A heat dissipation package structure for high power density IGBT module

Abstract

This invention relates to the field of heat dissipation packaging technology for power semiconductor devices, specifically a heat dissipation packaging structure for high power density IGBT modules. The structure includes an IGBT module, a module substrate fixed to the IGBT module, a capillary layer I on the heat dissipation contact surface of the module substrate, a phase change material layer between the module substrate and a heat dissipation device, and a second capillary layer opposite to the first capillary layer in the heat dissipation device. It also includes a micro heating element linked to a controller, a heat sink conversion chamber with a liquid flow channel, and an interface sealing structure. This invention can constrain the liquid phase change material to adaptively fill the microscopic gaps at the interface through capillary structure, significantly reducing interface thermal resistance and preventing material leakage. Preheating eliminates chip temperature spikes during startup, significantly improving module heat dissipation efficiency, power cycle life, and reliability under all operating conditions, thus meeting the stringent heat dissipation requirements of high power density IGBT modules.

Description

Technical Field

[0001] This invention relates to the field of heat dissipation packaging technology for power semiconductor devices, specifically a heat dissipation packaging structure for high power density IGBT modules. Background Technology

[0002] With the rapid development of power electronics technology, high power density IGBT modules, as core devices for power conversion and control, have been widely used in key fields such as new energy vehicles, industrial transmission, rail transit and smart grids. As the integration and power density of modules continue to increase, the high heat flux density generated during chip operation places increasingly stringent requirements on the thermal conductivity, operational stability and long-term reliability of heat dissipation packaging structures.

[0003] Existing heat dissipation packaging structures for high-power-density IGBT modules suffer from insufficient overall performance of the thermal interface. They cannot simultaneously achieve ultra-low interface thermal resistance, long-term leak-free stable operation, and adaptability to thermal management under all operating conditions. Conventional thermal interface materials have high interface thermal resistance and suffer severe performance degradation under long-term thermal cycling. Phase change thermal interface materials cannot effectively constrain liquid phase change materials, and are prone to material leakage and insufficient filling of micro-voids at the interface. These shortcomings make it difficult to meet the ever-increasing heat dissipation requirements of high-power-density IGBT modules, severely limiting the upper limit of the module's power density and long-term operational reliability. Therefore, it is urgent to develop a heat dissipation packaging structure for high-power-density IGBT modules to overcome the deficiencies in current practical applications. Summary of the Invention

[0004] The purpose of this invention is to provide a heat dissipation packaging structure for high power density IGBT modules to solve the problems mentioned in the background art.

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

[0006] A heat dissipation packaging structure for a high power density IGBT module includes an IGBT module, a module substrate fixedly mounted on the IGBT module, and a heat dissipation device detachably mounted on the module substrate.

[0007] The bottom of the module substrate is provided with a heat dissipation contact surface, and a capillary structure layer is provided on the heat dissipation contact surface.

[0008] A phase change material layer is placed between the module substrate and the heat dissipation device, and the phase change material layer is attached to the area directly opposite the first capillary structure layer.

[0009] When the IGBT module generates high heat, causing the phase change material layer to change from solid to liquid, the capillary structure layer is used to constrain the liquid phase change material and guide it to adaptively fill the microscopic contact gaps, thereby achieving a continuous reduction in interface thermal resistance and stable operation without leakage.

[0010] As a further aspect of the present invention: the module substrate is a metal base plate structure, preferably copper or aluminum silicon carbide;

[0011] The IGBT module and the heat dissipation device are connected by a fastening connection structure.

[0012] As a further aspect of the present invention: the heat dissipation device is provided with a second capillary structure layer, the second capillary structure layer having the same structure as the first capillary structure layer, and being disposed opposite each other;

[0013] The phase change material layer is filled within the first and second capillary structures, and is solid at room temperature and liquid at operating temperature.

[0014] As a further aspect of the present invention: the phase change material layer adopts a low melting point alloy preformed sheet, the material being a Bi-In-Sn eutectic alloy or a Ga-In-Sn alloy, and the sheet thickness being 100-300 μm.

[0015] As a further aspect of the present invention: the first capillary structure layer adopts a microgroove array, the microgrooves are parallel or grid-like, the groove depth is 50-150μm, the width is 50-100μm, and the groove spacing is 100-300μm;

[0016] Furthermore, the surface of the trench is plated with nickel or gold.

[0017] As a further aspect of the present invention: the heat dissipation device includes:

[0018] A heat sink conversion compartment, which is detachably connected to the IGBT module;

[0019] The heat sink conversion compartment is provided with a cold plate at its top, the capillary layer is disposed on the cold plate, and the module substrate is located between the IGBT module and the cold plate.

[0020] It also includes a coolant inlet and a coolant outlet, which are located at opposite ends of the radiator conversion chamber for coolant to enter and exit the radiator conversion chamber.

[0021] As a further aspect of the present invention, it also includes: a heat-conducting plate, wherein there are multiple heat-conducting plates, and the multiple heat-conducting plates are uniformly and fixedly installed on the cold plate and located inside the radiator conversion chamber;

[0022] The multiple heat-conducting plates are arranged in parallel, dividing the heat sink conversion chamber into multiple liquid flow channels.

[0023] As a further aspect of the present invention, it also includes: a second interface sealing groove, wherein the second interface sealing groove is formed on the cold plate;

[0024] Interface sealing groove one is formed on the heat dissipation contact surface. Interface sealing groove one has the same structure as interface sealing groove two and is positioned opposite to interface sealing groove two.

[0025] A metal C-shaped sealing ring is provided between the interface sealing groove one and the interface sealing groove two, forming a closed cavity after compression.

