CN106910691A - The radiator structure and packaging technology of IGBT module in power converter - Google Patents

Abstract

The present invention relates to the radiator structure and packaging technology of IGBT module in a kind of power converter, its structure includes substrate, chip, heat sink, Graphene heat dissipating layer, graphene-based interconnection material, busbar and silica gel；The single-layer graphene film prepared using chemical vapour deposition technique as chip surface heat dissipating layer, by playing its excellent face heat conduction performance, by the rapid lateral transport of hot localised points heat of IGBT module in power converter to heat sink；Few layer graphene powder prepared by oxidation-reduction method or solvent stripping method is filled into multi-modal Argent grain conducting resinl, strengthen its electrical and thermal conductivity performance, and as chip and substrate, the heat sink interconnection material and substrate between, improve longitudinal conducting power of the heat from chip to substrate；Interconnection mode using chip attachment shortens heat conduction path, strengthens integrally-built heat dispersion, realizes effective radiating of local high heat flux focus, so that the maximum temperature of IGBT module in power converter is reduced, boost device service life.

Description

Heat Dissipation Structure and Packaging Technology of IGBT Module in Power Converter

technical field

The invention belongs to the technical field of semiconductors, and in particular relates to a heat dissipation structure and packaging process of an IGBT module in a power converter.

Background technique

With the development of new power generation technologies such as wind power and solar photovoltaic power generation, distributed power generation systems have gradually become an effective way to meet the demand for load growth, reduce environmental pollution, and improve comprehensive energy utilization efficiency and power supply reliability. The demand for power converter capacity for energy conversion and storage between the generator and the grid is increasing, which requires the power device IGBT module to have a higher power level, and the failure rate of the large-capacity IGBT module cannot be ignored.

The faults of medium and high voltage power converters due to the failure of IGBT modules account for more than 90%. When the IGBT modules are turned on or off repeatedly, failure or fatigue effects will occur under repeated thermal shocks, and their working life and reliability will be reduced. affect the normal operation of the entire device or system. The semiconductor silicon chip in the IGBT module is responsible for commutation and the packaging structure provides auxiliary functions such as electrical connection, heat dissipation, insulation and mechanical strength. The failure of IGBT is mainly caused by the inability of the bonding wires, bonding points and solder layer to withstand thermal stress and deformation. Therefore, improving the heat dissipation technology and packaging structure of the IGBT module is one of the countermeasures to solve its failure.

In recent years, two-dimensional materials represented by graphene have shown great promise in the fields of electronics and photonics due to their unique physical properties, such as ultra-high electron mobility, high thermal conductivity, high Young's modulus, and high specific surface area. Wide application prospects. Among them, high thermal conductivity has become a prominent advantage in electronic thermal management applications. It is hoped that it can be directly used as a packaging material to dissipate heat from IGBT modules, which can improve the ability of the module to withstand thermal cycles, thereby improving the long-term reliability of device applications.

Contents of the invention

In order to solve the problems of the prior art, the purpose of the present invention is to overcome the deficiencies of the prior art, provide a heat dissipation structure and packaging process of the IGBT module in the power converter, and apply the graphene material in the form of a heat dissipation film The high surface of the IGBT chip is applied between the chip and the substrate, the heat sink and the substrate in the form of filling enhanced conductive and thermal conductive glue, and the interconnection method of the chip is mounted to solve the heat dissipation problem of the IGBT module in the power converter.

In order to achieve the above object, the present invention adopts the following technical solutions. The heat dissipation structure of the IGBT module in the power converter includes: a first IGBT chip, the upper surface of which is the first IGBT chip collector connection area, and the lower surface is provided with the first IGBT chip emitter connection area and the first IGBT chip Gate connection area; the first graphene thin film heat dissipation layer is in contact with the emitter connection area of the first IGBT chip.

The heat dissipation structure of the IGBT module in the power converter may also include: a second IGBT chip, the upper surface of which includes the second IGBT chip emitter connection area and the second IGBT chip gate connection area, and the lower surface of which is the second IGBT chip collector connection area; the second graphene film heat dissipation layer is in contact with the second IGBT chip collector connection area.

