CN109959289B - A kind of preparation method of anti-gravity ultra-thin micro heat pipe - Google Patents

Abstract

The invention discloses an anti-gravity ultra-thin micro-heat pipe and a preparation method thereof. The preparation method is to process a single-crystal silicon wafer by two consecutive laser processes to process grooves and a shuttle capable of unidirectionally transporting liquid in an array arrangement. Then, a single crystal silicon support is placed between the two single crystal silicon wafers with the fusiform structure, and the single crystal silicon wafer and the single crystal silicon support are connected by eutectic bonding technology. Then use femtosecond laser drilling to drill a vacuum filling hole on one side of the single crystal silicon wafer, vacuum the micro heat pipe and pour the working fluid through a vacuum filling machine, and then carry out laser welding to seal the vacuum filling hole to obtain The anti-gravity ultra-thin micro heat pipe. The anti-gravity ultra-thin micro heat pipe adopts a shuttle-shaped array liquid wick structure that can transport liquid in one direction directly on the inner wall, and has a larger vapor return channel; the shuttle-shaped array structure brings great capillary return flow Pressure, heat transfer performance is good, with anti-gravity characteristics.

Description

A kind of preparation method of anti-gravity ultra-thin micro heat pipe

technical field

The invention relates to the technical field of micro heat pipe preparation, in particular to a preparation method of an anti-gravity ultra-thin micro heat pipe.

Background technique

With the rapid development of microelectronics technology and large-scale integrated circuit technology, the heat flow density through high-power electronic chips has increased significantly, and the large-scale and highly integrated circuits have also resulted in a very small heat dissipation space for electronic components. Research data show that the failure rate of electronic components increases exponentially with the rise of its temperature, and when the temperature exceeds the rated operating temperature of electronic components, its reliability will decrease significantly. More than 55% of electronic equipment failures are caused by excessive temperature caused by untimely heat dissipation.

As an efficient phase change heat transfer element, the heat pipe has the advantages of high thermal conductivity, high stability and long service life. It can quickly transfer heat away and prevent the generation of local hot spots. one of the components. However, with the continuous development of electronic products towards miniaturization and high integration, traditional cylindrical heat pipes or flattened pipes can no longer meet the requirements of efficient heat dissipation in a small space, and are difficult to apply to compact, light and thin electronic devices. The capillary pressure brought by the wick structure is insufficient, and the heat pipe cannot be used in anti-gravity occasions. In addition, traditional heat pipes can generally transfer heat in two directions, so for electronic components, when the external temperature is too high, the traditional micro heat pipe will transfer the external heat to the electronic components, resulting in the electronic components due to excessive temperature. and damaged.

SUMMARY OF THE INVENTION

The object of the present invention is to overcome the deficiencies of the prior art and provide a method for preparing an anti-gravity ultra-thin micro-heat pipe, which can produce the anti-gravity ultra-thin micro-heat pipe with high precision and mass production, and the anti-gravity ultra-thin micro-heat pipe prepared by this method Compact structure, ultra-thin thickness, anti-gravity, and unidirectional heat transfer characteristics, suitable for efficient heat dissipation in small spaces.

The technical scheme of the present invention is: a preparation method of an anti-gravity ultra-thin micro heat pipe, comprising the following steps:

(1) Clean and dry the single crystal silicon wafer and the single crystal silicon support; the selected single crystal silicon wafer is a single crystal silicon wafer suitable for laser processing and with high thermal conductivity;

(2) The single side of the single crystal silicon wafer is subjected to two consecutive laser processing, and the shuttle-shaped structure arranged in an array and a plurality of grooves with rectangular cross-sections along the length of the single crystal silicon wafer are processed, and then cleaned and processed. drying;

(3) Two single crystal silicon wafers are processed by step (2), the sides of the two single crystal silicon wafers with the shuttle array are opposite to each other, and a single crystal silicon support is placed between the two single crystal silicon wafers, The two single crystal silicon wafers and the single crystal silicon support are sealed by eutectic bonding technology, and an inner cavity is formed between the single crystal silicon wafer and the single crystal silicon support;

(4) Laser drilling is carried out on one of the single crystal silicon wafers of the micro heat pipe, and a vacuum filling hole is processed, and the inner cavity is evacuated through the vacuum filling hole and the working medium liquid is poured into the inner cavity, and then the vacuum filling liquid is poured into the inner cavity. The hole is sealed by laser welding, that is, the anti-gravity ultra-thin micro heat pipe is obtained.

