WO2013094038A1 - Cooler and method of manufacturing same - Google Patents

Abstract

Provided is a cooler which has heat pipes and fins and which effectively utilizes the fins. The cooler (100) disclosed in the description is provided with bent heat pipes (2 and 3) and multiple fins (6). The heat pipes (2 and 3) form an L-shape and are configured from base plates (2a, 3a), which are attached to a heat-generating body, and from rib plates (2b, 3b), which extend towards the back surface of the base plates. Inside of the heat pipes, a flow path (4) is formed which extends across both the base plates and the rib plates. Further, the edges of the fins are in contact with the back surface of the base plates and with both rib plates. Heat from the heat-generating body is transferred to the fins by two paths, namely, a path via the base plates to the fins and a path via the rib plates to the fins. Therefore, more heat can be transferred to the fins.

Description

Cooler and manufacturing method thereof

The technology disclosed in this specification relates to a cooler using a heat pipe and a manufacturing method thereof.

Heat pipes are often used to cool electronic components such as CPUs and semiconductor chips. The heat pipe has a simple structure in which a plurality of sealed elongated holes are sealed and a small amount of working fluid is sealed in the elongated holes. Although it has a simple structure, various techniques for improving the heat pipe have been proposed (Patent Documents 1 to 5). The heat pipe itself is a device for transporting heat, and a fin for heat dissipation is attached to the heat pipe, and a fan that sends air to the fin often constitutes a cooler (for example, Patent Document 1 and Patent Document 2). ).

JP 2004-039861 A Japanese Patent Laid-Open No. 2003-066569 JP 2003-302180 A JP 2007-062683 A JP 2004-125382 A

In the conventional cooler, only one side of the fin is fixed to a flat heat pipe. However, in such a structure, the tip of the fin (the side far from the heat pipe) is not used effectively. The technology disclosed in the present specification provides a cooler that effectively uses fins by applying heat pipes to two sides of the fin, and a method of manufacturing the same.

The novel cooler disclosed in this specification includes a bent heat pipe and a plurality of fins. The heat pipe is L-shaped. In other words, the heat pipe is L-shaped by a base plate to which a heating element is attached and a rib plate extending to the back side of the base plate. Here, the surface to which the heating element is attached is referred to as “front surface”, and the surface opposite to the surface to which the heating element is attached is referred to as “back surface”. In addition, an L-shaped channel extending over both the base plate and the rib plate is formed inside the heat pipe. And the edge of the fin is in contact with both the back surface of the base plate and the surface of the rib plate. In other words, the fin has one side in contact with the base plate and the other side in contact with the rib plate. A gap is provided between a bent portion of the L-shaped heat pipe (a point where the base plate and the rib plate are connected) and the fin.

In the above cooler, a heat source such as a semiconductor chip is attached to the front surface of the base plate. The heat of the heat source is transferred to the fin in two paths: a path that is transmitted from the base plate to the fin and a path that is transmitted to the fin through the rib plate. Therefore, the heat of the heat source is efficiently transmitted to the fins. If the amount of heat transferred to the fins is large, the amount of heat released from the fins also increases. The above-described cooler can effectively use fins and can achieve high cooling efficiency. The L-shaped heat pipe is made by bending a flat heat pipe. A flat heat pipe can be made inexpensively by extrusion.

The cooler disclosed in the present specification may have a structure in which rib plates of two L-shaped heat pipes are coupled to each other. In other words, two L-shaped heat pipes may have a structure in which the L-shaped bottom surfaces are coupled back to back so that they form a single plane.

The fin is preferably made of a metal plate having a slit. The slit can be fitted to the rib plate. The fins may be a plurality of thin plates, but may be a single corrugated plate. In that case, it is preferable that a ventilation hole is provided in the peak of the corrugated plate (the top of the wave). When the corrugated plate is attached so that the corrugated valley (the bottom of the wave) is in contact with the base plate, the corrugated peak corresponds to the tip of the fin. If a ventilation hole is provided there, the ventilation to the side surface of a fin will become good.

