Single-phase full-bridge intelligent power module based on gallium nitride power chip and manufacturing method

Abstract

Single-phase full-bridge intelligent power module based on gallium nitride power chip and manufacturing method, including ceramic substrate, power chip, drive chip, power copper surface, decoupling capacitor, printed circuit board and shell; a plurality of power copper surfaces are arranged on the ceramic substrate, gaps are left between adjacent power copper surfaces, the decoupling capacitor and the power chip are arranged on the power copper surface; the printed circuit board is covered on the ceramic substrate, and a plurality of drive chips are arranged on the printed circuit board; the ceramic substrate, the power chip, the drive chip, the power copper surface, the decoupling capacitor and the printed circuit board are arranged in the shell. The processing flow designed by the application is easy to realize the automation of power module processing and preparation, effectively reduces the preparation steps of the power module, improves the yield of the power module preparation, and the raw material cost of processing and use is low, effectively controls the production cost of the power module. At the same time, the preparation process can guarantee the electrical insulation performance and the reliability of the electrical bonding connection in the power module.

Description

Technical Field

[0001] This invention belongs to the field of power module technology, and specifically relates to a single-phase full-bridge intelligent power module based on gallium nitride power chips and its manufacturing method. Background Technology

[0002] Power modules are modules that integrate and package power electronic chips. Compared to discrete devices, they offer higher reliability, lower parasitic parameters, higher power density, and lower losses, playing a crucial role in power electronics applications. Intelligent power modules integrate driver and power chips during the design process, reducing the complexity of peripheral circuit design. Current packaging technologies also offer customized packaging for specific topologies, improving the efficiency of power electronic converters and enhancing the reliability of power electronic devices.

[0003] Currently, novel packaging technologies proposed for power modules designed with wide bandgap semiconductors all suffer from difficulties in fabrication processes and low module manufacturing reliability. Overly complex processing can lead to decreased power module reliability and low product yield, hindering the large-scale application of wide bandgap power modules. Summary of the Invention

[0004] The purpose of this invention is to provide a single-phase full-bridge intelligent power module based on gallium nitride power chips and its manufacturing method, so as to solve the above-mentioned problems.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A single-phase full-bridge intelligent power module based on gallium nitride power chips includes a ceramic substrate, a power chip, a driver chip, power copper surfaces, decoupling capacitors, a printed circuit board, and a housing. Several power copper surfaces are disposed on the ceramic substrate, with gaps between adjacent power copper surfaces. The decoupling capacitors and power chips are disposed on the power copper surfaces. The printed circuit board covers the ceramic substrate, and several driver chips are disposed on the printed circuit board. The ceramic substrate, power chip, driver chip, power copper surfaces, decoupling capacitors, and printed circuit board are all disposed within the housing.

[0007] Furthermore, the power copper surface includes a first power copper surface, a second power copper surface, a third power copper surface, a fourth power copper surface, and a fifth power copper surface; the power chip includes a first power chip, a second power chip, a third power chip, and a fourth power chip; the second power chip is disposed on the third power copper surface; the third power chip is disposed on the first power copper surface; the first power chip is connected to the fifth power copper surface and the printed circuit board via bonding wires; the second power chip is connected to the printed circuit board and the fourth power copper surface via bonding wires; the third power chip is connected to the printed circuit board, the first power copper surface, and the second power copper surface via bonding wires; and the fourth power chip is connected to the printed circuit board, the first power copper surface, and the third power copper surface via bonding wires.

[0008] Furthermore, the decoupling capacitor includes a first decoupling capacitor and a second decoupling capacitor; the second decoupling capacitor is disposed on the fifth power copper surface, and the first decoupling capacitor is disposed on the second power copper surface.

[0009] Furthermore, power terminals are provided on the first power copper surface, the second power copper surface, the third power copper surface, the fourth power copper surface, and the fifth power copper surface.

[0010] Furthermore, the bottom copper layer of the printed circuit board and the top copper layer of the ceramic substrate are connected by solder, and the two copper layers have no electrical connection properties.

