Silver paste, preparation method and application

Abstract

The invention discloses silver paste, a preparation method and application. Relates to the technical field of electronic materials. The silver paste comprises the following components in parts by mass: 60-90 parts of silver particles; 10 to 40 parts of a solvent; 0.2 to 40 parts of an auxiliary agent; and 0.1 to 20 parts of second phase particles; the second-phase particles comprise high-temperature-resistant particles and metal particles; wherein the high-temperature-resistant particles comprise at least one of Al2O3 particles and SiC particles; the metal particles comprise at least one of Cu particles and Ni particles. According to the low-temperature sintered silver paste provided by the invention, the problems of insufficient connection strength, reduced high-temperature reliability and the like when the sintered silver paste is interconnected with heterogeneous interfaces such as gold, silver, copper and the like can be effectively solved by optimizing the components and the proportion thereof, and the formed heterogeneous interface interconnection structure is ensured to have high connection strength and excellent high-temperature resistance.

Description

Technical Field

[0001] This application relates to the field of electronic materials technology, and in particular to a silver paste, its preparation method, and its application. Background Technology

[0002] With the urgent demand for high-performance power electronics technology in fields such as new energy vehicles and aerospace, third-generation semiconductor devices, represented by silicon carbide (SiC) and gallium nitride (GaN), have been widely used due to their wider bandgap, higher breakdown field strength, and excellent thermal conductivity. To match the reliable operation of these devices under high temperatures and high power densities, packaging interconnect materials face even more stringent requirements. Against this backdrop, sintered silver technology has emerged. It utilizes micro / nano silver particles to form bulk sintered silver through solid-state diffusion under heating or pressure, achieving "low-temperature sintering and high-temperature service." With its excellent mechanical and thermoelectric properties, it has replaced traditional solder as the preferred choice for power device interconnects in many applications.

[0003] To optimize the electrothermal connection performance and long-term reliability between the chip and the substrate, the back of power chips (such as SiC chips) are often plated with gold, silver, or copper (forming back-gold / back-silver / back-copper chips). Meanwhile, high-power modules generally use active metal brazing (AMB) ceramic substrates (such as AlN or Si3N4 copper-clad substrates) as the key substrate for carrying the chip.

[0004] However, current sintered silver technology still faces severe challenges in practical applications: First, there is the thermal stress problem caused by the mismatch in the coefficients of thermal expansion between multiple layers such as the chip, sintered silver layer, and AMB substrate. Second, existing sintered silver technology suffers from inherently insufficient interconnect strength in the "heterogeneous interface" formed when connecting different metallization layers (especially gold plating), and its interface connection performance is significantly lower than that of a silver-silver homogeneous interface. Furthermore, under high-temperature service conditions, silver atoms and heterogeneous metal atoms (such as gold atoms) at the interface undergo non-uniform interdiffusion, leading to continuous evolution of the interface microstructure and the formation of defects such as voids, cracks, or brittle intermetallic compounds. Ultimately, this severely compromises the high-temperature stability and long-term operational reliability of the sintered silver-gold heterogeneous interconnect structure. Summary of the Invention

[0005] In view of the above, in order to solve at least one of the above technical problems, this application provides a silver paste, its preparation method and application, and an electronic device.

[0006] In a first aspect, this application provides a silver paste for low-temperature sintering of heterogeneous interface interconnects, comprising 60-90 parts of silver particles, 10-40 parts of solvent, 0.2-10 parts of additives, and 0.1-20 parts of second-phase particles; the second-phase particles include high-temperature resistant particles and metal particles; wherein the high-temperature resistant particles include at least one of Al2O3 and SiC particles; and the metal particles include at least one of Cu and Ni particles.

[0007] Based on the first aspect, in some embodiments of this application, the mass ratio of the organic amine auxiliary agent to the phosphorus-containing compound auxiliary agent is from 0.1:1 to 10:1. This mass ratio is further preferably from 0.5:1 to 2:1.

[0008] Based on the first aspect, in some embodiments of this application, the high-temperature resistant particles and the metal particles are both spherical or plate-shaped.

