A power module

Abstract

This application discloses a power module including a first connector, encapsulating resin, a chip, an AMB substrate, and a heat sink. The first connector includes a body, a roughening layer, and a connecting portion. The body includes a first surface and a second surface. The roughening layer includes a first roughening layer and a second roughening layer. The first surface has a first roughening layer, and the second surface has a second roughening layer. The connecting portion is located on the second surface without the second roughening layer. The encapsulating resin covers the first and second roughening layers. One end of the chip is connected to the connecting portion, and the other end of the chip is connected to the AMB substrate. The heat sink is connected to the end of the AMB substrate furthest from the chip. By providing a roughening layer on the surface of the body, this application increases the bonding force between the body and the encapsulating resin during connection, reduces the formation of interface voids, and improves the delamination phenomenon of the encapsulating resin under the influence of temperature, humidity, or mechanical stress.

Description

Technical Field

[0001] This application relates to the field of electronic device technology, and in particular to a power module. Background Technology

[0002] Power modules (such as IGBT modules, SiC modules, and IPM modules) are core components of power electronic systems. In packaging, copper clips (copper strips or bars) are used to replace traditional aluminum wire bonding for high-current interconnects between power semiconductor chips (such as IGBTs and diodes) and substrates (such as DBCs and AMBs). This improves the current-carrying capacity of the power module and reduces thermal resistance and parasitic inductance. Copper clips in power modules such as IGBT and SiC modules serve as high-current transmission and heat dissipation channels. A typical structure consists of a 0.2-0.8mm thick C11000 copper strip, which connects the chip electrodes to external terminals via soldering and requires encapsulation with epoxy resin to form a mechanically stable and hermetically tight protective structure.

[0003] However, traditional copper clips are often untreated before bonding with epoxy resin encapsulation, resulting in weak adhesion. Alternatively, silver plating on the copper leadframe surface is used for bonding with the epoxy resin encapsulation. These methods, under the stress of subsequent product processing and use, as well as the stress of the encapsulation itself, lead to insufficient interfacial adhesion between the silver plating layer on the metal surface and the outer epoxy molding compound in both traditional leadframe and copper clip-based plastic-encapsulated devices. This makes them prone to delamination under temperature, humidity, or mechanical stress. Once delamination occurs, it becomes a pathway for moisture intrusion or a source of delamination expansion, ultimately leading to device failure, poor long-term reliability, and difficulty meeting the long-term reliability requirements of electronic devices under extreme operating conditions.

[0004] Moreover, the surface treatment of traditional copper clips usually adopts a uniform process, without selective surface treatment for the needs of different parts of the product. When the structure after overall surface treatment is connected to the chip, it will scratch the chip surface and reduce the long-term reliability of the power module. Utility Model Content

[0005] This application aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, the purpose of this application is to provide a power module that solves the problem in the prior art where delamination easily occurs between the copper clip surface and the epoxy resin encapsulation, leading to poor reliability of the molded device.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows: A power module, comprising: A first connector, comprising a body, a roughening layer, and a connecting portion, wherein the body comprises a first surface and a second surface, the roughening layer comprises a first roughening layer and a second roughening layer, the first surface is provided with the first roughening layer, the second surface is provided with the second roughening layer, and the connecting portion is provided on the second surface where the second roughening layer is not provided. An encapsulating resin, wherein the encapsulating resin coats the first roughened layer and the second roughened layer; A chip, one end of which is connected to the connecting portion; AMB substrate, wherein the AMB substrate is connected to the other end of the chip; A heat dissipation base plate is connected to the end of the AMB substrate furthest from the chip.

[0007] According to some embodiments of this application, the roughness Ra of the first roughening layer and the second roughening layer ranges from 0.11 to 0.35. The shear strength of the first roughened layer and the second roughened layer ranges from 10.45 to 17.23 MPa.

[0008] According to some embodiments of this application, the thicknesses of the first roughening layer and the second roughening layer range from 0.3 to 3. .

[0009] According to some embodiments of this application, the first rough layer and the second rough layer are protruding structures or petal-shaped sheet structures arranged in a regular granular pattern.

