Cooling device

Abstract

[Problem] To provide an inexpensive cooling device with which it is possible to perform cooling without excess or deficiency by reviewing a configuration including a region where a flow passage is formed. [Solution] The present invention comprises a first cooling part 10 for cooling a first semiconductor chip 212 that is mounted on a first region 210 of a semiconductor substrate 200 and has a relatively large heat generation amount, a second cooling part 20 for cooling a second semiconductor chip 222 that is mounted on a second region 220 of the semiconductor substrate 200 and has a relatively small heat generation amount, and a planar connection part 30 between the first cooling part 10 and the second cooling part 20. A flow passage for a cooling medium is formed in the first cooling part 10, and the flow passage for the cooling medium is not formed in the second cooling part 20.

Description

cooling device

[0001] The present invention relates to a cooling device, and more particularly to a cooling device that includes both a first cooling section in which a flow path through which a cooling medium passes is formed, and a second cooling section in which no flow path is formed.

[0002] Patent Document 1 states that Patent Document 2 discloses a method for cooling multiple semiconductor elements (heat generating elements) mounted on a circuit board in an electronic device using a refrigerant, and then explains that in the cooling device disclosed in Patent Document 2, if the flow path is configured to pass through the heat generating elements scattered on the same circuit board in order, the temperature of the refrigerant will become higher the further downstream, resulting in a decrease in the cooling efficiency of the heat generating elements downstream.

[0003] JP 2009-099995 A U.S. Pat. No. 5,646,824

[0004] However, the consideration of the invention described in Patent Document 2 disclosed in Patent Document 1 is insufficient because there may be cases where the cooling efficiency of the heat-generating element does not need to be very high, for example, when the heat-generating element downstream does not generate much heat.

[0005] If the cooling efficiency of the downstream heat generating element does not need to be very high, there is no need to route the flow path directly toward the heat generating element, and if the flow path is routed excessively in the formation area, this will increase manufacturing costs and make the cooling device expensive.

[0006] Therefore, an object of the present invention is to provide an inexpensive cooling device that can provide just the right amount of cooling by reviewing the configuration including the region where the flow passages are formed.

[0007] In order to solve the above problem, the cooling device of the present invention comprises: a first cooling section that cools a first heating element that is mounted on a substrate and generates a relatively large amount of heat; a second cooling section that cools a second heating element that is mounted on the substrate and generates a relatively small amount of heat; and a connecting section that connects the first cooling section and the second cooling section in a planar manner, wherein a flow path for a cooling medium is formed in the first cooling section, and a flow path for a cooling medium is not formed in the second cooling section.

[0008] The first cooling portion and the second cooling portion may be made of different materials.

[0009] The connecting portion may include an I-shaped or L-shaped portion in plan view.

[0010] Preferably, one of the cross-sectional shapes of the first cooling section and the second cooling section of the connecting section is concave, and the other is convex.

[0011] The first cooling unit and the second cooling unit may be connected mechanically, chemically, or thermally.

[0012] The flow channel may have projections and depressions formed by mechanical or chemical processing. MODE FOR CARRYING OUT THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a cooling device according to the present invention will be described with reference to the drawings, taking a cooling device for semiconductor chips as an example. In each drawing, the same parts are designated by the same reference numerals.

[0014] (First Embodiment) Fig. 1 is a schematic plan view of a semiconductor chip cooling device 100 according to a first embodiment of the present invention. Fig. 2 is a cross-sectional view in the short direction of Fig. 1. Fig. 3 is an exploded perspective view of the semiconductor chip cooling device 100 shown in Fig. 1.

[0015] 3, in order to facilitate understanding of the manner in which the semiconductor chip cooling device 100 is used, a semiconductor substrate 200 on which first and second semiconductor chips 212, 222 are mounted is shown only on the lower side of the semiconductor chip cooling device 100. Note that the semiconductor chip cooling device 100 is configured so that it can also cool a semiconductor substrate on which a semiconductor chip (not shown) is mounted on the upper side thereof.

[0016] The semiconductor chip cooling device 100 may be sized to correspond to the size of the semiconductor substrate 200. Assuming that the semiconductor substrate 200 is a general-purpose size, the semiconductor chip cooling device 100 may have a longitudinal length of 450 mm to 500 mm (e.g., 480 mm), a lateral length of 150 mm to 200 mm (e.g., 160 mm), and a thickness of 3 mm to 10 mm (e.g., 6 mm).

[0017] 1, the semiconductor chip cooling device 100 is broadly divided into a first cooling section 10, a second cooling section 20, and a connection section 30, which will be described below. Hereinafter, the first cooling section 10 will be mainly described first, followed by the connection section 30, and then the second cooling section 20.