[0009] Based on the first aspect, in some embodiments of this application, the particle size of the high-temperature resistant particles and the metal particles is from 20 nm to 1000 nm.

[0010] Based on the first aspect, in some embodiments of this application, the high-temperature resistant particles are Al2O3 particles; the second phase metal particles are Cu particles.

[0011] Based on the first aspect, in some embodiments of this application, the additives include organic amine additives and phosphorus-containing compound additives.

[0012] Based on the first aspect, in some embodiments of this application, the weight ratio of the organic amine auxiliaries to the phosphorus-containing compound auxiliaries is 1:5 to 5:1.

[0013] Based on the first aspect, in some embodiments of this application, the organic amine auxiliaries include at least one of ethylenediamine, triethanolamine, dodecylamine, and octadecylamine; and / or, the phosphorus-containing compound auxiliaries include at least one of phosphite, diethyl phosphite, phosphate, dodecyl phosphoric acid, triphenyl phosphite, and triphenylphosphine.

[0014] Based on the first aspect, in some embodiments of this application, the solvent includes a low-boiling-point solvent, a medium-boiling-point solvent, and a high-boiling-point solvent; the boiling point of the low-boiling-point solvent is x, the boiling point of the medium-boiling-point solvent is y, and the boiling point of the high-boiling-point solvent is z; x, y, and z satisfy: x < 150℃, 150℃ ≤ y < 200℃, and 200℃ ≤ z.

[0015] Based on the first aspect, in some embodiments of this application, the low-boiling-point solvent includes at least one of ethanol, isopropanol, and ethyl acetate; and / or, the medium-boiling-point solvent includes at least one of ethylene glycol monobutyl ether, propylene glycol methyl ether, dipropylene glycol methyl ether, and butyl acetate; and / or, the high-boiling-point solvent includes at least one of α-terpineol, diethylene glycol butyl ether, triethylene glycol methyl ether, and benzyl alcohol.

[0016] Based on the first aspect, in some embodiments of this application, the solvent includes a low-boiling-point solvent, a medium-boiling-point solvent, and a high-boiling-point solvent; wherein the weight ratio of the low-boiling-point solvent, the medium-boiling-point solvent, and the high-boiling-point solvent is 1-5:2-6:0.5-2. This weight ratio is further preferably 1:2:1.

[0017] Based on the first aspect, in some embodiments of this application, the low-boiling-point solvent includes isopropanol and ethanol; wherein the weight ratio of isopropanol to ethanol is 1:10 to 10:1.

[0018] Based on the first aspect, in some embodiments of this application, the low-boiling-point solvent includes isopropanol and ethyl acetate; wherein the weight ratio of isopropanol to ethyl acetate is 1:10 to 10:1.

[0019] Based on the first aspect, in some embodiments of this application, the medium-boiling solvent includes ethylene glycol monobutyl ether and propylene glycol methyl ether; wherein the weight ratio of ethylene glycol monobutyl ether and propylene glycol methyl ether is 1:2 to 5:1.

[0020] Based on the first aspect, in some embodiments of this application, the medium-boiling solvent includes ethylene glycol monobutyl ether and dipropylene glycol methyl ether; wherein the weight ratio of ethylene glycol monobutyl ether and dipropylene glycol methyl ether is 1:2 to 5:1.

[0021] Based on the first aspect, in some embodiments of this application, the medium-boiling solvent includes ethylene glycol monobutyl ether and butyl acetate; wherein the weight ratio of ethylene glycol monobutyl ether and butyl acetate is 1:2 to 5:1.

[0022] Based on the first aspect, in some embodiments of this application, the high-boiling-point solvent is α-terpineol and diethylene glycol butyl ether; wherein the weight ratio of the high-boiling-point solvent α-terpineol and diethylene glycol butyl ether is 2:1-2:5.

[0023] Based on the first aspect, in some embodiments of this application, the high-boiling-point solvent is α-terpineol and triethylene glycol methyl ether; wherein the weight ratio of the high-boiling-point solvent α-terpineol and triethylene glycol methyl ether is 2:1-2:5.

