Cooling device for power semiconductor and method for manufacturing the same

Abstract

The present invention relates to a cooling device for power semiconductors and a method for manufacturing the same. The cooling device for power semiconductors comprises: a cooler having a cooling path so that a cooling medium flows in the cooler; and an auxiliary cooling plate of a multi-layer structure bonded to the surface of the cooler in contact with the power semiconductor. The method for manufacturing the cooling device comprises the following steps: providing an auxiliary cooling plate of a multi-layer structure; providing a cooler having a cooling path so that a cooling medium flows in the cooler; and bonding the auxiliary cooling plate to the surface of the cooler in contact with the power semiconductor, wherein providing the cooler and bonding the auxiliary cooling plate are performed together in the same brazing process, so that the manufacture of the cooler and bonding the auxiliary cooling plate are performed simultaneously.

Description

[0001] CROSS REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the priority of Korean Patent Application No. 10-2019-0108126 filed on September 2, 2019, in the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to a cooling device for power semiconductors and a method of manufacturing the same. More particularly, the present invention relates to an aluminum cooling device for power semiconductors and a method of manufacturing the same, the aluminum cooling device incorporating an auxiliary cooling plate. Background Art

[0004] Batteries are installed in eco-friendly cars such as hybrid cars or electric cars to supply power to generators, drive motors, etc. The batteries are connected to power semiconductors. Power semiconductors refer to semiconductors that regulate voltage and current and increase input voltage to reduce the current applied to the system, thereby improving the performance of the drive motor. Such power semiconductors are used in inverters, etc., and have recently attracted attention as key components of eco-friendly cars.

[0005] However, the power semiconductors of the inverter of the eco-friendly car generate a large amount of heat while controlling the power. Since the energy efficiency decreases in proportion to the amount of heat generated, a cooling device is required. In other words, in order to improve the performance of the power semiconductor, a cooler is installed in the power semiconductor. The cooler cools the power semiconductor by flowing a cooling medium therein.

[0006] Generally, the cooling method may include an air cooling method or a water cooling method. However, as the amount of power required by the vehicle gradually increases, the amount of heat generated also increases. Currently, most cooling methods utilize a water cooling method. In order to improve efficiency, a method of applying a double-side cooling method is proposed.

[0007] Compared with the single-side cooling method, the double-side cooling method may have improved cooling performance. However, there is no difference between the double-side cooling method and the single-side cooling method in the performance of transferring heat from the power semiconductor to the cooler. Therefore, an auxiliary cooling plate may be applied to improve the heat transfer performance from the power semiconductor to the cooler.

[0008] The auxiliary cooling plate may have a structure in which two metal layers are combined with each other, and may include a copper layer having excellent heat transfer capability and a filler layer that bonds the plate to the aluminum cooler. In other words, the function of the copper layer is to improve heat dissipation performance using high thermal conductivity and latent heat, while the filler layer is used to bond to the aluminum cooler in brazing. According to one embodiment, the filler layer may be made of aluminum.

[0009] When the auxiliary cooling plate of the above-mentioned two-layer structure is combined with the aluminum cooler, local melting and puncture of the aluminum cooler side occur at the bonding interface between the aluminum cooler and the auxiliary cooling plate. According to the results of the bonding experiment, the interface reaction of melting and puncture occurring under various brazing temperature and time conditions may not be controlled, and thus a good bonding state may not be obtained.

[0010] The reasons for the occurrence of melting and perforation are as follows: the process reaction occurs at a temperature of approximately 548°C, which is much lower than the melting points of copper and aluminum respectively, and when the process reaction occurs during the brazing bonding operation between the aluminum cooler and the auxiliary cooling plate, the aluminum cooler side forming the bonding interface melts.

[0011] The information included in this background section is merely intended to enhance understanding of the general background of the invention and should not be taken as an acknowledgment or any form of suggestion that this information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0012] The present invention is directed to solving the above problems associated with the related art. An object of the present invention is to prevent the interface reaction that occurs when the auxiliary cooling plate having a two-layer structure consisting of a copper layer and a filler layer is brazed to an aluminum cooler.

