Components for joining

Abstract

The present invention provides a bonding composition capable of producing a bonded body with excellent bonding strength while suppressing the occurrence of pores, a method for manufacturing such a bonded body, and a bonded body having a sintered body with few coarse pores and excellent bonding strength. [Solution] The product contains silver nanoparticles (A) and silver filler (B), wherein the particle size of the silver nanoparticles (A) is less than 100 nm, and the silver filler (B) has a particle size of 100 nm or more and a specific surface area of ​​0.42 to 1.2 m². 2 A bonding composition comprising a spherical filler in a quantity of / g, wherein the mass ratio (A / B) of the silver nanoparticles (A) to the silver filler (B) is 0.1 to 0.55.

Description

[Technical Field]

[0001] The present invention relates to a bonding composition, a bonded body, and a method for producing the same. [Background technology]

[0002] The use of silver paste as a bonding agent between semiconductor elements and substrates is being considered. Sintered silver paste offers advantages such as excellent heat resistance, thermal conductivity (heat dissipation), and electrical conductivity.

[0003] For example, Patent Document 1 discloses a silver paste containing silver particles with a particle size of 1 to 20 μm and silver particles with a particle size of 1 to 300 nm coated with a specific protective agent. In the aforementioned Patent Document 1, plate-shaped silver particles are used.

[0004] In Patent Document 2, the present inventors disclose a bonding composition containing metal powder, specific coated group particles, and liquid paraffin as a bonding composition with excellent bonding strength. Furthermore, in Patent Document 3, the present inventors disclose a bonding composition that has excellent bonding strength, which contains metal powder, specific coated particles, and an aliphatic carboxylic acid-based solvent or an aliphatic aldehyde-based solvent having a boiling point of 160 to 300°C. In the embodiments described in Patent Documents 2 and 3, 2 mm square Si chips are joined together to evaluate the bonding strength and other properties. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2015-82385 [Patent Document 2] Japanese Patent Publication No. 2020-87765 [Patent Document 3] Japanese Patent Publication No. 2020-87766 [Overview of the project] [Problems that the invention aims to solve]

[0006] The inventor of the present invention is considering joining members with a larger bonding surface area. In joining members with a large bonding surface area, when joining is performed using a conventional silver paste, large pores (voids) that did not pose a problem when the bonding surface area in the sintered body was small are likely to occur, and the bonding strength per unit area may easily decrease. The voids generated in the sintered body have a low thermal conductivity. For example, when the joined member is a semiconductor element, the heat exhaust performance of the heat generated from the element decreases. Further, when further processing such as wire bonding is performed on the element after joining, if there is a void near the bottom of the bonding portion, force may be applied locally to the element and damage may be caused.

[0007] The present invention solves such problems, and provides a bonding composition capable of manufacturing a sintered body that suppresses the generation of pores and has excellent bonding strength, a method for manufacturing a bonded body, and a bonded body having a sintered body with few large pores and excellent bonding strength.

Means for Solving the Problems

[0008] The bonding composition according to the present invention contains silver nanoparticles (A) and a silver filler (B), the particle size of the silver nanoparticles (A) is less than 100 nm, the silver filler (B) is a spherical filler having a particle size of 100 nm or more and a specific surface area of 0.42 to 1.2 m 2 / g, and the mass ratio (A / B) of the silver nanoparticles (A) to the silver filler (B) is 0.1 to 0.55.

[0009] One embodiment of the above bonding composition is that the tap density of the silver filler (B) is 5.5 g / cm 3 or more.

[0010] One embodiment of the above bonding composition further contains a solvent (C), and the solvent (C) includes liquid paraffin.

[0011] In one embodiment of the above bonding composition, the mass ratio (A / B) is 0.1 to 0.3.

[0012] The method for manufacturing a bonded body according to the present invention is A method for manufacturing a bonded body in which a first bonding member and a second bonding member are bonded, A coating film of the bonding composition according to the present invention is formed on the bonding surface of the first bonding member, The second bonding member is disposed on the coating film, The coating film is sintered.

[0013] In one embodiment of the above method for manufacturing a bonded body, the coating film is sintered without pressure.

[0014] In one embodiment of the above method for manufacturing a bonded body, the firing conditions when sintering the coating film are heating at a firing temperature of 200 to 300 °C for 10 minutes or more.

[0015] In one embodiment of the above method for manufacturing a bonded body, the rate of temperature increase to the firing temperature is 3 to 20 °C / min.

