A power module and a power device resistant to junction temperature fluctuations

Abstract

The present application provides a power device and a power module. The power module includes a phase change module and a chip, and the phase change module is stacked with the chip; the phase change module includes a housing frame and a phase change material, the housing frame includes at least two accommodation cavities, the at least two accommodation cavities are arranged in sequence in a direction away from the surface of the chip, and the phase change material is arranged in the at least two accommodation cavities; the at least two accommodation cavities include a first accommodation cavity and a second accommodation cavity, the distance between the first accommodation cavity and the surface of the chip is less than the distance between the second accommodation cavity and the surface of the chip, and the phase change point of the phase change material in the first accommodation cavity is higher than the phase change point of the phase change material in the second accommodation cavity. This solution utilizes the temperature distribution under the working conditions of the chip, enabling the phase change materials in the accommodation cavities at different distances from the chip surface to undergo phase changes, improving the heat absorption or energy storage effect, and enhancing the function of the power module to resist temperature fluctuations.

Description

Technical Field

[0001] This application relates to the field of electronic power technology, and particularly to a power module and a power device resistant to junction temperature fluctuations. Background Art

[0002] In recent years, with the increasing development of green energy, it has gradually become the main means to solve the energy crisis. As a core component of green energy, power modules have been widely used. With the rapid increase in the output power of power conversion devices, the transient junction temperature fluctuations are also becoming larger and larger. Due to the different thermal expansion coefficients of each layer of materials in the power module of the power conversion device, under long-term operation, the junction temperature fluctuations will cause problems such as solder layer fatigue and bonding wire detachment, ultimately leading to module failure and module reliability problems. Therefore, currently under overload conditions, further requirements are put forward for the ability of the power module to resist transient junction temperature fluctuations.

[0003] A phase change material (PCM: Phase Change Material) refers to a substance that changes its state without changing temperature and can provide latent heat. The process of mutual conversion between the solid, liquid, and gaseous states of the phase change material is called the phase change process, during which the phase change material will absorb or release a large amount of latent heat. The method of using the phase change material to absorb or release heat during the phase change process is called latent heat storage, which has the advantages of high energy storage density, constant temperature during energy storage and release, and recyclability. Therefore, phase change materials can be applied to the field of power modules to help solve the problem of junction temperature fluctuations. Summary of the Invention

[0004] This application provides a power module and a power device resistant to junction temperature fluctuations. In this application, a phase change material is introduced into the power module, and the structure of the power module is redesigned and optimized, which can effectively suppress the junction temperature fluctuations of the entire power module and improve its heat dissipation performance. Adding a phase change material near the chip can effectively increase the equivalent heat capacity of the power module, and the increase in heat capacity can effectively reduce the chip junction temperature fluctuations and improve the temperature uniformity effect of the power module. In this application, a receiving frame is arranged on the surface of the chip of the power module, and a plurality of receiving cavities are arranged in the receiving frame. Each receiving cavity is filled with a phase change material. Since the distances of each receiving cavity from the chip are not equal, according to the temperature distribution of the chip during operation, the temperature at the position farther from the chip will be lower. Therefore, a phase change material with a higher phase change point is filled in the receiving cavity closer to the chip, and a phase change material with a lower phase change point is filled in the receiving cavity farther from the chip. The characteristics of different phase change points can be fully utilized. When the chip has a power overload, the phase change materials in each receiving cavity can all undergo phase changes to absorb or store heat, thereby maximizing the heat capacity of the power module, effectively reducing the chip junction temperature fluctuations, and improving the temperature uniformity effect of the power module.

[0005] To this end, the embodiments of the present application adopt the following technical solutions:

[0006] In a first aspect, an embodiment of the present application provides a power module. The power module includes: a phase change module and a chip, and the phase change module is stacked with the chip; the phase change module includes a receiving frame and a phase change material, the receiving frame includes at least two receiving cavities, the at least two receiving cavities are sequentially arranged in a direction away from the first surface of the chip, and the phase change material is disposed in the at least two receiving cavities; the at least two receiving cavities include a first receiving cavity and a second receiving cavity, the distance between the first receiving cavity and the chip is less than the distance between the second receiving cavity and the chip, and the phase change point of the phase change material in the first receiving cavity is higher than the phase change point of the phase change material in the second receiving cavity, wherein the first surface of the chip is perpendicular to the thickness direction of the power module.

[0007] It can be understood that according to the thermal imaging analysis of the chip, as the distance from the chip surface increases, the temperature around the chip gradually decreases. In order to make full use of the phase change characteristics of the phase change material, a layered receiving frame is adopted in the present application, and phase change materials with different phase change points are used in different receiving cavities. Among them, the distance between the receiving cavity and the chip refers to the distance between the geometric center of the receiving cavity and the geometric center of the chip, or the distance between the geometric center of a receiving wall of the receiving cavity and the geometric center of a certain surface of the chip. For the calculation of the distance between different receiving cavities and the chip, it should be the distance between each receiving cavity and the same surface of the chip, and the relative positions of the receiving walls in each receiving cavity are the same. Specifically, a phase change material with a high phase change point is arranged in the receiving cavity close to the chip, and a phase change material with a low phase change point is arranged in the receiving cavity far from the chip, so that the phase change points of the phase change materials in each receiving cavity show a gradient distribution characteristic, which is consistent with the temperature distribution trend around the chip. When the chip power is overloaded and the power consumption suddenly increases, the phase change materials in each receiving cavity can reach the phase change point, so as to undergo a phase change to absorb or store heat, thereby maximizing the heat capacity of the power module, effectively reducing the junction temperature fluctuation of the chip, and improving the temperature uniformity effect of the power module.

[0008] Combined with the first aspect, in a first possible implementation manner, the at least two receiving cavities are sequentially arranged along the thickness direction of the power module, and the plane where each receiving cavity is located is parallel to the first surface of the chip, wherein the plane where the receiving cavity is located is the plane where the surface of the receiving cavity perpendicular to the thickness direction of the power module is located. It can be understood that different receiving cavities are parallel to each other and are sequentially arranged in a direction away from the surface of the chip. This distribution method of the receiving cavities is roughly the same as the temperature distribution trend around the chip in the horizontal direction, which is helpful for arranging phase change materials with different phase change points. Among them, the horizontal direction refers to the direction parallel to the surface of the chip in the thickness direction of the power module.

