Hard disk drive and method for manufacturing a base plate which includes a component receiving part

There is provided a base plate including: a base body; and a component receiving part penetrating through the base body so as to receive a circuit component mounted on a substrate therein at the time of coupling the substrate and the base body, wherein the component receiving part includes a step part formed in an outer edge thereof so that a sealing member is seated on the step part to seal the component receiving part.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of Korean Patent Application No. 10-2012-0106662 filed on Sep. 25, 2012, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a base plate for a hard disk drive and a hard disk drive including the same, and more particularly, to a base plate for a hard disk drive including a component receiving part capable of receiving circuit components mounted on a substrate therein, a method for manufacturing the same, and a hard disk drive including the same.

2. Description of the Related Art

A hard disk drive (HDD), a computer information storage device, reads data stored on a disk or writes data to a disk using a magnetic head.

In a hard disk drive, a base plate is installed with a head driver, that is, a head stack assembly (HSA), capable of moving the magnetic head across the face of the disk. The magnetic head performs its function while moving to a desired position in a state in which it is suspended above a writing surface of the disk by the head driver at a predetermined height.

According to the related art, in manufacturing a base plate provided in the hard disk drive, a post-processing scheme of die-casting aluminum (Al) and then removing burrs, or the like, generated due to the die-casting, has been used.

However, in the die-casting scheme according to the related art, since a process of injecting molten aluminum (Al) for die-casting to form a base plate is performed, high levels of temperature and pressure are required, such that a high amount of energy is required in the process and a process time is increased.

Further, in terms of a lifespan of a die-casting mold, there is a limitation in manufacturing a large number of base plates using a single mold, and a base plate manufactured by the die-casting process may have poor dimensional precision.

Therefore, the base plate has been manufactured by a pressing or forging process in order to solve problems inherent in the die-casting process. Accordingly, research into a technology of securing a space in which circuit components mounted on a substrate may be received and preventing a problem in rigidity, despite using a steel-based sheet provided to be as thin as possible at the time of a pressing or forging process, in accordance with the requirements for miniaturization and thinness of a hard disk drive, has been urgently demanded.

In the following Patent Document 1, a problem in that it is difficult to decrease the overall height of a hard disk drive due to circuit components mounted on a printed circuit board is present.

RELATED ART DOCUMENT

SUMMARY OF THE INVENTION

An aspect of the present invention provides a base plate for a hard disk drive capable of being manufactured by plastically deforming a steel sheet and satisfying requirements for miniaturization and thinness by including a component receiving part capable of receiving circuit components mounted on a substrate therein, a method for manufacturing the same, and a hard disk drive including the same.

Another aspect of the present invention provides a base plate capable of maintaining rigidity despite including a space capable of receiving circuit components mounted on a substrate therein, and a hard disk drive including the same.

Another aspect of the present invention provides a hard disk drive capable of preventing external foreign objects from being introduced into an inner portion thereof.

Another aspect of the present invention provides a base plate capable of significantly decreasing a process time and energy consumption by being manufactured in a pressing or forging process, a method for manufacturing the same, and a hard disk drive including the same.

According to an aspect of the present invention, there is provided a base plate including: a base body; and a component receiving part penetrating through the base body so as to receive a circuit component mounted on a substrate therein at the time of coupling the substrate and the base body, wherein the component receiving part includes a step part formed in an outer edge thereof so that a sealing member is seated on the step part to seal the component receiving part.

The base body may be formed by plastically deforming a steel plate.

A thickness of the step part may be less than that of the base body.

The base plate may satisfy the following Equation 7:
0<S′2<0.5625  Equation 7,

where S′2indicates a ratio of an area of the component receiving part to an area of the step part.

A diameter of the component receiving part may be larger than 0% of a diameter of the step part and may be equal to or smaller than 50% of the diameter of the step part.

According to another aspect of the present invention, there is provided a method for manufacturing a base plate, the method including: forming a preparation hole in a base body by penetrating through the base body in a predetermined position thereof; fixing the base body to a jig; pressing an outer edge of the preparation hole of the base body to form a step part in the base body; and forming a component receiving part in the base body by pressing the base body so as to decrease a diameter of the preparation hole.

