Paste composition and use thereof

Abstract

The present invention relates to a paste composition comprising: silver-containing metal nanoparticles (A) that have a particle size of less than 1 μm; silver particles (B) that have a particle size of not less than 1 μm; a silver ion scavenger (C); and an organic solvent (D), wherein the median particle size (D50) of the silver-containing metal nanoparticles (A) is 30-600 nm, and the median particle size (D50) of the silver particles (B) is 1.5-20 μm.

Description

Paste composition and its uses

[0001] This invention relates to a paste composition used as a bonding material in the field of electronics, and to the same applications.

[0002] In the field of electronics, where electronic components such as power semiconductors are mounted, solder and brazing materials have traditionally been used as bonding materials to join chips to electronic substrates, or to join electronic substrates to coolers (heat sinks). As an alternative to these bonding materials, silver paste (silver die attach paste), in which silver particles are dispersed as a filler in an organic solvent (or organic vehicle), has been developed with the aim of reducing environmental impact and improving heat dissipation.

[0003] Silver die attach pastes are classified into conductive adhesives, which consist of a mixture of silver filler, binder resin, and organic solvent, and silver sintering pastes, which consist only of silver filler and organic solvent without binder resin. They form a bonding layer to join components such as the aforementioned chips and electronic substrates. With conductive adhesives, the bonding layer is bonded via the binder resin, resulting in lower bonding strength and heat dissipation. On the other hand, with silver sintering pastes, the bonding layer is bonded via metallic bonding, which can improve bonding strength and heat dissipation. Recently, in the field of electronics, with the miniaturization and increased power output of devices, heat generation from devices has become a problem, leading to increased demand for silver sintering pastes with excellent heat dissipation. However, the bonding layer of silver sintering paste is rigid and brittle compared to conductive adhesives. Therefore, the bonding layer of silver sintering paste has the challenge of having relatively weak resistance to thermal expansion or contraction (thermal load) caused by changes in ambient temperature (thermal shock resistance).

[0004] Silver fillers used in silver sintering pastes often contain micro-sized silver particles, as well as nano-sized silver nanoparticles (silver fine particles). The inclusion of silver nanoparticles allows for the formation of a dense bonding layer through low-temperature sintering, improving heat dissipation and bonding strength without stressing the device during mounting (low-temperature sinterability). However, sintered bodies of silver nanoparticles tend to be too rigid, resulting in low thermal shock resistance. This can lead to the bonding layer becoming brittle and reducing bonding strength due to thermal stress caused by ambient temperature changes. Therefore, silver fillers used in silver sintering pastes often blend silver nanoparticles with micro-sized silver particles (silver powder).

[0005] Given the above background, in silver sintering paste, a technique is known that uses multiple types (two or more) of silver particles with different particle sizes in combination as a silver filler, and precisely adjusts the mixing ratio to achieve both low-temperature sinterability and thermal shock resistance.

[0006] For example, Japanese Patent Publication No. 2021-138991 (Patent Document 1) discloses a bonding material comprising a metal small particle powder with an average primary particle diameter of 150 nm or less, a metal medium particle powder with a volume-based cumulative 50% particle diameter (D50) of 1.1 to 4.5 μm, a metal large particle powder with a volume-based cumulative 90% particle diameter (D90) of 7 to 40 μm, and a solvent, wherein the content of the metal medium particle powder is 40% by mass or more.

[0007] WO2019 / 026799 (Patent Document 2) discloses a metal bonding composition comprising nanoparticles with a particle size of 1 to 99 nm, submicron particles with a particle size of 100 to 999 nm and / or micron particles with a particle size of 1 to 999 μm, and a solvent.

[0008] Japanese Patent Application Publication No. 2021-138991 WO2019 / 026799

[0009] However, even when attempting to achieve both low-temperature sinterability and thermal shock resistance by precisely adjusting the particle size of the silver filler, as described in Patent Documents 1 and 2, there is a distribution in the particle size of actual silver particles, as well as errors depending on the manufacturing lot. Therefore, these methods, which precisely control the particle size to achieve both low-temperature sinterability and thermal shock resistance in actual production products, were not practical.

[0010] Therefore, the object of the present invention is to provide a paste composition (silver sintering paste) that can improve the thermal shock resistance of a sintered bonding layer, even when containing silver nanoparticles (or silver-containing metal nanoparticles), and its applications.

