JP4458872B2 - heatsink - Google Patents

Description

  The present invention relates to a heat sink.

  In a semiconductor device (for example, a semiconductor power module) that generates a large amount of heat during operation, a heat sink is used to release heat generated in a heating element (for example, IBGT). The heat sink usually includes a base on which a heating element is placed and a plurality of fins supported by the base. The fins are disposed in the refrigerant flow path, and thereby transmit heat generated by the heat generator to the refrigerant via the base and the fins.

As such a heat sink, for example, Patent Document 1 discloses a material in which a porous material is used as a fin and a coolant is allowed to flow through a plurality of holes penetrating the fin.
JP 2001-358270 A

  However, in the above conventional configuration, it is necessary to join a plurality of fins to the wall surface (support base) forming the coolant channel one by one with, for example, adhesive, brazing, solder, etc. Costs increased and productivity declined.

  Therefore, an object of the present invention is to provide a heat sink with high productivity.

In order to achieve the above object, one aspect of the heat sink according to the present invention is:
A base having a first surface thermally connected to the heating element;
A plurality of fins supported by a second surface opposite to the first surface of the base and arranged along a predetermined direction, each having a plurality of through holes;
With
The base and the plurality of fins are integrally formed of a porous material.

  According to the present invention, it is not necessary to join a plurality of fins to the base one by one, and therefore the manufacturing time and manufacturing cost of the heat sink can be reduced, and as a result, the productivity can be improved.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In the following description, the same or similar components are represented by the same reference numerals or the same reference numerals with appropriate subscripts throughout the drawings.

Embodiment 1 FIG.
1A to 1C show a first embodiment of a heat sink according to the present invention. The heat sink 2 has a plate-like base 4 having a flat surface (first surface) 4a on which a heating element (not shown) is placed (thermally connected to the heating element), and is spaced parallel to each other. A plurality of (four in the example shown in the figure) plate-like fins 6 (6a) supported by the base 4 via a flat surface (second surface) 4b opposite to the flat surface 4a. , 6b, 6c, 6d). In the following description, it is assumed that the base 4 is positioned parallel to the XY plane, the arrangement direction of the fins 6a to 6d is the Y direction, and each fin 6 is positioned parallel to the XZ plane.

  Each fin 6 is a lotus type member having a large number of tubular through holes 8 extending substantially in the Y direction. During the operation of the heat sink 2, the refrigerant flows in the + Y direction through the through holes 8 in the order of the fins 6a, 6b, 6c, 6d. As the refrigerant, for example, a liquid such as cooling water or a gas such as cold air or chlorofluorocarbon is used. In order to prevent the leakage of the refrigerant, usually, piping is provided upstream and downstream of the heat sink 2 with respect to the flow direction of the refrigerant, and a plate for sealing the upper portion and the side portion of the fin 6 is provided so that the refrigerant flows. However, in the case of the air cooling type, it is possible to expose the fins 6 to the atmosphere instead of flowing cold air into the pipe.

  The base 4 and the fin 6 of the heat sink 2 are one or more parallel to the XZ plane with respect to a rectangular parallelepiped porous member 10 [FIG. 1 (d)] made of a metal such as copper or aluminum (in the example shown in the figure). The three grooves 11 (11a, 11b, 11c) are integrally formed by cutting. As apparent from the above description, the flat surface 4 b of the base 4 partially forms the bottom surface of the groove 11 (the appearance of the heat sink 2) and partially forms a virtual boundary with the fin 6. To do.

  Hereinafter, a method of forming the heat sink 2 will be described with reference to FIGS.

  First, a metal having a large number of tubular through-holes is formed using a known method (in this application, referred to as a metal coagulation method, and details are disclosed in, for example, JP-A-10-88254). . FIG. 2 shows a casting apparatus for forming such a porous metal. The casting apparatus 12 includes a crucible 14 for accommodating a metal lump. A coil 16 for heating the crucible 14 is wound around the outer periphery of the crucible 14, and a metal in the crucible 14 is melted by applying a high-frequency current to the coil 16. A mold 20 having a cooling part 18 at the bottom is disposed below the crucible 14, and a molten metal can be poured into the mold 20 through an on-off valve 22 attached to the lower end of the crucible 14. It has become.

