Seal shield oil immersion heat dissipation type beta-gallium oxide based igbt power package structure and method and use

Abstract

The application discloses a sealed protective cover oil immersion heat dissipation type beta-gallium oxide based IGBT power packaging structure and method and use. The structure comprises a beta-Ga2O3 vertical IGBT chip, a substrate, a sealed protective cover and insulating heat exchange oil. The protective cover forms a sealed oil storage cavity, and the chip is immersed in oil as a whole, and global heating is realized by oil buoyancy natural convection. The beta-Ga2O3 band gap is 4.5-4.9 eV, and the breakdown electric field is 8 MV / cm, which can greatly reduce the on-state loss of the device, inhibit high-temperature leakage, and reduce Joule heat from the source. The sealed oil immersion heat exchange makes up for the low thermal conductivity defect, the longitudinal temperature difference of the chip is less than or equal to 3.4 DEG C, and the PCB temperature difference is less than or equal to 0.1 DEG C, and the thermal mechanical stress is weakened. The application is matched with a carrier transport electro-thermal coupling heat source modeling and multi-physical field simulation optimization method, four sets of control experiments are set to quantize the heat dissipation gain, and can be used for high-voltage power transmission, new energy high-power fast charging and other equipment, and solves the problems of high heat generation, poor air cooling heat dissipation, heat point accumulation and low reliability of traditional silicon-based IGBT.

Description

Technical Field

[0001] This invention relates to the field of heat dissipation in power semiconductor IGBTs, and more particularly to a sealed protective cover oil-immersed heat dissipation type β-gallium oxide-based IGBT power packaging structure, method, and application. Background Technology

[0002] In recent years, power semiconductor IGBT technology has developed rapidly and has been widely used in core scenarios such as high-voltage power transmission, new energy power conversion, and high-power fast charging. Currently, most commercial mainstream devices are made of traditional silicon-based materials and are combined with conventional packaging and heat dissipation solutions such as substrate heat conduction and air cooling convection. The process is mature and can meet the basic operating requirements of small and medium power equipment. It is currently a common technical solution in the field of power electronics.

[0003] However, as power equipment upgrades towards high voltage, high frequency, and high power, the drawbacks of traditional silicon-based IGBTs and their associated heat dissipation and packaging solutions are becoming increasingly prominent. Traditional silicon-based semiconductor materials have high conduction and switching losses, and generate a large amount of Joule heat continuously during device operation, resulting in a large overall heat generation base and extremely high heat dissipation pressure from the source. At the same time, existing IGBTs generally adopt an open air-cooled heat dissipation structure without a sealed protective cavity or oil-immersed heat dissipation system. This results in a single heat exchange path and low heat dissipation efficiency, making them prone to heat accumulation and excessively high local hot spots under high-power transient conditions. Currently, the industry mainly improves heat dissipation performance by optimizing chip layout, upgrading to high thermal conductivity substrates, adding heat sink fins, and enhancing air cooling efficiency, but significant shortcomings still exist in practical applications.

[0004] Traditional improvement methods can only passively enhance heat dissipation capacity, failing to address the core issues of high loss and high heat generation in silicon-based materials, and the heat source of devices cannot be optimized. Simultaneously, open, shieldless structures cannot create a sealed heat dissipation space, preventing immersive, full-area heat dissipation. Insufficient heat exchange and uneven temperature distribution on the chip surface result in a severe bottleneck in heat dissipation improvement. Individual structural and material optimizations are disconnected from each other, failing to achieve synergistic heat dissipation effects. This leads to a surge in device losses, decreased stability, and shortened lifespan under high-temperature operating conditions, making it difficult to meet the engineering application requirements of high reliability, low temperature rise, and long-term stable operation of next-generation high-power power equipment.

[0005] This invention aims to achieve low-loss heat generation, highly uniform heat dissipation, and highly reliable protection operation of IGBT devices under high-power, high-frequency power electronic conditions. Based on high-voltage substation and high-power power supply applications in new energy sources, it deeply integrates gallium oxide wide-bandgap material, a sealed protective shield structure, and full-area oil immersion heat dissipation technology into an integrated packaging system, building upon the traditional silicon-based air-cooled IGBT packaging structure. Traditional IGBT packaging systems suffer from drawbacks such as high inherent losses in silicon-based materials, large heat generation at the source, insufficient conventional air-cooling heat exchange capacity, inability to achieve oil immersion heat dissipation due to the lack of a sealed cavity, severe localized heat accumulation on the chip, and weak protection performance. These defects easily lead to excessively high device temperature rise, poor stability, and short service life. Summary of the Invention

[0006] Purpose of the invention: To provide a more effective sealed protective cover oil-immersed heat dissipation type β-gallium oxide-based IGBT power packaging structure, method and application, the specific purpose of which is described in the specific implementation section for several substantial technical effects.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A sealed protective cover oil-immersed heat dissipation type β-gallium oxide-based IGBT power packaging structure is characterized by comprising a β-gallium oxide-based vertical IGBT chip, a substrate, a sealed protective cover, and insulating heat exchange oil; the sealed protective cover encloses a sealed oil storage cavity, and the β-Ga2O3-based IGBT chip is entirely immersed in the insulating heat exchange oil within the sealed oil storage cavity; the β-Ga2O3-based IGBT chip is an ultra-wide bandgap gallium oxide semiconductor chip, and a volumetric heat source is constructed inside the chip based on a carrier transport model; the insulating oil inside the sealed oil storage cavity forms a natural convection heat transfer field by relying on buoyancy, achieving full-area immersion heat dissipation of the chip.

[0008] A further technical solution of the present invention is as follows: the β-gallium oxide-based IGBT chip has a bandgap of 4.5-4.9 eV, a theoretical breakdown electric field of 8 MV / cm, and a thermal conductivity of 10-27 W / (m·K); the β-Ga2O3 single crystal has a monoclinic layered lattice structure, containing two types of coordinated gallium-oxygen bonding structures, tetrahedral GaO4 and octahedral GaO6, forming a stable crystal framework. This layered structure determines the intrinsic high critical breakdown field strength of the material and directly affects the anisotropy of phonon transport efficiency and thermal conductivity; when the power device is working, heat is conducted through lattice vibration, and the interatomic bonding morphology directly affects the phonon transport efficiency and overall thermal conductivity.

[0009] A further technical solution of the present invention is that: β-gallium oxide maintains extremely low leakage current due to its ultra-wide bandgap of 4.9eV; its high breakdown electric field allows for thinning of the drift region to reduce on-resistance; β-gallium oxide substrate IGBTs maintain good transfer characteristics at 350 K, 400 K and 500 K, and the drain current can quickly enter the stable platform after conduction, indicating that the device has good gate control capability and temperature stability; the ultra-wide bandgap of β-gallium oxide can effectively suppress high-temperature leakage current and maintain excellent high-temperature operating stability, making it suitable for high-voltage, high-temperature and high-power power electronic devices.

[0010] A further technical solution of the present invention is as follows: the sealed protective cover constitutes a completely sealed oil storage cavity without external exposure. After being heated, the insulating oil inside the cavity forms a natural convection flow field that rises upward along the outer surface of the IGBT chip, pins, and encapsulation. The insulating oil and the outer wall of the chip encapsulation form a forced convection heat transfer interface, and the convection heat transfer coefficient h is controlled by the natural buoyancy force of the oil field. It also includes a PCB substrate, copper pins, a SAC305 solder layer, and an epoxy resin encapsulation. The β-Ga2O3-based IGBT chip is bonded to the inside of the epoxy resin encapsulation through the SAC305 solder layer. The encapsulation and copper pins extend integrally to the PCB substrate, and the entire assembly is placed in the insulating oil of the sealed protective cover.