[0009] In combination with the first aspect, in the second possible implementation manner, the at least two accommodation cavities are arranged in sequence along a first direction, a plane where each accommodation cavity is located is perpendicular to a first surface of the chip, the first direction is perpendicular to a thickness direction of the power module, and a plane where the accommodation cavity is located is a plane where a surface perpendicular to the first direction in surfaces of the accommodation cavity is located. It can be understood that the different accommodation cavities are parallel to each other and are all perpendicular to the surface of the chip. This distribution manner of the accommodation cavities is roughly the same as the distribution trend of the temperature around the chip in the vertical direction, which helps to arrange phase change materials with different phase change points. Among them, the vertical direction refers to a direction perpendicular to the surface of the chip in the thickness direction of the power module.

[0010] In combination with the first aspect, in the third possible implementation manner, the at least two accommodation cavities are arranged in sequence along a first direction, a plane where each accommodation cavity is located is perpendicular to the surface of the chip, and each of the at least two accommodation cavities is annular and is arranged in sequence from the center of the chip to the edge of the chip. It can be understood that the temperature at positions with the same distance from the geometric center of the chip should be roughly the same. The distribution manner of the annular accommodation cavities is roughly the same as the distribution trend of the temperature around the chip in the direction extending outward from the geometric center of the chip. The different accommodation cavities are sleeved with each other, which helps to arrange phase change materials with different phase change points.

[0011] In combination with the first aspect, in the fourth possible implementation manner, each of the at least two accommodation cavities is hemispherical arc-shaped and is arranged in sequence from the center of the chip surface in a direction away from the chip. It can be understood that the temperature at positions with the same distance from the chip should be roughly the same. The isotherms around the chip roughly form a hemispherical arc shape. The distribution manner of the hemispherical arc-shaped accommodation cavities is roughly the same as the distribution trend of the temperature around the chip. The different accommodation cavities are sleeved with each other, which helps to arrange phase change materials with different phase change points.

[0012] In combination with the first aspect, in the fifth possible implementation manner, the phase change module includes a first phase change module, the first phase change module is arranged on a first surface of the chip, a second surface of the chip is used to arrange a first radiator, and the first surface and the second surface are arranged opposite to each other. It can be understood that the phase change material in the phase change module can increase the thermal resistance. Therefore, reducing the arrangement of the phase change material on the heat dissipation path or arranging the phase change module on a non-heat dissipation path, and arranging the phase change module and the radiator on two opposite surfaces of the chip in the thickness direction of the power module can ensure the heat dissipation effect of the power module.

[0013] In combination with the first aspect, in the sixth possible implementation manner, the accommodation frame of the first phase change module includes a current-carrying part, which is used to provide a path for the current in the chip. The current-carrying part is arranged on the side of the accommodation frame of the first phase change module close to the chip. The content of the phase change material per unit volume in the current-carrying part is less than the content of the phase change material per unit volume in other parts of the accommodation frame of the first phase change module. It can be understood that the phase change material in the first phase change module generally has poor conductivity, which is not conducive to the conduction of current. Therefore, in the current-carrying part where current flows, the setting of the phase change material is reduced to improve the conductivity of the phase change module.

[0014] In combination with the first aspect, in the seventh possible implementation manner, no phase change material is arranged in the current-carrying part. It can be understood that not arranging the phase change material in the current-carrying part can maximize the conductivity of the phase change module.

[0015] In combination with the first aspect, in the eighth possible implementation manner, the phase change module includes a second phase change module, which is arranged between the chip and the first heat sink. It can be understood that arranging the phase change module between the chip and the heat sink can also reduce the temperature fluctuation at the chip junction and improve the temperature uniformity effect of the power module.

[0016] In combination with the first aspect, in the ninth possible implementation manner, the accommodation frame of the second phase change module includes a first heat dissipation part and a first phase change part. The first phase change part is arranged around the first heat dissipation part. The projection of the first heat dissipation part in the thickness direction of the chip overlaps with the first surface of the chip. The content of the phase change material per unit volume in the first heat dissipation part is less than the content of the phase change material per unit volume in the first phase change part. It can be understood that the first heat dissipation part is located on the heat dissipation path of the power module, and the phase change material in the phase change module can increase the thermal resistance. Therefore, reducing the setting of the phase change material on the heat dissipation path can ensure the heat dissipation effect of the power module.

[0017] In combination with the first aspect, in the tenth possible implementation manner, no phase change material is arranged in the first heat dissipation part. It can be understood that not arranging the phase change material in the first heat dissipation part can maximize the heat dissipation efficiency of the power module.

[0018] In combination with the first aspect, in the eleventh possible implementation manner, the side of the first phase change module facing away from the chip is used to arrange a second heat sink; the accommodation frame of the first phase change module includes a second heat dissipation part and a second phase change part, the second phase change part is arranged around the second heat dissipation part, and the projection of the second heat dissipation part on the thickness of the chip overlaps with the first surface of the chip; the content of the phase change material per unit volume in the second heat dissipation part is less than the content of the phase change material per unit volume in the second phase change part. It can be understood that the second heat dissipation part is located on the heat dissipation path of the power module, and the phase change material in the phase change module can increase the thermal resistance. Therefore, reducing the setting of the phase change material on the heat dissipation path can ensure the heat dissipation effect of the power module.

[0019] In combination with the first aspect, in the twelfth possible implementation manner, no phase change material is arranged in the second heat dissipation part. It can be understood that not arranging the phase change material in the second heat dissipation part can maximize the heat dissipation efficiency of the power module.

[0020] In combination with the first aspect, in the thirteenth possible implementation manner, the projection of the first phase change module in the thickness direction of the power module covers the first surface of the chip. It can be understood that the projected area of the first phase change module is larger than the area of the first surface of the chip, and more phase change material can be accommodated in the accommodation cavity, thereby increasing the content of the phase change material in the power module and further increasing the heat capacity of the power module.

