A high-power radio frequency array three-dimensional heterogeneous microchannel cooling device

Abstract

The present invention discloses a high-power radio frequency array three-dimensional heterogeneous microfluidic cooling device, including a microfluidic cooling layer, wherein the microfluidic cooling layer is composed of a diamond substrate layer with microfluidics, a silicon substrate layer with fully parallel water collection and distribution microfluidics with tree-shaped branches, and an LTCC substrate layer with parallel co-flow design channels with integrated water collection and distribution functions. The front of the diamond substrate layer is welded with an RF chip array, and the silicon substrate layer is arranged below the diamond substrate layer. The silicon substrate layer includes a connected silicon substrate final water collection layer and a silicon substrate final water distribution layer, wherein the silicon substrate final water collection layer is provided with four groups and arranged in an array below the diamond substrate layer. The high-power radio frequency array microfluidic cooling device provided by the present invention performs flow channel design and multi-layer substrate material arrangement based on the flow and heat exchange characteristics in the microfluidic channel, thereby improving the heat dissipation capacity of the radio frequency array and ensuring the uniformity of the near-junction heat dissipation flow distribution.

Description

Technical Field

[0001] The invention relates to the field of radio frequency array heat dissipation, and in particular to a high-power radio frequency array three-dimensional heterogeneous microchannel cooling device. Background Art

[0002] RF array refers to the high-density arrangement of RF electronic chips including radar, communication, electronic warfare, navigation, remote sensing and telemetry in two dimensions. It has the advantages of diverse functions, easy power synthesis, and simultaneous processing of multiple targets. With the continuous development of chip technology and integration technology, the core transceiver module of the RF array has evolved from the traditional two-dimensional brick or chip type to the three-dimensional stacking direction. At the same time, the application of third-generation semiconductor materials (SiC, GaN, etc.) has made the heat flux density of microwave power chips exceed 1kW / cm2. Heat dissipation problems such as miniaturization, multiple heat sources, and high heat flux density have become the key bottleneck restricting the development of RF arrays. With the emergence of thermal control problems in RF arrays, cooling technology has gradually developed from traditional multi-layer conduction heat dissipation to chip near-junction heat dissipation. The main idea of ​​near-junction heat dissipation is to transfer the cold end from the traditional metal cold plate to the adjacent position of the power chip (package shell or substrate), shorten the heat transfer path, thereby reducing the heat transfer thermal resistance and improving the heat dissipation performance.

[0003] Existing typical chip near-junction heat dissipation solutions include invention patents with publication number CN107240578A and patent name "Silicon carbide microchannel heat dissipation structure for three-dimensional integrated circuits and its manufacturing method", and invention patents with publication number CN104201158A and patent name "A silicon-based microchannel radiator integrated cooling device". The above method uses a silicon-based or silicon carbide-based cooling device with an integrated microchannel radiator, and its significant advantages include short thermal resistance path and high heat dissipation area.

[0004] However, the main problems include:

[0005] 1. The low thermal conductivity leads to a large temperature gradient inside the substrate, which makes it difficult to meet the heat dissipation requirements of the chip under high heat flux density;

[0006] 2. There is a lack of heat dissipation microchannels and water distribution resistance design for large-scale RF arrays, and the flow distribution lacks uniformity design.

[0007] In general, existing patents only consider the design of near-junction heat dissipation structures under a single heat source, and basically do not consider the engineering issues in the near-junction heat dissipation design of large-scale RF arrays. Summary of the invention

[0008] The purpose of the present invention is to provide a high-power radio frequency array three-dimensional heterogeneous microfluidic cooling device. This technical solution aims to address the shortcomings of high-power radio frequency array microfluidic heat dissipation, such as large heat transfer temperature difference within the substrate, uneven coolant flow distribution, and high resistance in the microchannel. According to the flow and heat exchange characteristics in the microchannel, multi-layer substrate materials and microchannels are designed and interconnected to achieve heat expansion level, forced convection heat exchange, and multi-stage water collection and distribution functions, thereby providing a radio frequency array cooling device that achieves high thermal conductivity near-junction heat transfer under high heat flux density, excellent uniform flow and temperature, and low flow resistance water collection and distribution, thereby improving the engineering applicability and reliability of radio frequency array heat dissipation technology to solve the problems raised in the above-mentioned background technology.

