JP2008198967A - Heat sink, its manufacturing method, and heat sink fan - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a heat sink with high cooling properties for efficiently transmitting heat to heat radiating fins and a fixing method for attaching mounting members to the heat sink with high strength. <P>SOLUTION: A heat sink 1 has a plurality of radially extended heat radiating fins 12 that are continuously annularly arranged on the cylindrical outer side of a cylindrical base part 11. The base part 11 is formed in the shape of a cylinder with a central axis as the center. Moreover, the base part is formed in a solid structure. The heat sink 1 is cut such that a roughly cylindrical cooled object contacting portion 13 projects toward an axial direction from the end surface of the heat sink 1. An annular groove 14 is cut in the contact surface 131 of the cooled object contacting portion 13 along the outer peripheral end. The mounting member 9 is inserted to fit with the outer circumferential surface of the cooled object contacting portion 13, and a pressurizing section 15 is pressurized over the entire circumference by a pressing machine. The pressurizing section 15 is plastically deformed outward in the diameter direction, and the mounting member 9 is pinched and fixed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heat sink cooling device that cools an object to be cooled such as an electronic component including an MPU.

  The MPU (Micro Processing Unit) is a central part of a computer that obtains an output result by performing processing such as computation on received data, and is mounted on a high-performance electronic device. In recent years, MPU clocks have increased significantly, and the MPU itself has been increasing in heat with the increase in clocks. The MPU may malfunction due to heat generation, and the MPU cooling problem becomes extremely important. It is coming. For this reason, heat-generating electronic parts such as MPUs mounted on these high-performance electronic devices include a heat sink composed of a plurality of heat-dissipating fins made of metal and having a surface area as large as possible, and cooling air on the heat sink. A heatsink fan combined with a cooling fan that supplies At that time, the heat sink body is mounted so as to come into contact with the MPU, and the heat sink is forcibly cooled by the cooling air supplied by the cooling fan.

  In addition, in order to improve the cooling characteristics of the heat sink, it is necessary to configure the heat sink so that the transmission loss is reduced in the process of transferring heat from the MPU, which is a heat generation source, to the radiating fin. Therefore, the base (base) of the heat sink is composed of a cylindrical hollow portion having a cavity inside, and a high thermal conductivity body that is fitted in the cavity and arranged to be able to conduct heat to the hollow portion. . Further, it is disclosed that heat radiating fins are formed on the outer peripheral portion of the base portion, and that the high thermal conductivity body is made of copper having higher thermal conductivity than the material of the heat radiating fins and the hollow portion (aluminum). (Patent Document 1).

  When it is going to acquire the high cooling characteristic of a heat sink, the attachment strength of the heat sink with respect to MPU becomes important. As described in detail in the best mode for carrying out the invention, it is necessary to increase the contact pressure at the contact surface between the heat sink and the MPU in order to obtain high cooling characteristics of the heat sink. If the contact pressure is increased, the value of the contact thermal resistance generated between the heat sink and the MPU can be reduced. Thereby, the heat generated by the MPU can be efficiently transmitted to the heat sink. In order to increase the contact pressure between the heat sink and the MPU, the attachment strength when the heat sink is attached to the MPU is important. Generally, the heat sink and the MPU are fixed by an attachment member. That is, it is necessary to fix the mounting member to the heat sink.

  Therefore, a groove is formed on the outer peripheral side surface of the base (core), and the support material is fixed to the heat sink so that the hole formed in the support material (mounting member) is engaged with the groove. Has been disclosed (Patent Document 2). Further, in the case of a conventional heat sink structure, there is a method in which an attachment member is sandwiched and fixed between the heat sink and the core. With the former method (fixing method according to Patent Document 2), high fixing strength cannot be obtained. In addition, the latter fixing method (conventional method) requires a large number of mounting steps. Therefore, there is a demand for a fixing method that requires a small number of production steps and can provide high fixing strength.

JP 2005-327854 A JP 2006-32941 A

  In recent years, the calculation processing speed of the MPU tends to increase, and it is required to improve the cooling efficiency of the heat sink fan mounted on the MPU, and it is necessary to improve the heat transfer efficiency from the MPU to the heat sink.

  In order to improve the cooling efficiency of the heat sink, it is necessary to increase the surface area of the entire heat sink as described above. In order to increase the width, the thickness of the heat dissipating fins may be formed to be as thin as possible, and each heat dissipating fin may be formed to extend radially outward from the base. However. When the radiating fin is thinned, the strength of the heat sink is reduced, so there is a limit to making the radiating fin thin. In addition, when each radiating fin is extended radially outward from the base, the gap between adjacent radiating fins is too narrow near the base of the radiating fin, so that cooling air is generated on the heat sink. When supplied, the cooling air does not pass smoothly between adjacent radiating fins. Therefore, simply increasing the surface area of the heat sink does not improve the cooling efficiency.

  In order to further increase the cooling efficiency of the heat sink, in the configuration disclosed in Patent Document 1, the high thermal conductivity body that is the contact portion between the MPU and the heat sink is formed of a material having a higher thermal conductivity than the radiating fin and the hollow portion. ing. As a result, heat generated in the MPU is efficiently transmitted to the hollow portion, and is transmitted from the hollow portion to the radiation fins and radiated to the atmosphere.

  According to Patent Document 1, it is disclosed that copper is used as the material of the high thermal conductivity body, and aluminum is used as the material of the radiation fin and the hollow portion. Since the specific gravity of copper is higher than that of aluminum, the larger the volume occupied by the high thermal conductivity body, the higher the thermal conductivity and the larger the mass of the heat sink alone. Further, copper is less available than aluminum and its cost as a material is high. Therefore, in consideration of availability and cost, it is desirable to form the heat sink using only aluminum. In the above configuration, man-hours for fitting the high thermal conductivity body into the cavity of the hollow portion are also generated.

