CN101645430B - Chip cooling device - Google Patents

Abstract

The invention discloses a chip cooling device, which comprises a cooling chamber located at the bottom of the device and matched with the chip, a cooling liquid pool storing cooling liquid, a first micro-channel, a first micro-pump, a second micro-channel, micronozzle, the third microchannel, the second micropump, the fourth microchannel, the condenser and the microhole; The micro-channel communicates with the micro-nozzle; the micro-nozzle is arranged above the cooling chamber and communicates with the cooling chamber; one end of the second micro-pump communicates with the cooling chamber through the third micro-channel, and the other end passes through the fourth micro-channel It is connected with the condenser; the condenser is located above the cooling liquid pool, and the inside of the condenser is provided with a condensing flow channel, and the top of the condensing flow channel is provided with cooling fins, and the condensing flow channel and the cooling liquid pool are connected through micropores. The invention has small volume, high heat dissipation efficiency, high controllability and working flexibility, and can meet the cooling requirements of chips under different working conditions.

Description

Chip Cooler

technical field

The invention relates to a chip cooling device, in particular to a chip cooling device for cooling high-density and high-power chips using micro-electromechanical system technology.

Background technique

The current chip cooling devices mostly use external heat sinks and fans. These two chip cooling devices remove the heat from the chip through convective heat transfer of the air. Higher, take the fan cooling device used by the computer CPU as an example. When the fan blades rotate at a speed of up to 4000r/min, the temperature of the CPU can be basically prevented from being too high, but the device is very noisy, and the heat dissipation capacity has reached air convection heat transfer limit. With the rapid development of microelectronics technology, factors such as more complex integrated functions of a single chip, rapid increase of clock frequency, thinner package, reduced pin pitch of package, and reduced number of pins of package lead to the continuous trend of single chip to high power With the development of miniaturization, the traditional cooling method can no longer meet the heat dissipation requirements of single chip and chipset. When the operating frequency of the chip reaches above 800MHz, the maximum power can reach 100W, and the average heat flux density between the shell and the cooling device can reach above 7.1W/ ^cm2 . When the system uses a large number of high-power chips, use heat sink or fan to control The temperature of the chip can only be around 100°C, and the temperature that usually ensures the normal operation of the chip is around 60°C.

It can be seen that the thermal control problem of high-density and high-power chips has become more and more prominent, and in some fields of optoelectronic communication equipment, nuclear and electrical control equipment, etc., there are also many thermal control problems that need to be solved urgently. The key to this problem is to seek an efficient heat transport method for high-density heat sources in different chips. Since the convective heat transfer efficiency of liquid is higher than that of gas, an immersion liquid cooling device has appeared at present. The upper surface of the chip is in direct contact with the heat sink, and the other side of the heat sink is immersed in water, and the liquid circulates under the action of an external pump. , so that the heat of the chip is transported to the atmosphere. Although the device has a good cooling effect, it takes up a large space and affects the subsequent integration and packaging of the chip.

Contents of the invention

The object of the present invention is to solve the above-mentioned shortcomings in the existing chip cooling device and provide a chip cooling device with high heat dissipation efficiency.

The technical solution adopted by the present invention is: the chip cooling device mainly includes a cooling liquid pool, a first micro-channel, a first micro-pump, a second micro-channel, a micro-nozzle, a cooling chamber, a third micro-channel, a second micro-channel pump, the fourth microchannel, condenser and microholes, the coolant pool stores coolant; one end of the first micropump communicates with the coolant pool through the first microchannel, and the other end of the first micropump The second micro flow channel communicates with the micro nozzle; the cooling chamber is located at the bottom of the chip cooling device and matches the chip; the micro nozzle is located above the cooling chamber and communicates with the cooling chamber; the second One end of the second micropump communicates with the cooling chamber through the third microchannel, and the other end of the second micropump communicates with the condenser through the fourth microchannel; A condensing channel is arranged inside, and a cooling fin is arranged on the top of the condensing channel, and the condensing channel communicates with the cooling liquid pool through micropores.

Further, the first micropump of the present invention is provided with an elastic pump membrane.

Further, the second micropump of the present invention is provided with an elastic pump membrane.

Further, the micro-nozzles in the present invention are micro-nozzle arrays evenly arranged in a rectangular array.

Further, the microwells in the present invention are microwell arrays uniformly arranged in a rectangular array.

