Power module packaging structure

Abstract

The utility model provides a power module packaging structure. The power module packaging structure comprises a substrate; the metal gasket is brazed on the substrate; the plastic packaging layer is located on the substrate and covers the side surface of the metal gasket, the upper surface of the metal gasket is exposed, and the exposed upper surface of the metal gasket is used for achieving input and lead-out of electric signals. The power module packaging structure of the utility model can shorten the paths of the commutation loop and the driving loop, reduce the stray inductance of the power module packaging structure, and improve the overall performance of the power module packaging structure.

Description

Technical Field

[0001] This utility model relates to the field of integrated circuit technology, and in particular to a power module packaging structure. Background Technology

[0002] Electrical performance is a crucial part of power module packaging. A reasonable electrical connection method not only needs to maximize the performance of the chip, but also needs to reduce costs and extend the life of the module.

[0003] Currently, the external electrical connections of power module packages mainly adopt the lead frame method. The lead frame is soldered onto an AMB (Active Metal Brazing) or DBC (Direct Bonding Copper) substrate to achieve the purpose of electrical signal input and output. However, the exposed terminals on the outside of the module not only lengthen the entire module's loop and increase stray inductance, but also require consideration of safety regulations such as clearances and creepage distances, affecting module performance. In other words, the current external electrical connections have the following problems: First, external terminals increase the path of the overall commutation and drive loops, increasing stray inductance; second, there is a risk of delamination between the lead frame and the molding compound and solder during assembly. Utility Model Content

[0004] The purpose of this invention is to provide a power module packaging structure that shortens the path between the commutation circuit and the drive circuit of the power module packaging structure, reduces the stray inductance of the power module packaging structure, and improves the overall performance of the power module packaging structure.

[0005] To achieve the above and other related objectives, this utility model provides a power module packaging structure, including:

[0006] substrate;

[0007] Metal gaskets, which are brazed onto the substrate;

[0008] A molding layer is located on the substrate and covers the side surface of the metal pad, exposing the upper surface of the metal pad. The exposed upper surface of the metal pad is used to realize the input and output of electrical signals.

[0009] Optionally, in the power module packaging structure, a power chip is soldered onto the substrate, and the molding compound covers the power chip.

[0010] Optionally, in the power module packaging structure, the number of metal pads is multiple.

[0011] Optionally, in the power module packaging structure, the cross-sectional shape of the metal pad parallel to the substrate is circular or rounded rectangle.

[0012] Optionally, in the power module packaging structure, the side surface of the metal pad is provided with a first groove.

[0013] Optionally, in the power module packaging structure, there are multiple first grooves, and the first groove is a V-shaped groove.

[0014] Optionally, in the power module packaging structure, a second groove is provided on the bottom surface of the metal pad.

[0015] Optionally, in the power module packaging structure, the second groove is a cross-shaped groove.

[0016] Optionally, in the power module packaging structure, the upper surface of the metal pad is provided with positioning holes.

[0017] Optionally, in the power module packaging structure, the substrate is an active metal brazing substrate or a direct copper-clad ceramic substrate.

[0018] Optionally, in the power module packaging structure, the metal pad is a copper pad.

[0019] Compared with the prior art, the technical solution of this utility model has the following beneficial effects:

[0020] The power module packaging structure provided by this utility model includes a metal pad, which replaces the lead frame in the prior art as the main component of the power module packaging structure. The side surface of the metal pad is covered by a plastic encapsulation layer, with only the top surface exposed. This means that the metal pad is directly led out from inside the power module packaging structure, which can shorten the path between the commutation circuit and the drive circuit, reduce the stray inductance of the power module packaging structure, and improve the overall performance of the power module packaging structure.

[0021] Secondly, the power module packaging structure of this utility model has a cross groove on the bottom surface of the metal pad, which can enhance the welding effect.

[0022] Furthermore, the power module packaging structure of this invention has multiple V-grooves on the side surface of the metal pad, which can enhance the bonding with the molding layer, reduce the risk of delamination to a greater extent, and reduce the risk of the power module packaging structure being corroded by moisture.

