Cooler through which fluid can flow for cooling power module

Abstract

The invention relates to a cooler (100) through which a fluid can flow for cooling a power module (208) comprising a power substrate. A cooler (101) through which a fluid can flow comprises a first metal part (101), a second metal part (102) and a cooling structure (1). The first metal part (101) and the second metal part (102) are connected to each other by means of a brazing process and define a cooling channel (111) through which a fluid can flow and in which the cooling structure (1) is arranged. The first metal part (101) has a receiving region (109), to which the power module (208) can be fastened. The first metal member (101) is configured from a metal material having an expansion coefficient greater than that of the power substrate (208). Furthermore, the invention relates to a power electronics assembly (1000) having such a cooler (100) and a power module (200).

Description

Technical Field

[0001] The invention relates to a fluid-permeable cooler for cooling a power module, the power module having a power substrate. The invention also relates to a power electronics assembly, the power electronics assembly having: a power module including a power substrate and such a fluid-permeable cooler. The power electronics assembly can in particular include a plurality of power modules cooled by means of the cooler. Background Art

[0002] The power semiconductors of the power modules in power electronics conduct high currents. Together with the switching losses, the resulting conduction losses lead to high thermal losses that must be dissipated over a very small surface. The maximum permissible semiconductor temperature is critical for failure, so it is crucial to minimize the thermal resistance between the semiconductor and the coolant. For efficient cooling, the power substrate is used on a cooler through which a fluid can flow. Summary of the invention

[0003] The advantages of the fluid-permeable cooler for cooling a power module including a power substrate according to the present invention are the flexible design of the cooler and good cooling power. This is achieved by a fluid-permeable cooler, which is used to cool a power module with a power substrate, and the cooler includes a first metal component, a second metal component and a cooling structure. The first metal component and the second metal component are connected to each other by means of a brazing process. In other words, the first metal component and the second metal component are brazed together. The first metal component and the second metal component define a cooling channel, which can be traversed by a fluid and in which a cooling structure is arranged. The first metal component has a receiving area, and the power module can be fastened at / on the receiving area. The first metal component is constructed of the following metal material, the expansion coefficient of the metal material is greater than the expansion coefficient of the power substrate, so that the expansion caused by heat of the first metal component is reduced. Before the brazing process, the first metal component can be a metal component pre-plated with a solder layer, especially a barrel-plated metal component in an advantageous manner. Correspondingly, the second metal component can be a metal component pre-plated with a solder layer, especially a barrel-plated metal component before the brazing process in an advantageous manner. It is also possible that, as an alternative or in addition to the pre-plating of the first metal component and / or the second metal component, the connection between the first metal component and the second metal component is realized by means of at least one brazing foil or a brazing paste. In particular, the aforementioned expansion coefficient can be a linear expansion coefficient. The power substrate preferably comprises a carrier plate and at least one conductor track. The expansion coefficient of the first metal component can be, for example, at least twice, in particular at least three times, greater than the expansion coefficient of the power substrate.

[0004] The dependent claims indicate preferred developments of the invention.

[0005] The power substrate and the first metal component preferably have different yield points. The yield point is a material characteristic variable and indicates the mechanical stress within which the material can deform elastically.

[0006] The metallic material can preferably be a pure metal or a metal alloy.

[0007] Preferably, the metal material of the first metal component has a yield strength after the brazing process, which is greater than 30 N / mm 2 In other words, the metal material of the first metal component preferably has a resistance greater than 30 N / mm in its brazed state. 2 Yield limit. That is, the metal material of the first metal component has the mentioned yield limit after its heat treatment caused by the brazing process. It is thus ensured that in the event of bending of the first metal component due to different expansion coefficients of the first metal component and the power substrate, the first metal component deforms only within the elastic range below the yield limit. At the starting temperature, the first metal component returns to its original state. This prevents plastic deformation, in particular bending, of the first metal component, in particular in the region of the power substrate, which would otherwise occur in the event of heating / cooling due to a more drastic expansion / contraction of the first metal component than the power substrate and would continuously increase in the event of cyclic loading.

