CN209822624U - Microchannel-nano porous composite structure evaporator - Google Patents

Abstract

A micro-channel-nano porous composite structure evaporator belongs to the technical field of microelectronic device cooling. The substrate stage of the GaN HEMT device is cooled, so that the use of interface bonding materials is reduced, the junction temperature is greatly reduced, and the service life of the GaN HEMT device is prolonged. The application consists of an upper substrate (6) and a lower substrate (5), wherein the upper substrate comprises a nanoporous region (2), a fluid inlet (1) and a fluid outlet (8), and the front side of the lower substrate is decorated with a microchannel region (4), an inlet reservoir (3) and an outlet reservoir (9). The upper substrate (6) and the lower substrate (5) are packaged by adopting a bonding technology, so that the good contact between the nano porous structure region (2) and the micro channel region (4) is ensured. The device utilizes the phase change of liquid in the nanometer hole to evaporate and dissipate heat, and has the characteristics of stable operation, uniform temperature distribution, less required working medium, low operation pressure and the like.

Description

A Microchannel-Nanoporous Composite Structure Evaporator

technical field

The utility model belongs to the technical field of GaN HEMT device substrate-level cooling, and relates to a heat dissipation design of an evaporator with a microchannel-nano porous composite structure.

Background technique

With the development of advanced material manufacturing technology and high-power electronic device performance, Gallium Nitride (GaN) High Electron Mobility Transistor (HEMT) devices are used in various fields such as wireless communication and radar, especially in military and aerospace fields. However, the resulting extremely high heat flux problem limits the power of GaN HEMT devices to one-tenth of their potential power output in order to maintain acceptable junction temperatures and prolong device lifetime. GaN HEMT devices produce submillimeter hot spots of 5kW/cm ² on a plane area of 5-10mm ² , with multiple hot spots distributed, and the background heat flow on the entire substrate also reaches 1kW/cm ² . Therefore, a novel and efficient heat dissipation device is needed to solve the heat dissipation of GaN HEMT devices, so as to effectively reduce the junction temperature.

At present, the heat dissipation devices being actively researched at home and abroad include: micro heat pipe heat dissipation, micro heat spreader, micro channel heat sink, thermoelectric refrigeration technology and integral micro cooler, etc. However, these traditional heat dissipation methods mostly use solid heat dissipation with high thermal conductivity. Devices (copper, copper compounds and diamond, etc.) and thermal interface materials (solder and epoxy resin), combined with air cooling or liquid cooling, to achieve the purpose of heat dissipation. A new type of integral cooling evaporator in the device removes heat at the substrate level instead of at the package level of the device, thereby eliminating the use of interface bonding materials, greatly reducing the thermal resistance of the device, thereby reducing the junction temperature. Therefore, designing a phase-change evaporator on a device substrate can substantially improve the performance and reliability of GaN HEMT devices. A micro-nano composite structure evaporator is formed by combining micro-channels and nano-porous structures. This evaporator device combines the advantages of flow boiling and pool boiling, which not only meets the heat dissipation requirements of high heat flux density, but also does not cause boiling instability. , and the capillary force of the system in the nanopore is small, which greatly reduces the consumption of pump work, and becomes an ideal heat dissipation structure of the evaporator.

Aiming at the characteristics of high heat flux density and multi-heat zone distribution of GaN HEMT devices, the utility model proposes a substrate-level microchannel-nano-porous composite structure evaporative heat sink to achieve uniform temperature distribution, stable operation, and reduce GaN HEMT The operating junction temperature of the device has the effect of extending its service life.

Utility model content

The purpose of this utility model is to provide an evaporator with a microchannel-nanoporous composite structure, which is used to solve the problems of high heat flux density and multi-heat zone distribution of GaN HEMT devices, and provide reliable junction temperature for its safe and stable operation. .