  Further, when a high thermal conductivity body is fitted into the cavity of the hollow portion, a contact thermal resistance is generated on the contact surface between the cavity and the high thermal conductivity body. For the same member, the thermal conductivity is determined depending on the physical property value of the member, but when different members are brought into contact with each other, the contact thermal resistance value increases depending on the contact state of the contact surface. This leads to a decrease in thermal conductivity.

  Therefore, in the configuration disclosed in Patent Document 1, availability and production man-hours cannot be reduced. In recent years, there has been a demand for a heat sink having high cooling characteristics, high availability, and a small production man-hour.

  Next, as described in detail in the background art, in order to improve the cooling characteristics of the heat sink, it is necessary to firmly attach the heat sink to the MPU. Therefore, it is necessary to firmly fix the support material (attachment member) to the heat sink. Therefore, Patent Document 2 discloses a method for fixing a support material (attachment member) to a heat sink. Since the fixing method disclosed in Patent Document 2 is fixed only by fitting the protruding portion formed in the opening of the support material and the concave groove, the rotational strength around the central axis of the heat sink is low. Further, depending on the processing accuracy of the groove and the support material, there is a possibility that play may occur between the groove and the support material in the axial direction with the central axis as the axis. That is, the fixing method disclosed in Patent Document 2 cannot obtain high reliability.

  Therefore, the support material (mounting member) is fixed with high fixing strength to the heat sink (especially the heat sink in which radiating fins arranged radially at the base of the solid structure are continuously formed). There is a need for a fixing method.

  The present invention has been made in view of the above prior art. That is, the present invention is to obtain a heat sink having high cooling characteristics in which heat transmitted from the MPU to the base is efficiently transmitted to the radiation fins. Another object is to obtain a fixing method for attaching the attachment member to the heat sink with high strength.

  In order to solve the above problems, the heat sink according to claim 1 of the present invention is a heat sink that cools an object to be cooled such as an electronic component, and has a solid and columnar base formed around the central axis, A plurality of fins extending radially outward from the base about the central axis, wherein the base and the fin are axially having the central axis as an axis. It is characterized in that it is formed continuously by extrusion or drawing.

  The heat sink according to claim 2 of the present invention is the heat sink fan according to claim 1, wherein the base and the plurality of fins are formed by combining a plurality of divided materials obtained by dividing one billet into a plurality of parts. It is formed.

  In the heat sink according to claim 3 of the present invention, the heat sink according to claim 2, wherein the plurality of divided materials are substantially cylindrical central portions that form the central portion of the base portion with the central axis as a center. A plurality of heat dissipating fin part materials constituting a part of the outer part of the base part and part of the heat dissipating fins around the center part material around the center axis, Are arranged in the circumferential direction, and the center material and the plurality of heat dissipating fin materials are formed continuously.

  A heat sink according to a fourth aspect of the present invention is the heat sink according to any one of the first to third aspects, wherein the heat sink has a through-hole at the center and a plurality of mountings radially outward. The leg has a mounting member that extends radially, and an object-to-be-cooled portion that protrudes in the axial direction from the base is formed, and an outer peripheral side surface of the object-to-be-cooled contact portion is formed of the mounting member. It is fitted to the through hole.

  In the heat sink according to claim 5 of the present invention, the heat sink according to claim 4, wherein a plurality of portions plastically deformed radially outward at an outer peripheral end of a contact surface of the object to be cooled contact portion. The attachment member is fixed to the outer peripheral side surface of the object to be cooled contact portion.

  The heat sink according to claim 6 of the present invention is the heat sink according to claim 4, wherein the entire circumference of the outer peripheral end of the contact surface of the object to be cooled is plastically deformed outward in the radial direction. The mounting member is fixed to the outer peripheral side surface of the object to be cooled contact portion.

  A heat sink according to a seventh aspect of the present invention is the heat sink according to any one of the fourth to sixth aspects, wherein at least one notch is formed on an inner peripheral surface of the through hole formed in the attachment member. It is characterized by that.

  A heat sink fan according to an eighth aspect of the present invention is a heat sink fan using the heat sink according to any one of the first to seventh aspects, wherein the heat sink is disposed substantially coaxially with the heat sink and the central axis. A cooling fan that blows a cooling airflow, and the cooling fan includes a plurality of blades that generate an airflow in the axial direction by rotating about the central axis, and The motor unit that rotationally drives the impeller, and a housing that has a wind tunnel that surrounds the impeller from the outside in the radial direction and supports the motor unit.

  In the heat sink manufacturing method according to claim 9 of the present invention, a solid columnar base portion formed around the central axis and radially extending from the base portion radially outward about the central axis. A heat sink manufacturing method comprising: a) a step in which a material billet made of aluminum or aluminum alloy is heated in a furnace; and b) the material billet is pushed into a split mold, A step in which the material billet is divided into a plurality of divided materials; c) the plurality of divided materials are pushed into a heat sink mold, and the long heat sink is moved from the heat sink mold while the divided materials are joined to each other. And d) a step of cutting the long heat sink in the axial direction.

  The heat sink manufacturing method according to claim 10 of the present invention is the heat sink manufacturing method according to claim 9, wherein, in the step b), the material billet forms a central portion of the base portion. It is characterized by being divided into a material and a plurality of heat dissipating fin materials surrounding the circumferential direction of the outer portion of the central material.

  In a heat sink manufacturing method according to an eleventh aspect of the present invention, in the heat sink manufacturing method according to the ninth or tenth aspect of the present invention, e) the central axis is disposed on an axial end surface of one of the cut heat sinks. A step of cutting the heat sink so as to leave a columnar object to be cooled at the center, and f) an attachment having a through hole in the center and a plurality of attachment legs extending radially outward. A step of inserting a member so that an outer peripheral side surface of the object to be cooled contact portion fits into the through hole; and g) pressurizing a plurality of outer peripheral ends or the entire periphery of the contact surface of the object to be cooled contact portion. As a result, a plurality of outer peripheral ends or the entire circumference of the contact surface of the object to be cooled are plastically deformed radially outward, and the mounting member is fixed to the outer peripheral side surface of the object to be cooled. Process , Characterized by having a.

