COOLER

FIELD

[0001]The present disclosure relates to a cooler for cooling an element using a refrigerant circulated by a pump.

BACKGROUND

[0002]Patent Literature 1 discloses a conventional cooler for cooling a semiconductor power device. The cooler described in Patent Literature 1 includes a substrate assembly, which includes a manifold layer, a channel layer, a ceramic layer, and a metal layer stacked sequentially and joined together, and a plenum housing having an inlet port and an outlet port. The manifold layer branches a flow of cooling water, which is a refrigerant, flowing from the inlet port of the plenum housing into inlet manifolds, which are multiple channels, and supplies the cooling water to the channel layer. In addition, the manifold layer receives flows of the cooling water that have passed through the channel layer by outlet manifolds, which are multiple channels, and merges the flows of the cooling water into the outlet port of the plenum housing. In the manifold layer, the inlet manifolds and the outlet manifolds extending in a first direction are arranged alternately at a predetermined spacing in a second direction. The channel layer is a layer that supplies the cooling water from the manifold layer to channels extending in the second direction, and returns the cooling water that has flowed through the channels back to the manifold layer. In the channel layer, the multiple channels extending in the second direction are disposed on a side nearer to the joint surface with the manifold layer, at a predetermined spacing in the first direction. The ceramic layer is formed of a highly thermally conductive material. The metal layer is connected to a semiconductor power device to be cooled.

[0003]In the cooler described in Patent Literature 1, when the cooling water flows in from the inlet port of the plenum housing, the cooling water flows through the inlet manifolds of the manifold layer and then through the channels of the channel layer, and is discharged from the outlet port of the plenum housing via the outlet manifolds of the manifold layer. This causes heat generated by the semiconductor power device and transferred via the metal layer and the ceramic layer to be removed by the cooling water flowing through the channel layer.

CITATION LIST

Patent Literature

[0004]Patent Literature 1: Japanese U.S. Pat. No. 5,711,459

SUMMARY OF INVENTION

Problem to be Solved by the Invention

[0005]A heat-generating element such as a laser element whose temperature dependency directly affects oscillation performance desirably has a regular temperature distribution. Changing the generated heat distribution of such heat-generating element through adjustment of the pattern design, or adjustment of the amount of electrical current, inside the element can provide adjustment of the temperature distribution. However, making a design taking into account such adjustment of temperature distribution is not easy. For simpler design, a temperature distribution that is concentric and small is also preferred. Meanwhile, in the foregoing conventional technology, the cooling water flows through the channel layer in contact with the ceramic layer in a single direction, which is the direction of the channels formed to extend in the second direction. This presents a problem of a non-concentric temperature distribution and a significant change in the temperature along the flow direction of the cooling water.

[0006]The present disclosure has been made in view of the foregoing, and it is an object of the present disclosure to provide a cooler capable of bringing the temperature distribution caused by the cooler more concentric, and of reducing the temperature distribution inside an element to smaller than the temperature distribution of the conventional technology.

Means to Solve the Problem

[0007]To solve the problem and achieve the object described above, a cooler according to the present disclosure is a cooler to be joined to an element to cool the element, the cooler comprising: a base layer to which the element is to be joined; a fin-formed layer including a fin arrangement area having a plurality of fins disposed therein, the fins being connected to the base layer; and an opening-formed layer connected to the fin-formed layer and including a plurality of fin inflow ports and a plurality of fin outflow ports, the fin inflow ports allowing flow of a refrigerant to the fin arrangement area. The plurality of fin inflow ports are connected with an inlet port via an inflow channel, the inlet port being a port into which the refrigerant of the cooler flows. The plurality of fin outflow ports are connected with an outlet port via an outflow channel, the outlet port being a port out of which the refrigerant of the cooler flows. The plurality of fin inflow ports and the plurality of fin outflow ports are arranged alternately and in parallel to one another in a direction radially away from a point in an area of projection of a shape of the element onto the opening-formed layer.

Effects of the Invention

[0008]A cooler according to the present disclosure provides an advantageous effect in capability of bringing the temperature distribution caused by the cooler more concentric, and of reducing the temperature distribution inside an element to smaller than the temperature distribution of the conventional technology.

BRIEF DESCRIPTION OF DRAWINGS

[0009]FIG. 1 is a cross-sectional view schematically illustrating an example of configuration of a cooler according to a first embodiment.

[0010]FIG. 2 is a top view illustrating, in an exploded manner, a configuration of each layer of the cooler according to the first embodiment.

[0011]FIG. 3 is a diagram for describing an example of flow of refrigerant in the cooler according to the first embodiment.

[0012]FIG. 4 is a diagram illustrating an example of flow of refrigerant in an opening-formed layer of the cooler according to the first embodiment.

[0013]FIG. 5 is a diagram illustrating an example of relationship between an element placement area and the opening-formed layer constituting the cooler according to the first embodiment.

[0014]FIG. 6 is an enlarged top view of a portion of the opening-formed layer.

[0015]FIG. 7 is a top view illustrating another example of the configuration of the opening-formed layer constituting the cooler according to the first embodiment.

[0016]FIG. 8 is a top view illustrating still another example of the configuration of the opening-formed layer constituting the cooler according to the first embodiment.

[0017]FIG. 9 is a top view illustrating still another example of the configuration of the opening-formed layer constituting the cooler according to the first embodiment.

[0018]FIG. 10 is a top view illustrating still another example of the configuration of the opening-formed layer constituting the cooler according to the first embodiment.

[0019]FIG. 11 is a top view illustrating still another example of the configuration of the opening-formed layer constituting the cooler according to the first embodiment.

[0020]FIG. 12 is a top view schematically illustrating a positional relationship between an opening portion of the opening-formed layer and a groove in a fin arrangement area arranged in a fin-formed layer.

[0021]FIG. 13 is a partially-enlarged top view illustrating an example of configuration of the fin-formed layer constituting the cooler according to the first embodiment.

[0022]FIG. 14 is a top view illustrating another example of the configuration of the fin-formed layer constituting the cooler according to the first embodiment.

[0023]FIG. 15 is an enlarged top view of a portion of the fin arrangement area of the fin-formed layer of FIG. 14.

[0024]FIG. 16 is a top view illustrating an example of configuration of the opening-formed layer associated with the fin-formed layer of FIG. 14.

[0025]FIG. 17 is a cross-sectional view schematically illustrating an example of configuration of a cooler according to a second embodiment.

[0026]FIG. 18 is a top view illustrating an example of configuration of a channel-formed layer constituting the cooler according to the second embodiment.

[0027]FIG. 19 is a diagram illustrating an example of the opening-formed layer and the channel-formed layer as stacked one on top of the other.

[0028]FIG. 20 is a cross-sectional view schematically illustrating an example of configuration of a cooler according to a third embodiment.

[0029]FIG. 21 is a top view illustrating an example of configuration of a channel connection layer constituting the cooler according to the third embodiment.

[0030]FIG. 22 is a top view illustrating an example of configuration of a channel distribution layer constituting the cooler according to the third embodiment.

[0031]FIG. 23 is a top view illustrating an example of configuration of an inlet-outlet arrangement layer constituting the cooler according to the third embodiment.

[0032]FIG. 24 is a top view illustrating an example of the configuration of the channel connection layer constituting the cooler according to the third embodiment.

DESCRIPTION OF EMBODIMENTS

[0033]A cooler according to embodiments of the present disclosure will be described in detail below with reference to the drawings.

FIRST EMBODIMENT

[0034]FIG. 1 is a cross-sectional view schematically illustrating an example of configuration of a cooler according to a first embodiment. An element 100, which is an object to be cooled, is joined to a cooler 10 with a heat conduction layer 101, which provides electrical insulation, interposed therebetween. The element 100 is an element induced to generate heat during operation thereof, such as a laser element. The heat conduction layer 101 is a layer for transferring heat from the element 100 to the cooler 10, and is formed of a material that is electrically insulating and is highly thermally conductive, that is, easily transfers heat. The heat conduction layer 101 and the element 100 are joined together using a bonding material. Examples of the material of the heat conduction layer 101 include ceramics such as aluminum nitride (AlN), aluminum oxide (Al₂O₃), and AlSiC, and diamond. The heat conduction layer 101 also functions to prevent possible breakage of the element 100 caused by stress that is generated when being joined to the cooler 10 due to difference in thermal expansion coefficient between the element 100 and the cooler 10. When no electrical insulation is provided for the element 100 by using the heat conduction layer 101, stress that is generated when being joined to the cooler 10 due to difference in thermal expansion coefficient may be controlled by using copper-tungsten (CuW), copper-molybdenum (CuMo), or the like. Moreover, when no electrical insulation is necessary and the difference in thermal expansion coefficient between the element 100 and the cooler 10 will impose no problem depending on usage, the element 100 may be directly joined to the cooler 10 using a bonding material therebetween without using the heat conduction layer 101. Note that when the element 100 is disposed on the cooler 10 with the heat conduction layer 101 interposed therebetween, electrical conduction for the element 100 is provided by connection of a pattern of a thin film such as a copper (Cu) film formed on the heat conduction layer 101 and electrodes around the element 100 by wire bonding or the like. In one example, the heat conduction layer 101 is joined to the cooler 10 using a bonding material therebetween.

