Aluminum nitride copper-coated ceramic vapor chamber based on capillary core and preparation method of aluminum nitride copper-coated ceramic vapor chamber

Abstract

The invention relates to an aluminum nitride copper-coated ceramic vapor chamber based on a capillary core and a preparation method of the aluminum nitride copper-coated ceramic vapor chamber. The uniform-temperature plate comprises a uniform-temperature cavity. The temperature equalizing cavity is a cavity enclosed by a ring frame, a first aluminum nitride copper-clad plate and a second aluminum nitride copper-clad plate; the first aluminum nitride copper-clad plate comprises a first metal layer, a first aluminum nitride ceramic layer and a second metal layer which are arranged in sequence; the second aluminum nitride copper-clad plate comprises a third metal layer, a second aluminum nitride ceramic layer and a fourth metal layer which are arranged in sequence; the top of the third metal layer is provided with a capillary core structure. The problem that a traditional metal vapor chamber is not suitable for the power electronic industry due to the thermal expansion coefficient and the insulation problem can be solved, the problem that a pure ceramic vapor chamber is difficult to machine can also be solved, and through improvement of the AMB copper-clad plate machining technology, the reliability of the vapor chamber is improved, and the application range of the vapor chamber is widened.

Description

Technical Field

[0001] The invention relates to the technical field of temperature balancing plate manufacturing, and in particular to a capillary wick-based aluminum nitride copper-clad ceramic temperature balancing plate and a preparation method thereof. Background Art

[0002] The third generation of semiconductor materials refers to new semiconductor materials represented by wide bandgap semiconductor materials such as gallium nitride (GaN), silicon carbide (SiC), and zinc oxide (ZnO). The third generation of semiconductors can significantly reduce the size of the system and double the efficiency of the product, which will have a revolutionary impact on the equipment system. They are the key core materials and key electronic components that support the independent innovation and development and transformation and upgrading of industries such as the next generation of mobile communications, new energy vehicles, high-speed trains, energy Internet, and new generation displays and light sources. They play a core supporting role in national economic security (energy, transportation, communications) and the transformation and upgrading of traditional industries (low carbon, intelligence).

[0003] The integration and miniaturization of power electronic devices have led to higher and higher local temperatures of chips, and the current density of the heating unit has increased. It is necessary to dissipate the heat in time to ensure the normal operation of the device. The heat spreader can solve the heat dissipation problem caused by the concentration of current density. However, there are many problems in using metal heat spreaders on power electronic devices: metal plates are conductive and cannot be directly connected to electronic components; ceramic plates are insulating and cannot directly draw circuits, and accessories need to be added to expand the module volume; the thermal expansion coefficients of chips and metal plates are quite different, and cracks are easily generated during use, increasing thermal resistance and reducing product life. Ceramic copper clad laminates have excellent heat dissipation efficiency and insulation, and are comparable to the thermal expansion coefficient of chips. They can meet the use requirements of third-generation semiconductors and broaden the application field and service life of heat spreaders. However, since the thermal conductivity of ceramics or silicides is often low, the thermal conductivity of the insulating substrate of ceramic copper clad laminates is much lower than that of metals, and the thermal conductivity and temperature averaging capabilities are poor, which cannot meet the growing heat dissipation needs of semiconductor power devices.

[0004] Chinese patent document CN115424986A discloses an insulating substrate structure with temperature equalization capability and a preparation method thereof, wherein the insulating substrate structure comprises an upper cover plate and a lower cover plate correspondingly sealed and connected, a vacuum cavity is provided between the upper cover plate and the lower cover plate, the vacuum cavity is perfused with a liquid working medium, the outer side surfaces of the upper cover plate and the lower cover plate are both metal layers, the inner side surfaces of the upper cover plate and the lower cover plate are both ceramic layers, the ceramic layer is provided with a liquid wick, and the liquid wick is provided in the vacuum cavity. A liquid wick is provided in the ceramic layer of the upper cover plate and the lower cover plate, and high-speed heat dissipation is performed through the phase change of the working medium, and the heat dissipation capacity and temperature equalization capacity are greatly improved. Due to the good thermal conductivity, the thermal control of power devices in extreme environments can be achieved, and the requirements of power devices for heat dissipation and temperature equalization can be guaranteed. The interior of the insulating substrate substrate is a cavity structure, which can flexibly control the thickness and flatness of the insulating substrate, and make the substrate lightweight under the premise of ensuring heat dissipation performance. However, this preparation method cannot directly prepare the circuit on the ceramic surface, and an additional process is required to prepare a transition layer to connect the ceramic surface of the temperature equalization plate with the circuit, which greatly increases the packaging volume. In addition, the addition of a transition layer will increase thermal resistance, reduce the chip's heat dissipation capacity, and cannot meet the use requirements of high-current and high-voltage devices.

