Aluminum silicon carbide power substrate and preparation method thereof

Abstract

The application relates to the technical field of power substrates, in particular to a power substrate based on aluminum silicon carbide and a preparation method thereof, which comprises the following steps: first, printing an insulating film on the surface of an aluminum silicon carbide base, then printing a conductor soldering point and sintering, and then welding a component, wherein the power device is welded by a reflow soldering process. In the application, aluminum silicon carbide is used as a base material, an insulating film is first printed on the base material by a thick film process, a soldering point for welding is printed on the insulating film, and then a component can be welded, and finally paint or glue is coated for protection; the insulating layer adopts a silicon resin system, and is more matched with the thermal expansion coefficient of aluminum silicon carbide.

Description

Technical Field

[0001] This invention relates to the field of power substrate technology, and specifically to a power substrate based on aluminum silicon carbide and its preparation method. Background Technology

[0002] In today's rapidly developing era of electronic information technology, power electronic devices are widely used in many fields such as new energy vehicles, smart grids, rail transportation, and industrial automation. As these fields continue to increase the performance requirements of power devices, the performance of the power substrate, as a key supporting component, is becoming an increasingly important factor affecting the stability, reliability, and efficiency of the entire system. Power substrates use ceramic as the substrate and copper oxide bonding, but ceramic has poor thermal conductivity, requiring heat sinks, and copper bonding is costly. In addition, some power substrates use alumina, aluminum nitride, etc. as the substrate, but their thermal conductivity is also poor.

[0003] Existing power substrates are often manufactured by printing between insulating and conductive layers, which often results in poor interlayer peelability and low insulation resistance of the insulating layer, limiting the efficiency of the product. This invention provides further improvements to these processes. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the purpose of this invention is to provide a flexible waterproof slurry and its preparation method to solve the problems mentioned in the background art.

[0005] The present invention solves the technical problem by adopting the following technical solution:

[0006] This invention provides a method for fabricating a power substrate based on aluminum silicon carbide material, comprising the following steps:

[0007] First, an insulating film is printed on the surface of the aluminum silicon carbide substrate, then the conductor solder joints are printed and sintered, and then the components are soldered. The power devices are soldered using a reflow soldering process.

[0008] Finally, the protective layer is coated and cured. The protective layer is coated and cured by dip-coating with vinyl-terminated polydimethylsiloxane to cover the substrate surface and components, with a coverage thickness of 50-100μm, and then cured at 120℃ for 60min.

[0009] Preferably, the solder used in the reflow soldering process is Sn-3.0Ag-0.5Cu lead-free solder with a melting point of 217℃. The soldering temperature is as follows: preheating zone 150-180℃, 60s; reflow zone 240-250℃, 30s; cooling zone ≤100℃, 60s.

[0010] Preferably, the specific printing method for the printed insulating film is as follows:

[0011] Step 1: Prepare insulating slurry by mixing raw materials according to the following ratio: 15% modified alumina powder with a particle size of 1-5μm, 70% silicone resin (methylphenyl silicone resin is selected), 2% terpineol, and the remainder are additives; grind the slurry three times using a three-roll mill with roller spacing of 50μm, 30μm, and 20μm respectively to ensure uniform dispersion of the slurry and a particle size distribution D90≤10μm;

[0012] Step 2: Screen printing is performed on the aluminum silicon carbide substrate using a 325-mesh stainless steel wire mesh at a printing speed of 30-50 mm / s and a squeegee pressure of 0.1-0.3 MPa to form an insulating film with a thickness of 10-30 μm.

[0013] After printing, dry with hot air at 80-100℃ for 30-60 minutes, and then cure in a hot air oven at 350-400℃ for 1-2 hours.

[0014] Preferably, the modified alumina powder is prepared by:

[0015] Add 3-5 parts by weight of talc powder and 2-4 parts by weight of bentonite to 5-8 parts by weight of ethanol aqueous solution, then add 1-2 parts by weight of silane coupling agent and 2-4 parts by weight of β-cyclodextrin, stir thoroughly to obtain bentonite solution;

[0016] Alumina is first stirred thoroughly in bentonite liquid at a volume of 7-11 times its total volume, then filtered and dried to obtain modified alumina powder.