[0008] In particular, the metallic material can have an upper yield point and a lower yield point, wherein in this case the yield point is greater than 30 N / mm 2 The yield limit corresponds to the upper yield limit.

[0009] When the heat flux is less than 600000W / m 2 and / or the temperature difference between the starting temperature and the final temperature is at least 120° C., it can be advantageously avoided that the first metal component (the metal material of the first metal component has a greater than 30 N / mm 2 The yield limit of plastic deformation.

[0010] The thermal conductivity of the metal material of the first metal component is greater than 190 W / (m*K), preferably greater than 200 W / (m*K). Therefore, the heat generated by the power module can be efficiently transferred from the first metal component to the fluid flowing through the cooling channel.

[0011] The first metal component and the second metal component are preferably connected to each other by means of a brazing process. That is to say, there is preferably a connecting brazing material layer between the first metal component and the second metal component. That is to say, the first metal component and the second metal component are preferably brazable.

[0012] Advantageously, the cooling structure can contact the first metal component and / or the second metal component. In particular, the cooling structure can be connected to the first metal component and / or the second metal component in an advantageous manner by means of a brazing process. The connecting brazing material layer that connects the first metal component and the second metal component to one another can preferably also connect the cooling structure to the first metal component and / or the second metal component.

[0013] According to an advantageous embodiment of the invention, the metal material of the first metal component includes magnesium (that is, the metal material is a metal alloy), wherein the second metal component is constructed from a metal material that does not include magnesium. In this case, the second metal component can be a pure metal component or a metal alloy. In this embodiment of the invention, the mass percentage of magnesium in the mass of the first metal component is less than 1%.

[0014] According to an alternative design of the present invention, the metal material of the first metal component includes magnesium, wherein the second metal component is constructed of a metal material including magnesium. That is, the metal material of the first metal component and the metal material of the second metal component are both metal alloys and each include magnesium. In an advantageous manner, the mass percentage of magnesium in the mass of the first metal component and in the mass of the second metal component is less than 1% in total. Particularly preferably, the mass percentage of magnesium in each of the first metal component and the second metal component can be less than 0.5% of the mass of the corresponding metal component.

[0015] If the first metal component / the two metal components comprise magnesium, the first metal component / the two metal components can be connected to one another in a simple manner by means of a brazing process by means of a given mass percentage.

[0016] Preferably, the metal material of the first metal component is an aluminum alloy, wherein the metal material of the first metal component has a material state O after the brazing process. In other words, the metal material of the first metal component has a material state O in the brazed state of the first metal component. Material state O can represent the result that the properties required for the soft annealed state are obtained by the hot forming method.

[0017] In the context of the present invention, cooling structures are preferably understood to be structures which increase the surface area, guide the flow and increase the heat transfer.

[0018] The cooling structure can preferably include a cooling fin structure and / or a pin structure (cooling pin structure). It is also conceivable that, as an alternative or in addition, the cooling structure also has a cooling structure element or a plurality of cooling structure elements, which have a shape different from the cooling fins or the pins. It is particularly feasible that the cooling structure has a plurality of cooling structure elements of different shapes. It is then possible, for example, for the cooling structure to have a cooling fin and a pin, or to have a plurality of cooling fins and a plurality of pins. Within the scope of the present invention, cooling fins and pins can be respectively referred to as cooling structure elements in particular.

[0019] The cooling fin arrangement can preferably comprise (only) one cooling fin or a plurality of cooling fins, which are preferably arranged continuously along the throughflow direction. The throughflow direction corresponds in particular to the main flow direction of the fluid used as coolant, which flows through the through-opening formed by the cooling fin(s). The main flow direction is in particular the direction along which the fluid mainly flows, that is to say the direction along which the velocity component of the fluid is greater than the velocity component of the fluid in a direction perpendicular to the main flow direction. The main flow direction preferably corresponds to the direction of introduction of the fluid into the cooler through which the fluid can flow.

