Paste composition for pressureless sintering bonding, bonding method using the same, and electronic components manufactured using the same

Abstract

The present invention provides a paste composition for pressureless sintering bonding that does not require pressurization and utilizes only thermal energy, a bonding method, and an electronic component manufactured by bonding. [Solution] A paste composition for pressureless sintering bonding comprising silver nanoparticles; silver nanoparticle aggregates; and a mixed solvent comprising an alcohol-based solvent and an ether-based solvent; a bonding method comprising the step of applying the pressureless sintering bonding paste composition of the present invention to a bonding surface and heating the objects to be bonded to the bonding surface at a pressure of 1 atm and a temperature of 150 to 300°C; and an electronic component manufactured by bonding using the pressureless sintering bonding paste composition of the present invention.

Description

[Technical Field]

[0001] The present invention relates to a paste composition for pressureless sintering bonding, a bonding method using the same, and an electronic component manufactured using the same. More specifically, it relates to a pressureless sintering bonding paste composition that can be applied with high efficiency without requiring pressure conditions, a bonding method using the same, and an electronic component manufactured using the same. [Background technology]

[0002] Semiconductor chips using silicon carbide (SiC), gallium nitride (GaN), and other materials have the characteristic of being able to operate at high temperatures of 300°C or higher. On the other hand, when operating semiconductor chips at high temperatures, conventional solders and lead-free solders are unsuitable due to remelting and reduced high-temperature reliability. Therefore, sintering bonding pastes in which metal nanoparticles with excellent heat resistance and thermal / electrical conductivity are dispersed in a solvent are used.

[0003] Furthermore, as the markets for environmentally friendly electric vehicles and new renewable energy grow, the demand for high-power and high-efficiency power semiconductors is trending upward. Such power semiconductor devices must support higher power density and switching frequencies while ensuring the reliability of high-performance electronic modules. However, conventional lead-free solder (Pb-free solder) and other solders are unsuitable for the high-temperature operating environments of high-performance power semiconductor chips using silicon carbide (SiC), gallium nitride (GaN), etc., due to the way the solder alloy melts and joins the components.

[0004] To address this, when manufacturing power semiconductor modules using WBG (Wide Bandgap) power semiconductors (SiC, GaN, etc.), a pressure sintering bonding material utilizing solid diffusion bonding of nano-sized metal nanoparticles is used as a substitute for solder paste, which has low thermal conductivity and melting point characteristics. However, this generally requires a thermocompression bonding process involving pressure. For example, when performing a thermocompression bonding process involving pressure, as in Japanese Patent No. 4247800, there are problems with reduced production efficiency and yield. In particular, problems such as chip damage due to pressure can occur in semiconductor devices, leading to an increased defect rate.

[0005] Therefore, there is a demand for high-speed sintering bonding materials that offer high reliability in high-temperature operating environments for WBG (Wide Bandgap) power semiconductors used in electric vehicles, AI data centers, etc., and that can improve productivity and reduce the defect rate due to chip damage by simplifying the conventional pressure sintering process. [Overview of the project] [Problems that the invention aims to solve]

[0006] One aspect of the present invention is to provide a paste composition for pressureless sintering bonding that does not require pressurization and utilizes only thermal energy.

[0007] Another aspect of the present invention is to provide a bonding method under no-pressure conditions using the sintering bonding paste composition of the present invention.

[0008] Another aspect of the present invention is to provide electronic components manufactured using the sintering bonding paste composition of the present invention. [Means for solving the problem]

[0009] According to one aspect of the present invention, a paste composition for pressureless sintering bonding is provided, comprising silver nanoparticles; silver nanoparticle aggregates; and a mixed solvent including an alcohol-based solvent and an ether-based solvent.

[0010] According to another aspect of the present invention, a joining method is provided, which includes the steps of applying the pressureless sintering joining paste composition of the present invention to a joining surface and heating the objects to be joined at a temperature of 150 to 300°C under a pressure of 1 atm (atmospheric pressure) while joining them to the joining surface.

[0011] According to yet another aspect of the present invention, an electronic component is provided which is manufactured by joining using the pressureless sintering bonding paste composition of the present invention. [Effects of the Invention]

[0012] According to the present invention, a sintering bonding paste composition that can be sintered at high speed under no-pressure conditions is provided, and the process can be simplified by a no-pressure sintering process. Furthermore, the sintering bonding paste composition of the present invention has excellent continuous printability, excellent printing efficiency and viscosity non-recovery rate, prevents shrinkage and cracking during sintering bonding, and has excellent physical properties such as shear strength, and is expected to be widely applicable to fields such as semiconductors for power semiconductors where high reliability is required. [Brief explanation of the drawing]

[0013] [Figure 1] This diagram illustrates an example of applying the pressureless sintering bonding paste composition of the present invention to a substrate and a semiconductor bonding surface, illustrating the state immediately after application (left) to the state after sintering (right) over time. [Modes for carrying out the invention]

[0014] Preferred embodiments of the present invention will be described below with reference to the attached drawings. However, embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below.

[0015] According to the present invention, a paste composition that can be joined in a pressureless sintering process is provided.

[0016] More specifically, the paste composition for pressureless sintering bonding of the present invention contains silver nanoparticles; silver nanoparticle aggregates; and a mixed solvent containing an alcohol-based solvent and an ether-based solvent.