[0017] Preferably, the ethanol aqueous solution has a mass fraction of 75-85%; the silane coupling agent is silane coupling agent KH560.

[0018] Preferably, the additive is prepared by:

[0019] Glass fiber, nano-silica sol, and sodium citrate solution with a mass fraction of 8-11% are mixed evenly, and then urea solution with a mass fraction of 4-6% is added for ultrasonic treatment. After treatment, the mixture is filtered and dried to obtain the additive.

[0020] Alumina is improved and optimized through a specific bentonite solution. The raw materials such as talc and bentonite in the bentonite solution are blended to improve and optimize the alumina. At the same time, the additives used are glass fiber and nano-silica sol. Through the mutual optimization and improvement of the raw materials, the additives further enhance the performance of the product system and optimize the product performance.

[0021] Preferably, the ultrasonic power of the ultrasonic treatment is 350-400W, and the ultrasonic treatment lasts for 1 hour; the mass ratio of the glass fiber, nano-silica sol, sodium citrate, and urea solution is (5-8):(2-3):(11-13):5.

[0022] Preferably, the conductive paste is prepared; then, according to the component pin layout, a solder joint pattern is printed using a 200-mesh screen with a line width of 50-200μm and a thickness of 8-15μm, which is used to cover the designated area of ​​the insulating layer; after printing, it is dried at 100℃ for 40min, and then sintered in the same furnace with the insulating film at 350-400℃ for 1h.

[0023] Preferably, the conductive paste is composed of 70% silver powder, 10% glass powder, and 20% organic carrier. The organic carrier is composed of ethyl cellulose and terpineol in a weight ratio of 3:2. The paste is prepared by ball milling at a speed of 300-500 r / min for 2 hours to form a uniform paste with a viscosity of 8000-15000 mPa·s.

[0024] The present invention also provides a power substrate prepared by a method for preparing a power substrate based on aluminum silicon carbide material.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] This invention provides a power substrate using aluminum silicon carbide as the substrate. First, an insulating film is printed on this substrate using a thick-film process. Solder joints and other components are then printed on the insulating film, allowing for the soldering of components. Finally, a protective coating of paint or adhesive is applied. The insulating layer uses a silicone resin system, which has a better match with the thermal expansion coefficient of aluminum silicon carbide. After 1000 cycles of thermal shock from -55°C to 125°C, the insulating layer shows no cracking, solving the problem of traditional ceramic insulating layers easily detaching due to thermal mismatch. After curing, the volume resistivity of the insulating layer is ≥10. 14 Ω·cm, breakdown electric field strength ≥20kV / mm, peel strength from aluminum silicon carbide substrate ≥5N / cm, meeting the insulation requirements of power substrate. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to specific examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] This embodiment describes a method for fabricating a power substrate based on aluminum silicon carbide material, comprising the following steps:

[0029] First, an insulating film is printed on the surface of the aluminum silicon carbide substrate, then the conductor solder joints are printed and sintered, and then the components are soldered. The power devices are soldered using a reflow soldering process.

[0030] Finally, the protective layer is coated and cured. The protective layer is coated and cured by dip-coating with vinyl-terminated polydimethylsiloxane to cover the substrate surface and components, with a coverage thickness of 50-100μm, and then cured at 120℃ for 60min.

[0031] In this embodiment, the reflow soldering process uses Sn-3.0Ag-0.5Cu lead-free solder with a melting point of 217℃. The soldering temperature is as follows: preheating zone 150-180℃, 60s; reflow zone 240-250℃, 30s; cooling zone ≤100℃, 60s.