[0011] Another object of the present invention is to provide a paste composition that can form a bonding layer with high bonding strength and thermal shock resistance even when fired at low temperatures, and to provide the same for use.

[0012] Another object of the present invention is to provide a paste composition and its applications that can form a bonding layer with high bonding strength, heat dissipation, and thermal shock resistance even when fired at low temperatures.

[0013] The present inventors have conducted diligent studies to achieve the above objectives and have found that the particle diameter is less than 1 μm and the central particle diameter (D ５０ Silver-containing metal nanoparticles (A) with a diameter of 30 to 600 nm, and a particle diameter of 1 μm or more, with a central particle diameter (D ５０ We discovered that by combining silver particles (B) having a diameter of 1.5 to 20 μm, a silver ion scavenger (C), and an organic solvent (D), the thermal shock resistance of the sintered bonding layer can be improved even in a paste composition containing silver nanoparticles, thus completing the present invention.

[0014] In other words, the present invention includes the following embodiments.

[0015] Embodiment [1]: comprising silver-containing metal nanoparticles (A) having a particle diameter of less than 1 μm, silver particles (B) having a particle diameter of 1 μm or more, a silver ion scavenger (C), and an organic solvent (D), wherein the central particle diameter (D) of the silver-containing metal nanoparticles (A) ５０ The diameter is 30 to 600 nm, and the central particle diameter (D) of the silver particle (B) is 30 to 600 nm. ５０ A paste composition in which the particle size is 1.5 to 20 μm.

[0016] Embodiment [2]: The paste composition according to Embodiment [1], wherein the silver ion scavenging agent (C) is an inorganic compound having cation scavenging ability.

[0017] Embodiment [3]: The central particle size (D) of the silver ion scavenger (C). ５０ The paste composition according to embodiment [1] or [2], wherein the n is 100 to 300 nm.

[0018] Embodiment [4]: ​​The central particle diameter (D) of the silver ion scavenger (C). ５０ ) is the central particle diameter (D) of the silver-containing metal nanoparticle (A). ５０ A paste composition according to any one of the embodiments [1] to [3], wherein the ratio is 0.3 to 3 times.

[0019] Embodiment [5]: The paste composition according to any one of Embodiments [1] to [4], wherein the proportion of the silver ion scavenger (C) is 0.05 to 1 part by mass per 100 parts by mass of the silver-containing metal nanoparticles (A).

[0020] Embodiment [6]: The paste composition according to any one of Embodiments [1] to [5], wherein the mass ratio of the silver-containing metal nanoparticles (A) to the silver particles (B) is former / latter = 75 / 25 to 5 / 95.

[0021] Embodiment [7]: A paste composition according to any one of Embodiments [1] to [6], which does not contain a binder resin.

[0022] Embodiment [8]: A paste composition according to any one of Embodiments [1] to [7], which is a die attach paste.

[0023] Embodiment [9]: A method for manufacturing a laminate, comprising: a coating step of applying a paste composition according to any of Embodiments [1] to [8] onto a first member to be joined; a placement step of placing a second member to be joined on the applied paste composition; and a firing step of firing the paste composition interposed between the first member to be joined and the second member to be joined to obtain a laminate in which a bonding layer, which is a sintered body, is interposed between the first member to be joined and the second member to be joined.

[0024] Aspect

[10] : The production method according to Aspect [9], wherein in the firing step, the paste composition is fired without pressure at a firing temperature of 100 to 300°C.

[0025] Aspect

[11] : The production method according to Aspect [9], wherein in the firing step, the paste composition is fired under pressure at a firing temperature of 150 to 350°C.

[0026] Aspect

[12] : A laminate including a first member to be bonded, a second member to be bonded, and a bonding layer interposed between the first member to be bonded and the second member to be bonded, wherein the bonding layer is a sintered body of the paste composition according to any one of Aspects [1] to [8].

[0027] Aspect

[13] : The laminate according to Aspect

[12] , wherein the first member to be bonded or the second member to be bonded is a constituent member of an electronic device, and the electronic device includes a semiconductor chip having an operating temperature of 200°C or higher.

[0028] In the present application, the numerical range represented by "A to B" means "from A to B inclusive", and is used to include the numerical values A and B at both ends thereof.

