Structure for preventing heat dissipation material from overflowing based on power semiconductor application

Abstract

The invention discloses a structure for preventing a heat dissipation material from overflowing based on power semiconductor application. The structure comprises a power semiconductor module; the radiator is attached to the power semiconductor module and is used for radiating heat of the power semiconductor module; the heat dissipation material is arranged between the power semiconductor module and the heat sink and is used for conducting heat energy generated in the power semiconductor module to the heat sink; and the elastic sealing part is arranged between the power semiconductor module and the radiator by surrounding the periphery of the heat dissipation material so as to seal the heat dissipation material in a vacuum sealing cavity defined by the power semiconductor module, the radiator and the elastic sealing part and prevent the heat dissipation material from overflowing. The closed and vacuum structure of the invention can ensure that the heat dissipation material stably exists between the power device and the radiator and does not overflow, thereby ensuring that the external thermal resistance of the device is stable and reliable in the whole life cycle, and ensuring the service life and safety of the device.

Description

Technical Field

[0001] The present invention relates to the technical field of power modules, and in particular to a structure for preventing heat dissipation materials from overflowing based on power semiconductor applications. Background Art

[0002] Power semiconductor devices, as the core of the electronic industry chain, can realize power conversion and circuit control. In order to improve the power density of power semiconductor devices, power semiconductor devices are usually installed on the heat sink with bolts, so that the self-heating of the power semiconductor devices can be conducted to the heat sink through the heat dissipation material for heat dissipation, and then transferred to the heat sink by other heat dissipation media in the form of heat convection.

[0003] However, when the above-mentioned power semiconductor device is installed in an application (i.e., installed on a heat sink), as the power semiconductor device generates heat, the device interface and the heat sink interface will warp due to factors such as mismatched thermal expansion coefficients and stress constraints, thereby squeezing the heat dissipation materials in the two interfaces and causing the heat dissipation materials to overflow. Long-term heat dissipation material overflow is often irreversible, so that an air gap will appear between the power semiconductor device and the heat sink, which will cause the thermal resistance to become larger than that in the initial stage of use, thereby affecting the heat dissipation of the device and greatly reducing the life and safety characteristics of the device. Summary of the invention

[0004] The purpose of the present invention is to address the problem that after current power semiconductor devices are installed and applied to a heat sink, heat dissipation material overflows, resulting in an air gap between the device and the heat sink, causing the thermal resistance to increase and affecting the service life and safety characteristics of the device. The present invention designs a structure based on power semiconductor applications to prevent heat dissipation material from overflowing, thereby solving the problem of heat dissipation material overflow and improving the application reliability of power semiconductor device products.

[0005] To achieve the above object, the present invention is implemented by the following technical solutions:

[0006] The present invention designs a structure for preventing heat dissipation material from overflowing based on power semiconductor applications, the structure comprising:

[0007] Power semiconductor modules;

[0008] A heat sink, which is arranged in close contact with the power semiconductor module to dissipate heat from the power semiconductor module;

[0009] A heat dissipation material, which is disposed between the power semiconductor module and the heat sink, and is used to conduct heat energy generated in the power semiconductor module to the heat sink;

[0010] and an elastic sealing portion, which surrounds the periphery of the heat dissipation material and is arranged between the power semiconductor module and the heat sink, so as to seal the heat dissipation material in a vacuum sealing cavity formed by the power semiconductor module, the heat sink and the elastic sealing portion to prevent the heat dissipation material from overflowing.

[0011] Furthermore, a structure for preventing heat dissipation material from overflowing based on power semiconductor applications: the power semiconductor module comprises:

[0012] A plastic-sealed housing having a plurality of connection holes for connecting to the radiator;

[0013] A metal-clad ceramic substrate having a welding surface and a heat dissipation surface opposite to each other, which is disposed in the plastic-encapsulated housing and the heat dissipation surface is exposed to the outside of the plastic-encapsulated housing;

[0014] A plurality of semiconductor chips, which are electrically connected to the welding surface of the metal-clad ceramic substrate respectively (specifically, the semiconductor chips can be welded to the welding surface of the metal-clad ceramic substrate by reflow soldering or silver sintering);

