Heat dissipation structure for on-board power transistor

Abstract

Provided in the present invention is a heat dissipation structure for an on-board power transistor, the heat dissipation structure comprising: a PCB, power transistors attached to the PCB, and a heat sink corresponding to heat dissipation surfaces of the power transistors, wherein one or more dam structures are provided on the surface of the heat sink attached to the heat dissipation surfaces of the power transistors; thermal interface materials are provided in an area enclosed by the dam structures; and the heat dissipation surfaces of the power transistors are attached to the thermal interface materials. In the present invention, by means of integrating a thermally conductive insulating layer and the heat sink, it is unnecessary to additionally mount an insulating member, thereby simplifying the manufacturing process and improving production efficiency; and by means of using the dam structures arranged on the heat sink to confine thermally conductive materials inside dams, the problems of lateral shifting, sagging, etc., of the thermally conductive materials caused by the impact of temperature change and vibration factors are prevented, thereby improving the thermal reliability of a power supply device.

Description

A heat dissipation structure for vehicle power transistors Technical Field

[0001] This invention relates to the field of new energy vehicle technology, specifically to a vehicle-mounted power tube heat dissipation structure. Background Technology

[0002] With the continuous upgrading of new energy vehicle technology and the accelerated pace of product iteration, on-board chargers and other vehicle power supply products are rapidly developing towards higher power density, miniaturization, and lower cost. Currently, most on-board power supply products use a bottom-heat-dissipating package design for power transistors, achieving effective heat conduction and dissipation by adhering to a three-dimensional water channel surface. However, because the vibration of power transistors in the vehicle environment is much stronger than in a normal environment, the reliability of the heat dissipation structure of existing on-board chargers and other vehicle power supply products is relatively low. Summary of the Invention

[0003] In order to solve the technical problem of low reliability of vehicle power tube heat dissipation structure in the prior art, the present invention proposes a vehicle power tube heat dissipation structure.

[0004] The technical solution adopted in this invention is:

[0005] This invention proposes a vehicle-mounted power transistor heat dissipation structure, comprising: a PCB circuit board, a power transistor mounted on the PCB circuit board, and a heat sink corresponding to the heat dissipation surface of the power transistor. The side of the heat sink that is in contact with the heat dissipation surface of the power transistor is provided with one or more dam structures, and a thermally conductive interface material is provided in the area enclosed by the dam structures. The heat dissipation surface of the power transistor is in contact with the thermally conductive interface material.

[0006] Preferably, the projected area B of the region enclosed by the cofferdam structure is greater than or equal to the area A of the power transistor pin region, and the depth of the region enclosed by the cofferdam structure is greater than or equal to 50 μm.

[0007] Furthermore, a thermally conductive insulating layer is provided on the surface of the cofferdam structure.

[0008] Preferably, the thickness of the thermally conductive insulating layer ranges from 50 to 250 μm.

[0009] Preferably, the material of the thermally conductive insulating layer is any one or more combinations of Al2O3, AlN, Si3N4, PI, PEI, and epoxy resin composite materials.

[0010] Preferably, the thermally conductive and insulating layer on the surface of the cofferdam structure is integrated with the radiator through any one of the following processing techniques: spraying, gluing, welding, hot pressing, or micro-arc oxidation.

[0011] Preferably, the thickness of the thermally conductive interface material ranges from 150 to 500 μm.

[0012] Furthermore, the cofferdam structure is a groove provided on the surface of the radiator, and the angle between the sidewalls of the groove and the bottom surface is a right angle or an oblique angle.

[0013] Furthermore, the thickness of the thermally conductive insulating layer is h1, the thickness of the thermally conductive interface material is h2, the distance between the cofferdam structure and the top edge of the power transistor package is L, the creepage distance from the pin of the power transistor to the top of the power transistor body is L1, and L+h1+h2+L1≥3.7mm.

[0014] In the first embodiment, the cofferdam structure and the power tube are arranged in a one-to-one correspondence.

[0015] In the second embodiment, the multiple power tubes are bonded to a thermally conductive interface material disposed within the area enclosed by the cofferdam structure.

