Cold plate and cooling structure

Abstract

A cold plate according to one aspect of the present disclosure comprises a first plate and a second plate. The first plate is formed of metal and includes: a first surface; a second surface located opposite the first surface; and a plurality of fins formed on the second surface. The second plate is formed of metal and includes: a third surface facing the second surface; and a fourth surface located opposite the third surface. The second plate includes: a first region facing the plurality of fins; and a second region located outside the first region. In the second region, the second plate is joined to the first plate by laser welding. The thickness of the second region of the second plate is smaller than the thickness of the first region of the second plate. A melted part melted by the laser welding extends from the fourth surface of the second plate to the first plate beyond a joint surface between the first plate and the second plate.

Description

Cold Plate and Cooling Structure

[0001] This application claims priority based on Japanese Patent Application No. 2024-197309 filed in Japan on November 12, 2024, the content of which is incorporated herein by reference.

[0002] This disclosure relates to a cold plate and a cooling structure.

[0003] Conventionally, air cooling by fans has been the mainstream for computing servers used in data centers, companies, research institutions, etc. On the other hand, semiconductor computing devices for AI (Artificial Intelligence), which are expected to expand in the future, generate much higher heat than in the past. For such heat sources, a water cooling system with a higher cooling capacity than the air cooling method may be used.

[0004] In a water cooling system, cooling is performed by bringing a cold plate into contact with heat sources such as a CPU (Central Processing Unit) and a GPU (Graphical Processing Unit). The cold plate has a water cooling jacket structure in which a flow path for a refrigerant having fins for heat exchange is formed in an internal space. The cold plate is formed, for example, by overlapping and joining metal plates with high thermal conductivity such as copper and aluminum.

[0005] As a method of joining the plates, brazing or diffusion bonding is often adopted, but laser welding can also be adopted (see, for example, Patent Document 1).

[0006] Japanese Patent Application Laid-Open No. 2017-212401

[0007] However, when laser welding is adopted, there is a problem that warping due to thermal deformation is likely to occur because the metal is locally heated and melted by laser light. Such warping becomes larger as the amount of melting of the metal due to welding increases.

[0008] Therefore, one way to suppress warping is to make the thickness of the area to be welded thinner than other areas, thereby reducing the depth of penetration, or in other words, the amount of penetration. However, if this method is used, the rigidity of the area where the thickness is reduced will be lower, making it more susceptible to deformation due to the hydraulic pressure when circulating the coolant. If the cold plate deforms, the contact with the heat source will worsen, which may reduce the efficiency of heat conduction and decrease the cooling performance.

[0009] This disclosure provides a cold plate and a cooling structure that can maintain cooling performance while suppressing deformation caused by laser welding.

[0010] A cold plate according to one aspect of the present disclosure comprises a first plate and a second plate. The first plate is made of metal and has a first surface, a second surface opposite to the first surface, and a plurality of fins formed on the second surface. The second plate is made of metal and has a third surface facing the second surface and a fourth surface opposite to the third surface. The second plate also has a first region facing the plurality of fins and a second region located outside the first region, and is joined to the first plate by laser welding in the second region. The thickness of the second region of the second plate is thinner than the thickness of the first region of the second plate. Furthermore, the molten portion melted by laser welding extends from the fourth surface of the second plate, beyond the joint surface between the first and second plates, to the first plate.

[0011] According to this disclosure, it is possible to maintain cooling performance while suppressing deformation caused by laser welding.

[0012] Figure 1 is a schematic perspective view showing the basic structure of a cold plate according to an embodiment of the present disclosure. Figure 2 is a schematic plan view of a cold plate according to an exemplary embodiment. Figure 3 is a cross-sectional view taken along line II-II of Figure 2. Figure 4 is a schematic plan view of a cold plate according to another exemplary embodiment (part 1). Figure 5 is a cross-sectional view taken along line III-III of Figure 4. Figure 6 is a schematic plan view showing the width of the molten area relative to the top of one fin. Figure 7 is a schematic plan view of a cold plate according to another exemplary embodiment (part 2). Figure 8 is a cross-sectional view taken along line IV-IV of Figure 7. Figure 9 is a cross-sectional view of a cold plate according to another exemplary embodiment (part 3). Figure 10 is a schematic plan view (part 1) showing an example of a molten area formation pattern. Figure 11 is a schematic plan view (part 2) showing an example of a molten area formation pattern. Figure 12 is a cross-sectional view of a cold plate according to another exemplary embodiment (part 5). Figure 13 is a schematic plan view (part 3) showing an example of a molten area formation pattern. Figure 14 is a schematic plan view of a cold plate according to another exemplary embodiment (6). Figure 15 is a cross-sectional view taken along line V-V in Figure 14, illustrating how the second plate deforms. Figure 16 is a schematic plan view showing a modified example of the groove. Figure 17 is a cross-sectional view of a cold plate according to another exemplary embodiment (7).