[0029] In the present invention, the particle diameter is less than 1 μm, and the median particle diameter (D ５０ ) is 30 to 600 nm silver-containing metal nanoparticles (A), silver particles (B) having a particle diameter of 1 μm or more and a median particle diameter (D ５０ ) of 1.5 to 20 μm, and a silver ion scavenger (C) are combined. Therefore, even for a paste composition containing silver nanoparticles (silver sintering paste), the thermal shock resistance of the sintered bonding layer can be improved. Accordingly, even when fired at a low temperature, a bonding layer having high bonding strength, high heat dissipation and high thermal shock resistance can be formed.

[0030] Figure 1 is a graph showing the particle size distribution of silver nanoparticles and silver particles in the silver sintering paste prepared in Example 23. Figure 2 is a photograph of the evaluation sample in Example 2 observed with an X-ray transmission inspection device before the thermal shock test. Figure 3 is a photograph of the evaluation sample in Example 2 observed with an X-ray transmission inspection device after the thermal shock test. Figure 4 is a photograph of the evaluation sample in Comparative Example 1 observed with an X-ray transmission inspection device before the thermal shock test. Figure 5 is a photograph of the evaluation sample in Comparative Example 1 observed with an X-ray transmission inspection device after the thermal shock test.

[0031] [Paste Composition] The paste composition of the present invention (especially the silver sintering paste) comprises silver-containing metal nanoparticles (A) with a particle size of less than 1 μm, silver particles (B) with a particle size of 1 μm or more, a silver ion scavenger (C), and an organic solvent (D). In the paste composition of the present invention, the silver ion scavenger (C) suppresses the growth of crystal grains due to the reaction of silver-containing metal ions derived from the silver-containing metal nanoparticles (A), thereby suppressing the occurrence and propagation of defects (voids and cracks) that lead to embrittlement of the bonding layer, which is the sintered body of the paste composition. Therefore, the thermal shock resistance of the bonding layer can be improved.

[0032] In more detail, while conventional sintered bodies (bonding layers) of paste compositions containing silver nanoparticles suffered from reduced bonding strength due to inability to withstand thermal loads, the present invention successfully solves the conventional problem through the following mechanism.

[0033] (Behavior in conventional silver sintering paste) First, the mechanism by which the bonding strength of conventional silver sintering paste containing silver nanoparticles decreases under thermal load is as follows.

[0034] The bonding layer formed with silver sintering paste has a structure in which minute voids (micropores) are finely dispersed. However, after thermal loading (thermal shock) is applied to the bonding layer, these voids (micropores) aggregate and coarseen, propagating into large cavities (voids) and cracks. In other words, the bonding layer subjected to thermal loading changes into a brittle structure due to defects caused by the propagation of minute voids (micropores), leading to a decrease in bonding strength.

[0035] Furthermore, it can be inferred that the mechanism by which voids (micropores) aggregate is due to the growth of silver nanoparticle crystal grains in response to temperature changes in the bonding layer, and the movement (reconfiguration) of the silver nanoparticle crystal interfaces (grain boundaries), which leads to the aggregation of voids (micropores).

[0036] (Effects of the Paste Composition of the Present Invention) The inventors hypothesized that in conventional silver sintering paste, the growth of silver nanoparticle crystal grains, which leads to the aggregation of voids (micropores), is related to a reaction involving silver ions derived from the silver nanoparticles. Therefore, by incorporating a "silver ion scavenger (silver ion trapper)" that captures silver ions derived from silver nanoparticles into the silver sintering paste, the growth of silver nanoparticle crystal grains can be suppressed, and the aggregation of voids (micropores) that leads to defects in the silver layer can be prevented. In other words, by incorporating a silver ion scavenger (silver ion trapper) into the silver sintering paste, the aggregation of voids (micropores) that leads to the progression of defects in the silver layer can be prevented, and the embrittlement of the silver layer can be suppressed, thereby improving the thermal shock resistance.

[0037] (Composition of the paste composition) The paste composition of the present invention comprises silver-containing metal nanoparticles (A) having a particle size of less than 1 μm, silver particles (B) having a particle size of 1 μm or more, and a silver ion scavenger (C).

