JP2013032898A - Laminated heat sink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small heat sink that facilitates manufacture and has high cooling efficiency, and to provide a method of manufacturing the same.SOLUTION: This heat sink includes: a cooling plate in which a plurality of flow channel plates having through-holes serving as a cooling medium flow channel are laminated and sealing plates serving as sealing surfaces of the flow channels are arranged at both sides, wherein one or more flow channel through-holes are formed in the flow channel plate; and a header plate which is arranged between the cooling plate and each of the sealing plates and in which a header through-hole connected to all of the flow channel through-holes is formed, wherein the sealing plate or the header part is provided with a cooling medium inflow/outflow opening, and a heat generating body is installed on an outside surface of a lamination cross section. In the heat sink, cooling medium flows in and lamination direction of the flow channel plates.

Description

The present invention relates to a laminated heat sink having high cooling efficiency.

In an automobile having an electric drive device such as a hybrid vehicle or an electric vehicle, an inverter / converter circuit is used to store direct current and alternating current using a storage battery to supply power to the drive motor and store external power or self-generated power. Conversion and frequency conversion are performed. Since such a circuit uses a PCU (power control unit) including a semiconductor element, it is necessary to effectively remove generated heat. Therefore, a heat sink (cooler) for heat dissipation is essential.

For example, in Patent Document 1, a pair of header openings and a plurality of slits are provided, and a first intermediate plate and a second intermediate plate in which the plurality of slits are formed in different patterns are laminated, and both outer layers thereof are laminated. A stacked cooler in which the header openings of the first intermediate plate and the second intermediate plate communicate with each other and the slits communicate with each other to form a cooling channel. The first and second intermediate plates each have a connecting portion for connecting ribs between adjacent slits, and the connecting portions are provided at both ends of the slit and communicate with each other. The sizes of the openings differ between the two plates, and the end of the slit provided in one of the plates communicates with the header opening provided in the other plate. Laminated cooler is disclosed, wherein.

In the technique of the above document, since the intermediate plates are stacked and moved in a slit provided in the plates, it is difficult to secure a sufficient refrigerant flow rate because the flow path is narrow and the flow resistance is increased. Moreover, although two types are required as an intermediate | middle plate, the method of alignment before joining is not described. Furthermore, since the refrigerant flows in a direction perpendicular to the stacking direction of the intermediate plates, heat transfer is performed only through the bonding portion of the intermediate plate via the bonding member. Therefore, even if the thermal conductivity of the intermediate plate is high, the thermal conductivity of the entire unit depends on the thermal conductivity of the joining member.

Moreover, in patent document 2, it is a lamination | stacking module structure formed by laminating | stacking multiple module units which have a semiconductor module and the cooler which cools this semiconductor module, Comprising: The said semiconductor module is from a double-sided heat dissipation module. The one side of the semiconductor module in each module unit and the cooler are joined by brazing, and when the module units are stacked, the other side of the semiconductor module in one adjacent module unit A laminated module structure is disclosed in which a grease layer is interposed between the first module and the cooler in the other module unit.

In the technique of this document, corrugated cooling fins and spring members are disposed in the cooler, and the cooling fins are brazed to the cooler case. Therefore, this technique also has a problem that the flow resistance is large as in Patent Document 1, and the heat conduction efficiency of the unit is influenced by the brazing member. Further, since corrugated cooling fins are used, there is a problem that the structure is complicated and the manufacturing cost is increased.

JP 2002-164489 A JP 2010-135697 A

The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a laminated heat sink that is easy to manufacture, has low flow resistance, and high thermal conductivity.

In order to solve the above problems, the laminated heat sink according to the present invention is formed by laminating a plurality of flow path plates having through holes that serve as refrigerant flow paths, and sealing plates that serve as sealing surfaces of the flow paths are disposed on both sides. The flow path plate includes a cooling plate in which one or more flow path through holes are formed, and a header portion through hole that is disposed between the cooling plate and each of the sealing plates and connected to all of the flow path through holes. A heat sink having a refrigerant inlet / outlet provided on a laminated cross section of the outer surface of the sealing plate or the header portion, and configured such that the refrigerant flows in a direction in which the flow path plates are laminated. Features.

Each of the flow path plate and the sealing plate is formed with a plurality of embossed portions having a concave portion on one side and a convex portion on the opposite surface side. It is desirable that the embossed portion is fitted and connected.

