Sintered silver particles

Abstract

To provide a new sintered compact of silver particles having high denseness.SOLUTION: A sintered compact of silver particles has a denseness of 85% or more, in which the number average size of gaps is 0.50 μm or more.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a sintered body of silver particles and an electronic component having the sintered body provided between members.

Background Art

[0002] Conductive adhesives such as die bonding agents are bonding materials used in electronic components such as semiconductors, LEDs, and power semiconductors. As a bonding method, it is generally known to bond to a base material by bonding with pressure and heating, or by sintering without pressure and by heating or the like. In recent years, development of bonding materials of the non-pressure method has advanced from the viewpoints of simplicity and efficiency of the manufacturing process.

[0003] As a bonding material of the non-pressure method, one example is a conductive adhesive containing an epoxy resin. This bonding material is used by curing the epoxy resin by low-temperature treatment, and can suppress generation of voids and improve the bonding strength with a base material (Patent Document 1). However, since the epoxy resin itself becomes a resistor, the resulting conductivity and thermal conductivity become low.

[0004] On the other hand, in recent years, development of silver particles has advanced as a bonding material not containing a thermosetting resin such as an epoxy resin. Silver particles are characterized by being easily sintered by heat treatment at a low temperature for a short time. For example, Patent Document 2 discloses a metal paste obtained by kneading a solid content composed of silver particles and a solvent, wherein the solid content is composed of silver particles containing 30% or more of silver particles having a particle size of 100 to 200 nm on a particle number basis, and further, the silver particles constituting the solid content are a metal paste in which an amine compound having a total carbon number of 4 to 8 is bonded as a protective agent. According to the metal paste, silver particles can be sintered in a low temperature range, and on top of that, a sintered body having low resistance and excellent thermal conductivity can be formed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] In the field of conductive adhesives using silver particles, in order to reduce the voids (increase the density) of the sintered body obtained by applying and sintering the conductive adhesive to a member (for example, a substrate used for an electronic component, a semiconductor chip, etc.), it is generally performed to apply pressure during sintering (the pressure is, for example, about 10 to 30 MPa). By sintering the conductive adhesive while applying pressure, the voids of the sintered body can be reduced. In addition, when there are many voids in the sintered body, problems such as insufficient mechanical strength (shear strength) or cracks and chips are likely to occur in the sintered body, which is a problem in terms of reliability. On the other hand, problems such as damage to the member coated with the conductive adhesive due to the pressure during sintering and the need for special equipment for pressure application can also be cited. Further, when forming a sintered body on a semiconductor chip having a complex structure, there is also a problem that the conductive adhesive cannot be pressurized.

[0007] Therefore, in recent years, there has been a demand for a sintered body with high density even without applying pressure during the sintering of silver particles.

[0008] Under such circumstances, the main object of the present invention is to provide a novel sintered body made of silver particles and having high density. Further, it is also an object of the present invention to provide an electronic component having the sintered body between members. [Means for Solving the Problems]

[0009] The present inventors have conducted intensive studies to solve the above problems. As a result, by using relatively small silver particles having an average particle diameter within a predetermined range and relatively large silver particles having an average particle diameter within a predetermined range, and setting the average particle diameters of the large silver particles and the small silver particles in a specific relationship, it has been found that a novel sintered body having a high density of 85% or more and having voids of a predetermined size can be suitably produced. The present invention has been completed by further studies based on such findings.

[0010] That is, the present invention provides an invention in the following aspects. Item 1. A sintered body of silver particles, wherein the sintered body has a density of 85% or more, and the sintered body has an average size of the number of voids of 0.50 μm or more. Item 2. The sintered body according to Item 1, having a thickness of 200 μm or less. Item 3. The sintered body according to Item 1 or 2, wherein the area of the sintered body in plan view is 50 mm 2 or less. Item 4. The sintered body according to any one of Items 1 to 3, having a specific resistance value of 3.5 μΩ·cm or less. Item 5. The sintered body according to any one of Items 1 to 4, having a shear strength of 70 MPa or more. Item 6. An electronic component in which members are joined by the sintered body according to any one of Items 1 to 5.

Advantages of the Invention

[0011] According to the present invention, a novel sintered body of silver particles having a high density can be provided. Specifically, a novel sintered body having a high density of 85% or more and having voids of a predetermined size can be provided. Further, according to the present invention, an electronic component having the sintered body between members can also be provided.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0013] The sintered body of the present invention is a sintered body of silver particles, characterized in that the density is 85% or more and the average size of the number of voids is 0.50 μm or more. The sintered body of the present invention is a novel sintered body having a density and an average number size of voids equal to or more than a predetermined value. As will be described later, a sintered body having such a specific density and an average number size of voids can be suitably manufactured by adopting the manufacturing method described later.

[0014] Hereinafter, the sintered body of silver particles of the present invention and an electronic component provided with the sintered body between members will be described in detail. In this specification, numerical values connected by "~" mean a numerical range including the numerical values before and after "~" as a lower limit value and an upper limit value. When a plurality of lower limit values and a plurality of upper limit values are separately described, any lower limit value and upper limit value can be selected and connected by "~".

[0015] 1. Sintered body The sintered body of the present invention is a sintered body of silver particles. Specifically, it is obtained by sintering a composition containing silver particles and a solvent (used as a conductive adhesive). A preferred manufacturing method of the sintered body of the present invention will be described later.

[0016] The sintered body of the present invention has a relative density of 85% or more and an average size of the number of voids of 0.50 μm or more. Since the sintered body of the present invention is a sintered body of silver particles, voids exist inside the sintered body, and the relative density is less than 100%. The relative density of the sintered body of the present invention may be 87% or more, or may be 90% or more. Further, the average size of the number of voids is preferably about 0.50 to 1.00 μm, more preferably about 0.50 to 0.95 μm. The measuring methods for the relative density and the average size of the number of voids of the sintered body of the present invention are as follows.