[0024] Based on the first aspect, in some embodiments of this application, the high-boiling-point solvent is α-terpineol and benzyl alcohol; wherein the weight ratio of the high-boiling-point solvent to α-terpineol and benzyl alcohol is 2:1-2:5.

[0025] Secondly, this application provides a method for preparing silver paste, the method comprising: adding silver particles, additives and second phase particles to a solvent according to the mass fraction of silver paste according to any one of the first aspects, and mixing them evenly to obtain silver paste.

[0026] Thirdly, this application provides an electronic device manufactured from the aforementioned silver paste.

[0027] Fourthly, this application provides an application of silver paste in the field of electronic materials.

[0028] Compared with related technologies, the silver paste provided in this application introduces a second phase of particles composed of high-temperature resistant particles and metal particles, which can significantly improve the initial bonding strength between the silver paste and heterogeneous metal interfaces such as gold, silver, and copper under low-temperature sintering conditions, while effectively maintaining the performance stability of the interface in high-temperature working environments. This solves the problems of insufficient bonding strength and poor high-temperature reliability in the connection of existing sintered silver pastes in heterogeneous interface bonding. Detailed Implementation

[0029] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0030] Furthermore, if the technical solutions of the various embodiments in this application can be combined with each other, it must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0031] Firstly, this application provides a silver paste for low-temperature sintering of heterogeneous interface interconnects. The silver paste comprises the following components by weight: 60-90 parts silver particles, 10-40 parts solvent, 0.2-10 parts additives, and 0.1-20 parts second-phase particles. The second-phase particles include high-temperature resistant particles and metal particles. The high-temperature resistant particles include at least one of Al2O3 and SiC particles; the metal particles include at least one of Cu and Ni particles. By introducing second-phase particles composed of high-temperature resistant particles and metal particles, this application can improve the initial bonding strength between the silver paste and heterogeneous metal interfaces such as gold, silver, and copper under low-temperature sintering conditions, while also improving the performance stability of the interface in high-temperature working environments. This solves the problems of insufficient bonding strength and poor high-temperature reliability in existing sintered silver pastes for heterogeneous interface connections.

[0032] As an example, the weight parts of silver particles can be 60, 65, 70, 75, 80, 85, or 90, or any value within the range of any two of the above values. As an example, the weight parts of solvent can be 10, 15, 20, 25, 30, 35, or 40, or any value within the range of any two of the above values. As an example, the weight parts of additives can be 0.2, 1, 3, 5, 8, or 10, or any value within the range of any two of the above values. As an example, the weight parts of second-phase particles can be 0.1, 1, 5, 10, 15, or 20, or any value within the range of any two of the above values. As an example, the high-temperature resistant particles can be Al2O3 particles, SiC particles, or a mixture of Al2O3 and SiC particles. As an example, the metal particles can be Cu particles, Ni particles, or a mixture of Cu and Ni particles.

[0033] In some embodiments of this application, the mass ratio of organic amine auxiliaries to phosphorus-containing compound auxiliaries is from 0.1:1 to 10:1. This mass ratio is further preferably from 0.5:1 to 2:1. By selecting different auxiliaries in the aforementioned suitable proportions, this application synergistically enhances the wettability and atomic diffusion capability of silver paste at heterogeneous interfaces, improving both interfacial bonding strength and storage stability. As an example, the mass ratio of organic amine auxiliaries to phosphorus-containing compound auxiliaries can be 0.1:1, 0.5:1, 1:1, 2:1, 5:1, 10:1, or any value within the range of any two of the above values. As an example, this mass ratio is further preferably 0.5:1, 1:1, 1.5:1, 2:1, or any value within the range of any two of the above values.

[0034] Based on the first aspect, in some embodiments of this application, the high-temperature resistant particles and metal particles are both spherical or plate-shaped. This is beneficial for improving the dispersion and packing density of the second-phase particles in the silver matrix, enhancing the pinning effect on silver grain growth and the ability to relieve thermal stress while reducing the porosity of the sintered layer. As an example, the particle shape can be spherical or plate-shaped.