[0021] In combination with the first aspect, in the fourteenth possible implementation manner, the power module includes a metal-clad layer substrate, the metal-clad layer substrate is stacked with the chip and is in contact with the surface of the chip; or, the metal-clad layer substrate is arranged on the side of the phase change module facing away from the chip. Generally, the metal-clad layer substrate is a direct bond copper (DBC) substrate, an active metal brazed copper (AMB, such as Al2O3-AMB, Si3N4-AMB or AlN-AMB) substrate or an insulated metal substrate (IMS), etc. Exemplarily, in order to further improve the power density, the metal-clad layer substrate can be formed by using highly thermally conductive AlN-DBC, Si3N4-AMB or AlN-AMB, which is not limited herein.

[0022] In combination with the first aspect, in the fifteenth possible implementation manner, the phase change frame is a metal frame or a diamond frame, and the phase change material is any one or more of elemental metals, alloys, organic substances, and inorganic salts.

[0023] In combination with the first aspect, in the sixteenth possible implementation manner, the power module further includes a plastic package body. The chip and the phase change module are disposed inside the plastic package body, or the chip is disposed inside the plastic package body while the phase change module is disposed outside the plastic package body.

[0024] In combination with the first aspect, in the seventeenth possible implementation manner, the at least two accommodation cavities communicate with each other.

[0025] In a second aspect, an embodiment of the present application provides a power device, characterized in that the power device includes: at least one power module as described in the first aspect and a circuit board. The at least one power module is disposed on the circuit board, and the at least one power module is used for AC / DC conversion. It can be understood that the power device includes the power module in the embodiment of the application in the first aspect. Since the power module has good characteristics of resisting the fluctuation of the junction temperature, when the power is overloaded, the chip can still maintain a relatively good uniform temperature, thereby improving the working performance of the power device during power consumption overload and enhancing the stability. Description of the Drawings

[0026] Figure 1 Schematic diagram of the heat dissipation path of the current power module;

[0027] Figure 2 Cauer RC thermal network model of the power module;

[0028] Figures 3A - 3E Schematic structural diagram of a power module provided in Embodiment 1;

[0029] Figure 3F Schematic three-dimensional structure diagram of the phase change module in a power module provided in Embodiment 1;

[0030] Figure 4A Schematic structural diagram of a power module provided in Embodiment 2;

[0031] Figure 4B Schematic three-dimensional structure diagram of the phase change module in a power module provided in Embodiment 2;

[0032] Figure 5A Schematic structural diagram of a power module provided in Embodiment 3;

[0033] Figure 5B Schematic three-dimensional structure diagram of the phase change module in a power module provided in Embodiment 3;

[0034] Figure 6A Schematic structural diagram of a power module provided in Embodiment 4;

[0035] Figure 6BIt is a schematic three-dimensional structure diagram of a phase change module in a power module provided by Embodiment 4;

[0036] Figures 7A - 7C It is a schematic structure diagram of a power module provided by Embodiment 5;

[0037] Figures 8A - 8B It is a schematic structure diagram of a power module provided by Embodiment 6;

[0038] Figure 8C It is a schematic structure diagram of a power module provided by Embodiment 7;

[0039] Figures 9A - 9B It is a schematic structure diagram of a power module provided by Embodiment 8;

[0040] Figure 10 It is a schematic structure diagram of a power module provided by Embodiment 9;

[0041] Figure 11 It is a schematic structure diagram of a power module provided by Embodiment 10;

[0042] Reference Signs:

[0043] Substrate - 1, thermal grease - 2, substrate connection layer - 3, chip connection layer - 4, plastic package - 5, chip - 30, chip - 30’, heat sink - 40 - 41, metal - clad substrate - 60, phase change frame - 10, phase change frame - 10’, accommodation cavity - 11 - 18, accommodation cavity - 71 - 76, accommodation cavity - 01 - 06, accommodation cavity - 11’ - 13’, accommodation cavity - 71’ - 76’, phase change material - 21 - 28, phase change material - 81 - 86, phase change material - 91 - 96, phase change material - 21’ - 23’, phase change material - 81’ - 86’. Detailed implementation manners

[0044] Next, the technical solutions in the embodiments of the present application will be described with reference to the accompanying drawings in the embodiments of the present application.

[0045] Power modules play an important role in power devices and are the core components of power devices in fields such as new energy vehicles and intelligent photovoltaics. When the power device is working, the chips in the power module achieve the conversion of AC / DC power through frequent on / off state switching. With the development of the industry towards high-voltage scenarios, power modules are also developing in the direction of high voltage. Power modules often operate under overload conditions, such as the acceleration and deceleration of new energy electric vehicles and the start and stop of intelligent photovoltaic high-voltage power generation. This is reflected in the power module as a temperature fluctuation at the junction. The power module is composed of different materials stacked and connected, and the difference in the thermal expansion coefficients of the internal materials is relatively large. When the temperature changes, thermal stress aging occurs between the connection layers that realize internal interconnection of the module, leading to reliability problems such as solder layer fatigue or bond wire detachment. The temperature fluctuation at the junction has a great impact on the module life. Reducing the temperature fluctuation at the junction of the power module is of great significance for improving the reliability of the module in application scenarios with frequent power fluctuations.

[0046] The general structure of the power module is as Figure 1 described. The chip 30 is soldered to the metal-clad substrate 60 through solder. Then, the metal-clad substrate 60 is soldered to the substrate 1 to form the internal encapsulation of the module, and is encapsulated by the plastic package 5. The power module is connected to the heat sink 40 through the thermal grease 2. When the power module is working, the chip 30 will generate heat loss, and the heat is transferred to the heat sink 40 through the metal-clad substrate 60, the substrate 1, and the thermal grease 2, and the heat is dissipated through active or passive heat dissipation. Generally speaking, the junction temperature of the chip 30 in the power module does not exceed the allowable maximum temperature. According to the Cauer RC thermal network model of the power module, as Figure 2 shown, in the case of power fluctuation, there are two ways to reduce the temperature fluctuation at the junction of the power module. One is to reduce the thermal resistance R on the heat dissipation path of the power module, and the other is to increase the internal heat capacity C of the power module.