[0032] The specific printing method for the insulating film in this embodiment is as follows:

[0033] Step 1: Prepare insulating slurry by mixing raw materials according to the following ratio: 15% modified alumina powder with a particle size of 1-5μm, 70% silicone resin (methylphenyl silicone resin is selected), 2% terpineol, and the remainder are additives; grind the slurry three times using a three-roll mill with roller spacing of 50μm, 30μm, and 20μm respectively to ensure uniform dispersion of the slurry and a particle size distribution D90≤10μm;

[0034] Step 2: Screen printing is performed on the aluminum silicon carbide substrate using a 325-mesh stainless steel wire mesh at a printing speed of 30-50 mm / s and a squeegee pressure of 0.1-0.3 MPa to form an insulating film with a thickness of 10-30 μm.

[0035] After printing, dry with hot air at 80-100℃ for 30-60 minutes, and then cure in a hot air oven at 350-400℃ for 1-2 hours.

[0036] The method for preparing the modified alumina powder in this embodiment is as follows:

[0037] Add 3-5 parts by weight of talc powder and 2-4 parts by weight of bentonite to 5-8 parts by weight of ethanol aqueous solution, then add 1-2 parts by weight of silane coupling agent and 2-4 parts by weight of β-cyclodextrin, stir thoroughly to obtain bentonite solution;

[0038] Alumina is first stirred thoroughly in bentonite liquid at a volume of 7-11 times its total volume, then filtered and dried to obtain modified alumina powder.

[0039] The ethanol aqueous solution in this embodiment has a mass fraction of 75-85%; the silane coupling agent is silane coupling agent KH560.

[0040] The preparation method of the additive in this embodiment is as follows:

[0041] Glass fiber, nano-silica sol, and sodium citrate solution with a mass fraction of 8-11% are mixed evenly, and then urea solution with a mass fraction of 4-6% is added for ultrasonic treatment. After treatment, the mixture is filtered and dried to obtain the additive.

[0042] In this embodiment, the ultrasonic power of the ultrasonic treatment is 350-400W, and the ultrasonic treatment lasts for 1 hour; the mass ratio of the glass fiber, nano silica sol, sodium citrate, and urea solution is (5-8):(2-3):(11-13):5.

[0043] The conductive paste in this embodiment is prepared as follows: according to the component pin layout, a solder joint pattern is printed using a 200-mesh screen with a line width of 50-200μm and a thickness of 8-15μm, which is used to cover the specified area of ​​the insulating layer; after printing, it is dried at 100℃ for 40min, and then sintered with the insulating film in the same furnace at 350-400℃ for 1h.

[0044] The conductive paste in this embodiment consists of 70% silver powder, 10% glass powder, and 20% organic carrier. The organic carrier is composed of ethyl cellulose and terpineol in a weight ratio of 3:2. The paste is ball-milled at a speed of 300-500 r / min for 2 hours to produce a uniform paste with a viscosity of 8000-15000 mPa·s.

[0045] This embodiment describes a method for preparing a power substrate based on aluminum silicon carbide material.

[0046] Example 1.

[0047] This embodiment describes a method for fabricating a power substrate based on aluminum silicon carbide material, comprising the following steps:

[0048] First, an insulating film is printed on the surface of the aluminum silicon carbide substrate, then the conductor solder joints are printed and sintered, and then the components are soldered. The power devices are soldered using a reflow soldering process.

[0049] Finally, the protective layer is coated and cured. The protective layer is coated and cured by dip-coating with vinyl-terminated polydimethylsiloxane to cover the substrate surface and components, with a coverage thickness of 50μm, and then cured at 120℃ for 60min.

[0050] In this embodiment, the reflow soldering process uses Sn-3.0Ag-0.5Cu lead-free solder with a melting point of 217℃. The soldering temperature is as follows: preheating zone 150℃, 60s; reflow zone 240℃, 30s; cooling zone ≤100℃, 60s.

