Chip front heat dissipation structure, power module and manufacturing method

Abstract

The invention belongs to the technical field of semiconductor devices, and discloses a chip front heat dissipation structure, a power module and a manufacturing method.The chip front heat dissipation structure comprises a first ceramic copper-clad plate, a metal copper plate, a first copper strip and a second copper strip, and the two ends of the first copper strip and the two ends of the second copper strip are welded to the lower surface of the metal copper plate; the side, away from the metal copper plate, of the middle of the first copper strip is provided with a chip connecting part of an arched structure, the side, away from the metal copper plate, of the middle of the second copper strip is provided with a substrate connecting part of an arched structure, and the upper surface of the metal copper plate is welded to the lower surface of the first ceramic copper-clad plate. The chip front heat dissipation structure is excellent in heat conduction performance, the front heat dissipation effect of the chip is improved, and the chip front heat dissipation structure is stable in structure, high in integration degree and convenient to manufacture and install.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor module packaging, and in particular to a chip front heat dissipation structure, a power module and a manufacturing method thereof. Background Art

[0002] Power semiconductor devices (IGBT, MOSFET, SiC, GaN, etc.) are widely used in power supply and power electronics converter applications, and chip heat dissipation design is a core reliability indicator. In traditional power modules with single-sided heat dissipation, the heat dissipation structure is installed on the back of the chip. Bonding wires are also provided on the chip for current output, and the bonding wires are wrapped with potting glue to achieve electrical isolation and insulation safety. Potting glues include silicone gel and epoxy resin. The thermal conductivity of silicone gel is 0.3 W / (m·K), and the thermal conductivity of epoxy resin is 0.6 W / (m·K). They contribute very little to the heat dissipation of the chip. As a result, there is almost no heat transfer effect on the front of the chip. The power device mainly conducts heat through a single path on the back of the chip, resulting in poor heat dissipation.

[0003] Most of the double-sided heat dissipation structures currently available have additional soldering, spacer layers, AMB ceramic copper-clad laminate structures, etc. on the front side of the chip as heat conduction paths. The different materials used result in a low degree of integration, a complex connection process, and the stress generated by the plastic packaging process is easily transferred to the chip and substrate, increasing the probability of chip or ceramic cracking in the package, causing electrical and insulation performance failure, and reducing the chip packaging yield. Summary of the Invention

[0004] In response to the above-mentioned technical problems, the present invention proposes a chip front-side heat dissipation structure, a power module and a manufacturing method. The chip front-side heat dissipation structure is designed with a stable structure and good thermal conductivity, which improves the heat dissipation effect of the chip surface, realizes a double-sided heat dissipation path of the power module, and improves the heat dissipation effect and reliability of the power device.

[0005] To achieve this technical purpose, the present invention proposes the following technical solutions: A chip front heat dissipation structure includes a first ceramic copper-clad plate, a metal copper plate, a first copper strip and a second copper strip; Both ends of the first copper strip and the second copper strip are welded to the lower surface of the metal copper plate. A chip connection portion with an arched structure is provided on a side of the middle of the first copper strip away from the metal copper plate. A substrate connection portion with an arched structure is provided on a side of the middle of the second copper strip away from the metal copper plate. The upper surface of the metal copper plate is welded to the lower surface of the first ceramic copper-clad plate.

[0006] Preferably, the metal copper plate is provided with through holes at positions corresponding to the chip connection portion and the substrate connection portion, and the chip connection portion and the substrate connection portion are pressed down by a molding device and a supporting jig to form a contact plane.

[0007] Preferably, the first copper strip and the second copper strip are welded to the metal copper plate by ultrasonic welding, and the metal copper plate and the first ceramic copper-clad laminate are welded into one body by solder.

[0008] Preferably, the first ceramic copper-clad laminate comprises a first copper layer, an intermediate ceramic layer and a second copper layer arranged in sequence.

