JP2005005519A - Cooling mechanism for semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling mechanism for a semiconductor device which can easily and surely prevent flowing into the screw hole of a pasted thermoconductive material at the time of fixing a cooling mechanism with a screw to a semiconductor device as a heat generating body in order to cool the same. <P>SOLUTION: Screw holes 16a to 16d are formed to the four corners of a fitting surface 14 of a base 12 forming the cooling mechanism 10 for semiconductor device. The screw holes 16a to 16d allow screwing of the screw 60 for fixing the cooling mechanism 10 for semiconductor device to the semiconductor device 40. In the periphery of the screw holes 16a to 16d, grooves 18a to 18d are formed to have the surface of almost L-shape and to have the cross-section of almost U-shape, and are respectively formed to prevent flowing into the screw holes 16a to 16d of an extra heat conducting material 52 when the cooling mechanism 10 for semiconductor device is joined with the semiconductor device 40. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cooling mechanism for a semiconductor device, and more particularly to a cooling mechanism for a semiconductor device that can be suitably provided with a heat conductive material used when a heating element is attached to a heat sink in the semiconductor device. .
[0002]
[Prior art]
In semiconductor devices, in particular, high-speed and highly-integrated CPU (Central Processing Unit), power devices for inverter devices, for example, IGBT (Insulated Gate Bipolar Transistor) and MOSFET (Metal Oxide Semiconductor Field Transistor Effect: The type transistor) has a considerably high temperature during driving. Therefore, in order to avoid destruction or malfunction due to heat, the semiconductor device is cooled using a cooling member.
[0003]
An example of the cooling member is a heat sink. Usually, a heat sink is comprised from a base part and a fin part, and the said base part is attached to the heat spreader etc. which were formed in the semiconductor device. That is, the heat generated in the semiconductor device is released from the fin portion into the air through the heat spreader and the base portion, and the semiconductor device is cooled.
[0004]
By the way, when attaching a heat sink to a semiconductor device, a minute gap is formed at the joint between the two, and the thermal conductivity is lowered by the air present in the gap. As a result, there is a disadvantage that the cooling efficiency by the heat sink is not so high.
[0005]
Therefore, in Patent Document 1, in order to efficiently cool a power conversion device equipped with an IGBT chip that becomes high temperature during driving, the power conversion device is made of a metal plate (heat spreader) made of a copper material and silicon grease (thermally conductive material). ) Is technically held in pressure contact with the cooling fin (heat sink). Silicon grease has a high thermal conductivity and has a viscosity, so that it can flow into the gap and remove the air layer. Therefore, the thermal conductivity between the power converter and the cooling fin can be improved.
[0006]
By the way, in patent document 1, the said power converter device and a heat sink are being fixed with the screw. However, when the heat sink is attached to the power conversion device, the viscous silicone grease may flow into the screw holes. When the silicone grease flows into the screw hole, the coefficient of friction with the screw hole decreases when the screw is screwed in, and it becomes easy to screw and the tightening force increases to cause the screw to break or loosen due to insufficient tightening. And fatigue failure will occur. Therefore, in the case of Patent Document 1, it is necessary to strictly manage the application position and the application amount of silicon grease in order to prevent the silicon grease from flowing into the screw holes, and the work of attaching the heat sink to the power converter is very difficult. It is troublesome and it is difficult to maintain a certain quality.
[0007]
On the other hand, Patent Document 2 discloses a workpiece fixing device in which a groove for accommodating an excess adhesive at the time of joining is formed on the work surface when the work is joined to the work surface.
[0008]
[Patent Document 1]
JP-A-9-8224 (paragraphs [0014] to [0019])
[Patent Document 2]
JP 2002-52430 A (paragraphs [0027] and [0028])
[0009]
[Problems to be solved by the invention]
However, the groove in Patent Document 2 is intended to apply the adhesive to the work surface in a short time, and in a thin and uniform manner, and the specific groove, that is, the fixing screw hole described above. It is not intended to prevent a paste-like composition such as silicon grease or adhesive from flowing into the liquid.
[0010]
The present invention has been made in order to solve the above-described problems, and is intended to cool a semiconductor device as a heating element without strictly managing the application position and application amount of the heat conductive material. It is possible to easily and reliably prevent the paste-like thermally conductive material from flowing into the screw hole when the cooling mechanism is screwed, and as a result, the assembly work of the cooling mechanism to the semiconductor device can be made efficient. An object of the present invention is to provide a semiconductor device cooling mechanism that can be used.