The heat dissipation structure of the IGBT module in the power converter may also include:

a substrate, the upper surface of which includes the gate terminal of the first IGBT chip, the common terminal of the emitter of the first IGBT chip and the collector of the second IGBT chip;

A metal or graphite heat sink connected laterally with the first graphene film heat dissipation layer and the second graphene film heat dissipation layer, the heat sink is fixed in the middle of the first IGBT chip and the second IGBT chip, and the longitudinal thickness of the heat sink is both less than the thickness of the emitter connection area of the first IGBT chip, and less than the thickness of the collector connection area of the second IGBT chip;

Graphene-filled and enhanced conductive and heat-conducting glue in contact with the first graphene thin film heat dissipation layer, the second graphene thin film heat dissipation layer, the heat sink, the lower surface of the first IGBT chip gate connection region, and the upper surface of the substrate;

A bracket is connected above the substrate, and the busbar is fixedly supported by the bracket. The busbar is provided with: a first busbar terminal connected to the collector lead-out end of the first IGBT chip; The second busbar terminal connected to the gate terminal of the IGBT chip; the third busbar terminal connected to the common terminal of the emitter of the first IGBT chip and the collector of the second IGBT chip; connected to the second IGBT chip The fourth busbar terminal connected to the emitter terminal of the second IGBT chip; the fifth busbar terminal connected to the gate terminal of the second IGBT chip;

Silica gel is filled between the structure formed by the busbar and the bracket and the substrate.

A packaging process for an IGBT module heat dissipation structure in a power converter, comprising the following steps:

(1) grow single-layer graphene on copper foil surface, form graphene/copper foil structure layer, on graphene/copper foil structure layer, spin-coat one deck polymethyl methacrylate PMMA as film supporting layer, obtain PMMA/copper foil structure layer Graphene/copper foil structural layer system;

(2) Using sodium hydroxide solution as the electrolyte, connect the negative pole of the DC power supply to the copper foil of the PMMA/graphene/copper foil structural layer system, and connect the positive pole of the DC power supply to the platinum electrode at the same time, and gradually increase the current. After the copper foil is separated from PMMA and graphene, a PMMA/graphene structure layer is obtained;

(3) The PMMA/graphene structure layer is transferred to the first IGBT chip emitter and the second IGBT chip collector respectively, so that the single-layer graphene is directly combined with the chip, and the PMMA is removed with acetone after natural air drying, that is, the surface of the chip is obtained Single-layer graphene film;

(4) A substrate is provided, the upper surface of which is made with electrode lead-out lines according to the mounting method of the first IGBT chip and the second IGBT chip, including the gate lead-out end of the first IGBT chip, the emitter of the first IGBT chip and the second The common terminal of the collector of the IGBT chip, the terminal of the collector of the first IGBT chip, the terminal of the emitter of the second IGBT chip, and the terminal of the grid of the second IGBT chip; the method of screen printing on the surface of the substrate Apply graphene-enhanced conductive and heat-conducting glue, and glue the heat sink to the surface of the substrate through graphene-enhanced conductive and heat-conducting glue;

(5) The first IGBT chip and the second IGBT chip are mounted by mounting, that is, the emitter of the first IGBT chip and the collector of the second IGBT chip face down, so that the single-layer graphene film can enhance electrical conductivity and heat conduction through graphene Glue forms good contact with the substrate; at the same time, the first IGBT chip and the second IGBT chip are respectively placed on both sides of the heat sink, and the single-layer graphene film, the emitter of the first IGBT chip and the collector of the second IGBT chip are all in contact with the heat sink. The heat sink forms a physical contact, so that the heat of the local hot spot of the chip is transferred to the heat sink through the single-layer graphene, and then transferred to the substrate;

(6) Gradual heating makes the graphene-enhanced conductive and heat-conducting adhesive fully cured, and interconnects are formed between the emitter of the first IGBT chip and the gate of the first IGBT chip, the collector of the second IGBT chip and the substrate, and the heat sink and the substrate ; Connect the first IGBT chip collector, the second IGBT chip gate, and the second IGBT chip emitter to corresponding leads on the substrate through metal wires by wire bonding; install busbars and brackets above the substrate, Silica gel is filled between the busbar and bracket structure and the substrate, and cured at room temperature.

