A low-temperature sintering connection method of nano-copper material

Abstract

This invention provides a low-temperature sintering bonding method for nano-copper materials. The method includes sintering in a catalyzed formic acid gas atmosphere. During sintering, the temperature is first raised to 80-200℃ and held for 5-10 minutes, then sintered further for 3-30 minutes under a pressure of 0-30 MPa and a temperature of 0-280℃. The formic acid gas is catalyzed using a catalyst film loaded on the surface of a porous heated ceramic sheet. This invention utilizes a nano-film catalyst to catalyze formic acid, enabling low-temperature sintering bonding of nano-copper materials within a specific sintering process window. This method solves the problems of weak mechanical and electrical properties in nano-copper materials. Furthermore, this sintering bonding method exhibits significant reduction effect, is economical and environmentally friendly, and highly efficient.

Description

Technical Field

[0001] This invention relates to the field of electronic packaging technology, and in particular to a low-temperature sintering bonding method for nano-copper materials. Background Technology

[0002] With the development of the semiconductor industry, power semiconductors are playing an increasingly important role in semiconductor devices, mainly including power metal-oxide-semiconductor field-effect transistors, insulated-gate bipolar transistors, and power integrated circuits. International experts have likened its development to the second electronics revolution. The high thermal conductivity DBC substrate material and chip interconnect material inside power semiconductors are mostly encapsulated with copper solder paste. During sintering, there are two problems: Cu oxidation leading to decreased electrical performance and the volatilization of organic matter creating numerous pores that reduce the strength of the interconnect layer. Furthermore, power semiconductors cannot operate at high temperatures during use. Therefore, there is an urgent need in industry for an efficient low-temperature sintering method that can reduce the porosity of nano-copper materials during the sintering process.

[0003] Common reduction methods in sintering can be broadly categorized into two types. One involves adding reducing agents to the solder paste. This method is relatively common, but because it only affects the solder paste-coated joints, other parts will also be oxidized during sintering, affecting usability. The second method utilizes an atmosphere for reduction during sintering. In related technologies, Li Sujuan et al. (CN106340802A) directly used a formic acid atmosphere to reduce sintered samples. However, the chemical process of directly reducing CuO with uncatalyzed formic acid is complex, resulting in a long reduction time and unsatisfactory reduction effect. Ren et al. (Low temperature Cubonding with large tolerance of surface oxidation. AIP Advances 9, doi:10.1063 / 1.5097382) used C powder as a carrier and Pt powder as a catalyst to catalyze formic acid gas during sintering. However, this method suffers from problems such as Pt and C powder easily contaminating the sample during gas blowing and insufficient catalytic effect of the powdered catalyst. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a low-temperature sintering connection method for nano-copper materials.

[0005] In a first aspect, the present invention provides a low-temperature sintering bonding method for nano-copper materials, comprising: sintering in a catalyzed formic acid gas atmosphere, wherein during the sintering process, the temperature is first raised to 80-200°C, held for 5-10 min, and then sintered for another 3-30 min under a pressure of 0-30 MPa and a temperature of 0-280°C; wherein the formic acid gas is catalyzed by a catalyst film loaded on the surface of a porous heated ceramic sheet.

[0006] This invention utilizes a catalyst film loaded on the surface of a porous heated ceramic sheet to catalyze formic acid gas. This allows for the complete catalysis of formic acid gas without any catalyst contamination. The fully catalyzed formic acid is then used to reduce nano-copper materials under a specific sintering process window. This solves the problems of decreased electrical performance and reduced connection strength caused by copper oxidation during sintering.

[0007] The nano-copper materials of this invention include common copper materials such as copper solder paste, copper solder sheets with nanostructures, and copper thin films.

[0008] The operation of first heating to 80-200℃ and holding for 5-10 minutes can better solve the problem of performance degradation of copper solder paste caused by the volatilization of organic matter.

[0009] According to the low-temperature sintering bonding method for nano-copper materials provided by the present invention, the catalyst film is a Pt nanofilm or a Pd nanofilm, and the catalyst film is loaded onto the surface of a porous heated ceramic sheet by pulsed laser deposition.

[0010] Pulsed laser deposition (PLD) is a technique that uses a laser to bombard an object and then deposits the bombarded material onto different substrates to obtain a deposit or thin film. This technique is a well-known and mature technology in the field and can be performed using conventional methods. In a specific embodiment of the present invention, to improve efficiency, the pulsed laser deposition employs high-pressure dual-target deposition.