In step (1), the cleaning is to use deionized water for ultrasonic vibration cleaning for at least 20 minutes, and the drying is to dry the single crystal silicon wafer at a temperature of 80-95° C. for 10-15 minutes.

In step (1), the single crystal silicon wafer is rectangular, and the single crystal silicon wafer is polished on both sides in advance. The length of the single crystal silicon wafer is 100-200 mm, the width is 30-50 mm, and the thickness is 0.2-0.25 mm.

In step (1), the monocrystalline silicon support has a rectangular frame structure, the length, width and thickness of the monocrystalline silicon support are respectively the same as the length, width and thickness of the single crystal silicon wafer, and the frame width of the single crystal silicon support is 8 ~12mm.

In step (2), in the two laser processing processes, a plurality of grooves with rectangular cross-sections along the length direction of the single crystal silicon wafer are processed for the first time, and a shuttle-shaped structure arranged in an array is processed for the second time; Alternatively, a shuttle-shaped structure arranged in an array is processed for the first time, and a plurality of grooves with rectangular cross-sections along the length direction of the single crystal silicon wafer are processed for the second time.

In step (2), the laser processing adopts femtosecond laser processing, the wavelength of the laser is 400-800 nm, the energy of the laser is 80-100 mW, and the cutting speed of the laser does not exceed 30 μm/s.

In step (3), the eutectic bonding technology is a silicon-silicon direct eutectic bonding technology.

In step (4), femtosecond laser drilling technology is used for the laser drilling, the pressure in the micro-heat tube cavity is evacuated to 10-20 Pa, and the refrigerant is used as the working fluid. Among them, the refrigerant includes deionized water, ethanol, acetone, tetrafluoroethane, and chlorotrifluoropropene.

In step (3), multiple pairs of single crystal silicon wafers and single crystal silicon supports are simultaneously sealed by eutectic bonding technology. Multiple anti-gravity ultra-thin micro heat pipes can be obtained through a single bonding process to improve production efficiency.

In step (4), a vacuum perfusion machine is used when the inner cavity is evacuated and the working medium liquid is poured into the inner cavity.

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

The preparation method of the anti-gravity ultra-thin micro-heat pipe adopts a shuttle-shaped array liquid-absorbing core structure that can transport liquid in one direction directly on the inner wall. Steam return channel; at the same time, the shuttle-shaped array liquid-absorbing core structure brings great capillary return pressure, good heat transfer performance, and anti-gravity characteristics.

The anti-gravity ultra-thin micro heat pipe preparation method adopts laser processing technology, the groove width is extremely narrow, the cutting surface is smooth, the cutting process has no heat-affected layer, the surface of the processing material does not generate internal stress, and the processing precision is high. The anti-gravity ultra-thin micro-heat pipe prepared by the method of the present invention adopts all-silicon-based material and adopts the tight eutectic bonding technology, which is different from the micro-heat pipe using different materials for the matrix and the liquid-absorbing core, and has extremely small thermal resistance and has The advantages of compact structure, ultra-thin thickness and unidirectional heat transfer are suitable for heat dissipation devices with small heat dissipation space.

The preparation method of the anti-gravity ultra-thin micro heat pipe has simple process and high processing accuracy, and can bond multiple single crystal silicon wafers at the same time through a single eutectic bonding process to realize single or multiple mass production, which is suitable for product application and promotion. .

Description of drawings

FIG. 1 is a schematic diagram of the structure of the anti-gravity ultra-thin micro heat pipe.

FIG. 2 is a top view of a single crystal silicon wafer after laser processing.

FIG. 3 is a schematic structural diagram of a single crystal silicon wafer after laser processing.