[0020] The cooling fin structure can in particular also be referred to as a turbulator. The cooling fins are preferably formed by a wave profile which is repeated periodically along a repetition direction.

[0021] The cooling structure is preferably at least partially, in particular completely, made of and / or coated with a material having a thermal conductivity coefficient of more than 200 W / (m·K). Advantageously, the cooling structure can be at least partially, in particular completely, made of or coated with aluminum.

[0022] These embodiments relate in particular to cooling structure elements of the cooling structure.

[0023] Within the scope of the present invention, a fluid that can flow through a cooler can in particular also be referred to as cooling fluid.

[0024] The invention also relates to a power electronics assembly comprising a power module with a power substrate and the aforementioned fluid-permeable cooler. The power module is fastened at / on a receiving region of a first metal part of the fluid-permeable cooler by means of the power substrate.

[0025] The power baseplate can preferably be constructed from copper and / or ceramic (AMB / DBC power baseplate; AMB: active metal braze; DBG: direct copper bonding).

[0026] For the purpose of low thermal resistance between the power substrate and the cooler, in particular the first metal component, the power substrate can preferably be joined to the cooler, in particular the first metal component, by means of a soldering process, optionally also by means of a sintering process. That is, the power module is preferably joined to the cooler or the first metal component through which a fluid can flow, by means of a layer produced by a soldering process or a sintering process, which thus corresponds to a solder layer or a sintered layer.

[0027] The power module preferably comprises one or more power semiconductors. The power semiconductors generate heat during operation of the power module, which heat can be dissipated by a cooler. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Embodiments of the present invention are described in detail below with reference to the accompanying drawings. In the accompanying drawings:

[0029] Figure 1 A schematically simplified sectional view of a power module according to the invention is shown together with a cooler through which a fluid can flow according to an exemplary embodiment of the invention. DETAILED DESCRIPTION

[0030] Reference below Figure 1 A power electronics assembly 1000 according to the present invention is described, which has a power module (power electronics component unit) 200 and a cooler 100 through which a fluid can flow according to an exemplary embodiment of the present invention. It is also possible for the power electronics assembly 1000 to include a plurality of power modules 200 .

[0031] As from Figure 1 As can be seen, the power module 200 has a carrier plate 204, conductor tracks 203, 205 and a power semiconductor 201. The conductor tracks 203, 205 are in particular designed as copper conductor tracks, wherein the carrier plate 204 is preferably designed from ceramic.

[0032] The power semiconductor 201 is applied to the conductor track 203 by means of a layer 202. In this case, the layer 202 is designed in particular as a solder layer or a sintering layer.

[0033] The conductor tracks 203, 205 together with the carrier plate 204 form a power substrate 208. The power substrate 208 and thus the power module 200 are joined to a fluid-permeable cooler 100, in particular to a receiving region 109 of the first metal part 101 of the cooler 100, by means of a layer 206 produced by a soldering process or a sintering process (the layer thus corresponds to a solder layer or a sintered layer).

[0034] The fluid-permeable cooler 100 further comprises a second metal component 102, which is connected to the first metal component 101 by means of a soldering process. In other words, the first metal component 101 and the second metal component 102 are soldered together. In particular, the soldering process is a brazing process, so that the first metal component 101 and the second metal component 102 are connected by means of a connecting brazing material layer 103. In particular, the two metal components 101, 102 are designed as sheet metal parts.

[0035] In addition, by Figure 1 It can be seen that the first metal component 101 is the upper component of the housing 110 and the second metal component 102 is the lower component of the housing. The first metal component 101 faces the power module 200, wherein the second metal component 102 faces away from the power module 200. In addition, in the present embodiment, the first metal component 101 is plate-shaped, wherein the second metal component 102 has a plate-shaped area and a trapezoidal area in cross section. However, it is also possible that the first metal component 101 and the second metal component 102 have other shapes. The second metal component 102 can be manufactured in an advantageous manner by a deep drawing process.

