Cooling device, method of manufacturing a cooling device

Abstract

The present application provides a cooling device that can be manufactured without reducing the strength of components, and a manufacturing method for the cooling device. The cooling device includes a heat sink (10) having a flat plate portion (11) in a flat plate shape and a plurality of fins (12) protruding from the flat plate portion (11), and a cover (22) that houses the heat sink (10), the heat sink (10) being joined to the cover (22) by irradiating laser light (L) to the flat plate portion (11) between the plurality of fins (12) from the side of the plurality of fins (12).

Description

TECHNICAL FIELD

[0001] The present application relates to a cooling device, a manufacturing method of a cooling device. BACKGROUND

[0002] A cooler described in Patent Literature 1 is formed by housing a fin unit inside a base formed of a first base forming member and a second base forming member. An internal region through which a heat medium flows is formed inside the base. A surface of the first base forming member on the side opposite to the internal region is provided as a first surface to which a power module as a heat generating body is joined. In addition, a surface of the second base forming member on the side opposite to the internal region is provided as a second surface to which the power module is joined. The fin unit is formed by forming cylindrical fins on both surfaces of a flat plate-shaped base plate. The fin unit is formed by integrally molding the base plate and the fins. Specifically, the fin unit is formed by hot forging an aluminum plate and / or a copper plate using a forging die formed in accordance with the shape of the fin unit. Furthermore, in the first base forming member and the second base forming member, a brazing material is applied to the surface on the side of the internal region, and the hard brazing is performed in a state where the tip surface of the fin of the fin unit is in contact with the brazing material applied to the first base forming member and the second base forming member, and the first base forming member and the second base forming member are formed.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2013-239675 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] After a plurality of components are formed, if brazing is performed in order to join the components, the entire product can be annealed and the strength can be reduced.

[0008] An object of the present application is to provide a cooling device and the like that can be manufactured without reducing the strength of components.

[0009] MEANS FOR SOLVING THE PROBLEMS

[0010] The present application completed in order to achieve the above object is a cooling device including: a heat sink having a flat plate-shaped flat plate-shaped portion and a plurality of fins protruding from the flat plate-shaped portion; and a housing that houses the heat sink, the heat sink being joined to the housing by irradiating laser light from the plurality of fins side to the flat plate-shaped portion between the plurality of fins.

[0011] Here, a melting portion can be formed between the flat plate-shaped portion and the housing.

[0012] Further, the flat plate portion, the fins, and the housing can be formed with a fusion portion.

[0013] Further, the housing can have a bottomed concave housing main body, and a cover that covers an opening portion of the housing main body and holds a heat generating body on a side opposite to the housing main body, and the heat sink can be joined to a portion of the cover on a side opposite to the heat generating body.

[0014] Further, the housing can have a bottomed concave housing main body, and a cover that covers an opening portion of the housing main body, and a heat generating body can be held on a bottom portion of the housing main body on a side opposite to the cover, and the heat sink can be joined to a portion of the bottom portion of the housing main body on a side opposite to the heat generating body.

[0015] Further, a surface of the fin on a side opposite to an adjacent fin can be inclined with respect to a protruding direction in a manner such that a distance between the fin and the adjacent fin gradually decreases from a tip end portion to a base end portion.

[0016] Further, the fin can have at least either one of a chamfer and an R portion at a tip end portion.

[0017] Further, the heat sink can be formed of aluminum or copper.

[0018] Further, a portion of the housing to which the heat sink is joined can be formed of at least either one of aluminum and copper.

[0019] Further, the heat sink can be formed of aluminum, a portion of the housing to which the heat sink is joined can be formed of a clad material of aluminum and copper, and the aluminum can be a joining surface to which the heat sink is joined.

[0020] Further, from another viewpoint, the present application is a cooling device including: a heat sink having a flat plate portion that is flat and a plurality of fins that protrude from the flat plate portion; and a base that holds the heat sink and holds a heat generating body on a side opposite to the heat sink, the heat sink being joined to the base by irradiating laser light to the flat plate portion between the plurality of fins from a side of the plurality of fins.