[0016] In one embodiment of the above method for manufacturing a bonded body, the temperature is continuously increased at the rate of temperature increase to the firing temperature.

[0017] In one embodiment of the above method for manufacturing a bonded body, the area of the bonding surface is 10 mm 2 or more, and the method for manufacturing a bonded body according to any one of claims 5 to 9.

[0018] The bonded body according to the present invention is A bonded body in which a first bonding member and a second bonding member are bonded via a silver sintered body, The silver sintered body is a sintered body of the bonding composition according to the present invention, the area of the bonding surface is 10 mm 2 or more, and the bonding strength per unit area is 15 MPa or more.

Advantages of the Invention

[0019] The present invention provides a bonding composition capable of producing a sintered body with excellent bonding strength while suppressing the occurrence of pores, a method for manufacturing a bonded body, and a bonded body having a sintered body with few coarse pores and excellent bonding strength. [Brief explanation of the drawing]

[0020] [Figure 1] This is an SEM image of the cross-section of the joint in Comparative Example 1. [Figure 2] This is an SEM image of the cross-section of the joint in Comparative Example 1. [Figure 3] This is an SEM image of the cross-section of the joint in Example 2. [Figure 4] This is an SEM image of the cross-section of the joint in Example 2. [Figure 5] This is an SEM image of the cross-section of the joint in Example 3. [Figure 6] This is an SEM image of the cross-section of the joint in Example 3. [Modes for carrying out the invention]

[0021] The following describes the bonding composition, bonded body, and method for manufacturing the same according to the present invention. In this invention, the "~" symbol indicating a numerical range means that the numbers written before and after it are included as the lower and upper limits, respectively. Furthermore, in this invention, specific surface area is defined as surface area per unit mass.

[0022] [Joining composition] The bonding composition according to the present invention (hereinafter sometimes referred to as "this bonding composition") contains silver nanoparticles (A) and silver filler (B), wherein the particle size of the silver nanoparticles (A) is less than 100 nm, and the silver filler (B) has a particle size of 100 nm or more and a specific surface area of ​​0.42 to 1.2 m². 2 The spherical filler is in a quantity of / g, and the mass ratio (A / B) of the silver nanoparticles (A) to the silver filler (B) is 0.1 to 0.55.

[0023] This bonding composition comprises silver nanoparticles (A) with a particle size of less than 100 nm and particles with a particle size of 100 nm or more and a specific surface area of ​​0.42 to 1.2 m². 2 It is used in combination with spherical silver filler (B) in a quantity of / g. For example, when plate-shaped silver fillers are used, they can theoretically be arranged without gaps, but uniform arrangement is difficult during the coating process, and in practice, large gaps are formed, which can cause voids during sintering. In contrast, the silver fillers (B) in this bonding composition are spherical, so they are easily filled uniformly when formed into a coating. Silver nanoparticles (A) are mainly placed in the gaps between the silver fillers (B) in the coating and contribute to the bonding of the silver fillers (B) to each other during sintering. In this bonding composition, the mass ratio (A / B) of silver nanoparticles (A) to silver filler (B) is 0.1 to 0.55. A ratio of 0.1 or higher improves bonding strength. However, the upper limit of A / B is 0.55, indicating a relatively high proportion of silver filler (B). When a composition with a high proportion of silver nanoparticles (A) is formed into a coating film, the silver nanoparticles (A) completely fill the gaps between the silver filler (B). Therefore, vaporized solvents and coating materials during firing tend to accumulate and not flow out of the coating film, sometimes leading to the formation of large voids caused by these solvents. These voids were more likely to occur the greater the distance from the center to the side of the coating film, i.e., the larger the area of ​​the bonding surface. Furthermore, compositions with a high proportion of silver nanoparticles (A) are prone to volume shrinkage during firing. While volume shrinkage tends to increase bonding strength, it is presumed that voids are likely to form due to volume shrinkage and the retention of the aforementioned solvent. In this bonding composition, by setting the A / B ratio to 0.55 or less, an appropriate gap is left between the silver fillers (B) in the coating film, creating a condition in which vaporized solvent can easily flow to the sides, and volume shrinkage is suppressed. As a result, it is presumed that void formation is suppressed. Furthermore, when metal particles are joined by heating and sintering, shrinkage may occur in each material, including the sintered film and the joined members, due to cooling after heating. This can cause warping of the joined members. When a composition with a high proportion of silver nanoparticles is used, the volume contraction of the silver nanoparticles may cause distorted warping of the joined members. In contrast, a joint using this joining composition will be concentric even if warping occurs in the joined members, thus minimizing the impact on the joined members.