[0011] A further technical solution of the present invention is that: under the uniform heating effect of the insulating oil in the sealed oil storage cavity, the temperature difference of the chip along the length direction is ≤3.4℃, and the temperature difference of the PCB surface is ≤0.1℃, which greatly reduces the thermomechanical stress caused by the thermal expansion deformation inside the device and inhibits the peeling of the solder layer and the cracking failure of the chip.

[0012] A method for modeling heat sources in electrothermal coupling simulation of IGBT devices based on carrier transport theory, characterized by the following steps: S1. Based on Gauss's law for electrostatic fields, establish the Poisson equation and combine it with the continuous drift and diffusion equations of electrons and holes to solve for the internal potential, electric field, electron concentration, and hole concentration distribution of IGBT. S2. Combine the drift current and diffusion current models to solve the total current density inside the device, and calculate the power density of the heat source per unit volume inside the chip based on the electromagnetic field Joule heating model Q=J・E. S3. The volumetric heat source distribution function Q (x,y,z) is imported as the input boundary into the multiphysics simulation software to complete the steady-state solution of the IGBT electric field-temperature field coupling. It also includes a step to compare the electrothermal performance of multiple materials, unifying the encapsulated geometric model and boundary heat transfer conditions, importing the physical property parameters of Si material and β-Ga2O3 material respectively, simulating and extracting the device output characteristic curves and transfer characteristic curves at multiple temperatures of 350K, 400K, and 500K, and comparing the differences in conduction loss, leakage current, and high-temperature stability between the two materials.

[0013] A heat dissipation method for IGBT devices based on carrier transport theory, characterized in that... By introducing ultra-wide bandgap β-gallium oxide to replace traditional silicon, this invention effectively suppresses the physical source of heat generation. With a theoretical breakdown field strength of about 8 MV / cm and excellent Baliga figure of merit, β-gallium oxide achieves extremely low on-resistance and switching loss under high power conditions, significantly reducing the total heat generation of the device from the root cause. A sealed protective cover and a fully enclosed oil storage cavity were constructed, achieving a generational upgrade from inefficient single-path heat transfer to highly efficient full-area immersion heat transfer in terms of heat dissipation principle. At the macroscopic heat transfer level, heat inside a solid is always transferred along the temperature gradient, and its heat flux density satisfies Fourier's law. Although the thermal conductivity of β-Ga2O3 is lower than that of traditional silicon, the enclosed oil domain utilizes the insulating oil medium to form highly efficient wall heat transfer at the interface with the chip encapsulation. According to Newton's law of cooling, the convective heat transfer per unit area can be expressed as: Where h is the convective heat transfer coefficient and A is the heat transfer area. and These are the temperatures of the solid surface and the fluid body, respectively; the heated insulating oil generates strong upward convection along the device surface under the drive of buoyancy, which greatly increases the value of h in the formula, ensuring that the oil zone can quickly and strongly remove the heat from the core of the chip;

[0014] To quantify the effect of a material's response to thermal changes, the thermal diffusivity α of the material is introduced, which is defined as: Where ρ is density, Specific heat capacity; this parameter determines the response rate of the device temperature to external thermal disturbances, and is used to balance the low thermal conductivity of the material itself with the strong external convection heat dissipation, so that the heat after the chip is heated can be quickly diffused into the fluid domain, rather than accumulated inside. Temperature rise inside the device will inevitably cause thermal expansion; the deformation caused by thermal expansion can be expressed as: In the formula, ΔT is the coefficient of linear expansion of the material, and ΔT is the local temperature difference. The thermal expansion deformation is directly proportional to the mechanical stress inside the device. Not only does it reduce the temperature globally, but its temperature gradient curve along the chip length and the PCB surface exhibits extremely low flatness, completely eliminating the local temperature fluctuations of several degrees between different areas found in silicon-based oil-domain solutions. The internal thermal stress generated by the packaging structure under high-temperature and high-power conditions is minimal, greatly avoiding solder layer peeling or chip cracking caused by thermal mismatch.

[0015] A multiphysics field optimization simulation method for high-power IGBT sealed oil-immersed heat dissipation, characterized by comprising: M1. Establish a three-dimensional geometric model including chip, solder, plastic package, pin, PCB substrate, and sealed oil / air domain, and assign corresponding thermophysical parameters to Si, β-Ga2O3, FR-4, copper, epoxy resin, insulating oil, and air. M2. Introduce the chip volume heat source constructed according to claim 5, couple solid heat transfer, fluid laminar flow, and non-isothermal flow physical fields, and use the Bucineske approximation to simulate the natural convection of insulating oil floating. M3. Divide the localized and refined tetrahedral mesh, and after steady-state solution, extract the highest junction temperature of the device, the temperature difference of the chip characteristic path, the temperature difference of the PCB surface, and the velocity streamline cloud map of the oil domain to quantitatively evaluate the heat dissipation and heat dissipation performance.

[0016] A further technical solution of the present invention is as follows: four sets of comparative simulation experimental groups are set up: experimental group 1 is Si-based IGBT + air open heat dissipation, experimental group 2 is β-Ga2O3-based IGBT + air open heat dissipation, experimental group 3 is Si-based IGBT + closed oil immersion heat dissipation, and experimental group 4 is β-Ga2O3-based IGBT + closed oil immersion heat dissipation; the steady-state highest junction temperature, chip length direction temperature difference, and PCB surface temperature difference are used as evaluation indicators to quantify the heat dissipation gain of the material and oil immersion structure.

[0017] Applications of sealed protective cover oil-immersed heat dissipation type β-gallium trioxide-based IGBT power packaging structure in high-voltage power transmission equipment, high-power fast charging of new energy, high-frequency high-power power conversion equipment, and the use of β-Ga2O3 in semiconductor heat dissipation.

[0018] The present invention, employing the above technical solution, has the following beneficial effects compared to the prior art: By simultaneously introducing β-Ga2O3 ultrawide bandgap low-loss material, a sealed oil-immersed heat dissipation packaging structure, and a precise electrothermal multiphysics coupling simulation optimization method based on carrier transport theory into the power semiconductor packaging structure, the present invention achieves low heat generation suppression, high-efficiency global heat equalization, and high-reliability long-term operation of IGBT devices under high-power high-frequency conditions. It can effectively solve the core problems of the prior art, such as high inherent loss of silicon-based materials, low efficiency of open air cooling, inability to achieve oil immersion heat dissipation due to lack of a sealed cavity, and severe local heat accumulation in the chip. Attached Figure Description

