Novel packaging structure of power module

Abstract

The utility model provides a novel packaging structure of a power module. The novel packaging structure comprises a heat radiation bottom plate, a first metal connection layer, a second metal connection layer and a substrate. Wherein a plane is arranged on the heat dissipation bottom plate; the first metal connecting layer, the second metal connecting layer and the substrate are sequentially arranged on the plane. The packaging structure provided by the utility model improves the heat dissipation performance of the power module and the stability in use.

Description

Technical Field

[0001] The utility model relates to a novel packaging structure of a power module. Background Art

[0002] With the rapid development of materials and processes used to manufacture power semiconductor devices, the packaging of power modules driven under high current and high voltage is also developing rapidly, making power modules widely used in motor drives and power electronics fields including electric vehicles, washing machines, air conditioners, etc.

[0003] The existing power module packaging process is to set a soldering sheet or thermal grease on the heat dissipation base plate, and then weld the AMB substrate or DBC substrate to the heat dissipation base plate through the soldering sheet to complete the packaging process. In the above packaging process, the heat dissipation base plate is a copper heat dissipation base plate, which is heavy and cannot meet the requirements (lightweight / flight, etc.). Moreover, the thermal conductivity of the soldering sheet is 58W / m·K, and the thermal conductivity of the thermal grease is usually between 0.8 and 5.0W / m·K. The heat dissipation performance of the soldering sheet and the thermal grease cannot achieve the required high heat dissipation effect. Moreover, the reflow soldering temperature of the soldering sheet is relatively high, about 217°C. During the welding process, the thermal deformation of the material increases, which will reduce the reliability of the product. Therefore, designing a packaging structure of a new power module with good heat dissipation performance and stable performance is the research direction of the utility model. Utility Model Content

[0004] The utility model provides a new packaging structure of a power module, which can effectively solve the above problems.

[0005] The utility model is achieved in this way:

[0006] A novel packaging structure of a power module, the packaging structure comprising:

[0007] A heat dissipation base plate, a first metal connection layer, a second metal connection layer and a substrate;

[0008] Among them, there is a plane on the heat dissipation base plate; the first metal connection layer, the second metal connection layer and the substrate are arranged in sequence on the plane; the second metal connection layer is an indium sheet and is welded on the first metal connection layer.

[0009] As a further improvement, the thermal conductivity of the indium sheet is 83W / m·K-86W / m·K.

[0010] As a further improvement, the first metal connection layer is a metal plating layer, and the metal plating layer is arranged on the heat dissipation base plate by electroplating.

[0011] As a further improvement, the metal plating layer is nickel, silver, copper or gold.

[0012] As a further improvement, the metal plating layer is nickel, and the thickness of the nickel is 5-25 μm.

[0013] As a further improvement, the substrate is an AMB substrate or a DBC substrate, and is welded to the heat dissipation base plate through the second metal connection layer.

[0014] As a further improvement, the heat dissipation base plate is an aluminum base plate.

[0015] The beneficial effects of the utility model are:

[0016] (1) The utility model arranges the first metal connection layer (metal plating), the second metal connection layer and the substrate in sequence on the surface layer of the heat dissipation base plate, thereby completing the packaging of the power module. At the same time, the second metal connection layer uses an indium sheet. The indium sheet has a higher thermal conductivity than a solder sheet or thermal conductive silicone grease, and has better heat dissipation performance; the aluminum heat sink of the indium sheet + plated metal is lighter than the solder sheet + copper heat sink, and has a better cost-effectiveness; the indium sheet has a lower melting point temperature than the solder sheet. In the brazing process, the lower welding temperature can reduce the thermal deformation of the material during the welding process, making the product reliability more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solution of the implementation mode of the utility model, the drawings required for use in the implementation mode will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic diagram of the packaging structure of the power module of the utility model.

[0019] Figure 2 It is a schematic diagram of the existing power module packaging structure.

[0020] Description of Figure Numbers:

[0021] 1. Heat dissipation base plate; 2. First metal connection layer; 3. Second metal connection layer; 4. Base plate. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the utility model. Therefore, the following detailed description of the embodiments of the utility model provided in the drawings is not intended to limit the scope of the utility model for which protection is sought, but merely represents the selected embodiments of the utility model. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the utility model.

[0023] In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0024] Reference Figure 1 As shown, a new packaging structure of a power module includes:

[0025] Heat dissipation base plate 1, first metal connection layer 2, second metal connection layer 3 and substrate 4;

[0026] There is a plane on the heat dissipation base plate 1; the first metal connection layer 2, the second metal connection layer 3 and the base plate 4 are arranged in sequence on the plane.

[0027] Among them, the heat sink base plate 1 is an aluminum base plate. The weight of the aluminum heat sink base plate 1 is generally lighter than that of the traditional copper heat sink base plate, and the cost performance is more advantageous. At the same time, the thermal expansion coefficient of aluminum may be closer to that of semiconductor chips and ceramic substrates, which helps to reduce thermal stress during thermal cycles, thereby improving the reliability and life of the module. In addition, aluminum is easier to process into the required shape and size, and the processing cost is low. Secondly, the use of aluminum base plates helps to achieve better thermal management design, especially in applications that require more complex shapes to improve heat dissipation efficiency. Finally, aluminum base plates may help to improve the integration of power modules and support more compact designs.