[0013] The embodiments of this disclosure (hereinafter referred to as "these embodiments") will be described in detail below with reference to the drawings. In the following embodiments, the same parts will be denoted by the same reference numerals to avoid redundant explanations.

[0014] <<1. Overview>> First, an overview of the cold plate according to this embodiment will be explained using Figure 1. Figure 1 is a schematic perspective view showing the basic structure of the cold plate 100 according to this embodiment.

[0015] In addition to Figure 1, the following diagrams will include a Cartesian coordinate system with three axes (X, Y, and Z) as appropriate to facilitate explanation. In this Cartesian coordinate system, the view from the negative Z-axis side is considered a plan view.

[0016] Furthermore, in the drawings shown below, when the same reference numeral is used for multiple identical parts, the same reference numeral will be used for at least two identical parts in order to improve the readability of the drawings.

[0017] The cold plate 100 according to this embodiment has a water-cooled jacket structure in which a coolant flow path with fins for heat exchange is formed in the internal space. As shown in Figure 1, the cold plate 100 has a first plate 110 and a second plate 120.

[0018] The first plate 110 and the second plate 120 are, for example, metal plates. The first plate 110 and the second plate 120 may be formed from a metal with relatively high thermal conductivity, such as copper or aluminum.

[0019] The first plate 110 has a first surface 110a and a second surface 110b located opposite the first surface 110a. The first surface 110a is a heat-receiving surface that comes into contact with the heat source 300 (see arrow a1 in the figure). The second surface 110b has a plurality of fins 111 formed on it.

[0020] Figure 1 shows an example where the fin 111 is a skived fin formed by skiving. Note that the fin 111 is not limited to a skived fin, but may also be a pin fin or the like. A pin fin is a columnar fin. In addition, multiple fins 111 may be so-called stacked fins. A stacked fin is a fin obtained by stacking fins punched out from a metal sheet.

[0021] In this embodiment, a configuration example in which the fin 111 is a skived fin will be mainly described. A configuration example using pin fins will be described later with reference to Figures 12 and 13.

[0022] Furthermore, the first plate 110 has an inlet 112a and an outlet 112b. The inlet 112a is the inlet for the refrigerant. The outlet 112b is the outlet for the refrigerant. The refrigerant that flows in from the inlet 112a flows through the internal space of the cold plate 100 via the passage between the multiple fins 111 and is discharged from the outlet 112b. The refrigerant is, for example, a coolant. As the coolant, for example, an antifreeze such as an aqueous solution of ethylene glycol or propylene glycol, or water may be used.

[0023] Note that the positions of the inlet 112a and outlet 112b shown in Figure 1 are merely examples, and they may be in any position. For the sake of explanation, the inlet 112a and outlet 112b are omitted from the drawings shown below.

[0024] Furthermore, the second plate 120 has a third surface 120a facing the second surface 110b of the first plate 110, and a fourth surface 120b located opposite the third surface 120a. Although Figure 1 shows an example where the first plate 110, the second plate 120, and the heat source 300 are rectangular in plan view, they are not limited to being rectangular.

[0025] The cold plate 100 is formed integrally by overlapping and joining such a first plate 110 and a second plate 120. The configuration including the cold plate 100 and the heat source 300 corresponds to an example of a "cooling structure". In this embodiment, the first plate 110 and the second plate 120 are basically joined by laser welding.

[0026] The following describes exemplary embodiments of such joining that maintain cooling performance while suppressing deformation due to laser welding or hydraulic pressure of the refrigerant.

[0027] <<2. Exemplary Embodiments>> Figure 2 is a schematic plan view of a cold plate 100 according to an exemplary embodiment. Figure 3 is a cross-sectional view taken along line II-II in Figure 2.