[0035] Based on the first aspect, in some embodiments of this application, the particle size of the high-temperature resistant particles and the metal particles is between 20 nm and 1000 nm. By controlling the particle size of the high-temperature resistant particles and the metal particles within the range of 20 nm to 1000 nm, it is possible to effectively exert an interface strengthening effect while ensuring the uniform dispersion of the second-phase particles in the silver matrix. This improves the bonding strength of the heterogeneous interface while avoiding stress concentration caused by excessively large particle sizes or agglomeration caused by excessively small particle sizes. As an example, the particle size can be 20 nm, 50 nm, 100 nm, 200 nm, 500 nm, 800 nm, 1000 nm, or any value within the range of any two of the above values.

[0036] Based on the first aspect, in some embodiments of this application, the high-temperature resistant particles are Al2O3 particles; the second-phase metal particles are Cu particles. By selecting Al2O3 particles as the high-temperature resistant particles and Cu particles as the second-phase metal particles for compounding, the high-temperature stability characteristics of Al2O3 can be used to suppress silver grain coarsening, and the solid solution strengthening and thermal expansion coefficient matching effect of Cu can be utilized to improve the high-temperature service stability of the heterogeneous interface while also enhancing the interfacial bonding strength.

[0037] Based on the first aspect, in some embodiments of this application, the additives include organic amine additives and phosphorus-containing compound additives. By combining organic amine additives with phosphorus-containing compound additives, the sintering densification of silver particles and atomic interdiffusion at heterogeneous interfaces can be synergistically promoted during sintering, thereby improving the interfacial bonding strength while also improving the long-term storage stability of the slurry.

[0038] Based on the first aspect, in some embodiments of this application, the weight ratio of organic amine auxiliaries to phosphorus-containing compound auxiliaries is 1:5 to 5:1.

[0039] Based on the first aspect, in some embodiments of this application, the organic amine additives include at least one selected from ethylenediamine, triethanolamine, dodecylamine, and octadecylamine; and / or, the phosphorus-containing compound additives include at least one selected from phosphite, diethyl phosphite, phosphate, dodecyl phosphoric acid, triphenyl phosphite, and triphenylphosphine. By selecting suitable additives according to specific interfacial characteristics, the wetting behavior and interfacial reactivity of the silver paste can be controlled, thereby improving the heterogeneous interconnect strength while also improving stability during storage. Using two additives can enhance the stability of the paste. When organic amine additives are used alone, surface solvent desorption occurs during storage, while using two additives together can effectively alleviate this phenomenon and further improve the interconnect strength of the heterogeneous interface.

[0040] Based on the first aspect, in some embodiments of this application, the solvent includes a low-boiling-point solvent, a medium-boiling-point solvent, and a high-boiling-point solvent; the boiling point of the low-boiling-point solvent is x, the boiling point of the medium-boiling-point solvent is y, and the boiling point of the high-boiling-point solvent is z; x, y, and z satisfy: x < 150℃, 150℃ ≤ y < 200℃, and 200℃ ≤ z. By employing a compound solvent with a gradient boiling point design, the solvent can be volatilized in stages, avoiding cracking and porosity caused by rapid drying while ensuring the formation of a uniform and dense dry film.

[0041] Based on the first aspect, in some embodiments of this application, the low-boiling-point solvent includes at least one of ethanol, isopropanol, and ethyl acetate; and / or, the medium-boiling-point solvent includes at least one of ethylene glycol monobutyl ether, propylene glycol methyl ether, dipropylene glycol methyl ether, and butyl acetate; and / or, the high-boiling-point solvent includes at least one of α-terpineol, diethylene glycol butyl ether, triethylene glycol methyl ether, and benzyl alcohol. By specifically selecting and combining the types of solvents, the evaporation rate and solubility can be optimized, thereby ensuring both good printability of the silver paste and uniform drying.