[0038] (A) Silver-containing metal nanoparticles Silver-containing metal nanoparticles (A) are nanoparticles formed of a silver-containing metal (a metal containing silver). The silver-containing metal may be pure silver or an alloy of silver with another metal. The other metal is not particularly limited as long as it can be alloyed with silver, but examples include Cr, Mo, W, Ni, Pd, Pt, Cu, Au, Zn, In, Sn, Pb, etc. These other metals can be used alone or in combination of two or more. Of these other metals, Cu is preferred.

[0039] The proportion of silver may be 50% by mass or more in the silver-containing metal, for example, 90% by mass or more, preferably 95% by mass or more, more preferably 97% by mass or more, more preferably 99% by mass or more, and most preferably 100% by mass (pure silver). If the proportion of silver is too low, there is a risk that the heat dissipation performance will decrease.

[0040] When the silver-containing metal is a combination of silver and another metal (particularly Cu), the proportion of the other metal is, for example, 0.01 to 10 parts by mass, preferably 0.03 to 5 parts by mass, and more preferably 0.05 to 3 parts by mass, per 100 parts by mass of silver.

[0041] Silver-containing metal nanoparticles are solidified with adjacent particles in the sintered body, but in the raw material stage before sintering, they are nanometer-sized particles.

[0042] Silver-containing metal nanoparticles (A) are particles with a smaller particle size than silver particles (B), specifically, small particles with a particle size of less than 1 μm (i.e., a group of particles in the paste composition having a particle size distribution in the range of less than 1 μm).

[0043] In other words, the maximum particle diameter (maximum primary particle diameter) of the silver-containing metal nanoparticles (A) is less than 1 μm, preferably 900 nm or less, and more preferably 800 nm or less. If the maximum particle diameter is too large, it may become difficult for the nanoparticles to penetrate the gaps between the silver particles (B).

[0044] In this application, the maximum particle size of the silver-containing metal nanoparticles (A) can be confirmed based on the particle size distribution (volume distribution) measured using a laser diffraction scattering particle size distribution analyzer.

[0045] Center particle diameter of silver-containing metal nanoparticles (A) (50% volume particle diameter) (D ５０ The central particle diameter (D) can be 30 to 600 nm, preferably 50 to 600 nm (e.g., 50 to 500 nm), and more preferably 70 to 500 nm (e.g., 70 to 400 nm). The central particle diameter (D) can be used to greatly improve bonding strength and thermal shock resistance. ５０The particle size is preferably 80 to 300 nm, more preferably 100 to 250 nm (particularly 110 to 195 nm), more preferably 120 to 200 nm (particularly 120 to 190 nm), and most preferably 120 to 185 nm (particularly 120 to 180 nm). If the central particle size is too small, it becomes difficult to uniformly disperse the silver ion scavenger (C), which reduces thermal shock resistance and may also reduce handling and storage stability. If the central particle size is too large, it may reduce heat dissipation.

[0046] Silver-containing metal nanoparticles (A) 10% volume particle size (D １０ The particle size is, for example, 10 nm or larger (e.g., 10 to 100 nm), preferably 30 nm or larger (e.g., 30 to 90 nm), more preferably 50 nm or larger (e.g., 50 to 80 nm), more preferably 55 nm or larger (e.g., 55 to 75 nm), and most preferably 60 nm or larger (e.g., 60 to 70 nm). If the 10 volume% particle size is too small, it becomes difficult to uniformly disperse the silver ion scavenger (C), which reduces thermal shock resistance and may also reduce handling and storage stability.

[0047] 90% volume particle size (D) of silver-containing metal nanoparticles (A) ９０ The particle size is, for example, 100 nm or more (e.g., 100 to 900 nm), preferably 150 nm or more (e.g., 150 to 700 nm), more preferably 200 nm or more (e.g., 200 to 500 nm), more preferably 230 nm or more (e.g., 230 to 400 nm), and most preferably 240 nm or more (e.g., 240 to 300 nm). If the 90% volume particle size is too small, it becomes difficult to uniformly disperse the silver ion scavenger (C), which reduces thermal shock resistance and may also reduce handling and storage stability.

[0048] When the silver-containing metal nanoparticles (A) have such a particle size distribution, their low-temperature sinterability is enhanced, allowing for the formation of a dense bonding layer. Furthermore, silver ion scavenging particles (C) having a similar particle size can be uniformly dispersed within the bonding layer, thereby further improving bonding strength and thermal shock resistance.