[0028] In an exemplary embodiment, the first plate 110 and the second plate 120 are joined together as a single cold plate 100 by laser welding, which involves irradiating the fourth surface 120b, which is located opposite the first surface 110a (the heat receiving surface), with laser light.

[0029] As shown in Figures 2 and 3, the second plate 120 has a first region R1 facing the plurality of fins 111 and a second region R2 located outside the first region R1. The second plate 120 is joined to the first plate 110 in the second region R2 by laser welding.

[0030] As shown in Figure 2, the second region R2 surrounds the first region R1 in a plan view, and the laser beam is irradiated along the second region R2 in a trajectory that surrounds the first region R1. For example, if the first region R1 is rectangular in a plan view, the laser beam may be irradiated in a rectangular trajectory that surrounds the first region R1. As a result, a molten portion 121 surrounding the first region R1 along the second region R2 is formed on the fourth surface 120b of the second plate 120. The molten portion 121 is the part that was melted by laser welding during the joining of the first plate 110 and the second plate 120.

[0031] Here, as shown in Figure 3, the thickness T1 in the second region R2 of the second plate 120 is formed to be thinner than the thickness T2 in the first region R1 of the second plate 120. The first plate 110 and the second plate 120 are joined by laser welding in this thinner second region R2. That is, the molten portion 121 is formed extending from the fourth surface 120b of the second plate 120, across the joining surface S1 between the first plate 110 and the second plate 120, to the first plate 110.

[0032] Thus, because the cold plate 100 is formed with a thin thickness in the second region R2, which is the area to be welded, the output of the laser light required for welding is suppressed, and the amount of penetration associated with laser welding is reduced, thereby reducing the amount of deformation. However, by making the thickness thin, the rigidity near the boundary between the first region R1 and the second region R2 is reduced, and deformation such as the first region R1 of the second plate 120 bulging in the negative direction of the Z axis may occur due to the hydraulic pressure during refrigerant circulation. However, even if deformation occurs, it is on the second plate 120 side opposite to the first surface 110a that contacts the heat source 300, so the impact on the surface accuracy of the first surface 110a is small, and the contact state between the heat source 300 and the first surface 110a can be maintained, making it easy to maintain thermal conductivity. In other words, the cold plate 100 can maintain cooling performance while suppressing deformation caused by laser welding.

[0033] Furthermore, since welding of the second plate 120 and the first plate 110 is possible on the fourth surface 120b, which is opposite to the first surface 110a, which is the heat receiving surface, the welding work is simplified and manufacturing costs can be reduced. In addition, since the effect of thermal deformation that occurs due to welding of the second plate 120 and the first plate 110 is concentrated near the second plate 120, the thermal deformation of the first plate 110 can be reduced.

[0034] Furthermore, as shown in Figure 3, the molten portion 121 has a cross-sectional shape that tapers from the second plate 120 toward the first plate 110. This allows it to be confirmed that the cold plate 100 is heated by laser light irradiated from the second plate 120 side during the laser welding joint between the first plate 110 and the second plate 120.

[0035] Furthermore, as shown in Figure 2, the molten portion 121 surrounds the first region R1 along the second region R2. This allows the cold plate 100 to surround and seal the internal space where the refrigerant flow path is formed, and also increases the bonding strength.

[0036] <<3. Other Exemplary Embodiments (Part 1)>> Next, another exemplary embodiment (Part 1) will be described. Figure 4 is a schematic plan view of a cold plate 100A according to another exemplary embodiment (Part 1). Figure 5 is a cross-sectional view taken along line III-III of Figure 4. Figure 6 is a schematic plan view showing the width of the molten portion 125 relative to the top of one fin 111.

[0037] In the exemplary embodiment described above, the second plate 120 and the first plate 110 are joined in the thin second region R2. However, in order to suppress the deformation due to hydraulic pressure mentioned above, the second plate 120 and the fin 111 may be further joined by laser welding.

[0038] As shown in Figures 4 and 5, in another exemplary embodiment (part 1), the cold plate 100A is joined in the first region R1 by laser welding the second plate 120 to at least one of the tops of the plurality of fins 111.

[0039] Specifically, as shown in Figure 5, the second plate 120 of the cold plate 100A is formed such that when it is superimposed on the first plate 110, the third surface 120a comes into contact with the top of the fin 111.