[0017] In the present invention, the silver nanoparticles are monodispersed silver nanoparticles, and the particle size can be 10 nm to 300 nm, for example, 20 nm to 280 nm. Considering the dispersion performance based on the surface energy of the nanoparticles, it is preferably 30 nm or more. Considering the shear strength based on the specific surface area of the nanoparticles, it is preferably 200 nm or less. When the particle size of the silver nanoparticles is less than the above range, there are problems in handling and difficulties in ensuring the dispersion performance in the paste. When the dispersion performance cannot be reliably ensured, problems such as a decrease in printability due to a decrease in the degree of dispersion and a decrease in the bonding strength during sintering bonding may occur. When exceeding the above range, the bonding strength is disadvantageous when finally sintering and bonding with the silver nanoparticle aggregates of the present invention, or there are problems such as an increase in the variation of print surface leveling and print thickness during paste printing.

[0018] On the other hand, the form of the above silver nanoparticles is not particularly limited, and may have at least one form among spherical, plate-like, and dendrite-like forms. For example, it can be spherical.

[0019] The silver nanoparticle aggregates of the present invention are aggregates in which a plurality of silver nanoparticles are aggregated. For example, it may be an aggregate in which silver nanoparticles with a particle size of 10 nm to 300 nm of the present invention are aggregated. The particle size of the silver nanoparticle aggregates may be 0.5 μm to 30 μm, for example, may be 1 μm to 20 μm. When the size of the silver nano aggregates is less than 0.5 μm, it shows a surface energy similar to that of single silver nanoparticles, the dispersion performance decreases, and the shear strength becomes low. When the size of the silver nano aggregates exceeds 30 μm, it can be confirmed that the activation energy of the nanoparticles decreases and the shear strength tends to decrease.

[0020] Thus, by using an aggregate in which the silver nanoparticles of the present invention are aggregated as the silver nanoparticle aggregates of the present invention, excellent uniformity can be ensured after final sintering as shown in FIG. 1.

[0021] For example, the above silver nanoparticle aggregate may be obtained by reacting silver nanoparticles with a nitrate salt at 50-100°C for 1-3 hours. In this case, the nitrate salt may be ammonium nitrate, barium nitrate, iron nitrate, zinc nitrate, copper nitrate, sodium nitrate, potassium nitrate, calcium nitrate, magnesium nitrate, etc. The nitrate salt may be a metal nitrate with nitrates in groups 1-2, sodium nitrate, potassium nitrate, magnesium nitrate, calcium nitrate, strontium nitrate, barium nitrate, transition metal nitrates of periods 2, 3, 4, and 5, such as manganese nitrate, aluminum nitrate, iron(II) nitrate, cobalt(II) nitrate, and nickel(II) nitrate. It may also be at least one selected from the group consisting of metal nitrates of the lanthanum group corresponding to atomic numbers 58-71, such as copper(II) nitrate, zinc nitrate, gallium nitrate, palladium(II) nitrate, silver nitrate, cadmium nitrate, indium nitrate, and bismuth nitrate.

[0022] Furthermore, the silver nanoparticle aggregates used in the present invention contain saturated fatty acids and / or unsaturated fatty acids with a carbon chain length of C5-C 26 fatty acids, for example, with a carbon chain length of C5~C 20 fatty acids, C 12-22 Long-chain alkanethiols, for example, carbon chain length C 12-18It is preferably surface-treated with a surface treatment agent containing at least one selected from the group consisting of long-chain alkanethiols and amine derivatives, and the saturated fatty acid having a carbon chain length of C5 to C 26 includes, for example, hexanoic acid, ethylhexanoic acid, dodecanoic acid, hexadecanoic acid, oleic acid, dodecanethiol, stearic acid, lauric acid, ethylamine, tetraethylenepentamine, and oleylamine, and includes caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, and cerotic acid, and the carbon chain length is C5 to C 26 The unsaturated fatty acid containing one or more C=C double bonds of C includes, for example, linoleic acid, oleic acid, arachidic acid, etc., and as an amine derivative substituted with a primary amine group NH2 instead of the carboxylic acid functional group of the above fatty acid, it can be at least one selected from aliphatic primary amine groups consisting of hexylamine, octylamine, decylamine, dodecylamine, hexadecylamine, octadecylamine, oleylamine, etc., and C 12-22 The long-chain alkanethiol of may include alkanethiols such as dodecanethiol.

[0023] The surface-treated silver nanoparticle aggregate of the present invention has a specific surface area of more than 1 m 2 / g and not more than 2 m 2 / g, and can be, for example, 1.2 to 1.99 m 2 / g. On the other hand, the specific surface area of the silver nanoparticles of the present invention can be 1.7 to 1.9 m 2 / g.

[0024] On the other hand, the solvent used in the paste composition of the present invention is a mixed solvent containing an alcohol-based solvent and an ether-based solvent. It is preferable to contain the alcohol-based solvent and the ether-based solvent in a weight ratio of 1:3 to 3:1, for example, 1:1 to 2:1. When exceeding the above range, the printing performance and efficiency tend to decrease.

[0025] Furthermore, the mixed solvent used in the paste composition of the present invention may further contain an acetate-based solvent, in which case the mixed solvent may contain an alcohol-based solvent, an ether-based solvent, and an acetate-based solvent in a weight ratio of 80-98:1-10:1-10, for example, 84-96:2-8:2-8.

[0026] The paste composition for pressureless sintering bonding of the present invention may contain, on a weight basis of the total weight of the paste composition, 0.1 to 10% by weight of silver nanoparticles with a particle size of 10 nm to 300 nm; 60 to 80% by weight of aggregates of silver nanoparticles with a particle size of 0.5 μm to 30 μm; and the remainder being a mixed solvent containing an alcohol-based solvent and an ether-based solvent in a weight ratio of 1:3 to 3:1. For example, the above mixed solvent may be included in an amount of 10 to 40% by weight on a weight basis of the total weight of the paste composition.