[0013] The technical objectives to be achieved by the present invention are not limited to the above-mentioned technical objectives, and other technical objectives not mentioned above will be clearly understood by those skilled in the art from the following detailed description of the present invention.

[0014] According to one aspect of the present invention, a cooling device for a power semiconductor includes: a cooler having a cooling path so that a cooling medium flows in the cooler; and an auxiliary cooling plate of a multi-layer structure bonded to a surface of the cooler that contacts the power semiconductor.

[0015] The cooler may be made of aluminum, and the auxiliary cooling plate may have a multi-layer structure, comprising: a copper layer; a reaction prevention layer disposed on the copper layer to prevent an interface reaction between a copper component of the copper layer and an aluminum component of the cooler; and a filler layer disposed on the reaction prevention layer to bond to the aluminum cooler.

[0016] According to another aspect of the present invention, a method for manufacturing a cooling device for power semiconductors includes the following steps: providing an auxiliary cooling plate of a multilayer structure; providing a cooler, the cooler having a cooling path so that a cooling medium flows in the cooler; and bonding the auxiliary cooling plate to a surface of the cooler that is in contact with the power semiconductor, wherein providing the cooler and bonding the auxiliary cooling plate can be performed together in the same brazing process, so that the manufacture of the cooler and bonding the auxiliary cooling plate can be performed simultaneously.

[0017] Providing the cooler may be performed through an aluminum brazing process, and providing the auxiliary cooling plate may include the following steps: providing a copper layer; forming a reaction prevention layer on the copper layer to prevent an interface reaction between the copper component of the copper layer and the aluminum component of the cooler; and forming a filler layer on the reaction prevention layer, the filler layer being bonded to the aluminum cooler.

[0018] The reaction preventing layer may be made of a metal that causes a phase change reaction temperature when dissimilar metal components of the reaction preventing layer contact each other to be higher than a phase change reaction temperature when a copper component of the copper layer contacts an aluminum component of the aluminum cooler.

[0019] The metal component of the reaction preventing layer may be steel or nickel (Ni). BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Hereinafter, the accompanying drawings are intended to help understand the present invention, and together with the specific embodiments, provide embodiments of the present invention. However, the technical features of the present invention are not limited to specific drawings, and the features disclosed in the various drawings are combined with each other to form new embodiments.

[0021] Figure 1A and Figure 1B is a schematic diagram showing a cooling method of air cooling and water cooling types for a heat generating element according to the related art;

[0022] Figure 1C is a schematic diagram showing a double-side cooling method of a water cooling type according to the related art;

[0023] Figure 2 is a schematic diagram showing an inverter structure according to an exemplary embodiment of the present invention, in which a power semiconductor is assembled with a cooling device incorporating an auxiliary cooling plate;

[0024] Figure 3 is a flow chart illustrating an assembly process of an inverter including a cooling device for a power semiconductor according to an exemplary embodiment of the present invention;

[0025] Figure 4is a schematic diagram illustrating a three-layered structure of an auxiliary cooling plate according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0026] Various exemplary embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention is not limited to those exemplary embodiments. The same reference numerals in the accompanying drawings represent components that perform substantially the same functions.

[0027] The purpose and effect of the present invention can be naturally or more clearly understood through the following description, but the purpose and effect of the present invention are not limited to the following description. In addition, in the description of the present invention, if it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the subject matter of the present invention, its detailed description will be omitted.

[0028] Figure 1A and Figure 1B is a schematic diagram showing a cooling method of air cooling and water cooling types for a heat generating element according to the related art.

[0029] according to Figure 1A The air cooling type cooling method shown in FIG. 1 cools a heat generating element 120 such as a power semiconductor by circulating air using a heat sink 110 and a fan 100. Figure 1B In the cooling method of the water cooling type shown in , cooling water circulating in the cooler 130 absorbs heat generated from the heat generating element 120 such as a power semiconductor and then releases the heat to the atmosphere, thereby cooling the heat generating element 120.