[0051] The specific printing method for the insulating film in this embodiment is as follows:

[0052] Step 1: Prepare insulating slurry by mixing raw materials according to the following ratio: 15% modified alumina powder with a particle size of 1μm, 70% silicone resin (methylphenyl silicone resin is selected), 2% terpineol, and the remainder are additives; grind the slurry three times using a three-roll mill with roller spacing of 50μm, 30μm, and 20μm respectively to ensure uniform dispersion of the slurry and a particle size distribution D90≤10μm;

[0053] Step 2: Screen printing is performed on the aluminum silicon carbide substrate using a 325-mesh stainless steel wire mesh at a printing speed of 30 mm / s and a squeegee pressure of 0.1 MPa to form an insulating film with a thickness of 10 μm.

[0054] After printing, the product is first dried in hot air at 80℃ for 30 minutes, and then cured in a hot air oven at 350℃ for 1 hour.

[0055] The method for preparing the modified alumina powder in this embodiment is as follows:

[0056] Add 3 parts by weight of talc powder and 2 parts by weight of bentonite to 5 parts by weight of ethanol aqueous solution, then add 1 part by weight of silane coupling agent and 2 parts by weight of β-cyclodextrin, stir thoroughly to obtain bentonite solution;

[0057] The alumina was first stirred thoroughly in a bentonite solution with a total volume of alumina of 7 times, then filtered and dried to obtain modified alumina powder.

[0058] In this embodiment, the ethanol aqueous solution has a mass fraction of 75%; the silane coupling agent is silane coupling agent KH560.

[0059] The preparation method of the additive in this embodiment is as follows:

[0060] Glass fiber, nano-silica sol, and 8% sodium citrate solution were mixed evenly, and then 4% urea solution was added for ultrasonic treatment. After treatment, the mixture was filtered and dried to obtain the additive.

[0061] In this embodiment, the ultrasonic power of the ultrasonic treatment is 350W, and the ultrasonic treatment lasts for 1 hour; the mass ratio of the glass fiber, nano-silica sol, sodium citrate, and urea solution is 5:2:11:5.

[0062] The conductive paste in this embodiment is prepared as follows: according to the component pin layout, a solder joint pattern is printed using a 200-mesh screen with a line width of 50-200μm and a thickness of 8-15μm, which is used to cover the specified area of ​​the insulating layer; after printing, it is dried at 100℃ for 40min, and then sintered with the insulating film in the same furnace at 350-400℃ for 1h.

[0063] The conductive paste in this embodiment consists of 70% silver powder, 10% glass powder, and 20% organic carrier. The organic carrier is composed of ethyl cellulose and terpineol in a weight ratio of 3:2. The paste is ball-milled at 300 r / min for 2 h to produce a uniform paste with a viscosity of 8000 mPa·s.

[0064] This embodiment describes a method for preparing a power substrate based on aluminum silicon carbide material.

[0065] Example 2.

[0066] This embodiment describes a method for fabricating a power substrate based on aluminum silicon carbide material, comprising the following steps:

[0067] First, an insulating film is printed on the surface of the aluminum silicon carbide substrate, then the conductor solder joints are printed and sintered, and then the components are soldered. The power devices are soldered using a reflow soldering process.

[0068] Finally, the protective layer is coated and cured. The protective layer is coated and cured by dip-coating with vinyl-terminated polydimethylsiloxane to cover the substrate surface and components, with a coverage thickness of 100μm, and then cured at 120℃ for 60min.

[0069] In this embodiment, the reflow soldering process uses Sn-3.0Ag-0.5Cu lead-free solder with a melting point of 217℃. The soldering temperature is as follows: preheating zone 180℃, 60s; reflow zone 250℃, 30s; cooling zone ≤100℃, 60s.

[0070] The specific printing method for the insulating film in this embodiment is as follows:

[0071] Step 1: Prepare insulating slurry by mixing raw materials according to the following ratio: 15% modified alumina powder with a particle size of 5μm, 70% silicone resin (methylphenyl silicone resin is selected), 2% terpineol, and the remainder are additives; grind the slurry three times using a three-roll mill with roller spacing of 50μm, 30μm, and 20μm respectively to ensure uniform dispersion of the slurry and a particle size distribution D90≤10μm;

[0072] Step 2: Screen printing is performed on the aluminum silicon carbide substrate using a 325-mesh stainless steel wire mesh at a printing speed of 50 mm / s and a squeegee pressure of 0.3 MPa to form an insulating film with a thickness of 30 μm.