[0011] Furthermore, the printed circuit board is also equipped with several drive terminals.

[0012] Furthermore, solder pins are provided on all drive terminals.

[0013] Furthermore, each driver chip is connected to peripheral circuitry.

[0014] Furthermore, the housing includes a graphite clamp base, a graphite sheet clamp top cover, and a power module housing, with the graphite clamp base and graphite sheet clamp top cover positioned at both ends of the power module housing to form the housing.

[0015] Furthermore, the fabrication method of a single-phase full-bridge smart power module based on gallium nitride power chips includes the following steps:

[0016] Step 1: Apply solder to the ceramic substrate using a stencil; place the power copper plate, power chip, power terminals, and decoupling capacitor onto the ceramic substrate and solder them.

[0017] Step 2: Use a stencil to apply solder paste to the designated locations on the printed circuit board, and place the driver chip and peripheral circuitry in the locations where the solder paste has been applied.

[0018] Step 3: Place the driver printed circuit board on the power ceramic substrate, place the entire power module in a specific graphite fixture, and adjust the position of the nuts to fix the power chip, power terminals, driver terminals and decoupling capacitors.

[0019] Step 4: The entire power module is placed in a vacuum reflow soldering machine for soldering;

[0020] Step 5: Clean the power module with anhydrous ethanol to remove residual flux from the surface;

[0021] Step 6: Use a bonding machine to connect the power chip to the copper surface on the ceramic substrate; use gold bonding wire or aluminum bonding wire to connect the power chip to the copper surface on the printed circuit board.

[0022] Step 7: Use a robotic arm to embed the welding pins into the power base and drive base, cover the outside of the module with the module shell, pour the silicone gel into the module, let it stand until the silicone gel solidifies, and then perform electrical, thermal and reliability tests.

[0023] Compared with the prior art, the present invention has the following technical effects:

[0024] This module designs a gallium nitride (GaN)-based full-bridge layout, effectively reducing overvoltage and current oscillations during chip turn-on and turn-off, and avoiding overvoltage and overcurrent phenomena in GaN chips. The module integrates the driver chip within the module, optimizes the drive circuit, and reduces the possibility of false turn-on of the GaN chip.

[0025] The processing flow designed in this invention facilitates the automation of power module fabrication, effectively reduces the number of steps in power module fabrication, improves the yield rate of power modules, and uses low-cost raw materials, effectively controlling the production cost of power modules. Simultaneously, the fabrication process ensures the internal electrical insulation performance and the reliability of electrical bonding connections within the power module. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating the processing technology described in this invention;

[0027] Figure 2 This is a schematic diagram showing the connection between the power chip, decoupling capacitor, power terminals, and ceramic substrate fabricated based on this processing flow.

[0028] Figure 3 This is a schematic diagram of the connection of driver chips, terminals, etc., prepared based on this processing flow on a printed circuit board;

[0029] Figure 4 This is a schematic diagram showing the connection between the graphite fixture and the power module prepared based on this processing flow;

[0030] Figure 5 This is a schematic diagram of the bonding direction of the bonding lines of the power chip, ceramic substrate, and printed circuit board prepared based on this processing flow.

[0031] Figure 6 This is a schematic diagram of the connection between the power pin and the power terminal prepared based on this processing flow;

[0032] Figure 2 Marks 2 and 7 indicate that the substrate is not soldered to the bottom surface. Figure 5 , 6 The middle part describes the state of the weld.