[0030] Figure 1C is a schematic diagram illustrating a double-side cooling method of a water cooling type according to the related art. Figure 1B A one-side cooling method of water cooling type is shown. In order to improve the cooling efficiency of such a one-side cooling method, an application Figure 1C Double-sided cooling method. Figure 1C The double-sided cooling method is a method of placing the cooler 130 on both sides of the heat generating element 120 such as a power semiconductor. For example, when the double-sided cooling method using an aluminum cooler is applied, the cooling performance can be improved by about 60% compared to the case of using the single-sided cooling method.

[0031] However, the improvement of cooling performance is achieved by simply changing the cooling method from the single-side cooling method to the double-side cooling method. There is no difference in the performance of transferring heat from the power semiconductor to the cooling device between the single-side cooling method and the double-side cooling method. In view of this, the present invention proposes a method for improving cooling performance by maximizing the heat transfer effect from the power semiconductor to the cooling device.

[0032] According to an exemplary embodiment of the present invention, Figure 2 Schematically shows an inverter structure formed by assembling a power semiconductor and a cooling device combined with an auxiliary cooling plate. Figure 2 The inverter structure according to the exemplary embodiment of the present invention is characterized in that the auxiliary cooling plate 210 is coupled to the cooler 230 having a cooling path so that the cooling medium flows. According to the exemplary embodiment of the present invention, the cooler 230 may be an aluminum cooler. Figure 2 As shown, the auxiliary cooling plate 210 may be coupled to a surface of the cooler 230 that will come into contact with the power semiconductor 220. Thus, according to an exemplary embodiment of the present invention, the cooler 230 coupled with the auxiliary cooling plate 210 (in other words, a cooling device for a power semiconductor according to an embodiment of the present invention) is assembled with the power semiconductor 220, thereby forming an inverter.

[0033] Figure 3 It is shown as Figure 2 Flow chart of an assembly process of an inverter including a cooling device for power semiconductors according to an exemplary embodiment of the present invention shown in FIG. In this regard, an aluminum cooler is manufactured by a brazing method according to a conventional inverter assembly process. The aluminum cooler manufactured in this manner is assembled with the power semiconductors, thereby completing the inverter.

[0034] According to an exemplary embodiment of the present invention, the auxiliary cooling plate ( Figure 3 Part "a") can be applied to the conventional process of manufacturing aluminum coolers. Figure 3 As shown, the auxiliary cooling plate 210 may be composed of a copper layer, a reaction prevention layer and a filler layer. The structure of such an auxiliary cooling plate 210 will be described in detail later.

[0035] In addition, according to an exemplary embodiment of the present invention, a brazing bond can be used to firmly bond the above-mentioned auxiliary cooling plate a to the cooler. According to the embodiment, the cooler may include an aluminum cooler component b, and in step S310, the brazing bond may be an aluminum brazing bond. The brazing bond between the auxiliary cooling plate a and the cooler is achieved by assembling the auxiliary cooling plate a and the cooler together in a cooler brazing operation without using a separate process. Therefore, according to an exemplary embodiment of the present invention, in step S320, the cooler combined with the auxiliary cooling plate does not require an additional process in manufacturing. In step S330, the cooling device according to the exemplary embodiment of the present invention (in other words, the cooler combined with the auxiliary cooling plate) thus manufactured is assembled with a power semiconductor to constitute an inverter.

[0036] As described above, in order to maximize the heat transfer effect from the power semiconductor to the cooler in the present invention, a method of applying an auxiliary cooling plate between the cooler and the power semiconductor is used. Hereinafter, the configuration and function of the auxiliary cooling plate according to an exemplary embodiment of the present invention will be described in detail.

[0037] The three-layer structure of the auxiliary cooling plate according to the exemplary embodiment of the present invention is a structure composed of a plurality of metal layers, and mainly includes a copper layer 520 having excellent heat transfer capability and a filler layer 510 bonded to an aluminum cooler. A reaction prevention layer 500 for preventing the above-mentioned interface reaction is further added between the copper layer 520 and the filler layer 510.

