JP2003068943A - Cooling device and electronic equipment with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the heat-dissipation performance of a heating element while obtaining a cooling device having no adverse effect on environment. SOLUTION: The cooling device has a heat sink 24 being larger than an IC chip (the heating element) 16 and being arranged while covering the chip 16, a heat spreader 25 interposed between the sink 24 and the IC chip 16, a joining metal member 26 interposed between the spreader 25 and the IC chip 16 and a thermal conduction member 27 interposed between the heat spreader 25 and the heat sink 24. The joining metal member 26 is made of a tin alloy containing no lead component, the heat spreader 25 and the IC chip 16 are joined so as to be thermally connected, and the heat of the IC chip 16 is transmitted to the heat spreader 25. The heat spreader 25 is larger than the IC chip 16, and diffuses the heat of the IC chip 16 transmitted to heat spreader itself. The thermal conduction member 27 transmits the heat of the heat spreader 25 to the heat sink 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device for promoting heat dissipation of a heating element such as a semiconductor package, and electronic equipment such as a portable computer equipped with this device.

[0002]

2. Description of the Related Art Electronic equipment represented by a computer is
It is equipped with a semiconductor package for processing multimedia information such as characters, voice, and images. In this type of semiconductor package, the power consumption is steadily increasing as the processing speed is increased and the number of functions is increased, and the amount of heat generated tends to increase in proportion to this.

In order to ensure stable operation of electronic equipment, a cooling device for improving the heat dissipation of the semiconductor package is indispensable.

There is a conventional cooling device in which a heat spreader is arranged between an IC chip which is a heat generating portion of a semiconductor package and a heat sink which covers the IC chip. The heat spreader and the IC chip are thermally connected by the first heat connection layer, and the heat sink and the heat spreader are thermally connected by the second heat connection layer.

For the first and second thermal connection layers, a thermally conductive silicone rubber sheet or grease, or a thermosetting synthetic resin (silicone) adhesive is used. In some of these thermal connection layers, a filler of metal or ceramic having a higher thermal conductivity than that of the main material is mixed to increase the thermal conductivity.

However, the main material of the first and second thermal connection layers is a synthetic resin component. Therefore, even if the filler is mixed as described above, the improvement of the thermal conductivity is (10 to 15) W.
/ M · K is considered to be the limit.

Further, in a structure in which heat of a semiconductor package is radiated to a heat sink without using a heat spreader, there is one in which the heat generating portion of the semiconductor package and the heat sink are thermally connected using lead solder (Japanese Patent Laid-Open No. 10-
189839 and JP 2000-12748).

Because of the above-mentioned thermal connection, Japanese Patent Laid-Open No. 10-189
No. 839 discloses an example using a solder ball, and JP-A 2000-12748 describes an example using a solder sheet.

[0009]

In these techniques, since the thermal connection layer is made of metal, the thermal conductivity of the thermal connection layer is large, which is advantageous for promoting heat dissipation of the semiconductor package.

However, the metal thermal connection layer is formed of a solder containing a lead component, that is, a lead solder. Since lead is harmful to human health, it is not environmentally preferable in terms of manufacturing and recycling.

An object of the present invention is to obtain a cooling device and an electronic device which can enhance the heat radiation performance of a heating element and have no adverse effect on the environment.

[0012]

In order to achieve the above-mentioned object, a cooling device according to a first aspect of the present invention comprises a heat sink which is larger than a heating element and which is arranged to cover the heating element, and which is formed larger than the heating element. And a heat spreader interposed between the heat sink and the heating element, and made of a tin alloy containing no lead component, and joining them so as to thermally connect the heat spreader and the heating element, A joining metal member interposed between the heat spreader and the heating element; and a heat conducting member interposed between the heat spreader and the heat sink and thermally connecting the heat spreader and the heat sink. It has a feature.

