Millimeter wave QFN package heat dissipation enhancement method and system based on microchannel structure

Abstract

The application discloses a millimeter wave QFN packaging heat dissipation enhancement method and system based on a micro-channel structure, and comprises the following steps: step one: constructing a layered micro-channel network in the millimeter wave QFN packaging substrate, the layered micro-channel network comprises a heat conduction layer micro-channel attached to a chip, a main heat dissipation micro-channel located in the middle of the packaging substrate and an auxiliary heat dissipation micro-channel close to the side of the packaging pin, and the micro-channels in each layer are communicated with each other through flow guide holes; the application has the beneficial effects that: the layered micro-channel network design is adopted, the compact structure of the millimeter wave QFN packaging is adapted, multi-dimensional heat dissipation channel layout is realized in the limited packaging space, the close attachment to the chip is ensured to achieve efficient heat conduction, the reasonable distribution of the main heat dissipation micro-channel and the auxiliary heat dissipation micro-channel avoids the interference with the packaging pin, meanwhile, the packaging volume is not increased, and the high-frequency application advantages of the millimeter wave device are ensured.

Description

Technical Field

[0001] This invention belongs to the field of millimeter-wave device packaging and heat dissipation technology, specifically relating to a method and system for enhancing heat dissipation in millimeter-wave QFN packaging based on microchannel structure. Background Technology

[0002] With the widespread application of millimeter-wave technology in fields such as intelligent sensing, wireless communication, and radar detection, especially the rapid development of high-frequency millimeter-wave devices in the 120GHz and above frequency bands, stringent requirements have been placed on the heat dissipation performance of device packaging. Millimeter-wave QFN, as a compact packaging form, has advantages such as small size, short pins, and low parasitic parameters, and is widely used in high-frequency millimeter-wave chip packaging. However, high-frequency millimeter-wave chips generate significant power losses during operation, leading to high power density heat accumulation inside the package. If heat dissipation is not timely and effective, the chip's operating temperature will rise, which will not only reduce the device's electrical performance and shorten its lifespan, but may also cause thermal runaway, seriously affecting the stability and reliability of the entire system.

[0003] Extensive research has been conducted on heat dissipation solutions for chip packaging in the prior art. For example, Chinese invention patent CN117457602B discloses a high heat flux chip packaging structure and its real-time service temperature control method. This patent employs a multi-level control mode of air cooling, single-sided liquid cooling, double-sided liquid cooling, and liquid cooling plus air cooling composite heat dissipation based on the different heat flux densities detected by the chip, to achieve heat dissipation for logic chips and memory chips. Specifically, when the heat flux density is below 10W / cm², 2 Air cooling is used; heat flux density is 10 W / cm². 2 -50W / cm 2 Single-sided liquid cooling is used during this period; the heat flux density is 50 W / cm². 2 -100W / cm 2 Double-sided liquid cooling is used during operation; heat flux density is not less than 100W / cm². 2 It employs a combination of double-sided liquid cooling and air cooling for heat dissipation.

[0004] However, the aforementioned existing technologies have several limitations when applied to heat dissipation of millimeter-wave QFN packages: First, the upper and lower microchannel structure used in this technology is incompatible with the compact structure of millimeter-wave QFN packages. The pin distribution and package thickness of QFN packages limit the arrangement space of the double-sided microchannels, and forced arrangement will lead to an increase in package volume, destroying its advantages in high-frequency applications. Second, the heat dissipation mode switching of this technology is based solely on the single parameter of heat flux density, without considering the uneven heat flux density distribution of millimeter-wave chips and the temperature gradient of the package substrate, which can easily lead to insufficient local heat dissipation or waste of heat dissipation resources. Third, the heat dissipation working fluid flow mode used in this technology is unidirectional circulation, without targeted heat dissipation optimization for the heat accumulation areas of millimeter-wave chips, resulting in limited heat dissipation efficiency. Finally, this technology does not consider the transmission characteristics of millimeter-wave signals, and the arrangement of the heat dissipation structure may introduce additional electromagnetic interference, affecting the communication or detection performance of millimeter-wave devices.

