Press-fit power devices

Abstract

This application relates to the field of semiconductor device technology, specifically providing a press-fit power device aimed at solving the problem of improving the heat dissipation performance of press-fit power devices. To this end, the press-fit power device of this application includes a housing; multiple sub-modules disposed within the housing; and multiple positioning frames disposed within the housing and corresponding one-to-one with each sub-module, with each sub-module located within a positioning frame; wherein the positioning frames are made of a solid-liquid phase change material, and the inner surface of the positioning frames is attached to the sub-modules. This application integrates positioning frames made of phase change material inside the power device, thereby improving the heat dissipation performance of the device without altering the structural composition of the internal functional components.

Description

Technical Field

[0001] This application relates to the field of semiconductor device technology, specifically providing a press-fit power device. Background Technology

[0002] IGBT power devices mainly include welded devices and press-fit devices. Press-fit devices are widely used in DC power transmission due to their advantages such as double-sided heat dissipation, easy series connection, and high reliability.

[0003] Press-fit power devices are typically formed by multiple sub-modules connected in parallel. During operation, these devices generate heat, making heat dissipation a critical concern. Some related technologies employ spraying high thermal conductivity interface materials to improve thermal conductivity. However, under short-term overload conditions, the sudden increase in load causes a rapid increase in heat generation on the device surface. Due to the presence of thermal capacity, the device is difficult to cool in time. Therefore, the above methods have limited cooling effect on press-fit power devices, and the problem of poor heat dissipation persists.

[0004] Accordingly, a new technical solution is needed in this field to solve the above problems. Utility Model Content

[0005] This application aims to solve the aforementioned technical problem, namely, how to improve the heat dissipation performance of press-fit power devices.

[0006] In a first aspect, this application provides a press-fit power device comprising:

[0007] outer shell;

[0008] Multiple sub-modules are disposed within the outer casing;

[0009] Multiple positioning frames are disposed within the outer shell and correspond one-to-one with the sub-modules, with each sub-module located within the positioning frame;

[0010] The positioning frame is made of a solid-liquid phase change material, and the inner surface of the positioning frame is attached to the sub-module.

[0011] In one technical solution of the above-mentioned press-fit power device, the outer surfaces of adjacent positioning frames are in contact with each other.

[0012] In one technical solution of the above-mentioned press-fit power device, the inner diameter of the positioning frame gradually decreases along the press-fit direction of the submodule to form multiple steps that are adapted to the various functional components of the submodule.

[0013] In one technical solution of the above-mentioned press-fit power device, there is a gap between each step and the corresponding functional component.

[0014] In one technical solution of the above-mentioned press-fit power device, the positioning frame is an integrally formed structure.

[0015] In one technical solution of the above-mentioned press-fit power device, a PCB is provided in the housing, and the sub-module includes a boss, an emitter molybdenum sheet, a chip and a collector molybdenum sheet arranged sequentially from the PCB along the axial direction of the sub-module. The diameters of the boss, the emitter molybdenum sheet, the chip and the collector molybdenum sheet increase sequentially to adapt to the various steps of the positioning frame.

[0016] The submodule also includes a probe, one end of which is connected to the chip and the other end of which is connected to the PCB.

[0017] In one technical solution of the above-mentioned press-fit power device, the housing includes a base, a support frame, and a cover plate, wherein the support frame is located between the base and the cover plate;

[0018] The PCB is mounted on the base, the positioning frame is mounted on the support frame, and the cover plate covers each of the sub-modules and abuts against the molybdenum collector sheet.

[0019] In one technical solution of the above-mentioned press-fit power device, the positioning frame has a receiving hole, the probe is located in the receiving hole, one end of the probe extends out of the receiving hole and connects to the chip, and the other end passes through the support frame and connects to the PCB.

[0020] In one technical solution of the above-mentioned press-fit power device, an elastic element is provided between the boss and the bottom of the housing.

[0021] In one technical solution of the above-mentioned press-fit power device, multiple sub-modules are connected in parallel.

[0022] By employing the aforementioned technical solution, this application uses a phase change material for the positioning frame. In the event of unexpected conditions such as power grid failures, if the submodule experiences a sudden increase in heat generation, the positioning frame absorbs the heat and undergoes a phase change to become liquid, thereby carrying away some of the heat. This reduces the probability of damage to the chip within the submodule due to its temperature exceeding its maximum junction temperature, thus improving the heat dissipation efficiency of the power device. In other words, the positioning frame of this application not only serves to position the submodule during the power device packaging process but also assists in heat dissipation during the power device's operation. Therefore, by integrating the positioning frame inside the power device, this application can improve the device's heat dissipation performance without altering the structural composition of the internal functional components.

