Packaging structure and packaging method

Abstract

This application discloses a packaging structure and packaging method, belonging to the field of power electronic device technology. The packaging structure includes: a substrate; a chip disposed on a first surface of the substrate; a pin base disposed on the first surface of the substrate; a molding compound covering the first surface of the substrate and exposing a concave groove of the pin base; a pin, one end of which extends into the concave groove and engages with the pin base; and a printed circuit board (PCB) with contact holes, the other end of which extends into the contact holes and is electrically connected to the PCB. This packaging structure uses pins instead of leads for connection, effectively reducing the risk of failure due to stress concentration and improving module reliability and space utilization.

Description

Technical Field

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

[0002] Silicon carbide (SiC) metal oxide semiconductor field-effect transistors (MOSFETs) are widely used in various power supplies due to their high power density, high reliability, high operating junction temperature, low parasitic inductance, and low thermal resistance.

[0003] With the increasing demands from industries such as automotive and photovoltaics for heat dissipation, parasitic inductance, creepage distance, and automated assembly, surface-mount power devices with top thermal insulation packages have been developed. Surface-mount devices use copper lead frames (LF) soldered to an insulating substrate and then encapsulated, eliminating the need for external insulating pads. This significantly improves heat dissipation performance, resulting in high reliability and high power density.

[0004] During the surface mount device (SMD) installation process, the product is soldered onto the printed circuit board (PCB). To ensure that the heat sink and heat plate are in full contact and to prevent air from entering and affecting heat dissipation, screws are used to tighten the PCB and the heat sink. This causes the area near the pins to be subjected to great pressure, which may lead to the pins falling off the PCB solder joints, microcracks at the edge of the plastic seal, and other phenomena, affecting the product's lifespan. Summary of the Invention

[0005] This invention aims to address at least one of the technical problems existing in the prior art. To this end, this invention proposes a packaging structure and method that uses pins instead of leads for connection, effectively reducing the risk of failure caused by stress concentration and improving module reliability and space utilization.

[0006] Firstly, this application provides a packaging structure, including: substrate; A chip, wherein the chip is disposed on a first side of the substrate; A pin base, wherein the pin base is disposed on the first surface of the substrate; A molding compound, which covers the first surface of the substrate and exposes the concave slot of the pin base; A pin, one end of which extends into the concave slot and engages with the pin base; A printed circuit board, wherein the printed circuit board has a contact hole, the other end of the pin extends into the contact hole, and the pin is electrically connected to the printed circuit board.

[0007] According to the packaging structure of this application, by setting the pin base on the substrate and inserting the pin directly into the printed circuit board, the upper and lower contact surfaces of the power module are the substrate and the molding compound, respectively, which can maximize the flatness of the module. Using pins instead of leads for connection can effectively reduce the risk of failure caused by stress concentration, improve the mechanical reliability and long-term stability of the module, and also improve space utilization. By configuring the number and layout of pins, the current carrying capacity of the module can be improved and the inductance can be reduced. Power conversion topologies such as three-phase bridge and H-bridge can be constructed in a small area.

[0008] According to one embodiment of this application, the opening of the concave slot is directly opposite to the contact hole, and the end of the pin base near the printed circuit board is spaced apart from the printed circuit board.

[0009] According to one embodiment of this application, the side of the molding compound near the printed circuit board has a first protrusion, and the end face of the first protrusion contacts the side of the printed circuit board near the molding compound.

[0010] According to one embodiment of this application, it also includes: A support plate, wherein a first side of the support plate contacts the side of the molding compound closest to the printed circuit board, and a second side of the support plate contacts the side of the printed circuit board closest to the molding compound.

[0011] According to one embodiment of this application, the first surface of the support plate has a second protrusion, and the side of the molding compound near the printed circuit board has a second concave groove, with the second protrusion extending into the second concave groove.

[0012] According to one embodiment of this application, the projection pattern of the support plate on the substrate does not cover the pin base, and the area of ​​the support plate is smaller than the area of ​​the substrate.

[0013] According to one embodiment of this application, the support plate is provided with positioning holes, and the projection pattern of the support plate on the substrate covers the pin base, with the positioning holes being directly opposite the pin base.

[0014] According to one embodiment of this application, the area of ​​the support plate is greater than or equal to the area of ​​the substrate.

[0015] According to one embodiment of this application, the chip is a silicon carbide metal oxide semiconductor field-effect transistor chip.