[0035]The cooler 10 is a device that is joined to the element 100 to cool the element 100 using a refrigerant circulated by a pump (not illustrated). The cooler 10 according to the first embodiment roughly includes seven metal layers. That is, the cooler 10 includes, in order from near to far from the layer on which the element 100 is disposed, a base layer 1, a fin-formed layer 2, an opening-formed layer 3, a channel-formed layer 4, a channel-formed layer 5, a channel connection layer 6, and an inlet-outlet arrangement layer 7. These layers are each formed of a metal layer. These layers can each be formed using a metal having good thermal conductivity such as Cu or aluminum (Al). In addition, in this example, the layers of the cooler 10 are rectangular. Note that the cooler 10 is herein divided into multiple layers focusing on the functionality of each metal layer, and the cooler 10 is not necessarily formed of physically separate metal layers being joined together. In addition, a single layer may be formed of physically separate multiple layers. The stacking direction of the metal layers is hereinafter referred to as Z-axis direction. In addition, two positions along the Z-axis direction are designated using words of upper and lower.

[0036]A configuration of each of the layers included in the each cooler 10 will next be described. FIG. 2 is a top view illustrating, in an exploded manner, a configuration of each of the layers of the cooler according to the first embodiment. Note that the origin is the center of a projection area. The projection area, which is on the top surface of the opening-formed layer 3, is an area onto which the area having the element 100 disposed therein is projected. In addition, the X-axis passes through the origin and extends in the direction parallel to the longer side of the opening-formed layer 3 having a rectangular shape, and the Y-axis passes through the origin and extends in the direction parallel to the shorter side of the opening-formed layer 3 having a rectangular shape. The X-axis, Y-axis, and Z-axis are perpendicular to each other. Note that this is by way of example, and the X-axis and Y-axis can be determined arbitrarily.

[0037]The base layer 1 is a metal layer on top of which the element 100 is disposed directly or with the heat conduction layer 101 interposed therebetween. The base layer 1 serves as a base plate. The base layer 1 is a flat-plate-shaped metal layer. In the figure, the area R100 indicates an element placement area, which is the area in which the element 100 is disposed, and the area R101 indicates a heat conduction layer placement area, which is the area in which the heat conduction layer 101 is disposed. This example assumes that, in the element placement area R100, the element 100 is disposed to have the center of the element 100 positioned at the center on the XY-plane of the base layer 1. The heat conduction layer placement area R101 encompasses the element placement area R100, and is larger than the element placement area R100.

[0038]The fin-formed layer 2 is a metal layer that is disposed under the base layer 1, and is connected to the base layer 1. The fin-formed layer 2 includes multiple fins 21 connected to the base layer 1 to improve cooling performance, in an area including at least the area onto which the element placement area R100 is projected. The area in which the fins 21 are formed is herein referred to as fin arrangement area R20. In the fin arrangement area R20, the multiple fins 21 are arranged in a periodic arrangement in a two-dimensional plane in one example. Each pair of the fins 21 forms therebetween a groove 22, which serves as a channel for the refrigerant. An example of the fins 21 is a pin fin extending in the Z-axis direction and having one end connected to the base layer 1. Each pair of pin fins forms therebetween the groove 22, which is an opening formed between these pin fins functioning as side walls. Note that the groove 22 on the bottom surface of the metal layer forming the fin-formed layer 2 functions as an opening portion to the fin arrangement area R20 in the Z-axis direction. The area other than the fin arrangement area R20 of the fin-formed layer 2 has a plate shape.

[0039]The base layer 1 and the fin-formed layer 2 can be produced using various production methods. In one example, etching of a single metal layer to form the groove 22 allows the base layer 1 and the fin-formed layer 2 to be formed integrally. Specifically, a mask is formed on the area other than the fin arrangement area R20 on the bottom surface of a single metal layer and on portions for producing the pin fins in the fin arrangement area R20. Then, etching the bottom surface of the metal layer having the mask formed thereon to a predetermined depth results in formation of the groove 22 in the areas having no masks formed thereon. That is, in the fin arrangement area R20, the groove 22 is formed in portions where no mask has been formed, and the portions of the surface where the mask has been formed remain. These remaining portions become the pin fins extending in the Z-axis direction. Note that when etching is finished when the depth of the groove 22 has reached a predetermined value, a section having a thickness in which the groove 22 is formed becomes the fin-formed layer 2, and a section having another thickness becomes the base layer 1. As such, although the base layer 1 and the fin-formed layer 2 are illustrated in FIGS. 1 and 2 as two separate layers for illustration purpose, the base layer 1 and the fin-formed layer 2 are produced from a single metal block. Note that use of etching technique to produce the base layer 1 and the fin-formed layer 2 is by way of example, and another method can be used for production. In one example, the base layer 1 and the fin-formed layer 2 may be produced by metallic mold casting or formed by cutting from a block of metallic material. Alternatively, as described later, production by stacking metal layers is also applicable.

[0040]The opening-formed layer 3 is a metal layer including opening portions that serve as fin inflow ports 31 and fin outflow ports 32, the fin inlet ports allowing the flow of refrigerant flow to the fin arrangement area R20. The opening-formed layer 3 includes the fin inflow ports 31 and the fin outflow ports 32 in an area including at least the area onto which the element placement area R100 is projected. The fin inflow ports 31 supply the refrigerant to the fin arrangement area R20. The fin outflow ports 32 discharge the refrigerant from the fin arrangement area R20. The fin inflow ports 31 and the fin outflow ports 32, which are opening portions, are arranged alternately and in parallel to one another in a direction radially away from a point in the area onto which the element placement area R100 is projected. In this example, such a point, which is the origin, is in the area onto which the element placement area R100 is projected. The fin inflow ports 31 and the fin outflow ports 32 penetrate through the metal layer in the Z-axis direction. In this example, the fin inflow ports 31 and the fin outflow ports 32 are each defined by multiple opening portions extending in different directions and having individual end portions connected together. Specifically, the fin inflow ports 31 and the fin outflow ports 32 are defined by opening portions each defined by an opening portion extending in the X-axis direction and an opening portion extending in the Y-axis direction, the opening portions having their end portions connected together. The X-axis direction is an example of first direction, and the Y-axis direction is an example of second direction. A configuration of the opening portions of the opening-formed layer 3 will be described later in detail. The opening-formed layer 3 has a top surface, where the opening-formed layer 3 is joined to the fin-formed layer 2.

[0041]The channel-formed layer 4 is a metal layer including channels that guide a refrigerant flowing in from the channel-formed layer 5 to predetermined opening portions of the opening-formed layer 3 and guide the refrigerant discharged from predetermined opening portions of the opening-formed layer 3 to the channel-formed layer 5. The channel-formed layer 4 includes refrigerant inflow channels 41, which each constitute a part of a channel that transfers the refrigerant to the fin arrangement area R20, and refrigerant outflow channels 42, which each constitute a part of a channel that discharges the refrigerant from the fin arrangement area R20. The refrigerant inflow channels 41 and the refrigerant outflow channels 42 penetrate through the metal layer in the Z-axis direction. The channel-formed layer 4 has a top surface, where the channel-formed layer 4 is joined to the opening-formed layer 3.

[0042]The channel-formed layer 5 is a metal layer including channels that guide a refrigerant flowing in from the channel connection layer 6 to the refrigerant inflow channels 41 of the channel-formed layer 4 and guide the refrigerant discharged from the refrigerant outflow channels 42 of the channel-formed layer 4 to the channel connection layer 6. The channel-formed layer 5 includes refrigerant inflow channels 51, which each constitute a part of the channel that transfers the refrigerant to the fin arrangement area R20, and refrigerant outflow channels 52, which each constitute a part of the channel that discharges the refrigerant from the fin arrangement area R20. The refrigerant inflow channels 51 and the refrigerant outflow channels 52 penetrate through the metal layer in the Z-axis direction. The refrigerant inflow channels 51 and the refrigerant outflow channels 52 are formed by openings extending in the X-axis direction. In addition, the refrigerant inflow channels 51 and the refrigerant outflow channels 52 are arranged alternately in the Y-axis direction. The refrigerant inflow channels 51 and the refrigerant outflow channels 52 have a same length, but are arranged to have end portions thereof positioned at different positions in the X-axis direction. In this example, the refrigerant inflow channels 51 and the refrigerant outflow channels 52 are arranged in such a manner that a first end portion, which is an end portion in the positive X-axis direction, of each of the refrigerant inflow channels 51 protrudes in the positive X-axis direction with respect to the first end portions of the refrigerant outflow channels 52, and that a second end portion, which is an end portion in the negative X-axis direction, of each of the refrigerant outflow channels 52 protrudes in the negative X-axis direction with respect to the second end portions of the refrigerant inflow channels 51. An area including the end portions in the positive X-axis direction in which the positions of disposition of the refrigerant inflow channels 51 do not overlap the positions of disposition of the refrigerant outflow channels 52 is herein referred to as refrigerant inflow area R53. An area including the end portions in the negative X-axis direction in which the positions of disposition of the refrigerant outflow channels 52 do not overlap the positions of disposition of the refrigerant inflow channels 51 is herein referred to as refrigerant outflow area R54. The channel-formed layer 5 has a top surface, where the channel-formed layer 5 is joined to the channel-formed layer 4.

