Aluminum ribbon bonded gan high temperature power module

Abstract

The utility model relates to power device technical field, concretely relates to a kind of GaN high-temperature power module of aluminium band bonding, comprising: heat dissipation substrate, the surface of heat dissipation substrate is connected with metallized ceramic substrate;Gallium nitride chip, is fixed on the metallized ceramic substrate;Aluminium band, connects the gallium nitride chip and the metallized ceramic substrate;Shell, with heat dissipation substrate sealing connection;Power terminal, set on the shell, connect the metallized ceramic substrate.The utility model uses aluminium band bonding technology to replace traditional aluminium wire bonding, by increasing the electrically conductive cross-sectional area and heat dissipation capacity, effectively reduce the local overheating risk under high current condition;Meanwhile, using the high-temperature stability and high electron mobility characteristics of gallium nitride (GaN) chip, the high-temperature performance and power carrying capacity of power module are significantly improved, so that better reliability and high-temperature working capacity are realized under the constraint of miniaturization, high power density.

Description

Technical Field

[0001] This utility model relates to the field of power device technology, specifically to a GaN high-temperature power module with aluminum strip bonding. Background Technology

[0002] With the rapid development of new energy vehicles and aerospace, power modules need to meet the requirements of higher power density and smaller size. Traditional power device packaging processes typically use aluminum wire bonding technology to electrically interconnect metallized ceramic substrates with ordinary silicon chips. However, due to the small cross-sectional area, aluminum wire bonding is prone to localized overheating under high current conditions, affecting the reliability of the module. At the same time, silicon-based power chips have limited high-temperature resistance and are prone to performance degradation in high-temperature environments, further limiting the operating temperature range and power handling capacity of power modules.

[0003] To adapt to high-power, high-temperature operating scenarios, the industry urgently needs to optimize traditional packaging processes. Aluminum ribbon bonding technology has attracted attention due to its larger conductive cross-sectional area and better heat dissipation capabilities, while the high-temperature stability and high electron mobility of wide-bandgap semiconductor materials (such as GaN) also offer possibilities for improving the performance of power modules. However, under the constraints of high power density and miniaturization, how to effectively solve the temperature rise problem and improve the high-temperature operating capability of modules remains a key challenge facing current power module technology. Utility Model Content

[0004] To address the above technical problems, this invention provides a GaN high-temperature power module with aluminum strip bonding.

[0005] The technical problem solved by this utility model can be achieved by the following technical solution:

[0006] A GaN high-temperature power module with aluminum strip bonding, comprising:

[0007] A heat dissipation substrate, wherein a metallized ceramic substrate is attached to the surface of the heat dissipation substrate;

[0008] A gallium nitride chip is fixed on the metallized ceramic substrate;

[0009] An aluminum strip connects the gallium nitride chip and the metallized ceramic substrate;

[0010] The outer casing is sealed to the heat dissipation substrate;

[0011] A power terminal is disposed on the housing and connected to the metallized ceramic substrate.

[0012] Preferably, the metallized ceramic substrate comprises:

[0013] The ceramic layer serves as a carrier for electrical isolation and heat conduction.

[0014] A copper layer on the back side, located on the lower surface of the ceramic layer, is connected to the heat dissipation substrate by solder.

[0015] The emitter is located on the upper surface of the ceramic layer, and a copper emitter layer is provided on top of it.

[0016] Preferably, the gallium nitride chip is fixed to the emitter by solder.

[0017] Preferably, the anode of the gallium nitride chip is bonded to the emitter copper layer via the aluminum strip.

[0018] Preferably, the power terminal is connected to the emitter copper layer by an ultrasonic welding process.

[0019] Preferably, the number of power terminals matches the number of gallium nitride chips.

[0020] Preferably, the size and total area of ​​the metallized ceramic substrate are smaller than those of the heat dissipation substrate.

[0021] Preferably, the metallized ceramic substrate is a copper-clad ceramic substrate.

[0022] Preferably, the gallium nitride chip is a wide bandgap semiconductor material.

[0023] Preferably, the outer casing is sealed to the heat dissipation substrate by a sealant.