Further, a low melting point metal layer is provided on a contact surface between each sealing plate and each flow path plate, and each sealing plate and each flow path plate are joined by melting of the low melting point metal layer. It is preferable that

The low melting point metal layer preferably has a lower melting point than both the flow path plate and the sealing plate, and the base material of the flow path plate and the sealing plate may be aluminum, copper, or iron. As the low melting point metal layer, silver or an alloy thereof is particularly preferable when the base material is iron or copper, and an aluminum alloy is particularly preferable when the base material is an aluminum substrate. The purpose of the heat sink is to efficiently absorb heat from the heating element and conduct heat to the refrigerant in the refrigerant flow path of the heat sink. Therefore, the material of the flow path plate and sealing plate is copper / aluminum material with good thermal conductivity (Aluminum brazing material) is often used. In the case of a copper base material, a material having a good thermal conductivity is required as a material for joining laminates, and a material having a lower melting point than the joining material and a good thermal conductivity is solder. Alloys or silver materials are common materials. However, since an internal pressure for circulating the refrigerant liquid is generated in the refrigerant flow path, a silver material that is stronger than the solder alloy in strength is used, and this is good from the viewpoint of thermal conductivity. Usually, pure copper has a melting point of 1080 degrees and silver has a melting point of 960 degrees. When the melting temperature for bonding is around 1000 degrees, it is close to the melting temperature of the flow path plate and is likely to cause shape deformation and the like. I can't. In order to solve these problems, when the base material is a copper material, the low melting point metal layer can be prevented by interposing silver plating or silver foil.
The reason for this is that the laminated surface of the flow path plate and the sealing plate made of copper material are in close contact with each other by the fitting of the embossed part with a low melting point metal layer interposed, As the temperature is raised, the intermetallic diffusion phenomenon on the contact surface begins, causing eutectic formation of the silver alloy, and the alloyed state is realized at a relatively low temperature. The melting temperature of the silver alloy is determined by the contents of copper and silver, and from the existing alloy phase diagram, even if the content is half and half, it melts at around 800 degrees. (In the existing copper-silver alloy phase diagram, the melting temperature is 780 ° C for 40% silver and 60% copper) Deformation of the laminated member occurs because the bonding temperature can be lowered by lowering the bonding temperature relative to the melting temperature of the copper material. Good bonding conditions can be set.

The flow path plate can be made of an iron material in consideration of its use and cost, but the low melting point metal layer in that case is preferably copper. Compared to a combination of iron and tin, the combination of iron and copper can dramatically increase the strength of interlaminar bonding and increase the reliability.

The flow path through holes formed in the cooling plate can be a plurality of independent through holes, or a part of them can be a continuous through hole.

The remaining portion, that is, the fin portion located between the flow passage through holes of the cooling plate is formed so that the peripheral remaining portion on the radiator mounting portion side of the cooling plate, that is, the long side of the frame portion is wider than the central portion of the flow passage. It is also suitable for heat dissipation.

The remaining part located between the flow-through holes of the cooling plate, that is, the fin part, is thinner in one or both sides than the thickness of the cooling plate in the stacking direction, and the outer peripheral part of the cooling plate leaves the plate thickness between the fin parts. It is also preferable in terms of heat dissipation to create an air gap and bring the coolant into contact with the coolant over the entire fin portion.

The remaining portion, that is, the fin portion located between the flow passage through holes of the cooling plate is made thinner in one or both sides than the thickness of the cooling plate in the stacking direction, and a part or all of the fin portion is made in the cooling flow passage direction. Also, it becomes a cooling plate having a rake angle, and positively flowing the refrigerant between the fin portions can further improve the heat dissipation effect.

It is also possible to form a composite of a plurality of heat sink units by integrally forming a plurality of independent refrigerant channels and refrigerant inflow / outlet in parallel.

According to the present invention, an embossed portion is provided on each of the sealing plate and the thin metal plate, and the embossed portions are fitted and connected to each other at the time of stacking, thereby easily and reliably positioning each other and further holding them integrally. Is possible. Thereby, when joining a sealing plate and each metal thin plate, it is only necessary to raise the temperature and melt the low melting point metal layer without applying pressure.
It is also possible to change the heat sink to the size of the heating element by adjusting the number of cooling plates. Therefore, a small heat sink that is easy to manufacture and has high cooling efficiency can be provided. Moreover, since the embossed part is formed so that one side is a concave part and the opposite side is a convex part, it can be formed by simple press working.