[0042] Based on the first aspect, in some embodiments of this application, the solvent includes a low-boiling-point solvent, a medium-boiling-point solvent, and a high-boiling-point solvent; wherein the weight ratio of the low-boiling-point solvent, the medium-boiling-point solvent, and the high-boiling-point solvent is 1-5:2-6:0.5-2. This weight ratio is further preferably 1:2:1. By optimizing the ratio of low, medium, and high-boiling-point solvents, a balance between evaporation rate and film formation quality can be achieved, avoiding surface crusting caused by excessively rapid evaporation of the low-boiling-point solvent while also reducing the residue of the high-boiling-point solvent. As an example, the weight ratio of the low-boiling-point solvent, the medium-boiling-point solvent, and the high-boiling-point solvent can be 1:2:0.5, 1:2:1, 1:2:1.5, 1:2:2, 3:4:1, 5:6:2, or any value within the range of any two of the above values. As an example, this weight ratio is further preferably 1:2:1.

[0043] Based on the first aspect, in some embodiments of this application, the low-boiling-point solvent includes isopropanol and ethanol; wherein the weight ratio of isopropanol to ethanol is 1:10 to 10:1. By adjusting the ratio of isopropanol to ethanol, the evaporation rate and solubility characteristics of the low-boiling-point solvent can be precisely controlled, thereby adapting to different printing process requirements while ensuring both demolding performance and line shape retention. As an example, the weight ratio of isopropanol to ethanol can be 1:10, 1:5, 1:2, 1:1, 2:1, 5:1, 10:1, or any value within the range of any two of the above values.

[0044] Based on the first aspect, in some embodiments of this application, the low-boiling-point solvent includes isopropanol and ethyl acetate; wherein the weight ratio of isopropanol to ethyl acetate is 1:10 to 10:1. By introducing ethyl acetate to improve the solubility and volatility characteristics of the low-boiling-point solvent, the drying uniformity and surface smoothness of the silver paste can be further improved. As an example, the weight ratio of isopropanol to ethyl acetate can be 1:10, 1:5, 1:2, 1:1, 2:1, 5:1, 10:1, or any value within the range of any two of the above values.

[0045] Based on the first aspect, in some embodiments of this application, the medium-boiling-point solvent includes ethylene glycol monobutyl ether and propylene glycol methyl ether; wherein the weight ratio of ethylene glycol monobutyl ether to propylene glycol methyl ether is 1:2 to 5:1. By adjusting the ratio of the medium-boiling-point solvent, the volatilization behavior of the silver paste in the medium temperature range can be optimized, thereby avoiding excessive residual solvent before sintering while also ensuring drying efficiency. As an example, the weight ratio of ethylene glycol monobutyl ether to propylene glycol methyl ether can be 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, or any value within the range of any two of the above values.

[0046] Based on the first aspect, in some embodiments of this application, the medium-boiling-point solvent includes ethylene glycol monobutyl ether and dipropylene glycol methyl ether; wherein the weight ratio of ethylene glycol monobutyl ether to dipropylene glycol methyl ether is 1:2 to 5:1. Utilizing the high boiling point of dipropylene glycol methyl ether, the evaporation rate in the medium-temperature range can be slowed down, thereby improving the uniformity and line conformation of thick film printing. As an example, the weight ratio of ethylene glycol monobutyl ether to dipropylene glycol methyl ether can be 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, or any value within the range of any two of the above values.

[0047] Based on the first aspect, in some embodiments of this application, the medium-boiling solvent includes ethylene glycol monobutyl ether and butyl acetate; wherein the weight ratio of ethylene glycol monobutyl ether to butyl acetate is 1:2 to 5:1. The moderate evaporation rate and solubility of butyl acetate allow for a balance between the open time and drying efficiency of the silver paste, thus ensuring continuous printing performance. As an example, the weight ratio of ethylene glycol monobutyl ether to butyl acetate can be 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, or any value within the range of any two of the above values.