[0005] In addition, heat dissipation of millimeter-wave QFN packages also faces the following special challenges: First, millimeter-wave chips have high heat flux density and heat distribution is concentrated in the active area of ​​the chip, making it difficult for traditional heat dissipation structures to achieve precise heat dissipation; second, the substrate thickness of QFN packages is relatively thin, which limits the size and layout of heat dissipation channels; third, millimeter-wave signals have high requirements for the dielectric properties and electromagnetic shielding performance of the package structure, and the introduction of heat dissipation structures must not affect the signal transmission quality. Summary of the Invention

[0006] The purpose of this invention is to provide a heat dissipation enhancement method and system for millimeter-wave QFN packages based on microchannel structures, which solves the problems of incompatibility between existing heat dissipation technologies and millimeter-wave QFN package structures, poor heat dissipation targeting, and easy interference with signal transmission, thereby achieving efficient, accurate, and low-interference heat dissipation effects.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for enhancing heat dissipation in millimeter-wave QFN packages based on microchannel structures, comprising the following steps: Step 1: Construct a layered microchannel network inside the millimeter-wave QFN packaging substrate. The layered microchannel network includes a thermally conductive layer microchannel that is attached to the chip, a main heat dissipation microchannel located in the middle of the packaging substrate, and an auxiliary heat dissipation microchannel near the packaging pins. Each layer of microchannels is interconnected through a flow guide hole. Step 2: Real-time acquisition of operating temperature, heat flux density distribution, and temperature gradient data of the chip inside the millimeter-wave QFN package using thermal characteristic sensing components; Step 3: Determine the heat dissipation requirement level based on the collected thermal characteristic data, and select the corresponding heat dissipation mode based on the heat dissipation requirement level. The heat dissipation modes include gradient liquid cooling mode, microchannel-fin synergistic heat dissipation mode and phase change enhanced heat dissipation mode. Step 4: Activate the heat dissipation drive component in the corresponding heat dissipation mode to control the flow state of the heat dissipation medium in the layered microchannel network, or trigger the operation of the phase change heat dissipation unit to achieve directional heat dissipation of millimeter-wave QFN package. Step 5: Monitor the changes in thermal characteristics of the chip and packaging substrate in real time during the heat dissipation process, and dynamically adjust the heat dissipation driving parameters until the chip temperature stabilizes within the preset operating temperature range.

[0008] As a preferred technical solution of the present invention, in step one, the thermal conductive layer microchannel adopts a flat microchannel structure that fits the chip package surface, and the inner wall of the channel is provided with a micron-level bump turbulence structure; the main heat dissipation microchannel adopts a serpentine distribution structure, the channel cross-section is trapezoidal, and the channel density of the main heat dissipation microchannel gradually increases along the heat dissipation direction; the auxiliary heat dissipation microchannel is adapted to the pin avoidance area of ​​the QFN package, adopts a zigzag distribution, and the inlet and outlet of the auxiliary heat dissipation microchannel are connected to the external heat dissipation working fluid circulation system.

[0009] In a preferred embodiment of the present invention, in step two, the thermal characteristic sensing component includes a miniature temperature sensor disposed directly below the active area of ​​the chip, a heat flux density sensor distributed on the inner wall of the main heat dissipation microchannel, and a temperature gradient sensor arranged on the edge of the packaging substrate; the sampling frequency of the miniature temperature sensor is not less than 100Hz, and the measurement accuracy of the heat flux density sensor is not less than 0.1W / cm². 2 .

[0010] As a preferred embodiment of the present invention, in step three, the criterion for determining the heat dissipation requirement level is: when the chip operating temperature is below 60°C and the heat flux density is less than 15W / cm². 2 When the chip operating temperature is between 60℃ and 100℃ and the heat flux density is 15W / cm³, the appropriate cooling mode is selected; when the chip operating temperature is between 60℃ and 100℃ and the heat flux density is 15W / cm³, the appropriate cooling mode is selected. 2 -40W / cm 2 When the chip's operating temperature is above 100℃ and the heat flux density is greater than 40W / cm², the microchannel-fin co-heating mode is selected. 2 When the condition is determined to be of a high heat dissipation requirement level, the corresponding phase change enhanced heat dissipation mode should be selected.