[0033] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0034] in

[0035] 1. Ceramic substrate; 2. First power chip; 3. Second power chip; 4. First decoupling capacitor; 5. Third power chip; 6. Fourth power chip; 7. Second decoupling capacitor; 8. First power terminal; 9. First power copper surface; 10. Second power terminal; 11. Third power terminal; 12. Second power copper surface; 13. Third power copper surface; 14. Fourth power copper surface; 15. Fourth power terminal; 16. Fifth power terminal; 17. Fifth power copper surface; 18. Sixth power terminal; 19. Seventh power terminal; 20. Eighth power terminal; 21. Ninth power terminal; 22. Printed circuit board; 23. Fourth driver chip; 24. First driver terminal; 25. Second driver terminal; 26. Third driver terminal; 27. Third driver chip; 28. Fourth driver terminal; 29. ​​Fifth driver terminal; 30. 31. Sixth drive terminal; 32. Seventh drive terminal; 33. Eighth drive terminal; 34. Ninth drive terminal; 35. Second drive chip; 36. Tenth drive terminal; 37. Eleventh drive terminal; 38. Twelfth drive terminal; 39. First drive chip; 40. Solder pin; 41. Power module housing; 42. Graphite fixture base; 43. Graphite sheet fixture top cover; 44. Fixing nut; Detailed Implementation

[0036] This invention provides a single-phase full-bridge intelligent power module based on a gallium nitride (GaN) power chip to improve the reliability of power modules fabricated based on GaN power chips. The module includes a ceramic substrate 1, a power chip, a driver chip, power copper surfaces, a decoupling capacitor, a printed circuit board 22, and a housing. Several power copper surfaces are disposed on the ceramic substrate 1, with gaps between adjacent power copper surfaces. The decoupling capacitor and the power chip are disposed on the power copper surfaces. The printed circuit board 22 covers the ceramic substrate 1 and has several driver chips disposed on it. The ceramic substrate 1, power chip, driver chip, power copper surfaces, decoupling capacitor, and printed circuit board 22 are all housed within the housing.

[0037] To achieve the above objectives, the following materials and equipment are required for this processing method:

[0038] The system provides: a ceramic substrate with sintered copper layers on both sides; a printed circuit board consisting of four circuit layers and three insulating layers, with multiple solder ports (with the insulating layers removed) on the top layer of the printed circuit board; commercially available driver chips and power chips required for the power module; decoupling capacitors, resistors, and diodes required for the peripheral circuits of the driver chips; several custom terminals; a solder paste stencil for applying solder paste to designated locations on the ceramic substrate and circuit board; a custom module housing; commercially available sealing silicone gel; commercially available volatile medium-strong acid and anhydrous ethanol; commercially available solder paste; custom graphite clamps and nuts; custom bonding clamps; commercially available aluminum wire bonding machines and aluminum bonding wires; commercially available gold wire bonding machines and gold bonding wires; and a commercially available vacuum heating furnace.

[0039] The processing steps are as follows:

[0040] 1. Apply solder paste to the surface of the ceramic substrate using a stencil. The stencil should be of appropriate thickness to ensure that the solder can complete the soldering of the terminals without applying too much.

[0041] 2. Apply solder paste to the surface of the printed circuit board using a stencil, and place the driver chip, decoupling capacitor, resistor, driver diode chip, and driver terminals in the designated positions.

[0042] 3. Place the power chip, power terminals, and decoupling capacitors at designated locations on the ceramic substrate. Place the driver printed circuit board on the ceramic substrate; the bottom copper layer of the printed circuit board and the top copper layer of the ceramic substrate are connected by solder, but the copper layers of the two have no electrical connection.

[0043] 4. The ceramic substrate and printed circuit board are stacked and placed in a customized graphite fixture. The graphite fixture has holes at designated locations for flux evaporation and to secure the drive terminals. The graphite fixture also has threads at designated locations; adjusting the nut height allows for gentle pressure on the power chip and power terminals, preventing solder melting and chip misalignment.

[0044] 5. The power module is placed in a commercial vacuum soldering oven, and the temperature profile corresponding to the solder paste is set for vacuum soldering.

[0045] 6. Use specialized cleaning equipment and anhydrous ethanol to clean residual flux on the surface of power chips, driver chips, etc.

[0046] 7. Secure the power module using a customized bonding fixture, and then use a commercial bonding machine to connect the power chip to the specified copper surface of the ceramic substrate. Bonding machine parameters need to be adjusted to ensure a reliable connection between the bonding aluminum wires and the chip / copper foil, while keeping chip damage within a controllable range.