[0011] Furthermore, the thickness of the porous heating ceramic sheet is 2-50 mm, and the thickness of the catalyst film is 10-1000 μm.

[0012] According to the low-temperature sintering connection method of the nano-copper material provided by the present invention, the diameter of the pores on the porous heated ceramic sheet is 0.1-5 mm, and the porous heated ceramic sheet controls the catalytic temperature at 100-300℃.

[0013] According to the low-temperature sintering connection method of the nano-copper material provided by the present invention, the pores on the porous heated ceramic sheet are concentrated in half of the porous heated ceramic sheet. In the process of catalyzing formic acid gas, 2-10 porous heated ceramic sheets loaded with catalyst films are used, and the phase difference between each two adjacent porous heated ceramic sheets is 180°, so that the pores are staggered.

[0014] There are no special restrictions on the distance between any two adjacent porous heating ceramic plates, but 20-100mm is preferred.

[0015] According to the low-temperature sintering connection method of the nano-copper material provided by the present invention, when the nano-copper material is copper solder paste, before sintering, a layer of copper solder paste is first coated on the lower substrate and heated at 80-200°C for 5-15 minutes in an atmospheric atmosphere. Then, a second layer of copper solder paste is coated on the lower substrate to ensure the adhesion of the copper solder paste to the chip during sintering.

[0016] In the above technical solution, oxygen first evaporates some of the organic matter in the solder paste, which helps to ensure that the organic matter is completely evaporated in the end, thereby reducing the formation of porosity and reducing the impact on the connection strength.

[0017] According to the low-temperature sintering connection method of the nano-copper material provided by the present invention, the thickness of the first layer of copper solder paste ranges from 150 to 200 μm, and the thickness of the second layer of copper solder paste ranges from 50 to 100 μm.

[0018] According to the low-temperature sintering connection method of the nano-copper material provided by the present invention, when the nano-copper material is a copper solder sheet or a copper film, the sintering process can be simplified. Sintering can be carried out in the temperature range of 80-280℃. The use of catalytic formic acid gas reduction can ensure that the copper is not oxidized, thereby obtaining a product with good connection performance and electrical properties.

[0019] According to the low-temperature sintering connection method of the nano-copper material provided by the present invention, after sintering, it is cooled in a nitrogen atmosphere until the temperature drops below 100°C.

[0020] Secondly, this invention also provides the application of the low-temperature sintering bonding method for the above-mentioned nano-copper materials in the fabrication of power semiconductors. Using this method, the highly thermally conductive DBC substrate material inside the power semiconductor and the chip can be bonded and packaged.

[0021] Thirdly, the present invention provides a catalytic device, comprising a housing and porous heating ceramic plates disposed within the housing. The number of porous heating ceramic plates is 2-10, each plate is placed vertically and parallel to the others, with its edges adhering to the inner wall of the housing. Half of each porous heating ceramic plate has a hole with a diameter of 0.1-5 mm. The phase difference between any two adjacent porous heating ceramic plates is 180°. A catalyst film is loaded on the surface of each porous heating ceramic plate.

[0022] Fourthly, the present invention provides a device system for sintering and joining nano-copper materials, comprising an argon cylinder, an anti-backflow bottle, a heating module, a solution bottle containing formic acid solution, a catalytic module, and a packaging device connected in sequence. The packaging device is further connected to a nitrogen cylinder, a sintering control module, a waste gas recovery device, a mechanical pump, and a pressurizing device. The catalytic module is connected to a catalytic control module.

[0023] Furthermore, the catalytic module employs the aforementioned catalytic device.

[0024] This invention provides a low-temperature sintering bonding method for nano-copper materials. It utilizes a catalyst in the form of a nano-film to catalyze formic acid, and performs low-temperature sintering bonding of nano-copper materials under a specific sintering process window. This method can solve the difficult problems of weak mechanical properties and poor electrical properties of nano-copper materials. Moreover, this sintering bonding method has significant reduction effect, is economical and environmentally friendly, and has high efficiency. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the device system structure for sintering and joining nano-copper materials according to the present invention;

[0026] Figure 2 A flowchart illustrating the sintering and bonding method for nano-copper materials;

[0027] Figure 3 Three-view diagram of a porous heating ceramic plate;

[0028] Figure 4 This is a schematic diagram of the formic acid catalytic module.

