JP2003101270A - Cooling structure for electronic component, magnetic disk device provided therewith and manufacturing method for cooling structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling structure for an electronic component capable of effectively suppressing temperature rise of the electronic component, a magnetic disk device provided with it and a manufacturing method for the cooling structure. SOLUTION: A printed circuit board 34 is provided in face to face with a base 12a where a magnetic disk is arranged and the electronic component 38 is mounted on the printed circuit board. The electronic component is provided with a package 37 and a plurality of terminals 39 extended from the package. A heat radiation sheet 40 is clamped between the base and the printed circuit board, and the heat radiation sheet is provided with a shape along the shape of the electronic component and is in contact with the package of the electronic component, the terminals and the base.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling structure for electronic parts, a magnetic disk device provided with the same, and a method for manufacturing the cooling structure.

[0002]

2. Description of the Related Art In recent years, in computers such as personal computers, laptop computers and book computers, magnetic disk devices have been widely used as recording devices for storing a large amount of information. Such a magnetic disk device, for example, a hard disk drive (hereinafter referred to as HDD) is usually provided with a case made of metal and functioning as a base. In this case, a magnetic disk as a recording medium, a spindle motor for rotationally driving the magnetic disk, a magnetic head for recording and reproducing on the magnetic disk, and a carriage for movably supporting the magnetic head with respect to the magnetic disk. The assembly and a voice coil motor for driving the carriage assembly to move and position the magnetic head on a desired track of the magnetic disk are housed.

A printed circuit board for controlling the operation of the HDD is attached to the outer surface of the bottom wall of the case with a predetermined gap. A plurality of electronic components are mounted on the printed circuit board and are located between the case and the case.

[0004]

Such an HDD has the following problems.
When used in a high temperature environment, the heat generated by the HDD itself is added, resulting in a considerably high temperature. In particular, the temperature of the specific IC etc. mounted on the printed circuit board becomes high, and depending on the environmental temperature,
There is a risk that the guaranteed temperature will be exceeded. For example, 70
When the HDD is continuously read / written in a high temperature environment of .degree. C., the case is 70.degree. C. +. Alpha., But the specific IC or the like may exceed 100.degree. In this case, the IC becomes close to its guaranteed limit temperature, which causes malfunction of the HDD.

As a method of suppressing the temperature rise of the electronic component as described above, a method has been proposed in which a heat dissipation sheet or the like is arranged in the gap between the printed circuit board and the case to allow the heat of the electronic component to escape to the case side. However, the heat dissipation sheet is C
In the case of electronic parts such as PU, it is provided in contact with the resin package part of the CPU. Therefore, the cooling efficiency is low, and it is difficult to obtain a sufficient temperature rise suppression effect with this type of heat dissipation sheet.

The present invention has been made in view of the above points, and an object thereof is to provide a cooling structure for an electronic component capable of effectively suppressing an increase in temperature of the electronic component, a magnetic disk device including the same, and a cooling structure. It is to provide a manufacturing method of.

[0007]

In order to achieve the above object, a cooling structure for an electronic component according to an aspect of the present invention has a base and an electronic component mounted thereon, and the above-mentioned base is provided with a predetermined gap. A printed circuit board provided to face the base; and a heat dissipation sheet sandwiched between the base and the printed circuit board. The electronic component includes a package portion and a plurality of electronic components extending from the package portion. Characterized in that the heat dissipation sheet has a shape according to the shape of the electronic component, and is provided in contact with the package portion of the electronic component, the terminal, and the base. There is.

In the magnetic disk device according to the aspect of the present invention, a base on which the magnetic disk is arranged and electronic components are mounted, and the magnetic disk device is provided to face the base with a predetermined gap. A printed circuit board, and a heat dissipation sheet sandwiched between the base and the printed circuit board, the electronic component has a package portion and a plurality of terminals extending from the package portion, The heat dissipation sheet has a shape that conforms to the shape of the electronic component, and is provided in contact with the package portion, the terminal, and the base of the electronic component.

