JPH1168360A - Cooling structure for semiconductor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling structure for semiconductor element which can cool semiconductor elements having different sizes and mounted on a multichip module by efficiently radiating the heat generated from each semiconductor element through a simple means. SOLUTION: A thermally conductive elastic body which thermally connects each semiconductor element 3 mounted on a printed board 1 to a heat radiating plate 4 is provided in the gap between each element 3 and plate 4. The elastic body has at least a face-contact section which is brought into contact with the semiconductor element 3 and, perhaps, another face-contact section which is brought into contact with the heat radiating plate 4. To be more concrete, the thermally conductive elastic body is formed in a plate spring-like state. A metal having high thermal conductivity and elasticity or a thermally conductive resin is used for forming the elastic body.

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 a semiconductor device used in electronic equipment such as a small portable device, and more particularly to a cooling structure for a multi-chip module having a plurality of different semiconductor devices. The present invention relates to a cooling structure for a semiconductor device.

[0002]

2. Description of the Related Art In recent years, in a multi-chip module on which a plurality of semiconductor devices constituting a part of an electronic device are mounted, the size of the mounted semiconductor device has been increased due to the miniaturization and portableness of the electronic device. The degree of integration is further improved. In addition, the number of semiconductor elements mounted has been increasing in order to satisfy the multifunctionality of electronic equipment. further,
In each of these semiconductor elements, the amount of heat dissipated also increases as the operation speed increases, and the total amount of heat generated by the multi-chip module increases remarkably in conjunction with the increase in the degree of integration and the number of semiconductor elements. Since heat generated from the semiconductor element has an adverse effect on the semiconductor element itself, it is necessary to efficiently radiate heat to cool the semiconductor element.

When the size of electronic equipment is large, the cooling mechanism is often complicated, so that a cooling device using an air-cooling system or a water-cooling system is often arranged in order to efficiently radiate heat. Therefore, the size of the cooling device itself also increases. On the other hand, in a small portable device, although the heating value of the semiconductor element is smaller than that in the case of a large device, it is difficult to arrange the above-described cooling device due to the limitation of the size of the device. It is. Therefore, a means for dissipating heat by providing a heat sink near the semiconductor element has been adopted.

In a small portable device having a semiconductor element mounted on an insulating substrate, it is best to make a direct contact between the semiconductor element and the heat radiating plate in order to effectively radiate the semiconductor element. It is conceivable to fix the semiconductor element to the heatsink using screws or the like so that the semiconductor element and the heatsink are brought into direct contact with each other so as to maintain a good contact state. However, when fixing is performed using screws or the like, excessive external stress is applied to the semiconductor element. When an excessive external stress is applied to the semiconductor element, the reliability of the semiconductor element decreases. Therefore, the heat sink cannot be fixedly brought into contact with the semiconductor element by means to which an excessive external stress is applied.

Conventionally, as a means for thermally connecting a semiconductor element and a heat sink without directly contacting the heat sink without applying excessive external stress, there is known a means for thermally connecting a semiconductor element and a heat sink to the heat sink. Is provided, and a means for filling the gap with a thermally conductive non-solid material called thermal grease is employed. Silicon grease or the like is used as the thermal grease.

An example of a cooling structure of a semiconductor device using thermal grease will be described below. FIG. 6 is a sectional view of a conventional cooling structure for a semiconductor device. In this example, a semiconductor element mounted by flip chip bonding will be described. A semiconductor element 13 is mounted on a printed board 11 by a flip chip bonding unit 12. On the upper part of the semiconductor element 13, a heat sink 14 is disposed substantially in parallel with a certain gap. The gap between the semiconductor element 13 and the heat sink 14 is filled with thermal grease 15 and is thermally connected. The printed circuit board 11
The electrical connection between the semiconductor element 13 and the
It is done by.

The heat generated from the semiconductor element 13 is transferred to a heat radiating plate 14 thermally connected through a thermal grease 15.
Conducted to. The heat conducted to the heat radiating plate 15 is cooled by natural cooling or by a cooling means (not shown) provided in particular, and is radiated.

However, although the thermal conductivity of the thermal grease filling the gap between the semiconductor element and the heat sink is relatively high,
The heat radiation effect is significantly lower than in the case where the semiconductor element is directly contacted with the heat radiation plate to dissipate heat.