[0015] A plurality of power terminals, each having a signal terminal and a connection terminal opposite to the other, wherein the connection terminal is electrically connected to the welding surface of the metal-clad ceramic substrate, and the signal terminal extends to the outside of the plastic package housing (specifically, the connection terminal of the power terminal is welded to the welding surface of the metal-clad ceramic substrate by reflow soldering or ultrasonically crimped);

[0016] and a plurality of metal wires, one end of which is electrically connected to the semiconductor chip, and the other end of which is electrically connected to the surface of the metal-clad ceramic substrate or another semiconductor chip;

[0017] The welding surface of the metal-clad ceramic substrate and the surface of the semiconductor chip are completely covered with insulating material.

[0018] Furthermore, a structure for preventing heat dissipation material from overflowing based on power semiconductor applications: screws are connected in the connection holes and the heat sink to achieve a fixed connection after the plastic package housing and the heat sink are attached.

[0019] Furthermore, a structure for preventing heat dissipation material from overflowing based on power semiconductor applications: a ring-shaped protrusion is also provided on one side of the plastic package shell for bonding with the heat sink.

[0020] Furthermore, a structure for preventing heat dissipation material from overflowing based on power semiconductor applications: the heat dissipation material is coated on the heat dissipation surface and / or the surface of the heat sink, and the heat dissipation material is located within the range enclosed by the annular protrusion.

[0021] Furthermore, a structure for preventing heat dissipation material from overflowing based on power semiconductor applications: the elastic sealing portion is configured as an annular structure, one side of which is in close contact with the heat sink, and the other side forms an interference fit with the annular protrusion.

[0022] Furthermore, a structure for preventing heat dissipation material from overflowing based on power semiconductor applications: the heat dissipation material is thermal conductive silicone grease.

[0023] Furthermore, a structure for preventing heat dissipation material from overflowing based on power semiconductor applications: the elastic sealing portion is made of a material with a high elastic polymer matrix content.

[0024] Furthermore, in a structure for preventing heat dissipation material from overflowing based on power semiconductor applications, the thickness of the elastic sealing portion is 50-100% of the thickness of the heat dissipation material.

[0025] Furthermore, a structure for preventing the overflow of heat dissipation material based on power semiconductor application is provided: in a vacuum environment, the installation between the power semiconductor module and the heat sink, the heat dissipation material and the elastic sealing part is completed to form a vacuum sealed cavity.

[0026] Specifically, the structure designed by the present invention for preventing the overflow of heat dissipation materials based on power semiconductor applications involves a power semiconductor module, which includes a plastic-encapsulated shell with a limited through hole (connection hole), and the device (power semiconductor module) can be fixed on the heat sink by using the connection hole; at the same time, an elastic sealing part is arranged between the device and the heat sink to prevent the overflow of heat dissipation materials. As the device heats up, the device interface and the heat sink interface will bend due to factors such as thermal expansion coefficient mismatch and stress constraint, thereby squeezing the heat dissipation materials in the two interfaces and causing them to overflow. The long-term overflow of heat dissipation materials is often irreversible, so that an air gap will appear between the power device and the heat sink, making the thermal resistance larger, thereby affecting the heat dissipation of the device, affecting the service life and safety of the power device, so it is particularly important to prevent the overflow of heat dissipation materials. However, this point has not been noticed in the existing power device application structure, resulting in a decrease in the safety and service life of the power semiconductor module after it is installed on the heat sink. The present application has discovered this problem that leads to a decrease in the safety and service life of the power semiconductor module, and has proposed a corresponding solution, thereby improving the application reliability of the power semiconductor module product.

[0027] Beneficial effects of the present invention:

[0028] (1) Differences in physical structure will affect the effect of preventing the heat dissipation material from overflowing. Therefore, in the structure designed by the present invention for preventing the heat dissipation material from overflowing based on power semiconductor applications, an interference fit structural design is preferably adopted, which has a better effect of preventing the heat dissipation material from overflowing. The elastic sealing portion can define the interface between the heat sink and the plastic package shell. The preferred elastic sealing portion does not limit the specific shape, but it is better to extend along the annular raised surface of the shell to form a closed loop. The annular elastic sealing portion can also provide the following advantages: using the annular raised surface on the plastic package shell to help improve the positioning deviation during installation.