[0010] According to some embodiments of this application, the thickness of the body ranges from 0.3 to 0.6 mm.

[0011] According to some embodiments of this application, the structure of the body is one of the following: bent type, straight type, or frame type.

[0012] According to some embodiments of this application, the power module is further provided with a first solder layer, and the connection portion is connected to the chip through the first solder layer.

[0013] According to some embodiments of this application, the AMB substrate includes a first connection layer, a second connection layer, and a third connection layer, which are sequentially disposed along the thickness direction of the AMB substrate. The first connection layer is connected to the chip, and the third connection layer is connected to the heat dissipation base plate.

[0014] According to some embodiments of this application, the power module further includes a second solder layer and a third solder layer, the chip is connected to the first connection layer through the second solder layer, and the third connection layer is connected to the heat dissipation base plate through the third solder layer.

[0015] According to some embodiments of this application, the power module further includes a second connector and a fourth solder layer. One end of the second connector is connected to the first connector layer through the fourth solder layer, and the other end extends to the outside of the power module and is connected to an external system.

[0016] The beneficial effects of this application are: The power module of this application, by providing a first roughening layer and a second roughening layer on the first and second surfaces of the body respectively, can increase the bonding force between the body and the encapsulating resin when connected to the encapsulating resin, reduce the formation of interface voids, and improve the phenomenon of delamination of the encapsulating resin under the action of temperature, humidity, or mechanical stress. Furthermore, placing the structure after the body and encapsulating resin are connected within the power module can improve the product yield and reliability of the power module.

[0017] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0018] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the power module structure of this application.

[0019] Figure 2 This is a schematic diagram of the main structure of this application.

[0020] Figure 3 This is a schematic diagram of the structure of the first connector in this application.

[0021] Figure 4 This is a schematic diagram of the connection between the first connector and the chip in this application.

[0022] Figure 5 This is a schematic diagram of the roughened layer formed by the roughening process observed under an electron microscope (SEM). Figure 1 .

[0023] Figure 6 The diagram shows the roughened layer formed by the browning process observed under an electron microscope (SEM). Figure 2 .

[0024] Figure label: 100, First connector; 110, Body; 120, First roughened layer; 130, Second roughened layer; 140, Connecting part; 200. Encapsulating resin; 300. Chip; 400, Terminal; 410, Fourth solder layer; 500, AMB substrate; 510, First interconnect layer; 520, Second interconnect layer; 530, Third interconnect layer; 600. Heat dissipation base plate; 700, First solder layer; 800, Second solder layer; 900, Third solder layer. Detailed Implementation

[0025] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0026] In the description of this application, it should be understood that if directional descriptions are involved, such as up, down, front, back, left, right, etc., indicating the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings, it is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0027] In the description of this application, if words such as several, greater than, less than, exceeding, above, below, or within appear, "several" means one or more, "more than" means two or more, "greater than," "less than," "exceeding," etc. are understood to exclude the number itself, and "above," "below," "within," etc. are understood to include the number itself.

[0028] In the description of this application, the use of terms such as "first" and "second" is for the purpose of distinguishing technical features only, and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or the order of the technical features indicated.

[0029] In the description of this application, unless otherwise expressly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0030] Reference Figures 1 to 6 The following are specific embodiments of this application.

[0031] This application provides a power module including a first connector 100, an encapsulating resin 200, a chip 300, an AMB substrate 500, and a heat dissipation base plate 600. The first connector includes a body 110, a roughening layer 120, and a connecting portion 140. The body 110 is a copper clip, i.e., a copper strip or copper bar. The body 110 includes a first surface and a second surface. The roughening layer includes a first roughening layer 120 and a second roughening layer 130. The first surface has the first roughening layer 120, and the second surface has the second roughening layer 130. The connecting portion 140 is disposed on the second surface where the second roughening layer 130 is not provided. The connecting portion 140 is used to connect with the chip 300. The encapsulating resin 200 covers the first roughening layer 120 and the second roughening layer 130. The first roughening layer 120 and the second roughening layer 130 are used to increase the bonding force between the body 110 and the encapsulating resin 200 and reduce delamination after the encapsulating resin cures.