[0028] Therefore, the combination of an aluminum base plate and an indium sheet with high thermal conductivity and low melting point is more conducive to the use of the power module and improves the overall performance of the power module.

[0029] The second metal connection layer 3 is an indium sheet or an indium alloy. At the same time, the indium sheet or the indium alloy is welded on the first metal connection layer 2; in one embodiment, in order to improve the heat dissipation and reliability of the power module, the second metal connection layer 3 is an indium sheet. The thermal conductivity of the indium sheet is 83W / m·K-86W / m·K, and the thermal conductivity of the solder sheet is 58W / m·K. The thermal conductivity of the indium sheet is higher than that of the solder sheet, so that the heat generated by the power module can be quickly dissipated; the melting point of the indium sheet is about 157 degrees, and the melting point of the solder sheet is about 217 degrees. Therefore, the indium sheet is arranged on the heat dissipation base plate 1 to quickly dissipate the heat generated by the power module; and the higher the thermal conductivity, the better the performance of the power module. Furthermore, the melting point of the second metal connection layer 3 is lower than the melting point of the solder sheet, so that the thermal deformation of the material during the welding process can be reduced, while improving the reliability of the product.

[0030] Furthermore, the thermal conductivity of indium sheet is higher than that of solder sheet and thermal grease, and its heat dissipation performance is better; the aluminum heat sink of indium sheet + plated metal is lighter than that of solder sheet + copper heat sink, and has a better cost-effectiveness; the melting point of the second metal connection layer is lower than that of the solder sheet. In the brazing process, the lower welding temperature can reduce the thermal deformation of the material during the welding process, making the product reliability more stable.

[0031] The first metal connection layer 2 is a metal coating, and the metal coating is disposed on the heat sink 1 by electroplating. The reason for this arrangement is that the surface of the heat sink 1 made of aluminum is not weldable, so a metal layer needs to be electroplated on the surface of the heat sink 1 for a subsequent welding process.

[0032] Wherein, the metal coating is nickel, silver, copper or gold. In one embodiment, the metal coating is preferably nickel, and the thickness of nickel is 5-25 μm. In one embodiment, the thickness of nickel is about 7 μm. If the metal coating is too thick, the coating and the substrate may peel off due to mismatch of thermal expansion coefficient when the temperature changes. At the same time, too thick metal coating may affect the wettability of welding, making the welding process difficult and increasing the risk of welding defects; if the metal coating is too thin, it may affect welding.

[0033] When actually installing the first metal connection layer 2 and the second metal connection layer 3, the surface of the first metal connection layer 2 needs to be thoroughly cleaned to remove oil, oxides and other contaminants, and then welding is performed. When welding, such as soft soldering, solder needs to be placed between the indium sheet and the first metal connection layer 2 before welding. The temperature needs to be controlled during the welding process to avoid damaging the components or materials below. After installation, post-processing is required, such as removing excess debris or adhesives, followed by secondary cleaning or application of a protective coating.

[0034] The substrate 4 is an AMB substrate or a DBC substrate, and is welded to the heat dissipation base plate 1 through the second metal connection layer 3 .

[0035] Reference Figure 2 As shown, the existing power module packaging structure includes a copper heat sink, a solder sheet (thermal grease) and an AMB substrate or a DBC substrate. In actual use, as mentioned in the background technology, the copper heat sink substrate is relatively heavy and cannot meet the requirements (lightweight / flight, etc.); the thermal conductivity of the solder sheet is 58W / m·K, and the thermal conductivity of the thermal grease is usually between 0.8 and 5.0W / m·K. The heat dissipation performance of the solder sheet and the thermal grease cannot achieve the high heat dissipation effect of the second metal connection layer; the solder sheet reflow soldering temperature is relatively high, about 217°C, and the thermal deformation of the material increases during the soldering process, which will reduce the reliability of the product. Compared with this case, the existing packaging structure cannot meet the requirements of users during actual use. Therefore. This case is more worthy of promotion and use.

[0036] The above description is only the preferred implementation of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A new packaging structure of a power module, characterized in that: The packaging structure comprises: A heat dissipation base plate (1), a first metal connection layer (2), a second metal connection layer (3) and a substrate (4); The heat dissipation base plate (1) has a plane on it; the first metal connection layer (2), the second metal connection layer (3) and the substrate (4) are arranged in sequence on the plane; The second metal connection layer (3) is an indium sheet and is welded on the first metal connection layer (2).

2. The novel packaging structure of a power module according to claim 1, characterized in that: The thermal conductivity of the indium sheet is 83W / m·K-86W / m·K.

3. The novel packaging structure of a power module according to claim 1, characterized in that: The first metal connection layer (2) is a metal plating layer, and the metal plating layer is arranged on the heat dissipation base plate (1) by electroplating.

4. The novel packaging structure of a power module according to claim 3, characterized in that: The metal plating layer is nickel, silver, copper or gold.

5. The novel packaging structure of a power module according to claim 4, characterized in that: The metal plating layer is nickel, and the thickness of the nickel is 5-25 μm.

6. The novel packaging structure of a power module according to claim 1, characterized in that: The substrate (4) is an AMB substrate or a DBC substrate, and is welded to the heat dissipation base plate (1) via the second metal connection layer (3).

7. The novel packaging structure of a power module according to claim 1, characterized in that: The heat dissipation base plate (1) is an aluminum base plate.

Images