[0009] A power module comprises a housing, a chip, a second ceramic copper-clad plate and the chip front heat dissipation structure; The first ceramic copper clad plate is mounted on the top of the housing, with its upper surface exposed to the housing. A first electrode contact area is provided on the front of the chip, and the chip connection portion is butted against the first electrode contact area and connected by reflow soldering; The second ceramic copper clad board is arranged at the bottom of the shell, the upper surface of the second ceramic copper clad board is provided with a first pin, the back of the chip is fixed to the second ceramic copper clad board, and the substrate connection part is connected to the first pin and is connected by reflow soldering.

[0010] Preferably, the internal gap of the housing is filled with silica gel or epoxy resin, and the lower surface of the second ceramic copper clad board is provided with a metal heat dissipation base plate.

[0011] Preferably, a second electrode contact area is provided on the front side of the chip, a second pin is provided on the upper surface of the second ceramic copper clad board, and the second electrode contact area is connected to the second pin via a bonding wire; a third electrode contact area is provided on the back side of the chip, and the third electrode contact area is welded to the second ceramic copper clad board.

[0012] Preferably, a plurality of chips are provided inside the housing, and each chip is provided with a corresponding chip front heat dissipation structure.

[0013] A method for manufacturing a power module, comprising the following steps: Fabricating a front-side heat dissipation structure for the chip: ultrasonically welding two ends of a first copper strip having a chip connection portion with an arched structure and two ends of a second copper strip having a substrate connection portion with an arched structure to one surface of a metal copper plate, and then welding the other surface of the metal copper plate to a first ceramic copper-clad plate to obtain a front-side heat dissipation structure for the chip; Chip back mounting: Place the chip with the front side facing up on a second ceramic copper-clad laminate with solder printed on its upper surface. The front side of the chip is provided with a first electrode contact area, and the upper surface of the second ceramic copper-clad laminate is provided with a first pin. Chip front heat dissipation structure mounting: solder is printed on the first electrode contact area and the first pin, and the chip front heat dissipation structure is covered on the chip and the second ceramic copper clad board, so that the chip connection part is connected to the first electrode contact area and the substrate connection part is connected to the first pin; Reflow soldering reinforcement: The chip covered with the chip front heat dissipation structure is sent into the reflow soldering equipment, and the solder is melted by reflow soldering to form the corresponding solder connection layer.

[0014] Preferably, in the step of manufacturing the chip front heat dissipation structure, the metal copper plate is provided with through holes at positions corresponding to the chip connection portion and the substrate connection portion, and after the first copper strip and the second copper strip are ultrasonically welded to one side surface of the metal copper plate, the metal copper plate is placed horizontally with the side provided with the first copper strip and the second copper strip facing upward; The chip connection part and the substrate connection part are pressed and formed using a supporting jig and a molding device to form a contact plane of the arched structure; wherein, the molding device is provided with a lower pressing block, and the supporting jig is provided with a plurality of supporting columns, each supporting column passes through a through hole and contacts the inner surface of the arched structure of the corresponding chip connection part or substrate connection part, and the lower pressing block is located directly above the outer surface of the arched structure of the chip connection part or substrate connection part.

[0015] Due to the adoption of the above technical solution, the present invention has the following technical effects: 1) In this embodiment of the present invention, the first copper strip, the second copper strip, and the metal copper plate are all made of copper. Copper has a high thermal conductivity and is an excellent thermal conductor. The copper layer on the surface of the first ceramic copper-clad laminate further enhances thermal conductivity, providing both insulation and rapid heat dissipation. This increases the front-side thermal conductivity of the chip from the 0.3-0.6 W / (m·K) thermal conductivity of silicone gel or epoxy to over 28 W / (m·K) of the ceramic copper-clad laminate. The ends of the first and second copper strips are directly welded to the metal copper plate, which is in turn directly welded to the first ceramic copper-clad laminate. This allows heat to be transferred directly through the continuous structure of the copper strips, copper plate, and ceramic copper-clad laminate, preventing heat accumulation. The high connection strength makes the components a rigid whole, making electrical and insulation failure less likely to occur, thereby improving chip packaging yield.