[0023] In addition, the power module packaging structure of this utility model has positioning holes on the upper surface of the metal pad, which improves the positional accuracy of each component during the process assembly and enhances the overall practicality and aesthetics of the power module packaging structure. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a power module packaging structure;

[0025] Figure 2 This is a plan view of a metal gasket brazed onto a substrate according to an embodiment of the present invention;

[0026] Figure 3 This is a perspective view of a metal gasket brazed onto a substrate according to an embodiment of the present invention;

[0027] Figure 4 This is a perspective view of a cuboid metal gasket according to an embodiment of the present invention;

[0028] Figure 5 This is a plan view of a metal gasket with positioning holes according to an embodiment of the present invention;

[0029] Figure 6 This is a plan view of a metal gasket with positioning holes according to another embodiment of the present invention;

[0030] Figure 7 This is a perspective view of a cylindrical metal gasket according to an embodiment of the present invention;

[0031] Figure 8 This is a plan view of the bottom surface of a cylindrical metal gasket according to an embodiment of the present invention;

[0032] in Figure 1 middle:

[0033] 01-Module, 021-Power terminal, 022-Signal terminal;

[0034] Figures 2-8 middle:

[0035] 10 - Substrate, 201 - Rectangular metal pad, 2011 - Positioning hole, 2012 - First groove, 202 - Cylindrical metal pad, 2021 - Second groove. Detailed Implementation

[0036] See Figure 1The current power module packaging structure includes a molded module 01 and exposed power terminals 021 and signal terminals 022. This power module packaging structure includes a substrate, a chip soldered onto the substrate, a lead frame, and a molding compound that encapsulates the substrate, chip, and part of the lead frame. The molding compound, substrate, chip, and partially encapsulated lead frame constitute module 01, while the exposed lead frame forms the power terminals 021 and signal terminals 022. The exposed terminals not only lengthen the circuit of module 01 and increase stray inductance, but also require consideration of safety regulations such as clearances and creepage distances, affecting module performance. In other words, the current external electrical connection has the following problems: external terminals increase the path of the overall commutation and drive circuits, increasing stray inductance; and the lead frame poses a risk of delamination from the molding compound and solder during assembly.

[0037] The power module packaging structure proposed in this utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of this utility model will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of this utility model.

[0038] See Figure 2 and Figure 3 This utility model provides a power module packaging structure, which specifically includes:

[0039] substrate 10;

[0040] Metal gaskets are brazed onto the substrate 10;

[0041] A molding layer (not shown in the figure) is located on the substrate 10 and covers the side surface of the metal pad, exposing the upper surface of the metal pad. The exposed upper surface of the metal pad is used to realize the input and output of electrical signals.

[0042] In this embodiment, the substrate 10 is preferably an active metal brazing substrate or a direct copper-clad ceramic substrate, but is not limited thereto. Power chips can be soldered onto the substrate 10 in this embodiment, and the number of power chips is at least one. The specific model and quantity of the power chips can be set according to process requirements. The soldering position of the power chips can also be set according to process requirements. In other embodiments, other chips can also be soldered onto the substrate 10, specifically according to process requirements.

[0043] In this embodiment, the main function of the metal pad is to conduct electricity and provide support. The metal pad can be any conductive metal, but copper is preferred because it has excellent conductivity, low price, and high hardness.

[0044] The metal pads are brazed onto the substrate 10 using solder. The solder can be a tin-containing multi-element solder, including Sn(tin)Ag(silver)Cu(copper), Pb(lead)SnAg, or SnAgCuSb(antimony), etc., preferably PbSnAg. In this embodiment, the number of metal pads is preferably multiple, for example... Figure 2 Eight metal pads are disposed on the substrate 10.