[0017] <Relative density> First, prepare a substrate with electroless silver plating of 0.5 μm applied on a copper plate. On the substrate (the surface where the silver plating is formed), uniformly apply a composition of silver particles and a solvent (conductive adhesive: a silver particle dispersion liquid of 90% by mass of silver particles and 10% by mass of texanol) so that the coating film thickness becomes 50 μm. Further, on the coating film, laminate a silicon wafer (size 2 mm × 2 mm) with gold plating applied on the back surface (the surface in contact with the conductive adhesive) to obtain a laminate. Next, using a dryer (circulating type), heat the obtained laminate under sintering conditions of a predetermined sintering temperature (200 °C or 250 °C) for 60 minutes so that each conductive adhesive between the substrate and the silicon wafer is sintered, and produce a laminate in which the substrate and the silicon wafer are joined via the sintered body. Next, embed the sintered body together with the laminate in an epoxy resin (for example, manufactured by Buehler), and let it stand for 24 hours to cure the resin. Next, cut the resin-embedded laminate with a precision low-speed cutting machine (for example, TechCut4 manufactured by ALLIED), and perform cross-section milling by ion milling (for example, IM4000PLUS manufactured by Hitachi High-Technologies Corporation). Note that the cross-section milling is performed at a discharge voltage of 1.5 kV, an acceleration voltage of 6 kV, and an argon gas flow rate of 0.07 cm 3It is carried out by irradiating an ion beam with a swing of / min and ±30°. The cross-section of the sintered body obtained by cross-section milling is observed with a scanning electron microscope to obtain an SEM image. For the observation, the SED mode (secondary electron detector) is used, and a range of 60 μm in width is observed at an acceleration voltage of 20 kV and a magnification of 2000 times. Regarding the vertical direction of the SEM image, the range is set to be 10 μm or more and 200 μm or less in the vertical width of the silver sintered layer. This is because if the silver sintered layer is less than 10 μm, the mechanical strength may be impaired due to the characteristics of the joined body, and if it exceeds 200 μm, the bulk of the laminate becomes high, so it is assumed that outgassing during sintering does not occur uniformly, which is disadvantageous from the viewpoint of reliability. The density is calculated by converting the obtained SEM image into a binary image with black and white two-tone using binarization software (Image j), and obtaining it using the following relational expression. Apparent density (%) = Sintered silver area (number of white pixels) ÷ Total area of sintered body {Sintered silver area (number of white pixels) + Void area (number of black pixels)} × 100

[0018] <Measurement of voids> Regarding the SEM image of the sintered body obtained in the same manner as the measurement of the <apparent density> above and the binarized SEM image using Image j, image processing is performed using image analysis type particle size distribution measurement software (Macview) manufactured by Mountech Co., Ltd. (by automatically reading the color difference and analyzing the void portion of the binarized image as particles). Assuming that the voids in the sintered body are spherical, the number-average size of the voids is calculated. At this time, the specific surface area of the sintered body can be calculated from the surface area per unit volume of the spherical shape. Note that the void portion is different from voids and cracks, and is the pore portion generated by outgassing and particle growth. The pore portion is assumed to have a diameter of 50 nm or more and 10 μm or less. Holes with a size of 10 μm or more are called voids and cracks and are excluded from the conversion as the void portion.

[0019] The specific surface area of the voids of the sintered body of the present invention is preferably about 0.15 to 0.80 μm 2 more preferably about 0.18 to 0.75 μm 2 or so.

[0020] In addition, the shear strength of the sintered body of the present invention is preferably 70 MPa or more, more preferably 72 MPa or more. The upper limit of the shear strength is, for example, 200 MPa or less. The method for measuring the shear strength of the sintered body is as follows, and specifically, it is measured by the method described in the examples.

[0021] <Shear strength> In the same manner as the above-mentioned <density>, nine laminated bodies in which the base material and the silicon wafer are joined via the sintered body are produced. For each of the obtained laminated bodies, at room temperature, using a bond tester (for example, SS30-WD manufactured by Nishishin Shoko Co., Ltd.), a load is applied to the sintered body under the condition of 0.120 mm / s, and a dice shear test of each laminated body is carried out to measure the maximum load at the time of fracture. The shear strength value is obtained by dividing the maximum load thus obtained by the bonding area. The measurement result is the average value of the nine gold-plated silicon wafers for which the shear strength was measured.

[0022] In addition, the specific resistance value of the sintered body of the present invention is preferably 3.5 μΩ·cm or less, more preferably 3.2 μΩ·cm or less, and even more preferably 3.0 μΩ·cm or less. The lower limit of the specific resistance value is, for example, 2.0 μΩ·cm or more. The method for measuring the specific resistance value of the sintered body is as follows, and specifically, it is measured by the method described in the examples.

[0023] <Specific resistance value> A sintered body with a thickness of 50 μm is prepared. Next, the resistance value of the sintered body is measured at room temperature with a resistance meter (for example, HIOKI RM3548), and the specific resistance (volume resistance) value is obtained from the value measured with a micrometer for the actual film thickness. The specific resistance value is the average value of the values measured at four locations of the sintered body.

[0024] The thickness of the sintered body of the present invention can be appropriately designed according to the use of the sintered body. For example, it is 200 μm or less, preferably 150 μm or less, and more preferably 100 μm or less. The lower limit of the thickness of the sintered body is preferably 10 μm. The area of the sintered body in plan view of the present invention can also be appropriately designed according to the use of the sintered body, but preferably 25 mm 2Hereinafter, more preferably 16 mm 2 is as follows. The lower limit of the area is, for example, 1 mm 2 or more.

[0025] The method for manufacturing the sintered body of the present invention is not particularly limited as long as a sintered body satisfying the above-mentioned density and the average size of the number of voids is manufactured. A preferred method for manufacturing the sintered body of the present invention will be described below.

[0026] 2. Method for manufacturing a sintered body The sintered body of the present invention can be manufactured by sintering silver particles. More specifically, it can be manufactured by sintering a composition containing silver particles and a solvent.

[0027] The silver particles are particles containing silver. From the viewpoint of suitably manufacturing the sintered body of the present invention, the silver particles include silver particles A and silver particles B having different average particle diameters. The average particle diameter of silver particles A is preferably in the range of 50 to 500 nm. Further, the average particle diameter of silver particles B is preferably in the range of 0.5 to 5.5 μm. Furthermore, it is preferable that the average particle diameter of silver particles B satisfies the relationship of 5 to 11 times the average particle diameter of silver particles A. That is, for example, when the average particle diameter of silver particles A is 50 nm, the lower limit value, the average particle diameter of silver particles B is preferably in the range of 0.5 to 0.55 μm. Also, for example, when the average particle diameter of silver particles A is 500 nm, the upper limit value, the average particle diameter of silver particles B is preferably in the range of 2.5 to 5.5 μm.

[0028] From the viewpoint of suitably manufacturing the sintered body of the present invention, the average particle diameter of silver particles A is preferably in the range of 50 to 500 nm. Regarding the lower limit, preferably 60 nm or more can be mentioned, and regarding the upper limit, preferably 300 nm or less, more preferably 250 nm or less, and still more preferably 200 nm or less can be mentioned. Preferred ranges include 50 to 300 nm, 50 to 250 nm, 50 to 200 nm, 60 to 300 nm, 60 to 250 nm, 60 to 200 nm, and the like.

