Laser welding method and cooler

Abstract

To suppress deformation of a fin member caused by laser beam radiation.SOLUTION: In a laser welding method, a fin member including a flat plate-like part and a plurality of fins that project from a surface of the flat plate-like part and that are arrayed by sandwiching gaps extending in a first direction on the surface, is laser welded to a flat plate-like holding member. In the laser welding method, a gap of the flat plate-like part is irradiated with a laser beam by dividing the gap into a plurality of sections in the first direction.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a laser welding method and a cooler. [Background technology]

[0002] Patent Document 1 discloses a heat sink that is a forged product in which a large number of pin-shaped fins are provided upright integrally with a rectangular base plate at the center of one surface of the base plate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-107679 Summary of the Invention [Problem to be solved by the invention]

[0004] When a fin member having a flat portion and a plurality of fins protruding from the flat portion and arranged across a gap extending in a first direction is laser welded to a flat holding member, the fin member may be deformed if laser light is continuously irradiated onto the gap in the first direction. An object of the present invention is to suppress deformation of a fin member due to irradiation with laser light. [Means for solving the problem]

[0005] The present invention, which was completed with the above object in mind, is a method for laser welding a fin member having a flat plate-shaped portion and a plurality of fins protruding from the surface of the flat plate-shaped portion and arranged on the surface with gaps extending in a first direction therebetween, to a flat plate-shaped holding member, the method comprising: irradiating the gaps in the flat plate-shaped portion with laser light at a plurality of divided positions in the first direction; The length of the portion irradiated with the laser light along the first direction is longer than the length of the portion between the portions irradiated with the laser light that is not irradiated with the laser light along the first direction. This is a laser welding method. Here, with respect to the gap , the first direction while being spaced apart.After performing a first irradiation in which a laser beam is irradiated in divided portions at a plurality of positions in the first direction, the gap is In said interval between A second irradiation is performed by irradiating the laser light. and a length along the first direction of each of the locations irradiated with the laser light in the first irradiation and the second irradiation is longer than a length along the first direction of a location between the locations irradiated with the laser light in the first irradiation and the second irradiation and not irradiated with the laser light. That's good. Furthermore, it is preferable that the fin member has a rectangular flat portion with the first direction as its longitudinal direction, and a plurality of fins, each of which has a flat shape extending in the first direction, arranged in a second direction intersecting the first direction with the gaps therebetween. Preferably, the laser light is not irradiated onto both ends of the gap in the first direction. From another perspective, the present invention provides a fin member including a flat plate-shaped portion and a plurality of fins protruding from a surface of the flat plate-shaped portion and arranged with gaps therebetween extending in a first direction on the surface, and a flat plate-shaped holding member that holds the fin member, wherein the fin member is joined to the holding member by irradiating the holding member with laser light in a divided manner at a plurality of positions in the first direction. The length of the portion irradiated with the laser light along the first direction is longer than the length of the portion between the portions irradiated with the laser light that is not irradiated with the laser light along the first direction. It is a cooler. [Effects of the Invention]

[0006] According to the present invention, it is possible to suppress deformation of the fin member due to irradiation with laser light. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is an example of an exploded view of components constituting a cooling device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram illustrating an example of a cross section of a cooling device. [Figure 3] FIG. 2 is a diagram illustrating an example of a cross section of a cooling device. [Figure 4] FIG. 10 is a view of the heat sink and cover as seen from the side where the fins of the heat sink are formed. [Figure 5] 10A and 10B are diagrams for explaining the joining of the heat sink and the cover. [Figure 6] FIG. 2 is a diagram showing an example of a welded portion. [Figure 7] 10(a) and 10(b) are diagrams illustrating an example of a conventional method for joining a heat sink and a cover. [Figure 8] 10(a) and 10(b) are diagrams showing an example of a laser light irradiation method when joining a heat sink and a cover. [Figure 9] 10(a) and 10(b) are diagrams showing an example of a laser light irradiation method when joining a heat sink and a cover. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. FIG. 1 is an example of an exploded view of components constituting a cooling device 1 according to this embodiment. Figures 2 and 3 are diagrams showing an example of a cross section of the cooling device 1. Figure 2 is a diagram showing an example of a cross section of the cooling device 1 taken along a longitudinal direction, which will be described later, and Figure 3 is a diagram showing an example of a cross section of the cooling device 1 taken along a lateral direction, which will be described later. The cooling device 1 according to the embodiment includes a heat sink 10 having fins 12, and a case 20 that houses the heat sink 10 and forms a space through which a coolant flows. The cooling device 1 is a liquid-cooling type cooling device that cools a semiconductor module 5, which is an example of a heat generating body, using the coolant and the heat sink 10.