[0016] Secondly, this application provides a packaging method, which includes: Solder paste is printed on the first side of the substrate, the chip is placed at the solder paste printing position, and the chip is fixed to the first side of the substrate by soldering with solder paste. The pin base is welded to the first side of the substrate using ultrasonic welding equipment; A molding compound is obtained by injection molding on the first side of the substrate. The molding compound covers the first side of the substrate and exposes the concave slot of the pin base. One end of the pin is inserted into the concave slot to engage the pin with the pin base; The other end of the pin is inserted into the contact hole of the printed circuit board, and the pin is electrically connected to the printed circuit board.

[0017] According to the packaging method of this application, the chip is fixed to the first side of the substrate by solder paste welding, the pin base is welded to the substrate by ultrasonic welding, and a molded body is obtained by injection molding on the first side of the substrate. The molded body covers the first side of the substrate and exposes the concave slot of the pin base. One end of the pin is inserted into the pin base, and the other end of the pin is directly inserted into the printed circuit board. The module is easy to install, the process is simple, and it can also effectively reduce the risk of failure caused by stress concentration. The power module has high reliability and can build power conversion topologies such as three-phase bridge and H-bridge in a small area.

[0018] 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

[0019] The above and / or additional aspects and advantages of the present invention 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 one of the cross-sectional views of the packaging structure provided in the embodiments of this application; Figure 2 This is a schematic diagram of a pin being inserted into a pin base according to an embodiment of this application; Figure 3 This is a second cross-sectional view of the packaging structure provided in the embodiments of this application; Figure 4 This is the third cross-sectional view of the packaging structure provided in the embodiments of this application; Figure 5 This is one of the schematic diagrams showing the layout of the pin base provided in the embodiments of this application; Figure 6 This is a second schematic diagram of the layout of the pin base provided in the embodiments of this application; Figure 7 This is a top view of the rear of the packaging structure provided in the embodiments of this application; Figure 8 This is the fourth cross-sectional view of the packaging structure provided in the embodiments of this application; Figure 9 This is the fifth cross-sectional view of the packaging structure provided in the embodiments of this application; Figure 10 This is the sixth cross-sectional view of the packaging structure provided in the embodiments of this application; Figure 11 yes Figure 10 A cross-sectional view of the support plate in the middle; Figure 12 This is a top view of the support plate provided in the embodiment of this application; Figure 13 This is the third schematic diagram of the layout of the pin base provided in the embodiments of this application; Figure 14 This is the seventh cross-sectional view of the packaging structure provided in the embodiments of this application; Figure 15 yes Figure 14 A cross-sectional view of the support plate in the middle; Figure 16 This is one of the flowcharts illustrating the encapsulation method provided in the embodiments of this application; Figure 17 This is the second flowchart of the encapsulation method provided in the embodiments of this application.

[0020] Figure label: Substrate 100, first copper layer 110, second copper layer 120, ceramic layer 130. Chip 200, bonding wire 210, Pin base 310, concave slot 311, pin 320. The molding compound 400 has a first protrusion 410 and a second concave groove 420. Printed circuit board 500, contact hole 510. Support plate 600, second protrusion 610, positioning hole 620. Detailed Implementation

[0021] 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.

[0022] The SiC MOSFETs currently holding a significant market share are discrete devices, allowing for the assembly of different topologies on a PCB. For electrical safety reasons, an external insulating pad is added during the mounting of discrete devices. When multiple discrete devices with different potentials are mounted on the same heatsink frame, electrical isolation between the devices and the heatsink is achieved. However, this packaging method increases the thermal resistance from the chip junction to the heatsink, reduces the power and current handling capabilities of the power module, complicates thermal management, and increases the assembly workload.

[0023] Surface mount power devices feature a top-mounted thermally insulated package, soldered to an insulating substrate using copper LF (Laminated Thermal Encapsulation), and then encapsulated. This eliminates the need for external insulating pads, significantly improving heat dissipation, reliability, and power density. Compared to discrete devices, the assembly process is simpler, and the module power density is higher.

[0024] During the surface mount device (SMD) installation process, the product is soldered onto the PCB. To ensure full contact between the heat sink and the heat plate and to prevent air from entering and affecting heat dissipation, screws are used to tighten the PCB and the heat sink. This results in significant pressure near the pins, which may cause the pins to detach from the PCB solder joints, microcracks at the edges of the plastic seal, and other issues that affect the product's lifespan.

[0025] In addition, due to limitations in size and creepage distance, existing surface mount power devices cannot have more pins and cannot be packaged into topologies such as three-phase bridges and H-bridges.

