Metal sintering paste, preparation method and application thereof

Abstract

The application provides a metal sintering solder paste and a preparation method and application thereof, and the metal sintering solder paste comprises metal powder, low-temperature decomposable metal organic compound, organic microspheres and an organic carrier. The metal sintering solder paste is prepared by compounding micron metal particles and nanometer metal particles, so that the metal fillers in the paste form a continuous multi-size distribution state, the original close packing degree of the metal fillers in the paste is improved, the low-temperature decomposable metal organic compound generates new high-activity metal nanoparticles in situ during the sintering process, the original close packing degree of the metal fillers is further improved, the sintering between the metal particles is promoted, a dense sintered body is formed, the introduction of the organic microspheres reduces the Young's modulus of the whole sintered body, the sintered body exhibits good cold and hot impact resistance, the metal sintering solder paste provided by the application is not prone to interface delamination and sintered body cracking under high and low temperature impact, and good service reliability is exhibited.

Description

Technical Field

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

[0002] With the promotion and application of advanced science and technology, electric vehicles, 5G technology, intelligent robots, autonomous driving and other technologies have gradually appeared in people's daily lives, bringing tremendous changes to people's lives and greatly improving people's work efficiency. The great development of these science and technology cannot be separated from the support of chips. Chips have also become the focus of attention in recent years. From small items such as wristbands, headphones and smartphones to large items such as ships, airplanes and aircraft carriers, chips are indispensable. It can be said that chips are an indispensable core component of modern electronic products. Chips, also called microcircuits or microchips, are silicon wafers containing integrated circuits. They are small in size and are the brains of mobile phones, tablets, computers or other electronic products, controlling the operation of electronic products [1-2]. In recent years, in order to reduce carbon emissions, renewable energy technologies such as wind energy, solar energy and biomass energy have received widespread attention from researchers. Semiconductor power devices play a crucial role in power transmission. Usually, these power devices need to withstand high current density, high reverse breakdown voltage and high power dissipation. Due to their high bandgap (corresponding to high breakdown electric field and high power density), high electrical conductivity, and high thermal conductivity, third-generation semiconductors such as silicon carbide (SiC) and gallium nitride (GaN) are widely used in the development of high-power semiconductor devices. Compared to traditional silicon-based power devices, high-power semiconductor devices represented by SiC or GaN can operate at temperatures exceeding 200°C. Therefore, higher requirements are placed on their chip interconnect materials, which need to possess the following properties: good corrosion resistance and ductility, a suitable coefficient of thermal expansion, good thermal fatigue and thermal shock reliability, and high high-temperature operating reliability. In this context, metal sintering technologies (including silver sintering and copper sintering technologies) with the characteristics of "low-temperature sintering and high-temperature service" are widely used in the packaging of wide-bandgap semiconductor devices. However, due to the significant differences in the coefficients of thermal expansion between the chip, the sintered metal layer, and the substrate, the sintered metal layer is subjected to significant thermal stress during chip operation. Long-term stress can lead to delamination and cracking of the sintered metal layer, resulting in serious reliability problems. Summary of the Invention

[0003] Based on this, the present invention addresses the problems existing in the prior art by providing a metal sintering solder paste with good service reliability, its preparation method, and its application. To achieve the above objectives, the technical solution adopted in this application is as follows:

[0004] One objective of this application is to provide a metal sintering solder paste comprising the following substances: 50-95% metal powder, 0.1-25% low-temperature decomposable organometallic compound, 0.1-25% organic microspheres, and 3-35% organic carrier, wherein: the metal powder comprises micron-sized metal particles and nano-sized metal particles; the low-temperature decomposable organometallic compound is an organic complex containing metal ions and its decomposition temperature is ≤300℃; the organic microspheres have a thermal decomposition temperature ≥200℃; and the organic carrier comprises one or a combination of two or more of organic solvents, organic resins, sintering aids, dispersants, rheology modifiers, defoamers, thickeners, or other additives.