[0011] As a preferred technical solution of the present invention, the start-up process of the gradient liquid cooling mode in step four includes: starting a micro circulation pump to pump the heat dissipation medium from the inlet of the auxiliary heat dissipation microchannel, flowing through the guide hole sequentially through the main heat dissipation microchannel and the heat conduction layer microchannel, using the flat structure of the heat conduction layer microchannel to adhere to the chip and conduct heat, expanding the heat dissipation area through the serpentine distribution of the main heat dissipation microchannel, and finally flowing out from the outlet of the auxiliary heat dissipation microchannel to complete a single cycle of the heat dissipation medium; wherein, the flow rate of the heat dissipation medium is dynamically adjusted according to the chip temperature, and the adjustment range is 0.5m / s-2m / s.

[0012] As a preferred technical solution of the present invention, the startup process of the microchannel-fin synergistic heat dissipation mode in step four includes: on the basis of the gradient liquid cooling heat dissipation mode, starting the micro heat dissipation fin assembly outside the packaging substrate, the micro heat dissipation fin assembly being attached to the outer wall of the packaging substrate corresponding to the main heat dissipation microchannel; simultaneously adjusting the output power of the micro circulation pump to increase the flow rate of the heat dissipation medium to 1.5-2 times that in the gradient liquid cooling heat dissipation mode, and opening the electromagnetic flow guide valve in the main heat dissipation microchannel to increase the flow distribution ratio of the microchannel in the area of ​​concentrated heat flux density.

[0013] As a preferred technical solution of the present invention, the activation process of the phase change enhanced heat dissipation mode in step four includes: on the basis of the microchannel-fin collaborative heat dissipation mode, triggering the phase change heat dissipation unit set between the heat-conducting layer microchannel and the chip, the phase change heat dissipation unit is filled with a high thermal conductivity phase change material, when the chip temperature reaches the phase change temperature of the phase change material, the phase change material absorbs heat and undergoes a phase change, thereby achieving instantaneous cooling; at the same time, the heat dissipation working fluid cooling component is activated, and the circulating heat dissipation working fluid is cooled to a preset temperature and then pumped back into the microchannel network.

[0014] As a preferred technical solution of the present invention, the high thermal conductivity phase change material is a graphene composite paraffin-based phase change material with a phase change temperature of 80℃-90℃, a latent heat of phase change of not less than 180J / g, and a thermal conductivity of not less than 5W / (m・K); the heat dissipation working fluid cooling component adopts a micro semiconductor refrigeration chip with a cooling temperature adjustment range of 10℃-30℃.

[0015] This invention also discloses a millimeter-wave QFN package heat dissipation enhancement system based on a microchannel structure, including... The layered microchannel packaging module is used to carry millimeter-wave chips and provide heat dissipation channels. It includes a QFN packaging substrate, a layered microchannel network disposed inside the packaging substrate, and a phase change heat dissipation unit attached to the chip. The layered microchannel network is connected to an external heat dissipation working fluid circulation system. The thermal characteristic sensing module is used to collect thermal characteristic data of the chip and packaging substrate in real time. It includes a miniature temperature sensor, a heat flux density sensor, a temperature gradient sensor and a data acquisition unit. The data acquisition unit is electrically connected to each sensor and is used to summarize and transmit thermal characteristic data. The multi-mode heat dissipation drive module is used to provide driving power for different heat dissipation modes, including a micro circulation pump, an electromagnetic flow guide valve, a micro heat dissipation fin assembly and a heat dissipation working fluid cooling assembly. The micro circulation pump is connected to the inlet and outlet of the layered microchannel network, and the electromagnetic flow guide valve is set at the branch node of the main heat dissipation microchannel. The intelligent control module is used to receive thermal characteristic data and control the switching of heat dissipation modes. It includes a data processing unit, a heat dissipation level determination unit, and a drive control unit. The data processing unit performs filtering and noise reduction processing on the collected thermal characteristic data. The heat dissipation level determination unit determines the heat dissipation requirement level based on the processed data. The drive control unit controls the working state of the multi-mode heat dissipation drive module according to the heat dissipation requirement level.

