Refrigerant passage structure of heat sink

Abstract

To provide a refrigerant passage structure of a heat sink that can efficiently enhance cooling performance through improvement of a refrigerant path of the heat sink that cools a semiconductor module.SOLUTION: In a semiconductor device 1, a refrigerant path structure of a heat sink includes: a plurality of semiconductor modules 2a, 2b, and 2c; and a heat sink 6. The heat sink is mounted with the plurality of semiconductor modules on a plurality of defined sections 9a, 9b, and 9c of the module mounting surface, respectively. A refrigerant path 11 extending along a module mounting surface 8 is formed in the heat sink. The refrigerant path includes: a relay path 12 extending between a plurality of defined sections when viewed from a normal direction of the module mounting surface; and a plurality of section-by-section paths 21a, 21b, and 21c extending from the relay path toward the respective defined sections. Each section-by-section path forms a reciprocating path 25 including a turn-back part 22 for each defined section.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Embodiments of the present invention relate to a refrigerant flow path structure of a heat sink.

Background Art

[0002] Conventionally, a semiconductor device has been known in which a semiconductor module such as an IGBT (Insulated Gate Bipolar Transistor) module is mounted on a heat sink to enable cooling. However, in recent years, semiconductor devices have an increasing component mounting density in response to demands such as miniaturization, and thus a configuration for enhancing cooling efficiency more effectively is desired.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The problem to be solved by the present invention is to provide a refrigerant flow path structure of a heat sink that can enhance cooling efficiency more effectively by improving the refrigerant flow path of the heat sink for cooling a semiconductor module.

Means for Solving the Problems

[0005] The refrigerant flow path structure of the heat sink according to the embodiment includes a plurality of semiconductor modules and a heat sink. The heat sink mounts the plurality of semiconductor modules on a plurality of defined sections of the module mounting surface respectively. A refrigerant flow path is formed in the heat sink along the module mounting surface. The refrigerant flow path includes a relay path that extends across the plurality of defined sections when viewed from the normal direction of the module mounting surface, and a plurality of per-section paths that extend from the relay path toward each defined section. Each per-section path forms a reciprocating path including a folding portion for each defined section.

Brief Description of the Drawings

[0006] [Figure 1] Perspective view of the semiconductor device according to the embodiment. [Diagram 2] Explanatory diagram of the cooling water path of the heat sink of the semiconductor device according to the embodiment. [Diagram 3] Temperature distribution diagram of the heat sink according to the embodiment. [Figure 4] Explanatory diagram of the cooling water path of the conventional heat sink. [Figure 5] Temperature distribution diagram of the conventional heat sink. [Figure 6] Graph showing the surface temperature of the heat sink according to the embodiment. [Figure 7] Graph showing the surface temperature of the conventional heat sink. [Figure 8] Explanatory diagram of the cooling water path of the heat sink according to the second embodiment. [Figure 9] Temperature distribution diagram of the heat sink according to the second embodiment. [Figure 10] Graph showing the surface temperature of the heat sink according to the second embodiment. [Figure 11] Graph showing the pressure loss of the cooling water paths of the heat sinks according to each embodiment and the conventional heat sink.

Embodiments for Carrying Out the Invention

[0007] Hereinafter, the refrigerant flow path structure of the heat sink according to the embodiment will be described with reference to the drawings. Note that the same or corresponding components may be denoted by the same reference numerals, and repeated descriptions thereof may be omitted.

[0008] <Semiconductor device 1> FIG. 1 is a perspective view of the semiconductor device 1 according to the embodiment, and FIG. 2 is an explanatory view of the cooling water channel 11 of the heat sink 6 of the semiconductor device 1 according to the embodiment. The semiconductor device 1 according to the embodiment includes a plurality of semiconductor modules 2a, 2b, 2c including semiconductor elements (chips) 5, and a single heat sink 6 on which the plurality of semiconductor modules 2a, 2b, 2c are mounted.

[0009] For convenience of explanation, in the drawings, the arrow Y is in the front-rear direction, the arrow X is in the left-right direction, and the arrow Z is in the up-down direction. Also, the arrow FR in the drawing indicates the front in the Y direction, the arrow LH indicates the left in the X direction, and the arrow UP indicates the upper in the Z direction. The directions such as front, rear, left, and right in the embodiment do not limit the arrangement of the semiconductor device 1. Hereinafter, the plurality of semiconductor modules 2a, 2b, 2c are referred to as a first semiconductor module 2a, a second semiconductor module 2b, and a third semiconductor module 2c in order from the left side.