[0023] Furthermore, in the solid state, adjacent positioning frames in this application fit together, and the heat generated by the submodule can be transferred laterally through the positioning frames, which helps to improve the temperature uniformity of various regions within the entire device, reduce device deformation and warping caused by thermal expansion, and improve the reliability of the device. Attached Figure Description

[0024] The preferred embodiments of this application are described below with reference to the accompanying drawings, in which:

[0025] Figure 1 This is a schematic diagram of a crimped power device according to an embodiment of this application;

[0026] Figure 2 This is a three-dimensional exploded view of a submodule of a crimped power device according to an embodiment of this application;

[0027] Figure 3 This is a partial cross-sectional view of a crimped power device according to an embodiment of this application;

[0028] Figure 4 This is a schematic diagram of a positioning frame according to an embodiment of this application;

[0029] Figure 5 This is a partial cross-sectional view of a submodule according to an embodiment of this application.

[0030] In the figure, the reference numerals refer to the following:

[0031] 1. Outer shell; 100. Gap; 11. Base; 12. Support frame; 13. Cover plate; 2. Sub-module; 21. Boss; 22. Emitter molybdenum sheet; 23. Chip; 24. Collector molybdenum sheet; 25. Probe; 3. Positioning frame; 31. Accommodation hole; 4. PCB; 5. Insulating board. Detailed Implementation

[0032] Preferred embodiments of this application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of this application and are not intended to limit the scope of protection of this application. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.

[0033] It should be noted that in the description of this application, terms such as "upper," "lower," "left," "right," "inner," and "outer," which indicate direction or positional relationship, are based on the direction or positional relationship shown in the accompanying drawings. These terms are used merely for ease of description and do not indicate or imply that the relevant device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, ordinal numbers such as "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0034] Furthermore, it should be noted that, in the description of this application, unless otherwise expressly specified and limited, the terms "installation" and "connection" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0035] When assembling press-fit power devices, a positioning frame is usually required to position each sub-module during the press-fit process to prevent radial displacement of the functional components of the sub-module during the axial press-fit process. Therefore, the positioning frame on the outside of the sub-module usually only needs to have insulation properties, certain heat resistance and structural strength. Based on this, in this field, the positioning frame is usually made of engineering plastics, such as PEEK (polyether ether ketone), which can not only meet the above requirements, but also reduce the overall weight of the device and meet the requirements of lightweighting.

[0036] As can be seen above, the positioning frame on the outside of the submodule does not have a heat conduction function, but is only set up for positioning during the pressing process. This application aims to improve the above positioning frame to facilitate heat dissipation of power devices and improve the heat dissipation performance of power devices.

[0037] Reference Figure 1 This is a schematic diagram of a press-fit power device according to an embodiment of this application. It includes a housing 1, multiple sub-modules 2, and positioning frames 3 corresponding to the sub-modules 2. The housing 1 includes a base 11, a support frame 12, and a cover plate 13. The support frame 12 is located between the base 11 and the cover plate 13, and has through holes for accommodating each sub-module 2. The support frame 12 forms an accommodating space for accommodating each sub-module 2 and the positioning frame 3. During the packaging process of the power device, the positioning frame 3 is first installed on the outside of each through hole of the support frame 12, then the sub-modules 2 are placed inside the positioning frame 3, with the lower end of each sub-module 2 passing through the through holes. Finally, the cover plate 13 is installed to cover each sub-module 2.

[0038] With the power device fully packaged, the inner surface of the positioning frame 3 is in contact with the submodule 2, and the outer surfaces of adjacent positioning frames 3 are in contact with each other. For example, in Figure 1 In the arrangement shown, multiple sub-modules 2 and positioning frame 3 are arranged in a linear array.