[0005] In some embodiments, the metal powder can be a single-component or multi-component metal powder, and its components include, but are not limited to, silver, copper, gold, palladium, platinum, tin, bismuth, indium, nickel or aluminum; preferably, the metal powder is composed of silver and copper.

[0006] In some embodiments, the mass fraction of the metal powder is preferably 80-95%.

[0007] In some embodiments, the metal powder comprises metal nanoparticles with a size of 1-1000 nm and metal microparticles with a size of 1-50 μm.

[0008] In some embodiments, the size of the metal nanoparticles is preferably 300-500 nm; the size of the metal microparticles is preferably 5-20 μm.

[0009] In some embodiments, the metal powder is a combination comprising at least one metal nanoparticle of a specific size and at least one metal microparticle of a specific size.

[0010] In some embodiments, the microstructure of the metal particles includes, but is not limited to, spherical, near-spherical, rod-shaped, linear, sheet-like, hollow, core-shell, flower-like, and other complex structures; preferably, the microstructure of the metal particles is spherical and sheet-like.

[0011] In some embodiments, the surface of the metal particles is coated with surface ligands, including but not limited to organic acids, organic amines, and polymers.

[0012] In some embodiments, the decomposition temperature of the low-temperature decomposable organometallic compound is 100-250°C, and more preferably it is 150-200°C.

[0013] In some embodiments, the low-temperature decomposable organometallic compound is composed of metal ions and organic ligands. The metal ions include, but are not limited to, metal ions such as silver, copper, gold, palladium, platinum, tin, bismuth, indium, nickel, or aluminum. The organic ligands include monodentate or polydentate ligands, including, but not limited to, metal ligand molecules such as organic amines and organic acids.

[0014] In some embodiments, the low-temperature decomposable organometallic compound is preferably an organometallic complex formed by organic acid silver and organic acid copper with organic amine molecules, wherein the organic amine molecules include, but are not limited to, methylamine, ethylamine, ethylenediamine, propylamine, propylenediamine, 2-amino-2-methyl-1-propanol, ethanolamine or diethanolamine.

[0015] In some embodiments, the mass fraction of the low-temperature decomposable organometallic compound is preferably 5-15%.

[0016] In some embodiments, the organic microspheres include, but are not limited to, organosilicon microspheres, rubber microspheres, thermally expandable microspheres, PMMA microspheres, polyamide microspheres, acrylic resin microspheres, polyurethane microspheres, polyvinyl alcohol microspheres, ABS resin microspheres, AES resin microspheres, polystyrene microspheres, polyethylene microspheres, and other organic component microspheres.

[0017] In some embodiments, the organic microspheres are preferably one or a combination of two or more of the following: organosilicon microspheres, PMMA microspheres, polyamide microspheres, and rubber microspheres.

[0018] In some embodiments, the thermal decomposition temperature of the organic microspheres is ≥250°C.

[0019] In some embodiments, the organic microspheres can be of a single size or a multi-size distribution, with a size of 0.01-200 μm; preferably, the organic microspheres are of a single size, with a size of 0.2-20 μm.

[0020] In some embodiments, the microstructure of the organic microspheres includes, but is not limited to, spherical, near-spherical, rod-shaped, linear, sheet-like, hollow, core-shell, or flower-like shapes; preferably, the microstructure of the organic microspheres is spherical.

[0021] In some embodiments, the mass fraction of the organic microspheres is preferably 0.1-10%.

[0022] In some embodiments, the organic carrier preferably has a mass fraction of 3-10%.

[0023] In some embodiments, the organic solvents include, but are not limited to, ethylene glycol, diethylene glycol butyl ether, diethylene glycol hexyl ether, diethylene glycol octyl ether, triethylene glycol monomethyl ether, triethylene glycol dimethyl ether, toluene, polyethylene glycol, and terpineol.

[0024] The organic resin includes, but is not limited to, epoxy resin, phenoxy resin, acrylic resin, silicone resin, and polyimide resin; preferably, the organic resin is one or a combination of two of epoxy resin and acrylic resin.