[0009] The case 20 includes a case body 21 having a concave bottom, a cover 22 that covers the opening of the case body 21, an O-ring 23 that seals the gap between the case body 21 and the cover 22, and bolts 24 that join the case body 21 and the cover 22. The case 20 also includes an inlet pipe 25 that allows the coolant to flow into the case 20, and an outlet pipe 26 that allows the coolant to flow out of the case 20. Examples of materials for the case body 21 and the cover 22 include A6000 series aluminum alloys such as A6063, aluminum alloy die-casting such as ADC12, and copper.

[0010] The case body 21 has a flat rectangular bottom 31 and four side walls 32 that protrude from the peripheral edges of the bottom 31 in directions perpendicular to the plate surface of the bottom 31 . A first through-hole 323 penetrating the first side wall 321 is formed in a first side wall 321 of the four side walls 32. A second through-hole 324 penetrating the second side wall 322 is formed in a second side wall 322 facing the first side wall 321 of the four side walls 32. An inlet pipe 25 is fitted in the first through-hole 323, and an outlet pipe 26 is fitted in the second through-hole 324. In addition, on the end faces of the four side walls 32 facing the cover 22, a groove 325 into which an O-ring 23 is fitted is formed around the opening of the case body 21, and female threads 326 into which bolts 24 are tightened are formed at each of the four outer corners of the groove 325.

[0011] The cover 22 is a flat plate-shaped member, and holes 221 for passing the bolts 24 are formed at the four corners of the cover 22. The heat sink 10 is joined to an inner surface 222 of the cover 22, which is the surface on the case body 21 side.

[0012] On the other hand, the semiconductor module 5 is joined to an outer surface 223 of the cover 22, which is the surface opposite to the inner surface 222. 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 attached to the wiring layer 52 via a solder layer 54. The semiconductor module 5 also has a heat transfer layer 55 that transfers heat from the insulating substrate 51 to the cooling device 1. In the semiconductor module 5, the heat transfer layer 55 is joined to the outer surface 223 of the cover 22. Examples of methods for joining the heat transfer layer 55 and the cover 22 include brazing, soldering, sintering, bonding with resin, and pasting with thermally conductive grease.

[0013] The heat sink 10 has a flat plate-shaped portion 11 and a plurality of fins 12 protruding from the flat plate-shaped portion 11 in a direction perpendicular to the plate surface. The flat plate portion 11 is a rectangular member having a longitudinal direction, which is an example of a first direction, and a lateral direction, which is an example of a second direction perpendicular to the longitudinal direction. The flat plate portion 11 has a front surface 111 from which a plurality of fins 12 protrude, and a back surface 112 joined to the inner surface 222 of the cover. In the description of this embodiment, the longitudinal direction and the lateral direction of the flat plate portion 11 may be simply referred to as the longitudinal direction and the lateral direction, respectively.

[0014] Each fin 12 is a flat member extending in the longitudinal direction and in a direction perpendicular to the plate surface of the flat portion 11. The multiple fins 12 are arranged side by side across gaps 113 extending in the longitudinal direction on the surface 111 of the flat portion 11. In this example, each fin 12 is provided parallel to the direction from the inlet pipe 25 to the outlet pipe 26 (the flow direction of the coolant in the flow space 35, which will be described later).

