Cold plate and cooling structure
The cold plate design addresses warping issues from laser welding by balancing thermal expansion stresses through strategically positioned molten portions, maintaining cooling performance and heat conduction efficiency.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- NIDEC CORP(JP)
- Filing Date
- 2025-11-25
- Publication Date
- 2026-06-04
AI Technical Summary
Laser welding in cold plates used for water-cooling systems in semiconductor computing devices causes warping due to thermal deformation, leading to reduced heat conduction efficiency and cooling performance.
A cold plate design where the first and second metal plates are joined by laser welding with strategically positioned molten portions extending from opposing surfaces, creating balanced thermal expansion and contraction stresses to counteract warping, thereby maintaining cooling performance.
The design effectively suppresses warping and maintains cooling efficiency by balancing residual stresses, ensuring effective heat conduction and contact with heat sources.
Smart Images
Figure JP2025040905_04062026_PF_FP_ABST
Abstract
Description
Cold Plate and Cooling Structure
[0001] This application claims priority based on Japanese Patent Application No. 2024-208384 filed in Japan on November 29, 2024, and incorporates its content herein by reference.
[0002] This disclosure relates to a cold plate and a cooling structure.
[0003] Conventionally, the air-cooling method using 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 conventional ones. 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 by, for example, 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 Unexamined Patent Application Publication No. 2017-212401
[0007] However, when laser welding is adopted, there is a problem that warping due to thermal deformation is likely to occur.
[0008] Specifically, when laser welding is adopted, since the metal is locally heated and melted by laser light, the vicinity of the melted portion also becomes high temperature and thermal expansion occurs. The portion where thermal expansion has occurred solidifies while being expanded, but shrinks when cooled, thereby causing warping.
[0009] If warping occurs, the contact with the heat source will deteriorate, which may reduce the efficiency of heat conduction and decrease cooling performance.
[0010] This disclosure provides a cold plate and a cooling structure that can maintain cooling performance while suppressing warping caused by laser welding.
[0011] 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 located opposite the first surface, and a plurality of fins arranged on the second surface. The second plate is made of metal and has a third surface facing the second surface and a fourth surface located opposite 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. The first plate and the second plate are joined in the second region by irradiation with laser light. The second plate also has a first molten portion and a second molten portion that are melted by irradiation with laser light. The first molten portion extends in the second region from the first surface of the first plate toward the second plate. The second molten portion extends in the second region from the fourth surface of the second plate toward the first plate.
[0012] According to this disclosure, it is possible to suppress warping caused by laser welding while maintaining cooling performance.
[0013] Figure 1 is a schematic perspective view showing the basic structure of a cold plate according to an embodiment of this disclosure. Figure 2 is a schematic plan view of a cold plate according to an exemplary embodiment, viewed from the negative Z-axis side. Figure 3 is a schematic plan view of a cold plate according to an exemplary embodiment, viewed from the positive Z-axis side. Figure 4 is a cross-sectional view taken along line II-II of Figure 3. Figure 5 is an explanatory diagram of the principle of warping suppression according to an exemplary embodiment. Figure 6 is a cross-sectional view of a cold plate according to another exemplary embodiment (1). Figure 7 is a cross-sectional view of a cold plate according to another exemplary embodiment (2). Figure 8 is a cross-sectional view of a cold plate according to another exemplary embodiment (3). Figure 9 is a cross-sectional view of a cold plate according to another exemplary embodiment (4). Figure 10 is a cross-sectional view of a cold plate according to another exemplary embodiment (5). Figure 11 is a cross-sectional view of a cold plate according to another exemplary embodiment (6). Figure 12 is a cross-sectional view of a cold plate according to another exemplary embodiment (7). Figure 13 is a cross-sectional view of a cold plate according to another exemplary embodiment (8). Figure 14 is a cross-sectional view of a cold plate according to another exemplary embodiment (the ninth).
[0014] 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.
[0015] <<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.
[0016] 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 either the positive or negative Z-axis side is considered a plan view.
[0017] 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.
[0018] 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.