[0029] Figure 5 This is a scanning electron microscope (SEM) image of the catalyst coating surface;

[0030] Figure 6 This is a scanning electron microscope (SEM) image of the cross-section of the catalyst coating;

[0031] Figure 7 The pressure sintering temperature profile for Example 1;

[0032] Figure 8 This is a scanning electron microscope image of the pressure bonding layer in Example 1;

[0033] Figure 9 The pressureless sintering temperature curve for Example 2;

[0034] Figure 10 This is a scanning electron microscope image of the pressureless bonding layer in Example 2;

[0035] Figure 11 The pressure sintering temperature curve is for Comparative Example 1.

[0036] Figure 12 This is a scanning electron microscope image of the pressure-bonded layer in Comparative Example 1. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0038] This invention provides a device system for sintering and joining nano-copper materials, the structural schematic of which is shown in the figure below. Figure 1 As shown in the diagram. 1 is an N2 gas cylinder, 2 is an Ar gas cylinder, 3 is an anti-backflow bottle, 4 is a heating module, 5 is a solution bottle containing formic acid solution, 6 is a catalytic control module, 7 is a catalytic module, 8 is a packaging device, 9 is a sintering control module, 10 is a waste gas recovery device, 11 is a mechanical pump, and 12 is a pressurization device.

[0039] The specific operation process for sintering and bonding nano-copper materials in this invention is as follows: Figure 2 As shown.

[0040] The first step, before sintering, is to prepare solder paste by mixing the prepared copper powder with an organic compound (one or more of ethylene glycol, glycerol, and α-terpineol) using an ultrasonic vibrator for at least 12 hours. This process ensures thorough mixing of the powder and the organic compound. Next, the sintering sample is processed by immersing the lower substrate in dilute sulfuric acid for at least 5 minutes to remove the surface oxide layer. The sample is then rinsed with anhydrous ethanol to remove the adhering sulfuric acid. After drying the ethanol, copper solder paste is applied, and the sample is placed on the heating plate of the packaging equipment. Heating is performed in an atmospheric environment, utilizing atmospheric oxygen to promote the volatilization of the organic compound. The heating temperature is 80-200℃, and the heating time is 5-15 minutes. The lower substrate is then removed, and a second layer of solder paste is applied. This process allows the solder paste to better adhere to and wet the upper substrate (chip). The upper substrate is then mounted, and the cavity is closed. The thickness of the first layer of solder paste ranges from 150-200 μm, and the thickness of the second layer ranges from 50-100 μm. It should be noted that copper solder paste can also be purchased directly from the market.

[0041] The second step involves starting the mechanical pump 11 to evacuate the inner cavity of the encapsulation equipment 8, controlled by the sintering control module 9, to achieve a vacuum level of 1×10⁻⁶. -2 ~1×10 -4 Mechanical pump 11 is shut off when Pa is reached.

[0042] The third step involves opening the valve of Ar gas cylinder 2, allowing Ar to pass through the anti-backflow bottle 3, heating module 4, and solution bottle 5, reaching the catalytic module 7 where it is catalyzed. The Ar gas flow rate ranges from 0.1 to 5 L / min. Heating module 4 heats the Ar gas at a temperature range of 25-100℃. The heated gas, after passing through solution bottle 5, facilitates the volatilization of formic acid. The formic acid content can be controlled by adjusting the heating temperature and Ar gas flow rate. Catalytic module 7 utilizes Pt or Pd nanofilms to catalyze formic acid. Catalytic control module 6 controls the catalytic temperature, ranging from 100 to 300℃. The catalyzed formic acid is then introduced into the encapsulation device 8. The sintering control module 9 then opens the vent valve to control the gas pressure within the chamber, maintaining it between 0.01 and 1000 Pa.

[0043] The catalytic module 7 contains 2-10 porous heating ceramic plates, each placed vertically with its edges flush against the inner wall of the module. The phase difference between any two adjacent plates is 180°, ensuring that gas passing through the pores of one plate is always blocked by the next, forcing it to circulate within the module and thus ensuring sufficient catalysis of formic acid. Furthermore, each ceramic plate can be heated individually with controllable temperature via the catalytic control module 6. Small holes, each with a diameter of 0.1-5 mm, are located in half of each ceramic plate. The surface of the ceramic plates undergoes pulsed laser deposition (PLD) coating. High-pressure (100-10000 Pa) dual-target deposition is used during PLD, resulting in a loosely porous film that bonds well to the ceramic plate and is not easily dispersed by gas. The coating layer can be either Pt or Pd. A schematic diagram of the porous heating ceramic plate is shown below. Figure 3 As shown, a schematic diagram of the catalytic module 7 is as follows. Figure 4 As shown, the electron microscope scanning image of the catalyst coating is as follows: Figure 5-6 As shown (the catalyst in the figure is Pt). It should be noted that all schematic diagrams are for illustrative purposes only and do not correspond to the structural parameters of actual equipment. For example, porous heating ceramic plates are not limited to circles; they can also be squares or other shapes, and the number of holes may not be as shown in the figure.