[0029] From the perspective of preferably manufacturing the sintered body of the present invention, the average particle diameter of silver particles B is preferably in the range of 0.5 to 5.5 μm. However, from the perspective of more preferably achieving the effects of the present invention, the lower limit is preferably 0.6 μm or more, and the upper limit is preferably 3.0 μm or less, more preferably 2.5 μm or less, and even more preferably 2.0 μm or less. Preferred ranges include 0.5 to 3.0 μm, 0.5 to 2.5 μm, 0.5 to 2.0 μm, 0.6 to 3.0 μm, 0.6 to 2.5 μm, and 0.6 to 2.0 μm.

[0030] In the present invention, the average particle diameter of silver particles is the volume-based average particle diameter measured for 200 randomly selected particles using image analysis software (for example, Macview (manufactured by Mountech)) for SEM images. For observation, the SED mode (secondary electron detector) is used, the acceleration voltage is 20 kV, and the observation magnification is 5000 to 30000 times, and a range with a horizontal width of 1 to 20 μm is observed. Regarding the vertical direction of the SEM image, the width is such that it contains 200 or more (usually about 200 to 300) silver particles in the range with a horizontal width of 1 to 20 μm. Also, the volume-based average particle diameter is a value measured assuming that the particles observed in the SEM image are spherical with their diameters. The specific measurement method is as described in the examples.

[0031] From the perspective of preferably manufacturing the sintered body of the present invention, in the silver particles, it is preferable that the average particle diameter of silver particles B satisfies the relationship of 5 to 11 times the average particle diameter of silver particles A, more preferably satisfies the relationship of 8 to 11 times, and even more preferably satisfies the relationship of 9 to 11 times.

[0032] In the silver particles, the mass ratio of silver particle A to silver particle B (silver particle A: silver particle B) is preferably in the range of 1:9 to 9:1, more preferably in the range of 7:3 to 3:7, and even more preferably in the range of 6:4 to 4:6. Note that the silver particles mainly contain silver particle A and silver particle B, and the total content thereof is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, particularly preferably 98% by mass or more, and may be 100% by mass.

[0033] The silver particles may contain silver particles having a particle diameter of less than 50 nm. However, from the viewpoint of suitably manufacturing the sintered body of the present invention, the proportion of silver particles having a particle diameter of less than 50 nm is, for example, 30% or less, preferably 20% or less, more preferably 10% or less based on the number of silver particles. Similarly, the silver particles may contain silver particles having a particle diameter exceeding 5.5 μm. The proportion of silver particles having a particle diameter exceeding 5.5 μm is, for example, 30% or less, preferably 20% or less, more preferably 10% or less based on the number of silver particles. Here, the particle diameter refers to the volume-based particle diameter, which is calculated by the above-described particle diameter measurement method. The number ratio of the corresponding particles is measured from among 200 silver particles by image analysis software (Macview).

[0034] Further, it is preferable that a plurality of exothermic peaks are observed in the range of 120 to 250°C in the thermogravimetric differential thermal analysis for the silver particles. Specifically, it is preferable that at least one (usually one) exothermic peak is observed between 120 and 150°C and at least one (usually one or two) exothermic peak is observed between 160 and 250°C in the thermogravimetric differential thermal analysis. Also, it is preferable that the weight loss rate of the dry powder of the silver particles is 1.5% by weight or less, more preferably 0.05 to 1.3% by weight when heated from 30°C to 500°C by thermogravimetric differential thermal analysis. The method of thermogravimetric differential thermal analysis is as follows.

[0035] <Thermogravimetric Differential Thermal Analysis (TG-DTA)> First, prepare air-dried silver particles. For example, when obtaining and analyzing silver particles from a conductive adhesive, for each 1 g of the conductive adhesive, add 2 g of methanol and disperse well, then filter out the silver particles and air-dry them to obtain a dry powder of silver particles for analysis. Measure the TG-DTA of the dry powder of silver particles using a thermogravimetric differential thermal analyzer (for example, HITACHI G300 AST-2). The measurement conditions are: atmosphere: air, measurement temperature: 30 to 500 °C, heating rate: 10 °C / min. From the obtained TG-DTA chart, obtain the exothermic peak caused by the bonding of silver particles in the TG-DTA analysis and the weight loss rate when heated from 30 °C to 500 °C by thermal analysis.

[0036] The silver content in the silver particles is preferably 95% by mass or more, more preferably 98% by mass or more.

[0037] From the viewpoint of preferably manufacturing the sintered body of the present invention, it is preferable to perform surface treatment on the silver particles. That is, the silver particles are preferably surface-treated silver particles.

[0038] More specifically, in the silver particles, it is preferable that an amine compound is attached to the surface of silver particle A. Also, an amine compound may be attached to the surface of silver particle B. The amine compound can adhere to the surface of the silver particles and form a protective layer. In the silver particles, it is preferable to attach the amine compound so as to set the average particle diameter within the specific range.

[0039] The amine compound is not particularly limited, but from the viewpoint of more preferably achieving the effects of the present invention, an alkylamine is preferable. The alkylamine is not particularly limited, but preferably an alkylamine having 3 or more and 18 or less carbon atoms in the alkyl group, more preferably an alkylamine having 4 or more and 12 or less carbon atoms in the alkyl group.

[0040] Preferred specific examples of the alkylamine include ethylamine, n-propylamine, isopropylamine, 1,2-dimethylpropylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, isoamylamine, tert-amylamine, 3-pentylamine, n-amylamine, n-hexylamine, n-heptylamine, n-octylamine, 2-octylamine, 2-ethylhexylamine, n-nonylamine, n-aminodecane, n-aminoundecane, n-dodecylamine, n-tridecylamine, 2-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine, n-oleylamine, N-ethyl-1,3-diaminopropane, N,N-diisopropylethylamine, N,N-dimethylaminopropane, N,N-dibutylaminopropane, N,N-dimethyl-1,3-diaminopropane, N,N-diethyl-1,3-diaminopropane, N,N-diisobutyl-1,3-diaminopropane, N-lauryl diaminopropane, and the like. Further, dibutylamine which is a secondary amine and cyclopropylamine, cyclobutylamine, cyclopropylamine, cyclohexylamine, cycloheptylamine, cyclooctylamine and the like which are cyclic alkylamines can also be exemplified. Among these, from the viewpoint of more suitably exhibiting the effects of the present invention, n-propylamine, isopropylamine, cyclopropylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, cyclobutylamine, n-amylamine, n-hexylamine, cyclohexylamine, n-octylamine, 2-ethylhexylamine, n-dodecylamine, n-oleylamine, N,N-dimethyl-1,3-diaminopropane, N,N-diethyl-1,3-diaminopropane are preferred, and n-butylamine, n-hexylamine, cyclohexylamine, n-octylamine, n-dodecylamine, N,N-dimethyl-1,3-diaminopropane, N,N-diethyl-1,3-diaminopropane are more preferred. The amine compound may be used alone or in combination of two or more.