[0073] After printing, the product is first dried in hot air at 100℃ for 60 minutes, and then cured in a hot air oven at 400℃ for 2 hours.

[0074] The method for preparing the modified alumina powder in this embodiment is as follows:

[0075] Add 5 parts by weight of talc powder and 4 parts by weight of bentonite to 8 parts by weight of ethanol aqueous solution, then add 2 parts by weight of silane coupling agent and 4 parts by weight of β-cyclodextrin, stir thoroughly to obtain bentonite solution;

[0076] The alumina was first stirred thoroughly in a bentonite solution with a total volume of 11 times the alumina, then filtered and dried to obtain modified alumina powder.

[0077] In this embodiment, the ethanol aqueous solution has a mass fraction of 85%; the silane coupling agent is silane coupling agent KH560.

[0078] The preparation method of the additive in this embodiment is as follows:

[0079] Glass fiber, nano-silica sol, and 11% sodium citrate solution were mixed evenly, and then 6% urea solution was added for ultrasonic treatment. After treatment, the mixture was filtered and dried to obtain the additive.

[0080] In this embodiment, the ultrasonic power of the ultrasonic treatment is 400W, and the ultrasonic treatment lasts for 1 hour; the mass ratio of the glass fiber, nano-silica sol, sodium citrate, and urea solution is 8:3:13:5.

[0081] The conductive paste in this embodiment is prepared as follows: according to the component pin layout, a solder joint pattern is printed using a 200-mesh screen with a line width of 200μm and a thickness of 15μm, which is used to cover the specified area of ​​the insulating layer; after printing, it is dried at 100℃ for 40min, and then sintered with the insulating film in the same furnace at 400℃ for 1h.

[0082] The conductive paste in this embodiment consists of 70% silver powder, 10% glass powder, and 20% organic carrier. The organic carrier is composed of ethyl cellulose and terpineol in a weight ratio of 3:2. The paste is prepared by ball milling at 500 r / min for 2 hours to form a uniform paste with a viscosity of 15000 mPa·s.

[0083] This embodiment describes a method for preparing a power substrate based on aluminum silicon carbide material.

[0084] Example 3.

[0085] This embodiment describes a method for fabricating a power substrate based on aluminum silicon carbide material, comprising the following steps:

[0086] First, an insulating film is printed on the surface of the aluminum silicon carbide substrate, then the conductor solder joints are printed and sintered, and then the components are soldered. The power devices are soldered using a reflow soldering process.

[0087] Finally, the protective layer is coated and cured. The protective layer is coated and cured by dip-coating with vinyl-terminated polydimethylsiloxane to cover the substrate surface and components, with a coverage thickness of 50-100μm, and then cured at 120℃ for 60min.

[0088] In this embodiment, the reflow soldering process uses Sn-3.0Ag-0.5Cu lead-free solder with a melting point of 217℃. The soldering temperature is as follows: preheating zone 165℃, 60s; reflow zone 245℃, 30s; cooling zone ≤100℃, 60s.

[0089] The specific printing method for the insulating film in this embodiment is as follows:

[0090] Step 1: Prepare insulating slurry by mixing raw materials according to the following ratio: 15% modified alumina powder with a particle size of 1-5μm, 70% silicone resin (methylphenyl silicone resin is selected), 2% terpineol, and the remainder are additives; grind the slurry three times using a three-roll mill with roller spacing of 50μm, 30μm, and 20μm respectively to ensure uniform dispersion of the slurry and a particle size distribution D90≤10μm;

[0091] Step 2: Screen printing is performed on the aluminum silicon carbide substrate using a 325-mesh stainless steel wire mesh at a printing speed of 40 mm / s and a squeegee pressure of 0.2 MPa to form an insulating film with a thickness of 20 μm.

