High-voltage silicon carbide power packaging module based on PCB integration and processing method thereof

Abstract

The invention relates to the technical field of power semiconductor packaging, in particular to a high-voltage silicon carbide power packaging module based on PCB integration and a processing method of the high-voltage silicon carbide power packaging module. According to the technical scheme, the silicon carbide chip radiator comprises a radiator substrate, a DBC substrate, a plurality of silicon carbide chips, a PCB and a packaging shell, the DBC substrate is welded to the radiator substrate, and the PCB is located above the DBC substrate; a drain busbar, a Kelvin source busbar and a grid busbar on the DBC substrate respectively pass through the PCB, and a Kelvin drain leading-out terminal, a Kelvin source leading-out terminal and a grid leading-out terminal are respectively and sequentially led out upwards from the drain busbar, the Kelvin source busbar and the grid busbar on the DBC substrate; and the packaging shell is coated above the radiator substrate. The beneficial effects of the invention are that the interference of the main loop on the driving loop can be effectively reduced; meanwhile, a driving terminal and a power terminal are effectively separated, interference is reduced, and the insulating performance and the working performance of the module are improved; only two formic acid furnace welding procedures are needed in the machining process, the rest is common welding, the machining process is simple, and the yield is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power semiconductor packaging, and particularly relates to a high-voltage silicon carbide power packaging module based on PCB integration and a processing method thereof. BACKGROUND

[0002] The power packaging module of the power semiconductor chip switch is to package MOSFET chips in the power module to control high-speed switching of large current. Due to the advantages in switching speed, voltage resistance and temperature resistance, SiC MOSFET devices are paid more and more attention and applied in electric vehicles and photovoltaic inverters. High-voltage power modules increase the current-carrying capacity by connecting multiple SiC MOSFETs in parallel to realize capacity improvement and provide a solution for new energy efficient grid connection. However, due to the different current paths of multiple chips, different parasitic parameters are introduced into the loop, which reduces the symmetry between chips and the quality of module voltage and current, and affects the stability of device operation. In addition, the high-voltage module should have a reasonable insulation distance to meet the insulation requirements. Therefore, it is of great significance to develop a high-voltage power module with small parasitic parameters and good insulation performance.

[0003] The traditional bonding wire packaging structure is composed of a heat dissipation substrate, a solder layer between the substrate and the DBC substrate, a DBC substrate, a solder layer between the DBC substrate and the chip, SiC MOSFETs, a bonding wire, a power terminal, a potting glue and a shell. The two solder layers serve as the connection layer between the heat dissipation substrate and the DBC and the connection layer between the DBC and the chip. The DBC substrate is composed of an upper copper layer, a middle ceramic layer and a lower copper layer. The upper copper layer is etched to form a circuit and is connected with the chip and the terminal to form a circuit structure. The middle ceramic layer is used to electrically isolate the heat dissipation substrate from the upper copper layer and to transfer the heat generated by the chip to the heat dissipation substrate. The lower copper layer is a whole copper foil connected with the heat dissipation substrate. The chip is the core component of the power module and uses a switch to switch different circuit states. The bonding wire serves as a circuit connection and connects different electrodes of the power chip with the upper copper layer of the DBC. The potting glue is used to wrap the internal circuit components to improve the electrical insulation capability of the module and protect the power chip, the substrate and the power terminal from external dust, moisture and the like. The shell serves as the mechanical support of the power module. The power packaging module of this structure is mainly used for medium and low voltage modules and is not suitable for 10kV high-voltage and large-current packaging modules. The existing high-voltage power packaging modules mainly have the following problems: 1. Insufficient material system adaptability; the difference in CTE (thermal expansion coefficient) between the chip, the solder and the substrate leads to stress accumulation in thermal cycling, causing solder layer fatigue, bonding wire falling off and even substrate fracture. Although commercial modules use sintered silver to relieve stress, the cost is high and the process is complex; the theoretical working temperature of SiC chip can reach more than 200℃, and the material is easy to age and delaminate at high temperature, resulting in a decrease in insulation performance.

