Heat sink structure and method for manufacturing a heat sink used in the heat sink structure

Abstract

To provide a heat sink structure having a corrugated heat sink plate made of a metal plate in which a plurality of crest parts and valley parts are formed, capable of obtaining an excellent cooling performance which can be easily manufactured.SOLUTION: A heat sink structure comprises a heat sink 2 in which a plurality of crest parts 3 and valley parts 4, extending in a fluid direction of a cooling fluid are alternately provided in a direction orthogonal to the fluid direction. In each inner side of the crest parts 3 and each inner side of the valley parts 4, each of flow channels 30 and 40 extending toward a downstream side from an upstream side in the fluid direction is formed. In the inner side of each crest part 3, a fluid speed increase part that increases a fluid speed for cooling fluid is provided in at least a middle part of the fluid channel 30 by reducing a cross section area of a downstream fluid channel compared to that of an upstream fluid channel.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a forced flow type heat sink structure having a corrugated heat sink and a method for manufacturing the same. [Background technology]

[0002] Conventionally, a corrugated heat sink has been proposed for use in a power module, which is disposed within a flow path of a forcedly flowing cooling fluid, and which has louvers made of cut-out pieces in the intermediate wall between the peaks and valleys, causing the flowing cooling fluid (cooling medium) to swirl along the louvers to uniformize the temperature distribution (see Patent Document 1).

[0003] However, depending on the flow rate of the cooling fluid, the louvers made of the cut-and-raised pieces can obstruct the flow, which can cause heat to build up, especially inside the ridges, and can actually worsen the cooling performance.In addition, forming the louvers is difficult, which increases manufacturing costs. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-5673 Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, in view of the above-mentioned situation, the present invention aims to solve the problem of providing a forced flow type heat sink structure equipped with a corrugated heat sink that is easy to manufacture, can reduce costs, and provides excellent cooling performance. [Means for solving the problem]

[0006] The present invention includes the following inventions. (1) A heat sink structure comprising: a flow means for causing a cooling fluid to flow; and a corrugated heat sink made of a metal plate having a plurality of peaks and valleys extending in the flow direction of the cooling fluid, arranged alternately in a direction perpendicular to the flow direction; wherein the heat sink has flow passages formed inside the peaks and inside the valleys, each extending from the upstream side to the downstream side of the flow direction; and a flow rate increasing section is provided at least midway through the flow passage inside the peaks, which reduces the cross-sectional area of ​​the flow passage located on the downstream side compared to the upstream side, thereby increasing the flow rate of the cooling fluid.

[0007] (2) A heat sink structure as described in (1), in which the cross-sectional area of ​​the flow velocity increasing section is narrowed by configuring the left and right side walls of the ridge section that constitutes the flow passage to be closer to each other at the downstream position than at the upstream position.

[0008] (3) A heat sink structure as described in (2), in which the shape of the peak portion is changed so that the width of the peak is narrower downstream than upstream, thereby bringing the left and right side walls closer together.

[0009] (4) A heat sink structure as described in (2) in which the lower ends of the left and right side walls of the ridge portion are positioned closer to each other at a downstream position than at an upstream position, thereby making the left and right side walls closer to each other.

[0010] (5) A cooling fluid supply system including: a flow means for causing a cooling fluid to flow; and a heat sink made of a metal plate on which a plurality of peaks and valleys extending in the flow direction of the cooling fluid are arranged alternately in a direction perpendicular to the flow direction, the heat sink having a first heat sink plate and a second heat sink plate made of the metal plate on which the peaks and valleys are arranged; and by stacking the peaks and valleys of the first heat sink plate and the second heat sink plate one above the other, inter-peak flow paths extending from the upstream side to the downstream side in the flow direction are formed between each peak of the first heat sink plate and each corresponding peak of the second heat sink, and Between each valley portion of the first heat sink plate and each corresponding valley portion of the second heat sink, an inter-valley flow passage is formed, extending from the upstream side to the downstream side in the flow direction, and the first heat sink plate and the second heat sink plate are arranged diagonally stacked along the flow direction so that the overlapping depth is deeper downstream than upstream, thereby gradually bringing the tops of the upper and lower peaks and the bottoms of the valleys closer to each other, and the cross-sectional area of ​​both the inter-peak flow passage and the inter-valley flow passage on the downstream side is narrower than that on the upstream side, thereby forming a heat sink structure that functions as a flow rate increasing section that increases the flow rate of the cooling fluid. [Effects of the Invention]