  The crucible 14 and the mold 20 are disposed in a closed container (not shown), and the container is filled with a gas maintained at a predetermined pressure. This gas is a metal and a metal-gas phase diagram having an eutectic point in an isobaric gas atmosphere. For example, if the metal is copper or aluminum, hydrogen, nitrogen or the like is selected as the gas. In the metal solidification method, if the temperature is higher than the temperature at the eutectic point, the gas atoms dissolve into the metal in the liquid state, and if the temperature is lower than the temperature at the eutectic point, the gas atoms are converted into the solid state metal. Take advantage of the fact that it does not melt and exists as a gas.

  In such a casting apparatus 12, first, the sealed container is placed in an isobaric gas atmosphere, and a lump of metal 24 is loaded into the crucible 14 [FIG. 3 (a)]. By applying a high-frequency current to the coil 16 with the on-off valve 22 closed, the lump of metal 24 in the crucible 14 is melted. As a result, the gas is absorbed by the molten metal in an amount corresponding to its concentration and pressure. Next, the on-off valve 22 is opened and the molten metal 26 is poured into the mold 20 [FIG. 3 (b)]. Since the cooling unit 18 is provided at the bottom of the mold 20, a temperature gradient is formed upward from the bottom of the mold 20. As a result, the metal solidifies from the bottom of the mold 20 upward. In the process of solidification of the molten metal, a eutectic reaction occurs in which the gas atom is separated from the molten metal into a solid state metal and a gaseous state gas. Since the holes which are gas passages grow upward from the bottom of the mold 20, a porous metal (porous material) 30 having a tubular hole 28 formed therein is obtained [FIG. 3 (c)]. Even if silicon, which is a semiconductor, is used instead of metal, a porous material can be obtained by the metal solidification method described above. In this case, the following process is applied to a porous material made of silicon.

  Subsequently, the porous metal 30 obtained by the metal solidification method is formed into a rectangular parallelepiped using, for example, an end mill to complete the porous member 10 [FIG. 1 (d)]. Then, a groove is formed in the porous member 10 by, for example, discharge wire processing. Specifically, referring to FIG. 1 (d), the virtual region 32a corresponding to the groove 11a to be formed is intersected with the porous member 10 (this intersects with the extending direction of the hole 8 at an angle of about 90 °. A discharge wire (not shown) extending in the X direction is disposed above. Then, the discharge wire is moved in the −Z direction to reach the position on the upper side from the lower surface (corresponding to the flat surface 4a) by the thickness of the base 4 for the heat sink 2. Thereafter, the groove 11a is formed by pulling up in the + Z direction. The thickness of the groove 11a (the length in the Y direction) is at least the wire diameter of the wire. By repeating the above operation in the remaining two virtual regions 32b and 32c to form the grooves 11b and 11c, the heat sink 2 in which the lot type fins 6a to 6d are formed is obtained (note that the properties of the metal solidification method) In addition, not only the through-hole 8 but also a hole that does not penetrate is formed in the fin 6 [see FIG. 1C], and the cross-sectional shape of the through-hole is not limited to a circle.

  In general, the cooling capacity of the porous member is higher as the contact area (heat transfer area) S between the hole and the refrigerant and the heat transfer coefficient h from the inner surface of the hole to the refrigerant are higher. Also for the fins 6 used in this embodiment, in order to improve the cooling capacity, the number of holes 8 is increased to increase S, or the diameter of the holes 8 is decreased to increase the flow rate of the refrigerant passing through the holes. It is conceivable to increase h by It has been confirmed by the present applicant that the pore diameter is in the range of several tens of μm to several mm and the porosity can be arbitrarily set by the metal solidification method.