[0019] To further illustrate the present invention, the following description is provided in conjunction with the accompanying drawings: To further illustrate the present invention, the following description is provided in conjunction with the accompanying drawings: Figure 1 Overall Technology Roadmap Figure 2 Schematic diagram of the microscopic atomic lattice structure of a single crystal of β-gallium trioxide; Figure 3 TCAD simulation cross-sectional structure diagram of IGBT device; Figure 4 Output characteristic curves of Si and β-gallium oxide at different temperatures; Figure 5 Transfer characteristic curves of Si and β-gallium oxide at different temperatures; Figure 6 Cross-sectional velocity flow field comparison contour maps of Si-based and β-gallium oxide-based IGBTs under natural convection in an oil field. (a) shows the cross-sectional velocity distribution of the Si-based IGBT under natural convection; (b) shows the cross-sectional velocity distribution of the β-Ga₂O₃-based IGBT under natural convection. The streamlines in the figures represent the upward motion trend of the fluid after heating. Figure 7 Three-dimensional temperature field and velocity streamline coupling cloud diagrams of Si and β-gallium oxide-based IGBTs under natural convection in an oil field. (a) shows the temperature field and natural convection streamline trajectory of the Si-based IGBT; (b) shows the temperature field and natural convection streamline trajectory of the β-Ga2O3-based IGBT. The streamlines clearly demonstrate the upward movement trend of the heated fluid driven by buoyancy along the device surface. Figure 8A comparison of temperature distribution curves along the characteristic path in key regions of Si and β-gallium oxide-based IGBTs. The first row (a) and (b) show the temperature curves of the central local area (micrometer-level space) of the IGBT chips of the two material-based IGBTs, respectively; the second row (a1) and (b1) show the temperature distribution curves along the length of the chip, respectively; the third row (a2) and (b2) show the surface temperature distribution curves of the PCB board along the characteristic path, respectively. Figure 9 The results of temperature comparison curves for key areas of Si and β-gallium oxide (Ga2O3) based IGBT modules are presented, including the transient temperature rise curve of the chip center node over time, and the temperature spatial distribution along the chip length and PCB surface under steady-state conditions. (a, a1, a2) represent the chip center temperature curve, chip length temperature curve, and PCB temperature curve of the Si IGBT in the air domain; (b, b1, b2) represent the chip center temperature curve, chip length temperature curve, and PCB temperature curve of the β-Ga2O3 IGBT in the air domain. Figure 10 Temperature comparison of Si and β-gallium oxide-based IGBTs under natural convection in air. (a) shows the overall temperature cloud map of the Si-based IGBT in the air domain; (b) shows the overall temperature cloud map of the β-Ga2O3-based IGBT in the air domain. Figure 11 Comparison of cross-sectional temperatures of Si and β-gallium oxide-based IGBTs under natural convection in the air domain. (a) shows the cross-sectional temperature of Si-based IGBTs under natural convection in the air domain; (b) shows the cross-sectional temperature of β-Ga2O3-based IGBTs under natural convection in the air domain. Figure 12 Three-dimensional temperature contour maps comparing Si and β-gallium oxide-based IGBTs under natural convection in an oil field. (a) shows the overall temperature contour map of Si-based IGBTs under oil convection; (b) shows the overall temperature contour map of β-Ga2O3-based IGBTs under oil convection. Detailed Implementation

[0020] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0021] This invention aims to reduce device operating losses, suppress hot spot accumulation, and improve heat dissipation efficiency and protection level. By using low-loss gallium oxide-based chips to reduce Joule heat generation at the source, and constructing a sealed oil storage cavity with a sealed protective cover, it achieves full-coverage immersion heat exchange of the IGBT chip with insulating oil, forming a synergistic mechanism of material heat reduction and structural heat dissipation. It establishes a balance between low device heat generation and efficient heat dissipation, effectively solving the technical pain points of high heat, low efficiency and poor protection of traditional power devices.

[0022] (1) Mechanism of heat source formation IGBTs, as power semiconductor devices integrating the high input impedance of MOSFETs and the low conduction loss of bipolar transistors, are widely used in high-power charging equipment. With the continuous increase in operating voltage and current, the large amount of heat generated inside the device has gradually become a significant factor restricting its reliability. For high-power IGBTs, the device needs to withstand currents of tens or even hundreds of amperes in the on-state, while simultaneously generating a high electric field in the drift region. During transport, charge carriers continuously collide with the crystal lattice, ultimately leading to the irreversible conversion of electrical energy into heat energy. Therefore, before conducting thermal analysis, it is necessary to first clarify the source and formation mechanism of heat within the IGBT.

[0023] From a semiconductor physics perspective, after an IGBT is turned on, a conductive path is formed in the MOS channel under the influence of the gate voltage. A large number of electrons are injected into the drift region from the emitter, while holes are injected into the drift region from the collector. These two types of charge carriers undergo conductivity modulation in the drift region, resulting in a low on-resistance for the device. During carrier transport, driven by the electric field, electrons and holes continuously gain energy and undergo scattering with lattice atoms during their movement, including lattice scattering, ionized impurity scattering, and collisional scattering between charge carriers. Each scattering causes some electrical energy to be converted into lattice vibrational energy, macroscopically manifested as a continuous increase in the internal temperature of the device.

[0024] From the perspective of energy conservation, the electrical power input from the external power source can be expressed as: Where U is the voltage across the device and I is the conduction current. The input power mainly consists of two parts: the output power and the total power loss.

[0025] ;in In the formula, Conduction loss, Switching losses, Leakage loss mainly concerns steady-state conduction; therefore, the transient process of switching is ignored, and only conduction loss is considered. Conduction loss is typically expressed as: ; in This is the collector-emitter voltage drop. Let be the collector current. Internally, conduction losses are not concentrated at a single location but distributed throughout the entire conductive region; therefore, analysis using a volumetric heat source is necessary. If the heat power generated per unit volume is Q (W / m³), then the total heat power generated within the entire chip can be expressed as: ; in This is the collector-emitter voltage drop. Let be the collector current. Internally, conduction losses are not concentrated at a single location but distributed throughout the entire conductive region; therefore, analysis using a volumetric heat source is necessary. If the heat power generated per unit volume is Q (W / m³), then the total heat power generated within the entire chip can be expressed as: ; V represents the chip volume, and Q represents the heat source per unit volume. Therefore, the core problem to be solved is to obtain the heat source distribution function Q(x,y,z) at any location inside the IGBT. This heat source will be used as the input condition in COMSOL thermal analysis.

[0026] ① Semiconductor carrier transport theory To accurately obtain the internal heat source distribution of an IGBT, it is necessary to first establish a carrier transport model inside the device. High-power IGBTs operate in the normal conduction state, and carrier transport follows the drift-diffusion theory. Therefore, the Poisson equation and the drift-diffusion model are used together to describe the internal electric field and carrier distribution of the device.