[0021] Further, from another viewpoint, the present application is a manufacturing method of a cooling device, in which a heat sink having a flat plate portion that is flat and a plurality of fins that protrude from the flat plate portion, and a housing that accommodates the heat sink are overlapped, laser light is irradiated to the flat plate portion between the plurality of fins from a side of the plurality of fins, and the heat sink is joined to the housing.

[0022] Further, the present application is a manufacturing method of a cooling device, which is understood from another viewpoint, by bringing a heat sink having a flat plate portion of a flat plate shape and a plurality of fins protruding from the flat plate portion, and a base that holds the heat sink and holds a heat generating body on a side opposite to the heat sink, into coincidence, irradiating laser light to the flat plate portion between the plurality of fins from the plurality of fin side, thereby joining the heat sink and the base.

[0023] Effects of Invention

[0024] According to the present application, it is possible to provide a cooling device or the like that can be manufactured without reducing the strength of components. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is an example of a drawing in which components of the cooling device of the first embodiment are disassembled.

[0026] Figure 2 is an example of a drawing showing a cross section of the cooling device.

[0027] Figure 3 is a drawing for explaining joining of the heat sink and the cover.

[0028] Figure 4 is an example of a drawing showing a welding portion.

[0029] Figure 5 is an example of a drawing showing a welding path.

[0030] Figure 6 is an example of a drawing showing a welding path when joining the heat sink having wavy fins to the cover.

[0031] Figure 7 is an example of a drawing showing a modification example of the shape of the fins.

[0032] Figure 8 is an example of a drawing showing a welding portion of the second embodiment.

[0033] Figure 9 is an example of a drawing showing a cross section of the cooling device of the third embodiment.

[0034] Figure 10 is an example of a drawing showing a cross section of the cooling device of the fourth embodiment.

[0035] Explanation of Reference Numerals

[0036] 1, 2, 3, 4... cooling device, 5... semiconductor module, 10... heat sink, 11... flat plate portion, 12... fin, 20... housing, 21... housing main body, 22... cover, 31... bottom portion, 40... welding portion, 41... melting portion, 121... front end portion, 122... base end portion, 123... chamfer, 60... base, 151... laser head, L... laser DETAILED DESCRIPTION

[0037] Hereinafter, the embodiments will be described in detail with reference to the drawings.

[0038] <1st Embodiment>

[0039] Figure 1 is an example of a drawing in which the components of the cooling device 1 of the 1st embodiment are disassembled.

[0040] Figure 2 is a drawing showing an example of a cross section of the cooling device 1.

[0041] The cooling device 1 of the embodiment is provided with: the heat sink 10 having the fin 12; and the housing 20 that houses the heat sink 10 and forms a space for the cooling liquid to flow through. The cooling device 1 is a liquid cooling type cooling device that cools the semiconductor module 5, which is an example of a heat generating body, using the cooling liquid and the heat sink 10.

[0042] The housing 20 has the bottomed concave housing main body 21, the cover 22 that covers the opening portion of the housing main body 21, the O-ring 23 that seals between the housing main body 21 and the cover 22, and the bolt 24 that joins the housing main body 21 and the cover 22. In addition, the housing 20 is provided with the inflow pipe 25 that causes the cooling liquid to flow into the housing 20, and the outflow pipe 26 that causes the cooling liquid to flow out of the housing 20.

[0043] The material of the housing main body 21 and the cover 22 can be exemplified by A6000 series aluminum alloy such as A6063, copper.

[0044] The housing main body 21 has the flat plate-shaped rectangular bottom portion 31 and the four side walls 32 that protrude from the end portions of the periphery of the bottom portion 31 in a direction orthogonal to the plate surface of the bottom portion 31.