When in use, the chip cooling device of the present invention is installed on the surface of the chip, that is, the chip is placed in the cooling chamber, and at the same time, the micro nozzle is facing the upper surface of the chip. Since the cooling chamber matches the chip, after the chip is placed in the cooling chamber, the cooling chamber is isolated from the external atmosphere through the chip, and the cooling chamber has good sealing performance relative to the external atmosphere. A cycle process of cooling the chip by the chip cooling device is as follows: the cooling liquid in the cooling liquid pool is driven by the first micro-pump, flows into the micro-nozzle through the first micro-channel and the second micro-channel, and flows into the micro-droplet The cooling liquid is sprayed into the cooling chamber from the micro-nozzle in the form of cooling liquid, and since the cooling chamber is located directly above the upper surface of the chip, the micro-droplet cooling liquid directly impacts on the upper surface of the heating chip; The effective control of the frequency makes the ejected micro-droplet cooling liquid form a film of appropriate thickness on the upper surface of the chip, and directly completes the mass and energy transfer between the liquid and gas on the solid-liquid interface, so that the contact thermal resistance of the interface reaches Minimum, high critical heat flux values are obtained without the influence of boiling initial hysteresis, so that the surface temperature of the chip can be maintained near the saturation temperature value of the coolant at system pressure, and the temperature distribution of the hot surface of the chip is uniform The cooling liquid boils on the upper surface of the chip, absorbs the heat of the chip in the cooling chamber and changes from a liquid state to a gaseous state, and the gaseous cooling liquid flows into the condenser through the third micro-channel and the fourth micro-channel driven by the second micro-pump , by effectively controlling the vibration amplitude and frequency of the second micropump pump membrane, to ensure that the gaseous cooling liquid generated in the cooling chamber flows into the condenser in time, thereby ensuring the smooth cooling cycle in the closed space; inside the condenser there is The ring-shaped condensing channel, and the evenly distributed fin-shaped fins on the top of the condenser are in contact with the atmospheric environment, which can ensure that the gaseous cooling liquid can fully dissipate heat in the condensing channel; because the boiling point of the cooling liquid is lower than the ambient temperature, the gaseous cooling liquid is condensed The heat released in the flow channel condenses into liquid cooling liquid, and the liquid cooling liquid passes through the micropores under the annular condensing flow channel to form droplets and flow back to the cooling liquid pool, completing a cooling cycle in a closed space.

In summary, compared with the existing chip cooling device, the chip cooling device of the present invention has the following advantages:

1. The chip cooling device of the present invention integrates the micropump as the driving source of the cooling liquid on the surface of the chip, which makes it possible to reduce the space occupied by the cooling device, and utilizes the bulk micromachining process and surface micromachining process in the microelectromechanical system technology. Layer etching, removal of the sacrificial layer, and then through the reversible anode bonding process, the cooling device is packaged layer by layer on the surface of the electronic device chip to achieve effective coupling and efficient matching, reducing the occupied space and reducing the subsequent integration of the chip. and encapsulation negatively.

2. The chip cooling device of the present invention adopts a closed internal circulation cooling method, controls the formation and injection of micro-droplets through the first micropump, and realizes the recovery and reuse of gas through the second micropump. The entire circulation process does not require manual intervention, and It has high controllability and working flexibility to meet the cooling requirements of chips under different working conditions.

3. The chip cooling device of the present invention impacts the hot surface of the chip through the micro-droplet cooling liquid to form a thin film to obtain a very high critical heat flux value, and utilizes the two-phase heat conduction technology that the liquid is vaporized in the high temperature area and the gas is condensed in the low temperature area, That is, the phase change latent heat characteristic of the cooling liquid realizes the temperature control of high-density and high-power chips. Compared with the traditional free convection heat transfer, forced convection heat transfer and immersion cooling method, cooling by liquid phase change mechanism is a more efficient cooling method, and the micro-surface spray boiling cooling involved in the present invention has a higher performance of up to ( The critical heat flux value of 500-600) W/cm ² can fully meet the cooling requirements of existing high-density and high-power chips, and can even solve the thermal control problems that must be faced in chip development for a long time in the future.

Description of drawings

Fig. 1 is a partial cross-sectional schematic diagram of an embodiment of the present invention;

Fig. 2 is a working principle diagram of the present invention;

in:

1. Coolant pool, 12. First microchannel, 2. First micropump, 21. First micropump pump membrane, 23. Second microchannel, 3. Micronozzle, 3a. Microdroplet state cooling liquid, 4. cooling chamber, 4a. thin film, 46. the third microchannel, 6. the second micropump, 61. the second micropump pump membrane, 67. the fourth microchannel, 7. condenser, 71. Condensation channel, 72. Fin-shaped heat sink, 8. Microhole, 8a. Droplet, 9. Chip.