Specifically, the above step (6) uses wire bonding to connect the first IGBT chip collector to the collector terminal of the first IGBT chip on the substrate through the first metal wire, and connect the second IGBT chip through the second metal wire. The chip gate is connected to the gate terminal of the second IGBT chip on the substrate, and the emitter of the second IGBT chip is connected to the emitter terminal of the second IGBT chip on the substrate through a third metal wire.

Specifically, there are a plurality of busbar terminals on the busbar in step (6), wherein the collector terminal of the first IGBT chip is connected to the first busbar terminal, and the gate terminal of the first IGBT chip is connected to the second busbar terminal. The terminals of the first IGBT chip and the collector of the second IGBT chip are connected to the third busbar terminal, the emitter terminal of the second IGBT chip is connected to the fourth busbar terminal, and the second IGBT chip The grid lead-out end of the grid is connected to the fifth busbar terminal.

Compared with the prior art, the present invention has the following advantages:

1. The present invention uses a single-layer graphene film as the heat dissipation layer on the surface of the chip, which can exert its excellent in-plane thermal conductivity, quickly transfer heat to the heat sink, and then dissipate it through the substrate. For the local IGBT module in the power converter High heat flow hot spots are very effective thermal management solutions;

2. The present invention uses a few-layer graphene powder to fill the enhanced conductive and thermally conductive adhesive as the interconnection material between the chip and the substrate, the heat sink and the substrate, which can improve the longitudinal conduction performance of heat from the chip to the substrate, and at the same time, the interconnection of the chip mounting The method can enhance the reliability of the overall structure and meet the heat dissipation requirements in high-power IGBT modules with high heat flux density.

Description of drawings

FIG. 1 is a schematic diagram of the structure of a graphene film applied to the surface of a first IGBT chip according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of the structure of a graphene film applied to the surface of a second IGBT chip according to an embodiment of the present invention.

Fig. 3 is a schematic diagram of the heat dissipation structure of the IGBT module in the power converter proposed by the present invention.

Fig. 4 is a schematic diagram of the PMMA/graphene/Cu structural layer system in the process implementation step 1.1 of the present invention.

Fig. 5 is a schematic diagram of the PMMA/graphene structure layer in the process implementation step 1.2 of the present invention.

Fig. 6 is a schematic diagram of the substrate in step 2.1 of the process of the present invention.

Fig. 7 is a schematic diagram of mounting a heat sink in Step 2.2 of the process of the present invention.

Fig. 8 is a schematic diagram of chip mounting in step 2.2 of the process implementation of the present invention.

detailed description

The present invention will be further described below in conjunction with drawings and embodiments.

The invention proposes a heat dissipation structure of an IGBT module in a power converter, including a substrate, a chip, a heat sink, a graphene heat dissipation layer, a graphene-based interconnection material, a busbar and silica gel.

The single-layer graphene film prepared by chemical vapor deposition is used as a heat dissipation layer for the surface of the emitter 12 of the first IGBT chip and the surface of the collector 22 of the second IGBT chip, see FIGS. 1 and 2 . In FIG. 1 , the first IGBT chip 11 has an emitter 12 and a gate 13 on the upper surface of the first IGBT chip, and the upper surface of the emitter 12 of the first IGBT chip is a first single-layer graphene film 10 . In FIG. 2 , there is a collector electrode 22 of the second IGBT chip on the upper surface of the second IGBT chip 21 , and the second single-layer graphene film 20 is on the upper surface thereof.