[0019] 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.
[0020] The first plate 110 has a first surface 110a and a second surface 110b located opposite the first surface 110a. The second surface 110b has a plurality of fins 111 arranged on it.
[0021] 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. In this embodiment, we will mainly describe an example in which the fin 111 is a skived fin.
[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.
[0025] The cold plate 100 is integrally formed by overlapping and joining the first plate 110 and the second plate 120. In the cold plate 100, as shown in Figure 1, for example, the first surface 110a of the first plate 110 becomes the heat receiving surface that contacts the heat source 300 (see arrow a1 in the figure). Note that the example in Figure 1 is not limited to this, for example, the fourth surface 120b of the second plate 120 may become the heat receiving surface that contacts the heat source 300.
[0026] Furthermore, Figure 1 shows an example where the first plate 110, the second plate 120, and the heat source 300 are rectangular in plan view, but they do not necessarily have to be rectangular.
[0027] 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 joined by laser welding.
[0028] The following describes exemplary embodiments of such joining, which aim to suppress warping caused by laser welding while maintaining cooling performance. While the following primarily describes a configuration in which multiple fins 111 are arranged on the first plate 110, similar to that shown in Figure 1, the positions of the multiple fins 111 are not limited. For example, the multiple fins 111 may be arranged on the second plate 120 instead of the first plate 110.
[0029] <<2. Exemplary Embodiments>> Figure 2 is a schematic plan view of the cold plate 100 according to an exemplary embodiment, viewed from the negative Z-axis side. Figure 3 is a schematic plan view of the cold plate 100 according to an exemplary embodiment, viewed from the positive Z-axis side. Figure 4 is a cross-sectional view taken along line II-II in Figure 3.
[0030] In an exemplary embodiment, the first plate 110 and the second plate 120, when integrally formed as a cold plate 100 by laser welding, have a first molten portion 113 and a second molten portion 123 that were melted by irradiation with laser light.
[0031] Specifically, as shown in Figures 2 and 4, the first molten portion 113 is formed to extend from the first surface 110a of the first plate 110 toward the second plate 120. Also, as shown in Figures 3 and 4, the second molten portion 123 is formed to extend from the fourth surface 120b of the second plate 120 toward the first plate 110.
[0032] The first plate 110 and the second plate 120 are joined together by, for example, the second molten portion 123 of the first molten portion 113 and the second molten portion 123.
[0033] Specifically, as shown in Figure 4, 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. When the second plate 120 is joined to the first plate 110, laser light is irradiated onto the fourth surface 120b in the second region R2. The second molten portion 123, which is melted by the irradiation of the laser light, extends from the fourth surface 120b beyond the joining surface S1 between the first plate 110 and the second plate 120 to the first plate 110, thereby joining the second plate 120 and the first plate 110.
[0034] As shown in Figure 3, the second region R2 surrounds the first region R1 in a plan view, and the laser light 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 light may be irradiated in a rectangular trajectory that surrounds the first region R1. As a result, a second molten portion 123 surrounding the first region R1 along the second region R2 is formed on the fourth surface 120b of the second plate 120. In this way, the second molten portion 123 surrounds the first region R1 along the second region R2. As a result, the cold plate 100 can surround and seal the internal space in which the refrigerant flow path is formed, and the bonding strength can be increased.
[0035] On the other hand, when joining the first plate 110 to the second plate 120, as shown in Figure 4, laser light is irradiated onto the first surface 110a in the second region R2 in accordance with the formation of the second molten portion 123. The first molten portion 113, which is melted by the irradiation of the laser light, is formed to extend from the first surface 110a toward the second plate 120.
[0036] At this time, the first molten portion 113 is formed in a position opposite to the second molten portion 123, as shown in Figures 2 to 4. Note that the opposing positions do not have to be geometrically exact; in other words, a slight misalignment is acceptable.