[0027] If the silver nanoparticle content is below the above range, there is a problem of reduced sintering bonding performance; if it exceeds the range, the paste becomes sticky (tack) and there is a problem of poor printing performance; if the silver nanoparticle aggregate content is below the above range, there is a problem of delayed sintering, poor printing performance, and sintering shrinkage; if it exceeds the range, there is a problem of reduced sintering bonding performance.

[0028] Other metal powder particles besides silver nanoparticles can be added. For example, the metal particles may be one or more metal particles selected from copper (Cu), silver-coated copper (Ag-Coated Cu), gold (Au), platinum (Pt), nickel (Ni), tin (Sn), aluminum (Al), zinc (Zn), bismuth (Bi), indium (In), phosphorus (P), and silicon (Si), or two or more alloy particles selected from these.

[0029] The alcohol-based solvents that can be used in the present invention include α-terpineol, 1,2-propanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, pine oil alcohol (85%), triethylene glycol, 1-decanol, 1-octanol, propylene glycol, glycerol, trimethylolpropane, ethylene glycol, diethylene glycol, triethylene glycol, cyclohexanol, lauryl alcohol, and oleyl alcohol. It may be at least one selected from Alcohol, Nonyl Alcohol, and Dodecanol. Preferably, it contains terpene alcohols and / or glycol alcohols in an amount of 40-80% by weight of the total alcohol solvent, in addition to one or more acyclic aliphatic saturated alcohols (alkanols).

[0030] For example, as an alcohol solvent, a mixed alcohol solvent containing α-terpineol, 1,2-propanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, and 1-decanol can be used, and these components can be mixed in a weight ratio of 4:2:1:1:1. If triethylene glycol is also used in addition to this, the α-terpineol, triethylene glycol, 1,2-propanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, and 1-decanol components can be mixed in a weight ratio of 2:2:1:1:1:1.

[0031] The ether-based solvents that can be used in the present invention include diethylene glycol butyl ether, diethylene glycol mono-n-hexyl ether, diethylene glycol monomethyl ether, diethylene glycol monophenyl ether, tri(propylene glycol) butyl ether, diethylene glycol dibutyl ether, triethylene glycol monobutyl ether, diethylene glycol monobenzyl ether, diethylene glycol butyl methyl ether, triethylene glycol dimethyl ether, and dipropylene glycol n-propyl ether. The solvent can be at least one selected from diethylene glycol monobutyl ether, ethylene glycol monophenyl ether, isopropyl ether, and tetraethylene glycol dimethyl ether. For example, as the ether solvent, a mixed ether solvent can be used, which is a mixture of diethylene glycol monobutyl ether, diethylene glycol mono-n-hexyl ether, diethylene glycol monophenyl ether, and triethylene glycol monobutyl ether, in which case the above components can be mixed in a weight ratio of 1:1:1:1.

[0032] The acetate-based solvents that can be used in the present invention may be at least one selected from propylene glycol diacetate, dipropylene glycol methyl ether acetate, propylene glycol monomethyl ether acetate, butyl acetate, methyl acetate, ethyl acetate, 4-tert-butylcyclohexyl acetate, 2-butoxyethyl acetate, and ethylene glycol monobutyl ether acetate. For example, as an acetate-based solvent, a mixed acetate-based solvent obtained by mixing propylene glycol diacetate and dipropylene glycol methyl ether acetate can be used, and in this case, the above components can be mixed in a 1:1 weight ratio.

[0033] Furthermore, the pressureless sintering bonding paste composition of the present invention may further contain at least one thickening agent selected from the group consisting of epoxy and curing agent mixtures, organic thixotropes, and inorganic thixotropes.

[0034] In this case, epoxy with an EEW (equivalent weight / g) of 100 to 6000 can be used. For example, at least one of low molecular weight epoxy with an EEW (equivalent weight / g) of 100 to 400, intermediate molecular weight epoxy with an EEW (equivalent weight / g) of 400 to 1000, and high molecular weight epoxy with an EEW (equivalent weight / g) of 1000 to 4000 can be used, and preferably low molecular weight epoxy can be used.

[0035] More specifically, the epoxy resins used may have two or more epoxy groups in a single molecule. One type may be used, or two or more types may be used in combination. Specific examples of such epoxy resins include those obtained by the condensation of epichlorohydrin with polyhydric phenols such as bisphenols or polyhydric alcohols, such as glycidyl ether type epoxy resins including bisphenol A type, bromide bisphenol A type, hydrogenated bisphenol A type, bisphenol F type, bisphenol S type, bisphenol AF type, biphenyl type, naphthalene type, fluorene type, novolac type, phenol novolac type, orthocresol novolac type, tris(hydroxyphenyl)methane type, and tetraphenyloleethane type. Other examples include glycidyl ester type epoxy resins obtained by condensation of epichlorohydrin with carboxylic acids such as phthalic acid derivatives and fatty acids, glycidylamine type epoxy resins obtained by reaction of epichlorohydrin with amines, cyanuric acids, and hydantoins, and epoxy resins modified by various methods, but are not limited to these. In particular, bisphenol type epoxy resins and glycidylamine type epoxy resins are preferably used, and among these, epoxy resins such as bisphenol A type, bisphenol F type, bisphenol AF type, and glycidylamine type epoxy resins are preferably used.

[0036] Examples of curing agents include resol-type phenolic resins, novolac-type phenolic resins, curing catalysts such as acid anhydrides, tertiary amines, and triphenylphosphines, anionic polymerization curing agents such as dicyandiamides, hydrazines, and aromatic diamines, and organic peroxides, but are not limited to these. For example, an anhydride-based and / or aromatic diamine epoxy curing agents can be used. One type of epoxy curing agent may be used, or two or more types may be used in combination. An anhydride-based epoxy curing agent is, for example, at least one selected from 3 or 4-methyl-1,2,3,6-tetrahydrophthalic anhydride, methyl tetrahydrophthalic anhydride, nadic methyl anhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, pyromellitic dianhydride, and hexahydro-4-methylphthalic anhydride. Aromatic diamine epoxy curing agents are, for example, imidazol and aromatic amines. It may be at least one selected from amine, phenylenediamine, benzidine, diaminostilbene, m-xylylene diamine, and p-xylylene diamine.

