Heat sink and information processor using it

Details Heat sink and information processor using it Heat sink and information processor using it

2001-08-20

2002-12-31

Schuberg, Darren (Department: 2835)

Electricity: electrical systems and devices

Housing or mounting assemblies with diverse electrical...

For electronic systems and devices

C361S689000, C361S692000, C361S695000, C257S721000, C165S104320, C165S080200

Reexamination Certificate

active

06501652

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a heat sink. More particularly, the present invention relates to a heat sink used for cooling an integrated circuit package, which generates heat, such as a microprocessor unit (MPU) incorporated into electronic equipment.
2. Description of the Related Art
Recently, concerning the integrated circuits used for a personal computer, especially concerning the MPU, the degree of integration is enhanced so as to enhance the function of the integrated circuit and increase the processing speed. Therefore, the quantity of heat generated in the integrated circuit has been increased. Accordingly, the inside of the casing of a personal computer is forcibly cooled by a cooling fan, and the MPU is located at a position where the cool air of the cooling fan flows, and a heat sink provided with a large number of fins is fixed to the MPU so that the MPU can be forcibly air-cooled. However, an MPU of a higher performance is now required for a personal computer. An MPU of a higher performance generates a quantity of heat larger than that generated by other electronic parts. For this reason, there is used a heat sink into which a cooling fan is incorporated so that an MPU, which generates a large quantity of heat, can be locally cooled by means of forcible air cooling. Such a heat sink into which a cooling fan is incorporated as a local cooling means is used to replace a conventional heat sink into which a cooling fan is not incorporated. Accordingly, there is proposed a heat sink of small size in which the cooling fan or a portion of the cooling fan is incorporated inside the cooling fins.
FIGS.
15
A~C are views showing a heat sink described in Japanese Unexamined Patent Publication No. 62-49700 which is used as a local cooling means.
FIG. 15A
is a plan view which is taken from the upper surface side,
FIG. 15B
is a cross-sectional view taken at the one-dotted chain line ABCD shown in
FIG. 15A
, and
FIG. 15C
is a plan view taken in the direction of arrow Z in FIG.
15
B. As shown in
FIGS. 15A and 15B
, this heat sink is composed in such a manner that a motor
2
a
, which is a drive section for blades
2
b
, is attached to the main body
1
of the heat sink, and fins
1
a
are perpendicularly arranged so that they surround the blades
2
b
. As shown in
FIGS. 15B and 15C
, the main body
1
of the heat sink is fixed to a heating element
3
such as a power transistor. Heat generated in the heating element is conducted to a bottom portion of the main body of the heat sink and further conducted to the fins
1
a
. When the motor
2
a
is driven, the blades
2
b
are rotated, so that cooling air is sucked from an upper portion of the cooling fan
2
. The cooling air to which a centrifugal force is given by the rotation of the blades
2
b
cools the upper portions of the fins
1
a
, and the cooling air blown out downward by the blades
2
b
cools lower portions of the fins
1
a
. In this way, the cooling air which has been sucked from the upper portion passes through the fins
1
a
is discharged into the periphery of the heat sink. Therefore, the main body
1
of the heat sink can be cooled and further the heating element
3
can be cooled.
FIG. 16
is a view showing the heat sink described in Japanese Unexamined Patent Publication (PCT route) No. 8-502804. In the overall periphery of the main body
1
of the heat sink, there are provided a plurality of perpendicular fins
1
a
, and the cooling fan
2
is supported by the main body
1
of the heat sink. When the motor is arranged inside the blades
2
b
, the height of the cooling fan
2
in the axial direction is reduced, and when a portion of the cooling fan
2
intrudes into the main body of the heat sink, the thickness of the fan body
5
is reduced. When the cooling fan
2
is driven, the blades
2
b
are rotated, so that a cooling air can be sucked from the upper portion. The thus sucked cooling air cools the bottom portion of the main body
1
of the heat sink and passes through among the fins
1
a
. Therefore, the cooling air absorbs the heat which has been conducted from the main body
1
of the heat sink to the fins
1
a
, and the absorbed heat is dissipated to the periphery of the heat sink. When this heat sink is fixed to a heating element such as an MPU, the heating element can be locally cooled.
FIGS. 17A and 17B
are views showing the heat sink described in Japanese Unexamined Patent Publication No. 6-268125.
FIG. 17A
is a plan view which is taken from the upper surface.
FIG. 17B
is a cross-sectional view taken on line B—B in FIG.
17
A. The motor
2
a
of the cooling fan
2
is fixed to the bottom portion of the main body
1
of the heat sink, and cooling fins
1
a
are perpendicularly arranged in such a manner that they surround the cooling fan
2
. The bottom portion of the main body
1
of the thus composed heat sink is fixed to a heating element
3
such as an MPU. When the motor
2
a
is driven, the blades
2
b
are rotated, so that a cooling air can be sucked from the upper portion. The sucked cooling air passes through among the fins
1
a
and discharges into the periphery of the heat sink. When the fins
1
a
are cooled, the heating element
3
can be cooled via the main body
1
of the heat sink.
In the heat sinks shown in
FIGS. 15A-C
and
17
A and
17
B, the motor
2
a
which drives the cooling fan
2
is directly fixed to the bottom portion of the main body
1
of the heat sink. In the driving section of the cooling fan
2
, ball bearings or sleeve bearings are used, and lubricant such as grease or oil is charged in the bearing. Due to the above structure, heat is directly transmitted to the bearing from the bottom portion of the main body
1
of the heat sink located close to the heating element
3
. Accordingly, the temperature of the bearing is raised. When the temperature of the bearing is raised, the deterioration of the grease or oil is facilitated, and the life of the motor
2
a
is shortened.
In the heat sink shown in
FIG. 16
, the cooling fan
2
is mounted on the upper portion. Accordingly, areas of the fins
1
a
arranged on the side are small. Therefore, in order to realize a sufficiently high cooling performance, it is necessary to provide small fins with very small intervals between the fins. In order to realize the small fins
1
a
, the manufacturing cost is increased in the cutting process. Further, since the intervals between the fins
1
a
are very small, blocking tends to occur when dust gathers between the fins
1
a
. Accordingly, a quantity of cooling air is lowered, and the cooling performance is deteriorated.
In the structure of the heat sinks shown in FIGS.
15
A~C and
17
A and
17
B in which the fins
1
a
are perpendicularly arranged on the overall bottom surface of the main body
1
of the heat sink, analysis of the flow of the cooling air becomes complicated and also analysis of the noise becomes complicated. Therefore, it is difficult to design the heat sink. Accordingly, it is impossible to optimize the cooling performance and reduce the noise.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a heat sink of low manufacturing cost and long life, the cooling performance of which is sufficiently high and in which the designing of the heat sink can be easily performed.
The invention described in claim
1
is to provide a heat sink comprising a box composed of a bottom surface coming into contact with a heating element, a side on which ventilation holes are formed and an upper surface on which a cooling fan having at least blades and a motor is embedded and fixed. Due to the above structure, when the design of the hole is changed, the performance can be easily optimized, and when the upper surface is provided on the box and the cooling fan is fixed onto the upper surface, the area of the side of the box can be sufficiently ensured, and further the deterioration of lubricant in the motor bearing can be prevented.
The invention described in
FIG. 2
is to provide a heat sin

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