[0037] Furthermore, as shown in Figure 4, the first molten portion 113 does not have to extend beyond the joint surface S1 between the first plate 110 and the second plate 120 to the second plate 120. In other words, the first molten portion 113 does not have to join the first plate 110 and the second plate 120. The first molten portion 113 appears to be a dummy weld bead, appearing as if welded but not actually welded. In the exemplary embodiment, warping of the cold plate 100 due to laser welding is suppressed by providing the first molten portion 113 of the first plate 110 to the second molten portion 123 of the second plate 120.
[0038] The principle will be explained using Figure 5. Figure 5 is an explanatory diagram of the principle of warping suppression according to an exemplary embodiment. When the second plate 120 is joined to the first plate 110 from the fourth surface 120b side by laser welding, the vicinity of the molten second molten portion 123 also becomes hot and thermal expansion occurs. The part where this thermal expansion occurs is tentatively shown as the thermally expanded portion 125.
[0039] The thermally expanded portion 125 solidifies in its expanded state, but contracts upon cooling, which generates tensions TN21 and TN22 in the second plate 120 toward the second molten portion 123. These tensions TN21 and TN22 act as residual stresses that cause the second plate 120 to indent (bend), for example, in the negative direction of the Z-axis.
[0040] Therefore, in this exemplary embodiment, a first molten portion 113 is formed on the first plate 110 by irradiating it with laser light from the first surface 110a side of the first plate 110. As a result, a thermal expansion portion 115 is created near the first molten portion 113, and when cooled, it contracts and generates tensions TN11 and TN12 directed toward the first molten portion 113. On the other hand, these act as residual stresses that cause the first plate 110 to bend, for example, in the positive direction of the Z axis. In other words, the residual stress of the first plate 110 acts as a force that cancels out the force that causes the second plate 120 to bend due to the residual stress of the second plate 120 (see arrow a2 in the figure) (see arrow a3 in the figure).
[0041] In other words, according to the exemplary embodiment, the difference in residual stress between the second plate 120 and the first plate 110 can be reduced, thereby suppressing warping of the cold plate 100 due to laser welding. Furthermore, this prevents deterioration of the contact condition with the heat source 300 and a reduction in the cooling performance of the cold plate 100.
[0042] Further, as shown in FIGS. 2 to 4, by forming the first melting portion 113 and the second melting portion 123 at positions facing each other, it is possible to easily make the tensions TN21 and TN22 of the second plate 120 equal to the tensions TN11 and TN12 of the first plate 110. That is, it is possible to easily reduce the difference in residual stress between the second plate 120 and the first plate 110 respectively.
[0043] Note that the irradiation conditions of the laser beam on the first plate 110 do not necessarily have to match the irradiation conditions of the laser beam on the second plate 120. These irradiation conditions can be appropriately adjusted according to the shapes of the second plate 120 and the first plate 110 respectively so that at least the residual stresses of the second plate 120 and the first plate 110 become uniform.
[0044] Also, among the irradiation conditions, the irradiation timing of the laser beam on the first plate 110 may be any of the timings before, after, or simultaneous with the irradiation timing on the second plate 120.
[0045] Hereinafter, other exemplary embodiments (No. 1) to (No. 9) will be sequentially described. In those descriptions, similar to the above-described exemplary embodiments, basically, a configuration example in which the second melting portion 123 joins the second plate 120 and the first plate 110 will be mainly described, but the first melting portion 113 may join the second plate 120 and the first plate 110.
[0046] <<3. Other Exemplary Embodiments (No. 1)>> An other exemplary embodiment (No. 1) will be described. FIG. 6 is a cross-sectional view of the cold plate 100A according to the other exemplary embodiment (No. 1). Note that, including FIG. 6, each cross-sectional view shown in FIGS. 6 to 14 used in the following description corresponds to the cross-sectional view taken along line II-II shown in FIG. 4.
[0047] Correspondingly, in the description using FIGS. 6 to 14, mainly the points different from the respective embodiments already described will be described. In the description of the other exemplary embodiment (No. 1) using FIG. 6, mainly the points different from FIG. 4 will be described.