In the case of a multi-chip module, a plurality of different semiconductor elements are mounted on an insulating substrate, and the thickness of each semiconductor element, that is, the gap distance from the printed board to the surface of the semiconductor element on the heatsink side, and the size of each semiconductor element. That is, the area of the surface of the semiconductor element on the heat sink side is different. Therefore, a difference in the gap distance between each semiconductor element and the heat sink occurs, and as a result, a difference in the thickness of the thermal grease filled in the gap between each semiconductor element and the heat sink occurs. Due to the difference in the thickness of the thermal grease, there is a problem that a heat dissipation mechanism such as heat transfer is complicated and a heat dissipation effect is reduced. Furthermore, it is necessary to control the amount of thermal grease to be filled according to the area of the site where the thermal grease contacts the heat sink side surface of each semiconductor element.
There has also been a problem that the manufacturing process becomes complicated.

Therefore, various means have been developed as a cooling structure for a multi-chip module on which a plurality of different semiconductor elements are mounted, which can solve these problems. As a main means, without using thermal grease, a metal heat radiating plate with high thermal conductivity is pressed against the multi-chip module, and the heat generated from the semiconductor element is conducted to the metal heat radiating plate. In some cases, heat is released by cooling the plate.

For example, in the technique described in Japanese Patent Publication No. 58-31732, chips are cooled by a heat conducting piston and cooling fins on a substrate on which a plurality of integrated circuit chips are mounted. Specifically, a heat-conductive flange is provided on the tip end surface of the piston, and the flange is divided into a plurality of chip connection portions by slots. Therefore, heat generated in the plurality of chips in contact with the flange is transmitted to the heat transfer piston via the flange, and further dissipated by the cooling fins. It is also possible to newly use a spring means for pressing the chip contact portion against the chip so as to provide good contact between the chip and the flange. Further, the spring means may be formed by a curved extension of the tip contact portion. According to this configuration,
Since the heat-conducting flange surface contacts the plurality of chips, the temperature of the chips is averaged, and it is not necessary to take special measures for the low-power chip as in the prior art. Further, since the heat is radiated by the fins of the common piston, the size of the module is not increased, and no large impedance is given to the cooling air flow.

As a technique already reported by the present applicant, there is a technique described in Japanese Patent Application Laid-Open No. 1-270298. A plurality of multi-chip packages (modules) each having a printed circuit board and a plurality of semiconductor elements mounted thereon and arranged in a row on the printed circuit board, and a cold plate having a coolant flow path, each of which is positioned between the respective multi-chip packages. A plurality of heat conducting plates thermally coupled to the cold plate; a force provided between the heat conducting plate and the multi-chip package; and a force pressing the heat conducting plate and the multi-chip package. And a leaf spring that provides A multi-chip package provided with a semiconductor element as a heating element is arranged between the heat conductive plates connected to the cold plate, and the multi-chip package is brought into close contact with the heat conductive plate via a cool sheet and a leaf spring, so that an individual heat generation amount is obtained. Can efficiently cool a memory-based semiconductor element, which is low in number but is frequently mounted, by a water-cooling method.

[0013]

However, the conventional technique has the following problems. Japanese Patent Publication No. 58-3
According to the technology described in Japanese Patent No. 1732, when cooling the multi-chip module as described above, the gap distance between each semiconductor element and the heat sink is different, so that each semiconductor element is brought into contact with the semiconductor element with an appropriate stress. It is necessary to change the shape of the flange portion according to each gap distance. Therefore, the shape of the heat conduction piston becomes complicated, which leads to an increase in manufacturing cost. In addition, the heat transfer piston becomes large due to its complicated shape, so that it is difficult to apply the heat transfer piston to a small portable device. Furthermore, since a coil spring is used, the heat radiation mechanism is complicated, and the heat radiation effect may be reduced.

The technique described in Japanese Patent Application Laid-Open No. 1-270298 is also configured in consideration of effective heat radiation in a large-sized device in terms of cooling with a water-cooling method. Application to is inappropriate. Also, since a plurality of chips are adhered to the heat conductive plate by one leaf spring, it is effective when the thickness of each semiconductor element is almost the same, and when the thickness is different, good heat conduction and heat radiation are performed. There is a problem that cannot be solved.

