Pressureless sintering elargol, preparation method thereof and semiconductor device

Abstract

The invention discloses pressureless sintering silver colloid, a preparation method of the silver colloid and a semiconductor device. The pressureless sintering silver colloid comprises the following components in parts by mass: 80-90 parts of silver powder; 0.1 to 15 parts of an epoxy resin composition; 0.1 to 7 parts of a diluent; 0.1-5 parts of a curing agent; 0.01 to 1 part of a curing accelerator; 0.1 to 7 parts of a solvent; 0.1 to 5 parts of a coupling agent; wherein the silver powder comprises large thick sheet powder, submicron ball powder and nano silver powder, and the epoxy resin composition comprises at least one of epoxy resin, high-temperature-resistant resin or toughened resin. The large thick sheet powder, the submicron ball powder and the nano silver powder are compounded to ensure that the pin has low viscosity under the condition of high silver content so as to improve the dispensing workability, the epoxy resin combination is adopted, and the high temperature resistance and the flexibility of the conductive adhesive are balanced through the toughened modified epoxy resin or the high-temperature-resistant resin, so that the high-temperature resistance of the conductive adhesive is improved, and the service life of the conductive adhesive is prolonged. The composite material can resist high temperature, and has low CTE, low modulus and high TST reliability.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor packaging technology, and in particular to a pressureless sintering silver paste, its preparation method, and semiconductor devices. Background Technology

[0002] With the continuous development of semiconductor chip packaging technology, the application scenarios for bonding bare silicon chips (without metal plating) onto metal substrates are becoming increasingly common, and most of these are large-area, uniform bonding. The coefficient of thermal expansion of silicon (CTE≈2.6×10⁻⁶) is... -6 / ℃) and metal substrate (e.g., copper CTE≈16.5×10 -6 The difference in temperature (°C) is significant, and with the large-area bonding, the use of traditional sintered silver paste bonding would result in significant thermal mismatch and thermal stress, ultimately leading to interface failure.

[0003] Currently, the bonding of bare silicon chips at metal interfaces often uses semi-sintered conductive silver paste with a silver powder + resin system. Although this can solve the problems of thermal mismatch and thermal stress, conventional resins have poor heat resistance. The addition of resin will reduce the heat resistance and thermal conductivity of the conductive paste, making it difficult to balance the conductivity and thermal conductivity of the paste with TST reliability, and making it difficult to meet the reliability requirements of short-term high temperature under high temperature conditions. In addition, large-area pressureless sintering will result in interface pores after sintering. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a pressureless sintering silver paste, wherein pressureless sintering means that no pressure or only a very small pressure (<1 MPa) is applied during sintering. The pressureless sintering silver paste comprises the following components by weight: 80-90 parts silver powder; 0.1 to 15 parts of epoxy resin composition; Diluent 0.1 to 7 parts; Hardener 0.1~5 parts; Curing accelerator: 0.01~1 part; Solvent: 0.1~7 parts; Coupling agent: 0.1~5 parts; The silver powder includes: thick sheet powder, submicron spherical powder and nano silver powder, and the epoxy resin composition includes: at least one of epoxy resin, high temperature resistant resin or toughening resin.

[0005] In some embodiments, the above components may specifically be: silver powder in quantities of 80, 81, 87, 88, 89, or 90 parts; epoxy resin composition in quantities of 0.1, 0.5, 1, 2, 8, 9, 10, 11, 12, or 15 parts; diluent in quantities of 0.1, 0.5, 4, 5, 6, or 7 parts; curing agent in quantities of 0.1, 0.5, 1, 2, or 5 parts; curing accelerator in quantities of 0.01, 0.05, 0.4, 0.5, 0.7, 0.8, 0.9, or 1 part; solvent in quantities of 0.1, 0.5, 1, 2, 6, or 7 parts; and coupling agent in quantities of 0.1, 0.5, 1, 1.5, or 5 parts. The above quantities are not specifically limited by weight.

[0006] Furthermore, according to the mass fraction, it includes the following components: 82-86 parts silver powder; 3-7 parts of epoxy resin composition; 1-3 parts diluent; 3-4.5 parts of curing agent; Curing accelerator: 0.1~0.3 parts; Solvent: 3-5 parts; Coupling agent: 2-4 parts.