The present invention adopts the few-layer graphene powder prepared by the redox method or the solvent stripping method, fills the multi-modal silver particle conductive adhesive to enhance the electrical and thermal conductivity, and then serves as the interconnection between the chip and the substrate, the heat sink and the substrate, Refer to Figure 3 for the overall heat dissipation structure. The upper surface of the substrate 31 is made with electrode lead-out lines according to the mounting method of the first IGBT chip 11 and the second IGBT chip 21, including the gate lead-out end 32 of the first IGBT chip 11, the first IGBT chip emitter 12 and the second IGBT chip. The common terminal 33 of the collector 22 of the two IGBT chips, the collector terminal 35 of the first IGBT chip 11 , the emitter terminal 41 of the second IGBT chip 21 , and the gate terminal 38 of the second IGBT chip 21 . The heat sink 42 is made of metal or graphite, and between the heat sink 42 and the substrate 31 , between the first IGBT chip 11 and the second IGBT chip 21 and the substrate 31 , graphene-enhanced conductive and heat-conducting glue 43 is used as an interconnection material. The first IGBT chip 11 is mounted on the substrate 31 in a mounting manner, that is, the collector 14 of the first IGBT chip 11 is on the top, and the emitter 12 and the gate 13 of the first IGBT chip 11 are on the bottom, wherein the first IGBT chip The emitter 12 of 11 is pasted with a first single-layer graphene film 10 . The second IGBT chip 21 is also installed on the substrate 31 in a mounting manner, that is, the gate 36 and the emitter 39 of the second IGBT chip 21 are on the top, and the collector 22 is on the bottom, wherein the collector 22 of the second IGBT chip 21 A second single-layer graphene film 20 is pasted on it. The first IGBT chip collector 14 is connected to the first IGBT chip collector terminal 35 on the substrate 31 by the first metal wire 34, and the second IGBT chip gate 36 is connected to the second IGBT chip gate terminal 38 on the substrate 31. The second IGBT chip emitter 39 is connected to the second IGBT chip emitter terminal 41 on the substrate 31 by the third metal wire 40 . A busbar 44 and a bracket 45 are also made on the substrate 31. The busbar 44 is fixedly supported by the bracket 45 connected to the top of the substrate. The busbar 44 is provided with a plurality of busbar terminals, and the upper end of the busbar terminal is arranged on the busbar 44. and the upper surface of the bracket 45 structure, wherein the collector terminal 35 of the first IGBT chip 11 is connected to the first busbar terminal 46, and the gate terminal 32 of the first IGBT chip 11 is connected to the second busbar terminal 47. The emitter 12 of one IGBT chip and the leading end 33 of the collector 22 of the second IGBT chip 21 are connected to the third busbar terminal 48, and the emitter leading end 41 of the second IGBT chip 21 is connected to the fourth busbar terminal 49, The gate terminal 38 of the second IGBT chip 21 is connected to the fifth busbar terminal 50 . Silicone gel 51 is filled between the structure formed by the busbar 44 and the bracket 45 and the substrate 31 .

The invention proposes a packaging process for the heat dissipation structure of the IGBT module in the power converter, including the transfer process of a single-layer graphene film prepared by chemical vapor deposition as the heat dissipation layer of the IGBT chip, and the use of a redox method or a solvent stripping method The prepared few-layer graphene powder is filled into the multi-modal silver particle conductive adhesive to enhance the electrical and thermal conductivity, and is used in two parts of the interconnection process between the chip and the substrate, and the heat sink and the substrate.

Among them, the specific steps of the transfer process of the heat dissipation layer in the heat dissipation structure of the IGBT module are as follows:

Step 1.1, as shown in Figure 4, grow single-layer graphene 61 by chemical vapor deposition on the surface of copper foil 60 to form a graphene/copper foil structure layer, and then spin-coat a layer of poly on the graphene/copper foil structure layer. Methyl methacrylate (PMMA) 62 was used as a film support layer to obtain a PMMA/graphene/Cu structural layer system.

Step 1.2, using NaOH solution with a molar concentration of 0.25-1M as the electrolyte, connecting the negative electrode of the DC power supply to the copper foil 60 of the PMMA/graphene/Cu structure layer system, and connecting the positive electrode of the DC power supply to the platinum electrode at the same time, The current is gradually increased (for example, gradually increased from zero to about 1A), and the copper foil 60 will be separated from the PMMA/graphene after 20-30 seconds to obtain a PMMA/graphene structure layer, as shown in FIG. 5 .

