A composite metal solder paste, its preparation method and application

Abstract

The present invention provides a composite metal solder paste and a preparation method and application thereof. The composite metal solder paste of the present invention comprises the following components in parts by mass: 50-75 parts of inhibitor-coated nano-copper particles, 15-40 parts of interstitial metal particles, and 10-25 parts of an organic solvent system; wherein, the organic solvent system comprises a dispersant, a thixotropic agent and a solvent, and the mass content of the dispersant in the organic solvent system is 0.2-1.5%, and the mass content of the thixotropic agent is 0.05-0.5%. The composite metal solder paste prepared by the present invention has a dense structure, and the microstructure will not change significantly with time during the service life, effectively solving the problems such as seal failure caused by the change of the structure of the current metal solder paste as a sealing material over time; in addition, the sealing structure connected by the composite metal solder paste of the present invention has a high shear strength and good high-temperature shear performance, and can be well applied to various sealing scenarios.

Description

Technical Field

[0001] The present invention relates to the technical field of sealing connection, and in particular to a composite metal solder paste and a preparation method and application thereof. Background Art

[0002] With the rapid development of new energy power and aerospace industries, the reliability requirements for electronic power devices are getting higher and higher. Products with airtight soldering are widely used in aerospace, military and other fields due to their more excellent service reliability. The sealing structure has high requirements for its shear strength, airtightness and high-temperature resistance. Therefore, relevant joining layer materials have also been widely studied.

[0003] At present, gold-tin solder is commonly used for connection by brazing. Gold-tin solder is often used for welding between ceramics, kovar alloy, metal housings, etc., and is widely used in fields including reliable packaging connection, welding of airtight packaging processes for metal or ceramic housings, etc. Gold-tin solder can meet the high requirements of high vacuum, high strength and corrosion resistance, but the brazing temperature of gold-tin solder is above 300°C, which requires a relatively high temperature and has high requirements for the high-temperature resistance of packaged devices; at the same time, gold is expensive, resulting in high sealing costs and other problems.

[0004] A small amount of research has used nano-silver or nano-copper solder paste as sealing materials. The sealing structures formed by these sealing materials have high strength, and the connection temperature is below 270°C, which to a certain extent guarantees the service performance. However, as a device sealing material, a higher density of the sintered tissue structure is required. The currently studied sintered silver and sintered copper have a porous and loose structure, and their numerous pores affect the sealing effect and may cause the failure of the structure during use.

[0005] In view of this, the present invention is specifically proposed. Summary of the Invention

[0006] The purpose of the present invention is to provide a composite metal solder paste and a preparation method and application thereof. The composite metal solder paste has a dense structure, and its microstructure will not change significantly over time during the service life. The sealing structure connected by the composite metal solder paste has a relatively high shear strength and good high-temperature shear performance.

[0007] The present invention provides a composite metal solder paste, which comprises the following components in parts by mass: 50 - 75 parts of nano-copper particles coated with a corrosion inhibitor, 15 - 40 parts of interstitial metal particles, and 10 - 25 parts of an organic solvent system; wherein, the organic solvent system includes a dispersant, a thixotropic agent and a solvent, and the mass content of the dispersant in the organic solvent system is 0.2 - 1.5%, and the mass content of the thixotropic agent is 0.05 - 0.5%.

[0008] Preferably, the composite metal solder paste of the present invention comprises the following components in parts by mass: 55 - 60 parts of corrosion inhibitor-coated nano copper particles, 23 - 30 parts of interstitial metal particles, and 15 - 17 parts of an organic solvent system; wherein, the organic solvent system comprises a dispersant, a thixotropic agent, and a solvent, and the mass content of the dispersant in the organic solvent system is 1 - 1.3%, and the mass content of the thixotropic agent is 0.2 - 0.3%.

[0009] In the present invention, the corrosion inhibitor comprises at least one of α-hydroxy acids; specifically, the corrosion inhibitor is selected from at least one of malic acid, succinic acid, citric acid, and ascorbic acid, preferably succinic acid or malic acid.