  A configuration using a foam material (for example, foam metal such as foam aluminum) in which the through hole is not tubular is also included in the scope of the present invention as the porous member. However, when the lotus-type porous member 10 and thus the lotus-type fins 6 are used, the refrigerant flowing through the adjacent holes does not merge or the refrigerant flowing through a certain hole does not diverge. It is preferable in that a heat sink having no loss and low pressure loss as a whole can be provided.

  As described above, in this embodiment, since the base 4 and the fins 6 are formed by cutting the grooves 11 in the porous member 10, unlike the conventional configuration described above, the base and the plurality of fins are combined. The process of joining each one becomes unnecessary, and as a result, productivity can be improved.

  Note that a heat sink having one groove and thus two fins is also included in the scope of the present invention. Further, the shape of each fin, the shape of the base (including the shapes of the first and second surfaces 4a and 4b), and the method of cutting the groove do not limit the present invention.

  4A and 4B show another method for cutting out the porous member to obtain the heat sink according to the present embodiment. In this method, a rectangular parallelepiped porous member 10 'formed in the same manner as described above is prepared. Then, the discharge wires are moved relative to the porous member 10 ′ along the virtual surface 34 of the porous member 10 ′, thereby producing substantially the same heat sinks 2 ′, 2 ″. Unlike the above-described cutting method, the diameter is sufficiently smaller than the width of the groove to be formed (length in the Y direction), specifically, from one side in the Y direction, from the upper side to the base 4 ′ for the heat sink 2 ′. The discharge wire is applied to the position below the thickness by 1) and moved by a predetermined distance in the + Y direction. 2) The discharge wire is moved in the −Z direction by the thickness of the base 4 ″ for the heat sink 2 ″ from the lower surface. Next, the discharge wire is moved in the + Y direction by the width of the groove, and 3) the discharge wire is moved in the + Z direction by the thickness of the base 4 ′ for the heat sink 2 ′. From the bottom After repeating the operation two more times .1) to 3) to reach the location, by moving the discharge wire in the + Y direction, 'the heat sink 2 from the' porous member 10, 2 "is obtained.

  According to this cutting method, two heat sinks can be formed at the same time. Therefore, productivity is further improved as compared with the above-described method of cutting the groove.

Embodiment 2. FIG.
FIG. 5 shows a second embodiment of the heat sink according to the present invention. In the heat sink 2A according to the present embodiment, a plate (second base) 40 having better thermal conductivity is joined to the first surface 4a opposite to the side of the base 4 that supports the fins 6. The heating element is placed on the base 40 (the first surface 4a of the base 4 is thermally connected to the heating element).

  When the porous member that is the basis of the heat sink 2A is manufactured, the hole 8 may not be tubular, and the refrigerant passage and the first surface 4a of the base 4 may communicate with each other through the hole 8. In this case, when the heat generating element is placed on the first surface 4a of the base 4 and the heat sink is operated, the refrigerant leaks from the first surface 4a. Therefore, in this embodiment, the sealing performance of the heat sink 2A can be ensured by providing the base 40. As a result, the yield of the porous member is improved.

Embodiment 3 FIG.
FIG. 6 shows a third embodiment of the heat sink according to the present invention. In the heat sink 2B according to the present embodiment, the through holes 8B of the fins 6B are not parallel to the Y direction (arrangement direction of the fins 6B) but extend obliquely. Therefore, fin 6B has a larger heat transfer area S than fin 6 of the first embodiment having the same thickness, and as a result, the cooling capacity of heat sink 2B can be improved.

  The fin 6B of the heat sink 2B is a virtual region that is not substantially perpendicular to the direction of expansion of the tubular hole with respect to the porous member (a virtual region parallel to the XZ plane that forms an angle of about 90 ° or less (acute angle) with the expansion direction). ) Along the groove).