[0043]The channel-formed layer 4 and the channel-formed layer 5 correspond to a second channel-formed layer including the refrigerant inflow channels 41 and 51 and the refrigerant outflow channels 42 and 52. The channel-formed layer 5 has a role of transferring the refrigerant in the X-axis direction, and the channel-formed layer 4 has a role of transferring the refrigerant in the X-and Y-axis directions. In addition, in the channel-formed layer 4, the refrigerant inflow channels 41 are arranged to be connected to the fin inflow ports 31 of the opening-formed layer 3, but unconnected to the fin outflow ports 32; and the refrigerant outflow channels 42 are arranged to be connected to the fin outflow ports 32, but unconnected to the fin inflow ports 31. This results in a configuration in which the refrigerant inflow channels 41 do not exist in the positions corresponding to the fin outflow ports 32, and the refrigerant outflow channels 42 do not exist in the positions corresponding to the fin inflow ports 31. In addition, in the channel-formed layer 5, the refrigerant inflow channels 51 and the refrigerant outflow channels 52 are formed by openings extending in the X-axis direction.

[0044]The channel connection layer 6 is a metal layer including channels that guide a refrigerant flowing in from the inlet-outlet arrangement layer 7 to the refrigerant inflow channels 51 of the channel-formed layer 5 and guide the refrigerant discharged from the refrigerant outflow channels 52 of the channel-formed layer 5 to the inlet-outlet arrangement layer 7. The channel connection layer 6 includes two opening portions extending in the Y-axis direction in both respective end portions in the X-axis direction in an area outside the area of projection of the element placement area R100. In this example, the channel connection layer 6 includes an inflow connection port 61 extending in the Y-axis direction, in the end portion in the positive X-axis direction, and an outflow connection port 62 extending in the Y-axis direction, in the end portion in the negative X-axis direction. The inflow connection port 61 is disposed at a position corresponding to the refrigerant inflow area R53 of the channel-formed layer 5. The outflow connection port 62 is disposed at a position corresponding to the refrigerant outflow area R54 of the channel-formed layer 5. The inflow connection port 61 and the outflow connection port 62 penetrate through the metal layer in the Z-axis direction. The channel connection layer 6 has a top surface, where the channel connection layer 6 is joined to the channel-formed layer 5.

[0045]The inlet-outlet arrangement layer 7 is a metal layer including opening portions that guide a refrigerant flowing in through a pipe from the outside world, to the inflow connection port 61 of the channel connection layer 6, and guide the refrigerant discharged from the outflow connection port 62 of the channel connection layer 6, to an external pipe. The inlet-outlet arrangement layer 7 includes an inlet port 71 and an outlet port 72, which are opening portions smaller in size than the inflow connection port 61 and the outflow connection port 62, correspondingly to the area in which the inflow connection port 61 of the channel connection layer 6 is disposed and to the area in which the outflow connection port 62 is disposed. The inlet port 71 and the outlet port 72 penetrate through the metal layer in the Z-axis direction. The pipe for supplying the refrigerant is fixed to the inlet port 71 using a fixing component. The pipe for discharging the refrigerant is fixed to the outlet port 72 using a fixing component. The inlet-outlet arrangement layer 7 has a top surface, where the inlet-outlet arrangement layer 7 is connected to the channel connection layer 6.

[0046]As described above, the channel connection layer 6 is disposed between the channel-formed layer 5 and the inlet-outlet arrangement layer 7. The inflow connection port 61 connects the inlet port 71 and the refrigerant inflow channels 51 to each other, and the outflow connection port 62 connects the outlet port 72 and the refrigerant outflow channels 52 to each other.

[0047]The refrigerant flowed in from the inlet port 71 of the inlet-outlet arrangement layer 7 is broadened in the inflow connection port 61 of the channel connection layer 6. The refrigerant then flows into the refrigerant inflow channels 51 disposed in the refrigerant inflow area R53 of the channel-formed layer 5 to flow along the X-axis direction. The refrigerant flows through the channel-formed layer 4, the opening-formed layer 3, and the fin-formed layer 2, comes into contact with the bottom surface of the base layer 1, and then flows through the fin-formed layer 2, the opening-formed layer 3, and the channel-formed layer 4. The refrigerant flows along the refrigerant outflow channels 52 extending in the X-axis direction, of the channel-formed layer 5, and flows out of the refrigerant outflow area R54 to the channel connection layer 6. The refrigerant is collected to a portion corresponding to the position of disposition of the outlet port 72 of the inlet-outlet arrangement layer 7, by the outflow connection port 62 of the channel connection layer 6 corresponding to the refrigerant outflow area R54, and is then discharged from the outlet port 72 of the inlet-outlet arrangement layer 7. In the channel-formed layer 5, merely the refrigerant inflow channels 51 are disposed, and the refrigerant outflow channels 52 are not disposed, in an area corresponding to the inflow connection port 61 connected to the inlet port 71. In addition, merely the refrigerant outflow channels 52 are disposed, and the refrigerant inflow channels 51 are not disposed, in an area corresponding to the outflow connection port 62 connected to the outlet port 72. This results in a configuration in which the refrigerant flowing into the cooler 10 is not led to the refrigerant outflow channels 42 or 52, or on the contrary, the refrigerant to flow out of the cooler 10 is not led from the refrigerant inflow channels 41 or 51.

[0048]FIG. 3 is a diagram for describing an example of flow of the refrigerant in the cooler according to the first embodiment. FIG. 3 illustrates a top view of layers from the opening-formed layer 3 to the channel-formed layer 5. A refrigerant 90 flows in from the portions of the refrigerant inflow channels 51 disposed in the refrigerant inflow area R53 of the channel-formed layer 5, and spreads along the refrigerant inflow channels 51. In this process, the refrigerant 90 also flows into the refrigerant inflow channels 41 of the channel-formed layer 4. The refrigerant 90 flowing through the refrigerant inflow channels 51 of the channel-formed layer 5 is guided through the refrigerant inflow channels 41 of the channel-formed layer 4 to the fin inflow ports 31 of the opening-formed layer 3.

[0049]The drawing of the channel-formed layer 4 of FIG. 3 illustrates projected positions 51a corresponding to the refrigerant inflow channels 51 of the channel-formed layer 5, and the drawing of the opening-formed layer 3 illustrates projected positions 41a corresponding to the refrigerant inflow channels 41 of the channel-formed layer 4. The channel-formed layer 4 includes coverings 43 at the positions of portions of the refrigerant inflow channels 41 corresponding to the fin outflow ports 32 of the opening-formed layer 3. The coverings 43 close the fin outflow ports 32 of the opening-formed layer 3, and function to prevent the refrigerant 90 flowing through the refrigerant inflow channels 41 from being led to the fin outflow ports 32. This results in a configuration in which, as indicated by the projected positions 41a corresponding to the refrigerant inflow channels 41 in the opening-formed layer 3, the refrigerant inflow channels 41 are connected to the fin inflow ports 31 of the opening-formed layer 3, but are unconnected to the fin outflow ports 32. FIG. 4 is a diagram illustrating an example of flow of the refrigerant in the opening-formed layer of the cooler according to the first embodiment. The refrigerant 90 from the channel-formed layer 4 flows along the fin inflow ports 31 as illustrated in FIG. 4, thereby spreading two-dimensionally in the opening-formed layer 3, and then flows into the fin-formed layer 2.

[0050]A similar description applies to the discharge process of the refrigerant 90. In this respect, the channel-formed layer 4 includes coverings 44 at the positions of portions of the refrigerant outflow channels 42 corresponding to the fin inflow ports 31 of the opening-formed layer 3. The coverings 44 close the fin inflow ports 31 of the opening-formed layer 3, and function to prevent the refrigerant 90 flowing through the refrigerant outflow channels 42 from being led from the fin inflow ports 31. This results in a configuration in which the refrigerant outflow channels 42 are connected to the fin outflow ports 32 of the opening-formed layer 3, but are unconnected to the fin inflow ports 31.

