Power module and manufacturing method thereof

Abstract

The invention provides a power module and a manufacturing method thereof. In the power module, a chip is installed on a first surface of a bottom plate, a plurality of conductive columns are installed on the first surface of the bottom plate, a plastic package body is located on the first surface and wraps the chip and the side walls of the conductive columns, and the surfaces, away from the bottom plate, of the conductive columns are exposed out of the surface, away from the bottom plate, of the plastic package body. The bonding layer is located on the surface, away from the bottom plate, of the plastic package body, and the metal shielding cover is attached to the plastic package body through the bonding layer and covers the side wall of the plastic package body and the surface, away from the bottom plate, of the plastic package body in a conformal mode, so that the chip can be led out, electromagnetic waves inside and outside the module can be shielded, and then the problem of electromagnetic interference can be solved. The manufacturing method of the power module can be used for manufacturing the power module.

Description

Technical Field

[0001] The present invention relates to the field of packaging technology, and particularly to a power module and a manufacturing method thereof. Background Art

[0002] With the rise of power device products, the integration of devices such as power modules has increased, and the market prospect of power modules such as SiC is broad. The conventional manufacturing process of a power module is as follows: welding an SiC chip on a bottom plate through a sintering operation; realizing electrical connection between the chip and the bottom plate through a metal strip (Clip) and / or a metal bonding wire; welding a lead frame on the bottom plate; and encapsulating the SiC chip, the metal strip, the metal bonding wire, and the lead frame.

[0003] However, since the power devices in the power module have been operating in a switching state and handle a relatively large power, supporting high voltage and large current, in a high-frequency circuit, the parasitic inductance generated between the interconnecting lines will cause a relatively large electromagnetic interference (EMI), which will in turn affect the performance of the power module. Summary of the Invention

[0004] One object of the present invention is to provide a power module and a manufacturing method thereof, which can improve the electromagnetic interference problem and enhance the performance of the power module.

[0005] To achieve the above object, on the one hand, the present invention provides a power module. The power module includes: a bottom plate including opposite first and second surfaces; a chip mounted on the first surface, the chip being electrically connected to the bottom plate; a plurality of conductive posts mounted on the first surface; an encapsulant located on the first surface, wrapping the chip and the side walls of the plurality of conductive posts, the surfaces of the plurality of conductive posts away from the bottom plate being exposed from the surface of the encapsulant away from the bottom plate; an adhesive layer located on the surface of the encapsulant away from the bottom plate; and a metal shielding cover mounted on the encapsulant through the adhesive layer, conformally covering the side walls and the surface of the encapsulant away from the bottom plate.

[0006] Optionally, the bottom plate includes a ceramic substrate, a top surface metal layer on one side of the ceramic substrate facing the first surface, and a bottom surface metal layer on one side of the ceramic substrate facing the second surface. The top surface metal layer includes a plurality of pads, and the chip and the conductive posts are respectively mounted on the corresponding pads of the top surface metal layer.

[0007] Optionally, the thermal expansion coefficients of both the metal shielding cover and the bottom plate are smaller than the thermal expansion coefficient of the encapsulant.

[0008] Optionally, the thermal expansion coefficient of the metal shielding cover is greater than or equal to 14×10-6 / °C and less than 20×10 -6 / °C, the thermal expansion coefficient of the bottom plate is greater than or equal to 14×10 -6 / °C and less than or equal to 17×10 -6 / °C, the thermal expansion coefficient of the plastic package is greater than or equal to 20×10 -6 / °C and less than or equal to 40×10 -6 / °C.

[0009] Optionally, the chip and the bottom plate are electrically connected by a metal strip and / or a metal bonding wire.

[0010] Optionally, the power module includes a half-bridge module and a heat sink. The half-bridge module includes the bottom plate, the chip, the plurality of conductive posts, the plastic package, the adhesive layer, and the metal shielding cover. The second surface of the bottom plate of the half-bridge module is welded to the heat sink, and the metal shielding cover of the half-bridge module protrudes from the side wall of the plastic package toward the second surface of the bottom plate and is connected to the heat sink.

[0011] Optionally, Pin pins are installed on the top surfaces of some of the conductive posts.

[0012] On the other hand, the present invention also provides a method for manufacturing a power module. The method for manufacturing the power module includes: providing a bottom plate, the bottom plate including opposite first and second surfaces; installing a chip on the first surface, the chip being electrically connected to the bottom plate; installing a plurality of conductive posts on the first surface; forming a plastic package on the first surface, the plastic package wrapping the chip and the side walls of the plurality of conductive posts, and the surfaces of the plurality of conductive posts away from the bottom plate being exposed from the surface of the plastic package away from the bottom plate; forming an adhesive layer on the top surface of the plastic package; and mounting a metal shielding cover on the adhesive layer, the metal shielding cover conformally covering the side walls and the top surface of the plastic package.

[0013] Optionally, the step of installing the chip on the first surface includes: fixing the chip on the first surface by a sintering process, and then electrically connecting the chip and the bottom plate by welding a metal strip and / or forming a metal bonding wire.