Embodiment 4 FIG.
FIGS. 7A and 7B show a heat sink according to a fourth embodiment of the present invention. In the said embodiment, the groove | channel was formed so that the part for the thickness of a base may be left from a porous member, Therefore, fins were connected via the base. On the other hand, in the heat sink 2C according to the present embodiment, the through groove 41 extending from the upper surface in the Z direction to the lower surface of the porous member 10 is formed, and the plurality of fins 6C are formed by the side walls 42 formed on one side surface in the X direction. It is supported. That is, the fin 6C and the side wall 42 are integrally formed of a porous material. A plate (base) 40 having good thermal conductivity is joined to the lower surface of the fin 6C in the Z direction. The heating element is placed on the base 40. During the operation of the heat sink 2C, the base 40 also functions as a seal for preventing the refrigerant from leaking when the refrigerant passage and the lower surface of the fin 6C are communicated with each other through the hole 8. Further, since the side wall 42 also functions as a wall constituting the refrigerant flow path, there is an advantage that the labor required for manufacturing the piping can be saved when the cooling device including the heat sink 2C is manufactured.

  The manufacturing method of the heat sink 2C is the same as the manufacturing method of the heat sink 2 of FIG. That is, with respect to the rectangular parallelepiped porous member 10, the discharge wire extending in the Z direction is disposed on the left side in the X direction of the virtual region 32C corresponding to the groove to be formed. Then, the discharge wire is moved in the + X direction to reach the position on the left side from the right surface in the X direction by the thickness of the side wall 42 for the heat sink 2C. Then, one through groove 41 is formed by moving in the −X direction. The porous member 10 is joined to the base 40 after forming a plurality of through grooves.

  The arrangement direction of the fins 6C may be substantially parallel to the extension direction of the tubular through-hole 8 as in the first embodiment, and forms an acute angle with the extension direction as in the third embodiment. You may do it. In the latter case, the heat transfer area S of the through hole and the refrigerant is increased, and the cooling capacity of the heat sink 2C can be improved.

  In the present embodiment, the plurality of fins 6C are connected via the side wall 42 (in other words, the plurality of fins 6C are supported by the side wall 42 via the side surface adjacent to the joint surface with the base 40). Therefore, since the plurality of fins 6C can be joined to the base 40 at a time, productivity can be improved.

  The case where the fins 6C and the side walls 42 are attached to the piping constituting the cooling flow path, and the wall of the piping constitutes the base 40 (a heating element is placed on the wall of the piping) is also included in the scope of the present invention. It is. This configuration also has the above effect according to the present embodiment.

  The side walls need not be provided only on one side (with respect to the X direction), and the side walls 42R and 42L may be provided on both sides as in the heat sink 2D of FIG. The through groove 41D separating the adjacent fins 6D is formed using, for example, an end mill. Moreover, since the said effect which concerns on this embodiment can be acquired if the adjacent fin is connected at least, a side wall does not need to be provided in the whole side surface (one side regarding X direction). For example, as in the heat sink 2E in FIG. 9A, side walls 42a, 42b, and 42c may be provided alternately on the right and left sides in the X direction (in this case, the through grooves 41E that separate the adjacent fins 6E are formed in a staggered manner. To do.)

  7 and 8, when a side wall that supports all the fins is provided, in addition to the heating element placed on the base 40, another heating element can be placed on the side wall, corresponding to heat generation from the side surface. A heat sink can be provided. In order to ensure the sealing performance of the heat sink, the base may be further bonded to the side wall.

  When the side walls are provided on a part of each side surface as shown in FIG. 9A, if another base 46R, 46L is joined to each side wall as shown in FIG. 9B, the side walls 46R, 46L are placed on the bases 46R, 46L. A heat generating body can be mounted, and therefore a heat sink corresponding to heat generated from the side surface can be provided.

Embodiment 5 FIG.
In the first to third embodiments, adjacent fins are connected via a base, and in the fourth embodiment, adjacent fins are connected via a side wall. You may make it connect adjacent fins via both a base and a side wall. For example, as shown in the heat sink 2F in FIG. 10, grooves 41F that are open to the outside in only one direction may be provided (that is, each groove 41F is bounded by the side walls 42R, 42L, the adjacent fins 6F, and the base 4F). 11, grooves 41G that are open to the outside in only two adjacent directions may be provided (that is, each groove 41G has side walls 42, adjacent fins 6G, and base 4G). To form a boundary.)