[0026] As a further aspect of the present invention, it also includes: a controller, which is fixedly mounted on the IGBT module and is signal-connected to the heat dissipation device;

[0027] A miniature heating element is disposed on the heat dissipation contact surface and is signal-connected to the controller.

[0028] The controller is used to actively activate the micro heating element to preheat the phase change material layer when the IGBT module starts up or the power jumps and the chip has not yet generated a lot of heat, so as to melt it in advance, thereby eliminating the thermal response lag and instantaneous temperature spike of the chip during the startup phase.

[0029] As a further aspect of the present invention: the micro heating element adopts an embedded resistance heating wire, and a serpentine resistance wire is made on the lower surface of the module substrate by thick film printing or electroplating process. The material is NiCr or Pt, and the thickness is 10-30μm.

[0030] The resistance wire surface is covered with an electrically insulating and thermally conductive thin film, which is electrically isolated from the phase change material layer.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] By melting and liquefying the phase change material layer at the operating temperature, and guided by the capillary forces of capillary structure layer one and capillary structure layer two, it can adaptively fill the microscopic contact gaps between the module substrate and the cold plate, completely eliminating interfacial air gaps and reducing the interfacial contact thermal resistance from 50-100 mmHg compared to traditional thermal grease. 2 • K / W reduced to 5-15mm 2• K / W, with a reduction of over 80%; at the same time, the molten phase change material can form a flexible thermal interface, effectively absorbing the shear stress caused by the mismatch of thermal expansion coefficients between the IGBT module, the module substrate and the heat dissipation equipment, avoiding fatigue cracking of the solder layer during power cycling, and significantly improving thermal conductivity and module life.

[0033] The capillary structure layer formed by the microgroove array can strongly constrain and guide the liquid phase change material, avoiding uneven distribution and leakage of the material under gravity, vibration or thermal cycling. Combined with the closed cavity formed by the interface sealing groove one and interface sealing groove two that are set opposite each other and pressed with the metal C-type sealing ring, it can form a secondary sealing protection for the phase change material, completely eliminating the risk of leakage and providing excellent long-term operational stability.

[0034] Through the coordinated control of the controller and the micro heating element, the phase change material layer can be preheated to melt it in advance when the IGBT module starts up or the power surges and the chip has not yet generated a large amount of heat. This allows the interface to enter an ultra-low thermal resistance state before the chip heats up, controlling the instantaneous temperature fluctuation of the module during startup to within 5°C, and reducing the chip startup peak temperature by 21.3%.

[0035] Multiple independent liquid flow channels are formed by parallel heat-conducting plates arranged within the radiator conversion chamber, enabling full convective heat exchange between the coolant and the heat-conducting plates. Differential zoning design can also be implemented according to the internal chip layout of the IGBT module, achieving precise heat dissipation. The structure extending the heat-conducting plates to the outside of the radiator conversion chamber forms a combined liquid cooling and air cooling mode, improving heat dissipation redundancy under extreme high-temperature conditions. It can also serve as an emergency cooling measure in case of liquid cooling system failure, extending the module's emergency operating time. Combined with the controller's dynamic closed-loop regulation of coolant flow, auxiliary energy consumption of the cooling system can be reduced by up to 20% or more while ensuring heat dissipation performance.

[0036] The phase change material layer, which is solid at room temperature, adopts a pre-formed sheet design, which can greatly simplify the assembly process of modules and heat dissipation equipment. Uniform pressing can be achieved through a diagonal step-locking fastening connection structure, ensuring batch consistency of interface performance. The controller has built-in multi-mode control logic and self-diagnostic health monitoring functions, which can realize intelligent thermal management under all operating conditions such as standby, start-up, steady state, overload and shutdown. It can also repair the micro gaps at the interface through full-power remelting heating, realizing interface self-repair. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the overall structure of the heat dissipation packaging structure for a high power density IGBT module in an embodiment of the present invention.

[0038] Figure 2 This is a schematic diagram of the installation location of the controller in an embodiment of the present invention.

[0039] Figure 3 This is a three-dimensional structural diagram of the IGBT module in an embodiment of the present invention.

[0040] Figure 4 This is a schematic diagram of the installation location of the phase change material layer in an embodiment of the present invention.

[0041] Figure 5 This is a schematic diagram of the installation position of the first capillary layer in an embodiment of the present invention.

[0042] Figure 6 This is a three-dimensional structural diagram of the radiator conversion compartment in an embodiment of the present invention.

[0043] Figure 7 This is a schematic diagram of the distribution structure of the heat-conducting plate in an embodiment of the present invention.

[0044] Figure 8 This is a schematic diagram of the distribution structure of the fluid flow channels in an embodiment of the present invention.

[0045] Figure 9 This is a partial structural diagram of the micro heating element in an embodiment of the present invention.

[0046] In the diagram: 1-IGBT module, 2-module substrate, 3-heat sink conversion chamber, 4-coolant inlet, 5-fastening connection structure, 6-coolant outlet, 7-heat conduction plate, 8-controller, 9-phase change material layer, 10-interface sealing groove one, 11-heat dissipation contact surface, 12-capillary structure layer one, 13-capillary structure layer two, 14-interface sealing groove two, 15-cold plate, 16-fluid flow channel, 17-micro heating element. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0049] Please see Figures 1-9The present invention provides a heat dissipation packaging structure for a high power density IGBT module, including an IGBT module 1, a module substrate 2 fixedly mounted on the IGBT module 1, an IGBT chip and a freewheeling diode chip integrated inside the IGBT module 1, the chip being sintered onto a DBC substrate through a solder layer, and the DBC substrate being fixed onto the module substrate 2 through a vacuum brazing process to form a complete power module body, and a heat dissipation device being detachably mounted on the module substrate 2;

[0050] The bottom of the module substrate 2 is provided with a heat dissipation contact surface 11, and a capillary structure layer 12 is provided on the heat dissipation contact surface 11.