[0040] Furthermore, the first region R1 of the cold plate 100A has a recess 123 that extends (is recessed) from the fourth surface 120b to the third surface 120a of the second plate 120. The thickness T1 of the first region R1 at the location where the recess 123 is formed is the same as the thickness T1 of the second region R2.

[0041] The second plate 120 is joined to at least one of the tops of the multiple fins 111 in the recess 123 by laser welding. As a result, as shown in Figure 5, a molten portion 125 is formed in the recess 123, extending from the first region R1 of the second plate 120 toward the top of the fin 111. The molten portion 125 is the part that was melted by laser welding during the joining of the second plate 120 and the fin 111.

[0042] The melting portion 125 may be locally formed at at least any position in the first region R1, or may be formed as a continuous locus in the first region R1. For example, FIG. 4 shows an example in which the melting portion 125 is linearly formed along the extending direction D1 of the fin 111 at the central portion of the first region R1.

[0043] Also, as shown in FIGS. 5 and 6, the melting portion 125 may be formed across two or more fins 111. Specifically, as shown in FIG. 6, the width W1 of the melting portion with respect to the top 111a of one fin 111 may be wider than the width W2 at which one top 111a abuts against the second plate 120. In this case, the melting portion 125 is formed across, for example, two or more tops 111a.

[0044] In addition, when one fin 111 is thinned to increase the surface area, if the second plate 120 is joined to only the top 111a of the fin 111 by laser welding, a deep penetration form will result. In this case, since the generated gas is likely to be trapped, voids called blow holes are likely to occur, and there is a concern that the welding strength will decrease and the probability of water leakage will increase. Therefore, as shown in FIG. 6, by setting the width W1 > width W2, the gas can easily escape, and the generation rate of voids can be reduced. Also, by making the melting portion 125 wide and melting the space between adjacent tops 111a, the aforementioned gas can escape not only to the fourth surface 120b side which is the laser light irradiation surface side but also to the third surface 120a side, and the generation rate of voids can be reduced.

[0045] Also, since the melting portion 125 is formed across two or more fins 111, the plurality of fins 111 are melt-fixed, so the joining strength can be increased.

[0046] In this way, by joining at least one of the tops 111a of the plurality of fins 111 formed integrally with the first plate 110 to the second plate 120, the joining strength between the first plate 110 and the second plate 120 can be increased compared to the case where they are not joined. Also, the rigidity against the hydraulic pressure applied during the refrigerant circulation in the cold plate 100A can be increased to suppress deformation due to the hydraulic pressure. Further, this can suppress deterioration of the contact state between the heat source 300 and the heat receiving surface and maintain the cooling performance.

[0047] Also, by joining the top 111a and the second plate 120 in the thin recess 123, the output of the laser required for welding can be suppressed, the penetration amount can be suppressed, and heat deformation can be reduced.

[0048] Also, as described above, since the thickness T1 of the first region R1 at the position where the recess 123 is formed is the same as the thickness T1 in the second region R2, the melting portions 121 and 125 can be formed under the same welding conditions, and the laser welding process can be simplified.

[0049] <<4. Other Exemplary Embodiments (Part 2)>> Next, other exemplary embodiments (part 2) will be described. FIG. 7 is a schematic plan view of a cold plate 100B according to other exemplary embodiments (part 2). Further, FIG. 8 is a cross-sectional view taken along line IV-IV of FIG. 7.

[0050] In the above-described other exemplary embodiment (part 1), for example, an example of the formation pattern of the melting portion 125 in which the melting portion 125 is linearly formed along the extending direction D1 of the fin 111 at the center of the first region R1 was given (see FIG. 4). However, the example of the formation pattern of the melting portion 125 in the first region R1 is not limited to such an example.

[0051] The melting portion 125 that joins the second plate 120 and the top 111a of the fin 111 may be formed in a straight line intersecting the extending direction D1 of the fin 111 in a plan view. Also, a plurality of such straight melting portions 125 intersecting the extending direction D1 may be formed.

[0052] As shown in Figure 7, in another exemplary embodiment (part 2), the cold plate 100B has, for example, a molten portion 125 formed in two straight lines perpendicular to the extending direction D1 of the fin 111 in a plan view.

[0053] In this case, as shown in Figure 8, the cold plate 100B has two recesses 123 in the first region R1 of the second plate 120 as viewed from the Y-axis direction. The thickness T1 of the first region R1 at the location where the two recesses 123 are formed is the same as the thickness T1 of the second region R2, as in another exemplary embodiment (part 1).