[0049] In this application, the central particle diameter (D) of the silver-containing metal nanoparticle (A)５０ ), 10% by volume particle size (D １０ ) and 90% volume particle size (D ９０ ) can be measured using a transmission electron microscope, and the central particle diameter (D) when any 200 particle diameters are expressed as a volume distribution is the central particle diameter. ５０ ), 10% by volume particle size (D １０ ) and 90% volume particle size (D ９０ ) means.

[0050] The shape of the silver-containing metal nanoparticles (A) is not particularly limited as long as it is granular (or in lump form), and examples include spherical (perfectly spherical or nearly spherical), ellipsoidal, rod-shaped or rod-shaped, cylindrical or conical, polyhedral [for example, polygonal prisms such as cubes and rectangular prisms; polygonal pyramidal shapes such as triangular pyramidal or square pyramidal (pyramidal) shapes], flake-shaped, fibrous, dendritic, and irregular shapes. Of these, granular shapes such as spherical and irregular shapes are commonly used.

[0051] The sintered body obtained by firing silver-containing metal nanoparticles (A) only needs to be in a state where the silver-containing metal nanoparticles (A) are solidified together by firing. It may be a sintered body of silver-containing metal nanoparticles (A) alone, or a sintered body of composite nanoparticles of silver-containing metal nanoparticles (A) and an organic component. In the case of the composite nanoparticle sintered body, a sintered body containing an organic component in addition to the solidified silver-containing metal nanoparticles (A) is obtained. Of these, a sintered body of composite nanoparticles containing a protective colloid as the organic component is preferred. Using composite nanoparticles containing a protective colloid improves handling and increases the productivity of the bonding layer.

[0052] In composite nanoparticles of silver-containing metal nanoparticles (A) and protective colloid, the composite form of silver-containing metal nanoparticles (A) and protective colloid is not particularly limited. The composite may be one in which the protective colloid is attached to or coordinated to the surface of the silver-containing metal nanoparticles (A), or it may be a composite in which the surface of the silver-containing metal nanoparticles (A) is coated with protective colloid. Because silver-containing metal nanoparticles (A) have high coordination ability to protective colloid (or dispersant), the composite may be one in which the protective colloid coordinates to the surface of the silver-containing metal nanoparticles (A) and coats the silver-containing metal nanoparticles (A). When silver-containing metal nanoparticles (A) are composited with protective colloid, the dispersion stability of the silver-containing metal nanoparticles (A) can be improved.

[0053] The protective colloid may be a dispersant, and is often a non-volatile dispersant. In particular, it is preferable that the protective colloid contains a polymeric dispersant having a carboxyl group or a derivative group thereof. In this application, the carboxyl group also includes carboxyl groups in the form of acid anhydride groups.

[0054] The polymer dispersant (or polymer-type dispersant) may have at least carboxyl groups and be capable of dispersing silver-containing metal nanoparticles, and may be an amphiphilic polymer dispersant (or oligomeric dispersant).

[0055] Examples of the aforementioned polymer dispersants include polymer dispersants commonly used for dispersing colorants in the paint and ink fields. Typical polymer dispersants (amphiphilic polymer dispersants) include water-soluble or water-dispersible resins containing hydrophilic units (or hydrophilic blocks) formed from hydrophilic monomers.

[0056] Examples of the hydrophilic monomers include addition polymerizable monomers such as carboxyl group-containing monomers (unsaturated polycarboxylic acids such as (meth)acrylic acid, maleic acid, and maleic anhydride or their acid anhydrides), monomers having a sulfo group (such as styrene sulfonic acid), and hydroxyl group-containing monomers (such as hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate and vinylphenol); and condensation polymerizable monomers such as ethylene oxide. The condensation polymerizable monomer may form a hydrophilic unit (or block) by reaction with active hydrogen such as a hydroxyl group (for example, the hydroxyl group). The hydrophilic monomers may form a hydrophilic unit (or block) alone or in combination of two or more. Preferred hydrophilic monomers are (meth)acrylic acid, maleic acid, maleic anhydride, and ethylene oxide.

[0057] The polymer dispersant may have at least a carboxyl group, and may also have the functional group of the hydrophilic monomer, such as an acid group (sulfo group) or a hydroxyl group. These functional groups may be introduced into the polymer dispersant individually or in combination of two or more.