[0041] The amount of the amine compound attached to the silver particles is not particularly limited. Assuming the mass of the silver particles is 100% by mass, it is preferably 1.5% by mass or less, more preferably 1.3% by mass or less. Regarding the lower limit, it is preferably 0.05% by mass or more. Similarly, for the amount of the amine compound attached to silver particles A and B, assuming the masses of silver particles A and B are 100% by mass respectively, it is preferably 1.5% by mass or less, more preferably 1.3% by mass or less. Regarding the lower limit, it is preferably 0.05% by mass or more. The content of the amine compound attached to the silver particles can be measured by thermogravimetric differential thermal analysis.

[0042] In addition, fatty acids, hydroxy fatty acids, etc. may adhere to the surface of the silver particles. The fatty acids are not particularly limited, but preferably fatty acids having 3 to 18 carbon atoms in the alkyl group, more preferably fatty acids having 4 to 18 carbon atoms in the alkyl group. Preferable specific examples of the fatty acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, 2-ethylhexanoic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, α-linolenic acid, etc. In addition, specific examples of the fatty acids also include cyclic alkyl carboxylic acids such as cyclohexanecarboxylic acid. Further, as the hydroxy fatty acid, a compound having 3 to 24 carbon atoms and having one or more (for example, one) hydroxyl groups can be used. Examples of the hydroxy fatty acid include 2-hydroxydecanoic acid, 2-hydroxydodecanoic acid, 2-hydroxytetradecanoic acid, 2-hydroxyhexadecanoic acid, 2-hydroxyoctadecanoic acid, 2-hydroxyicosanoic acid, 2-hydroxydocosanoic acid, 2-hydroxytricosanoic acid, 2-hydroxytetracosanoic acid, 3-hydroxyhexanoic acid, 3-hydroxyoctanoic acid, 3-hydroxynonanoic acid, 3-hydroxydecanoic acid, 3-hydroxyundecanoic acid, 3-hydroxydodecanoic acid, 3-hydroxytridecanoic acid, 3-hydroxytetradecanoic acid, 3-hydroxyhexadecanoic acid, 3-hydroxyheptadecanoic acid, 3-hydroxyoctadecanoic acid, ω-hydroxy-2-decenoic acid, ω-hydroxypentadecanoic acid, ω-hydroxyheptadecanoic acid, ω-hydroxyicosanoic acid, ω-hydroxydocosanoic acid, 6-hydroxyoctadecanoic acid, ricinoleic acid, 12-hydroxystearic acid, [R-(E)]-12-hydroxy-9-octadecenoic acid, etc. Among them, hydroxy fatty acids having 4 to 18 carbon atoms and having one hydroxyl group at a position other than the ω-position (especially the 12-position) are preferable, and ricinoleic acid and 12-hydroxystearic acid are more preferable. The fatty acids and hydroxy fatty acids may each be used alone or in combination of two or more.

[0043] In the case of silver particles, the amount of fatty acid or hydroxy fatty acid attached is also adjusted as appropriate, similar to the amine compound. The specific amount of fatty acid or hydroxy fatty acid attached is not particularly limited, but assuming the mass of the silver particles is 100% by mass, it is preferably 1.5% by mass or less, more preferably 1.3% by mass or less, and the lower limit is preferably 0.01% by mass or more. Similarly, for the amount of fatty acid or hydroxy fatty acid attached to silver particles A and B, assuming the mass of silver particles A and B is 100% by mass respectively, it is preferably 1.5% by mass or less, more preferably 1.3% by mass or less, and the lower limit is preferably 0.01% by mass or more. The content of fatty acid and hydroxy fatty acid attached to the silver particles can be measured by differential thermal analysis.

[0044] Note that the amine compound, fatty acid, and hydroxy fatty acid may be used in combination, or other compounds different from these may be attached to the surface of the silver particles. It is particularly preferable that an amine compound is attached to the surface of the silver particles.

[0045] Method for manufacturing silver particles An example of the method for producing silver particles is shown below.

[0046] First, prepare a composition for producing silver particles (a composition for preparing silver particles). Specifically, prepare a silver compound that serves as a raw material for silver particles, and, if necessary, an amine compound or the like to be attached to the surface of the silver particles, and a solvent. From the viewpoint of more preferably achieving the effects of the present invention, preferable silver compounds include silver nitrate, silver oxalate, etc., and silver oxalate is particularly preferable. Note that as the solvent, the same solvents as those exemplified as the solvents to be blended in the composition described later are exemplified. Next, mix these components to obtain a composition for preparing silver particles. The ratio of each component in the composition is adjusted as appropriate. For example, the content of silver oxalate in the composition is preferably about 20 to 70% by mass based on the total amount of the composition. Also, when an amine compound is to be attached to the surface of the silver particles, the content of the amine compound is preferably about 5 to 55% by mass based on the total amount of the composition. Also, when a fatty acid is to be attached to the surface of the silver particles, the content of the fatty acid is preferably about 0.1 to 20% by mass based on the total amount of the composition. When a hydroxy fatty acid is to be attached to the surface of the silver particles, the content of the hydroxy fatty acid is preferably about 0.1 to 15% by mass based on the total amount of the composition.

[0047] Note that it is also possible to once synthesize silver particles using a composition for preparing silver particles adjusted such that the content of the amine compound or the like is outside the above range, and then adjust (substitute the amine compound) the type and amount of attachment of the amine compound or the like to have the above physical properties by the method described later.

[0048] Also, the mixing means of each component is not particularly limited, and for example, it can be mixed with a general-purpose device such as a mechanical stirrer, a magnetic stirrer, a vortex mixer, a planetary mill, a ball mill, a three-roll mill, a line mixer, a planetary mixer, a dissolver, etc. In order to avoid the temperature of the composition rising due to the influence of the heat of dissolution, frictional heat, etc. during mixing and the start of the thermal decomposition reaction of the silver particles, it is preferable to mix while suppressing the temperature of the composition to, for example, 60°C or lower, particularly 40°C or lower.

[0049] Next, the composition for preparing silver particles is subjected to a reaction, usually a reaction by heating, in a reaction vessel, whereby a thermal decomposition reaction of the silver compound occurs and silver particles are generated. In carrying out the reaction, the composition may be introduced into a pre-heated reaction vessel, or the composition may be heated after being introduced into the reaction vessel.