[0024] The advantages or beneficial effects of this utility model are as follows: This utility model uses aluminum strip bonding technology to replace traditional aluminum wire bonding, which effectively reduces the risk of local overheating under high current conditions by increasing the conductive cross-sectional area and heat dissipation capacity; at the same time, by utilizing the high temperature stability and high electron mobility characteristics of gallium nitride (GaN) chips, the high temperature resistance and power carrying capacity of the power module are significantly improved, thereby achieving better reliability and high temperature operation under the constraints of miniaturization and high power density. Attached Figure Description

[0025] Figure 1 This is a front view of the overall structure of the GaN high-temperature power module of this utility model;

[0026] Figure 2 This is an enlarged view showing the structural details of the GaN high-temperature power module of this utility model;

[0027] Figure 3 This is a side sectional view of the overall structure of the GaN high-temperature power module of this utility model.

[0028] Explanation of reference numerals in the attached diagram: 1. Power terminal; 2. Gallium nitride chip; 3. Emitter; 4. Solder; 5. Heat sink substrate; 6. Emitter copper layer; 7. Sealant; 8. Back copper layer; 9. Housing; 10. Aluminum strip. Detailed Implementation

[0029] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0031] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the present invention.

[0032] Reference Figures 1 to 3 This utility model provides a GaN high-temperature power module with aluminum strip bonding, comprising:

[0033] A heat dissipation substrate 5, wherein a metallized ceramic substrate is attached to the surface of the heat dissipation substrate 5;

[0034] Gallium nitride (GaN) chip 2 is fixed on the metallized ceramic substrate;

[0035] Aluminum strip 10 connects the gallium nitride chip 2 and the metallized ceramic substrate;

[0036] The outer casing 9 is sealed to the heat dissipation substrate 5;

[0037] Power terminal 1 is disposed on the housing 9 and connected to the metallized ceramic substrate.

[0038] Specifically, in this embodiment of the invention, by using aluminum strip 10 bonding instead of traditional aluminum wire bonding, the cross-sectional area of ​​the current path is significantly increased, effectively reducing contact resistance and Joule heating effect under high current conditions. Simultaneously, combined with the wide bandgap characteristics of the GaN chip, stable operation of the power module in high-temperature environments is achieved. The multi-layer thermal design of the heat dissipation substrate 5 and the metallized ceramic substrate, along with the distributed heat conduction path of the aluminum strip 10, significantly improves the module's thermal management capabilities. The sealed housing 9 structure, while ensuring electrical insulation, further reduces parasitic inductance through optimized power terminal layout. This allows the module to meet the requirements of high power density and miniaturization while possessing high-temperature reliability and excellent electrothermal performance, providing a new generation of power solutions for new energy vehicle electric drive systems and aerospace power equipment.

[0039] In a preferred embodiment of this utility model, the metallized ceramic substrate is a copper-clad ceramic substrate (DBC), whose size and total area are smaller than the heat dissipation substrate 5; the metallized ceramic substrate is provided with the following layers from bottom to top:

[0040] The back copper layer 8 is located on the lower surface of the ceramic layer. It is made of high-purity oxygen-free copper material. The thickness is optimized to ensure current carrying capacity while taking into account the high-frequency skin effect. It is connected to the heat dissipation substrate 5 through solder 4.

[0041] The ceramic layer, serving as a carrier for electrical isolation and heat conduction, is made of aluminum nitride (AlN) or aluminum oxide (Al2O3).

[0042] Emitter 3 is located on the upper surface of the ceramic layer, and an emitter copper layer 6 is provided on top of it, which is formed by precision etching to create an optimized current distribution network.

[0043] Specifically, in this embodiment of the invention, the metallized ceramic substrate adopts a multilayer composite structure design, and the packaging requirements of the high-performance power module are achieved through the synergistic optimization of material properties and process parameters. The back copper layer 8 is made of high-purity oxygen-free copper (OFC) material, and its thickness is optimized by thermo-electric coupling simulation to effectively suppress the skin effect under high-frequency conditions while ensuring high current carrying capacity. The surface of the copper layer is micro-roughened to enhance the wettability of the solder 4, and a reliable connection is achieved with the heat dissipation substrate 5 through active metal brazing process.

[0044] The ceramic layer serves as the core functional medium, using either AlN or Al2O3 materials. AlN, with its excellent thermal conductivity, is particularly suitable for high power density applications, while Al2O3 meets conventional requirements due to its mature processing technology and cost advantages. The ceramic layer forms a metallurgical bond with the upper and lower copper layers through a precisely controlled co-firing process. Its thickness and grain boundary structure are optimized to balance insulation strength and thermal resistance characteristics.