[0051]That is, stacking layers from the fin-formed layer 2 to the channel-formed layer 5 causes applicable ones of the opening portions of the channel-formed layer 4, i.e., the refrigerant inflow channels 41, to be disposed in such a manner that the refrigerant inflow channels 51 of the channel-formed layer 5 connected to the inlet port 71 at least partly overlap the fin inflow ports 31 of the opening-formed layer 3 for causing the refrigerant 90 to flow to the fin arrangement area R20, but do not overlap the fin outflow ports 32 of the opening-formed layer 3 for discharging the refrigerant 90 from the fin arrangement area R20. Stacking layers from the fin-formed layer 2 to the channel-formed layer 5 also causes applicable ones of the opening portions of the channel-formed layer 4, i.e., the refrigerant outflow channels 42, to be disposed in such a manner that the refrigerant outflow channels 52 of the channel-formed layer 5 connected to the outlet port 72 at least partly overlap the fin outflow ports 32 of the opening-formed layer 3 for discharging the refrigerant 90 from the fin arrangement area R20, but do not overlap the fin inflow ports 31 of the opening-formed layer 3 for causing the refrigerant 90 to flow to the fin arrangement area R20. That is, the refrigerant inflow channels 51 and the refrigerant outflow channels 52 of the channel-formed layer 5, the refrigerant inflow channels 41 and the refrigerant outflow channels 42 of the channel-formed layer 4, and the fin inflow ports 31 and the fin outflow ports 32 of the opening-formed layer 3 are disposed to prevent the refrigerant 90 flowed in from the inlet port 71 of the inlet-outlet arrangement layer 7 from flowing out from the outlet port 72 of the inlet-outlet arrangement layer 7 without passing through the fin arrangement area R20.

[0052]Meanwhile, the cooler 10 includes one inlet port 71 and one outlet port 72 in the inlet-outlet arrangement layer 7, while the cooler 10 includes multiple fin inflow ports 31 in the opening-formed layer 3, which extend two-dimensionally over the entire area onto which the fin arrangement area R20 is projected. This configuration requires the channel-formed layer 4.

[0053]A configuration of the opening-formed layer 3 will next be described in detail. As illustrated in FIG. 2, the intersection of X-axis and Y-axis, i.e., the origin, is defined in an area of projection, onto the opening-formed layer 3, of the element placement area R100, in which the element 100, i.e., a heat source, is disposed. The origin is preferably the center of the heat source in general. FIG. 5 is a diagram illustrating an example of relationship between the element placement area and the opening-formed layer constituting the cooler according to the first embodiment. As illustrated in FIG. 5, an area R100a, which is an area of projection of the element placement area R100 onto the opening-formed layer 3, exists inside the area in which the fin inflow ports 31 and the fin outflow ports 32 of the opening-formed layer 3 are disposed. In addition, the area in which the fin inflow ports 31 and the fin outflow ports 32 are disposed almost coincides with the fin arrangement area R20. This is because when the element 100 to be cooled joined to the base layer 1 does not coincide with the fin arrangement area R20, such configuration will prevent sufficient cooling of the element 100.

[0054]FIG. 6 is an enlarged top view of a portion of the opening-formed layer. This figure illustrates an enlarged view of the first quadrant of the XY-plane defined in FIG. 2. In the first embodiment, the opening-formed layer 3 includes a cross-shaped opening portion 311, which is one of the fin inflow ports 31 extending along X-axis and Y-axis. That is, the cross-shaped opening portion 311 has four-fold rotational symmetry about the origin, and extends planarly in two-dimensional directions. That is, the cross-shaped opening portion 311 extends not one-dimensionally, but has four-fold rotational symmetry about the origin on a two-dimensional plane, and is thus configured by opening portions extending in multiple directions.

[0055]The opening-formed layer 3 includes, in addition to the cross-shaped opening portion 311, opening portions 312 and 313, which are part of the fin inflow ports 31, and opening portions 321 and 322, which are part of the fin outflow ports 32, at positions radially away from the origin. That is, the multiple opening portions 311, 312, 313, 321, and 322 are formed in the metal layer. Similar opening portions are also formed in the second quadrant, the third quadrant, and the fourth quadrant. This configuration causes the opening portions in the area of projection of the fin arrangement area R20 onto the opening-formed layer 3 to have a shape of four-fold rotational symmetry about the origin.

[0056]The opening portion 321 adjacent to the cross-shaped opening portion 311 is disposed spaced apart by a certain distance from the cross-shaped opening portion 311 both in the X-and Y-axis directions. That is, the opening portion 321 extends not linearly in one direction, but planarly in two-dimensional directions. In this example, the opening portion 321 has an L shape having a right-angled bend at a position on a line angled at about 45° with respect to the X-axis, at which position an opening extending in the X-axis direction and an opening extending in the Y-axis direction are connected to each other. The opening portion 312 adjacent to the opening portion 321, the opening portion 322 next to the opening portion 312, and the opening portion 313 next to the opening portion 322 similarly extend planarly in two-dimensional directions, and each have an L shape having a right-angled bend at a position on a line angled at about 45° with respect to the X-axis.

[0057]The cross-shaped opening portion 311 and the L-shaped opening portions 312 and 313 constitute the fin inflow ports 31 in the fin arrangement area R20, and communicate with the inlet port 71 through the opening portions formed in layers from the channel-formed layer 4 to the inlet-outlet arrangement layer 7.

[0058]The L-shaped opening portions 321 and 322 constitute the fin outflow ports 32 in the fin arrangement area R20, and communicate with the outlet port 72 through the opening portions formed in layers from the channel-formed layer 4 to the inlet-outlet arrangement layer 7.

[0059]As described above, in the cooler 10 according to the first embodiment, the cross-shaped opening portion 311 and the L-shaped opening portions 312 and 313, which are part of the fin inflow ports 31, and the L-shaped opening portions 321 and 322, which are part of the fin outflow ports 32, both for letting the refrigerant flow to and from the fin arrangement area R20, are alternately arranged in a direction radially away from the origin.

[0064]The foregoing three sections exhibit different levels of heat radiation performance, i.e., different heat transfer coefficients, from one section to another, in heat transfer to the refrigerant from the metal layer that forms the base layer 1 and the fin-formed layer 2. Moreover, the temperature of the refrigerant gradually rises as the refrigerant flows in from the cross-shaped opening portion 311, passes through the groove 22 in the fin arrangement area R20, and flows out from the L-shaped opening portion 321.

[0065]Similarly, refrigerant flowed in from the L-24 shaped opening portion 312 passes through the groove 22 in the fin arrangement area R20 and flows out from the L-shaped opening portion 321 and the L-shaped opening portion 322 both adjacent to the L-shaped opening portion 312. In addition, refrigerant flowed in from the L-shaped opening portion 313 passes through the groove 22 in the fin arrangement area R20 and flows out from the L-shaped opening portion 322 adjacent to the L-shaped opening portion 313. The flows of the refrigerant in these cases are generally equivalent to the above-mentioned flow from the cross-shaped opening portion 311 through the groove 22 in the fin arrangement area R20 out from the L-shaped opening portion 321.

[0066]In terms of the direction of flow of the refrigerant, heat radiation performance in heat transfer from the metal layer to the refrigerant differs from one section to another of the flow. In addition, the temperature of the refrigerant gradually rises. This inevitably results in a temperature distribution along the direction of flow of the refrigerant.

[0067]In this respect, in the first embodiment, the fin inflow ports 31 and the fin outflow ports 32 in the opening-formed layer 3 for letting the refrigerant flow to and from the fin arrangement area R20 are disposed alternately in a direction from center to edge. By reducing the spacing in the alternate arrangement, the temperature distribution can be made to occur limitedly in a small area.

[0068]In addition, alternate arrangement of the fin inflow ports 31 and the fin outflow ports 32 means that the fin outflow ports 32 is disposed adjacent to the fin inflow ports 31, and similarly, the fin inflow ports 31 is disposed adjacent to the fin outflow ports 32. A flow of the refrigerant is accordingly produced from one of the fin inflow ports 31 to an adjacent one of the fin outflow ports 32, and such refrigerant flows in directions opposite to each other, acting to cancel the temperature distributions each other. This enables the temperature distribution to be averaged locally. In particular, the base layer 1 is formed of a highly thermally conductive metal, thereby allowing the temperature distribution to be reduced.

[0069]Moreover, as the fin inflow ports 31 for allowing the flow of refrigerant to the fin arrangement area R20 and the fin outflow ports 32 are alternately arranged in parallel in a direction radially away from the origin, it becomes possible to obtain a concentric temperature distribution. Furthermore, reduction in the distance between adjacent ones of the fin inflow ports 31 and the fin outflow ports 32 can reduce the length of flow of the refrigerant flowing through the groove 22 in the fin arrangement area R20. This can reduce an increase in the pressure loss when the refrigerant flows through the groove 22 of the fin-formed layer 2.