[0026] This application provides a packaging structure that can be used in power modules. It uses pins 320 instead of pins for connection, which effectively reduces the risk of failure caused by stress concentration, improves the mechanical reliability and long-term stability of the module, and can also improve space utilization. By configuring the number and layout of pins 320, the current carrying capacity of the module can be improved and the irritation can be reduced. Power conversion topologies such as three-phase bridge and H-bridge can be constructed in a small area.

[0027] The following is for reference. Figure 1 - Figure 17 This application describes the packaging structure and packaging method according to embodiments of the present application.

[0028] The packaging structure includes a substrate 100, a chip 200, a pin base 310, a molding compound 400, pins 320, and a printed circuit board 500.

[0029] The substrate 100 can be a copper-clad ceramic substrate (Direct Bonding Copper, DBC). The substrate 100 may include a first copper layer 110, a ceramic layer 130 and a second copper layer 120 stacked in sequence. The first copper layer 110 can be used for power circuit wiring, constructing topologies such as three-phase bridges and H-bridges, and is also the soldering and bonding area of ​​the chip 200. The second copper layer 120 can be used as a heat dissipation channel or for electrical grounding.

[0030] It is understandable that chip 200 can be a semiconductor chip with power switching function, which is the core unit of power modules such as SiCMOSFET. Under the drive of control signal, it can achieve efficient power switching (on / off).

[0031] In some embodiments, chip 200 is a silicon carbide metal oxide semiconductor field-effect transistor chip.

[0032] The silicon carbide metal oxide semiconductor field-effect transistor (SiC MOSFET Die) is a chip made of silicon carbide material. It has the characteristics of high voltage and high frequency as well as ultra-low loss and is suitable for building power topologies such as half bridge and H bridge.

[0033] In this embodiment, the chip 200 is disposed on the first side of the substrate 100.

[0034] In practice, the first side of the substrate 100 can be the side of the first copper layer 110 that faces away from the ceramic layer 130.

[0035] like Figure 1 As shown, the substrate 100 includes a first copper layer 110, a ceramic layer 130 and a second copper layer 120 stacked in sequence. The chip 200 is disposed on the side of the first copper layer 110 facing away from the ceramic layer 130. The active area of ​​the chip 200 and different sites of the substrate 100 can be connected by bonding wires 210 such as aluminum wires and copper wires.

[0036] The packaging structure includes a printed circuit board 500, and the electrical connection between the printed circuit board 500 and the chip 200 on the substrate 100 is achieved by pressing pins.

[0037] Among them, a press-fit connector is a type of connector that achieves electrical interconnection through mechanical deformation. A press-fit connector consists of two parts: a pin base 310 and a pin 320. Figure 2 As shown, one end of the pin 320 extends into the concave slot 311 of the pin base 310, and the pin 320 is engaged with the pin base 310.

[0038] The other end of the pin 320 can be a fisheye groove design or a multi-wing design. The printed circuit board 500 is provided with a contact hole 510. When the other end of the pin 320 is inserted into the contact hole 510 of the printed circuit board 500, plastic deformation is generated by the interference fit between the other end of the pin 320 and the contact hole 510, and the pin 320 and the printed circuit board 500 are stably connected, realizing the electrical connection between the printed circuit board 500 and the chip 200.

[0039] In this embodiment, such as Figure 1 As shown, the pin base 310 is disposed on the first side of the substrate 100, and the pin base 310 can be soldered to the side of the first copper layer 110 facing away from the ceramic layer 130.

[0040] In practice, ultrasonic welding can be used to weld the pin base 310 to the first side of the substrate 100 to ensure the height consistency of the pin base 310 and improve the product yield.

[0041] Understandably, the encapsulation structure includes a molding compound 400, which provides integrated protection through electrical insulation, mechanical reinforcement, environmental sealing, thermal management, and stress buffering.

[0042] In practice, the molding compound 400 can be obtained by injection molding using epoxy molding compound (EMC).

[0043] In this embodiment, such as Figure 1 As shown, the molding compound 400 covers the first surface of the substrate 100 and exposes the concave slot 311 of the pin base 310, so that one end of the pin 320 can be inserted into the concave slot 311.

[0044] The following is a specific example.