[0037] The amount of hardener to be added is not limited and can be determined appropriately depending on the type and amount of epoxy resin, but for example, epoxy and hardener can be mixed and used in a weight ratio of 5:5 to 9:1, or for example, 6:5 to 7:3.

[0038] On the other hand, the above organic thixotropic agents can be selected from the group consisting of wax-based thixotropic agents such as carnauba wax, microcrystalline wax, montan wax, and Fischer-Tropsch wax; amine-based thixotropic agents such as stearylamine, oleylamine, and dodecylamine; and cellulose-based thixotropic agents such as HPC (Hydroxypropyl Cellulose), CMC (Carboxymethyl Cellulose), and methylcellulose, and may be at least one selected from, for example, amide wax, polyethylene wax (PE wax), cetylamine, ethylcellulose, and polytetrafluoroethylene wax (PTFE wax).

[0039] On the other hand, the inorganic thixotropic agent can be selected from the group consisting of: silica series such as colloidal silica and precipitated silica; clay-based hexadecylbentonite and montmorillonite; carbonate series such as magnesium carbonate (MgCO3) and strontium carbonate (SrCO3); and silicate series such as palygorskite and talc. For example, it may be at least one selected from fumed silica, bentonite, calcium carbonate (CaCO3), and sepiolite.

[0040] In this case, the thickening agent may be included in an amount of 0.1 wt% to 15 wt% of the total weight of the paste composition, for example, 5 wt% to 10 wt%. If the amount is less than the above range, the thickening effect may be insufficient, and if it exceeds the above range, there may be a problem of reduced sintering bonding performance due to organic matter in the paste. On the other hand, if the content of inorganic thixotropic agents increases, it hinders solid diffusion bonding between metal particles, and unlike organic matter, the decomposition temperature is high, and a phenomenon may occur where the sintering bonding performance decreases as the amount added increases.

[0041] Furthermore, the pressureless sintering bonding paste composition of the present invention may further contain an additive comprising at least one selected from the group consisting of an organic dispersant, a nonionic surfactant, and an aliphatic compound comprising a carboxylic acid and a fatty acid. For example, the aliphatic compound may be at least one selected from the group consisting of palmitic acid, malonic acid, oleic acid, glutaric acid, picolinic acid, sebacic acid, hexanoic acid, ascorbic acid, citric acid, polyacrylic acid, lauric acid, and maleic acid. Amines such as trialkanolamines, for example, alkanols may have 1 to 5 carbon atoms, and acyclic aliphatic unsaturated diols such as halogenated alkenyl diols can be used.

[0042] Furthermore, the above additives may further include nonionic surfactants and organic dispersants.

[0043] The above organic dispersant may be at least one selected from high molecular weight block copolymers, alkylammonium salts of high molecular weight copolymers, acrylate copolymers, unsaturated polyamine amides, low molecular weight acidic polyester salts, acidic copolymers, alkylammonium salts of block copolymers having acidic groups, methoxypropyl acetate, and low molecular weight unsaturated polycarboxylic acids. More specifically, high molecular weight block copolymers can be Pluronic series (EO-PO-EO) such as Pluronic F68, Pluronic L64, Pluronic P85, Tetronic series such as Tetronic 1107, Tetronic 304, Hypermer series such as Hypermer KD1, Hypermer KD3, etc.; high molecular weight copolymer alkylammonium salts can be Polyquaternium series such as Polyquaternium-10, Polyquaternium-7, Cetrimonium Methosulfate, etc.; acrylate copolymers can be Carbomers such as Carbomer 940, Carbopol ETD 2020, Disperbyk series such as Disperbyk 110, Disperbyk 111, Disperbyk 163, etc., Rheovis series such as Rheovis AS1125, Rheovis This could be PU1191, etc.; unsaturated polyamine amides could be Versamid series such as Versamid 125, Versamid 140, etc.; low molecular weight acidic polyester salts could be Solsperse series such as Solsperse 20000, Solsperse 30000, or Efka 7700 (BASF), etc.; acidic copolymers could be polyacrylic acid, Dispex series, etc.; alkylammonium salts of block copolymers having acidic groups could be block copolymers of PEG and PAA, Dispex Ultra series, etc.; low molecular weight unsaturated polycarboxylic acids could be PASA (Polyaspartic Acid), Solsperse 46000, etc.

[0044] On the other hand, nonionic surfactants are classified as alkyl alkoxylate series, C 11 ~C 15 These may include polyoxyethylene-based materials such as alcohol alkoxylates, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenol ethers, and polysorbates; poloxamers (Pluronics) such as Pluronics with an EO-PO-EO block copolymer structure; glycerin derivatives such as glyceryl monostearate (GMS) and glyceryl monolaurate (GML); sorbitol derivatives such as sorbitan esters; and alkyl glucosides such as decyl glucoside and lauryl glucoside.

[0045] The above-mentioned additive may be included in the paste composition at a content of 0.1 wt% to 5 wt%, for example, 0.1 wt% to 4 wt%, based on the total weight of the paste composition. If the content is less than the above range, the effect of the additive may be insufficient, and if it exceeds the above range, the organic matter content in the paste will increase, which may lead to problems with reduced sintering bonding performance.