[0011] The heat sink structure according to the present invention, as described above, includes a flow velocity increasing section at least midway along the flow passage inside the ridges, where heat is particularly likely to build up, that narrows the cross-sectional area of ​​the downstream flow passage compared to the upstream section, thereby increasing the flow velocity of the cooling fluid. As a result, when the cooling fluid flows through the flow passage, the flow rate per unit time passing near the inner surface of the ridges, which contributes to heat absorption, increases. In other words, more cooling fluid can be efficiently collected near the sidewalls to absorb heat, thereby improving heat dissipation efficiency. Furthermore, such a flow velocity increasing section can be realized by simply modifying the shape of the ridges, thereby reducing manufacturing costs.

[0012] Here, when the flow rate increasing section is configured such that the left and right side walls of the ridge section that constitutes the flow passage are closer to each other at the downstream position than at the upstream position, thereby reducing the cross-sectional area, this configuration can be easily processed by pressing the left and right side walls of the ridge section, and can be easily realized while suppressing increases in manufacturing costs.In addition, the cooling fluid passing through the flow passage is pressed against the inner surface of the ridge section by the flow rate increasing section, and heat is efficiently absorbed from the inner surface, thereby increasing the efficiency of heat dissipation.

[0013] In particular, in the case of a configuration in which the shape of the peaks is changed so that the left and right widths of the peaks are narrower downstream than upstream, thereby bringing the left and right side walls closer together, this configuration can be easily achieved by first forming peaks of the same cross-sectional shape along the entire length of the flow passage, and then pressing the left and right side walls so that they are closer together on the downstream side. This avoids increases in cost and allows the flow rate to be increased while the surface area of ​​the inner walls of the peaks remains the same along the flow direction, resulting in excellent cooling efficiency.

[0014] Furthermore, in a case where the lower ends of the left and right side walls of the peaks are closer to each other at the downstream position than at the upstream position, thereby forming the left and right side walls closer together, this configuration can be easily achieved without press processing or other processes by first forming peaks and valleys with the same cross-sectional shape along the entire length of the flow passage and then simply deforming the peaks and valleys so that adjacent peaks on the downstream side are closer to each other (and thus the valleys are also closer to each other), thereby avoiding increased costs. Furthermore, in such a heat sink, the cross-sectional area of ​​not only the inner surface of the peaks but also the inner surface of the valleys decreases toward the downstream side, and flow velocity increasing portions are also formed on the inner surface of the valleys, thereby further improving cooling efficiency. Furthermore, such a heat sink can increase the flow velocity while maintaining the same surface area of ​​the inner wall of the peaks and the inner wall of the valleys along the flow direction, thereby achieving excellent cooling efficiency.