[0011]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a base part attached to a semiconductor device as a heating element via a paste-like heat conductive material, and is formed integrally with the base part, and In a cooling mechanism for a semiconductor device comprising a material and a fin portion that releases heat of the semiconductor device conducted through the base portion into the air,
The base portion is
A mounting surface on which the thermally conductive material is applied between the semiconductor device and the surface opposite to the surface on which the fin portion is formed;
A screw hole for fixing the semiconductor device cooling mechanism to the semiconductor device;
A groove portion that is formed at least around the screw hole and prevents a part of the thermally conductive material from flowing into the screw hole;
(Invention of Claim 1).
[0012]
According to the present invention, when the semiconductor device cooling mechanism is screwed to the semiconductor device, a part of the heat conductive material interposed therebetween is accommodated in the groove formed around the screw hole. Will not flow into the screw hole. That is, it is possible to easily and reliably prevent the heat conductive material from flowing into the screw hole without strictly managing the application position and the application amount of the heat conductive material. As a result, the screw does not break due to excessive tightening, and does not cause loosening or fatigue failure due to insufficient tightening, so that a semiconductor device with excellent quality can be obtained and the semiconductor device cooling mechanism can be assembled to the semiconductor device. Can be made more efficient.
[0013]
In this case, the groove portion includes a first wall portion formed on the screw hole side and substantially perpendicular to the mounting surface, and an inclined second wall formed on the opposite side of the screw hole side. When the semiconductor device cooling mechanism is screwed to the semiconductor device, a part of the thermally conductive material interposed between them is smoothly guided to the groove portion. In addition, the heat conductive material that has flowed into the groove can be suitably prevented from flowing into the screw hole.
[0014]
Furthermore, a protruding portion extending toward the second wall portion along the mounting surface is formed on the upper portion of the first wall portion (the invention according to claim 3), or surrounded by the groove portion on the mounting surface. If the height of the formed region is set higher than the height of the region where the heat conductive material is applied on the mounting surface (the invention according to claim 4), the screw hole of the heat conductive material flowing into the groove is provided. Can be more suitably prevented.
[0015]
Furthermore, if a through-hole is formed in the bottom of the groove portion so as to penetrate the base portion and communicate with the outside from the fin portion side (the invention according to claim 5), the heat conductive material in an amount exceeding the volume is assumed in the groove portion. Even when inflowing, the thermally conductive material that has flowed into the groove portion is discharged to the outside of the fin portion through the through hole, so that it does not overflow from the groove portion and flow into the screw hole. Furthermore, in this case, the through-hole also functions as an air vent hole for venting air generated on the mounting surface when the semiconductor device cooling mechanism is attached to the semiconductor device in close contact. Further, the through hole can contribute to heat exchange with the outside during operation of the semiconductor device.
[0016]
Still further, when the groove portion has a shape surrounding the entire region of the mounting surface to which the thermally conductive material is applied (invention of claim 6), when the semiconductor device cooling mechanism is screwed to the semiconductor device, Part of the thermally conductive material interposed between the two is accommodated in the groove without leaking to the outside of the semiconductor device cooling mechanism. Therefore, in addition to the effects of the inventions according to the first to fifth aspects, the invention according to the sixth aspect has an effect of eliminating work such as wiping off the thermally conductive material leaked to the outside of the semiconductor device cooling mechanism. Play.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
A preferred embodiment of a semiconductor device cooling mechanism according to the present invention will be described below with reference to the accompanying drawings.
[0018]
FIG. 1 shows a semiconductor device cooling mechanism 10 according to a first embodiment of the present invention. The semiconductor device cooling mechanism 10 includes a base portion 12, and a mounting surface 14 to which a semiconductor device 40 described later is attached is formed on the upper surface side of the base portion 12 in FIG. 1. Screw holes 16 a to 16 d into which screws 60 for fixing the semiconductor device cooling mechanism 10 to the semiconductor device 40 are respectively formed at the four corners of the mounting surface 14. Around the screw holes 16a to 16d, groove portions 18a to 18d having a substantially plane L shape (see FIG. 1) and a substantially U-shaped cross section (see FIG. 2) are formed, respectively.