A plurality of flow paths extending in parallel may be formed inside the heat pipe, or one or several flow paths described below may be formed. That is, in a plurality of flow paths arranged in parallel, adjacent flow paths are alternately connected on one end side and the other end side, and between one end and the other end of the heat pipe. A reciprocating flow path may be formed. If such a reciprocating flow path is provided, a self-excited vibration heat pipe can be configured.

This specification also provides a manufacturing method suitable for the above-described cooler. The method includes the following steps. One is a process of joining rib plates of two L-shaped heat pipes. In other words, it is a step of joining two L-shaped vertical surfaces together so that the bottom surfaces of the two L-shapes form one plane. The other is a process of fitting the slits of the fins with slits into the joining part of the two heat pipes. The L-shaped heat pipe is typically formed by bending a flat heat pipe into an L-shape. As described above, the above-described cooler itself can be made inexpensive by using a flat heat pipe that can be manufactured at low cost.

Details of the technology disclosed in this specification and further improvements will be described in the embodiments of the invention.

It is a perspective view of the cooler of the 1st example. It is a side view of the cooler of the 1st example. It is a perspective view of an L-shaped heat pipe. It is a perspective view of a multi-hole pipe. It is a perspective view of the multi-hole pipe | tube which closed opening. It is a perspective view which shows the completion figure of an L-shaped heat pipe. It is a figure which shows a mode that two L-shaped heat pipes are couple | bonded. It is a figure which shows a mode that a fin is attached. It is a perspective view of the cooler using a corrugated sheet as a fin. It is a figure which shows a mode that a some heat pipe is connected. It is a perspective view of the cooler of the 2nd example. It is a side view of the cooler of the 3rd example. It is a side view of the cooler of the 4th example.

(First Embodiment) The cooler of the embodiment will be described with reference to the drawings. FIG. 1 is a perspective view of the cooler 100 of the first embodiment. FIG. 2 is a side view of the cooler 100. The cooler 100 includes two L- shaped heat pipes 2 and 3 and a plurality of fins 6. The two L- shaped heat pipes 2 and 3 are joined back to back so that the bottom surfaces of the respective L-shapes form one plane, and form a T shape as a whole. The portion corresponding to the L-shaped bottom side of the L-shaped heat pipe 2 (3) is referred to as a base plate 2a (3a), and the portion corresponding to the L-shaped vertical side is referred to as a rib plate 2b (3b). For explanation, in the base plate 2a (3a), the side to which the semiconductor chip 90 (heat source) is attached is referred to as a front surface, and the side in contact with the fins 6 is referred to as a back surface.

Inside the L-shaped heat pipe 2 (3), a flow path 4 (see FIG. 2) is formed extending from one end to the other over the base plate 2a (3a) and the rib plate 2b (3b). In other words, the channel 4 is a closed elongated hole. As will be described later, the flow path 4 is folded at the end of the L shape and reciprocates between both ends of the L shape. The flow path 4 is a flow path in which a working fluid is enclosed. The flow path 4 will be separately described later.

The fin 6 is a thin metal plate having a slit 6s formed at the center, and the slit 6s is fitted to the tip of the coupled rib plate 2b (3b) (see FIG. 2). The edge 6a of the fin 6 is in contact with the back surface of the base plate 2a (3a), and the edge of the slit 6s is in contact with the rib plate 2b (3b). That is, the fin 6 is in contact with the heat pipe 2 (3) at two sides (a side indicated by reference numeral 6a in FIGS. 1 and 2 and a side indicated by reference numeral 6e). The fin 6 is cut obliquely from the opening of the slit 6s toward the edge 6a (6c in FIG. 2). A gap 5 is formed between the fin 6 and the portion where the base plate 2a (3a) and the rib plate 2b (3b) are connected, corresponding to the cut portion. A portion where the base plate 2a (3a) and the rib plate 2b (3b) are connected corresponds to an L-shaped bent portion of the heat pipe.

In order to show the structure of the flow path 4, FIG. 4 shows only the L-shaped heat pipe 2 in the configuration of the cooler 100. As shown in FIG. 4, the flow path 4 is bent along the L shape of the heat pipe 2 and reciprocates between both ends of the L shape of the heat pipe 2.