  In the heat sink manufacturing method according to a twelfth aspect of the present invention, the heat sink manufacturing method according to the eleventh aspect of the present invention may be provided at the outer peripheral end of the contact surface of the object to be cooled before the step g). A step of forming a groove along the step, and in the step g), a portion outside the groove of the object contact portion to be cooled is pressurized.

In the heat sink manufacturing method according to a thirteenth aspect of the present invention, the heat sink manufacturing method according to the eleventh aspect, wherein the step (g) is performed before the outer peripheral end of the contact surface of the object to be cooled portion. Along the step of forming a stepped portion that is recessed toward the heat sink side,
In the step g), the stepped portion of the object contact portion to be cooled is pressurized.

  According to the heat sink of claim 1 of the present invention, the radiation fin and the base are continuously formed, and the base is formed in a solid structure. For this reason, since there is no contact surface where the two members come into contact with each other until the MPU is transmitted from the base that contacts the MPU to the radiating fin, no contact thermal resistance is generated inside the heat sink. Therefore, the loss of thermal resistance can be kept to a minimum, and the cooling efficiency of the heat sink can be increased.

  According to the heat sinks according to claims 2 and 3 of the present invention, it is possible to easily perform the extruding (pulling) process of the heat sink, which has been difficult in the past. In general, when performing extrusion (drawing) processing, it is necessary to devise the shape so that the thickness of the extruded processed product is constant. Therefore, the conventional heat sink was formed only by the extrusion (drawing) process of the part on the outer peripheral side of the base part which connects the radiation fin and the radiation fin. The portion on the inner side of the base portion is fitted with a high thermal conductivity body as shown in Patent Document 1. However, by dividing and extruding (pulling) the material into a plurality of materials as in the present invention, it is possible to continuously form the radiating fin and the solid structure base. In particular, by disposing the central portion material in the central portion of the base portion, the difference in thickness between the heat radiating fin and a portion of the base portion can be reduced, and therefore, processing becomes easier.

  Further, in the conventional heat sink processing method, the heat sink is configured by fitting the core into the center of the base. However, in this case, it is necessary to employ a processing method called shrink fitting in order to fit the core to the center of the base. Shrink fitting is a method of heating a heat sink (in which the core is not fitted and a cavity is formed in the center), thermally expanding the heat sink, inserting the core into the thermally expanded cavity, and cooling the cavity. It is a processing method for fitting the core inside. With this method, there arises a problem that the strength of the heat dissipating fins is reduced by performing heating and cooling operations. However, if it is the structure of Claims 2 and 3 of this invention, it is not necessary to perform shrink fitting and the intensity | strength of a radiation fin does not fall.

  Moreover, when the heat sink is used in the conventional operating temperature range, the core fitted by shrink fitting does not fall out. However, when the operating temperature range is further increased, thermal expansion occurs in the heat sink and the core may fall off. According to the configuration of the present invention, such a problem does not occur.

  According to the heat sink according to claims 5 and 6 of the present invention, it is easy to fix the mounting member to the heat sink. As the fixing operation, only the contact surface of the object contact portion to be cooled is pressurized, and therefore the production man-hour is small. Further, the mounting member is fixed to the outer peripheral surface of the object to be cooled by plastically deforming the outer peripheral end of the contact surface of the object to be cooled. Since the mounting member is sandwiched between the axial end surface of the heat sink and the plastically deformed object contact portion, the mounting member is firmly fixed. Moreover, if the attachment member of Claim 7 of this invention is used, the circumference strength in the circumferential direction will become higher. Therefore, if this fixing method is adopted, the number of production steps is small, and high fixing strength can be obtained.

  Hereinafter, a heat sink, a manufacturing method thereof, and a heat sink fan according to an embodiment of the present invention will be described with reference to FIGS. In the embodiment of the present invention, the vertical direction of each drawing is referred to as the “vertical direction” for convenience, but the direction in the actual mounting state is not limited.

  First, the heat sink fan according to the first embodiment of the present invention will be described. FIG. 1 is a perspective view showing a heat sink according to an embodiment of the present invention. FIG. 2 is a perspective view showing a state of the divided material of the heat sink according to the embodiment of the present invention.

  The heat sink 1 is a heat radiating member formed by extrusion (pulling) processing of a material having relatively high thermal conductivity such as aluminum or aluminum alloy. In this embodiment, an aluminum alloy is used. Usually, the heat sink 1 has a plurality of heat radiation fins 12 projecting radially outward from the cylindrical outer surface of the cylindrical base 11 so that the contact area with the outside air, that is, the surface area of the heat sink 1 is increased. The plurality of heat dissipating fins 12 are formed continuously with the base 11. However, the base 11 is not cylindrical and may have a shape other than a cylindrical shape such as a square pole. In the present embodiment, as shown in FIG. 1, a plurality of heat dissipating fins 12 extending radially with respect to the base portion 11 are arranged in an annular shape on the outer periphery of the base portion 11. In particular, the heat dissipating fins 12 are curved with respect to the arrangement direction in order to increase the surface area. When the radiating fin 12 is bent, the surface area of the radiating fin 12 alone increases. The shape of the radiating fin 12 for increasing the surface area of the heat sink 1 is not limited to this, and the shape can be changed as appropriate.

  In the present embodiment, the base portion 11 and the heat radiation fin 12 are formed of an aluminum alloy. As shown in FIG. 1, the base 11 is formed in a columnar shape centered on the central axis. The base is formed in a solid structure.