[0016] Compared with the prior art, the beneficial effects of the present invention are: Employing a layered microchannel network design, adapted to the compact structure of millimeter-wave QFN packages, it achieves a multi-dimensional heat dissipation channel layout within a limited package space. This ensures close contact with the chip for efficient heat conduction, while the reasonable distribution of the main and auxiliary heat dissipation microchannels avoids interference with the package pins. At the same time, it does not increase the package size, ensuring the high-frequency application advantages of millimeter-wave devices. The heat dissipation requirement level is determined by two parameters: chip operating temperature and heat flux density. The heat dissipation mode is switched by combining the temperature gradient data of the packaging substrate. Compared with the existing technology that only controls the heat flux density as a single parameter, this method is more in line with the uneven heat distribution of millimeter-wave chips, and achieves precise and differentiated heat dissipation, avoiding insufficient local heat dissipation or waste of heat dissipation resources. From gradient liquid cooling to microchannel-fin synergy, and then to phase change enhanced heat dissipation, it covers different heat dissipation needs of millimeter-wave QFN packaging. In particular, the introduction of phase change heat dissipation unit can quickly cope with the sudden high power heat loss of the chip and solve the heat dissipation problem caused by heat accumulation in high-frequency millimeter-wave chips. By setting a turbulence structure on the inner wall of the microchannel and optimizing the flow velocity and flow distribution of the heat dissipation medium, the heat dissipation efficiency was improved. The system adopts a modular design, with each module functioning independently yet working collaboratively, facilitating installation, maintenance, and upgrades. It can be adapted and adjusted according to different specifications of millimeter-wave QFN packages, making it widely applicable. Attached Figure Description

[0017] Figure 1 This is a flowchart of the heat dissipation enhancement method for millimeter-wave QFN packaging based on microchannel structure according to the present invention; Figure 2 This is a schematic diagram of the heat dissipation enhancement system of the millimeter-wave QFN package based on the microchannel structure of the present invention. Detailed Implementation

[0018] 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.