[0047] Regarding the reduction of the thermal resistance on the heat dissipation path, it is mainly to reduce the thermal resistance of the contact materials between different components. For example, the module and the heat sink are connected by silver sintering. This process technology is relatively mature and has been commercially applied. Currently, the focus of research in the industry is on how to increase the heat capacity of the power module and reduce the temperature fluctuation at the junction of the power module.

[0048] Regarding the increase in heat capacity along the heat dissipation path, the current mainstream approach is the application of phase change materials. Phase change materials (PCM: Phase Change Material) absorb or release heat during phase change while maintaining a constant temperature, with dQ / dT equivalent to infinity, that is, the equivalent heat capacity is infinite. Therefore, phase change materials have higher value in enhancing heat capacity. Phase change materials have been used in heat management fields such as heat sinks in the integrated circuit field, but their temperature response time is too long, which to a certain extent limits the cooling effect of phase change materials. To solve this problem, a copper block with a special structure is tried to be added between the chip and the DBC, and the inside of the copper block is grooved and filled with phase change materials, taking advantage of the property of phase change materials absorbing latent heat during the phase change process. Such a design usually only has partial phase change materials undergo phase change under the overload condition of the power module, failing to fully utilize the performance of phase change materials absorbing heat during phase change. Therefore, a new power module structure needs to be sought so that the module can respond to the change of the junction temperature at a faster speed, reduce the amplitude of the junction temperature fluctuation, and improve the reliability of the power module.

[0049] To address the above problems, the present application provides a novel power module and power device. Through the thermal map analysis of the chip in the working state, it can be obtained that the temperature is higher closer to the chip, and in the direction from the center of the chip to away from the chip, the temperature around the chip shows a gradually decreasing distribution. In order to make full use of the chip temperature distribution, a phase change frame is set at a position close to the chip, and a plurality of accommodating cavities are set at different distances from the chip in the phase change frame, and phase change materials with different phase change points are set in different accommodating cavities, so that phase change materials with different phase change points can all undergo phase change, thereby maximizing the utilization rate of phase change materials.

[0050] The first embodiment provided by the present application is as follows Figure 3AIn the first embodiment of the present application, a power module is provided. The power module includes a chip 30 and a phase change frame 10. The phase change frame 10 includes two accommodating cavities, specifically, an accommodating cavity 11 and an accommodating cavity 12. The accommodating cavity 11 and the accommodating cavity 12 are arranged in sequence in the direction away from the first surface of the chip 30. A phase change material 21 is arranged in the accommodating cavity 11, and a phase change material 22 is arranged in the accommodating cavity 12. The distance between the accommodating cavity 12 and the chip 30 is less than the distance between the accommodating cavity 11 and the chip 30, and the phase change point of the phase change material 22 in the accommodating cavity 12 is higher than the phase change point of the phase change material 21 in the accommodating cavity 11. Among them, the phase change point of the phase change material 22 is equal to the temperature at the accommodating cavity 12 of the chip 30 under overload conditions, and the phase change point of the phase change material 21 is equal to the temperature at the accommodating cavity 11 of the chip 30 under overload conditions. Note: The equality here also includes approximate equality, not necessarily exactly equal, for example, the difference is 1%-10%. Through the above settings, when the chip 30 operates under overload conditions, both the phase change material 21 and the phase change material 22 can undergo phase changes, which can absorb or store energy to the greatest extent, increase the heat capacity of the power module, and improve the anti-junction temperature fluctuation effect of the power module.

[0051] The accommodating cavity 11 and the accommodating cavity 12 are cuboids with a certain height in the thickness direction of the power module. The surfaces of the accommodating cavity 11 and the accommodating cavity 12 in the thickness direction of the power module are parallel to the surface of the chip 30 in the thickness direction of the power module. Among them, the plane where the accommodating cavity is located is the plane where the surface of the accommodating cavity in the thickness direction of the power module is located. In a feasible embodiment, the projections of the accommodating cavity 11 and the accommodating cavity 12 in the thickness direction of the power module cover the projection of the chip 30 in the thickness direction of the power module. This setting can increase the phase change area of the phase change frame and improve the anti-junction temperature fluctuation effect. Of course, the size of the phase change frame can also be set according to the junction temperature fluctuation of the chip. For a chip with small junction temperature fluctuation, the setting of the phase change frame can be reduced, so that the projection area of the accommodating cavity 11 and the accommodating cavity 12 in the thickness direction of the power module is smaller than the projection area of the chip 30 in the thickness direction of the power module.

[0052] In some feasible embodiments, the phase change frame 10 may include more than 2 accommodating cavities, such as Figure 3BAs shown, the phase change framework 10 includes 5 accommodating cavities, and phase change materials with different phase change points are respectively arranged therein. Specifically, a phase change material 21 is arranged in the accommodating cavity 11, a phase change material 22 is arranged in the accommodating cavity 12, a phase change material 23 is arranged in the accommodating cavity 13, a phase change material 24 is arranged in the accommodating cavity 14, and a phase change material 25 is arranged in the accommodating cavity 15. Among them, the distances from the accommodating cavity 11, the accommodating cavity 12, the accommodating cavity 13, the accommodating cavity 14, and the accommodating cavity 15 to the chip 30 decrease in sequence, while the phase change points of the phase change material 21, the phase change material 22, the phase change material 23, the phase change material 24, and the phase change material 25 increase in sequence. The specific settings of the phase change points of the phase change material 21, the phase change material 22, the phase change material 23, the phase change material 24, and the phase change material 25 can be set according to the temperature distribution of the chip 30 under the overload condition, so that the phase change materials in each accommodating cavity can undergo phase changes, maximizing the heat capacity of the power module.

[0053] Meanwhile, different accommodating cavities can be connected or separated from each other, and the specific settings can be adjusted according to the application scenario. The material of the accommodating framework 10 can be metal or diamond. The heat dissipation effect of diamond is better, but the cost is higher, and the framework material can be flexibly selected according to actual needs. The material of the phase change material can be any one or more of elemental metals, alloys, organic substances, and inorganic salts, and can be selected according to the temperature distribution of the chip 30 under the actual working condition.

