fracture occurs. Can be suppressed or prevented. Therefore, the flex life of the FPC 60 is extended, and the reliability as a disk device is also increased. Of course, in this configuration, the vibration damping sheet 67 fully demonstrates its function.

As in the case of the first embodiment, the vibration damping sheet 6
Since the longitudinal elastic modulus of the viscoelastic material 67b inside the damping sheet 7 is usually much smaller than the longitudinal elastic coefficient of the sheet-like support 67a inside the damping sheet 67, the vibration damping sheet 6
As the thickness of 7, the thickness of the sheet-like support 67a may be used.

It should be noted that the FPC 60 shown in FIG.
When used in the magnetic disk device described in (1), the same effect as the magnetic disk device in the first embodiment can be obtained. (Other Embodiments) Although the first and second embodiments relate to a magnetic disk drive using a plurality of disks, the present invention is not limited to this, and a magnetic disk drive using a single disk Also, the present invention is applicable to disk devices other than magnetic disk devices.

For example, in an optical disk device, an optical head for reading / writing data is supported by an arm of an actuator, and an actuator is driven so that the optical head moves in a direction crossing a track of the disk. I do. In this optical disk device, the photodetector in the optical head and the circuit section on the device main body side are electrically connected via the FPC, so that the present invention can be applied to this.

[0067]

As described above, according to the first aspect of the present invention, the base film, the conductor pattern adhered to one surface of the base film by the first adhesive, and the conductor pattern adhered to the surface of the conductor pattern. In an FPC having a cover film adhered by the adhesive of No. 2 and a vibration damping sheet adhered to at least one of the other surface of the base film or the surface of the cover film, the thickness of the cover film and the base film The relationship between the thickness and the thickness of the damping sheet is selected so that the neutral plane is located inside the conductor pattern.

According to this configuration, since the neutral plane exists inside the conductor pattern, for example, the FP with the vibration damping sheet
Even in an environment in which one end of C is attached to the movable portion and the degree of bending varies, the repetitive stress acting on the bent portion of the conductor pattern is small, and the occurrence of fatigue fracture can be suppressed or prevented. Therefore, the flex life becomes longer.

According to the second aspect of the present invention, the base film, the conductor pattern adhered to one surface of the base film by the first adhesive, and the conductor film adhered to the surface of the conductor pattern by the second adhesive. In an FPC having a cover film and a vibration damping sheet adhered to the other surface of the base film 11, the thickness of the cover film is equal to the sum of the thickness of the base film and the thickness of the vibration damping sheet. Has become.

According to this configuration, since the neutral surface exists substantially inside the conductor pattern, for example, the FP with the vibration damping sheet
Even in an environment in which one end of C is attached to the movable portion and the degree of bending varies, the repetitive stress acting on the bent portion of the conductor pattern is small, and the occurrence of fatigue fracture can be suppressed or prevented. Therefore, the flex life becomes longer.

According to the third aspect of the present invention, the base film, the conductor pattern adhered to one surface of the base film by the first adhesive, and the conductor film adhered to the surface of the conductor pattern by the second adhesive. F having a cover film and a vibration damping sheet adhered to the surface of the cover film
In the PC, the thickness of the base film is equal to the thickness of the cover film plus the thickness of the damping sheet.

Also in this configuration, since the neutral surface exists substantially inside the conductor pattern, for example, F
Even in an environment where one end of the PC is attached to the movable part and the degree of bending varies, the repetitive stress acting on the bent part of the conductor pattern is small, and the occurrence of fatigue fracture can be suppressed or prevented. Therefore, the flex life becomes longer.

In the disk device according to the fourth or fifth aspect,
3. An FPC, one end of which is supported on the actuator side and the other end of which is supported on the apparatus main body side, and which bends in response to the swing of the actuator, for electrically connecting the circuit unit and the head on the apparatus main body side. Or, the FPC described in 3 is used.

In these disk devices, even in a use environment in which the degree of bending varies, excessive repetitive stress does not act on the conductor pattern.
Disconnection hardly occurs, and the reliability as a disk device is high. In addition, since the vibration of the actuator is suppressed by the function of the vibration damping sheet as in the conventional disk device, the head can be moved by the actuator with high accuracy.

[Brief description of the drawings]

FIG. 1 is a principle view of an FPC with a vibration damping sheet according to the first and second aspects of the invention.

FIG. 2 is a principle view of an FPC with a vibration damping sheet according to the first and third aspects of the invention.