[0044] The fourth step is to start sintering. Under formic acid conditions, the sintering sample is heated by the sintering control module 9 to volatilize the organic matter. The heating temperature is 80-200℃ and the heating time is 5-10 minutes. After the sample temperature reaches the required level, the pressurization device 12 is turned on. The pressure is adjusted to the corresponding value according to the sintering area in advance (F = p * s, where F is the pressure, p is the pressure intensity, and s is the area of ​​the upper substrate (chip)). After pressurization, the pressure is kept constant. The pressure range is 0-30 MPa (when it is 0, the pressurization device 12 does not need to be turned on). The heating temperature range is 0-280℃ and can be adjusted in a gradient. The sintering time range is 3-30 minutes. Formic acid mixed gas is continuously introduced during the sintering process.

[0045] Fifth step: Close Ar gas cylinder 2 and open N2 gas cylinder 1. Open the vent valve of the packaging device 8 to allow the sintered sample to cool in an N2 environment. Use the sintering control module 9 to maintain the gas pressure between 0.01-1000 Pa until the sample temperature drops below 100℃. Then close N2 gas cylinder 1 and the vent valve of the packaging device 8, remove the sample, and allow it to cool at room temperature.

[0046] Under this operating procedure and process window, the reduction sintering layer is achieved by using catalytically catalyzed formic acid gas, which enables the sample to achieve good bonding results even at low temperatures.

[0047] Example 1

[0048] A 10mm*10mm*2mm copper plate was used as the lower substrate, and a 3mm*3mm*2mm copper plate as the upper substrate. Before sintering, solder paste was prepared by ultrasonically vibrating nano-copper powder with organic matter for 12 hours. Then, the sample lower substrate was immersed in dilute sulfuric acid for 5 minutes, rinsed with anhydrous ethanol, dried, and coated with a 150μm thick layer of solder paste. It was then placed on the lower heating plate of the packaging equipment and heated at 160℃ for 10 minutes under atmospheric pressure. After removing the lower substrate, a second 50μm thick layer of solder paste was applied before mounting. After mounting, the sample was placed back on the lower heating plate of the packaging equipment, and the cavity door was closed.

[0049] The valve of Ar gas cylinder 2 is opened, allowing Ar to pass through the anti-backflow bottle 3, heating module 4, and solution bottle 5, reaching the catalytic module 7 where it is catalyzed. The Ar gas flow rate is 2 L / min. Heating module 4 heats the Ar gas to a temperature of 60°C. Catalytic module 7 uses Pt to catalyze formic acid, and catalytic control module 6 controls the catalytic temperature at 180°C. The catalyzed formic acid mixture is then introduced into the encapsulation equipment 8. Sintering control module 9 opens the vent valve to control the gas pressure within the chamber, maintaining it at 0.5 Pa.

[0050] Sintering begins, with a catalyzed formic acid mixture continuously introduced during the sintering process. The temperature profile of the pressurized sintering process used is shown in the figure. Figure 7 As shown, 60℃ is the initial temperature. The heating plate inside the packaging equipment is heated at a rate of 20℃ / min. When it reaches 160℃, it is held for 5 minutes to allow the second layer of organic matter to volatilize. Then, the temperature is rapidly increased to 180℃ and pressurization is started. The auxiliary pressure is 10 MPa. After holding for 15 minutes, the pressurization and heating are stopped.

[0051] Close Ar cylinder 2 and open N2 cylinder 1 to cool the sintered sample in an N2 environment, controlling the gas pressure at 5 Pa until the sample temperature drops below 100℃. After sintering, close N2 cylinder 1 and the vent valve of the encapsulation device 8, remove the sample, and cool it to room temperature. The shear strength of the sintered sample reached 55 MPa. The scan image of the pressure bonding layer is shown below. Figure 8 As shown.