[0025] The sintering aids include, but are not limited to, organic acids, organic acid anhydrides, or organic amines.

[0026] In some embodiments, the thermal decomposition temperature of the organic resin is ≥200°C.

[0027] The second objective of this application is to provide a method for preparing a metal sintering solder paste, comprising the following steps: uniformly mixing 50-95% metal powder, 0.1-25% low-temperature decomposable organometallic compounds, 0.1-25% organic microspheres and 3-35% organic carrier to obtain the metal sintering solder paste.

[0028] The third objective of this application is to provide an application of the aforementioned metal sintering solder paste in the field of electronic packaging.

[0029] The present application adopts the above technical solution, and its beneficial effects are as follows:

[0030] The metal sintering solder paste and its preparation method provided in this application comprise the following substances: 50-95% metal powder, 0.1-25% low-temperature decomposable organometallic compound, 0.1-25% organic microspheres, and 3-35% organic carrier. The metal powder comprises micron-sized and nano-sized metal particles. The low-temperature decomposable organometallic compound is an organic complex containing metal ions with a decomposition temperature ≤300℃. The organic microspheres have a thermal decomposition temperature ≥200℃. The organic carrier comprises one or a combination of two or more of the following: organic solvent, organic resin, sintering aid, dispersant, rheology modifier, defoamer, thickener, or other additives.

[0031] The metal sintered solder paste provided in this application achieves a continuous multi-size distribution of metal fillers within the paste through the combination of micron-sized and nano-sized metal particles. This improves the initial dense packing of the metal fillers in the paste. Simultaneously, low-temperature decomposable organometallic compounds generate new highly active metal nanoparticles in situ during the sintering process. This further enhances the initial dense packing of the metal solder paste and promotes the sintering between metal particles, forming a dense sintered body. The introduction of organic microspheres reduces the Young's modulus of the entire sintered body, resulting in good resistance to thermal shock. Therefore, the metal sintered solder paste proposed in this invention is less prone to interfacial delamination and sintered body cracking under high and low temperature shocks, exhibiting good service reliability. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the packaging structure provided in embodiments 1-4 of this application.

[0034] Figure 2 This is an Xray-CT image of the sintered sample provided in Example 3 of this application. Detailed Implementation

[0035] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0036] In the description of this application, it should be understood that the terms "upper", "lower", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0037] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0038] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments.

[0039] This application provides a metal sintering solder paste comprising the following substances: 50-95% metal powder, 0.1-25% low-temperature decomposable organometallic compound, 0.1-25% organic microspheres, and 3-35% organic carrier. The metal powder includes micron-sized and nano-sized metal particles; the low-temperature decomposable organometallic compound is an organic complex containing metal ions with a decomposition temperature ≤300℃; the organic microspheres have a thermal decomposition temperature ≥200℃; and the organic carrier comprises one or a combination of two or more of the following: organic solvent, organic resin, sintering aid, dispersant, rheology modifier, defoamer, thickener, or other additives. The specific components of each substance are described in detail below.

[0040] In this embodiment, the metal powder can be a single-component or multi-component metal powder, and its components include, but are not limited to, silver, copper, gold, palladium, platinum, tin, bismuth, indium, nickel or aluminum; preferably, the metal powder is composed of silver or copper.

[0041] In this embodiment, the mass fraction of the metal powder is preferably 80-95%, and a high solid content is beneficial for forming a dense sintered body.

[0042] In this embodiment, the metal powder includes metal nanoparticles with a size of 1-1000 nm and metal microparticles with a size of 1-50 μm, to form a micro-nano composite metal filler system.

[0043] In this embodiment, the size of the metal nanoparticles is preferably 300-500 nm; the size of the metal microparticles is preferably 5-20 μm, which is beneficial for forming a sintered body with good performance.

[0044] In this embodiment, the metal powder is a combination of at least one metal nanoparticle of a specific size and at least one metal microparticle of a specific size to form a metal filler system with a multi-size distribution.