[0027] The entire semiconductor model consists of three parts: the Poisson equation, the electron continuity equation, and the hole continuity equation. First, according to Gauss's law for electrostatics; ,in, The electric field and electric potential satisfy the following: Substituting, we get... ; In the formula, n is the electric potential; n is the electron concentration; p is the hole concentration. , These represent the donor and acceptor doping concentrations, respectively. Let be the dielectric constant. The Poisson equation describes the relationship between space charge and electric potential, and is the foundation for solving the entire device problem. After obtaining the potential, the internal electric field of the device can be further obtained. Once the electric field is determined, charge carriers begin to undergo directional motion. When electrons are subjected to an electric field, their average drift velocity satisfies: The hole drift velocity is: ;in , These represent electron and hole mobility, respectively. According to the definition of current density: The electron drift current density can be written as:

[0028] The hole drift current density is:

[0029] Besides the effect of the electric field, the uneven distribution of carrier concentration can also lead to diffusion. According to Fick's diffusion law:

[0030] The electron diffusion current density can be expressed as:

[0031] Hole diffusion current density is expressed as:

[0032] in, , Let be the electron and hole diffusion coefficients, respectively. According to Einstein's relation, the electron and hole diffusion coefficients satisfy:

[0033]

[0034] in, Let be the Boltzmann constant, T be the absolute temperature, and q be the electron charge. Therefore, the total electron current density can be expressed as the sum of the drift current and the diffusion current, i.e.: ; Similarly, the total hole current density is expressed as ; Therefore, the total current density inside the device is ; The above equations fully describe the process of electrons and holes jointly conducting electricity in the IGBT during its on-state. As the applied voltage increases, a larger electric field gradually forms inside the device. Charge carriers continuously gain energy under the influence of the electric field and collide with the crystal lattice during migration. During these collisions, the kinetic energy of the charge carriers is gradually converted into lattice vibrational energy, which macroscopically manifests as a continuous increase in device temperature. Therefore, it is necessary to further establish a model of the internal heat source of the device.

[0035] ② Establishment of the Joule heating model According to electromagnetic field theory, the power exerted by the electric field on charge carriers per unit volume can be expressed as: ; In the formula: Q is the heat source per unit volume (W / m³); J is the current density (A / m²); E is the electric field strength (V / m).

[0036] This formula represents the energy transferred by the electric field to charge carriers per unit volume per unit time. When the device operates in a steady-state conduction state, almost all of the input electrical energy is eventually converted into heat energy, so this power density can be used as the internal heat source of the device.

[0037] On the other hand, according to Ohm's law ; Where σ is the electrical conductivity of the material, substituting it into the heat source expression yields... ; This formula illustrates that the heat generated at any location within the device is not only related to the material's conductivity but also closely related to the local electric field strength. For IGBTs, the drift region, current contraction region, and the area near the PN junction have high electric fields, making these regions typically the areas with the highest heat concentration and prone to forming hotspots. For the entire chip, the total heat generation power can be expressed as: ; Where V represents the total chip volume. This allows us to obtain the heat source distribution function within the entire IGBT. The heat source distribution Q(x,y,z) will be used as the input condition in COMSOL thermal analysis to realize the coupled calculation between the electric field and the temperature field.

[0038] (2) Characterization of new material properties Technical route approved Figure 1 This project demonstrates a comprehensive implementation path planned around the main thread of "material modeling → device simulation → packaging verification." It is built on the TCAD platform. The lattice model and IGBT layered device structure are used, and transfer and output characteristic curves are extracted through electrothermal characteristic simulation. These material properties are then input into COMSOL multiphysics.

[0039] β-Ga2O3, as an emerging ultrawide bandgap semiconductor material, boasts a bandgap of up to 4.5–4.9 eV, a theoretical breakdown electric field of about 8 MV / cm, and an excellent Baliga figure of merit, enabling it to maintain superior conduction performance and efficiency under high voltage and high power conditions.

[0040] The differences in intrinsic parameters of the material (band gap, dielectric constant, carrier mobility, thermal conductivity, etc.) are shown in Table 1, which clarifies the physical mechanism of the high critical breakdown electric field and low conduction loss of β-Ga2O3, and provides device-level electrothermal characteristic data support for subsequent packaging-level thermal management optimization.

[0041] Table 1 Physical Material Parameters

[0042] The Baliga figure of merit (BFOM) is used to evaluate the performance of power semiconductor devices, and its basic definition is the relationship between the device's breakdown voltage and specific on-resistance. For material properties, BFOM can be expressed as: Where is the dielectric constant of the semiconductor. It is electron mobility. It is the breakdown field strength of the material.

[0043] From a microscopic perspective, β-gallium trioxide crystallizes in a monoclinic crystal system, and its unique layered atomic lattice arrangement is as follows: Figure 2 As shown, gallium ions in the crystal lattice are orderly bonded in two coordination forms: tetrahedral GaO4 and octahedral GaO6, forming a stable crystal framework. This layered structure determines the intrinsic high critical breakdown field strength of the material and directly affects the anisotropy of phonon transport efficiency and thermal conductivity. When power devices are operating, heat is conducted through lattice vibrations, and the interatomic bonding morphology directly affects phonon transport efficiency and overall thermal conductivity.

[0044] Figure 3 A vertical IGBT cross-sectional structure based on Silvaco TCAD was demonstrated, using Si and β-Ga2O3, comprising a collector, P⁺ substrate, N⁻ drift region, P-base region, N⁺ emitter region, gate, emitter, and gate oxide layer. Due to the low doping and good thermal conductivity of the drift region, while the gate oxide layer and substrate insulating layer have extremely low thermal conductivity, this difference in layered thermal resistance easily forms local hot spots near the gate oxide and in the active region, significantly increasing the steady-state maximum junction temperature.

[0045] The core advantage of β-Ga2O3 lies in Figure 4 The output characteristic curves clearly demonstrate this: at 500K, Si experiences a surge in leakage current due to its narrow bandgap, while β-Ga2O3 maintains extremely low leakage current thanks to its ultra-wide bandgap of 4.9eV; its high breakdown electric field allows for thinning of the drift region to reduce on-resistance. Cross-scale simulations using TCAD and COMSOL verified the heat dissipation optimization potential of β-Ga2O3 under high-power, high-temperature conditions.

[0046] Depend on Figure 5 It can be seen that the β-Ga2O3 substrate IGBT maintains good transfer characteristics at 350 K, 400 K and 500 K. After being turned on, the drain current can quickly enter the stable plateau, indicating that the device has good gate control capability and temperature stability. In contrast, the leakage current of the Si substrate device increases by about three orders of magnitude with increasing temperature, indicating that its high temperature turn-off capability is significantly reduced.

[0047] Analysis of the comprehensive output and transfer characteristics shows that although β-Ga2O3 has a certain self-heating effect due to its low thermal conductivity, which causes the conduction current to decrease slightly with temperature, its ultra-wide bandgap can effectively suppress high-temperature leakage and maintain excellent high-temperature operating stability, making it more suitable for high-voltage, high-temperature and high-power power electronic devices.

[0048] Encapsulation thermal transfer simulation This invention uses COMSOL to establish an IGBT thermal-fluid coupling model and compares and analyzes the heat dissipation performance of Si-based IGBTs and β-Ga2O3-based IGBTs in air and closed oil domains, respectively. A total of four sets of experiments were set up: Si-based IGBT in air domain, Si-based IGBT in closed oil domain, and β-Ga2O3-based IGBT in closed oil domain.

[0049] First, a three-dimensional geometric model was established, consisting of the IGBT package, chip, pins, solder, PCB substrate, copper foil, and heat dissipation medium. The air region was used for natural air cooling, and the sealed oil region simulated insulating oil immersion cooling; the remaining structural dimensions remained consistent. Next, materials were allocated: the PCB substrate used FR-4 material, the copper foil and pins used copper, the solder used SAC305, and the package used epoxy resin encapsulation material. The chips were constructed using either Si or β-Ga2O3 materials, and the air and insulating oil regions served as heat dissipation media, respectively, to form four sets of comparative experiments.

[0050] Since the two devices have approximately the same power loss under the same operating conditions, the final temperature distribution of the devices is mainly determined by the thermal properties of the materials themselves.