[0048] As shown in FIG. 6, the cold plate 100A is different from the cold plate 100 shown in FIG. 4 in that the thickness T1 of the portion of the first plate 110 facing the first region R1 is smaller than the thickness T2 in the first region R1 of the second plate 120 (T1 < T2).
[0049] Further, the cold plate 100A is different from the cold plate 100 shown in FIG. 4 in that the melting amount of the first melting portion 113 of the first plate 110 is larger than the melting amount of the second melting portion 123 of the second plate 120.
[0050] According to such a configuration example, by applying a relatively large thermal strain to the thinner first plate 110 side and increasing the tensile forces TN11 and TN12 of the first plate 110, the difference in residual stress of the first plate 110 with respect to the second plate 120 can be reduced. That is, according to the cold plate 100A, even when the thickness T1 of the portion of the first plate 110 facing the first region R1 is smaller than the thickness T2 in the first region R1 of the second plate 120, it is possible to maintain the cooling performance while suppressing warping due to laser welding.
[0051] <<4. Other exemplary embodiments (Part 2)>> Next, other exemplary embodiments (Part 2) will be described. FIG. 7 is a cross-sectional view of a cold plate 100B according to other exemplary embodiments (Part 2). In the description using FIG. 7, mainly the differences from FIG. 6 will be described.
[0052] As shown in FIG. 7, the cold plate 100B is different from the cold plate 100A shown in FIG. 6 in that the thickness T2 in the first region R1 of the second plate 120 is smaller than the thickness T1 of the portion of the first plate 110 facing the first region R1 (T1 > T2).
[0053] With this configuration, a relatively large thermal strain is applied to the thinner second plate 120, and the tensions TN21 and TN22 of the second plate 120 are increased, thereby reducing the difference in residual stress between the second plate 120 and the first plate 110. In other words, with the cold plate 100B, even when the thickness T2 of the first region R1 of the second plate 120 is thinner than the thickness T1 of the part of the first plate 110 facing the first region R1, cooling performance can be maintained while suppressing warping caused by laser welding.
[0054] <<5. Other Exemplary Embodiments (Part 3)>> Next, another exemplary embodiment (Part 3) will be described. Figure 8 is a cross-sectional view of a cold plate 100C according to another exemplary embodiment (Part 3). In the explanation using Figure 8, the differences from Figure 6 will be mainly explained.
[0055] As shown in Figure 8, the cold plate 100C is similar to the cold plate 100A shown in Figure 6 in that the thickness T1 of the portion of the first plate 110 facing the first region R1 is thinner than the thickness T2 of the second plate 120 in the first region R1 (T1 < T2). However, the cold plate 100C differs from the cold plate 100A shown in Figure 6 in that the second molten portion 123 of the second plate 120 and the first molten portion 113 of the first plate 110 are formed in positions that are not facing each other.
[0056] The first molten portion 113 of the cold plate 100C is located closer to the first region R1 than the second molten portion 123. Furthermore, the amount of melting in the first molten portion 113 of the cold plate 100C is equal to the amount of melting in the second molten portion 123. However, these melting amounts do not need to be exactly equal.
[0057] In this configuration example, since the second molten portion 123 and the first molten portion 113 are formed in positions that are not opposite to each other, it becomes possible to adjust the magnitude of thermal strain according to the shapes of the second plate 120 and the first plate 110, respectively.
[0058] Furthermore, by positioning the first molten portion 113 of the thin first plate 110 closer to the first region R1 than the second molten portion 123 of the second plate 120, the tensions TN11 and TN12 generated on the first plate 110 side can be increased even with the same amount of thermal strain due to the same amount of melting. In addition, this can reduce the difference in residual stress between the first plate 110 and the second plate 120.
[0059] In other words, with the cold plate 100C, even when the thickness T1 of the portion of the first plate 110 facing the first region R1 is thinner than the thickness T2 of the second plate 120 in the first region R1, it is possible to maintain cooling performance while suppressing warping caused by laser welding.