[0007] In a preferred embodiment, the silver powder can be 82 parts, 83 parts, 84 parts, or 86 parts; the epoxy resin composition can be 3 parts, 4 parts, 5 parts, 6 parts, or 7 parts; the diluent can be 1 part, 1.5 parts, 2 parts, 2.5 parts, or 3 parts; the curing agent can be 3 parts, 3.5 parts, 4 parts, or 4.5 parts; the curing accelerator can be 0.1 parts, 0.15 parts, 0.2 parts, 0.25 parts, or 0.3 parts; the solvent can be 3 parts, 3.5 parts, 4 parts, 4.5 parts, or 5 parts; and the coupling agent can be 2 parts, 2.5 parts, 3 parts, 3.5 parts, or 4 parts. The above-mentioned parts by weight are not specifically limited.

[0008] Specifically, the mass ratio of large thick flakes, submicron spherical powder, and nano silver powder in the silver powder is (40~70):(20~30):(0.5~2.0), specifically 40:20:0.5, 40:30:0.5, 40:30:2, 40:30:0.5, 50:20:0.5, 50:30:0.5, 50:30:2, 50:30:0.5, and 70:20:0.5. The ratios are 70:30:0.5, 70:30:2, and 70:30:0.5, with the preferred ratio being (50~65):(22~25):(0.7~1.5), specifically 50:22:0.7, 50:25:0.7, 50:22:1.5, 50:25:1.5, 65:22:0.7, 65:25:0.7, 65:22:1.5, and 65:25:1.5. More preferably, the ratio is (55~60):(23~24):(0.9~1.2), specifically 55:23:0.9, 55:24:0.9, 50:23:1.2, 50:24:1.2, 60:23:0.9, 60:24:0.9, 60:23:1.2, 60:24:1.2. The above ratios are not specifically limited.

[0009] Furthermore, to achieve the highest possible silver content and ensure the sintering activity of the silver powder, the silver powder is a composite silver powder, including thick flake powder, submicron spherical powder, and nano silver powder, wherein the tap density of the thick flake powder is 4.5~7.0 g / cm³. 3 The particle size D50 is 3~10μm, and in some embodiments, the tap density can be 4g / cm³. 3 5g / cm 3 5.5g / cm 3 6g / cm 3 6.5g / cm 3 7g / cm 3 The particle size D50 can be 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, or 10μm. The above mass fractions are not specifically limited.

[0010] The preferred grades for thick flake silver powder are Japanese Deli TC-465, TC-466, TC-506 and Kunming Norman APS-05. The preferred physical properties of submicron silver powder are a particle size D50 of 200~600nm, and the preferred grades are Suzhou Simite SN200, SN300, Guoyin New Materials SP-1501, Shandong Jianbang 152-3, 152-5N. The preferred physical properties of nano silver powder are 50~100nm, specifically 50nm, 70nm, 80nm, 100nm, and the preferred grades are Kunming Norman Ag-07 and AgNa-100s from Japan Battery Co., Ltd. It should be noted that the D50 particle size is the median particle size, measured using a laser particle size analyzer based on the dynamic light scattering method, and the testing standard is GB / T19077.1.

[0011] Further, the epoxy resin composition includes: epoxy resin, high-temperature resistant resin, and toughening resin, wherein the toughening resin is a polyether-modified epoxy resin and a long-chain hydrocarbon-modified epoxy resin; the mass ratios of epoxy resin, polyether-modified epoxy resin, long-chain hydrocarbon-modified epoxy resin, and high-temperature resistant resin are (0.5~1.5):(1~2):(1~2):(0.5~1.5), specifically: 0.5:1:1:0.5, 0.5:1:1:1.5, 0.5:1: 2:0.5, 0.5:1:2:1.5, 0.5:2:1:0.5, 0.5:2:1:1.5, 0.5:2:2:0.5, 0.5:2:2:1.5, 1.5:1:1:0.5, 1.5:1:1:1.5, 1.5:1:2:0.5, 1.5:1:2:1.5, 1.5:2:1:0.5, 1.5:2:1:1.5, 1.5:2:2:0.5, 1.5:2:2:1.5. The preferred ratio is (0.8~1.2):(1.2~1.8):(1.2~1.8):(0.8~1.2), specifically 0.8:1.2:1.2:0.8, 0.8:1.2:1.2:1.2, 0.8:1.2:1.8:0.8, 0.8:1.2:1.8:0.8, 0.8:1.8:1.2:0.8, 0.8:1.8:1.2:1.2, 0.8:1.8:1.8:0.8, and 0.8:1. The ratios 8:1.8:0.8, 1.2:1.2:1.2:0.8, 1.2:1.2:1.2:1.2, 1.2:1.2:1.8:0.8, 1.2:1.2:1.8:0.8, 1.2:1.8:1.2:0.8, 1.2:1.8:1.2:1.2, 1.2:1.8:1.8:0.8, and 1.2:1.8:1.8:0.8 are not specifically limited, but 1:1.5:1:1.5 is more preferred.