[0015] FIG. 4 is a view of the heat sink 10 and the cover 22 as viewed from the side of the heat sink 10 on which the fins 12 are formed. Although the details will be described later, the heat sink 10 and the cover 22 are joined by irradiating a laser beam from the heat sink 10 side to the portion where the heat sink 10 and the cover 22 are stacked. In addition, the heat sink 10 and the cover 22 are joined by irradiating a laser beam along a gap 113 formed on the surface of the flat plate portion 11 of the heat sink 10 to the portion where the heat sink 10 and the cover 22 are stacked.

[0016] 4, welds 40 are formed on the heat sink 10 and the cover 22 by irradiating the heat sink 10 with laser light to melt the materials that make up the heat sink 10 and the cover 22. In addition, the heat sink 10 and the cover 22 have welds 40 that extend along the gaps 113 in the flat portion 11 of the heat sink 10. More specifically, the heat sink 10 and the cover 22 have welds 40 that are divided into multiple locations (five in this example) in the longitudinal direction along the gaps 113.

[0017] The cooling device 1 and the semiconductor module 5 configured as above are assembled as follows. First, the cover 22 and the semiconductor module 5 are brazed together. Thereafter, the cover 22 to which the semiconductor module 5 is joined and the heat sink 10 are joined by laser welding. Then, the cover 22 to which the heat sink 10 is joined is placed on the case body 21 so that the semiconductor module 5 is located on the outside and the heat sink 10 is housed inside the case 20, and the opening of the case body 21 is covered with the cover 22. When the cover 22 is placed on the case body 21, an O-ring 23 is fitted into a groove 325 formed in the case body 21. After the cover 22 is placed on the case body 21 , the bolt 24 is passed through the hole 221 formed in the cover 22 and tightened into the female screw 326 formed in the case body 21 . As a result, a flow space 35 through which the coolant flows is formed in the space surrounded by the heat sink 10 and the recess 34 of the case body 21. In this example, the flow direction of the coolant through the flow space 35 is parallel to the longitudinal direction. The flow space 35 is sealed with an O-ring 23.

[0018] Next, a method for joining the heat sink 10 to the cover 22 will be described. FIG. 5 is a diagram for explaining the joining of the heat sink 10 and the cover 22. As shown in FIG. FIG. 6 is a diagram showing an example of a welded portion 40. As shown in FIG. As shown in FIG. 5, the cover 22 and the heat sink 10 are placed on top of each other so that the back surface 112 of the flat portion 11 of the heat sink 10 is in contact with each other. Furthermore, as shown in FIG. 5 and FIGS. 8(a) and 8(b), which will be described later, pressing members 9 for pressing the fins 12 are attached to both longitudinal ends of the heat sink 10. Then, from the side of the fins 12 of the heat sink 10, a laser head 157 of the laser device 150 irradiates a laser beam L onto gaps 113 formed between the fins 12 on the surface 111 of the flat portion 11. The laser head 157 is moved along the gaps 113 formed between the fins 12 to irradiate the laser beam L. As will be described in detail later, in this example, the laser beam L is irradiated onto the gaps 113 at multiple locations in the longitudinal direction. The laser source of the laser device 150 is not particularly limited. Examples include a YAG laser, a CO laser, a fiber laser, a disk laser, and a semiconductor laser.

[0019] When laser light L is irradiated onto flat plate portion 11 of heat sink 10, the energy of laser light L is converted into heat, causing the base materials of flat plate portion 11 of heat sink 10 and cover 22 to melt and then rapidly cool. This rapid heating and cooling causes a structural change in welded portion 40, and welded portion 40 is composed of melted portion 41 that has melted and solidified and heat-affected zone 42 that has undergone a structural change due to the heat of fusion. Heat-affected zone 42 is composed of heat-affected zone 42h of flat plate portion 11 and heat-affected zone 42c of cover 22.