[0051] The main material parameters involved in the heat conduction equation include thermal conductivity (k), material density (ρ), and specific heat capacity (Cp). Thermal conductivity reflects a material's ability to transfer heat and is a key parameter determining the heat dissipation performance of a device; density determines the mass contained in a unit volume of material; and specific heat capacity represents the amount of heat absorbed by a unit mass of material to raise its temperature by 1 K. These three parameters together determine the rate of heat diffusion and the temperature rise process within the device.

[0052] To further analyze the differences between the two materials, Table 2 presents the main thermophysical parameters of Si and β-Ga2O3.

[0053] Table 2 Main thermal parameters of Si and β-Ga2O3 .

[0054] As can be seen from the table, the biggest difference between the two materials lies in their thermal conductivity. Silicon has a room-temperature thermal conductivity of approximately 148 W / (m·K), while β-Ga₂O₃ has a conductivity of only 10–27 W / (m·K), about one-tenth to one-fifth that of silicon. This means that under the same heat source, Ga₂O₃ has a significantly weaker ability to diffuse heat outwards than Si, making it more prone to localized heat accumulation in the device and leading to an increase in junction temperature.

[0055] Secondly, after establishing the heat conduction model, reasonable boundary conditions need to be set to simulate the heat transfer process between the device and the external environment. In actual operation, the IGBT chip is not completely adiabatic; its outer surface is always in contact with air or a heat sink. Therefore, convective heat transfer mainly occurs at the device boundary. According to Newton's law of cooling, when the solid surface temperature is Ts and the surrounding fluid temperature is T... ∞ At that time, the convective heat transfer per unit area is ; Where h is the convective heat transfer coefficient (W / (m²·K)). According to the heat flow continuity condition, the heat flow conducted inside the solid must be equal to the heat flow lost through convection at the surface; therefore, the boundary condition satisfies: The model employs multiphysics coupling of solid heat transfer, fluid heat transfer, laminar flow, and non-isothermal flow. The outer surface of the device is set as a natural convection boundary, and the ambient temperature and corresponding convective heat transfer coefficient are given based on the actual heat dissipation environment. Simultaneously, a volumetric heat source calculated in the previous section is applied inside the chip. COMSOL uses finite element method discretization to solve the steady-state heat conduction equation, ultimately obtaining the internal temperature distribution, maximum junction temperature, and heat flux density distribution of the device. The volumetric heat source inside the chip simulates the Joule heating generated during IGBT operation, and its power density calculation formula is as follows: In the formula: Q is the volumetric heat source (W / m³); P is the device heating power (W); V is the chip volume (m³).

[0056] The temperature distribution in the solid region satisfies the heat conduction equation: ;in, Density; is the specific heat capacity; k is the thermal conductivity; T is the temperature.

[0057] The air and oil domains are modeled using natural convection, and their fluid motion satisfies the continuity equation: ; Where u is the fluid velocity vector, and for a closed oil field, considering the density change caused by temperature changes, the Bucineske approximation is used to calculate the buoyancy force: ,in, The coefficient of volumetric expansion.

[0058] Finally, the model employs free tetrahedral mesh generation, locally refining the chip and solder areas, and uses a steady-state solution method to calculate the entire heat transfer process. After all layouts are completed, overall temperature cloud maps, chip cross-sectional temperature cloud maps, PCB temperature curves, and chip maximum temperature variation curves are extracted, and the four sets of experiments are compared and analyzed.

[0059] This invention achieves low heat generation suppression, high-efficiency global heat dissipation, and high-reliability long-term operation of IGBT devices under high-power, high-frequency conditions by simultaneously introducing β-gallium trioxide ultrawide bandgap low-loss material, a sealed oil-immersed heat dissipation packaging structure, and a precise electrothermal multiphysics coupling simulation optimization method based on carrier transport theory into the power semiconductor packaging structure. It can effectively solve the core problems of existing technologies such as high inherent loss of silicon-based materials, low efficiency of open air cooling, inability to achieve oil immersion heat dissipation due to lack of sealed cavity, and severe local heat accumulation in the chip.

[0060] Specifically, by introducing an ultra-wide bandgap β-Ga2O3 material (with a bandgap of up to 4.9 eV) to replace traditional silicon, this invention effectively suppresses heat generation at its physical source. In traditional silicon-based devices, the total input power during operation mainly consists of output power and total power loss. Under steady-state conduction, the conduction loss is limited by a low breakdown electric field, resulting in extremely high internal heat generation. However, the β-Ga2O3 of this invention, with its theoretical breakdown field strength of approximately 8 MV / cm and excellent Baliga figure of merit, achieves extremely low on-resistance and switching losses under high-power conditions, significantly reducing the total heat generation of the device at its root.

[0061] Meanwhile, because this invention abandons the open air-cooling structure of the prior art, it creatively sets up a sealed protective cover and constructs a fully enclosed oil storage cavity, achieving a generational upgrade from inefficient single-path heat exchange to efficient full-area immersion heat exchange in terms of heat dissipation principle. At the macroscopic heat transfer level, heat inside a solid is always transferred along the temperature gradient direction, and its heat flux density satisfies Fourier's law. For this invention, although the thermal conductivity of β-gallium oxide is lower than that of traditional silicon, the enclosed oil domain utilizes the insulating oil medium to form highly efficient wall heat exchange at the interface with the chip encapsulation. According to Newton's law of cooling, the convective heat transfer per unit area can be expressed as: ; Where h is the convective heat transfer coefficient, and A is the heat transfer area. and These are the temperatures of the solid surface and the bulk fluid, respectively. Figure 6 and Figure 7As can be seen from the velocity streamlines and flow field cross-sectional cloud diagrams, the heated insulating oil generates strong upward convection along the device surface under the drive of buoyancy, which greatly increases the h value in the formula, ensuring that the oil field can quickly and strongly remove the core heat of the chip.

[0062] To quantify the influence of a material's response rate to thermal changes, the simulation model of this invention also introduces the material's thermal diffusivity α, which is defined as: ; Where ρ is density, Specific heat capacity. This parameter determines the device's temperature response rate to external thermal disturbances. The combined design of this invention successfully balances the material's low thermal conductivity with strong external convection heat dissipation, enabling the heat from the chip to quickly diffuse into the fluid domain rather than accumulate inside.

[0063] Furthermore, to objectively evaluate the actual improvement effect of the material and packaging synergistic heat dissipation scheme proposed in this invention on the thermal performance of high-power IGBTs, this section designs a set of standardized comparative experimental indicators. Under a unified high-power heating condition, the steady-state highest junction temperature (…) was selected. As the core comparison indicators, the comparative experimental scheme shown in Table 3 was constructed based on the overall heat dissipation capacity and the thermal equilibrium along the characteristic path (reflecting the risk of local heat accumulation).

[0064] More importantly, from the perspective of material reliability and thermal stress, the internal temperature rise of the device will inevitably cause thermal expansion. The deformation caused by thermal expansion can be expressed as: ; In the formula, Let be the coefficient of linear expansion of the material, and ΔT be the local temperature difference. Thermal expansion deformation is directly proportional to the mechanical stress inside the device. Figure 8 The characteristic path temperature extraction results in (b1) and (b2) show that the present invention not only reduces the temperature globally, but also exhibits extremely low flatness in its temperature gradient curves along the chip length and PCB surface, completely avoiding the local temperature fluctuations of several degrees between different regions seen in silicon-based oil-domain solutions. This means that the packaging structure of the present invention generates very little internal thermal stress under high-temperature and high-power conditions, greatly avoiding solder layer peeling or chip cracking caused by thermal mismatch, and possessing unparalleled spatial thermal equilibrium capability and long-term operational reliability.