[0046] According to another aspect of the present invention, a bonding method is provided which includes the steps of applying the above-described pressureless sintering bonding paste composition of the present invention to a bonding surface and heating the objects to be bonded to the bonding surface at a pressure of 1 atm and a temperature of 150 to 300°C.

[0047] When using the pressureless sintering bonding paste of the present invention, pressurization conditions are unnecessary, thus eliminating problems such as reduced production efficiency and lower yield due to the pressurization process. Furthermore, the problem of chip damage caused by pressurization is eliminated.

[0048] According to another aspect of the present invention, an electronic component manufactured by joining using the pressureless sintering bonding paste composition of the present invention is provided, wherein the electronic component may be a semiconductor, such as a power semiconductor.

[0049] More specifically, the semiconductor device described above is formed by bonding a semiconductor element to a substrate that serves as an element support member using the aforementioned paste composition. In other words, the paste composition is used here as a die attach material, and the semiconductor element and the substrate are bonded and fixed together through this die attach material.

[0050] Here, the semiconductor device is not particularly limited as long as it is a known semiconductor device, for example, a transistor or diode. Furthermore, the above semiconductor device can be a light-emitting element such as an LED. Furthermore, the type of light-emitting element is not particularly limited, for example, one in which a nitride semiconductor such as InN, AlN, GaN, InGaN, AlGaN, or InGaAlN is formed as a light-emitting layer on a substrate by MOCVD or the like.

[0051] Furthermore, examples of element support members include support members formed from materials such as copper, copper-plated copper, PPF (pre-plated lead frame), glass epoxy, and ceramics.

[0052] By using the above-mentioned die-attach material, semiconductor elements can be bonded to substrates that have not been metal-plated.

[0053] For example, the step of applying the above composition onto a power semiconductor substrate is not limited to rollers, brushes, spray coating, etc., and can be done using stencils or screen printing, etc.

[0054] By sintering, the above-mentioned silver particles and silver particle aggregates can be melted and bonded together.

[0055] In the present invention, "melting" is understood to include not only the complete dissolution of the entire particle, but also partial melting and surface premelting, where fluidity is generated on the particle surface. The sintering may be carried out at the temperature at which the silver particles are sintered. For example, the sintering may be carried out at a temperature of 150 to 300°C, or more specifically, by heating to 200 to 250°C.

[0056] In particular, the composition of the present invention can be sufficiently melted and bonded during sintering even without pressure or at pressures of 15 MPa or less, or 10 MPa or less.

[0057] The present invention will be described in more detail below with reference to specific examples. The following examples are merely illustrative to aid in understanding the present invention, and the scope of the present invention is not limited thereto.

[0058] Examples 1. Manufacturing of paste composition for pressureless sintering bonding (1) Production of silver nanoparticles A silver nitrate solution is prepared by stirring a mixture containing silver nitrate (AgNO3) at a concentration of 30 wt% in ethylene glycol (EG). A polyvinylpyrrolidone solution is prepared by stirring a mixture containing polyvinylpyrrolidone (PVP, MW=40,000) at a concentration of 20 wt% in ethylene glycol. The polyvinylpyrrolidone solution is heated to 120°C in a reactor equipped with a reflux condenser and stirred, then the temperature is maintained. The silver nitrate (AgNO3) solution is injected into the prepared polyvinylpyrrolidone solution at a rate of 10 ml / min for 30 minutes using a syringe pump, and then maintained for 18 hours. After that, the resulting mixture is cooled to room temperature, and the silver particles are separated from the solution by centrifugation. The separated silver nanoparticles are redispersed with ethanol, and then an excess of acetone is added to form a precipitate. After this, centrifugation is performed again, and the supernatant is removed. After repeating this process three times, the silver nanoparticles are redispersed in distilled water (DW) to produce an aqueous solution of silver nanoparticles.

[0059] The resulting silver single particles were designated as Production Example 1, and their size was confirmed while varying the PVP concentration as shown in Table 1. TIFF2026103873000002.tif68170

[0060] As shown in Table 1 above, it was confirmed that the Ag nanoparticle size decreased as the PVP concentration increased. The particle size at this time was expressed by measuring the average particle size using SEM imaging.

[0061] For the production of the pressureless sintering bonding paste composition of the present invention, silver single particles with an average size of 30 to 100 nm are used.

[0062] (2) Production of silver particle aggregates 1) Production of silver particle aggregates To remove PVP from the surface of the silver nanoparticles dispersed in distilled water (DW) as obtained in Production Example 2 above (1), a 50 wt% citric acid aqueous solution was gradually added to the silver nanoparticle aqueous solution while continuously stirring. The stirring speed was set to 300 rpm. After adding the citric acid aqueous solution until the color of the silver nanoparticle aqueous solution changed to dark gray, the resulting solution was centrifuged to recover the silver nanoparticles from which the PVP had been removed. The silver nanoparticles were then washed three times with distilled water, and the washed silver nanoparticles were redispersed in distilled water. The redispersed silver nanoparticles were heated to 50-100°C and stirred while adding ammonia water to adjust the pH to 10-11. After this, ammonium nitrate (NH4NO3) was added as a flocculant at a rate of 5 parts by weight per 100 silver nanoparticles, and the mixture was heated and stirred for 1 hour. After that, the flocculated nanoparticles were recovered by centrifugation, washed three times with distilled water, and then dried at 60°C.

[0063] Table 2 below shows the specific surface area and average particle size (D50) measurements obtained using a wet particle size analyzer for silver particle aggregates produced under various reaction conditions (the grinding conditions after aggregate production were the same).

[0064] TIFF2026103873000003.tif200170

[0065] As a result, it was confirmed that the cohesive strength of the aggregates increased with increasing temperature during the manufacturing process. However, it was also confirmed that the aggregates were not produced smoothly when ammonium nitrate (NH4NO3), a flocculant, was added at a rate of less than 5 parts by weight per 100 silver nanoparticles.