[0070]Still furthermore, the fin inflow ports 31 and the fin outflow ports 32, which are arranged alternately and in parallel to one another in a direction radially away from a predetermined point in the area of projection of the element placement area R100 onto the opening-formed layer 3, are disposed to have four-fold rotational symmetry with respect to the predetermined point. Forming the opening portions in the opening-formed layer 3 into a shape having four-fold rotational symmetry reduces non-uniformity in the X-and Y-axis directions, and can thus bring the temperature distribution to be more concentric about the predetermined point. Note that a case where the opening portions are arranged to have rotational symmetry of higher order will be described later.

[0071]The first embodiment assigns the cross-shaped opening portion 311 in the opening-formed layer 3 as one of the fin inflow ports 31 rather than one of the fin outflow ports 32. A heat source generally has a higher temperature in a center portion thereof and a lower temperature in a peripheral portion thereof. The first embodiment defines the origin as a point right under the element 100, which is a heat source. This is because providing a flow of a low-temperature fluid to the origin can provide higher cooling performance.

[0072]In this respect, the cross-shaped opening portion 311, which is the one of the fin inflow ports 31 right under the element 100, which is a heat source, is configured to have the opening portion not only at the origin or at near the origin as illustrated in FIGS. 7 and 11 (described later), but to have the opening portion extending planarly in two-dimensional directions from the opening portion near the origin. Such structure enables the entire element 100 to be uniformly cooled in contrast to the structure in which the opening portion is provided only at the origin or at near the origin as illustrated in FIGS. 7 and 11 (described later). The cooling performance can thus be improved.

[0073]In addition, the L-shaped opening portions 312 and 313, which are part of the fin inflow ports 31, and the L-shaped opening portions 321 and 322, which are part of the fin outflow ports 32, arranged alternately and in parallel to one another in a direction radially away from a predetermined point present in the area of projection of the element placement area R100 onto the opening-formed layer 3 are disposed spaced apart with specific spacings from the cross-shaped opening portion 311. This configuration can reduce the temperature distribution. The L-shaped opening portions 312, 313, 321, and 322 are disposed spaced apart from the cross-shaped opening portion 311 by specific spacings, and accordingly inevitably extend planarly in two-dimensional directions, and each have a structure having a right-angled bend.

[0074]Variations of the cooler 10 according to the first embodiment will next be described. FIG. 7 is a top view illustrating another example of the configuration of the opening-formed layer constituting the cooler according to the first embodiment. FIG. 7 illustrates the origin also as the center of the area of projection of the element placement area R100 onto the opening-formed layer 3. In the example of FIG. 7, an opening portion 311a having a point-like shape serving as one of the fin inflow ports 31 is disposed at the origin. In addition, linear opening portions 312a and 313a serving as the fin inflow ports 31 and linear opening portions 321a and 322a serving as the fin outflow ports 32 are arranged alternately and in parallel to one another in a direction radially away from the origin. In this example, the linear opening portions 312a, 313a, 321a, and 322a extend in a direction perpendicular to a line passing through the origin and angled at 45° or −45 ° with respect to the X-axis. The opening portions in the opening-formed layer 3 are arranged to have four-fold rotational symmetry about the origin. This configuration enables the temperature distribution to be averaged and more concentric.

[0075]In the example of FIG. 7, the structure including the base layer 1 and the fin-formed layer 2, and the opening-formed layer 3 are joined to each other. The opening-formed layer 3 has opening portions formed by processing such as etching and/or cutting from a single metal layer as described above. As such, the opening-formed layer 3 includes holding portions 33 for maintaining the structure of a metal layer. In the example of FIG. 7, the squarely-shaped opening portions are formed parallel to one another with the centers thereof at the origin, arranged in a direction radially away from the origin. In addition, the vertices of the squarely-shaped opening portions are positioned on the X-and Y-axes, on which positions of these vertices no opening portions are formed but the holding portions 33 are provided, which are remaining portions of the metal layer. These holding portions 33 hold the portions of the metal layer at positions between opening portions, and thus maintain the structure of a metal layer.

[0076]An optimum disposition condition in terms of the positions, and the number of, the holding portions 33 depends on factors such as the shape of the fins 21 and the thickness, i.e., the strength, of the opening-formed layer 3. FIGS. 8 to 10 are each a top view illustrating still another example of the configuration of the opening-formed layer constituting the cooler according to the first embodiment. FIG. 8 illustrates a case where the holding portions 33 are formed on lines passing through the origin and angled at 45° and −45 ° with respect to the X-axis. FIG. 9 illustrates a configuration combining the configurations illustrated in FIGS. 7 and 8, i.e., a case where the holding portions 33 are provided on the X-and Y-axes and on lines passing through the origin and angled at 45° and −45 ° with respect to the X-axis. Note that when the holding portions 33 have a narrow width, the holding portions 33 will not have a large effect on the temperature distribution even when the holding portions 33 are not positioned to have four-fold rotational symmetry about the origin. That is, formation of the holding portions 33 in a narrow shape allows the holding portions 33 to be provided at arbitrary positions. Note however that it is ideally preferable that the holding portions 33 be not present as illustrated in FIG. 10. In this case, the metal layer for forming the opening-formed layer 3 is joined to the structure including the base layer 1 and the fin-formed layer 2, after which only that metal layer is processed. This complicates the manufacturing process.

[0077]As described above, a heat source generally has a higher temperature in a center portion thereof and a lower temperature in a peripheral portion thereof because no heat is generated in the peripheral portion of the heat source. FIGS. 7 to 10 therefore each illustrate a configuration in which the spacing, which is the distance between opening portions adjacent to each other in a direction radially away from the origin, is greater at a radially outer position than at a radially inner position. That is, the spacing between adjacent ones of the fin inflow ports 31 and the fin outflow ports 32 is greater at a position farther from a point in the area onto which the element placement area R100 is projected, than at a position nearer to the point in the area. In one example, the spacing between opening portions adjacent to each other can be made greater at a position farther from a predetermined point.

[0078]Configuring the spacing between opening portions adjacent to each other to be greater in a radially outer portion than in a radially inner portion increases the length of the channel through which the refrigerant flows in a radially outer portion of the fin arrangement area R20, which corresponds to a peripheral portion of the heat source. This results in, in a radially outer portion, a greater pressure loss and accordingly a lower flow rate, and also results in a longer length from one of the fin inflow ports 31 to one of the fin outflow ports 32. This increases the total amount of heat generation in a region including channels through which the refrigerant flows in a radially outer portion. This leads to a larger temperature increase in fluid in a radially outer portion than in fluid in a radially inner portion, thereby causing the temperature to rise in a peripheral portion of the heat source. This enables the temperature distribution of the heat source to be reduced. Note however that a temperature increase in a peripheral portion of the heat source also causes a temperature increase in the center portion. This requires design of spacing between opening portions taking into account the amount of heat generation, required temperature specifications, and a required temperature distribution.

[0079]FIG. 11 is a top view illustrating still another example of the configuration of the opening-formed layer constituting the cooler according to the first embodiment. FIG. 11 illustrates the origin also as the center of the area of projection of the element placement area R100. In the example of FIG. 11, arc-shaped opening portions 311b, 312b, and 313b serving as the fin inflow ports 31 and arc-shaped opening portions 321b and 322b serving as the fin outflow ports 32 are arranged alternately and in parallel to one another in a direction radially away from the origin. Also in the example of FIG. 11, the opening portions in the area of projection of the element placement area R100 are arranged to have four-fold rotational symmetry about the origin. In addition, the spacing between the adjacent opening portions is greater at a radially outer side than at a radially inner side.

[0080]In the case of FIG. 11, the fin inflow ports 31 and the fin outflow ports 32 have a circular shape by joining together the parts of each of the arc-shaped opening portions 311b, 312b, 313b, 321b, and 322b by the holding portions 33. Thus, the fin inflow ports 31 and the fin outflow ports 32 have a shape of circular symmetry, and thus have rotational symmetry of higher order, thereby enabling the temperature distribution to be more uniform. Note however that the groove 22 in the fin arrangement area R20 is generally often formed by a combination of linear portions. Accordingly, as described above, it is preferable that the opening portions 311b, 312b, 313b, 321b, and 322b in the opening-formed layer 3 extend in alignment with the direction of the opening portions in the fin arrangement area R20 from a viewpoint of reduction of increase in the pressure loss. That is, the fins 21 in the fin arrangement area R20 of the fin-formed layer 2 are desirably also arranged to cause corresponding portions of the groove 22 to have an arc shape, i.e., circular symmetry, to align with the opening portions of the opening-formed layer 3. Such configuration, however, complicates the manufacturing process of the fins 21 and of the opening portions having circular symmetry as compared to the case of a linear shape.