[0005] Therefore, in order to solve the deficiencies in the prior art, it is necessary to realize an aluminum nitride copper-clad ceramic temperature equalizing plate based on a capillary wick and a preparation method thereof. Summary of the invention

[0006] The purpose of the present invention is to provide an aluminum nitride copper-clad ceramic temperature-averaging board based on a capillary core and a preparation method thereof. The temperature-averaging board and the preparation method thereof can not only solve the problem that traditional metal temperature-averaging boards are not suitable for the power electronics industry due to thermal expansion coefficient and insulation problems, but also solve the problem that pure ceramic temperature-averaging boards are difficult to process. By improving the AMB copper-clad board processing technology, the reliability of the temperature-averaging board is improved and its scope of application is expanded.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A capillary wick-based aluminum nitride copper-clad ceramic temperature balancing plate, the temperature balancing plate comprising a temperature balancing cavity; the temperature balancing cavity is a cavity surrounded by a ring frame, a first aluminum nitride copper-clad plate arranged on the top of the ring frame, and a second aluminum nitride copper-clad plate arranged on the bottom of the ring frame; the first aluminum nitride copper-clad plate comprises a first metal layer, a first aluminum nitride ceramic layer, and a second metal layer arranged in sequence; the second aluminum nitride copper-clad plate comprises a third metal layer, a second aluminum nitride ceramic layer, and a fourth metal layer arranged in sequence; a capillary wick structure is arranged on the top of the third metal layer.

[0009] Preferably according to the present invention, the capillary wick structure is a plurality of grooves opened on the top of the third metal layer, and the depth and width of the grooves are 0.12 mm and 0.12 mm respectively.

[0010] Preferably according to the present invention, the first metal layer, the second metal layer, the third metal layer and the fourth metal layer are all made of oxygen-free copper foil.

[0011] Preferably according to the present invention, the first aluminum nitride ceramic layer and the second aluminum nitride ceramic layer are both made of aluminum nitride ceramic sheets.

[0012] The present invention also includes a method for preparing an aluminum nitride copper-clad ceramic temperature-averaging plate based on a capillary core, the method comprising the following steps:

[0013] S1. Determine the materials for preparing the temperature equalization board and clean the materials; the materials include aluminum nitride ceramic sheets, oxygen-free copper foil and ring frames.

[0014] S2. Using aluminum nitride ceramic sheets to make aluminum nitride substrates, screen printing is used to evenly print a layer of AgCuTi solder with a thickness of d on the aluminum nitride substrates, and the printed aluminum nitride substrates are placed in a vacuum oven for drying.

[0015] S3, placing the dried aluminum nitride ceramic sheet into a vacuum debinding furnace for debinding.

[0016] S4, stacking the oxygen-free copper foil and the aluminum nitride ceramic sheet obtained in step S3 together, configuring a counterweight block on the top, and welding the oxygen-free copper foil and the aluminum nitride ceramic sheet in a vacuum environment using a vacuum brazing furnace to form an aluminum nitride copper clad laminate; the aluminum nitride copper clad laminate is divided into a first aluminum nitride copper clad laminate and a second aluminum nitride copper clad laminate;

[0017] S5, performing film lamination, exposure, development, etching, and film stripping processes on the welded second aluminum nitride copper clad laminate, preparing a chip circuit pattern on the front side of the processed second aluminum nitride copper clad laminate, and preparing a capillary wick structure pattern on the back side;

[0018] S6. Use solder etching solution to remove excess solder between patterns on the aluminum nitride copper clad laminate.