[0045] In the 1st side wall 321 of the four side walls 32, the 1st through-hole 323 that penetrates the 1st side wall 321 is formed. In addition, in the 2nd side wall 322 of the four side walls 32, which is opposite to the 1st side wall 321, the 2nd through-hole 324 that penetrates the 2nd side wall 322 is formed. The inflow pipe 25 is inserted into the 1st through-hole 323, and the outflow pipe 26 is inserted into the 2nd through-hole 324.

[0046] Further, at the side end surfaces of the cover 22 of the four side walls 32, grooves 325 for fitting O-rings 23 are formed around the opening of the housing main body 21, and internal threads 326 for fastening the bolts 24 are formed at the four corners outside the grooves 325.

[0047] The cover 22 is a flat plate-like member. At the four corners of the cover 22, holes 221 for the bolts 24 to pass through are formed.

[0048] At the surface of the cover 22 on the housing main body 21 side, i.e., the inner surface 222, the heat sink 10 is joined. The method of joining will be described later.

[0049] On the other hand, at the surface of the cover 22 on the side opposite to the inner surface 222, i.e., the outer surface 223, the semiconductor module 5 is joined.

[0050] Here, the semiconductor module 5 has an insulating substrate 51, a wiring layer 52 provided on the insulating substrate 51, and a semiconductor element 53 mounted on the wiring layer 52 via a solder layer 54. Further, the semiconductor module 5 has a heat transfer layer 55 that transmits heat from the insulating substrate 51 to the cooling device 1.

[0051] Further, the heat transfer layer 55 of the semiconductor module 5 is joined to the outer surface 223 of the cover 22. As the method of joining the heat transfer layer 55 to the cover 22, brazing, soldering, sintering, adhesion using a resin, adhesion using a thermally conductive paste, etc. can be exemplified.

[0052] The heat sink 10 has a flat plate-like flat plate portion 11, and a plurality of columnar fins 12 that protrude from the flat plate portion 11 in a direction orthogonal to the plate surface.

[0053] The fin 12 can be exemplified as a columnar shape in which the protruding direction from the flat plate portion 11 becomes the column direction. Further, the shape when the fin 12 is viewed from the protruding direction (hereinafter sometimes referred to as "cross-sectional shape") can be exemplified as a circle or an ellipse. Further, the cross-sectional shape can be exemplified as a square, a rectangle, a rhombus, or the like quadrilateral. Further, the fin 12 can also be flat plate-like. In the case where the fin 12 is flat plate-like, it can be parallel to the direction from the inflow pipe 25 toward the outflow pipe 26, or can be wavy with portions inclined with respect to the direction from the inflow pipe 25 toward the outflow pipe 26.

[0054] The heat sink 10 can be exemplified as being formed by forging. Further, the material of the heat sink 10 can be exemplified as A1000 series pure aluminum such as A1100, or copper.

[0055] The cooling device 1 and the semiconductor module 5 configured as above are assembled as follows.

[0056] First, the cover 22 and the semiconductor module 5 are brazed.

[0057] Subsequently, the cover 22, to which the semiconductor module 5 is attached, is joined to the heat sink 10 using laser welding. This joining process will be described in detail later.

[0058] Next, the cover 22, to which the heat sink 10 is attached, is placed over the housing body 21 such that the semiconductor module 5 is located on the outside and the heat sink 10 is housed inside the housing 20, and the cover 22 covers the opening of the housing body 21. When the cover 22 is placed over the housing body 21, the O-ring 23 is pre-embedded in the groove 325 formed in the housing body 21.

[0059] After the cover 22 is placed over the housing body 21, the bolt 24, which is inserted into the hole 221 formed in the cover 22, is tightened into the internal thread 326 formed in the housing body 21.

[0060] Thus, a flow space 35 for coolant to flow is formed in the space enclosed between the radiator 10 and the recess 34 of the housing body 21. The flow space 35 is sealed by an O-ring 23.

[0061] Next, the method of attaching the heat sink 10 to the cover 22 will be described.

[0062] Figure 3 This is a diagram illustrating the connection between the radiator 10 and the cover 22.

[0063] Figure 4 This is a diagram showing an example of the welded part 40.