[0016] 2) The power module proposed in the present invention has a front heat dissipation structure arranged on the upper surface of the chip. The upper surface of the first ceramic copper-clad plate of the front heat dissipation structure is exposed to the outer casing. The heat transferred by the front heat dissipation structure is quickly discharged to the outside of the power module through the window at the top of the outer casing, further improving the heat dissipation effect of the power module, reducing the thermal resistance of the power semiconductor device and the operating temperature of the chip, and ultimately improving the current output capacity and long-term reliability of the power semiconductor device.

[0017] 3) The chip front heat dissipation structure and power module proposed in the present invention are convenient for soldering to the chip and the ceramic copper-clad board pins below the chip through a solder reflow process. The process flow is simple and the packaging yield of the power module is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of a chip front heat dissipation structure proposed in the first embodiment of the present invention; Figure 2 A schematic diagram of a chip front heat dissipation structure is provided for the second embodiment of the present invention; Figure 3 Schematic diagram of copper strip stamping in the present invention; Figure 4 A schematic diagram of a power module is provided for the third embodiment of the present invention; Figure 5 A schematic diagram of a power module is provided for the fourth embodiment of the present invention; Among them: 1. First ceramic copper clad laminate; 11. First copper layer; 12. Middle ceramic layer; 13. Second copper layer; 2. Metal copper plate; 21. Through hole; 3. First copper strip; 31. Chip connection part; 4. Second copper strip; 41. Substrate connection part; 5. Molding equipment; 6. Support fixture; 100. Housing; 200. Chip; 300. Second ceramic copper clad laminate; 301. First pin; 302. Second pin; 400. Metal heat dissipation base; 500. Bonding wire; 600. Solder. DETAILED DESCRIPTION

[0019] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0020] Example 1 like Figure 1 As shown, this embodiment provides a chip front heat dissipation structure, including: a first ceramic copper clad plate 1, a metal copper plate 2, a first copper strip 3 and a second copper strip 4.

[0021] The first copper strip 3 includes at least two fixing points, which are welded to the lower surface of the metal copper plate 2. A chip connection portion 31 is formed between the fixing points, arching away from the lower surface of the metal copper plate 2. In this embodiment, the first copper strip 3 includes a first fixing point, an intermediate fixing point, and a second fixing point arranged in a row, all of which are welded to the lower surface of the metal copper plate 2. The chip connection portion 31 is formed between the first and intermediate fixing points, arching away from the lower surface of the metal copper plate 2. An elastic portion is formed between the intermediate and second fixing points, arching away from the lower surface of the metal copper plate 2.

[0022] The second copper strip 4 includes at least two fixing points, which are welded to the lower surface of the metal copper plate 2. A base connecting portion 41 is formed between the fixing points, arching away from the lower surface of the metal copper plate 2. In this embodiment, the second copper strip 4 includes a first fixing point, an intermediate fixing point, and a second fixing point arranged in a row, all of which are welded to the lower surface of the metal copper plate 2. The base connecting portion 41 arching away from the lower surface of the metal copper plate 2 is formed between the first and intermediate fixing points, and an elastic portion arching away from the lower surface of the metal copper plate 2 is formed between the intermediate and second fixing points.

[0023] The upper surface of the metal copper plate 2 is welded to the lower surface of the first ceramic copper-clad laminate 1. The first ceramic copper-clad laminate 1 includes a first copper layer 11, an intermediate ceramic layer 12, and a second copper layer 13, arranged in sequence. In this embodiment, the ends of the intermediate ceramic layer 12 extend beyond the ends of the first copper layer 11. The first and second copper layers 11, 13 are of equal length and aligned at their ends.

[0024] The front-side chip heat dissipation structure disclosed in Example 1 comprises a first copper layer 11, a second copper layer 13, a metal copper plate 2, a first copper tape 3, and a second copper tape 4, forming a continuous, highly conductive path between the chip, the copper tape, the metal copper plate, and the copper layer of the ceramic copper-clad laminate. This reduces thermal resistance and accelerates heat transfer from the chip to the external heat sink. The intermediate ceramic layer 12 extends beyond the first copper layer 11 at both ends, increasing the heat dissipation area, particularly at the edges. This improves the efficiency of heat dissipation by radiation or convection into the air and prevents localized heat accumulation.