[0054] In some feasible embodiments, according to the actual temperature distribution of the chip 30, the phase change points of the phase change materials in each accommodating cavity do not necessarily have differences. As the distance from different phase change cavities to the chip 30 becomes farther and farther, as long as the phase change points of the corresponding phase change materials in the accommodating cavity show a gradually decreasing trend. As Figure 3C shown, the setting of the accommodating cavity is the same as that in Figure 3B , but the setting of the phase change material is different. Specifically, the phase change points of the phase change material 21, the phase change material 22, and the phase change material 23 are the same, the phase change points of the phase change material 24 and the phase change material 25 are the same, and the phase change points of the phase change material 21, the phase change material 22, and the phase change material 23 are less than the phase change points of the phase change material 24 and the phase change material 25. Similarly, as Figure 3D shown, the setting of the accommodating cavity is the same as that in Figure 3B , but the setting of the phase change material is different. Specifically, the phase change points of the phase change material 21, the phase change material 22, the phase change material 23, and the phase change material 24 are the same, the phase change point of the phase change material 25 is different from the phase change points of the other four phase change materials, and the phase change points of the phase change material 21, the phase change material 22, the phase change material 23, and the phase change material 24 are less than the phase change point of the phase change material 25. Further, in some embodiments, as Figure 3E shown, the setting of the accommodating cavity is the same as that in Figure 3BSame as above, the phase change materials are arranged differently. Specifically, the phase change points of the phase change materials 21, 22, 23, 24, and 25 are the same. That is to say, the phase change materials with the same phase change point are discretely arranged, which can also improve the utilization rate of the phase change materials and further enhance the heat capacity of the power module.

[0055] Such as Figure 3F As a schematic three-dimensional structure diagram of the phase change frame, the accommodating cavities 11, 12, 13, 14, and 15 are cuboids with a certain height in the thickness direction of the power module. The accommodating cavities 11, 12, 13, 14, and 15 are arranged in sequence along the thickness direction of the power module, and the surfaces of the accommodating cavities 11, 12, 13, 14, and 15 in the thickness direction of the power module are all parallel to the surface of the chip 30 in the thickness direction of the power module.

[0056] In the second embodiment, such as Figure 4A shown, the accommodating cavities in the phase change frame are arranged at intervals from each other, and the plane where each accommodating cavity is located is perpendicular to the surface of the chip 30. The three-dimensional shape of the accommodating cavity is as Figure 4B shown. The plane where the accommodating cavity is located is the plane where the surface perpendicular to the first direction in the surface of the accommodating cavity is located. The plane where the accommodating cavity is located is perpendicular to the surface of the chip 30 in the thickness direction of the power module and extends along the second direction. The first direction, the second direction, and the thickness direction of the power module are perpendicular to each other.

[0057] The phase change frame 10 includes accommodating cavities 11, 12, 13, 14, 15, 16, 17, and 18. Among them, the accommodating cavity 11 and the accommodating cavity 18 are symmetrically arranged, the accommodating cavity 12 and the accommodating cavity 17 are symmetrically arranged, the accommodating cavity 13 and the accommodating cavity 16 are symmetrically arranged, and the accommodating cavity 14 and the accommodating cavity 15 are symmetrically arranged. The symmetric arrangement means that the distances between different accommodating cavities and the chip 30 are equal, and the symmetric arrangements are on both sides of the geometric center of the chip 30. The distances from the accommodating cavity 11 and the accommodating cavity 18, the accommodating cavity 12 and the accommodating cavity 17, the accommodating cavity 13 and the accommodating cavity 16, and the accommodating cavity 14 and the accommodating cavity 15 to the surface of the chip 30 decrease in sequence. Here, the distance from the chip 30 is the distance between the geometric center of each accommodating cavity or the geometric center of a certain accommodating wall and the geometric center of the surface of the chip 30.

[0058] Phase change materials with different phase change points are respectively arranged in each accommodation cavity. Specifically, phase change material 21 is arranged in accommodation cavity 11, phase change material 22 is arranged in accommodation cavity 12, phase change material 23 is arranged in accommodation cavity 13, phase change material 24 is arranged in accommodation cavity 14, phase change material 25 is arranged in accommodation cavity 15, phase change material 26 is arranged in accommodation cavity 16, phase change material 27 is arranged in accommodation cavity 17, and phase change material 28 is arranged in accommodation cavity 18. Among them, the phase change points of phase change material 21 and phase change material 28 are the same, the phase change points of phase change material 22 and phase change material 27 are the same, the phase change points of phase change material 23 and phase change material 26 are the same, and the phase change points of phase change material 24 and phase change material 25 are the same. The phase change points of phase change material 21 and phase change material 28, phase change material 22 and phase change material 27, phase change material 23 and phase change material 26, phase change material 24 and phase change material 25 increase in sequence. The specific settings of the phase change points of phase change material 21, phase change material 22, phase change material 23, phase change material 24, phase change material 25, phase change material 26, phase change material 27, and phase change material 28 can be set according to the temperature distribution of the chip 30 under the overload condition, so that the phase change materials in each accommodation cavity can all undergo phase change, maximizing the heat capacity of the power module.

[0059] In the third embodiment, as Figures 5A - 5B shown, the accommodation cavities in the phase change frame 10 are in a ring-shaped three-dimensional structure and are arranged in sequence from the center of the chip 30 to the edge of the chip 30. The planes where the side walls of each accommodation cavity are located are perpendicular to the surface of the chip 30. The temperatures at positions with the same distance from the chip 30 should be approximately the same. The distribution pattern of the annular accommodation cavities is approximately the same as the distribution trend of the temperature around the chip 30 in the direction extending outward from the geometric center of the chip 30 surface. Different accommodation cavities are sleeved with each other, as Figures 5A - 5B shown, the connection between adjacent side walls of each accommodation cavity is a right angle. Generally, the connection between different accommodation cavities can also be an arc.