Step 1.3, transfer the PMMA/graphene structure layer to the emitter electrode 12 of the first IGBT chip, so that the single-layer graphene is directly combined with the chip, and after natural air drying, remove the PMMA with acetone, that is, the first single-layer graphene film is obtained on the surface of the chip 10, as shown in Figure 1. Repeat steps 1.1 and 1.2 to transfer the PMMA/graphene structure layer to the second IGBT chip collector 22, so that the single-layer graphene is directly combined with the chip, and the PMMA is removed with acetone after natural air drying, that is, the chip surface obtains the second single layer. Layer graphene film 20, as shown in Figure 2.

The specific steps of the interconnection process in the IGBT module heat dissipation structure of the present invention are:

Step 2.1. According to the mounting method of the first IGBT chip 11 and the second IGBT chip 21 proposed in the present invention, design and manufacture a substrate 31 with electrode lead-out lines, as shown in FIG. 6 . The upper surface of the substrate 31 is made with electrode lead-out lines according to the mounting method of the first IGBT chip 11 and the second IGBT chip 21, including the gate lead-out end 32 of the first IGBT chip 11, the first IGBT chip emitter 12 and the second IGBT chip. The common terminal 33 of the collector 22 of the two IGBT chips, the collector terminal 35 of the first IGBT chip 11 , the emitter terminal 41 of the second IGBT chip 21 , and the gate terminal 38 of the second IGBT chip 21 .

Step 2.2: Apply graphene-enhanced conductive and heat-conducting glue 43 on the surface of the substrate 31 by screen printing, and the heat sink 42 is adhered to the surface of the substrate 31 through the graphene-enhanced conductive and heat-conducting glue 43, as shown in FIG. 7 . The first IGBT chip 11 and the second IGBT chip 21 are mounted by mounting, that is, the first IGBT chip emitter 12 and the second IGBT chip collector 22 face down, so that the first single-layer graphene film 10 and the second single-layer graphene film The layered graphene film 20 is in good contact with the substrate 31 through the graphene-enhanced conductive and thermally conductive glue 43, as shown in FIG. 8 . Simultaneously, the first IGBT chip 11 and the second IGBT chip 21 are respectively placed on both sides of the heat sink 42, and make the first single-layer graphene film 10 and the second single-layer graphene film 20, the first IGBT chip emitter 12 and The second IGBT chip collector 22 is in physical contact with the heat sink 42, so that the heat of the first IGBT chip emitter 12 and the second IGBT chip collector 22 can pass through the first single-layer graphene film 10 and the second single-layer graphene film. The in-plane high thermal conductivity of the graphene film 20 is quickly transferred to the heat sink 42 and then to the substrate 31 .

Step 2.3, stepwise heating, for example, heating at 110°C for 30 minutes, then raising the temperature to 140°C, and keeping it warm for 1.5 hours, so that the graphene conductive and thermally conductive adhesive 43 is completely cured, and the first IGBT chip emitter 12 and grid 13, the second A reliable interconnection is formed between the IGBT chip collector 22 and the heat sink 42 and the substrate 31 . Connect the collector electrode 14 of the first IGBT chip to the collector terminal 35 of the first IGBT chip on the substrate 31 through the first metal wire 34 by wire bonding, and connect the gate of the second IGBT chip through the second metal wire 37. 36 is connected to the gate terminal 38 of the second IGBT chip on the substrate 31 , and the emitter 39 of the second IGBT chip is connected to the emitter terminal 41 of the second IGBT chip on the substrate 31 through the third metal wire 40 . Install the busbar 44 and the bracket 45, wherein the collector terminal 35 of the first IGBT chip 11 is connected to the first busbar terminal 46, and the gate terminal 32 of the first IGBT chip 11 is connected to the second busbar terminal 47. The emitter 12 of one IGBT chip and the leading end 33 of the collector 22 of the second IGBT chip 21 are connected to the third busbar terminal 48, and the emitter leading end 41 of the second IGBT chip 21 is connected to the fourth busbar terminal 49, The gate terminal 38 of the second IGBT chip 21 is connected to the fifth busbar terminal 50 , as shown in FIG. 3 . Silica gel 45 is filled between the busbar 44 , the bracket 45 and the substrate 31 and cured at room temperature.