[0048] Based on the first aspect, in some embodiments of this application, the high-boiling-point solvent is α-terpineol and diethylene glycol butyl ether; wherein the weight ratio of the high-boiling-point solvent α-terpineol and diethylene glycol butyl ether is 2:1 to 2:5. By using α-terpineol and diethylene glycol butyl ether in combination, the evaporation endpoint and residual amount of the high-boiling-point solvent can be adjusted, thereby ensuring low organic residue after sintering while avoiding cracks caused by excessively rapid evaporation.

[0049] As an example, the weight ratio of α-terpineol to diethylene glycol butyl ether can be 2:1, 2:1.5, 2:2, 2:2.5, 2:3, 2:4, 2:5, or any value within the range of any two of the above values.

[0050] Based on the first aspect, in some embodiments of this application, the high-boiling-point solvent is α-terpineol and triethylene glycol methyl ether; wherein the weight ratio of the high-boiling-point solvent α-terpineol and triethylene glycol methyl ether is 2:1 to 2:5. Utilizing the strong polarity of triethylene glycol methyl ether, the dispersion stability of silver particles in the high-boiling-point solvent can be improved, thereby ensuring the anti-settling ability of the slurry. As an example, the weight ratio of α-terpineol and triethylene glycol methyl ether can be 2:1, 2:1.5, 2:2, 2:2.5, 2:3, 2:4, 2:5, or any value within the range of any two of the above values.

[0051] Based on the first aspect, in some embodiments of this application, the high-boiling-point solvent is α-terpineol and benzyl alcohol; wherein the weight ratio of the high-boiling-point solvent α-terpineol and benzyl alcohol is 2:1 to 2:5. Utilizing the low volatility and good solubility of benzyl alcohol, the process window for silver paste can be broadened, thereby achieving both densification and interfacial bonding strength under low-temperature sintering conditions. As an example, the weight ratio of α-terpineol and benzyl alcohol can be 2:1, 2:1.5, 2:2, 2:2.5, 2:3, 2:4, 2:5, or any value within the range of any two of the above values.

[0052] Secondly, this application provides a method for preparing silver paste, the method comprising: adding silver particles, additives, and second-phase particles to a solvent according to the mass fraction of silver paste as described in the first aspect, and mixing them uniformly to obtain silver paste. This preparation method employs a simple physical mixing process, which can achieve uniform dispersion of each component in the solvent, avoiding damage to the morphology of the second-phase particles by high-energy grinding while ensuring batch stability.

[0053] Thirdly, this application provides an electronic device manufactured from the aforementioned silver paste. This electronic device, relying on the heterogeneous interface bonding properties of the silver paste, can achieve both high reliability and long lifespan.

[0054] Fourthly, this application provides an application of silver paste in the field of electronic materials. The silver paste of this application can be extended to various electronic packaging scenarios requiring heterogeneous interface interconnection, expanding the application boundaries of low-temperature sintering technology while also ensuring the durability of heterogeneous interconnection structures.

[0055] Compared with related technologies, the silver paste provided in this application introduces a second phase of particles composed of high-temperature resistant particles and metal particles, which can improve the initial bonding strength between the silver paste and heterogeneous metal interfaces such as gold, silver, and copper under low-temperature sintering conditions, while also improving the performance stability of the interface in high-temperature working environments. This solves the problems of insufficient bonding strength and poor high-temperature reliability in the connection of existing sintered silver pastes in heterogeneous interface bonding.

[0056] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0057] Example 1

[0058] A silver paste, comprising the following components by weight: Silver particles: 65 parts; solvent: 27 parts; additives: 3 parts; second phase particles: 5 parts; wherein, the second phase particles are composed of high-temperature resistant particles and metal particles in a weight ratio of 1:1.

[0059] Among them, the high-temperature resistant particles are Al2O3 particles, and the metal particles are Cu particles; all particles are spherical in shape, and the average particle size is 200nm.

[0060] The additives are triethanolamine and phosphite in a weight ratio of 1:1.

[0061] The solvent consists of ethanol, ethylene glycol monobutyl ether, and α-terpineol in a weight ratio of 1:2:1.

[0062] The method for preparing silver paste includes: adding silver particles, additives and second-phase particles to a solvent according to the above-mentioned mass proportions, mixing them evenly to obtain silver paste.