[0024] This bonding composition contains at least silver nanoparticles (A) and silver filler (B), and may further contain other components as needed. Each component of this bonding composition will be described in turn.

[0025] <Silver nanoparticles (A)> In this bonding composition, silver nanoparticles (A) with a particle size of less than 100 nm are used. These silver nanoparticles (A) have low-temperature sinterability and promote the bonding of silver filler (B) to improve bonding strength.

[0026] The particle size of the silver nanoparticles (A) should be less than 100 nm and can be adjusted as appropriate from the viewpoint of firing conditions, etc. Preferably, the particle size of the silver nanoparticles (A) is 80 nm or less, and more preferably 70 nm or less. Also, the particle size of the silver nanoparticles (A) is usually 1 nm or more, preferably 5 nm or more, and more preferably 20 nm or more. The particle size of the silver nanoparticles (A) is the primary particle size and can be measured from images obtained by scanning electron microscopy (SEM). The shape of the silver nanoparticles (A) may be spherical, plate-shaped, rod-shaped, or any other shape, but a spherical shape is preferred. In this invention, a spherical shape refers to a particle with an aspect ratio (a / b) of 1 to 2, where 1 to 1.5 is preferred.

[0027] The silver nanoparticles (A) may be coated with a coating compound on their surface. The presence of the coating compound suppresses oxidation of the silver nanoparticle (A) surface, resulting in a bonding layer with excellent conductivity. The particle size of the silver nanoparticles (A) does not include the coating compound.

[0028] The coating compound is preferably one that decomposes or volatilizes easily upon heating at 100 to 300°C. The coating compound is preferably physically adsorbed or ionically adsorbed from the viewpoint of desorption during heating, and an organic compound having a polar group is preferred. Examples of polar groups include amino groups, hydroxyl groups, carboxyl groups, aldehyde groups, and amide groups. Furthermore, it is preferable that the coating compound has a linear hydrocarbon group from the viewpoint of dispersibility of silver nanoparticles (A). In addition, aliphatic amines, aliphatic alcohols, amino alcohols, fatty acids (aliphatic carboxylic acids), aliphatic aldehydes, fatty acid alkanolamides, and fatty acid aminoalkyl esters are preferred from the viewpoint of suppressing surface oxidation of silver nanoparticles and suppressing aggregation of silver nanoparticles. The coating compound can be used individually or in combination of two or more types.

[0029] Specific examples of coated compounds include aliphatic amines such as octylamine, decylamine, dodecylamine, and oleylamine; Aliphatic alcohols such as hexanol, octanol, decanol, dodecanol, and oleyl alcohol; Amino alcohols such as ethanolamine, propanolamine, octanolamine, decanolamine, dodecanolamine, and oleyl alcoholamine; Fatty acids such as butyric acid, caproic acid, caprylic acid, pelargonic acid, undecanoic acid, stearic acid, palmitoleic acid, oleic acid, vaccenic acid, linoleic acid, and linolenic acid; Aliphatic aldehydes such as butanal, hexanal, octinal, nonanal, decanal, undecylaldehyde, octadecylaldehyde, and hexadecenylaldehyde; Fatty acid alkanolamides such as caproic acid ethanolamide, caprylic acid propanolamide, lauric acid ethanolamide, tridecyl acid propanolamide, and palmitic acid propanolamide; Examples include aminoethyl caproate, aminopropyl caprylate, aminoethyl laurate, aminopropyl laurate, aminopropyl palmitate, and other aminoalkyl fatty acids.

[0030] The number of carbon atoms in the linear hydrocarbon group constituting the above-mentioned coated compound is preferably 3 or more, more preferably 5 or more, and even more preferably 7 or more, from the viewpoint of oxidation suppression and dispersibility in the solvent. Furthermore, from the viewpoint of detachability during heating, the number of carbon atoms in the aliphatic group is preferably 24 or less, more preferably 16 or less, and even more preferably 12 or less.

[0031] The coating compound preferably forms a monolayer with polar groups positioned on the silver particle side, from the viewpoint of suppressing surface oxidation of silver nanoparticles and exhibiting desorption during heating. Furthermore, when the coating compound forms a monolayer, the coating density on the surface of the silver nanoparticles is 2.5 to 5.2 molecules / nm. 2 It is preferable that this be the case.