[0066] 2) Surface treatment In a container containing the silver particle aggregate powder obtained in Production Example 16 of the silver particle aggregates described in (2)1) above, an organic acid, long-chain alkanethiol, or amine derivative equivalent to 20 parts by weight per 100 parts by weight of the silver particle aggregate is added as a surface treatment agent. The mixture is then heated and stirred at 65°C for 1 hour at 300 rpm to allow the organic acid to adsorb onto the silver particle aggregate. During this time, the pH of the solution is maintained at 8-9, and heating and stirring are maintained for 10 minutes to 240 minutes. After the reaction is complete, the solution is cooled to room temperature, the supernatant is removed, and the mixture is washed five times with distilled water. Finally, it is filtered using a centrifuge and dried at 60°C for 15 hours. The specific types of surface treatment agents used in each of the production examples obtained in this way are shown in Table 3 below.

[0067] On the other hand, the results of surface treatment performed using the same process as performed on the aggregates, except that silver nanoparticles dispersed in distilled water (DW) obtained in (1) above were used instead of the aggregates, are shown in Table 3 as a comparative manufacturing example.

[0068] TIFF2026103873000004.tif144170

[0069] (3) Manufacturing of paste composition A paste composition was prepared by compounding 9.5 wt% of a mixed solvent (containing alcohol-based solvents, ether-based solvents, and acetate solvents) with 5 wt% silver single particles from Production Example 2 and 72 wt% silver particle aggregates from Production Example 30 as solvents, along with 6 wt% epoxy, 4 wt% curing agent, and 3.5 wt% additives.

[0070] In this study, the alcohol solvent used was a mixed alcohol solvent prepared by mixing α-terpineol, triethylene glycol, 1,2-propanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, and 1-decanol in a weight ratio of 4:2:1:1:1. The ether solvent used was a mixed ether solvent prepared by mixing diethylene glycol monobutyl ether, diethylene glycol mono-n-hexyl ether, diethylene glycol monophenyl ether, and triethylene glycol monobutyl ether in a weight ratio of 1:1:1:1. The acetate solvent used was a solvent prepared by mixing propylene glycol diacetate and dipropylene glycol methyl ether acetate in a weight ratio of 1:1.

[0071] Furthermore, in the case of a thickening agent, a mixture of bisphenol F epoxy with an EEW (equivalent / g) of 170 and MTHPA (3 or 4-Methyl-1,2,3,6-Tetrahydrophthalic Anhydride) was used in a weight ratio of epoxy to hardener of 8:2. As additives, BYK 111 was used as an organic dispersant, alcohol alkoxylate as a nonionic surfactant, and at least one of palmitic acid, malonic acid, maleic acid, oleic acid, dodecanethiol, and trans-2,3-dibromo-2-butene-1,4-diol was used as an activator.

[0072] The paste composition thus produced corresponds to the paste composition of Example 5 below.

[0073] On the other hand, in Table 4 below, Comparative Examples 3 to 6 contain only 75 wt% of the silver nanoparticles from Comparative Manufacturing Examples 4 to 7, and do not contain silver particle aggregates. They were prepared by blending 11.5 wt% solvent, 6 wt% epoxy, 4 wt% curing agent, and 3.5 wt% additive.

[0074] During this process, dispersion proceeded including a primary dispersion using a planetary mixer for 5-30 minutes at a dispersion speed of 100-1000 rpm, a secondary dispersion using a 3-roll mill for 10-40 minutes at a dispersion speed of 50-400 rpm and a roller gap of 3-50 μm, and a tertiary dispersion using a paste mixer for 1-5 minutes at a dispersion speed of 700-1000 rpm.

[0075] The dispersion of the manufactured paste composition was measured using a Fineness of Grind Gauge (FOG) and the surface gloss was visually confirmed. Dispersion was expressed as a numerical value confirmed by the FOG measurement results, and gloss was evaluated as follows: Bad (deteriorated) if the surface was dry and many air bubbles were formed, Normal (average) if there were few air bubbles but the surface was still dry, Good (good) if the surface was moist and there were no air bubbles, and Excellent (excellent) if the surface was moist and glossy enough to reflect light.

[0076] Table 4 below shows the degree of paste dispersion and surface gloss for each type of surface treatment agent as shown in Table 3 above.

[0077] TIFF2026103873000005.tif180170

[0078] As can be seen from Table 4, the dispersion in the paste composition is affected by the surface treatment of the silver particle aggregates, and it was confirmed that the dispersion of the silver particle aggregates in production examples 30-34 was the best.

[0079] Furthermore, the change in the degree of dispersion of the paste due to changes in the content of the surface treatment agent is shown in Table 5 below. More specifically, the degree of dispersion of the paste produced with the composition of Example 5 was measured and shown using particles that were surface-treated by the same process as in Production Examples 30-34, which have excellent dispersion performance, but with a different content of the surface treatment agent.

[0080] TIFF2026103873000006.tif148170

[0081] As can be seen from Table 5, the dispersion degree in the paste composition is affected by the surface treatment of the silver particle aggregates, and it was confirmed that all pastes produced in the examples of the present invention have excellent dispersion.

[0082] 2. Evaluation of the physical properties of paste compositions based on the type of solvent. Screen printing was performed under the following conditions to evaluate the screening printing of the paste compositions produced in Example 5 and the paste compositions produced in Example 5 with only the type of solvent differing as shown in Table 6. *Screen printing conditions Thickness: 30 μm Speed: 30mm / s Plate separation speed: 0.5mm / s S / Q angle: 55 *Conditions for the non-pressurized sintering process Sintering: 250°C, 30 minutes, air-conditioned oven drying.