[0019] S7. Use the silver-copper welding process to weld the first aluminum nitride copper clad laminate and the second aluminum nitride copper clad laminate at the upper and lower ends of the ring frame respectively to form a uniform temperature cavity.

[0020] S8. The working fluid is poured into the temperature-averaging cavity through the rat tail, and the rat tail is sealed, and the temperature-averaging plate is prepared.

[0021] Preferably according to the present invention, in step S2, the value of d is 20 μm.

[0022] Preferably according to the present invention, in step S2, the drying temperature of the vacuum oven is 100° C., and the drying time is 30 min.

[0023] Preferably, according to the present invention, in step S3, the temperature in the vacuum debinding furnace is 350-450° C., and the debinding time is 5 hours.

[0024] Preferably, according to the present invention, in step S4, the weight of the counterweight block is 2-5 kg; and the temperature of the vacuum environment is 850° C.-910° C.

[0025] Preferably according to the present invention, in step S7, the welding temperature of the silver-copper welding process is 780°C.

[0026] Compared with the prior art, the advantages of the present invention are:

[0027] (1) In the prior art, metal heat spreaders are conductors that cannot be patterned. Ceramic heat spreaders need to be connected to the circuit pattern area by plating or welding to achieve the purpose of heat dissipation. However, the transition of the transition layer or welding layer will increase the thermal resistance between the chip and the heat dissipation area, weaken the direct heat dissipation effect of the chip, and reduce the service life of the chip. The present invention strongly links the copper clad laminate preparation technology with the heat spreader preparation technology, solves the two problems of packaging volume and circuit connection at one time, and can effectively ensure the rapid heat dissipation of the chip and the miniaturized packaging of the module.

[0028] (2) A major technical difficulty in using copper-clad laminates to prepare temperature-averaging boards is how to connect the liquid-absorbing core to the copper-clad laminate to form a vapor chamber, ensure the volatilization of the working fluid, and achieve a rapid heat dissipation effect. The traditional method is to fill the vapor chamber with honeycomb copper and use the direct capillary effect of the copper wire to promote the volatilization and reflux of the working fluid. However, the product welding process of AMB copper-clad laminates is 800-900°C, and the sintering temperature of copper or other metal capillary cores is higher than 900°C. If the capillary core is sintered on the copper-clad laminate, the product structure and performance of the copper-clad laminate itself will be destroyed, reducing product reliability. Therefore, the present invention does not use the traditional metal capillary core sintering process, but instead transfers the capillary core structure to the copper layer of the copper-clad laminate, and uses an etching process to prepare the capillary core structure on the copper layer, which not only ensures the integrity of the overall temperature-averaging board process structure, but also ensures the rapid volatilization and reflux of the working fluid, and also reduces the packaging volume.

[0029] (3) The present invention proposes a novel ceramic copper-clad temperature-averaging board and a preparation method thereof. The upper and lower cover plates of the ring frame are prepared by the active metal brazing (AMB) copper-clad board production process; the capillary wick structure for heat absorption and heat dissipation is prepared by the etching process; the circuit pattern is prepared by the etching process; and a vacuum cavity is constructed by sealing the ring frame to promote the evaporation heat absorption cycle, thereby realizing the preparation of a novel aluminum nitride copper-clad ceramic temperature-averaging board. The aluminum nitride copper-clad ceramic temperature-averaging board based on the capillary wick prepared by the method of the present invention has an equivalent thermal conductivity of ≥1500W / m·k and a linear expansion coefficient of ≤10ppm / ℃. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic structural diagram of the aluminum nitride copper-clad ceramic temperature balancing plate based on the capillary core in the present invention;

[0031] Figure 2 is a schematic structural diagram of the fourth metal layer and the capillary wick structure;

[0032] Figure 3 is a top view of the fourth metal layer and the capillary wick structure.