[0032] Furthermore, a fatty acid or aliphatic aldehyde is preferred as the coating compound because it suppresses the particle size distribution of silver nanoparticles (A) by the method described later, making it easier to obtain silver nanoparticles with relatively uniform particle size. In addition, if the silver filler (B) has an oxide film, the fatty acid or aliphatic aldehyde also has the effect of removing the oxide film, contributing to improved bonding strength and conductivity.

[0033] Silver nanoparticles (A) are substantially composed of silver particles, but may also contain silver oxide, silver hydroxide, or other elements that are inevitably present, as long as they do not impair the effects of the present invention. From the viewpoint of bonding strength, the content of silver oxide and silver hydroxide is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less, relative to the total amount of silver particles. Also from the viewpoint of bonding strength, the purity of silver in the silver particles is preferably 95% by mass or more, more preferably 97% by mass or more, and even more preferably 99% by mass or more.

[0034] Coated silver nanoparticles coated with fatty acids or aliphatic aldehydes can be produced by referring to, for example, Japanese Patent Application Laid-Open No. 2017-179403. According to the method of Japanese Patent Application Laid-Open No. 2017-179403, fatty acids or aliphatic aldehydes are arranged on the surface of spherical silver nanoparticles (A) with an average particle size of 10 to 80 nm and a particle size distribution of about average particle size ±10 nm, and a coating layer of a monolayer is formed. The coating density of the coating layer is 2.5 to 5.2 molecules / nm 2 Thus, silver nanoparticles (A) excellent in suppression of surface oxidation and dispersibility can be obtained. The coating density can be calculated using the method of Japanese Patent Application Laid-Open No. 2017-179403. Moreover, commercially available products in which silver nanoparticles (A) are coated with a desired coating compound may also be used.

[0035] <Silver filler (B)> In this bonding composition, the silver filler (B) uses spherical fillers having a particle size of 100 nm or more and a specific surface area of 0.42 to 1.2 m 2 / g. By using the silver filler, the silver filler (B) is relatively easily arranged uniformly during film formation, and since it is filling between spheres, spaces are also secured relatively uniformly.

[0036] The particle size of the silver filler (B) only needs to be 100 nm or more, and the upper limit may be appropriately adjusted in consideration of the film thickness of the obtained sintered body and the like. The particle size of the silver filler (B) can be, for example, 100 μm or less, preferably 50 μm or less, more preferably 25 μm or less. Also, the particle size of the silver filler (B) is preferably 200 nm or more, more preferably 500 nm or more. The particle size of the silver filler (B) is the primary particle size, and it can be measured from an image obtained by SEM or an optical microscope according to the particle size.

[0037] The silver filler (B) has a specific surface area of 0.42 to 1.2 m 2 / g. The bonding strength is improved when the ratio of the surface acting with the silver nanoparticles (A) is within the above range. The specific surface area is preferably 0.6 to 1.0 m 2 / g, especially from the perspective of bonding strength. The specific surface area of the silver filler (B) can be measured by the nitrogen gas adsorption method.

[0038] Furthermore, the tap density of silver filler (B) is 5.5 g / cm³ from the standpoint of bonding strength. 3 The above is preferable, 5.8 g / cm³ 3 The above is preferable. On the other hand, from the viewpoint of suppressing voids in the sintered body, the tap density should be 7.7 g / cm³. 3 The following is preferable: 6.7 g / cm³ 3 The following are preferable.

[0039] The silver filler (B) is substantially composed of silver particles, but may also contain silver oxide, silver hydroxide, or other elements that are inevitably present, as long as they do not impair the effects of the present invention. From the viewpoint of bonding strength, the content of silver oxide and silver hydroxide is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less, relative to the total amount of silver filler. Also from the viewpoint of bonding strength, the purity of silver in the silver filler is preferably 95% by mass or more, more preferably 97% by mass or more, and even more preferably 99% by mass or more.

[0040] Furthermore, the silver filler (B) may be surface-treated to suppress corrosion such as oxidation. Examples of surface treatment include coating with a coating compound for the silver nanoparticles (A) or forming an oxide film.

[0041] Silver filler (B) may be manufactured by known methods or a commercially available product may be used. Examples of commercially available products include SL01 manufactured by Mitsui Mining & Smelting Co., Ltd.