[0054] The second plate 120 is joined to the tops 111a of the multiple fins 111 facing the two recesses 123 by laser welding. As a result, as shown in Figure 8, two molten portions 125 are formed extending from the first region R1 of the second plate 120 toward the tops 111a of the multiple fins 111. Although Figures 7 and 8 show an example in which two linear molten portions 125 are formed, there may be one or three or more such molten portions 125.

[0055] In this way, the molten portion 125 that joins the second plate 120 and the top portion 111a of the fin 111 is formed in a straight line that intersects the extending direction D1 of the fin 111 in a plan view, thereby enabling multiple fins 111 to be melted and fixed in a straight line, and increasing the joining strength.

[0056] Furthermore, by forming multiple molten portions 125 in a linear shape perpendicular to the extending direction D1, it is possible to effectively suppress the expansion of the second plate 120 towards the negative Z-axis due to the liquid pressure during refrigerant circulation.

[0057] <<5. Other Exemplary Embodiments (Part 3)>> Next, another exemplary embodiment (Part 3) will be described. Figure 9 is a cross-sectional view of the cold plate 100C according to another exemplary embodiment (Part 3). Note that, similar to Figure 5, Figure 9 is a cross-sectional view of the cold plate 100C cut in the YZ plane.

[0058] In the other exemplary embodiments described above (1) and (2), examples were given in which the molten portions 121 and 125 are formed in the thin second region R2 and recess 123, respectively, to join the first plate 110 and the second plate 120 (see Figures 5 and 8). However, the second region R2 does not necessarily have to be thin if the second plate 120 is joined not only to the first plate 110 and the second region R2, but also to at least one of the tops 111a of the multiple fins 111 in the first region R1.

[0059] As shown in Figure 9, in another exemplary embodiment (the third), the cold plate 100C is joined to the first plate 110 by laser welding, in which the second plate 120 is irradiated with laser light from, for example, the fourth surface 120b side in the second region R2 (see molten portion 121 in the figure).

[0060] Furthermore, in the cold plate 100C, the second plate 120 is joined to at least one of the tops 111a of the multiple fins 111 by laser welding in the first region R1 (see molten portion 125 in the figure).

[0061] This increases the bonding strength between the first plate 110 and the second plate 120 compared to the case where the fins 111, which are integrally formed with the first plate 110, and the second plate 120 are not joined. It also increases the rigidity of the cold plate 100C against the hydraulic pressure applied during refrigerant circulation, thereby suppressing deformation due to hydraulic pressure. Furthermore, this prevents deterioration of the contact condition between the heat source 300 and the heat receiving surface, thus maintaining cooling performance.

[0062] Figure 9 shows an example in which the first plate 110 and the second plate 120 are joined by laser welding in the second region R2, forming a molten portion 121. However, the joining in the second region R2 here does not necessarily have to be done by laser welding.

[0063] <<6. Other Exemplary Embodiments (Part 4)>> Next, other exemplary embodiments (Part 4) will be described. Figure 10 is a schematic plan view (Part 1) showing an example of the formation pattern of the molten portion 125. Figure 11 is a schematic plan view (Part 2) showing an example of the formation pattern of the molten portion 125.

[0064] In the explanation using Figures 4 or 7 above, examples of formation patterns in which the molten portion 125 is formed linearly along or perpendicular to the extension direction D1 of the fin 111 were given, but the examples of formation patterns for the molten portion 125 are not limited to these.

[0065] For example, as shown in Figure 10, the molten portion 125 may be formed so as to intersect the extending direction D1 of the fin 111 at an oblique angle in a plan view. In this case, as shown in Figure 10, the molten portion 125 may be formed in an X shape that intersects, for example, along the diagonal of the first region R1.

[0066] Furthermore, as shown in Figure 11, for example, the molten portion 125 may be formed in a grid pattern. In either of the formation pattern examples shown in Figure 10 and Figure 11, it is possible to effectively suppress the expansion of the second plate 120 toward the negative Z-axis due to the liquid pressure during refrigerant circulation.

[0067] Furthermore, if the molten portions 125 intersect, the thermal effects from welding will accumulate at the intersection point. Therefore, as shown in Figures 10 and 11, it is desirable that the multiple molten portions 125 do not intersect.