[0010] In the present invention, the shape of the nano copper particles includes at least one of spherical and flaky, preferably spherical; the particle size range of the nano copper particles is 600 - 2000 nm, preferably 800 - 1500 nm, such as 800 nm, 900 nm, 1000 nm, 1200 nm, 1500 nm, and more preferably 1000 - 1200 nm.

[0011] In the present invention, the mass ratio of the corrosion inhibitor to the nano copper particles in the corrosion inhibitor-coated nano copper particles is (0.1 - 3):(97 - 99.9), preferably (1 - 2):(98 - 99).

[0012] In the present invention, the interstitial metal particles are selected from at least one of tin, indium, and bismuth, preferably tin or bismuth; the particle size range of the interstitial metal particles is 80 - 300 nm, such as 80 nm, 100 nm, 150 nm, 200 nm, 300 nm, and preferably 80 - 200 nm.

[0013] In the present invention, the dispersant is selected from at least one of fatty acids; preferably, the dispersant is selected from at least one of propionic acid, n-butyric acid, stearic acid, oleic acid, and capric acid, preferably n-butyric acid or stearic acid. The dispersant is mainly used to prevent particle agglomeration and ensure that the interstitial metal disperses into the gaps of the nano copper particles during the sintering process.

[0014] In the present invention, the thixotropic agent is selected from at least one of sodium polyacrylate, polyvinyl alcohol, polyvinylamide, hydroxyethyl cellulose, and polystyrene, preferably sodium polyacrylate or polyvinylamide. The thixotropic agent is mainly used to ensure the printing quality of the composite metal solder paste.

[0015] In the present invention, the solvent is selected from at least one of alcohol solvents; preferably, the solvent is selected from at least one of ethylene glycol, polyethylene glycol, propylene glycol, glycerol, terpineol, and diethylene glycol.

[0016] The present invention also provides a preparation method of the above composite metal solder paste, comprising the following steps:

[0017] S1: Mix the nano copper particles with the acid solution and then perform ultrasonic treatment. Centrifuge to remove the supernatant, add ethanol and perform ultrasonic treatment again, and then centrifuge to remove the supernatant to obtain pretreated nano copper particles;

[0018] S2. Mix the pretreated nano copper particles with the ethanol solution of the corrosion inhibitor and then perform ultrasonic treatment. Centrifuge to remove the supernatant, add ethanol and perform ultrasonic treatment again, and then centrifuge to remove the supernatant to obtain nano copper particles coated with the corrosion inhibitor;

[0019] S3. Mix the dispersant, thixotropic agent and solvent evenly to obtain an organic solvent system;

[0020] S4. Stir and mix the nano copper particles coated with the corrosion inhibitor, interstitial metal particles and the organic solvent system by mass parts to obtain a composite metal solder paste (also known as a low-temperature sintering type composite metal solder paste).

[0021] In step S1, the acid solution is at least one of dilute sulfuric acid and lactic acid; the ultrasonic treatment time after mixing the nano copper particles with the acid solution is 5 - 20 min, and the centrifugation speed is 7000 - 9000 r / min; the ultrasonic treatment time after adding ethanol is 5 - 20 min, and the centrifugation speed is 5000 - 7000 r / min.

[0022] In step S2, in the ethanol solution of the corrosion inhibitor, the mass ratio of the corrosion inhibitor to ethanol is (0.5 - 5):(95 - 99.5); the ultrasonic treatment time after mixing the pretreated nano copper particles with the ethanol solution of the corrosion inhibitor is 20 - 80 min; the ultrasonic treatment time after adding ethanol is 5 - 20 min.

[0023] In step S3, there is no limit to the mixing method of the organic solvent system as long as it can be mixed evenly, including but not limited to magnetic stirring for 40 - 100 min.

[0024] In step S4, stirring and mixing can be carried out by a mixer for 20 - 40 min.

[0025] The present invention also provides the application of the above composite metal solder paste in hermetic packaging.