Detailed ways

The chip cooling device of the present invention will be described below with reference to the accompanying drawings.

代表液态冷却液的流动方向，箭头符号

代表气态冷却液的流动方向。本发明芯片冷却装置主要包括冷却液池1、第一微流道12、第一微泵2、第二微流道23、微喷嘴3、冷却室4、第三微流道46、第二微泵6、第四微流道67、冷凝器7、微孔8。冷却液池1存储有冷却液(图中未示出)。冷却液要求具有良好的热物理性能、电气性能，并且对芯片具有缓蚀性、安全性及稳定性。热物理性能包括合适的沸点温度，较高的汽化潜热和比热，密度较大，粘度较小。其中沸点要求在室温与芯片能保持正常工作的最高温度之间，通常沸点在40℃～60℃。电气性能主要指绝缘性和兼容性，总体要求是不致影响芯片的寿命和性能。安全性和稳定性主要指无毒、无刺激性、不燃、不溶于水、不易分解、不污染环境等。目前市场上常用的碳氟化合物能很好地满足上述要求，例如在本实施方式中，使用的冷却液为碳氟化合物中的FC-72，FC-72在一个标准大气压下的沸点为56.6℃。Please refer to Figure 1 and Figure 2, where the arrow symbol in Figure 2

Represents the flow direction of liquid coolant, the arrow symbol

Indicates the flow direction of the gaseous coolant. The chip cooling device of the present invention mainly includes a cooling liquid pool 1, a first micro-channel 12, a first micro-pump 2, a second micro-channel 23, a micro-nozzle 3, a cooling chamber 4, a third micro-channel 46, a second micro-channel Pump 6 , fourth microchannel 67 , condenser 7 , and micropore 8 . The cooling liquid pool 1 stores cooling liquid (not shown in the figure). Coolant is required to have good thermophysical properties, electrical properties, corrosion inhibition, safety and stability for chips. Thermophysical properties include suitable boiling point temperature, higher latent heat of vaporization and specific heat, higher density and lower viscosity. Among them, the boiling point is required to be between room temperature and the highest temperature at which the chip can maintain normal operation, and usually the boiling point is between 40°C and 60°C. Electrical performance mainly refers to insulation and compatibility, and the general requirement is not to affect the life and performance of the chip. Safety and stability mainly refer to non-toxic, non-irritating, non-flammable, insoluble in water, difficult to decompose, and non-polluting to the environment. Fluorocarbons commonly used in the market can well meet the above requirements. For example, in this embodiment, the cooling liquid used is FC-72 in fluorocarbons. The boiling point of FC-72 at a standard atmospheric pressure is 56.6°C .

In this embodiment, the first micropump 2 is a valveless liquid micropump with an elastic pump membrane capable of reciprocating vibration, that is, the first micropump pump membrane 21, and one end of the first micropump 2 passes through the first microflow The channel 12 communicates with the cooling liquid pool 1, and the other end communicates with the micro nozzle 3 through the second micro channel 23. Under the reciprocating vibration of the first micro pump membrane 21, the cooling liquid in the cooling liquid pool 1 passes through the A micro-channel 12 and a second micro-channel 23 flow into the micro-nozzle 3, and are sprayed out from the micro-nozzle 3 in the form of micro-droplet cooling liquid 3a, that is, injected into the cooling chamber 4 communicated with the micro-nozzle 3 . In this embodiment, there may be a plurality of micro-nozzles 3, which are evenly arranged in the form of a rectangular array above the cooling chamber 4 to form a micro-nozzle array, which can better ensure the spraying of micro-droplet cooling liquid 3a. Uniformity. Certainly, the micro-nozzles 3 of the chip cooling device of the present invention may also be arranged not in a rectangular array, but in other appropriate ways. The cooling chamber 4 is positioned at the bottom of the chip cooling device, and the size of the cooling chamber 4 at the position where the chip 9 is installed matches the chip 9, so that after the chip 9 is placed in the cooling chamber 4, the cooling chamber can be closed by the chip 9. 4 is isolated from the external atmospheric environment, and makes the cooling chamber 4 have good sealing performance relative to the external atmospheric environment. If micronozzle 3 is arranged on the top of cooling chamber 4, then it can be ensured that micronozzle 3 can face the upper surface of chip 9, so that the micro-droplet state cooling liquid 3a ejected from micronozzle 3 is effectively impacted on the chip. 9 on the upper surface. The micro-droplet cooling liquid 3a forms a thin film 4a on the upper surface of the chip 9, and boils in the cooling chamber 4, and turns into a gaseous state to take away the heat of the chip 9.