[0060] The phase change frame 10 includes a receiving cavity 11, a receiving cavity 12, and a receiving cavity 13. Among them, the receiving cavity 11, the receiving cavity 12, and the receiving cavity 13 are nested with each other. The four side walls of each of the receiving cavity 11, the receiving cavity 12, and the receiving cavity 13 are symmetrically arranged with respect to the center of the surface of the chip 30, and the planes where the four side walls of each of the receiving cavity 11, the receiving cavity 12, and the receiving cavity 13 are located are perpendicular to the surface of the chip 30 in the thickness direction of the power module. Phase change materials with different phase change points are respectively arranged in the receiving cavity 11, the receiving cavity 12, and the receiving cavity 13. Specifically, a phase change material 21 is arranged in the receiving cavity 11, a phase change material 22 is arranged in the receiving cavity 12, and a phase change material 23 is arranged in the receiving cavity 13. Among them, the distances from the receiving cavity 11, the receiving cavity 12, and the receiving cavity 13 to the chip 30 decrease in sequence, while the phase change points of the phase change material 21, the phase change material 22, and the phase change material 23 increase in sequence. The specific settings of the phase change points of the phase change material 21, the phase change material 22, and the phase change material 23 can be set according to the temperature distribution of the chip 30 under overload conditions, so that the phase change materials in each receiving cavity can undergo phase changes, maximizing the heat capacity of the power module.

[0061] In the fourth embodiment, as Figures 6A - 6B shown, the receiving cavities in the phase change frame 10 are hemispherical arc-shaped three-dimensional structures and are arranged in sequence from the center of the chip 30 to the edge of the chip 30. Different receiving cavities are nested with each other, and the opening directions of each receiving cavity are all facing the surface of the chip 30 in the thickness direction of the power module. The temperatures at positions with the same distance from the chip 30 should be approximately the same. The distribution mode of the hemispherical arc-shaped receiving cavities is approximately the same as the distribution trend of the temperature around the chip 30 in the direction extending outward from the geometric center of the chip 30.

[0062] The phase change framework 10 includes a receiving cavity 11, a receiving cavity 12, a receiving cavity 13, and a receiving cavity 14. Among them, the shapes of the receiving cavity 11, the receiving cavity 12, the receiving cavity 13, and the receiving cavity 14 are all hemispherical arcs, and the receiving cavities are nested with each other. The cross-sections of the receiving cavity 11, the receiving cavity 12, the receiving cavity 13, and the receiving cavity 14 with the plane of the surface of the chip 30 in the thickness direction of the power module are annular, and the centers of the respective annuli are roughly coincident with the center of the surface of the chip 30. Phase change materials with different phase change points are respectively arranged in the receiving cavity 11, the receiving cavity 12, the receiving cavity 13, and the receiving cavity 14. Specifically, a phase change material 21 is arranged in the receiving cavity 11, a phase change material 22 is arranged in the receiving cavity 12, a phase change material 23 is arranged in the receiving cavity 13, and a phase change material 24 is arranged in the receiving cavity 14. Among them, the distances from the respective arc-shaped walls of the receiving cavity 11, the receiving cavity 12, the receiving cavity 13, and the receiving cavity 14 to the chip 30 decrease in sequence, while the phase change points of the phase change material 21, the phase change material 22, the phase change material 23, and the phase change material 24 increase in sequence. The temperatures at positions with the same distance from the hemispherical arc to the surface of the chip 30 should be roughly the same. The isotherms around the chip roughly form a hemispherical arc. The distribution mode of the hemispherical arc-shaped receiving cavities is roughly the same as the distribution trend of the temperature around the chip. The mutual nesting of different receiving cavities helps to arrange phase change materials with different phase change points and improve the utilization rate of the phase change materials.

[0063] Examples 1 to 4 introduced in detail the shapes and distributions of the respective receiving cavities in the phase change framework 10. It should be noted that the shapes and distributions of the receiving cavities in the phase change framework 10 are not limited to the above four cases. In order to further make the setting of the receiving cavities consistent with the working condition temperature distribution of the chip 30, the receiving cavities can be further divided. The receiving cavities can be set in a grid shape and further divided into multiple sub-receiving cavities. For example, the receiving cavity 11 in Example 2 is cut into a plurality of grid structures in the second direction and the thickness direction. The refined receiving cavities can further arrange phase change materials with different phase change points to improve the utilization rate of the phase change materials.

[0064] In the fifth embodiment, generally, the power module needs to cooperate with a radiator to take the heat in the chip out of the chip by using the radiator, as Figure 7A shown. A first radiator 40 is provided on the second surface of the chip 30, and the phase change module includes a first phase change module. Since the heat dissipation effect of the phase change material is poor, the setting of the phase change material should be minimized on the heat dissipation path. Therefore, the first phase change module is arranged on the first surface of the chip 30 to make the first phase change module in contact with the first surface of the chip 30, and the radiator is arranged on the second surface opposite to the first surface of the chip 30, which helps to improve the heat dissipation effect.

[0065] Generally, there is current flow on the first surface of the chip 30. Therefore, the current of the chip 30 will flow through the accommodating frame. Since the conductivity of the phase change material is poor, in order to enable the accommodating frame 10 to provide a better current-carrying path for the chip 30, a current-carrying part is provided in the accommodating frame 10. The current-carrying part is used to provide a path for the current in the chip 30. The current-carrying part is arranged on the side of the accommodating frame 10 of the phase change module close to the chip. The content of the phase change material per unit volume in the current-carrying part is less than the content of the phase change material per unit volume in other parts of the accommodating frame 10. As Figure 7B shown, the accommodating frame 10 includes an accommodating cavity 11, an accommodating cavity 12, an accommodating cavity 13, an accommodating cavity 14, and an accommodating cavity 15. Among them, the current-carrying part is approximately located at the positions of the accommodating cavities 14 and 15 in the accommodating frame 10. In terms of the height setting of the accommodating cavity, the height of the accommodating cavities 14 and 15 in the thickness direction of the power module is less than the height of the accommodating cavities 11, 12, and 13 in the thickness direction of the power module. The volumes of the accommodating cavities 14 and 15 are also smaller than the volumes of the accommodating cavities 11, 12, and 13. Therefore, the content of the phase change material in the accommodating cavities 14 and 15 is less than the content of the phase change material in the accommodating cavities 11, 12, and 13. Further, as Figure 7C shown, the accommodating frame 10 includes an accommodating cavity 11, an accommodating cavity 12, an accommodating cavity 13, and an accommodating cavity 14. Among them, the current-carrying part is approximately located at the position of the accommodating cavity 14 in the accommodating frame 10. No phase change material is provided in the accommodating cavity 14. In terms of the height setting of the accommodating cavity, the height of the accommodating cavity 14 in the thickness direction of the power module may be the same as or different from the height of other accommodating cavities. Further, an accommodating cavity may not be provided at the position of the accommodating cavity 14, maximizing the use of the conductive performance of the accommodating frame and improving the current-carrying capacity of the current-carrying part.

