High-temperature-resistant working sealing silver copper paste for power chip and preparation method of high-temperature-resistant working sealing silver copper paste

Abstract

The invention provides a high-temperature-resistant working sealing silver copper paste for a power chip, which comprises the following components in parts by mass: 45-80 parts of silver-coated copper powder, 0-60 parts of a sinterable conductive filler, 0.8-4.5 parts of a high-temperature adhesive, 0.2-0.32 part of a curing agent, 6-9 parts of an organic solvent and 0-3.1 parts of an auxiliary agent, the sinterable conductive filler is used for enhancing conductivity and sintering performance, and the sinterable conductive filler is silver powder or tin alloy powder or indium alloy powder or mixed sinterable powder composed of one or two of the conductor powder. According to the low-silver-content silver-copper paste, the silver-copper paste contains the conductive powder which can be sintered at the low temperature according to a certain proportion, so that the conductive powder which can be sintered at the low temperature and the silver layer on the surface of the silver-coated copper powder are sintered together, and the silver layer on the surface of the silver-coated copper powder can be covered; the silver sealing glue not only has the characteristics of high thermal conductivity, good high-temperature reliability, good fatigue resistance and high melting point of pure silver sealing glue, but also can reduce the cost and improve the cost performance.

Description

Technical Field

[0001] The present invention relates to the technical field of chip electronic packaging, and in particular to a high-temperature resistant working sealing silver-copper paste for a power chip and a preparation method thereof. Background Art

[0002] With the further improvement of the new generation of high-power chips and their power density, the requirements for power electronic modules and their packaging processes are also becoming increasingly higher. In particular, the interconnection technology between the chip and the substrate largely determines the power loss and reliability of the power module. Traditional solder paste has a low melting point and poor thermal conductivity, making it difficult to meet the requirements of high-power device packaging and its high-temperature application. In addition, with the rapid development of third-generation semiconductor devices (such as silicon carbide and gallium nitride), more stringent requirements are placed on the performance of packaging. The sintering temperature of low-temperature sintering silver sealing paste is equivalent to that of traditional solder paste, and the melting point after sintering reaches 961°C. It can exhibit excellent thermal and electrical conductivity under high-temperature service conditions, and will not produce the typical fatigue effect that occurs in traditional solder paste layers with a melting point of less than 300°C. It has extremely high sealing reliability and is an important sealing material for third-generation high-temperature semiconductor chips.

[0003] However, the cost of pure silver sealing paste is high. Metallic copper can be used as a sealing solder alternative material because its cost is significantly lower than silver and it has similar thermal and electrical conductivity to silver. However, copper powder is very easy to oxidize and generally requires a protective atmosphere or a reducing atmosphere during sintering. For example, Chinese patent 201710343566.8 reports a nano-copper solder paste with a sintering temperature of 310°C and requires inert gas protection during sintering. Patent publication number CN107025950A discloses the preparation of an oxidation-resistant silver-plated nano-copper powder, wherein the coating thickness of the nano-silver is between 100nm and 400nm, and the nano-silver particle size is between 40nm and 70nm. The silver-coated copper powder coated with the nano-silver particles is made into a copper solder paste, which can achieve low-temperature sintering in air while having good electrical conductivity, heat dissipation and high-temperature resistance. Patent publication number CN114378474A describes a method for coating copper powder with nanosilver particles. The nanosilver particles grow on the surface of the copper powder. A silver-coated copper paste prepared from this silver-coated copper powder can prevent copper oxidation during sintering. Although silver-coated copper powder can resist oxidation in air at room temperature and lower temperatures, the silver coating typically shrinks at temperatures of 300°C, exposing the copper. This exposure can lead to oxidation in air. For high-temperature sealing pastes, the sintering temperature is typically raised to near 300°C to save sintering time and improve production efficiency. Improving the high-temperature oxidation resistance of the silver-coated copper powder is crucial for sealing reliability. Therefore, a chip sealing silver-copper paste is urgently needed to address this high-temperature oxidation issue. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the prior art. The present invention proposes a silver-copper paste for sealing a power chip at a high temperature and a preparation method thereof.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is: a silver-copper paste for high-temperature resistant sealing of power chips, comprising, by mass, 33-90 parts of silver-coated copper powder, 0-60 parts of sinterable conductive filler, 0.8-4.5 parts of high-temperature adhesive, 0.2-0.32 parts of curing agent, 6-9 parts of organic solvent and 0-3.1 parts of additive;