In this embodiment, the second micropump 6 is a valveless gas micropump with an elastic pump membrane capable of reciprocating vibration, that is, the second micropump pump membrane 61, and one end of the second micropump 6 passes through the third microflow The channel 46 communicates with the cooling chamber 4, and the other end communicates with the condenser 7 through the fourth micro-channel 67. Under the reciprocating vibration of the second micro-pump pump membrane 61, the gaseous cooling liquid in the cooling chamber 4 passes through the third micro-pump. The flow channel 46 and the fourth micro channel 67 flow into the condenser 7 . The condenser 7 is located above the cooling liquid pool 1, and the inside of the condenser 7 is provided with an annular condensing flow channel 71, and the top of the condensing flow channel 71 is provided with evenly distributed fin-shaped fins 72 to ensure that the gaseous cooling liquid flows in the condenser. 7. The condensing flow channel 71 inside 7 fully dissipates heat. The condensing flow channel 71 communicates with the cooling liquid pool 1 through the micropore 8 below it. The gaseous cooling liquid condenses into a liquid cooling liquid in the condensing flow channel 71 and releases heat to the atmosphere. environment, the liquid cooling liquid passes through the micropore 8 to form droplets 8a and flow back to the cooling liquid pool 1 . Microholes 8 can have a plurality, and are evenly arranged above the cooling liquid pool 1 in the form of a rectangular array to form a microhole array, which can better ensure that the liquid droplets 8a flow back to the cooling liquid pool 1 in time to ensure Smooth cooling circulation in enclosed spaces. Of course, the microholes 8 of the chip cooling device of the present invention may not be arranged in a rectangular array, but in other appropriate ways.

As shown in Figures 1 and 2, the chip cooling device of the present invention is installed on the surface of the chip 9 when in use, and the micro nozzle 3 is facing the upper surface of the chip 9. In addition, it is necessary to ensure that the cooling chamber 4 is relatively external to the atmospheric environment. Has good sealing. A cyclical process in which the chip cooling device cools the chip 9 is as follows: under the reciprocating vibration of the first micropump pump membrane 21, the coolant stored in the coolant pool 1 flows into the micronozzle 3, and flows into the first micropump pump membrane. Under the action of the liquid pressure generated by 21, the micro-droplet cooling liquid 3a is formed through the micro-nozzle 3, and is sprayed into the cooling chamber 4 from the micro-nozzle 3, and the micro-droplet cooling liquid 3a finally impacts on the upper surface of the heating chip 9; Through the effective control of the vibration amplitude and frequency of the pump membrane 21 of the first micropump, the sprayed micro-droplet cooling liquid 3a forms a thin film 4a of appropriate thickness on the upper surface of the chip 9, thereby forming a thin film 4a on the solid-liquid interface. The mass and energy transfer between the liquid and gas is directly completed, so that the contact thermal resistance of the interface is minimized, and a high critical heat flux value is obtained, without the influence of the initial hysteresis of boiling, so that the surface temperature of the chip 9 can be kept at a cool The liquid is near the saturation temperature value under the system pressure, and the temperature distribution of the hot surface of the chip 9 is uniform. The cooling liquid boils on the upper surface of the chip 9, absorbs the heat of the chip 9 in the cooling chamber 4 and changes from a liquid state to a gaseous state. The effective control of the vibration amplitude and frequency of the pump membrane 61 of the second micropump can ensure that the gaseous cooling liquid flows into the condenser 7 in time, so as to ensure the smoothness of the entire cooling cycle. The evenly distributed fin-shaped cooling fins 72 on the top of the condenser 7 are in contact with the atmospheric environment. Since the boiling point of the cooling liquid FC-72 is 56.6°C, which is higher than the ambient temperature (usually lower than 40°C), the gaseous cooling liquid in the condenser 7 The internal condensation channel 71 condenses into liquid coolant and releases heat to the atmosphere. The condensed liquid coolant passes through the micropores 8 below the annular condensation channel 71 under the action of its own weight and gas pressure to form a liquid coolant. The drops 8a flow back to the cooling liquid pool 1 to complete a cooling cycle in a closed space.