Further, according to the present invention, since the flow path plates are stacked and the refrigerant flows in the flow direction of the flow path plates, the size and flow of the cooling target can be changed by changing the shape and number of the flow path plates. The resistance can be freely changed, and heat conduction between the refrigerant and the external heating element can be performed directly through the cross section of only the flow path plate without other inclusions, so that high heat conduction efficiency can be obtained.

Further, the remaining portion located between the flow path through holes of the cooling plate, that is, the fin portion is formed so that the peripheral remaining portion on the heating element mounting side of the cooling plate, that is, the long side of the frame portion is widened. The heat transfer can be facilitated, and the cooling efficiency can be further increased.
In addition, a part or the whole of the fin portion of the cooling plate is thinned on one side or both sides in the stacking direction so as to provide a gap between the stacks, and a rake angle is provided in the flow path direction so that the refrigerant is interposed between the fins. It can pass and further cooling effect can be expected.

It is also possible to simultaneously cool a plurality of objects to be cooled by integrally forming a plurality of independent refrigerant channels and refrigerant inflow / outlet in parallel to form a parallel composite of a plurality of heat sink units.

Hereinafter, preferred embodiments of a heat sink according to the present invention will be described with reference to the drawings. FIG. 1 shows a main part assembly diagram of an embodiment of a heat sink according to the present invention. A plurality of flow path through holes 32 are formed in the elongated cooling plate 3 in parallel with the short side direction, and a number of the cooling plates 3 having a desired depth are stacked. A plurality of header plates 2 </ b> A and 2 </ b> B each having a header portion through hole 31 are stacked on both sides of the cooling plate 3 and coupled to the cooling plate 3. Sealing plates 1A and 1B for closing the refrigerant flow path are arranged on both sides of the header plates 2A and 2B. These sealing plates 1A and 1B are provided with refrigerant inflow / outflow ports 11A and 11B for taking in and out the refrigerant.
In addition, if the inlet and outlet of the refrigerant cannot be installed on the sealing plate due to the arrangement of the heat sink, it can be provided on the header portions (four external surfaces) at both ends of the stacked cooling plates.

On the cooling plate 3, the header plates 2A and 2B, and the sealing plates 1A and 1B, embossed portions 21 formed so that one side is convex and the opposite side is concave are arranged at corresponding locations at a plurality of surrounding locations. It can be temporarily fixed in an accurate positional relationship by caulking each other. Although not shown, each of the cooling plate 3, the header plates 2A and 2B, and the sealing plates 1A and 1B has a low melting point metal layer having a melting point lower than that of the respective base material on one surface. The heat sink can be completed by melting and sealing the low melting point metal layer and joining and sealing the whole. As the low melting point metal layer, a silver layer having a thickness of 5 microns can be used.

FIG. 2 is a perspective view of the completed body of the above-described embodiment, and a plurality of heating elements can be placed on the upper surface of the heat sink body and used for cooling.
In this example, the heat-dissipating surface of the heating element is flat, so the heat-receiving part of the heat sink is also flat, but if the outer shape is round or square like a motor, in order to remove the heat generated by the motor, A laminated structure (round shape, semicircle shape, square shape, half angle shape, etc.) matched to the shape of the heat radiating surface of the heating element can be easily formed by pressing, and the cooling effect is not different from the description.

FIG. 3 is a side view (a) and a front view (b) of the embodiment shown in FIG. The refrigerant introduced from the inflow port 11A is guided to the plurality of flow paths 32 from the header portion 31, flows in the direction perpendicular to the cooling plate 3, and is discharged from the outflow port 11B. Therefore, the cooling effect can be enhanced by adjusting the flow resistance by devising the shape of the flow path through hole 32.