[0010] Each semiconductor module 2a, 2b, 2c includes a flat base 3 with a reduced thickness in the up-down direction, and a plurality of conductor connection portions 4 protruding from one side surface of the base 3 in the up-down direction. Each semiconductor module 2a, 2b, 2c is exemplified by, for example, an IGBT (Insulated Gate Bipolar Transistor) module.

[0011] The base 3 has a rectangular flat plate shape when viewed from the up-down direction. The front and rear sides of the rectangle when viewed from the up-down direction of the base 3 are arranged along the left-right direction, and the left and right sides are arranged along the front-rear direction. The base 3 is arranged with the thickness direction along the up-down direction. The upper and lower surfaces of the base 3 are arranged perpendicular to the up-down direction. The front and rear side portions and the left and right side portions of the base 3 are fixed to the heat sink 6 by screws or the like along the up-down direction. At each conductor connection portion 4, a connection portion with an external component is fixed by a screw or the like whose direction along the vertical direction.

[0012] The heat sink 6 includes a heat sink body 7 formed of a metal material such as copper or aluminum with high thermal conductivity (thermal conductivity). The heat sink body 7 has a rectangular flat plate shape that is slightly larger than the region where the plurality of semiconductor modules 2a, 2b, 2c are mounted when viewed from the vertical direction (the normal direction of the module mounting surface 8). The heat sink body 7 has a flat shape with a reduced thickness in the vertical direction. The heat sink body 7 is arranged with the front and rear sides of the rectangular shape viewed from the vertical direction along the left - right direction and the left and right sides along the vertical direction. The heat sink body 7 is arranged with the thickness direction along the vertical direction. The heat sink body 7 has both upper and lower surfaces arranged orthogonal to the vertical direction.

[0013] One side surface of the heat sink body 7 in the vertical direction is the module mounting surface 8 on which the plurality of semiconductor modules 2a, 2b, 2c are mounted. On the module mounting surface 8, a plurality of defined sections 9a, 9b, 9c for mounting the respective semiconductor modules 2a, 2b, 2c are formed. Hereinafter, the plurality of defined sections 9a, 9b, 9c are referred to as the first defined section 9a, the second defined section 9b, and the third defined section 9c in order from the left side.

[0014] Each of the defined sections 9a, 9b, 9c is formed, for example, in a rectangular shape when viewed from the vertical direction. Each of the defined sections 9a, 9b, 9c is arranged with the front and rear sides of the rectangular shape viewed from the vertical direction along the left - right direction and the left and right sides along the vertical direction. Each of the defined sections 9a, 9b, 9c has, for example, different sizes (front - to - rear widths). Each of the defined sections 9a, 9b, 9c has, for example, the positions of the rear sides 9r generally aligned, but the positions of the front sides 9f are different from each other. Each of the defined sections 9a, 9b, 9c has the left and right sides of adjacent sections close to each other. The front sides 9f of the first and third defined sections 9a, 9c are generally in the same front - to - rear direction position. The front side 9f of the second defined section 9b is offset rearward from the front sides 9f of the first and third defined sections 9a, 9c.

[0015] The heat sink 6 is a water-cooled type in which cooling water (refrigerant) circulates in cooling water channels (refrigerant flow paths) 11 formed in the heat sink body 7. For example, a water supply nozzle 7g for introducing cooling water into the cooling water channels 11 in the heat sink body 7 and a drain nozzle 7h for discharging cooling water from the cooling water channels 11 in the heat sink body 7 are respectively provided on the front edge of the heat sink body 7. The heat sink 6 is not limited to being water-cooled, and may be one that flows a refrigerant (including liquid and gas) other than cooling water.

[0016] <Cooling channel 11> 2, the cooling water passage 11 extends along the module mounting surface 8 within the thickness of the heat sink body 7. When viewed from the top-bottom direction, the cooling water passage 11 includes a relay path 12 that extends between the plurality of defined sections 9a, 9b, and 9c, and a plurality of section-by-section paths 21a, 21b, and 21c that extend from the relay path 12 toward the inside of each defined section 9a, 9b, and 9c. Hereinafter, the multiple section-by-section paths 21a, 21b, and 21c will be referred to as a first section-by-section path 21a, a second section-by-section path 21b, and a third section-by-section path 21c, in that order from the left.