[0020] Here, from the viewpoint of preventing unevenness from occurring on the outer surface 223 of the cover 22 to which the semiconductor module 5 is joined, it is preferable to irradiate the laser light L so that the molten portion 41 does not penetrate the cover 22. To perform laser welding so that the molten portion 41 does not penetrate the cover 22, the energy density per unit time of the laser light L can be adjusted. Since a deeper molten portion 41 is formed as the energy density per unit time increases, the energy density per unit time of the laser light L is reduced so that the molten portion 41 is smaller than the size that would allow it to penetrate the cover 22. In addition, the energy density per unit time of the laser light L can be reduced by increasing the movement speed of the laser head 157 or by reducing the laser output.

[0021] Incidentally, when joining the heat sink 10 and the cover 22 by laser welding by irradiating laser light L along the gaps 113 extending longitudinally between the multiple fins 12, depending on how the laser light L is irradiated, deformation of the heat sink 10 may be more likely to occur. 7(a) and 7(b) are diagrams illustrating an example of a conventional method for joining a heat sink 10 and a cover 22, and are views of the heat sink 10 placed on the cover 22 (see FIG. 5, etc.) as viewed from the fin 12 side. FIG. 7(a) is a diagram showing an example of the path of irradiation of laser light L, and FIG. 7(b) is a diagram showing an example of the state of the heat sink 10 after irradiation with laser light L. The heat sink 10 and cover 22 shown in FIGS. 7(a) and 7(b) have the same configuration as the heat sink 10 and cover 22 in the cooling device 1 of the present embodiment shown in FIG. 1, etc.

[0022] 7(a), similarly to the present embodiment, the heat sink 10 and the cover 22 are stacked one on top of the other, and the pressing members 9 for pressing the fins 12 are attached to both ends of the heat sink 10 in the longitudinal direction. Then, laser light L is irradiated continuously from one end to the other in the longitudinal direction along each gap 113 of the heat sink 10, as shown by arrow B. Furthermore, the laser light L is not irradiated onto both ends of the gap 113 in the longitudinal direction where the pressing members 9 are attached.

[0023] As described above, when the flat plate portion 11 of the heat sink 10 is irradiated with the laser light L, the energy of the laser light L is converted into heat, causing the base material of the flat plate portion 11 of the heat sink 10 and the cover 22 to melt and then rapidly cool. As a result, the base material of the heat sink 10 and the cover 22 may shrink in the area irradiated with the laser light L as it cools and solidifies. As shown in Figure 7(a), when laser light L is irradiated continuously from one end to the other end of the longitudinal direction along the gap 113 of the heat sink 10, the base material of the heat sink 10 contracts and deforms over the entire area from one end to the other end of the longitudinal direction at the area irradiated with the laser light L, whereas deformation of the base material of the heat sink 10 is less likely to occur at both ends of the longitudinal direction where the laser light L is not irradiated. As a result, as shown in FIG. 7(b), the heat sink 10 is deformed so that the distance between the fins 12 (the width of the gap 113) at the center in the longitudinal direction becomes narrower than at both ends in the longitudinal direction.

[0024] In contrast to this, in this embodiment, from the viewpoint of suppressing deformation of the heat sink 10, the laser light L is irradiated onto the gap 113 of the heat sink 10 at a plurality of locations in the longitudinal direction. Figures 8(a) to (b) are diagrams showing an example of a method of irradiating laser light L when joining a heat sink 10 and a cover 22, and are diagrams showing the heat sink 10 placed on the cover 22 (see Figure 5, etc.) as viewed from the fin 12 side. Next, a method of applying the laser light L when joining the heat sink 10 and the cover 22 in this embodiment will be specifically described.

[0025] First, as shown in FIG. 8(a), the gaps 113 of the heat sink 10 are irradiated with laser light L, which is divided into multiple positions in the longitudinal direction. Specifically, as shown by arrow A1 in FIG. 8(a), the laser light L is irradiated into each gap 113 of the heat sink 10 at multiple positions in the longitudinal direction (three positions in this example) with a gap in the longitudinal direction. As a method for dividing the laser light L into multiple positions in the longitudinal direction and irradiating it, for example, there is a method for repeatedly irradiating and extinguishing the laser light L while moving the laser head 157 in the longitudinal direction. As another method for dividing the laser light L into multiple positions in the longitudinal direction and irradiating it, there is a method for placing a blocking plate on the heat sink 10 that blocks the progression of the laser light L, thereby providing portions in the gaps 113 of the heat sink 10 that are irradiated with the laser light L and portions that are not irradiated with the laser light L. Note that the method for dividing the laser light L into multiple positions in the longitudinal direction and irradiating it is not limited to these. As shown in FIG. 8(a), the step of irradiating the gap 113 of the heat sink 10 with laser light L at multiple locations in the longitudinal direction corresponds to the first irradiation.