[0060] <<6. Other Exemplary Embodiments (Part 4)>> Next, another exemplary embodiment (Part 4) will be described. Figure 9 is a cross-sectional view of a cold plate 100D according to another exemplary embodiment (Part 4). In the explanation using Figure 9, the differences from Figure 7 will be mainly explained.
[0061] As shown in Figure 9, the cold plate 100D is similar to the cold plate 100B shown in Figure 7 in that the thickness T2 of the first region R1 of the second plate 120 is thinner than the thickness T1 of the portion of the first plate 110 facing the first region R1 (T1 > T2). However, the cold plate 100D differs from the cold plate 100B shown in Figure 7 in that the second molten portion 123 of the second plate 120 and the first molten portion 113 of the first plate 110 are formed in positions that are not facing each other.
[0062] The second molten portion 123 of the cold plate 100D is located closer to the first region R1 than the first molten portion 113. Furthermore, the amount of melting in the second molten portion 123 of the cold plate 100D is equal to the amount of melting in the first molten portion 113. However, these melting amounts do not need to be exactly equal.
[0063] In this configuration example, by positioning the second molten portion 123 of the thin second plate 120 closer to the first region R1 than the first molten portion 113 of the first plate 110, the tensions TN21 and TN22 generated on the second plate 120 side can be increased even with the same amount of thermal strain due to the same amount of melting. Furthermore, this makes it possible to reduce the difference in residual stress between the first plate 110 and the second plate 120.
[0064] In other words, with the cold plate 100D, even when the thickness T2 of the first region R1 of the second plate 120 is thinner than the thickness T1 of the portion of the first plate 110 facing the first region R1, it is possible to maintain cooling performance while suppressing warping caused by laser welding.
[0065] <<7. Other Exemplary Embodiments (Part 5)>> Next, another exemplary embodiment (Part 5) will be described. Figure 10 is a cross-sectional view of a cold plate 100E according to another exemplary embodiment (Part 5). In the explanation using Figure 10, the differences from Figure 9 will be mainly explained.
[0066] As shown in Figure 10, the cold plate 100E differs from the cold plate 100D shown in Figure 9 in that the thickness T1 of the portion of the first plate 110 facing the first region R1 is equal to the thickness T2 of the second plate 120 in the first region R1 (T1 = T2). Furthermore, the cold plate 100E differs from the cold plate 100D in that, due to constraints such as other installed components 500, one of the first molten portion 113 and the second molten portion 123 is located closer to the first region R1 than the other. Figure 10 shows an example where the second molten portion 123 is located closer to the first region R1 than the first molten portion 113. In addition, in the cold plate 100E, the amount of melting in the first molten portion 113 is greater than the amount of melting in the second molten portion 123 that is located closer to the first region R1. In the example in Figure 10, the amount of melting in the first molten portion 113 is greater than the amount of melting in the second molten portion 123.
[0067] With this configuration, by increasing the amount of thermal strain in the relatively outer of the first molten portion 113 and the second molten portion 123 (the first molten portion 113 in Figure 10), it becomes possible to apply the same tension to the first plate 110 and the second plate 120. In other words, this reduces the difference between the residual stress of the first plate 110 and the residual stress of the second plate 120, making them uniform.
[0068] In other words, with the cold plate 100E, even if, due to constraints such as other components 500 to be installed, the first molten portion 113 must be formed relatively outward from the second molten portion 123, it is possible to maintain cooling performance while suppressing warping caused by laser welding.
[0069] <<8. Other Exemplary Embodiments (Part 6)>> Next, another exemplary embodiment (Part 6) will be described. Figure 11 is a cross-sectional view of a cold plate 100F according to another exemplary embodiment (Part 6). In the explanation using Figure 11, the differences from Figure 10 will be mainly explained.
[0070] As shown in Figure 11, the cold plate 100F is similar to the cold plate 100E shown in Figure 10 in that the second molten portion 123 of the second plate 120 extends from the fourth surface 120b of the second plate 120, across the joining surface S1, to the first plate 110. However, the cold plate 100F differs from the cold plate 100E shown in Figure 10 in that the first molten portion 113 of the first plate 110 extends from the first surface 110a of the first plate 110, across the joining surface S1, to the second plate 120.