[0026] The present invention also provides a method for hermetically connecting a metal package material, including the following steps:

[0027] A) Place the upper cover, sealing frame and bottom plate of the metal package material in ethanol for ultrasonic cleaning, and then dry to remove anhydrous ethanol;

[0028] B) Uniformly coat the above composite metal solder paste on the connection surface of the bottom plate by screen printing to form a stacked structure of the solder paste and the bottom plate;

[0029] C) Place the stacked structure formed in step B) in an oven for drying;

[0030] D) laminating the connection surfaces of the upper cover and the sealing frame onto the stacked structure after drying in step C) to form a stacked structure of the upper cover, solder paste and base plate;

[0031] E) placing the stacked structure formed in step D) under an inert atmosphere or a reducing atmosphere, maintaining it at a preset temperature and a preset pressure for a preset time, and then cooling it under the protection of the inert atmosphere to obtain a metal tube shell sealing structure.

[0032] In step A), the metal tube shell material includes an upper cover and a sealing frame, a bottom plate and a connecting layer for connecting the sealing frame and the bottom plate. The connecting layer is formed by sintering the above-mentioned composite metal solder paste through a sintering process.

[0033] In step C), the drying temperature is 90-140° C. and the drying time is 5-20 min.

[0034] In step E), the preset temperature is 200-250° C., the preset pressure is 5-20 MPa, and the preset time is 1-7 min; the temperature is lowered to below 100° C.

[0035] The present invention provides a low-temperature sintering composite metal solder paste. Nano copper particles with a relatively large particle size are mixed with a small particle size low melting point interstitial metal to prepare the solder paste. A dispersant is added to ensure that the small particle interstitial metal is evenly distributed in the gaps between the nano copper particles with a relatively large particle size. In the connection process, the nano copper particles form a sintered copper structure, and the low melting point interstitial metal melts at the pores of the copper sintered structure and fills the pores of the sintered copper, thereby forming a dense mixed sintered structure after cooling (the connection mechanism is as follows: Figure 7 As shown), this organization ensures the compactness of the sintered microstructure and its reliability as a sealing material. The sealing structure connected by the above-mentioned composite metal solder paste has high shear strength and high shear strength at high temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 It is a schematic diagram of the process of preparing a low temperature sintering composite metal solder paste;

[0038] Figure 2 It is a top view of the sealed metal shell structure;

[0039] Figure 3 It is the front view of the sealed metal shell structure;

[0040] Figure 4 Schematic diagram of the shell structure for sealing a metal shell

[0041] Figure 5 Shear strength diagram of the low-temperature sintered composite metal solder paste of Example 1 after connection at different temperatures with an auxiliary pressure of 20 MPa

[0042] Figure 6 Shear strength diagram obtained from high-temperature shear experiments of the low-temperature sintered composite metal solder paste of Example 1 at different temperatures

[0043] Figure 7 Schematic diagram of the connection mechanism of the low-temperature sintered composite metal solder paste

[0044] Explanation of reference numerals in the drawings

[0045] 1: Upper cover; 2: Sealing frame; 3: Bottom plate; 4: Solder paste coating area; 5: Sealing area Detailed implementation manners

[0046] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs

[0047] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form also includes the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof

[0048] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention

[0049] Example 1

[0050] This example provides a composite metal solder paste, which is composed of the following raw materials in mass percentage: 55% of nano copper particles coated with corrosion inhibitor, 30% of interstitial metal, and 15% of organic solvent system; wherein:

[0051] The particle size of the nano copper particles is 1000 - 1200 nm, and the morphology is spherical

[0052] The interstitial metal is tin, and the particle size of the tin particles is less than 150 nm;

[0053] The corrosion inhibitor is succinic acid, and the mass ratio of the corrosion inhibitor to the nano copper particles is 2:98.

[0054] The organic solvent system is composed of the following raw materials by mass percentage: 1% of dispersant, 0.3% of thixotropic agent, and 98.7% of solvent; among them:

[0055] The dispersant is n-butyric acid;

[0056] The thixotropic agent is sodium polyacrylate;

[0057] The solvent is composed of ethylene glycol, polyethylene glycol, propylene glycol and glycerol, and the mass ratio among ethylene glycol, polyethylene glycol, propylene glycol and glycerol in the solvent is 2:2:1:1.