[0026] Next, as shown in Fig. 8(b), laser light L is irradiated to the gap 113 of the heat sink 10 between the locations irradiated with the laser light L in the first irradiation. Specifically, as shown by arrows A2 in Fig. 8(b), laser light L is irradiated to a plurality of locations (two locations in this example) in the longitudinal direction between the locations irradiated with the laser light L in the first irradiation to form the welded portion 40A. As shown in FIG. 8(b), the step of irradiating the gap 113 of the heat sink 10 with the laser light L between the locations irradiated with the laser light L in the first irradiation corresponds to the second irradiation. In the first and second irradiations, the laser light L is not irradiated onto both ends in the longitudinal direction of the heat sink 10 to which the pressing member 9 is attached.

[0027] By the above-described first and second irradiations of laser light L, as shown in FIG. 4 above, welds 40 are formed in the heat sink 10 and the cover 22 along the respective gaps 113, and are divided into multiple locations (five in this example) in the longitudinal direction.

[0028] In this way, by irradiating the laser light L to the gap 113 of the heat sink 10 at multiple locations in the longitudinal direction, deformation of the heat sink 10 can be suppressed compared to when the laser light L is irradiated continuously from one end to the other end in the longitudinal direction. When the laser beam L is irradiated to the gap 113 of the heat sink 10 at multiple locations in the longitudinal direction, continuous shrinkage from one end to the other in the longitudinal direction due to the base material constituting the heat sink 10 and the cover 22 melting, cooling, and solidifying is suppressed. This is thought to suppress deformation of the entire heat sink 10 compared to when the laser beam L is irradiated continuously from one end to the other in the longitudinal direction.

[0029] Here, when laser light L is irradiated onto the gap 113 of the heat sink 10 at multiple locations in the longitudinal direction, the laser light L may be irradiated so that the ends of the welds 40 formed adjacent to each other in the longitudinal direction overlap, or the laser light L may be irradiated so that the ends of the welds 40 formed adjacent to each other in the longitudinal direction do not overlap. From the viewpoint of joining the heat sink 10 and the cover 22 with higher accuracy, it is preferable to irradiate the welded portions 40 so that no gaps are formed between the welded portions 40 that are adjacent to each other in the longitudinal direction.

[0030] Furthermore, in the present embodiment, the laser light L is irradiated onto the gap 113 of the heat sink 10 at five separate locations, and five separate welded portions 40 are formed along each gap 113 in the heat sink 10 and the cover 22, but this is not limited to this. From the viewpoint of suppressing deformation of the heat sink 10 compared to when the laser light L is irradiated onto the gap 113 of the heat sink 10 continuously from one end to the other in the longitudinal direction, it is sufficient to irradiate the laser light L onto the gap 113 of the heat sink 10 at two or more separate locations. The more locations where the laser light L is divided in the longitudinal direction and irradiated into the gaps 113 of the heat sink 10, the more likely it is that deformation of the heat sink 10 can be suppressed, but the operation of irradiating the laser light L can become complicated. The number of locations where the laser light L is divided in the longitudinal direction and irradiated into the gaps 113 of the heat sink 10 is preferably determined depending on the ease of deformation of the heat sink 10, the size of the heat sink 10, the manufacturing process of the cooling device 1, etc.