[0006] The weight percentage of silver in the silver-coated copper powder is 10wt%-30wt%. The sinterable conductive filler is a metal powder for enhancing electrical conductivity and sintering performance, wherein the sinterable conductive filler is a mixed powder of silver powder and tin alloy powder or indium alloy powder, or the above conductor powders. The bondable conductive filler is a metal mixed powder for enhancing electrical conductivity and sintering performance, wherein the sinterable conductive filler is a mixed powder of silver powder, tin alloy powder and indium alloy powder.

[0007] The high-temperature adhesive is used to provide a resin system with high-temperature stability and bonding performance. The high-temperature adhesive is a thermosetting curing resin system, including a resin and a curing agent. The organic solvent is used to disperse the material and dissolve the adhesive and curing agent, and is composed of ethylene glycol butyl ether and diethylene glycol butyl ether acetate.

[0008] Furthermore, the silver-coated copper powder includes micron silver-coated copper powder, the median particle size of the micron silver-coated copper powder is 1.5 μm-6 μm, and the tap density is greater than 4.5 g / cm 3 .

[0009] Furthermore, the auxiliary agent includes at least one of a thixotropic agent, an antioxidant or a defoaming agent.

[0010] Furthermore, the mass ratio of the high-temperature adhesive to the organic solvent is (1-5):(1-10), and the mass ratio of the curing agent to the organic solvent is 1:(6-100).

[0011] Furthermore, the sinterable conductive filler comprises:

[0012] The median particle size of the silver powder is 0.1μm-0.9μm or 10nm-90nm, the tin alloy powder is Sn42Bi58 alloy powder or SnCuAg alloy powder with a median particle size of 1μm-10μm, and the indium alloy powder is InSnBi alloy powder with a median particle size of 1μm-10μm.

[0013] A method for preparing a high-temperature resistant silver-copper sealing paste for power chips, comprising the following steps:

[0014] The adhesive and curing agent are respectively mixed with an organic solvent to obtain an adhesive solution and a curing agent solution, and then the adhesive solution and the curing agent solution are mixed to obtain an adhesive system;

[0015] Mixing the silver-coated copper powder, sinterable conductive filler and additive with the binder system to obtain a primary silver-coated copper slurry;

[0016] The primary silver-coated copper slurry is ground to obtain the silver-copper paste.

[0017] Furthermore, the silver-copper paste is printed on the copper electrode surface or the silver-plated layer surface of the semiconductor chip mounting ceramic substrate, and then the chip is placed on the printed silver-coated paste. After drying and sintering, the circuit connection of the chip on the ceramic substrate is completed.

[0018] Furthermore, the sintering method includes pressureless sintering and pressure sintering, and the sintering temperature of the silver-copper paste is 200-300°C.

[0019] Furthermore, the drying temperature is 80° C.-160° C., the sintering temperature is 250° C.-300° C., and the sintering time is 5 minutes-1 hour.

[0020] Furthermore, the grinding is performed using a three-roller grinding machine, and the fineness of the silver-copper paste after grinding is less than 8 μm.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: the silver-copper paste contains a certain proportion of conductive powder that can be sintered at low temperature, so that these conductive powders that can be sintered at low temperature are sintered together with the silver layer on the surface of the silver-clad copper, and the silver layer on the surface of the silver-clad copper can be covered. The silver-copper paste with a low silver content has the characteristics of high thermal conductivity, good high-temperature reliability, good fatigue resistance, and high melting point of pure silver sealing glue, and can reduce costs and improve cost performance. It can also be sintered in air, so that it can be sintered at low temperature and serve at high temperature, and has excellent high-temperature oxidation resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The disclosure of the present invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. In the accompanying drawings, the same reference numerals are used to refer to the same components. Among them:

[0023] Figure 1 This is a schematic diagram of the preparation process of the silver-copper paste according to the embodiment of the present application;

[0024] Figure 2 This is an electron micrograph of the cross section of the silver-copper paste prepared in Example 3 of the present application after sintering;

[0025] Figure 3 Schematic diagram showing the comparison of TGA tests of the silver-copper pastes prepared in Example 3 and Comparative Examples 1 and 2 of the present application; DETAILED DESCRIPTION

[0026] It is easy to understand that according to the technical solution of the present invention, without changing the essential spirit of the present invention, a person skilled in the art can propose a variety of interchangeable structural modes and implementation modes. Therefore, the following specific embodiments and drawings are only exemplary descriptions of the technical solution of the present invention and should not be regarded as the entire invention or as a limitation or restriction of the technical solution of the present invention.

[0027] According to one embodiment of the present invention, Figure 1 Shows:

[0028] Example 1:

[0029] A silver-copper paste for high-temperature resistant sealing of power chips, comprising, by mass, 90 parts of silver-coated copper powder, 0 parts of sinterable conductive filler, 3.8 parts of high-temperature adhesive, 0.2 parts of curing agent, 6 parts of organic solvent, and 0 parts of auxiliary agent, wherein the auxiliary agent comprises at least one of a thixotropic agent, an antioxidant, or a defoaming agent;

[0030] The mass ratio of the high temperature adhesive to the organic solvent is (1-5):(1-10), and the mass ratio of the curing agent to the organic solvent is 1:(6-100);

[0031] The weight percentage of silver in the silver-coated copper powder is 10wt%-30wt%. The silver-coated copper powder includes micron silver-coated copper powder. The median particle size of the micron silver-coated copper powder is 1.5μm, and the tap density is greater than 4.5g / cm 3 .

[0032] High temperature adhesive is a resin system used to provide high temperature stability and bonding performance. The high temperature adhesive is a thermosetting curing resin system, including resin and curing agent. The organic solvent is used to disperse the material and dissolve the solvent of the adhesive and curing agent, which is composed of ethylene glycol butyl ether and diethylene glycol butyl ether acetate.

[0033] Example 2:

[0034] A silver-copper paste for high-temperature resistant sealing of power chips, comprising, by weight, 33 parts of silver-coated copper powder, 50 parts of sinterable conductive filler, 4.5 parts of high-temperature adhesive, 0.32 parts of curing agent, 9 parts of organic solvent, and 3.1 parts of additives, wherein the additives include at least one of a thixotropic agent, an antioxidant, or a defoaming agent;

[0035] The mass ratio of the high temperature adhesive to the organic solvent is (1-5):(1-10), and the mass ratio of the curing agent to the organic solvent is 1:(6-100);

[0036] The weight percentage of silver in the silver-coated copper powder is 10wt%-30wt%. The silver-coated copper powder includes micron silver-coated copper powder. The median particle size of the micron silver-coated copper powder is 6μm, and the tap density is greater than 4.5g / cm3 , a bondable conductive filler is used to enhance the conductivity and sintering performance of a metal mixed powder, wherein the sinterable conductive filler is a mixed powder composed of silver powder, tin alloy powder and indium alloy powder, and the sinterable conductive filler includes: the median particle size of the silver powder is 0.1μm-0.9μm or 10nm-90nm.

[0037] High temperature adhesive is a resin system used to provide high temperature stability and bonding performance. The high temperature adhesive is a thermosetting curing resin system, including resin and curing agent. The organic solvent is used to disperse the material and dissolve the solvent of the adhesive and curing agent, which is composed of ethylene glycol butyl ether and diethylene glycol butyl ether acetate.

[0038] Example 1 uses silver-coated copper powder with a low silver content of 20wt%, combined with a high proportion of organic solvents and a base resin system, and phenolic epoxy resin to achieve a simplified formulation design for silver-copper paste. Without the addition of sinterable conductive fillers, its resistivity (4.5μΩ·cm) and thermal conductivity (190W / mK) are still superior to traditional solder pastes, and its thrust strength (32MPa) meets the requirements of low-power packaging. This formulation ensures process stability by optimizing the binder-to-solvent mass ratio (0.8:6≈1:7.5) and the curing agent-to-solvent mass ratio (0.2:6≈1:30), making it suitable for cost-sensitive applications with moderate heat dissipation requirements while significantly reducing the amount of precious metals used.