[0009] To achieve the above-mentioned objectives, the present invention provides the following technical solutions: a high-power radio frequency array three-dimensional heterogeneous microfluidic cooling device, comprising a microfluidic cooling layer, wherein the microfluidic cooling layer is composed of a diamond substrate layer with microfluidics, a silicon substrate layer with fully parallel water collection and distribution microchannels with tree-shaped branches, and an LTCC substrate layer with parallel co-flow design channels with integrated water collection and distribution functions. An RF chip array is welded on the front side of the diamond substrate layer, the silicon substrate layer is arranged below the diamond substrate layer, the silicon substrate layer includes a silicon substrate final water collection layer and a silicon substrate final water distribution layer connected to each other, wherein the silicon substrate final water collection layer is provided with four groups and they are arranged in an array below the diamond substrate layer, and the silicon substrate final water distribution layer is provided with four groups and they are arranged in an array below the silicon substrate final water collection layer; the LTCC substrate layer is arranged below the silicon substrate layer, and a first opening group and a second opening group are provided on the front side of the LTCC substrate layer, wherein the first opening group has sixteen openings A which are liquid supply ports for the silicon substrate, and the second opening group has eight openings B which are liquid return ports for the silicon substrate.

[0010] Preferably, the back side of the LTCC substrate is welded to connect the liquid inlet interface and the liquid return interface, and the liquid inlet interface and the liquid return interface are connected to an external cooling unit. The external cooling unit outputs the cooling medium from the liquid inlet interface to the microfluidic system. The cooling medium includes but is not limited to deionized water and HFE electronic fluorinated liquid.

[0011] Preferably, two openings C are provided on the back side of the LTCC substrate layer, and the two openings C are respectively the total liquid inlet and the total liquid return port of the microfluidic channel system.

[0012] Preferably, the diamond substrate layer is grown by nucleation from a silicon-based substrate, and the substrate grooves are removed to form the diamond-based microchannels.

[0013] Preferably, the front side of the LTCC substrate and the back side of the silicon substrate layer are bonded by dispensing glue, and the LTCC substrate is formed into an LTCC-based flow channel by 3D printing.

[0014] Preferably, the cooling medium output by the external cooling unit enters the first layer of LTCC substrate through the liquid inlet. The LTCC substrate has a wide flow channel for primary water diversion. The flow channel design section is 4mm*2mm. The wide section ensures lower flow resistance during primary diversion. After primary diversion, it enters the second layer of silicon substrate through the diversion port. The silicon substrate has a precision-machined microchannel for final diversion. The flow channel design section is 1mm*0.3mm. The silicon-based flow channel adopts a full parallel design to ensure uniformity of flow distribution. After the final diversion, it enters the third layer of diamond microchannel through silicon vias. This layer has densely arranged microchannel fins. The design width and spacing of the fins are both 50μm, the fin height is 300μm, and the total length of the microchannel is 3mm.

[0015] Preferably, the RF chip is welded on the front side of the diamond substrate layer. Since diamond has an extremely high thermal conductivity (1200-2000W / m·K), it can provide the chip with excellent thermal expansion capability. The heat expands to the wall of the microchannel, and forced convection heat exchange occurs with the cooling medium in the channel. After the heat exchange, the cooling medium returns to the second-layer silicon substrate for final convergence, and returns to the first-layer LTCC substrate through the convergence hole for primary convergence, and finally flows out of the cooling device through the liquid return port on the back of the LTCC. After the cooling medium undergoes heat exchange in the external heat exchanger, it is pumped back to the liquid inlet of the cooling device to form a cooling cycle.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The high-power RF array microfluidic cooling device provided by the present invention performs flow channel design and multi-layer substrate material arrangement based on the flow and heat exchange characteristics in the microchannel, thereby improving the heat dissipation capacity of the RF array, ensuring the uniformity of near-junction heat dissipation flow distribution, and reducing the overall flow resistance of the cooling system, providing a solution for the engineering application of high-power RF array efficient heat dissipation technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0019] Figure 2 It is a side view of the present invention;

