Method and component for connecting cooling module to metal sheet

Abstract

The invention relates to a method for connecting a cooling module (4) to a metal sheet by means of a sintering method, the cooling module (4) comprising a metallic housing (5) having a coolant inlet (7), a coolant outlet (8) and a first housing side (9) and having a coolant flow structure (6) in the housing (5), and wherein the method comprises the following steps: introducing at least one ethylene glycol between the coolant flow structures (6), applying a sintering paste and sintering at pressure and temperature in order to connect the metal plate to the first housing side (9).

Description

Technical Field

[0001] The invention relates to a method for connecting a cooling module to a metal plate and a component comprising a cooling module and an electronic power module. Background Art

[0002] The power semiconductor in the power electronic device conducts high current. As a result, high temperature is generated during operation, which leads to conduction loss and thus subsequently leads to loss of thermal power. In order to avoid this, the power electronic module is connected to a high-power cooler. This cooler is composed of aluminum, AlSiC alloy or copper alloy. The power module can be directly joined, that is, for example, brazed or sintered to the surface plate of the high-power cooler. The advantage of sintering connection relative to brazing connection is that they have higher thermal conductivity, so that the cooling power of the high-power cooler can be used more effectively to cool the power electronic module and better carry away the heat of the power electronic module. However, in order to construct the sintering connection, high pressure is also used in addition to high temperature. These high pressures may damage the flow structure that is often fragile in the interior of the high-power cooler. In order to prevent this, the flow structure can be supported by corresponding components relative to the pressure to be applied. However, this is only successfully done for the cooler whose flow structure is exposed, that is, for the cooler that is not fully closed. This process is therefore very complex, since on the one hand the support must be adapted to the respective flow structure and on the other hand the cooler must also be closed before starting operation. Summary of the invention

[0003] Compared to the methods known from the prior art, the method according to the invention according to claim 1 represents a significantly simplified method which not only allows the formation of a stable sintered connection but also allows the use of a closed cooler. The provision of a supporting structure designed specifically for supporting the flow structure of the cooler is not necessary, so that by using the method according to the invention not only time but also costs can be saved.

[0004] The method according to the invention is configured to connect a cooling module to a metal plate by a sintering method. The cooling module comprises a metal housing having a coolant inlet and a coolant outlet. In addition, the housing comprises a first housing side, which should be connected to the metal plate according to the invention. A coolant flow structure is present inside the housing. The coolant flow structure is not restricted in detail and is generally used to generate eddies in the coolant flowing through the coolant flow structure so that the coolant can absorb particularly much heat. The surface of the coolant is also enlarged by the coolant flow structure. This also contributes to particularly effective heat absorption of the coolant. The coolant flow structure can be, for example, a grid structure.

[0005] The size, shape and design of the cooler are adapted to the structure to be cooled. The structure to be cooled is symbolized here by a metal plate. The metal plate can, for example, include electronic power modules such as for power electronics, such as so-called power modules, on its surface.

[0006] The method comprises the following method steps: First, at least one glycol is introduced between the coolant flow structures. This is done in particular by injecting the glycol via a coolant inlet. The coolant outlet is closed so that the glycol remains in the interior of the housing. After the coolant has been injected via the coolant inlet, the coolant inlet is also closed. The cooler is then a closed system. In other words, a conventional cooler that is provided for cooling power electronics can already be used to establish a sintered connection without an open cooler being required. More precisely, the cooler is used for the method in its ready-to-use state. The cooler is therefore closed except for the coolant inlet and the coolant outlet, wherein the coolant inlet and the coolant outlet are closed during the method according to the invention after the glycol has been introduced.

[0007] Furthermore, the method comprises the step of applying a sintering paste. The two aforementioned method steps can be carried out in this order, but also in the reverse order.

[0008] As sinter paste, a commercially customary sinter paste is used for connecting the corresponding metal of the first housing side to the metal plate. The sinter paste can be applied to the first housing side and / or to the surface of the metal plate provided for connection to the first housing side. The surface usually corresponds to the side opposite the power electronics and thus to the underside of the power electronics.

[0009] In a further method step, sintering is performed to connect the metal plate to the first housing side. This is done using pressure and, if necessary, heat, depending on the sintering paste to be used. A suitable pressure range is, for example, 10 to 20 MPa and a suitable temperature range is 180° C. to 230° C.

[0010] For process control it is important that the glycol is substantially free of water, ie apart from technically unavoidable residues, since otherwise, for example, gas bubbles may form at the temperatures used which do not allow for uniform support, so that the sintered connection would be formed inhomogeneously.

[0011] By controlling the method according to the invention, conventional coolers, which usually have very thin metal housings due to the high thermal conductivity to be provided, can be connected directly to metal plates by sintering. The glycol introduced into the coolant flow structure provides very good support without requiring high technical or cost-technical expenditure.

[0012] The dependent claims describe preferred developments of the invention.

[0013] According to an advantageous refinement, the glycol is selected from ethylene glycol, propylene glycol, butyl glycol and mixtures thereof. The aforementioned glycols have proven to be particularly stable at the sintering temperatures and sintering pressures to be used and can also be injected and flushed out very well.

[0014] As already explained above, the structure, size and shape of the cooling module are basically unlimited. The housing of the cooling module advantageously comprises two half shells connected by a brazed connection. The half shells can be designed as a lower shell and an upper shell of the cooling module, for example as deep-drawn parts, and comprise a coolant flow structure between them. The construction of a cooling module with two half shells is cost-effective, wherein additional weight caused by additional components can be saved. One of the half shells here comprises a first housing side, which is connected to the metal plate by a sintered connection.