[0042] In this bonding composition, the mass ratio (A / B) of silver nanoparticles (A) to silver filler (B) is 0.1 to 0.55. By setting A / B within this range, the generation of coarse pores in the sintered body is suppressed, and a bonded body with excellent bonding strength can be obtained. Furthermore, from the standpoint of suppressing uneven warping, it is preferable that the above mass ratio (A / B) is 0.1 to 0.5.

[0043] <Solvent (C)> The bonding composition preferably contains a solvent (C) from the viewpoint of ease of coating. Solvent (C) can be appropriately selected from solvents capable of dispersing silver nanoparticles (A) and silver filler (B) depending on the coating method (printing method), etc. The solvent may be a single solvent or a mixed solvent of two or more solvents.

[0044] From the viewpoint of the dispersibility of silver nanoparticles (A) and compatibility with the coating compound, the solvent (C) preferably includes aliphatic amine solvents, aliphatic alcohol solvents, aliphatic amino alcohol solvents, aliphatic carboxylic acid solvents, aliphatic aldehyde solvents, terpine acetate solvents, aliphatic alkane solvents, and carbitol solvents.

[0045] Specific examples of solvent (C) include aliphatic amine solvents such as octylamine, decylamine, dodecylamine, and oleylamine; Aliphatic alcohol solvents such as hexanol, octanol, decanol, dodecanol, and oleyl alcohol; Aliphatic amino alcohol solvents such as ethanolamine, propanolamine, octanolamine, decanolamine, dodecanolamine, and oleyl alcoholamine; Aliphatic carboxylic acid solvents such as hexanoic acid, heptanoic acid, octanoic acid, and nonanoic acid; Aliphatic aldehyde solvents such as octanal, decanal, dodecanal, and tridecanal; Terpine acetate solvents such as 1,8-terpine-1-acetate, 1,8-terpine-8-acetate, and 1,8-terpine-1,8-diaacetate; Aliphatic alkane solvents such as octane, decane, dodecane, and liquid paraffin; Examples include carbitol-based solvents such as butyl carbitol, hexyl carbitol, and decyl carbitol. Furthermore, from the standpoint of preserving the silver nanoparticles (A), it is preferable that the solvent (C) contains 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate.

[0046] In order to suppress the oxidation of silver nanoparticles (A) and silver filler (B) during firing, etc., it is preferable that the solvent (C) contains an aliphatic carboxylic acid-based solvent or an aliphatic aldehyde-based solvent, and in particular, it is preferable that it contains an aliphatic aldehyde-based solvent.

[0047] Furthermore, the solvent (C) preferably contains liquid paraffin. Liquid paraffin is a mixture of aliphatic hydrocarbons with different numbers of carbon atoms and has a wide range of vaporization temperatures. Therefore, liquid paraffin gradually volatilizes during firing and does not easily remain in the coating film, suppressing the formation of large voids and resulting in a bonded body with excellent bonding strength. Examples of commercially available liquid paraffin include the Hycol K series (manufactured by Kaneda Corporation).

[0048] When using liquid paraffin, its proportion is preferably 10 to 80% by mass, and more preferably 20 to 70% by mass, relative to 100% by mass of the total amount of solvent (C). Furthermore, when using an aliphatic carboxylic acid solvent or an aliphatic aldehyde solvent, the total proportion is preferably 0.5 to 20% by mass, and more preferably 1 to 10% by mass, based on 100% by mass of the total amount of solvent (C).

[0049] The proportion of solvent (C) in this bonding composition can be adjusted as appropriate depending on the coating method applied to the members to be bonded. For example, in 100% by mass of the total amount of this bonding composition containing solvent (C), solvent (C) can be 1 to 40% by mass, and 5 to 20% by mass is preferred. Furthermore, the total content ratio of silver nanoparticles (A) and silver filler (B) in this bonding composition can be 60 to 99% by mass of solvent (C) out of 100% by mass of the total bonding composition, with 80 to 95% by mass being preferred.

[0050] <Optional ingredients> The bonding composition may further contain other components to the extent that it achieves the effects of the present invention. Examples of such other components include antioxidants, dispersants, thickeners, and gelling agents.

[0051] When solvent (C) is used, the method for preparing the bonding composition is one that allows for the uniform dispersion of silver nanoparticles (A) and silver filler (B) in the solvent (C). For example, the bonding composition can be obtained by adding silver nanoparticles, silver filler, and optionally the above-mentioned optional components to the solvent and dispersing them using a known stirrer or disperser.