In summary, compared with the existing chip cooling device, the chip cooling device of the present invention has the following advantages:

1. The chip cooling device of the present invention integrates the first micropump 2 and the second micropump 6 on the surface of the chip 9 as the driving source of the liquid cooling liquid and the gaseous cooling liquid respectively, which makes it possible to reduce the space occupied by the cooling device. Bulk micromachining technology and surface micromachining technology in microelectromechanical system technology, layered etching, removal of sacrificial layer, and then through reversible anode bonding process, the cooling device is packaged on the surface of the electronic device chip 9 layer by layer, realizing Effective coupling and high-efficiency matching reduce the occupied space and reduce the negative impact on subsequent chip integration and packaging.

2. The chip cooling device of the present invention adopts a closed internal circulation cooling method, controls the formation and injection of micro-droplets through the first micropump 2, and realizes the recovery and reuse of gas through the second micropump 6, and the entire circulation process does not require manual intervention , with high controllability and working flexibility to meet the cooling requirements of different power chips under different working conditions.

3. The chip cooling device of the present invention impacts the hot surface of the chip 9 through the cooling liquid 3a of the micro-droplet, forms a thin film 4a, obtains a very high critical heat flux value, and utilizes the gasification of the liquid in the high temperature zone and the condensation of the gas in the low temperature zone. Phase heat conduction technology, that is, the phase change latent heat characteristics of the cooling liquid, realizes the temperature control of high-density and high-power chips. Compared with the traditional free convection heat transfer, forced convection heat transfer and immersion cooling method, cooling by liquid phase change mechanism is a more efficient cooling method, and the micro-surface spray boiling cooling involved in the present invention has a higher performance of up to ( The critical heat flux value of 500-600) W/cm ² can fully meet the cooling requirements of existing high-density and high-power chips, and can even solve the thermal control problems that must be faced in chip development for a long time in the future.

The above description is only the best implementation mode of the present invention, and does not limit the present invention in any form. Although the present invention has been discussed above with the best embodiment, it is not intended to limit the present invention. Any skilled person in this field can use the technical content disclosed above to make some changes or modifications without departing from the scope of the technical solution of the present invention. To achieve an equivalent implementation, for example, choose other types of cooling liquid to replace fluorocarbon FC-72, change the arrangement of micro-nozzle arrays, and select other types of micro-pumps, etc. However, any simple modifications, equivalent changes and modifications made to the above implementation methods according to the technical essence of the present invention are still within the scope of the technical solutions of the present invention.

Claims (5)

1. chip cooling device, it is characterized in that: it comprises coolant reservoirs (1), first fluid channel (12), first Micropump (2), second fluid channel (23), micro-nozzle (3), cooling chamber (4), the 3rd fluid channel (46), second Micropump (6), the 4th fluid channel (67), condenser (7) and micropore (8), and described coolant reservoirs (1) stores cooling fluid; One end of first Micropump (2) is connected with coolant reservoirs (1) by first fluid channel (12), and the other end of first Micropump (2) is connected with micro-nozzle (3) by second fluid channel (23); Bottom and cooling chamber (4) that described cooling chamber (4) is positioned at described chip cooling device are complementary with described chip; Described micro-nozzle (3) is located at the top of cooling chamber (4) and is connected with cooling chamber (4); One end of second Micropump (6) is connected with cooling chamber (4) by the 3rd fluid channel (46), and the other end of second Micropump (6) is connected with condenser (7) by the 4th fluid channel (67); Described condenser (7) is positioned at the top of coolant reservoirs (1), and the inside of condenser (7) is provided with condensation runner (71), and the top of condensation runner (71) is provided with fin (72), and described condensation runner (71) is connected by micropore (8) with coolant reservoirs (1).

2. chip cooling device according to claim 1 is characterized in that: be provided with the elasticity pumping diaphragm in described first Micropump (2).

3. chip cooling device according to claim 1 is characterized in that: be provided with the elasticity pumping diaphragm in described second Micropump (6).

4. chip cooling device according to claim 1 is characterized in that: described micro-nozzle (3) is for pressing the micro-nozzle array that the rectangular array mode is evenly arranged.

5. chip cooling device according to claim 1 is characterized in that: described micropore (8) is for pressing the microwell array that the rectangular array mode is evenly arranged.

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