[0031] Furthermore, in the present embodiment, when joining the heat sink 10 and the cover 22, the laser light L is irradiated in a first irradiation and a second irradiation, but the irradiation method is not limited to this as long as the laser light L is irradiated to a plurality of positions in the longitudinal direction of the gaps 113 of the heat sink 10. For example, the laser light L may be irradiated sequentially from one end to the other end in the longitudinal direction to a plurality of positions in the longitudinal direction of each gap 113, or the laser light L may be irradiated in three or more divided irradiations to a plurality of positions in the longitudinal direction of each gap 113.

[0032] Next, another example of the method of irradiating the laser light L when joining the heat sink 10 and the cover 22 will be described. Figures 9(a) to (b) are diagrams showing an example of a method of irradiating laser light L when joining a heat sink 10 and a cover 22, and are diagrams showing the heat sink 10 placed on the cover 22 (see Figure 5, etc.) as viewed from the fin 12 side.

[0033] In the example shown in FIG. 9(a), the irradiation direction of the laser light L in the second irradiation (the movement direction of the laser head 157 (see FIG. 5)) is different from the examples shown in FIGS. 8(a) and 8(b). That is, in the example shown in Figures 8(a) to (b), when laser light L is irradiated onto the gap 113 of the heat sink 10 at multiple locations in the longitudinal direction, the laser light L is irradiated from one end to the other end in the longitudinal direction (from the left side to the right side in Figures 8(a) to (b)) in both the first irradiation and the second irradiation. In contrast, in the example shown in Figure 9(a), in the first irradiation, laser light L is irradiated from one end in the longitudinal direction to the other end (from the left side to the right side in Figure 9(a)) as shown by arrow A1, while in the second irradiation, laser light L is irradiated from the other end in the longitudinal direction to one end (from the right side to the left side in Figure 9(a)) as shown by arrow A3.

[0034] Furthermore, in the example shown in Figure 9(b), compared to the examples shown in Figures 8(a) to (b), the number of divisions into which the laser light L is irradiated when it is divided into multiple locations in the longitudinal direction for each gap 113 is different. That is, in the example shown in FIGS. 8(a) and 8(b), the laser light L is irradiated onto all of the gaps 113 of the heat sink 10, divided into five locations in the longitudinal direction.

[0035] In contrast, in the example shown in FIG. 9(b), the laser light L is irradiated by dividing it into different numbers in the longitudinal direction depending on the position of the gap 113 in the heat sink 10. Specifically, as shown by arrow A4 in FIG. 9(b), the gaps 113 located at both ends in the short-side direction among the multiple gaps 113 in the heat sink 10 are irradiated with the laser light L by dividing it into seven positions in the longitudinal direction. Furthermore, as shown by arrow A6 in FIG. 9(b), the gap 113 located at the center in the short-side direction among the multiple gaps 113 in the heat sink 10 is irradiated with the laser light L by dividing it into three positions in the longitudinal direction. Furthermore, as shown by arrow A6 in FIG. 9(b), the gaps 113 located between both ends in the short-side direction and the center in the short-side direction among the multiple gaps 113 in the heat sink 10 are irradiated with the laser light by dividing it into five positions in the longitudinal direction. Additionally, in the example shown in FIG. 9(b), the closer the gap 113 is located to both ends in the short side direction, the greater the number of divisions when the laser light L is irradiated by dividing it into multiple locations in the long side direction.

[0036] As shown in Figure 7(b), when laser light L is continuously irradiated onto the gap 113 of the heat sink 10 from one end to the other in the longitudinal direction, the amount of deformation of the heat sink 10 tends to be larger at both ends of the heat sink 10 in the lateral direction and smaller toward the center in the lateral direction. As shown in Figure 9(b), the more the gap 113 is located at both ends in the short direction, the more the number of divisions when irradiating laser light L into multiple locations in the longitudinal direction is increased, making it easier to suppress deformation of the heat sink 10.

[0037] As described above, the laser welding method is a method of laser welding a fin member (e.g., heat sink 10) having a flat portion (e.g., flat portion 11) and a plurality of fins (e.g., fins 12) protruding from the surface (e.g., surface 111) of the flat portion and arranged across a gap (e.g., gap 113) extending in a first direction (e.g., longitudinal direction) on the surface, to a flat holding member (e.g., cover 22), in which laser light is irradiated onto the gap in the flat portion in multiple divided positions in the first direction. This makes it possible to suppress deformation of the fin member caused by irradiation with laser light, compared to when the laser light is continuously irradiated onto the gaps in the flat plate-shaped portion in the first direction.