[0064] like Figure 3 As shown, the flat plate portion 11 of the heat sink 10 is placed on the cover 22 in a contact manner, so that the cover 22 overlaps with the heat sink 10. Then, the laser head 151 of the laser device 150 irradiates the flat plate portion 11 between the plurality of fins 12 from the side of the plurality of fins 12 of the heat sink 10 with laser L. Then, the laser head 151 is moved along the shape of the gap between the plurality of fins 12, thereby continuously irradiating the flat plate portion 11 with laser L.

[0065] When laser L irradiates the flat plate portion 11 of the heat sink 10, the energy of laser L is converted into heat, thereby melting the flat plate portion 11 of the heat sink 10 and the base material of the cover 22, followed by rapid cooling. Due to this rapid heating / cooling, a microstructure change occurs in the welded portion 40, which consists of a molten portion 41 that has melted and then solidified, and a heat-affected zone 42 that has undergone microstructure change due to the welding heat. The heat-affected zone 42 consists of the heat-affected zone 42h of the flat plate portion 11 and the heat-affected zone 42c of the cover 22.

[0066] Also, in the present embodiment, laser welding is performed in such a manner that the molten portion 41 does not penetrate the cover 22. This is to suppress the occurrence of unevenness on the outer surface 223 of the cover 22 to which the semiconductor module 5 is joined, due to the molten portion 41 penetrating the cover 22. To perform laser welding in such a manner that the molten portion 41 does not penetrate the cover 22, the energy density per unit time is adjusted. As the energy density per unit time becomes larger, a deeper molten portion 41 is formed, and thus the energy density per unit time is made smaller than the energy density per unit time when the cover 22 is penetrated. To reduce the energy density per unit time, the moving speed of the laser head 151 is increased. Alternatively, to reduce the energy density per unit time, the laser output is reduced. Thus, by adopting at least either of increasing the moving speed of the laser head 151 and reducing the laser output, laser welding can be performed in such a manner that the molten portion 41 does not penetrate the cover 22.

[0067] In the cooling device 1 configured as described above, the heat sink 10 having the flat plate portion 11 in a flat plate shape and the plurality of fins 12 protruding from the flat plate portion 11, and the housing 20 accommodating the heat sink 10 and forming the flow-through space 35 as an example of a space through which a coolant flows, are provided, and the heat sink 10 is joined to the housing 20 by irradiating the flat plate portion 11 between the plurality of fins 12 with the laser light L from the plurality of fins 12 side. Thus, for example, compared with a configuration in which the heat sink 10 and the housing 20 are joined by brazing, since annealing of the entire cooling device 1 does not occur when brazing is performed, a case in which the strength of the housing main body 21 and / or the cover 22 is reduced due to annealing can be suppressed. Also, since the heat sink 10 is joined to the housing 20 by irradiating the heat sink 10 with the laser light L from the fins 12 side, compared with a configuration in which the heat sink 10 is joined to the housing 20 by irradiating the heat sink 10 with the laser light L from the housing 20 side, a case in which unevenness is formed in the housing 20 can be suppressed.

[0068] Here, the case 20 has a bottomed concave case main body 21, and a cover 22 that covers an opening portion of the case main body 21 and holds the semiconductor module 5 on the side opposite to the case main body 21. The heat sink 10 is joined to the inner surface 222 of the cover 22 as an example of a portion on the side opposite to the semiconductor module 5. By irradiating the laser light L from the fin 12 side of the heat sink 10, it is possible to suppress the occurrence of unevenness on the surface of the portion of the cover 22 that holds the semiconductor module 5 due to the formation of a weld portion at the portion. For example, in the case where the laser light L is irradiated to the outer surface 223 of the cover 22 in order to join the heat sink 10 to the cover 22, a weld portion is formed on the outer surface 223 of the cover 22, and unevenness is formed. When the gap between the cover 22 and the semiconductor module 5 becomes large due to the unevenness, it can not be possible to efficiently transfer heat from the semiconductor module 5 to the cover 22, and the cooling performance deteriorates. In addition, in the case where, for example, a thermally conductive paste is used as the heat transfer layer 5, it is necessary to increase the amount of the thermally conductive paste that fills the gap between the cover 22 and the semiconductor module 5. In addition, in order to prevent these cases, if the machining of cutting is performed in order to form a flat surface that eliminates the unevenness of the weld portion formed on the outer surface 223 of the cover 22, the manufacturing man-hours increase, and thus the manufacturing cost increases. In the cooling device 1 of the above-described embodiment, unevenness is less likely to occur on the surface of the portion of the cover 22 that holds the semiconductor module 5, and thus it is possible to suppress the above-described cases where the cooling performance deteriorates and the cost increases due to the occurrence of unevenness.