The utility model designs a novel GaN HEMT device substrate-level microchannel-nanoporous composite evaporator cooling device, which is characterized in that: etching is carried out on the GaN HEMT device substrate, eliminating the use of interface bonding materials, as shown in the figure As shown in 9; including an upper substrate (6) and a lower substrate (5) that fit together up and down; the center of the upper substrate (6) is provided with a plurality of nanoporous structure regions (2), and a plurality of nanoporous structure regions (2) The opposite sides are respectively provided with a fluid inlet (1) and a fluid outlet (8), and both the fluid inlet (1) and the fluid outlet (8) are through holes connected to the external liquid supply pipeline; the nanoporous is nanometer An array of through holes; the nano through holes are the upper and lower sides of the upper substrate (6), that is, the inner and outer communication holes;

The upper surface of the lower substrate (5) is surrounded by a flat and smooth area, the center of the upper surface is provided with a groove, and the center of the groove is provided with a plurality of microchannel regions (4), and the plurality of microchannel regions (4) are arranged in parallel and in series , the two sides of a plurality of microchannel areas (4) in the groove are the inlet liquid storage tank (3) and the outlet liquid storage tank (9), and each microchannel area (4) is connected with the inlet liquid storage tank (3) It communicates with the outlet reservoir (9), the inlet reservoir (3) communicates with the fluid inlet (1) of the upper substrate (6), and the outlet reservoir (9) communicates with the fluid outlet (8) of the upper substrate (6). ) communicate with each other, and the microchannel region (4) of the lower substrate (5) corresponds to the nanoporous structure region (2) of the upper substrate (6);

The microchannel area (4) is a plurality of microchannels arranged side by side, provided that the direction of the channel is along the AB direction, then a plurality of microchannels are arranged side by side along the CD direction perpendicular to the AB direction, and a plurality of microchannel areas (4 ) are arranged along the AB direction; the nanoporous structure region (2) is in direct contact with the microchannel region (4) up and down, and the nano-through hole diameter of the preferred nanoporous structure region (2) is less than the width of the microchannel and between two adjacent microchannels The interval dimension is the thickness dimension, and the minimum interval between two nanometer through holes is smaller than the width of the microchannel and the interval dimension between two adjacent microchannels is the thickness dimension.

The top surface of the microchannel area (4) of the entire evaporator cooling device is flush with the top surface of the area around the lower substrate (5), the bottom surface of the nanoporous structure area (2) is flush with the bottom surface of the upper substrate (6), and the nanometer porous structure area (2) is flush with the bottom surface of the upper substrate (6). The thickness of the porous structure region is also on the order of nanometers. The upper substrate (6) and the lower substrate (5) are welded together by encapsulation and bonding technology, and the microchannel region (4) and the nanoporous structure region (2) are also closely bonded, ensuring the airtightness and good contact of the entire device.

The distribution position and area size of the cooling device of the new GaN HEMT device substrate-level microchannel-nanoporous composite evaporator proposed by the utility model can be determined according to the specific size of the device. In order to clarify the structure of the upper and lower substrates, Fig. 1 and Fig. 2 respectively give the top views of the upper substrate (6) and the lower substrate (5).

In the utility model, the liquid enters the inlet liquid storage tank (3) of the lower substrate (5) through the fluid inlet (1) of the upper substrate (6), then flows through the microchannel region (4), and finally enters the nanoporous structure region (2), the heat source of the entire evaporator is transferred to the nanoporous structure area (2) through heat conduction, and the nanoporous structure area (2) is vertically corresponding to the position of the bottom hot zone; the evaporation of liquid occurs in the nanoporous structure area (2) During the phase change process, the heat from the heat source is taken away and dissipated into the condenser. The excess liquid reaches the fluid outlet (8) through the outlet liquid storage tank (9), and then enters the circulation pump again. The size of the condenser in the circulation system can be adjusted according to actual needs. Regulation, the schematic diagram of the circulatory system is shown in Figure 8.

The fluid working medium can be selected from air, water, refrigerant or other insulating dielectric fluid, and the material of the system device can be selected from silicon and silicon compounds.

The utility model has the following advantages and effects:

1. In the utility model, the liquid enters the inlet liquid storage tank (3) of the lower substrate (5) from the liquid inlet (1) of the upper substrate (6), flows through the microchannel (4), and part of the liquid is in the nanoporous The structural area (2) evaporates, and another part of the liquid passes through the microchannel (4) and reaches the outlet liquid storage tank (9), so that the temperature distribution on the bottom surface of the lower substrate (5) is more uniform, and the temperature is effectively reduced.

2. Utilize the thin film evaporation phenomenon in the nanopore and the latent heat of vaporization of the liquid to achieve heat dissipation at the substrate level of the GaN HEMT device and reduce the junction temperature.

3. Satisfy the characteristics of high heat flux density and multi-hot zone distribution of GaN HEMT devices, and the amount of evaporation can be self-adjusted under the action of capillary force according to the magnitude of heat flux.