[0019] Please see Figure 1 and Figure 2 This invention provides a method for enhancing heat dissipation in millimeter-wave QFN packages based on microchannel structures, comprising the following steps: Step 1: Construct a layered microchannel network inside the millimeter-wave QFN package substrate. The layered microchannel network includes a thermally conductive layer microchannel bonded to the chip, a main heat dissipation microchannel located in the middle of the package substrate, and auxiliary heat dissipation microchannels near the package pins. Each layer of microchannels is interconnected through flow guide holes. The thermally conductive layer microchannel adopts a flat microchannel structure bonded to the chip package surface, and the inner wall of the channel is provided with a micron-level bump turbulence structure. The main heat dissipation microchannel adopts a serpentine distribution structure with a trapezoidal channel cross-section, and the channel density of the main heat dissipation microchannel gradually increases along the heat dissipation direction. The auxiliary heat dissipation microchannel is adapted to the pin avoidance area of ​​the QFN package, adopts a zigzag distribution, and the inlet and outlet of the auxiliary heat dissipation microchannel are connected to the external heat dissipation working fluid circulation system. Step 2: Real-time acquisition of operating temperature, heat flux density distribution, and temperature gradient data of the chip within the millimeter-wave QFN package using thermal characteristic sensing components. These components include a miniature temperature sensor positioned directly below the active area of ​​the chip, heat flux density sensors distributed along the inner walls of the main heat dissipation microchannels, and temperature gradient sensors positioned along the edges of the package substrate. The acquisition frequency of the miniature temperature sensor is no less than 100Hz, and the measurement accuracy of the heat flux density sensor is no less than 0.1W / cm². 2 ; Step 3: Determine the heat dissipation requirement level based on the collected thermal characteristic data, and select the corresponding heat dissipation mode based on the heat dissipation requirement level. The heat dissipation modes include gradient liquid cooling mode, microchannel-fin synergistic heat dissipation mode, and phase change enhanced heat dissipation mode. The criteria for determining the heat dissipation requirement level are: when the chip operating temperature is below 60℃ and the heat flux density is less than 15W / cm³. 2 When the chip operating temperature is between 60℃ and 100℃ and the heat flux density is 15W / cm³, the appropriate cooling mode is selected; when the chip operating temperature is between 60℃ and 100℃ and the heat flux density is 15W / cm³, the appropriate cooling mode is selected. 2 -40W / cm 2When the chip's operating temperature is above 100℃ and the heat flux density is greater than 40W / cm², the microchannel-fin co-heating mode is selected. 2 When the condition is determined to be of a high heat dissipation requirement level, the phase change enhanced heat dissipation mode should be selected accordingly. Step 4: Activate the heat dissipation drive component in the corresponding heat dissipation mode to control the flow state of the heat dissipation medium within the layered microchannel network, or trigger the operation of the phase change heat dissipation unit to achieve directional heat dissipation for the millimeter-wave QFN package; the activation process of the gradient liquid cooling mode includes: activating the micro circulation pump to pump the heat dissipation medium from the inlet of the auxiliary heat dissipation microchannel, flowing through the guide hole sequentially through the main heat dissipation microchannel and the thermally conductive layer microchannel, utilizing the flat structure of the thermally conductive layer microchannel to adhere to the chip and conduct heat, expanding the heat dissipation area through the serpentine distribution of the main heat dissipation microchannel, and finally flowing out from the outlet of the auxiliary heat dissipation microchannel, completing a single cycle of the heat dissipation medium; wherein, the flow rate of the heat dissipation medium is dynamically adjusted according to the chip temperature, with an adjustment range of 0.5m / s-2m / s; the activation process of the microchannel-fin synergistic heat dissipation mode includes: based on the gradient liquid cooling mode, activating the micro heat dissipation fin assembly outside the package substrate, the micro heat dissipation fin assembly adhering to the outer wall of the package substrate corresponding to the main heat dissipation microchannel; simultaneously adjusting the micro The output power of the circulating pump increases the flow rate of the heat dissipation medium to 1.5-2 times that of the gradient liquid cooling mode, and opens the electromagnetic flow guide valve in the main heat dissipation microchannel, increasing the flow distribution ratio of the microchannel in the area of ​​concentrated heat flux density. The start-up process of the phase change enhanced heat dissipation mode includes: based on the microchannel-fin synergistic heat dissipation mode, triggering the phase change heat dissipation unit set between the heat-conducting layer microchannel and the chip. The phase change heat dissipation unit is filled with a high thermal conductivity phase change material. When the chip temperature reaches the phase change temperature of the phase change material, the phase change material absorbs heat and undergoes a phase change, achieving instantaneous cooling. At the same time, the heat dissipation medium cooling component is activated to cool the circulating heat dissipation medium to the preset temperature and then pump it back into the microchannel network. The high thermal conductivity phase change material is a graphene composite paraffin-based phase change material with a phase change temperature of 80℃-90℃, a latent heat of phase change of not less than 180J / g, and a thermal conductivity of not less than 5W / (m・K). The heat dissipation medium cooling component uses a micro semiconductor refrigeration chip with a cooling temperature adjustment range of 10℃-30℃. Step 5: Monitor the changes in thermal characteristics of the chip and packaging substrate in real time during the heat dissipation process, and dynamically adjust the heat dissipation driving parameters until the chip temperature stabilizes within the preset operating temperature range. The process of dynamically adjusting the heat dissipation driving parameters includes: when the chip temperature drops at a rate greater than 5°C / min, reducing the output power of the micro circulation pump or reducing the rotation speed of the heat sink fins; when the chip temperature stabilizes within the preset operating temperature ±2°C range, maintaining the current heat dissipation driving parameters; when the chip temperature rebounds and the rate of increase is greater than 2°C / min, increasing the heat dissipation driving power or switching to a higher level of heat dissipation mode.

[0020] A millimeter-wave QFN package thermal enhancement system based on a microchannel structure, including The layered microchannel packaging module is used to carry millimeter-wave chips and provide heat dissipation channels. It includes a QFN packaging substrate, a layered microchannel network disposed inside the packaging substrate, and a phase change heat dissipation unit attached to the chip. The layered microchannel network is connected to an external heat dissipation working fluid circulation system. The thermal characteristic sensing module is used to collect thermal characteristic data of the chip and packaging substrate in real time. It includes a miniature temperature sensor, a heat flux density sensor, a temperature gradient sensor and a data acquisition unit. The data acquisition unit is electrically connected to each sensor and is used to summarize and transmit thermal characteristic data. The multi-mode heat dissipation drive module is used to provide driving power for different heat dissipation modes, including a micro circulation pump, an electromagnetic flow guide valve, a micro heat dissipation fin assembly and a heat dissipation working fluid cooling assembly. The micro circulation pump is connected to the inlet and outlet of the layered microchannel network, and the electromagnetic flow guide valve is set at the branch node of the main heat dissipation microchannel. The intelligent control module is used to receive thermal characteristic data and control the switching of heat dissipation modes. It includes a data processing unit, a heat dissipation level determination unit, and a drive control unit. The data processing unit performs filtering and noise reduction processing on the collected thermal characteristic data. The heat dissipation level determination unit determines the heat dissipation requirement level based on the processed data. The drive control unit controls the working state of the multi-mode heat dissipation drive module according to the heat dissipation requirement level.