FIG. 4 is a schematic diagram of a single fusiform structure of a single crystal silicon wafer.

FIG. 5 is a schematic cross-sectional view of the anti-gravity ultra-thin micro heat pipe.

Among them, as shown in the figure, 1 is a single crystal silicon wafer, 2 is a single crystal silicon support, 3 is a shuttle structure, 4 is a groove, and 5 is an inner cavity.

Detailed ways

The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto.

Example 1

A method for preparing an anti-gravity ultra-thin micro-heat pipe of the present embodiment, as shown in FIG. 1 , includes the following steps:

(1) Select a single crystal silicon wafer with high thermal conductivity suitable for laser processing as the raw material, clean the single crystal silicon wafer and the single crystal silicon support with deionized water ultrasonic vibration for 20 minutes, the ultrasonic frequency is 25kHz, and then the single crystal silicon wafer and the single crystal silicon support The crystalline silicon wafers were dried in a drying oven at 95°C for 15 minutes.

(2) As shown in Figures 2-4, femtosecond laser processing is performed on a single side of a single crystal silicon wafer for two consecutive times to process a shuttle-shaped structure arranged in an array; among them, the shuttle in an array is processed for the first time. The shape structure is used as a capillary wick, and a plurality of grooves with rectangular cross-sections along the length of the single crystal silicon wafer are processed for the second time. Specifically, in the first step, on a substrate with a length of 240mm and a width of 60mm, horizontal Place two single crystal silicon wafers with a length of 100mm, a width of 40mm and a thickness of 0.2mm. The wavelength is 800nm, the laser energy is controlled at 100mW, the laser cutting speed is 30μm/s, the distance between the processed sharp grooves in the long side direction is 150μm, and the distance in the broad side direction is 65μm, between the laser generator and the silicon wafer In the second step, the femtosecond laser is used to cut the grooves on both sides at a distance of 15 μm from the two sides of the laser-processed shuttle array in the first step. The wavelength of the laser is 500 nm. The energy of the laser is controlled at 80mW, and the laser cutting speed is 15μm/s. The absorbent core with the fusiform surface structure was obtained after two laser processes. The single-crystal silicon wafers were cleaned by ultrasonic vibration of deionized water for 20 minutes, and the ultrasonic frequency was 25 kHz, and then the single-crystal silicon wafers were dried in a drying oven at 95°C for 15 minutes.

(3) As shown in FIG. 5 , two single crystal silicon wafers are processed through step (2), and the two single crystal silicon wafers with the shuttle-shaped array are placed opposite each other and placed between the two single crystal silicon wafers. Insert the monocrystalline silicon support, and use the clamp for positioning and clamping, the clamping pressure is about 1.45Pa, and then heated in a vacuum environment of 1100 ° C for 4 hours, and the two monocrystalline silicon wafers are bonded by the silicon-silicon direct eutectic bonding technology. It is sealed with a monocrystalline silicon support to obtain a micro heat pipe. The micro heat pipe is a three-layer sealing structure of a single crystal silicon wafer, a single crystal silicon support and a single crystal silicon wafer. The two single crystal silicon wafers and the single crystal silicon support form an inner cavity 5 .

(4) On one of the single crystal silicon wafers of the micro heat pipe, the distances from the upper side and the right side of the rectangular single crystal silicon wafer are both 20mm, using femtosecond laser drilling without heat-affected zone to process the vacuum irrigation Liquid hole, the drilling diameter is 1mm, the hole depth is 0.2mm, and the laser power is 50W. The micro heat pipe is evacuated by the vacuum perfusion machine and the working fluid liquid is poured into the micro heat pipe. The vacuum pumping is to pump the pressure in the micro heat pipe cavity. To 15Pa, then pour 0.08ml of deionized water as the working medium, and then seal the vacuum filling hole by laser welding, the welding speed is 10m/min, and the output power of the laser welding equipment is 20kW, that is, the anti-gravity ultra-thin micro heat pipe is obtained. Preparation The anti-gravity ultra-thin micro heat pipe has a length of 100mm, a width of 40mm, a section thickness of 0.6mm, and a wall thickness of the tube shell of 0.2mm.