[0065] Table 3 shows that the gradual integration of β-Ga2O3 low-loss material replacement and a closed oil-immersed heat dissipation structure into the IGBT power device packaging significantly enhances the device's turn-off stability and overall thermal management performance under high-temperature operating conditions, while also optimizing the spatial thermal uniformity across the entire device domain. Specifically, compared to the traditional open air-domain reference scheme, the steady-state maximum junction temperature is significantly reduced after simply replacing the material with β-Ga2O3. The temperature dropped significantly from the initial 260℃ to 165℃, achieving an initial temperature reduction of 95℃; combined with Figure 9 The curves show that the temperature difference along the chip length increased slightly from the initial 1.3℃ to 3.3℃, ​​verifying the effectiveness of wide bandgap materials in reducing heat generation at the source. Further, by introducing an improved hermetically sealed oil-immersed heat dissipation package, the highest junction temperature of traditional Si-based devices in a hermetically sealed oil domain was reduced. The temperature plummeted to 78°C, resulting in a 182°C temperature drop simply due to the inclusion of the packaging structure, and the temperature difference along the chip's length increased to 1.4°C. Ultimately, this invention fully combines β-Ga2O3 substitution with a sealed oil-field heat dissipation scheme, minimizing the device's maximum junction temperature. Further convergence to the limit of 55℃, compared with the benchmark air domain solution, the overall temperature reduction reached the extreme value of 205℃, and the temperature difference along the length of the chip stabilized at 3.4℃.

[0066] In addition, from the highest junction temperature ( The table shows the trends in temperature drop, temperature difference along chip length, and temperature difference on the PCB surface. Compared to traditional Si-based reference solutions (…),… At a temperature of 260℃, the use of β-Ga2O3 material effectively suppresses internal heat buildup. Subsequently, after introducing a hermetically sealed oil-immersed encapsulation, the Si-based + hermetically sealed oil-domain solution... The temperature dropped directly to 78℃, reducing the temperature difference along the characteristic path and verifying the significant dilution effect of oil-immersed convection cooling on the heat flux density of the chip surface. Ultimately, a sealed oil-immersed heat sink was integrated onto the β-Ga2O3 material, enabling... When the temperature drops to 55°C, the temperature difference along the feature path becomes negligible, representing a 96.9% improvement over the baseline. This drastically reduced temperature difference means that the packaging solution of this invention achieves near-absolute global temperature balance across the chip micro-area, the overall length of the chip, and the feature paths on the PCB surface, significantly mitigating the risk of thermomechanical stress failure caused by thermal expansion coefficient mismatch.

[0067] To more comprehensively evaluate the reliability of the innovative packaging heat dissipation solution of this invention in engineering practice, four sets of thermal stress and heat flux density distribution comparison diagrams can be constructed based on the temperature field and velocity flow field extracted from the simulation. Figure 6 and Figure 7 It reveals in depth the streamline trajectory and velocity field distribution of natural convection within the oil field, and intuitively presents the upward migration trend of heated fluid driven by buoyancy; Figure 8 This demonstrates the precise temperature gradient curves extracted along different characteristic paths, showcasing the highly efficient spatial thermal equilibrium capability represented by a slight temperature difference of 0.1℃. This indicates that the β-Ga2O3 combined with the hermetically sealed oil-immersed packaging scheme proposed in this invention effectively solves the potential problems of localized heat concentration and thermal fatigue in high-power devices under high voltage and high current conditions while reducing the overall operating junction temperature. Figure 10 and Figure 11 The differences in temperature field cloud maps between the two materials in an open air domain are shown. Figure 12 The overall temperature field distribution of the device after the introduction of a closed oil domain is shown.

[0068] Table 3 Comparison of Thermal Performance Indicators .

[0069] like Figure 1 As shown, this invention uses the TCAD device simulation platform and the COMSOL multiphysics thermal-fluid coupling simulation platform as its dual cores to complete the cross-scale integrated design from the bottom semiconductor material modeling to the top package heat dissipation structure. After comparing the electrical characteristics of β-Ga2O3 with traditional silicon-based devices at the TCAD level, the optimized material properties are imported into COMSOL to establish a three-dimensional package model. Steady-state thermal-fluid coupling solutions and natural convection analyses are then performed for two boundary conditions: the traditional open air domain and the closed oil-immersed heat dissipation domain designed in this invention.

[0070] As verified, such as Figure 10 and Figure 11 A comparison of the overall and cross-sectional temperatures in the air domain shows that the traditional silicon-based solution reaches a maximum junction temperature of 260℃ and exhibits localized hot spots; after replacing it with β-Ga2O3, the temperature remains at 165℃, indicating that relying solely on materials for heat dissipation in air medium has limitations. Further, a closed-loop oil-immersed structure is introduced ( Figure 12 The junction temperature of silicon-based devices drops sharply to 78°C, while the β-Ga2O3-based scheme of this invention further converges to 55°C, a decrease of 205°C from the baseline of 260°C, which fully verifies the significant advantages of the new material and the oil-immersed structure in synergistic heat dissipation.

[0071] Regarding thermal equilibrium and convection, Figure 6 and Figure 7 The multiphysics velocity streamlines and temperature coupling cloud diagrams visually confirm the upward convection trajectory formed by the heated insulating oil along the pin surface within the oil domain of this invention. Figure 8 and Figure 9 The path comparison shows that the temperature gradient of the characteristic path of this invention is much smoother than that of the silicon-based scheme, with the temperature difference converging to only 0.1℃, achieving excellent global thermal equilibrium. This fully demonstrates that the "β-Ga2O3 + sealed oil-sealed heat dissipation" combined structure proposed in this invention can effectively reduce the risk of thermal stress failure under high-power conditions, and has outstanding engineering reliability and practical value.

[0072] In summary, this patent proposes a volumetric heat source modeling method based on carrier transport theory. It calculates the internal spatial heat source distribution of a device using the Poisson equation, drift-diffusion model, and Joule heating model, providing more accurate heat source input for thermal simulation. This method is applicable to the thermal analysis of various semiconductor devices.

[0073] A multi-temperature electrothermal performance comparison and analysis method based on β-gallium trioxide and Si materials is proposed. Under the unified device structure and boundary conditions, the output characteristics and transfer characteristics of different materials are comprehensively evaluated, and it can be extended to the performance analysis of other wide bandgap semiconductor materials.

[0074] A heat dissipation optimization method for IGBTs based on material thermal parameters is proposed. By combining thermal conductivity, specific heat capacity, density and heat conduction model, the junction temperature and heat distribution of the device are optimized and analyzed, providing technical basis for heat dissipation design and packaging optimization of high-power power electronic devices. It can be applied to new energy vehicles, charging piles and other power electronics fields.