[0004] 2. Parasitic parameters and high-frequency response suppression difficulties; SiC device switching frequency reaches MHz level, and traditional bonding wire structure causes high-frequency oscillation and voltage overshoot. Although the planar interconnection or three-dimensional stacked packaging can reduce the inductance to 1-5nH, the spatial layout flexibility needs to be sacrificed, and the design complexity is increased; in order to reduce the parasitic inductance, the module size needs to be reduced, but the compact layout will aggravate the local electric field concentration and reduce the insulation strength.

[0005] 3. Manufacturing efficiency and yield problems; the manufacturing process designed for a specific packaging structure includes welding, bonding and other processes, in order to ensure the manufacturing yield, the packaging method is often more complex. SUMMARY

[0006] In order to solve the above technical problems, the purpose of the present application is to provide a high-voltage silicon carbide power packaging module based on PCB integration and a processing method thereof, in particular to provide a high-voltage silicon carbide power packaging module based on PCB integration and a processing method thereof, which has reasonable structure, good insulation performance and relatively simple packaging process.

[0007] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows: a high-voltage silicon carbide power packaging module based on PCB integration, comprising a heat sink substrate, a DBC substrate, a plurality of silicon carbide chips, a PCB board and a packaging shell, the DBC substrate is welded on the heat sink substrate, a plurality of silicon carbide chips are welded on the DBC substrate, the PCB board is located above the DBC substrate, the drain bus bar, the kelvin source bus bar and the gate bus bar on the DBC substrate pass through the PCB board in sequence and are respectively led out kelvin drain terminal, kelvin source terminal and gate terminal; the source power terminal and the drain power terminal are respectively welded on the source bus bar and the drain bus bar on the DBC substrate; the packaging shell is wrapped above the heat sink substrate and wraps the DBC substrate, the silicon carbide chip and the PCB board therein, and the silicon gel is filled in the packaging shell.

[0008] Specifically, the source bus bar and the drain bus bar on the DBC substrate are both distributed in the middle part of the DBC substrate, and the gate bus bar and the kelvin source bus bar are arranged at the upper and lower edges of the DBC; the PCB board is arranged in a square frame along the edge of the DBC substrate.

[0009] Specifically, the source of the silicon carbide chip is connected with the source bus bar and the kelvin source bus bar on the DBC substrate through the source lead-out bonding wire respectively; the gate of the silicon carbide chip is connected with the gate bus bar on the DBC substrate through the gate lead-out bonding wire.

[0010] Specifically, the silicon carbide chip is welded and connected with the drain bus bar on the DBC substrate through the drain at the bottom.

[0011] Specifically, the drain bus bar, the Kelvin source bus bar and the gate bus bar on the DBC substrate are connected with the PCB board through the lower layer Kelvin drain terminal, the lower layer Kelvin source terminal and the lower layer gate terminal respectively.

[0012] Specifically, the top surface of the packaging shell is provided with an insulating slot between the source power terminal and the drain power terminal.

[0013] Specifically, the side surface of the packaging shell is provided with a plurality of annular slots.

[0014] A processing method of the above-mentioned high-voltage silicon carbide power packaging module based on PCB integration, comprising the following steps: S1, a solder resist layer is first made on the area of the DBC substrate surface provided with copper by an ultraviolet curing method.

[0015] S2, the silicon carbide chip is welded on the drain bus bar of the DBC substrate in the formic acid atmosphere of the formic acid furnace.

[0016] S3, the gate of the silicon carbide chip is connected with the gate bus bar on the DBC substrate through a lead by using an ultrasonic bonding process, and the source of the silicon carbide chip is connected with the Kelvin source bus bar and the source bus bar on the DBC substrate through a lead respectively.

[0017] S4, the DBC substrate is welded on the heat sink substrate in the formic acid atmosphere.

[0018] S5, the lower layer Kelvin drain terminal, the lower layer Kelvin source terminal and the lower layer gate terminal are welded to the PCB board.