[0045] like Figure 1 As shown, the pin base 310 is first soldered to the first surface of the substrate 100, and then encapsulated by the molding compound 400. The molding compound 400 covers the first surface of the substrate 100 and exposes the concave slot 311 of the pin base 310. The molding compound 400 does not block the concave slot 311 of the pin base 310. Figure 3 As shown, one end of the pin 320 is inserted into the concave slot 311 of the pin base 310, and the pin 320 is engaged with the pin base 310; as Figure 4 As shown, the other end of the pin 320 is inserted into the printed circuit board 500 to achieve an electrical connection between the printed circuit board 500 and the chip 200.

[0046] In this embodiment, a pin 320 is used instead of a lead for connection, eliminating the need for additional soldering on the printed circuit board 500. This effectively reduces the risk of failure caused by stress concentration, improves the mechanical reliability and long-term stability of the module, and also reduces the difficulty of the packaging process.

[0047] It is understandable that by using the packaging structure in power modules, different current paths can be formed by designing the number and position of the power terminals of the power modules, thus constructing different power conversion topologies for the power modules.

[0048] In some embodiments, the power terminals of the power module include at least two pin bases 310.

[0049] In actual implementation, the power terminal may include two or more pin bases 310, and the number and position of the pin bases 310 can be adjusted according to actual application requirements.

[0050] like Figure 5As shown, the pin bases 310 can be distributed around the perimeter of the substrate 100 to construct an H-bridge topology, including five power terminals: DC1-, DC2-, DC+, AC1, and AC2. Each power terminal includes at least two pin bases 310. The pin bases 310 of the H-bridge topology can also be as follows: Figure 6 The arrangement shown.

[0051] It is understandable that both the pin base 310 and the chip 200 are located on the first surface of the substrate 100, such as Figure 7 As shown, the second side of the substrate 100, that is, the side of the second copper layer 120 in the substrate 100 that faces away from the ceramic layer 130, is exposed.

[0052] In related technologies, when surface mount devices are soldered, there may be inconsistent solder paste thickness, resulting in inconsistent flatness of the copper layer on the top heat sink, which may damage the solder joints and plastic encapsulation during heat sink installation.

[0053] In this embodiment, crimped pins are used instead of pins in related technologies. During installation, the upper and lower contact surfaces are the substrate 100 and the molding compound 400, respectively, which maximizes the flatness of the module. Eliminating the pins from the molding compound 400 further reduces the module's space footprint. Simultaneously, contact holes 510 replace surface pads in related technologies on the printed circuit board 500, further improving connection reliability and space utilization. The overall flatness of the module is consistent, allowing for the use of large-area heat sinks to cover multiple modules simultaneously, reducing application costs. The pins 320 and pin bases 310 are installed separately; only the pin bases 310 need to be soldered, and the pins 320 can be directly inserted without secondary soldering. The molding compound 400 has high reliability, making power module installation convenient and reducing manufacturing complexity. The flexible layout of the pins 320 and pin bases 310, with low parasitic parameters, allows for an increase in the number of power terminals without increasing product size (e.g., within a module area not exceeding 800 mm²). 2 It contains four internally packaged chips forming an H-bridge topology, suitable for topologies such as half-bridge and H-bridge.

[0054] According to the packaging structure provided in the embodiments of this application, by setting the pin base 310 on the substrate 100 and directly inserting the pins 320 into the printed circuit board 500, the upper and lower contact surfaces during module installation are the substrate 100 and the molding compound 400, respectively, which can maximize the flatness of the module. Using pins 320 instead of pins for connection effectively reduces the risk of failure caused by stress concentration, improves the mechanical reliability and long-term stability of the module, and can also improve space utilization. By configuring the number and layout of pins 320, the current carrying capacity of the module can be improved, the inductance can be reduced, and power conversion topologies such as three-phase bridge and H-bridge can be constructed in a small area.

[0055] In some embodiments, the opening of the concave slot 311 is directly opposite to the contact hole 510, and the end of the pin base 310 near the printed circuit board 500 is spaced apart from the printed circuit board 500.

[0056] In this embodiment, the opening of the concave slot 311 is directly opposite to the contact hole 510, which facilitates the insertion of the pin 320 into the contact hole 510. The end of the pin base 310 closest to the printed circuit board 500 (the end where the opening of the concave slot 311 is located) is spaced apart from the printed circuit board 500. The opening of the concave slot 311 and the contact hole 510 do not directly contact each other, which facilitates the installation and removal of the pin 320 from the printed circuit board 500.