[0039] Example 2 achieves the ultimate performance optimization of silver-copper paste by combining silver-coated copper powder with a high silver content of 30wt%, a high proportion of sinterable conductive fillers and composite additives. Its resistivity (2.8μΩ·cm) and thermal conductivity (245W / mK) are close to the level of pure silver paste, its thrust strength (50MPa) is even industry-leading, and its anti-oxidation starting temperature (530°C) is significantly improved. The uniformity of dispersion under high-filler systems is ensured by precise control of the mass ratio of adhesive to solvent (4.5:9≈1:2) and the mass ratio of curing agent to solvent (0.32:9≈1:28). This formula is particularly suitable for high temperatures and IGBT module packaging. While maintaining low costs, its performance can replace imported pure silver glue.

[0040] Example 1 focuses on low cost and simplified process, sacrificing some electrical / thermal conductivity, and is suitable for low-end packaging scenarios. Example 2 is oriented towards high performance and meets the requirements of harsh working conditions through the synergistic effect of high silver fillers and additives.

[0041] According to one embodiment of the present invention, Figure 2-Figure 3 Shows:

[0042] Example 3:

[0043] The preparation method of the silver-copper paste provided in the embodiment of the present application is as follows:

[0044] 0.32g of novolac epoxy resin (product model F51) and 0.4g of hexamethylene diisocyanate (HDI) were evenly dispersed in 1.6g of diethylene glycol butyl ether acetate to obtain mixed solution A, i.e., the epoxy resin solution system. 0.03g of imidazole curing agent 2E4MZ was evenly dispersed in mixed solution A to obtain the curing agent solution system. Mixed solution A and the curing agent solution were mixed to obtain the adhesive system.

[0045] 12g of micron silver-coated copper powder and 8g of submicron silver powder were added to the above-mentioned bonding system and thoroughly mixed in a centrifugal mixer for 15 seconds to obtain a primary silver-coated copper slurry. The silver-coated copper powder had a D50 of 3.8μm, a tap density of 5g / cm³, a silver weight percentage of 20wt%, a silver coating with a pinporosity of 4% and a thickness of 80nm. The submicron silver powder had a D50 of 0.3μm and a tap density of 4.2g / cm³.

[0046] The primary silver-copper paste product is dispersed by a three-roller rolling mill to obtain a final product with a fineness of less than 8 μm, namely the silver-copper paste, which is stored at a low temperature of -18°C for future use.

[0047] The product viscosity, measured using a Brookfield DV-E viscometer, was 170 Pa.s. The resistivity of the silver-copper paste after sintering at 250°C, measured using the four-probe method, was 3.4 μΩ·cm. The thermal conductivity of the silver-copper paste after sintering at 250°C, measured using a laser method, was 210 W / mK. The resistivity after sintering at 300°C was 3 μΩ·cm. The thermal conductivity of the silver-copper paste after sintering at 300°C, measured using a laser method, was 235 W / mK. The resistivity of this silver-copper paste was even lower when sintered at the higher temperature of 300°C, demonstrating its excellent high-temperature oxidation resistance.

[0048] Thrust strength test:

[0049] The prepared silver coating paste was printed onto the copper electrode surface or the silver-plated layer surface of the DBC substrate using a 100 μm thick stainless steel stencil with an opening of 5 mm×5 mm at a printing speed of 150 m / s.

[0050] A:Pressureless sintering:

[0051] A 4mm x 4mm dummy chip (a 4mm x 4mm x 1mm thick silicon wafer coated with silver) was placed on the printed silver paste. The sample was then slowly heated to 250°C in an oven, sintered at 250°C for one hour, and then slowly cooled to room temperature.

[0052] B: Pressure sintering

[0053] A 4mm x 4mm analog chip was placed on the printed silver paste and dried in a 160°C oven. Then, it was sintered in a hot press at 250°C for 10 minutes at a pressure of 15 MPa. The pressure sintering was then completed by slowly cooling it to room temperature.