[0052] [Method for manufacturing a jointed body] The method for manufacturing a jointed body according to the present invention (hereinafter also referred to as the manufacturing method) is: A method for manufacturing a joined body in which a first member to be joined and a second member to be joined are joined, A coating film of the bonding composition is formed on the bonding surface of the first member to be bonded. The second member to be joined is placed on the coating film, The aforementioned coating film is sintered.

[0053] According to the above-described joining method, a joined body can be obtained that has fewer coarse pores and a sintered body with excellent joining strength. The manufacturing method will be described below, but the joining composition has been described above and will not be explained here.

[0054] First, a coating film of the bonding composition is formed on the bonding surface of the first member to be bonded. The method for forming the coating film can be appropriately selected from known coating and printing methods. Dispenser coating or screen printing is preferred because it allows for the formation of a patterned coating film and enables the creation of a thick film.

[0055] Dispenser application is a method of applying the bonding composition using a device that dispenses a fixed amount of the bonding composition. The dispensing method is not particularly limited and can be appropriately selected from, for example, an air pulse method, a mechanical method, a non-contact method, a plunger method, etc. As an example, in the case of an air pulse type dispenser, the bonding composition is filled into a syringe and an air pulse is applied to dispense a fixed amount of the bonding composition at a time, and applied in a predetermined pattern such as dots. By lightly pressing the second member to be bonded, the bonding composition wets and spreads on the bonding surface. Screen printing is a method of transferring a bonding composition to a predetermined pattern by applying a bonding composition to a screen having predetermined openings, placing the screen on the first member to be bonded, and pressing the screen against the first member to be bonded using a squeegee. The film thickness of the bonding composition coating can be appropriately adjusted within the range of, for example, 1 to 100 μm, with 2 to 80 μm being preferred. The first and second members to be joined may be appropriately selected depending on the intended use of the joined body to be manufactured. The material of the joining surface of the members to be joined only needs to have heat resistance to the sintering temperature, and examples include metals such as gold, silver, and copper, as well as silicon, glass, and inorganic ceramics. From the viewpoint of superior bonding properties with this joining composition, the aforementioned metals are preferred.

[0056] Next, the joining surface of the second member to be joined is placed on the coating film. At this time, pressure may be applied from the second member to be joined toward the first member to ensure close contact with the coating film. Alternatively, the coating film may be dried after its formation but before the second member to be joined is placed.

[0057] Next, the coating film is sintered to form a bonding layer that joins the first and second members to be joined. The firing conditions for sintering the coating film can be adjusted as appropriate, taking into consideration the sinterability of the silver nanoparticles (A). Regarding firing conditions, it is preferable that the heating rate to reach the firing temperature be 3 to 20°C / min. By increasing the heating rate to 3°C / min or higher, the time to reach the firing temperature can be shortened, improving productivity. Furthermore, by using this bonding composition, the formation of large voids is suppressed even at heating rates of 3°C / min or higher, resulting in excellent bonding strength. In fact, the formation of large voids is also suppressed by using heating rates of 20°C / min or lower. Although there are known methods of preheating at intermediate temperatures rather than raising the temperature to the firing temperature all at once to remove solvents, in this manufacturing method, the temperature may be continuously raised to the firing temperature at a constant heating rate. The firing temperature is preferably 200 to 300°C, taking into consideration the sinterability of silver nanoparticles (A) and the ease of removing organic substances such as solvents (C). The heating time at the firing temperature should be 10 minutes or more, and can be appropriately adjusted within the range of 15 minutes to 12 hours, preferably 20 minutes to 2 hours. Pressurization may be applied during firing to improve the bonding strength, but sufficient bonding strength can be obtained even without pressurization using this manufacturing method. Furthermore, firing may be carried out in the presence of oxygen, such as in the atmosphere, or in the absence of oxygen by purging with nitrogen. When firing is carried out in the presence of oxygen, carbon content in the coating is more easily removed, which tends to improve bonding strength. On the other hand, if other components are easily oxidized by heating, it is preferable to fire in the absence of oxygen.

[0058] According to the above-described method for manufacturing a joined body, for example, if the area of ​​the joining surface is 10 mm 2 As described above, even with relatively large areas, it is possible to obtain a sintered body with few coarse pores and excellent bonding strength, and a joined body can be obtained in which the first member to be joined and the second member to be joined are joined via a high-density bonding layer.