(A) The perspective view which shows Embodiment 1 of the heat sink concerning this invention. (B) The top view of the heat sink of Fig.1 (a). (C) Sectional drawing along the Ic-Ic line | wire of FIG.1 (b). (D) The perspective view which shows the porous member used for manufacturing the heat sink of Fig.1 (a). Schematic which shows the casting apparatus for manufacturing the porous metal used as the origin of the porous member of FIG.1 (d). The figure which shows the manufacturing process of the porous metal using the casting apparatus of FIG. (A) The perspective view which shows another porous member. (B) The perspective view which shows the heat sink manufactured using the porous member of Fig.4 (a). The perspective view which shows Embodiment 2 of the heat sink which concerns on this invention. (A) The perspective view which shows Embodiment 3 of the heat sink concerning this invention. (B) The front view of the heat sink of Fig.6 (a). (C) Sectional drawing along the VIc-VIc line | wire of FIG.6 (b). (A) The perspective view which shows Embodiment 4 of the heat sink concerning this invention. (B) The perspective view which shows the porous member used for manufacturing the heat sink of Fig.7 (a). (A) The perspective view which shows another example of Embodiment 4 of the heat sink which concerns on this invention. (B) Sectional drawing along the VIIIb-VIIIb line | wire of Fig.8 (a). (A) The perspective view which shows another example of Embodiment 4 of the heat sink which concerns on this invention. (B) The perspective view which shows the modification of the heat sink of Fig.9 (a). (A) The perspective view which shows Embodiment 5 of the heat sink concerning this invention. (B) Sectional drawing along the Xb-Xb line | wire of Fig.10 (a). (A) The perspective view which shows another example of Embodiment 5 of the heat sink which concerns on this invention. (B) The side view of Fig.11 (a).

Explanation of symbols

2 Heat sink 4 Base 4a Base first surface 4b Base second surface 6a to 6d Fin 10 Porous member

Claims (8)

A base having a first surface thermally connected to the heating element;
A plurality of fins supported by a second surface opposite to the first surface of the base and arranged in a predetermined direction;
The fin has a plurality of tubular through-holes arranged in parallel so that the extending direction intersects the surface facing the arrangement direction of the fins ,
The heat sink, wherein the base and the plurality of fins are integrally formed of a porous material.   The heat sink of claim 1, further comprising a second base joined to the first surface of the base. A base having a first surface thermally connected to the heating element;
A plurality of fins joined to a second surface opposite to the first surface of the base and aligned along a predetermined direction;
A side wall that supports the plurality of fins via side surfaces of the fins adjacent to the joint surface with the base, and
The fin has a plurality of tubular through-holes arranged in parallel so that the extending direction intersects the surface facing the arrangement direction of the fins ,
The heat sink, wherein the side wall and the plurality of fins are integrally formed of a porous material. A plurality of fins joined to an external base thermally connected to the heating element and arranged in a predetermined direction;
A side wall that supports a plurality of fins via a side surface of each fin adjacent to the joint surface with the external base, and
The fin has a plurality of tubular through-holes arranged in parallel so that the extending direction intersects the surface facing the arrangement direction of the fins ,
The heat sink, wherein the side wall and the plurality of fins are integrally formed of a porous material. Prepare a porous member having a predetermined shape,
The base or the side wall and the plurality of fins are formed by machining one or more grooves in the porous member, according to any one of claims 1 to 4. heatsink. The heat sink according to any one of claims 1 to 5, wherein an extension direction of the tubular through hole and an arrangement direction of the fins are parallel to each other.   The heat sink according to any one of claims 1 to 5, wherein an extension direction of the tubular through-hole and an arrangement direction of the fins form an acute angle. The porous member is
A metal-gas phase diagram in an isobaric gas atmosphere is prepared with a metal and a gas having eutectic points, and after melting the metal in the isobaric gas atmosphere, the molten metal has a temperature gradient along a predetermined direction. Solidify in a mold having, and then process the solidified metal into a predetermined shape,
The heat sink according to claim 6 or 7, wherein the heat sink is prepared by:

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