[0036] An intermediate layer 107 is advantageously located between the layer 206 and the cooler 100, in particular between the layer 206 and the first metal component 101, which intermediate layer is fixedly connected to the first metal component 101 and allows wetting of the layer 206. The intermediate layer 107 is an optional feature of the power electronics component 1000 and can be considered in particular either as a separate component or as a component of the cooler 100.

[0037] An inner cavity is defined by the first metal component 101 and the second metal component 102 which form the housing 110 of the cooler 100 in the joined state, and the inner cavity serves as a cooling channel 111 of the cooler 100. In other words, the metal components 101, 102 connected to each other define the cooling channel 111 of the cooler 100. The cooling channel 111 is closed in an advantageous manner, wherein an inlet and an outlet for a fluid are arranged at the housing of the cooler 100.

[0038] A cooling structure 1 is arranged in the cooling channel 111 and serves as a surface-enlarging, flow-guiding and heat-transfer-enhancing structure for a fluid serving as a coolant. The cooling structure 1 is connected to the first metal component 101 and the second metal component 102 by means of a connecting brazing material layer 103 .

[0039] The cooling structure 1 comprises in particular a cooling fin structure or a cooling fin structure. For this purpose, the cooling fin structure has cooling fins 10, which extend in the direction of the length of the cooling channel 111 or the flow direction 500 of the fluid. In this case, the cooling structure 1 therefore corresponds to the cooling fins 10. The flow direction 500 corresponds in particular to the main flow direction of the fluid used as a coolant.

[0040] In addition, if Figure 1 As shown, the cooling fin 10 is formed by a wave profile that repeats periodically along the repetition direction 501. Through the cooling fin 10, a through-opening 14 is formed, through which a fluid can flow. The cooling fin 10 is preferably made of a material and / or coated with a material whose thermal conductivity coefficient is greater than 200 W / (m·K). The cooling fin 10 can advantageously be made of aluminum or coated with aluminum. It is also possible to use other heat-conducting materials for the cooling fin 10 and / or its layers.

[0041] Although the cooling fin structure has only one cooling fin 10 in the present exemplary embodiment, it is also possible for the cooling fin structure to have a plurality of cooling fins 10 which are arranged successively to one another, in particular along the throughflow direction 500 of the fluid.

[0042] The first metal component 101 is constructed of a metal material whose expansion coefficient is greater than that of the power substrate 200, so that the thermal expansion of the first metal component 101 is reduced. The metal material of the first metal component 101 is a metal alloy, preferably an aluminum alloy. However, it is also possible to use a pure metal as the metal material of the first metal component 101.

[0043] In case of thermal expansion / contraction, the expansion / contraction of the first metal component 101 is prevented by securing the power substrate 208 at / on the receiving area 109 of the first metal component 101 thereby causing the first metal component 101 and thus the cooler 100 to bend due to the different thermal expansion coefficients of these components.

[0044] In order to avoid plastic deformation due to bending, a high-strength metal alloy, preferably a high-strength aluminum alloy, is used as the metal material of the first metal component 101, so that the first metal component 101 deforms only in the elastic range below the yield strength of the metal alloy when bending is caused by heat. When the first metal component 101 is no longer subject to expansion / contraction, that is, at the starting temperature, the first metal component 101 returns to its original state. For the metal material of the first metal component 101, the yield strength of the metal alloy is greater than 30N / mm 2It should be noted that the yield strength of the metal alloy is the yield strength that the metal alloy has after the brazing process, that is, after the heat treatment of the first metal component 101 by the brazing process. Advantageously, the first metal component 101 is designed based on the yield strength of the metal alloy to be able to withstand a heat flux of less than 600,000 W / m only in the elastic range. 2 and / or the deformation is carried out with a temperature difference of at least 120°C between the starting temperature and the final temperature.