[0018] The first cooling unit 10 is a portion that cools a plurality of first semiconductor chips 212 that generate a relatively large amount of heat and are mounted in a first region 210 of the semiconductor substrate 200 shown in Fig. 3. As shown in Fig. 2, the first cooling unit 10 has a three-layer structure consisting of a first layer 12, a second layer 14, and a third layer 16.

[0019] The first, second, and third layers 12, 14, and 16 may have the same thickness or different thicknesses. If the thicknesses are the same, they may all be 1 mm to 5 mm (e.g., 2 mm). If the thicknesses are different, only the second layer 14 may be thinner, at 1 mm to 3 mm (e.g., 1 mm).

[0020] The first cooling section 10 does not necessarily have to have a three-layer structure, and may have, for example, a two-layer structure (for example, only the second layer 14 and the third layer 16) or a four-layer structure. In this case, the manufacturing conditions of the flow path may or may not be changed depending on the number of layers.

[0021] The first cooling unit 10 has a receiving portion 16B for the first semiconductor chip 212 on the lower side of Fig. 2, and similarly has a receiving portion 12B on the upper side of Fig. 2. The receiving portion 16B and the like serve to achieve close contact between the third layer 16 and the first semiconductor chip 212, and also to absorb any height differences between the first semiconductor chips 212.

[0022] If there is a large difference in height between the first semiconductor chips 212, one method is to dig out corresponding positions in the first and third layers 12, 16 and provide receiving portions 12B, 16B there so that the steps can be sufficiently absorbed. Thermal interface materials such as thermal pads can be used for the receiving portions 16B, etc.

[0023] 3, the first cooling unit 10 has flow path sections 12A, 14A, and 16A that form a flow path for the cooling medium. The cooling medium can be either cooling water or cooling gas. For example, when the semiconductor chip cooling device 100 is used in a factory, it is preferable to use cooling water from the perspective of cooling efficiency, while when the semiconductor chip cooling device 100 is incorporated into a final product, it is preferable to use cooling gas from the perspective of handling efficiency.

[0024] The cooling medium will vary depending on the heat generation temperature of the object to be cooled, but in the case of a semiconductor chip, which typically has a temperature of about 250°C, cooling water can be used at a temperature of about 25°C and a flow rate of 600 cc / min, for example, and cooling air can be used at a temperature of about 10°C and a flow rate of 800 cc / min, for example.

[0025] If it is essential to use cooling water as the cooling medium, the first cooling part 10 may be manufactured under conditions that ensure the airtightness of the flow passages so that the cooling water does not leak from the flow passages. One manufacturing method for this purpose is to connect the first layer 12, the second layer 14, and the third layer 16 by diffusion bonding.

[0026] When the thickness of the first and third layers 12, 16 is, for example, 2 mm, the flow path portions 12A, 16A may be formed by processing grooves to a depth of about 1.3 mm, and then processing the inner walls of the grooves to have irregularities of about 0.1 mm to 1.0 mm. For this purpose, etching, for example, may be used, although this is not limited to this method.

[0027] In this embodiment, although it is not essential to do so, in order to increase the surface area of ​​the flow path from the viewpoint of cooling efficiency, the flow path portions 12A and 16A are processed to form irregularities by mechanical or chemical processing (e.g., etching).

[0028] The first cooling part 10 is preferably made of a material with high thermal conductivity, such as copper, aluminum, stainless steel, aluminum nitride, ceramic, or alloys thereof. The first, second, and third layers 12, 14, and 16 may or may not all be made of the same material.

[0029] When cooling water is used as the refrigerant, the first cooling section 10 can be made of stainless steel, which has excellent rust resistance. Of course, even if a material with poor rust resistance (such as copper) is used, it can be used by applying rust prevention processing to the surface.

[0030] On the other hand, when the first cooling section 10 uses a cooling gas as a refrigerant, the material can be selected according to the cooling requirements of the first semiconductor chip 212, for example, copper material if heat conductivity is prioritized, or aluminum material if weight is prioritized.

[0031] Next, the connection portion 30 will be described.

[0032] The connection part 30 is a part that connects the first cooling part 10 and the second cooling part 20 in a planar manner. The connection part 30 has a shape that includes an I-shaped portion in a plan view as shown in Fig. 1, and has an uneven shape in a cross-sectional view as shown in Fig. 2.

[0033] 1, the connecting part 30 has an I-shape extending in the left-right direction of the drawing, and as shown in Fig. 2, the cross-sectional shape of the first cooling part 10 is concave and the cross-sectional shape of the second cooling part 20 is convex, and the connecting part 30 is connected in a manner such that the end of the first layer 22 of the second cooling part 20 is sandwiched between the ends of the first and third layers 12, 16 of the first cooling part 10. However, the cross-sectional shape of the first cooling part 10 may be convex and the cross-sectional shape of the second cooling part 20 may be concave.