[0068] <<7. Other Exemplary Embodiments (Part 5)>> Next, another exemplary embodiment (Part 5) will be described. Figure 12 is a cross-sectional view of a cold plate 100D according to another exemplary embodiment (Part 5). Figure 13 is a schematic plan view (Part 3) showing an example of a formation pattern of the molten portion 125.

[0069] Note that Figure 12 is a cross-sectional view corresponding to Figure 9, so the explanation using Figure 12 will mainly focus on the differences from Figure 9. As shown in Figure 12, the cold plate 100D according to another exemplary embodiment (No. 5) differs from the cold plate 100C according to another exemplary embodiment (No. 3) shown in Figure 9 in that the multiple fins 111A are pin fins instead of skived fins.

[0070] The cold plate 100D is formed when the second plate 120 is joined to at least one of the tops 111a of the multiple fins 111A by laser welding in the first region R1 (see molten portion 125 in the figure).

[0071] This increases the bonding strength between the first plate 110 and the second plate 120 compared to the case where the fins 111A, which are integrated with the first plate 110, and the second plate 120 are not joined. It also increases the rigidity of the cold plate 100D against the hydraulic pressure applied during refrigerant circulation, thereby suppressing deformation due to hydraulic pressure. Furthermore, this prevents deterioration of the contact condition between the heat source 300 and the heat receiving surface, thus maintaining cooling performance.

[0072] Furthermore, since pin fins typically have a diameter of 1 mm or more, the cold plate 100D allows the area in which the molten portion 125 is formed for a single fin 111A to be contained within the area occupied by the top portion 111a of the fin 111A.

[0073] Therefore, an example of the formation pattern of the molten portion 125 in the cold plate 100D is shown in Figure 13, for example. That is, the cold plate 100D has a formation pattern of molten portions 125 in which the second plate 120 is locally joined to the top portions 111a of one or more fins 111A by laser welding.

[0074] Figure 13 shows an example of a formation pattern in which the second plate 120 is joined to every other fin 111A in an arrangement of multiple fins 111A, but this is merely one example.

[0075] <<8. Other Exemplary Embodiments (Part 6)>> Next, other exemplary embodiments (Part 6) will be described. Figure 14 is a schematic plan view of the cold plate 100E according to another exemplary embodiment (Part 6). Figure 15 is a cross-sectional view taken along line V-V in Figure 14, illustrating how the second plate 120 deforms. Figure 16 is a schematic plan view showing a modified example of the groove 127.

[0076] As shown in Figures 14 and 15, the cold plate 100E according to another exemplary embodiment (the sixth) has an annular groove 127 in the first region R1 that extends from the fourth surface 120b toward the third surface 120a and along the in-plane direction of the fourth surface 120b.

[0077] The groove 127 is a thin portion in the first region R1. This groove 127 functions as a fold, so to speak, that makes the second plate 120 easier to deform.

[0078] Specifically, as shown in Figure 15, the cold plate 100E is joined to the fin 111 by laser welding while the second plate 120 is deformed and the third surface 120a is pressed against the top portion 111a of the fin 111 (see arrow a2 in the figure).

[0079] At this time, the presence of the groove 127 allows the cold plate 100E to increase the displacement of the second plate 120, making it easier to press the third surface 120a against the top 111a of the fin 111. As a result, during the welding operation of the fin 111 and the second plate 120, it becomes easier to deform the second plate 120 by pressing it down so that it comes into contact with the top 111a of the fin 111, thereby facilitating the welding of the second plate 120 and the fin 111.

[0080] Although Figure 14 shows an example where the groove 127 is annular in plan view, the groove 127 is not limited to annular shapes. As shown in Figure 16, for example, linearly extending grooves 127A may be provided on the top, bottom, left, and right sides. In other words, the cold plate 100E has grooves 127 and grooves 127A in the first region R1 that extend from the fourth surface 120b toward the third surface 120a and along the in-plane direction of the fourth surface 120b.

[0081] <<9. Other Exemplary Embodiments (7)>> Next, we will describe other exemplary embodiments (7). Figure 17 is a cross-sectional view of a cold plate 100F according to another exemplary embodiment (7). Note that since Figure 17 is a cross-sectional view corresponding to Figure 5, the explanation using Figure 17 will mainly focus on the differences from Figure 5.