[0038] The cooler (e.g., case 20) also includes a fin member (e.g., heat sink 10) having a flat portion (e.g., flat portion 11), a plurality of fins (e.g., fins 12) protruding from a surface (e.g., surface 111) of the flat portion and arranged across a gap (e.g., gap 113) extending in a first direction (e.g., longitudinal direction) on the surface, and a flat holding member (e.g., cover 22) that holds the fin member, and the fin member is joined to the holding member by irradiating the holding member with laser light in multiple divided positions in the first direction. This makes it possible to provide a cooler in which deformation of the fin member due to irradiation with laser light is suppressed compared to when laser light is continuously irradiated in the first direction onto the gaps in the flat plate-shaped portion.

[0039] In the above-described cooling device 1 and the manufacturing method of the cooling device 1, the flat portion 11 of the heat sink 10 is a rectangular member having a longitudinal direction and a lateral direction, and the multiple fins 12 are flat members extending in a direction perpendicular to the plate surface of the flat portion 11 and in the longitudinal direction, but the shape, etc. of the heat sink 10 is not limited to this. That is, on the surface 111 of the flat portion 11, gaps 113 extending in a predetermined first direction are formed between the multiple fins 12, and as long as laser light L is irradiated onto these gaps 113 in multiple divided locations in the first direction, the shapes of the flat portion 11 and the fins 12 of the heat sink 10 are not limited. For example, the fins 12 of the heat sink 10 may be flat and extend along the short side direction, or may be columnar and protrude from the flat portion 11 in the columnar direction. [Explanation of symbols]

[0040] 1...cooling device, 9...holding member, 10...heat sink, 11...flat plate portion, 12...fin, 22...cover, 40...welded portion, 41...melted portion, 42...heat-affected portion, 111...surface, 112...back surface, 113...gap

Claims

1. A method for laser welding a fin member having a flat plate-shaped portion and a plurality of fins protruding from a surface of the flat plate-shaped portion and arranged with gaps therebetween, the fins extending in a first direction on the surface, to a flat plate-shaped holding member, the method comprising: irradiating the gap of the flat plate portion with laser light at a plurality of divided positions in the first direction; The length of the portion irradiated with the laser light along the first direction is longer than the length of the portion between the portions irradiated with the laser light that is not irradiated with the laser light along the first direction. Laser welding method.

2. After performing a first irradiation in which laser light is irradiated in divided portions at intervals in the first direction onto the gap at a plurality of positions in the first direction, performing a second irradiation of the gap by irradiating the laser light onto the interval between the locations irradiated with the laser light in the first irradiation; The length along the first direction of each of the locations irradiated with the laser light in the first irradiation and the second irradiation is longer than the length along the first direction of a location between the locations irradiated with the laser light in the first irradiation and the second irradiation and not irradiated with the laser light. The laser welding method according to claim 1 .

3. The fin member has the rectangular flat plate portion with the first direction as its longitudinal direction, and a plurality of the fins each having a flat plate shape extending in the first direction and arranged in a second direction intersecting the first direction with the gap therebetween. The laser welding method according to claim 1 or 2.

4. The laser beam is not irradiated onto both ends of the gap in the first direction. The laser welding method according to any one of claims 1 to 3.

5. a fin member having a flat plate-shaped portion and a plurality of fins protruding from a surface of the flat plate-shaped portion and arranged on the surface with gaps therebetween and extending in a first direction; a flat plate-shaped holding member that holds the fin member; Equipped with the fin member is joined to the holding member by irradiating the holding member with laser light in a divided manner at a plurality of positions in the first direction, The length of the portion irradiated with the laser light along the first direction is longer than the length of the portion between the portions irradiated with the laser light that is not irradiated with the laser light along the first direction. cooler.

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