[0050] The reaction temperature may be any temperature at which the thermal decomposition reaction proceeds and silver particles are generated, for example, about 50 to 250°C. Also, the reaction time may be appropriately selected according to the desired size of the average particle diameter and the composition of the composition accordingly. Examples of the reaction time include, for example, 1 minute to 100 hours.

[0051] Since the silver particles generated by the thermal decomposition reaction are obtained as a mixture containing unreacted raw materials, it is preferable to purify the silver particles. Examples of the purification method include a solid-liquid separation method, a precipitation method using the specific gravity difference between the silver particles and unreacted raw materials such as an organic solvent, etc. Examples of the solid-liquid separation method include methods such as filter filtration, centrifugation, cyclone type, or decanter. In order to facilitate handling during purification, the mixture containing silver particles may be diluted with a low-boiling solvent such as acetone or methanol to adjust its viscosity.

[0052] By adjusting the composition and reaction conditions of the composition for manufacturing silver particles, the average particle diameter of the obtained silver particles can be adjusted.

[0053] Method for substituting and adjusting an amine compound on the surface of silver particles Using the above method, once synthesized silver particles (with an amine compound attached to the surface) are prepared and dispersed in a solvent. Examples of the solvent are the same as those exemplified as the solvent to be blended in the composition described later. Next, another amine compound is added in the range of 0.1 to 5 times the mass of the silver particles, and the mixture is subjected to a step of stirring at room temperature to 80°C for 1 minute to 24 hours, whereby the type of the amine compound attached to the surface of the silver particles can be replaced or the attached amount can be adjusted. The silver particles with the amine compound replaced can be recovered by the above-mentioned solid-liquid separation method or the like.

[0054] In manufacturing the sintered body of the present invention, by using a composition of silver particles and a solvent, the fluidity of the silver particles is enhanced, and it becomes easier to place the silver particles at a desired location.

[0055] The solvent is not particularly limited as long as it can disperse silver particles, but it preferably contains a polar organic solvent. Examples of the polar organic solvent include ketones such as acetone, acetylacetone, and methyl ethyl ketone; ethers such as diethyl ether, dipropyl ether, dibutyl ether, tetrahydrofuran, and 1,4-dioxane; diols such as 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,2-hexanediol, 1,6-hexanediol, 1,2-pentanediol, 1,5-pentanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol, 1,2-octanediol, 1,8-octanediol, and 2-ethyl-1,3-hexanediol; glycerol; linear or branched alcohols having 1 to 5 carbon atoms, cyclohexanol, alcohols such as 3-methoxy-3-methyl-1-butanol and 3-methoxy-1-butanol; fatty acid esters such as ethyl acetate, butyl acetate, ethyl butyrate, ethyl formate, and texanol;Polyethylene glycol, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 3-methoxybutyl acetate, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, ethylene glycol monohexyl ether, ethylene glycol monooctyl ether, ethylene glycol mono-2-ethylhexyl ether, ethylene glycol monobenzyl ether, diethylene glycol monomethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol monohexyl ether, diethylene glycol mono-2-ethylhexyl ether, polypropylene glycol, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monopropyl ether, tripropylene glycol monobutyl ether and other glycols or glycol ethers; N,N-dimethylformamide; dimethyl sulfoxide; terpenes such as terpineol; acetonitrile; γ-butyrolactone; 2-pyrrolidone; N-methylpyrrolidone;Examples include N-(2-aminoethyl)piperazine and the like. Among these, from the viewpoint of more suitably exhibiting the effects of the present invention, linear or branched alcohols having 3 to 5 carbon atoms, 3-methoxy-3-methyl-1-butanol, 3-methoxy-1-butanol, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol monohexyl ether, diethylene glycol mono-2-ethylhexyl ether, terpineol, and texanol are preferred.;

[0056] In addition to the polar organic solvent, the solvent may further contain a nonpolar or hydrophobic solvent. Examples of the nonpolar organic solvent include linear, branched, or cyclic saturated hydrocarbons such as hexane, heptane, octane, nonane, decane, 2-ethylhexane, and cyclohexane; alcohols such as linear or branched alcohols having 6 or more carbon atoms; aromatic compounds such as benzene, toluene, and benzonitrile; halogenated hydrocarbons such as dichloromethane, chloroform, and dichloroethane; methyl-n-amyl ketone; methyl ethyl ketone oxime; and triacetin. Among these, saturated hydrocarbons and linear or branched alcohols having 6 or more carbon atoms are preferred, and hexane, octane, decane, octanol, decanol, and dodecanol are more preferred. The solvent can be used alone or in combination of two or more kinds.

[0057] When both a polar organic solvent and a nonpolar organic solvent are included, the ratio of the polar organic solvent is preferably 5% by volume or more, more preferably 10% by volume or more, and even more preferably 15% by volume or more, based on the total amount of the solvent. Also, it can be 60% by volume or less, 55% by volume or less, or 50% by volume or less. The solvent can also consist only of a polar organic solvent. Even when the composition containing silver particles and the solvent contains a large amount of the polar organic solvent in this way, the dispersibility of the silver particles is good.

[0058] In the composition containing silver particles and the solvent, the ratio of the solvent is not particularly limited, but is preferably 20% by mass or less, and more preferably about 5% to 15% by mass.

[0059] The content of silver particles contained in the composition containing silver particles and a solvent is preferably 80% by mass or more, more preferably 85% by mass or more.

[0060] The composition containing silver particles and a solvent can be produced by a method including a step of mixing silver particles and a solvent.

[0061] In addition, in the composition containing silver particles, in the above-described method for producing silver particles, the silver particles generated in the solvent may be used as the composition together with the solvent.

[0062] In the method for producing the sintered body of the present invention, most of the components (such as amine compounds) and solvents adhering to the surface of the silver particles are removed by the high heat during sintering, and the sintered body of the present invention is substantially composed of silver.

[0063] The sintering temperature is not particularly limited. However, from the viewpoint of favorably sintering at a low temperature while increasing the shear strength and density of the obtained sintered body, for example, it is 250°C or lower, preferably about 150°C to 250°C, more preferably about 200°C to 250°C. From the same viewpoint, the sintering time is preferably about 0.4 hours to 2.0 hours, more preferably about 0.5 hours to 1.2 hours. In the method for manufacturing the sintered body of the present invention, the silver particles include silver particles A having an average particle diameter in the range of 50 to 500 nm and silver particles B having an average particle diameter in the range of 0.5 to 5.5 μm, and the average particle diameter of the silver particles B satisfies the relationship of being 5 to 11 times the average particle diameter of the silver particles A. Thus, even without applying pressure during the sintering of the silver particles, sintering is favorably performed at a low temperature of 250°C or lower, and the sintered body of the present invention having the predetermined density and voids is favorably formed. Therefore, there is no need to apply pressure during the sintering of the silver particles. That is, the sintered body of the present invention can be suitably used for applications where no pressure is required during the sintering of the silver particles. Note that pressure may be applied during the production of the sintered body of the present invention, and the pressure in the case of applying pressure is, for example, about 10 to 30 MPa. Sintering can be performed in an atmosphere such as air, an inert gas (nitrogen gas, argon gas), etc. The sintering means is not particularly limited, and examples include an oven, a hot air drying furnace, an infrared drying furnace, laser irradiation, flash lamp irradiation, microwave, etc.