[0058] Combined Figure 1 As shown, the preparation method of the composite metal solder paste of this embodiment includes the following steps:

[0059] S1: Mix the nano copper particles with dilute sulfuric acid and then ultrasonic for 10 min, then centrifuge at a centrifugal speed of 8000 r / min to remove the supernatant, add ethanol and ultrasonic for 10 min, and finally centrifuge at a centrifugal speed of 6000 r / min to remove the supernatant to obtain pretreated nano copper particles.

[0060] S2: Mix the pretreated nano copper particles obtained in step S1 with an ethanol solution of succinic acid, and the mass ratio of succinic acid to ethanol in the ethanol solution of succinic acid is 2:98. After mixing, ultrasonic for 40 min, then centrifuge to remove the supernatant, add ethanol and ultrasonic for 10 min, and centrifuge to remove the supernatant to obtain nano copper particles coated with a corrosion inhibitor.

[0061] S3: Weigh n-butyric acid, sodium polyacrylate, ethylene glycol, polyethylene glycol, propylene glycol and glycerol according to the ratio and stir magnetically for 60 min to obtain an organic solvent system.

[0062] S4. Weigh the nano copper particles coated with a corrosion inhibitor obtained in step S2, the organic solvent system and the interstitial metal particles according to the ratio, and place them in a blender and stir for 30 min to obtain a composite metal solder paste.

[0063] Apply the composite metal solder paste prepared above to the connection layer material for metal package sealing.

[0064] This embodiment also provides a sealing connection method for a metal package material based on the above composite metal solder paste. The sealing connection method of the metal package material, the structure of the sealed metal package is as Figures 2 - 4 shown, and the specific steps are as follows:

[0065] 1) Place the upper cover 1, the sealing frame 2, and the bottom plate 3 of the metal package material in ethanol and ultrasonically remove the surface dirt, and then dry it in a vacuum drying oven to remove anhydrous ethanol;

[0066] 2) Through stencil printing, uniformly coat the above-mentioned composite metal solder paste on the bottom plate connection surface obtained in step 1) according to the solder paste coating area 4 shown in Figure 4 ;

[0067] 3) Place the stacked structure of the composite metal solder paste-bottom plate obtained in step 2) in a drying oven, heat it up to 110 °C, keep it warm for 10 min, and dry it;

[0068] 4) Attach the connection surfaces of the upper cover and the sealing frame to the stacked structure obtained in step 3) to form a stacked structure of the upper cover and the sealing frame-composite metal solder paste-bottom plate;

[0069] 5) Place the stacked structure obtained in step 4) in a pressure-assisted sintering furnace, heat it up to 200 - 250 °C under a reducing atmosphere condition, apply a pressure of 20 MPa, keep it for 5 min, and then cool it down to 90 °C under the protection of an inert atmosphere to obtain a metal package sealing structure (see the sealing area 5 in Figure 4 ).

[0070] After use testing, after connecting the low-temperature sintered composite metal solder paste prepared in this embodiment at different temperatures, the measured shear strength is as shown in Figure 5 ; Figure 5 The results show that the shear strength of the metal package sealing structure is all above 50 MPa, meeting the usage requirements.

[0071] At the same time, the high-temperature shear strength is tested at different temperatures, and the shear strength is as shown in Figure 6 ; Figure 6 The results show that the metal package sealing structure has a high shear strength under high-temperature conditions.

[0072] In addition, the connection mechanism of the composite metal solder paste is as shown in Figure 7 . After connection, the organizational structure of the metal package sealing structure is dense and uniform, and the porosity is much lower than that of sintered copper, which can well meet the sealing requirements.

[0073] Example 2

[0074] This example provides a composite metal solder paste, which is composed of the following raw materials in mass percentage: 60% of nano-copper particles coated with corrosion inhibitor, 23% of interstitial metal, and 17% of organic solvent system. Among them:

[0075] The particle size of the nano-copper particles is 1000 - 1200 nm, and the morphology is spherical;

[0076] The interstitial metal is bismuth, and the particle size of bismuth particles is less than 200 nm;

[0077] The corrosion inhibitor is malic acid, and the mass ratio of the corrosion inhibitor to the nano copper particles is 1:99.