4. The liquid is always in the state of evaporation in the nanoporous structure, and there will be no boiling phenomenon, so that the entire evaporator can operate safely and stably.

5. Due to the capillary force of the nanoporous structure, the consumption of pump work is greatly reduced, thereby effectively reducing the utilization of energy.

6. The existence of microchannels can support and protect the nanoporous structure, making the nanostructures less prone to damage. At the same time, the flow and liquid supply of the microchannels will also reduce the probability of contamination of the nanostructures to a certain extent. .

Description of drawings

Fig. 1 is the top view of the upper substrate of the composite structure of the present invention;

In the figure: 1. liquid inlet, 2. nanoporous structure area, 6. upper substrate, 8. liquid outlet.

Fig. 2 is a top view of the lower substrate of the composite structure of the present invention;

In the figure: 3, inlet liquid storage tank, 4, microchannel area, 5, lower substrate, 9, outlet liquid storage tank.

Fig. 3 is a schematic diagram of the overall structure of the utility model.

In the figure: 1. Liquid inlet, 2. Nanoporous structure area, 3. Inlet liquid storage tank, 4. Microchannel area, 5. Lower substrate, 6. Upper substrate, 8. Liquid outlet, 9. Outlet liquid storage tank.

Fig. 4 is a bottom schematic diagram of the cooling device of the present invention.

In the figure: 7. GaN HEMT device or heating film.

Fig. 5 is the A-A sectional view of the overall structure of the utility model device and its partial enlarged view.

Figure 6 shows the detailed dimensions of microchannels and nanoporous structures (not to scale, in um).

Fig. 7 is a schematic diagram of a specific processing technique of the present invention.

Fig. 8 is a schematic diagram of the principle of the large condenser in the circulation system of the present invention.

Fig. 9 is a schematic diagram of the principle of the small condenser in the circulation system of the utility model.

Fig. 10 is a schematic diagram of a GaN HEMT device and the position of an evaporator.

Detailed ways

The utility model will be further described below in conjunction with the accompanying drawings and the application of the microchannel-nanoporous composite structure evaporator in GaN HEMT devices; but the utility model is not limited to the following examples.

The core idea of the utility model is: the etching is performed on the GaN HEMT device substrate, which saves the use of interface bonding materials and reduces the junction temperature. The liquid enters the inlet liquid storage tank 3 of the lower substrate 6 through the through hole of the liquid inlet 1, and then flows through the microchannel area 4. Part of the liquid enters the nanoporous structure area 2 from the microchannel area 4, and the other part flows into the outlet liquid storage tank 9. The heat is transferred to the nanoporous structure area 2 through the heat conduction of the wall surface of the microchannel, and the inflowing liquid undergoes a phase change through evaporation to take away the heat in the porous area, so as to achieve the purpose of heat dissipation. Utilize the effect of condenser and micropump for recycling.

Etching on the GaN HEMT device substrate eliminates the use of interface bonding materials and reduces the junction temperature. Including an upper substrate 6 and a lower substrate 5; the center of the upper substrate 6 is a nanoporous structure region 2, and the two sides of the nanoporous structure region 2 are respectively a fluid inlet 1 and a fluid outlet 8, and both the fluid inlet 1 and the fluid outlet 8 are through holes , connected to the external liquid pipeline; the front of the lower substrate 5 is surrounded by a flat and smooth area, the center of the front is a microchannel area 4, a plurality of microchannel areas 4 are parallel and side by side, and the left and right ends are the inlet liquid storage tank 3 and the outlet The liquid storage tank 9, the micro channel communicates with the part between the two liquid storage tanks, the inlet liquid storage tank 3 and the fluid inlet 1 of the upper substrate 6 communicate with each other, and the outlet liquid storage tank 9 and the fluid outlet 8 of the upper substrate 6 communicate with each other Throughout, the microchannel region 4 of the lower substrate 5 corresponds vertically upward to the nanoporous structure region 2 of the upper substrate 6 . The upper substrate 6 and the lower substrate 5 are packaged together by bonding technology, which ensures good airtightness of the whole device.

The top surface of the microchannel region 4 is flush with the surface of the top surface region around the lower substrate 5 .

The bottom of the nanoporous structure region 2 is flush with the bottom of the upper substrate 6 , and the thickness of the nanoporous structure region 2 is also on the order of nanometers.