[0071] This configuration allows for the suppression of warping caused by laser welding, while simultaneously improving the joint strength and sealing performance between the first plate 110 and the second plate 120.
[0072] <<9. Other Exemplary Embodiments (7)>> Next, another exemplary embodiment (7) will be described. Figure 12 is a cross-sectional view of a cold plate 100G according to another exemplary embodiment (7). In the explanation using Figure 12, the differences from Figure 4 will be mainly explained.
[0073] As shown in Figure 12, the cold plate 100G differs from Figure 4 in that the first plate 110 and the second plate 120 are joined in the second region R2 via an intermediate member 130. The intermediate member 130 is an annular member that forms a side wall in the integrally formed cold plate 100G. The intermediate member 130 may be made of a metal with relatively high thermal conductivity, such as copper or aluminum. The first molten portion 113 of the cold plate 100G is formed to extend from the first surface 110a of the first plate 110, across the second surface 110b, to the intermediate member 130. The second molten portion 123 of the cold plate 100G is formed to extend from the fourth surface 120b of the second plate 120, across the third surface 120a, to the intermediate member 130.
[0074] This configuration suppresses warping caused by laser welding while simultaneously improving the joint strength and sealing performance between the first plate 110 and the second plate 120. Figure 12 shows an example where the first molten portion 113 and the second molten portion 123 of the cold plate 100G are formed in opposing positions, but they may be in non-opposing positions. Also, Figure 12 shows an example where the melting amounts of the first molten portion 113 and the second molten portion 123 are equal, but depending on the shape of the first plate 110 and the second plate 120, the melting amount of one may be greater than that of the other.
[0075] <<10. Other Exemplary Embodiments (Part 8)>> Next, other exemplary embodiments (Part 8) will be described. Figure 13 is a cross-sectional view of a cold plate 100H according to another exemplary embodiment (Part 8). In the explanation using Figure 13, the differences from Figure 10 will be mainly explained.
[0076] As shown in Figure 13, the cold plate 100H differs from the cold plate 100E shown in Figure 10 in that, in the second region R2, the direction in which the first molten portion 113 extends and the direction in which the second molten portion 123 extends are non-parallel.
[0077] Thus, even if the direction in which the first molten portion 113 extends and the direction in which the second molten portion 123 extends are not parallel, it is possible to apply the same tension to the first plate 110 and the second plate 120 by adjusting the amount of thermal strain in the first molten portion 113 or the second molten portion 123. In other words, the difference between the residual stress of the first plate 110 and the residual stress of the second plate 120 can be reduced and made uniform.
[0078] In other words, with the cold plate 100H, even if the direction in which the first molten portion 113 and the second molten portion 123 extend must be non-parallel due to constraints such as other components 500 installed, it is possible to maintain cooling performance while suppressing warping caused by laser welding.
[0079] Figure 13 shows an example where the first molten portion 113 of the cold plate 100H extends in the positive direction of the Z-axis. However, the second molten portion 123 may extend in the negative direction of the Z-axis, and the direction of extension of the first molten portion 113 may be non-parallel to it. Furthermore, the melting amounts of the first molten portion 113 and the second molten portion 123 may be equal or different, depending on the shapes of the first plate 110 and the second plate 120, respectively.
[0080] <<11. Other Exemplary Embodiments (9)>> Next, another exemplary embodiment (9) will be described. Figure 14 is a cross-sectional view of a cold plate 100I according to another exemplary embodiment (9). In the explanation using Figure 14, the differences from Figures 4 to 13 will be mainly explained.
[0081] As shown in Figure 14, the cold plate 100I differs from Figures 4 to 13 in that both the first molten portion 113 of the first plate 110 and the second molten portion 123 of the second plate 120 become the dummy weld beads described above.
[0082] The cold plate 100I has a third molten portion 143. The third molten portion 143 is a portion that is melted by laser light irradiated from the outer circumference onto the aforementioned joining surface S1 and extends along the in-plane direction of the joining surface S1, joining the first plate 110 and the second plate 120.