[0078] The organic solvent system is composed of the following raw materials in mass percentage: 1.3% of dispersant, 0.2% of thixotropic agent, and 98.5% of solvent; among them:

[0079] The dispersant is stearic acid;

[0080] The thixotropic agent is polyacrylamide;

[0081] The solvent is composed of polyethylene glycol and terpineol, and the mass ratio of polyethylene glycol to terpineol in the solvent is 1:1.

[0082] The preparation method of the composite metal solder paste of this embodiment includes the following steps:

[0083] S1: Mix the nano copper particles with dilute sulfuric acid and ultrasonicate for 10 min, then centrifuge at a centrifugal speed of 8000 r / min to remove the supernatant, add ethanol and ultrasonically oscillate for 10 min, and finally centrifuge at a centrifugal speed of 6000 r / min to remove the supernatant to obtain pretreated nano copper particles;

[0084] S2: Mix the pretreated nano copper particles obtained in step S1 with an ethanol solution of malic acid. The mass ratio of malic acid to ethanol in the ethanol solution of malic acid is 3:97. After mixing, ultrasonicate for 60 min, then centrifuge to remove the supernatant, add ethanol and ultrasonically oscillate for 15 min, and centrifuge to remove the supernatant to obtain nano copper particles coated with a corrosion inhibitor.

[0085] S3: Weigh stearic acid, polyacrylamide, polyethylene glycol, and terpineol according to the ratio and magnetically stir for 80 min to obtain an organic solvent system.

[0086] S4: Weigh the nano copper particles coated with a corrosion inhibitor obtained in step S2, the organic solvent system, and the interstitial metal particles according to the ratio, and place them in a blender and stir for 40 min to obtain a composite metal solder paste.

[0087] Apply the composite metal solder paste prepared above to the connection layer material for metal package sealing.

[0088] This embodiment also provides a sealing connection method for a metal package material based on the above composite metal solder paste. The specific steps are as follows:

[0089] 1) Place the upper cover, sealing frame, and bottom plate of the metal package material in ethanol and ultrasonically remove the surface dirt, and dry in a vacuum drying oven to remove anhydrous ethanol;

[0090] 2) The above-mentioned composite metal solder paste is evenly coated on the bottom plate connection surface obtained in step 1) by stencil printing according to Figure 4 the solder paste coating area shown;

[0091] 3) The stacked structure of the composite metal solder paste-bottom plate obtained in step 2) is placed in a drying oven, heated to 120 °C, kept warm for 10 min, and dried;

[0092] 4) The connection surfaces of the upper cover and the sealing frame are attached to the stacked structure obtained in step 3) to form a stacked structure of the upper cover and the sealing frame-composite metal solder paste-bottom plate;

[0093] 5) The stacked structure obtained in step 4) is placed in a pressure-assisted sintering furnace, heated to 220 °C under a reducing atmosphere condition, a pressure of 15 MPa is applied, and kept for 3 min. Subsequently, it is cooled to 90 °C under an inert atmosphere protection to obtain a metal package sealing structure.

[0094] After use testing, the shear strength of the low-temperature sintered composite metal solder paste prepared in this embodiment is above 40 MPa at different temperatures, meeting the use requirements; meanwhile, its high-temperature shear strength is tested at different temperatures, and the results show that the metal package sealing structure has a high shear strength. The organizational structure of the connected metal package sealing structure is dense and uniform, and the porosity is much lower than that of sintered copper, which can well meet the sealing requirements.

[0095] Comparative Example 1

[0096] Except for not adding tin particles, the rest, including nano copper powder coated with corrosion inhibitor, organic solvent system, connection process, etc., are the same as in Example 1.

[0097] The cross-section tissue of the metal package sealing joint formed after connection in this comparative example is cut, and a microscopic image is taken. The microscopic image shows that there are many connection holes in it, which cannot meet the sealing requirements.

[0098] Comparative Example 2

[0099] Except that the particle size of bismuth particles is 800 nm, the rest, including nano copper particles, organic solvent system, connection process, etc., are the same as in Example 2.

[0100] The shear strength of the metal package sealing joint formed after connection in this comparative example is tested, and the strength drops to 25 MPa. The cross-section tissue of the joint is observed, and a microscopic image is taken. It is found that due to the close particle size, the bismuth particles cannot be melted and filled in the pores of the copper particles, resulting in uneven joint tissue and a significant reduction in strength.