[0019] S6, the heat sink substrate, the PCB board, the source power terminal and the drain power terminal are fixed by using a clamp, and the lower layer Kelvin drain terminal, the lower layer Kelvin source terminal and the lower layer gate terminal on the PCB board, and the source power terminal and the drain power terminal are welded on the DBC substrate respectively by a reflow soldering process.

[0020] S7, a packaging shell is made by injection molding or 3D printing, and the packaging shell is assembled and connected with the heat sink substrate.

[0021] S8, silicon gel is poured and sealed in the packaging shell, and the silicon gel completely covers all elements in the packaging shell.

[0022] The beneficial effects of this invention are as follows: All the gates of the silicon carbide chips are uniformly led to the edge gate terminal via the PCB board, and all the Kelvin drains and Kelvin sources are uniformly led to a single Kelvin drain terminal and Kelvin source terminal via the PCB board, thus forming a stacked drive circuit, reducing the equivalent area of ​​the drive circuit, and reducing interference from the main circuit (i.e., the circuit between the source power terminal and the drain power terminal); simultaneously, the source power terminal and drain power terminal are positioned in the middle of the module, while the PCB board and drive terminals (gate terminal, Kelvin drain terminal, and Kelvin source terminal) are positioned at the edge of the module, effectively separating the drive terminals and power terminals, reducing interference, and improving the module's insulation and operating performance; slots are provided between the power terminals on the package shell, and circumferential slots are provided on the sides to increase the creepage distance, effectively improving the module's insulation performance; the processing only requires two formic acid furnace welding processes, with the rest being ordinary welding, making the processing relatively simple and resulting in a high yield rate. Attached Figure Description

[0023] Appendix Fig. 1 This is a top view of the interior of the packaging module without the outer casing in the embodiment; Appendix Fig. 2 This is a perspective view of the interior of the packaging module without the outer casing in the embodiment. Appendix Fig. 3 This is a perspective view of the overall appearance of the packaging module in the embodiment.

[0024] 1-Heat sink substrate, 2-DBC substrate, 21-Drain busbar, 22-Kelvin source busbar, 23-Gate busbar, 24-Source busbar, 3-Silicon carbide chip, 31-Source lead bonding wire, 32-Gate lead bonding wire, 4-PCB board, 41-Lower Kelvin drain terminal, 42-Lower Kelvin source terminal, 43-Lower gate terminal, 5-Package housing, 51-Insulating slot, 52-Circular slot, 61-Kelvin drain lead terminal, 62-Kelvin source lead terminal, 63-Gate lead terminal, 71-Source power terminal, 72-Drain power terminal. Detailed Implementation

[0025] Example 1, referring to Figs. 1-3The application discloses a high-voltage silicon carbide power packaging module based on PCB integration, which comprises a radiator substrate 1, a DBC substrate 2, a plurality of silicon carbide chips 3, a PCB plate 4 and a packaging shell 5, the DBC substrate 2 is welded on the radiator substrate 1, the plurality of silicon carbide chips 3 are welded on the DBC substrate 2, the PCB plate 4 is located above the DBC substrate 2, a drain bus 21, a Kelvin source bus 22 and a gate bus 23 on the DBC substrate 2 pass through the PCB plate 4 and are sequentially led out to a Kelvin drain terminal 61, a Kelvin source terminal 62 and a gate terminal 63 upwards respectively, a source power terminal 71 and a drain power terminal 72 are respectively welded on a source bus 24 and the drain bus 21 on the DBC substrate 2, and the packaging shell 5 is wrapped above the radiator substrate 1 and wraps the DBC substrate 2, the silicon carbide chips 3 and the PCB plate 4 in it, and the packaging shell 5 is filled with silicon gel.

[0026] Specifically, the source bus 24 and the drain bus 21 on the DBC substrate 2 are both distributed in the middle part of the DBC substrate 2, and the gate bus 23 and the Kelvin source bus 22 are arranged on the upper and lower end edges of the DBC substrate 2; the PCB plate 4 is arranged in a square frame type along the edge of the DBC substrate 2.