[0014] Optionally, the thermal expansion coefficients of both the metal shielding cover and the bottom plate are less than the thermal expansion coefficient of the plastic package.

[0015] Optionally, a half-bridge module is formed after mounting a metal shielding cover on the adhesive layer; the manufacturing method further includes: mounting a plurality of the half-bridge modules on a heat sink to form a full-bridge module, wherein a second surface of the bottom plate of the half-bridge module is mounted on the heat sink, and the metal shielding cover extends from a side wall of the plastic package body to a surface of the heat sink and is connected to the heat sink; and soldering Pin pins on surfaces of some of the conductive posts away from the bottom plate.

[0016] In the power module and its manufacturing method provided by the present invention, a chip is mounted on a first surface of a bottom plate, a plurality of conductive posts are mounted on the first surface of the bottom plate, a plastic package body is located on the first surface and wraps side walls of the chip and the plurality of conductive posts, surfaces of the plurality of conductive posts away from the bottom plate expose from a surface of the plastic package body away from the bottom plate, an adhesive layer is located on the surface of the plastic package body away from the bottom plate, and a metal shielding cover is mounted on the plastic package body through the adhesive layer and conformally covers the side wall and the surface of the plastic package body away from the bottom plate. In this way, through the cooperation of the conductive posts and the metal shielding cover, the metal shielding cover can conformally cover the surface and the side wall of the plastic package body away from the bottom plate, the chip can be led out, and electromagnetic waves outside and inside the module can be shielded, the electromagnetic interference problem can be improved, and the performance of the power module can be enhanced; in addition, the metal shielding cover is conformally mounted on the side wall and the surface of the plastic package body away from the bottom plate. Compared with forming a shielding layer through a deposition process such as CVD, the process efficiency is high, and the metal shielding cover can also cover a specified area instead of non-selectively covering comprehensively. At the same time, the thickness uniformity of the metal shielding cover is relatively high, which helps to improve the shielding effect of electromagnetic waves.

[0017] Furthermore, the thermal expansion coefficients of both the metal shielding cover and the bottom plate are smaller than that of the plastic package body. In this way, in a high-temperature environment, the metal shielding cover and the bottom plate can have a certain degree of inhibitory effect on the expansion of the plastic package body, which helps to improve the warping problem in the power module and is beneficial to improving the reliability of the power module.

[0018] Furthermore, the metal shielding cover of the half-bridge module protrudes from the side wall of the plastic package body towards the second surface of the bottom plate and is connected to the heat sink, so that the metal shielding cover and the heat sink can be connected into a complete shielding chamber, and the shielding effect of electromagnetic interference can be significantly improved. Description of the Drawings

[0019] Figure 1 It is a flowchart of a manufacturing method of a power module provided by an embodiment of the present invention.

[0020] Figure 2 It is a schematic cross-sectional view after mounting a chip on a bottom plate in an embodiment of the present invention.

[0021] Figure 3 It is a partial top view after mounting a chip on a bottom plate in an embodiment of the present invention.

[0022] Figure 4 This is a schematic cross-sectional view of installing conductive posts on the bottom plate in an embodiment of the present invention.

[0023] Figure 5 This is a schematic cross-sectional view of forming a plastic package on the bottom plate in an embodiment of the present invention.

[0024] Figure 6 This is a schematic cross-sectional view of a half-bridge module of a power module provided in an embodiment of the present invention.

[0025] Figure 7 This is a schematic cross-sectional view of installing the half-bridge module on a heat sink in an embodiment of the present invention.

[0026] Figure 8 This is a schematic cross-sectional view of a power module provided in an embodiment of the present invention.

[0027] Explanation of reference numerals: 100 - bottom plate; 101 - ceramic substrate; 102 - top metal layer; 103 - bottom metal layer; 200 - chip; 201 - sintered layer; 202 - metal strip; 203 - metal bonding wire; 300 - conductive post; 400 - plastic package; 501 - adhesive layer; 502 - metal shielding cover; 503 - heat sink; 600 - half-bridge module. Detailed implementation manners

[0028] The following further elaborates on the power module and its manufacturing method proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise scales, only for conveniently and clearly assisting in explaining the purpose of the embodiments of the present invention.

[0029] As used in the present invention, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. As used in the present invention, the term "or" is generally used in the sense of including "and / or" unless the context clearly dictates otherwise. As used in the present invention, the term "several" is generally used in the sense of including "at least one" unless the context clearly dictates otherwise. As used in the present invention, the terms "at least two", "a plurality of" are generally used in the sense of including "two or more" unless the context clearly dictates otherwise. In addition, the terms "first", "second", "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first", "second", "third" may explicitly or implicitly include one or at least two of such features unless the context clearly dictates otherwise. The terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", etc. related to the present invention indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for convenience of describing the present application and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and should not be construed as a limitation to the present application.