  Conventionally, a heat sink is formed by a method of forming a through-hole centered on the central axis at the center of the base and press-fitting a cylindrical core into the through-hole. As described above, contact thermal resistance is generated on the contact surface between the through hole and the core. Therefore, in order to reduce the value of the contact thermal resistance generated on the contact surface between the side surface of the core and the through hole when the core is inserted into the through hole, the contact pressure is press-fitted and fixed. . More precisely, while the base 11 is heated to a high temperature and the inner diameter of the through hole 111 of the base 11 is expanding, a core is inserted into the through hole 111 and the base 11 is cooled, so-called shrink fitting. Is press-fitted and fixed. Thereby, the value of the contact thermal resistance in the contact surface of the through-hole 111 and a core becomes small. Therefore, the heat transmitted from the MPU 3 to the core is efficiently transmitted to the base 11 and is radiated from the radiation fins 12 to the outside air. However, in this method, since a large temperature change occurs when the heat sink 1 is heated or cooled, the strength of the heat sink 1 itself may be reduced, and high reliability cannot be obtained. The reason will be described later.

  Generally, the extrusion (drawing) process using an aluminum alloy material has a simple mold structure used for molding, and has a high dimensional accuracy in the finished product. Copper materials are very difficult to form by extrusion (drawing) of complex shapes, and the finished dimensional accuracy is extremely poor. In fact, it is impossible to form a heat sink having a complicated shape made of copper by extrusion (pulling). For this reason, in the complicated heat sink 1 in which the heat radiating fins 12 are continuously formed with respect to the base 11, an aluminum alloy material is used instead of a copper material.

  Next, a method for forming a heat sink by extrusion (drawing) will be described in detail. FIG. 3 is a perspective view showing the flow of the mold until the heat sink is formed. FIG. 4 is a diagram showing a molding flow of the first embodiment showing until the heat sink is formed.

  As an aluminum alloy used for the heat sink 1, 6000 series Al-Mg-Si series or 1000 series pure Al is mainly used. Among these, 6063 of 6000-based Al—Mg—Si is often used. 6063 has excellent extrudability, and is used as a structural material that does not require particularly high strength, mainly for building sashes. Since the heat sink 1 is not required to be as strong as a building structural material, 6063 is most used. When the thermal conductivity is given the highest priority, 1060, 1070 out of 1000 series pure Al is used.

  First, a cylindrical billet 6 (a lump of metal used for rolling or the like) made of aluminum alloy is prepared. Next, the billet 6 is heated to about 500 ° C. in a furnace (step S1). The billet 6 heated in the furnace is softened compared to the normal temperature state. In this state, the billet 6 is pushed into the split mold 7 shown in FIG. 3A. The dividing mold 7 is processed into a shape that allows the billet 6 to be divided into seven when the billet 6 is pushed in (step S2).

  In this embodiment, the division mold 7 divides the number into seven, but the number of divisions is not limited to seven. That is, the number of divisions can be changed as appropriate depending on the shape and size of the heat sink. The billet 6 pushed into the split mold 7 is divided into a plurality (seven) of split materials 61 and 62. As shown in FIG. 3B, the divided materials 61 and 62 are constituted by a center portion material 61 and a heat radiation fin portion material 62. The central part material 61 is a material obtained by dividing the part constituting the central part of the billet by a dividing die as the name suggests. Next, a plurality of radiating fin part materials 62 are arranged so as to surround the periphery of the center part material 61.

  Next, the divided materials 61 and 62 are pushed into the heat sink mold 8 (step S3). The heat sink mold 8 is processed into a shape in which a plurality of heat radiation fins 12 are arranged around the base portion 11 as shown in FIG. 3C when the divided materials 61 and 62 are extruded. When the divided materials 61 and 62 are pushed into the heat sink mold 8, they are brought into contact with each other and joined. In other words, the heat sink 1 processed by this method is formed in a state where the billet 6 is divided and the heat radiation fin material 620 is arranged around the center portion material 610 and joined to each other.

  In the extrusion (drawing) process of the heat sink of this embodiment, a direct method is mainly used. The direct method is a method of extruding a raw material directly in the extrusion direction like tokoroten. More specifically, the direct method is a method in which a heated billet is inserted into a container in which an extrusion mold is placed, and the billet is compressed in the mold direction. The compressed billet passes through the mold and is extruded into a predetermined mold. In the direct method, friction is generated between the billet and the container during extrusion. Moreover, since the pressure at the time of passing through a metal mold | die changes with parts, a metal flow (flow of metal structure) becomes non-uniform | heterogenous. In the heat sink of this embodiment, the pressure generated in the heat radiating fin material 62 on which the heat radiating fins 12 are formed increases. In addition, the pressure generated in the center material 61 that forms the center of the base 11 is increased. That is, when the extrusion (pulling) process is performed without using the split mold 7, the billet 6 corresponding to the radiating fin 12 part has friction with the container and the heat sink corresponding to the radiating fin 12 part. The pressure generated in the billet 6 by the mold 8 is high. On the contrary, in the vicinity of the center portion of the billet 6, the generation of friction is low, and the pressure change inside the billet 6 generated when the billet 6 passes through the heat sink mold 8 is small. If the dividing mold 7 is not used, the metal flow becomes completely non-uniform, and extrusion (drawing) processing with high accuracy cannot be performed.

  By using the dividing mold 7, the billet 6 is divided into a center part material 61 and a plurality of radiating fin materials 62. As a result, the metal flow is divided. Therefore, the non-uniform state of the metal flow in each of the divided materials 61 and 62 is reduced.

  The heat sink 1 that has been subjected to the extrusion (drawing) process is finished into a long heat sink 1 that is long in the axial direction, like the billet 6. At the time of extrusion, the heat sink 1 is soft because it is hot. For this reason, the heat sink 1 itself is easily twisted, and there is a twisted heat sink 1. Therefore, by pulling both ends of the heat sink 1 to each other, the twist of the heat sink 1 is corrected and cooled in a straight state. By this operation, the accuracy of the size of the heat sink 1 is determined.