[0027] Specifically, the source of the silicon carbide chip 3 is connected with the source bus 24 and the Kelvin source bus 22 on the DBC substrate 2 through a source lead-out bonding wire 31 respectively, the gate of the silicon carbide chip 3 is connected with the gate bus 23 on the DBC substrate 2 through a gate lead-out bonding wire 32, and the silicon carbide chip 3 is welded and connected with the drain bus 21 on the DBC substrate 2 through the bottom drain.

[0028] The high-voltage silicon carbide power packaging module is integrated by using a plurality of silicon carbide chips 3 in parallel to achieve a large enough current flow capacity (i.e. a large current, generally tens to hundreds of amperes), the power packaging module of the embodiment generally divides the silicon carbide chips 3 into two rows arranged on the DBC substrate 2, and the two rows of silicon carbide chips 3 are symmetrically arranged relative to the transverse middle axis, the source of the silicon carbide chip 3 faces the middle part of the DBC substrate 2, and the gate of the silicon carbide chip 3 is close to the upper edge / lower edge of the DBC substrate 2, so as to facilitate the connection of the source of the silicon carbide chip 3 with the source bus 24 in the middle part of the DBC substrate 2 and the connection of the gate of the silicon carbide chip 3 with the gate bus 23 on the edge of the DBC substrate 2, when the number of silicon carbide chips 3 in each row is large, a plurality of columns can be arranged according to requirements, and the embodiment is arranged in two columns. The source power terminal 71 and the drain power terminal 72 are arranged at the middle position of the module, and the PCB plate 4 and the driving terminals (the gate terminal 63, the Kelvin drain terminal 61 and the Kelvin source terminal 62) are arranged at the edge position of the module, so that the driving terminals and the power terminals are effectively separated, interference is reduced, and the insulation performance and working performance of the module are improved.

[0029] Specifically, the drain bus bar 21, the Kelvin source bus bar 22 and the gate bus bar 23 on the DBC substrate 2 are connected with the PCB board 4 through the lower layer Kelvin drain terminal 41, the lower layer Kelvin source terminal 42 and the lower layer gate terminal 43 respectively.

[0030] Specifically, the top surface of the packaging shell 5 is provided with an insulating slot 51 between the source power terminal 71 and the drain power terminal 72. The side surface of the packaging shell 5 is provided with a plurality of annular slots 52. The packaging shell 5 is provided with insulating slots between the power terminals and annular slots on the side surface, which can improve the creepage distance and effectively improve the insulation performance of the module.

[0031] The embodiment also provides a processing method of the high-voltage silicon carbide power packaging module based on PCB integration, which comprises the following steps: S1, a solder resist layer is formed on the region with copper on the surface of the DBC substrate by an ultraviolet curing method.

[0032] S2, the silicon carbide chip is welded on the drain bus bar of the DBC substrate in the formic acid atmosphere of the formic acid furnace.

[0033] S3, the gate of the silicon carbide chip is connected with the gate bus bar on the DBC substrate through a lead by using an ultrasonic bonding process, and the source of the silicon carbide chip is connected with the Kelvin source bus bar and the source bus bar on the DBC substrate through a lead respectively.

[0034] S4, the DBC substrate is welded on the heat sink substrate in the formic acid atmosphere.

[0035] S5, the lower layer Kelvin drain terminal, the lower layer Kelvin source terminal and the lower layer gate terminal are welded on the PCB board.

[0036] S6, the heat sink substrate, the PCB board, the source power terminal and the drain power terminal are fixed by using a clamp, and the lower layer Kelvin drain terminal, the lower layer Kelvin source terminal and the lower layer gate terminal on the PCB board, and the source power terminal and the drain power terminal are welded on the DBC substrate respectively by a reflow soldering process.

[0037] S7, a packaging shell is made by injection molding or 3D printing, and the packaging shell is assembled and connected with the heat sink substrate.