[0052] Example 2

[0053] A 10mm*10mm*2mm copper plate was used as the lower substrate, and a 3mm*3mm*2mm copper plate as the upper substrate. Before sintering, solder paste was prepared by ultrasonically vibrating nano-copper powder with organic matter for 12 hours. Then, the sample lower substrate was immersed in dilute sulfuric acid for 5 minutes, rinsed with anhydrous ethanol, dried, and coated with a 150μm thick layer of solder paste. It was then placed on the lower heating plate of the packaging equipment and heated at 160℃ for 10 minutes under atmospheric pressure. After removing the lower substrate, a second 50μm thick layer of solder paste was applied before mounting. After mounting, the sample was placed back on the lower heating plate of the packaging equipment, and the cavity door was closed.

[0054] The valve of Ar gas cylinder 2 is opened, allowing Ar to pass through the anti-backflow bottle 3, heating module 4, and solution bottle 5, reaching the catalytic module 7 where it is catalyzed. The Ar gas flow rate is 2 L / min. Heating module 4 heats the Ar gas to a temperature of 60°C. Catalytic module 7 uses Pt to catalyze formic acid, and catalytic control module 6 controls the catalytic temperature at 180°C. The catalyzed formic acid mixture is then introduced into the encapsulation equipment 8. Sintering control module 9 opens the vent valve to control the gas pressure within the chamber, maintaining it at 0.5 Pa.

[0055] Sintering begins, with a continuously introduced catalyzed formic acid mixture during the sintering process. The temperature profile of the pressureless sintering process used is shown in the figure. Figure 9 As shown, 60℃ is the initial temperature. The heating plate inside the packaging equipment is heated at a rate of 20℃ / min. When it reaches 160℃, it is held for 5 minutes to allow the second layer of organic matter to volatilize. Then, the temperature is rapidly increased to 250℃ and held for 15 minutes before heating is stopped.

[0056] Close Ar cylinder 2 and open N2 cylinder 1 to cool the sintered sample in an N2 environment, controlling the pressure at 15 Pa until the sample temperature drops below 100°C. After sintering, close N2 cylinder 1 and the vent valve of the encapsulation device 8, remove the sample, and cool it to room temperature. The shear strength of the sintered sample reached 30 MPa. The pressureless bonding layer scanning image is shown below. Figure 10 As shown.

[0057] Comparative Example 1

[0058] A 10mm*10mm*2mm copper plate was used as the lower substrate, and a 3mm*3mm*2mm copper plate as the upper substrate. Before sintering, solder paste was prepared by ultrasonically vibrating nano-copper powder with organic matter for 12 hours. Then, the sample lower substrate was immersed in dilute sulfuric acid for 5 minutes, rinsed with anhydrous ethanol, dried, and coated with a 150μm thick layer of solder paste. It was then placed on the lower heating plate of the packaging equipment and heated at 160℃ for 10 minutes under atmospheric pressure. After removing the lower substrate, a second 50μm thick layer of solder paste was applied before mounting. After mounting, the sample was placed back on the lower heating plate of the packaging equipment, and the cavity door was closed.

[0059] Open the valve of Ar gas cylinder 2 to allow Ar to flow through the anti-backflow bottle 3, heating module 4, and solution bottle 5, with an Ar gas flow rate of 2 L / min. Heating module 4 is not used for heating. Do not activate the catalytic control module 6. Remove the porous heating ceramic plate; catalytic module 7 is used only as a gas passage. Formic acid mixture is introduced into the encapsulation equipment 8. The sintering control module 9 opens the vent valve to control the gas pressure within the chamber, maintaining it at 0.5 Pa.

[0060] Sintering begins, with formic acid mixed gas continuously introduced during the sintering process. The temperature profile of the pressurized sintering process used is as follows: Figure 11 As shown, 60℃ is the initial temperature. The heating plate inside the packaging equipment is heated at a rate of 20℃ / min. When it reaches 160℃, it is held for 5 minutes to allow the second layer of organic matter to volatilize. Then, the temperature is rapidly increased to 180℃ and pressurization is started. The auxiliary pressure is 10 MPa. After holding for 15 minutes, the pressurization and heating are stopped.

[0061] Close Ar cylinder 2 and open N2 cylinder 1 to cool the sintered sample in an N2 environment, controlling the gas pressure at 5 Pa until the sample temperature drops below 100℃. After sintering, close N2 cylinder 1 and the vent valve of the encapsulation device 8, remove the sample, and cool it to room temperature. The shear strength of the sintered sample reached 32 MPa. The scan image of the pressure bonding layer is shown below. Figure 12 As shown.