The invention adopts the single-layer graphene film prepared by chemical vapor deposition method as the heat dissipation layer on the surface of the chip, and by exerting its excellent in-plane heat conduction performance, the local hot spot heat of the IGBT module in the power converter is quickly and laterally transferred to the heat sink; Fill the few-layer graphene powder prepared by the redox method or solvent exfoliation method into the multi-modal silver particle conductive adhesive to enhance its electrical and thermal conductivity, and use it as the interconnection material between the chip and the substrate, the heat sink and the substrate , improve the longitudinal conduction capacity of heat from the chip to the substrate; adopt the interconnection method of chip mounting to shorten the heat conduction path, enhance the heat dissipation performance of the overall structure, and realize the effective heat dissipation of local high heat flux hot spots, thereby reducing the IGBT module in the power converter The maximum temperature increases the service life of the device.

The above descriptions are only preferred embodiments of the invention, and are not intended to limit the invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the invention shall be included in this invention. within the protection scope of inventions and creations.

Claims (6)

1. The heat dissipation structure of the IGBT module in the power converter is characterized in that it comprises: a first IGBT chip (11), its upper surface is the first IGBT chip collector (14) connection area, and its lower surface is provided with a first The IGBT chip emitter (12) connection area and the first IGBT chip gate (13) connection area; the first graphene film heat dissipation layer (10) is in contact with the first IGBT chip emitter (12) connection area. 2. The heat dissipation structure of the IGBT module in the power converter according to claim 1, further comprising: a second IGBT chip (21), the upper surface of which includes a second IGBT chip emitter (39) connection area and the second IGBT chip gate (36) connection area, its lower surface is the second IGBT chip collector (22) connection area; the second graphene thin film heat dissipation layer (20) is connected with the second IGBT chip collector (22) ) connection area contacts. 3. The heat dissipation structure of the IGBT module in the power converter according to claim 2, further comprising: A substrate (31), the upper surface of which includes a gate terminal (32) of the first IGBT chip, a common terminal (33) of the emitter (12) of the first IGBT chip and the collector (22) of the second IGBT chip; A metal or graphite heat sink (42) laterally connected to the first graphene thin film heat dissipation layer (10) and the second graphene thin film heat dissipation layer (20), the heat sink (42) is fixed on the first IGBT chip (11) Between the second IGBT chip (21), the longitudinal thickness of the heat sink (42) is both smaller than the thickness of the first IGBT chip emitter (12) connection area, and smaller than the second IGBT chip collector (22) connection area. thickness; The lower surface of the connection area with the first graphene thin film heat dissipation layer (10), the second graphene thin film heat dissipation layer (20), the heat sink (42), the first IGBT chip gate (13) and the substrate (31) The upper surface is contacted with graphene-filled and enhanced conductive and thermally conductive adhesive (43); A bracket (45) is connected above the substrate (31), and the busbar (44) is fixedly supported by the bracket (45). The busbar (44) is provided with: the collector electrode of the first IGBT chip The first bus bar terminal (46) connected to the lead end (35); the second bus bar terminal (47) connected to the gate lead end (32) of the first IGBT chip; The third busbar terminal (48) connected to the common terminal (33) of the second IGBT chip collector; the fourth busbar terminal (49) connected to the emitter terminal (41) of the second IGBT chip ); a fifth busbar terminal (50) connected to the gate terminal (38) of the second IGBT chip; Silica gel (51) is filled between the structure formed by the busbar (44) and the bracket (45) and the substrate (31). 