[0045] Emitter 3 and its top copper emitter layer 6 are formed using a precision photolithography etching process, creating an optimized three-dimensional current distribution network. This design not only reduces on-resistance but also improves high-frequency switching characteristics. The surface of the copper emitter layer 6 undergoes a controllable roughness treatment (Ra 0.5-1.0μm), providing ideal interface characteristics for subsequent aluminum strip 10 bonding.

[0046] This hierarchical design significantly reduces interfacial stress under temperature cycling conditions by matching the gradient of the material's thermal expansion coefficient. Combined with the edge buffer region formed by size optimization (substrate area smaller than the heat dissipation substrate by 5), it ensures the long-term reliability of the module under high-temperature and high-current operating conditions. The interface treatment process and thickness parameters between each layer have been rigorously verified by thermo-mechanical-electrical multiphysics simulation, achieving an optimal balance between electrical performance, thermal management, and mechanical reliability.

[0047] The copper-clad ceramic substrate (DBC) selected in this invention can form a sandwich structure by bonding copper foil to both sides of the ceramic layer (AlN or Al2O3), which retains the excellent insulation and thermal conductivity of ceramic and has the high conductivity of copper layer. This combination is particularly suitable for dealing with electrothermal coupling problems under high power density.

[0048] Furthermore, the smaller DBC size creates a buffer area at the edge of the heat sink substrate 5, avoiding edge stress concentration caused by differences in the coefficients of thermal expansion of the materials, and providing a safety margin for solder 4 to climb. This dimensional difference design also optimizes the heat flow path, allowing heat to be more evenly distributed throughout the heat sink substrate, while facilitating precise alignment during assembly and ensuring the integrity of the solder interface. The edge blank area further reduces the risk of interface fatigue caused by thermal cycling, significantly improving the long-term reliability of the module under extreme operating conditions.

[0049] In a preferred embodiment of the present invention, the gallium nitride chip 2 is made of a wide bandgap semiconductor material and is fixed to the emitter 3 by solder 4; and the anode of the gallium nitride chip 2 is bonded to the emitter copper layer 6 by the aluminum strip 10.

[0050] Specifically, in this embodiment of the invention, the wide bandgap (3.4 eV) of the gallium nitride chip 2 endows the chip with excellent high-temperature operating capability and high breakdown field strength (>3 MV / cm), making it particularly suitable for high power density applications. The chip is mechanically fixed and electrically connected to the emitter 3 via solder 4. The solder layer thickness is precisely controlled to ensure a good heat conduction path while mitigating interface stress caused by differences in thermal expansion coefficients. The chip anode and emitter copper layer 6 are bonded together using multi-layer aluminum strip 10. The aluminum strip 10 undergoes special annealing treatment to improve ductility, and its width and thickness are optimized according to current carrying requirements, forming a low-impedance, high-reliability current path. Compared to traditional aluminum wire bonding, this connection method has a larger contact area and better thermal diffusion performance, effectively reducing contact resistance and local temperature rise under high current conditions.

[0051] More specifically, the connection process between the anode and emitter copper layer 6 of the gallium nitride chip 2 can employ various advanced interconnect technologies. Besides aluminum strip bonding 10, thermocompression welding or low-temperature sintering can also be used. Thermocompression welding achieves solid-state diffusion bonding at the metal interface under controlled temperature and pressure conditions, forming a void-free, high-strength metallurgical bond. Low-temperature sintering, on the other hand, utilizes materials such as nano-silver paste to achieve high thermal conductivity bonding at temperatures lower than traditional brazing. Both processes significantly improve the thermomechanical reliability of the interface. In particular, the porous structure formed by sintering exhibits excellent resistance to thermal fatigue, while thermocompression welding allows for finer control of interconnect dimensions, enabling flexible selection of the optimal connection scheme based on different power levels and application scenarios. These advanced interconnect technologies, combined with the wide bandgap characteristics of the gallium nitride chip, jointly ensure the long-term stable operation of the power module under high switching frequencies and high current conditions.

[0052] In a preferred embodiment of this utility model, the solder 4 is a high-temperature solder 4, specifically a gold-tin (AuSn20) or silver-copper (AgCu28) eutectic alloy system.