[0045] If the metal alloy of the first metal component 101 is an aluminum alloy, the metal alloy advantageously has a material state O after the brazing process. In other words, the aluminum alloy of the first metal component 101 advantageously has a material state O in the brazed state of the first metal component 101 .

[0046] The power substrate 208 and the first metal component 101 preferably have different yield limits.

[0047] The thermal conductivity of the metal alloy of the first metal component 101 is greater than 190 W / (m*K), preferably greater than 200 W / (m*K). Therefore, the heat generated by the power module 200 can be efficiently transferred from the first metal component 101 to the fluid flowing through the cooling channel 111 and discharged by the fluid, thereby cooling the power module 200.

[0048] The second metal component 102 is also advantageously constructed from an aluminum alloy. In this case, the two metal components 101, 102 can include magnesium. In order to be able to connect the two metal components 101, 102 to one another by means of a brazing process, the mass percentage of magnesium from the mass of the first metal component 101 and from the mass of the second metal component 102 totals less than 1%. In particular, the mass percentage of magnesium in the first metal component 101 can be less than 0.5% of the mass of the first metal component 101, wherein the mass percentage of magnesium in the second metal component can be less than 0.5% of the mass of the second metal component 102.

[0049] In order to produce the cooler 100 through which a fluid can flow, the first metal component 101 , the second metal component 102 and the cooling structure 1 can preferably be joined together in the same production step by means of a brazing process.

Claims

1. A cooler (100) through which a fluid can flow for cooling a power module (200), the power module comprising a power substrate (208), wherein: The cooler (101) capable of fluid flow comprises: A first metal component (101); a second metal component (102), wherein the first metal component (101) and the second metal component (102) are connected to each other by means of a brazing process and define a cooling channel (111) through which a fluid can flow; and A cooling structure (1) arranged in the cooling channel (111), wherein the first metal component (101) has a receiving area (109) to which the power module (208) can be fastened, and wherein the first metal component (101) is constructed of a metal material having a coefficient of expansion greater than a coefficient of expansion of the power substrate (208).

2. The cooler (100) through which a fluid can flow according to claim 1, wherein: The metal material of the first metal component (101) has a thermal conductivity greater than 30 N / mm after the brazing process. 2 The yield limit.

3. The cooler (100) through which a fluid can flow according to any one of the preceding claims, wherein: The thermal conductivity of the metal material of the first metal component (101) is greater than 190 W / (m*K), preferably greater than 200 W / (m*K).

4. The cooler (100) through which a fluid can flow according to any one of the preceding claims, wherein: The first metal component (101) and the second metal component (102) are connected to each other by means of a brazing process.

5. A cooler (100) through which a fluid can flow according to any one of the preceding claims, in, The metal material of the first metal component (101) includes magnesium, and the second metal component is constructed of a metal material that does not include magnesium, wherein the mass percentage of magnesium in the mass of the first metal component (101) is less than 1%, or The metal material of the first metal component (101) includes magnesium, and the second metal component is constructed of a metal material including magnesium, wherein the mass percentage of magnesium in the mass of the first metal component (101) and in the mass of the second metal component (102) is less than 1% in total.

6. The cooler (100) through which a fluid can flow according to any one of the preceding claims, wherein: The metal material of the first metal component (101) is an aluminum alloy, which has a material state O after the brazing process.

7. The cooler (100) through which a fluid can flow according to any one of the preceding claims, wherein: The metal material of the first metal component (101) is a metal alloy.

8. The cooler (100) through which a fluid can flow according to any one of claims 1 to 4, wherein: The metal material of the first metal component (101) is pure metal.

9. A power electronics assembly (1000) comprising a power module (200) having a power substrate (208) and a cooler (100) through which a fluid can flow according to any one of the preceding claims, wherein: The power module (200) is fastened by means of the power substrate (208) to a receiving region (109) of a first metal part (101) of the cooler (100) through which a fluid can flow.

10. The power electronic device assembly (1000) according to claim 9, wherein: The power substrate (100) is made of copper and / or ceramic.

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