[0069] Figure 5 is a view that shows an example of a weld path.

[0070] As Figure 5 shown, the laser light L is irradiated in such a manner that weld portions 40 are formed between all of the adjacent fins 12 among the plurality of fins 12 whose cross-sectional shape is a rhombus. In addition, when the laser light L is irradiated, the laser head 151 is moved in such a manner that it reciprocates in the same direction. For example, the operation of irradiating while moving the laser head 151 in the first direction Ml from the lower left toward the upper right of Figure 5 , and the operation of irradiating while moving in the second direction M2 from the upper right toward the lower left are repeated. Also, in the case where the right end portion is reached, the operation of irradiating while moving the laser head 151 in the third direction M3 from the lower right toward the upper left, and the operation of irradiating while moving in the fourth direction M4 from the upper left toward the lower right are repeated.

[0071] Thus, it is possible to quickly and highly accurately form the weld portions 40.

[0072] Figure 6 is a view that shows an example of a weld path when the heat sink 10 having the wave-shaped fins 12 is joined to the cover 22.

[0073] Even if the fins 12 are in a wave shape, the laser L is irradiated in a manner that welds 40 are formed between all of the adjacent fins 12 among the plurality of fins 12. For example, the operation of irradiating while moving the laser head 151 in the fifth direction M5 from the left toward the right, and irradiating while moving in the sixth direction M6 from the right toward the left is repeated. Figure 6

[0074] Thus, the welds 40 can be formed quickly and with high accuracy.

[0075] (Regarding the materials of the heat sink 10 and the cover 22)

[0076] The materials of the heat sink 10 and the cover 22 can be exemplified as described below.

[0077] That is, the materials of the heat sink 10 and the cover 22 can be exemplified as being the same, both being copper or aluminum. Alternatively, the materials of the heat sink 10 and the cover 22 can be exemplified as being different, either being copper and the other being aluminum. For example, the heat sink 10 is aluminum and the cover 22 is copper, whereby the heat sink 10 can be easily formed by forging, and the heat conductivity of the cover 22 can be improved, so the cooling performance of the cooling device 1 can be improved.

[0078] Alternatively, the heat sink 10 can be formed of aluminum, and the cover 22 can be formed of aluminum as a clad material with the heat sink 10 at the joint surface. Thus, the heat sink 10 can be easily formed by forging, and the portion of the cover 22 to which the heat sink 10 is joined is aluminum like the heat sink 10, so the joint can be easily performed by laser welding. In addition, the portion of the cover 22 to which the semiconductor module 5 is joined is copper, so heat from the semiconductor module 5 can be rapidly transmitted to the heat sink 10, so the cooling performance of the cooling device 1 can be improved.

[0079] (Regarding the shape of the fins 12)

[0080] Figure 7 is a view showing an example of a modification of the shape of the fins 12.

[0081] As shown in Figure 7 , the fins 12 can be formed in such a manner that the surface of the fin 12 opposite to the adjacent fin 12 is inclined with respect to the protruding direction in such a manner that the distance between the adjacent fins 12 gradually decreases from the tip end portion 121 to the base end portion 122. Thus, the laser L irradiated between the adjacent fins 12 can be prevented from being irradiated to the fin 12.