An object of the present invention is to provide a cooling structure for a semiconductor element mounted on a multi-chip module having a plurality of semiconductor elements having different sizes, and to efficiently generate heat from each semiconductor element by simple means. An object of the present invention is to provide a cooling structure for a semiconductor element which can dissipate and cool the semiconductor element.

[0016]

SUMMARY OF THE INVENTION The present invention is a cooling structure for a semiconductor device, and has the following structure to solve the above-mentioned problems. The semiconductor element cooling structure of the present invention has at least a surface contact portion for the semiconductor element between each of the plurality of different semiconductor elements mounted on the printed circuit board and the heat sink, and is integrated with or separate from the heat sink. It is characterized by having a thermally conductive elastic body arranged.

The cooling structure for a semiconductor device according to the present invention comprises the essential components described above. However, this is true even when the constituent elements are specifically as follows. The specific constituent element is characterized in that the heat conductive elastic body has a surface contact portion for each of the semiconductor element and the heat sink.

Further, the cooling structure of the semiconductor device of the present invention comprises:
The heat conductive elastic body is a leaf spring.

The semiconductor element cooling structure of the present invention is characterized in that the contact area of the heat conductive elastic body with the semiconductor element is smaller than the contact area with the heat sink.

The cooling structure for a semiconductor device according to the present invention is characterized in that the heat conductive elastic body is made of a metal. Alternatively, the heat conductive elastic body is made of a resin.

Further, in the semiconductor device cooling structure of the present invention, the heat radiating plate has a contact portion with a printed board,
The semiconductor device has a structure in which the semiconductor element mounted on the printed board is held on the printed board by the surface contact between the contact portion and the semiconductor element of the heat conductive elastic body.

In the cooling structure for a semiconductor device according to the present invention, the heat radiating plate has a contact portion with the printed circuit board, and the contact portion and the surface contact portion of the semiconductor element of the heat conductive elastic body allow the printed circuit board to be connected to the printed circuit board. The semiconductor device has a structure in which the mounted semiconductor element is held on a printed circuit board.

The semiconductor device cooling structure according to the present invention has a holding hole in the printed board or / and the semiconductor element at a position corresponding to the contact portion of the heat sink to the printed board and the surface contact portion to the semiconductor device. It is characterized by becoming.

According to the cooling structure of the semiconductor device of the present invention thus constituted, each semiconductor element and the heat sink are thermally connected to the gap between each semiconductor element mounted on the printed circuit board and the heat sink. A thermally conductive elastic body to be connected is provided. The thermally conductive elastic body has at least a surface contact portion with respect to the semiconductor element, or additionally has a surface contact portion with the heat sink. More specifically, the heat conductive elastic body has a leaf spring shape. The heat conductive elastic body having elasticity is made of a metal or a heat conductive resin having high heat conductivity and elasticity. However, these metals or resins need to have sufficiently higher thermal conductivity than thermal grease. The heat conductive elastic body having the spring property is brought into close contact between each semiconductor element and the heat radiating plate, so that the thermal connection between them is ensured.

Each of the heat conductive elastic members is integrated with the heat sink or separate from the heat sink. When they are integrated, the heat radiating plate and each thermally conductive elastic body are fixed by means of high thermal conductivity and are thermally connected. For example, fixed connection by welding, screwing with a screw made of a metal having high heat conductivity, or press-fitting to a heat radiating plate when the heat conductive elastic body is made of a highly ductile member may be considered.

As another integration means, it is conceivable to provide the heat conductive elastic body with the heat radiating function of the heat radiating plate. That is, the heat conductive elastic body can be used as the heat radiating plate without providing the heat radiating plate. This is effective when the heat generation amount of the semiconductor element is not so large, and the heat conductive elastic body has a large surface area and is made of a member that easily radiates heat.

By thermally connecting each semiconductor element to the heat radiating plate by using a thermally conductive elastic body having high thermal conductivity,
Compared to the case where thermal connection is made using thermal grease,
The heat generated from the semiconductor element can be well conducted to the heat radiating plate. At the same time, since the heat conductivity of the heat conductive elastic body is high, the heat dissipation mechanism does not become complicated due to the difference in the gap distance between each semiconductor element and the heat dissipation plate. At this time, the contact area of the heat conductive elastic body with the semiconductor element is
By making the contact area with the heat sink large, heat conduction can be further satisfactorily performed.