[0092] After printing, the product is first dried in hot air at 90℃ for 45 minutes, and then cured in a hot air oven at 365℃ for 1.5 hours.

[0093] The method for preparing the modified alumina powder in this embodiment is as follows:

[0094] Add 4 parts by weight of talc powder and 3 parts by weight of bentonite to 6.5 parts by weight of ethanol aqueous solution, then add 1.5 parts by weight of silane coupling agent and 3 parts by weight of β-cyclodextrin, stir thoroughly to obtain bentonite solution;

[0095] The alumina was first stirred thoroughly in a bentonite solution with a total volume of alumina of 9 times, then filtered and dried to obtain modified alumina powder.

[0096] In this embodiment, the ethanol aqueous solution has a mass fraction of 80%; the silane coupling agent is silane coupling agent KH560.

[0097] The preparation method of the additive in this embodiment is as follows:

[0098] Glass fiber, nano-silica sol, and 9% sodium citrate solution were mixed evenly, and then 5% urea solution was added for ultrasonic treatment. After treatment, the mixture was filtered and dried to obtain the additive.

[0099] In this embodiment, the ultrasonic power of the ultrasonic treatment is 375W, and the ultrasonic treatment lasts for 1 hour; the mass ratio of the glass fiber, nano-silica sol, sodium citrate, and urea solution is 6.5:2.5:12:5.

[0100] The conductive paste in this embodiment is prepared as follows: according to the component pin layout, a solder joint pattern is printed using a 200-mesh screen with a line width of 100μm and a thickness of 12μm, which is used to cover the designated area of ​​the insulating layer; after printing, it is dried at 100℃ for 40min, and then sintered in the same furnace as the insulating film at 375℃ for 1h.

[0101] The conductive paste in this embodiment consists of 70% silver powder, 10% glass powder, and 20% organic carrier. The organic carrier is composed of ethyl cellulose and terpineol in a weight ratio of 3:2. The paste is ball-milled at 400 r / min for 2 hours to produce a uniform paste with a viscosity of 11000 mPa·s.

[0102] This embodiment describes a method for preparing a power substrate based on aluminum silicon carbide material.

[0103] Comparative Example 1.

[0104] Unlike Example 3, bentonite liquid was not added during the preparation of the modified alumina powder.

[0105] Comparative Example 2.

[0106] Unlike Example 3, no talc or bentonite was added to the bentonite solution.

[0107] Comparative Example 3.

[0108] Unlike Example 3, no silane coupling agent and β-cyclodextrin were added to the bentonite solution.

[0109] Comparative Example 4.

[0110] Unlike Example 3, no additives were added.

[0111] Performance tests were conducted on Examples 1-3 and Comparative Examples 1-4, and the test results are as follows.

[0112]

[0113]

[0114] Examples 1-3 and Comparative Examples 1-4 show that after 1000 cycles of thermal shock from -55℃ to 125℃, the insulation layer of the product of the present invention does not crack, solving the problem of easy detachment of traditional ceramic insulation layers due to thermal mismatch; the volume resistivity of the insulation layer after curing is ≥10. 14 Ω·cm, breakdown electric field strength ≥20kV / mm, peel strength from aluminum silicon carbide substrate ≥5N / cm, meeting the insulation requirements of power substrate;

[0115] In the preparation of modified alumina powder, if bentonite liquid is not added, and if talc powder and bentonite are not added to the bentonite liquid, and if silane coupling agent and β-cyclodextrin are not added, and no additives are added, the performance of the product tends to deteriorate. Only the product raw material obtained by the method of this invention has the most significant performance effect.