The base plate may satisfy the following Equation 7:
0<S′2<0.5625  Equation 7,

where S′2indicates a ratio of an area of the component receiving part to an area of the step part.

The base plate may satisfy the following Equation 9:
0.16<S2<0.81  Equation 9,

where S2indicates a ratio of an area of the preparation hole to an area of the step part.

The base plate may satisfy the following Equation 5:

where w indicates a ratio of a diameter of the preparation hole to a diameter of the step part, w′ indicates a ratio of a diameter of the component receiving part to the diameter of the step part, t indicates a thickness of the base body, and t′ indicates a thickness of the step part.

The base plate may satisfy the following Equation 6:
0<w′<0.75  Equation 6,

where w′ indicates a ratio of the diameter of the component receiving part to the diameter of the step part.

The base plate may satisfy the following Equation 8:
0.4<w<0.9  Equation 8,

where w indicates a ratio of the diameter of the preparation hole to the diameter of the step part.

According to another aspect of the present invention, there is provided a hard disk drive including: the base plate as described above; a spindle motor coupled to the base plate to rotate a disk; a magnetic head writing data to and reading data from the disk; and a head driver moving the magnetic head to a predetermined position on the disk.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the drawings, the shapes and dimensions of components may be exaggerated for clarity, and the same reference numerals will be used throughout to designate the same or like components.

FIG. 1is a schematic exploded perspective view showing a hard disk drive according to an embodiment of the present invention.

Referring toFIG. 1, the hard disk drive according to the embodiment of the present invention may include a base plate100for a hard disk drive (hereinafter, referred to as the base plate), a spindle motor200, a head driver300, and a substrate400.

The base plate100may be a housing forming an appearance together with a cover plate500in the hard disk drive according to the embodiment of the present invention and include a base body110and a head seating part120.

Here, the base plate100and the cover plate500may be coupled to each other by coupling a plurality of screws510to holes112formed in the base plate100.

Here, the base body110may be formed by plastically deforming a steel plate. More specifically, after a basic shape of the base body110is manufactured by press processing, a final shape thereof may be manufactured by additional processing such as bending or cutting.

That is, the base body110according to the embodiment of the present invention may be manufactured by performing a single process by plastic working such as press processing, or the like, or an additional process on a cold rolled steel sheet (SPCC, SPCE, or the like), a hot rolled steel sheet, a stainless steel, or a lightweight alloy steel sheet such as a boron or a magnesium alloy sheet, unlike the post-processing scheme according to the related art in which aluminum (Al) is die-cast and burrs and the like, generated due to the die-casting are then removed.

Therefore, since the base body110according to the embodiment of the present invention may be manufactured by the press processing, a process time and energy consumption are significantly decreased, whereby production capability may be improved.

Here, the base body110may be provided with at least one component receiving part130penetrating through upper and lower surfaces thereof.

The component receiving part130may provide a space in which circuit components410mounted on the substrate400may be received.

The component receiving part130may be described in detail with reference toFIGS. 2 through 6.

The base body110, a part on which a disk D coupled to the spindle motor200to be described below is disposed, may have the disk D positioned thereon, the disk D having data stored thereon.

The base body110may be formed in a generally circular shape so as to correspond to a shape of the disk D, and a portion of the base body110may be stepped to configure the head seating part120on which the head driver300to be described below is disposed.

Here, the head seating part120is positioned in a position lower than that of the base body110to provide a space in which the head driver300is repeatedly rotated so as to read data from and write data to the disk D.

That is, the reason why the head seating part120is positioned in the position lower than that of the base body110is to secure a space in which the head driver300provides driving force to a magnetic head (not shown) to insert the magnetic head (not shown) into the disk D, thereby reading data from and writing data to the disk D.

The spindle motor200, provided to rotate the disk D, may be fixedly mounted in the center of the base body110. The disk D, coupled to the spindle motor200to rotate together therewith, may have a writing surface on which data is written.