[0053] Specifically, in this embodiment of the invention, gold-tin solder, with its excellent thermal conductivity (>50W / m·K) and high melting point (280℃), can maintain stable mechanical strength and electrical connection reliability in high-temperature operating environments; silver-copper solder, with its good wettability and high conductivity, provides a low thermal resistance connection interface for the power module. The solder layer achieves a controllable and uniform thickness distribution through precision screen printing or pre-formed solder sheet processes. Its reflow process is carried out in a vacuum or inert gas protected environment, effectively avoiding oxidation and ensuring the metallurgical quality of the interface. This choice of high-temperature solder 4 matches the wide bandgap characteristics of gallium nitride chips, enabling the power module to operate stably in high-temperature environments above 200℃. At the same time, through optimized solder 4 composition and process parameters, the risk of interface failure caused by differences in the thermal expansion coefficients of materials during thermal cycling is significantly reduced, providing a reliable packaging solution for high power density applications.

[0054] In a preferred embodiment of this utility model, the power terminal 1 is connected to the emitter copper layer 6 by an ultrasonic welding process, and the number of power terminals 1 matches the number of gallium nitride chips 2.

[0055] Specifically, in this embodiment of the invention, the power terminal 1 is made of highly conductive oxygen-free copper material and is connected to the emitter copper layer 6 with high strength through ultrasonic welding. This process utilizes high-frequency mechanical vibration to achieve solid-state bonding between metals at room temperature, avoiding the heat-affected zone problem of traditional welding, and is particularly suitable for temperature-sensitive wide bandgap semiconductor devices. The metallurgical interface generated by ultrasonic welding has extremely low contact resistance (<0.5mΩ), and no additional thermal stress is introduced during the welding process, perfectly maintaining the thermal matching between the gallium nitride chip 2 and the ceramic substrate. The number of power terminals 1 strictly corresponds to the layout of the gallium nitride chip 2, and a one-to-one connection method is used to ensure uniform current distribution. The cross-sectional area of ​​each terminal is optimized according to the maximum operating current of the chip. This connection scheme not only achieves low-loss power transmission of the module, but its repeatable welding quality also provides stable electrical performance and mechanical reliability for high-power applications, enabling the module to maintain excellent electrical characteristics under high-frequency switching and high-temperature conditions.

[0056] In a preferred embodiment of this utility model, the outer shell 9 is sealed to the heat dissipation substrate 5 by a sealant 7. The material of the outer shell 9 is high-temperature engineering plastic, and the sealant 7 is high-temperature resistant silicone or epoxy resin.

[0057] Specifically, the outer casing 9 is injection molded from special high-temperature engineering plastics (such as polyphenylene sulfide PPS or liquid crystal polymer LCP). These materials not only possess excellent temperature resistance (long-term operating temperature > 200℃) and dimensional stability, but also meet high-voltage insulation requirements. The sealant 7 uses high-temperature resistant silicone or modified epoxy resin, forming a continuous and uniform sealing layer at the interface between the heat dissipation substrate 5 and the outer casing 9 through a precision dispensing process. Silicone sealant, with its elastic properties, effectively absorbs stress generated by thermal cycling, while epoxy resin provides higher mechanical strength and chemical corrosion resistance. The sealing interface undergoes special surface treatment (such as plasma cleaning) to enhance adhesion strength, enabling the entire power module to meet the IP67 protection standard. This prevents the intrusion of external moisture and contaminants while withstanding internal temperature fluctuations and mechanical vibrations generated during power device operation, ensuring long-term reliable operation of the module in harsh environments.

[0058] In a preferred embodiment of the present invention, the heat dissipation substrate 5 is a copper-based or aluminum-based high thermal conductivity substrate, and its surface is provided with a microchannel heat dissipation structure.