[0116] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0117] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for fabricating a power substrate based on aluminum silicon carbide material, characterized in that, Includes the following steps: First, an insulating film is printed on the surface of the aluminum silicon carbide substrate, then the conductor solder joints are printed and sintered, and then the components are soldered. The power devices are soldered using a reflow soldering process. Finally, the protective layer is coated and cured. The protective layer is coated and cured by dip-coating with vinyl-terminated polydimethylsiloxane to cover the substrate surface and components, with a coverage thickness of 50-100μm, and then cured at 120℃ for 60min. The specific printing method for the insulating film is as follows: Step 1: Prepare insulating slurry by mixing raw materials according to the following ratio: 15% modified alumina powder with a particle size of 1-5μm, 70% silicone resin (methylphenyl silicone resin is selected), 2% terpineol, and the remainder are additives; grind the slurry three times using a three-roll mill with roller spacing of 50μm, 30μm, and 20μm respectively to ensure uniform dispersion of the slurry and a particle size distribution D90≤10μm; Step 2: Screen printing is performed on the aluminum silicon carbide substrate using a 325-mesh stainless steel wire mesh at a printing speed of 30-50 mm / s and a squeegee pressure of 0.1-0.3 MPa to form an insulating film with a thickness of 10-30 μm. After printing, dry with hot air at 80-100℃ for 30-60 minutes, and then cure in a hot air oven at 350-400℃ for 1-2 hours. The preparation method of modified alumina powder is as follows: Add 3-5 parts by weight of talc powder and 2-4 parts by weight of bentonite to 5-8 parts by weight of ethanol aqueous solution, then add 1-2 parts by weight of silane coupling agent and 2-4 parts by weight of β-cyclodextrin, stir thoroughly to obtain bentonite solution; Alumina is first stirred thoroughly in bentonite liquid at a volume of 7-11 times its total volume, then filtered and dried to obtain modified alumina powder.

2. The method for fabricating a power substrate based on aluminum silicon carbide material according to claim 1, characterized in that, In the reflow soldering process, Sn-3.0Ag-0.5Cu lead-free solder is selected, with a melting point of 217℃. The soldering temperature is as follows: preheating zone 150-180℃, 60s; reflow zone 240-250℃, 30s; cooling zone ≤100℃, 60s.

3. The method for fabricating a power substrate based on aluminum silicon carbide material according to claim 1, characterized in that, The mass fraction of the ethanol aqueous solution is 75-85%; the silane coupling agent is silane coupling agent KH560.

4. The method for fabricating a power substrate based on aluminum silicon carbide material according to claim 1, characterized in that, The preparation method of the additive is as follows: Glass fiber, nano-silica sol, and sodium citrate solution with a mass fraction of 8-11% are mixed evenly, and then urea solution with a mass fraction of 4-6% is added for ultrasonic treatment. After treatment, the mixture is filtered and dried to obtain the additive.

5. The method for fabricating a power substrate based on aluminum silicon carbide material according to claim 4, characterized in that, The ultrasonic power of the ultrasonic treatment is 350-400W, and the ultrasonic treatment lasts for 1 hour; the mass ratio of the glass fiber, nano silica sol, sodium citrate and urea solution is (5-8):(2-3):(11-13):

5.

6. The method for fabricating a power substrate based on aluminum silicon carbide material according to claim 1, characterized in that, Preparation of conductive paste; then, according to the component pin layout, use 200 mesh screen printing to print solder joint patterns with a line width of 50-200μm and a thickness of 8-15μm, which are used to cover the specified area of ​​the insulating layer; after printing, dry at 100℃ for 40min, and then sinter with the insulating film in the same furnace at 350-400℃ for 1h.

7. The method for preparing a power substrate based on aluminum silicon carbide material according to claim 6, wherein the conductive paste is composed of 70% silver powder, 10% glass powder, and 20% organic carrier, the organic carrier being a composite of ethyl cellulose and terpineol in a weight ratio of 3:2, and is prepared into a uniform paste by ball milling at a speed of 300-500 r / min for 2 hours, with a viscosity of... .

8. The power substrate prepared by the method for preparing a power substrate based on aluminum silicon carbide material as described in any one of claims 1-7.

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