[0019]
In FIG. 1, a comb-like fin portion 20 that is integrally formed with the base portion 12 and releases the heat of the semiconductor device 40 into the air is formed on the lower surface side of the base portion 12.
[0020]
Next, the configuration of the semiconductor device 40 that is a heating element and is a cooling target by the semiconductor device cooling mechanism 10 will be described. As the semiconductor device 40, for example, a device that becomes high temperature when driving a CPU, IGBT, MOSFET or the like can be cited.
[0021]
In FIG. 1, a heat spreader 42 is formed at a substantially central portion on the lower surface side of the semiconductor device 40 so as to face the mounting surface 14. The heat spreader 42 is formed of a metal material having a high thermal conductivity and is thermally connected to the internal circuit of the semiconductor device 40. Through holes 44a to 44d are formed in the rectangular corners of the semiconductor device 40 corresponding to the screw holes 16a to 16d. The screw 60 is inserted into the through holes 44a to 44d.
[0022]
As shown in FIGS. 1 to 3, a paste-like thermally conductive material 50 for increasing thermal conductivity is interposed between the semiconductor device 40 and the semiconductor device cooling mechanism 10. Examples of the heat conductive material 50 include non-curing type heat dissipating grease (for example, silicon grease), or heat dissipating gel that is in a paste state at the time of application and is heat-cured in a subsequent process to become an elastomer. Can be mentioned.
[0023]
Next, a procedure for attaching the semiconductor device cooling mechanism 10 to the semiconductor device 40 configured as described above will be described.
[0024]
First, as shown in FIGS. 1 and 2, an appropriate amount of a heat conductive material 50 is applied to a substantially central portion of the mounting surface 14 of the semiconductor device cooling mechanism 10. Next, the semiconductor device 40 and the semiconductor device cooling mechanism 10 are aligned so that the through holes 44a to 44d of the semiconductor device 40 and the screw holes 16a to 16d of the semiconductor device cooling mechanism 10 are aligned. Then, the screws 60 are respectively screwed into the screw holes 16a to 16d through the through holes 44a to 44d of the semiconductor device 40, and the semiconductor device 40 and the semiconductor device cooling mechanism 10 are joined (state of FIG. 3). .
[0025]
At the time of joining, the thermally conductive material 50 applied to the substantially central portion of the mounting surface 14 is moved from the central portion to the periphery on the mounting surface 14 as the semiconductor device 40 and the semiconductor device cooling mechanism 10 are pressure-bonded. It diffuses (see arrow in FIG. 1). In this case, since the thermal conductive material 50 is applied in a large amount so as to increase the thermal conductivity, an extra thermal conductive material (also referred to as surplus thermal conductive material) 52 is generated at the time of joining (FIG. 3). reference). However, since this surplus heat conductive material 52 is accommodated in each of the grooves 18a to 18d, it does not flow into the screw holes 16a to 16d. That is, it is possible to easily and reliably prevent the surplus heat conductive material 52 from flowing into the screw holes 16a to 16d without strictly managing the application position and the application amount of the heat conductive material 50. As a result, the screw 60 does not break due to overtightening, and neither loosening nor fatigue failure due to insufficient tightening occurs, and a semiconductor device 40 with excellent quality is obtained and the semiconductor device 40 of the semiconductor device cooling mechanism 10 is obtained. Assembling work can be made more efficient.
[0026]
FIG. 4 shows groove portions 70a to 70d as modified examples of the groove portions 18a to 18d shown in FIGS. The groove portions 70a to 70d are characterized by a first wall portion 72 formed on the screw hole 16a to 16d side and substantially perpendicular to the mounting surface 14, and on the opposite side of the screw holes 16a to 16d. And it is in the point comprised from the 2nd wall part 74 inclined. That is, by configuring in this way, the surplus heat conductive material 52 when the semiconductor device cooling mechanism 10 is screwed to the semiconductor device 40 can be smoothly guided to the grooves 70a to 70d, and the grooves 70a to 70d. It is possible to suitably prevent the surplus heat conductive material 52 that has flowed into 70d from flowing into the screw holes 16a to 16d.