[0015] The heat sink further includes a first heat sink plate and a second heat sink plate made of metal plates having ridges and valleys, and by stacking the ridges and valleys of the first heat sink plate and the second heat sink plate vertically, inter-ridge flow paths extending from the upstream side to the downstream side in the flow direction are formed between each ridge of the first heat sink plate and each corresponding ridge of the second heat sink, and inter-valley flow paths extending from the upstream side to the downstream side in the flow direction are formed between each valley of the first heat sink plate and each corresponding valley of the second heat sink, and the first heat sink plate and the second heat sink plate are stacked vertically. In a heat sink structure in which the peaks and valleys are arranged diagonally in the flow direction so that the depth of the peaks is deeper downstream than upstream, the tops of the peaks and the bottoms of the valleys gradually approach each other, and the cross-sectional area of ​​each of the inter-peak and inter-valley flow passages is narrower downstream than upstream, acting as flow rate increasing sections that increase the flow rate of the cooling fluid. As the cooling fluid flows through the inter-peak and inter-valley flow passages, the flow rate per unit time passing near the inner walls of each passage that contributes to heat absorption increases. In other words, more cooling fluid can be efficiently collected near the inner walls of each passage for heat absorption, thereby improving heat dissipation efficiency. Furthermore, this configuration can be easily achieved by simply overlapping the first and second corrugated heat sink plates, without press-forming or deforming the heat sink plates, thereby avoiding increased costs. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a perspective view showing a heat sink structure according to a representative embodiment of the present invention; [Figure 2] Cross section of line AA in Figure 1. [Figure 3] Cross-sectional view of line CC in Figure 1. [Figure 4] Cross-sectional view of line BB in Figure 1. [Figure 5] 10A to 10C are explanatory diagrams showing a manufacturing procedure of a heat sink used in the heat sink structure. [Figure 6] 10A and 10B are explanatory diagrams showing modified shapes of the peaks of the heat sink. [Figure 7] 10A and 10B are explanatory diagrams showing modified examples of the flow velocity increasing portion of the heat sink. [Figure 8] FIG. 10 is an explanatory diagram showing another modified example of the shape of the flow velocity increasing portion of the heat sink. [Figure 9] 10A to 10C are explanatory diagrams showing still other modified examples of the configuration of the flow velocity increasing portion of the heat sink. [Figure 10] FIG. 10 is a perspective view showing a modified example of the heat sink structure of the present invention. [Figure 11] Cross section of line AA in Figure 10. [Figure 12] Cross-sectional view of line CC in Figure 10. [Figure 13] FIG. 10 is an explanatory diagram showing a state in which the heat sink according to the modified example is deformed. [Figure 14] FIG. 10 is a perspective view showing another modified example of the heat sink structure of the present invention. [Figure 15] Cross-sectional view of line AA in Figure 14. [Figure 16] Cross-sectional view of line CC in Figure 14. [Figure 17] 10A to 10C are explanatory views showing a procedure for manufacturing the heat sink according to the modified example. DETAILED DESCRIPTION OF THE INVENTION

[0017] 1 to 4, a heat sink structure s1 according to a representative embodiment of the present invention includes a flow means 1 for flowing a cooling fluid 9, and a corrugated heat sink 2 made of a metal plate having a plurality of peaks 3 and valleys 4 extending in the flow direction of the cooling fluid 9, arranged alternately in a direction perpendicular to the flow direction. Flow passages 30, 40 are formed inside the peaks 3 and inside the valleys 4, respectively, extending from the upstream side to the downstream side in the flow direction. The peaks 3 refer to portions that are generally inverted U-shaped in cross section, and the valleys 4 refer to portions that are generally U-shaped in cross section. In this example, the side walls 34 are common, and the peaks 3 are composed of left and right side walls 34 and a top wall 33 at the top (upper portion), while the valleys 4 refer to portions that are composed of the left and right side walls 34 and a bottom wall 41 at the bottom (lower portion).

[0018] In particular, a flow rate increasing section 6 is provided at least midway along the flow path 30 inside the ridges 3, narrowing the cross-sectional area of ​​the flow path 30 located downstream compared to the upstream side, thereby increasing the flow rate of the cooling fluid 9. By providing the flow rate increasing section 6 in the flow path 30 inside the ridges 3 where heat tends to accumulate, the flow rate per unit time of the cooling fluid 9 passing near the inner surface of the ridges 3, which contributes to heat absorption, increases as the cooling fluid 9 flows through the flow path 30. In other words, a larger amount of cooling fluid 9 can be efficiently collected near the sidewalls 34 of the ridges 3, allowing heat to be absorbed by the sidewalls 34, thereby improving heat dissipation efficiency.