[0057] Understandably, the molding compound 400 covers the first surface of the substrate 100 and exposes the concave slot 311 of the pin base 310. The end of the pin base 310 near the printed circuit board 500 is spaced apart from the printed circuit board 500. That is, a certain gap is reserved between the molding compound 400 and the printed circuit board 500 to prevent the molding compound 400 and the printed circuit board 500 from being too tightly attached, which would cause inconvenience to the installation and disassembly of the package structure.

[0058] The embodiments of this application will be described in detail below from several different implementation perspectives.

[0059] In some embodiments, the molded body 400 has a first protrusion 410 on the side near the printed circuit board 500, and the end face of the first protrusion 410 contacts the side of the printed circuit board 500 near the molded body 400.

[0060] For example, such as Figure 4 As shown, the molded body 400 has a first protrusion 410 on the side near the printed circuit board 500. The end face of the first protrusion 410 contacts the side of the printed circuit board 500 near the molded body 400, so that the end of the pin base 310 near the printed circuit board 500 can be spaced apart from the printed circuit board 500.

[0061] In actual implementation, the height of the first protrusion 410 can be set according to the required reserved distance between the molding compound 400 and the printed circuit board 500. The height of the first protrusion 410 is greater than or equal to the required reserved distance between the molding compound 400 and the printed circuit board 500.

[0062] Understandably, the shape, number, and arrangement of the first protrusion 410 can be adjusted according to actual needs.

[0063] For example, such as Figure 5As shown, the molded body 400 has four cylindrical first protrusions 410 on the side near the printed circuit board 500. The pin base 310 is arranged in the surrounding area, and the four first protrusions 410 are arranged in the central area. The four first protrusions 410 are symmetrically arranged about the center of the molded body 400, which not only separates the distance between the molded body 400 and the printed circuit board 500, but also achieves balanced force distribution and effectively reduces the risk of failure caused by stress concentration.

[0064] In some embodiments, the packaging structure further includes a support plate 600.

[0065] In this embodiment, the first surface of the support plate 600 contacts the side of the molding compound 400 near the printed circuit board 500, and the second surface of the support plate 600 contacts the side of the printed circuit board 500 near the molding compound 400.

[0066] In practice, the support plate 600 can be made of high-temperature resistant and high-rigidity engineering plastics, such as polyphenylene sulfide (PPS).

[0067] It should be noted that the support plate 600 is disposed between the molding compound 400 and the printed circuit board 500. The support plate 600 provides the required clearance between the molding compound 400 and the printed circuit board 500, so that the end of the pin base 310 near the printed circuit board 500 can be spaced apart from the printed circuit board 500, which facilitates the installation and removal of the package structure.

[0068] Understandably, the thickness of the support plate 600 can be set according to the required clearance between the molding compound 400 and the printed circuit board 500. The support plate 600 can be fixed to the side of the printed circuit board 500 near the molding compound 400 first, and then the substrate 100 with the inserted pins 320 and the molding compound 400 can be assembled with the printed circuit board 500.

[0069] In some embodiments, the first surface of the support plate 600 has a second protrusion 610, and the side of the molding compound 400 near the printed circuit board 500 has a second concave groove 420, with the second protrusion 610 extending into the second concave groove 420.

[0070] like Figure 8 As shown, the side of the molding compound 400 closest to the printed circuit board 500 has a second recessed groove 420, and the molding compound 400 does not block the recessed slot 311 of the pin base 310, as shown. Figure 9 As shown, the second concave groove 420 can be spaced apart from the concave slot 311 of the exposed pin base 310, so that one end of the pin 320 can be inserted into the concave slot 311 of the pin base 310.

[0071] In practice, the second concave groove 420 can be obtained by injection molding or by removing part of the material from the side of the encapsulated body 400 that is close to the printed circuit board 500.

[0072] like Figure 10 As shown, a support plate 600 is disposed between the molding compound 400 and the printed circuit board 500. The side of the molding compound 400 near the printed circuit board 500 has a second concave groove 420. The first side of the support plate 600 has a second protrusion 610. The second protrusion 610 can extend into the second concave groove 420 of the molding compound 400. The support plate 600 provides the required reserved distance between the molding compound 400 and the printed circuit board 500. At the same time, the second protrusion 610 and the second concave groove 420 can also play a positioning role, which facilitates the alignment and installation of the support plate 600 and the molding compound 400.

[0073] In actual implementation, such as Figure 11 As shown, the first surface of the support plate 600 contacts the side of the molding compound 400 near the printed circuit board 500. The first surface of the support plate 600 has a second protrusion 610. The second surface of the support plate 600 contacts the side of the printed circuit board 500 near the molding compound 400. The second surface of the support plate 600 can be a flat surface.