The nanoporous structure region 2 is in close contact with the microchannel region 4 and has the same overall apparent area. The nanoporous structure region 2 is located on the upper side of the microchannel region 4 and is vertically corresponding to the position of the bottom hot zone.

The channel wall thickness of the microchannel area 4 is about 5um, and the channel width is about 20um, which not only ensures the support and protection of the channel for the nanoporous structure area 2, but also satisfies sufficient liquid supply channels, making the overall device structure more stable and efficient.

The liquid enters the inlet liquid storage tank 9 of the lower substrate 5 through the fluid inlet 1 of the upper substrate 6, and then flows through the microchannel region 4, and part of the liquid enters the nanoporous structure region 2, where the evaporation phase transition process of the liquid occurs, bringing The heat of the device is dissipated to the surrounding environment, and another part of the liquid passes through the microchannel area 4 and reaches the outlet liquid storage tank 9 .

The heat source introduces heat into the nanoporous structure region 2 through the heat conduction effect of the wall surface of the microchannel region 4 , and an evaporation phase transition occurs in the nanoporous region, thereby achieving the purpose of heat dissipation.

The size of the condenser of the whole circulation system can choose whether to use a compressor to reduce the size of the condenser according to the needs of the actual heat dissipation area.

Example 1

With the development of the performance of high-power electronic devices, GaN HEMT devices are widely used, because the cost of electronic equipment is too high, so in the utility model, the way of heating the film of the platinum-coated layer on the bottom surface of the lower substrate 6 is used to simulate the actual electronic device Fever, as shown in Figure 4. In practical applications, the overall area and position of the microchannel and nanoporous region can be changed according to the size of the GaN HEMT device and the distribution characteristics of the hot zone. In this example, the specific structural size of the microchannel, as well as the pore size and interval size of the nanoporous 6. The wall thickness of the microchannel is 5um, the channel width is 20um, the upper and lower height of the channel is 20um, the diameter of the nanopore is 0.1um, the interval is 0.2um, and the upper and lower thickness is 0.4um.

The utility model uses silicon as the material, and the thickness of the silicon wafer is 150um. The substrate is processed by MEMSMicro-Electromechanical System and NEMSNano-Electromechanical System technology. The schematic diagram of the specific processing and bonding process is shown in Figure 7. In the figure, a-1 and b-1 are both initial silicon substrates, and the liquid inlet 1 and liquid outlet 8 of the upper substrate 6 and the thickness of the porous area are respectively etched by ion etching, as shown in b-2 of FIG. 7 ; At the same time, the microchannels and the inlet and outlet reservoirs of the lower substrate 5 are etched, as shown in a-2 of FIG. 7 . Then electron beam lithography is used for the reduced thickness region of b-2 in FIG. 7 to obtain a nanoporous structure, as shown in b-3 of FIG. 7 . Then a-2 and b-3 in Figure 7 are packaged together by silicon-silicon bonding technology. At this time, the fluid inlet 1 and the fluid outlet 8 of the upper substrate 6 are respectively connected with the inlet liquid storage tank 3 and the outlet liquid storage tank of the lower substrate 5. Groove 9 just opposite. The bottom of the packaged device is coated with a 0.1um Pt heating layer 7 by magnetron sputtering technology, and two electrodes are drawn out to connect the circuit, so far the manufacturing process of the entire experimental evaporator is completed.

Using insulating fluid as the working medium, the liquid enters the inlet liquid storage tank 3 from the liquid inlet 1, and then flows through the microchannel area 4. A part of the fluid in the nanoporous structure area 2 undergoes a phase change and evaporates, and the other part flows through the microchannel area 4 and enters the outlet storage tank. Tank 9. Heat is introduced into the porous structure by the heating film 7 at the bottom of the lower substrate 5 through micro-channels, and then the heat is taken away by the phase change of the liquid in the pores. Heating the bottom surface of the lower substrate 5 has good temperature uniformity at various positions, which meets the heat dissipation requirements of the GaN HEMT device, reduces the junction temperature, and prolongs the service life of the device. The size of the condenser of the entire circulation system can be adjusted according to actual needs, and the schematic diagrams of the system are shown in Figures 8 and 9.

To sum up, the above are only preferred embodiments of the present utility model, and are not intended to limit the protection scope of the present utility model. All modifications and improvements made within the spirit and principles of the present utility model shall be included in the protection scope of the present utility model.