[0033] in:

[0034] 1. first metal layer, 2. first aluminum nitride ceramic layer, 3. second metal layer, 4. ring frame, 5. capillary core structure, 6. third metal layer, 7. second aluminum nitride ceramic layer, 8. fourth metal layer, 9. groove. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with the accompanying drawings:

[0036] like Figure 1 A capillary core-based aluminum nitride copper-clad ceramic temperature balancing board is shown, which includes a temperature balancing cavity; the temperature balancing cavity is a cavity surrounded by a ring frame 4, a first aluminum nitride copper-clad board arranged on the top of the ring frame 4, and a second aluminum nitride copper-clad board arranged at the bottom of the ring frame 4.

[0037] like Figure 1 As shown, the first aluminum nitride copper clad laminate includes a first metal layer 1, a first aluminum nitride ceramic layer 2 and a second metal layer 3 which are arranged in sequence from top to bottom.

[0038] like Figure 1 As shown, the second aluminum nitride copper clad laminate comprises a third metal layer 6, a second aluminum nitride ceramic layer 7 and a fourth metal layer 8 arranged in sequence from top to bottom. A capillary wick structure 5 is arranged on the top of the third metal layer 6.

[0039] In the above technical solution, the ring frame 4 forms the basic framework of the temperature-averaging cavity. The first aluminum nitride copper-clad laminate is located on the top of the ring frame 4, and the first metal layer 1 therein directly contacts the heat source and is responsible for quickly transferring heat to the next layer. The first aluminum nitride ceramic layer 2, as an insulating medium layer with good thermal conductivity, helps to evenly disperse the heat from the first metal layer. The second metal layer 3 plays a role in further conducting heat. The third metal layer 6 in the second aluminum nitride copper-clad laminate not only participates in heat conduction, but also has a capillary wick structure 5 on its top to increase the heat exchange efficiency through liquid evaporation and condensation cycles. The second aluminum nitride ceramic layer 7 is used to achieve better heat distribution. The capillary wick structure 5 is one of the key components of the entire system. It can promote the evaporation of the working fluid (such as water) when heated, and re-condense back to liquid in a lower temperature place, thereby realizing an efficient heat transfer process. This process relies on capillary force to automatically pump the liquid, without the need for an additional power source, making the system more compact and efficient. Such a design is very suitable for application scenarios that require efficient heat dissipation but have limited space.

[0040] like Figure 2 and Figure 3 As shown, the capillary wick structure 5 is a plurality of grooves opened on the top of the third metal layer 6, and the depth and width of the grooves are 0.12 mm. This micro-scale groove design can effectively promote the circulation of the working fluid (such as water) by capillary action, thereby improving the heat conduction efficiency. The design of the capillary wick structure is crucial to ensure that the liquid can be evenly distributed on the entire plate and effectively evaporate and condense.

[0041] Preferably, the first metal layer 1, the second metal layer 3, the third metal layer 6 and the fourth metal layer 8 are all made of oxygen-free copper foil. Oxygen-free copper foil has the characteristics of good electrical conductivity and thermal conductivity, good processing performance, strong corrosion resistance and high stability, and can maintain good mechanical properties under high temperature conditions.

[0042] Preferably, according to the present invention, the first aluminum nitride ceramic layer 2 and the second aluminum nitride ceramic layer 7 are both made of aluminum nitride ceramic sheets. Using aluminum nitride as a ceramic layer can improve the efficiency of heat conduction, provide an efficient and reliable heat conduction path, and quickly remove heat from the heat source. Combined with the excellent thermal conductivity of oxygen-free copper foil, the aluminum nitride ceramic layer further ensures the stability and long-term reliability of the entire system. Compared with other traditional materials, aluminum nitride is relatively light, which helps to reduce the weight of the overall equipment.

[0043] The present invention also includes a method for preparing an aluminum nitride copper-clad ceramic temperature-averaging plate based on a capillary core, the method comprising the following steps:

[0044] S1. Determine the materials for preparing the temperature homogenizing plate and clean the materials; the materials include aluminum nitride ceramic sheets, oxygen-free copper foils and ring frames to remove surface contaminants.