Further, in the method of manufacturing a cooling structure for an electronic component according to the aspect of the present invention, the base and the electronic component are mounted, and the base is provided so as to face the base with a predetermined gap. The electronic component includes a printed circuit board and a heat dissipation sheet sandwiched between the base and the printed circuit board, and the electronic component has a package portion and a plurality of terminals extending from the package portion. In a method of manufacturing a cooling structure for electronic components, a heat dissipation sheet is placed on the printed circuit board at a predetermined position so as to overlap the electronic component, and the heat dissipation sheet placed on the printed circuit board is heated to a predetermined temperature. After softening, the heat dissipation sheet is compression-molded into a shape that conforms to the electronic parts, the printed circuit board with the heat dissipation sheet is attached to the base, and the heat dissipation is performed between the printed circuit board and the base. It is characterized by clamping the over bets.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the magnetic disk device of the present invention is applied to an HDD will be described in detail below with reference to the drawings. As shown in FIG.
Has a case 12 that functions as a base. The case 12 is formed in a rectangular box shape having an open upper end, and its upper opening is closed by screwing a top cover (not shown).

In the case 12, two magnetic disks 16a and 16b as magnetic recording media, a spindle motor 18 for supporting and rotating these magnetic disks, and a magnetic head for recording and reproducing information on and from the magnetic disks. A plurality of magnetic head assemblies 20, each of which includes a carriage assembly 22 that rotatably supports these magnetic head assemblies, a voice coil motor 24 that rotates and positions the carriage assembly, and a substrate unit 21 having a preamplifier and the like. It is stored.

The two magnetic disks 16a and 16bc are
It is fitted to the hub of the spindle motor 18 and stacked along the axial direction of the hub. And the magnetic disk 16
The a and 16b are fixed by a disk-shaped clamper 17 screwed to the upper end of the hub, and are rotationally driven by a spindle motor 18 at a predetermined speed.

The carriage assembly 22 includes a case 1
A bearing assembly 26 of substantially cylindrical shape fixed on the bottom wall of No. 2
And extended from the bearing assembly toward the magnetic disk 4
And a book arm 25. And each arm 2
The magnetic head assembly 20 is fixed to the extended end of the magnetic head assembly 5.
By rotating the carriage assembly 22 around the bearing assembly 26, each magnetic head can be moved to an arbitrary track of the corresponding magnetic disk.

The VCM 24 is fixed to the inner surface of the bottom wall of the case 12 and has a pair of yokes 28 opposed to each other with a predetermined gap.
And a permanent magnet (not shown) fixed to the inner surface of one of the yokes. Further, the VCM 24 has a voice coil (not shown) attached to the carriage assembly 22, and the voice coil is located between one yoke and the permanent magnet. Then, by energizing the voice coil, the carriage assembly 22 is rotated.

The board unit 21 has a board body installed on the inner surface of the bottom wall of the case 12, and a flexible wiring board 32 extending from the board body. A plurality of electronic components including the connector 30 are mounted on the board body.
The connector 30 penetrates the board main body and the bottom wall of the case 12, and is exposed on the outer surface of the bottom wall. In addition, the extended end of the flexible wiring board 32 is attached to the carriage assembly 22.
It is fixed to the bearing assembly 26 and is connected to the four magnetic head assemblies 20 via wires (not shown).

On the other hand, on the outer surface of the bottom wall 12a of the case 12, a spindle motor 18, a voice coil motor 24,
A printed circuit board 34 that controls the operation of the magnetic head assembly 20 is screwed and faces the outer surface of the bottom wall with a predetermined gap. Further, the case 12 and the printed circuit board 3
A heat dissipation sheet 40, which will be described later, is sandwiched between the heat dissipation sheet 40 and the heat sink 4.

The printed circuit board 34 is formed in a substantially rectangular shape, and a large number of electronic components 38 are mounted on the upper surface thereof. Further, on the printed circuit board 34, a connector 42 connectable to the connector 30 on the board unit 21 side and a main connector 44 for connecting the HDD to an electronic device such as a personal computer are mounted.