[0064] 3. Electronic component The electronic component of the present invention includes a portion where members are adhered by the sintered body of the present invention. That is, the electronic component of the present invention can be suitably manufactured by disposing the aforementioned silver particles between members of the electronic component (for example, between members included in a circuit) and sintering the silver particles to adhere the members.

[0065] As described above, since the sintered body of the present invention has a high density, the density of the sintered body is also high in the electronic component including the same. Also, the specific resistance value of the electronic component of the present invention can be made low.

Examples

[0066] The present invention will be described more specifically in the following examples, but the present invention is not limited thereto.

[0067] Details of each component used in the examples and comparative examples are as follows. · Silver oxalate ((COOAg)2) was synthesized by the method described in Patent No. 5574761. · N,N-Diethyl-1,3-diaminopropane (manufactured by Fujifilm Wako Pure Chemical Corporation) · n-Hexylamine (carbon number 6, manufactured by Fujifilm Wako Pure Chemical Corporation) · Ricinoleic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) · 1-Butanol (manufactured by Fujifilm Wako Pure Chemical Corporation) · Methanol (manufactured by Fujifilm Wako Pure Chemical Corporation) · Ethylene glycol (manufactured by Fujifilm Wako Pure Chemical Corporation) · Texanol (manufactured by Fujifilm Wako Pure Chemical Corporation)

[0068] <Synthesis of silver particles A> (1) Silver particles A1 (average particle diameter 68 nm) Into a 50 mL glass centrifuge tube containing a magnetic stir bar, ricinoleic acid (2.34 g), N,N-diethyl-1,3-diaminopropane (203 g), and 1-butanol (375 g) were added. After stirring for about 1 minute, silver oxalate (250 g) was added and stirred for about 10 minutes to obtain a composition for preparing silver particles A1. Thereafter, these glass centrifuge tubes were placed upright on a hot stirrer equipped with an aluminum block (HHE-19G-U manufactured by Koike Precision Instruments Co., Ltd.) and stirred at 40 °C for 30 minutes, and further stirred at 90 °C for 30 minutes. After allowing to cool, the magnetic stir bar was taken out, 15 g of methanol was added to each composition and stirred with a vortex mixer, and then a centrifugation operation was performed at 3000 rpm (about 1600×G) for 1 minute using a centrifuge (CF7D2 manufactured by Hitachi Koki Co., Ltd.), and the supernatant was removed by tilting the centrifuge tube. The steps of adding 15 g of methanol, stirring, centrifuging, and removing the supernatant were repeated twice to recover the silver particles.

[0069] Next, using the obtained dispersion of silver particles (methanol solution), n-hexylamine was added in an amount three times the mass of the silver particles, and the mixture was stirred at room temperature for 4 hours. After stirring, the magnetic stir bar was taken out, 15 g of methanol was added to each composition, and the mixture was stirred with a vortex mixer. Then, a centrifugation operation was performed at 3000 rpm (about 1600×G) for 1 minute using a centrifuge (CF7D2 manufactured by Hitachi Koki Co., Ltd.), and the supernatant was removed by tilting the centrifuge tube. The steps of adding 15 g of methanol, stirring, centrifuging, and removing the supernatant were repeated twice to recover silver particles A1 (average particle diameter 68 nm) in which N,N-diethyl-1,3-diaminopropane adhering to the surface of the silver particles was replaced with n-hexylamine.

[0070] (2) Silver particles A2 (average particle diameter 181 nm) Into a 50 mL glass centrifuge tube containing a magnetic stir bar, ricinoleic acid (6.25 g), N,N-diethyl-1,3-diaminopropane (203 g), and 1-butanol (187.5 g) were added and stirred for about 1 minute. Then, silver oxalate (250 g) was added and stirred for about 10 minutes to obtain a composition for preparing silver particles A1. Thereafter, these glass centrifuge tubes were placed upright on a hot stirrer equipped with an aluminum block (HHE-19G-U manufactured by Koike Seimitsu Kikai Seisakusho Co., Ltd.) and stirred at 40°C for 30 minutes, and further stirred at 90°C for 30 minutes. After cooling, the magnetic stir bar was taken out, 15 g of methanol was added to each composition, and the mixture was stirred with a vortex mixer. Then, a centrifugation operation was performed at 3000 rpm (about 1600×G) for 1 minute using a centrifuge (CF7D2 manufactured by Hitachi Koki Co., Ltd.), and the supernatant was removed by tilting the centrifuge tube. The steps of adding 15 g of methanol, stirring, centrifuging, and removing the supernatant were repeated twice to recover the silver particles.

[0071] Next, using the obtained dispersion of silver particles (methanol solution), 3 times the mass of silver particles of n-hexylamine was added, and the mixture was stirred at room temperature for 4 hours. After stirring, the magnetic stirrer was taken out, 15 g of methanol was added to each composition, and the mixture was stirred with a vortex mixer. Then, a centrifugation operation was performed at 3000 rpm (about 1600×G) for 1 minute using a centrifuge (CF7D2 manufactured by Hitachi Koki Co., Ltd.), and the supernatant was removed by tilting the centrifuge tube. The steps of adding 15 g of methanol, stirring, centrifuging, and removing the supernatant were repeated twice to recover silver particles A2 (average particle diameter 181 nm) in which N,N-diethyl-1,3-diaminopropane was substituted for n-hexylamine.

[0072] [[ID=H4]]<Silver particles B> · As silver particles B1 (average particle diameter 0.65 μm), the product name AG2-1C manufactured by DOWA Electronics Co., Ltd. was used. · As silver particles B2 (average particle diameter 1.88 μm), the product name AG3-1F manufactured by DOWA Electronics Co., Ltd. was used. <C · As silver particles B3 (average particle diameter 2.21 μm), the product name AG4-8F manufactured by DOWA Electronics Co., Ltd. was used.