The present invention can be suitably used as a cooling device for a semiconductor package such as a CPU, which generates heat in an electronic device such as a portable or disk-top type computer. Further, in the invention of claim 1, the heat conductive member is a silicone rubber sheet or grease having excellent heat conductivity, a thermosetting synthetic resin (silicone) adhesive, or a joining metal member containing no lead component. Can be used.

In the invention of claim 1, the heat generated by the heating element is transmitted to the heat spreader through the joining metal member. The heat transferred to the spreader is transferred to the heat sink through the heat conductive member while being diffused throughout the heat spreader. The heat transferred to this sink is
It is released from this heat sink. In such a heat radiation system, the medium that transfers the heat of the heating element to the heat spreader is the joining metal member, so that its thermal conductivity is large. Therefore, the thermal resistance of the heat connecting portion between the heating element and the heat spreader is suppressed to be small, and the heat of the heating element can be efficiently transmitted to the heat spreader.

In the heat dissipation system capable of efficiently transmitting heat as described above, while diffusing the heat over the entire heat spreader larger than the heating element as described above,
This heat can be transferred to the heat sink via the heat conducting member. For this reason, in the heat connection portion between the heat spreader and the heat sink, the amount of heat transfer per unit area is suppressed to be small, and the temperature difference between the heat spreader and the heat sink can be reduced.

As described above, the heat of the heating element can be efficiently transmitted to the heat spreader by the joining metal member, and the heat can be efficiently moved from the heat spreader to the heat sink.

Since a tin alloy containing no lead component is used for the joining metal member, it is preferable in that there is no adverse effect on the environment.

Further, in order to achieve the above-mentioned object, claim 8
According to another aspect of the invention, there is provided a cooling device, which comprises a heat sink which is larger than a heat generating element and which is disposed so as to cover the heat generating element, and which is made of a tin alloy containing no lead component and which is interposed between the heat sink and the heat generating element. It is characterized in that these are joined so as to be thermally connected to the heating element, and a joining metal member interposed between the heat sink and the heating element is provided.

The invention of claim 8 can be suitably used as a cooling device for an electronic component that generates heat in an electronic device such as a portable or desktop computer, for example, a semiconductor package such as a CPU.

In the invention of claim 8, the heat generated by the heating element is directly transmitted to the heat sink through the joining metal member and is radiated from the heat sink. In such a heat radiation system, the medium that transfers the heat of the heating element to the heat sink is the joining metal member, so that its thermal conductivity is high. Therefore, the thermal resistance of the heat connecting portion between the heating element and the heat sink is suppressed to be small, and the heat of the heating element can be efficiently transmitted to the heat sink.

Since a tin alloy containing no lead component is used for the joining metal member, it is preferable in that there is no adverse effect on the environment.

Further, in order to achieve the above-mentioned object, claim 1
The electronic device of the invention according to claim 1, an electronic component mounted on the circuit board having a housing, a circuit board built in the housing, and a heat generating IC chip, and the IC chip being larger than the IC chip. A heat sink arranged to cover the chip, made of a tin alloy containing no lead component, and the heat sink and the IC
And a bonding metal member interposed between the heat sink and the IC chip so as to be thermally connected to the heat sink and the IC chip, and interposed between the heat sink and the IC chip. It is characterized by that.

According to the eleventh aspect of the invention, the heat generated by the IC chip of the electronic component is directly transmitted to the heat sink through the joining metal member and is radiated from the heat sink. In such a heat radiation system, the medium that transfers the heat of the heating element to the heat sink is the joining metal member, so that its thermal conductivity is high. Therefore, the thermal resistance of the heat connecting portion between the heating element and the heat sink is suppressed to be small, and the heat of the heating element can be efficiently transmitted to the heat sink.

Since a tin alloy containing no lead component is used for the joining metal member, it is preferable in that there is no adverse effect on the environment.

[0025]

DETAILED DESCRIPTION OF THE INVENTION A first embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a portable computer 1 as an electronic device. The computer 1 includes a computer main body 2 and a display unit 3 supported by the main body 2.