[0038] The reaction preventing layer 500 is made of a material that does not cause a process reaction with copper and aluminum. The reaction preventing layer is made of a metal that makes the phase change reaction temperature when dissimilar metals (i.e., the metal component of the reaction preventing layer 500 and another metal component) contact each other higher than the phase change reaction temperature when the copper component of the copper layer 520 contacts the aluminum component of the aluminum cooler.

[0039] According to the embodiment, the reaction preventing layer 500 may be made of steel such that the interface reaction temperature with the copper component of the copper layer 520 or the aluminum component of the aluminum cooler is about 1100° C. or higher, but is not limited thereto. In addition, according to an exemplary embodiment of the present invention, the reaction preventing layer 500 may be made of nickel (Ni), but is not limited thereto. In addition, according to an exemplary embodiment of the present invention, Figure 4 The auxiliary cooling plate of the three-layer structure shown in FIG. 1 may be made of a clad material, but is not limited thereto.

[0040] If the exemplary embodiment according to the present invention is used Figure 4 The three-layer auxiliary cooling plate shown in the figure can solve the problem of interface reaction that may occur when using a two-layer auxiliary cooling plate.

[0041] Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

[0042] The cooling device for a power semiconductor according to the present invention has an advantage in that it prevents an interface reaction from occurring when the cooling device having a two-layer structure of a copper layer and a filler layer is brazed to an aluminum cooler.

[0043] Effects achieved by the present invention are not limited to the above-mentioned effects, and those skilled in the art will easily understand other effects not mentioned above based on the detailed description of the present invention.

Claims

1. A cooling device for a power semiconductor, comprising: a cooler having a cooling path so that a cooling medium flows in the cooler; as well as An auxiliary cooling plate of a multi-layer structure bonded to a surface of the cooler in contact with the power semiconductor; Wherein, the cooler is made of aluminum, The auxiliary cooling plate has a multi-layer structure, and the multi-layer structure comprises: Copper layer; A reaction preventing layer provided on the copper layer to prevent an interface reaction between a copper component of the copper layer and an aluminum component of the cooler; and a filler layer disposed on the reaction preventing layer to be bonded to the aluminum cooler; The reaction preventing layer is made of a metal which makes the phase change reaction temperature of the different metal components of the reaction preventing layer when they contact each other higher than the phase change reaction temperature of the copper component of the copper layer when they contact the aluminum component of the aluminum cooler.

2. The cooling device for power semiconductor according to claim 1, wherein: The metal component of the reaction prevention layer is steel.

3. The cooling device for power semiconductor according to claim 1, wherein: The metal component of the reaction prevention layer is nickel.

4. A method for manufacturing a cooling device for a power semiconductor, comprising the following steps: Providing an auxiliary cooling plate of a multi-layer structure; providing a cooler having a cooling path so that a cooling medium flows in the cooler; and bonding an auxiliary cooling plate to a surface of the cooler that makes contact with the power semiconductor, in, Providing the cooler and the auxiliary cooling plate are bonded together in the same brazing process so that the cooler is manufactured simultaneously with the auxiliary cooling plate; Wherein, the providing of the cooler is carried out by an aluminum brazing process, Providing an auxiliary cooling plate includes the following steps: Providing a copper layer; forming a reaction preventing layer on the copper layer to prevent an interface reaction between a copper component of the copper layer and an aluminum component of the cooler; and forming a filler layer on the reaction preventing layer, the filler layer being bonded to the aluminum cooler; The reaction preventing layer is made of a metal which makes the phase change reaction temperature of the different metal components of the reaction preventing layer when they contact each other higher than the phase change reaction temperature of the copper component of the copper layer when they contact the aluminum component of the aluminum cooler.

5. The method according to claim 4, wherein: The metal component of the reaction prevention layer is steel.

6. The method according to claim 4, wherein: The metal component of the reaction prevention layer is nickel.

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