[0038] S8, silicon gel is filled in the packaging shell and sealed, and the silicon gel completely covers all the elements in the packaging shell.

[0039] Of course, the above is only the preferred embodiment of the present application, and does not limit the use range of the present application, so any equivalent changes made on the principle of the present application should be included in the protection scope of the present application.

Claims

1. A high-voltage silicon carbide power package module based on PCB integration, characterized in that: The device includes a heat sink substrate, a DBC substrate, several silicon carbide chips, a PCB board, and a package shell. The DBC substrate is soldered onto the heat sink substrate, and the several silicon carbide chips are soldered onto the DBC substrate. The PCB board is located above the DBC substrate. The drain bus, Kelvin source bus, and gate bus on the DBC substrate pass through the PCB board and are led upwards to Kelvin drain terminals, Kelvin source terminals, and gate terminals, respectively. Source power terminals and drain power terminals are soldered onto the source bus and drain bus on the DBC substrate, respectively. The package shell covers the heat sink substrate and encapsulates the DBC substrate, silicon carbide chips, and PCB board. The package shell is filled with encapsulating silicone gel.

2. The high-voltage silicon carbide power packaging module based on PCB integration according to claim 1, characterized in that: The source busbar and drain busbar on the DBC substrate are both distributed in the middle of the DBC substrate, and the gate busbar and Kelvin source busbar are disposed at the upper and lower edges of the DBC; the PCB board is arranged in a square shape along the edge of the DBC substrate.

3. The high-voltage silicon carbide power packaging module based on PCB integration according to claim 1, characterized in that: The source of the silicon carbide chip is connected to the source busbar and Kelvin source busbar on the DBC substrate via source lead-out bonding wires, respectively; the gate of the silicon carbide chip is connected to the gate busbar on the DBC substrate via gate lead-out bonding wires.

4. The high-voltage silicon carbide power packaging module based on PCB integration according to claim 1, characterized in that: The silicon carbide chip is soldered to the drain busbar on the DBC substrate via the drain at the bottom.

5. A high-voltage silicon carbide power packaging module based on PCB integration according to claim 1, characterized in that: The drain bus, Kelvin source bus, and gate bus on the DBC substrate are connected to the PCB board through the lower Kelvin drain terminal, the lower Kelvin source terminal, and the lower gate terminal, respectively.

6. The high-voltage silicon carbide power packaging module based on PCB integration according to claim 1, characterized in that: An insulating slot is provided on the top surface of the package housing between the source power terminal and the drain power terminal.

7. A high-voltage silicon carbide power packaging module based on PCB integration according to claim 1, characterized in that: The side of the encapsulation shell is provided with several circumferential slots.

8. A method for processing a high-voltage silicon carbide power packaging module based on PCB integration as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. First, a solder resist layer is made on the copper-clad area on the surface of the DBC substrate by ultraviolet light curing. S2. The silicon carbide chip is soldered onto the drain busbar of the DBC substrate in a formic acid atmosphere in a formic acid furnace; S3. Using ultrasonic bonding technology, the gate of the silicon carbide chip is connected to the gate busbar on the DBC substrate by wires, and the source of the silicon carbide chip is connected to the Kelvin source busbar and the source busbar on the DBC substrate by wires respectively. S4. Solder the DBC substrate onto the heat sink substrate in a formic acid atmosphere; S5. Solder the lower Kelvin drain terminal, the lower Kelvin source terminal and the lower gate terminal to the PCB board; S6. Fix the heat sink substrate, PCB board, source power terminal and drain power terminal using a fixture, and solder the lower Kelvin drain terminal, lower Kelvin source terminal and lower gate terminal, as well as the source power terminal and drain power terminal on the PCB board onto the DBC substrate through a reflow soldering process. S7. The packaging shell is manufactured by injection molding or 3D printing, and the packaging shell is assembled and connected to the heat sink substrate; S8. Infuse silicone gel into the package and seal it, so that the silicone gel completely covers all components inside the package.

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