[0045] In this embodiment, the microstructure of the metal particles includes, but is not limited to, spherical, near-spherical, rod-shaped, linear, sheet-like, hollow, core-shell, flower-like, and other complex structures; preferably, the microstructure of the metal particles is spherical and sheet-like, which is beneficial for forming a dense sintered body.

[0046] In this embodiment, the surface of the metal particles is coated with surface ligands, which include, but are not limited to, organic acids, organic amines, or polymers.

[0047] In this embodiment, the decomposition temperature of the low-temperature decomposable organometallic compound is 100-250°C, and more preferably it is 150-200°C, which is beneficial to promoting the low-temperature sintering of metal powder.

[0048] In this embodiment, the low-temperature decomposable organometallic compound is composed of metal ions and organic ligands. The metal ions include, but are not limited to, metal ions such as silver, copper, gold, palladium, platinum, tin, bismuth, indium, nickel, or aluminum. The organic ligands include monodentate or polydentate ligands, including, but not limited to, metal ligand molecules such as organic amines and organic acids.

[0049] In this embodiment, the low-temperature decomposable organometallic compound is preferably an organometallic complex formed by organic acid silver and organic acid copper and organic amine molecules. The organic amine molecules include, but are not limited to, methylamine, ethylamine, ethylenediamine, propylamine, propylenediamine, 2-amino-2-methyl-1-propanol, ethanolamine or diethanolamine.

[0050] In this embodiment, the mass fraction of the low-temperature decomposable organometallic compound is preferably 5-15% to generate sufficient highly active metal nanoparticles in situ to promote the sintering of the metal solder paste.

[0051] In this embodiment, the organic microspheres include, but are not limited to, organosilicon microspheres, rubber microspheres, thermally expandable microspheres, PMMA microspheres, polyamide microspheres, acrylic resin microspheres, polyurethane microspheres, polyvinyl alcohol microspheres, ABS resin microspheres, AES resin microspheres, polystyrene microspheres, polyethylene microspheres, and other organic component microspheres.

[0052] In this embodiment, the organic microspheres are preferably one or a combination of two or more of the following: organosilicon microspheres, PMMA microspheres, polyamide microspheres, or rubber microspheres, to obtain a high-performance sintered body.

[0053] In this embodiment, the thermal decomposition temperature of the organic microspheres is ≥250℃ to obtain good thermal stability.

[0054] In this embodiment, the organic microspheres can be of a single size or a multi-size distribution, with a size of 0.01-200 μm; preferably, the organic microspheres are of a single size, with a size of 0.2-20 μm, so that the sintered body obtains good impact resistance.

[0055] In this embodiment, the microstructure of the organic microspheres includes, but is not limited to, spherical, near-spherical, rod-shaped, linear, sheet-like, hollow, core-shell, or flower-like shapes; preferably, the microstructure of the organic microspheres is spherical.

[0056] In this embodiment, the mass fraction of the organic microspheres is preferably 0.1-10%, which enables the sintered body to obtain good impact resistance.

[0057] In this embodiment, the organic carrier is preferably 3-10% by mass to give the silver paste good rheological properties.

[0058] In this embodiment, organic solvents include, but are not limited to, hydrocarbon solvents, alcohol solvents, alcohol ether solvents, ester solvents, amide solvents, organic acids, and organic amines.

[0059] In this embodiment, preferably, the organic solvent is one or a combination of two or more of the following: ethylene glycol, diethylene glycol, diethylene glycol butyl ether, diethylene glycol hexyl ether, diethylene glycol octyl ether, triethylene glycol monomethyl ether, triethylene glycol dimethyl ether, toluene, polyethylene glycol, and terpineol.

[0060] In this embodiment, the organic resin includes, but is not limited to, epoxy resin, phenoxy resin, acrylic resin, silicone resin, and polyimide resin.

[0061] Preferably, the organic resin is one or a combination of two of epoxy resin and acrylic resin.

[0062] Preferably, the thermal decomposition temperature of the organic resin is ≥200℃.

[0063] The sintering aids include, but are not limited to, organic acids, organic anhydrides, organic amines, and other sintering aids.