[0082] Alternatively, as shown in Figure 7 ​As shown, the fin 12 can have a chamfer 123 at the front end portion 121. Thereby, the laser light L irradiated between the adjacent fins 12 can be inhibited from reaching the front end portion 121. Note that the fin 12 can have an R portion obtained by rounding a corner of the front end portion 121 of the fin 12 instead of the chamfer 123. Even with the R portion, the laser light L can be inhibited from reaching the front end portion 121. In addition, the fin 12 can have an R portion at a corner of the chamfer 123.

[0083] <2nd Embodiment>

[0084] The cooling device 2 of the 2nd embodiment differs from the cooling device 1 of the 1st embodiment in the shape of the weld portion 40. Hereinafter, points different from the 1st embodiment will be described. The same reference numerals are used for portions having the same function in the 1st and 2nd embodiments, and detailed description thereof will be omitted.

[0085] Figure 8 Fig. 10 is a view showing an example of the weld portion 240 of the 2nd embodiment.

[0086] As for the weld portion 240 of the 2nd embodiment, the molten portion 241 is formed at the flat plate portion 11, the base end portion 122 of the fin 12, and the cover 22, unlike the 1st embodiment in which the weld portion 40 is not formed with the molten portion 41 at the base end portion 122 of the fin 12. In other words, the laser welding is performed in a manner that the molten portion 241 is formed at the flat plate portion 11, the base end portion 122 of the fin 12, and the cover 22. In order to perform the laser welding in a manner that the molten portion 241 is formed at the base end portion 122 of the fin 12 as well, it is sufficient to increase the energy density per unit time compared to the formation of the weld portion 40 of the 1st embodiment. In order to increase the energy density per unit time, it is sufficient to decrease the moving speed of the laser head 151. In addition, in order to increase the energy density per unit time, it is sufficient to increase the laser output. Therefore, by adopting at least either of the method of decreasing the moving speed of the laser head 151 and the method of increasing the laser output, the laser welding can be performed in a manner that the molten portion 241 is formed at the base end portion 122 of the fin 12 as well.

[0087] Further, by forming the molten portion 241 at the base end portion 122 of the fin 12 as well in this way, the width W of the molten portion 241 at the joint interface between the heat sink 10 and the cover 22 can be increased compared to the case where the molten portion 41 is not formed at the base end portion 122 of the fin 12. As a result, the thermal conductivity between the heat sink 10 and the cover 22 can be improved, so the cooling performance can be improved.

[0088] <3rd Embodiment>

[0089] The cooling device 3 of the third embodiment differs from the cooling device 1 of the first embodiment in that the heat sink 10 is joined to the case main body 21. Hereinafter, points of difference from the first embodiment will be described. The same reference numerals are used for parts having the same function in the first and third embodiments, and detailed description thereof will be omitted.

[0090] Figure 9 is a view showing an example of a cross section of the cooling device 3 of the third embodiment.

[0091] In the cooling device 3, the semiconductor module 5 is joined to the bottom portion 31 of the case main body 21 on the side opposite the cover 22. Also, the heat sink 10 is joined to the bottom surface 311 of the bottom portion 31 of the case main body 21, which is the side opposite the semiconductor module 5.

[0092] As for the method of joining the heat sink 10 to the case main body 21, the same method as that described above for joining the heat sink 10 to the cover 22 is used. That is, the case main body 21 is overlapped with the heat sink 10 in such a manner that the flat plate portion 11 of the heat sink 10 is placed in contact on the bottom surface 311 of the case main body 21. Also, the flat plate portion 11 between the plurality of fins 12 of the heat sink 10 is irradiated with laser light L from the side of the plurality of fins 12. Figure 3

[0093] Also, in the present embodiment, laser welding is performed in such a manner that the molten portion formed by irradiation with laser light L does not penetrate the case main body 21. This is to suppress the occurrence of unevenness on the outer surface 211 of the case main body 21 for joining the semiconductor module 5, due to the molten portion penetrating the case main body 21.