Claims (8)

1. A microchannel-nano porous composite evaporator is characterized in that the microchannel-nano porous composite evaporator is a GaN HEMT device substrate-level microchannel-nano porous composite evaporator, and comprises an upper substrate (6) and a lower substrate (5) which are vertically matched together; the center of the upper substrate (6) is provided with a plurality of nano porous structure areas (2), two opposite sides of the plurality of nano porous structure areas (2) are respectively provided with a fluid inlet (1) and a fluid outlet (8), and the fluid inlet (1) and the fluid outlet (8) are through holes and are connected with an external liquid supply pipeline; the nano-porous is a nano-through hole array; the nano through holes are communicated with the upper substrate (6) and the lower substrate (6) in an internal and external mode;

the periphery of the upper surface of a lower substrate (5) is a flat and smooth area, a groove is formed in the center of the upper surface, a plurality of micro-channel areas (4) are arranged in the center of the groove in parallel and in series, an inlet liquid storage tank (3) and an outlet liquid storage tank (9) are respectively arranged on two sides of each of the plurality of micro-channel areas (4) in the groove, each micro-channel area (4) is communicated with the inlet liquid storage tank (3) and the outlet liquid storage tank (9), the inlet liquid storage tank (3) is communicated with a fluid inlet (1) of the upper substrate (6), the outlet liquid storage tank (9) is communicated with a fluid outlet (8) of the upper substrate (6), and the micro-channel areas (4) of the lower substrate (5) correspond to the nano-porous structure areas (2) of the upper substrate (6) one by one;

the top surface of a micro-channel region (4) of the whole evaporator heat dissipation device is flush with the top surfaces of the peripheral regions of the lower substrate (5), the bottom surface of the nano porous structure region (2) is flush with the bottom surface of the upper substrate (6), and the thickness of the nano porous structure region is in the nano level; the upper substrate (6) and the lower substrate (5) are welded together by adopting an encapsulation bonding technology, and the micro-channel region (4) and the nano porous structure region (2) are also tightly combined.

2. A microchannel-nanoporous composite structure evaporator according to claim 1, wherein the microchannel region (4) is formed by arranging a plurality of microchannels in parallel, and the direction of the arranged microchannels is along the AB direction, and the plurality of microchannels are arranged in parallel along the CD direction perpendicular to the AB direction, and the plurality of microchannel regions (4) are arranged along the AB direction; the nano porous structure area (2) is directly contacted with the micro channel area (4) up and down.

3. A microchannel-nanoporous composite structured evaporator according to claim 1 wherein the diameter of the nanopores in the nanoporous structured region (2) is less than the width of the microchannel and the dimension of the space between two adjacent microchannels, i.e. the thickness dimension, and the minimum space between two nanopores is less than the width of the microchannel and the dimension of the space between two adjacent microchannels, i.e. the thickness dimension.

4. A microchannel-nanoporous composite evaporator according to claim 3 wherein the microchannel region has a channel wall thickness of 5 μm and a channel width of 20 μm.

5. A microchannel-nanoporous composite structured evaporator according to claim 1, wherein the top surface of the microchannel region (4) of the entire evaporator heat sink is flush with the top surface of the peripheral region of the lower substrate (5), the bottom surface of the nanoporous structured region (2) is flush with the bottom surface of the upper substrate (6), and the thickness of the nanoporous structured region is also in the order of nanometers.

6. A microchannel-nanoporous composite structured evaporator according to claim 1, wherein the upper substrate (6) and the lower substrate (5) are welded together by encapsulation bonding technique, and the microchannel region (4) and the nanoporous structure region (2) are also tightly combined, ensuring good tightness and contact of the whole device.

7. A microchannel-nanoporous composite structured evaporator according to claim 1 wherein the liquid enters the inlet header (3) of the lower substrate (5) through the fluid inlet (1) of the upper substrate (6), passes through the microchannel region (4) and finally enters the nanoporous structured region (2), the heat source of the entire evaporator is transferred to the nanoporous structured region (2) by conduction, and the nanoporous structured region (2) is positioned vertically with respect to the bottom hot zone; the evaporation phase change process of the liquid occurs in the nano porous structure area (2), the heat of a heat source is taken away, the heat is dissipated to a condenser, and the redundant liquid reaches a fluid outlet (8) through an outlet liquid storage tank (9) and enters the circulating pump again.

8. A microchannel-nanoporous composite structure evaporator according to claim 1, wherein the upper substrate (6) and the lower substrate (5) are etched on a GaN HEMT device substrate.