[0082] As shown in Figure 17, the cold plate 100F according to another exemplary embodiment (the 7th embodiment) differs from the cold plate 100A shown in Figure 5 in that the second region R2 has a flange region R21, and the first plate 110 has a flange portion 113 facing the flange region R21. The flange portion 113 is a so-called flange-like portion that protrudes from the first plate 110 in the XY plane. The term "flange-like" can also be rephrased as "rim-like."

[0083] Specifically, the first plate 110 has a first portion that is spaced apart from the second plate 120, and a plurality of second portions that extend from the first portion toward the second plate 120. For example, as shown in Figure 17, when the cold plate 100F is positioned with the first surface 110a of the first plate 110 facing upward, the first portion corresponds to the top of the first plate 110, and the second portion corresponds to the side of the first plate 110. The flange portion 113 is located at the tip of the second portion, that is, at the connection end with the second plate 120, and protrudes outward from the second portion in a plan view.

[0084] In the cold plate 100F, the second plate 120 is joined to the flange portion 113 by laser welding in the flange region R21. This makes it easier to contain the effects of thermal deformation caused by laser welding within the flange region R21, thereby reducing the impact on the surface accuracy of the first surface 110a.

[0085] <<10. Conclusion>> As described above, according to one embodiment of the present disclosure, the cold plate 100 comprises a first plate 110 and a second plate 120. The first plate 110 is made of metal and has a first surface 110a, a second surface 110b located opposite the first surface 110a, and a plurality of fins 111 formed on the second surface 110b. The second plate 120 is made of metal and has a third surface 120a facing the second surface 110b, and a fourth surface 120b located opposite the third surface 120a. The second plate 120 also has a first region R1 facing the plurality of fins 111 and a second region R2 located outside the first region R1, and is joined to the first plate 110 by laser welding in the second region R2. The thickness T1 in the second region R2 of the second plate 120 is thinner than the thickness T2 in the first region R1 of the second plate 120. Furthermore, the molten portion 121, which is melted by laser welding, extends from the fourth surface 120b of the second plate 120, beyond the joint surface S1 between the first plate 110 and the second plate 120, to the first plate 110. With such a cold plate 100, it is possible to maintain cooling performance while suppressing deformation caused by laser welding.

[0086] Furthermore, according to one embodiment of the present disclosure, the cold plate 100C comprises a first plate 110 and a second plate 120. The first plate 110 is made of metal and has a first surface 110a, a second surface 110b located opposite the first surface 110a, and a plurality of fins 111 formed on the second surface 110b. The second plate 120 is made of metal and has a third surface 120a facing the second surface 110b, and a fourth surface 120b located opposite the third surface 120a. The second plate 120 also has a first region R1 facing the plurality of fins 111 and a second region R2 located outside the first region R1, and is joined to the first plate 110 in the second region R2. In addition, at least one top 111a of the plurality of fins 111 is joined to the second plate 120 by laser welding. With such a cold plate 100C, cooling performance can be maintained while suppressing deformation due to hydraulic pressure.

[0087] Although embodiments of this disclosure have been described above, the technical scope of this disclosure is not limited to the embodiments described above, and various modifications are possible without departing from the gist of this disclosure. Furthermore, components from different embodiments and modifications may be combined as appropriate.

[0088] Furthermore, the effects described in each embodiment of this specification are merely illustrative and not limiting, and other effects may also occur.