[0083] Furthermore, the first molten portion 113 and the second molten portion 123 of the cold plate 100I appear to be temporarily welded, but are actually formed by irradiation with laser light as dummy weld beads that are not actually welded. In this case, the first molten portion 113 and the second molten portion 123 play a role specifically in applying the same tension to the first plate 110 and the second plate 120.
[0084] In other words, the cold plate 100I makes it possible to reduce and equalize the difference between the residual stress of the first plate 110 and the residual stress of the second plate 120, thereby maintaining cooling performance while suppressing warping caused by laser welding.
[0085] Figure 14 shows an example where the first molten portion 113 and the second molten portion 123 of the cold plate 100I are formed in positions opposite to each other, but they may be in positions that are not opposite to each other. Also, Figure 14 shows an example where the melting amounts of the first molten portion 113 and the second molten portion 123 are equal, but depending on the shape of the first plate 110 and the second plate 120, the melting amount of one may be greater than that of the other. Furthermore, the direction in which the first molten portion 113 extends and the direction in which the second molten portion 123 extends may be non-parallel.
[0086] <<12. 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 arranged 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. The first plate 110 and the second plate 120 are joined together in the second region R2 by irradiation with laser light. Furthermore, it has a first molten portion 113 and a second molten portion 123 that are melted by irradiation with laser light. The first molten portion 113 extends from the first surface 110a of the first plate 110 toward the second plate 120 in the second region R2. The second molten portion 123 extends from the fourth surface 120b of the second plate 120 toward the first plate 110 in the second region R2. With such a cold plate 100, it is possible to maintain cooling performance while suppressing warping caused by laser welding.
[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 arranged 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, the first plate and the second plate are joined in the second region by irradiation with laser light and have a first molten portion and a second molten portion that are melted by irradiation with laser light, the first molten portion extends in the second region from the first surface of the first plate toward the second plate, and the second molten portion extends in the second region from the fourth surface of the second plate toward the first plate. (2) The cold plate according to (1), wherein the first molten portion and the second molten portion are formed at positions facing each other. (3) The cold plate according to (2), wherein the thickness of the portion of the first plate facing the first region is thinner than the thickness of the second plate in the first region, and the amount of melting in the first molten portion is greater than the amount of melting in the second molten portion. (4) The cold plate according to (2), wherein the thickness of the second plate in the first region is thinner than the thickness of the portion of the first plate facing the first region, and the amount of melting in the second molten portion is greater than the amount of melting in the first molten portion. (5) The cold plate according to (1), wherein the first molten portion and the second molten portion are formed in positions that are not opposite to each other. (6) The cold plate according to (5), wherein the thickness of the portion of the first plate facing the first region is thinner than the thickness of the second plate in the first region, the first molten portion is located on the first region side of the second molten portion, and the amount of melting in the first molten portion is equal to the amount of melting in the second molten portion.(7) The cold plate according to (5), wherein the thickness of the second plate in the first region is thinner than the thickness of the portion of the first plate facing the first region, the second molten portion is located closer to the first region than the first molten portion, and the amount of melting of the second molten portion is equal to the amount of melting of the first molten portion. (8) The cold plate according to (5), wherein the thickness of the portion of the first plate facing the first region is equal to the thickness of the second plate in the first region, one of the first molten portion and the second molten portion is located closer to the first region than the other, and the amount of melting of the other is greater than the amount of melting of the one. (9) The cold plate according to any one of (5) to (8), wherein the first molten portion extends from the first surface of the first plate, across the joint surface between the first plate and the second plate to the second plate, and the second molten portion extends from the fourth surface of the second plate, across the joint surface to the first plate. (10) The cold plate according to (1), wherein the first plate and the second plate are joined via an intermediate member that forms a side wall in the second region, the first molten portion extends from the first surface of the first plate beyond the second surface to the intermediate member, and the second molten portion extends from the fourth surface of the second plate beyond the third surface to the intermediate member. (11) The cold plate according to any one of (1) to (10), wherein the first surface of the first plate or the fourth surface of the second plate is a heat receiving surface that contacts a heat source.