[0025] In addition, in this embodiment, the first copper strip 3 and the second copper strip 4 are both welded to the metal copper plate 2 at multiple fixing points, significantly improving the connection strength between the copper strips and the metal copper plate and reducing the risk of welds falling off. The first copper strip 3 and the second copper strip 4 are not only provided with a raised connection portion between the fixing points, but also with an additional raised elastic portion. This can buffer thermal and mechanical stresses through multi-stage deformation, further protecting the weld points and the chip body from cracking or contact failure. At the same time, the raised connection portion and the elastic portion together provide greater elastic expansion space, ensuring a tight fit between the chip connection portion 31 and the chip electrode contact area, and between the substrate connection portion 41 and the substrate pins.

[0026] This embodiment significantly improves structural reliability, assembly fault tolerance, and functional compatibility, and is suitable for chip packaging scenarios with high requirements for heat dissipation and stability.

[0027] Example 2 This embodiment proposes a chip front heat dissipation structure, such as Figure 2 As shown, the main difference from the first embodiment is that the metal copper plate 2 is provided with through holes 21 at positions corresponding to the chip connection portion 31 and the substrate connection portion 41 .

[0028] like Figure 3 As shown, the chip connection portion 31 and the substrate connection portion 41 are pressed down by the molding equipment 5 and the supporting fixture 6 to form a contact plane at the outer end of the arch structure, and the contact plane is parallel to the surface of the chip 200 .

[0029] When the chip front heat dissipation structure is installed on the chip 200, the contact plane is connected to the front of the chip 200, which can further ensure the bonding effect between the chip connection part 31 and the chip electrode contact area, and the substrate connection part 41 and the substrate pin.

[0030] Example 3 like Figure 4 As shown, this embodiment proposes a power module, including a housing 100, a chip 200, and a second ceramic copper-clad laminate 300. A plurality of chips 200 are arranged inside the housing 100, and each chip 200 is provided with a corresponding chip front heat dissipation structure. The chip front heat dissipation structure can adopt either embodiment 1 or embodiment 2. Among them, the top of the housing 100 is provided with a window for installation and heat dissipation. The first ceramic copper-clad laminate 1 is installed at the window on the top of the housing 100, and the upper surface, i.e., the first copper layer 11, is exposed to the housing 100. The window on the top of the housing 100 overlaps the edge of the intermediate ceramic layer 12. The front of the chip 200 is provided with a first electrode contact area, and the chip connection portion 31 is connected to the first electrode contact area and connected by reflow soldering. The second ceramic copper-clad laminate 300 is arranged at the bottom of the housing 100. The upper surface of the second ceramic copper-clad laminate 300 is provided with a first pin 301. The back of the chip 200 is fixed to the second ceramic copper-clad laminate 300, and the substrate connection portion 41 is connected to the first pin 301 and connected by reflow soldering. The internal gap of the housing 100 is filled with silica gel or epoxy resin, and a metal heat dissipation base plate 400 is provided on the lower surface of the second ceramic copper clad board 300 .

[0031] The power module in this embodiment has the chip front heat dissipation structure described in Example 1 installed on the front of the chip 200. In addition, the top of the housing 100 is not a closed structure. The heat emitted from the front of the chip 200 is transferred through the continuous structure of copper strips, copper plates, and ceramic copper-clad laminates, and can be quickly discharged to the outside of the module through the window at the top of the housing 100, further improving the heat dissipation effect of the module.

[0032] Example 4 like Figure 5 As shown, this embodiment proposes a power module, which is different from the fourth embodiment in that a second electrode contact area is further provided on the front of the chip 200, a second pin 302 is provided on the upper surface of the second ceramic copper clad board 300, and the second electrode contact area is connected to the second pin 302 via a bonding wire 500; a third electrode contact area is provided on the back of the chip 200, and the third electrode contact area is welded to the second ceramic copper clad board 300.

[0033] In this embodiment, the power module is installed with the front heat dissipation structure, which not only plays a role in heat dissipation but also provides a certain support for the space from the front of the chip 200 to the top of the housing 100. The second electrode contact area on the chip 200 can still be electrically connected through the bonding wire 500. Compared with the traditional chip 200 with two electrodes on the front, one bonding wire is reduced, and it does not affect the use of any of the front heat dissipation structures in Example 1 or Example 2.