[0059] Thus, according to this manufacturing method, a joint is formed in which a first member to be joined and a second member to be joined are joined via a silver sintered body, and the joint is a sintered body of the aforementioned joining composition. The surface area of ​​the joining surface is 10 mm 2 That's all. A joint can be obtained that has a joint strength of 15 MPa or more per unit area. [Examples]

[0060] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0061] (Manufacturing Example 1: Manufacturing of coated silver nanoparticles Ag1) Referring to Japanese Patent Publication No. 2017-179403, the surface of silver nanoparticles (A) has a thickness of 2.5 to 5.2 nm. 2 Coated silver nanoparticles Ag1 coated with undecanoic acid were produced at the specified coating density. The particle size of the coated silver nanoparticles Ag1 was 55 nm ± 10 nm. The obtained coated silver nanoparticles Ag1 were dispersed in 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (solvent, manufactured by KH Neochem Co., Ltd., Kyowanol M) to prepare a dispersion (85% by mass of coated silver nanoparticles, 15% by mass of solvent).

[0062] (Example 1) <1. Preparation of bonding composition> 7.00 parts by mass of a dispersion of the coated silver nanoparticles Ag1, and silver filler (manufactured by Mitsui Mining & Smelting Co., Ltd., SL01; specific surface area 0.69 m²). 2 Spherical particles / g, tap density 6.25g / cm³ 3 Composition 1 was obtained by mixing 11 parts by mass of a particle size D50 (1.25 μm), 0.1 parts by mass of decanal, 1 part by mass of liquid paraffin (manufactured by Kaneda Co., Ltd., Hycol K-230), and 1.35 parts by mass of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (manufactured by KH Neochem Co., Ltd., Kyowanol M).

[0063] <2. Manufacturing of the assembled product> Using the above-mentioned bonding composition 1, the following four bonded bodies were manufactured. (1) Two of each of the two types of laminates were manufactured according to (1-1) and (1-2) below. (1-1) The bonding composition was applied to a 10 mm square gold-plated silicon substrate to form a coating film. Next, a 5 mm square gold-plated silicon chip was placed on the coating film, and pressure was applied to obtain a laminate 1 with a film thickness of approximately 50 μm before firing. (1-2) The bonding composition was applied to a 5mm square gold-plated silicon substrate to form a coating film. Next, a 2mm square gold-plated silicon chip was placed on the coating film, and pressure was applied to obtain a laminate 2 with a film thickness of approximately 50 μm before sintering. (2) The laminates 1 and 2 described above were fired under the firing conditions (2-1) and (2-2) below to produce a total of four types of laminates. (2-1) Under a nitrogen-purged atmosphere, the temperature was raised to 250°C at a heating rate of 3°C / min and fired for 30 minutes. During firing, nitrogen gas was supplied to the electric furnace at an N2 flow rate of 5 L / min. After firing, the nitrogen flow was continued until the temperature inside the furnace fell below 50°C. The cooling time was approximately 2 hours. (2-2) Under atmospheric conditions, the furnace was heated to 225°C at a heating rate of 3°C / min and fired for 30 minutes. After firing, the assembled body was removed after confirming that the temperature inside the furnace had fallen below 50°C. The cooling time was approximately 10 minutes.

[0064] (Examples 2-7 and Comparative Examples 1-8) Each bonding composition was obtained in the same manner as in Example 1, except that the type and amount of each component were changed as shown in Table 1 in <1. Preparation of bonding composition> of Example 1.

[0065] Next, following the same procedure as in <2. Manufacturing of the Joint> of Example 1, a joint was manufactured using the joining composition of each example and comparative example. For Comparative Examples 3 to 8, only the laminates described in (1-2) above were manufactured.

[0066] [evaluation] <Joining strength> For each bond obtained in the above examples and comparative examples, a die shear test was performed using a bond tester (Condor Sigma: manufactured by XYZTEC, Netherlands), and the shear strength [kgf] and its converted value per unit area [MPa] were determined. The results are shown in Table 1.