[0094] In addition, the molten portion of the third embodiment can be formed in the same manner as the molten portion 41 of the first embodiment, that is, in the flat plate portion 11 of the heat sink 10 and the case main body 21, or in the same manner as the molten portion 241 of the second embodiment, that is, in the flat plate portion 11 of the heat sink 10, the base end portion 122 of the fin 12, and the case main body 21.

[0095] Also, the cooling device 3 and the semiconductor module 5 configured as described above can be assembled as follows.

[0096] First, the semiconductor module 5 and the case main body 21 are brazed.

[0097] Subsequently, the case main body 21 to which the semiconductor module 5 is joined is joined to the heat sink 10 by laser welding.

[0098] ​Next, the cover 22 is covered on the case main body 21, and the bolt 24 inserted through the hole 221 formed in the cover 22 is fastened to the internal thread 326 formed in the case main body 21. At the time of covering the cover 22 on the case main body 21, the O-ring 23 is embedded in the groove 325 formed in the case main body 21 in advance.

[0099] With the cooling device 3 thus configured, compared with a configuration in which the heat sink 10 and the case main body 21 are joined by brazing, since annealing of the entire cooling device 3 does not occur at the time of performing brazing, a case in which the strength of the case main body 21 and / or the cover 22 is reduced due to annealing can be suppressed. Further, since the heat sink 10 is joined to the case main body 21 by irradiating the laser L from the fin 12 side of the heat sink 10, compared with a configuration in which the heat sink 10 is joined to the case main body 21 by irradiating the laser L from the case main body 21 side, a case in which a concave-convex is formed on the outer surface 211 of the case main body 21 can be suppressed. That is, in the cooling device 3, the outer surface 211 of the case main body 21, which is a surface that holds the semiconductor module 5, is less likely to have a concave-convex formed therein, so a case in which the cooling performance deteriorates and the cost increases due to the formation of a concave-convex can be suppressed.

[0100] <4th Embodiment>

[0101] The cooling device 4 of the 4th embodiment is an air-cooled cooling device that cools the semiconductor module 5, which is an example of a heat generating body, using air and the heat sink 10, unlike the cooling device 1 of the 1st embodiment. Hereinafter, points different from the 1st embodiment will be described. The same reference numerals are used for portions having the same function in the 1st embodiment and the 4th embodiment, and detailed description thereof will be omitted.

[0102] Figure 10 is a view that shows an example of a cross section of the cooling device 4 of the 4th embodiment.

[0103] The cooling device 4 includes the heat sink 10 and a base 60 that holds the heat sink 10.

[0104] The base 60 is a flat plate-like member. On the base 60, for example, a hole 60h through which a bolt 64 for mounting to an article to which the cooling device 4 is to be attached is formed at the four corners.

[0105] Further, on the base 60, the heat sink 10 is joined to a first surface 61, which is one of the surfaces, and the semiconductor module 5 is joined to a second surface 62, which is the other surface, as with the cover 22 of the 1st embodiment.

[0106] The method of joining the semiconductor module 5 to the base 60 is the same as the method of joining the semiconductor module 5 to the cover 22 of the 1st embodiment.

[0107] In addition, the method of joining the heat sink 10 to the base 60 is the same as the method of joining the heat sink 10 to the cover 22 of the first embodiment. That is, the base 60 is overlapped with the heat sink 10 in such a manner that the flat plate portion 11 of the heat sink 10 is placed in contact with the first face 61 of the base 60. Then, the flat plate portion 11 between the plurality of fins 12 of the heat sink 10 is irradiated with the laser light L from the side of the plurality of fins 12.

[0108] In addition, in the present embodiment, the laser welding is performed in such a manner that the molten portion formed by the irradiation of the laser light L does not penetrate the base 60. This is to suppress the occurrence of a concavo-convex on the second face 62 of the base 60 for joining the semiconductor module 5 due to the penetration of the molten portion into the base 60.