Example 2

The present embodiment is a method for preparing an anti-gravity ultra-thin micro heat pipe, comprising the following steps:

(1) Select a single crystal silicon wafer suitable for laser processing and with high thermal conductivity as the raw material, clean the single crystal silicon wafer and the single crystal silicon support with ultrasonic vibration of deionized water for 30 minutes, the ultrasonic frequency is 25kHz, and then the single crystal silicon wafer and the single crystal silicon support are cleaned by ultrasonic vibration for 30 minutes. The crystalline silicon wafers were dried in a drying oven at 80°C for 10 minutes.

(2) Perform two femtosecond laser processing on a single side of a single crystal silicon wafer in succession to process a shuttle-shaped structure arranged in an array; wherein, the shuttle-shaped structure arranged in an array is processed for the first time as a capillary wick, For the second time, a plurality of grooves with rectangular cross-sections along the length of the single crystal silicon wafer are processed. Specifically, in the first step, two pieces of 200mm long and 60mm wide are placed horizontally on a substrate with a length of 480mm and a width of 60mm. It is a single crystal silicon wafer with a thickness of 40mm and a section thickness of 0.2mm. The distance between the two single crystal silicon wafers is 10mm. The sharp groove of the fusiform structure is processed on the silicon wafer by laser. The wavelength of the laser is 600nm, and the energy of the laser is controlled. At 90mW, the laser cutting speed is 20μm/s, the distance of the processed sharp grooves in the long side direction is 200μm, the distance in the wide side direction is 70μm, the angle between the laser generator and the silicon wafer is 40°, and the shuttle is obtained. In the second step, the femtosecond laser is used to cut the grooves on both sides at a distance of 20 μm from the two sides of the laser-processed shuttle array in the first step. The wavelength of the laser is 450 nm, and the energy of the laser is controlled at 75 mW. The cutting speed was 12 μm/s. The absorbent core with the fusiform surface structure was obtained after two laser processes. The single-crystal silicon wafers were cleaned by ultrasonic vibration of deionized water for 30 minutes, and the ultrasonic frequency was 25 kHz, and then the single-crystal silicon wafers were dried in a drying oven at 80°C for 10 minutes.

(3) Two single crystal silicon wafers are processed by step (2), the sides of the two single crystal silicon wafers with the shuttle array are opposite to each other, and a single crystal silicon support is placed between the two single crystal silicon wafers, And use a clamp for positioning and clamping, the clamping pressure is about 2Pa, and then heated in a vacuum environment of 500 ° C for 2 hours, and the two single-crystal silicon wafers and the single-crystal silicon support are sealed by the silicon-silicon direct eutectic bonding technology. A micro heat pipe is obtained. The micro heat pipe is a three-layer sealing structure of a single crystal silicon wafer, a single crystal silicon support and a single crystal silicon wafer, and the two single crystal silicon wafers and the single crystal silicon support jointly form an inner cavity.

(4) On one of the single crystal silicon wafers of the micro heat pipe, the distances from the upper side and the right side of the rectangular single crystal silicon wafer are both 20mm, using femtosecond laser drilling without heat-affected zone to process the vacuum irrigation Liquid hole, the drilling diameter is 2mm, the hole depth is 0.2mm, and the laser power is 55W. The micro-heat pipe is evacuated by the vacuum perfusion machine and the working fluid is poured into the micro-heat pipe. The vacuum is to pump the pressure in the micro-heat pipe cavity To 15Pa, then pour 0.1ml of deionized water as the working medium, and then seal the vacuum filling hole by laser welding, the welding speed is 5m/min, and the output power of the laser welding equipment is 15kW, that is, the anti-gravity ultra-thin micro heat pipe is obtained. The anti-gravity ultra-thin micro heat pipe has a length of 200mm, a width of 40mm, a section thickness of 0.6mm, and a wall thickness of the tube shell of 0.2mm.