The function of the cooler 100 will be described. The front surface of the base plate 2a (3a) corresponding to the gap 5 corresponds to a mounting region of the semiconductor chip 90 (heat source). A small amount of working fluid is sealed in the flow path 4 inside the heat pipe 2 (3), and the working fluid is vaporized and moved by the heat of the semiconductor chip 90. The heat of the semiconductor chip 90 moves to the working fluid as heat of vaporization. A part of the working fluid vaporized in the vicinity of the semiconductor chip 90 moves to the end of the base plate 2a (3a), where it returns to the liquid and releases heat. The released heat moves to the fins 6. An arrow A in FIG. 2 indicates the heat path. On the other hand, the remainder of the working fluid vaporized in the vicinity of the semiconductor chip 90 moves to the end of the rib plate 2b (3b), where it returns to the liquid and releases heat. The released heat moves to the fins 6. An arrow B in FIG. 2 indicates the heat path. Thus, the heat of the semiconductor chip 90 is transferred to the fin 6 from two locations of the fin 6 through two paths. Therefore, this cooler 100 can efficiently transfer heat to the fins 6. Since the amount of heat transferred to the fin 6 is large, the amount of heat released from the fin 6 is also increased. The cooler 100 achieves a high cooling capacity.

The heat pipe 2 can also be used as a self-excited vibration heat pipe. The self-excited vibration type heat pipe uses its own vibration force as a force for moving the working fluid (heat medium) in the pipe. In that case, the flow channel portion (the flow channel portion in the vicinity of the L-shaped bent portion) located in the immediate vicinity of the semiconductor chip 90 corresponds to the evaporation portion of the self-excited vibration heat pipe. The flow path portion near the L-shaped end corresponds to the condensing portion. The flow path is in a state where gas phase portions and liquid phase portions exist alternately. In the evaporation section, the working fluid takes away heat from the semiconductor chip 90 and evaporates to generate new bubbles (the heat medium takes away heat of vaporization). In the evaporation section, the pressure increases due to the generation of bubbles. On the other hand, in the condensing part, the bubbles are liquefied by the cooling action (at this time, the heat medium releases the heat of condensation), and the pressure decreases. A self-excited pressure oscillation occurs due to the pressure difference between the evaporation section and the condensation section, and the heat medium in the gas phase and the liquid phase in the flow path moves from the evaporation section having a high pressure to the condensation section having a low pressure. This movement of the heat medium causes both latent heat and sensible heat to be transported simultaneously.

Next, a method for manufacturing the cooler 100 will be described. The L-shaped heat pipes 2 and 3 are made of flat multi-hole tubes. A multi-hole tube is a tube having a large number of through-holes made by an extrusion method. FIG. 4 shows a perspective view of the multi-hole tube 50. In FIG. 4, in order to facilitate understanding of the drawing, a part of broken lines indicating through holes are omitted. Hereinafter, description will be made by paying attention to the four through holes 51a, 51b, 51c, and 51d. Accordingly, in the subsequent drawings, illustration of the through holes other than the through holes 51a to 51d is omitted. Note that some of the through holes 51a and 51d are also omitted. FIG. 5 is a perspective view of the multi-hole tube 50 with the openings at both ends closed. When the openings at both ends of the multi-hole tube 50 are closed, adjacent through holes are alternately connected at one end side and the other end side. In FIG. 5, the through holes 51a and 51b are connected at the front end (see reference numeral 53a). The through holes 51b and 51c are connected at the end on the back side (see reference numeral 53b). The through holes 51c and 51d are connected again at the front end (see reference numeral 53c). Similarly, when all the through holes are alternately connected at both ends, the flow path 4 reciprocating the both ends of the multi-hole tube 50 is completed. When closing the last opening, a small amount of working fluid is put into the flow path 4. Thus, the multi-hole tube 50 becomes a flat heat pipe 55. A heat pipe having a flow path that reciprocates a plurality of times between both ends is a self-excited vibration type heat pipe.