[0058] The polymeric dispersant may contain at least a hydrophilic unit (or hydrophilic block), and may be a hydrophilic monomer alone or a copolymer thereof (e.g., polyacrylic acid or a salt thereof), or a copolymer of a hydrophilic monomer and a hydrophobic monomer. Examples of hydrophobic monomers (nonionic monomers) include (meth)acrylic acid esters [(meth)acrylic acid C, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate]. １－２０(Meth)acrylic monomers such as alkyl, cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate, aryl (meth)acrylates such as phenyl (meth)acrylate, benzyl (meth)acrylate, aralkyl (meth)acrylates such as 2-phenylethyl (meth)acrylate; styrene monomers such as styrene, α-methylstyrene, vinyltoluene; α-C ２－２０ Olefin monomers such as olefins (ethylene, propylene, 1-butene, isobutylene, 1-hexene, 1-octene, 1-dodecene, etc.); addition polymerizable monomers such as vinyl carboxylate monomers such as vinyl acetate and vinyl butyrate; and C120 ３－６ Examples include condensation polymerizable monomers such as alkylene oxides. Hydrophobic monomers may be used alone or in combination of two or more to form hydrophobic units.

[0059] The copolymer (for example, a copolymer of a hydrophilic monomer and a hydrophobic monomer) may be a random copolymer, an alternating copolymer, a block copolymer (for example, a copolymer composed of a hydrophilic block made of hydrophilic monomers and a hydrophobic block made of hydrophobic monomers), a comb copolymer (or comb graft copolymer), etc. The structure of the block copolymer is not particularly limited and may be a diblock structure, a triblock structure (ABA type, BAB type), etc. Furthermore, in the comb copolymer, the main chain may be formed of the hydrophilic block or the hydrophobic block, or it may be formed of a hydrophilic block and a hydrophobic block. Block copolymers of hydrophilic blocks and hydrophobic blocks can also have improved silver luster.

[0060] As mentioned above, the hydrophilic unit can also be formed from a hydrophilic block (such as a polyalkylene oxide like polyethylene oxide). The hydrophilic block (such as a polyalkylene oxide) and the hydrophobic block (such as a polyolefin block) may be linked via linking groups such as ester bonds, amide bonds, ether bonds, or urethane bonds. These bonds may be formed, for example, by modifying the hydrophobic block (such as a polyolefin) with a modifying agent [such as an unsaturated carboxylic acid or its anhydride (such as maleic anhydride), lactam or aminocarboxylic acid, hydroxylamine, or diamine], and then introducing the hydrophilic block. Alternatively, a comb copolymer (a comb copolymer whose main chain is composed of hydrophobic blocks) may be formed by reacting (or bonding) a polymer obtained from a monomer having hydrophilic groups such as hydroxyl groups or carboxyl groups (such as the aforementioned hydroxyalkyl (meth)acrylate) with the hydrophilic monomer of the condensation system (such as ethylene oxide).

[0061] Furthermore, the balance between hydrophilicity and hydrophobicity may be adjusted by using hydrophilic nonionic monomers as copolymerization components. Examples of such components include monomers or oligomers having ethylene oxide units, such as 2-(2-methoxyethoxy)ethyl (meth)acrylate and polyethylene glycol mono(meth)acrylate (e.g., number average molecular weight 200 to 1,000). Alternatively, the balance between hydrophilicity and hydrophobicity may be adjusted by modifying (e.g., esterifying) hydrophilic groups (such as carboxyl groups).

[0062] In polymer dispersants having carboxyl groups, the carboxyl groups may be salts or acid anhydride groups. For example, at least some of the carboxyl groups may form salts (salts with amines, metal salts, etc.). However, polymer dispersants in which acid groups such as carboxyl groups do not form salts [i.e., polymer dispersants having free carboxyl groups] can be suitably used.

[0063] The acid value of a polymeric dispersant having a carboxyl group may be, for example, 1 mg KOH / g or more (e.g., 2 to 100 mg KOH / g), preferably 3 mg KOH / g or more (e.g., 4 to 90 mg KOH / g), more preferably 5 mg KOH / g or more (e.g., 6 to 80 mg KOH / g), and more preferably 7 mg KOH / g or more (e.g., 8 to 50 mg KOH / g), and is usually 3 to 30 mg KOH / g (particularly 5 to 20 mg KOH / g). In addition, the amine value of such a polymeric dispersant may be 0 (or nearly 0).