[0012] Among them, epoxy resin is one or more combinations of conventional epoxy resins, mainly playing a role in coordinating and balancing the high-temperature resistant resin and the toughening resin, as well as providing a certain adhesive force. Epoxy resins include: bisphenol A epoxy resin, bisphenol F epoxy resin, hydrogenated bisphenol A epoxy resin and ultra-low chlorine bisphenol F epoxy resin.

[0013] Furthermore, the high-temperature resistant resin, after curing, possesses a high glass transition temperature, providing excellent heat resistance for the conductive adhesive. Simultaneously, its high crosslinking density further promotes the contact between silver powder particles, reducing resistance and improving thermal conductivity. The high-temperature resistant resin is one or a combination of trifunctional epoxy resin, tetrafunctional epoxy resin, o-cresin epoxy resin, bisphenol A type phenolic epoxy resin, phenol-formaldehyde type epoxy resin, trifunctional phenolic epoxy resin, and tetrafunctional phenolic epoxy resin.

[0014] Furthermore, the toughening resin is a modified epoxy resin, including one or more combinations of polyether-modified epoxy resin, long-chain hydrocarbon-modified epoxy resin, dimer acid-modified epoxy resin, and isocyanate-modified epoxy resin. Specifically, the polyether-modified epoxy resin is Huntsman's HP-4000 and DIC's EXA-4850, the long-chain hydrocarbon-modified epoxy resin is DIC's HP-A-4860, the dimer acid-modified epoxy resin is Nanya Di NPER-172, and the isocyanate-modified bisphenol A epoxy resin is Shandong Shengquan's SQE-1402.

[0015] Furthermore, phenolic resin, as a curing agent, has a low CTE, ensuring a high crosslinking density after the conductive adhesive is cured, reducing the CTE of the conductive adhesive, and simultaneously promoting the contact sintering of silver powder. Phenolic resin curing agents include one or more combinations of linear phenolic resin, BPA-type phenolic resin, o-cresol-type phenolic resin, and benzyl-type phenolic resin. Phenolic resin has good temperature resistance and crosslinking density, preferably linear phenolic resin (models PF-8101 and CR132 from Shandong Shengquan) or BPA-type phenolic resin (model SW-280 from Benlong).

[0016] Furthermore, the curing accelerator is one of DMP-30, 2E4MZ, 2E4MZ-CN, and 2P4MHZ-PW.

[0017] Furthermore, the diluent is an active diluent, including one or more of glycidyl oxypropyl phenyl ether, long-chain alkyl monoglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, and polypropylene glycol diglycidyl ether.

[0018] Furthermore, the solvent is a high-boiling-point organic solvent, including one or more combinations of DBE, butyl carbitol acetate, butyl carbitol, dodecyl alcohol ester, hexadecyl alcohol ester, dimethyl phthalate, ethylene glycol phenyl ether, propylene glycol phenyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, and diphenyl ether. Using a high-boiling-point organic solvent ensures that the solvent is uniformly and stably discharged during the drying process of the conductive adhesive, guaranteeing that the conductive adhesive is free of pores during large-area sintering.

[0019] Furthermore, coupling agents can enhance the bonding strength between silver powder and resin, silver powder and silicon interfaces, and silver powder and metal interfaces, thereby improving adhesive strength. Coupling agents include epoxy-based coupling agents, amino-based coupling agents, mercapto-based coupling agents, and phthalate-based coupling agents, with specific models including KH550, KH560, KH570, KH590, KBM4803, KBM404, KR-12, KR-TTS, KR-38S, and BYK4510.