As shown in FIG. 2, the housing 4 of the computer main body 2 includes a bottom wall 4a, an upper wall 4b, a front wall 4c, left and right side walls 4d (only one of which is shown in FIG. 1), and a rear wall (not shown). It has a flat box shape.

The upper wall 4a of the housing 4 has a palm rest 5 and a keyboard mounting portion 6 located behind it. A keyboard 7 is installed on the keyboard mounting portion 6.

The display unit 3 includes a display housing 9 and a liquid crystal display panel 10 housed in the housing 9. The liquid crystal display panel 10 is
It has a display screen 10a for displaying an image, and this screen 10a
Are exposed in the opening 11 on the front surface of the display housing 9.

The display housing 9 is connected to the rear end of the upper wall 4b via a hinge device 12. Therefore, the display unit 3 is rotatably supported between a closed position in which the display unit 3 is tilted down to cover the upper wall 4b from above and an open position in which the display unit 3 is erected to expose the upper wall 4b and the liquid crystal display panel 10. .

As shown in FIG. 2, a circuit board 13 is housed inside the housing 4. The circuit board 13 has a mounting surface 13a facing the upper wall 4b of the housing 4 and the keyboard 7, and for example, a ball grid array (BGA) solder connection type semiconductor package 14 is an electronic component that generates heat on the surface 13a. Has been implemented.

The semiconductor package 14 is the computer 1.
It constitutes the core microprocessor. As shown in FIG. 3, the semiconductor package 14 has a rectangular base substrate 15 and an IC chip 16 as a heating element. The length of one side of the base substrate 15 is about 30 mm. The IC chip 16 is attached to the central portion of the base substrate 15 by flip-chip connection. The IC chip 16 has a rectangular shape smaller than the base substrate 15, and one side thereof has a length of about 10 mm. The flat heat generating surface 16 a of the IC chip 16 slightly protrudes from one surface of the base substrate 15. The IC chip 16 processes multimedia information such as characters, voices, and images at high speed.
The amount of heat generated during its operation is very large.

On the other surface of the base substrate 15, a large number of solder balls 17 (see FIG. 4) are arranged side by side in a grid pattern. These solder balls 17 are soldered to the mounting surface 13 a of the circuit board 13. It is environmentally preferable to use a solder containing no lead component (so-called lead-free solder) for the solder ball 17.

As shown in FIGS. 2 and 4, a cooling device 21 for cooling the semiconductor package 14 is housed. The cooling device 21 includes a heat dissipation portion 22 and an electric fan portion 23, and is incorporated between the circuit board 13 and the upper wall 4b of the housing 4.

The heat radiating portion 22 includes a heat sink 24, a heat spreader 25, a joining metal member 26, and a heat conducting member 27.

The heat sink 24 is made of a metal having excellent thermal conductivity, such as copper or a copper alloy, aluminum or an aluminum alloy. The heat sink 24 has a base portion 24a and a top plate 24b that covers the base portion 24a from above and is connected to the base portion 24a, and has a flat box shape. The base portion 24a and the top plate 24b cooperate with each other to form the cooling air passage 28. The outlet 28a of this cooling air passage 28
Are close to and face the exhaust port 29 (see FIGS. 1 and 2) opened on one side wall 4.

The base portion 24a used as a heat receiving portion has a rectangular shape, and its planar shape is formed to be much larger than that of the semiconductor package 14. A plurality of heat radiation fins (only one is shown in the figure) 24c are integrally provided on one surface of the base portion 24a facing the top plate 24b. The radiating fins 24c are provided in parallel with each other with being separated from each other, and are arranged so as to extend in the longitudinal direction of the heat sink 24 (the flow direction of the air in the cooling air passage 28).

The base portion 24a of the heat sink 24 is screwed to the circuit board 13. In this mounted state, the base portion 24a is separated from the mounting surface 13a by a predetermined distance, and is arranged so as to cover the entire semiconductor package 14 from the IC chip 16 side.