FIG. 4 shows another shape of the cooling plate 3 in the embodiment shown in FIG. (A) is an elliptical shape, (c) is an array of circular holes, and (d) is a waveform. As for the flow-through holes, the rectangle in FIG. 1, the ellipse in (a) and the circle in (c) are an assembly of independent through-holes, but in (d), they are integrated through-holes. Yes. As for the cooling plate 3 of (a) and (d), the fin portion 33 between the flow path through holes 32 is formed to be wide near the upper and lower surfaces of the cooling plate 3. With this configuration, heat transfer from the vertical direction of the cooling plate 3 and heat exchange with the refrigerant can be made more efficient. Thus, there is no restriction | limiting about the shape of a through-hole, It can change according to the objectives, such as the mounting surface of the heat generating body, the number of mounting, and the magnitude | size of the emitted-heat amount. FIG. 4B shows a partial cross-sectional view of the state when these cooling plates 3 are stacked. Each cooling plate 3 is fitted and connected to each other by an embossed portion 21. Although not shown in the drawing, a low-melting point metal layer is provided between the cooling plates and finally joined by melting.

FIG. 5 shows another shape of the fin portion with respect to the fin portion of the cooling plate shown in FIG. (A) is a front view of a cooling plate, (b) is a sectional view of the cooling plate, fin portions are thinned from both sides, and (c) is a sectional view in which cooling plates are laminated. As a result, a gap through which the liquid can permeate in a direction perpendicular to the coolant flow path is formed.
In order to further improve the heat sink cooling effect, (d) shows a method of tilting the entire fan in one direction, and (e) shows a structure in which the fins are tilted in a staggered direction toward the flow-through hole, and the refrigerant is actively used. If the pressure of the refrigerant is adjusted and the refrigerant flows between the inclined fins by combining the header-plate hole arrangement described below and this staggered inclined row, the refrigerant flows into the fins. Further, the cooling effect is enhanced.
Further, (f) shows a method of thinning the fin portion by using a drawing method with a press or the like as a method of thinning the fin thickness direction.

FIG. 6 shows another embodiment according to the present invention. The heat sink of this embodiment has a shape in which the single heat sink units shown in FIG. 2 are arranged side by side, but the sealing plates 1A and 1B, header plates 2A and 2B, and the flow path plate 3 are all units. It is formed as one piece. By adopting this configuration, the cooling efficiency can be increased because the refrigerant can be supplied to each heating element 12.

In FIG. 7, the shape of the header plate is devised so that the refrigerant can be uniformly supplied to the plurality of flow paths. Furthermore, a header plate configuration for increasing the cooling efficiency was shown. (C), (d), (e) are embodiments of the header plate, and the refrigerant liquid pressure changes with respect to the passage surface of the through hole of the cooling plate 3 depending on the arrangement and size of the refrigerant inflow / outlet, and cooling. Since a uniform refrigerant flow cannot be created in the through hole, the arrangement of the flow passage through holes in the header plate is not uniform. Specifically, the left and right sides of the header plate 3 have a large total cross-sectional area of the through holes. Before the refrigerant enters the through hole, the refrigerant is disposed as a pressure adjustment refrigerant pool. As a result, a large amount of refrigerant flows near the outer periphery of the cooling plate 3 to promote cooling of the cooling plate 3. (B) is a header plate 2A having a uniform through hole. For implementation, an adjustment header plate (c), (d), (e) is inserted between the header plate (b) and the cooling plate. Is also possible.
By laminating these as shown in (a), a large amount of refrigerant is guided along the flow path 32 to the left and right sides.

In manufacturing the heat sink according to the present invention described above, the sealing plates 1A and 1B, the header plates 2A and 2B, and the flow path plate 3 are thin plates. 21 can be formed integrally. A low melting point metal layer can be provided in advance on at least one surface of each element plate. If a progressive die or the like is used, it is possible to continuously form each of the above-described base materials and to integrate them by fitting and bonding by laminating pressure.

For example, if the base material is copper, the integrated heat sink assembly is put in a high-temperature bath of about 830 ° C., and the low-melting metal layer is melted and then cooled. In this example, silver is used as the low melting point metal layer, but other materials such as other silver alloys or solders can be selected according to the type of the sealing plate or metal thin plate.