[0020] This invention provides a method for preparing silver paste, comprising: Weigh the epoxy resin composition, diluent, curing agent and solvent according to the above components, heat and stir at 50~90℃ until they are mixed evenly, and after cooling to room temperature, stop heating, add curing accelerator and coupling agent, and continue stirring for 30 minutes to obtain organic carrier; The organic carrier is mixed and stirred with silver powder, and then rolled and degassed to obtain pressureless sintered silver paste.

[0021] The preferred temperature for heating and stirring is 60~70℃. During rolling, a planetary mixer is used for mixing, and a three-roll mill is used for rolling and a vacuum degassing machine is used to remove air bubbles from the conductive adhesive.

[0022] This invention provides a semiconductor device encapsulated using pressureless sintered silver paste or a pressureless sintered silver paste prepared by the aforementioned method. For example, the semiconductor device may include a metal substrate and a chip, with the pressureless sintered silver paste used for the sintered interconnection between the metal substrate and the chip.

[0023] This invention utilizes a silver powder compounding technology, combining thick sheet powder, submicron spherical powder, and nano-silver powder to ensure that the conductive adhesive maintains viscosity that improves dispensing workability even with high silver content. An epoxy resin combination is employed, using toughened modified epoxy resin or high-temperature resistant resin to balance the conductive adhesive's high-temperature resistance and flexibility, enabling it to withstand temperatures up to 260°C while exhibiting low CTE, low modulus, and high TST reliability. Furthermore, its low CTE and high adhesion make it suitable for bonding chips to metal substrates, especially under pressureless conditions. In addition, this silver paste, due to its excellent adhesion, is suitable for bonding large-area bare silicon chips, while also possessing high reliability, high temperature resistance, and good thermal conductivity. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the process of bonding bare silicon chips onto a metal substrate using pressureless sintering silver paste according to Embodiment 1 of the present invention. Figure 2 This is a scanning electron microscope (SEM) image of the sintered surface of the pressureless sintered silver paste in Embodiment 1 of the present invention. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0027] The specifications of the raw materials used in the comparative examples and embodiments are as follows: Thick flake silver powder: TC466, D50=4.0μm, from Japan's Deli Group; Submicron silver powder: SP-1501, D50=0.37μm, Guoyin New Materials; Nano silver powder: Ag-07, D50=0.41μm, Kunming Norman; Bisphenol F epoxy resin is commercially available; Toughening resin: Polyether-modified epoxy resin: EXA-4850, DIC Japan; Long-chain hydrocarbon modified epoxy resin: HP-A-4860, DIC Japan; High-temperature resistant resin: HP-4710, DIC Japan; Hardener: Linear phenolic resin: PF8101, softening point 85℃, Shandong Shengquan; Linear phenolic resin: CR132, softening point 117~125℃, Shandong Shengquan; Curing accelerator: DMP-30 Reactive diluent: commercially available glycidyl phenyl ether; Coupling agent: KH550, Hangzhou Jessica; Solvent: Butyl carbitol acetate, commercially available.

[0028] Example 1 Weigh the epoxy resin (bisphenol F epoxy resin), reactive diluent (epoxypropyl phenyl ether), curing agent (PF8101), and solvent (butyl carbitol acetate) according to the formula in Table 1. Heat and stir at 70°C until homogeneous. After cooling to room temperature, stop heating and add curing accelerator DMP-30 and coupling agent KH550. Continue stirring for 30 minutes to obtain the organic carrier.

[0029] The organic carrier and silver powder (TC466, SP-1501 and Ag-07) are mixed and stirred in a planetary mixer according to the formula ratio, then rolled by a three-roll mill, and finally degassed by a vacuum degassing machine to remove air bubbles from the conductive adhesive to obtain the conductive adhesive product.

[0030] Please refer to Table 1 for the component ratios of Comparative Example 1 and Examples 2-10, and refer to Example 1 for the preparation method.

[0031] Table 1. Component ratios of Comparative Example 1 and Examples 2-10

[0032] The conductive adhesives obtained in the comparative examples and embodiments above were subjected to viscosity tests, resistivity tests, and thermal conductivity tests.