The heat spreader 25 is the heat sink 2
It is made of the same metal material as 4 and its thickness is several mm. The heat spreader 25 has a rectangular shape in plan view and is smaller than the base portion 24 a of the heat sink 24. As shown in FIG. 3, the heat spreader 25 is formed smaller than the outer size of the semiconductor package 14 and larger than the IC chip 16.

As shown in FIG. 4B, the heat spreader 25 has a first heat connecting surface 25 which is one surface in the thickness direction.
a and the second heat connection surface 25b formed of the other surface in the thickness direction. The areas of the first and second heat connecting surfaces 25a and 25b are much larger than the area of the heat generating surface 16a. These thermal connection surfaces 25a and 25b are finished to be smooth.

The edge 25c of the heat spreader 25 is bent toward the first heat connection surface 25a side as shown in FIGS. Although the edge 25a is provided over the entire circumference of the heat spreader 25, it may be provided only on two sides parallel to each other.

The heat spreader 25 is interposed between the semiconductor package 14 and the heat sink 24. In this arrangement, the first thermal connection surface 25a is located on the semiconductor package 14 side and the second thermal connection surface 25b is located on the heat sink 24 side.

The heat spreader 25 covers the semiconductor package 14 and joins the package 14 with a metal member 26.
And the adhesive 30 is used for integration. By this integration, the semiconductor package 14 and the heat spreader 25
And can be handled as a single part in one assembly of electronic equipment or the like.

The joining metal member 26 is used for the semiconductor package 1.
4 is interposed in the clearance between the heat generating surface 16a of the IC chip 16 and the first heat connecting surface 25a of the heat spreader 25. The adhesive 30 is used for the semiconductor package 14
The base substrate 15 and the edge 25c of the heat spreader 25 are interposed and joined to each other.

The joining metal member 26 has a first heating surface 16a and a first heating member 16a.
The IC chip 16 and the heat spreader 25 are joined to each other by thermally connecting the thermal connection surface 25a. The joining metal member 26 is made of a lead-free low melting point metal, preferably a lead-free tin alloy.

The joining metal member 26 has a joining function like solder, and its thermal conductivity is as high as about 30 W / mK. The melting point of the joining metal member 26 is slightly higher than the melting point of the solder containing lead, but is relatively low at around 200 ° C. Since the joining metal member 26 is a low melting point metal in this way, when joining is performed using this, the heat resistance of the surrounding parts may be of a degree corresponding to the low melting point. Therefore, since high temperature environment and high temperature resistant parts are not required in the joining, it is excellent in terms of usability in manufacturing.

As a preferred example, the joining metal member 26 has a layered shape to form the joining, and the thickness of the joining metal layer is preferably about 0.1 mm in order to further reduce the thermal resistance.

As the tin alloy forming the joining metal member 26, a Sn—Ag base alloy containing tin (Sn) as a main component or a Sn—Zn base alloy containing tin as a main component can be preferably used.

The Sn-Ag base alloy containing no lead contains 80% by weight to 98% by weight of Sn and 2% by weight to 10% by weight.
And silver (Ag), and if necessary, an additive element is mixed therein. As an additive element, copper (Cu),
Examples thereof include indium (In) and bismuth (Bi).

Specific examples of this Sn-Ag based alloy are shown below. Example 1: Sn 96.5% by weight, Ag 3% by weight, Cu 0.5% by weight Example 2: Sn 93% by weight, Ag 3.5% by weight, In 3% by weight, Bi 0.5% by weight Example 3: Sn 92% by weight, Ag 3.5% by weight Wt%, In4 wt%, Bi0.5 wt% Example 4: Sn88 wt%, Ag3.5 wt%, In8 wt%, Bi0.5 wt% Example 5: Sn91.4 wt%, Ag3.2 wt%, In2 .7 wt%, Bi2.7 wt% Example 6: Sn93 wt%, Ag3.5 wt%, In3 wt%, Bi0.5 wt% Further, the Sn-Zn-based alloy containing no lead is 80 wt% or more 98 It contains Sn in an amount of 2% by weight and zinc (Zn) in an amount of 2% by weight or more and 15% by weight, and an additive element is mixed therein if necessary. Examples of the additive element include Bi.