[0019] As shown in the cross-sectional views of Figures 1, 2, and 3, the flow velocity increasing section 6 is configured such that the left and right side walls 34 of the ridges 3 that make up the flow passage 30 are closer together downstream than upstream, thereby gradually narrowing the cross-sectional area of ​​the flow passage 30. More specifically, as can be seen from a comparison of the cross-sectional views of Figures 2 and 3, the shape of the tops (top walls 33) of the ridges 3 changes so that the left and right widths are narrower downstream than upstream, causing the left and right side walls 34 to be closer together downstream. This configuration allows the flow velocity to be increased while the surface area (internal surface area) of the inner walls of the ridges remains the same along the flow direction, resulting in excellent cooling efficiency.

[0020] More specifically, as the cross-sectional shape of the flow path 30 changes from a rectangle on the upstream side to a triangle on the downstream side, the distance from the center point (center of gravity) O of the flow path 30 to the side walls 34, 34 located on the left and right sides of the flow path 30 also changes, and the distance from the center point O to the side walls 34, 34 on the downstream side shown in Figure 3 is closer than that on the upstream side shown in Figure 2. Therefore, on the downstream side where the flow velocity of the cooling fluid is faster, more cooling fluid is efficiently collected near the side walls 34, 34 to absorb heat, thereby effectively improving cooling performance. As shown in Figure 6, a preferred example is one in which the side walls 34 are curved inwardly to further reduce the cross-sectional area.

[0021] 5, such a heat sink 2 can be manufactured very easily without requiring complex design or processing by forming a corrugated plate 102 having peaks 103 and valleys 104 of the same cross-sectional shape along the entire length of the flow path, and then further pressing the plate 102. Specifically, the left and right side walls 34 of the peaks 103 are pressed closer together toward the downstream side to form the heat sink 2. The plate 102 can be a corrugated heat sink plate previously proposed by the present applicant and described in JP 2018-129484 A.

[0022] The flow velocity increasing section 6 may be formed over the entire length of the flow passage 30, or may be formed only in a portion of it. For example, FIG. 7 shows an example in which it is formed only in the downstream half region. In addition to gradually narrowing the cross-sectional area to increase the flow velocity, a preferred example is one in which the cross-sectional area is reduced in a stepped manner at one or more locations, as shown in FIGS. 8 and 9(a). Furthermore, as shown in FIGS. 9(b) and 9(c), a relaxation region R1 that expands the cross-sectional area downstream of the flow velocity increasing section 6 is also preferred, as it can eliminate resistance and promote flow in the flow velocity increasing section 6. While an example in which the cross-sectional area gradually expands is shown here, a stepped expansion structure is also preferred.

[0023] Similar to the heat sink plate of the above publication, the heat sink 2 of this embodiment has a through groove 31 extending in the direction of flow of the cooling fluid, i.e., the lengthwise direction of the ridges 3, provided on the upper side of the ridges 3, and also has a pair of upright pieces 32, 32 that stand upward from the opening edge of the through groove 31. These upright pieces 32, 32 can be formed easily and at low cost by pressing a metal plate.

[0024] Specifically, the upright pieces 32 are formed as two long through grooves 31 extending in the length direction along the upper side of the ridge portion 3 in an area of ​​the heat sink 2 excluding one end (the supply side of the cooling fluid), the middle portion, and the other end (the discharge side of the cooling fluid) (see FIG. 1). The length, number, and spacing of the through grooves 31 can be determined appropriately. For example, three or more through grooves extending in the length direction of the ridge portion 3 may be provided, or only one through groove may be provided. The through groove 31 and the upright pieces 32, 32 may be formed by skipping one or two or more ridge portions 3. A structure in which the through groove 31 and the upright pieces 32, 32 are omitted may also be used.

[0025] Such through grooves 31 are expected to have the effect of allowing the cooling fluid, such as cold air located above, to smoothly flow into the flow passage 30 whose internal pressure has decreased due to the Venturi effect, and to have the effect of absorbing heat and discharging excess fluid that cannot pass through the flow passage 30, although this effect depends on the flow rate of the cooling fluid being supplied.