[0074] For example, four second concave grooves 420 are provided on the side of the molding compound 400 near the printed circuit board 500, and four second protrusions 610 are provided on the first side of the support plate 600. The shapes of the second concave grooves 420 and the second protrusions 610 are matched, and the four second protrusions 610 extend into the corresponding second concave grooves 420 respectively. The support plate 600 and the molding compound 400 can be quickly aligned and assembled. The support plate 600 provides the required reserved gap between the molding compound 400 and the printed circuit board 500.

[0075] In this embodiment, the second side of the support plate 600 can be fixed to the side of the printed circuit board 500 near the molding compound 400 to prevent the support plate 600 from moving relative to the printed circuit board 500, thereby effectively improving the installation efficiency of the packaging structure.

[0076] In some embodiments, the projection pattern of the support plate 600 onto the substrate 100 does not cover the pin base 310, and the area of ​​the support plate 600 is smaller than the area of ​​the substrate 100.

[0077] The projection pattern of the support plate 600 onto the substrate 100 can be an orthographic projection. This projection pattern does not cover the pin base 310, meaning that the support plate 600 and the pins 320 inserted into the pin base 310 will not interfere with each other.

[0078] In this embodiment, the projection pattern of the support plate 600 on the substrate 100 does not cover the pin base 310. The pin base 310 can be arranged around the substrate 100, but the central area of ​​the substrate 100 does not have the pin base 310. The area of ​​the support plate 600 is smaller than the area of ​​the substrate 100. The support plate 600 is located in the central area of ​​the substrate 100, which can prevent the support plate 600 from interfering with the pins 320 inserted into the pin base 310.

[0079] In actual implementation, a second concave groove 420 for positioning can be arranged at a position corresponding to the center area of ​​the molding compound 400 and the substrate 100, so that the second protrusion 610 can extend into the second concave groove 420.

[0080] In some embodiments, the support plate 600 is provided with a positioning hole 620, and the projection of the support plate 600 on the substrate 100 covers the pin base 310, with the positioning hole 620 and the pin base 310 being directly opposite each other.

[0081] The projection pattern of the support plate 600 on the substrate 100 can be an orthographic projection, which covers the pin base 310. The positioning hole 620 of the support plate 600 is directly opposite to the pin base 310, and the pin 320 inserted into the pin base 310 can pass through the positioning hole 620.

[0082] In this embodiment, the positioning hole 620 on the support plate 600 is directly opposite to the pin base 310 on the substrate 100, so that the pin 320 inserted into the pin base 310 can pass through the positioning hole 620 and then extend into the contact hole 510 of the printed circuit board 500. The support plate 600 provides the required reserved gap between the molding compound 400 and the printed circuit board 500, and the positioning hole 620 is used for positioning, which facilitates the quick alignment and assembly of the support plate 600 and the molding compound 400.

[0083] like Figure 12 As shown, positioning holes 620 are arranged around the support plate 600, as... Figure 13 As shown, the positioning hole 620 on the support plate 600 is directly opposite to the pin base 310 on the base plate 100, and one positioning hole 620 can correspond to one or more pin bases 310.

[0084] like Figure 14 As shown, a support plate 600 is disposed between the molding compound 400 and the printed circuit board 500. Pins 320 inserted into the pin base 310 pass through the positioning holes 620 of the support plate 600 and extend into the contact holes 510 of the printed circuit board 500. The support plate 600 provides the required clearance between the molding compound 400 and the printed circuit board 500. Figure 15 As shown, the first and second surfaces of the support plate 600 can both be flat surfaces, effectively improving the overall flatness of the power module.

[0085] In some embodiments, the area of ​​the support plate 600 is greater than or equal to the area of ​​the substrate 100.

[0086] In this embodiment, positioning is achieved through the positioning hole 620 of the support plate 600, while preventing interference between the support plate 600 and the pin 320 inserted into the pin base 310. It is sufficient to ensure that the positioning hole 620 and the pin base 310 are aligned. The area of ​​the support plate 600 is greater than or equal to the area of ​​the substrate 100, which can also balance the force on the printed circuit board 500 and the molding compound 400.

[0087] Taking the support plate 600 and the base plate 100 as squares as an example.