[0030] Reference Figure 1 As shown, the manufacturing method of the power module provided in this embodiment includes:

[0031] Step S1, providing a bottom plate, the bottom plate including opposite first and second surfaces;

[0032] Step S2, mounting a chip on the first surface, the chip being electrically connected to the bottom plate;

[0033] Step S3, mounting a plurality of conductive posts on the first surface;

[0034] Step S4, forming a plastic package on the first surface, the plastic package wrapping the chip and the side walls of the plurality of conductive posts, and the surfaces of the plurality of conductive posts away from the bottom plate being exposed from the surface of the plastic package away from the bottom plate;

[0035] Step S5, forming an adhesive layer on the surface of the plastic package away from the bottom plate; and

[0036] Step S6, mounting a metal shielding cover on the adhesive layer, the metal shielding cover conformally covering the side walls and the surface away from the bottom plate of the plastic package.

[0037] It should be understood that although Figure 1The steps in the flowchart are shown in sequence according to the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise clearly stated in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 1 At least some of the steps in

[0038] Specifically, referring to Figure 2 and Figure 3 as shown, the base plate 100 provided in step S1 may include a ceramic substrate 101, a top surface metal layer 102 on one side of the ceramic substrate 101 facing the first surface, and a bottom surface metal layer 103 on one side of the ceramic substrate 101 facing the second surface; the top surface metal layer 102 may be a patterned metal layer including a plurality of pads. The materials of the top surface metal layer 102 and the bottom surface metal layer 103 include but are not limited to copper, and the material of the ceramic substrate 101 includes but is not limited to AlN.

[0039] Exemplarily, the base plate 100 may be a DBC (Direct Bonded Copper) ceramic substrate or an AMB (Active Metal Brazing) ceramic substrate. The DBC ceramic substrate is a substrate in which a copper foil is directly attached to a ceramic substrate, and the AMB ceramic substrate is a substrate that realizes high-temperature metallurgical bonding between ceramics and metals using an active metal solder.

[0040] Continuing to refer to Figure 2 and Figure 3 , step S2 is executed to mount the chip 200 on the first surface of the base plate 100. Among them, the back surface of the chip 200 may be adhered to the base plate 100, and the front surface of the chip 200 faces away from the base plate 100.

[0041] In step S2, multiple chips 200 may be mounted on the base plate 100 as needed; the multiple chips 200 may be chips with the same function or chips with different functions. For example, as Figure 2 shown, two chips are mounted on the base plate 100.

[0042] In this embodiment, the chip 200 includes, but is not limited to, a SiC chip or an IGBT (Insulated Gate Bipolar Transistor). The SiC chip has a wider bandgap width and a higher breakdown electric field strength, which enables it to withstand higher voltages and currents and is suitable for high-voltage and high-power scenarios. Among them, the SiC power device in the SiC chip can withstand a higher electric field strength, and at the same time can reduce power loss, is particularly suitable for high-voltage power applications, and there is no current tailing phenomenon during the turn-off process of the SiC power device, and the switching speed is fast, which is suitable for higher-frequency applications.

[0043] In step S2, the chip 200 can be fixed on the first surface of the bottom plate 100 through a sintering process, and then the metal bonding wire 203 is formed by welding the metal strip 202 (Clip) and wire bonding process to electrically connect the chip 200 and the bottom plate 100.

[0044] It should be noted that the sintering process is a low-temperature sintering technology. Taking the silver sintering process as an example, silver particles of micron size and below are sintered at a temperature below 300 °C, and good connection is achieved through the diffusion between atoms. The silver sintering technology has excellent electrical and thermal conductivity, and can obtain a connection interface with high temperature resistance and high thermal conductivity under low-temperature conditions, and is particularly suitable for high-temperature power modules. In this application, the sintering process can also be a sintering process of other metals such as copper.

[0045] When the chip 200 is fixed on the first surface of the bottom plate 100 through the sintering process, there is a sintering layer 201 between the chip 200 and the bottom plate 100, and the material of the sintering layer 201 includes, but is not limited to, silver or copper. In some embodiments, the back surface of the chip 200 has an electrode, and the electrode on the back surface of the chip 200 can be electrically connected to the pad on the first surface of the bottom plate 100 through the sintering layer 201. That is to say, different electrodes on the surface of the chip 200 can be electrically connected to the bottom plate 100 through the metal strip 202, the metal bonding wire 203 and the sintering layer 201 respectively.

[0046] Exemplarily, one source-drain terminal of the chip 200 can be connected to the top metal layer 102 of the bottom plate 100 through the metal strip 202, the gate of the chip 200 can be connected to the bottom plate 100 through the metal bonding wire 203, and the other source-drain terminal of the chip 200 can be connected to the bottom plate 100 through the sintering layer 201. In some embodiments, the source-drain terminals between adjacent chips 200 can be connected through the metal strip 202, and the gates between adjacent chips 200 can be connected through the metal bonding wire 203. The metal strip 202 can be a copper strip, but is not limited thereto. The material of the metal bonding wire 203 includes, but is not limited to, copper, aluminum, silver, gold or their alloys.

[0047] Reference Figure 4As shown, step S3 is executed to install a plurality of conductive posts 300 on the first surface of the base plate 100. Exemplarily, the bottom surface of the conductive post 300 can be soldered to the first surface of the base plate 100.