[0073] For silver particles A1, A2, B1, B2, and B3, observation by a scanning electron microscope (acquisition of SEM images), measurement of the average particle diameter (volume-based average particle diameter), measurement of the particle size distribution, and measurement of TG-DTA were performed under the following conditions.

[0074] <Observation by electron microscope> For silver particles A1, A2, B1, B2, and B3, SEM images were acquired using a scanning electron microscope (SEM (JSM-IT500HR manufactured by JEOL Ltd.)). The SEM images of silver particles A1, A2, B1, B2, and B3 are shown in Figure 1, Figure 2, Figure 3, Figure 4, and Figure 5, respectively.

[0075] <Measurement of average particle diameter (volume-based average particle diameter) and particle size distribution (D10~D100)> For each SEM image (width 1 to 20 μm) obtained by the <observation with an electron microscope>, the volume-based average particle diameter and particle size distribution of 200 randomly selected particles were measured using image analysis software (MacView (manufactured by Mountech Co., Ltd.)). For the vertical direction of the SEM image, a range with a width of 1 to 20 μm is observed. Note that for the vertical direction of the SEM image, the width is such that it contains 200 or more (usually about 200 to 300) silver particles in the range of 1 to 20 μm in width. Note that the volume-based average particle diameter is a value measured assuming that the particles observed in the SEM image are spherical with that diameter. The results are shown in Table 1 and Table 2.

[0076]

Table 1

[0077]

Table 2

[0078] <Thermogravimetric differential thermal analysis (TG-DTA measurement)> TG-DTA was measured for each of silver particles A1 and A2. Specifically, first, in the same manner as <manufacture of conductive adhesive> described later, for silver particle A1 and silver particle A2, a solvent (texanol) was mixed respectively to prepare each silver particle dispersion with a concentration of 90% by mass. Next, 2 g of methanol was added to 1 g of each silver particle dispersion and dispersed well, and then the silver particles were filtered and air-dried to obtain silver particle dry powder. The TG-DTA of the obtained silver particle dry powder was measured with HITACHI G300 AST-2. The measurement conditions were: atmosphere: air, measurement temperature: 30 to 500 °C, heating rate: 10 °C / min. From the obtained TG-DTA chart, the weight loss rate when heated from 30 °C to 500 °C by thermal analysis was obtained. The results are shown in Table 3.

[0079] Further, for silver particles A1 and silver particles A2, solvents (texanol) were mixed respectively to prepare silver particle dispersions with a concentration of 90% by mass. Each silver particle dispersion was used for the measurement of the main exothermic peak in TG-DTA analysis and measured with HITACHI G300 AST-2. The measurement conditions were as follows: atmosphere: air, measurement temperature: 30 to 500 °C, heating rate: 10 °C / min. The obtained TG-DTA chart is shown in Fig. 6. The temperatures of the exothermic peaks of each silver particle in Fig. 6 are shown in Table 3.

[0080]

Table 3

[0081] <Manufacture of Conductive Adhesive> Silver particles A, silver particles B, and a solvent (texanol) were mixed to prepare a conductive adhesive so as to have the composition shown in Table 4. Specifically, first, for each of silver particles A1, silver particles A2, silver particles B1, silver particles B2, and silver particles B3, texanol equivalent to 10% by mass was added to prepare each silver particle dispersion with a concentration of 90% by mass (silver particle dispersion A1, silver particle dispersion A2, silver particle dispersion B1, silver particle dispersion B2, and silver particle dispersion B3, respectively). For mixing, a Mazelstar manufactured by Kurabo Industries Ltd. was used, and mixing was performed in the stirring priority mode twice. Next, each silver particle dispersion and texanol were mixed so as to have the composition shown in Table 4 to obtain each conductive adhesive having the composition of Example Composition 1-2 and Comparative Composition 1-4.

[0082]

Table 4

[0083] The units of the numerical values described for silver particle A, silver particle B, and the solvent in Table 4 are parts by mass. In the conductive adhesives of Example Composition 1-2 and Comparative Composition 1-4, when the number of particles was set to 100%, particles having a particle size of less than 50 nm were contained in an amount of 10% or less. For the measurement of particles with a size of less than 50 nm, for each SEM image (horizontal width 1 to 20 μm) obtained by the <Observation with an electron microscope>, using image analysis software (MacView (manufactured by Mountech Co., Ltd.)), the volume particle diameters of 200 randomly selected particles were measured, and the percentage of the number contained therein was calculated. For the vertical direction of the SEM image, the width (range of 1 to 20 μm) in which 200 or more silver particles were contained in the range of 1 to 20 μm in horizontal width was used.

[0084] <Manufacture of sintered body (sintering temperature 200 °C)> First, a substrate with electroless silver plating of 0.5 μm applied on a copper plate was prepared. A conductive adhesive (a silver particle dispersion liquid containing 90% by mass of silver particles and 10% by mass of texanol) was uniformly applied on the substrate (the surface on which the silver plating was formed) so that the coating thickness was 50 μm. Further, on the coating film, a silicon wafer (size 2 mm × 2 mm) with gold plating applied on the back surface (the surface in contact with the conductive adhesive) was laminated to obtain a laminate. Next, using a dryer (circulation type), the obtained laminate was heated under sintering conditions of a predetermined sintering temperature (200 °C or 250 °C) for 60 minutes, and each conductive adhesive between the substrate and the silicon wafer was sintered, and 9 laminates in which the substrate and the silicon wafer were joined via a sintered body were obtained.

[0085] Also, for reference, silver particle dispersion liquid A1, silver particle dispersion liquid A2, silver particle dispersion liquid B1, and silver particle dispersion liquid B2 prepared in the above <Manufacture of conductive adhesive> (each silver particle dispersion liquid in which 10% by mass equivalent of texanol was added to silver particles A1, silver particles A2, silver particles B1, and silver particles B2, and the concentration was set to 90% by mass) were used to manufacture sintered bodies in the same manner as conductive adhesives (Comparative Examples 5 to 8 as shown in Table 5).

[0086] Various physical properties of each sintered body obtained from the conductive adhesives of Example Composition 1-2 and Comparative Composition 1-8 were measured under the following measurement conditions.