[0017] The relay path 12 includes a water supply relay path 13 that bends to the right in the left-right direction from the downstream end of the water supply nozzle 7g on the left side in the left-right direction and extends in a straight line to the right in the left-right direction at a position forward of the front edges 9f of the first and third specified sections 9a, 9c, and a drainage relay path 14 that extends in a straight line from near the downstream end of the water supply relay path 13 to the left in the left-right direction at a position overlapping with the front edges 9f of the first and third specified sections 9a, 9c and is connected to the upstream end of the drainage nozzle 7h that is lined up on the left and right outside the water supply nozzle 7g.

[0018] Section-by-section paths 21a, 21b, and 21c extend from the relay path 12 toward the inside of each of the specified sections 9a, 9b, and 9c. The relay path 12 has first and second dividing sections 14a and 14b that divide the path into upstream and downstream sides, for example, in a range that overlaps with the first and second specified sections 9a and 9b in the left-right direction of the drainage relay path 14 (the direction in which the multiple specified sections 9a, 9b, and 9c are arranged). The relay path 12 has a third dividing section 14c that divides the water supply relay path 13 and the drainage relay path 14, for example, in a range that overlaps with the third specified section 9c in the left-right direction of the drainage relay path 14.

[0019] Each of the section paths 21a, 21b, and 21c extends as a pair of paths 23 and 24 from each of the divisions 14a, 14b, and 14c formed along the relay path 12 toward the designated section (rear side) where the divisions 14a, 14b, and 14c overlap in the left-right direction. Each of the paths 23 and 24 extends while curving in a spiral shape within the left-right width of the corresponding designated section. The paths 23 and 24 communicate with each other at a turning portion 22 to form a round-trip path 25 that includes the turning portion 22. Of the paths 23 and 24, the path extending from the upstream end of each of the divisions 14a, 14b, and 14c to the turning portion 22 is the outward path 23, and the path extending from the turning portion 22 to the downstream end of each of the divisions 14a, 14b, and 14c is the return path 24.

[0020] In the example of Fig. 2, for each path 21a, 21b, 21c in each section, a downstream reciprocating path 27 that makes one or two round trips through the left, right, and central parts of the corresponding defined section is formed on the downstream side of the return path 24. The path from the folding part 22 to the upstream end of the downstream reciprocating path 27 is referred to as the return path main body 24a. From the upstream ends of the respective divided parts 14a, 14b, 14c to the folding part 22, an upstream path 23 that is parallel to the return path main body 24a extends. The parallel paths composed of the return path main body 24a and the upstream path 23 extend so as to surround the outside of the downstream reciprocating path 27 from the respective divided parts 14a, 14b, 14c. The return path main body 24a and the upstream path 23 are arranged at positions (directly below the chip) that overlap the chip 5 when viewed from the vertical direction (extending along the chip arrangement). The downstream reciprocating path 27 includes paths arranged at positions that do not overlap the chip 5 when viewed from the vertical direction, but contributes to suppressing the temperature of the entire defined section.

[0021] The paths 21a, 21b, 21c for each section extend within the corresponding defined section and then return to the relay path 12 without reaching other defined sections. The cooling water path 11 flows to one side (right side) in the horizontal direction through the water supply relay path 13, and then flows from the path 21c for each third section corresponding to the third defined section 9c on one side in the horizontal direction, to the path 21b for each second section corresponding to the second defined section 9b in the center of the horizontal direction, and to the path 21a for each first section corresponding to the first defined section 9a on the other side (left side) in the horizontal direction, in this order, to cool each defined section 9a, 9b, 9c.

[0022] The portion that extends linearly along the front-rear direction in each path 21a, 21b, 21c for each section is referred to as the extension part 26. The extension part 26 is arranged so as to overlap the chip 5 of each defined section 9a, 9b, 9c when viewed from the vertical direction. The semiconductor modules 2a and 2c have the same outer shape, but the semiconductor module 2c has a larger heat generation amount of the chip. The semiconductor module 2b has a smaller outer shape and a smaller heat generation amount compared to the semiconductor modules 2a and 2c. By arranging the semiconductor module 2c with the largest heat generation amount in the third defined section 9c where the cooling water first flows in, there is an intention to preferentially cool it.