[0048] In this embodiment, the chip 200 and the conductive posts 300 are respectively installed on the pads corresponding to the top surface metal layer 102 of the base plate 100. Among the plurality of conductive posts 300, some conductive posts 300 can be used as signal terminals, and some conductive posts 300 can be used as power terminals, where the cross-sectional width of the power terminals can be greater than the cross-sectional width of the signal terminals.

[0049] In this embodiment, the cross-section of the conductive post 300 can be circular, but is not limited thereto. The material of the conductive post 300 includes but is not limited to copper.

[0050] Reference Figure 5 As shown, step S4 is executed to form a molding compound 400 on the first surface of the base plate 100. The molding compound 400 wraps the chip 200 and the side walls of the plurality of conductive posts 300. The surfaces of the plurality of conductive posts 300 away from the base plate 100 (subsequently referred to as the top surfaces) are exposed from the surface of the molding compound 400 away from the base plate 100 (subsequently referred to as the top surface). The molding compound 400 can isolate the devices within the molding compound 400 from external moisture / impurity interference.

[0051] In this embodiment, the molding compound 400 can be formed by injection molding. The material of the molding compound 400 can be epoxy molding compound (EMC) or silicone gel, but is not limited thereto.

[0052] In this embodiment, the heights of the plurality of conductive posts 300 can be equal. In other embodiments, the heights of the plurality of conductive posts 300 can also be unequal. At this time, the mold used to form the molding compound 400 needs to be adjusted according to the heights of the conductive posts so that the top surfaces of the plurality of conductive posts can all contact the mold during injection molding, so that the top surfaces of the plurality of conductive posts 300 are exposed from the molding compound 400.

[0053] In this embodiment, the top surfaces of the conductive posts 300 are flush with the top surface of the molding compound 400 adjacent to the conductive posts 300. Exemplarily, as shown in Figure 5 As shown, the top surface of the molding compound 400 is a stepped surface. The part of the top surface of the molding compound 400 close to the conductive posts 300 is higher than the part away from the conductive posts 300. In this way, the molding compound near the top surface of the conductive posts can electrically isolate the conductive posts 300 and the metal shielding cover. In some embodiments, the top surface of the molding compound 400 can also be a flat surface, and the top surface of the molding compound 400 can be flush with the top surface of the conductive posts 300. In other embodiments, the conductive posts 300 can protrude slightly from the molding compound 400, and the top surfaces of the conductive posts 300 can protrude from the top surface of the molding compound 400.

[0054] In this embodiment, referring to Figure 5 as shown, the distance from the side wall of the conductive post 300 to the outer edge of the encapsulant 400 can be greater than or equal to 0.1 mm. Or rather, the thickness D of the encapsulant wrapping the top end of the conductive post 300 can be greater than or equal to 0.1 mm. This can ensure that the encapsulant 400 can effectively provide electrical isolation for the conductive post 300 and the subsequently mounted metal shielding cover. In other embodiments, the distance from the side wall of the conductive post 300 to the outer edge of the encapsulant 400 can be set according to the actual situation.

[0055] It should be noted that in this embodiment, the top surface of the conductive post 300 is exposed from the top surface of the encapsulant 400, that is, pin-out from the top of the encapsulant, which can reduce the stray inductance and help improve the performance of the power module.

[0056] After forming the encapsulant 400, the residue on the top surface of the conductive post 300 can also be removed by laser. The residue can be the overflow glue that overflowed onto the top surface of the conductive post 300 when the encapsulant 400 was formed. This can ensure the electrical connection reliability between the conductive post 300 and the pin on its top surface.

[0057] Referring to Figure 6 as shown, perform step S5 to form an adhesive layer 501 on the top surface and the side wall of the encapsulant 400.

[0058] Exemplarily, the adhesive layer 501 can be conductive silver paste coated on the top surface and the side wall of the encapsulant 400, but is not limited thereto.

[0059] Perform step S6 to mount a metal shielding cover 502 on the adhesive layer 501. The metal shielding cover 502 conformally covers the side wall and the top surface of the encapsulant 400.

[0060] In this embodiment, the metal shielding cover 502 may not be in direct contact with the conductive post 300 exposed from the top surface of the encapsulant 400. Specifically, the metal shielding cover 502 has a plurality of openings, and the top surfaces of the plurality of conductive posts 300 are exposed from the plurality of openings. Exemplarily, the width of one opening is greater than the width of the top surface of its corresponding conductive post 300. Among them, after mounting the metal shielding cover 502 on the adhesive layer 501, the adhesive layer 501 can be cured to fix the metal shielding cover 502 on the encapsulant 400.

[0061] In this embodiment, for the situation where the top surface of the encapsulant 400 is a stepped surface, the openings of the metal shielding cover 502 can surround the top surface of the corresponding conductive post and the encapsulant around the top end of the conductive post. Therefore, the width W2 of the opening ≥ W1 + D, where W1 is the width of the top surface of the conductive post 300 corresponding to the opening, and D is the thickness of the encapsulant at the top end of the conductive post 300. The top surface of the opening of the metal shielding cover 502 can be flush with the top surface of the conductive post 300, but is not limited thereto.