[0034] The connection part 30 can be, for example, a mechanical connection such as screwing the first cooling part 10 and the second cooling part 20 together, a chemical connection such as bonding with an adhesive, a thermal connection such as welding or diffusion bonding, or a chemical-thermal hybrid connection such as using a thermally conductive adhesive.

[0035] Next, the second cooling section 20 will be described.

[0036] The second cooling unit 20 is a portion that cools a plurality of second semiconductor chips 222 that have a relatively small amount of heat generation and are mounted in a second region 220 of the semiconductor substrate 200 shown in Fig. 3. As shown in Fig. 2, the second cooling unit 20 has a single-layer structure consisting of only a first layer 22.

[0037] The thickness of the first layer 22 can be 1 mm to 5 mm (for example, 3 mm). If the thickness of the first layer 22 is thicker than the second layer 14 of the first cooling part 10, then, depending on the deformability of the first layer 22, the end portions of the first layer 22 may be thinned to approximately the thickness of the second layer 14. On the other hand, if the first layer 22 of the second cooling part 20 is thinner than the second layer 14 of the first cooling part 10, then the gap may be eliminated by, for example, using an attachment made of the same material as the second cooling part 20.

[0038] It should be noted that the second cooling section 20 does not necessarily have to have a single-layer structure, and may have, for example, a two-layer structure or a three-layer structure, in which case the thickness and material of each layer may or may not be the same.

[0039] Similar to the first cooling unit 10, the second cooling unit 20 includes a receiving portion 22B.

[0040] 3, the second cooling section 20 does not have a flow path, so the semiconductor chip cooling device 100 can be manufactured more inexpensively than when flow paths are formed over the entire surface.

[0041] The second cooling unit 20 may also be made of a high thermal conductivity material such as copper or aluminum. The first cooling unit 10 and the second cooling unit 20 may be made of the same material or different materials. The second cooling unit 20 does not necessarily have to be restricted by the cooling medium, so there is more freedom in material selection than for the first cooling unit 10.

[0042] In other words, the second cooling section 20 can be selected according to the cooling requirements of the second semiconductor chip 222, for example, by using copper material when thermal conductivity is prioritized, or aluminum material when weight is prioritized.

[0043] As described above, the semiconductor chip cooling device 100 of this embodiment has the advantage that it can effectively cool the first semiconductor chip 212, which generates a relatively large amount of heat, while it does not have to excessively cool the second semiconductor chip 222, which generates a relatively small amount of heat, at the expense of increasing the cost of the semiconductor chip cooling device 100.

[0044] On the other hand, according to the semiconductor chip cooling device 100 of this embodiment, the end of the first layer 22 of the second cooling section 20 is sandwiched between the ends of the first and third layers 12, 16 of the first cooling section 10, so that the heat generated in the second semiconductor chip 222 is not only absorbed and released by the second cooling section 20, but can also be transferred to and cooled by the first cooling section 10, which has a relatively high cooling efficiency, making it possible to prevent the cooling efficiency of the second cooling section 20 from decreasing too much.

[0045] It should be noted that the semiconductor chip cooling device 100 of this embodiment is merely illustrative, and for example, the sizes and positions of the first and second semiconductor chips 212, 222 on the semiconductor substrate 200 are merely examples. Therefore, the positions of the first and second cooling parts 10, 20 in the semiconductor chip cooling device 100, and in turn the positions of the first and second cooling parts 10, 20, are not limited to the aspects shown in FIGS.

[0046] Furthermore, the semiconductor chip cooling device 100 of this embodiment can be partially modified or altered as needed, and for example, the second cooling section 20 can be made up of, for example, two or three relatively small cooling sections instead of the relatively large single section shown in Figure 1. This eliminates the need to take measures against warpage that can occur in the case of a large section, and can prevent the semiconductor chip cooling device 100 from increasing in cost.

[0047] (Embodiment 2) Fig. 4 is a plan view of a semiconductor chip cooling device 100 according to embodiment 2 of the present invention, and corresponds to Fig. 1. Fig. 5 is a cross-sectional view in the short direction of Fig. 4, and corresponds to Fig. 2. In Figs. 4 and 5, a semiconductor substrate 200 is also shown to help understand how the semiconductor chip cooling device 100 is used.

[0048] The semiconductor chip cooling device 100 shown in Figures 4 and 5 can be suitably used for a semiconductor package (multi-chip module) that includes a main substrate 200 in which a first semiconductor chip 212 that generates a relatively large amount of heat is located in the center and second semiconductor chips 222 that generate a relatively small amount of heat are located in a sheet-like manner around the first semiconductor chip 212.