(12) A cooling structure 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 arranged 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 first surface of the first plate or the fourth surface of the second plate is a heat receiving surface in contact with a heat source; the second plate has a first region facing the plurality of fins and a second region located outside the first region; the first plate and the second plate are joined in the second region by irradiation with laser light and have a first molten portion and a second molten portion that are melted by irradiation with laser light, the first molten portion extends in the second region from the first surface of the first plate toward the second plate, and the second molten portion extends in the second region from the fourth surface of the second plate toward 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 100G Cold plate 100H Cold plate 100I Cold plate 110 First plate 110a First surface 110b Second surface 111 Fin 113 First melting area 115 Thermal expansion area 120 Second plate 120a Third surface 120b Fourth surface 123 Second melting area 125 Thermal expansion area 130 Intermediate member 143 Third melting area 300 Heat source 500 Parts R1 First region R2 Second region S1 Joining surface
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 arranged 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, the first plate and the second plate are joined in the second region by irradiation with laser light and have a first molten portion and a second molten portion melted by the irradiation with laser light, the first molten portion extending in the second region from the first surface of the first plate toward the second plate, and the second molten portion extending in the second region from the fourth surface of the second plate toward the first plate.
2. The cold plate according to claim 1, wherein the first molten portion and the second molten portion are formed at positions opposite to each other.
3. The cold plate according to claim 2, wherein the thickness of the portion of the first plate facing the first region is thinner than the thickness of the second plate in the first region, and the amount of melting in the first molten portion is greater than the amount of melting in the second molten portion.
4. The cold plate according to claim 2, wherein the thickness of the second plate in the first region is thinner than the thickness of the portion of the first plate facing the first region, and the amount of melting in the second molten portion is greater than the amount of melting in the first molten portion.
5. The cold plate according to claim 1, wherein the first molten portion and the second molten portion are formed at positions that are not opposite to each other.
6. The cold plate according to claim 5, wherein the thickness of the portion of the first plate facing the first region is thinner than the thickness of the second plate in the first region, the first molten portion is located on the first region side of the second molten portion, and the amount of melting in the first molten portion is equal to the amount of melting in the second molten portion.
7. The cold plate according to claim 5, wherein the thickness of the second plate in the first region is thinner than the thickness of the portion of the first plate facing the first region, the second molten portion is located on the first region side of the first molten portion, and the amount of melting in the second molten portion is equal to the amount of melting in the first molten portion.
8. The cold plate according to claim 5, wherein the thickness of the portion of the first plate facing the first region is equal to the thickness of the second plate in the first region, one of the first molten portion and the second molten portion is located closer to the first region than the other, and the amount of melting of the other portion is greater than the amount of melting of the one portion.
9. The cold plate according to claim 5, wherein the first molten portion extends from the first surface of the first plate, across the joint surface between the first plate and the second plate, to the second plate, and the second molten portion extends from the fourth surface of the second plate, across the joint surface, to the first plate.
10. The cold plate according to claim 1, wherein the first plate and the second plate are joined via an intermediate member that forms a side wall in the second region, the first molten portion extends from the first surface of the first plate beyond the second surface to the intermediate member, and the second molten portion extends from the fourth surface of the second plate beyond the third surface to the intermediate member.
11. The cold plate according to claim 1, wherein the first surface of the first plate or the fourth surface of the second plate is a heat receiving surface that contacts a heat source.
12. A cooling structure 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 arranged 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 first surface of the first plate or the fourth surface of the second plate is a heat receiving surface in contact with a heat source; the second plate has a first region facing the plurality of fins and a second region located outside the first region; the first plate and the second plate are joined in the second region by irradiation with laser light, and have a first molten portion and a second molten portion that are melted by the irradiation with laser light, the first molten portion extending in the second region from the first surface of the first plate toward the second plate, and the second molten portion extending in the second region from the fourth surface of the second plate toward the first plate.