Here, the spindle motor200may includes a clamp210coupled to an upper end portion thereof by a screw215in order to firmly fix the disk D thereto.

In addition, althoughFIGS. 1 and 2show a configuration in which a single disk D is mounted on the spindle motor200, this configuration is only an example. That is, one or more disks D may be mounted on the spindle motor200. In the case in which a plurality of disks D are mounted as described above, a ring shaped spacer for maintaining an interval between the disks D may be disposed between the disks D.

The head driver300may be called a head stack assembly (HAS) and be a component having a magnetic head (not shown) mounted thereon and moving the magnetic head to a predetermined position to write data to the disk D or read data written on the disk D.

The head driver300may include a voice coil motor (VCM), a swing arm320, and a suspension330, wherein the suspension330may be fixedly coupled to a front end portion of the swing arm320.

In addition, the head driver300may be coupled to the base plate100so as to be rotatable around a pivot shaft160of the head seating part120of the base plate100. When the disk D rotates on the base body110of the base plate100at a high speed, the magnetic head (not shown) may serve to read the data written on the writing surface of the disk D or write the data to the writing surface of the disk D.

Here, the VCM, providing rotational driving force to the head driver300, may include magnets340and350disposed on upper and lower portions of a VCM coil310of the head driver300.

The VCM may be controlled by a servo control system and rotate the head driver300around the pivot shaft160in a direction according to Fleming's left hand rule by interaction between current input by the VCM coil310and a magnetic field formed by the magnets340and350.

Here, the magnets340and350disposed on the upper and lower portions of the coil310provided in the VCM may be coupled to upper and lower yokes360and370, respectively, in order to increase magnetic flux density and be fixed to the base body110.

Here, when an operation start command is input to the hard disk drive according to the embodiment of the present invention, the disk D starts to rotate, and the VCM rotates the swing arm320in a counterclockwise direction to move the magnetic head (not shown) onto the writing surface of the disk D.

On the other hand, when an operation stop command is input to the hard disk drive according to the embodiment of the present invention, the VCM rotates the swing arm320in a clockwise direction to allow the magnetic head (not shown) to deviate from the disk D.

The magnetic head (not shown) deviating from the writing surface of the disk D is parked in a ramp380provided outside the disk D.

FIG. 2is a cross-sectional view of a half of the hard disk drive according to the embodiment of the present invention;FIG. 3is a schematic cross-sectional view showing a process of forming a component receiving part in a base body according to the embodiment of the present invention;FIG. 4is a perspective view showing a form in which a base body is fixed to a jig in order to form a step part in the base body according to the embodiment of the present invention;FIG. 5is a perspective view showing a form in which the step part is formed in the base body using a punch according to the embodiment of the present invention;FIG. 6Ais a schematic plan view showing a form in which a preparation hole is formed in the base body according to the embodiment of the present invention; andFIG. 6Bis a schematic plan view showing a form in which the component receiving part and the step part are formed in the base body according to the embodiment of the present invention.

Referring toFIGS. 2 through 6B, the base body110according to the embodiment of the present invention may be provided with the component receiving part130and a step part140.

The base body110may have the substrate400mounted on a lower portion thereof in order to supply power to a coil of the spindle motor200, wherein the substrate400may be a flexible printed circuit board.

The substrate400may be mounted with the plurality of circuit components410, and the base body110may be provided with the component receiving part130capable of receiving the circuit components410mounted on the substrate400.

Therefore, the component receiving part may be larger than that of the circuit component410.

The component receiving part130may be provided to penetrate through the upper and lower surfaces of the base body110and be formed as a hole.

Here, the component receiving part130may be rectangular, square, circular, or oval, and may also have various shapes according to a shape of the circuit component410mounted on the substrate400.

The component receiving part130may be formed in a predetermined position of the base body100so as to correspond to a position of the circuit component410mounted on the substrate400when the substrate400is mounted under the base body110, and the circuit component410may be received in the component receiving part130.