[0032] The first surface is the upper surface of the body 110, and the second surface is the lower surface of the body 110.

[0033] Based on the requirements of different areas on the body 110, selective surface treatment is performed on the body 110 to avoid the risk of mechanical scratches to the chip 300 caused by the formation of local protrusions in the connection area between the body 110 and the chip 300 after the body 110 is homogenized. This further reduces the risk of chip 300 damage during processing and further improves the long-term reliability of the power module.

[0034] Among them, the encapsulating resin 200 is one of epoxy resin, epoxy molding compound (EMC), silicone gel, polyurethane (PU) or epoxy potting compound.

[0035] One end of chip 300 is connected to connector 140, and the other end of chip 300 is connected to the top of AMB substrate 500. Heat sink 600 is connected to the end of AMB substrate 500 away from chip 300. AMB substrate 500 provides a mounting base for chip 300.

[0036] In some embodiments, as shown in Table 1, the roughness Ra of the first roughening layer 120 and the second roughening layer 130 ranges from 0.11 to 0.35. The shear strength of the first roughened layer 120 and the second roughened layer 130, corresponding to a roughness Ra, ranges from 10.45 to 17.23 MPa. Specifically, when the roughness Ra of the roughened layer 120 is 0.11... At that time, its corresponding shear strength is 10.45 MPa, and when the roughness Ra of the rough layer 120 is 0.35... At that time, its corresponding shear strength was 17.23 MPa; as the roughness of the rough layer 120 gradually increased, its shear strength also gradually increased, which shows that increasing the roughness by copper roughening can significantly improve the bonding strength between the body 110 and the encapsulating resin 200.

[0037] Table 1 Correspondence between copper surface roughness and shear strength

[0038] The surface of the connecting part 140 is flat, and the first roughening layer 120 and the second roughening layer 130 can be nanoscale microporous structures, or made of... Figure 5 and Figure 6 As shown, the first rough layer 120 and the second rough layer 130 may also be a granular, regularly arranged protruding structure or a petal-shaped sheet structure.

[0039] In some embodiments, the structure of the body 110 is one of the following: bent type, straight type, or frame type, or other shapes that can meet the actual working conditions.

[0040] In some embodiments, the thickness of the body 110 ranges from 0.3 to 0.6 mm. This thickness ensures the stability of the body 110 structure while meeting the requirements of high current transmission and heat conduction, and adapts to the process requirements such as high-temperature sintering, ensuring the reliability of the connection between the body 110 and the chip 300, the AMB substrate 500 and the encapsulation resin 200.

[0041] In some embodiments, the thicknesses of the first roughening layer 120 and the second roughening layer 130 range from 0.3 to 3. .

[0042] The first roughened layer 120 and the second roughened layer 130 can be obtained by a roughening process or a browning process. The specific preparation process is as follows: (1) Roughening process First, the body 110 is cleaned and dried. Then, a protective film is coated on the surface of the connecting part 140 or it is isolated by a specific device. The unisolated part of the body 110 is roughened in copper ion electrolyte. A first rough layer 120 and a second rough layer 130 are formed on a portion of the upper and lower surfaces of the body 110, respectively. Then, the protective film or specific device on the surface of the connecting part 140 is removed. The body 110 is cleaned and dried and connected to the chip 300. The chip 300 is connected to the AMB substrate 500, the heat sink 600 and the terminal 400. Finally, it is bonded to the encapsulation resin to form a power module.