[0023] 4 shows a conventional cooling water channel 11'. In the conventional cooling water channel 11', a water supply nozzle 7g and a water drain nozzle 7h are arranged on one left-right side (right side) of the front edge of the heat sink body 7, and a pair of paths 23', 24' extend from each of these nozzles toward the specified compartment (rear). The pair of paths 23', 24' snake back and forth within the left-right width of the specified compartment 9c on one left-right side, proceeding to the other left-right side and extending to fill the entire left-right width of the specified compartment 9c on one left-right side. Thereafter, the pair of paths 23', 24' reach the left-right width of the specified section 9b in the center of the left-right direction, and extend to fill the left-right width of the specified section 9b in the center of the left-right direction, snaking back and forth in the same manner as within the left-right width of the specified section 9c on one side of the left-right direction.

[0024] Furthermore, the pair of paths 23', 24' reach the left-right width of the specified section 9a on the other side (left side) in the left-right direction, and extend to fill the left-right width of the specified section 9a on the other side in the left-right direction, snaking back and forth in the same manner as within the left-right widths of the other specified sections 9c, 9b. The pair of paths 23', 24' communicate with each other via a folded portion 22' at a position that fills the left-right width of the defined section 9a on the other side in the left-right direction. The conventional cooling water passage 11' has a structure in which a round trip path (parallel path) 25' is formed across the entire left-right width of the heat sink 6, and a turn-back portion 22' is provided on only one of the left and right sides of the heat sink 6. The cooling water flowing through the conventional cooling water passage 11' absorbs heat from each of the specified sections 9a, 9b, and 9c on an outward path 23' that runs from the specified section 9c on one left-right side to the specified section 9a on the other left-right side, and then flows in the opposite direction on a return path 24' to absorb heat before reaching the drain nozzle 7h.

[0025] Figure 3 is an explanatory diagram showing the distribution of the surface temperature of the heat sink 6 of an embodiment when the semiconductor device is operating, and Figure 6 is a graph showing the surface temperature of the heat sink 6 on the semiconductor module 2a, 2b, 2c side on the vertical axis and the position from the other end (left end) of the heat sink 6 in the left-right direction on the horizontal axis. FIG. 5 is an explanatory diagram showing the distribution of the surface temperature of a conventional heat sink 6 when a semiconductor device is in operation, and FIG. 7 is a graph similar to the diagram, showing the surface temperature of a conventional heat sink 6. In the temperature distribution diagrams of FIGS. 3, 5 (and FIG. 9 described later), the darker the color, the higher the temperature.

[0026] As shown in FIGS. 5 and 7, when measuring the surface temperature of the heat sink 6 when the conventional cooling water channel 11' is applied, the temperature difference between the chips in each specified section 9a, 9b, 9c is a maximum of 5° C. in the first specified section 9a. Also, the highest surface temperature was 63° C.

[0027] On the other hand, when measuring the surface temperature of the heat sink 6 when the cooling water channel 11 of the embodiment is applied, as shown in FIGS. 3 and 6, the temperature difference between the chips in each specified section 9a, 9b, 9c is suppressed to a maximum of 0.3° C. in the third specified section 9c, and the highest temperature is suppressed to 58° C. Thus, according to the cooling water channel 11 of the embodiment, it can be seen that the temperature difference between the chips is almost eliminated and the highest temperature also decreases. In the heat sink 6 for cooling the switching element, a thermal gradient occurs due to the arrangement of the heat sources (chips) and the positional relationship between the heat sources and the flow paths. Since the chips are affected by the operating temperature, it is desirable that the thermal gradient between the chips is low, and the configuration of the embodiment is suitable.