[0051] A phase change material layer 9 is also placed between the module substrate 2 and the heat dissipation device, and the phase change material layer 9 is attached to the area directly opposite the capillary structure layer 12.

[0052] When the IGBT module 1 generates high heat, causing the phase change material layer 9 to change from solid to liquid, the capillary structure layer 12 is used to constrain the liquid phase change material and guide it to adaptively fill the micro-contact gaps, thereby achieving a continuous reduction in interface thermal resistance and stable operation without leakage.

[0053] Please see Figures 1-9 The module substrate 2 is a metal base plate structure, preferably copper or aluminum silicon carbide; the thickness of the module substrate 2 is preferably 3-5mm. When copper is used, the surface needs to be nickel-plated for anti-oxidation treatment; when aluminum silicon carbide is used, its coefficient of thermal expansion is preferably 6-8ppm / K, which is more compatible with the coefficient of thermal expansion of silicon chips and can further reduce the thermomechanical stress inside the module.

[0054] The IGBT module 1 and the heat dissipation device are connected by a fastening connection structure 5, wherein the fastening connection structure 5 adopts a structure in which the lug plate and the bolt are locked together. The lug plate of the fastening connection structure 5 is integrally injection molded with the shell of the IGBT module 1 and the shell of the heat dissipation device. The lug plate has bolt through holes with a diameter of 6-8mm, and 8.8 grade high-strength internal hex bolts are used. The locking torque is preferably 5-10N·m. During assembly, a diagonal step-by-step locking process is adopted to ensure uniform distribution of interface pressure.

[0055] The heat dissipation device is provided with a second capillary structure layer 13, which has the same structure as the first capillary structure layer 12 and is arranged opposite to each other. The first capillary structure layer 12 and the second capillary structure layer 13 can also be arranged in a staggered manner, that is, the microgrooves on the module substrate 2 and the microgrooves on the cold plate 15 are staggered in the vertical direction, and the offset of the center line of the groove is 1 / 2 of the groove spacing. The opposite arrangement is suitable for mating interfaces with high flatness, while the staggered arrangement is suitable for interfaces with slight flatness deviation. It can form a three-dimensional staggered capillary network, further improve the lateral spreading ability of the liquid phase change material, avoid local void residue, and enhance the shear force buffering effect between the two interfaces, further reducing the stress damage caused by thermal expansion mismatch.

[0056] The phase change material layer 9 is filled within the capillary structure layer 12 and the capillary structure layer 13. It is solid at room temperature and liquid at operating temperature.

[0057] The phase change material layer 9 is made of a low-melting-point alloy preformed sheet, the material being a Bi-In-Sn eutectic alloy or a Ga-In-Sn alloy, with a sheet thickness of 100–300 μm; when using a Bi-In-Sn eutectic alloy, the preferred grade is Bi-35In-32Sn, with a melting point of 62±2℃, a thermal conductivity of 40–60 W / m・K, and a sheet thickness preferably of 150 μm; when using a Ga-In-Sn alloy, the preferred grade is Ga-14In-8Sn. The alloy has a melting point of 48±2℃ and a thermal conductivity of 60~80W / m・K. The thickness of the sheet is preferably 200μm. The size of the pre-formed sheet matches the size of the heat dissipation contact surface 11 of the module substrate 2, with a clearance of 0.5~1mm around it to avoid interference with the sealing structure. The surface of the sheet can be pre-imprinted with raised textures that match the microgrooves of the capillary layer 12 to improve the positioning accuracy and initial contact area during assembly. This low-melting-point alloy has excellent oxidation resistance in both solid and liquid states, and its volume shrinkage rate is less than 3% during long-term thermal cycling, which can ensure the long-term stability of the interface contact.

[0058] The capillary structure layer 12 adopts a microgroove array. The microgrooves are parallel or grid-like, with a groove depth of 50-150 μm, a width of 50-100 μm, and a groove spacing of 100-300 μm.

[0059] Furthermore, the trench surface is plated with nickel or gold; the micro-groove array is processed by precision mechanical milling, laser etching or wet etching processes, and the surface roughness Ra≤0.8μm after processing can further improve the capillary flow performance of liquid phase change materials; when a grid-like micro-groove is used, a liquid storage pit with a diameter of 1.5 times the width of the trench is set at the intersection of the trenches, which can store a small amount of phase change material and replenish the material lost due to trace volatilization during long-term hot and cold cycles, further extending the effective service life of the interface.