[0043] The roughening solution includes: a copper sulfate solution with a concentration of 0.1 mol / L to 1.2 mol / L, a copper chloride solution with a concentration of 0.02 mol / L to 0.5 mol / L, a Na₂S₂O₃ solution with a concentration of 0.01 mol / L to 0.06 mol / L, and a citric acid solution with a concentration of 0.02 mol / L to 0.05 mol / L. The roughening temperature ranges from 20 to 60℃, and the current density ranges from 2 to 6 A / dm³. 3 The roughening time ranges from 5 to 20 seconds. By spraying the roughening liquid onto the surface of the body 110 requiring surface treatment, a layer of deposited copper crystals is formed on a portion of the upper and lower surfaces of the body 110 using electrodeposition technology, resulting in a first roughened layer 120 and a second roughened layer 130. In the subsequent chip sintering process, the deposited copper crystals are recrystallized at high temperatures, forming a more stable first roughened layer 120 and second roughened layer 130. The surface structures of the first roughened layer 120 and the second roughened layer 130 are as follows: Figure 5 As shown.

[0044] The concentrations of the copper sulfate solution, copper chloride solution, and Na₂S₂O₃ solution were 0.8 mol / L, 0.3 mol / L, 0.05 mol / L, and 0.05 mol / L, respectively. The temperature was 56℃, and the current density was 6 A / dm³. 3 At this time, a copper clip with a surface roughness of 0.25 μm can be obtained, and under this parameter, the surface roughness of the rough layer increases with the increase of current density.

[0045] (2) Browning process First, the body 110 is cleaned and dried. Second, in areas where browning treatment is not required, such as the connecting part 140 and the chip layer or AMB layer, a protective film is applied or the area is isolated using a specific device. Then, the body 110 is immersed in a browning solution to brown the unisolated parts of the body 110. After cleaning and drying, the browned body 110 is obtained and connected to the chip 300. The chip 300 is connected to the AMB substrate 500, the heat sink 600, and the terminal 400. Finally, it is bonded with encapsulating resin to form a power module.

[0046] The browning treatment uses a mixture of 0.45 mol / L sodium sulfate solution, 0.15 mol / L hydrogen peroxide, and 0.8 mol / L H₂SO₄, and is performed at 65°C for 10 minutes. The surface structures of the first roughened layer 120 and the second roughened layer 130 are as follows: Figure 6 As shown.

[0047] The browning process enhances the interfacial adhesion between the copper substrate 110 and the encapsulating resin 200 through the micro-etching action of the browning solution. This prevents epoxy delamination during the power module packaging and usage processes, improves the power module's resistance to high temperatures and humidity, and extends its lifespan. During browning, an uneven, active, micro-rough oxide layer is formed on the copper surface, such as… Figure 6 As shown. By increasing the browning treatment, the contact area between the surface of the body 110 and the encapsulating resin 200 during epoxy potting is increased, thereby increasing the bonding force between the surface of the body 110 and the encapsulating resin 200. This helps to avoid delamination and thus improves the reliability and stability of the power module.

[0048] In some embodiments, the power module is further provided with a first solder layer 700, and the connection portion 140 is connected to the chip 300 through the first solder layer 700.

[0049] In some embodiments, the AMB substrate 500 includes a first connection layer 510, a second connection layer 520, and a third connection layer 530, which are sequentially arranged along the thickness direction of the AMB substrate 500; wherein the first connection layer 510 is connected to the chip 300, and the third connection layer 530 is connected to the heat sink 600.

[0050] The first connecting layer 510 and the third connecting layer 530 are copper layers, and the second connecting layer 520 is a ceramic layer, which may be composed of silicon nitride or aluminum nitride.

[0051] In another embodiment, the power module of this application further includes a second solder layer 800 and a third solder layer 900. The chip 300 is connected to the first connection layer 510 through the second solder layer 800, and the third connection layer 530 is connected to the heat sink base plate 600 through the third solder layer 900.

[0052] In another embodiment, the power module further includes a second connector and a fourth solder layer 410. One end of the second connector is connected to the first connection layer 510 via the fourth solder layer 410, and the other end extends to the outside of the power module and connects to an external system. The external system includes an external bus, a PCB (printed circuit board), or a power system, etc.

[0053] The second connector is a terminal 400. There are two terminals 400, which are symmetrically arranged at both ends of the body 110 and spaced apart along the horizontal direction of the body 110, with a gap between them and the body 110.

[0054] In some embodiments, the first solder layer 700, the second solder layer 800, the third solder layer 900, and the fourth solder layer 410 are all solder layers.