Further, since the connection is performed by closely adhering a heat conductive elastic body having a spring property to each semiconductor element, it is assumed that there is a difference in gap distance between the semiconductor element and the heat sink caused by a difference in thickness of each semiconductor element. Also, due to the elasticity of the thermally conductive elastic body,
The difference in the gap distance can be neglected, and the connection between each semiconductor element and the heat sink is all well connected. The heat conductive elastic body having elasticity also has an effect of absorbing excessive external stress applied to the semiconductor element. Even if the semiconductor element has a mounting inclination, the inclination of the semiconductor element can be absorbed by the elasticity of the heat conductive elastic body, the surface contact portion between the heat sink and the semiconductor element is secured, and the thermal connection is made reliably. You.

The leaf spring used as the heat conductive elastic body does not need to have a complicated structure. Further, the same device can be used within a possible range, and since it is not necessary to prepare for each semiconductor element, the manufacturing cost of the leaf spring does not increase.

As described above, the thermal connection between the heat radiating plate and each semiconductor element is made only through the heat conductive elastic body made of metal or resin having high thermal conductivity. And a heat radiation effect approximately equal to that in the case where the contact is made directly. In addition, when a leaf spring having a particularly simple structure is used as the heat conductive elastic body, the heat conduction mechanism and the heat radiation mechanism are simplified, and the heat radiation effect is enhanced. this is,
This means that the heat dissipation mechanism does not become complicated, which occurs in the case of the conventional technique using an elastic body such as a coil (winding) spring as a part of the heat conducting member. Further, by using a leaf spring having an extremely large area in contact with each semiconductor element and the heat radiating plate, the effect of heat conduction and heat radiation is further enhanced.

By using the technique of the present invention, it is possible to improve the reliability of a semiconductor element and a device using the same. In addition, the overall structural design including the heat sink is simplified, and productivity and maintainability are improved.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a cooling structure for a semiconductor device according to the present invention will be described below. FIG. 4A is an external view of an example of a leaf spring serving as a heat conductive elastic body which is a main part of the present invention. The leaf spring 5 is made of a member having good heat conductivity and high elasticity, particularly a metal or resin. The semiconductor element contact portion 8 that makes surface contact with the semiconductor element of the leaf spring 5 and the heat sink contact portion 9 that makes surface contact with the heat sink are made substantially parallel to each other. FIGS. 4B to 4G are cross-sectional views of other examples of the leaf spring serving as the heat conductive elastic body. In this case, as the heat conductive elastic body, two same leaf springs are used as one set. The shape of the leaf spring can be arbitrarily selected. A closed shape like the one shown in FIG. 4 (g) can also be used. Flat portions existing above and below each leaf spring in the drawing are a heat sink contact portion and a semiconductor element contact portion, respectively. The ones shown in FIGS. 4B to 4G are merely examples, and various shapes can be considered.

FIG. 5 is a cross-sectional view of a cooling structure of a semiconductor device when the leaf spring 5 shown in FIG. 4A is used as a heat conductive elastic body. FIG. 5A shows the difference between the distance between the semiconductor element contact portion 8 and the heat radiating plate contact portion 9 when no displacement is applied to the leaf spring 5 which is a thermally conductive elastic body. It is almost the same as the gap distance with the heat sink 4 (however,
(A difference in the gap distance between the semiconductor element 3 and the heat sink 4 is slightly small). A semiconductor element 3 is mounted on a printed circuit board 1 by a flip chip bonding portion 2, and a radiator plate 4 is arranged above the semiconductor element 3 with a certain gap therebetween in a substantially parallel manner. A leaf spring 5 is arranged in a gap between the semiconductor element 3 and the heat sink 4. The electrical connection between the printed circuit board 1 and the semiconductor element 3 is as follows.
This is performed by the solder balls 6. Although the leaf spring 5 is not substantially displaced, the difference between the semiconductor element contact portion 8 and the heat sink contact portion 9 of the leaf spring 5 is slightly smaller than the gap. As a result, the respective contact portions come into close contact with each other, and the semiconductor element 3 and the heat sink 4 are thermally connected well.