  The heat sink 1 subjected to extrusion (drawing) processing is long. For this reason, the heat sink 1 is cut | disconnected by a surface perpendicular | vertical to an axial direction (step S4).

  5 and 6 are perspective views showing a part of the cutting process of the object contact portion of the first embodiment. The cut heat sink 1 is chucked on a lathe. The heat sink 1 is a lathe, and the radiating fins 12 are cut so that the substantially cylindrical object to be cooled contact portion 13 protrudes in the axial direction from the end face of the heat sink 1 (step S5). In the heat sink 1 of this embodiment, since the to-be-cooled object contact portion 13 has a columnar shape as shown in FIG. 5, machining by a lathe requires the smallest number of work steps. However, the shape is not limited to this, and the object to be cooled 13 may be formed by using, for example, a square mill. Moreover, when it is desired to reduce the diameter of the object contact portion 13, the outer peripheral end of the base portion 11 may be cut by a lathe.

  Next, as shown in FIG. 6, as the cutting process by a lathe, the annular groove 14 is cut along the outer peripheral edge of the end surface of the object-to-be-cooled object contact portion 13 (surface that contacts the MPU 3: contact surface 131). (Step S6). An annular groove 14 is formed on the inner side of the outer peripheral end of the contact surface 131 so that the pressurizing portion 15 (a portion to be pressed by a press in a process described later) remains. Therefore, in the contact surface 131, the region in contact with the object to be cooled (MPU 3) is an area inside the annular groove 14.

  FIG. 7 is a perspective view showing a process of fixing the mounting member to the heat sink of the first embodiment. FIG. 8 is a perspective view showing the heat sink of the first embodiment to which the mounting member is fixed. FIG. 9 is a perspective view showing an attachment member according to the present invention. The heat sink 1 in this embodiment is used for cooling the MPU 3. Therefore, it is necessary to bring the contact surface 131 into contact with the MPU 3. For this purpose, it is necessary to attach the heat sink 1 to the mother board 31 on which the MPU 3 is mounted. Therefore, the attachment member 9 for attaching the mother board 31 and the heat sink 1 is attached and fixed to the heat sink 1. As shown in FIG. 9, the attachment member 9 has a through hole 92 formed in the center, and four attachment legs 91 are formed outward in the radial direction. A through hole 911 into which a fixing member 90 to be fastened to the mother board 31 and the mounting member 9 is inserted is formed at the tip of the mounting leg 91. The attachment member 9 is made of a stainless material such as SUS having a high rust prevention property.

  First, as shown in FIG. 7, the attachment member 9 is inserted so that a through hole formed at the center of the attachment member 9 is fitted to the outer peripheral surface of the object to be cooled contact portion 13. When the attachment member 9 is inserted into the object-to-be-cooled contact portion 13, the attachment member 9 is pushed in until it comes into contact with the end face of the radiating fin 12. In this state, the pressurizing unit 15 is pressurized by the press toward the lower side in the axial direction in FIG. 7 over the entire circumference (step S7). The pressurized pressure part 15 is plastically deformed outward in the radial direction of the cooled object contact part 13. As shown in FIG. 8, the mounting member 9 is sandwiched and fixed between the plastically deformed pressurizing portion 15 and the end surface of the radiating fin 12. Since the pressurizing portion 15 is plastically deformed, the shape is continuously maintained in the deformed state. Therefore, the state in which the attachment member 9 is fixed to the object to be cooled contact portion 13 is continuously maintained. Further, by being pressurized, the outer shape of the outer peripheral surface of the object-to-be-cooled object contact portion 13 is deformed so as to increase in diameter radially outward. Therefore, the outer peripheral surface of the cooled object contact portion 13 applies pressure to the through hole of the mounting member 9, whereby the mounting member 9 is fixed to the outer peripheral surface of the cooled object contact portion 13.

  Cutouts 921 are formed at a plurality of locations (four locations in the present embodiment) on the inner peripheral surface of the through hole 92 of the attachment member 9. By increasing the outer diameter of the outer peripheral surface of the object to be cooled contact 13, the inner peripheral surface of the through hole 92 of the attachment member 9 bites into the outer peripheral surface of the object to be cooled contact 13. At this time, the notch 921 is formed on the inner peripheral surface of the through-hole 92, so that the circumferential strength around the central axis of the attachment member 9 with respect to the object to be cooled 13 is improved.

  In the conventional heat sink structure, the core is press-fitted into the center of the base. The reason is that the process of extruding (drawing) the heat sink is performed in a shape in which a through hole is formed at the center of the base. In general, such a heat sink shape is a shape called a hollow shape, and it is not necessary to perform a special extrusion (drawing) process. Therefore, it was necessary to press-fit the core into the through hole by the above-described shrink fitting. However, when press-fitting the core by shrink fitting, the heat sink is heated and then cooled. That is, heat shock (a state in which heating and cooling are repeated) is performed on the heat sink, and the mechanical strength of the heat sink itself may be reduced. In particular, the portion corresponding to the base of the outer periphery of the core is thin, and there is also a joint surface of the divided material. For this reason, if the mechanical strength is reduced, the joint surface of the divided material may be torn and the core may fall off. However, in the heat sink according to the present embodiment, since the base portion has a solid structure, there is no problem of falling off the core. Further, there is no need for shrink fitting, and the mechanical strength of the heat sink is not lowered.