[0039] It should be noted that the positioning frame 3 in this application is made of a solid-liquid phase change material, such as paraffin wax or fatty acids. Of course, other phase change materials with insulating properties can also be used. Thus, by setting the positioning frame 3 as a phase change material, in the event of unexpected conditions such as power grid failures, if the heat generated by the submodule 2 increases sharply, the positioning frame 3 absorbs the heat and undergoes a phase change to become liquid, thereby carrying away some of the heat. This reduces the probability of the chip temperature inside the submodule 2 exceeding its maximum junction temperature and causing damage, improving the heat dissipation efficiency of the power device. In other words, the positioning frame 3 in this application not only serves to position the submodule 2 during the power device packaging process but also assists in heat dissipation during the operation of the power device. Therefore, by integrating the positioning frame 3 inside the power device, this application can improve the heat dissipation performance of the device without changing the structural composition of the internal functional components.

[0040] In addition, in the solid state, the adjacent positioning frames 3 are in close contact with each other, and the heat generated by the submodule 2 can be transferred laterally through the positioning frames 3, which helps to improve the temperature uniformity of various regions in the entire device, reduce the device deformation and warping caused by thermal expansion, and improve the reliability of the device.

[0041] Reference Figure 2 and Figure 3 , Figure 2 This is a three-dimensional exploded view of a submodule of a crimped power device according to an embodiment of this application. Figure 3 This is a partial cross-sectional view of a press-fit power device according to an embodiment of this application. A PCB 4 is disposed inside the housing 1, and the PCB 4 is attached to the base 11. In practical applications, depending on the requirements, an insulating plate 5 can be provided between the PCB 4 and the base 11 to meet the insulation requirements between the PCB 4 and the base 11. The lower part of the support frame 12 is attached to the PCB 4.

[0042] Submodule 2 includes a boss 21, an emitter molybdenum sheet 22, a chip 23, and a collector molybdenum sheet 24 arranged sequentially along the axial direction of submodule 2 from the side where PCB4 is located. Optionally, the boss 21 can be made of copper to meet the requirements of heat conduction and electrical conductivity. The connection relationship and function of the above components are well known in the art and will not be described in detail here. The positioning frame 3 is set on the support frame 12. Along the pressing direction of submodule 2 (from top to bottom in the figure), the inner diameter of the positioning frame 3 gradually decreases, forming a stepped distribution to form multiple "steps". Correspondingly, the diameters of the boss 21, emitter molybdenum sheet 22, chip 23, and collector molybdenum sheet 24 increase sequentially to match the steps. After the positioning frame 3 is fixed to the support frame 12, the above functional components of submodule 2 are placed in the positioning frame 3 in sequence and pressed down. Finally, the cover plate 13 is installed, and the cover plate 13 abuts against the collector molybdenum sheet 24 to complete the pressing process.

[0043] Reference Figure 4 and Figure 5 , Figure 4 This is a schematic diagram of a positioning frame according to an embodiment of this application. Figure 5 This is a partial cross-sectional view of a submodule according to an embodiment of this application. A receiving hole 31 is provided on the positioning frame 3. Both ends of the receiving hole 31 penetrate the bottom surface of the positioning frame 3 and the step of the positioning frame 3 near the chip 23, respectively. The submodule 2 also includes a probe 25 disposed within the receiving hole 31. Both ends of the probe 25 extend out of the receiving hole 31. Specifically, the upper end of the probe 25 extends out of the receiving hole 31 and connects to the chip 23, thereby achieving an electrical connection between the probe 25 and the chip 23. The lower end of the probe 25 extends out of the receiving hole 31 and passes through the support frame 12 to connect to the PCB 4, thereby achieving an electrical connection between the probe 25 and the PCB 4. Thus, external power and drive signals are transmitted sequentially to each chip 23 through the PCB 4 and the probe 25.

[0044] In one embodiment of this application, each step of the positioning frame 3 has a gap 100 between it and the corresponding functional component. This gap 100 means that, along the pressing direction of the sub-module 2, the functional component and the positioning frame 3 do not contact each other, thus forming the aforementioned gap 100. For example... Figure 5 As shown, the location of gap 100 is illustrated. It can be seen that the gap 100 is formed between each step of the positioning frame 3 and the cover plate 13, the collector molybdenum sheet 24, the chip 23, and the emitter molybdenum sheet 22.

[0045] The aforementioned gap 100 serves two purposes. First, it prevents pressure from being directly transmitted to the positioning frame 3 during the power device crimping process, thus avoiding the positioning frame 3 bearing some of the pressure and affecting the crimping process of the submodule 2. Second, considering that the positioning frame 3 may expand in volume after being heated and changing to a liquid state, the gap 100, designed to allow space for the volume expansion of the positioning frame 3 during the phase change process, prevents the liquid working fluid after the phase change from putting pressure on the functional components of each layer of the submodule 2.