In addition, the circuit component410may be received in the component receiving part130so as not to protrude upwardly from the base body100.

This is intended to form a space in which a sealing member150to be described below may be seated.

The step part140may be formed outwardly of the component receiving part130in an upper surface of the base body110.

The step part140may be stepped from the upper surface of the base body110downwardly in an axial direction. The sealing member150may be seated on the step part140to seal the component receiving part130.

Since the component receiving part130needs to be sealed in order to prevent foreign objects, or the like, from being introduced into the hard disk drive according to the embodiment of the present invention and maintain rigidity of the base body110, the component receiving part130may be sealed by the sealing member150.

That is, the sealing member150may be seated on the step part140formed in the base body110and seal the component receiving part130.

Here, as the sealing member150, a member such as a tape, or the like, may be used.

Hereinafter, a method for manufacturing the base body110according to the embodiment of the present invention will be described with reference toFIG. 3.

The configuration of the base body110described above may also become clear from the following description of the method for manufacturing the base body110.

First, the base body110according to the embodiment of the present invention is manufactured by performing plastic working such as press processing, or the like, on a cold rolled steel sheet (SPCC, SPCE, or the like), a hot rolled steel sheet, stainless steel, or a lightweight alloy steel sheet such as a boron or a magnesium alloy sheet.

After a basic shape of the base body110is manufactured by press processing, a preparation hole132is formed in a position corresponding to that of the circuit component410mounted on the substrate400.

Here, the preparation hole132refers to an initial hole provided in the base body110, and the component receiving part130refers to a component formed by pressing a predetermined position of the base body110to decrease a size of the preparation hole132.

A jig600is fixed to the base body110including the preparation hole132and the base body110corresponding to an outer edge of the preparation hole132is pressed using a punch700, or the like, to form the step part140in the base body110.

In the case in which the base body110is pressed, since a thickness of the base body110is changed, a size of the preparation hole132may be decreased. Here, the preparation hole132decreased to a desired size may become the component receiving part130.

This will be described below in detail with reference toFIGS. 6A and 6B.

The sealing member150may be seated on the step part140, prevent external foreign objects from being introduced, and maintain the rigidity of the base body110.

Referring toFIG. 6A, the preparation hole132penetrating through the upper and lower surfaces of the base body110according to the embodiment of the present invention may have a rectangular shape, and it may be assumed that a length and a width of the preparation hole132are x and y, respectively.

Here, in order for the base body110to include the step part140, the outer edge of the preparation hole132may be pressed, and it may be assumed that a length and a width of the step part140are a and b, respectively.

In addition, it may be assumed that a thickness of the base body110is t.

When the outer edge of the preparation hole132of the base body110according to the embodiment of the present invention is pressed, the base body110is deformed to thereby decrease the size of the preparation hole132, the component receiving part130may be formed accordingly.

More specifically, in the case of pressing the base body110to form the step part140, since the base body110is deformed by a thickness decreased at a portion thereof at which the step part140is formed, the size of the preparation hole132may be decreased as compared with an initial size thereof.

That is, since the component receiving part130capable of receiving the circuit component410therein is formed by decreasing the size of the preparation hole132, it is preferable that the component receiving part130is formed to have a size corresponding to that of the circuit component410mounted on the substrate400, and the preparation hole132needs to be formed to have a sufficiently large size.

Since the component receiving part130is formed by decreasing the size of the preparation hole132, it is consequentially important to determine at what size the preparation hole132is initially formed to be.

Referring toFIG. 6B, it may be assumed that a length and a width of the component receiving part130formed by decreasing the size of the preparation hole132are x′ and y′, respectively, and a thickness of the step part140is t′.

Here, before or after the step part140is formed by pressing the base body110, the overall volume of the base body110is not changed, which may be represented by the following Equation 1.
(a×b−x×y)×t=(a×b−x′×y′)×t′[Equation 1]

In addition, when Equation 1 is arranged, it may be represented by the following Equation 2.