[0049] In such a semiconductor package, the first semiconductor chip 212 is a logic LSI such as a CPU or GPU and a memory, and the second semiconductor chip 222 is an optical element such as an optical module or an optical chip.

[0050] As shown in Figure 5, the semiconductor package includes a sub-substrate 200A on which a first semiconductor chip 212 is mounted and a sub-substrate 200B on which a second semiconductor chip 222 is mounted, which are connected to a main substrate 200 via solder balls 200C.

[0051] The semiconductor chip cooling device 100 may be sized to correspond to the respective sizes of the main substrate 200 and the sub-substrates 200A and 200B. Assuming that the main substrate 200 and the like are of general-purpose size, the semiconductor chip cooling device 100 may have a width of 70 mm to 90 mm (e.g., 80 mm) and a length of 150 mm to 160 mm (e.g., 150 mm) as shown in Fig. 4, and a thickness of 30 mm to 50 mm (e.g., 40 mm) as shown in Fig. 5.

[0052] Furthermore, the first cooling section 10 can have a horizontal width of 50 mm to 60 mm (e.g., 55 mm) and a vertical width of 55 mm to 65 mm (e.g., 60 mm) as shown in FIG. 4, and a thickness of 3 mm to 10 mm (e.g., 6 mm) as shown in FIG. 5.

[0053] Furthermore, the second cooling section 20 can have a longitudinal length of 10 mm to 30 mm (e.g., 25 mm) and a lateral length of 5 mm to 15 mm (e.g., 10 mm) as shown in FIG. 4, and a thickness of 1 mm to 30 mm (e.g., 2 mm) as shown in FIG. 5.

[0054] 4 illustrates a configuration in which the second semiconductor chips 222 and the second cooling units 20 are allocated in a 1:1 ratio, but they may also be allocated in a 2:1 ratio, for example. Just to be clear, one second cooling unit 20 that is approximately twice the size of that shown in FIG. 4 may be allocated to a pair of adjacent second semiconductor chips 222.

[0055] Furthermore, Figure 4 shows a cooling device 100 for semiconductor chips in a layout in which the first cooling section 10 is located in the center and the second cooling section 20 is located around it in a single-wafer manner, according to the layout of the main board 200, but it can also be configured in a layout in which the first cooling section 10 is located in the center and the second cooling section 20 is located around it in an L-shape or a V-shape (which means that it includes an L-shaped portion).

[0056] The cooling medium will vary depending on the heat generation temperature of the object to be cooled, but in the case of a semiconductor chip, which generally has a temperature of about 250°C, cooling water can be used at a temperature of about 25°C and a flow rate of 500 cc / min, for example, and cooling air can be used at a temperature of about 10°C and a flow rate of 800 cc / min, for example.

[0057] As described above, according to the present invention, by reviewing the configuration including the flow path formation area, it is possible to provide an inexpensive cooling device 100 for semiconductor chips that can provide cooling that is neither excessive nor insufficient.

[0058] 1 is a schematic plan view of a semiconductor chip cooling device 100 according to a first embodiment of the present invention; FIG. 2 is a cross-sectional view in the short side direction of FIG. 1; FIG. 3 is an exploded perspective view of the semiconductor chip cooling device 100 shown in FIG. 1; FIG. 4 is a plan view of a semiconductor chip cooling device 100 according to a second embodiment of the present invention; FIG. 5 is a cross-sectional view in the short side direction of FIG.

[0059] REFERENCE SIGNS LIST 10 First cooling section 12 First layer 12A Flow path section 12B Receiving section 14 Second layer 14A Flow path section 16 Third layer 16A Flow path section 16B Receiving section 20 Second cooling section 30 Connection section 100 Semiconductor chip cooling device 200 Semiconductor substrate 210 First region 212 First semiconductor chip 220 Second region 222 Second semiconductor chip

Claims

1. A cooling device comprising: a first cooling section that cools a first heating element that is mounted on a base material and generates a relatively large amount of heat; a second cooling section that cools a second heating element that is mounted on the base material and generates a relatively small amount of heat; and a connecting section that connects the first cooling section and the second cooling section in a planar manner, wherein a flow path for a cooling medium is formed in the first cooling section, and a flow path for a cooling medium is not formed in the second cooling section.

2. The cooling device according to claim 1, wherein the first cooling section and the second cooling section are made of different materials.

3. The cooling device according to claim 1, wherein the connecting portion includes an I-shaped or L-shaped portion in plan view.

4. The cooling device according to claim 1, wherein one of the cross-sectional shapes of the first cooling section and the second cooling section of the connecting section is concave and the other is convex.

5. The cooling device according to claim 1, wherein the first cooling section and the second cooling section are connected mechanically, chemically, or thermally.

6. The cooling device according to claim 1, wherein the flow path has irregularities formed thereon by mechanical or chemical processing.

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