[0034] Example 5 This embodiment provides a method for manufacturing a power module, comprising the following steps: Fabricating a front-side heat dissipation structure for the chip: ultrasonically weld the two ends of a first copper strip 3 having a chip connection portion 31 with an arched structure and the two ends of a second copper strip 4 having a substrate connection portion 41 with an arched structure to one surface of a metal copper plate 2, and then weld the other surface of the metal copper plate 2 to a first ceramic copper-clad laminate 1 to obtain the front-side heat dissipation structure for the chip. This step combines the various components of the front-side heat dissipation structure for the chip into a rigid whole, resulting in high connection strength, convenient subsequent installation, and less prone to electrical and insulation failure, thereby improving the chip packaging yield. Chip back mounting: Place the chip 200 with the front side facing up on the second ceramic copper clad laminate 300 with solder 600 printed on its upper surface. The front side of the chip 200 is provided with a first electrode contact area, and the upper surface of the second ceramic copper clad laminate 300 is provided with a first pin 301. Chip front heat dissipation structure mounting: Solder 600 is printed on the first electrode contact area and the first pin 301, and the chip front heat dissipation structure is covered on the chip 200 and the second ceramic copper clad board 300, so that the chip connection part 31 is connected to the first electrode contact area and the substrate connection part 41 is connected to the first pin 301; Reflow soldering reinforcement: The chip 200 covered with the chip front heat dissipation structure is sent into a reflow soldering device, and the solder 600 is melted by reflow soldering to form a corresponding solder 600 connection layer.

[0035] Shell packaging: Place the reflow-soldering device into the shell, and perform silicone gel or epoxy resin potting or plastic sealing on the device to complete the packaging structure.

[0036] In the above-mentioned steps of making the chip front heat dissipation structure, if the metal copper plate 2 is provided with a through hole 21 at the position corresponding to the chip connection part 31 and the substrate connection part 41, then after the first copper tape 3 and the second copper tape 4 are welded to one side surface of the metal copper plate 2 by ultrasonic welding, the metal copper plate 2 is placed horizontally with the side provided with the first copper tape 3 and the second copper tape 4 facing upward; then the chip connection part 31 and the substrate connection part 41 are pressed and molded using the supporting jig 6 and the molding equipment 5 to form a contact plane of the arched structure.

[0037] The molding device 5 is provided with a pressing block, and the supporting fixture 6 is provided with a plurality of supporting columns. Each supporting column passes through the through hole 21 and contacts the inner surface of the arched structure of the corresponding chip connection portion 31 or substrate connection portion 41. The supporting column supports the corresponding chip connection portion 31 or substrate connection portion 41 during the pressing process. The pressing block presses down directly above the outer surface of the arched structure of the chip connection portion 31 or substrate connection portion 41.

[0038] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A chip front heat dissipation structure, characterized by: It comprises a first ceramic copper-clad plate (1), a metal copper plate (2), a first copper strip (3) and a second copper strip (4); Both ends of the first copper strip (3) and the second copper strip (4) are welded to the lower surface of the metal copper plate (2); a chip connection portion (31) with an arched structure is provided on a side of the middle portion of the first copper strip (3) away from the metal copper plate (2); and a substrate connection portion (41) with an arched structure is provided on a side of the middle portion of the second copper strip (4) away from the metal copper plate (2); The upper surface of the metal copper plate (2) is welded to the lower surface of the first ceramic copper-clad plate (1).

2. The chip front heat dissipation structure according to claim 1, characterized in that: The metal copper plate (2) is provided with a through hole (21) at a position corresponding to the arched structure of the chip connection portion (31) and the substrate connection portion (41), and the arched structure is provided with a contact plane.

3. The chip front heat dissipation structure according to claim 1, characterized in that: The first copper strip (3) and the second copper strip (4) are welded to the metal copper plate (2) by ultrasonic welding, and the metal copper plate (2) and the first ceramic copper-clad plate (1) are welded into one body by solder (600).