[0109] In addition, the molten portion of the fourth embodiment can be formed in the flat plate portion 11 of the heat sink 10 and the base 60 as in the molten portion 41 of the first embodiment, or can be formed in the flat plate portion 11 of the heat sink 10, the base end portion 122 of the fin 12, and the base 60 as in the molten portion 241 of the second embodiment.

[0110] With the cooling device 4 thus configured, compared with the configuration in which the heat sink 10 and the base 60 are joined by brazing, since the entire cooling device 4 is not annealed when the brazing is performed, the decrease in the strength of the base 60 due to the annealing can be suppressed. In addition, since the heat sink 10 and the base 60 are joined by irradiating the laser light L from the side of the fin 12 of the heat sink 10, compared with the configuration in which the heat sink 10 and the base 60 are joined by irradiating the laser light L from the side of the base 60, the occurrence of a concavo-convex on the second face 62 of the base 60 can be suppressed. That is, in the cooling device 4, the second face 62 of the base 60, which is the surface of the base 60 on which the semiconductor module 5 is held, is less likely to have a concavo-convex, so the above-described deterioration of the cooling performance and the increase in the cost due to the occurrence of the concavo-convex can be suppressed.

Claims

1. A cooling device comprising: a heat sink having a flat plate portion in a flat plate shape and a plurality of fins protruding from the flat plate portion; and a case housing the heat sink, the heat sink being joined to the case by irradiating laser light to the flat plate portion between the plurality of fins from the plurality of fin side, a fusion portion being formed in the flat plate portion, the fins, and the case.

2. The cooling device according to claim 1, wherein the case has a case main body in a bottomed recess shape, and a cover covering an opening portion of the case main body and holding a heat generating body on a side opposite to the case main body, the heat sink being joined to a portion of the cover on a side opposite to the heat generating body.

3. The cooling device according to claim 1, wherein the case has a case main body in a bottomed recess shape, and a cover covering an opening portion of the case main body, and holding a heat generating body on a side of a bottom portion of the case main body opposite to the cover, the heat sink being joined to a portion of the bottom portion of the case main body on a side opposite to the heat generating body.

4. The cooling device according to claim 1, wherein a surface of the fin opposite to an adjacent fin is inclined with respect to a protruding direction in a manner such that a distance between the adjacent fin is gradually reduced from a tip end portion to a base end portion.

5. The cooling device according to claim 1, wherein the fin has at least either one of a chamfer and an R portion at a tip end portion.

6. The cooling device according to claim 1, wherein the heat sink is formed of aluminum or copper.

7. The cooling device according to claim 1, wherein a portion of the case to which the heat sink is joined is formed of at least either one of aluminum and copper.

8. The cooling device according to claim 1, wherein the heat sink is formed of aluminum, a portion of the case to which the heat sink is joined is formed of clad material of aluminum and copper, the aluminum becoming a joining surface with the heat sink.

9. A cooling device comprising: a heat sink having a flat plate portion in a flat plate shape and a plurality of fins protruding from the flat plate portion; and a base holding the heat sink, and holding a heat generating body on a side opposite to the heat sink, the heat sink being joined to the base by irradiating laser light to the flat plate portion between the plurality of fins from the plurality of fin side, a fusion portion being formed in the flat plate portion, the fins, and the base.

10. A manufacturing method of a cooling device, bringing a heat sink having a flat plate portion in a flat plate shape and a plurality of fins protruding from the flat plate portion, and a case housing the heat sink in coincidence, joining the heat sink to the case by irradiating laser light to the flat plate portion between the plurality of fins from the plurality of fin side, thereby forming a fusion portion in the flat plate portion, the fins, and the case.

11. A manufacturing method of a cooling device, bringing a heat sink having a flat plate portion in a flat plate shape and a plurality of fins protruding from the flat plate portion, and a base holding the heat sink and holding a heat generating body on a side opposite to the heat sink in coincidence, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The heat sink is joined to the base by irradiating laser light from the plurality of fin sides to the flat plate-shaped portions between the plurality of fins, thereby forming a fused portion in the flat plate-shaped portions, the fins, and the base.

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