Specific examples of this Sn-Ag based alloy are shown below. Example: Sn 89% by weight, Zn 8% by weight, Bi 3% by weight The adhesive agent 30 is bent toward the base substrate 15 of the semiconductor package 14, and the edge 2 of the heat spreader 25 is bent.
5c and the base substrate 15 are bonded. As the adhesive 30, it is preferable to use an adhesive material having excellent thermal conductivity, for example, a thermosetting silicone adhesive.

As shown in FIG. 4A, the distance A between the base substrate 15 and the edge 25c is set to be larger than the clearance B between the heat generating surface 16a and the first heat connecting surface 25a. ing. Therefore, the thickness of the layered joining metal member 26 is thinner than the layer of the adhesive 30. With this configuration, it is possible to prevent the edge 25c from hitting the base substrate 15 and preventing the first heat connecting surface 25a from approaching the heat generating surface 16a. Therefore, the thickness of the joining metal member 26 can be made extremely thin to about 0.1 mm as described above, and this is advantageous in that the thermal resistance of the joining metal member 26 itself can be made smaller.

The heat conducting member 27 is interposed in the clearance between the second heat connecting surface 25b of the heat spreader 25 and the base portion 24a of the heat sink 24. As the heat sink 24 is screwed onto the circuit board 13, the heat conducting member 27 is pinched between the second heat connection surface 25b and the base portion 24a and is in close contact with them.

The heat conducting member 27 is spread so as to have an area of substantially the same size as the second heat connecting surface 25b, and the area is much larger than the heat generating surface 16a. This heat conducting member 2
The thickness of 7 is thicker than the thickness of the joining metal member 26. The heat conduction member 27 is in close contact with the second heat connection surface 25b and the base portion 24a to thermally connect the heat spreader 25 and the heat sink 24. Therefore, the heat of the second heat connecting surface 25b is transferred to the base portion 24a through the heat conducting member 27.

Heat-conducting member 27 whose main component is a synthetic resin component
Has a thermal conductivity lower than that of the metal heat spreader 25 and the joining metal member 26. In order to improve the thermal resistance of the heat conducting member 27, a filler can be mixed in the synthetic resin component which is the main material of the heat conducting member 27. As the filler, a metal, a ceramic or the like having a thermal conductivity higher than that of the main material may be used. In the case of using the heat conducting member 27 in which the filler is mixed in this way, its heat conductivity becomes large. Therefore, heat transfer from the heat spreader 25 to the heat sink 24 becomes easier, and the heat dissipation of the semiconductor package 14 can be further improved, which is excellent.

For the heat conducting member 27, a silicone rubber sheet or grease which is flexible and has excellent heat conductivity can be preferably used. By using the heat conductive member 27 made of a silicone rubber sheet or grease, the heat sink 24 larger than the semiconductor package 14 can be provided so as to be separable from the heat spreader 25 with the heat conductive member 27 as a boundary.

Therefore, when inspecting the circuit board 13, the heat sink 24 can be separated. Therefore,
In the inspection, a large heat sink 24 is used when an inspection probe or the like is brought into contact with the semiconductor package 14.
Does not get in the way. Further, the heat spreader 25 integrated with the semiconductor package 14 is smaller than the outer size of the semiconductor package 14 and does not stick out around the package 14. Therefore, the heat spreader 25 also does not interfere with the inspection.

Moreover, since the heat conducting member 27 made of a silicone rubber sheet or grease is used, it is not necessary to apply a high temperature when separating the heat sink 24, and naturally it is necessary to apply a high temperature when the heat sink 24 is mounted again. Absent. Therefore, it is possible to easily attach / detach the heat sink 24 to / from the heat spreader 25 in the inspection or the like.