[0083] In this study, printing efficiency was determined by measuring the volume fraction of the printed shape after screen printing via 3D image analysis, and shear strength was determined using conventional die shear measurement. The results are shown in Table 6 below.

[0084] In the solvents listed in Table 6 below, the acetate, alcohol, and ether solvents used were the same mixed acetate, alcohol, and ether solvents used in the production of the paste composition described in 1.(3) above, respectively. The ketone solvent used was a mixed solvent of cyclohexanol and isophorone in a 1:1 weight ratio.

[0085] TIFF2026103873000007.tif99170

[0086] As can be seen from Table 6 above, alcohol-based solvents are mostly highly polar, resulting in good compatibility with other components, excellent dispersibility, and superior printing properties. Ether-based solvents have high affinity for metals, improving shear strength, but their low viscosity and high affinity for metal substrates lead to low tack and poor rolling properties of the paste composition. Acetate-based solvents have poor compatibility and low viscosity, but they create a reducing atmosphere and offer excellent bonding performance (shear strength). On the other hand, ketone-based solvents have high vapor pressure at room temperature and low boiling point (BP), which can result in poor continuous printing properties of the paste composition and low printing efficiency.

[0087] In particular, when using the surface treatment agent of the present invention, it was confirmed that the dispersibility of the paste is improved, maintaining excellent printability, while the surface activation of the silver particles facilitates solid diffusion bonding between silver particles during paste sintering, thereby improving shear strength. However, when using too much surface treatment agent, it may not all decompose inside the paste during sintering, leaving residual organic matter that hinders solid diffusion bonding between silver particles, potentially lowering shear strength.

[0088] 3. Suitability of paste compositions containing additional components for printing processes. 1) Viscosity ratio recovery rate, printing SPI (thickness deviation), and shear strength due to thickeners Of the paste compositions produced in 1.(3) above, the viscosity ratio recovery rate, printed SPI (thickness deviation), and shear strength of Example 5 and the paste compositions produced in Example 5 with only the type of thickener differing as shown in Table 7 were confirmed. Ethyl cellulose was used as the cellulose-based thickener, cetyl amine as the amine-based thickener, bentonite as the inorganic thixotropic agent, and amide wax as the organic thixotropic agent. In the case of epoxy and curing agents, bisphenol F epoxy with an EEW (equivalent weight / g) of 170 and the curing agent MTHPA were mixed and used in a weight ratio of 8:2.

[0089] TIFF2026103873000008.tif157170

[0090] When the example compositions of the present invention were used, the shear strength was good, all at 10 MPa or higher, and particularly excellent shear strength was observed when epoxy and curing agent were used in amounts above a certain level.

[0091] 2) Shear strength due to additives Of the paste compositions produced in 1.(3) above, the shear strength of Example 5 and the paste composition produced in Example 5 with only the type of additives differing as shown in Table 8 was confirmed.

[0092] The additives were added in the amounts shown in Table 8 below, with alcohol alkoxylate used as the nonionic surfactant and BYK 111 as the organic dispersant.

[0093] TIFF2026103873000009.tif165170

[0094] As can be seen from Table 8 above, in order to improve the shear strength of the sintered bonding material, a dispersant that can improve dispersion performance and an organic acid series activator can be added together, and it was confirmed that two or more types of activators can be used.

[0095] 4. Evaluation of the physical properties of paste compositions based on the content of single particles and aggregates. Of the paste compositions produced in 1.(3) above, the dispersion of the paste compositions produced in Example 5 and Example 5, in which the content of silver nanoparticles and silver nanoparticle aggregates was varied as shown in Table 9, was measured using a Fineness of Grind Gauge (FOG) and is shown below. The shear strength was measured using a standard die shear measurement in the same manner as in 2. and the results are shown in Table 9 below.

[0096] TIFF2026103873000010.tif125170

[0097] As can be seen from Table 9 above, when monodisperse silver nanoparticles are included in amounts exceeding the content range specified in the present invention, the paste dispersion performance tends to decrease, and the shear strength also tends to decrease.

[0098] 5. Evaluation of the physical properties of paste compositions based on the size of silver nanoparticles and silver nanoaggregates. Of the paste compositions produced in 1.(3) above, the dispersion of the paste compositions produced in Example 5 and Example 5, in which the sizes of the silver nanoparticles and silver nanoparticle aggregates were varied as shown in Table 10, was measured using a Fineness of Grind Gauge (FOG) and is shown below. The shear strength was measured using a standard die shear measurement in the same manner as in 2., and the results are shown in Table 10 below.

[0099] TIFF2026103873000011.tif229170TIFF2026103873000012.tif141170

[0100] As can be seen from Table 10 above, when the particle size falls below the range of the present invention, the surface energy of the nanoparticles increases, causing them to aggregate and reducing their dispersion performance, which tends to lower the shear strength. When the size exceeds the range, the specific surface area of ​​the nanoparticles decreases, which tends to lower the shear strength. Furthermore, when the size of the silver nano aggregate is less than 0.5 μm, it exhibits a surface energy similar to that of single silver nanoparticles, resulting in reduced dispersion performance and lower shear strength. When the size of the silver nano aggregate exceeds 30 μm, the activation energy of the nanoparticles decreases, which tends to lower the shear strength.

[0101] 6. Evaluation of the physical properties of paste compositions based on the size of silver single particles Of the paste compositions produced in 1.(3) above, the dispersion of the paste compositions produced in the same manner as in 1.(3) above was measured using a Fineness of Grind Gauge (FOG) and the shear strength was measured using a standard die shear measurement in the same manner as in 2. The results are shown in Table 10 below. At this time, all cases including nano-sized and micro-sized silver particles are referred to as "single particles".