[0064] In the polymer dispersant, the position of the functional group is not particularly limited and may be located in the main chain, in the side chain, or in both the main chain and the side chain. Such a functional group may be, for example, a functional group derived from a hydrophilic monomer or hydrophilic unit (e.g., a functional group introduced by copolymerization of (meth)acrylic acid, maleic anhydride, ethylene oxide, etc.).

[0065] Polymeric dispersants containing carboxyl groups may be used alone or in combination of two or more types.

[0066] Furthermore, as a polymer dispersant, polymer dispersants (high molecular weight pigment dispersants) described in Japanese Patent Publication No. 2004-207558, etc., may be used. Also, the polymer dispersant may be synthesized or a commercially available product may be used. Specific examples of commercially available polymer dispersants (or dispersants composed of at least an amphiphilic dispersant) include the Solspers series [manufactured by Abyssia Co., Ltd.] such as Solspers 13240, Solspers 13940, Solspers 32550, Solspers 31845, Solspers 24000, Solspers 26000, Solspers 27000, Solspers 28000, Solspers 41090; Dispervic 160, Dispervic 161, Dispervic 162, etc. The Disperbyk series, including Superbic 163, Disperbyk 164, Disperbyk 166, Disperbyk 170, Disperbyk 180, Disperbyk 182, Disperbyk 184, Disperbyk 190, Disperbyk 191, Disperbyk 192, Disperbyk 193, Disperbyk 194, Disperbyk 2001, Disperbyk 2015, Disperbyk 2050, etc. [BIG-Chemie Japan Co., Ltd.] ) ]; EFKA-46, EFKA-47, EFKA-48, EFKA-49, EFKA-1501, EFKA-1502, EFKA-4540, EFKA-4550, Polymer 100, Polymer 120, Polymer 150, Polymer 400, Polymer 401, Polymer 402, Polymer 403, Polymer 450, Polymer 451, Polymer 452, Polymer 453 [Manufactured by EFKA Chemical Co., Ltd.]; Azisper PB711, Azisper PA111, Azisper PB811, Azisper PB82 Examples include: 1. The Azisper series, such as Azisper PW911 [manufactured by Ajinomoto Co., Inc.]; the Floren series, such as Floren DOPA-158, Floren DOPA-22, Floren DOPA-17, Floren TG-700, Floren TG-720W, Floren-730W, Floren-740W, Floren-745W [manufactured by Kyoeisha Chemical Co., Ltd.]; and the Johncryl series, such as Johncryl 678, Johncryl 679, Johncryl 62 [manufactured by Johnson Polymer Co., Ltd.].Representative polymer dispersants include Dispervic 190, Dispervic 194, and Dispervic 2015.

[0067] The number-average molecular weight of the polymer dispersant, when measured by gel permeation chromatography (GPC), is, for example, 1,500 to 100,000, preferably 2,000 to 80,000 (e.g., 2,000 to 60,000), more preferably 3,000 to 50,000 (e.g., 5,000 to 30,000), and more preferably 7,000 to 20,000, in terms of polystyrene equivalent.

[0068] The polymeric dispersant having a carboxyl group may also be a polymeric dispersant that does not have a hydroxyl group.

[0069] The protective colloid may contain other dispersants if necessary, and these other dispersants may be inorganic compounds, but are usually organic compounds. Examples of other dispersants include alkanols (such as hexanol, octanol, decanol, dodecanol, octadecanol, etc.). ６－２０ Alkane monools), aldehydes (such as caprylic aldehyde, lauryl aldehyde, palmitaldehyde, etc.) ６－２０ Examples include aliphatic aldehydes, aliphatic hydroxycarboxylic acids, higher fatty acids or their salts, and sulfonic acids (such as alkanesulfonic acids, benzenesulfonic acids, and arenesulfonic acids like toluenesulfonic acid). These other dispersants may be used alone or in combination of two or more.

[0070] The proportion of other dispersants is, for example, 0.1 to 100 parts by mass, preferably 0.5 to 50 parts by mass, and more preferably 1 to 30 parts by mass, per 100 parts by mass of the polymer dispersant.