[0062] It should be noted that the metal shielding cover 502 can be a metal sheet with a set shape. The metal shielding cover 502 is designed according to the shape and size of the plastic package 400, and the opening of the metal shielding cover 502 is designed according to the shape, size and installation position of the conductive posts 300.

[0063] In this embodiment, referring to Figure 6 as shown, the metal shielding cover 502 protrudes from the side wall of the plastic package 400 towards the second surface of the bottom plate 100, which facilitates the subsequent contact connection between the metal shielding cover 502 and the heat sink.

[0064] Exemplarily, the material of the metal shielding cover 502 can include stainless steel, copper, aluminum, ferrite, nickel, carbon black or iron hydroxide, etc.

[0065] After performing step S6, a half-bridge module 600 can be formed. Figure 6 The structure of the half-bridge module 600 is shown. The half-bridge module 600 can include the bottom plate 100, the chip 200, the plurality of conductive posts 300, the plastic package 400, the adhesive layer 501 and the metal shielding cover 502.

[0066] In this embodiment, the thermal expansion coefficients of both the metal shielding cover 502 and the bottom plate 100 are smaller than that of the plastic package 400. In this way, in a high-temperature environment, the metal shielding cover 502 and the bottom plate 100 can have a certain degree of inhibitory effect on the expansion of the plastic package 400, which helps to improve the warping problem of the half-bridge module 600 in the power module and is beneficial to improving the reliability of the power module.

[0067] Exemplarily, the thermal expansion coefficient of the metal shielding cover 502 is greater than or equal to 14×10 -6 / °C and less than 20×10 -6 / °C, the thermal expansion coefficient of the bottom plate 100 is greater than or equal to 14×10 -6 / °C and less than or equal to 17×10 -6 / °C, and the thermal expansion coefficient of the plastic package 400 is greater than or equal to 20×10 -6 / °C and less than or equal to 40×10 -6 / °C.

[0068] Next, referring to Figure 7 as shown, a plurality of half-bridge modules 600 are installed on the heat sink 503 to form a full-bridge module. The second surface of the bottom plate 100 of the half-bridge module 600 is mounted on the heat sink 503, and the metal shielding cover 502 extends from the side wall of the plastic package 400 to the surface of the heat sink 503 and is connected to the heat sink 503. The metal shielding cover 502 and the heat sink 503 can be connected into a complete shielding chamber, which helps to improve the shielding effect of electromagnetic interference.

[0069] Specifically, solder can be coated on the bottom metal layer 102 of the bottom plate 100 of the half-bridge module 600 or on the surface of the heat sink 503, and then the half-bridge module 600 is soldered to the heat sink 503 by using the reflow soldering process.

[0070] Exemplarily, the heat sink 503 can include a copper block and a nickel layer on the surface of the copper block, where copper serves as an effective shielding metal. In other embodiments, the heat sink 503 can also be made of other conductive materials. In this embodiment, the full-bridge module includes two half-bridge modules 600, but is not limited thereto.

[0071] Reference Figure 8 As shown, Pin pins 504 are soldered on the top surfaces of some of the conductive posts 300, and the Pin pins 504 are the pins.

[0072] In this embodiment, Pin pins 504 can be soldered on the top surface of the conductive post 300 serving as a signal terminal, and Pin pins do not need to be soldered on the top surface of the conductive post 300 serving as a power terminal. The power terminal can be directly soldered to the whole board later.

[0073] It should be noted that some of the conductive posts 300 serve as grounding terminals, and the grounding terminals are electrically connected to the metal shielding cover 502. The metal shielding cover 502 can be directly in contact with the grounding terminals to achieve electrical connection, or the top surface of the grounding terminals and the metal shielding cover 502 can be electrically connected by coating solder, or other conductive means can be used to achieve the electrical connection between the grounding terminals and the metal shielding cover 502. It should be noted that except for the grounding terminals, other signal terminals and power terminals are electrically isolated from the metal shielding cover 502, that is, they are not electrically connected to the metal shielding cover 502.

[0074] This embodiment also provides a power module, and the power module can be made by using the manufacturing method of the above power module, but is not limited thereto.

[0075] Reference Figure 6 As shown, the power module provided in this embodiment includes a bottom plate 100, a chip 200, a plurality of conductive posts 300, a plastic package 400, an adhesive layer 501, and a metal shielding cover 502. The bottom plate 100 includes opposite first and second surfaces; the chip 200 is mounted on the first surface of the bottom plate 100, and the chip 200 is electrically connected to the bottom plate 100; a plurality of conductive posts 300 are mounted on the first surface; the plastic package 400 is located on the first surface, wrapping the chip 200 and the side walls of the plurality of conductive posts 300, and the surfaces of the plurality of conductive posts 300 away from the bottom plate 100 (subsequently referred to as the top surfaces) are exposed from the surface of the plastic package 400 away from the bottom plate 100 (subsequently referred to as the top surface); the adhesive layer 501 is located on the top surface of the plastic package 400; the metal shielding cover 502 is mounted on the plastic package 400 through the adhesive layer 501, conformally covering the side walls and the top surface of the plastic package 400.