[0089] Furthermore, this technology can take the following configurations: (1) A cold plate comprising: a first plate made of metal and having a first surface, a second surface located opposite the first surface, and a plurality of fins formed on the second surface; and a second plate made of metal and having a third surface facing the second surface and a fourth surface located opposite the third surface, wherein the second plate has a first region facing the plurality of fins and a second region located outside the first region, and is joined to the first plate by laser welding in the second region, the thickness of the second plate in the second region is thinner than the thickness of the second plate in the first region, and the molten portion melted by the laser welding extends from the fourth surface of the second plate beyond the joint surface between the first plate and the second plate to the first plate. (2) The cold plate according to (1), wherein the molten portion has a cross-sectional shape that tapers from the second plate toward the first plate. (3) The cold plate according to (1) or (2), wherein the second region surrounds the first region in a plan view, and the molten portion surrounds the first region along the second region. (4) The cold plate according to (1), (2) or (3), wherein the first region has a recess extending from the fourth surface toward the third surface, and the second plate is joined to at least one of the tops of the plurality of fins by laser welding in the recess. (5) The cold plate according to (4), wherein the molten portion joining the second plate and the top is formed across two or more of the fins. (6) The cold plate according to (5), wherein the plurality of fins are skived fins, and the molten portion joining the second plate and the top is formed in a straight line intersecting the extending direction of the skived fins in a plan view. (7) The cold plate according to (6), wherein the molten portion joining the second plate and the top portion is formed in a plurality of straight lines perpendicular to the direction of extension of the skive fin in a plan view.(8) The cold plate according to any one of (4) to (7), wherein the thickness of the first region of the second plate at the position where the recess is formed is the same as the thickness of the second region of the second plate. (9) The cold plate according to any one of (1) to (8), wherein the first surface is a heat receiving surface that contacts a heat source. (10) A cooling structure comprising: a first plate made of metal and having a first surface which is a heat receiving surface in contact with a heat source, a second surface located opposite to the first surface, and a plurality of fins formed on the second surface; and a second plate made of metal and having a third surface facing the second surface and a fourth surface located opposite to the third surface, wherein the second plate has a first region facing the plurality of fins and a second region located outside the first region, and is joined to the first plate by laser welding in the second region, the thickness of the second plate in the second region is thinner than the thickness of the second plate in the first region, and the molten portion melted by the laser welding extends from the fourth surface of the second plate beyond the joint surface between the first plate and the second plate to the first plate.

[0090] 100 Cold plate 100A Cold plate 100B Cold plate 100C Cold plate 100D Cold plate 100E Cold plate 100F Cold plate 110 First plate 110a First surface 110b Second surface 111, 111A Fin 111a Top 113 Flange 120 Second plate 120a Third surface 120b Fourth surface 121 Molten area 123 Recess 125 Molten area 127, 127A Groove 300 Heat source R1 First region R2 Second region R21 Flange region

Claims

1. A cold plate comprising: a first plate made of metal and having a first surface, a second surface located opposite the first surface, and a plurality of fins formed on the second surface; and a second plate made of metal and having a third surface facing the second surface and a fourth surface located opposite the third surface, wherein the second plate has a first region facing the plurality of fins and a second region located outside the first region, and is joined to the first plate by laser welding in the second region, the thickness of the second plate in the second region is thinner than the thickness of the second plate in the first region, and the molten portion melted by the laser welding extends from the fourth surface of the second plate beyond the joint surface between the first plate and the second plate to the first plate.

2. The cold plate according to claim 1, wherein the molten portion has a cross-sectional shape that tapers from the second plate toward the first plate.

3. The cold plate according to claim 1, wherein the second region surrounds the first region in a plan view, and the molten portion surrounds the first region along the second region.

4. The cold plate according to claim 1, wherein the first region has a recess extending from the fourth surface to the third surface, and the second plate is joined in the recess to at least one of the tops of the plurality of fins by laser welding.

5. The cold plate according to claim 4, wherein the molten portion joining the second plate and the top portion is formed spanning two or more fins.

6. The cold plate according to claim 5, wherein the plurality of fins are skive fins, and the molten portion joining the second plate and the top portion is formed in a straight line that intersects the extending direction of the skive fins in a plan view.

7. The cold plate according to claim 6, wherein the molten portion joining the second plate and the top portion is formed in a plurality of straight lines perpendicular to the extending direction of the skive fin in a plan view.

8. The cold plate according to any one of claims 4 to 7, wherein the thickness of the first region of the second plate at the location where the recess is formed is the same as the thickness of the second region of the second plate.

9. The cold plate according to claim 1, wherein the first surface is a heat-receiving surface that contacts a heat source.

10. A cooling structure comprising: a first plate made of metal and having a first surface which is a heat receiving surface in contact with a heat source, a second surface located opposite to the first surface, and a plurality of fins formed on the second surface; and a second plate made of metal and having a third surface facing the second surface and a fourth surface located opposite to the third surface, wherein the second plate has a first region facing the plurality of fins and a second region located outside the first region, and is joined to the first plate by laser welding in the second region, the thickness of the second plate in the second region is thinner than the thickness of the second plate in the first region, and the molten portion melted by the laser welding extends from the fourth surface of the second plate beyond the joint surface between the first plate and the second plate to the first plate.

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