[0045] S2. Use aluminum nitride ceramics to make aluminum nitride substrates, use screen printing to evenly print a layer of AgCuTi solder with a thickness of 20 μm on the aluminum nitride substrate, and place the printed aluminum nitride substrate in a vacuum oven for drying to ensure that the solder layer is dry and well adhered. The drying temperature of the vacuum oven is 100°C and the drying time is 30 minutes.

[0046] S3. Put the dried aluminum nitride ceramic sheet into a vacuum debinding furnace to debind the aluminum nitride ceramic sheet to remove possible organic matter; the temperature in the vacuum debinding furnace is 350-450° C., and the debinding time is 5 hours.

[0047] S4. Stack the oxygen-free copper foil and the aluminum nitride ceramic sheet obtained in step S3 together, configure a counterweight block on the top to ensure close contact, and use a vacuum brazing furnace to weld the oxygen-free copper foil and the aluminum nitride ceramic sheet in a vacuum environment to form an aluminum nitride copper clad laminate; the weight of the counterweight block is 2 to 5 kg; the temperature of the vacuum environment is 850°C to 910°C.

[0048] S5. The welded aluminum nitride copper clad laminate is processed by laminating, exposing, developing, etching, and stripping. The chip circuit pattern is prepared on the front of the processed aluminum nitride copper clad laminate. The capillary core structure on the back is realized by a two-step etching method. First, the film is laminated, exposed, and etched in part. After stripping and cleaning, the film is laminated, exposed, and etched in another area, thereby realizing an uneven three-dimensional structure to achieve a capillary effect. Only the copper clad laminate at the bottom will be patterned. This product is a flip-chip product, and the chip position will be patterned. The chip circuit pattern is prepared on the front of the second aluminum nitride copper clad laminate located at the bottom, and the capillary core structure is prepared on the back.

[0049] S6. Use solder etching solution to remove excess solder between patterns on the aluminum nitride copper clad board to keep the patterns clear.

[0050] S7. Using the silver-copper welding process, weld an aluminum nitride copper-clad plate at the upper and lower ends of the ring frame to form a closed uniform temperature cavity; the welding temperature of the silver-copper welding process is 780°C.

[0051] S8, the working fluid is poured into the temperature equalization cavity through the rat tail, and the rat tail is sealed, and the temperature equalization board is prepared. After the working fluid is filled, the rat tail is sealed to ensure that the internal environment of the temperature equalization board is closed to prevent leakage.

[0052] In the prior art, metal / ceramic temperature equalizers cannot be used in the power electronics industry, and the present invention broadens the application field of temperature equalizers. The copper-clad laminate temperature equalizer prepared by the present invention solves the problem that the thermal expansion coefficients of ordinary ceramic and metal temperature equalizers do not match those of chips, and the chips cannot be directly welded. The present invention also solves the problem of difficult processing of circuit graphics of ceramic temperature equalizers, increases the reliability and scope of application of temperature equalizers, and improves the heat dissipation capacity and reliability of ceramic temperature equalizers. Different from the prior art, the present invention focuses on the pain points of power device development, which are to enhance heat dissipation and reduce packaging volume. Through the integrated preparation process of copper-clad laminates and temperature equalizers, an aluminum nitride temperature equalizer with a small packaging volume and strong heat dissipation capacity is obtained, in order to solve the industry's pain points.

[0053] The above-described embodiments are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the scope of protection determined by the claims of the present invention.

Claims

1. A capillary wick-based aluminum nitride copper-clad ceramic temperature-averaging plate, characterized in that: The temperature equalizing plate comprises a temperature equalizing cavity; the temperature equalizing cavity is a cavity surrounded by a ring frame (4), a first aluminum nitride copper clad plate arranged on the top of the ring frame (4), and a second aluminum nitride copper clad plate arranged on the bottom of the ring frame (4); the first aluminum nitride copper clad plate comprises a first metal layer (1), a first aluminum nitride ceramic layer (2), and a second metal layer (3) arranged in sequence; the second aluminum nitride copper clad plate comprises a third metal layer (6), a second aluminum nitride ceramic layer (7), and a fourth metal layer (8) arranged in sequence; and a capillary wick structure (5) is arranged on the top of the third metal layer (6).