As shown in FIG. 2, the electric fan unit 23
Includes a fan casing 41 and a fan motor 42. The fan motor 42 is composed of an outer rotor type flat motor 42a and a large number of fans 42b protruding from the outer peripheral surface of the rotor. The fan motor 42 is driven when the temperature of the semiconductor package 14 exceeds the operation guarantee temperature.

The fan casing 41 has a hollow box shape and accommodates the fan motor 42. The fan casing 41 is continuous with the upstream end of the cooling air passage 28 and integrated with the heat sink 24. This fan casing 4
1, a suction port 43 is formed to face the fan 42b of the fan motor 42.

When the temperature of the semiconductor package 14 exceeds a predetermined operation guarantee temperature during use of the computer 1, the fan motor 42 is driven. Then, the fan motor 42 sends the air sucked from the suction port 43 into the cooling air passage 28 from the inside of the fan casing 41 as cooling air. This wind passes around the radiation fins 24c and is discharged from the exhaust port 29 to the outside of the housing 4.

The cooling air forcibly cools the heat sink 24 while flowing through the cooling air passage 28. for that reason,
As described below, heat dissipation of the semiconductor package 14 to the heat sink 24 is promoted.

A heat spreader 25 is arranged between the heat sink 24 and the IC chip 16 that generates heat during use of the computer 1 having the above-described structure.
5, the first heat connection surface 25a and the heat generation surface 16a of the IC chip 16
And are metal-bonded with an extremely thin metal joining member 26.

The thermal conductivity of the joining metal member 26 is 30 W / m.
It is much higher than K and heat conductive grease, and the thickness of the joining metal member 26 is as thin as about 0.1 mm, and the thermal resistance of itself is also small. Therefore, the thermal resistance of the thermal connection portion between the IC chip 16 and the heat spreader 25 can be extremely reduced to about 1/10 or less as compared with the case where the thermal connection is performed with the thermal conductive grease. Therefore, the heat generated by the IC chip 16 can be efficiently transmitted to the heat spreader 25 through the joining metal member 26.

Further, the heat spreader 25 and the base substrate 15 of the semiconductor package 14 are thermally connected via the adhesive 30 having excellent thermal conductivity. Therefore, the heat of the base substrate 15 heated by the IC chip 16 can also be transferred to the heat spreader 25 through the adhesive 30, so that the temperature rise of the base substrate 15 can be suppressed.

The area of the first and second heat connecting surfaces 25a, 25b of the heat spreader 25 is much larger than that of the heat generating surface 16a of the IC chip 16, and the heat conductivity of the heat spreader 25 is that of the heat conducting member 27. Greater than thermal conductivity. Therefore, from the IC chip 16 to the heat spreader 25
The heat transmitted to the heat spreader 25 is quickly diffused to every corner of the heat spreader 25. The heat thus diffused over the entire heat spreader 25 is transmitted to the heat sink 24 through the heat conducting member 27 that thermally connects the second heat connecting surface 25b and the heat sink 24, and the heat sink 2
It is released from 4 to the surroundings.

As described above, in the heat connection portion between the heat spreader 25 and the heat sink 24, the area required for heat connection is sufficiently large, so that the heat transfer amount per unit area can be suppressed to be small. Therefore, although the heat conducting member 27 is thicker than the joining metal member 26, the temperature difference between the heat spreader 25 and the heat sink 24 can be reduced.

With the heat dissipation system as described above, the IC chip 1
The heat of No. 6 is efficiently transmitted to the heat spreader 25 by the joining metal member 26, and the heat spreader 2
The heat can be efficiently transferred from 5 to the heat sink 24. As a result, the heat dissipation performance of the IC chip 16 can be improved and the temperature rise thereof can be suppressed, and by this suppression, stable operation of the computer 1 can be guaranteed.