[0081]Note that when the opening-formed layer 3 has a shape such as the shapes illustrated in FIGS. 7 to 11, the channels of the channel-formed layer 4 and of the channel-formed layer 5 may have shapes different from the shapes of FIG. 2. In this case, the channels of the channel-formed layer 4 and of the channel-formed layer 5 are arranged to prevent the refrigerant flowed in from the inlet port 71 of the inlet-outlet arrangement layer 7 from flowing out from the outlet port 72 of the inlet-outlet arrangement layer 7 without passing through the fins 21. That is, applicable ones of the opening portions of the channel-formed layer 4, i.e., the refrigerant inflow channels 41, are disposed in such a manner that the refrigerant inflow channels 51 of the channel-formed layer 5 connected to the inlet port 71 at least partly overlap the fin inflow ports 31 of the opening-formed layer 3 for causing the refrigerant to flow to the fin arrangement area R20, but do not overlap the fin outflow ports 32 of the opening-formed layer 3 for discharging the refrigerant from the fin arrangement area R20. In addition, applicable ones of the opening portions of the channel-formed layer 4, i.e., the refrigerant outflow channels 42, are disposed in such a manner that the refrigerant outflow channels 52 of the channel-formed layer 5 connected to the outlet port 72 at least partly overlap the fin outflow ports 32 of the opening-formed layer 3 for discharging the refrigerant from the fin arrangement area R20, but do not overlap the fin inflow ports 31 of the opening-formed layer 3 for causing the refrigerant to flow to the fin arrangement area R20. That is, the refrigerant inflow channels 51 and the refrigerant outflow channels 52 of the channel-formed layer 5, the refrigerant inflow channels 41 and the refrigerant outflow channels 42 of the channel-formed layer 4, and the fin inflow ports 31 and the fin outflow ports 32 of the opening-formed layer 3 are disposed to prevent the refrigerant flowed in from the inlet port 71 of the inlet-outlet arrangement layer 7 from flowing out from the outlet port 72 of the inlet-outlet arrangement layer 7 without passing through the fin arrangement area R20.

[0082]In addition, in the above example, due to presence of one inlet port 71 and one outlet port 72 in the cooler 10, the refrigerant from the inlet port 71 is spread in the channel connection layer 6 to be led to the refrigerant inflow area R53 of the channel-formed layer 5, and the refrigerant from the refrigerant outflow area R54 of the channel-formed layer 5 is collected in the channel connection layer 6 to be led to the outlet port 72 of the inlet-outlet arrangement layer 7. When the cooler 10 includes multiple inlet ports 71 and multiple outlet ports 72, the channel-formed layer 4 and the channel-formed layer 5 may have different shapes to connect the multiple inlet ports 71 to the refrigerant inflow area R53 of the channel-formed layer 5 and to connect the multiple outlet ports 72 to the refrigerant outflow area R54 of the channel-formed layer 5.

[0083]Moreover, although FIGS. 5 and 6 illustrate a case where adjacent ones of the L-shaped opening portions 312, 313, 321, and 322 have a constant spacing therebetween, adjacent ones of the L-shaped opening portions 312, 313, 321, and 322 may have a spacing that is greater at a radially outer position than at a radially inner position similarly to the cases illustrated in FIGS. 7 to 11.

[0084]FIG. 12 is a top view schematically illustrating a positional relationship between each of the opening portions of the opening-formed layer and the groove in the fin arrangement area arranged in the fin-formed layer.

[0085]FIG. 12 is an enlarged view of a portion of an area R34 of FIG. 7. The fin inflow ports 31 and the fin outflow ports 32, which are opening portions of the opening-formed layer 3, are disposed in directions aligned with the directions of the opening portions that are the groove 22 formed between the fins 21 disposed in the fin-formed layer 2. That is, the fin inflow ports 31 and the fin outflow ports 32 are arranged to align with the directions in which the opening portions defined by the fins 21 on a surface contacting the opening-formed layer 3 extend in the XY-plane. This results in reduced obstacles hampering a flow, and can therefore reduce an increase in the pressure loss when the refrigerant flows from the fin inflow ports 31 formed in the opening-formed layer 3 into the groove 22 of the fin-formed layer 2, and when oppositely, the refrigerant flows out of the groove 22 of the fin-formed layer 2 into the fin outflow ports 32 formed in the opening-formed layer 3.

[0086]Adjacent ones of the fin inflow ports 31 and the fin outflow ports 32 of the opening-formed layer 3 are disposed in a direction radially away from the origin, and have therefore different areas. That is, an opening portion has a smaller area at a position farther from the origin. Accordingly, a groove 22 of the fin-formed layer 2 extending in one-dimensional direction would cause retardation of the flow, leading to an increase in the temperature distribution and a degradation in cooling performance. Thus, the groove 22 of the fin-formed layer 2 is desirably configured to be locally spreadable two-dimensionally between the fin inflow ports 31 and the fin outflow ports 32. This configuration can reduce or prevent occurrence of non-uniform flow between the fin inflow ports 31 and the fin outflow ports 32, eliminate retardation of the flow, and improve cooling performance.

[0087]FIG. 13 is a partially-enlarged top view illustrating an example of configuration of the fin-formed layer constituting the cooler according to the first embodiment. FIG. 13 is an enlarged view of a portion of the fin arrangement area R20 in the fin-formed layer 2. FIG. 13 illustrates, by an arrow, the flow of the refrigerant in the groove 22 of the fin arrangement area R20 of the fin-formed layer 2 illustrated in FIG. 2. As illustrated in FIG. 13, the groove 22 in the fin arrangement area R20 has local periodicity of repetition of merging and branching in a narrow area. In addition, the groove 22 having this periodicity is formed over the entire fin arrangement area R20. In one example, the refrigerant flowing through the groove 22, which is the channel in the fin arrangement area R20, merges and then branches at a position 23 as illustrated in FIG. 13. Alternatively, the opening portions forming the fins 21 are desirably provided to allow the refrigerant to repeat merging and branching between the adjacent ones of the fin inflow ports 31 and the fin outflow ports 32. Such configurations can provide a uniform flow in two-dimensional directions, that is, in all directions on the plane formed by the X-and Y-axes even when the fin inflow ports 31 and the fin outflow ports 32 have different areas. This can reduce the temperature distribution and improve cooling performance.

[0088]FIG. 14 is a top view illustrating another example of the configuration of the fin-formed layer constituting the cooler according to the first embodiment. FIG. 15 is an enlarged top view of a portion of the fin arrangement area of the fin-formed layer of FIG. 14. FIG. 15 is a diagram illustrating, in enlargement, the portion of the area R210 of FIG. 14. FIGS. 14 and 15 illustrate an example of the fin-formed layer 2 including the fins 21 having a shape different from the shape of FIG. 13 that locally repeats merging and branching. In the example of FIGS. 14 and 15, a fin-formed layer 2a includes a thin plate 210, on which opening portions 211 extending in the first direction are formed in the fin arrangement area R20 including the area of projection of the element placement area R100, and a thin plate 220, on which opening portions 221 extending in the second direction crossing the first direction are formed in the fin arrangement area R20. The fin-formed layer 2a has a structure of stacking multiple ones of the thin plate 210 and multiple ones of the thin plate 220 alternately one on top of another. In the fin arrangement area R20 of the fin-formed layer 2a, the opening portions 211 extending in the first direction and the opening portions 221 extending in the second direction overlap each other to form fins 21a. In the example of FIGS. 14 and 15, the opening portions 211 and the opening portions 221 are stacked one on top of another to form a groove 22a. The groove 22a has a three-dimensional mesh-shaped structure.

[0089]FIG. 16 is a top view illustrating an example of configuration of the opening-formed layer associated with the fin-formed layer of FIG. 14. In the example illustrated in FIG. 16, a cross-shaped opening portion 311c passing through the origin is disposed along the directions of the groove 22a in the fin arrangement area R20 of FIGS. 14 and 15, that is, along the directions aligned with the first direction and the second direction. Also in this case, L-shaped opening portions 312c, 313c, 321c, and 322c are arranged in parallel to one another in a direction radially away from the origin each spaced apart by specific distances from the cross-shaped opening portion 311c.

[0090]The refrigerant flows from the fin inflow ports 31 of the opening-formed layer 3 into the fin arrangement area R20 of the fin-formed layer 2. Specifically, the refrigerant flows in from the opening portions formed in areas of the fin arrangement area R20 overlapping the fin inflow ports 31. The opening portions formed in the fin arrangement area R20 correspond to the positions of the groove 22a as viewed from the bottom surface of the fin-formed layer 2a. The refrigerant then passes through the gaps formed along the opening portions 211 and 221 in the stacked thin plates 210 and 220 to thus repeat merging and branching, after which the refrigerant flows out from opening portions overlapping the fin outflow ports 32 and from the fin outflow ports 32 of the opening-formed layer 3. Use of the thin plates 210 and 220 having a low thickness for forming the fins 21a enables narrow channels to be produced, and thus enables a cooler with high cooling performance to be provided.