On the other hand, FIG. 5B shows that the gap distance between the semiconductor element 3 ′ and the radiator plate 4 is different from that of the semiconductor element 3 in a state where the leaf spring 5, which is a heat conductive elastic body, is not displaced. The case where the difference is smaller than the difference between the distance between the portion 8 and the heat radiating plate contact portion 9 is shown. As an example of this case, the thickness of the semiconductor element 3 ′ is
A case where the thickness is larger than that of the semiconductor element 3 shown in FIG. Since the gap distance is smaller than the difference between the semiconductor element contact portion 8 and the heat radiating plate contact portion 9 of the leaf spring 5, the leaf spring 5
Are curved as shown in the figure and come into close contact with a strong repulsive force. However, due to the elasticity of the leaf spring 5, excessive external stress is absorbed by the leaf spring 5 and is not applied to the semiconductor element 3 '.

Therefore, the reliability of the semiconductor device is not reduced due to the external stress applied to the semiconductor device. Also in the case of this example, since a metal leaf spring 5 having high thermal conductivity is closely connected to the gap between the semiconductor element and the heat sink, a good heat conduction path is formed. In addition, even in the case where the semiconductor element is inclined to be mounted, the elasticity of the leaf spring 5 which is a heat conductive elastic body absorbs the inclination and forms a heat conduction path between the heat sink and the semiconductor element. Can be.

FIG. 4A shows the shape of the leaf spring if the heat sink and the semiconductor element are in good contact with each other and heat conduction is ensured.
The shape is not limited to those shown in FIGS.

The leaf spring can be fixed to the heat radiating plate in advance by means of high thermal conductivity such as welding or screwing, or by crimping. In this case, a leaf spring is fixed and integrated at a predetermined position of the heat sink corresponding to the position of the semiconductor element on the printed circuit board. Thereby, the assemblability when arranging each leaf spring is improved.

The semiconductor device cooling structure of the present invention can be used for cooling an exposed device such as a bare chip. Further, the present invention can be applied to cooling of a semiconductor element mounted by a method other than flip chip bonding.

[0039]

【Example】

(Embodiment 1) An embodiment of a semiconductor device cooling structure according to the present invention will be described below. FIG. 1 is a sectional view for explaining one embodiment of a cooling structure for a semiconductor device of the present invention. In the present embodiment, a semiconductor element mounted by flip chip bonding will be described. Note that the present invention can be applied to cooling other than the semiconductor element mounted by flip chip bonding. A semiconductor element 3 is mounted on a printed board 1 by a flip chip bonding unit 2. On the upper part of the semiconductor element 3, a heat sink 4 is disposed substantially in parallel with a certain gap. A leaf spring 5 is provided in a gap between the semiconductor element 3 and the heat radiating plate 4 and is thermally connected. The electrical connection between the printed board 1 and the semiconductor element 3 is made by solder balls 6. This electrical connection is made not only by solder but also by other metals such as gold. Further, the shape of the metal for electrical connection is not limited to the ball shape as shown. The shape of the leaf spring 5 is the same as that shown in FIG. In addition, the leaf spring 5 may be connected and fixed to the heat sink 4 in advance by a method having high thermal conductivity such as welding and integrated.

The contact between the semiconductor element contact portion of the leaf spring 5 and the semiconductor element 3 is brought into close contact by the repulsive force of the leaf spring 5. As a result, a heat conduction path from the upper surface of the semiconductor element 3 to the heat sink 4 via the leaf spring 5 is formed. The heat generated from the semiconductor element 3 is conducted through the leaf spring 5 and then radiated from the heat sink 4. By dissipating heat in this way, the semiconductor element 3 is cooled.

(Embodiment 2) FIG. 2 is a sectional view for explaining another embodiment of the cooling structure of the semiconductor device. In the present embodiment, unlike the first embodiment, a heat sink is not particularly provided, and the plate spring 5 'which is a heat conductive elastic body also plays a role of a heat sink. This can be said that the heat radiating plate and the plate spring 5 'which is a heat conductive elastic body are integrated. Also in this embodiment, a semiconductor element mounted by flip chip bonding as in the first embodiment will be described. As shown in FIG. 2A, the leaf spring 5 'is formed so as to surround the printed circuit board 1 and the semiconductor element 3 mounted thereon by the flip chip bonding section 2. The electrical connection between the printed circuit board 1 and the semiconductor element 3 is made by solder balls 6
It is done by. This electrical connection is made not only by solder but also by other metals such as gold. Further, the shape of the metal for electrical connection is not limited to the ball shape as shown.