In the heat dissipation system, a tin alloy such as a lead-free solder containing no lead component is used for the joining metal member 26 to quickly and efficiently move the heat of the IC chip 16 to the heat spreader 25 as described above. ing. As described above, the joining metal member 26 does not contain lead which is harmful to the health of the human body, so that it is preferable in that there is no adverse effect on the environment in terms of manufacturing and recycling.

By adopting the joining metal member 26 made of an alloy containing tin as a main component, the joining metal member 2
The melting point of 6 can be suppressed low. Therefore, when the heat spreader 25 is metal-bonded to the semiconductor package 14, it is not necessary to apply a considerably high temperature, which is preferable in manufacturing.

Moreover, tin, which is the main component of the joining metal member 26, is easily available at low cost. Therefore, it is also excellent in that the cost of the joining metal member 26 is low.

5 and 6 show a second embodiment of the present invention. Since this embodiment has basically the same configuration as that of the first embodiment, the same components are designated by the same reference numerals as those of the first embodiment, and the description of the configuration and operation thereof is omitted. Will be described. The difference between the second embodiment and the first embodiment is that the heat dissipation portion 2 of the cooling device 21 is different.
It is 2.

In the second embodiment, the heat dissipation portion 22 is
The heat spreader and the joining metal member 26 are provided, and the heat spreader and the heat conducting member used in the first embodiment are omitted. Then, the joining metal member 26
Is the base portion 24a of the IC chip 16 and the heat sink 24.
And a small clearance between them, and these are thermally connected to each other. That is, the IC chip 16 and the heat sink 24 are directly bonded via the layered bonding metal member 26. The configuration other than the above points is the same as that of the first embodiment, including the configuration not shown in FIGS. 5 and 6.

In such a structure, the heat generated by the IC chip 16 as the heat generating element can be directly transmitted to the heat sink 24 through the joining metal member 26 and can be released from the heat sink 24.

In this heat dissipation system, the joint metal member 26 in which the IC chip 16 and the heat sink 24 are metal-joined has a thin thickness of about 0.1 mm and a thermal conductivity of 30 W / mK.
And extremely high. Therefore, the thermal resistance of the thermal connection portion between the IC chip 16 and the heat sink 24 is suppressed to be small, and the heat of the IC chip 16 can be efficiently transmitted to the heat sink 24 to be radiated. Therefore, by improving the heat dissipation performance of the IC chip 16,
The temperature rise can be suppressed, and stable operation of the computer 1 can be guaranteed by this suppression.

Since the joining metal member 26 is made of a tin alloy containing no lead component, it is preferable in that it has no adverse effect on the environment. Furthermore, the melting point of the joining metal member 26 can be suppressed low, and the cost of the joining metal member 26 is low, which is also excellent.

[0077]

The present invention is carried out in the form as described above, and has the following effects.

According to the cooling device of the present invention, the heat of the heating element is efficiently transmitted to the heat spreader via the joining metal member, and the heat is efficiently transferred from this heat spreader to the heat sink, so that the heat dissipation performance of the heating element is improved. In addition, since a tin alloy containing no lead component is used for the joining metal member, it is excellent in that it does not adversely affect the environment.

Further, according to the cooling device of the present invention, the heat of the heating element is directly and efficiently transferred to the heat sink through the joining metal member, so that the heat dissipation performance of the heating element can be improved and the joining metal member Since a tin alloy containing no lead component is used, it is excellent in that it does not adversely affect the environment.

Further, according to the electronic apparatus of the present invention, in the cooling device for suppressing the temperature rise of the electronic component, the heat of the heating element is efficiently transmitted to the heat sink through the joining metal member, so that the heat radiation performance of the heating element is improved. In addition, since a tin alloy containing no lead component is used for the joining metal member, it is excellent in that it does not adversely affect the environment.

[Brief description of drawings]

FIG. 1 is a perspective view showing an electronic device according to a first embodiment of the invention.