[0064] The additive system in the organic carrier includes, but is not limited to, industrial dispersants, rheology modifiers, defoamers, thickeners, etc., commonly used in metal slurries.

[0065] The metal sintered solder paste provided in the above embodiments of this application achieves a continuous multi-size distribution of metal fillers in the paste through the compounding of micron-sized and nano-sized metal particles, thereby improving the original dense packing degree of the metal fillers in the paste. At the same time, low-temperature decomposable organometallic compounds generate new highly active metal nanoparticles in situ during the sintering process, which further improves the original dense packing degree of the metal solder paste and promotes the sintering between metal particles, forming a dense sintered body. The introduction of organic microspheres reduces the Young's modulus of the entire sintered body, resulting in good resistance to thermal shock. Therefore, the metal sintered solder paste proposed in this invention is not prone to problems such as interface delamination and sintered body cracking under high and low temperature shocks, and exhibits good service reliability.

[0066] This application also provides a method for preparing a metal sintering solder paste, comprising the following steps: uniformly mixing 50-95% metal powder, 0.1-25% low-temperature decomposable organometallic compounds, 0.1-25% organic microspheres and 3-35% organic carrier to obtain the metal sintering solder paste.

[0067] The metal sintering solder paste provided in the above embodiments of this application can be applied to the field of electronic device packaging.

[0068] Example 1

[0069] formula:

[0070] Metal powder: Micro-nano silver powder system, with nano silver powder having a particle size of 100nm and micron flake silver powder having a particle size of 5-10μm, and the mass ratio of the two types of silver powder is 2:8.

[0071] Low-temperature decomposable organometallic compounds: 1g of propylenediamine was added to 30ml of ethanol solution, followed by 1g of silver acetate. After the silver acetate dissolved, the solution was filtered to obtain a clear solution of silver-based organometallic compounds.

[0072] Organic microspheres: PMMA microspheres with a particle size of 20 μm.

[0073] Organic carrier: Add 1% octanoic acid, 1% BYK-410 and 1% ethyl cellulose to 10 ml of diethylene glycol, stir and mix evenly to form a compound organic carrier.

[0074] Preparation method:

[0075] Metal powder, silver-based organometallic compound, organic microspheres and organic carrier were mixed in a high-speed mixer for 10 minutes at a mass ratio of 85:7:0.5:7.5 to obtain metal sintered silver paste.

[0076] Performance evaluation methods:

[0077] (1) Shear strength

[0078] Sample preparation: Sandwich-shaped packaging structure, such as Figure 1 As shown, the silver paste prepared in this embodiment is uniformly coated on the gold-plated DBC lower substrate. Then, the gold-plated DBC upper substrate is stacked on the surface coated with silver paste, and a pressure of 0.2N is applied to ensure that the upper and lower DBC substrates are in full contact with the silver paste layer in the middle. The substrates are hot-pressed and sintered at 250°C and 10MPa for 10 minutes to obtain a sandwich-shaped encapsulation structure of DBC / silver sintered layer / DBC after sintering.

[0079] Performance testing: Shear strength was tested using dage-4000, with five sintered samples tested in parallel. The average shear strength was 50.6 MPa.

[0080] (2) Young's modulus

[0081] Sample preparation: The sandwich-shaped encapsulation structure of the sintered DBC / silver sintered layer / DBC was embedded in epoxy resin and cured. The cured body was then polished to obtain the cross-section of the sintered joint and further polished.

[0082] Performance testing: The sintered silver layer of the obtained sintered joint cross section was mechanically tested using a nanoindentation device. 30 parallel tests were conducted, and the average Young's modulus was 18 GPa.

[0083] Example 2

[0084] formula:

[0085] Metal powder: Micro-nano silver powder system, with nano silver powder having a particle size of 150nm, micron spherical silver powder having a particle size of 2-5μm, and micron flake silver powder having a particle size of 5-10μm, and the mass ratio of the three types of silver powder is 3:3:4.