[0047] 8. Use customized bonding fixtures to fix the power module, and use commercial bonding machines to complete the connection between the copper surface of the driver chip and the power chip.

[0048] 9. Insert the terminal pins into the power terminals.

[0049] 10. Place the power module into a customized module housing and inject commercial insulating silicone gel into the housing to protect the bonding wires and ensure insulation.

[0050] 11. Conduct a series of module electrical characteristic and reliability tests.

[0051] Example:

[0052] according to Figure 1 The processing flow shown is as follows: First, a stencil is used to apply solder (SAC305) to the designated location on the ceramic substrate.

[0053] The second step involves placing the first power chip, the second power chip, the third power chip, the fourth power chip, as well as power terminals, the first decoupling capacitor, and the second decoupling capacitor at designated locations on the ceramic substrate.

[0054] The third step is to apply solder (SAC305) to the designated locations on the printed circuit board using a stencil.

[0055] The fourth step is to place the first driver chip, the second driver chip, the third driver chip, the fourth driver chip, and peripheral passive components and printed circuit board driver terminals into the designated positions for applying solder paste.

[0056] The fifth step is to place the driver printed circuit board at the designated location on the power ceramic substrate.

[0057] The sixth step is to place the entire power module in a specific graphite fixture and adjust the position of the nuts to fix the first power chip, the second power chip, the third power chip, the fourth power chip, the power terminals, the drive terminals, and the first and second decoupling capacitors of the power circuit.

[0058] The seventh step involves placing the entire power module in a commercially available vacuum reflow soldering machine for soldering.

[0059] Step 8: Use specialized equipment and anhydrous ethanol to clean the power module and remove residual flux from the surface.

[0060] Step 9: Using a commercial bonding machine, connect the power chip to the designated copper surface on the ceramic substrate, using bonding wires with a diameter of 5 mil. Connect the source terminals of the first and second power chips to the designated copper layer on the ceramic substrate. Connect the drain and source terminals of the third and fourth power chips to the designated copper layer. Use commercial gold or aluminum bonding wires to connect the power chip to the designated copper surface on the printed circuit board, using gold bonding wires with a diameter of 1 mil and aluminum bonding wires with a diameter of 5 mil.

[0061] The tenth step involves using a robotic arm to embed the welding pins into the power base and drive base.

[0062] Step 11: Cover the outside of the module with the custom module shell.

[0063] Step 12: Inject silicone gel into the module through the round hole on the module shell to protect the bonding wires, protect the chip, and ensure insulation strength.

[0064] Step 13: After the silicone gel has solidified, conduct tests on its electrical, thermal, and reliability characteristics.

[0065] The power chips, driver chips, peripheral passive devices, ceramic substrates, and printed circuit boards used in this module are all commercially available products. The structure of the module mentioned in this application is merely an example of the process and not a limitation. Figures 2-6 The internal structure of the module shown is only for the purpose of illustrating the processing technology and process of this patent design, and is not intended to limit it.

[0066] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "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 the invention. 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.

[0067] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" 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 invention 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 invention.