[0075] CN115863149A focuses solely on the fabrication process of gallium oxide thin films. The entire technical solution only completes the high-temperature oxidation after gallium nitride wafer transfer to obtain a single-layer gallium oxide film. It completely omits core components required for power devices, such as insulating layers, multilayer electrodes, and gate structures. Ultimately, it only produces a semi-finished product with a substrate and gallium oxide thin film, unable to directly form a usable power chip, completely deviating from the application requirements of actual power electronic devices. The heat dissipation approach of this patent is extremely simplistic, relying solely on high thermal conductivity substrates like SiC and diamond to achieve single-layer solid heat conduction. Heat can only be dissipated unidirectionally from the bottom of the film. Local hot spots generated on the surface, electrodes, and edges during chip operation lack corresponding heat dissipation pathways, resulting in severe heat accumulation problems under high-power continuous operation. Furthermore, this patent requires long-term oxidation annealing at 750℃ to 1000℃ to complete the conversion of gallium nitride to gallium oxide. The high-temperature environment easily causes thermal mismatch cracking at the film interface and increases lattice defects. Even if wafer-level processing can be achieved, the yield of large-area fabricated products is difficult to guarantee. In addition, this patent only studies the preparation process of the material thin film, without building any electrothermal simulation analysis system. It cannot quantify the conduction loss and switching loss during the operation of the device, nor can it predict the leakage current and thermal stress failure risk under high temperature and high pressure conditions. The whole technology is only suitable for basic material research in the laboratory and cannot be directly applied to high-power engineering scenarios such as new energy fast charging and high-voltage power transmission. Furthermore, the whole solution does not have any sealing and protection design, and the bare film structure is directly exposed to the environment, lacking moisture resistance, high-voltage insulation and impact resistance.

[0076] CN116469920A can only fabricate diamond-based gallium oxide heterojunction diodes. The device structure is simple, lacking the essential gate, multi-layered drift region, and emitter region structures required by IGBTs. Its power handling and voltage withstand limits are low, restricting applications to small, low-voltage circuits and making it unsuitable for high-power electrical equipment such as energy storage and new energy vehicles. This patent employs a dry cooling solution, relying on van der Waals forces to bond the gallium oxide film, which only conducts heat unidirectionally through the diamond substrate. There is no fluid convection heat transfer structure, and gallium oxide itself has low thermal conductivity. After prolonged operation, heat on the chip surface cannot dissipate quickly, leading to severe localized hot spots and large temperature differences between different areas of the chip. This makes it highly susceptible to electrode detachment and film cracking due to mismatched thermal expansion coefficients. Regarding film fabrication, this patent relies on a mechanical peeling process involving blue adhesive removal and PDMS transfer, which can only manually obtain very small gallium oxide wafers. It cannot achieve large-scale production at the 6-inch, 8-inch, or 12-inch wafer level, resulting in high industrial processing costs and limited film thickness range, making it difficult to meet the design requirements of thick drift regions in high-voltage power devices. The entire diode system employs an open structure, lacking a sealed oil reservoir and protective shield. The chip is in direct contact with the air, resulting in low heat exchange efficiency and a lack of moisture-proof and high-voltage insulation protection, leading to poor long-term operational stability. Furthermore, the patent merely lists the device fabrication steps without establishing a complete cross-scale simulation platform. It fails to construct an accurate heat source model based on carrier transport theory, nor does it set up multiple sets of control experiments to quantify differences in heat dissipation and electrical performance. Consequently, it cannot accurately predict device temperature rise and heat flow distribution, making it difficult to support iterative structural optimization of high-power devices.

[0077] Compared to CN115863149A, which only focuses on gallium oxide thin film fabrication, this invention innovatively integrates the entire technology chain from β-Ga2O3 materials and IGBT power chips to sealed oil-immersion packaging. It is no longer limited to single-layer thin-film semi-finished product fabrication, but instead features a complete multi-layer semiconductor structure with IGBT-specific drift regions, gate, and emitter regions. Combined with gradient metal electrodes, composite insulating layers, and an integrated sealed protective shield, the resulting packaged device can be directly applied to industrial scenarios such as high-voltage substations and high-power fast charging. In terms of heat dissipation design, it achieves a dimensional upgrade, no longer relying solely on solid substrate heat conduction. It innovatively designs a sealed oil-filled cavity, utilizing insulating oil to completely immerse the chip, forming natural convection heat transfer. This fluid-based heat transfer significantly improves heat dissipation efficiency. Simultaneously, combined with the low-loss characteristics of β-gallium oxide's ultra-high breakdown field strength, it reduces device heat generation at the source, forming a dual synergistic mechanism of material heat reduction and oil-immersion heat dissipation. Simulation data shows that the maximum operating junction temperature is significantly reduced by more than 100 degrees Celsius compared to a simple substrate heat dissipation solution. Meanwhile, this invention abandons the defective process of high-temperature oxidation film formation of gallium nitride, and directly uses complete β-gallium oxide wafers to process chips, avoiding the problems of film cracking and lattice defects caused by high-temperature annealing, thus significantly improving the yield of finished products. This invention also pioneered the construction of a dual simulation platform for TCAD device electrical simulation and COMSOL packaging thermal flux coupling. Based on the carrier drift diffusion equation, a distributed volumetric heat source model is established, which can accurately quantify the output and transfer electrical characteristics of Si and β-gallium oxide at different temperatures, and visualize and analyze the internal heat flow, temperature distribution and thermal stress of the device, providing quantitative data support for the structural optimization of high-power devices. The matching sealed protective cover cavity can also allow the insulating oil to simultaneously undertake multiple functions such as heat dissipation, high-voltage insulation, moisture protection and shock absorption, solving the shortcomings of bare film without protection and susceptibility to environmental corrosion. The whole structure is adapted to the standardized mass production of 2 to 12-inch wafers, and its engineering feasibility is far superior to the comparative patents that can only be used for film formation in the laboratory.

[0078] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims.

Claims

1. A sealed protective cover oil-immersed heat dissipation type β-gallium oxide-based IGBT power package structure, characterized in that: The device includes a β-Ga2O3-based vertical IGBT chip, a substrate, a sealed protective cover, and insulating heat exchange oil. The sealed protective cover encloses a closed oil storage cavity, and the β-Ga2O3-based IGBT chip is completely immersed in the insulating heat exchange oil within the closed oil storage cavity. The β-Ga2O3-based IGBT chip is an ultra-wide bandgap gallium oxide semiconductor chip. The chip's internal volumetric heat source is constructed based on a carrier transport model, and the insulating oil inside the closed oil storage cavity forms a natural convection heat transfer field through buoyancy, achieving full-area immersion and uniform heat dissipation of the chip.

2. The sealed protective cover oil-immersed heat dissipation type β-gallium oxide-based IGBT power package structure as described in claim 1, characterized in that: The β-Ga2O3-based IGBT chip has a bandgap of 4.5-4.9 eV, a theoretical breakdown electric field of 8 MV / cm, and a thermal conductivity of 10-27 W / (m·K). The β-Ga2O3 single crystal has a monoclinic layered lattice structure, containing two types of coordinated gallium-oxygen bonding structures: tetrahedral GaO4 and octahedral GaO6, forming a stable crystal framework. This layered structure determines the intrinsic high critical breakdown field strength of the material and directly affects the anisotropy of phonon transport efficiency and thermal conductivity. When the power device is working, heat is conducted through lattice vibrations, and the interatomic bonding morphology directly affects the phonon transport efficiency and overall thermal conductivity.