[0016] In the third embodiment, the multiple power tubes are bonded to a thermal interface material disposed within the area enclosed by the cofferdam structure.

[0017] Furthermore, the PCB circuit board is pressed together by a support column provided inside the power supply device housing cover, and the support column is directly opposite the position of the power transistor on the PCB circuit board.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. By integrating the thermally conductive insulation layer and the heat sink, there is no need to install additional insulation components, which simplifies the manufacturing process and improves production efficiency.

[0020] 2. By setting a thermally conductive interface material that facilitates a tight fit between the radiator and the power tube, the heat transfer efficiency is improved while also buffering some vibrations. Furthermore, by confining the thermally conductive interface material within the dam structure on the radiator, problems such as horizontal slippage and sagging of the thermally conductive interface material due to temperature changes and strong vibrations in the vehicle environment can be prevented, thereby improving the heat dissipation reliability of power devices such as on-board chargers.

[0021] 3. The cofferdam structure increases the electrical insulation distance between the power transistor pins, the heat dissipation surface, and the water channel heat dissipation surface, thereby improving the electrical reliability of the power supply product.

[0022] 4. Compared to structures without cofferdams, the waterway wall thickness in the cofferdam area is reduced, further reducing thermal resistance and increasing the heat dissipation capacity of power devices. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 is a structural schematic diagram of a specific embodiment of the present invention;

[0025] Figure 2 is a schematic diagram of the structure of a single cofferdam structure and the corresponding power tube in a specific embodiment of the present invention;

[0026] Figure 3 is a schematic diagram of the structure of the right-angled groove formed by the surface indentation in a specific embodiment of the present invention;

[0027] Figure 4 is a schematic diagram of the structure of the oblique groove formed by the surface indentation in a specific embodiment of the present invention;

[0028] Figure 5 is a schematic diagram of a cofferdam structure corresponding to multiple power tubes in a specific embodiment of the present invention;

[0029] Figure 6 is a schematic diagram of the structure with added support columns in a specific embodiment of the present invention;

[0030] Figure 7 is a flowchart of a specific embodiment of the present invention;

[0031] Figure 8 is a structural schematic diagram of another embodiment of the present invention;

[0032] 101. Heat sink; 102. Dike structure; 103. Thermally conductive insulation layer; 2. Thermally conductive interface material; 301. Power transistor; 4. PCB circuit board; 501. Threaded connector; 601. Housing cover plate; 602. Support column. Detailed Implementation

[0033] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0034] The principles and structure of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0035] In the existing technology, the reliability of existing vehicle power products such as on-board chargers is relatively low. This is mainly because the vibration of power transistors in the vehicle environment has a significant impact. As a result, during actual use, the heat dissipation surface of the power transistor cannot be effectively attached due to factors such as temperature changes and vibration, which affects the heat conduction efficiency.

[0036] As shown in Figure 1, this invention proposes a heat dissipation structure for automotive power transistors, applicable to power supply products such as on-board chargers. Specifically, it includes a PCB circuit board 4, power transistors 301, and a heat sink 101. Multiple power transistors 301 are mounted on the PCB circuit board 4. The side of the power transistor 301 facing away from the PCB circuit board 4 is the heat dissipation surface, i.e., it adopts a top-heat dissipation packaging. The pins of the power transistors 301 are soldered to the PCB circuit board 4 for electrical connection. The heat sink 101 is fixedly connected to the PCB circuit board 4, and one or more dike structures 102 are provided on the side of the heat sink 101 opposite to the heat dissipation surface of the power transistors 301. A thermally conductive interface material 2 is provided on the bottom surface of the area enclosed by the dike structure 102. The thermally conductive interface material 2 is used to adhere to the heat dissipation surface of the power transistors 301. After the heat sink 101 is fixedly connected to the PCB circuit board 4, the dike structure 102 confines the thermally conductive interface material 2 within the heat dissipation area of ​​the power transistors 301, while simultaneously ensuring close contact between the thermally conductive interface material 2 and the heat dissipation surface of the power transistors 301.