4. The packaging process of the heat dissipation structure of the IGBT module in the power converter is characterized in that it comprises the following steps: (1) grow single-layer graphene (61) on copper foil (60) surface, form graphene/copper foil structure layer, on graphene/copper foil structure layer, spin-coat one deck polymethyl methacrylate PMMA (62 ) as a film support layer to obtain a PMMA/graphene/copper foil structural layer system; (2) Use sodium hydroxide solution as the electrolyte, connect the negative pole of the DC power supply to the copper foil (60) of the PMMA/graphene/copper foil structural layer system, and connect the positive pole of the DC power supply to the platinum electrode at the same time, and gradually turn the current Increase, until the copper foil (60) is separated from PMMA and graphene to obtain a PMMA/graphene structure layer; (3) The PMMA/graphene structure layer is transferred to the first IGBT chip emitter (12) and the second IGBT chip collector (22) respectively, so that the single-layer graphene is directly combined with the chip, and removed with acetone after natural air drying PMMA, that is, a single-layer graphene film is obtained on the surface of the chip; (4) A substrate (31) is provided, the upper surface of which is made with electrode lead-out lines according to the mounting method of the first IGBT chip (11) and the second IGBT chip (21), including the gate of the first IGBT chip (11) lead end (32), the common lead end (33) of the first IGBT chip emitter (12) and the second IGBT chip collector (22), the collector lead end (35) of the first IGBT chip (11), the first The emitter terminal (41) of the second IGBT chip (21), the gate terminal (38) of the second IGBT chip (21); on the surface of the substrate (31), apply graphene reinforcement by screen printing Electrically conductive thermally conductive glue (43), the heat sink (42) is bonded to the surface of the substrate (31) through the graphene-enhanced conductively thermally conductive glue (43); (5) The first IGBT chip (11) and the second IGBT chip (21) are mounted by mounting, that is, the emitter (12) of the first IGBT chip and the collector (22) of the second IGBT chip face downward, Make the single-layer graphene film form good contact with the substrate (31) through the graphene-enhanced conductive heat-conducting adhesive (43); meanwhile, the first IGBT chip (11) and the second IGBT chip (21) are respectively placed on the heat sink (42) both sides, and make the single-layer graphene film, the emitter (12) of the first IGBT chip and the collector (22) of the second IGBT chip all form physical contact with the heat sink (42), so that the heat of the local hot spot of the chip passes through the single Layer graphene is delivered to heat sink (42), and then delivered to substrate (31); (6) Gradual heating makes the graphene-enhanced conductive and heat-conducting adhesive (43) solidify completely, and the emitter (12) of the first IGBT chip and the gate (13) of the first IGBT chip, the second IGBT chip collector (22) and The substrate (31), and the interconnection between the heat sink (42) and the substrate (31); the first IGBT chip collector (14), the second IGBT chip gate ( 36), the second IGBT chip emitter (39) is connected to the corresponding lead-out terminal on the substrate (31); install the busbar (44) and the bracket (45) above the substrate (31), and connect the busbar (44) and the bracket Silica gel (51) is filled between the structure formed by (45) and the substrate (31), and cured at room temperature. 5. the encapsulation process of IGBT module cooling structure in the power converter as claimed in claim 4, it is characterized in that, step (6) connects the first IGBT chip collector by the first metal wire (34) with the method of wire bonding (14) Connect with the collector terminal (35) of the first IGBT chip on the substrate (31), and connect the second IGBT chip gate (36) to the first IGBT chip gate on the substrate (31) through the second metal wire (37). The gate terminal (38) of the two IGBT chips is connected, and the second IGBT chip emitter (39) is connected to the emitter terminal (41) of the second IGBT chip on the substrate (31) by a third metal wire (40). connected. 6. the encapsulation process of IGBT module cooling structure in the power converter as claimed in claim 4, is characterized in that, there are a plurality of busbar terminals on the described busbar (44) of step (6), wherein the first IGBT chip The collector terminal (35) is connected to the first busbar terminal (46), the gate terminal (32) of the first IGBT chip is connected to the second busbar terminal (47), and the first IGBT chip emitter (12) The common terminal (33) of the second IGBT chip collector (22) is connected to the third busbar terminal (48), and the emitter terminal (41) of the second IGBT chip is connected to the fourth busbar terminal (49) , the gate terminal (38) of the second IGBT chip is connected to the fifth busbar terminal (50).