[0026] The flow passage 30 inside the ridges 3 of the heat sink 2 of the present invention excludes the spaces between the upstanding pieces 32, 32 on the outside of the through grooves 31, and the cross-sectional area thereof is also excluded. In this case, the inner surface area is reduced where the through grooves 31 exist, but since the upstanding pieces rise up by that amount, the surface area can be considered constant in the flow direction if these upstanding pieces are included.

[0027] Such a heat sink 2 is made of a metal plate such as a copper plate or an aluminum plate having high thermal conductivity. The bottom wall 41 of the valley portion 4 is fixed in close contact with a base member 5 fixed to an object to be cooled (not shown) such as an LED or a CPU by caulking or a fixing pin 51. The base member 5 is made of a material having high thermal conductivity such as a copper plate or an aluminum plate. The base member 5 may be omitted, and the bottom wall 41 of the valley portion 4 may be directly abutted against an object to be cooled (not shown).

[0028] The flow means 1 is arranged on the upstream side (the inlet side of the cooling fluid) of the heat sink 2, and is composed of a blower fan that sends the cooling fluid 9 to the peaks 3 and valleys 4, a suction fan that sucks the cooling fluid 9 from the downstream side (the outlet side), and fluid flow paths on the inlet and outlet sides that are provided as needed.

[0029] 10 to 13 show modified examples of the heat sink structure according to the present invention. As can be seen from a comparison of Figures 11 and 12, the heat sink 2 of the heat sink structure s2 according to this modified example has the lower ends 34a of the left and right side walls 34 of the ridges 3 positioned closer to each other at the downstream position than at the upstream position, so that the left and right side walls 34 are closer to each other.

[0030] As shown in Figure 13, such a heat sink 2 can be easily realized without press processing or the like by first forming a corrugated plate 102 having peaks 103 and valleys 104 of the same cross-sectional shape along the entire length of the flow passage as described above, and then simply deforming it so that adjacent peaks on the downstream side are closer to each other (and as a result, the valleys are also closer to each other).

[0031] In this heat sink 2, the cross-sectional area of ​​the flow passages 40 on the inner surfaces of not only the peaks 3 but also the valleys 4 decreases downstream, and flow velocity increasing sections 6A are also formed on the inner surfaces of the valleys 4, thereby further improving cooling efficiency. Furthermore, this heat sink 2 can also increase the flow velocity along the flow direction while keeping the surface areas of the inner walls of the peaks 3 and valleys 4 the same, thereby achieving excellent cooling efficiency. In this example, through grooves 31 and upright pieces 32 are provided midway through the flow passages, and their effects are as described above.

[0032] 14 to 17 show another modified example of the heat sink structure according to the present invention. The heat sink 2 of this modified example s3 includes a first corrugated heat sink plate 24 made of a metal plate having peaks 3A and valleys 4A, and a second corrugated heat sink plate 25 made of a metal plate having peaks 3B and valleys 4B. The peaks 3A, 3B and valleys 4A, 4B of the first and second heat sink plates 24, 25 are stacked one on top of the other. This stacking arrangement forms inter-peak flow passages 70 extending from the upstream side to the downstream side in the flow direction between each peak 3A of the first heat sink plate 24 and the corresponding peak 3B of the second heat sink plate 25, and inter-valley flow passages 80 extending from the upstream side to the downstream side in the flow direction between each valley 4A of the first heat sink plate 24 and the corresponding valley 4B of the second heat sink plate 25.