FIG. 2 is a cross-sectional view showing a part of the electronic device of FIG.

FIG. 3 is a perspective view showing a relationship between a semiconductor package and a heat spreader included in the electronic device of FIG.

FIG. 4A is a cross-sectional view showing a heat radiating portion of a cooling device included in the electronic device of FIG. FIG. 2B is a cross-sectional view showing the semiconductor package, the heat spreader, and the heat sink included in the electronic device of FIG. 1 separated from each other.

FIG. 5 is a sectional view showing a part of an electronic device according to a second embodiment of the invention.

6 is a cross-sectional view showing a heat dissipation portion of a cooling device included in the electronic device of FIG.

[Explanation of symbols]

1 ... Computer (electronic device) 4 ... Case 13 ... Circuit board 14 ... Semiconductor package (electronic component) 15 ... Base substrate 16 ... IC chip (heating element) 21 ... Cooling device 22 ... Heat dissipation part 24 ... Heat sink 25 ... Heat spreader 25a ... Edge of heat spreader 26 ... Joined metal member 27 ... Heat conduction member 30 ... Adhesive

Claims (14)

[Claims] 1. A heat sink which is larger than a heat generating element and is arranged to cover the heat generating element, a heat spreader which is formed larger than the heat generating element and is interposed between the heat sink and the heat generating element, and does not contain a lead component. A joining metal member made of a tin alloy, which is joined so as to thermally connect the heat spreader and the heating element, and is interposed between the heat spreader and the heating element; the heat spreader and the heat sink; And a heat conduction member that is interposed between the heat spreader and the heat sink to thermally connect the heat spreader and the heat sink. 2. The heat spreader is smaller than the outer size of a semiconductor package having an IC chip as the heating element, and an edge of the heat spreader is connected to the semiconductor package with an adhesive. Cooling system. 3. The thickness of the joining metal member is thinner than the thickness of the heat conducting member.
The cooling device according to. 4. The cooling device according to claim 1, wherein an area of the heat conducting member is larger than an area of the joining metal member. 5. The cooling device according to claim 1, wherein the thermal conductivity of the joining metal member is made higher than the thermal conductivity of the heat conducting member. 6. The cooling device according to claim 1, wherein the heat sink is detachably connected to the heat spreader. 7. The heat conducting member is mixed with a filler of a metal or a ceramic having a heat conductivity higher than that of the main material of the heat conducting member. The cooling device according to item 1. 8. A heat sink, which is larger than the heat generating element and is disposed so as to cover the heat generating element, and a tin alloy containing no lead component, the heat sink and the heat generating element being interposed between the heat sink and the heat generating element. And a joining metal member interposed between the heat sink and the heating element by joining them so as to be thermally connected to each other. 9. The cooling device according to claim 1, wherein the joining metal member is formed of a Sn—Ag based alloy containing tin as a main component. 10. The bonding metal member is formed of an Sn—Zn based alloy containing tin as a main component.
Or the cooling device according to 8. 11. A housing, a circuit board built in the housing, an electronic component having an IC chip that generates heat, mounted on the circuit board, and covering the IC chip larger than the IC chip. The heat sink to be arranged and a tin alloy containing no lead component are interposed between the heat sink and the IC chip, and the heat sink and the IC chip are arranged so as to thermally connect the heat sink and the IC chip. An electronic device, comprising: a joining metal member interposed between and. 12. A heat spreader larger than the IC chip is interposed between the heat sink and the IC chip, and the heat spreader and the IC chip are joined so as to be thermally connected by the joining metal member, and The electronic device according to claim 11, wherein a heat conductive member that thermally connects the heat spreader and the heat sink is interposed between the heat spreader and the heat sink. 13. The joining metal member is formed of a Sn—Ag based alloy containing tin as a main component.
The cooling device according to 1 or 12. 14. The bonding metal member is formed of a Sn—Zn based alloy containing tin as a main component.
The cooling device according to 1 or 12.