[0037] The vehicle-mounted power tube heat dissipation structure provided by this invention takes into account that the heat dissipation surface of the power tube and the contact surface of the radiator 101 are not perfectly flat. Therefore, a deformable thermally conductive interface material 2 is provided between them. By compression, it can be tightly bonded to the heat dissipation surface of the power tube 301 and the radiator 101, thereby improving the heat conduction efficiency. Furthermore, the thermally conductive interface material 2 is confined inside the dam by the dam structure 102 provided on the radiator, preventing horizontal slippage and sagging of the thermally conductive interface material 2 under the influence of temperature changes and strong vibration factors in the vehicle environment, thus improving the thermal reliability of the power supply device.

[0038] In addition, the interior of the contact surface of the radiator 101 can be provided with a heat dissipation structure such as a three-dimensional water channel, or other radiative heat dissipation structures.

[0039] Specifically, the PCB circuit board 4 can be fixedly connected to the heat sink through the threaded connector 501, so that the power tube 301, the thermal interface material 2 and the heat sink are tightly attached, while the dike structure 102 confines the thermal interface material 2 within the area it encloses.

[0040] In a further embodiment, a thermally conductive insulating layer 103 is provided on the surface of the cofferdam structure 102, and a thermally conductive interface material 2 is disposed outside the thermally conductive insulating layer 103, so that the power tube 301 remains insulated from the heat sink body when it is in contact with the heat sink for heat dissipation. By integrating the thermally conductive insulating layer 103 with the heat sink, there is no need to install additional insulating components, which simplifies the manufacturing process and improves production efficiency.

[0041] In other embodiments, as shown in FIG8, a thermally conductive insulating layer 103 can also be provided inside the heat sink, and formed into an integrated structure with the heat sink material by means of pressing or other methods. The outer part is a metal heat dissipation layer such as aluminum and aluminum alloy, copper and copper alloy, and the core is a thermally conductive insulating layer 103.

[0042] In a specific embodiment, as shown in Figures 2 to 4, the projected area B of the region enclosed by the cofferdam structure 102 is greater than or equal to the pin area A of the power transistor 301. That is, when the region enclosed by the cofferdam structure 102 is projected onto the motherboard, it includes the power transistor 301 and the extended range of the power board pins. The depth of the region enclosed by the cofferdam structure 102 is greater than or equal to 50 μm.

[0043] A thermally conductive insulating layer 103 is provided on the bottom surface of the area of ​​the cofferdam structure 102, that is, a thermally conductive insulating layer 103 is provided on the surface of the cofferdam structure 102. The thickness of the thermally conductive insulating layer 103 is between 50-250um, which can be selected according to the actual situation, preferably greater than or equal to 80um.

[0044] In a further embodiment, the material of the thermally conductive insulating layer 103 is any one or a combination of Al2O3, AlN, Si3N4, PI, PEI, and epoxy resin composite materials.

[0045] In a further embodiment, the thermally conductive insulating layer 103 disposed on the surface of the cofferdam structure 102 is integrated with the radiator by any one of the following processing techniques: spraying, gluing, welding, hot pressing, and micro-arc oxidation.

[0046] In a further embodiment, the thermal interface material 2 is any one of thermally conductive gel, thermally conductive pad, or thermally conductive phase change material. That is, the thermal interface material is a thermally conductive layer disposed in the area of ​​the dam structure 102 of the heat sink 101, used for heat conduction between the power transistor 301 and the heat sink 101. The thickness of the thermal interface material 2 ranges from 150-500 μm, preferably 150-350 μm. Excessive thickness of the thermally conductive material will increase the interface thermal resistance and affect the actual heat dissipation effect of the power supply device. Moreover, the selection of the thickness of the thermal interface material 2 not only considers thermal conductivity but also the electrical insulation distance between the power transistor pins, the heat dissipation surface, and the water channel heat dissipation surface, improving the electrical reliability of the power supply product.

[0047] In a specific embodiment, the cofferdam structure 102 is specifically a groove provided on the lower surface of the radiator 101, as shown in Figures 3 and 4. The groove can be formed by the lower surface being directly recessed inward, or it can be formed by a ring of protrusions, with the area between the protrusions forming the groove.

[0048] In the case of multiple cofferdam structures, the lower surface of the radiator 101 has multiple grooves with protrusions between them, resulting in an overall uneven surface structure. Alternatively, the surface of the radiator 101 may exhibit an overall uneven texture.