[0033] In particular, as can be seen by comparing Figures 15 and 16, the first heat sink plate 24 and the second heat sink plate 25 are arranged to be overlapped diagonally along the flow direction so that the overlapping depth (symbol L in the figures) is deeper downstream than upstream, and as a result, the tops (top walls 33, 33) of the upper and lower peaks 3A, 3B and the bottoms (bottom walls 41, 41) of the valleys 4A, 4B gradually approach each other toward the downstream side, and the cross-sectional area of ​​the inter-peak flow passage 70 and the inter-valley flow passage 80 on the downstream side is narrower than that on the upstream side, thereby forming flow rate increasing sections 6, 6A that increase the flow rate of the cooling fluid 9.

[0034] In the heat sink structure s3 of this example, when the cooling fluid 9 flows through the peak-to-peak flow passages 70 and the valley-to-valley flow passages 80, the flow rate per unit time passing near the inner walls of each passage that contributes to heat absorption increases. In other words, more cooling fluid can be efficiently collected near the inner walls of each passage to absorb heat, thereby improving the efficiency of heat dissipation.

[0035] Furthermore, such a heat sink 2 can be easily realized by simply stacking a first heat sink plate 24 and a second heat sink plate 25, which have been processed into a corrugated shape, one on top of the other, as shown in Figure 17, without having to press or deform each heat sink plate, thereby avoiding any increase in costs.

[0036] In this example, the lower first heat sink plate 24 is provided with a through groove 31 and standing pieces 32, 32 extending in the length direction of the ridge portion 3A, as in the above-mentioned examples (see FIG. 17). On the other hand, the upper second heat sink plate 24 is not provided with the through groove 31 and standing pieces 32, 32, and the upper side of the ridge portion 3A is closed by a top wall 33.

[0037] It is also possible to omit the through grooves 31 and the standing pieces 32, 32 provided in the ridges 3A of the lower first heat sink plate 24. However, if the through grooves 31 and the standing pieces 32, 32 are provided in the ridges 3A of the first heat sink plate 24, the Venturi effect allows the cooling fluid flowing inside the ridges 3A of the first heat sink plate 24 to smoothly flow into the inter-ridge flow passages 70 on the upper side, preventing heat from building up and allowing the cooling fluid to be discharged through the flow passages 70, which is effective.

[0038] Furthermore, if a downwardly protruding upright piece and a through groove are provided at the bottom of the valley portion 4B of the second heat sink plate 25, cooling fluid can be discharged or introduced from the inter-valley flow passage 80 through the through groove to the flow passage inside the valley portion 4B of the upper second heat sink plate 25, which is effective in more reliably preventing heat from building up.

[0039] Although the present invention has been described above in terms of an embodiment, it is to be understood that the present invention is not limited to such an embodiment and can be embodied in various forms without departing from the spirit and scope of the present invention. For example, the above description has been given of an example in which the heat sink is first press-formed into the heat sink plate 102 as shown in Figure 5 and then further deformed by pressing or the like, but it is of course also possible to manufacture the heat sink 2 having the flow velocity increasing portion according to the present invention by pressing or the like without first passing through the heat sink plate 102. [Example]

[0040] Next, we will explain the results of cooling performance tests conducted on Example 1, which is a sample of the heat sink structure of the present invention, and Comparative Example 1, which is a sample of the heat sink of Example 1 that does not have the conventional flow rate increasing portion.

[0041] (sample) Example 1 had the heat sink shown in Fig. 8. Comparative Example 1 had the state before deformation processing shown in the upper part of Fig. 5. All had the same length and number of peaks and valleys, plate material, thickness, etc., and were installed on the top surface of a base member.

[0042] (Test Method) A 10-watt LED was attached to the underside of the base member as the object to be cooled, the airflow rate of the flow means 1 was set to a constant, and the room temperature was set to 25°C.The underside temperature and the top surface temperature were measured at the same position on the base member.

[0043] (result) After 1 minute had passed, Comparative Example 1 had a lower surface temperature of 26.6°C and an upper surface temperature of 26.2°C, while Example 1 had a lower surface temperature of 25.7°C and an upper surface temperature of 25.1°C. After 20 minutes had passed, Comparative Example 1 had a lower surface temperature of 37.4°C and an upper surface temperature of 33.2°C, while Example 1 had a lower surface temperature of 36.1°C and an upper surface temperature of 30.8°C.