[0076] Exemplarily, the bottom plate 100 may include a ceramic substrate 101, a top surface metal layer 102 located on one side of the ceramic substrate 101 facing the first surface, and a bottom surface metal layer 103 located on one side of the ceramic substrate 101 facing the second surface. The top surface metal layer 102 may include a plurality of pads, and the chip 200 and the conductive posts 300 are respectively mounted on the corresponding pads of the top surface metal layer 102. The materials of the top surface metal layer 102 and the bottom surface metal layer 103 include but are not limited to copper, and the material of the ceramic substrate 101 includes but is not limited to AlN. For example, the bottom plate 100 may be a DBC ceramic substrate or an AMB ceramic substrate.

[0077] In this embodiment, the chip 200 may be a SiC chip or an IGBT, but is not limited thereto. There may be a sintering layer 201 between the chip 200 and the bottom plate 100, and the chip 200 is fixed on the bottom plate 100 through the sintering layer 201. The material of the sintering layer 201 includes but is not limited to silver or copper.

[0078] Reference Figure 6 and Figure 3 As shown, in this embodiment, the chip 200 and the bottom plate 100 may be electrically connected through a metal strip 202 and a metal bonding wire 203. Exemplarily, one source-drain end of the chip 200 may be connected to the top surface metal layer 102 of the bottom plate 100 through the metal strip 202, and the gate of the chip 200 may be connected to the top surface metal layer 102 of the bottom plate 100 through the metal bonding wire 203. In some embodiments, two or more chips 200 may be mounted on the bottom plate 100, and the source-drain ends between adjacent chips 200 may be connected through the metal strip 202, and the gates between adjacent chips 200 may be connected through the metal bonding wire 203. The metal strip 202 may be a copper strip, but is not limited thereto. The material of the metal bonding wire 203 includes but is not limited to copper, aluminum, silver, gold, or their alloys.

[0079] In this embodiment, the heights of the plurality of conductive posts 300 may be equal. In other embodiments, the heights of the plurality of conductive posts 300 may also be unequal.

[0080] In this embodiment, the cross-section of the conductive post 300 may be circular, but is not limited thereto. The material of the conductive post 300 includes but is not limited to copper. It should be noted that among the plurality of conductive posts 300, some conductive posts 300 may be used as signal terminals, and some conductive posts 300 may be used as power terminals. The cross-sectional width of the power terminals may be greater than the cross-sectional width of the signal terminals.

[0081] Reference Figure 6 As shown, the encapsulant 400 is located on the first surface of the bottom plate 100, wrapping the chip 200 and the side walls of the plurality of conductive posts 300, and the top surfaces of the plurality of conductive posts 300 are exposed from the top surface of the encapsulant 400.

[0082] In this embodiment, as Figure 6 shown, the top surface of the encapsulant 400 can be a stepped surface. The part of the top surface of the encapsulant 400 close to the conductive post 300 is higher than the part away from the conductive post 300. In this way, the encapsulant near the top surface of the conductive post can effectively electrically isolate the conductive post 300 and the metal shielding cover 502. In some embodiments, the top surface of the encapsulant 400 can also be a flat surface, and the top surface of the encapsulant 400 can be flush with the top surface of the conductive post 300. In other embodiments, the conductive post 300 can protrude slightly from the encapsulant 400, and the top surface of the conductive post 300 can protrude from the top surface of the encapsulant 400.

[0083] Exemplarily, the material of the encapsulant 400 can be epoxy molding compound (EMC) or silicone gel, but is not limited thereto.

[0084] The adhesive layer 501 is located on the top surface of the encapsulant 400, and the adhesive layer 501 can also be located on the side wall of the encapsulant 400. The adhesive layer 501 can be silver paste, but is not limited thereto.

[0085] The metal shielding cover 502 is mounted on the encapsulant 400 through the adhesive layer 501, and conformally covers the side wall and the top surface of the encapsulant 400.

[0086] In this embodiment, the metal shielding cover 502 may not be in direct contact with the conductive post 300 (except for the conductive post as the ground terminal) exposed from the top surface of the encapsulant 400. Specifically, the metal shielding cover 502 has a plurality of openings, and the plurality of openings correspond to the top surface positions of the plurality of conductive posts 300. In this embodiment, the openings of the metal shielding cover 502 can surround the top ends of the corresponding conductive posts 300.

[0087] In one embodiment, as Figure 6 shown, the top surface of the encapsulant 400 is a stepped surface, and the metal shielding cover 502 on the top surface of the encapsulant 400 conformally undulates with the top surface of the encapsulant 400. The metal shielding cover 502 covers the side wall of the top end of the conductive post 300 and the encapsulant 400 attached to the side wall of the top end of the conductive post 300. For the case where the top surface of the encapsulant 400 is a stepped surface, the openings of the metal shielding cover 502 can surround the top surface of the corresponding conductive post and the encapsulant around the top end of the conductive post. Therefore, the width W2 of the opening ≥ W1 + D, where W1 is the width of the top surface of the conductive post 300 corresponding to the opening, and D is the thickness of the encapsulant at the top end of the conductive post 300.