[0049] The angle between the sidewalls and the bottom surface of the groove can be either a right angle or an oblique angle, with no specific restriction. The sidewalls other than the bottom of the groove and other surfaces of the radiator may or may not have a thermally conductive insulation layer 103, depending on the actual electrical insulation and structural processing requirements. Furthermore, there is no requirement for the number of cofferdam structures 102; it depends on the number of power tubes 301 needed for heat dissipation and the available structural and layout space.

[0050] As shown in Figure 2, the thickness h1 of the thermally conductive insulating layer 103, the thickness h2 of the thermally conductive interface material 2, the distance L between the dam structure and the top edge of the power transistor 301 package (in the third embodiment, this refers to the outermost dam structure), and the creepage distance L1 from the pins of the power transistor 301 to the top of the power transistor 301 body satisfy the following relationship: L + h1 + h2 + L1 ≥ 3.7 mm. That is, by increasing the electrical insulation distance between the power transistor pins, the heat dissipation surface, and the water channel heat dissipation surface through the dam structure, the electrical reliability of the power supply product is improved.

[0051] The specific processing method of the cofferdam structure 102 is applicable to various embodiments. Specifically, it can be formed by die casting, machining, setting a cofferdam support frame (i.e., forming a protruding part) or cofferdam adhesive (i.e., forming a protruding part).

[0052] The number of cofferdam structures 102 and power tubes 301 opposite each other can be implemented in two ways, as follows:

[0053] In the first embodiment, as shown in Figures 1 to 4, each power tube 301 is provided with a corresponding cofferdam structure 102, that is, the power tube 301 and the cofferdam structure 102 correspond one-to-one, and each power tube 301 can be adapted for installation.

[0054] In the second embodiment, as shown in Figures 5 and 6, in order to improve the processing and production efficiency of the radiator 101, multiple power tubes 301 share a single cofferdam structure 102. The thermally conductive interface material 2 is disposed on the surface of the thermally conductive insulating coating of the cofferdam structure 102, and the multiple power tubes 301 are bonded to the thermally conductive interface material 2 in the cofferdam structure 102.

[0055] In the third embodiment, it can also be in the form of one power tube 301 corresponding to multiple cofferdam structures 102, that is, each cofferdam structure 102 has a thermally conductive interface material 2 on its thermally conductive insulating coating surface, and one power tube 301 is bonded to the thermally conductive interface material 2 in multiple cofferdam structures 102.

[0056] In a further embodiment, as shown in Figure 6, considering the tolerance and PCB deformation issues during the assembly of multiple power transistors 301, it is necessary to ensure the thickness of the thermally conductive material and sufficient contact for heat dissipation through the threaded connector 501. However, in some scenarios, due to the limitations of the water channel structure and the layout of the PCB circuit board 4, there is no extra space to set the mounting holes for the threaded connector 501. To solve this problem, a support post 602 can be set at the position of the power transistor 301 on the housing cover 601. When installing the housing cover 601 (the housing cover 601 is connected to the housing or the edge of the heat exchanger through the threaded connector 501), the support post 602 presses down on the PCB circuit board 4, reducing the deformation of the PCB circuit board 4 and the assembly gap, controlling the thickness of the thermally conductive material within a small range, and reducing the interface thermal resistance.

[0057] The present invention also proposes a power supply device, including the above-mentioned vehicle-mounted power tube heat dissipation structure.

[0058] In a specific embodiment, the power supply device is an on-board charger, and the heat sink is a housing water channel provided inside the housing of the on-board charger.

[0059] As shown in Figure 7, a manufacturing method for the heat dissipation structure described in this invention is also proposed, including the following steps:

[0060] S101, a dam structure is first machined on the surface of the radiator structural component;

[0061] S102, and a thermally conductive and insulating layer is sprayed onto the surface of the cofferdam structure;

[0062] S103, Apply a thermally conductive interface material to the location of the cofferdam structure with a thermally conductive insulating layer;

[0063] S104 assembles the PCB circuit board for assembling the power transistor with the heat sink, ensuring that the heat dissipation surface of the power transistor is in full contact with the thermal interface material.