The leaf spring 5 ′, which also has a heat radiation function, satisfactorily holds the semiconductor element mounted on the printed board by the contact part with the printed board 1 and the contact part with the semiconductor element 3. That is, the leaf spring 5 'formed so as to surround the printed circuit board 1 exerts a force for causing the semiconductor element 3 to approach the printed circuit board 1 and the printed circuit board 1 to approach the semiconductor element 3 respectively. In this case, it can be said that the semiconductor element 3 elastically supports the leaf spring 5 'as a heat radiating plate.

Although the width of the leaf spring 5 'itself varies depending on the size of the semiconductor element 3, it is about several mm, and the surface area of the whole leaf spring 5' is sufficient for the heat generated from the semiconductor element 3 by the leaf spring 5 '. Large enough to dissipate. With the leaf spring 5 'having such a shape, the leaf spring 5', which is a thermally conductive elastic body, also has a heat radiation function, and it is not necessary to particularly provide a heat radiation plate. This is applicable when the amount of heat generated from each semiconductor element and the entire multi-chip module is relatively small. When such a heat conductive elastic body having a heat dissipation function is not provided, the surface area capable of dissipating heat is equal to the surface area of the semiconductor element, and the heat dissipation effect is low. On the other hand, when a heat conductive elastic body having a heat function as in the present embodiment is provided, the surface area capable of dissipating heat is dramatically increased, so that the heat dissipating efficiency is extremely high.

Further, the end of the leaf spring 5 'is hooked on the lower surface of the printed board 1, and the semiconductor element 3 is pressed in the direction of the printed board 1 by the repulsive force of the leaf spring 5'. This is because the heat generated by the semiconductor element 3 is sufficiently conducted to the entire leaf spring 5 ′ by making sufficient contact at the portion of the leaf spring 5 ′ which is in contact with the surface of the semiconductor element 3, and the heat is efficiently radiated. That's why. Further, the leaf spring 5 'can be fixed in contact with the semiconductor element 3 without using a screw or the like, so that productivity and maintainability are high.

FIG. 2B shows an example in which the printed board 1 and the semiconductor element 3 have the holding holes 7. This holding hole 7
Are provided on the printed circuit board and the semiconductor element at positions corresponding to a contact portion of the plate spring 5 'as a heat radiating plate with the printed circuit board and a surface contact portion with the semiconductor element. At this time, a depression corresponding to the holding hole 7 is provided in the leaf spring 5 'as necessary. Due to the presence of the holding holes 7, the recesses or bent portions that are compatible with the holding holes 7 provided in the leaf spring 5 'are simply fitted and attached, and the leaf spring 5' holds the printed circuit board 1 and the semiconductor element 3 well. And it is hard to come off. In addition, the positioning when performing the attaching work of the leaf spring 5 ′ is facilitated,
The work time for attaching the leaf spring during the manufacturing process can be reduced.
This means is difficult to provide the holding hole 7 when the semiconductor element 3 is a bare chip, but is effective for a semiconductor element molded with resin or the like. Also,
It is also possible to provide the holding hole 7 in either the printed circuit board 1 or the semiconductor element 3.

(Embodiment 3) FIG. 3 is an external view for explaining still another embodiment of the cooling structure of the semiconductor device.
In the second embodiment shown in FIG. 2, a leaf spring 5 ′ is provided for each semiconductor element 3. In this embodiment, as shown in FIG. 3A, the radiator plate is processed by a press or the like, and a plate spring portion is formed in a part of the radiator plate. A leaf spring portion 5 ″ is formed by pressing or the like on a part of a heat radiating plate 4 ′ made of a member such as metal or resin having high thermal conductivity. The leaf spring portion 5 ″ has a surface that elastically contacts the semiconductor element. . The leaf spring portion 5 ″ is positioned at a corresponding position such that when the heat sink 4 is mounted on a semiconductor element mounted on a printed circuit board, the semiconductor element and the semiconductor element contact portion of the leaf spring portion 5 ″ come into surface contact. In advance.