[0045] The metal pads can be soldered to the substrate 10 in different shapes and independently, serving as power terminals or signal terminals in the power module packaging structure. The shape of the metal pads can be cylindrical, preferably cylindrical or cuboid, for example... Figure 2 The metal pads 201 and 202 are rectangular and cylindrical, respectively. The rectangular metal pad 201 preferably has a rounded rectangular cross-section parallel to the upper surface of the substrate 10, and the cylindrical metal pad 202 preferably has a circular cross-section parallel to the upper surface of the substrate 10. All cross-sections mentioned below refer to those parallel to the upper surface of the substrate 10. In this embodiment, the shape of the metal pads can depend on the application and functional requirements, and therefore the shape of the metal pads can be selected according to the application and functional requirements. For example, metal pads with a rounded rectangular cross-section generally have better mechanical strength and stability, are suitable for applications requiring high stress, and may also more easily achieve a larger contact area, thereby reducing contact resistance; while metal pads with a circular cross-section may provide better flexibility and shock resistance in certain situations, and may exhibit better signal transmission characteristics in high-frequency applications, with a smaller contact area. Therefore, metal gaskets with rounded rectangular cross-sections have a larger volume and cross-sectional area, making them suitable as power terminals; while metal gaskets with circular cross-sections have a smaller volume and cross-sectional area, making them suitable as signal terminals. The cross-sectional area settings of the cuboid metal gasket 201 and the cylindrical metal gasket 202 mainly depend on the end customer's requirements for subsequent soldering area. For example, the cross-sectional area (length × width) of the cuboid metal gasket 201 can be set to (20 × 5) mm. 2 (15×5)mm 2 (11×5)mm 2 And so on. For example, the cross-sectional area of ​​the cylindrical metal gasket 202 can be set to Π(1.5). 2 mm 2 That is, the cross-sectional diameter of the cylindrical metal gasket 202 can be set to 1.5mm.

[0046] Rectangular metal spacers 201 and cylindrical metal spacers 202 can be simultaneously brazed onto the substrate 10. The position and number of the rectangular metal spacers 201 and cylindrical metal spacers 202 can be set according to process requirements. For example... Figure 1 In this process, there are three rectangular metal pads 201 brazed on the substrate 10, and five cylindrical metal pads 202 brazed on the substrate 10.

[0047] See Figure 4 In this embodiment, the side surface of the metal gasket can optionally be provided with a first groove 2012. The first groove 2012 can be a groove of any shape. Since the process of forming a V-groove on the side surface is relatively simple, the first groove 2012 is preferably a V-groove. The number of first grooves 2012 is preferably multiple. Since the rectangular metal gasket 201 has a relatively large volume, the first groove 2012 can be provided on its side surface to enhance the adhesion with the molding layer and improve the purpose of delamination and moisture erosion prevention. The cylindrical metal gasket 202, due to its smaller volume, does not need to have a first groove on its side surface. For example, Figure 4 Multiple V-grooves are arranged in parallel on the side surface of the rectangular metal gasket 201.

[0048] Continue reading Figure 4 In this embodiment, the upper surface of the metal pad can be provided with positioning holes 2011. The positioning holes 2011 can improve the positional accuracy of each component during the assembly process, enhancing the overall practicality and aesthetics of the power module packaging structure. In this embodiment, the positioning holes are preferably provided on the upper surface of the cuboid metal pad 201. The number of positioning holes 2011 provided on the upper surface of the cuboid metal pad 201 is preferably one, and preferably a group of cuboid metal pads 201 located diagonally opposite each other on the substrate 10 have the positioning holes 2011 on their upper surfaces. Other metal pads may not have the positioning holes 2011. This can meet process requirements while also preventing mistakes and reducing costs. Please refer to... Figure 3 The positioning hole 2011 in this embodiment can be circular in shape, for example... Figure 5 The positioning hole 2011 is circular in shape. In another embodiment, the positioning hole 2011 may be elliptical in shape, for example... Figure 6 The positioning hole 2011 is elliptical in shape. Of course, the positioning hole 2011 can also be other shapes, which will not be elaborated here.

[0049] See Figure 7 and Figure 8In this embodiment, the metal pad can optionally have a second groove 2021 formed on its bottom surface. The second groove 2021 can be a groove of any shape. Since forming a cross groove on the bottom surface is simple, the second groove 2021 is preferably a cross groove. Further, in this embodiment, a cross groove is preferably formed on the bottom surface of the cylindrical metal pad 202. Since the cross-sectional area of ​​a circular metal pad is relatively small, the contact area with the solder on the substrate is relatively small, which easily leads to the risk of delamination between the metal pad and the solder. Therefore, in this embodiment, the cylindrical metal pad 202 can increase the contact area with the solder by forming a second groove 2021 on its bottom surface to achieve better solder climbing effect and avoid delamination between the metal pad and the solder.