[0064] The specific embodiments of its installation process and manufacturing method are as follows:

[0065] S101, a cofferdam structure is machined on the heat dissipation surface of the structural component of the radiator (including the shell water channel);

[0066] S102, the surface of the cofferdam structure is sprayed with one or more layers of epoxy resin thermally conductive material, which is then rapidly cured by UV to form a thermally conductive and insulating layer on the surface of the radiator cofferdam structure.

[0067] S103, apply thermally conductive gel material (i.e. thermally conductive interface material) to the location of the cofferdam structure with thermally conductive insulating layer. The material application process is not limited, but dispensing is preferred and stencil printing is optional.

[0068] S104 assembles the PCB circuit board of the power transistor with the heat sink and other housings, so that the heat dissipation surface of the power transistor is in full contact with the thermal conductive gel material, and the thermal conductive gel material is confined to the heat dissipation surface of the power transistor by the cofferdam structure, and the interface thickness is guaranteed.

[0069] It should be noted that the terminology used above is for describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form as well. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0070] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0071] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0072] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

Claims

1. A heat dissipation structure for automotive power transistors, comprising: A PCB circuit board, a power transistor mounted on the PCB circuit board, and a heat sink corresponding to the heat dissipation surface of the power transistor, characterized in that one or more dam structures are provided on the side of the heat sink that is in contact with the heat dissipation surface of the power transistor, and a thermally conductive interface material is provided in the area enclosed by the dam structure, and the heat dissipation surface of the power transistor is in contact with the thermally conductive interface material.

2. The vehicle-mounted power tube heat dissipation structure as described in claim 1, characterized in that, The projected area B of the region enclosed by the cofferdam structure is greater than or equal to the area A of the power transistor pin region, and the depth of the region enclosed by the cofferdam structure is greater than or equal to 50 μm.

3. The vehicle-mounted power tube heat dissipation structure as described in claim 1, characterized in that, The surface of the cofferdam structure is provided with a thermally conductive and insulating layer.

4. The vehicle-mounted power tube heat dissipation structure as described in claim 3, characterized in that, The thickness of the thermally conductive insulating layer ranges from 50 to 250 μm.

5. The vehicle-mounted power tube heat dissipation structure as described in claim 3, characterized in that, The material of the thermally conductive insulating layer is any one or a combination of Al2O3, AlN, Si3N4, PI, PEI, and epoxy resin composite materials.

6. The vehicle-mounted power tube heat dissipation structure as described in claim 3, characterized in that, The thermally conductive and insulating layer on the surface of the cofferdam structure is integrated with the radiator through any one of the following processing techniques: spraying, gluing, welding, hot pressing, or micro-arc oxidation.

7. The vehicle-mounted power tube heat dissipation structure as described in claim 1, characterized in that, The thickness of the thermally conductive interface material ranges from 150 to 500 μm.

8. The vehicle-mounted power tube heat dissipation structure as described in claim 1, characterized in that, The cofferdam structure is a groove provided on the surface of the radiator, and the angle between the side walls of the groove and the bottom surface is a right angle or an oblique angle.

9. The vehicle-mounted power tube heat dissipation structure as described in claim 3, characterized in that, The thickness of the thermally conductive insulating layer is h1, the thickness of the thermally conductive interface material is h2, the distance between the cofferdam structure and the top edge of the power transistor package is L, the creepage distance from the pin of the power transistor to the top of the power transistor body is L1, and L+h1+h2+L1≥3.7mm.

10. The vehicle-mounted power transistor heat dissipation structure as described in any one of claims 1 to 9, characterized in that, The cofferdam structure is configured in a one-to-one correspondence with the power tube; or one power tube is configured to correspond to multiple cofferdam structures; or multiple power tubes are configured to be bonded to a heat-conducting interface material within the area enclosed by one cofferdam structure.

11. The vehicle-mounted power transistor heat dissipation structure as described in claim 1, characterized in that, The PCB circuit board is pressed together by a support column provided inside the cover plate of the power supply unit housing, and the support column is directly opposite the position of the power transistor on the PCB circuit board.

Images