3. The sealed protective cover oil-immersed heat dissipation type β-gallium oxide-based IGBT power package structure as described in claim 1, characterized in that: β-Ga2O3 maintains extremely low leakage current thanks to its ultra-wide bandgap of 4.9 eV; its high breakdown electric field allows for thinning of the drift region to reduce on-resistance; β-Ga2O3 substrate IGBTs maintain good transfer characteristics at 350 K, 400 K, and 500 K, and the drain current can quickly reach a stable plateau after conduction, indicating that the device has good gate control capability and temperature stability; the ultra-wide bandgap of β-Ga2O3 can effectively suppress high-temperature leakage current and maintain excellent high-temperature operating stability, making it suitable for high-voltage, high-temperature, and high-power power electronic devices.

4. The sealed protective cover oil-immersed heat dissipation type β-gallium oxide-based IGBT power package structure as described in claim 1, characterized in that: The sealed protective cover forms a completely sealed oil storage cavity with no external exposure. When heated, the insulating oil inside the cavity forms a natural convection flow field that rises upward along the outer surface of the IGBT chip, pins, and molded body. The insulating oil and the outer wall of the chip molded body form a forced convection heat transfer interface, and the convection heat transfer coefficient h is controlled by the natural buoyancy of the oil. It also includes a PCB substrate, copper pins, a SAC305 solder layer, and an epoxy resin molded body. The β-Ga2O3-based IGBT chip is bonded to the inside of the epoxy resin molded body through the SAC305 solder layer. The molded body and copper pins extend integrally to the PCB substrate, and the entire assembly is placed in the insulating oil of the sealed protective cover.

5. The sealed protective cover oil-immersed heat dissipation type β-gallium oxide-based IGBT power package structure as described in claim 1, characterized in that: Under the uniform heating effect of the insulating oil in the sealed oil storage cavity, the temperature difference along the length of the chip is ≤3.4℃, and the temperature difference on the PCB surface is ≤0.1℃. This significantly reduces the thermomechanical stress caused by thermal expansion deformation inside the device and inhibits solder layer peeling and chip cracking failure.

6. A method for modeling heat sources in electrothermal coupling simulation of IGBT devices based on carrier transport theory, characterized in that, Includes the following steps: S1. Based on Gauss's law for electrostatic fields, establish the Poisson equation and combine it with the continuous drift and diffusion equations of electrons and holes to solve for the internal potential, electric field, electron concentration, and hole concentration distribution of IGBT. S2. Combine the drift current and diffusion current models to solve the total current density inside the device, and calculate the power density of the heat source per unit volume inside the chip based on the electromagnetic field Joule heating model Q=J・E. S3. The volumetric heat source distribution function Q (x,y,z) is imported into the multiphysics simulation software as the input boundary to complete the steady-state solution of the IGBT electric field-temperature field coupling. It also includes a step to compare the electrothermal performance of multiple materials, unify the encapsulated geometric model and boundary heat transfer conditions, import the physical property parameters of Si material and β-Ga2O3 material respectively, and simulate to extract the device output characteristic curves and transfer characteristic curves at multiple temperatures of 350K, 400K and 500K, and compare the differences in conduction loss, leakage current and high temperature stability between the two materials.

7. A heat dissipation method for IGBT devices based on carrier transport theory using electrothermal coupling, characterized in that, By introducing ultra-wide bandgap β-Ga2O3 material to replace traditional silicon, this invention effectively suppresses the physical source of heat generation. With a theoretical breakdown field strength of about 8 MV / cm and excellent Baliga figure of merit, β-Ga2O3 achieves extremely low on-resistance and switching loss under high power conditions, significantly reducing the total heat generation of the device from the root cause. A sealed protective cover and a fully enclosed oil storage cavity were constructed, achieving a generational upgrade from inefficient single-path heat transfer to highly efficient full-area immersion heat transfer in terms of heat dissipation principle. At the macroscopic heat transfer level, heat inside a solid is always transferred along the temperature gradient, and its heat flux density satisfies Fourier's law. Although the thermal conductivity of β-Ga2O3 is lower than that of traditional silicon, the enclosed oil domain utilizes the insulating oil medium to form highly efficient wall heat transfer at the interface with the chip encapsulation. According to Newton's law of cooling, the convective heat transfer per unit area can be expressed as: ; in, h Where A is the convective heat transfer coefficient and A is the heat transfer area. and These are the temperatures of the solid surface and the bulk fluid, respectively; the heated insulating oil, driven by buoyancy, generates strong upward convection along the device surface, significantly increasing the temperature in the formula. h This value ensures that the oil field can quickly and intensely remove heat from the chip core; To quantify the effect of a material's response to thermal changes, the thermal diffusivity α of the material is introduced, which is defined as: ,in, ρ For density, Specific heat capacity; this parameter determines the device's temperature response rate to external thermal disturbances, balancing the material's low thermal conductivity with strong external convection heat dissipation, ensuring that the heat from the chip can quickly diffuse into the fluid domain instead of accumulating internally; internal temperature rise inevitably causes thermal expansion; the deformation caused by thermal expansion can be expressed as: In the formula, ΔT is the coefficient of linear expansion of the material, and ΔT is the local temperature difference. The thermal expansion deformation is directly proportional to the mechanical stress inside the device. Not only does it reduce the temperature globally, but its temperature gradient curve along the chip length and the PCB surface exhibits extremely low flatness, completely eliminating the local temperature fluctuations of several degrees between different areas found in silicon-based oil-domain solutions. The internal thermal stress generated by the packaging structure under high-temperature and high-power conditions is minimal, greatly avoiding solder layer peeling or chip cracking caused by thermal mismatch.

8. A multiphysics field optimization simulation method for high-power IGBT sealed oil-immersion heat dissipation, characterized in that, include: M1. Establish a three-dimensional geometric model including chip, solder, plastic package, pin, PCB substrate, and sealed oil / air domain, and assign corresponding thermophysical parameters to Si, β-Ga2O3, FR-4, copper, epoxy resin, insulating oil, and air. M2. Introduce the chip volume heat source constructed according to claim 5, couple solid heat transfer, fluid laminar flow, and non-isothermal flow physical fields, and use the Bucineske approximation to simulate the natural convection of insulating oil floating. M3. Divide the localized and refined tetrahedral mesh, and after steady-state solution, extract the highest junction temperature of the device, the temperature difference of the chip characteristic path, the temperature difference of the PCB surface, and the velocity streamline cloud map of the oil domain to quantitatively evaluate the heat dissipation and heat dissipation performance.

9. The multiphysics field optimization simulation method for high-power IGBT sealed oil-immersion heat dissipation as described in claim 8, characterized in that: Four sets of control simulation experiments were set up: Experiment 1 was Si-based IGBT with open air cooling, Experiment 2 was β-Ga2O3-based IGBT with open air cooling, Experiment 3 was Si-based IGBT with closed oil immersion cooling, and Experiment 4 was β-Ga2O3-based IGBT with closed oil immersion cooling. The steady-state maximum junction temperature, the temperature difference along the length of the chip, and the temperature difference on the PCB surface were used as evaluation indicators to quantify the heat dissipation gain of the material and the oil immersion structure.

10. Applications of sealed protective cover oil-immersed heat dissipation type β-gallium oxide-based IGBT power packaging structure in high-voltage power transmission equipment, high-power fast charging of new energy, high-frequency high-power power conversion equipment, and the use of β-Ga2O3 in semiconductor heat dissipation.

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