[0050] In this embodiment, the molding compound is formed by injection molding. The molding compound covers the substrate 10 and also covers the side surface of the metal pad, exposing only the upper surface of the metal pad. The exposed upper surface of the metal pad is used for input and output of electrical signals. In this embodiment, the metal pad is directly led out from inside the power module packaging structure (i.e., inside the molding compound), meaning the terminals do not need to extend outside the molding compound. This shortens the path between the commutation circuit and the drive circuit, reduces stray inductance of the power module packaging structure, and improves the overall performance of the power module packaging structure. The molding compound also covers the power chip on the substrate 10. In this embodiment, the material of the molding compound can be a conventional molding compound, and the injection molding process can be a conventional injection molding process, which will not be elaborated here.

[0051] In summary, the power module packaging structure provided by this utility model incorporates a metal pad that replaces the lead frame in the prior art. This metal pad extends directly from inside the power module packaging structure, shortening the path between the commutation circuit and the drive circuit, reducing stray inductance, and improving the overall performance of the power module packaging structure. Furthermore, the cross-shaped groove on the bottom surface of the metal pad enhances the soldering effect, and the multiple V-grooves on the side surface of the metal pad enhance its adhesion to the molding compound, further reducing the risk of delamination and minimizing the risk of moisture corrosion to the power module packaging structure.

[0052] In addition, the power module packaging structure of this utility model has positioning holes on the upper surface of the metal pad, which improves the positional accuracy of each component during the process assembly and enhances the overall practicality and aesthetics of the power module packaging structure.

[0053] Furthermore, it is understood that although the present invention has been disclosed above with reference to preferred embodiments, these embodiments are not intended to limit the present invention. For any person skilled in the art, many possible variations and modifications can be made to the present invention's technical solutions using the disclosed technical content, or equivalent embodiments can be modified accordingly, without departing from the scope of the present invention's technical solutions. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention's technical solutions, shall still fall within the protection scope of the present invention's technical solutions.

[0054] Furthermore, it should be understood that this invention is not limited to the specific methods, compounds, materials, manufacturing techniques, uses, and applications described herein, which can vary. It should also be understood that the terminology described herein is used only to describe particular embodiments and not to limit the scope of this invention. It must be noted that the singular forms “a,” “an,” and “the” used herein and in the appended claims include plural bases unless the context clearly indicates otherwise. Thus, for example, a reference to “a step” means a reference to one or more steps, and may include secondary steps. All conjunctions used should be understood in the broadest sense. Therefore, the word “or” should be understood to have the definition of logical “or” rather than logical “exclusive”, unless the context clearly indicates otherwise. The structures described herein will be understood to also refer to functional equivalents of that structure. Language that can be interpreted as approximate should be understood in that way, unless the context clearly indicates otherwise.

Claims

1. A power module package structure, characterized by, The application relates to a substrate, a metal pad brazed on the substrate, a bottom surface of the metal pad being provided with a second groove, a plastic sealing layer located on the substrate and covering side surfaces of the metal pad, an upper surface of the metal pad being exposed, and the exposed upper surface of the metal pad being used for input and output of electric signals. The substrate is welded with a power chip, and the plastic sealing layer covers the power chip. The number of the metal pads is multiple. The cross section of the metal pad parallel to the substrate is circular or circular-rectangular.

2. The power module package structure of claim 1, wherein, The side surface of the metal pad is provided with a first groove.

3. The power module package structure of claim 1, wherein, The number of the first grooves is multiple, and the first grooves are V-shaped grooves.

4. The power module package structure of claim 1, wherein, The second groove is a cross-shaped groove.

5. The power module package structure of claim 1, wherein, The upper surface of the metal pad is provided with a positioning hole.

6. The power module package structure of claim 5, wherein, The substrate is an active metal brazing substrate or a direct copper clad ceramic substrate.

7. The power module package structure of claim 1, wherein, The metal pad is a copper pad.

8. The power module package structure of claim 1, wherein, ​ 9. The power module package structure of claim 1, wherein, ​ 10. The power module package structure of claim 1, wherein, ​

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