Next, the flat heat pipe 55 is bent into an L shape (see FIG. 6). Thus, the heat pipe 2 that is bent in an L shape and has a flow path 4 that reciprocates between both ends of the L shape is completed. The portion corresponding to the L-shaped bottom side corresponds to the base plate 2a, and the portion corresponding to the L-shaped vertical side corresponds to the rib plate 2b.

Create a heat pipe 3 that has the same shape as the heat pipe 2. Next, the two heat pipes 2 and 3 are joined back to back (FIG. 7). “Back-to-back” means that the L-shaped vertical surfaces are joined so that the L-shaped bottom surfaces of the two heat pipes 2 and 3 form a single plane. The two heat pipes are joined by brazing. For brazing, for example, a brazing method using a chamber is employed. Alternatively, the heat pipes 2 and 3 are made of a clad material in which two kinds of metals are bonded together, and may be joined using an outer metal as a brazing material.

The clad material used here is typically a laminate of two types of metals having different melting points. As the clad material used here, a material whose melting point of the metal corresponding to the outside of the heat pipes 2 and 3 is lower than the melting point of the metal corresponding to the inside is used. The outer metal is used as the brazing material. That is, after the two L-shaped heat pipes 2 and 3 are back to back, the heat pipe is heated to a temperature at which the inner metal does not melt but the outer metal melts, and then cooled. Then, the two heat pipes 2 and 3 are joined by melting and solidifying the outer metal. For example, the outer metal is aluminum containing silicon, and the inner metal is aluminum not containing silicon. The melting point of silicon-containing aluminum is lower than the melting point of aluminum not containing silicon. Further, since the outer metal is used as a brazing material, its thickness may be about 0.1 mm to 0.5 mm. One of the two heat pipes 2 and 3 may be made of the clad material described above.

Thus, the heat pipe having the base plates 2a and 3a and the rib plates 2b and 3b extending from the back surface of the base plate and having the L-shaped flow path 4 extending over both the inside of the base plate and the inside of the rib plate is completed. . Although not shown, a flow path that reciprocates between both ends is also formed inside the heat pipe 3.

Finally, the fins 6 are coupled to the heat pipes 2 and 3 (FIG. 8). As described above, the fin 6 is provided with the slit 6s at substantially the center, and the slit 6s is fitted into the tips of the rib plates 2b and 3b. The fin 6 and the heat pipes 2 and 3 are joined by brazing, for example. When at least one of the heat pipes 2 and 3 is made of the above-described clad material, the fin 6 may be fixed using a metal outside the clad material as a brazing material. Thus, the cooler 100 of FIG. 1 is completed.

A modification of the cooler 100 will be described. The cooler 100 of FIG. 1 employs a plurality of thin plate fins 6. Instead of the plurality of fins 6, corrugated plates can be used as fins. FIG. 9 shows a perspective view of a cooler 100b using the corrugated plate 206 as a fin. The corrugated plate 206 is provided with slits 206 s similar to the fins 6. The corrugated plate 206 has a shape that reciprocates along the Z-axis direction of FIG. 9 with respect to the heat pipe in which the vertical surfaces of the two L-shaped heat pipes 2 and 3 are coupled to each other. The corrugated plate 206 has a crest (wave top) and a trough (wave bottom) that are the return of the wave. The trough (the bottom of the wave) is in contact with the base plate 2a (3a). No valley is formed in the gap 5 or the slit 206s, but it is possible to form the valley by forming it as “margin” or by using another member. The slit 206s penetrates the corrugated plate in a direction crossing the repeated wave of the corrugated plate. The tips of the two rib plates 2b and 3b that are joined are fitted into the slit 206s, and the corrugated plate 206 is fixed to the heat pipe. At this time, the height from the bottom of the wave to the top of the wave is higher than the height from the base plate 2a (3a) to the tip of the rib plate 2b (3b). In addition, a vent hole 206 d is provided on the top of the corrugated plate 206. External air passes through the vent hole 206d and contacts the side surface of the corrugated plate. Ventilation is improved by the vent hole 206d, and cooling efficiency is improved.