[0020] Figure 3 It is a back view of the present invention;

[0021] Figure 4 This is a schematic diagram of the structure of the diamond microchannel layer of the present invention;

[0022] Figure 5 is a schematic diagram of AA of the present invention;

[0023] Figure 6 is a schematic structural diagram of a silicon substrate layer in an embodiment of the present invention;

[0024] Figure 7 This is a schematic diagram of the front structure of the water collecting and distributing layer of the LTCC substrate in an embodiment of the present invention;

[0025] Figure 8 It is a schematic diagram of the back structure of the water collecting and distributing layer of the LTCC substrate in an embodiment of the present invention;

[0026] Fig. 9 Schematic diagram of the flow channel structure of the primary water collecting and distributing layer of the LTCC substrate in an embodiment of the present invention;

[0027] Fig.10 For the present invention Fig. 9 Cross-section of the primary water diversion channel in the middle BB;

[0028] Fig.11 For the present invention Fig. 9 Cross-section of the primary water collection channel in the middle CC;

[0029] Fig.12 For the present invention Fig. 9 Cross-sectional view of the system inlet and return flow paths of DD.

[0030] In the figure: 1. RF chip array; 2. Diamond substrate layer; 3. Silicon substrate final water collection layer; 4. Silicon substrate final water distribution layer; 5. LTCC substrate layer; 6. Liquid inlet interface; 7. Liquid return interface; 8. Diamond microfluidic channel fin; 9. Diamond-based microfluidic channel; 10. Silicon substrate liquid return hole; 11. Silicon substrate liquid supply hole; 12. First opening group; 13. Second opening group; 14. Total liquid inlet; 15. Total liquid return port. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] In the description of the present invention, it should be noted that the terms "vertical", "up", "down", "horizontal", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0033] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] See also Figure 1-3 The present invention provides a technical solution: a high-power radio frequency array three-dimensional heterogeneous microfluidic cooling device, including a microfluidic cooling layer, wherein the microfluidic cooling layer is composed of a diamond substrate layer 2, a silicon substrate final water collection layer 3, a silicon substrate final water distribution layer 4 and a LTCC substrate layer 5.

[0035] In this embodiment, the array chip 1 is welded or bonded to the front side of the diamond substrate layer 2 (the embodiment refers to the side of all substrates close to the chip as the front side). The diamond substrate layer 2 is formed by nucleation growth of a silicon-based substrate, and the substrate groove is removed to form a diamond-based microchannel. The back of the silicon substrate final water collection layer 3 and the silicon substrate final water separation layer 4 are formed into a silicon-based microchannel by laser dry etching, the back of the silicon substrate final water collection layer 3 and the front of the silicon substrate final water separation layer 4 are connected by silicon-silicon bonding, and the front of the silicon substrate final water collection layer 3 is connected to the silicon-based substrate material on the back of the diamond substrate layer 2 by silicon-silicon and silicon-diamond bonding. The front of the LTCC substrate layer 5 is bonded to the back of the silicon substrate 4 by dispensing glue, and the LTCC substrate layer 5 is formed into an LTCC-based flow channel by 3D printing. The back of the LTCC substrate layer 5 is welded to connect the liquid inlet interface 6 and the liquid return interface 7, and the liquid inlet and return interface is connected to the external cooling unit.

[0036] See also Figure 4-5 The diamond microfluidic substrate preferably has a thickness of 0.5 mm. Figure 4 , Figure 5 The area of ​​the middle microchannel region is slightly larger than the area of ​​the upper chip. This layer of substrate acts as a thermal floor to provide the chip with excellent thermal expansion capability and structural support capability. Diamond microchannel fins 8 are provided on this layer of substrate. The diamond microchannel fins 8 are preferably 350 μm in height and the microchannel is preferably 50 μm in width. The higher aspect ratio can ensure a higher convective heat exchange between the cooling medium and the diamond wall.