[0091]The refrigerant repeats merging and branching in a local area also in the case of the fins 21a illustrated in FIG. 14. That is, the fins 21a illustrated in FIG. 14 have channels that allow the flow to spread uniformly in two-dimensional directions, that is, in all directions on the plane formed by the X- and Y-axes. Note that there are no particular limitations on a production method or a form with respect to the fins 21a.

[0092]As described above, the cooler 10 according to the first embodiment includes: the base layer 1 to which the element 100 is to be joined; the fin-formed layer 2 including a fin arrangement area R20 having the multiple fins 21, 21a disposed therein, the multiple fins being connected to the base layer 1; and the opening-formed layer 3 connected to the fin-formed layer 2 and including the multiple fin inflow ports 31 and the multiple fin outflow ports 32, the fin inflow ports allowing the flow of refrigerant flow to the fin arrangement area R20. The multiple fin inflow ports 31 are connected via inflow channels with the inlet port 71 into which the refrigerant of the cooler 10 flows. The fin outflow ports 32 are connected via outflow channels with the outlet port 72 out of which the refrigerant of the cooler 10 flows. In addition, the multiple fin inflow ports 31 and the multiple fin outflow ports 32 are arranged alternately and in parallel to one another in a direction radially away from a point present in an area of projection of a shape of the element 100 onto the opening-formed layer 3. This configuration enables the temperature distribution caused by heat generation of the element 100 to be more concentric, and the temperature distribution to be reduced. This configuration further enables an increase to be reduced in the pressure loss of the refrigerant in the fin-formed layer 2 between the fin inflow ports 31 and the fin outflow ports 32.

SECOND EMBODIMENT

[0093]FIG. 17 is a cross-sectional view schematically illustrating an example of configuration of a cooler according to a second embodiment. Note that components the same as the corresponding components described in the first embodiment are designated by like reference characters, and description thereof will be omitted. A cooler 10a of the second embodiment further includes a channel-formed layer 8 between the opening-formed layer 3 and the channel-formed layer 4.

[0094]FIG. 18 is a top view illustrating an example of configuration of the foregoing channel-formed layer constituting the cooler according to the second embodiment. The channel-formed layer 8 is a metal layer including channels 81 and 82, which are opening portions, in an area encompassing the area of projection of the element placement area R100. The area in which the channels 81 and 82 of the channel-formed layer 8 are disposed is herein referred to as channel arrangement area R80. The channel-formed layer 8 corresponds to a first channel-formed layer.

[0095]FIG. 19 is a diagram illustrating an example of the opening-formed layer and the foregoing channel-formed layer as stacked one on top of the other. The hatched portions in FIG. 19 indicate portions of the channels 81 and 82 of the channel-formed layer 8 overlapping the areas other than the opening portions of the opening-formed layer 3. In the example illustrated in FIG. 19, the channel arrangement area R80 encompasses the element placement area R100, and is larger in area than the element placement area R100. In this example, the channel arrangement area R80 is similar in size to the element placement area R100 in the Y-axis direction, but is larger in size than the element placement area R100 in the X-axis direction. In addition, as illustrated in FIGS. 18 and 19, the channels 81 and 82 of the channel arrangement area R80 are disposed correspondingly to the opening portions of the opening-formed layer 3. The channel-formed layer 8 is disposed in such a manner that the widthwise center of each of the channels 81 and 82 of the channel-formed layer 8 coincides in position with the widthwise center of a corresponding one of the opening portions of the opening-formed layer 3. In this manner, a cross-shaped opening portion 81a passing through the origin and L-shaped opening portions 81b and 82b are disposed in the channel arrangement area R80. The L-shaped opening portions 81b and 82b are arranged in parallel to one another in a direction radially away from the origin. That is, the channel-formed layer 8 includes the channel arrangement area R80 including an area including the opening portions 81a and 81b onto which the fin inflow ports 31 are projected, and the opening portions 82b onto which the fin outflow ports 32 are projected, where the fin inflow ports 31 and the fin outflow ports 32 are arranged alternately and in parallel to one another in a direction radially away from the origin of the opening-formed layer 3. The channels 81 and 82 of the channel-formed layer 8 accordingly have widths and lengths equivalent to or greater than the widths and the lengths of the opening portions of the opening-formed layer 3.

[0096]To ensure a large area in the fin arrangement area R20 of the fin-formed layer 2 for the refrigerant to flow, the opening portions of the opening-formed layer 3 often have a narrow width. In addition, in FIG. 2 of the first embodiment, the refrigerant inflow channels 41 and the refrigerant outflow channels 42, which are the opening portions of the channel-formed layer 4, are basically opening portions encompassing the area of projection, onto the channel-formed layer 4, of the fin inflow ports 31 and the fin outflow ports 32, which are the opening portions of the opening-formed layer 3, and of the refrigerant inflow channels 51 and the refrigerant outflow channels 52, which are the opening portions of the channel-formed layer 5. Note however that, to prevent the refrigerant flowed in from the inlet port 71 from flowing out from the outlet port 72 without passing through the fins 21, there are portions without opening portions of the channel-formed layer 4 immediately above the opening portions of the opening-formed layer 3. The refrigerant does not readily flow toward the fins 21 in these portions. There is also an opposite situation in which there are portions without opening portions of the opening-formed layer 3 at positions corresponding to the opening portions of the channel-formed layer 4. This may cause non-uniformity in the flow, thereby increasing the temperature distribution, and causing a degradation in cooling performance.

[0097]The cooler of the second embodiment is configured to connect the channel-formed layer 8 to the opening-formed layer 3, where, as illustrated in FIG. 18, the channel-formed layer 8 includes the channel arrangement area R80 having the channels 81 and 82 formed therein, onto which channels 81 and 82 the fin inflow ports 31 and the fin outflow ports 32 arranged alternately and in parallel to one another in a direction radially away from the origin of the opening-formed layer 3 are projected. This produces wide channels above the areas without the opening portions of the channel-formed layer 4, and thus allows the refrigerant to flow also in such areas, thereby enabling the refrigerant to flow more uniformly between the fins 21. This can reduce the temperature distribution, and improve cooling performance. Moreover, this configuration also produces wide channels under the areas without the opening portions of the opening-formed layer 3 at positions corresponding to the opening portions of the channel-formed layer 4, and thus allows the refrigerant to flow also in such areas, thereby enabling the refrigerant to flow more uniformly between the fins 21.

[0098]In addition, the channels 81 and 82 disposed in the channel-formed layer 8 reduce non-uniformity of flow occurred in the opening portions of the channel-formed layer 4. Thus, use of the opening-formed layer 3 having a decreased thickness and the channel-formed layer 8 having an increased thickness, specifically, use of the channel-formed layer 8 having a thickness greater than the thickness of the opening-formed layer 3 can more effectively eliminate non-uniformity of flow of the refrigerant. This can further reduce the temperature distribution, and improve cooling performance.

[0099]The cooler 10a according to the second embodiment further includes the channel-formed layer 8 connected to the opening-formed layer 3. The channel-formed layer 8 includes a projection area that is an area onto which the multiple fin inflow ports 31 and the multiple fin outflow ports 32 of the opening-formed layer 3 are projected. The channel-formed layer 8 includes the channels 81 and 82 in an area larger than the projection area. The channels 81 and 82 are opening portions greater in at least one of length and width than the multiple fin inflow ports 31 and the multiple fin outflow ports 32 of the opening-formed layer 3. This configuration produces the wide channels 81 and 82 above the areas without the opening portions of the channel-formed layer 4, and thus allows the refrigerant to flow also in such areas, thereby enabling the refrigerant to flow more uniformly between the fins 21. This can reduce the temperature distribution, and improve cooling performance.

THIRD EMBODIMENT

[0100]FIG. 20 is a cross-sectional view schematically illustrating an example of configuration of a cooler according to a third embodiment. Note that components the same as the corresponding components described in the first embodiment are designated by like reference characters, and description thereof will be omitted. FIG. 20 illustrates a case where three elements 100 arranged in a same direction, one example of which is the X-axis direction, are joined to a single cooler 10b. Also in this case, layers from the base layer 1 to the channel-formed layer 5 are structured generally similarly to the structure illustrated in FIG. 2 when focusing on an area A of the cooler 10b where one of the elements 100 is joined. This is also true for ones of the elements 100 joined at other positions. That is, the cooler 10b is configured such that three of the metal layer structure illustrated in FIG. 2 are disposed in parallel to one another.