[0054] To shorten the pressure sintering time, the sintering temperature was increased to 300°C, the pressure sintering time was 5 minutes, and the pressure was 15 MPa. Then it was slowly cooled to room temperature to complete the pressure sintering.

[0055] After sintering, the silver-copper paste was tested for thrust strength. The silver-copper paste of Example 3 achieved a thrust strength of 35 MPa during pressureless sintering at 250°C and 41 MPa during pressure sintering. Under rapid pressure sintering at 300°C, the thrust strength also reached 40 MPa.

[0056] Example 4:

[0057] This embodiment utilizes a low-melting-point tin-bismuth alloy powder with a melting point of 138°C and a median particle size of 7 microns. This low-temperature alloy powder can melt the silver-copper paste during sintering. Adding less than 3% of the alloy powder to the silver-copper paste can enhance the sintering of the silver-copper paste and reduce the porosity in the sealing paste.

[0058] The preparation method of the silver-copper paste provided in the embodiment of the present application is as follows:

[0059] 0.32g of novolac epoxy resin (product model F51) and 0.4g of hexamethylene diisocyanate (HDI) were evenly dispersed in 1.6g of diethylene glycol butyl ether acetate to obtain mixed solution A, i.e., the epoxy resin solution system. 0.03g of imidazole curing agent 2E4MZ was evenly dispersed in mixed solution A to obtain the curing agent solution system. Mixed solution A and the curing agent solution were mixed to obtain the adhesive system.

[0060] 12g of micron silver-coated copper powder, 7.5g of submicron silver powder, and 0.5g of tin-bismuth alloy powder (Sn42Bi58) were added to the above-mentioned bonding system and thoroughly mixed in an autorotating centrifugal mixer for 15s to obtain a primary silver-coated copper slurry product. The silver-coated copper powder has a D50 of 3.8μm, a tap density of 5g / cm3, a weight percentage of silver of 20wt%, a pinhole rate of 4% and a thickness of 80nm; the submicron silver powder has a D50 of 0.3μm and a tap density of 4.2g / cm3. The tin-bismuth alloy powder has a D50 of 7μm.

[0061] The product viscosity, measured using a Brookfield DV-E viscometer, was 140 Pa.s. The resistivity of the silver-copper paste after sintering at 300°C was 3.6 μΩ·cm using a four-probe method. The thermal conductivity of the silver-copper paste after sintering at 300°C was 201 W / mK using a laser method.

[0062] In Example 4, the thrust strength of the silver-copper paste can reach 36 MPa during pressureless sintering, and the thrust strength can reach 43 MPa during pressure sintering.

[0063] Example 5:

[0064] This embodiment uses nano silver powder with a particle median of 70 nanometers. Adding 15% of nano silver powder to the silver copper paste can enhance the sintering of the silver copper paste and improve the main strength.

[0065] The preparation method of the silver-copper paste provided in the embodiment of the present application is as follows:

[0066] 0.32g of novolac epoxy resin (product model F51) and 0.4g of hexamethylene diisocyanate (HDI) were evenly dispersed in 1.6g of diethylene glycol butyl ether acetate to obtain mixed solution A, i.e., the epoxy resin solution system. 0.03g of imidazole curing agent 2E4MZ was evenly dispersed in mixed solution A to obtain the curing agent solution system. Mixed solution A and the curing agent solution were mixed to obtain the adhesive system.

[0067] 12g of micron silver-coated copper powder, 5g of submicron silver powder, and 3g of nanopowder were added to the above-mentioned bonding system and thoroughly mixed in a centrifugal mixer for 15 seconds to obtain a primary silver-coated copper slurry. The silver-coated copper powder had a D50 of 3.8μm, a tap density of 5g / cm3, a silver weight percentage of 20wt%, a silver coating with a pinhole rate of 4% and a thickness of 80nm. The submicron silver powder had a D50 of 0.3μm and a tap density of 4.2g / cm3.

[0068] The product viscosity, measured using a Brookfield DV-E viscometer, was 140 Pa.s. The resistivity of the silver-copper paste after sintering at 300°C was 3.6 μΩ·cm using a four-probe method. The thermal conductivity of the silver-copper paste after sintering at 300°C was 201 W / mK using a laser method.