When making a wide L-shaped heat pipe, it is also preferable to connect a narrow heat pipe. FIG. 10 shows a plurality of narrow L-shaped heat pipes 302. On one side of the heat pipe 302, a protrusion 302a is formed. On the other side of the heat pipe 302, a groove 302b is formed. The size of the protrusion 302a is substantially equal to the size of the groove 302b. The protrusions 302a of the two adjacent heat pipes 302 are press-fitted into the groove 302b to couple the two heat pipes. Repeat the same to join the three heat pipes. Thus, a wide heat pipe can be obtained.

(Second Embodiment) FIG. 11 shows a perspective view of a cooler 100c of the second embodiment. The cooler 100 c includes one L-shaped heat pipe 402 and a plurality of fins 6. The plurality of fins 6 have one edge 6a in contact with the base plate 402a and the other edge 6b in contact with the rib plate 402b. The corner between the edge 6a and the edge 6b is cut, so that a gap 5 is formed between the coupling portion of the base plate 402a and the rib plate 402b and the fin 6. A heat source such as a semiconductor chip is attached to the back side of the gap 5. In the cooler 100c, similarly to the cooler 100 of the first embodiment, the heat of the heat source is finned in two paths: a path via the base plate 402a and the edge 6a, and a path via the rib plate 402b and the edge 6b. It is transmitted to 6. The fins 6 and the heat pipes 402 may be joined by brazing or may be joined by other methods.

(Third Embodiment) FIG. 12 shows a side view of a cooler 100d of the third embodiment. The cooler 100 d is obtained by assembling the cooler 100 and the fan 13 of the first embodiment to the case 12. In FIG. 12, only the case 12 is shown in cross section. The fan 13 is attached so as to blow air from the back surface of the base plate 2a (3a). The wind flowing toward the base plate 2a (3a) by the fan 13 passes between the plurality of fins 6 and flows outward from the holes 12a provided on the sides of the case 12. In the cooler 100d, air smoothly passes between the fins 6 to increase the cooling capacity.

(Fourth Embodiment) FIG. 13 shows a side view of a cooler 100e of the fourth embodiment. The cooler 100 e is obtained by assembling the cooler 100 and the fan 13 of the first embodiment to the case 22. In FIG. 131, only the case 22 is shown in cross section. The fan 13 is attached to the side of the case 22. Inside the case 22 is provided a blower passage 24 that directs the direction of the air blown out by the fan 13 toward the back surface of the base plate 2a (3a). By adopting the air passage 24, the degree of freedom of arrangement of the fan 13 for blowing air to the back surface of the base plate 2a (3a) is expanded.

留意 Points to keep in mind regarding the technology of the examples. The L-shaped heat pipe is preferably a self-excited vibration type, but is not limited thereto. In the embodiment, the heat pipe having the flow path 4 reciprocating between both ends has been described. Instead of such a heat pipe, a heat pipe having a plurality of parallel elongated holes filled with a working fluid may be adopted. The heat pipe and the heat pipe, or the heat pipe and the fin may be coupled by a method other than brazing. For example, they may be joined by an adhesive or welding.

As shown in FIG. 10, when connecting a plurality of heat pipes, it is also preferable to join a flat heat pipe having protrusions 302 a and grooves 302 b and then bend it into an L shape. The joint between the protrusion and the groove is plastically deformed by bending, and the two heat pipes are firmly connected.

The flow path that reciprocates both ends of the multi-hole tube can also be made by the following process. For adjacent through holes, the walls separating the openings are cut out. At this time, the walls separating the openings are alternately cut out at both ends of the through-hole so that the plurality of through-holes arranged in parallel form one reciprocating flow path. For example, if a wall between one through hole and the right adjacent through hole is cut out, the wall between the left through hole is cut out at the other end of the one through hole. Next, both ends of the multi-hole tube are closed. In order to close both ends, it may be closed by crimping the end of the multi-hole tube, or it may be closed by attaching a cover.