2. The aluminum nitride copper-clad ceramic temperature-averaging plate based on a capillary core according to claim 1, characterized in that: The capillary core structure (5) is a plurality of grooves opened on the top of the third metal layer (6), and the depth and width of the grooves are 0.12 mm.

3. The aluminum nitride copper-clad ceramic temperature-averaging plate based on a capillary core according to claim 1, characterized in that: The first metal layer (1), the second metal layer (3), the third metal layer (6) and the fourth metal layer (8) are all made of oxygen-free copper foil.

4. The aluminum nitride copper-clad ceramic temperature-averaging plate based on a capillary core according to claim 1, characterized in that: The first aluminum nitride ceramic layer (2) and the second aluminum nitride ceramic layer (7) are both made of aluminum nitride ceramic sheets.

5. A method for preparing an aluminum nitride copper-clad ceramic temperature-averaging plate based on a capillary core, characterized in that: The method comprises the following steps: S1. Determine the materials for preparing the temperature equalization board and clean the materials; the materials include aluminum nitride ceramic sheets, oxygen-free copper foil and ring frames; S2, using aluminum nitride ceramic sheets to make aluminum nitride substrates, using screen printing to evenly print a layer of AgCuTi solder with a thickness of d on the aluminum nitride substrate, and placing the printed aluminum nitride substrate in a vacuum oven for drying; S3, placing the dried aluminum nitride ceramic sheet into a vacuum debinding furnace, and debinding the sheet in the vacuum debinding furnace; S4, stacking the oxygen-free copper foil and the aluminum nitride ceramic sheet obtained in step S3 together, configuring a counterweight block on the top, and welding the oxygen-free copper foil and the aluminum nitride ceramic sheet in a vacuum environment using a vacuum brazing furnace to form an aluminum nitride copper clad laminate; the aluminum nitride copper clad laminate is divided into a first aluminum nitride copper clad laminate and a second aluminum nitride copper clad laminate; S5, performing film lamination, exposure, development, etching, and film stripping processes on the welded second aluminum nitride copper clad laminate, preparing a chip circuit pattern on the front side of the processed second aluminum nitride copper clad laminate, and preparing a capillary wick structure on the back side; S6, using a solder etching solution to remove excess solder between the patterns on the second aluminum nitride copper clad laminate; S7, using a silver-copper welding process, respectively welding the first aluminum nitride copper-clad plate and the second aluminum nitride copper-clad plate at the upper and lower ends of the ring frame to form a temperature-averaging cavity; S8. The working fluid is poured into the temperature-averaging cavity through the rat tail, and the rat tail is sealed, and the temperature-averaging plate is prepared.

6. The method for preparing the aluminum nitride copper-clad ceramic temperature-averaging plate based on a capillary core according to claim 5, characterized in that: In step S2, the value of d is 20 μm.

7. The method for preparing the aluminum nitride copper-clad ceramic temperature-averaging plate based on a capillary core according to claim 5, characterized in that: In step S2, the drying temperature of the vacuum oven is 100°C and the drying time is 30 minutes.

8. The method for preparing the aluminum nitride copper-clad ceramic temperature-averaging plate based on a capillary core according to claim 5, characterized in that: In step S3, the temperature in the vacuum debinding furnace is 350-450° C., and the debinding time is 5 hours.

9. The method for preparing the aluminum nitride copper-clad ceramic temperature-averaging plate based on a capillary core according to claim 5, characterized in that: In step S4, the weight of the counterweight block is 2-5 kg; the temperature of the vacuum environment is 850° C.-910° C.

10. The method for preparing the aluminum nitride copper-clad ceramic temperature-averaging plate based on a capillary wick according to claim 5, characterized in that: In step S7, the welding temperature of the silver-copper welding process is 780°C.

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