[0060] In this embodiment, through the above structural design, when the IGBT module 1 is working normally, the heat generated by the chip is transferred to the module substrate 2 via the solder layer and the DBC substrate. The module substrate 2 is made of copper or aluminum silicon carbide with high thermal conductivity, which can achieve rapid lateral temperature uniformity and longitudinal heat transfer, avoiding local hot spot concentration. When the module operating temperature rises to the melting point of the phase change material layer 9, the pre-formed thin-film phase change material layer 9, made of Bi-In-Sn eutectic alloy or Ga-In-Sn alloy, changes from solid to liquid. At this time, the capillary force generated by the micro-groove array of the directly opposite capillary structure layer 12 and capillary structure layer 13 forms a bidirectional constraint and guiding effect on the liquid phase change material. On the one hand, it can guide the molten liquid phase change material to flow spontaneously under the action of capillary force, completely filling the micro-uneven gaps between the heat dissipation contact surface 11 and the cold plate 15 of the module substrate 2 caused by mechanical processing, completely eliminating the air gap at the interface, and reducing the interface contact thermal resistance from 50-100 mm in traditional thermal grease. 2 • K / W reduced to 5-15mm 2 • K / W significantly improves the interface thermal conductivity. On the other hand, the micro-groove array can firmly confine the liquid phase change material within the trench network, avoiding uneven distribution and leakage during gravity, equipment vibration, or thermal cycling. Meanwhile, the nickel or gold plating on the trench surface can prevent the low-melting-point alloy from corroding the base metal and improve the wettability of the liquid phase change material on the trench surface, further enhancing the capillary filling effect and the stability of interface thermal conduction. The pre-formed thin sheet of phase change material layer 9, which is solid at room temperature, can greatly simplify the assembly process of the module and the heat dissipation equipment. Unlike liquid thermal conductive materials, it does not require controlling the coating thickness and uniformity. By fastening the ear plate and bolts of the fastening connection structure 5, uniform pressing of the two mating interfaces can be achieved. At the same time, the molten liquid phase change material can form a flexible thermal conductive interface, effectively absorbing the shear stress caused by the mismatch of thermal expansion coefficients between the IGBT module 1, the module substrate 2, and the heat dissipation equipment, avoiding fatigue cracking of the solder layer during power cycling, and improving the power cycle life and long-term operational reliability of the module.

[0061] The fastening connection structure 5 with diagonal step-locking can ensure that the pressing force between the module substrate 2 and the cold plate 15 is evenly distributed and the flatness deviation is controlled within 5μm, avoiding the problem of uneven local compression of the phase change material layer 9. At the same time, the final compression thickness of the interface can be precisely controlled by torque control to ensure batch consistency of interface thermal resistance.

[0062] When capillary layer 12 and capillary layer 13 are staggered, the interlaced trench network allows the liquid phase change material to form a continuous thermal bridge in the direction perpendicular to the interface, further reducing the longitudinal thermal resistance of the interface. At the same time, when there is a small relative displacement at the interface, the flow of the liquid material can adaptively compensate, avoiding contact failure. The aluminum silicon carbide module substrate 2 has a thermal expansion coefficient that is more compatible with the ceramic layer of the silicon chip and DBC substrate. This can significantly reduce the residual stress generated during the cooling of the module from the soldering temperature to room temperature, and at the same time reduce the thermal cycling stress caused by temperature fluctuations during operation, increasing the power cycle life of the module from 50,000 cycles in the traditional copper substrate solution to more than 200,000 cycles.

[0063] In one embodiment of the present invention, please refer to Figures 1-9 The heat dissipation device includes:

[0064] The heat sink conversion compartment 3 is detachably connected to the IGBT module 1.

[0065] The top of the heat sink conversion chamber 3 is provided with a cold plate 15, the capillary structure layer 2 13 is provided on the cold plate 15, and the module substrate 2 is located between the IGBT module 1 and the cold plate 15.

[0066] And a coolant inlet 4 and a coolant outlet 6, the coolant inlet 4 and the coolant outlet 6 being located at opposite ends of the radiator conversion chamber 3, for coolant to enter and exit the radiator conversion chamber 3;

[0067] The radiator conversion chamber 3 and the cold plate 15 are integrally brazed from 6061 aluminum alloy or welded from stainless steel. The chamber wall thickness is 1.5-2mm, and the rated pressure bearing capacity is not less than 1MPa, which is suitable for the normal working pressure of automotive liquid cooling systems. The thickness of the cold plate 15 is 2-3mm, and the welding surface with the radiator conversion chamber 3 adopts a bevel welding process to ensure the welding seal and prevent coolant leakage. The coolant inlet 4 and the coolant outlet 6 adopt an external thread pipe joint structure. The thread specification is preferably G1 / 4 or M12×1.5. The inner wall of the joint is provided with a flow guide slope to reduce the flow resistance of coolant when entering and exiting the chamber.

[0068] It also includes: a heat-conducting plate 7, wherein there are multiple heat-conducting plates 7, which are uniformly fixedly installed on the cold plate 15 and located inside the radiator conversion chamber 3;

[0069] The multiple heat-conducting plates 7 are arranged in parallel and divide the heat sink conversion chamber 3 into multiple liquid flow channels 16 for the coolant to flow in separate zones.

[0070] The heat-conducting plate 7 extends from one end of the cold plate 15 to the bottom of the radiator conversion chamber 3. This allows for further cooling during high-heat operation via air cooling (optional).

[0071] The heat-conducting plate 7 and the cold plate 15 are integrally formed using a molding process, and the material is the same as that of the cold plate 15, avoiding contact thermal resistance caused by welding different materials. The thickness of the heat-conducting plate 7 is 0.8-1.2mm, the height is 8-12mm, and the spacing between adjacent heat-conducting plates 7 is 3-5mm. The width-to-height ratio of the liquid flow channel 16 is preferably 1:3, which can maximize the heat exchange area while ensuring low flow resistance. The liquid flow channel 16 can be designed differently according to the chip layout inside the IGBT module 1. For areas corresponding to high-heat-generating chips, the spacing of the heat-conducting plates 7 can be reduced and the number of heat-conducting plates 7 can be increased to improve the coolant flow rate and heat exchange area in that area, achieve precise heat dissipation in zones, avoid the problem of excessive temperature difference inside the module, and improve the current balance and long-term reliability of multi-chip parallel operation. The length of the heat-conducting plate 7 extending to the outside of the heat sink conversion chamber 3 is 10-15mm. Parallel heat dissipation teeth can be set on the surface of the extension section. The thickness of the heat dissipation teeth is 0.5mm and the spacing is 1mm, which further improves the air-cooled heat exchange area.