[0028] As described above, the refrigerant flow path structure of the heat sink 6 of the embodiment includes a plurality of semiconductor modules 2a, 2b, 2c, and a heat sink 6 that mounts the plurality of semiconductor modules 2a, 2b, 2c on a plurality of specified sections 9a, 9b, 9c arranged in a first direction on the module mounting surface 8, respectively. A cooling water channel 11 extending along the module mounting surface 8 is formed in the heat sink 6. The cooling water channel 11 includes a relay path 12 that extends across the plurality of specified sections 9a, 9b, 9c when viewed from the normal direction of the module mounting surface 8, and a plurality of per-section paths 21a, 21b, 21c that extend from the relay path 12 toward each of the specified sections 9a, 9b, 9c. Each per-section path 21a, 21b, 21c forms a reciprocating path 25 including a folding portion 22 for each of the specified sections 9a, 9b, 9c.

[0029] According to this configuration, the section-by-section paths 21a, 21b, and 21c extend from the relay path 12 to correspond to each of the specified sections 9a, 9b, and 9c, and each section-by-section path 21a, 21b, and 21c forms a round-trip path 25 including a return section 22 within the corresponding specified section 9a, 9b, and 9c. This allows the cooling water path 11 to move the cooling water back and forth between each of the specified sections 9a, 9b, and 9c. This configuration offers the following advantages over a round-trip path 25' (see FIG. 4 ) that extends across the specified sections 9a, 9b, and 9c: The temperature gradient of the cooling water within the specified sections 9a, 9b, and 9c is reduced, improving the temperature difference between the mounted chips. Furthermore, the temperature difference between the outgoing path 23 and the returning path 24 of the cooling water path 11 within each specified section 9a, 9b, and 9c is reduced, improving the temperature balance between the chips.

[0030] In the refrigerant flow path structure of the heat sink 6 described above, each of the compartment paths 21a, 21b, 21c has an extension portion 26 that extends within the specified compartments 9a, 9b, 9c in a second direction that intersects with the first direction, and the extension portion 26 is arranged so as to overlap with the chips 5 of the semiconductor modules 2a, 2b, 2c when viewed from the normal direction of the module mounting surface 8. According to this configuration, the extensions 26 of the section-by-section paths 21a, 21b, 21c are arranged so as to follow the chip arrangement (in other words, so as to be positioned directly below the chip), thereby effectively improving the cooling performance of the heat sink 6.

[0031] In the refrigerant flow path structure of the heat sink 6 described above, the cooling water path 11 allows the cooling water to flow in order from the specified section 9c on one side (right side) in the first direction to the specified section 9a on the other side (left side) in the first direction. By flowing the cooling water in order from the specified section 9c on one side of the heat sink 6 in the first direction to the specified section 9a on the other side of the first direction, it becomes possible to arrange the semiconductor modules that generate a lot of heat upstream, thereby improving the cooling efficiency. Also, by reversing the flow of the cooling water in the cooling water channel 11, it becomes possible to change the cooling order of the semiconductor modules in the first direction, resulting in a highly versatile flow channel structure.

[0032] Second Embodiment Next, a second embodiment of the present invention will be described. Referring to FIG. 8, the semiconductor device 31 of the second embodiment has partition-by-partition paths 51a, 51b, 51c that eliminate the downstream reciprocating paths 27a, 27b, 27c with respect to the semiconductor device 1 of the first embodiment, and is particularly different in that a part of the flow path is shortened at a position that does not overlap with the chips 5 of the semiconductor modules 2a, 2b, 2c in the partition-by-partition paths 51a, 51b, 51c. The same components as those in the above embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

[0033] The relay path 12 of the cooling water channel 41 in the second embodiment includes a water supply relay path 13 connected to the downstream end of the water supply nozzle 7g on the left side in the left-right direction, and a drainage relay path 14 connected to the upstream end of the drainage nozzle 7h. The water supply and drainage relay paths 13, 14 are each entirely or at least partially located outside the respective defined partitions 9a, 9b, 9c when viewed from the up-down direction.

[0034] Each partition-by-partition path 51a, 51b, 51c extends a pair of paths 53, 54 from each of the divided portions 14a, 14b, 14c formed in the middle of the relay path 12 to the defined partition side (rear side) where the left-right positions overlap with the divided portions 14a, 14b, 14c. The pair of paths 53, 54 extend while bending in a swirling manner within the left-right width of the corresponding defined partitions 9a, 9b, 9c. The pair of paths 53, 54 communicate with each other at the turning portion 52, and form a reciprocating path 55 including the turning portion 52. Among the pair of paths 53, 54, the path extending from the upstream end of each of the divided portions 14a, 14b, 14c to the turning portion 52 is the forward path 53, and the path extending from the turning portion 52 to the downstream end of each of the divided portions 14a, 14b, 14c is the return path 54.