Example 3

The present embodiment is a method for preparing an anti-gravity ultra-thin micro heat pipe, comprising the following steps:

(1) Select a single crystal silicon wafer with high thermal conductivity suitable for laser processing as the raw material, clean the single crystal silicon wafer and the single crystal silicon support with deionized water ultrasonic vibration for 20 minutes, the ultrasonic frequency is 25kHz, and then the single crystal silicon wafer and the single crystal silicon support The crystalline silicon wafers were dried in a drying oven at 95°C for 15 minutes.

(2) The single side of the single crystal silicon wafer is processed by femtosecond laser twice continuously, and the shuttle-shaped structure arranged in an array is processed; wherein, the shuttle-shaped structure arranged in an array is processed for the first time as a capillary wick, For the second time, a plurality of grooves with rectangular cross-sections along the length direction of the single crystal silicon wafer are processed. Specifically, in the first step, a substrate with a length of 600mm and a width of 120mm is placed horizontally with a length of 100mm and a width of 40mm. , 10 single-crystal silicon wafers with a section thickness of 0.2mm, the spacing between each single-crystal silicon wafer is 20mm, and the fusiform structure of the sharp groove is processed on the silicon wafer by laser. The wavelength of the laser is 500nm, and the energy of the laser is controlled. At 80 mW, the laser cutting speed is 15 μm/s, the pitch of the processed sharp grooves in the long-side direction is 300 μm, the pitch in the wide-side direction is 80 μm, and the angle between the laser generator and the silicon wafer is 45°, the obtained The shuttle-shaped array; in the second step, femtosecond laser is used to cut the grooves on both sides at a distance of 25 μm from the two sides of the laser-processed shuttle-shaped array in the first step. The wavelength of the laser is 400 nm, and the energy of the laser is controlled at 70 mW. The laser cutting speed is 10 μm/s. Axonometric schematic diagram of a single fusiform dimple obtained by two laser processes, thereby obtaining a wick with a fusiform surface structure. The single-crystal silicon wafers were cleaned by ultrasonic vibration of deionized water for 20 minutes, and the ultrasonic frequency was 25 kHz, and then the single-crystal silicon wafers were dried in a drying oven at 95°C for 15 minutes.

(3) 10 single crystal silicon wafers are processed through step (2), the side of the single crystal silicon wafer with the shuttle array is opposite to each other, and a single crystal silicon support is placed between the two single crystal silicon wafers to form five Yes, and use a clamp for positioning and clamping, the clamping pressure is about 1.45Pa, and then heated in a vacuum environment of 1100 ° C for 4 hours, through the silicon-silicon direct eutectic bonding technology, two single crystal silicon wafers and single crystal silicon The support is sealed to obtain a micro heat pipe. The micro heat pipe is a three-layer sealing structure of a single crystal silicon wafer, a single crystal silicon support and a single crystal silicon wafer, and the two single crystal silicon wafers and the single crystal silicon support jointly form an inner cavity.

(4) On one of the single crystal silicon wafers of the micro heat pipe, the distances from the upper side and the right side of the rectangular single crystal silicon wafer are both 20mm, using femtosecond laser drilling without heat-affected zone to process the vacuum irrigation Liquid hole, the drilling diameter is 1mm, the hole depth is 0.2mm, and the laser power is 50W. The micro heat pipe is evacuated by the vacuum perfusion machine and the working fluid liquid is poured into the micro heat pipe. The vacuum pumping is to pump the pressure in the micro heat pipe cavity. To 15Pa, then pour 0.08ml of deionized water as the working medium, and then seal the vacuum filling hole by laser welding, the welding speed is 10m/min, and the output power of the laser welding equipment is 20kW, that is, five anti-gravity ultra-thin micro heat pipes are obtained. The prepared anti-gravity ultra-thin micro heat pipe has a length of 100 mm, a width of 40 mm, a section thickness of 0.6 mm, and a wall thickness of the tube shell of 0.2 mm.

As described above, the present invention can be well realized, and the above-mentioned embodiments are only preferred embodiments of the present invention, and are not intended to limit the scope of implementation of the present invention; It is covered by the scope of protection of the claims of the present invention.