[0029] (2) The material selection of the elastic sealing part will also affect the effect of preventing the heat dissipation material from overflowing. The present invention preferably uses a filler with a high polymer matrix content, which can strongly inhibit the heat dissipation material from overflowing. In view of the relatively low processing accuracy of the plastic package shell and the heat sink, the surface roughness thereof will cause a tiny gap. The sealing part with sufficient elasticity and softness has a better sealing effect with the power semiconductor device and the heat sink surface under compression, thereby further improving the effect of preventing the heat dissipation material from overflowing.

[0030] (3) When installing power semiconductor devices, the residual air in the gap between the elastic sealing part and the heat dissipation material will continuously impact the sealing effect during the temperature cycle, thereby destroying the sealing effect and causing the heat dissipation material to overflow, ultimately resulting in a deterioration in the heat dissipation effect and affecting the service life of the device. The present invention preferably installs the device in a vacuum environment to effectively remove the air in the internal gap and avoid the above-mentioned problems.

[0031] (4) The heat dissipation material is arranged between the copper-clad ceramic substrate and the heat sink of the device. An elastic sealing portion with a suitable thickness helps to relieve the stress on the copper-clad ceramic substrate during installation, thereby improving the safety of device application. An elastic sealing portion that is too thin cannot fully play a sealing role, and an elastic sealing portion that is too thick will affect the heat dissipation effect of the device. The preferred thickness of the elastic sealing portion of the present invention is controlled to be 50-100% of the thickness of the heat dissipation material, which ensures both the sealing effect and the heat dissipation effect.

[0032] (5) The structure designed by the present invention can ensure that all electrical, thermal and mechanical parameters of the power semiconductor device remain unchanged. No matter what kind of tooling environment the device is used in, the heat dissipation material will not overflow due to changes in the temperature state. The closed and vacuum structure of the present invention can ensure that the heat dissipation material is stably present between the power device and the heat sink without overflowing, thereby ensuring that the external thermal resistance of the device is stable and reliable throughout its life cycle, thereby ensuring its service life and safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the description of the embodiments 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 work.

[0034] Figure 1 A schematic structural diagram of a structure designed for the present invention to prevent heat dissipation material from overflowing based on power semiconductor applications.

[0035] Markings in the figure: 1-power semiconductor module, 2-heat sink, 3-heat dissipation material, 4-elastic sealing part, 5-vacuum sealing cavity, 6-screw, 11-plastic package housing, 12-metal-ceramic substrate, 13-semiconductor chip, 14-power terminal, 15-metal wire, 111-connection hole, 112-annular protrusion. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In the description of the present invention, it should be understood that the terms "upper", "lower", "left", "right", "top", "bottom", etc., indicating the position or positional relationship, are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. Moreover, the terms "first", "second", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein.

[0038] Example 1

[0039] like Figure 1As shown, this embodiment 1 designs a structure for preventing heat dissipation material from overflowing based on power semiconductor applications, and the structure includes:

[0040] Power semiconductor module 1;

[0041] A heat sink 2, which is arranged in close contact with the power semiconductor module 1 to dissipate heat for the power semiconductor module 1;

[0042] A heat dissipation material (thermal conductive silicone grease) 3 is provided between the power semiconductor module 1 and the heat sink 2 to conduct the self-heating generated during the operation of the power semiconductor module 1 to the heat sink 2;

[0043] and an elastic sealing portion (using a filler with a high polymer matrix content) 4, which surrounds the periphery of the heat dissipation material 3 and is arranged between the power semiconductor module 1 and the heat sink 2, so as to seal the heat dissipation material 3 in a vacuum sealing cavity 5 formed by the power semiconductor module 1, the heat sink 2 and the elastic sealing portion 4, thereby preventing the heat dissipation material 3 from overflowing; the thickness of the elastic sealing portion 4 is set to 50-100% of the thickness of the heat dissipation material 3;

[0044] The above installation between the power semiconductor module 1, the heat sink 2, the heat dissipation material 3 and the elastic sealing part 4 is performed under a vacuum environment;

[0045] Wherein, the power semiconductor module 1 comprises:

[0046] The plastic-sealed housing 11 is provided with a plurality of connection holes 111 for connecting with the radiator 2. By connecting screws 6 in the connection holes 111 and the radiator 2, the plastic-sealed housing 11 can be attached to the radiator 2 and then connected and fixed. The plastic-sealed housing 11 is also provided with an annular protrusion 112, which is provided on one side of the plastic-sealed housing 11 for attaching with the radiator 2.