FIG. 3 is a perspective view showing an embodiment of a magnetic disk drive provided with an FPC with a vibration damping sheet.

FIG. 4 is a partially cutaway perspective view showing the configuration of the actuator in FIG. 3 and its periphery.

5 is a cross-sectional view illustrating a configuration of an FPC with a vibration damping sheet in FIG.

FIG. 6 is a cross-sectional view showing a setting state of the FPC with a vibration damping sheet in FIG. 3;

FIG. 7 is a cross-sectional view showing another set state of the FPC with a vibration damping sheet in FIG. 3;

FIG. 8 is an explanatory diagram of a second embodiment relating to an FPC with a vibration damping sheet and a magnetic disk device having the same.

FIG. 9 is a cross-sectional view illustrating an example of an FPC with a vibration damping sheet used in a conventional magnetic disk drive.

FIG. 10 is a cross-sectional view showing a state in which the FPC shown in FIG. 9 is bent so that the cover film side becomes convex.

FIG. 11 is a cross-sectional view showing a state in which the FPC shown in FIG. 9 is bent so that the cover film side is concave.

[Explanation of symbols]

 N: neutral surface 1, 11, 61: base film 2, 12, 62: first adhesive 3, 13, 63: conductor pattern 4, 14, 64: second adhesive 5, 15, 65: cover Film 6, 16, 66: FPC body 7, 17, 67: Damping sheet 7a, 67a: Sheet-like support 7b, 67b: Viscoelastic material 21: Disk 22: Spindle motor 23: Actuator 25: Arm 27: Suspension 28 : Magnetic head 30: base plate 31: actuator drive unit 32: coil 33: magnetic circuit 50: connector 60: FPC 70: support member

Claims (5)

[Claims] 1. A base film, a conductor pattern adhered to one surface of the base film by a first adhesive, a cover film adhered to a surface of the conductor pattern by a second adhesive, A damping sheet adhered to at least one of the other surface of the base film or the surface of the cover film, and a relationship between a thickness of the cover film, a thickness of the base film, and a thickness of the damping sheet. Wherein the neutral plane is selected so as to be located inside the conductor pattern. 2. A base film, a conductor pattern adhered to one surface of the base film by a first adhesive, a cover film adhered to a surface of the conductor pattern by a second adhesive, A damping sheet adhered to the other surface of the base film, wherein the thickness of the cover film is equal to the sum of the thickness of the base film and the thickness of the damping sheet. Flexible printed circuit with vibration damping sheet. 3. A base film, a conductor pattern adhered to one surface of the base film by a first adhesive, a cover film adhered to a surface of the conductor pattern by a second adhesive, A damping sheet adhered to the surface of the cover film, wherein the thickness of the base film is equal to the sum of the thickness of the cover film and the thickness of the damping sheet. Flexible printed circuit with vibration sheet. 4. A disk, a disk drive for rotating and driving the disk, a head for reading / writing data from / to a recording surface of the disk, an actuator having an arm for supporting the head, An actuator drive unit that drives the actuator so that the head moves in a direction traversing the track of the disk, and one end of the actuator drive unit for electrically connecting a circuit unit on a device main body side and the head. And a flexible printed circuit, the other end of which is supported by the device body and bent in accordance with the swing of the actuator, wherein the flexible printed circuit includes a base film, and one of the base films. A conductor pattern adhered to a surface by a first adhesive, and the conductor pattern A cover film adhered to the surface of the base film with a second adhesive, and a vibration damping sheet adhered to the other surface of the base film, wherein the thickness of the cover film is equal to the thickness of the base film. A disk device using a flexible printed circuit with a vibration damping sheet equal in thickness to the thickness of the vibration damping sheet. 5. A disk, a disk drive for rotating the disk, a head for reading / writing data from / to a recording surface of the disk, an actuator having an arm for supporting the head, An actuator drive unit that drives the actuator so that the head moves in a direction traversing the track of the disk, and one end of the actuator drive unit for electrically connecting a circuit unit on a device main body side and the head. The other end is supported by the apparatus main body side and the flexible printed circuit which is bent in accordance with the swing of the actuator, the flexible printed circuit, a base film, one of the base film A conductor pattern adhered to a surface by a first adhesive, and the conductor pattern A cover film adhered to the surface of the cover film by a second adhesive; and a vibration damping sheet adhered to the surface of the cover film, wherein the thickness of the base film is equal to the thickness of the cover film and the vibration damping. A disk device using a flexible printed circuit with a vibration damping sheet equal in thickness to the thickness of the sheet.