[0088] In this embodiment, as Figure 6 shown, the metal shielding cover 502 protrudes from the side wall of the encapsulant 400 toward the second surface of the bottom plate 100 and at least extends to the plane where the second surface of the bottom plate 100 is located, so that the metal shielding cover 502 can be connected to the heat sink.

[0089] In this embodiment, the thermal expansion coefficients of the metal shielding cover 502 and the bottom plate 100 can be less than that of the plastic package 400, and the thermal expansion coefficients of the metal shielding cover 502 and the bottom plate 100 can be similar. In this way, in a high-temperature environment, the metal shielding cover 502 and the bottom plate 100 can inhibit the expansion of the plastic package 400 to a certain extent, which helps to improve the warping problem of the half-bridge module 600 in the power module and is beneficial to improving the reliability of the power module.

[0090] Exemplarily, the thermal expansion coefficient of the metal shielding cover 502 is greater than or equal to 14×10 -6 / °C and less than 20×10 -6 / °C, the thermal expansion coefficient of the bottom plate 100 is greater than or equal to 14×10 -6 / °C and less than or equal to 17×10 -6 / °C, and the thermal expansion coefficient of the plastic package 400 is greater than or equal to 20×10 -6 / °C and less than or equal to 40×10 -6 / °C.

[0091] It should be noted that in this embodiment, Figure 6 the half-bridge module 600 of the power module is shown. The half-bridge module 600 includes the above-mentioned bottom plate 100, chip 200, multiple conductive posts 300, plastic package 400, adhesive layer 501 and metal shielding cover 502, wherein the half-bridge module 600 may include two chips 200, but is not limited thereto.

[0092] Referring to Figure 8 as shown, the power module may further include a heat sink 503. The second surface of the bottom plate 100 of the half-bridge module 600 is welded to the heat sink 503. Specifically, the bottom surface metal layer 103 of the bottom plate 100 can be welded to the heat sink 503 through solder. Referring to Figure 6 and Figure 8 as shown, the metal shielding cover 502 of the half-bridge module 600 protrudes from the side wall of the plastic package 400 toward the second surface of the bottom plate 100 and is connected to the heat sink 503. Thus, the metal shielding cover 502 and the heat sink 503 can be connected into a complete shielding chamber, which can significantly improve the shielding effect of electromagnetic interference.

[0093] In this embodiment, the power module can be a full-bridge module including multiple half-bridge modules 600. The second surfaces of the bottom plates 100 of the multiple half-bridge modules 600 are all welded to the heat sink 503.

[0094] Exemplarily, the heat sink 503 may include a copper block and a nickel layer on the surface of the copper block, wherein copper is the effective shielding metal.

[0095] Referring to Figure 8As shown in the figure, in the power module, Pin pins 504 are installed on the top surfaces of some of the conductive posts 300 so that these conductive posts 300 can be connected to an external circuit. In this embodiment, the top surfaces of the conductive posts 300 serving as signal terminals can be welded with Pin pins 504. The top surfaces of the conductive posts 300 serving as power terminals do not need to be welded with Pin pins, and the power terminals can be directly welded to the entire board later.

[0096] It should be noted that some of the conductive posts 300 serve as ground terminals, and the ground terminals are electrically connected to the metal shielding cover 502. The metal shielding cover 502 can be directly in contact with the ground terminals to achieve electrical connection, or the top surface of the ground terminals and the metal shielding cover 502 can be electrically connected by coating solder, or the top surface of the ground terminals and the metal shielding cover 502 can be electrically connected by other conductive means. It should be noted that except for the ground terminals, other signal terminals and power terminals are electrically isolated from the metal shielding cover 502.

[0097] In the power module and its manufacturing method provided by the present invention, the chip 200 is installed on the first surface of the bottom board 100, a plurality of conductive posts 300 are installed on the first surface of the bottom board 100, the plastic package 400 is located on the first surface and wraps the side walls of the chip 200 and the plurality of conductive posts 300, the top surfaces of the plurality of conductive posts 300 are exposed from the top surface of the plastic package 400, the adhesive layer 501 is located on the top surface of the plastic package 400, the metal shielding cover 502 is mounted on the plastic package 400 through the adhesive layer 501 and conformally covers the side walls and the top surface of the plastic package 400, the metal shielding cover 502 has a plurality of openings, and the positions of the plurality of openings correspond to the top surfaces of the plurality of conductive posts 300. In this way, through the cooperation of the conductive posts 300 and the metal shielding cover 502, the metal shielding cover 502 can conformally cover the top surface and the side walls of the plastic package 400, the chip 200 can be led out, and the electromagnetic waves outside and inside the module can be shielded, the electromagnetic interference problem can be improved, and the performance of the power module can be improved; in addition, the metal shielding cover 502 is conformally mounted on the side walls and the top surface of the plastic package 400. Compared with forming a shielding layer through deposition processes such as CVD, the process efficiency is high, and the metal shielding cover 502 can also cover a specified area instead of non-selectively covering the whole, and at the same time, the thickness uniformity of the metal shielding cover 502 is relatively high, which helps to improve the shielding effect of electromagnetic waves.