[0021] Although embodiments of the invention have been shown and described (see the detailed description above), it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for enhancing heat dissipation in millimeter-wave QFN packages based on microchannel structures, characterized in that: Includes the following steps: Step 1: Construct a layered microchannel network inside the millimeter-wave QFN packaging substrate. The layered microchannel network includes a thermally conductive layer microchannel that is attached to the chip, a main heat dissipation microchannel located in the middle of the packaging substrate, and an auxiliary heat dissipation microchannel near the packaging pins. Each layer of microchannels is interconnected through a flow guide hole. Step 2: Real-time acquisition of operating temperature, heat flux density distribution, and temperature gradient data of the chip inside the millimeter-wave QFN package using thermal characteristic sensing components; Step 3: Determine the heat dissipation requirement level based on the collected thermal characteristic data, and select the corresponding heat dissipation mode based on the heat dissipation requirement level. The heat dissipation modes include gradient liquid cooling mode, microchannel-fin synergistic heat dissipation mode and phase change enhanced heat dissipation mode. Step 4: Activate the heat dissipation drive component in the corresponding heat dissipation mode to control the flow state of the heat dissipation medium in the layered microchannel network, or trigger the operation of the phase change heat dissipation unit to achieve directional heat dissipation of millimeter-wave QFN package. Step 5: Monitor the changes in thermal characteristics of the chip and packaging substrate in real time during the heat dissipation process, and dynamically adjust the heat dissipation driving parameters until the chip temperature stabilizes within the preset operating temperature range.

2. The heat dissipation enhancement method for millimeter-wave QFN packaging based on microchannel structure according to claim 1, characterized in that: In step one, the thermal conductive layer microchannel adopts a flat microchannel structure that fits the chip package surface, and the inner wall of the channel is provided with a micron-level bump turbulence structure; the main heat dissipation microchannel adopts a serpentine distribution structure, the channel cross-section is trapezoidal, and the channel density of the main heat dissipation microchannel gradually increases along the heat dissipation direction; the auxiliary heat dissipation microchannel is adapted to the pin avoidance area of ​​the QFN package, adopts a zigzag distribution, and the inlet and outlet of the auxiliary heat dissipation microchannel are connected to the external heat dissipation working fluid circulation system.

3. The heat dissipation enhancement method for millimeter-wave QFN packaging based on microchannel structure according to claim 1, characterized in that: In step two, the thermal characteristic sensing component includes a miniature temperature sensor positioned directly below the active area of ​​the chip, heat flux density sensors distributed along the inner wall of the main heat dissipation microchannel, and a temperature gradient sensor arranged along the edge of the packaging substrate; the sampling frequency of the miniature temperature sensor is not less than 100Hz, and the measurement accuracy of the heat flux density sensor is not less than 0.1W / cm². 2 .

4. The heat dissipation enhancement method for millimeter-wave QFN packaging based on microchannel structure according to claim 1, characterized in that: In step three, the criteria for determining the heat dissipation requirement level are: when the chip operating temperature is below 60℃ and the heat flux density is less than 15W / cm². 2 When the chip operating temperature is between 60℃ and 100℃ and the heat flux density is 15W / cm³, the appropriate cooling mode is selected; when the chip operating temperature is between 60℃ and 100℃ and the heat flux density is 15W / cm³, the appropriate cooling mode is selected. 2 -40W / cm 2 When the chip's operating temperature is above 100℃ and the heat flux density is greater than 40W / cm², the microchannel-fin co-heating mode is selected. 2 When the condition is determined to be of a high heat dissipation requirement level, the corresponding phase change enhanced heat dissipation mode should be selected.