[0086] Low-temperature decomposable organometallic compounds: 1g of ethylamine is added to 30ml of ethanol solution, followed by 1g of silver acetate. After the silver acetate dissolves, the solution is filtered to obtain a clear solution of silver-based organometallic compounds.

[0087] Organic microspheres: PMMA microspheres with a particle size of 30 μm.

[0088] Organic carrier: 10 ml of diethylene glycol, 10% cyclohexane dihydrate glycerol ether and 10% dodecyl succinic anhydride are added and stirred until homogeneous to form a compounded organic carrier.

[0089] Preparation method:

[0090] Metal powder, silver-based organometallic compound, organic microspheres and organic carrier were mixed in a high-speed mixer at a mass ratio of 85:5:1:9 for 10 minutes to obtain metal sintered silver paste.

[0091] Performance evaluation methods:

[0092] (1) Shear strength

[0093] Sample preparation: Sandwich-shaped packaging structure, such as Figure 1 As shown, the silver paste prepared in this embodiment is uniformly coated on the lower gold-plated DBC substrate. Then, the upper gold-plated DBC substrate is stacked on the surface coated with silver paste, and a pressure of 0.2N is applied to ensure that the upper and lower DBC substrates are in full contact with the silver paste layer in the middle. The substrates are sintered at 250°C without pressure for 90 minutes to obtain a sandwich-like encapsulation structure of DBC / silver sintered layer / DBC.

[0094] Performance testing: Shear strength was tested using dage-4000, with five sintered samples tested in parallel. The average shear strength was 33.5 MPa.

[0095] (2) Young's modulus

[0096] Sample preparation: The sandwich-shaped encapsulation structure of the sintered DBC / silver sintered layer / DBC was embedded in epoxy resin and cured. The cured body was then polished to obtain the cross-section of the sintered joint and further polished.

[0097] Performance testing: The sintered silver layer of the obtained sintered joint cross section was mechanically tested using a nanoindentation device. 30 parallel tests were conducted, and the average Young's modulus was 12.3 GPa.

[0098] Example 3

[0099] formula:

[0100] Metal powder: Micro-nano silver powder system, with nano silver powder having a particle size of 100nm, micron spherical silver powder having a particle size of 3-5μm, and micron flake silver powder having a particle size of 10-20μm, and the mass ratio of the three types of silver powder is 4:2:4.

[0101] Low-temperature decomposable organometallic compounds: 1g hexylamine is added to 30ml of ethanol solution, then 1g of silver acetate is added. After the silver acetate dissolves, the solution is filtered to obtain a clear silver-based organometallic compound solution.

[0102] Organic microspheres: Organosilicon microspheres with a particle size of 10 μm.

[0103] Organic carrier: Add 1% ethyl cellulose to 10 ml of diethylene glycol and stir to mix evenly to form a compounded organic carrier.

[0104] Preparation method:

[0105] Metal powder, silver-based organometallic compound, organic microspheres and organic carrier were mixed in a high-speed mixer for 10 minutes at a mass ratio of 85:5:1.5:8.5 to obtain metal sintered silver paste.

[0106] Performance evaluation methods:

[0107] (1) Shear strength

[0108] Sample preparation: Sandwich-shaped packaging structure, such as Figure 1 As shown, the silver paste prepared in this embodiment is uniformly coated onto the lower gold-plated DBC substrate. Then, the upper gold-plated DBC substrate is stacked on the surface coated with silver paste, and a pressure of 0.2N is applied to ensure full contact between the upper and lower DBC substrates and the intermediate silver paste layer. The substrate is then sintered at 250°C without pressure for 60 minutes to obtain a sandwich-like encapsulation structure of DBC / silver sintered layer / DBC, as shown. Figure 2 As shown, it has relatively few internal cavities.

[0109] Performance testing: Shear strength was tested using dage-4000, with five sintered samples tested in parallel. The average shear strength was 63.5 MPa.

[0110] (2) Young's modulus

[0111] Sample preparation: The sandwich-shaped encapsulation structure of the sintered DBC / silver sintered layer / DBC was embedded in epoxy resin and cured. The cured body was then polished to obtain the cross-section of the sintered joint and further polished.