  Next, a process of transferring heat from the MPU 3 as a heat source to the heat sink will be described. FIG. 10 is a plan view showing a state of contact between the MPU and the heat sink. The MPU 3 is mounted on the mother board 31. The core is in contact with the MPU 3 at the contact surface. A heat conducting material is interposed between the MPU 3 and the contact surface. The heat generated in the MPU 3 is transferred to the core. That is, the value of the contact thermal resistance generated between the MPU 3 and the contact surface becomes important. For example, if the flatness of the surfaces of the MPU 3 and the contact surface is 0, the surface roughness is 0, and the contact pressure is high, the contact thermal resistance is extremely small. However, in reality, neither the flatness nor the surface roughness is zero, and a gap is generated between the MPU 3 and the contact surface 131 if no heat conductive material is formed. Since air has a high heat insulation effect, when a gap is formed between the MPU 3 and the contact surface 131, the contact thermal resistance becomes a high value. In the present embodiment, as described above, since the heat conductive material is interposed between the MPU 3 and the contact surface 131, the value of the contact thermal resistance can be lowered.

  A material having a high heat transfer property is used as the heat conducting material. In this embodiment, in consideration of workability, a polyimide film (Polyimide Film), a tape-like material such as a thermal tape coated with a pressure sensitive adhesive containing a filler on a support substrate such as an aluminum foil is coated. A member is used. The higher the contact area between the heat conductive material, the MPU3 surface, and the contact surface 131, the lower the value of the contact thermal resistance. For this reason, a grease-like thermally conductive silicone resin or the like in which a silicone oil is used as a base oil and a powder having high thermal conductivity such as alumina is blended may be used as a material for the thermally conductive material. Since the thermal tape is cut to a predetermined size, the area of the MPU 3 surface and the contact surface 131 may not be effectively utilized. Since the thermally conductive silicone resin is in the form of grease, it can be brought into close contact with the surface of each member with almost no gap. Therefore, the area of the MPU 3 surface and the contact surface 131 can be effectively utilized. The heat conductive material can be appropriately changed as long as it is a member having high heat conductivity, and the shape and material are not limited.

  The heat generated in the MPU 3 is transmitted to the base 11 of the heat sink 1 through the heat conductive material. In this transmission process, it is possible to greatly improve the heat radiation efficiency by reducing the value of the thermal resistance. What is important here is the value of the contact thermal resistance generated between the MPU 3 and the heat conductive material and between the heat conductive material and the contact surface 131. The value of contact thermal resistance depends on contact pressure, contact area, surface roughness of contact surface, thermal conductivity of each material, thermal conductivity of thermal conductive material, thickness of thermal conductive material, hardness of each material surface It is determined. The surface of the MPU 3 is generally composed of a copper plate having a high thermal conductivity called a heat spreader. For this reason, it is necessary to propose a method for reducing the value of the contact thermal resistance by setting the contact area on the MPU 3 side, the surface roughness of the contact surface, the thermal conductivity of the material (copper plate), and the hardness of the material (copper plate) as constant values. is there. Since the contact surface 131 of the heat sink 1 uses an aluminum alloy as described above, the surface roughness of the contact surface, the thermal conductivity of the material (copper), and the hardness of the material (copper) are assumed to be constant values. There is a need to propose a method for reducing the value of resistance. It is a well-known technique that the value of the contact thermal resistance is lowered by increasing the contact pressure.

  FIG. 11 is a perspective view showing a heat sink cooling device in which a cooling fan is attached to the upper portion of the heat sink 1 cooling device. Heat is transmitted from the MPU 3 to the base 11 through the heat conductive material. Next, the heat transferred to the base 11 is transferred to the heat radiating fins 12. In the present embodiment, as shown in FIG. 11, the cooling fan 5 operates on the heat sink 1 to supply cooling air to the radiation fins 12, and the heat transmitted to the radiation fins 12 is forced. Heat is released. The configuration of the cooling fan 5 will be described below.

  The cooling fan 5 converts an impeller 52 that generates cooling air by rotating, an electric motor (not shown) that rotates the impeller 52, and cooling air generated by rotating the impeller 52 into static pressure energy. A wind tunnel portion 511, a base portion 51 for fixing the electric motor, and at least three or more spoke portions 512 for connecting and connecting the base portion 51 and the wind tunnel portion 511 are provided.

  The impeller 52 has a plurality of blades 521. The blade 521 protrudes radially outward from the rotation axis of the impeller 52. As impeller 52 rotates, kinetic energy is given to air in blade 521. As the impeller 52 rotates, air is sucked in the axial direction and exhausted in the axial direction. That is, the impeller 52 rotates to generate an axial air flow. As the impeller 52 rotates, an air flow is generated. Therefore, the air flow is divided into three components, a centrifugal direction component that is radially outward, a rotation component that is directed to the circumferential direction of rotation, and an axial component that is discharged in the axial direction. With ingredients. Considering the component of the flow velocity of the air flow, the flow velocity is greatest at the radially outer side of the impeller 52 and is smallest at the radially inner side of the impeller 52. Therefore, the cooling air supplied to the heat sink 1 has the highest flow velocity radially outward of the radiating fins 12.

  As shown in FIG. 11, the cooling fan 5 is placed on the upper side of the heat sink 1 so that the central axis of the base 11 and the rotation axis of the impeller 52 of the cooling fan 5 substantially coincide with each other. As shown in FIG. 11, a cutout portion 112 is formed on the outer peripheral edge of the heat radiating fin 12 on the outer peripheral side surface of the heat sink 1. An arm 5111 extending downward from the wind tunnel 511 is locked to the notch 112, and the heat sink 1 and the cooling fan 5 are fixed. The heat generated in the MPU 3 is transmitted to the base 11 through the heat conductive material. Heat is transferred from the base 11 to the heat radiating fins 12. As the cooling fan 5 rotates, cooling air is supplied from above to below in FIG. The radiation fins 12 are arranged in the same direction as the rotation direction of the impeller 52. For this reason, the cooling air efficiently flows between the heat radiating fins 12, and the heat transmitted to the heat radiating fins 12 is forcibly radiated. By combining the heat sink 1 cooling device and the cooling fan 5, the cooling characteristics of the heat sink 1 cooling device are further enhanced.