[0033] Viscosity test: Test temperature: 25℃, rotation speed: 5rpm, rheometer, standard: ASTM D1084; instrument model: Anton Paar MCR72 Resistivity testing: Four-point probe method, standard: ASTM F1896; instrument model: RTS-9 dual-electrical-measurement four-probe tester (Guangzhou Four-Probe Technology). Thermal conductivity test: flash test, standard: ASTM-E1461.

[0034] The conductive adhesive obtained in the comparative examples and embodiments above was used to bond a 5*5*0.5mm bare silicon chip onto a metal substrate (bare copper, gold-plated, or silver-plated substrate). Figure 1 Bonding is performed using the bonding method shown, such as... Figure 2 The image shown is a scanning electron microscope (SEM) image of the bonded sample. Under a nitrogen / air atmosphere, the temperature was increased from room temperature to 130°C at a rate of 5°C / min, held at that temperature for 60 min, then increased to 200°C at a rate of 5°C / min, held at that temperature for 120 min, and finally cooled to room temperature. The cooled sample underwent thrust testing and TST reliability testing.

[0035] Thrust test: room temperature & 260℃, 200Kg thrust module, instrument: MFM1200 (TRY PRESCISION) TST Reliability Testing: DUT mode, thermal shock from -30℃ to 140℃, holding time 5s, instrument: TS580 (Chengdu Zhongleng Cryogenic Technology Co., Ltd.) Table 2. Test results of Comparative Example 1 and Examples 2-10

[0036] Depend on Figure 2 It can be seen that the sintered surface is dense and without pores.

[0037] Comparative Example 1 did not contain thick flake silver powder. Example 1 and Comparative Example 1 had the same silver powder content, the difference being that Example 1 contained a higher content of thick flake silver powder. Test results from Comparative Example 1 and Example 1 show that the viscosity and resistivity of Example 1 are lower than Comparative Example 1, while its thermal conductivity is higher. The difference in conventional pushing force and pushing force at 260°C is not significant, indicating that adding thick flake silver powder can reduce viscosity and resistivity while increasing thermal conductivity. The high tap density of the thick flake silver powder can improve the close packing of the silver powder, increase the density of the cured conductive adhesive, and reduce resistivity. Simultaneously, it can reduce the amount of resin and solvent required for silver powder wetting and dispersion, lowering the system viscosity and improving the dispensing workability of the conductive adhesive.

[0038] As shown in Examples 1-4, Example 1, with only epoxy resin, exhibits low viscosity and resistivity, high thermal conductivity, and relatively high conventional thrust, but its thrust at 260°C is too low, resulting in poor reliability. Example 2, with only high-temperature resistant resin, has excessively high viscosity, increasing the thrust at 260°C to 15, but still suffers from poor reliability. Example 3, with only polyether-modified epoxy resin, has low viscosity, increased resistivity to 30, poor thermal conductivity, reduced conventional thrust, and excessively low thrust at 260°C, but good reliability. Example 4, with only long-chain modified epoxy resin, has excessively high viscosity and resistivity, excellent thermal conductivity, and relatively low conventional thrust, also resulting in excessively low thrust at 260°C, but good reliability.

[0039] As shown in Examples 5-7, Example 5, with its combination of epoxy resin and polyether-modified epoxy resin, exhibits low viscosity, low resistivity, high thermal conductivity, and high conventional thrust, but low thrust at 260°C, demonstrating excellent reliability. Example 6, with its combination of epoxy resin and high-temperature resistant resin, shows low viscosity, low resistivity, high thermal conductivity, and high conventional thrust, but low thrust at 260°C, indicating moderate reliability. Example 7, with its combination of epoxy resin and long-chain modified epoxy resin, exhibits excessively high viscosity, low resistivity, high thermal conductivity, and high conventional thrust, but low thrust at 260°C, demonstrating good reliability. This indicates that the combination of epoxy resin and long-chain modified epoxy resin, or epoxy resin and polyether-modified epoxy resin, can ensure low viscosity, low resistivity, high thermal conductivity, high conventional thrust, and high reliability, but with lower thrust at high temperatures.

[0040] As can be seen from Example 9, when epoxy resin, long-chain modified epoxy resin, and polyether modified epoxy resin are combined, compared with Example 8, the performance of Example 9 is improved in all aspects and the overall performance is better.