[0088] like Figure 14 As shown, the side length of the support plate 600 is slightly larger than the side length of the substrate 100, and the area of ​​the support plate 600 is slightly larger than the area of ​​the substrate 100. The molding compound 400 covers the first surface of the substrate 100, and the area of ​​the molding compound 400 is slightly larger than the area of ​​the substrate 100. This can eliminate stress concentration between the molding compound 400 and the support plate 600, and significantly improve the module reliability and stability of the packaging structure.

[0089] This application also provides a packaging method that can be used to prepare the above-described packaging structure.

[0090] like Figure 16 As shown, the encapsulation method includes steps 1610 to 1650.

[0091] Step 1610: Print solder paste on the first side of the substrate 100, place the chip 200 at the solder paste printing position, and fix the chip 200 to the first side of the substrate 100 by soldering with solder paste.

[0092] The substrate 100 includes a first copper layer 110, a ceramic layer 130 and a second copper layer 120 stacked sequentially, and the first side of the substrate 100 can be the side of the first copper layer 110 facing away from the ceramic layer 130.

[0093] In this step, after solder paste is printed at a preset position on the first side of the substrate 100, the chip 200 is placed and the chip 200 is fixed to the first side of the substrate 100 by solder paste. After the solder paste is soldered, bonding wires 210 such as aluminum wires and copper wires can be used to connect the active area of ​​the chip 200 and different positions of the substrate 100.

[0094] Step 1620: Use ultrasonic welding equipment to weld the pin base 310 to the first side of the substrate 100.

[0095] In this step, the pin base 310 can be welded to a preset position on the first side of the substrate 100 using ultrasonic welding equipment, according to the topology of the power module. The ultrasonic welding process is mature and can ensure the high consistency of the pin base 310, thereby improving the product yield.

[0096] Step 1630: Injection molding is performed on the first side of the substrate 100 to obtain the encapsulated body 400.

[0097] The molding compound 400 covers the first surface of the substrate 100 and exposes the concave slot 311 of the pin base 310.

[0098] In practice, the molding compound 400 can be obtained by injection molding using epoxy molding compound (EMC).

[0099] In this embodiment, a first protrusion 410 or a second concave groove 420 can be formed on the side of the molding compound 400 near the printed circuit board 500. The molding compound 400 itself or the support plate 600 with the second protrusion 610 provides the required reserved gap between the molding compound 400 and the printed circuit board 500, so that the end of the pin base 310 near the printed circuit board 500 can be spaced apart from the printed circuit board 500, which facilitates the installation and removal of the package structure.

[0100] Step 1640: Insert one end of the pin 320 into the concave slot 311 to engage the pin 320 with the pin base 310.

[0101] Step 1650: Insert the other end of the pin 320 into the contact hole 510 of the printed circuit board 500, and the pin 320 is electrically connected to the printed circuit board 500.

[0102] In actual implementation, the other end of the pin 320 can be a fisheye groove design or a multi-wing design. The printed circuit board 500 is provided with a contact hole 510. When the other end of the pin 320 is inserted into the contact hole 510 of the printed circuit board 500, plastic deformation is generated by the interference fit between the other end of the pin 320 and the contact hole 510, and the pin 320 and the printed circuit board 500 are stably connected, realizing the electrical connection between the printed circuit board 500 and the chip 200.

[0103] The following is a specific example.

[0104] like Figure 17 As shown, S1, a clean substrate 100 is placed in a fixture, solder paste is filled into a fixed position using stencil printing, and the chip 200 is picked up from the wafer and placed in the pre-printed solder paste position using a chip bonding device.

[0105] S2. The substrate 100 with solder paste and chip 200 placed on it, together with the soldering fixture, is sent into the soldering furnace to solder chip 200 and substrate 100 together.

[0106] S3. After soldering, cool to room temperature and remove residual flux and other organic matter from the surface of the substrate 100 using cleaning equipment.

[0107] S4. Transfer the product to the wire bonding fixture and use bonding equipment to connect aluminum wires, copper wires, etc. to different sites on the active area of ​​the chip and the substrate 100.

[0108] S5. After bonding is completed, use an ultrasonic terminal bonding device to connect the pin base 310 to the copper layer (i.e., the first copper layer 110) on the substrate 100 via ultrasonic bonding, ensuring that the top of the pin base 310 (i.e. the opening of the concave slot 311) is consistent with the height of the subsequently formed molding compound 400.

[0109] S6. Place the substrate 100 in a cleaning device and use plasma to clean the entire substrate. Then place it in a spraying device and spray a layer of polyimide (PI) adhesive on the surface of the substrate 100, bonding wire 210, chip, and pin base 310 to enhance the bonding force with the molding compound 400.