[0015] Furthermore, it is advantageous that the cooling module is formed from aluminum, copper and stainless steel and in particular consists of aluminum due to the high thermal conductivity. To improve thermal conductivity and connection capability to metal plates, aluminum or stainless steel can have a copper or silver coating and copper can have a silver coating.

[0016] In order to provide particularly effective cooling, the cooling module advantageously comprises a turbocharger.

[0017] For reasons of good connection to the power electronics and also due to the high thermal conductivity, the metal plate is a copper plate.

[0018] Therefore, it is further advantageously provided that the metal plate is part of the electronic power module.

[0019] According to the invention, a component is also specified which comprises an electronic power module and a cooling module which are connected to one another by means of a sintered connection.

[0020] A cooling module is a cooling module with a closed metal housing having a coolant inlet and a coolant outlet. A coolant flow structure is present in the housing. The housing is formed by one or more housing parts, wherein two or more housing parts are respectively connected to each other by a soldering connection. The coolant flow structure can also be connected to the housing by one or more soldering connections. In other words, the cooling module according to the invention can also be described as a soldering connector.

[0021] The electronic power module is connected to the cooling module directly via a sintering connection to the first housing side of the cooling module. According to the invention, an "electronic power module" refers to at least one semiconductor structure (especially composed of Si / SiC), which includes a metal plate and especially a copper plate on the lower side connected to the first housing side. The copper plate can be silver-plated and formed as thin as desired. The metal plate or copper plate is used to form the sintering connection. If the sintering paste is directly connected to the semiconductor structure of the electronic power module, the semiconductor structure will be damaged and the effective power of the electronic power module will be adversely affected.

[0022] The component according to the invention is made very light and simple in structure due to the use of a brazed cooler. In particular, the first housing side connected to the electronic power module is designed to be quite thin, so that a good heat transfer to the coolant contained in the cooling module occurs. The sintered connection additionally supports a high heat conduction.

[0023] It is also advantageous if the housing and / or the coolant flow structure of the cooling module are made of aluminum, copper or high-quality steel in view of the good thermal conductivity for dissipating heat from the electronic power module to the coolant in the coolant module. Aluminum or a metal (such as steel) coated with aluminum or copper is particularly advantageously used as the material.

[0024] For particularly effective cooling of the electronic power module, the cooling module includes the turbocharger. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] An embodiment of the present invention is described in detail below with reference to the accompanying drawings. In the accompanying drawings:

[0026] Figure 1 A schematic diagram of a component according to an advantageous development is shown in section; DETAILED DESCRIPTION

[0027] The present invention is illustrated by means of an embodiment. Here, only the components important to the present invention are shown, and all other components are omitted for the sake of simplicity.

[0028] Figure 1 A component 1 according to an advantageous development is shown in detail in cross section in the diagrammatic illustration. The component 1 comprises an electronic power module 2 which comprises at least one power semiconductor. The bottom side 3 of the electronic power module 2 is formed by a copper metal plate.

[0029] In addition, the component 1 includes a cooling module 4, which has a housing 5 and a coolant flow structure 6 in the housing 5. The cooling module 4 has a closed metal housing 5, which has a coolant inlet 7 and a coolant outlet 8. The housing 5 here has two housing parts 5a and 5b, which are respectively connected to each other by a solder connection. The first housing part 5a is oriented toward the electronic power module 2. The first housing side 9 of the first housing part 5a is connected to the lower side 3 of the electronic power module 2 by means of a sintering connection 10. The lower side 3 of the electronic power module includes a metal plate or is in particular configured as a metal plate, such as a copper plate.

[0030] The cooling module 4 is designed as a brazed cooler. To form the sintered connection 10, the housing interior 11 can be filled with one or more glycols so that the first housing part 5a is supported relative to the electronic power module 2 and the coolant flow structure 6 is stabilized so that no deformations or other damages occur in the component due to the pressure applied during the sintering process. The sintered connection 10 can be obtained by applying and sintering a sintering paste.

Claims

1. A method for connecting a cooling module (4) to a metal plate by a sintering method, wherein the cooling module (4) comprises a metal housing (5) having a coolant inlet (7), a coolant outlet (8) and a first housing side (9) and a coolant flow structure (6) in the housing (5), the method comprising the following steps: - introducing at least one glycol between the coolant flow structures (6); - Apply sintering paste and - Sintering under pressure and temperature in order to connect the metal sheet to the first housing side (9).

2. The method according to claim 1, wherein the glycol is selected from ethylene glycol, propylene glycol, butyl glycol and a mixture thereof.

3. The method according to claim 1 or 2, wherein the housing (5) of the cooling module (4) comprises two half shells connected by a soldered connection. 4 . The method according to claim 1 , wherein the cooling module ( 4 ) consists of aluminum, copper or high-quality steel, and in particular consists of aluminum.

5. The method according to any of the preceding claims, wherein the cooling module (4) comprises a turbocharger.

6. The method according to any of the preceding claims, wherein the metal plate is a copper plate.

7. The method according to any of the preceding claims, wherein the metal plate is part of an electronic power module (2).

8. A component comprising an electronic power module (2) and a cooling module (4), which are connected to each other by means of a sintered connection (10), wherein the cooling module (4) comprises a closed metal housing (5) having a coolant inlet (7) and a coolant outlet (8) and a coolant flow structure (6) in the housing (5), wherein the housing comprises housing parts (5a, 5b), which are respectively connected to each other by means of a soldered connection.

9. The component according to claim 8, wherein the housing (5) and / or the coolant flow structure (6) of the cooling module (4) consists of aluminum, copper or preferably steel and in particular consists of aluminum and / or is coated with aluminum or copper.

10. The component according to claim 8 or 9, wherein the cooling module (4) comprises a turbocharger.

Images