[0041] A comparison of Examples 10 and 9 shows that both phenolic curing agents can improve thermal conductivity to a certain extent. Specifically, the phenolic curing agent in Example 10 has a higher softening point temperature, which promotes the improvement of thermal conductivity.

[0042] The above description is only a partial embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A pressureless sintered silver paste for packaging semiconductor devices, characterized in that, According to the mass fraction, it includes the following components: 80-90 parts silver powder; 0.1 to 15 parts of epoxy resin composition; Diluent 0.1 to 7 parts; Hardener 0.1~5 parts; Curing accelerator: 0.01~1 part; Solvent: 0.1~7 parts; Coupling agent: 0.1~5 parts; The silver powder includes: thick sheet powder, submicron spherical powder and nano silver powder, and the epoxy resin composition includes: at least one of epoxy resin, high temperature resistant resin or toughening resin.

2. The pressureless sintering silver paste according to claim 1, characterized in that, According to the mass fraction, it includes the following components: The silver powder is 82-86 parts; The epoxy resin composition is 3-7 parts; The diluent is 1-3 parts; The curing agent is 3-4.5 parts; The curing accelerator: 0.1~0.3 parts; The solvent: 3-5 parts; The coupling agent: 2-4 parts.

3. The pressureless sintering silver paste according to claim 1, characterized in that, The mass ratio of the thick flake powder, the submicron spherical powder, and the nano silver powder in the silver powder is (40~70):(20~30):(0.5~2.0), and the tap density of the thick flake powder is 4.5~7.0 g / cm³. 3 The particle size is 3~10μm.

4. The pressureless sintering silver paste according to claim 1, characterized in that, The epoxy resin composition comprises: the epoxy resin, the high-temperature resistant resin, and the toughening resin, wherein the toughening resin is a polyether-modified epoxy resin and a long-chain hydrocarbon-modified epoxy resin; the mass ratio of the epoxy resin, the polyether-modified epoxy resin, the long-chain hydrocarbon-modified epoxy resin, and the high-temperature resistant resin is (0.5~1.5):(1~2):(1~2):(0.5~1.5).

5. The pressureless sintering silver paste according to claim 1, characterized in that, The epoxy resin is one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, hydrogenated bisphenol A epoxy resin, or ultra-low chlorine bisphenol F epoxy resin.

6. The pressureless sintering silver paste according to claim 1, characterized in that, The high-temperature resistant resin is one or more combinations of trifunctional epoxy resin, tetrafunctional epoxy resin, o-cresol epoxy resin, bisphenol A type phenolic epoxy resin, phenol-formaldehyde type epoxy resin, trifunctional phenolic epoxy resin, and tetrafunctional phenolic epoxy resin.

7. The pressureless sintering silver paste according to claim 1, characterized in that, The toughening resin is a modified epoxy resin, including one or more combinations of polyether modified epoxy resin, long-chain hydrocarbon modified epoxy resin, dimer acid modified epoxy resin, and isocyanate modified epoxy resin.

8. The pressureless sintering silver paste according to claim 1, characterized in that, The curing agent is a phenolic resin curing agent, including one or more combinations of linear phenolic resin, BPA-type phenolic resin, o-cresol-type phenolic resin and benzyl-phenolic resin.

9. The pressureless sintering silver paste according to claim 1, characterized in that, The solvent is a high-boiling-point organic solvent, including one or more combinations of DBE, butyl carbitol acetate, butyl carbitol, dodecyl alcohol ester, hexadecyl alcohol ester, dimethyl phthalate, ethylene glycol phenyl ether, propylene glycol phenyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, and diphenyl ether.

10. A method for preparing pressureless sintered silver paste, characterized in that, include: According to any one of claims 1 to 9, the epoxy resin composition, diluent, curing agent and solvent are weighed out according to the mass fraction of the silver paste, heated and stirred at 50 to 90°C until they are mixed evenly. After cooling to room temperature, the heating is stopped, the curing accelerator and coupling agent are added, and the mixture is stirred for 30 minutes to obtain the organic carrier. The organic carrier is mixed and stirred with silver powder, and then rolled and degassed to obtain silver paste.

11. A semiconductor device, characterized in that, Encapsulation using pressureless sintered silver paste as described in claims 1-9 or the preparation method described in claim 10.

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