[0027]
Furthermore, the groove portions 70a to 70d shown in FIG. 4 may be groove portions 80a to 80d as shown in FIG. The groove portions 80a to 80d are characterized in that a protruding portion 82 that protrudes toward the second wall portion 74 along the mounting surface 14 is formed on the upper portion of the first wall portion 72 that is formed substantially vertically. That is, by comprising in this way, it can prevent further more that the excess heat conductive material 52 which flowed into the groove parts 80a-80d overflows, and flows into screw hole 16a-16d.
[0028]
FIG. 6 shows a semiconductor device cooling mechanism 90 according to a second embodiment of the present invention. The semiconductor device cooling mechanism 90 is characterized in that the region A on the mounting surface 14 outside the grooves 18a to 18d (the region surrounded by the two-dot chain line in FIG. 1) is more than the region B inside the grooves 18a to 18d. The point is to set the height d low. That is, by comprising in this way, the surplus heat conductive material 52 which flowed into groove part 18a-18d can flow in into screw holes 16a-16d more suitably. The height d may be appropriately selected according to the amount of heat conductive material 50 used.
[0029]
In FIG. 6, the configuration of the second embodiment described above is applied to the configuration of the first embodiment shown in FIGS. 1 to 3, that is, the grooves 18 a to 18 d having a substantially U-shaped cross section. However, it goes without saying that the second embodiment can be applied to the groove portions 70a to 70d shown in FIG. 4 or the groove portions 80a to 80d shown in FIG.
[0030]
7 and 8 show a semiconductor device cooling mechanism 100 according to a third embodiment of the present invention. The semiconductor device cooling mechanism 100 is characterized in that a through hole 102 that penetrates the base portion 12 and communicates with the outside is formed in the groove portions 18a to 18d. That is, by configuring in this way, even if the surplus heat conductive material 52 in an amount exceeding the volume flows into the grooves 18a to 18d, the surplus heat conductive material 52 that has flowed into the through holes 102 Since it is discharged to the outside of the fin portion 20 through the groove portion 18a to 18d, it does not overflow and flow into the screw holes 16a to 16d. In this case, the through hole 102 also functions as an air vent hole for venting air generated on the mounting surface 14 when the semiconductor device cooling mechanism 100 is to be closely attached to the semiconductor device 40 and assembled. Further, the through hole 102 can contribute to heat exchange with the outside during the operation of the semiconductor device 40.
[0031]
7 and 8, the configuration of the third embodiment described above is replaced with the configuration of the first embodiment shown in FIGS. 1 to 3, that is, the grooves 18 a to 18 d having a substantially U-shaped cross section. In the third embodiment, the groove portions 70a to 70d shown in FIG. 4, the groove portions 80a to 80d shown in FIG. 5, or the semiconductor device cooling mechanism 90 shown in FIG. Needless to say, the present invention can be applied to the embodiment.
[0032]
A semiconductor device cooling mechanism 110 according to a fourth embodiment of the present invention is shown in FIG. The semiconductor device cooling mechanism 110 is characterized in that the grooves 18a to 18d are not individually provided as in the semiconductor device cooling mechanism 10 of the first embodiment shown in FIGS. The entire region where the conductive material 50 is applied (see FIG. 9) is surrounded by the groove 112. In this case, the depth of the groove 112 may be the same as the grooves 18a to 18d or may be shallower in some cases. With this configuration, even when the heat conductive material 50 is applied to the mounting surface 14 in a large amount, the surplus heat conductive material 52 does not leak to the outside of the semiconductor device cooling mechanism 110. The groove 112 is accommodated. Therefore, the trouble of wiping off the excess heat conductive material 52 leaked to the outside of the semiconductor device cooling mechanism 110 does not occur.
[0033]
In addition, the shape of the groove part 112 of 4th Embodiment demonstrated above can also be made into the groove part shape shown in FIG. 4 or FIG. Furthermore, the fourth embodiment can be used in appropriate combination with the configuration of the second embodiment or the third embodiment.
[0034]
【The invention's effect】
As described above, according to the present invention, when the semiconductor device cooling mechanism is screwed to the semiconductor device, a part of the thermally conductive material interposed therebetween is formed around the screw hole. It is accommodated in the groove and does not flow into the screw hole. That is, it is possible to easily and reliably prevent the heat conductive material from flowing into the screw hole without strictly managing the application position and the application amount of the heat conductive material. As a result, the screw will not break due to excessive tightening, and it will not cause looseness or fatigue failure due to insufficient tightening, and a semiconductor device with excellent quality will be obtained and the semiconductor device cooling mechanism will be assembled to the semiconductor device. Work can be made efficient.