[0059] Specifically, the heat dissipation substrate 5 is made of high-purity copper or aluminum alloy, and an optimized microchannel heat dissipation structure is constructed on its surface through precision machining. Copper substrates, with their excellent thermal conductivity (>400W / m·K), are particularly suitable for ultra-high power density applications, while aluminum substrates meet conventional requirements with their lighter weight and cost advantages. The microchannel structure adopts a biomimetic design, optimizing the channel width (0.3-0.5mm), depth (2-3mm), and distribution density through computational fluid dynamics (CFD) to maximize the heat dissipation surface area within a limited space. The high-efficiency heat pipes integrated inside the substrate work in conjunction with the microchannels to form a composite heat dissipation system, effectively reducing thermal resistance. The surface is anodized (aluminum-based) or nickel-plated (copper-based) to enhance corrosion resistance and improve the interfacial bonding strength with the solder 4. This heat dissipation design, combined with the heat conduction path of the metallized ceramic substrate, ensures that the chip junction temperature remains within a safe range when the power module is operating at full load, significantly improving system reliability and lifespan.

[0060] In summary, the power module of this utility model adopts a modular assembly design, and its typical implementation is as follows:

[0061] First, the gallium nitride chip 2 is precisely mounted onto the emitter 3 region of the DBC substrate using high-temperature solder 4, achieving mechanical fixation and electrical connection between the chip and the substrate. Then, using aluminum ribbon bonding 10, the anode of the chip is interconnected with the emitter copper layer 6 on the surface of the DBC substrate using a low-impedance bonding process, forming an efficient current path. The DBC substrate is then welded and fixed to a copper / aluminum substrate with a microchannel heat dissipation structure via a back copper layer 8, constructing a complete heat conduction path.

[0062] Next, to ensure the long-term reliability of the module, the engineering plastic shell 9 is hermetically sealed to the heat dissipation substrate 5 using high-temperature resistant sealant 7, and the internal power terminals 1 are connected to the DBC substrate using ultrasonic welding technology for high reliability. The DBC substrate is manufactured using advanced copper-clad ceramic technology, and by precisely controlling the thickness and interface characteristics of the ceramic and copper layers, the electrical insulation performance and thermal conductivity efficiency of the module are ensured under high power density operating conditions. This structural design not only achieves excellent heat dissipation performance but also effectively reduces thermomechanical stress through matching the thermal expansion coefficients of the materials, enabling the power module to adapt to harsh operating environments.

[0063] The above description is only a preferred embodiment of the present utility model and does not limit the implementation method and protection scope of the present utility model. Those skilled in the art should realize that all solutions obtained by equivalent substitutions and obvious changes made based on the description and illustrations of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A GaN high-temperature power module with aluminum strip bonding, characterized in that, include: A heat dissipation substrate, wherein a metallized ceramic substrate is attached to the surface of the heat dissipation substrate; A gallium nitride chip is fixed on the metallized ceramic substrate; An aluminum strip connects the gallium nitride chip and the metallized ceramic substrate; The outer casing is sealed to the heat dissipation substrate; A power terminal is disposed on the housing and connected to the metallized ceramic substrate.

2. The GaN high-temperature power module with aluminum strip bonding according to claim 1, characterized in that, The metallized ceramic substrate includes: The ceramic layer serves as a carrier for electrical isolation and heat conduction. A copper layer on the back side, located on the lower surface of the ceramic layer, is connected to the heat dissipation substrate by solder. The emitter is located on the upper surface of the ceramic layer, and a copper emitter layer is provided on top of it.

3. The GaN high-temperature power module with aluminum strip bonding according to claim 2, characterized in that, The gallium nitride chip is fixed to the emitter with solder.

4. The GaN high-temperature power module with aluminum strip bonding according to claim 3, characterized in that, The anode of the gallium nitride chip is bonded to the emitter copper layer via the aluminum strip.

5. A GaN high-temperature power module with aluminum strip bonding according to claim 2, characterized in that, The power terminal is connected to the emitter copper layer by an ultrasonic welding process.

6. A GaN high-temperature power module with aluminum strip bonding according to claim 5, characterized in that, The number of power terminals is matched with the number of gallium nitride chips.

7. A GaN high-temperature power module with aluminum strip bonding according to claim 1, characterized in that, The size and total area of ​​the metallized ceramic substrate are smaller than those of the heat dissipation substrate.

8. A GaN high-temperature power module with aluminum strip bonding according to claim 1, characterized in that, The metallized ceramic substrate is a copper-clad ceramic substrate.

9. A GaN high-temperature power module with aluminum strip bonding according to claim 1, characterized in that, The gallium nitride chip is a wide bandgap semiconductor material.

10. A GaN high-temperature power module with aluminum strip bonding according to claim 1, characterized in that, The outer casing is sealed to the heat dissipation substrate by sealant.

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