[0112] Performance testing: The sintered silver layer of the obtained sintered joint cross section was mechanically tested using a nanoindentation device. 30 parallel tests were conducted, and the average Young's modulus was 11.3 GPa.

[0113] Example 4

[0114] formula:

[0115] Metal powder: Micro-nano copper powder system, with nano copper powder having a particle size of 500nm, micron spherical copper powder having a particle size of 3-4μm, and micron flake copper powder having a particle size of 5-10μm, and the mass ratio of the three copper powders being 3:4:3.

[0116] Low-temperature decomposable organometallic compounds: 1g of propylenediamine was added to 30ml of ethanol solution, followed by 1g of copper formate. After the copper formate dissolved, the solution was filtered to obtain a clear copper-based organometallic compound solution.

[0117] Organic microspheres: Organosilicon microspheres with a particle size of 15 μm.

[0118] Organic carrier: Add 1% octanoic acid and 1% BYK-410 to 10ml diethylene glycol, stir and mix evenly to form a compound organic carrier.

[0119] Preparation method:

[0120] Metal powder, copper-based organometallic compound, organic microspheres and organic carrier were mixed in a high-speed mixer for 10 minutes at a mass ratio of 85:9:0.5:5.5 to obtain metal sintered copper paste.

[0121] Performance evaluation methods:

[0122] (3) Shear strength

[0123] Sample preparation: Sandwich-shaped packaging structure, such as Figure 1 As shown, the copper paste prepared in this embodiment is uniformly coated on the gold-plated DBC lower substrate. Then, the gold-plated DBC upper substrate is stacked on the surface coated with copper paste, and a pressure of 0.2N is applied to ensure that the upper and lower DBC substrates are in full contact with the copper paste layer in the middle. The substrates are hot-pressed and sintered at 250°C and 10MPa for 10 minutes to obtain a sandwich-shaped encapsulation structure of DBC / copper sintered layer / DBC.

[0124] Performance testing: Shear strength was tested using dage-4000, with five sintered samples tested in parallel. The average shear strength was 55.8 MPa.

[0125] (4) Young's modulus

[0126] Sample preparation: The sandwich-shaped encapsulation structure of the sintered DBC / copper sintered layer / DBC was embedded in epoxy resin and cured. The cured body was then polished to obtain the cross-section of the sintered joint and further polished.

[0127] Performance testing: The sintered copper layer of the obtained sintered joint cross section was mechanically tested using a nanoindentation device. 30 parallel tests were conducted, and the average Young's modulus was 19.6 GPa.

[0128] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0129] The above are merely preferred embodiments of this application, and only specifically describe the technical principles of this application. These descriptions are only for explaining the principles of this application and should not be construed as limiting the scope of protection of this application in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, as well as other specific embodiments of this application that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of this application.

Claims

1. A metal sintering solder paste, characterized in that, The product comprises the following substances in the following mass ratio: 50-95% metal powder, 0.1-25% low-temperature decomposable organometallic compounds, 0.1-25% organic microspheres, and 3-35% organic carrier, wherein: the metal powder includes micron-sized metal particles and nano-sized metal particles; the low-temperature decomposable organometallic compounds are organic complexes containing metal ions with a decomposition temperature ≤300℃; the organic microspheres have a thermal decomposition temperature ≥200℃; and the organic carrier includes one or a combination of two or more of the following: organic solvents, organic resins, sintering aids, dispersants, rheology modifiers, defoamers, and thickeners. The low-temperature decomposable organometallic compound is composed of metal ions and organic ligands; the metal ions include, but are not limited to, silver, gold, palladium, platinum, tin, bismuth, indium, nickel or aluminum metal ions; the organic ligands include monodentate ligands or polydentate ligands, which include, but are not limited to, organic amine and organic acid metal ligand molecules.

2. The metal sintering solder paste as described in claim 1, characterized in that, The metal powder is a single-component or multi-component metal powder, and its components include, but are not limited to, silver, copper, gold, palladium, platinum, tin, bismuth, indium, nickel or aluminum.