In FIG. 3B, as in the second embodiment shown in FIG. 2, the heat radiating plate 4 'is formed so as to surround the printed circuit board. The radiator plate 4 'formed so as to surround the printed board exerts a force for bringing the semiconductor element and the printed board close to each other. The heat radiating plate 4 'satisfactorily holds the semiconductor element mounted on the printed circuit board by the holding section contacting the printed circuit board and the holding section contacting the semiconductor element. In this way, by integrating the heat sink 4 'and the leaf spring portion 5 ", the assemblability is improved.

[0048]

As described above, the present invention has the following excellent effects. In a multi-chip module equipped with a plurality of different semiconductor elements, the connection to the heat sink is made individually using a thermally conductive elastic body with high thermal conductivity, so that the thermal connection using thermal grease Compared with this, heat conduction can be performed better, and effective cooling of the semiconductor element can be realized.

Further, even if there is a difference in the gap distance from the heat sink caused by the difference in the thickness of each semiconductor element, the difference in the gap distance can be ignored by the elasticity of the heat conductive elastic body. The thermally conductive elastic body having elasticity absorbs excessive external stress applied to the semiconductor element, and does not exert any adverse effect on the semiconductor element due to the excessive external stress.

Further, since the structure of the leaf spring used as the heat conductive elastic body is simple, the heat radiation mechanism does not become complicated, and the heat radiation effect is enhanced. By using a leaf spring having a simple structure, the reliability of semiconductor elements and devices using them is improved, and the overall structural design including a heat sink is simplified, so that productivity and maintainability are better. It will be.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a cooling structure for a semiconductor device of the present invention.

FIG. 2 is a sectional view showing another embodiment of the cooling structure of the semiconductor element of the present invention.

FIG. 3 is an external view showing still another embodiment of the semiconductor device cooling structure of the present invention.

FIG. 4 is a diagram showing an appearance of an example of a leaf spring.

5 is a diagram showing a cross section of a cooling structure of a semiconductor element when the leaf spring shown in FIG. 3 is used as a heat conductive elastic body.

FIG. 6 is a diagram showing a cross section of a conventional cooling structure for a semiconductor device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printed board 2 Flip chip bonding part 3, 3 'Semiconductor element 4, 4' Heat sink 5, 5 'Leaf spring 5 "Leaf spring part 6 Solder ball 7 Holding hole 8 Semiconductor element contact part 9 Heat sink contact part 11 Printed circuit board 12 Flip chip bonding part 13 Semiconductor element 14 Heat sink 15 Thermal grease 16 Solder ball

Claims (9)

[Claims] 1. A heat conduction device having at least a surface contact portion with respect to a semiconductor element between each of a plurality of different semiconductor elements mounted on a printed circuit board and a heat sink, and disposed integrally with or separate from the heat sink. A cooling structure for a semiconductor element, characterized by having an elastic body. 2. The cooling structure for a semiconductor device according to claim 1, wherein the heat conductive elastic body has a surface contact portion for each of the semiconductor device and the heat sink. 3. The heat conductive elastic body is a leaf spring.
Or a cooling structure for a semiconductor element according to claim 2. 4. The cooling structure for a semiconductor element according to claim 2, wherein a contact area of the heat conductive elastic body with the semiconductor element is smaller than a contact area with the heat sink. 5. The heat conductive elastic body is made of a metal.
A cooling structure for a semiconductor device according to claim 4. 6. The heat conductive elastic body is made of a resin.
A cooling structure for a semiconductor device according to claim 4. 7. A heat conductive elastic body integral with a heat radiating plate has a surface contact portion elastically contacting a semiconductor element.
4. A cooling structure for a semiconductor device according to claim 1. 8. A heat radiating plate has a contact portion with a printed circuit board, and a semiconductor element mounted on the printed circuit board is connected to the printed circuit board by a surface contact portion between the contact portion and the semiconductor element of the heat conductive elastic body. The cooling structure for a semiconductor element according to claim 7, wherein the cooling structure has a structure held against the semiconductor element. 9. The printed circuit board and / or the semiconductor element at a position corresponding to a contact portion of the heat sink to the printed circuit board and a surface contact portion to the semiconductor element, wherein a holding hole is provided. A cooling structure for a semiconductor device as described in the above.