[0101] In summary, the present invention uses a mixture of large-sized nano copper particles and small-sized interstitial metals, and is prepared with an organic solvent system containing a dispersant. The low-temperature sintered composite metal solder paste has good performance, can complete high-quality connection at a lower temperature, the strength of the connection structure formed under the connection conditions is higher than 50 MPa, meeting the usage requirements; at the same time, it still has a high shear strength under high-temperature working conditions. The low-temperature sintered composite metal solder paste prepared by the preparation method of the present invention has a dense and uniform structure, and can well meet the sealing requirements of metal package materials.

[0102] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite metal solder paste, characterized in that, It comprises components in the following parts by mass: 50 - 75 parts of inhibitor-coated nano copper particles, 15 - 40 parts of interstitial metal particles, and 10 - 25 parts of organic solvent system; Among them, the organic solvent system includes a dispersant, a thixotropic agent, and a solvent. The mass content of the dispersant in the organic solvent system is 0.2 - 1.5%, and the mass content of the thixotropic agent is 0.05 - 0.5%; The inhibitor is malic acid or succinic acid, and the mass ratio of the inhibitor to the nano copper particles in the inhibitor-coated nano copper particles is (1 - 2):(98 - 99); The interstitial metal particles are tin or bismuth, and the particle size range of the interstitial metal particles is 80 - 300 nm; The dispersant is n-butyric acid or stearic acid; The thixotropic agent is sodium polyacrylate or polyacrylamide; The solvent is composed of ethylene glycol, polyethylene glycol, propylene glycol, and glycerol. The mass ratio among ethylene glycol, polyethylene glycol, propylene glycol, and glycerol in the solvent is 2:2:1:1; or the solvent is composed of polyethylene glycol and terpineol, and the mass ratio of polyethylene glycol to terpineol in the solvent is 1:

1.

2. The preparation method of the composite metal solder paste according to claim 1, characterized in that, It includes the following steps: S1: Mix the nano copper particles with an acid solution and then perform ultrasonic treatment. Centrifuge to remove the supernatant, then add ethanol and perform ultrasonic treatment, and centrifuge to remove the supernatant to obtain pretreated nano copper particles; S2: Mix the pretreated nano copper particles with an ethanol solution of the inhibitor and then perform ultrasonic treatment. Centrifuge to remove the supernatant, then add ethanol and perform ultrasonic treatment, and centrifuge to remove the supernatant to obtain inhibitor-coated nano copper particles; S3: Mix the dispersant, the thixotropic agent, and the solvent evenly to obtain an organic solvent system; S4: Stir and mix the inhibitor-coated nano copper particles, the interstitial metal particles, and the organic solvent system by mass parts to obtain a composite metal solder paste.

3. Application of the composite metal solder paste according to claim 1 in hermetic packaging.

4. A method for sealing and connecting a metal shell material, characterized in that, It includes the following steps: A) Place the upper cover, the sealing frame, and the bottom plate of the metal package material in ethanol for ultrasonic cleaning, and then dry to remove anhydrous ethanol; B) Uniformly coat the composite metal solder paste according to claim 1 on the connecting surface of the bottom plate by stencil printing to form a stacked structure of the solder paste and the bottom plate; C) Place the stacked structure formed in step B) for drying; D) Attach the connecting surfaces of the upper cover and the sealing frame to the stacked structure dried in step C) to form a stacked structure of the upper cover, the solder paste, and the bottom plate; E) Place the stacked structure formed in step D) under an inert atmosphere or a reducing atmosphere condition, maintain it at a preset temperature and a preset pressure for a preset time, and then cool down under the protection of an inert atmosphere to obtain a metal package sealing structure.

5. The method for hermetically connecting a metal package material according to claim 4, characterized in that In step C), the drying temperature is 90 - 140 °C, and the drying time is 5 - 20 min; in step E), the preset temperature is 200 - 250 °C, the preset pressure is 5 - 20 MPa, and the preset time is 1 - 7 min.

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