[0063] The differences between Examples 2 and 3 and Example 1 are shown in Table 1 below. The rest of the parts and parameters are the same as in Example 1.

[0064] Table 1

[0065] Example 4 The difference between this embodiment and Example 1 is that the additives in this embodiment are triethanolamine and phosphite in a weight ratio of 5:1. The remaining parts and parameters are consistent with those in Example 1.

[0066] Comparative Example 1 The difference between this comparative example and Example 1 is that the solvent used in this comparative example is entirely a low-boiling-point solvent, specifically ethyl acetate. All other parts and parameters remain the same as in Example 1.

[0067] Comparative Example 2 The difference between this comparative example and Example 1 is that the solvents in this comparative example are all medium-boiling solvents, and the medium-boiling solvent is ethylene glycol monobutyl ether. The rest of the parameters are the same as those in Example 1.

[0068] Comparative Example 3 The difference between this comparative example and Example 1 is that the solvent used in this comparative example is entirely a high-boiling-point solvent, and the high-boiling-point solvent is α-terpineol.

[0069] Comparative Example 4 The difference between this comparative example and Example 1 is that no additives are added when preparing the low-temperature sintered silver paste, and the remaining components and their proportions are exactly the same as in Example 1.

[0070] Comparative Example 5 The difference between this comparative example and Example 1 is that, in the preparation of low-temperature sintering silver paste, the additives are all triethanolamine, while the remaining components and their proportions are exactly the same as in Example 1.

[0071] Comparative Example 6 The difference between this comparative example and Example 1 is that, in the preparation of low-temperature sintered silver paste, all the additives are phosphites, while the remaining components and their proportions are exactly the same as in Example 1.

[0072] Comparative Example 7 The difference between this comparative example and Example 1 is that, in the preparation of low-temperature sintered silver paste, an equal amount of Al2O3 was used to replace Cu, while the remaining components and their proportions were exactly the same as in Example 1.

[0073] The low-temperature sintered silver paste samples prepared according to Examples 1 to 4 and Comparative Examples 1 to 7 were subjected to structural stability tests and high-temperature aging reliability tests, as detailed below: Sample preparation: Silver paste was printed onto the solderable area of ​​the bare copper AMB substrate using a stencil. The substrate with the printed silver paste was then placed in a blower and dried at 140°C for 20 minutes. The gold-plated SiC chip on the back was then mounted onto the silver paste area. Finally, the sample was sintered at 250°C and 15MPa for 5 minutes using a hot press to form a sandwich structure of AMB substrate / silver paste layer / gold-plated SiC chip.

[0074] Structural stability testing: The prepared samples underwent a temperature shock test (TST) of 1000 cycles from -48℃ to 158℃, with each temperature zone held for 3 minutes and a temperature change time of 1 minute. After the cycles, the shear force was tested using a push-pull testing machine to assess the strength degradation rate (required to be less than 10%, i.e., the strength reduction divided by the initial strength is less than 10%). The shear strength evaluation method is GJB 7400-2011. Furthermore, the delamination rate of the silver sintered layer was detected using a scanning ultrasonic microscope (C-SAM) (required to be less than 15%, i.e., the delaminated area divided by the welded area). (100% less than 15%) to verify structural stability; the superscan evaluation method is GJB 548B-2005.

[0075] High-temperature aging reliability test: Another sample was aged at 200℃ for 1000 hours, and the strength degradation rate and delamination rate were tested in the same way to evaluate its high-temperature resistance.

[0076] The experimental test results of Examples 1 to 4 and Comparative Examples 1 to 7 are shown in Table 2 below.