  Further, the radiating fins 12 are curved toward a direction different from the rotation direction of the impeller 52. Thus, the air flow generated from the blades 521 due to the rotation of the impeller 52 does not interfere with the heat radiating fins 12 at the same time. Therefore, it is possible to reduce the noise value due to the interference between the air flow and the radiation fins 12. However, although the radiating fin 12 is curved toward a direction different from the rotation direction of the impeller 52, it is possible to sufficiently reduce the interference between the airflow and the radiating fin 12 just by inclining without bending. Is possible. Since the blades 521 themselves of the impeller 52 are curved in the rotation direction, the interference between the air flow and the radiation fins 12 can be sufficiently reduced even if the heat radiation fins 12 extend in the radiation direction without being inclined. Is possible.

  Next, a heat sink fan according to a second embodiment of the present invention will be described. The heat sink fan according to the second embodiment has the same configuration as the heat sink fan shown in FIGS. 1 to 3 and FIGS. 9 to 12 except for the fixing method for fixing the attachment member 9. Components other than those relating to the method are denoted by the same reference numerals.

  FIG. 12 is a diagram showing a molding flow of the second embodiment showing the process until the heat sink is formed in the present invention. FIG. 13: is a perspective view which shows a part of cutting process of the to-be-cooled object contact part of 2nd Embodiment concerning this invention.

  As shown in FIG. 12, the heat sink formation process is exactly the same as in the first embodiment up to step S5. Therefore, it demonstrates from the process after step 5. FIG.

  The heat sink 1A is a lathe, and the radiating fins 12 are cut so that the substantially cylindrical object to be cooled contact portion 13 protrudes in the axial direction from the end face of the heat sink 1A (step S5). Next, as a cutting process by a lathe, as shown in FIG. 13, toward the heat sink 1 </ b> A side along the outer peripheral end of the end surface (surface contacting MPU 3: contact surface 131 </ b> A) of the object to be cooled 13. The recessed step portion 14A is cut (step S6A). A region on the inner side of the stepped portion 14A, that is, a contact surface 131A protruding from the stepped portion 14A upward in the axial direction in FIG. 13 is formed. This contact surface 131 becomes an area | region which contacts a to-be-cooled object (MPU3).

  FIG. 14 is a perspective view showing a process of fixing the mounting member to the heat sink of the second embodiment. FIG. 15 is a perspective view showing the heat sink of the second embodiment to which the mounting member is fixed. The heat sink 1A in the present embodiment is used to cool the MPU 3. Therefore, it is necessary to bring the contact surface 131A into contact with the MPU 3. For this purpose, it is necessary to attach the heat sink 1A to the mother board 31 on which the MPU 3 is mounted. Therefore, the attachment member 9 for attaching the mother board 31 and the heat sink 1A is attached and fixed to the heat sink 1A. As shown in FIG. 9, the attachment member 9 has a through hole 92 formed in the center, and four attachment legs 91 are formed outward in the radial direction. A through hole 911 into which a fixing member 90 to be fastened to the mother board 31 and the mounting member 9 is inserted is formed at the tip of the mounting leg 91. The attachment member 9 is made of a stainless material such as SUS having a high rust prevention property.

  First, as shown in FIG. 14, the attachment member 9 is inserted so that a through hole formed in the center of the attachment member 9 is fitted to the outer peripheral surface of the object to be cooled contact portion 13. When the attachment member 9 is inserted into the object-to-be-cooled contact portion 13, the attachment member 9 is pushed in until it comes into contact with the end face of the radiating fin 12. In this state, the step 14A is pressurized by the press toward the lower side in the axial direction in FIG. 14 over the entire circumference (step S7A). The pressed stepped portion 14 </ b> A is plastically deformed outward in the radial direction of the object-to-be-cooled contact portion 13. As shown in FIG. 15, the attachment member 9 is sandwiched and fixed between the plastically-deformed step portion 14 </ b> A and the end surface of the radiating fin 12. Since the step portion 14A is plastically deformed, the shape is continuously maintained in the deformed state. Therefore, the state in which the attachment member 9 is fixed to the object to be cooled contact portion 13 is continuously maintained. Further, by being pressurized, the outer shape of the outer peripheral surface of the object-to-be-cooled object contact portion 13 is deformed so as to increase in diameter radially outward. Therefore, the outer peripheral surface of the cooled object contact portion 13 applies pressure to the through hole of the mounting member 9, whereby the mounting member 9 is fixed to the outer peripheral surface of the cooled object contact portion 13.

  In order to stabilize the cooling characteristics of the heat sinks 1 and 1A, the contact areas of the contact surfaces 131 and 131A need to be constant in mass-produced products. In the first embodiment, a region inside the annular groove 14 becomes the contact surface 131. In this case, the pressure unit 15 is pressurized and plastically deformed, but the deformation does not reach the contact surface 131. In the second embodiment, a region on the inner side of the stepped portion 14A is the contact surface 131A. In this case, the step portion 14A is pressurized and plastically deformed, but the deformation does not reach the contact surface 131A. Therefore, also in the first and second embodiments, the areas of the contact surfaces 131 and 131A are constant, and the cooling characteristics of the heat sinks 1 and 1A can be stabilized.

  As another modification, the outer peripheral end of the object contact portion 13 is pressed without forming the annular groove 14 and the stepped portion 14A, and the attachment member 9 is fixed to the outer peripheral surface of the object contact portion 13 to be cooled. The upper surface of the object contact portion 13 may be cut to form the contact surface 131.