[0072] It also includes: interface sealing groove 2 14, which is formed on the cold plate 15;

[0073] Interface sealing groove 10 is formed on the heat dissipation contact surface 11. Interface sealing groove 10 has the same structure as interface sealing groove 2 14 and is positioned opposite to interface sealing groove 2 14.

[0074] A metal C-shaped sealing ring is provided between the interface sealing groove 10 and the interface sealing groove 14, forming a closed cavity after compression.

[0075] The groove depth of interface sealing groove 10 and interface sealing groove 2 is 0.6-0.8mm, and the groove width is 1.5-2mm. The metal C-type sealing ring is made of 304 stainless steel or Invar, with a ring body cross-sectional diameter of 0.8-1mm, a height of 1.2-1.5mm in the free state, and a compression amount of 30%-40% after compression, which is within the optimal elastic compression range of the metal sealing ring, ensuring that the sealing performance does not decrease during long-term hot and cold cycles. A buffer gap of 0.1-0.3mm is reserved between the inner side of the sealing ring and the outer side of the capillary structure, preferably 0.2mm.

[0076] Through the above structural design, during the operation of the module, the heat transferred to the cold plate 15 via the phase change heat conduction interface can be quickly transferred to the liquid flow channel 16 inside the radiator conversion chamber 3 through multiple parallel heat conduction plates 7 evenly arranged on the cold plate 15. After the coolant enters from the coolant inlet 4 at one end of the radiator conversion chamber 3, it is divided into multiple independent liquid flow channels 16 by multiple sets of parallel heat conduction plates 7 for zoned flow guidance, realizing sufficient convective heat exchange between the coolant and the heat conduction plates 7, quickly carrying away the heat on the cold plate 15 and discharging it through the coolant outlet 6. At the same time, the end of the heat conduction plate 7 away from the cold plate 15 extends to the bottom outside of the radiator conversion chamber 3. When the module is under extreme high heat load conditions, it can form a liquid cooling + air cooling composite heat dissipation mode in conjunction with the external air cooling structure, further improving the heat dissipation redundancy capacity.

[0077] The interface sealing groove 10 and interface sealing groove 2 14, which are positioned opposite each other, form a fully enclosed cavity surrounding the phase change interface by pressing the metal C-shaped sealing ring during assembly. On the one hand, this provides secondary protection for the liquid phase change material after being constrained by the capillary structure, completely eliminating the risk of leakage. On the other hand, it forms a reserved buffer gap between the inner side of the sealing ring and the capillary structure to accommodate the volume expansion and contraction of the liquid phase change material due to temperature changes, avoiding fluctuations in interface compressive stress caused by volume changes during thermal cycling. At the same time, this sealing structure can completely isolate the coolant from the phase change heat conduction interface, preventing coolant leakage into the heat conduction interface and causing phase change material contamination and failure of thermal conductivity, thus ensuring the sealing and stability of the heat dissipation system during long-term operation.

[0078] The controller 8 can also dynamically adjust the input flow rate and velocity of the coolant based on the chip junction temperature or interface temperature signal detected by the temperature sensor. Under the premise of ensuring that the chip junction temperature does not exceed the safety threshold, it can achieve heat dissipation on demand, reduce the auxiliary energy consumption of the cooling water pump, and improve the energy utilization efficiency of the system. The interface sealing groove 10 and interface sealing groove 2 14 set opposite to each other can also play a pre-positioning role in the assembly process. During assembly, the C-type sealing ring can be embedded in the groove first, and then the module substrate 2 and the cold plate 15 can be aligned to avoid assembly misalignment between the two interfaces, ensure the alignment accuracy of the capillary structure and the phase change material layer 9, and at the same time, the compression amount of the C-type sealing ring can be precisely controlled to ensure batch consistency of sealing performance.

[0079] The buffer gap inside the sealing ring, in addition to accommodating the volume expansion and contraction of the phase change material, can also accommodate excess liquid phase change material squeezed out during assembly, preventing the phase change material from overflowing to the sealing ring and affecting the sealing performance. At the same time, it can form an annular liquid storage cavity, which can replenish the interface area through capillary force when there is a local material loss at the interface, realizing the self-repair of the interface. The integrated heat-conducting plate 7 and cold plate 15 structure eliminates the contact thermal resistance between the traditional split fins and cold plate 15, which can increase the equivalent thermal conductivity of the cold plate 15 by more than 20%. The air-cooling function of the extension section of the heat-conducting plate 7 can be used as an emergency heat dissipation means when the liquid cooling system fails, extending the emergency operation time of the module by 3 to 5 times, providing sufficient time for the safe shutdown of the system, and greatly improving the fault redundancy capability of the system.

[0080] In one embodiment of the present invention, please refer to Figures 1-9 It also includes: a controller 8, which is fixedly installed on the IGBT module 1 and is signal-connected to the heat dissipation device;

[0081] A miniature heating element 17 is disposed on the heat dissipation contact surface 11 and is signal-connected to the controller 8;

[0082] The controller 8 is used to actively activate the micro heating element 17 to preheat the phase change material layer 9 when the IGBT module 1 starts up or the power jumps and the chip has not yet generated a lot of heat, so as to melt it in advance, thereby eliminating the thermal response lag and instantaneous temperature spike of the chip during the start-up phase.

[0083] The controller 8 uses a 32-bit automotive-grade MCU, preferably the STM32G031K8T6, which is integrated on the driver circuit board of the IGBT module 1, or can be a separate control board that is fixed to the side of the housing of the IGBT module 1 with screws. The power supply voltage of the controller 8 is 12V / 24V, which is compatible with automotive and industrial power supply systems.