[0077] Table 2

[0078] Results Analysis: Table 2 shows that the experimental results indicate that this application improves the structural stability and high-temperature resistance of silver paste in heterogeneous interface interconnection by introducing a second-phase particle composed of high-temperature resistant particles and metal particles. Example 1 exhibits relatively balanced overall performance due to its balanced composition. Examples 2 and 3 also achieved performance improvement through the addition of second-phase particles, but the effect was slightly less than that of Example 1. Example 4 uses an additive system composed of organic amines and phosphorus-containing compounds. Although its performance is slightly lower than that of Example 1, it still shows an advantage over the comparative example using only a single additive, indicating a possible synergistic effect between the two types of additives. The comparative examples, using single-boiling-point solvents, showed no significant performance improvement and were lower than the gradient solvent system used in Example 1, suggesting that the gradient evaporation design helps form a more dense and uniform silver paste structure. The comparative example with only high-temperature resistant particles but no metal particles performed worse than other samples, indicating that the metal component in the second-phase particles has a positive effect on improving the bonding strength of the heterogeneous interface.

[0079] In summary, this application, through the combined design of second-phase particles, compounded additives, and gradient solvent system, helps to improve the insufficient strength and high-temperature reliability problems of existing sintered silver paste in heterogeneous interface bonding.

[0080] The above description is merely an exemplary embodiment of this application and does not limit the patent scope of this application. Any equivalent structural transformations made using the content of this application's specification under the technical concept of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A silver paste, characterized in that, According to parts by weight, it includes the following components: The mixture consists of 60-90 parts silver particles, 10-40 parts solvent, 0.2-10 parts additives, and 0.1-20 parts second-phase particles. The second phase particles include high-temperature resistant particles and metal particles; wherein the high-temperature resistant particles include at least one of Al2O3 and SiC particles; The metal particles include at least one of Cu and Ni particles.

2. The silver paste according to claim 1, characterized in that, In the second phase particles, the weight ratio of the high-temperature resistant particles to the metal particles is 0.1:1 to 10:1; and / or, Both the high-temperature resistant particles and the metal particles are spherical or plate-shaped; and / or, The particle size of the high-temperature resistant particles and the metal particles is from 20 nm to 1000 nm.

3. The silver paste according to any one of claims 1 to 2, characterized in that, The high-temperature resistant particles are Al2O3 particles; the second phase metal particles are Cu particles.

4. The silver paste according to claim 1, characterized in that, The additives include organic amine additives and phosphorus-containing compound additives.

5. The silver paste according to claim 4, characterized in that, The organic amine adjuvant includes at least one selected from ethylenediamine, triethanolamine, dodecylamine, and octadecylamine; and / or, The phosphorus-containing compound auxiliaries include at least one of phosphite, diethyl phosphite, phosphate, dodecyl phosphoric acid, triphenyl phosphite, and triphenylphosphine.

6. The silver paste according to claim 1, characterized in that, The solvents include low-boiling-point solvents, medium-boiling-point solvents, and high-boiling-point solvents; The boiling point of the low-boiling-point solvent is x, the boiling point of the medium-boiling-point solvent is y, and the boiling point of the high-boiling-point solvent is z; x, y, and z satisfy: x<150℃, 150℃≤y<200℃, 200℃≤z.

7. The silver paste according to claim 6, characterized in that, The low-boiling-point solvent includes at least one of ethanol, isopropanol, and ethyl acetate; and / or, The medium-boiling-point solvent includes at least one of ethylene glycol monobutyl ether, propylene glycol methyl ether, dipropylene glycol methyl ether, and butyl acetate; and / or, The high-boiling-point solvent includes at least one of α-terpineol, diethylene glycol butyl ether, triethylene glycol methyl ether, and benzyl alcohol.

8. The silver paste according to claim 7, characterized in that, The solvents include low-boiling-point solvents, medium-boiling-point solvents, and high-boiling-point solvents; wherein the weight ratio of the low-boiling-point solvents, medium-boiling-point solvents, and high-boiling-point solvents is 1-5:2-6:0.5-2.

9. A method for preparing silver paste according to any one of claims 1 to 8, characterized in that, The preparation method includes: adding the silver particles, the additives, and the second phase particles to the solvent according to the mass fraction of the silver paste according to any one of claims 1 to 8, and mixing them evenly to obtain the silver paste.

10. The application of the silver paste according to any one of claims 1 to 8 in the field of electronic materials.

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