[0037] See also Figure 6In this embodiment, the silicon substrate layer is arranged below the diamond substrate layer 2, and the silicon substrate layer includes a silicon substrate final water collection layer 3 and a silicon substrate final water separation layer 4 connected to each other; the thickness of the two silicon substrates (silicon substrate final water collection layer 3 and silicon substrate final water separation layer 4) is preferably 0.5 mm, and the microchannels of the silicon substrate final water collection layer 3 and the silicon substrate final water separation layer 4 adopt a tree-shaped branched full parallel structure. The width of the silicon-based flow channel is preferably 0.5-1.0 mm, and the flow channel height is preferably 0.3 mm. The silicon substrate is precisely processed by photolithography to obtain a microchannel with precisely controllable size, thereby ensuring uniform distribution of flow in each branch pipeline.

[0038] In this embodiment, a silicon substrate liquid return through hole 10 and a silicon substrate liquid supply through hole 11 are provided on the silicon substrate.

[0039] See also Figure 7-12 The thickness of the LTCC substrate layer 5 is preferably 3mm. The flow channel of the primary water collection and distribution layer of the LTCC substrate layer 5 adopts a parallel design to ensure the uniformity of flow distribution and the compactness of the flow channel structure. The height of the LTCC base flow channel is preferably 2mm, and the flow channel width is preferably 2.0-8.0mm. The primary water collection and distribution adopts a wide flow channel design to reduce the extended flow resistance loss. The LTCC substrate has excellent processing and molding capabilities and is easy to form cavities of various structures. The flow channel manufacturing in the substrate can be realized through 3D printing technology to ensure low flow resistance loss of the system.

[0040] In this embodiment, the back side of the LTCC substrate layer 5 is welded to connect the liquid inlet interface 6 and the liquid return interface 7, and the liquid inlet interface 6 and the liquid return interface 7 are connected to an external cooling unit, and the external cooling unit outputs the cooling medium from the liquid inlet interface 6 to the microchannel system.

[0041] In this embodiment, a first opening group 12 and a second opening group 13 are provided on the front side of the LTCC substrate layer 5, wherein the first opening group 12 has sixteen openings / through holes A which are liquid supply ports for the silicon substrate, and the second opening group 13 has eight openings / through holes B which are liquid return ports for the silicon substrate, which are respectively connected to the "four supply and two return" liquid supply and return ports on the bottom surfaces of the four silicon substrates.

[0042] In this embodiment, the cooling medium may be electronic fluoride liquid, and the phase change cooling in the microchannel has a higher cooling efficiency and good compatibility with various materials of the cooling device (diamond, silicon, LTCC).

[0043] In this embodiment, the cooling medium enters the cooling device from the liquid inlet port 6 on the back of the LTCC substrate, and the flow in the LTCC substrate is as follows: Figure 9-12 As shown by the arrows, the water enters the silicon substrate water diversion layer 4 through the 16 through holes A (first opening group 12) on the front side of the LTCC substrate. Figure 6As shown by the arrows, each of the four silicon substrates is evenly divided into 16 branches, and the cooling medium passes through the rectangular through holes in the silicon substrate water collecting layer 3 and enters the diamond substrate layer 2. Figure 4-5 In the process, the cooling medium flows through the diamond-based microchannel 9 to perform forced convection heat exchange, and enters the silicon substrate water collection layer 3 through the diamond-based microchannel 9 and the silicon-based connecting through hole.

[0044] In this embodiment, the silicon substrate has a plurality of converging currents. Figure 6 As shown by the arrows, the 16 branch channels in each of the four silicon substrates merge into two channels and return to the LTCC substrate layer 5 through the silicon substrate liquid return through hole 10. The cooling medium returns to the primary water collection layer from the 8 through holes B (the second opening group 13) on the front side of the LTCC substrate layer 5. The LTCC substrate layer 5 merges into the following channels: Figure 9-12 As shown by the arrow, the liquid leaves the cooling device through the return liquid interface 7 on the back of the LTCC substrate, enters the cooling unit for heat exchange, and then returns to the liquid inlet interface 6 to complete the cycle. The cooling medium in the device circulates to achieve cooling of 64 high-power chip sub-arrays.