It is the perspective view which showed the heat sink of embodiment concerning this invention. It is the perspective view which showed the state of the division material of the heat sink of embodiment concerning this invention. It is a perspective view which shows the flow of the metal mold | die which shows until a heat sink concerning this invention is formed. It is a figure which shows the flow of shaping | molding of 1st Embodiment which shows until a heat sink is formed in this invention. It is a perspective view which shows a part of cutting process of the to-be-cooled object contact part of 1st Embodiment concerning this invention. It is a perspective view which shows a part of cutting process of the to-be-cooled object contact part of 1st Embodiment concerning this invention. It is a perspective view which shows the process in which the attachment member of 1st Embodiment concerning this invention is fixed to a heat sink. It is a perspective view which shows the heat sink with which the 1st attachment member concerning this invention was fixed. It is a perspective view which shows the attachment member concerning this invention. It is the top view which showed the condition of contact with MPU concerning this invention and a heat sink. It is a perspective view which shows the heat sink fan which attached the cooling fan to the upper part of the heat sink 1 cooling device concerning this invention. It is a figure which shows the flow of shaping | molding of 2nd Embodiment which shows until a heat sink is formed in this invention. It is a perspective view which shows a part of cutting process of the to-be-cooled object contact part of 2nd Embodiment concerning this invention. It is a perspective view which shows the heat sink with which the 2nd attachment member concerning this invention was fixed. It is a perspective view which shows the heat sink with which the 2nd attachment member concerning this invention was fixed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat sink 11 Base 12 Radiation fin 13 Cooling object contact part 131 Contact surface 14 Annular groove 15 Pressurization part 3 MPU
31 Motherboard 5 Cooling fan 6 Billet 61 Center part material 62 Radiation fin part material 9 Mounting member 91 Mounting leg 92 Through hole 921 Notch

Claims (13)

A heat sink for cooling an object to be cooled such as an electronic component,
A solid and columnar base formed around the central axis;
A plurality of fins extending radially outward from the base about the central axis,
The heat sink, wherein the base part and the fin part are continuously formed by extrusion or drawing in an axial direction with the central axis as an axis.   The heat sink according to claim 1, wherein the base portion and the plurality of fin portions are formed by combining a plurality of divided materials obtained by dividing one billet into a plurality of pieces.   The plurality of divided materials include a substantially cylindrical center part material that forms the center part of the base part with the center axis as a center, and one outer portion of the base part around the center part material with the center axis as a center. And a plurality of heat dissipating fin materials constituting part of the heat dissipating fins, each heat dissipating fin portion being arranged in the circumferential direction, and the center material and the heat dissipating fin member materials being formed continuously. The heat sink according to claim 2, wherein the heat sink is provided. The heat sink is
It has a through hole in the center, and has a mounting member in which a plurality of mounting legs are radially extended toward the outside in the radial direction.
An object-to-be-cooled contact portion that protrudes in the axial direction from the base is formed, and an outer peripheral side surface of the object-to-be-cooled contact portion is fitted into the through hole of the mounting member. Item 4. The heat sink according to any one of Items 1 to 3.   A plurality of portions plastically deformed radially outward are formed at the outer peripheral end of the contact surface of the object to be cooled, and the attachment member is fixed to the outer peripheral side surface of the object to be cooled The heat sink according to claim 4.   The entire circumference of the outer peripheral end of the contact surface of the object to be cooled is plastically deformed radially outward, and the mounting member is fixed to the outer peripheral side surface of the object to be cooled contact. The heat sink according to claim 4.   The heat sink according to any one of claims 4 to 6, wherein at least one notch is formed in an inner peripheral surface of the through hole formed in the attachment member. A heat sink fan using the heat sink according to any one of claims 1 to 7,
The heat sink;
A cooling fan that is arranged substantially coaxially with the central axis and blows a cooling airflow to the heat sink,
The cooling fan is
An impeller comprising a plurality of blades that generate an air flow in the axial direction by rotating about the central axis;
A motor unit for rotationally driving the impeller;
A heat sink fan comprising: a housing that has a wind tunnel portion that surrounds the impeller from the outside in a radial direction and supports the motor portion. A solid and columnar base formed around the central axis;
A plurality of fin portions extending radially outward from the base portion about the central axis, and a heat sink manufacturing method comprising:
a) a step of heating a billet made of aluminum or aluminum alloy in a furnace;
b) the material billet is pushed into a dividing mold, and the material billet is divided into a plurality of divided materials;
c) a step in which the plurality of divided materials are pushed into a heat sink mold, and a long heat sink is extruded from the heat sink mold while the divided materials are joined to each other;
and d) cutting the long heat sink in the axial direction.   In the step b), the raw material is divided into a central part material that forms the central part of the base part and a plurality of radiating fin part materials that surround the circumferential direction of the outer part of the central part material. A method for manufacturing a heat sink according to claim 9. In the manufacturing method of the heat sink according to claim 9 or 10,
e) cutting the heat sink so as to leave a columnar object to be cooled centered on the central axis on the axial end surface on either side of the cut heat sink;
f) Insert a mounting member having a through hole in the center and having a plurality of mounting legs radially extending outward in the radial direction so that the outer peripheral side surface of the object-to-be-cooled contact portion fits into the through hole. Process,
g) Pressurizing the plurality of outer peripheral ends or the entire circumference of the contact surface of the object to be cooled by pressurizing the plurality of outer peripheral ends or the entire periphery of the contact surface of the object to be cooled is radially outward. A step in which the mounting member is fixed to an outer peripheral side surface of the object to be cooled,
A method of manufacturing a heat sink. Before the step g), a step of forming a groove along the outer peripheral edge of the contact surface of the object contact portion to be cooled is provided.
The method of manufacturing a heat sink according to claim 11, wherein in the step g), a portion outside the groove of the object contact portion to be cooled is pressurized. Before the step g), it includes a step of forming a step portion that is recessed toward the heat sink side along the outer peripheral edge of the contact surface of the object to be cooled contact portion,
The method of manufacturing a heat sink according to claim 11, wherein in the step g), the step portion of the object contact portion to be cooled is pressurized.

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