[0062] Comparative Example 2

[0063] A 10mm*10mm*1mm copper plate was used as the lower substrate, and a 3mm*3mm*1mm copper plate as the upper substrate. Before sintering, solder paste was prepared by ultrasonically vibrating nano-copper powder with organic matter for 12 hours. The lower substrate was then immersed in dilute sulfuric acid for 5 minutes, rinsed with anhydrous ethanol, dried, and coated with solder paste. The sample was then heated at 150℃ for 15 minutes to slowly remove the organic matter. Finally, at 250℃ under an Ar atmosphere, C-Pt catalyzed formic acid was used, with a heating rate maintained at 15℃ / min and a pressure of 5 MPa. After sintering, the shear strength of the sintered sample reached 25 MPa.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-temperature sintering bonding method for nano-copper materials, characterized in that, include: Sintering is carried out in a catalytic formic acid gas atmosphere. During the sintering process, the temperature is first raised to 80-200℃ and held for 5-10 minutes. Then, sintering is continued for 3-30 minutes under the conditions of pressure 0-30MPa and temperature 0-280℃. In this method, a catalyst film loaded on the surface of a porous heated ceramic sheet is used to catalyze formic acid gas.

2. The low-temperature sintering connection method for nano-copper materials according to claim 1, characterized in that, The catalyst film is a Pt nanofilm or a Pd nanofilm, and the catalyst film is loaded onto the surface of a porous heated ceramic sheet by pulsed laser deposition.

3. The low-temperature sintering connection method for nano-copper materials according to claim 2, characterized in that, The thickness of the porous heating ceramic sheet is 2-50 mm, and the thickness of the catalyst film is 10-1000 μm.

4. The low-temperature sintering connection method for nano-copper materials according to claim 2, characterized in that, The porous heating ceramic sheet has pores with a diameter of 0.1-5 mm, and the porous heating ceramic sheet controls the catalytic temperature at 100-300℃.

5. The low-temperature sintering connection method for nano-copper materials according to claim 4, characterized in that, The pores on the porous heating ceramic sheet are concentrated in half of the porous heating ceramic sheet. In the process of catalyzing formic acid gas, 2-10 porous heating ceramic sheets loaded with catalyst films are used. The phase difference between each two adjacent porous heating ceramic sheets is 180°, so that the pores are staggered.

6. The low-temperature sintering joining method for nano-copper materials according to any one of claims 1-5, characterized in that, The nano-copper material is copper solder paste. Before sintering, a layer of copper solder paste is first coated on the lower substrate and heated at 80-200℃ for 5-15 minutes in an atmospheric atmosphere. Then, a second layer of copper solder paste is coated on the lower substrate to ensure the adhesion of the copper solder paste to the chip during sintering.

7. The low-temperature sintering connection method for nano-copper materials according to claim 6, characterized in that, The thickness of the first layer of copper solder paste ranges from 150 to 200 μm, and the thickness of the second layer of copper solder paste ranges from 50 to 100 μm.

8. The low-temperature sintering joining method for nano-copper materials according to any one of claims 1-5, characterized in that, After sintering, the mixture is cooled in a nitrogen atmosphere until the temperature drops below 100°C.

9. The application of the low-temperature sintering bonding method for the nano-copper material according to any one of claims 1-8 in the preparation of power semiconductors.

10. The catalytic device prepared by the sintering connection method according to any one of claims 1-8, characterized in that, The device includes a housing and porous heating ceramic plates disposed within the housing. The number of porous heating ceramic plates is 2-10, each plate is placed vertically and parallel to each other, and its edges are attached to the inner wall of the housing. Half of each porous heating ceramic plate has holes with a diameter of 0.1-5 mm. The phase difference between any two adjacent porous heating ceramic plates is 180°. A catalyst film is loaded on the surface of each porous heating ceramic plate.

11. The apparatus system used in the sintering joining method according to any one of claims 1-8, characterized in that, The device includes an argon cylinder, an anti-backflow bottle, a heating module, a solution bottle containing formic acid solution, a catalytic module, and a packaging device connected in sequence. The packaging device is also connected to a nitrogen cylinder, a sintering control module, a waste gas recovery device, a mechanical pump, and a pressurizing device. The catalytic module is connected to a catalytic control module.

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