[0047] A metal-clad ceramic substrate (DBC) 12 having a relative welding surface and a heat dissipation surface, wherein the metal-clad ceramic substrate 12 is disposed in the plastic package housing 11, and the heat dissipation surface is exposed to the outside of the plastic package housing 11; the heat dissipation material 3 is coated and disposed on the heat dissipation surface or the surface of the heat sink 2, and ensures that the heat dissipation material 3 is located within the range enclosed by the annular protrusion 112; the elastic sealing portion 4 is configured as an annular structure, one side of which is in close contact with the heat sink 2, and the other side forms an interference fit with the annular protrusion 112;

[0048] A plurality of semiconductor chips 13, which are electrically connected to the welding surface of the metal-clad ceramic substrate 12 respectively;

[0049] A plurality of power terminals 14, each having a signal terminal and a connection terminal, wherein the connection terminal is electrically connected to the welding surface of the metal-clad ceramic substrate 12, and the signal terminal extends to the outside of the plastic package housing 11;

[0050] and a plurality of metal wires 15, one end of which is electrically connected to the semiconductor chip 13, and the other end of which is electrically connected to the surface of the metal-clad ceramic substrate 12 or another semiconductor chip 13;

[0051] The welding surface of the metal-clad ceramic substrate 12 and the surface of the semiconductor chip 13 are completely covered with insulating material.

[0052] Specifically, in this example 1, the thermal grease 3 is evenly applied on the power semiconductor module 1 or the heat sink 3 in advance, and the annular elastic sealing portion 4 is placed in advance according to the installation position of the power semiconductor module 1 so that it forms an interference fit with the annular protrusion 112 on the plastic shell 11, and then the plastic shell 11 is locked on the heat sink 2 by screws 6.

[0053] The annular elastic sealing portion 4 extends along the annular protrusion 112 of the plastic package housing 11 to form a closed loop, which has a better effect. The annular sealing portion 4 can also provide the following advantages: the annular protrusion 112 on the housing helps to improve the positioning deviation during the installation of the power semiconductor module 1.

[0054] Since the residual air in the gap between the elastic sealing part 4 and the thermal grease 3 will continuously impact the sealing effect during the temperature cycle, the cavity 5 formed between the sealing part 4 and the thermal grease 3 will be affected by the environment during installation. Therefore, installing the device in a vacuum environment will effectively eliminate the air in the internal gap.

[0055] Specifically, in the process of installing and applying the power semiconductor device 1 to the heat sink 2, as the power semiconductor device 1 generates self-heat during operation, it will cause the interface of the device 1 and the interface of the heat sink 2 to warp due to factors such as mismatched thermal expansion coefficients and stress constraints, thereby squeezing the heat dissipation material 3 in the two interfaces, causing the heat dissipation material 3 to overflow, and the long-term overflow of the heat dissipation material 3 is often irreversible, so that an air gap will appear between the power semiconductor device 1 and the heat sink 2, which will cause the thermal resistance to become larger than that in the initial use, thereby affecting the heat dissipation of the device 1, and greatly reducing the life and safety characteristics of the device 1. Therefore, it is particularly important to prevent the overflow of the heat dissipation material 3. However, the problem that air gaps are easily generated after the power semiconductor device 1 is installed and applied to the heat sink 2, resulting in increased thermal resistance and affecting the heat dissipation, service life and safety characteristics of the device 1 has not received much attention. The present invention has discovered this problem that leads to reduced safety and service life of the power semiconductor module 1 after application, and has designed a structure based on power semiconductor application to prevent overflow of heat dissipation material, thereby solving many negative problems caused by overflow, improving the application reliability of power semiconductor module products, ensuring that no air gaps will appear between the heat dissipation material 3 and the power semiconductor module 1 and the heat sink 2 during the entire life cycle of the power semiconductor module 1, ensuring that the external thermal resistance is stable and reliable, and ensuring its service life and safety.