Here, when the length x and the width y of the preparation hole132are constantly changed by applying constant force to the base body110, it may be represented by the following Equation 3 and Equation 4.

The above Equation 2 indicates a ratio of the length x of the preparation hole132to the length a of the step part140and a ratio of the width y of the preparation hole132to the width b of the step part140.

The above Equation 4 indicates a ratio of the length x′ of the component receiving part130to the length a of the step part140and a ratio of the width y′ of the component receiving part130to the width b of the step part140.

When the above Equation 3 and Equation 4 are substituted for the above Equation 2, it may be represented by the following Equation 5.

Although the above Equation 5 indicates the ratio of lengths or the ratio of widths in the case in which the preparation hole132and the component receiving part140have a rectangular shape, it may also be applied to a ratio of diagonal lengths and to the case in which the preparation hole132and the component receiving part130have a circular shape.

That is, w may be a ratio of a diameter of the preparation hole132to a diameter of the step part140, and w′ may be a ratio of a diameter of the component receiving part130to the diameter of the step part140.

The following Table 1 shows variously changed diameters of the preparation hole132, variously changed diameters of the component receiving part130, and variously changed thicknesses of the step part140in the case in which the step part140has a diameter of 20 mm and the base body110has a thickness t of 0.8 mm when the preparation hole132and the component receiving part130have a circular shape.

The following Table 2 shows a pressing load required for forming the step part140in the base body110according to thicknesses t′ of the step part140and diameters of the component receiving part130.

FIG. 7is a graph showing a pressing load required in the case of allowing a diameter of the component receiving part to be constant and allowing a thickness of the step part to be changed.

Referring toFIG. 7, it could be appreciated that there is no large difference in a magnitude of a pressing load required even in the case that the thickness t′ of the step part140is variously changed with respect to each of the diameters of the component receiving part130when the diameters of the component receiving part130are 5 mm, 10 mm, and 15 mm, respectively.

Therefore, it could be appreciated that the magnitude of the pressing load is not significantly affected by the thickness t′ of the step part140.

FIG. 8is a graph showing a pressing load required in the case of allowing a thickness of the step part to be constant and allowing a diameter of the component receiving part to be changed.

Referring toFIG. 8, it could be appreciated that there is a large difference in a magnitude of a pressing load required even in the case that the diameter of the component receiving part130is changed with respect to each of the thicknesses t′ of the step part140when the thicknesses t′ of the step part140are 0.4 mm, 0.5 mm, and 0.6 mm, respectively.

That is, the smaller the diameter of the component receiving part130is, the larger the required pressing load is, while the larger the diameter of the component receiving part130is, the smaller the required pressing load is.

Since the magnitude of the pressing load applied to the base body110is not significantly affected by the thickness t′ of the step part140, a relationship between the magnitude of the pressing load applied to the base body110and the diameter of the component receiving part130may be a quadratic polynomial relationship as shown inFIG. 9.

Therefore, an appropriate pressing load is applied to the base body110, whereby the diameter of the component receiving part130may be formed to have a desired size.

In the case in which the hole is formed in the base body110, rigidity may be deteriorated.

That is, in the case in which a load is applied to one end of the base body100including the hole formed therein, a sag amount of the base body110including the hole may be increased as compared with a base body that does not include a hole.

In addition, the sag amount of the base body may be affected by a size of the hole formed in the base body110.

Since the component receiving part130according to the embodiment of the present invention is formed as the hole, when the component receiving part130is formed in the base body110, the rigidity of the base body110may be deteriorated.

FIG. 10is a graph showing a sag amount of the base body in the case in which a predetermined load is applied to the base body with respect to the diameter of the component receiving part.

Referring toFIG. 10, it could be appreciated that the sag amount of the base body110for a bending load is changed according to the diameter of the component receiving part130.

More specifically, a relationship between the diameter of the component receiving part130and the sag amount of the base body110may be a quadratic polynomial relationship, and the larger the diameter of the component receiving part130is, the larger the sag amount of the base body110is.