[0098] Furthermore, the thermal expansion coefficients of both the metal shielding cover 502 and the bottom board 100 are smaller than that of the plastic package 400. In this way, in a high-temperature environment, the metal shielding cover 502 and the bottom board 100 can have a certain degree of inhibitory effect on the expansion of the plastic package 400, which helps to improve the warping problem in the power module and is beneficial to improving the reliability of the power module.

[0099] Furthermore, the metal shielding cover 502 of the half-bridge module protrudes from the side wall of the plastic package 400 toward the second surface of the bottom plate and is connected to the heat sink, so that the metal shielding cover 502 and the heat sink 503 can be connected into a complete shielding chamber, which can significantly improve the shielding effect of electromagnetic interference.

[0100] It should be noted that this specification is described in a progressive manner. The parts described later mainly focus on the differences from the parts described earlier. For the same and similar parts between each part, reference can be made to each other.

[0101] The above description is only a description of the preferred embodiments of the present invention, and does not limit any scope of the rights of the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the technical solutions of the present invention all belong to the protection scope of the technical solutions of the present invention.

Claims

1. A power module, characterized in that, Comprising: A bottom plate, including opposite first and second surfaces; A chip, mounted on the first surface, and electrically connected to the bottom plate; A plurality of conductive posts, mounted on the first surface; A plastic encapsulation body, located on the first surface, wrapping the chip and the side walls of the plurality of conductive posts, and the surfaces of the plurality of conductive posts away from the bottom plate are exposed from the surface of the plastic encapsulation body away from the bottom plate; An adhesive layer, located on the surface of the plastic encapsulation body away from the bottom plate; And A metal shielding cover, mounted on the plastic encapsulation body through the adhesive layer, conformally covering the side walls and the surface away from the bottom plate of the plastic encapsulation body.

2. The power module according to claim 1, wherein The bottom plate includes a ceramic substrate, a top surface metal layer on one side of the ceramic substrate facing the first surface, and a bottom surface metal layer on one side of the ceramic substrate facing the second surface. The top surface metal layer includes a plurality of pads, and the chip and the conductive posts are respectively mounted on the corresponding pads of the top surface metal layer.

3. The power module according to claim 1, characterized in that, The thermal expansion coefficients of both the metal shielding cover and the bottom plate are less than that of the plastic encapsulation body.

4. The power module according to claim 3, characterized in that, The thermal expansion coefficient of the metal shielding cover is greater than or equal to 14×10 -6 / °C and less than 20×10 -6 / °C, the thermal expansion coefficient of the bottom plate is greater than or equal to 14×10 -6 / °C and less than or equal to 17×10 -6 / °C, the thermal expansion coefficient of the plastic package is greater than or equal to 20×10 -6 / °C and less than or equal to 40×10 -6 / °C.

5. The power module according to claim 1, wherein The chip and the bottom plate are electrically connected through a metal strip and / or a metal bonding wire.

6. The power module according to claim 1, wherein The power module includes a half-bridge module and a heat sink. The half-bridge module includes the bottom plate, the chip, the plurality of conductive posts, the plastic encapsulation body, the adhesive layer, and the metal shielding cover. The second surface of the bottom plate of the half-bridge module is welded to the heat sink, and the metal shielding cover of the half-bridge module protrudes from the side wall of the plastic encapsulation body towards the second surface of the bottom plate and is connected to the heat sink.

7. The power module according to claim 1, characterized in that, Pin pins are mounted on the surfaces of some of the conductive posts away from the bottom plate.

8. A manufacturing method of a power module, characterized in that, Comprising: Providing a bottom plate, the bottom plate including opposite first and second surfaces; Mounting a chip on the first surface, and electrically connecting the chip to the bottom plate; Mounting a plurality of conductive posts on the first surface; Forming a plastic encapsulation body on the first surface, the plastic encapsulation body wrapping the chip and the side walls of the plurality of conductive posts, and the surfaces of the plurality of conductive posts away from the bottom plate are exposed from the surface of the plastic encapsulation body away from the bottom plate; Forming an adhesive layer on the surface of the plastic encapsulation body away from the bottom plate; And Mounting a metal shielding cover on the adhesive layer, the metal shielding cover conformally covering the side walls and the surface away from the bottom plate of the plastic encapsulation body.

9. The manufacturing method of the power module according to claim 8, wherein The step of mounting the chip on the first surface includes: fixing the chip on the first surface through a sintering process, and then electrically connecting the chip and the bottom plate by welding a metal strip and / or forming a metal bonding wire.

10. The manufacturing method of the power module according to claim 8, characterized in that, The thermal expansion coefficients of both the metal shielding cover and the bottom plate are less than that of the plastic encapsulation body.

11. The manufacturing method of the power module according to claim 8, characterized in that, After mounting the metal shielding cover on the adhesive layer, a half-bridge module is formed; the manufacturing method further includes: mounting a plurality of the half-bridge modules on a heat sink to form a full-bridge module, wherein the second surface of the bottom plate of the half-bridge module is mounted on the heat sink, the metal shielding cover extends from the side wall of the plastic encapsulation body to the surface of the heat sink and is connected to the heat sink; and welding Pin pins on the surfaces of some of the conductive posts away from the bottom plate.

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