[0102] TIFF2026103873000013.tif92170

[0103] As can be seen in Table 11 above, when the silver nanoparticle aggregates of the present invention are used together with silver nanoparticles, a significantly superior shear strength tends to be observed compared to when micro single particles of a similar size are used instead of the silver nanoparticle aggregates.

[0104] Although embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and it will be obvious to those with ordinary skill in the art that various modifications and variations are possible without departing from the technical idea of ​​the present invention as described in the claims.

Claims

1. Silver nanoparticles; Silver nanoparticle aggregates; and Mixed solvents containing alcohol-based solvents and ether-based solvents; A paste composition for pressureless sintering bonding, including the following:

2. Based on the total weight of the paste composition, 0.1 to 10% by weight of silver nanoparticles with a particle size of 10 nm to 300 nm; 60-80% by weight of silver nanoparticle aggregates measuring 0.5 μm to 30 μm; and A mixed solvent containing an alcohol-based solvent and an ether-based solvent in a weight ratio of 1:3 to 3:1; A paste composition for pressureless sintering bonding according to claim 1, comprising:

3. The paste composition for pressureless sintering bonding according to claim 1, wherein the mixed solvent further comprises an acetate-based solvent.

4. The paste composition for pressureless sintering bonding according to claim 3, wherein the mixed solvent contains an alcohol-based solvent, an ether-based solvent, and an acetate-based solvent in a weight ratio of 80-98:1-10:1-10.

5. The silver nanoparticle aggregate is obtained by reacting silver nanoparticles in a nitrate salt at 50 to 100°C for 1 to 3 hours, as described in claim 1, for a paste composition for pressureless sintering bonding.

6. The aforementioned silver nanoparticle aggregates have a carbon chain length of C ５ ~C ２６ The surface is treated with a surface treatment agent containing at least one component selected from the group consisting of fatty acids, long-chain alkanethiols, and amine derivatives, and the specific surface area is 1 m². ２ / g excess 2m ２ The paste composition for pressureless sintering bonding according to claim 1, wherein the amount is less than or equal to / g.

7. The aforementioned surface treatment agent is C １０ ~C ２２ The pressureless sintering bonding paste composition according to claim 6, comprising at least one component selected from the group consisting of fatty acids, alkanethiols, and aliphatic primary amines.

8. The aforementioned alcohol-based solvents include α-terpineol, 1,2-propanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1-decanol, 1-octanol, propylene glycol, glycerol, trimethylolpropane, ethylene glycol, diethylene glycol, and triethylene glycol. The paste composition for pressureless sintering bonding according to claim 1, comprising at least one selected from Glycol, cyclohexanol, lauryl alcohol, oleyl alcohol, nonyl alcohol, and dodecanol.

9. The aforementioned ether-based solvents include diethylene glycol butyl ether, diethylene glycol mono-n-hexyl ether, diethylene glycol monomethyl ether, diethylene glycol monophenyl ether, tripropylene glycol butyl ether, diethylene glycol dibutyl ether, and triethylene glycol monobutyl ether. The paste composition for pressureless sintering bonding according to claim 1, comprising at least one selected from Glycol Monobutyl Ether, Diethylene Glycol Monobenzyl Ether, Diethylene Glycol Butyl Methyl Ether, Triethylene Glycol Dimethyl Ether, Ethylene Glycol Monophenyl Ether, Isopropyl Ether, and Tetraethylene Glycol Dimethyl Ether.

10. The acetate-based solvents include propylene glycol diacetate, dipropylene glycol methyl ether acetate, propylene glycol monomethyl ether acetate, butyl acetate, methyl acetate, ethyl acetate, 4-tert-butylcyclohexyl acetate, and 2-butoxyethanol acetate. The paste composition for pressureless sintering bonding according to claim 3, comprising at least one selected from monobutyl ether acetate and ethylene glycol monobutyl ether acetate.

11. The paste composition for pressureless sintering bonding according to claim 1, further comprising at least one thickener selected from the group consisting of epoxy and curing agent mixtures, inorganic thixotropes, and organic thixotropes.

12. The paste composition for pressureless sintering bonding according to claim 11, wherein the thickening agent is included in a content of 0.1 wt% to 15 wt% based on the total weight of the paste composition.

13. The paste composition for pressureless sintering bonding according to claim 1, further comprising at least one additive selected from the group consisting of organic dispersants, nonionic surfactants, and aliphatic compounds.

14. The aliphatic compound is at least one selected from the group consisting of palmitic acid, malonic acid, and oleic acid, according to claim 13, a paste composition for pressureless sintering bonding.

15. The paste composition for pressureless sintering bonding according to claim 13, wherein the additive is included in an amount of 0.1 wt% to 5 wt% based on the total weight of the paste composition.

16. The pressureless sintering bonding paste composition according to claim 1, further comprising one or more metal particles selected from copper (Cu), silver-coated copper (Ag-Coated Cu), gold (Au), platinum (Pt), nickel (Ni), tin (Sn), aluminum (Al), zinc (Zn), bismuth (Bi), indium (In), phosphorus (P), and silicon (Si), or two or more alloy particles selected from these.

17. A joining method comprising the steps of applying a pressureless sintering joining paste composition according to any one of claims 1 to 16 to a joining surface, and heating the objects to be joined at a pressure of 1 atm at a temperature of 150 to 300°C while joining them to the joining surface.

18. An electronic component manufactured by joining using the pressureless sintering bonding paste composition described in any one of claims 1 to 16.

19. A semiconductor manufactured by bonding using the pressureless sintering bonding paste composition described in any one of claims 1 to 16.

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