[0087] <Apparent density of the sintered body> Each sintered body was resin-embedded with epoxy resin (manufactured by Buehler) for each of the above-mentioned laminates and allowed to stand for 24 hours to cure the resin. Next, the resin-embedded sintered body was cut with a precision low-speed cutting machine TechCut4 (manufactured by Allied), and cross-section milling was performed for 3 hours by ion milling (IM4000PLUS, manufactured by Hitachi High-Technologies Corporation). The cross-section milling was carried out by irradiating an ion beam with a discharge voltage of 1.5 kV, an acceleration voltage of 6 kV, an argon gas flow rate of 0.07 cm 3 / min, and a swing of ±30°. The cross-section of the sintered body obtained by cross-section milling was observed with a scanning electron microscope JSM-IT500HR (manufactured by JEOL Ltd.) to obtain an SEM image. For the observation, the SED mode (secondary electron detector) was used, and a range of 60 μm in width was observed at an acceleration voltage of 20 kV and a magnification of 2000 times. For the vertical direction of the SEM image, the vertical width of the silver sintered layer was set to a range of 10 μm or more and 200 μm or less. The apparent density was calculated by converting the obtained SEM image into a binary image with two shades of white and black using binarization software "image J" and obtaining it from the following relational expression. The measurement results of the apparent density are shown in Table 5. Apparent density (%) = Sintered silver area (number of white pixels) ÷ Total area of the sintered body {Sintered silver area (number of white pixels) + Pore area (number of black pixels)} × 100

[0088] <Mechanical strength (shear strength) of the sintered body> For the obtained laminate, at room temperature, using a bond tester (SS30-WD manufactured by Nishi-Shin Shoko Co., Ltd.), a load was applied to the sintered body under the condition of 0.120 mm / s, and a die shear test was performed on each laminate to measure the maximum load at the time of fracture. The shear strength value was obtained by dividing the maximum load thus obtained by the bonding area. The measurement results are the average values of 9 gold-plated silicon wafers for which the shear strength was measured. The measurement results of the shear strength are shown in Table 5.

[0089] <Specific resistance value of the sintered body> A conductive adhesive (a silver particle dispersion liquid containing 90 mass% silver particles and 10 mass% texanol) was uniformly applied onto a polyimide film to a size of 2 mm × 60 mm with a coating thickness of 50 μm, and then fired at a predetermined temperature (200 °C or 250 °C) for 60 minutes to obtain a sintered body. Next, the resistance value of the sintered body was measured at room temperature using a two-terminal measurement method with a resistance meter (HIOKI RM3548), and the specific resistance (volume resistance) value was obtained from the value measured for the actual film thickness with a micrometer. Note that this specific resistance value is the average value of the values measured at four locations on the sintered body. The measurement results of the specific resistance values are shown in Table 5.

[0090]

Table 5

[0091] <Void of the sintered body (sintering temperature 200 °C)> For each SEM image binarized using "Image j" obtained by the <observation with an electron microscope>, image processing was performed using image analysis type particle size distribution measurement software (Macview) (manufactured by Mountech Co., Ltd.) (by automatically reading the color difference, the void portions of the binarized image were analyzed as particles), and the number average size and specific surface area of the voids of the sintered body were calculated. The results are shown in Table 6. Note that the number average size referred to here is the result of analysis with image analysis software (Macview) assuming that the voids are spheres, and the specific surface area value was obtained by calculating the surface area per unit volume of the said spheres.

[0092]

Table 6

[0093] <Manufacture of the sintered body (sintering temperature 250 °C)> Next, for each of the conductive adhesives of Example Compositions 1 and 2, which had a density of 85% or more and a number-average void size of 0.50 μm or more when sintered at a sintering temperature of 200°C, sintered bodies were obtained in the same manner as in <Production of Sintered Body (Sintering Temperature 200°C)>, except that the sintering temperature was increased to an even higher temperature of 250°C. Furthermore, the shear strength, density, and resistivity of the obtained sintered bodies were measured in the same manner as in <Mechanical Strength (Shear Strength) of Sintered Body>, <Density of Sintered Body>, and <Resistivity of Sintered Body>. The results are shown in Table 7.

[0094] [Table 7]

[0095] <Porosity in sintered body (sintering temperature 250°C)> Similar to the above-mentioned <Observation by electron microscope>, SEM images of each sintered body obtained in <Production of sintered body (sintering temperature 250°C)> were obtained, and each SEM image was processed using image analysis particle size distribution measurement software (Macview) (manufactured by Mountech Co., Ltd.) (the voids in the binarized image were analyzed as particles by automatically reading the color difference), and the number-average size and specific surface area of the voids in the sintered body were calculated. The results are shown in Table 8. Note that the number-average size here was analyzed using image analysis software (Macview) assuming the voids to be spheres, and the specific surface area was calculated to be the surface area per unit volume of the spheres.

[0096] [Table 8]

Claims

1. A sintered body in a laminate joined via a sintered body of silver particles, wherein the sintered body has a density of 85% or more as measured by the following method, and the sintered body has an average size of the number of voids of 0.50 μm or more and 1.00 μm or less as measured by the following method. <Density> The sintered body is resin-embedded with an epoxy resin together with the laminate and left standing for 24 hours to cure the resin. Next, the resin-embedded laminate is cut with a precision low-speed cutting machine, and cross-section milling is performed by ion milling. The cross-sectional milling is carried out by irradiating an ion beam with a swing of ±30° at a discharge voltage of 1.5 kV and an acceleration voltage of 6 kV, with an argon gas flow rate of 0.07 cm 3 / min. The cross-section of the sintered body obtained by the cross-section milling is observed with a scanning electron microscope to obtain an SEM image. For the observation, the SED mode (secondary electron detector) is used, and the observation is carried out at an acceleration voltage of 20 kV, in a field of view of 2000 times, in a range of 60 μm in width and in a range of 10 μm or more and 200 μm or less in length. The density is calculated by converting the obtained SEM image into a binary image with binarization software so that the shades are converted into a two-tone image of white and black, and is obtained by the following relational expression. Density (%) = Sintered silver area (number of white pixels) ÷ Total area of sintered body {Sintered silver area (number of white pixels) + Void area (number of black pixels)} × 100 <Measurement of voids> For the SEM image of the sintered body binarized using binarization software obtained in the same manner as the measurement of <Density> above, image processing is performed using image analysis formula particle size distribution measurement software (by automatically reading the color difference, the void portion of the binarized image is analyzed as particles), assuming that the voids of the sintered body are spherical, and the average size of the number of those voids is calculated. Note that the void portion is different from voids and cracks, and is a pore portion generated by outgassing or particle growth, and the pore portion has a diameter of 50 nm or more and 10 μm or less.

2. The sintered body according to claim 1, having a thickness of 200 μm or less.

3. The area when the sintered body is viewed in plan is 50 mm 2 or less. The sintered body according to claim 1 or 2.

4. The sintered body according to any one of claims 1 to 3, having a specific resistance value of 3.5 μΩ·cm or less. [[ID= 16]]

5. The sintered body according to any one of claims 1 to 4, having a shear strength of 70 MPa or more.

6. An electronic component in which members are joined by the sintered body according to any one of claims 1 to 5.

Images