[0084] The signal input terminal of the controller 8 is electrically connected to the drive circuit of the IGBT module 1, the vehicle VCU / industrial controller, and the built-in temperature sensor, and the signal output terminal is electrically connected to the drive circuit of the micro heating element 17 and the coolant flow regulation actuator (electronic proportional valve / variable frequency water pump).

[0085] The driving circuit of the miniature heating element 17 adopts MOSFET switching control, supports PWM speed regulation, and can realize continuous adjustment of heating power with an adjustment range of 0-20W. The IGBT module 1 also has an embedded NTC thermistor or thermocouple temperature sensor. The sensor is installed on the ceramic layer of the DBC substrate, close to the soldering position of the IGBT chip, and can collect the junction temperature analog signal of the chip in real time with a sampling frequency of not less than 100Hz, providing the core basis for the closed-loop control of the controller 8. An additional temperature sensor can also be set at the interface edge. The sensor is embedded in the trench of the capillary structure layer and directly contacts the phase change material layer 9 to collect interface temperature data in real time with a sampling frequency of not less than 50Hz.

[0086] The micro heating element 17 adopts an embedded resistance heating wire. The serpentine resistance wire is made on the lower surface of the module substrate 2 by thick film printing or electroplating process. The material is NiCr or Pt and the thickness is 10-30μm.

[0087] The serpentine resistance heating wire has a linewidth of 40–60 μm and a spacing of 200–300 μm between adjacent heating wires. The overall coverage area perfectly matches the layout area of ​​the phase change material layer 9, ensuring heating uniformity. When NiCr material is used, the temperature coefficient of resistance is less than ±100 ppm / ℃, and the heating power stability is high. The preferred total resistance value is 7.2 Ω, and the rated heating power is 20 W under 12V power supply. It can be adjusted to the operating power range of 5–20 W via PWM. When Pt material is used, the temperature coefficient of resistance is 3850 ppm / ℃, which can simultaneously perform heating and temperature sensing functions. It can acquire interface temperature data in real time without the need for additional interface temperature sensors, simplifying the structure while improving the response speed and accuracy of temperature monitoring, and further optimizing the closed-loop control accuracy.

[0088] The surface of the resistance wire is covered with an electrically insulating and thermally conductive thin film, which is electrically isolated from the phase change material layer 9.

[0089] The electrically insulating and thermally conductive thin film covering the surface of the resistance wire is preferably an Al2O3 ceramic thin film with a thickness of 5-8 μm, deposited by magnetron sputtering. The breakdown voltage is not less than 500V and the thermal conductivity is not less than 25W / m・K. This ensures excellent electrical insulation performance while achieving efficient heat transfer and avoiding heat loss. The surface of the film needs to be passivated to prevent penetration corrosion by low-melting-point alloys. The two ends of the resistance wire are led out as electrodes through metallized vias on the side of the module substrate 2. The electrodes are gold-plated and electrically connected to the drive circuit of the controller 8 through high-temperature resistant wires. The connection resistance is less than 0.1Ω to ensure stable output of heating power.

[0090] Existing passive phase change thermal interfaces generally suffer from a core defect: delayed thermal response during startup. When IGBT module 1 starts up or experiences a power surge, the phase change material melts due to the chip's own heating, resulting in instantaneous temperature spikes that far exceed the rated junction temperature by 10–30°C. This severely accelerates chip aging and can even prevent normal melting at temperatures as low as -40°C. This embodiment, through the aforementioned structural design and a controller 8 linked to the IGBT module 1 drive circuit, enables active intelligent control of the phase change thermal interface under all operating conditions. The controller 8 has built-in complete control logic and operating modes, as detailed below:

[0091] Standby / Cold Mode: When the IGBT module 1 is not powered on or is in a low-power standby state, and the chip junction temperature is more than 20°C below the melting point of the phase change material layer 9, the controller 8 turns off the output of the micro heating element 17, and the phase change material layer 9 remains solid. At this time, the module generates very little heat and there is no risk of overheating. At the same time, the controller 8 controls the coolant flow regulation actuator to maintain the minimum flow or stop the machine, reducing auxiliary energy consumption.

[0092] Start preheating mode: When the controller 8 receives the drive enable signal of the IGBT module 1, the vehicle start command or the load jump prediction signal, it immediately executes the preheating process: before the power switch of the IGBT chip is activated, the rated heating power (preferably 10-15W) is output to the micro heating element 17 1-2 seconds in advance, and the phase change material layer 9 is heated from the ambient temperature to above the melting point within 0.5-3 seconds, so that it is completely melted into a liquid state and fills the micro gaps at the interface under the action of capillary force;

[0093] After the controller 8 confirms that the phase change material has completely melted by the resistance change of the Pt heating wire or the signal of the interface temperature sensor, it delays for 0.2 to 0.5 seconds before sending an enable signal to the IGBT drive circuit to allow the main power circuit of the module to start operation.

[0094] This mode is equipped with hardware interlock logic, meaning that the IGBT drive circuit can only receive the enable signal after the preheating completion signal is triggered. This completely avoids the module operating at high power before the phase change material has completely melted, eliminating the risk of chip overheating during the startup phase from a hardware perspective. The micro-gaps are filled before the chip starts to generate a lot of heat, allowing the interface to enter an ultra-low thermal resistance state in advance, completely eliminating the chip temperature spike during the module startup phase, and controlling the instantaneous temperature fluctuation during startup to within 5°C. At the same time, the electrically insulating and thermally conductive film covering the surface of the resistance wire can ensure efficient heat transfer while achieving reliable electrical isolation between the heating wire and the liquid phase change material, avoiding the risk of short circuits.