Therefore, it could be appreciated that the larger the diameter of the component receiving part130is, the lower the rigidity of the base body110is.

Therefore, it is required that the diameter of the component receiving part130may be appropriately determined so that there is no problem in the rigidity of the base body110even in the case that the component receiving part130is formed in the base body110.

As shown inFIG. 11, the pressing load required for forming the diameter of the component receiving part130to have a desired size and the sag amount of the base body110with respect to the diameter of the component receiving part130tend to be opposite to each other.

Referring toFIG. 11, a range capable of significantly decreasing the pressing load required for forming the step part140in the base body110while securing the rigidity of the base body110including the component receiving part130may be found out.

Therefore, a range of a ratio of the diameter of the component receiving part130to the diameter of the step part140may satisfy the following Equation 6.
0<w′<0.75  [Equation 6],

The above Equation 6 means that the diameter of the component receiving part130may be in a range of 0 to 75% of the diameter of the step part140.

Particularly, when the diameter of the component receiving part130is larger than 0% of the diameter of the step part140and is equal to or smaller than 50% of the diameter of the step part140, an effect of maintaining the rigidity of the base body110may be excellent and the pressing load required for forming the step part140may also be decreased.

That is, the diameter of the component receiving part130may be in a range of 0 to 50% of the diameter of the step part140.

Here, when the above Equation 6 is represented by a ratio (S′) of an area of the component receiving part130to an area of the step part140, it may be represented by the following Equation 7.

Referring toFIG. 6A, the area of the step part140may be represented by a×b, and referring toFIG. 6B, the area of the component receiving part130may be represented by x′×y′.

That is, the ratio (S′) of the area of the component receiving part130to the area of the step part140may be represented by

The above Equation 7 may be applied to the case in which the component receiving part130and the step part140have a rectangular shape, the case in which the component receiving part130and the step part140have a square shape, and the case in which the component receiving part130and the step part140have a circular shape.

Further, in order to satisfy the above Equation 6, a range of a ratio of the diameter of the preparation hole132to the diameter of the step part140may satisfy the following Equation 8.
0.4<w<0.9  [Equation 8],

The above Equation 8 means that the diameter of the preparation hole132may be in a range of 40 to 90% of the diameter of the step part140.

Here, when the above Equation 8 is represented by a ratio (S) of an area of the preparation hole132to an area of the step part140, it may be represented by the following Equation 9.

Referring toFIG. 6A, the area of the step part140may be represented by a×b, and referring toFIG. 6A, the area of the preparation hole132may be represented by x×y.

That is, the ratio of the area of the preparation hole132to the area of the step part140may be represented by

The above Equation 9 may be applied to the case in which the component receiving part130and the step part140have a rectangular shape, the case in which the component receiving part130and the step part140have a square shape, the case in which the component receiving part130and the step part140have a polygonal shape, and the case in which the component receiving part130and the step part140have a circular shape.

According to the above-mentioned embodiments, the base plate100for a hard disk drive may be manufactured using the pressing or forging process, the introduction of the external foreign objects may be prevented, and the rigidity of the base body110may be maintained.

In addition, since the circuit component410mounted on the substrate400may be received in the component receiving part130formed in the base body110, the overall height of the hard disk drive is decreased, whereby the hard disk drive may be miniaturized and thinned.

In addition, the base plate100is manufactured by the forging or pressing process to significantly decrease the process time and the energy consumption, whereby production capability may be significantly increased.

As set forth above, in a base plate, a method for manufacturing the same, and a hard disk drive including the same according to embodiments of the present invention, a component receiving part capable of receiving circuit components mounted on a substrate therein is provided to decrease the overall height of the hard disk drive, whereby the requirements for miniaturization and thinness may be satisfied.

In addition, even in the case that the base plate includes a space in which the circuit components mounted on the substrate are received, the rigidity of the base plate may be maintained.

Further, the introduction of foreign objects into the hard disk drive may be prevented.

Furthermore, the base plate is manufactured by a pressing or forging process to significantly decrease a process time and energy consumption, whereby production capability may be improved.