[0067] [Table 1]

[0068] The silver fillers in Table 1 are as follows: • SL01: Manufactured by Mitsui Mining & Smelting Co., Ltd., specific surface area 0.69 m² 2 Spherical particles / g, tap density 6.25g / cm³ 3 The particle size D50 is 1.25 μm. • AG-2-8F: Manufactured by DOWA High-Tech Co., Ltd., specific surface area 0.97 m² 2 The spherical particles per gram have a particle size D50 of 0.9 μm. • AG-3-8-FDI: Manufactured by DOWA High-Tech Co., Ltd., specific surface area 0.49 m² 2 The spherical particles per gram have a particle size D50 of 1.7 μm. • AG-4-8F: Manufactured by DOWA High-Tech Co., Ltd., specific surface area 0.44 m² 2 Spherical particles weighing / g, tap density 5.2g / cm³ 3 The particle size D50 is 1.9 μm. ·SPQ03R: Specific surface area 1.40m 2 Spherical particles / g, tap density 4.6g / cm³ 3 The particle size D50 is 0.8 μm. ·SPN10JS: Specific surface area 0.40m 2 Spherical particles weighing / g, tap density 5.3g / cm³ 3 The particle size D50 is 2.0 μm. ·SPH02J: Specific surface area 1.66m 2 Aggregated powder at / g, tap density 2.8g / cm³ 3 The particle size D50 is 1.8 μm.

[0069] <Cross-sectional observation> The laminate was manufactured in the same manner as described above, except that the heating rate was changed to 10°C / min in both of the firing conditions described in (2-1) and (2-2) of <2. Manufacturing of the bonded body>. Each joint was cut through the central part of the joint surface, and the cross-section was observed. The results are shown in Table 2. SEM images of the cross-sections of Comparative Example 1, Example 2, and Example 3 are shown in Figures 1 to 6. In Figures 1 to 6, the upper row shows the SEM image of the joint fired in an atmospheric environment, and the lower row shows the SEM image of the joint fired in a nitrogen atmosphere. (Evaluation Criteria) ○ (Good): No voids larger than 3 μm were observed. × (Unacceptable): Voids or delamination of 3 μm or larger were observed.

[0070] [Table 2]

[0071] <Volume resistivity> Kapton tape with a thickness of 50 μm was attached to both ends of a glass slide that had been cleaned with acetone. The bonding compositions of the above examples and comparative examples were applied to the glass slides, respectively, and a coating film with a thickness of 50 μm was formed by squeezing. The Kapton tape was removed, and the slides were fired in a nitrogen-purged atmosphere at a heating rate of 3°C / min to 250°C for 30 minutes. During firing, nitrogen gas was supplied to the electric furnace at an N2 flow rate of 5 L / min. The thickness of the obtained strip-shaped sintered body was measured at three locations, and the volume resistivity was measured using the four-probe method (using a resistivity meter MODELK-705RS manufactured by Kyowa Riken Co., Ltd.). Separately, the same measurements were performed on sintered bodies manufactured using the same method as above, except that the firing conditions were changed to firing in an atmospheric environment at a heating rate of 3°C / min to 225°C for 30 minutes. The results are shown in Table 3.

[0072] [Table 3]

[0073] [Summary of results] As shown in Figure 1, even with the bonding composition of Comparative Example 1, the bonding surface is 4 mm 2 In cases of this magnitude, the formation of large voids is not observed. However, as shown in Figure 2, the joint surface is 25 mm 2 In this case, the occurrence of voids near the center becomes more noticeable. In contrast, as shown in Figures 3 to 6, the bonding compositions of Examples 2 and 3, in which the mass ratio (A / B) of silver nanoparticles (A) to silver filler (B) was adjusted to the range of 0.1 to 0.55, have a bonding surface of 25 mm. 2 Even in this case, no large voids were observed. As shown in Tables 1-3, silver nanoparticles (A) have a particle size of less than 100 nm, and silver nanoparticles with a particle size of 100 nm or more and a specific surface area of ​​0.5-1.2 m². 2 This bonding composition, which combines spherical filler (B) at a mass ratio (A / B) of 0.1 to 0.88, has a bonding surface area of ​​10 mm².2 Even with the above conditions, it was shown that there are no large voids and that a joint strength of 15 MPa or higher can be achieved.

Claims

1. It contains silver nanoparticles (A) and silver filler (B), The particle size of the silver nanoparticles (A) is less than 100 nm. The silver filler (B) has a particle size of 100 nm or more and a specific surface area of ​​0.42 to 1.2 m². ２ It is a spherical filler in / g, The mass ratio (A / B) of the silver nanoparticles (A) to the silver filler (B) is 0.1 to 0.

55. Bonding composition.

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