Specific and non-limiting specific examples of the present invention have been described in detail with reference to the drawings. This detailed description is intended merely to present those skilled in the art with the details for practicing the preferred embodiments of the present invention and is not intended to limit the scope of the invention. Also, the disclosed additional features and inventions can be used separately from or in conjunction with other features and inventions to provide further improved coolers.

Further, the combinations of features and steps disclosed in the above detailed description are not indispensable when practicing the present invention in the broadest sense, and are only for explaining representative specific examples of the present invention. It is described. Moreover, various features of the representative embodiments described above, as well as various features of what is recited in the claims, are described herein in providing additional and useful embodiments of the present invention. They do not have to be combined in the specific examples or in the order listed.

All the features described in the specification and / or claims are described in the disclosure and the claims at the beginning of the application separately from the configuration of the features described in the embodiments and / or claims. It is intended that the specific details provided be disclosed separately and independently of one another. Further, all numerical ranges and descriptions regarding groups or groups are intended to disclose intermediate configurations thereof as a limitation to the specific matters described in the original disclosure and the claims.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

Claims (17)

1. A base plate for attaching a heating element to the front surface, and a heat pipe having a flow path extending over both the inside of the base plate and the inside of the rib plate, with a rib plate extending toward the back side of the base plate,
   Fins whose edges are in contact with both the back surface of the base plate and the rib plate;
   A cooler characterized by comprising:
2. The cooler according to claim 1, wherein a gap is provided between a bent portion of the L-shaped heat pipe and the fin.
3. The cooler according to claim 1 or 2, wherein rib plates of two L-shaped heat pipes are coupled to each other.
4. The cooler according to any one of claims 1 to 3, wherein the fin has a slit, and the slit is fitted in the rib plate.
5. The cooler according to any one of claims 1 to 4, wherein the fin is formed of a corrugated plate, and a vent is provided in a crest portion of the corrugated plate.
6. The cooler according to any one of claims 1 to 5, further comprising a fan that sends air toward the fins from the back side of the base plate.
7. The cooler according to any one of claims 1 to 5, further comprising an air passage that sends air from the back side of the base plate toward the fins.
8. The adjacent flow paths are connected to each other, and a flow path reciprocating between one end and the other end of the heat pipe is formed. The cooler described.
9. The cooler according to claim 8, wherein the heat pipe is a self-excited vibration type.
10. It has an L-shaped first heat pipe with ridges formed on the sides and an L-shaped second heat pipe with grooves formed on the sides, and the ridges and grooves of adjacent heat pipes are fitted. The cooler according to any one of claims 1 to 9, comprising a continuous heat pipe.
11. The part of the heat pipe that contacts the fin is made of a clad material whose melting point of the outer metal is lower than the melting point of the inner metal, and the fin is bonded to the heat pipe by melting of the outer metal. The cooler according to any one of claims 1 to 10.
12. The joint portion between the heat pipes is made of a clad material in which the melting point of the outer metal is lower than the melting point of the inner metal, and the heat pipes are bonded by melting of the outer metal. Item 12. The cooler according to any one of Items 1 to 11.
13. Joining the rib plates of two L-shaped heat pipes;
    Fitting the slits of the fins with slits into the joint of the two heat pipes;
    The manufacturing method of the cooler characterized by including.
14. The manufacturing method according to claim 13, wherein the L-shaped heat pipe is formed by bending a flat heat pipe into an L-shape.
15. An L-shaped heat pipe is prepared by preparing a flat first heat pipe having a ridge on the side and a flat second heat pipe having a groove on the side, and a ridge of the adjacent heat pipe, The manufacturing method according to claim 14, wherein the groove is fitted and formed by bending a flat continuous heat pipe into an L shape.
16. The part of the heat pipe that comes into contact with the fin is made of a clad material in which the melting point of the outer metal is lower than the melting point of the inner metal, and the fin is bonded to the heat pipe by melting the outer metal. The manufacturing method according to any one of claims 13 to 15.
17. The joining portion between the heat pipes is made of a clad material in which the melting point of the outer metal is lower than the melting point of the inner metal, and the heat pipes are joined by melting the outer metal. Item 17. The production method according to any one of Items 12 to 16.

Images