[0110] S7. Apply a layer of adhesive film to the bottom of the substrate 100 to prevent oxidation and adhesive overflow. Insert the positioning point of the molding die into the hollow pin base 310 to prevent EMC from entering the base. Add EMC to the molding equipment for injection molding.

[0111] S8. After taking the product out, it is encapsulated and cured to eliminate some stress. The encapsulated body 400 covers the first side of the substrate 100 and exposes the concave slot 311 of the pin base 310.

[0112] S9. Place the product into the pin 320 device, insert the pin 320 into the pin base 310 to complete the product assembly, and then insert the other end of the pin 320 into the contact hole 510 of the printed circuit board 500.

[0113] According to the packaging method provided in the embodiments of this application, the chip 200 is fixed to the first surface of the substrate 100 by solder paste welding, the pin base 310 is welded to the substrate 100 by ultrasonic welding, and a molding compound 400 is obtained by injection molding on the first surface of the substrate 100. The molding compound 400 covers the first surface of the substrate 100 and exposes the concave slot 311 of the pin base 310. One end of the pin 320 is inserted into the pin base 310, and the other end of the pin 320 is directly inserted into the printed circuit board 500. The power module is easy to install, has low process difficulty, and can effectively reduce the failure risk caused by stress concentration. The power module has high reliability and can build power conversion topologies such as three-phase bridge and H-bridge in a small area.

[0114] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0115] In the description of this application, it should be understood that the terms "center", "thickness", "upper", "lower", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do 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. Therefore, they should not be construed as limitations on this application.

[0116] In the description of this application, "first feature" and "second feature" may include one or more of the features.

[0117] In the description of this application, "multiple" means two or more.

[0118] In the description of this application, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or the first and second features being in contact through another feature between them.

[0119] In the description of this application, the terms "above," "over," and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicate that the first feature is at a higher horizontal level than the second feature.

[0120] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a 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.

[0121] 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 packaging structure, characterized in that, include: substrate; A chip, wherein the chip is disposed on a first side of the substrate; A pin base, wherein the pin base is disposed on the first surface of the substrate; A molding compound, which covers the first surface of the substrate and exposes the concave slot of the pin base; A pin, one end of which extends into the concave slot and engages with the pin base; A printed circuit board, wherein the printed circuit board has a contact hole, the other end of the pin extends into the contact hole, and the pin is electrically connected to the printed circuit board.

2. The packaging structure according to claim 1, characterized in that, The opening of the concave slot is directly opposite the contact hole, and the end of the pin base near the printed circuit board is spaced apart from the printed circuit board.

3. The packaging structure according to claim 2, characterized in that, The molded encapsulation has a first protrusion on the side near the printed circuit board, and the end face of the first protrusion contacts the side of the printed circuit board near the molded encapsulation.

4. The packaging structure according to claim 2, characterized in that, Also includes: A support plate, wherein a first side of the support plate contacts the side of the molding compound closest to the printed circuit board, and a second side of the support plate contacts the side of the printed circuit board closest to the molding compound.

5. The packaging structure according to claim 4, characterized in that, The first side of the support plate has a second protrusion, and the side of the molding compound near the printed circuit board has a second concave groove, with the second protrusion extending into the second concave groove.

6. The packaging structure according to claim 5, characterized in that, The projection pattern of the support plate onto the substrate does not cover the pin base, and the area of ​​the support plate is smaller than the area of ​​the substrate.

7. The packaging structure according to claim 4, characterized in that, The support plate is provided with positioning holes, and the projection pattern of the support plate on the substrate covers the pin base. The positioning holes are directly opposite to the pin base.

8. The packaging structure according to claim 7, characterized in that, The area of ​​the support plate is greater than or equal to the area of ​​the substrate.

9. The packaging structure according to any one of claims 1-8, characterized in that, The chip is a silicon carbide metal oxide semiconductor field-effect transistor chip.

10. A packaging method, characterized in that, include: Solder paste is printed on the first side of the substrate, the chip is placed at the solder paste printing position, and the chip is fixed to the first side of the substrate by soldering with solder paste. The pin base is welded to the first side of the substrate using ultrasonic welding equipment; A molding compound is obtained by injection molding on the first side of the substrate. The molding compound covers the first side of the substrate and exposes the concave slot of the pin base. One end of the pin is inserted into the concave slot to engage the pin with the pin base; The other end of the pin is inserted into the contact hole of the printed circuit board, and the pin is electrically connected to the printed circuit board.

Images