[0056] The above are preferred embodiments of the present invention and are only used to explain the present invention, not to limit the present invention. Any obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A structure for preventing heat dissipation material from overflowing based on power semiconductor applications, characterized in that: The structure includes: Power semiconductor module (1); A heat sink (2) is arranged to fit the power semiconductor module (1) and is used to dissipate heat from the power semiconductor module (1); a heat dissipation material (3) disposed between the power semiconductor module (1) and the heat sink (2) for conducting heat energy generated in the power semiconductor module (1) to the heat sink (2); and an elastic sealing portion (4) which surrounds the periphery of the heat dissipation material (3) and is arranged between the power semiconductor module (1) and the heat sink (2) so as to seal the heat dissipation material (3) in a vacuum sealing cavity (5) formed by the power semiconductor module (1), the heat sink (2) and the elastic sealing portion (4) to prevent the heat dissipation material (3) from overflowing.

2. The structure for preventing heat dissipation material from overflowing based on power semiconductor applications according to claim 1, characterized in that: The power semiconductor module (1) comprises: A plastic-sealed housing (11) having a plurality of connection holes (111) for connecting to the heat sink (2); A metal-clad ceramic substrate (12) having a welding surface and a heat dissipation surface opposite to each other, which is arranged in the plastic-encapsulated housing (11), and the heat dissipation surface is exposed to the outside of the plastic-encapsulated housing (11); A plurality of semiconductor chips (13) which are respectively electrically connected to the welding surface of the metal-clad ceramic substrate (12); A plurality of power terminals (14) having a signal end and a connection end, wherein the connection end is electrically connected to the welding surface of the metal-clad ceramic substrate (12), and the signal end extends to the outside of the plastic-encapsulated housing (11); and a plurality of metal wires (15), one end of which is electrically connected to the semiconductor chip (13), and the other end of which is electrically connected to the surface of the metal-clad ceramic substrate (12) or another semiconductor chip (13); The welding surface of the metal-clad ceramic substrate (12) and the surface of the semiconductor chip (13) are completely covered with insulating material.

3. The structure for preventing heat dissipation material from overflowing based on power semiconductor applications according to claim 2, characterized in that: By connecting screws (6) in the connection hole (111) and the heat sink (2), the plastic-sealed housing (11) and the heat sink (2) are fixedly connected after being fitted together.

4. The structure for preventing heat dissipation material from overflowing based on power semiconductor applications according to claim 2, characterized in that: A ring-shaped protrusion (112) is also provided on one side of the plastic-sealed housing (11) for contacting with the heat sink (2).

5. The structure for preventing heat dissipation material from overflowing based on power semiconductor applications according to claim 4, characterized in that: The heat dissipation material (3) is coated on the heat dissipation surface and / or the surface of the heat sink (2), and the heat dissipation material (3) is located within the range enclosed by the annular protrusion (112).

6. The structure for preventing heat dissipation material from overflowing based on power semiconductor applications according to claim 4, characterized in that: The elastic sealing portion (4) is configured as an annular structure, one side of which is in close contact with the radiator (2), and the other side of which forms an interference fit with the annular protrusion (112).

7. The structure for preventing heat dissipation material from overflowing based on power semiconductor applications according to claim 1, characterized in that: The heat dissipation material (3) is thermally conductive silicone grease.

8. The structure for preventing heat dissipation material from overflowing based on power semiconductor applications according to claim 1, characterized in that: The elastic sealing part (4) is made of a material with a high polymer matrix content.

9. The structure for preventing heat dissipation material from overflowing based on power semiconductor applications according to claim 1, characterized in that: The thickness of the elastic sealing portion (4) is 50 to 100% of the thickness of the heat dissipation material (3).

10. The structure for preventing heat dissipation material from overflowing based on power semiconductor applications according to claim 1, characterized in that: The power semiconductor module (1) is installed with the heat sink (2), the heat dissipation material (3) and the elastic sealing portion (4) in a vacuum environment.

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