[0095] Steady-state operation mode: When IGBT module 1 is working normally and continuously, and the chip junction temperature is stable in the range of 5-20°C above the melting point of phase change material layer 9, controller 8 turns off micro heating element 17. The phase change material is maintained in a molten state by relying on the heat flow generated by the chip itself. The capillary structure layer maintains a uniform distribution of liquid material, and the interface thermal resistance is always at the lowest level. If the interface temperature drops to 2°C below the melting point due to extremely low ambient temperature or excessive heat dissipation, controller 8 intermittently activates the heating element for heat replenishment. Heat replenishment uses a PWM signal with a duty cycle of 5-10% to maintain the interface temperature above the melting point and ensure stable interface thermal resistance.

[0096] Overload emergency cooling mode: When the temperature sensor detects that the chip junction temperature exceeds the first threshold (preferably 150°C), the controller 8 forces the micro heating element 17 to work continuously at maximum power (20W). By increasing the interface temperature, the viscosity of the liquid phase change material is reduced, the interface wettability is enhanced, and the interface thermal resistance is further reduced. At the same time, a full-power operation command is sent to the coolant flow regulating actuator to increase the coolant flow to the maximum value. Simultaneously, a power reduction request is sent to the system controller to provide additional thermal management margin and delay the triggering of over-temperature protection. When the chip junction temperature exceeds the second threshold (preferably 175°C), the controller 8 directly triggers the module over-temperature protection shutdown to avoid permanent damage to the chip.

[0097] Shutdown cooling mode: When IGBT module 1 stops working and the main power circuit is disconnected, controller 8 immediately shuts down the micro heating element 17. The phase change material solidifies naturally as the interface temperature drops. Due to the constraint of the capillary structure, the material solidifies in situ without generating shrinkage gaps, preparing for the next startup. At the same time, controller 8 gradually reduces the coolant flow rate according to the chip junction temperature drop curve until the junction temperature drops to a safe threshold and then shuts down the cooling system.

[0098] Self-diagnosis and health monitoring mode: The controller 8 can periodically perform a self-diagnosis process. By inputting a short-time small current pulse to the micro heating element 17, it measures the resistance change of the heating wire and indirectly judges the melting state of the phase change material and whether there are voids, aging or other problems at the interface. When an abnormal increase in interface thermal resistance is detected, the controller 8 can perform a full-power remelting heating to repair the micro gaps generated during long-term operation and achieve self-repair of the interface. At the same time, it sends an early warning signal to the system controller to achieve predictive maintenance. Even if the heating element fails, this structure can still degenerate into a passive phase change thermal interface, and its performance is still better than that of traditional thermal grease solutions. It has extremely high operational redundancy and reliability.

[0099] The controller 8 employs closed-loop control logic for the dynamic adjustment of coolant flow rate. Specifically, the controller 8 uses the chip junction temperature, interface temperature, and output power of the IGBT module 1 as input parameters. It calculates the target coolant flow rate using a PID algorithm and sends corresponding control signals to the electronic proportional valve or variable frequency water pump to adjust the coolant flow rate and velocity in real time. When the module output power increases or the chip junction temperature rises, the coolant flow rate is increased synchronously to enhance heat dissipation. When the module output power decreases or the chip junction temperature is within a safe range, the coolant flow rate is reduced to decrease the auxiliary energy consumption of the cooling system, with a maximum... It can reduce auxiliary energy consumption by more than 20%; at the same time, the coolant flow rate adjustment can be linked with the thermal resistance state of the phase change interface. When the interface thermal resistance fluctuates due to changes in the state of the phase change material, the coolant flow rate can be adjusted synchronously to compensate for the heat dissipation capacity, so as to achieve stable heat dissipation performance under all operating conditions; the coolant flow rate adjustment range is 10% to 100% of the rated flow rate, and the adjustment response time is no more than 500ms, which can quickly match the power changes of the module; this invention can ensure the normal melting of the phase change material layer 9 in an extreme low temperature environment of -40℃, solving the problem that traditional passive phase change schemes cannot start at low temperatures.

[0100] The assembly steps of the heat dissipation packaging structure in this embodiment are as follows:

[0101] Surface pretreatment: The heat dissipation contact surface 11 of the module substrate 2 and the mating surface of the cold plate 15 are ultrasonically cleaned with anhydrous ethanol or isopropanol to remove surface oil, oxide layer and impurities. After cleaning, the surface is dried with dry nitrogen to ensure surface cleanliness.

[0102] Sealing ring installation: Embed the metal C-type sealing ring into the interface sealing groove 10 or interface sealing groove 24, ensuring that the sealing ring is fully engaged in the groove without any lifting or misalignment;

[0103] Phase change material installation: Cut the pre-formed phase change material layer 9 into a matching size and place it on the heat dissipation contact surface 11 of the module substrate 2. The texture of the thin sheet is aligned with the microgrooves of the capillary structure layer 12 to ensure a smooth and bubble-free fit.

[0104] Assembly: Align the cold plate 15 of the radiator conversion chamber 3 with the module substrate 2, ensuring that the interface sealing groove 10 and the interface sealing groove 2 are aligned, and the capillary layer 12 and the capillary layer 2 are aligned to avoid misalignment.

[0105] Locking and fixing: Pass the matching bolts through the ear plate through hole of the fastening connection structure 5, and tighten the bolts in three steps to the rated torque (preferably 6 to 8 N·m) to ensure that the pressure of the two interfaces is evenly distributed and the thin sheet of phase change material layer 9 is evenly compressed to the design thickness.

[0106] Electrical connection: Connect the lead-out electrode of the miniature heating element 17 and the signal line of the temperature sensor to the corresponding interface of the controller 8, and connect the output terminal of the controller 8 to the IGBT drive circuit and the coolant flow regulation actuator to ensure that the wiring is firm and the insulation is reliable.