The printed circuit board 34 is arranged so as to face the outer surface of the bottom wall of the case 12 with the connector 42 connected to the connector 30 on the side of the case 12, and is fixed to the outer surface of the bottom wall by a plurality of screws 50. ing. The gap between the outer surface of the bottom wall of the case 12 and the electronic component 38 mounted on the printed circuit board 34 is set to about 0.3 mm on average. A circular through hole 36 for allowing a bracket (not shown) of the spindle motor 18 to escape is formed in a substantially central portion of the printed circuit board 34.

As shown in FIG. 2, at least one of the electronic components 38 includes a package portion 37 formed in a flat rectangular shape by covering a semiconductor chip with, for example, synthetic resin, and a package portion 37 of this package portion. And a plurality of terminals 39 extending outward from each side edge. And each terminal 3
The extended end portion of 9 is soldered to a predetermined position on the printed circuit board 34.

The heat dissipation sheet 40 is formed on the bottom wall 12 of the case 12.
It is sandwiched between a and the printed circuit board 34. The surface of the heat dissipation sheet 40 on the case 12 side is the case bottom wall 12a.
Is formed to be substantially flat. Further, in the heat dissipation sheet 40, the portion corresponding to the electronic component 38 is formed in conformity with the shape of this electronic component. That is,
The heat dissipation sheet 40 has a recess having a shape corresponding to the package portion 37 and the terminal 39 of the electronic component 38, and the electronic component is housed in the recess. As a result, the heat dissipation sheet 40 is provided in close contact with the bottom wall 12a of the case 12 and also with the electronic component 38 in close contact not only with the package portion 37 but also with the terminals 39.

As the material of the heat dissipation sheet 40, silicone resin, butylcom, acrylic resin or the like can be used. Further, in order to improve thermal conductivity, silica, silicon nitride, alumina, silicon carbide, boron nitride, nitride is used. It is possible to add aluminum, aluminum hydroxide or the like. In the present embodiment, as the material of the heat dissipation sheet 40,
Two types were used: a silicone resin containing alumina and boron nitride as filler, and a butyl rubber containing aluminum hydroxide as filler.

The heat dissipation structure having the printed circuit board 34, the heat dissipation sheet 40, and the case 12 as described above is formed by the following steps. First, as shown in FIG. 3, the printed circuit board 34 on which the electronic components 38, the connectors 42, 44, etc. are mounted, and the heat dissipation sheet 4 formed in a predetermined shape.
0 and prepare. The heat dissipation sheet 40 is made of, for example, butyl rubber having aluminum hydroxide as a filler and has a thickness of 1.6 mm.

Subsequently, as shown in FIG. 4, the heat dissipation sheet 4
0 at a predetermined position on the printed circuit board 34
Place them on top of each other. In this state, as shown in FIG. 5, the printed circuit board 34 and the heat dissipation sheet 40 are attached to the mold 54,
By placing between 56 and compression molding at 170 ° C,
The heat dissipation sheet 40 is formed into a shape along the electronic component 38 on the printed circuit board. Heat dissipation sheet 40 softened at high temperature
By compression molding, the heat dissipation sheet can be molded in almost the same shape as the electronic component 38.

Here, the surface of the die 56 that contacts the heat dissipation sheet 40 is shaped to conform to the unevenness of the bottom surface of the case 12. However, it is not necessary that the shape of the bottom surface of the case 12 is completely transferred. In the case of a completely transferred shape, the adhesion between the heat dissipation sheet 40 and the bottom surface of the case 12 deteriorates due to a slight deviation in size. Therefore, it is desirable that the convex portion on the inner surface of the mold 56 be formed to have a slightly smaller dimension than the corresponding concave portion on the bottom surface of the case 12 to have a margin for a dimensional error. Then, the printed circuit board 34 with the heat dissipation sheet formed as described above is screwed to the bottom wall 12a of the case 12, so that the heat dissipation sheet 40 is sandwiched between the printed circuit board and the case bottom wall. Stick to.