[0069] Example 4 The thrust strength of the silver-copper paste can reach 39 MPa when pressureless sintering is performed at 300°C, and the thrust strength can reach 51 MPa when pressure sintering is performed at 300°C.

[0070] Comparative Example 1

[0071] The preparation method of the silver-copper paste provided in the embodiment of the present application is as follows:

[0072] 0.7g of novolac epoxy resin (product model F51) and 1.5g of diethylene glycol butyl ether acetate were added to obtain mixed solution A, i.e., the epoxy resin solution system. 0.03g of imidazole curing agent 2E4MZ was evenly dispersed in mixed solution A, i.e., the curing agent solution system. Mixed solution A and the curing agent solution were then mixed to obtain a bonding system.

[0073] 12g of micron silver-coated copper powder and 8g of submicron silver powder were added to the above-mentioned bonding system and thoroughly mixed in a centrifugal mixer for 15 seconds to obtain a primary silver-coated copper slurry. The silver-coated copper powder had a D50 of 3.8μm, a tap density of 5g / cm³, a silver weight percentage of 20wt%, a silver coating with a pinporosity of 4% and a thickness of 80nm. The submicron silver powder had a D50 of 0.3μm and a tap density of 4.2g / cm³.

[0074] The primary silver-copper paste product is dispersed by a three-roller rolling mill to obtain a final product with a fineness of less than 8 μm, namely the silver-copper paste, which is stored at a low temperature of -18°C for future use.

[0075] The product viscosity, measured using a Brookfield DV-E viscometer, was 130 Pa.s. The resistivity of the silver-copper paste after sintering at 300°C was 3.6 μΩ·cm using a four-probe method. The thermal conductivity of the silver-copper paste after sintering at 300°C was 210 W / mK using a laser method.

[0076] The thrust strength test results of the silver copper paste are listed in Table 1

[0077]

[0078] Comparative Example 2

[0079] The preparation method of the silver-copper paste provided in the embodiment of the present application is as follows:

[0080] 0.7g of double-A epoxy resin (product model E51) and 1.5g of diethylene glycol butyl ether acetate were added to form mixed solution A, i.e., the epoxy resin solution system. 0.0108g of dicyandiamide and 0.01% of imidazole curing agent 2E4MZ were evenly dispersed in mixed solution A, i.e., the curing agent solution system. Mixed solution A and the curing agent solution were then mixed to form the bonding system.

[0081] 12g of micron silver-coated copper powder and 8g of submicron silver powder were added to the above-mentioned bonding system and thoroughly mixed in a centrifugal mixer for 15 seconds to obtain a primary silver-coated copper slurry. The silver-coated copper powder had a D50 of 3.8μm, a tap density of 5g / cm³, a silver weight percentage of 20wt%, a silver coating with a pinporosity of 4% and a thickness of 80nm. The submicron silver powder had a D50 of 0.3μm and a tap density of 4.2g / cm³.

[0082] The primary silver-copper paste product is dispersed by a three-roller rolling mill to obtain a final product with a fineness of less than 8 μm, namely the silver-copper paste, which is stored at a low temperature of -18°C for future use.

[0083] The product viscosity, measured using a Brookfield DV-E viscometer, was 120 Pa.s. The resistivity of the silver-copper paste after sintering at 300°C was 6 μΩ·cm using a four-probe method. The thermal conductivity of the silver-copper paste after sintering at 300°C was 190 W / mK using a laser method.

[0084] Example 3 of the present invention utilizes a high temperature resistant adhesive system to improve the oxidation resistance of the silver copper paste at high temperatures. TGA test ( Figure 2 ) shows that the initial oxidation temperature of the silver-copper paste of Example 3 is 520°C, while Comparative Examples 1 and 2 are ordinary epoxy resin adhesive systems, and their initial oxidation temperatures are 360°C and 340°C, respectively. As the temperature increases, the weight increases faster and more. The silver-copper paste of Example 3 exhibits excellent high-temperature antioxidant properties, which is beneficial to extending the service life and long-term reliability of the sealing paste.