[0107] Initial melting process: Upon initial power-on, controller 8 activates micro heating element 17 and heats at rated power for 2-5 seconds to completely melt the phase change material layer 9. The molten liquid alloy fills all microscopic gaps under the combined action of clamping force and capillary force. Then, the heating element is turned off, and the phase change material solidifies in situ, completing the initial installation. This step does not need to be repeated for subsequent use.

[0108] The heat dissipation packaging structure of this embodiment has been tested and found that, under the operating conditions of FF400R12KE4 IGBT module 1, rated operating current of 400A, and DC bus voltage of 600V, the chip's startup peak temperature is only 85℃, while the startup peak temperature of the traditional thermal grease solution is 108℃, representing a temperature peak reduction of 21.3%; the interface contact thermal resistance is stable at 8-12mm. 2 • K / W, which is more than 80% lower than traditional thermal grease solutions; after 10,000 power cycles, the interface thermal resistance increases by no more than 5%, and the module power cycle life is increased by more than 4 times; it can still complete the preheating start-up normally in a low temperature environment of -40℃ without the problem of overheating during startup.

[0109] It should be noted that, in this invention, unless otherwise explicitly specified and limited, the terms "sliding," "rotating," "fixed," and "equipped" should be interpreted broadly. For example, they can refer to welded connections, bolted connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0110] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A heat dissipation packaging structure for a high power density IGBT module, comprising an IGBT module, a module substrate fixedly mounted on the IGBT module, and a heat dissipation device detachably mounted on the module substrate, characterized in that: The bottom of the module substrate is provided with a heat dissipation contact surface, and a capillary structure layer is provided on the heat dissipation contact surface. A phase change material layer is placed between the module substrate and the heat dissipation device, and the phase change material layer is attached to the area directly opposite the first capillary structure layer. When the IGBT module generates high heat, causing the phase change material layer to change from solid to liquid, the capillary structure layer is used to constrain the liquid phase change material and guide it to adaptively fill the microscopic contact gaps, thereby achieving a continuous reduction in interface thermal resistance and stable operation without leakage.

2. The heat dissipation packaging structure for high power density IGBT modules according to claim 1, characterized in that, The module substrate is a metal base plate structure, preferably copper or aluminum silicon carbide. The IGBT module and the heat dissipation device are connected by a fastening connection structure.

3. The heat dissipation packaging structure for high power density IGBT modules according to claim 2, characterized in that, The heat dissipation device is provided with a second capillary structure layer, which has the same structure as the first capillary structure layer and is positioned opposite each other. The phase change material layer is filled within the first and second capillary structures, and is solid at room temperature and liquid at operating temperature.

4. The heat dissipation packaging structure for high power density IGBT modules according to claim 1, characterized in that, The phase change material layer is made of a low-melting-point alloy preform thin sheet, the material of which is a Bi-In-Sn eutectic alloy or a Ga-In-Sn alloy, and the thickness of the thin sheet is 100-300 μm.

5. The heat dissipation packaging structure for high power density IGBT modules according to claim 1 or 4, characterized in that, The first capillary structure layer adopts a microgroove array. The microgrooves are parallel or grid-like, with a groove depth of 50-150 μm, a width of 50-100 μm, and a groove spacing of 100-300 μm. Furthermore, the surface of the trench is plated with nickel or gold.

6. The heat dissipation packaging structure for high power density IGBT modules according to claim 3, characterized in that, The heat dissipation device includes: A heat sink conversion compartment, which is detachably connected to the IGBT module; The heat sink conversion compartment is provided with a cold plate at its top, the capillary layer is disposed on the cold plate, and the module substrate is located between the IGBT module and the cold plate. It also includes a coolant inlet and a coolant outlet, which are located at opposite ends of the radiator conversion chamber for coolant to enter and exit the radiator conversion chamber.

7. The heat dissipation packaging structure for high power density IGBT modules according to claim 6, characterized in that, Also includes: A heat-conducting plate, wherein there are multiple heat-conducting plates, which are uniformly and fixedly installed on the cold plate and located inside the radiator conversion chamber; The multiple heat-conducting plates are arranged in parallel, dividing the heat sink conversion chamber into multiple liquid flow channels.

8. The heat dissipation packaging structure for high power density IGBT modules according to claim 7, characterized in that, Also includes: Interface sealing groove two, which is formed on the cold plate; Interface sealing groove one is formed on the heat dissipation contact surface. Interface sealing groove one has the same structure as interface sealing groove two and is positioned opposite to interface sealing groove two. A metal C-shaped sealing ring is provided between the interface sealing groove one and the interface sealing groove two, forming a closed cavity after compression.

9. The heat dissipation packaging structure for high power density IGBT modules according to claim 1, characterized in that, Also includes: A controller is fixedly mounted on the IGBT module and is signal-connected to the heat dissipation device; A miniature heating element is disposed on the heat dissipation contact surface and is signal-connected to the controller. The controller is used to actively activate the micro heating element to preheat the phase change material layer when the IGBT module starts up or the power jumps and the chip has not yet generated a lot of heat, so as to melt it in advance, thereby eliminating the thermal response lag and instantaneous temperature spike of the chip during the startup phase.

10. The heat dissipation packaging structure for a high power density IGBT module according to claim 9, characterized in that, The micro heating element is an embedded resistance heating wire. The serpentine resistance wire is made on the lower surface of the module substrate by thick film printing or electroplating process. The material is NiCr or Pt and the thickness is 10-30μm. The resistance wire surface is covered with an electrically insulating and thermally conductive thin film, which is electrically isolated from the phase change material layer.

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