[0068] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0069] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0070] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0071] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A single-phase full-bridge intelligent power module based on gallium nitride power chips, characterized in that, The device includes a ceramic substrate (1), a power chip, a driver chip, a power copper surface, a decoupling capacitor, a printed circuit board (22), and a housing. The power copper surface is disposed on the ceramic substrate (1), with gaps between adjacent power copper surfaces. The decoupling capacitor and the power chip are disposed on the power copper surface. The printed circuit board (22) covers the ceramic substrate (1), and the driver chip is disposed on the printed circuit board (22). The driver chip and the printed circuit board are connected by copper, and the driver chip is used to drive the power chip. The ceramic substrate (1), power chip, driver chip, power copper surface, decoupling capacitor and printed circuit board (22) are all housed inside the housing; The power copper surface includes a first power copper surface (9), a second power copper surface (12), a third power copper surface (13), a fourth power copper surface (14), and a fifth power copper surface (17); the power chip includes a first power chip (2), a second power chip (3), a third power chip (5), and a fourth power chip (6); the copper plating and the gate and source of the power chip are connected by bonding; the second power chip (3) is disposed on the third power copper surface (13); the third power chip (5) is disposed on the first power copper surface (9); the first power chip (2) is connected to the fifth power copper surface (17) and the printed circuit board (22) by bonding wires; the second power chip (3) is connected to the printed circuit board (22) and the fourth power copper surface (14) by bonding wires; the third power chip (5) is connected to the printed circuit board (22), the first power copper surface (9), and the second power copper surface (12) by bonding wires; the fourth power chip (6) is connected to the printed circuit board (22), the first power copper surface (9), and the third power copper surface (13) by bonding wires.

2. The single-phase full-bridge intelligent power module based on gallium nitride power chip according to claim 1, characterized in that, The decoupling capacitors include a first decoupling capacitor (4) and a second decoupling capacitor (7); the second decoupling capacitor (7) is disposed on the fifth power copper surface (17), and the first decoupling capacitor (4) is disposed on the second power copper surface (12).

3. The single-phase full-bridge intelligent power module based on gallium nitride power chip according to claim 1, characterized in that, Power terminals (8) are provided on the first power copper surface (9), the second power copper surface (12), the third power copper surface (13), the fourth power copper surface (14), and the fifth power copper surface (17).

4. The single-phase full-bridge intelligent power module based on gallium nitride power chip according to claim 1, characterized in that, The bottom copper layer of the printed circuit board and the top copper layer of the ceramic substrate are connected by solder, and the two copper layers have no electrical connection properties.

5. The single-phase full-bridge intelligent power module based on gallium nitride power chip according to claim 1, characterized in that, The printed circuit board (22) is also provided with drive terminals (24).

6. The single-phase full-bridge intelligent power module based on gallium nitride power chip according to claim 5, characterized in that, All drive terminals (24) are provided with solder pins (39).

7. The single-phase full-bridge intelligent power module based on gallium nitride power chip according to claim 1, characterized in that, Each driver chip is connected to an external circuit.

8. The single-phase full-bridge intelligent power module based on gallium nitride power chip according to claim 1, characterized in that, The housing includes a graphite clamp base (41), a graphite sheet clamp top cover (42), and a power module housing (40). The graphite clamp base (41) and the graphite sheet clamp top cover (42) are disposed at both ends of the power module housing (40) to form the housing.

9. A method for fabricating a single-phase full-bridge intelligent power module based on a gallium nitride power chip, characterized in that, The single-phase full-bridge intelligent power module based on gallium nitride power chips according to any one of claims 1 to 8 includes the following steps: Step 1: Apply solder to the ceramic substrate using a stencil; place the power copper plate, power chip, power terminals, and decoupling capacitor onto the ceramic substrate and solder them. Step 2: Use a stencil to apply solder paste to the designated locations on the printed circuit board, and place the driver chip and peripheral circuitry in the locations where the solder paste has been applied. Step 3: Place the driver printed circuit board on the power ceramic substrate, place the entire power module in the graphite fixture, and adjust the position of the nuts to fix the power chip, power terminals, driver terminals and decoupling capacitors. Step 4: The entire power module is placed in a vacuum reflow soldering machine for soldering; Step 5: Clean the power module with anhydrous ethanol to remove residual flux from the surface; Step 6: Use a bonding machine to connect the power chip to the copper surface on the ceramic substrate; use gold bonding wire or aluminum bonding wire to connect the power chip to the copper surface on the printed circuit board. Step 7: Use a robotic arm to embed the welding pins into the power base and drive base, cover the outside of the module with the module shell, pour the silicone gel into the module, let it stand until the silicone gel solidifies, and then perform electrical, thermal and reliability tests.

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