[0066] In the sixth embodiment, as Figure 8A shown, when the power module needs to cooperate with the radiator, the phase change module further includes a second phase change module, and the second phase change module is arranged between the chip 30 and the first radiator 40. Since the second phase change module is arranged on the heat dissipation path of the chip 30, and the phase change material will affect the heat transfer, no phase change material is arranged on the heat dissipation path as much as possible. The accommodating frame 10 of the second phase change module includes a first heat dissipation part and a first phase change part. The first phase change part is arranged around the first heat dissipation part. The projection of the first heat dissipation part in the thickness of the power module overlaps with the first surface of the chip 30; the content of the phase change material per unit volume in the first heat dissipation part is less than the content of the phase change material per unit volume in the first phase change part. Further, no phase change material is provided in the first heat dissipation part.

[0067] The first phase change part includes accommodation cavities 71, 72, 73, 74, 75, and 76. The planes where the accommodation cavities 71, 72, 73, 74, 75, and 76 are located are parallel to the surface of the chip 30. Here, the surface of the chip 30 can be the first surface or the second surface of the chip 30. The accommodation cavity 71 and the accommodation cavity 74 are arranged in the same plane, the accommodation cavity 72 and the accommodation cavity 75 are arranged in the same plane, and the accommodation cavity 73 and the accommodation cavity 76 are respectively arranged in the same plane. The phase change points of the phase change materials in the accommodation cavity 71 and the accommodation cavity 74 are the same, the phase change points of the phase change materials in the accommodation cavity 72 and the accommodation cavity 75 are the same, and the phase change points of the phase change materials in the accommodation cavity 73 and the accommodation cavity 76 are the same. The phase change points of the phase change materials can be set according to the working condition temperature distribution of the chip 30.

[0068] In order to fully improve the heat capacity of the power module, phase change modules can be arranged on both the first surface and the second surface of the chip 30. For example, Figure 8B as shown, the first phase change module is arranged on the first surface of the chip 30, the second phase change module is arranged on the second surface of the chip 30. The arrangement of the accommodation cavities and the phase change materials in the first phase change module can refer to the arrangement of the first phase change module in Embodiment 5 Figure 7A The arrangement of the accommodation cavities and the phase change materials in the second phase change module can refer to the arrangement of the second phase change module in Embodiment 6 Figure 8A

[0069] In the seventh embodiment, for a power module with double-sided heat dissipation, such as Figure 8C as shown, the phase change module includes a first phase change module and a second phase change module. The first phase change module is arranged on the first surface of the chip 30, and the second phase change module is arranged on the second surface of the chip 30. The side of the first phase change module facing away from the chip 30 is used to arrange the second radiator 41, and the side of the second phase change module facing away from the chip 30 is used to arrange the first radiator 40. The arrangement of the accommodation cavities and the phase change materials in the first phase change module and the second phase change module can refer to the arrangement of the second phase change module in Embodiment 7 Figure 8A

[0070] In some feasible implementation manners, in order to improve the heat capacity of the power module, the relative area between the phase change module and the chip 30 can be further increased, so that the projection of the first phase change module or the second phase change module in the thickness direction of the power module covers the first surface of the chip 30. There is no limitation on the arrangement of the accommodation cavities and the phase change materials in the first phase change module or the second phase change module, and it can be any one of the phase change module arrangements in Embodiments 1 to 6.

[0071] In the eighth embodiment, such as Figure 9A ​​As shown, the power module further includes a metal-clad substrate 60, which can be disposed on the surface of the chip 30. The metal-clad substrate 60 is in contact with the surface of the chip 30. The phase change module is disposed on the other surface of the chip 30 and is disposed opposite to the metal-clad substrate 60. A radiator 40 is configured to be disposed on the side of the metal-clad substrate 60 facing away from the chip 30. The heat generated by the chip 30 is taken away by the radiator 40 through the metal-clad substrate 60. The metal-clad substrate can be a three-layer substrate such as a direct bond copper (DBC) substrate, an active metal brazed copper (AMB, such as Al2O3-AMB, Si3N4-AMB or AlN-AMB) substrate, or an insulated metal substrate (IMS). The upper and lower layers of the three-layer substrate are conductive and heat-conductive materials. The lower layer close to the power chip can not only provide a channel for the flow of the internal current of the power chip, but also timely conduct the heat generated by the power chip. The upper layer close to the radiator can mainly provide protection for the power chip and reduce the impact of external impacts on the power chip. The middle layer is an insulating layer, which can prevent the conductive and heat-conductive materials in the lower layer from being electrically connected to the radiator and prevent problems such as short circuits in the chip. However, since the lower layer of the three-layer substrate, such as DBC, generally uses a copper layer to connect to the power chip, the copper layer in the lower layer is relatively thin, which has limited improvement in transient thermal performance, resulting in a small effective thermal diffusion area and non-optimal steady-state thermal performance.

[0072] In some feasible embodiments, as Figure 9B shown, the phase change module is disposed between the chip 30 and the radiator 40, and the metal-clad substrate 60 is disposed on the side of the phase change module facing away from the chip 30.. The heat generated by the chip 30 is conducted to the metal-clad substrate 60 through the heat dissipation part of the phase change module and is finally taken away by the radiator 40.

[0073] In the ninth embodiment, as Figure 10 shown, the power module further includes a plastic package 5. The chip 30, the phase change module, and the metal-clad substrate 60 are encapsulated in the plastic package 5, and the chip 30, the phase change module, and the metal-clad substrate 60 are stacked in sequence. The unified packaging method improves the overall structure of the power module.