[0045] In this embodiment, the first layer of LTCC substrate layer 5 is processed with a primary water collection and distribution channel with low flow resistance, and processes such as stacking encapsulation lamination and low-temperature sintering are adopted; the second layer of silicon base is finely processed by dry etching to evenly distribute the flow of the final water collection and distribution channel; the third layer of diamond microchannel is nucleated and grown on the silicon substrate containing grooves, and the part of the substrate adjacent to the diamond is removed to form a diamond-based microchannel. In terms of multi-layer stacking, the LTCC substrate and the silicon substrate are cured and bonded by epoxy conductive silver glue; the silicon-based shunt and converging channels cannot coexist in the same layer, and the shunt layer and the converging layer are processed by dry etching on two silicon substrates respectively, and the two silicon substrates are silicon-silicon bonded; the substrate of the diamond microchannel layer is a silicon substrate, and silicon-silicon and silicon-diamond heterogeneous bonding is performed with the silicon substrate water collection layer. Through the above processing method, a high-power RF array cooling device of diamond microchannel layer-silicon-based final water collection and distribution layer-LTCC-based primary water collection and distribution layer is finally realized.

[0046] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-power radio frequency array three-dimensional heterogeneous microchannel cooling device, characterized in that: The invention comprises a micro-channel cooling layer, wherein the micro-channel cooling layer is composed of a stack of a diamond substrate layer (2) having micro-channels, a silicon substrate layer having tree-shaped branched fully parallel water collection and distribution micro-channels, and an LTCC substrate layer (5) having parallel same-path design channels with integrated water collection and distribution functions; The diamond substrate layer (2) is welded with a radio frequency chip array (1) on the front side; the silicon substrate layer is arranged below the diamond substrate layer (2); the silicon substrate layer comprises a silicon substrate final water collection layer (3) and a silicon substrate final water distribution layer (4) connected to each other; wherein the silicon substrate final water collection layer (3) is provided with four groups and arranged in an array below the diamond substrate layer (2); and the silicon substrate final water distribution layer (4) is provided with four groups and arranged in an array below the silicon substrate final water collection layer (3); the LTCC substrate layer (5) is arranged below the silicon substrate layer; and a first opening group (12) and a second opening group (13) are provided on the front side of the LTCC substrate layer (5); wherein the first opening group (12) has sixteen openings A which are silicon substrate liquid supply ports, and the second opening group (13) has eight openings B which are silicon substrate liquid return ports.

2. A high-power radio frequency array three-dimensional heterogeneous microchannel cooling device according to claim 1, characterized in that: The back side of the LTCC substrate layer (5) is welded to a liquid inlet interface (6) and a liquid return interface (7), and the liquid inlet interface (6) and the liquid return interface (7) are connected to an external cooling unit, and the external cooling unit outputs a cooling medium from the liquid inlet interface (6) to the microfluidic system, wherein the cooling medium includes, but is not limited to, deionized water and HFE electronic fluorinated liquid.

3. According to claim 1, a high-power radio frequency array three-dimensional heterogeneous microchannel cooling device is characterized in that: The back side of the LTCC substrate layer (5) is provided with two openings C, and the two openings C are respectively a total liquid inlet (14) and a total liquid return port (15) of the microfluidic channel system.

4. A high-power radio frequency array three-dimensional heterogeneous microchannel cooling device according to claim 1, characterized in that: The diamond substrate layer (2) is formed by nucleation growth of a silicon-based substrate, and the substrate grooves are removed to form a diamond-based microchannel (9).

5. The high-power radio frequency array three-dimensional heterogeneous microchannel cooling device according to claim 1, characterized in that: The front side of the LTCC substrate layer (5) and the back side of the silicon substrate layer are bonded by dispensing glue, and the LTCC substrate layer (5) is formed into an LTCC base flow channel by 3D printing.

Images