The heat dissipation structure may be formed by the following steps. First, for example, a phase change type heat dissipation sheet 40 made of polyisobutylene and aluminum hydroxide, here, a heat dissipation sheet having a thickness of 1.6 mm and a phase change temperature of 60 ° C. is prepared and placed on a predetermined position on the printed circuit board 34. Place it. Next, the heat dissipation sheet 40 is heated to about 90 ° C. by a heater or the like to be softened, and then compression molding is performed at a mold temperature of 40 ° C. using the molds 54 and 56 described above. The printed circuit board 34 with the heat dissipation sheet formed in this manner is screwed to the bottom wall 12a of the case 12, and H
Installed in DD.

Alternatively, the following method may be used. That is, a casting mold having the same shape as the case 12 is prepared, and the printed circuit board 34 is mounted on the casting mold. Subsequently, a curable liquid silicone resin containing silicon carbide as a filler is injected between the casting mold and the printed circuit board. Then, after degassing in vacuum, the liquid silicone resin is heated to 180 ° C.
Heat cure for 1 hour. As a result, a printed circuit board 34 covered with a heat dissipation sheet made of silicone rubber is obtained, which is screwed to the bottom wall 12a of the case 12,
Installed in D.

According to the HDD configured as described above,
The heat dissipation sheet 40 is formed in conformity with the shape of the electronic component 38 to be cooled, and is arranged so as to be in close contact with the entire package portion 37 and terminals 39 of the electronic component. In particular, since the terminal 39 is made of metal and has high heat dissipation, the heat dissipation of the electronic component 38 can be improved. Comparing the above-described present embodiment with the case where the heat dissipation sheet is brought into contact with only the package part of the electronic component, the heat dissipation efficiency of the electronic component is improved by 20%. Here, the heat dissipation efficiency is defined as follows.

[Equation 1]

Therefore, it is possible to obtain a cooling structure for electronic components having excellent heat dissipation, and at the same time, it is possible to obtain an HDD which can suppress the temperature rise of the electronic components 38 and can operate stably even in a high temperature environment.

The present invention is not limited to the above-mentioned embodiments, but can be variously modified within the scope of the present invention. For example, in the above-described embodiment, the heat dissipation sheet 40 has the plurality of electronic components 38 on the printed circuit board 34.
However, it is also possible to cover each electronic component with a separate heat dissipation sheet. In this case, as shown in FIG.
And a rectangular frame-shaped second portion 40b which is formed so as to cover the periphery of the package portion 37 and contact the terminals 39. The first and second portions 40a and 40b may be integrally molded or may be formed by bonding separately formed ones.

Further, as shown in FIG. 7, in the bottom wall 12a of the case 12, an uneven portion may be provided in a region facing the electronic component 38. In this case, the surface of the heat dissipation sheet 40 on the case 12 side is formed in an uneven shape so as to match the case bottom wall 12a, and is in close contact with the case bottom wall. With such a configuration, the contact area between the heat dissipation sheet 40 and the case 12, that is, the heat dissipation area is increased, and the heat dissipation of the electronic component 38 can be further improved.

Further, as shown in FIG. 8, the printed circuit board 34 is attached to the bottom wall 12 of the case 12 near the electronic component 38.
By screwing to a, the heat dissipation sheet 40 may be adhered to the electronic component and the bottom wall of the case to improve heat dissipation. In this case, as shown in FIGS. 4 and 8, at least two through holes 50 are provided in the printed circuit board 34 on both sides of the electronic component 38 with the electronic component 38 interposed therebetween, and the screws 51 are respectively inserted through these through holes to form a case. Bottom wall 12
The printed circuit board is screwed into place by screwing it into a. It should be noted that the screwing position, that is, the position of the through hole 50 is preferably provided within a distance L from the outer edge of the package part, where L is the diagonal length of the package part 37 of the electronic component 38. .

In addition, the shape and material of the heat dissipation sheet can be changed as necessary. Further, the cooling structure of the electronic component according to the present invention is not limited to the HDD and can be applied to other electronic devices.