[0074] The power module can include various packaging methods. In some feasible embodiments, the side of the chip 30 facing away from the phase change module is exposed on the outer surface of the plastic package 5, and at the same time, the surface of the chip 30 facing away from the phase change module is flush with the outer surface of the plastic package 5.

[0075] In some feasible embodiments, the power module further includes a plastic package body 5. A chip 30 and a metal-clad substrate 60 are disposed in the plastic package body 5. The chip 30 and the metal-clad substrate 60 are stacked. The side of the metal-clad substrate 60 facing away from the chip 30 is used to dispose a radiator 40. The phase change module is disposed outside the plastic package body 5 and on the side of the chip 30 facing away from the metal-clad substrate 60.

[0076] In some feasible embodiments, no corresponding illustration is provided in this application. The power module further includes a plastic package body 5. A chip 30 is disposed in the plastic package body 5. One side of the chip 30 in the thickness direction of the power module is used to dispose a radiator 40, and the other side of the chip 30 in the thickness direction of the power module is used to dispose a phase change module.

[0077] In the tenth embodiment, as Figure 11 shown, the power module may include two chips, the chip 30 and the chip 30'. The chip 30 and the chip 30' are disposed on the same metal-clad substrate 60. The side of the metal-clad substrate 60 facing away from the chip 30 and the chip 30' is used to dispose a radiator 40. In some feasible embodiments, the chip 30 and the chip 30' may be respectively disposed on different metal-clad substrates.

[0078] In the eleventh embodiment, a power device is provided. The power device includes at least one power module and a circuit board as in any of the above application embodiments. The power module is disposed on the circuit board. The power device is used for AC / DC conversion. In the embodiments of this application, the structure and working principle of the power module may refer to the description of the above embodiments, and will not be repeated herein.

[0079] Generally, for the power device provided in the embodiments of this application, since the power device adopts the power module in the above embodiments, and the above power module has a phase change module, the heat capacity of the power module is increased, so that the anti-junction temperature fluctuation performance of the power module is improved. When the power is overloaded, the chips can still maintain a good temperature uniformity, thereby improving the working performance of the power device when the power consumption is overloaded and improving the stability.

[0080] The above are only the specific embodiments of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed in this application, and all should be covered by the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

1. A power module, characterized in that, the power module includes: a phase change module and a chip, and the phase change module is stacked with the chip; the phase change module includes a housing frame and a phase change material, the housing frame includes at least two accommodation cavities, the at least two accommodation cavities are arranged in sequence in a direction away from the first surface of the chip, and the phase change material is arranged in the at least two accommodation cavities; the at least two accommodation cavities include a first accommodation cavity and a second accommodation cavity, the distance between the first accommodation cavity and the chip is less than the distance between the second accommodation cavity and the chip, and the phase change point of the phase change material in the first accommodation cavity is higher than the phase change point of the phase change material in the second accommodation cavity, wherein the first surface of the chip is perpendicular to the thickness direction of the power module; the phase change module includes a first phase change module, the first phase change module is arranged on the first surface of the chip, and the second surface of the chip is used to arrange a first radiator, and the first surface and the second surface are arranged opposite to each other; the housing frame of the first phase change module includes a current-carrying part, the current-carrying part is used to provide a path for the current in the chip, the current-carrying part is arranged on the side of the housing frame of the first phase change module close to the chip, and the content of the phase change material per unit volume in the current-carrying part is less than the content of the phase change material per unit volume in other parts of the housing frame of the first phase change module.

2. The power module according to claim 1, characterized in that, the at least two accommodation cavities are arranged in sequence along the thickness direction of the power module, and the plane where each accommodation cavity is located is parallel to the first surface of the chip, wherein the plane where the accommodation cavity is located is the plane of the surface of the accommodation cavity that is perpendicular to the thickness direction of the power module.

3. The power module according to claim 1, characterized in that, the at least two accommodation cavities are arranged in sequence along a first direction, the plane where each accommodation cavity is located is perpendicular to the first surface of the chip, and the first direction is perpendicular to the thickness direction of the power module, wherein the plane where the accommodation cavity is located is the plane of the surface of the accommodation cavity that is perpendicular to the first direction.

4. The power module according to claim 3, characterized in that, each of the at least two accommodation cavities is annular and is arranged in sequence from the center of the chip to the edge of the chip.

5. The power module according to claim 1, characterized in that, no phase change material is arranged in the current-carrying part.

6. The power module according to any one of claims 1-5, characterized in that, the phase change module includes a second phase change module, and the second phase change module is arranged between the chip and the first radiator; the housing frame of the second phase change module includes a first heat dissipation part and a first phase change part, the first phase change part is arranged around the first heat dissipation part, and the projection of the first heat dissipation part on the thickness of the chip overlaps with the first surface of the chip; the content of the phase change material per unit volume in the first heat dissipation part is less than the content of the phase change material per unit volume in the first phase change part.

7. The power module according to claim 6, wherein, no phase change material is provided in the first heat dissipation part.

8. The power module according to claim 5, wherein, a second heat sink is arranged on the surface of the first phase change module facing away from the chip; the accommodating frame of the first phase change module includes a second heat dissipation part and a second phase change part, the second phase change part is arranged around the second heat dissipation part, and the projection of the second heat dissipation part on the thickness of the chip overlaps with the first surface of the chip; the content of the phase change material per unit volume in the second heat dissipation part is less than the content of the phase change material per unit volume in the second phase change part.

9. The power module according to claim 5, wherein, the projection of the first phase change module in the thickness direction of the power module covers the first surface of the chip.

10. The power module according to claim 1, wherein, the power module includes a metal-clad layer substrate, the metal-clad layer substrate is stacked with the chip and is in contact with the surface of the chip; or, the metal-clad layer substrate is arranged on the surface of the phase change module facing away from the chip.

11. The power module according to claim 1, wherein, the accommodating frame is a metal frame or a diamond frame, and the phase change material is any one or more of elemental metals, alloys, organic substances, and inorganic salts.

12. A power device, wherein, the power device includes at least one power module according to any one of claims 1-11 and a circuit board, and the power module is arranged on the circuit board.

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