[0035] The parallel paths composed of the forward path 53 and the return path 54 extend from each of the divided portions 14a, 14b, 14c to the right side of the defined partitions 9a, 9b, 9c and then rearward, and turn leftward and forward near the rear side of the defined partitions 9a, 9b, 9c and extend to reach the turning portion 52.

[0036] Each of the section routes 51a, 51b, and 51c extends within the corresponding specified section and then returns to the relay route 12 without reaching another specified section. Each of the section-by-section paths 51a, 51b, 51c flows to one side (right side) in the left-right direction through the water supply relay path 13, then flows from the third section-by-section path 51c corresponding to the third specified section 9a on one side in the left-right direction, to the second section-by-section path 51b corresponding to the second specified section 9b in the center in the left-right direction, and to the first section-by-section path 51a corresponding to the first specified section 9a on the other side in the left-right direction (left side), thereby cooling each of the specified sections 9a, 9b, 9c.

[0037] The extensions 56 are arranged so as to overlap the chips 5 in the respective defined sections 9a, 9b, and 9c when viewed from above and below. Although semiconductor modules 2a and 2c have the same external dimensions, semiconductor module 2c generates more heat from its chips. Semiconductor module 2b has a smaller external dimension and generates less heat than semiconductor modules 2a and 2c. By placing semiconductor module 2c, which generates the most heat, in third specified section 9c, where cooling water first flows in, the aim is to cool it preferentially.

[0038] The front edge 9f of the second defined section 9b is offset rearward from the front edges 9f of the first and third defined sections 9a and 9c. The second defined section 9b has a smaller area than the first and third defined sections 9a and 9c. An empty area (an area that does not overlap with the semiconductor modules 2a, 2b, and 2c when viewed from above) is formed in front of the second defined section 9b. In the example of FIG. 9 , the folded portion 52 of the second defined section path 51b is positioned directly below the front edge of the second defined section 9b (at a position that overlaps with the front edge 9f when viewed from above), eliminating a flow path (particularly the extension portion 56) in the empty area. When viewed from above, the second defined section path 51b has the extension portion 56 positioned in a portion that overlaps with the semiconductor modules 2a, 2b, and 2c, and does not have the extension portion 56 in a portion that does not overlap with the semiconductor modules 2a, 2b, and 2c (a portion that does not match the chip layout). This reduces the flow path in the region where active cooling by cooling water is not required, and reduces pressure loss in the cooling water path 41.

[0039] FIG. 11 is a graph showing the pressure loss of the cooling water passage 41 on the vertical axis and the flow rate of the cooling water passage 41 on the horizontal axis. As shown in FIG. 11, compared with the conventional cooling water passage 11’ (see FIG. 4), the pressure loss of the cooling water passage 11 (see FIG. 2) of the first embodiment is reduced, but the pressure loss of the cooling water passage 41 (see FIG. 8) of the second embodiment is further significantly reduced compared with the first embodiment. The cooling water passage 41 in the heat sink 6 is preferably of low pressure loss because if the pressure loss is high, the flow velocity will decrease and the cooling efficiency will deteriorate. In the second embodiment, by optimizing the cooling flow path according to the chip arrangement, the heat sink 6 is made isothermal and the cooling efficiency is improved.

[0040] FIG. 9 is an explanatory diagram similar to FIGS. 3 and 5, showing the surface temperature distribution of the heat sink 6 in the second embodiment. FIG. 10 is a graph similar to FIGS. 6 and 7, showing the surface temperature of the heat sink 6 of the second embodiment. As shown in FIGS. 9 and 10, the temperature difference between the chips in each defined section 9a, 9b, 9c is 1.6°C, and the maximum temperature is 59°C. Thus, in the second embodiment, by increasing the operating flow rate due to the reduction of the pressure loss of the cooling water passage 41, it is possible to improve the cooling performance compared with the conventional configuration despite reducing the number of flow paths (downstream reciprocating paths 27a, 27b, 27c).