[0033]

As described in detail above, according to the present invention, the temperature rise of the electronic component is effectively achieved by providing the heat dissipation sheet having the shape corresponding to the electronic component between the base and the printed circuit board. It is possible to provide a cooling structure for an electronic component that can be effectively suppressed, a magnetic disk device including the same, and a method for manufacturing a cooling structure for an electronic component.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an HDD according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a heat dissipation sheet portion of the HDD in a cutaway manner.

FIG. 3 is a plan view of a printed circuit board and a heat dissipation sheet of the HDD.

FIG. 4 is a plan view showing a state in which a heat dissipation sheet is placed on the printed circuit board.

FIG. 5 is a cross-sectional view showing a manufacturing process of the heat dissipation sheet.

FIG. 6 is a diagram showing a heat dissipation sheet and an electronic component according to another embodiment of the present invention.

FIG. 7 is a sectional view showing a heat dissipation sheet portion of an HDD according to still another embodiment of the present invention in a cutaway manner.

FIG. 8 is a sectional view showing a heat dissipation sheet portion of an HDD according to another embodiment of the present invention in a cutaway manner.

[Explanation of symbols]

10 ... HDD 12 ... Case 12a ... bottom wall 16a, 16b ... magnetic disk, 18 ... Spindle motor 34 ... Printed circuit board 37 ... Package part 38 ... Electronic components 39 ... Terminal 40 ... Heat dissipation sheet

Claims (7)

[Claims] 1. A base, a printed circuit board on which electronic components are mounted, and which is provided to face the base with a predetermined gap, and between the base and the printed circuit board. And a sandwiched heat dissipation sheet, wherein the electronic component has a package portion and a plurality of terminals extending from the package portion, and the heat dissipation sheet has a shape along the shape of the electronic component. A cooling structure for an electronic component, which is provided in contact with the package portion of the electronic component, the terminal, and the base. 2. A region of the base that faces the electronic component has irregularities, and a surface of the heat dissipation sheet on the base side is formed in an irregular shape corresponding to the irregularities. 1. A cooling structure for an electronic component according to 1. 3. The heat dissipation sheet has a first portion in contact with an upper surface of a package portion of the electronic component, and a second portion in contact with the periphery of the package portion and the terminals, and a single electronic component. The cooling structure for the electronic component according to claim 1, wherein the cooling structure covers the. 4. A base on which a magnetic disk is arranged, an electronic component is mounted, a printed circuit board provided facing the base with a predetermined gap, and the base and the print. A heat dissipation sheet sandwiched between the circuit board and the electronic component, the electronic component has a package portion and a plurality of terminals extending from the package portion, the heat dissipation sheet is in the shape of the electronic component. A magnetic disk device having a conformal shape and provided in contact with the package part of the electronic component, the terminal, and the base. 5. The region of the base opposite to the electronic component has irregularities, and the surface of the heat dissipation sheet on the base side is formed in an irregular shape corresponding to the irregularities. 4. The magnetic disk device according to item 4. 6. The heat dissipation sheet has a first portion that is in contact with the upper surface of the package portion of the electronic component and a second portion that is in contact with the periphery of the package portion and the terminals, and is a single electronic component. The magnetic disk device according to claim 4, wherein the magnetic disk device covers the magnetic disk device. 7. A base, a printed circuit board on which electronic components are mounted, and which is provided to face the base with a predetermined gap, and between the base and the printed circuit board. A heat dissipation sheet sandwiched between the electronic component and the electronic component, the electronic component having a package portion and a plurality of terminals extending from the package portion. A heat dissipation sheet is placed on the electronic component at a predetermined position, and the heat dissipation sheet placed on the printed circuit board is heated to a predetermined temperature to be softened, and then the heat dissipation sheet is placed along the electronic component. Manufacturing a cooling structure for electronic parts, characterized in that the printed circuit board with the heat dissipation sheet is attached to the base and the heat dissipation sheet is sandwiched between the printed circuit board and the base. Law.