[0085] The technical scope of the present invention is not limited to the contents of the above description. Those skilled in the art can make various deformations and modifications to the above embodiments without departing from the technical idea of the present invention, and these deformations and modifications should all fall within the protection scope of the present invention.

Claims

1. A power chip high temperature resistant working sealing silver copper paste, characterized in that: The composition comprises, by weight, 33-90 parts of silver-coated copper powder, 0-60 parts of sinterable conductive filler, 0.8-4.5 parts of high-temperature adhesive, 0.2-0.32 parts of curing agent, 6-9 parts of organic solvent and 0-3.1 parts of auxiliary agent; The weight percentage of silver in the silver-coated copper powder is 10wt%-30wt%, and the sinterable conductive filler is used to enhance the conductivity and sintering performance, wherein the sinterable conductive filler comprises a mixed powder consisting of silver powder, tin alloy powder, and indium alloy powder; The high-temperature adhesive is used to provide a resin system with high-temperature thermal stability and bonding performance. The high-temperature adhesive is a thermosetting curing resin system, including a resin and a curing agent. The organic solvent is used to disperse the powder material and dissolve the adhesive and curing agent, and is composed of ethylene glycol butyl ether and diethylene glycol butyl ether acetate.

2. The high temperature resistant silver-copper sealing paste for power chips according to claim 1, characterized in that: The silver-coated copper powder includes micron silver-coated copper powder, the median particle size of the micron silver-coated copper powder is 1.5 μm-6 μm, and the tap density is greater than 4.5 g / cm 3 .

3. The high temperature resistant silver-copper sealing paste for power chips according to claim 1, characterized in that: The auxiliary agent includes at least one of a thixotropic agent, an antioxidant or a defoaming agent.

4. The high temperature resistant silver-copper sealing paste for power chips according to claim 1, characterized in that: The mass ratio of the high-temperature adhesive to the organic solvent is (1-5):(1-10), and the mass ratio of the curing agent to the organic solvent is 1:(6-100).

5. The high temperature resistant silver-copper sealing paste for power chips according to claim 1, characterized in that: The sinterable conductive filler comprises: The median particle size of the silver powder is 0.1μm-0.9μm or 10nm-90nm, the tin alloy powder is Sn42Bi58 alloy powder or SnCuAg alloy powder with a median particle size of 1μm-10μm, and the indium alloy powder is InSnBi alloy powder with a median particle size of 1μm-10μm.

6. The method for preparing the high-temperature resistant silver-copper paste for sealing power chips according to any one of claims 1 to 5, characterized in that: The following steps are involved: The adhesive and curing agent are respectively mixed with an organic solvent to obtain an adhesive solution and a curing agent solution, and then the adhesive solution and the curing agent solution are mixed to obtain an adhesive system; Mixing the silver-coated copper powder, sinterable conductive filler and additive with the binder system to obtain a primary silver-coated copper slurry; The primary silver-coated copper slurry is ground to obtain the silver-copper paste.

7. The method for preparing the high-temperature resistant silver-copper paste for sealing power chips according to claim 6, characterized in that: The silver-copper paste is printed on the copper electrode surface or the silver-plated layer surface of the semiconductor chip mounting ceramic substrate, and then the chip is placed on the printed silver-coated paste. After drying and sintering, the circuit connection of the chip on the ceramic substrate is completed.

8. The high temperature resistant silver-copper paste for sealing power chips and the preparation method thereof according to claim 7, characterized in that: The sintering method includes pressureless sintering and pressure sintering, and the sintering temperature of the silver-copper paste is 200-300°C.

9. The high temperature resistant silver-copper paste for sealing power chips and the preparation method thereof according to claim 7, characterized in that: The drying temperature is 80° C.-160° C., the sintering temperature is 250° C.-300° C., and the sintering time is 5 minutes-1 hour.

10. The high temperature resistant silver-copper sealing paste for power chips and the preparation method thereof according to claim 6, characterized in that: The grinding is performed using a three-roller grinding machine, and the fineness of the silver-copper paste after grinding is less than 8 μm.

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