In this heat sink prototype, the metal thin plate was made of copper and the low melting point metal layer was plated with silver. However, considering other heat dissipation applications, the metal thin plate was made of iron, which is compatible with iron. The types of melting point metal layer materials and melting furnaces for joining them were also examined in parallel.
Two types of tin and copper were investigated as low melting point metal layer materials that have a lower melting point than iron materials and can be easily implemented, and a joining test was conducted using three types of melting furnaces: electric furnace, non-oxidizing furnace, and brazing furnace. .
The following is the joint tensile strength test data performed.
* Low melting point material is tin, thickness 3μm, 0.8kg to 1kg / mm ^{2 in} electric furnace
* Low melting point material is tin, thickness 5μm, 1Kg / mm ^{2 for} electric furnace ²
* Low melting point material is tin, thickness 3μm, 7kg to 8kg / mm ² in non-oxidizing furnace
* Low melting point material is tin, thickness 5μm, non-oxidizing furnace 5kg-4Kg / mm ²
* Low melting point material is tin, thickness 3μm, 65kg-70Kg / mm ^{2 in} brazing furnace
* Low melting point material is tin, thickness 5μm, 60Kg-65Kg / mm ^{2 in} brazing furnace
From the above results, even if a non-oxidizing furnace is used for tin, the flowability is poor due to the surface oxidation phenomenon at the time of melting, and a stable bonding state cannot be obtained.
Regarding the thickness, the strength is slightly stable at 3 μm than 5 μm.
As a result, when the metal thin plate material was iron, the copper material could be stably secured as the low melting point metal layer.

As described above, according to the present invention, a small heat sink that is easy to manufacture and has high cooling efficiency can be provided. Therefore, the present invention can greatly contribute to the cooling field of electric and electronic devices including the automobile industry.

It is an assembly drawing which shows the structure of the heat sink by this invention. 1 is a perspective view of a heat sink according to the present invention. (A) is a side view of the heat sink shown in FIG. 2, (b) is a front view. (A), (c), (d) is a figure which shows another embodiment and connection state of the cooling plate used for the heat sink by this invention shown in FIG. 1, (b) is a connection state of these cooling plates. FIG. (A), (b), and (c) allow the refrigerant liquid to permeate in the direction of the fin plate, and (d) and (e) indicate that each of the fins can positively flow the refrigerant liquid between the fins. 2 is a drawing of a cooling plate having a rake angle in the direction of the flow path of the refrigerant liquid. Further, (f) is a cross-sectional view of a diaphragm structure for providing a gap between fins. It is a perspective view which shows another Example of the heat sink by this invention. (B) is a front view showing an example of a header plate, (c), (d) and (e) are front views showing another embodiment of the header plate, and (a) is a part when these are assembled. It is sectional drawing.

1A, 1B Sealing plate 2A, 2B Header plate 3 Cooling plate 10 Heat sink body 11A, 11B Inlet / outlet 12 Heating element 21 Embossed portion 31 Header portion through-hole 32 Channel passage through-hole 33 Fin portion

Claims (7)

A plurality of flow path plates having through holes serving as refrigerant flow paths are stacked, sealing plates serving as sealing surfaces of the flow paths are disposed on both sides, and the flow path plate has one or more flow path through holes formed therein. A cooling plate, and a header plate formed between the cooling plate and each of the sealing plates and formed with header part through holes connected to all of the flow path through holes, the sealing plate or A heat sink in which a refrigerant inlet / outlet is provided in a header portion and a heating element is installed on an outer surface of a laminated cross section, wherein the refrigerant flows in a direction in which the flow path plates are laminated. The laminated heat sink according to claim 1, wherein the flow path through holes formed in the cooling plate are partially continuous through holes. The remaining portion, that is, the fin portion located between the flow path through holes of the cooling plate is formed so that the peripheral remaining portion of the cooling plate, that is, the long side of the frame portion is wide. The laminated heat sink according to any one of the above. The laminated heat sink according to any one of claims 1 to 3, wherein the header part through hole is a through hole that is regulated so that the refrigerant flows uniformly or in an intended direction in the flow path through hole of the cooling plate. The laminated heat sink according to any one of claims 1 to 4, wherein a plurality of independent refrigerant flow paths and a refrigerant inflow / outlet are integrally formed in parallel. 2. The cooling plate in which the remaining portion, that is, the fin portion located between the flow path through holes of the cooling plate is thinner than the thickness of the cooling plate in the stacking direction, and the outer peripheral portion is a cooling plate that retains the thickness of the cooling plate. 6. The laminated heat sink according to any one of 1 to 5. The laminated heat sink according to any one of claims 1 to 6, wherein a cooling plate having a rake angle with respect to the direction of the refrigerant flow path in part or all of the fin portion.

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