[0055] The power module assembly process of this application is as follows: First, the connecting part 140 is connected to the top of the chip 300 through the first solder layer 700 by a sintering process, and the bottom of the chip 300 is connected to the first connecting layer 510 through the second solder layer 800.

[0056] Then, the third connection layer 530 is connected to the heat sink 600 through the third solder layer 900, and the terminal 400 is connected to the first connection layer 510 through the fourth solder layer 410 at one end near the chip 300, while the other end extends outward to connect to an external system, thus completing the assembly of the interconnect structure.

[0057] The assembled first connector 100, chip 300, AMB substrate 500, heat sink 600 and terminal 400 are encapsulated in an insulating shell and finally filled with epoxy resin to form a power module.

[0058] The sintering process employs low-temperature sintering silver technology.

[0059] In this embodiment, the connection methods between the body 110, encapsulating resin, chip 300, AMB substrate 500, heat sink 600, and terminal 400 are the same as in the above-described embodiments. The body 110 has a U-shaped structure and a thickness of 0.4 mm. The encapsulating resin 200 is epoxy resin, used for encapsulating the overall power module. The processing technology of the body 110 can refer to the stamping technology of copper lead frames.

[0060] The power module of this application, by providing roughened layers on the upper and lower surfaces of the body, increases the bonding force between the body and the encapsulating resin during connection, reduces the formation of interface voids, and mitigates the delamination phenomenon of the encapsulating resin under temperature, humidity, or mechanical stress. Furthermore, placing the body-encapsulating resin connection structure within the power module improves product yield and reliability. Selective surface treatment of different areas of the body reduces the risk of chip damage, further enhancing the long-term reliability of the power module.

[0061] In the description of this specification, the use of terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," and "some examples" indicates that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0062] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A power module, characterized in that, include: A first connector, comprising a body, a roughening layer, and a connecting portion, wherein the body comprises a first surface and a second surface, the roughening layer comprises a first roughening layer and a second roughening layer, the first surface is provided with the first roughening layer, the second surface is provided with the second roughening layer, and the connecting portion is provided on the second surface where the second roughening layer is not provided. An encapsulating resin, wherein the encapsulating resin coats the first roughened layer and the second roughened layer; A chip, one end of which is connected to the connecting portion; AMB substrate, wherein the AMB substrate is connected to the other end of the chip; A heat dissipation base plate is connected to the end of the AMB substrate furthest from the chip.

2. A power module according to claim 1, characterized in that, The roughness Ra of the first and second roughening layers ranges from 0.11 to 0.

35. The shear strength of the first roughened layer and the second roughened layer ranges from 10.45 to 17.23 MPa.

3. A power module according to claim 1, characterized in that, The thicknesses of the first and second roughening layers range from 0.3 to 3. .

4. A power module according to claim 1, characterized in that, The first rough layer and the second rough layer are raised structures or petal-shaped sheet structures arranged in a regular granular pattern.

5. A power module according to claim 1, characterized in that, The thickness of the body is in the range of 0.3-0.6 mm.

6. A power module according to claim 1, characterized in that, The structure of the body can be one of the following: bent, straight, or frame type.

7. A power module according to claim 1, characterized in that, The power module also includes a first solder layer, and the connection part is connected to the chip through the first solder layer.

8. A power module according to claim 1, characterized in that, The AMB substrate includes a first connection layer, a second connection layer, and a third connection layer, which are sequentially arranged along the thickness direction of the AMB substrate. The first connection layer is connected to the chip, and the third connection layer is connected to the heat sink.

9. A power module according to claim 8, characterized in that, The power module further includes a second solder layer and a third solder layer. The chip is connected to the first connection layer through the second solder layer, and the third connection layer is connected to the heat dissipation base plate through the third solder layer.

10. A power module according to claim 8, characterized in that, The power module further includes a second connector and a fourth solder layer. One end of the second connector is connected to the first connector layer through the fourth solder layer, and the other end extends to the outside of the power module and is connected to an external system.

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