4. The chip front heat dissipation structure according to claim 1, characterized in that: The first ceramic copper-clad plate (1) comprises a first copper layer (11), an intermediate ceramic layer (12), and a second copper layer (13) which are arranged in sequence.

5. A power module, characterized in that: It comprises a housing (100), a chip (200), a second ceramic copper-clad plate (300), and a chip front heat dissipation structure according to any one of claims 1 to 4; The first ceramic copper-clad plate (1) is mounted on the top of the housing (100), with the upper surface exposed from the housing (100); a first electrode contact area is provided on the front of the chip (200); the chip connection portion (31) is connected to the first electrode contact and is connected by reflow soldering; The second ceramic copper-clad plate (300) is arranged at the bottom of the housing (100), a first pin (301) is provided on the upper surface of the second ceramic copper-clad plate (300), the back surface of the chip (200) is fixed on the second ceramic copper-clad plate (300), and the substrate connection portion (41) is connected to the first pin (301) and is connected by reflow soldering.

6. The power module according to claim 5, wherein: The internal gap of the housing (100) is filled with silica gel or epoxy resin, and the lower surface of the second ceramic copper-clad board (300) is provided with a metal heat dissipation base plate (400).

7. The power module according to claim 5, wherein: A second electrode contact area is provided on the front surface of the chip (200), a second pin (302) is provided on the upper surface of the second ceramic copper-clad plate (300), and the second electrode contact area is connected to the second pin (302) via a bonding wire (500); a third electrode contact area is provided on the back surface of the chip (200), and the third electrode contact area is welded to the second ceramic copper-clad plate (300).

8. The power module according to claim 5, wherein: A plurality of chips (200) are provided inside the housing (100), and each chip (200) is provided with a corresponding chip front heat dissipation structure.

9. A method for manufacturing a power module, characterized in that: The following steps are involved: Manufacturing a chip front heat dissipation structure: welding two ends of a first copper strip (3) having a chip connection portion (31) with an arched structure and two ends of a second copper strip (4) having a substrate connection portion (41) with an arched structure to one side surface of a metal copper plate (2) by ultrasonic welding, and then welding the other surface of the metal copper plate (2) to a first ceramic copper-clad plate (1), thereby obtaining a chip front heat dissipation structure; Chip back mounting: placing the chip (200) with the front side facing upward on a second ceramic copper-clad plate (300) with solder 600 printed on its upper surface, the front side of the chip (200) being provided with a first electrode contact area, and the upper surface of the second ceramic copper-clad plate (300) being provided with a first pin (301); Chip front heat dissipation structure mounting: solder 600 is printed on the first electrode contact area and the first pin (301), and the chip front heat dissipation structure is covered on the chip (200) and the second ceramic copper clad plate (300), so that the chip connection portion (31) is connected to the first electrode contact area, and the substrate connection portion (41) is connected to the first pin (301); Reflow soldering reinforcement: the chip (200) covered with the chip front heat dissipation structure is sent into a reflow soldering device, and the solder 600 is melted by reflow soldering to form a corresponding solder 600 connection layer.

10. The method for manufacturing a power module according to claim 9, characterized in that: In the step of manufacturing the chip front heat dissipation structure, the metal copper plate (2) is provided with a through hole (21) at a position corresponding to the chip connection portion (31) and the substrate connection portion (41), and after the first copper strip (3) and the second copper strip (4) are welded to one side surface of the metal copper plate (2) by ultrasonic welding, the metal copper plate (2) is placed horizontally with the side provided with the first copper strip (3) and the second copper strip (4) facing upward; The chip connection part (31) and the substrate connection part (41) are pressed and molded using a support jig (6) and a molding device (5) to form a contact plane of the arched structure; wherein the molding device (5) is provided with a lower pressing block, and the support jig (6) is provided with a plurality of supporting columns, each supporting column passes through a through hole (21) and contacts the inner surface of the arched structure of the corresponding chip connection part (31) or substrate connection part (41), and the lower pressing block is pressed down directly above the outer surface of the arched structure of the chip connection part (31) or substrate connection part (41).

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