[0046] Of course, the width of the aforementioned gap 100 can be determined according to actual needs, and this application does not impose any limitations on it. In one embodiment of this application, the positioning frame 3 is an integrally formed structure, so that the positioning frame 3 can be formed in an independent mold, which can simplify the production and processing procedures and improve production efficiency.

[0047] Reference Figure 5 In one embodiment of this application, the positioning frame 3 essentially surrounds the outer side of the submodule 2, with a gap 100 only between the upper end face of the positioning frame 3 and the cover plate 13. Compared to the conventional method where the positioning frame 3 is relatively low and only surrounds the lower part of the submodule 2 to provide positioning during the pressing process, the positioning frame 3 of this application uses a phase change material with good thermal conductivity. Furthermore, the upper end face of the positioning frame 3 is essentially flush with the upper end face of the submodule 2. This maximizes the contact area between the submodule 2 and the positioning frame 3, allowing the heat generated during the operation of the chip 23 to be transferred laterally along the submodule 2 after being transferred axially, thereby further improving the heat dissipation performance of the device.

[0048] It should be noted that the press-fit power device of this application can be either a spring-loaded device or a hard-loaded device, and this application does not limit the type of device. For example, in one implementation, the press-fit power device is a spring-loaded device. In this case, an elastic element is provided between the boss 21 and the bottom of the housing 1 (i.e., the base 11). During the pressing process, the deformation of the elastic element makes the force on the chip 23 more uniform. At the same time, during the operation of the device, the phenomenon of pressure change caused by the chip's heat expansion can be effectively alleviated by the elastic element.

[0049] The technical solutions of this application have been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of this application is obviously not limited to these specific embodiments. Without departing from the principles of this application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of this application.

Claims

1. A press-fit power device, characterized in that, include: Outer shell (1); Multiple sub-modules (2) are disposed within the outer casing (1); Multiple positioning frames (3) are disposed inside the outer shell (1) and correspond one-to-one with the sub-modules (2), and each sub-module (2) is located inside the positioning frame (3); The positioning frame (3) is made of solid-liquid phase change material, and the inner surface of the positioning frame (3) is attached to the sub-module (2).

2. The press-fit power device according to claim 1, characterized in that, The outer surfaces of adjacent positioning frames (3) are in contact with each other.

3. The press-fit power device according to claim 1, characterized in that, Along the pressing direction of the submodule (2), the inner diameter of the positioning frame (3) gradually decreases to form multiple steps that adapt to the various functional components of the submodule (2).

4. The press-fit power device according to claim 3, characterized in that, Each step has a gap (100) between it and the corresponding functional component.

5. The press-fit power device according to claim 3, characterized in that, The positioning frame (3) is an integrally formed structure.

6. The press-fit power device according to claim 3, characterized in that, The outer casing (1) contains a PCB (4), and the sub-module (2) includes a boss (21), an emitter molybdenum sheet (22), a chip (23), and a collector molybdenum sheet (24) arranged sequentially from the PCB (4) along the axial direction of the sub-module (2). The diameters of the boss (21), the emitter molybdenum sheet (22), the chip (23), and the collector molybdenum sheet (24) increase sequentially to adapt to the various steps of the positioning frame (3). The submodule (2) also includes a probe (25), one end of which is connected to the chip (23) and the other end is connected to the PCB (4).

7. The press-fit power device according to claim 6, characterized in that, The outer shell (1) includes a base (11), a support frame (12) and a cover plate (13), wherein the support frame (12) is located between the base (11) and the cover plate (13); The PCB (4) is mounted on the base (11), the positioning frame (3) is mounted on the support frame (12), and the cover plate (13) covers each of the sub-modules (2) and abuts against the molybdenum collector sheet (24).

8. The press-fit power device according to claim 7, characterized in that, The positioning frame (3) has a receiving hole (31), the probe (25) is located in the receiving hole (31), one end of the probe (25) extends out of the receiving hole (31) and is connected to the chip (23), and the other end passes through the support frame (12) and is connected to the PCB (4).

9. The press-fit power device according to claim 7, characterized in that, An elastic element is provided between the boss (21) and the bottom of the outer shell (1).

10. The press-fit power device according to any one of claims 1 to 9, characterized in that, Multiple sub-modules (2) are connected in parallel.

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