[0101]The cooler 10b according to the third embodiment differs in the configuration of a channel connection layer 6b and an inlet-outlet arrangement layer 7b from the corresponding layers of the cooler 10 of the first embodiment, and further includes a channel distribution layer 9 between the channel connection layer 6b and the inlet-outlet arrangement layer 7b. That is, the channel connection layer 6b, the channel distribution layer 9, and the inlet-outlet arrangement layer 7b are sequentially joined under the channel-formed layer 5.

[0102]FIG. 21 is a top view illustrating an example of configuration of the channel connection layer constituting the cooler according to the third embodiment. As illustrated in FIG. 21, the channel connection layer 6b includes an inflow connection port 61b and an outflow connection port 62b in each pair of positions corresponding to each of the three elements 100. Note however that, unlike the first embodiment, in which the inflow connection port 61 and the outflow connection port 62 are aligned with each other in the Y-axis direction as illustrated in FIG. 2, the inflow connection ports 61b and the outflow connection ports 62b in the third embodiment are offset from each other in the Y-axis direction. In the example of FIG. 21, the inflow connection ports 61b are disposed at positions deviated by a predetermined distance Ay in the positive Y-axis direction with respect to the outflow connection ports 62b.

[0103]The channel distribution layer 9 is a metal layer including a channel for distributing the refrigerant flowing from an inlet port 71b of the inlet-outlet arrangement layer 7b to the inflow connection ports 61b of the channel connection layer 6b, and a channel for merging the refrigerant from the outflow connection ports 62b of the channel connection layer 6b into an outlet port 72b of the inlet-outlet arrangement layer 7b. FIG. 22 is a top view illustrating an example of configuration of the channel distribution layer constituting the cooler according to the third embodiment. As illustrated in FIG. 22, the channel distribution layer 9 includes a distribution channel 91 for distributing the refrigerant from the inlet port 71b to the inflow connection ports 61b of the channel connection layer 6b, and a merging channel 92 for merging the refrigerant from the outflow connection ports 62b of the channel connection layer 6b into the outlet port 72b. The distribution channel 91 is disposed to cross the inflow connection ports 61b of the channel connection layer 6b, but not to cross the outflow connection ports 62b. The merging channel 92 is disposed to cross the outflow connection ports 62b of the channel connection layer 6b, but not to cross the inflow connection ports 61b. In this example, the distribution channel 91 is disposed at a position more positive in the Y-axis direction with respect to the merging channel 92.

[0104]FIG. 23 is a top view illustrating an example of configuration of the inlet-outlet arrangement layer constituting the cooler according to the third embodiment. As illustrated in FIG. 23, the inlet-outlet arrangement layer 7b includes the single inlet port 71b and the single outlet port 72b. The inlet port 71b is disposed at a position to cross the distribution channel 91 of the channel distribution layer 9. The outlet port 72b is disposed at a position to cross the merging channel 92 of the channel distribution layer 9. The example of FIG. 23 illustrates a case where the inlet port 71b and the outlet port 72b are provided at positions corresponding to the leftmost one of the elements 100 of FIG. 20, spaced apart from each other in the Y-axis direction. The inlet port 71b and the outlet port 72b can however be provided at any positions that allow the inlet port 71b to cross the distribution channel 91 of the channel distribution layer 9 and allow the outlet port 72b to cross the merging channel 92 of the channel distribution layer 9. In addition, the third embodiment assumes that the cooler 10b includes the single inlet port 71b and the single outlet port 72b although three elements 100 are disposed on the cooler 10b.

[0105]As described above, the channel distribution layer 9 is inserted between the channel connection layer 6b and the inlet-outlet arrangement layer 7b, where the channel distribution layer 9 includes the distribution channel 91, which connects the single inlet port 71b with the inflow connection ports 61b of the channel connection layer 6b provided correspondingly to the respective three elements 100, and includes the merging channel 92, which connects the single outlet port 72b with the outflow connection ports 62b of the channel connection layer 6b provided correspondingly to the respective three elements 100. This configuration causes the refrigerant flowing from inlet port 71b of the inlet-outlet arrangement layer 7b to pass through the distribution channel 91 and flow to the inflow connection ports 61b, which connects to the fins 21 for cooling the elements 100. The refrigerant then reaches the fins 21 at the positions of the respective elements 100, and returns to the outflow connection ports 62b. The refrigerant that has flowed out from the outflow connection ports 62b passes though the merging channel 92, and is discharged from the outlet port 72b of the inlet-outlet arrangement layer 7b. In this example, the X-axis direction corresponds to a third direction, and the Y-axis direction correspond to a fourth direction.

[0106]As described above, even when there are multiple elements 100 each acting as a heat source on the cooler 10b, which is as a heat sink, the elements 100 can be cooled using a configuration similar to the configuration of when there is a single element 100 on the cooler 10b.

[0107]Note that FIG. 21 illustrates, by broken lines, areas R20b, which are each an area of projection, onto the channel connection layer 6b, of the fin arrangement area R20 of the fin-formed layer 2. The areas R20b of projection of the fin arrangement area R20 are hereinafter each referred to as fin projection area R20b. As illustrated in FIG. 21, the three fin projection areas R20b are disposed in parallel to one another along the X-axis direction. In this respect, it is on the opening-formed layer 3 that the fin inflow ports 31 and the fin outflow ports 32 are defined, which are opening portions leading to the fin arrangement area R20 including the fins 21 forming the groove 22, which locally repeats merging and branching. FIG. 24 is a top view illustrating an example of the configuration of the channel connection layer constituting the cooler according to the third embodiment. As illustrated in FIG. 24, the fin arrangement areas R20 respectively provided for the three elements 100 are integrated into a single fin arrangement area. The area of projection of this fin arrangement area onto the channel connection layer 6b is a fin projection area R20c indicated by the broken line. The fins 21 may be provided over the entire area of the fin-formed layer 2 in such manner.

[0108]Note that although the above example has been described with respect to the case where three of the elements 100 are disposed on the single cooler 10b, the cooler 10b of the third embodiment is also applicable to cases where the number of the elements 100 is two and four or higher.

[0109]The cooler 10b according to the third embodiment is configured in which layers from the base layer 1 to the channel-formed layer 5 are structured similarly to what has been described in the first embodiment, for each of the multiple elements 100 disposed in one direction. The cooler 10b includes the channel connection layer 6b, the channel distribution layer 9, and the inlet-outlet arrangement layer 7b under the channel-formed layer 5. In the channel connection layer 6b, the inflow connection ports 61b are disposed at positions deviated along the extending direction with respect to the positions of the outflow connection ports 62b. The channel distribution layer 9 includes the distribution channel 91 for connecting together the multiple inflow connection ports 61b of the channel connection layer 6b, and the merging channel 92 for connecting together the multiple outflow connection ports 62b. The inlet-outlet arrangement layer 7b includes the inlet port 71b, which is provided at a position corresponding to a part of the distribution channel 91, and the outlet port 72b, which is provided at a position corresponding to a part of the merging channel 92. Such configuration enables the temperature distribution caused by heat generation of the elements 100 to be more concentric, and the temperature distribution to be reduced even when multiple ones of the element 100 are connected to the cooler 10b. This configuration further enables an increase to be reduced in the pressure loss of the refrigerant in the fin-formed layer 2 between the fin inflow ports 31 and the fin outflow ports 32.

[0110]The configurations described in the foregoing embodiments are merely examples. These configurations may be combined with another known technology, and configurations of different embodiments may be combined together. Moreover, such configurations may be partly omitted and/or modified without departing from the gist.

REFERENCE SIGNS LIST

[0111]1 base layer; 2, 2a fin-formed layer; 3 opening-formed layer; 4, 5, 8 channel-formed layer; 6, 6b channel connection layer; 7, 7b inlet-outlet arrangement layer; 9 channel distribution layer; 10, 10a, 10b cooler; 21, 21a fin; 22, 22a groove; 31 fin inflow port; 32 fin outflow port; 33 holding portion; 41, 51 refrigerant inflow channel; 42, 52 refrigerant outflow channel; 43, 44 covering; 61, 61b inflow connection port; 62, 62b outflow connection port; 71, 71b inlet port; 72, 72b outlet port; 81, 82 channel; 81a, 81b, 82b, 211, 221, 311, 311a, 311b, 311c, 312, 312a, 312b, 312c, 313, 313a, 313b, 313c, 321, 321a, 321b, 321c, 322, 322a, 322b, 322c opening portion; 90 refrigerant; 91 distribution channel; 92 merging channel; 100 element; 101 heat conduction layer; 210, 220 thin plate; A, R34, R100a, R210 area; R20 fin arrangement area; R20b, R20c fin projection area; R53 refrigerant inflow area; R54 refrigerant outflow area; R80 channel arrangement area; R100 element placement area; R101 heat conduction layer placement area.