[Brief description of the drawings]
FIG. 1 is a perspective view illustrating a configuration of a cooling mechanism for a semiconductor device according to a first embodiment of the present invention and a bonding relationship between the cooling mechanism for a semiconductor device and a semiconductor device to be cooled.
2 is a longitudinal sectional view taken along the line II-II of the cooling mechanism for a semiconductor device shown in FIG. 1, and shows a state in which a heat conductive material is applied to a substantially central portion of a mounting surface.
3 is a longitudinal sectional view taken along the line II-II of the semiconductor device cooling mechanism shown in FIG. 1, and shows a state in which the semiconductor device cooling mechanism and the semiconductor device are screwed together.
4 is a partial longitudinal sectional view of a cooling mechanism for a semiconductor device, illustrating a structure of a modified example of the groove shown in FIGS. 1 to 3; FIG.
5 is a partial longitudinal sectional view of a cooling mechanism for a semiconductor device, illustrating a structure of a modified example of the groove portion shown in FIG. 4. FIG.
FIG. 6 is a partial vertical cross-sectional view illustrating the main structure of a cooling mechanism for a semiconductor device according to a second embodiment of the present invention.
FIG. 7 is a partial plan view for explaining a main structure of a cooling mechanism for a semiconductor device according to a third embodiment of the present invention.
8 is a longitudinal sectional view taken along line VII-VII of the semiconductor device cooling mechanism shown in FIG. 7;
FIG. 9 is a plan view illustrating the shape of a groove of a semiconductor device cooling mechanism according to a fourth embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10, 90, 100, 110 ... Semiconductor device cooling mechanism 12 ... Base part 14 ... Mounting surface 16a-16d ... Screw hole 18a-18d, 70a-70d, 80a-80d, 112 ... Groove part 20 ... Fin part 40 ... Semiconductor device 42 ... Heat spreader 44a-44d ... Through hole 50 ... Thermally conductive material 52 ... Excess thermal conductive material 60 ... Screw 72 ... First wall part 74 ... Second wall part 82 ... Protruding part 102 ... Through hole

Claims (6)

A base portion attached to a semiconductor device as a heating element via a paste-like heat conductive material, and the semiconductor device formed integrally with the base portion and conducted via the heat conductive material and the base portion In a cooling mechanism for a semiconductor device composed of fins that release heat of air into the air,
The base portion is
A mounting surface on which the thermally conductive material is applied between the semiconductor device and the surface opposite to the surface on which the fin portion is formed;
A screw hole for fixing the semiconductor device cooling mechanism to the semiconductor device;
A groove portion that is formed at least around the screw hole and prevents a part of the thermally conductive material from flowing into the screw hole;
A cooling mechanism for semiconductor devices, comprising: The cooling mechanism for a semiconductor device according to claim 1,
The groove portion includes a first wall portion formed on the screw hole side and substantially perpendicular to the mounting surface, and a second wall portion formed on the side opposite to the screw hole side and inclined. A cooling mechanism for a semiconductor device. The cooling mechanism for a semiconductor device according to claim 2,
A cooling mechanism for a semiconductor device, wherein a protruding portion extending toward the second wall portion along the mounting surface is formed on an upper portion of the first wall portion. In the cooling mechanism for semiconductor devices according to any one of claims 1 to 3,
A cooling mechanism for a semiconductor device, characterized in that a height of a region surrounded by the groove portion on the mounting surface is set higher than a height of a region on the mounting surface to which the heat conductive material is applied. In the cooling mechanism for a semiconductor device according to any one of claims 1 to 4,
A cooling mechanism for a semiconductor device, wherein a through-hole penetrating the base portion and communicating from the fin portion side to the outside is formed at a bottom portion of the groove portion. In the cooling mechanism for a semiconductor device according to any one of claims 1 to 5,
The said groove part surrounds the whole area | region where the said heat conductive material is applied in the said attachment surface, The cooling mechanism for semiconductor devices characterized by the above-mentioned.

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