[0041] As described above, also in the refrigerant flow path structure of the heat sink 6 of the second embodiment, similar to the first embodiment, partition-by-partition paths 51a, 51b, 51c are extended from the relay path 12 corresponding to each of the specified partitions 9a, 9b, 9c, and each partition-by-partition path 51a, 51b, 51c forms a reciprocating path 55 including a folding portion 52 within the corresponding specified partition 9a, 9b, 9c. As a result, since the cooling water channel 41 reciprocates the cooling water for each of the plurality of specified partitions 9a, 9b, 9c, the following effects are achieved compared to the case of forming a reciprocating path 25' (see FIG. 4) extending across the plurality of specified partitions 9a, 9b, 9c. That is, the temperature gradient of the cooling water within the specified partitions 9a, 9b, 9c can be reduced, and the temperature difference between the mounted chips can be improved. Also, the temperature difference between the forward path 53 and the return path 54 of the cooling water channel 41 in each specified partition 9a, 9b, 9c can be reduced, and the temperature balance between the chips can be improved. Further, by arranging the extending portions 56 of each partition-by-partition path 51a, 51b, 51c along the chip arrangement (so as to be positioned directly below the chips), the cooling performance of the heat sink 6 can be effectively enhanced. Also, by flowing the cooling water in order from the third specified partition 9c on one side in the left-right direction to the first specified partition 9a on the other side in the left-right direction in the heat sink 6, it becomes possible to take measures such as arranging the high heat-generating semiconductor module on the upstream side, and the cooling efficiency can be improved. Also, by reversing the flow of the cooling water in the cooling water channel 11, it becomes possible to change the cooling order of the semiconductor modules in the first direction, and a highly versatile flow path structure can be obtained.

[0042] And according to the refrigerant flow path structure of the heat sink 6 of the second embodiment, each partition-by-partition path 51a, 51b, 51c reduces the flow paths at positions that do not overlap with the chips 5 of the semiconductor modules 2a, 2b, 2c when viewed from the normal direction of the module mounting surface 8. According to this configuration, for each section, the paths 51a, 51b, and 51c reduce the flow paths other than directly under the chip, thereby minimizing the flow path length, reducing the pressure loss, increasing the flow rate of the cooling water, and improving the cooling performance. Also, by suppressing the flow path length, the processing of the heat sink 6 can be reduced, and cost reduction can be achieved. Further, compared with a configuration that does not reduce the flow paths other than directly under the chip, even if the flow rate of the cooling water is the same, the pressure loss is reduced, so it is possible to reduce the capacity of the cooling water pump, and the miniaturization and cost reduction of the pump can be achieved.

[0043] Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof.

Explanation of Reference Numerals

[0044] 1, 31... semiconductor device 2a, 2b, 2c... semiconductor module 5... chip, element 6... heat sink 8... module mounting surface 9a, 9b, 9c... specified section 11, 41... cooling water path 12... relay path 21a, 21b, 21c, 51a, 51b, 51c... path for each section 22, 52... turning portion 23, 53... forward path 24, 54... return path 25, 55... round-trip path 26, 56... extension portion

Claims

1. A heat sink comprising a plurality of semiconductor modules and a heat sink that mounts the plurality of semiconductor modules on a plurality of defined sections arranged in a first direction on a module mounting surface. A cooling water channel extending along the module mounting surface is formed in the heat sink. The cooling water channel includes a relay path extending across the plurality of defined sections when viewed from the normal direction of the module mounting surface, and a plurality of section-by-section paths extending from the relay path toward each defined section. A refrigerant flow path structure of a heat sink, wherein each of the plurality of section-by-section paths forms a reciprocating path including a folding portion for each defined section.

2. Each of the plurality of section-by-section paths has an extension portion extending along a second direction intersecting the first direction within the corresponding defined section. The refrigerant flow path structure of the heat sink according to claim 1, wherein the extension portion is arranged to overlap a chip of a semiconductor module mounted in the corresponding defined section when viewed from the normal direction of the module mounting surface.

3. The refrigerant flow path structure of the heat sink according to claim 2, wherein each of the plurality of section-by-section paths reduces a flow path at a position that does not overlap with the semiconductor module mounted in the corresponding defined section when viewed from the normal direction of the module mounting surface.

4. The refrigerant flow path structure of the heat sink according to any one of claims 1 to 3, wherein the cooling water channel sequentially flows cooling water from the defined section on one side in the first direction to the defined section on the other side in the first direction.

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