3. The metal sintering solder paste as described in claim 1 or 2, characterized in that, The mass fraction of the metal powder is 80-95%.

4. The metal sintering solder paste as described in claim 1, characterized in that, The size of the nanoscale metal particles is 300-500 nm; the size of the micrometer-scale metal particles is 5-20 micrometers.

5. The metal sintering solder paste as described in claim 1, characterized in that, The microstructure of the metal particles includes, but is not limited to, spherical, near-spherical, rod-shaped, linear, sheet-like, hollow, core-shell, and flower-like shapes.

6. The metal sintering solder paste as described in claim 1, characterized in that, The surface of the metal particles is coated with surface ligands, which include, but are not limited to, organic acids, organic amines, and polymers.

7. The metal sintering solder paste as described in claim 1, characterized in that, The decomposition temperature of the low-temperature decomposable organometallic compound is 100-250℃.

8. The metal sintering solder paste as described in claim 1, characterized in that, The low-temperature decomposable organometallic compound is an organometallic complex formed by silver or copper ions with organic acid and organic amine molecules; the organic amine molecules include, but are not limited to, methylamine, ethylamine, ethylenediamine, propylamine, propylenediamine, 2-amino-2-methyl-1-propanol, ethanolamine or diethanolamine; the organic acid molecules include, but are not limited to, formic acid, acetic acid, propionic acid, butyric acid.

9. The metal sintering solder paste as described in claim 1, characterized in that, The organic microspheres include, but are not limited to, organosilicon microspheres, rubber microspheres, thermally expandable microspheres, PMMA microspheres, acrylic resin microspheres, polyurethane microspheres, polyamide microspheres, polyvinyl alcohol microspheres, ABS resin microspheres, AES resin microspheres, polystyrene microspheres, and polyethylene microspheres.

10. The metal sintering solder paste as described in claim 9, characterized in that, The organic microspheres are one or a combination of two or more of the following: organosilicon microspheres, PMMA microspheres, polyamide microspheres, and rubber microspheres.

11. The metal sintering solder paste as described in claim 1, characterized in that, The thermal decomposition temperature of the organic microspheres is ≥250℃.

12. The metal sintering solder paste as described in claim 1, characterized in that, The organic microspheres are of a single or multiple sizes, ranging from 0.01 to 200 μm.

13. The metal sintering solder paste as described in claim 1, characterized in that, The microstructure of the organic microspheres includes, but is not limited to, spherical, near-spherical, rod-shaped, linear, sheet-like, hollow, core-shell, or flower-like shapes.

14. The metal sintering solder paste as described in claim 1, characterized in that, The organic microspheres have a mass fraction of 0.1-10%.

15. The metal sintering solder paste as described in claim 1, characterized in that, The organic carrier has a mass fraction of 3-10%.

16. The metal sintering solder paste as described in claim 1, characterized in that, The organic solvents include, but are not limited to, one or a combination of two or more of the following: ethylene glycol, diethylene glycol, diethylene glycol butyl ether, diethylene glycol hexyl ether, diethylene glycol octyl ether, triethylene glycol monomethyl ether, triethylene glycol dimethyl ether, toluene, polyethylene glycol, and terpineol. The organic resins include, but are not limited to, epoxy resins, phenoxy resins, acrylic resins, silicone resins, and polyimide resins; The sintering aids include, but are not limited to, organic acids, organic acid anhydrides, or organic amines.

17. The metal sintering solder paste as described in claim 1, characterized in that, The thermal decomposition temperature of the organic resin is ≥200℃.

18. A method for preparing the metal sintering solder paste as described in claim 1, characterized in that, The process includes the following steps: mixing 50-95% metal powder, 0.1-25% low-temperature decomposable organometallic compounds, 0.1-25% organic microspheres and 3-35% organic carrier evenly to obtain the metal sintering solder paste.

19. The application of a metal sintering solder paste as described in any one of claims 1-17 in the field of electronic packaging.

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