5. The heat dissipation enhancement method for millimeter-wave QFN packaging based on microchannel structure according to claim 4, characterized in that: In step four, the start-up process of the gradient liquid cooling mode includes: starting the micro-circulation pump, pumping the heat dissipation medium into the auxiliary heat dissipation microchannel from the inlet, flowing through the guide hole sequentially through the main heat dissipation microchannel and the heat conduction layer microchannel, utilizing the flat structure of the heat conduction layer microchannel to adhere to the chip and conduct heat, expanding the heat dissipation area through the serpentine distribution of the main heat dissipation microchannel, and finally flowing out from the outlet of the auxiliary heat dissipation microchannel, completing a single cycle of the heat dissipation medium; wherein, the flow rate of the heat dissipation medium is dynamically adjusted according to the chip temperature, with an adjustment range of 0.5m / s-2m / s.

6. The heat dissipation enhancement method for millimeter-wave QFN packaging based on microchannel structure according to claim 4, characterized in that: In step four, the startup process of the microchannel-fin synergistic heat dissipation mode includes: on the basis of the gradient liquid cooling heat dissipation mode, starting the micro heat dissipation fin assembly outside the packaging substrate, the micro heat dissipation fin assembly is attached to the outer wall of the packaging substrate corresponding to the main heat dissipation microchannel; at the same time, the output power of the micro circulation pump is adjusted to increase the flow rate of the heat dissipation medium to 1.5-2 times that in the gradient liquid cooling heat dissipation mode, and the electromagnetic flow guide valve in the main heat dissipation microchannel is opened to increase the flow distribution ratio of the microchannel in the area of ​​concentrated heat flux density.

7. The heat dissipation enhancement method for millimeter-wave QFN packaging based on microchannel structure according to claim 4, characterized in that: In step four, the activation process of the phase change enhanced heat dissipation mode includes: based on the microchannel-fin collaborative heat dissipation mode, triggering the phase change heat dissipation unit set between the heat-conducting layer microchannel and the chip. The phase change heat dissipation unit is filled with a high thermal conductivity phase change material. When the chip temperature reaches the phase change temperature of the phase change material, the phase change material absorbs heat and undergoes a phase change, achieving instantaneous cooling; at the same time, the heat dissipation working fluid cooling component is activated to cool the circulating heat dissipation working fluid to the preset temperature and then pump it back into the microchannel network.

8. The heat dissipation enhancement method for millimeter-wave QFN packaging based on microchannel structure according to claim 7, characterized in that: The high thermal conductivity phase change material is a graphene-paraffin composite phase change material with a phase change temperature of 80℃-90℃, a latent heat of phase change of not less than 180J / g, and a thermal conductivity of not less than 5W / (m・K); the heat dissipation working fluid cooling component adopts a micro semiconductor refrigeration chip with a cooling temperature adjustment range of 10℃-30℃.

9. A millimeter-wave QFN packaged heat dissipation enhancement system based on a microchannel structure, characterized in that: The method for enhancing heat dissipation of millimeter-wave QFN packages based on microchannel structures as described in any one of claims 1-8 includes: The layered microchannel packaging module is used to carry millimeter-wave chips and provide heat dissipation channels. It includes a QFN packaging substrate, a layered microchannel network disposed inside the packaging substrate, and a phase change heat dissipation unit attached to the chip. The layered microchannel network is connected to an external heat dissipation working fluid circulation system. The thermal characteristic sensing module is used to collect thermal characteristic data of the chip and packaging substrate in real time. It includes a miniature temperature sensor, a heat flux density sensor, a temperature gradient sensor and a data acquisition unit. The data acquisition unit is electrically connected to each sensor and is used to summarize and transmit thermal characteristic data. The multi-mode heat dissipation drive module is used to provide driving power for different heat dissipation modes, including a micro circulation pump, an electromagnetic flow guide valve, a micro heat dissipation fin assembly and a heat dissipation working fluid cooling assembly. The micro circulation pump is connected to the inlet and outlet of the layered microchannel network, and the electromagnetic flow guide valve is set at the branch node of the main heat dissipation microchannel. The intelligent control module is used to receive thermal characteristic data and control the switching of heat dissipation modes. It includes a data processing unit, a heat dissipation level determination unit, and a drive control unit. The data processing unit performs filtering and noise reduction processing on the collected thermal characteristic data. The heat dissipation level determination unit determines the heat dissipation requirement level based on the processed data. The drive control unit controls the working state of the multi-mode heat dissipation drive module according to the heat dissipation requirement level.

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