Claims (10)

1. The preparation method of the antigravity ultrathin micro heat pipe is characterized by comprising the following steps of:

(1) cleaning and drying the monocrystalline silicon wafer and the monocrystalline silicon support;

(2) successively and continuously carrying out laser processing twice on a single surface of a monocrystalline silicon piece to process a fusiform structure arranged in an array and a plurality of grooves with rectangular cross sections along the length direction of the monocrystalline silicon piece, and then cleaning and drying the monocrystalline silicon piece;

(3) processing two monocrystalline silicon wafers through the step (2), wherein one surfaces of the two monocrystalline silicon wafers with the fusiform arrays are opposite, a monocrystalline silicon support is placed between the two monocrystalline silicon wafers, the two monocrystalline silicon wafers and the monocrystalline silicon support are sealed through an eutectic bonding technology, and an inner cavity is formed between the monocrystalline silicon wafers and the monocrystalline silicon support;

(4) and laser drilling is carried out on one of the monocrystalline silicon pieces of the micro heat pipe, a vacuum liquid filling hole is processed, the inner cavity is vacuumized through the vacuum liquid filling hole and is filled with working medium liquid, and then the vacuum liquid filling hole is sealed by laser welding, so that the anti-gravity ultrathin micro heat pipe is obtained.

2. The method for preparing an antigravity ultrathin micro heat pipe according to claim 1, wherein in the step (1), the cleaning is ultrasonic vibration cleaning for at least 20 minutes by using deionized water, and the drying is drying of the monocrystalline silicon wafer at the temperature of 80-95 ℃ for 10-15 minutes.

3. The method for preparing an antigravity ultrathin micro heat pipe according to claim 1, wherein in the step (1), the monocrystalline silicon piece is rectangular, the monocrystalline silicon piece is subjected to two-side polishing treatment in advance, the length of the monocrystalline silicon piece is 100-200 mm, the width of the monocrystalline silicon piece is 30-50 mm, and the thickness of the monocrystalline silicon piece is 0.2-0.25 mm.

4. The method for preparing an antigravity ultrathin micro heat pipe according to claim 3, wherein in the step (1), the monocrystalline silicon support is of a rectangular frame structure, the length, width and thickness of the monocrystalline silicon support are respectively the same as those of the monocrystalline silicon piece, and the frame width of the monocrystalline silicon support is 8-12 mm.

5. The method for preparing the antigravity ultrathin micro heat pipe as claimed in claim 1, wherein in the step (2), in the two laser processing processes, a plurality of grooves with rectangular cross sections are processed for the first time along the length direction of the monocrystalline silicon piece, and spindle-shaped structures arranged in an array are processed for the second time; or processing the spindle-shaped structures arranged in an array for the first time, and processing a plurality of grooves with rectangular cross sections along the length direction of the monocrystalline silicon piece for the second time.

6. The method for preparing an antigravity ultrathin micro heat pipe as claimed in claim 1, wherein in the step (2), the laser processing is femtosecond laser processing, the wavelength of the laser is 400 nm-800 nm, the energy of the laser is 80-100 mW, and the cutting speed of the laser is not more than 30 μm/s.

7. The method for preparing an antigravity ultrathin micro heat pipe as claimed in claim 1, wherein in the step (3), the eutectic bonding technology is a silicon-silicon direct eutectic bonding technology.

8. The method for preparing the antigravity ultrathin micro heat pipe according to claim 1, wherein in the step (4), the laser drilling adopts a femtosecond laser drilling technology, the vacuumizing is to pump the pressure in the micro heat pipe cavity to 10-20 Pa, and the working medium liquid adopts a refrigerant.

9. The method for preparing an antigravity ultrathin micro heat pipe as claimed in claim 1, wherein in the step (3), a plurality of pairs of monocrystalline silicon wafers and monocrystalline silicon supports are simultaneously sealed by a eutectic bonding technology.

10. The method for preparing an antigravity ultrathin micro heat pipe as claimed in claim 1, wherein in the step (4), a vacuum filling machine is adopted when the inner cavity is vacuumized and the working medium liquid is filled into the inner cavity.

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