[0044] As described above, it was confirmed that after 20 minutes had passed, Example 1 according to the present invention had a lower bottom surface temperature of about 1.3°C and a lower top surface temperature of about 2.4°C compared to Comparative Example 1. This means that the cooling performance of Example 1 was improved over the Comparative Example by about 3.47% (=1.3°C / 37.4°C x 100%) in terms of the rate of decrease in bottom surface temperature, and by about 7.22% (=2.4°C / 33.2°C x 100%) in terms of the rate of decrease in top surface temperature. [Explanation of symbols]

[0045] 1 Fluid means 2 heat sinks 2 First heat sink plate 3 Yamabe 3A,3B Yamabe 4 Valley 4A, 4B Valley 5 Base material 6, 6A Flow velocity increase section 9 Cooling fluid 24 First heat sink plate 25 Second heat sink plate 30, 40 Distribution path 31 Through groove 32 Standing piece 33 Top Wall 34 Side wall 34a Lower end 40 Distribution path 41 Bottom wall 51 Fixing pin 70 Yamabe Interchange 80 Valley flow path 102 Heat sink plate 103 Yamabe 104 Valley R1 relaxation region s1~s3 Heat sink structure

Claims

1. A heat sink comprising: a flow means for causing a cooling fluid to flow; and a corrugated heat sink made of a metal plate having a plurality of peaks and valleys extending in the direction of flow of the cooling fluid, the peaks and valleys being arranged alternately in a direction perpendicular to the flow direction; The heat sink is a flow passage extending from the upstream side to the downstream side in the flow direction is formed inside the peak portion and inside the valley portion, A method of manufacturing a heat sink used in a heat sink structure in which a flow rate increasing section is provided in at least a middle section of the flow passage inside the ridge section, the flow passage being configured to increase a flow rate of the cooling fluid by narrowing a cross-sectional area of ​​the flow passage located downstream compared to that of the flow passage located upstream, the method comprising: After forming a corrugated plate having peaks and valleys of the same cross-sectional shape over the entire length of the flow passage, The plate is pressed to form the heat sink.

2. 2. A method for manufacturing a heat sink as described in claim 1, wherein the cross-sectional area of ​​the flow velocity increasing portion is narrowed by configuring the left and right side walls of the ridge portion that constitutes the flow passage to be closer to each other at the downstream position than at the upstream position.

3. 3. A method for manufacturing a heat sink as described in claim 2, wherein the shape of the ridge portion is changed so that the left and right width of the top of the ridge portion is narrower at the downstream position than at the upstream position, thereby bringing the left and right side walls closer together.

4. A heat sink comprising: a flow means for causing a cooling fluid to flow; and a corrugated heat sink made of a metal plate having a plurality of peaks and valleys extending in the direction of flow of the cooling fluid, the peaks and valleys being arranged alternately in a direction perpendicular to the direction of flow; The heat sink is a flow passage extending from the upstream side to the downstream side in the flow direction is formed inside the peak portion and inside the valley portion, a flow velocity increasing section that increases the flow velocity of the cooling fluid by narrowing the cross-sectional area of ​​the flow passage located downstream compared to the cross-sectional area of ​​the flow passage located upstream, at least in the middle of the flow passage inside the ridge section; the flow velocity increasing portion has a cross-sectional area narrowed by configuring left and right side walls of the ridge portion that constitutes the flow passage so that they are closer to each other at a downstream position than at an upstream position, A method of manufacturing a heat sink used in a heat sink structure in which a shape is changed so that a left-right width of the top of the peak portion is narrower at a downstream position than at an upstream position, thereby bringing the left and right side walls closer to each other, comprising: After forming a corrugated plate having peaks and valleys of the same cross-sectional shape over the entire length of the flow passage, The plate is pressed so that the left and right side walls of the peaks are closer to each other downstream, thereby forming the heat sink.

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