[0071] The proportion of protective colloid (particularly a polymer dispersant having a carboxyl group) can be selected from a range of, for example, 0.1 to 10 parts by mass per 100 parts by mass of silver-containing metal nanoparticles (A), preferably 0.1 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, and more preferably 0.7 to 2 parts by mass. If the proportion of protective colloid is too low, the dispersion stability in the paste composition may decrease. If the proportion of protective colloid is too high, the heat dissipation of the bonding layer may decrease.

[0072] In this application, the proportion of protective colloids in the composite nanoparticles can be measured by conventional methods, such as thermal analysis (e.g., simultaneous thermogravimetric / differential thermal analysis).

[0073] The proportion of silver-containing metal nanoparticles (A) in the paste composition may be 10% by mass or more, for example, 10 to 90% by mass, preferably 30 to 80% by mass, more preferably 35 to 70% by mass, more preferably 40 to 60% by mass, and most preferably 45 to 55% by mass. If the proportion of silver-containing metal nanoparticles (A) is too low, the low-temperature sinterability may decrease.

[0074] The method for producing the composite nanoparticles is not particularly limited. The composite nanoparticles can be prepared by conventional methods, for example, by reducing a silver compound corresponding to the silver nanoparticles in a solvent in the presence of a protective colloid and a reducing agent when the silver-containing metal is elemental silver. Specific production methods include, for example, the methods described in Japanese Patent Publication No. 2010-80442 and Japanese Patent Publication No. 2010-229544.

[0075] (B) Silver particles The silver particles (B) are particles with a larger particle size than the silver-containing metal nanoparticles (A), and specifically, they are large particles with a particle size of 1 μm or more (i.e., a group of particles in the paste composition having a particle size distribution in the range of 1 μm or more).

[0076] In other words, the minimum particle diameter (minimum primary particle diameter) of the silver particles (B) is 1 μm or larger, preferably 1.01 μm or larger, more preferably 1.05 μm or larger, more preferably 1.1 μm or larger, and most preferably 1.15 μm or larger. If the minimum particle diameter is too small, the bonding layer will become too rigid, which may reduce its thermal shock resistance.

[0077] In this application, the minimum particle size of the silver particles (B) can be confirmed based on the particle size distribution (volume distribution) measured using a laser diffraction scattering particle size distribution analyzer.

[0078] Silver particle (B) central particle diameter (50% volume particle diameter) (D) ５０ The central particle diameter (D) is 1.5 to 20 μm, preferably 1.5 to 15 μm, and more preferably 1.5 to 12 μm (for example, 1.5 to 10 μm). From the viewpoint of improving bonding strength and thermal shock resistance, the central particle diameter (D) is ５０ The particle size is preferably 2 to 8 μm, more preferably 2.5 to 7 μm, more preferably 3 to 5 μm, and most preferably 3.5 to 4.5 μm. If the central particle size is too small, the bonding layer may become too rigid, which may reduce its thermal shock resistance. If the central particle size is too large, the density of the bonding layer may decrease, which may reduce the bonding strength.

[0079] The central particle diameter (D) of the silver particle (B) ５０ ) is the central particle diameter (D) of the silver-containing metal nanoparticle (A). ５０ The ratio can be selected from a range of approximately 1.5 to 1000 times (particularly 2 to 500 times) relative to the given value, for example, 3 to 100 times, preferably 5 to 50 times, more preferably 10 to 40 times, more preferably 20 to 35 times, and most preferably 25 to 30 times.

[0080] 10% volume particle size (D) of silver particles (B) １０ The particle size is, for example, 1.1 to 3.5 μm, preferably 1.2 to 3 μm, more preferably 1.3 to 2.8 μm, more preferably 1.5 to 2.5 μm, and most preferably 1.8 to 2.2 μm. If the 10% volume particle size is too small, the thermal shock resistance may decrease. If the 10% volume particle size is too large, the bonding strength may decrease.

[0081] 90% volume particle size (D) of silver particles (B) ９０ The particle size is, for example, 4 to 20 μm, preferably 5 to 15 μm, more preferably 6 to 12 μm, more preferably 8 to 10 μm, and most preferably 8.5 to 9.5 μm. If the 90% volume particle size is too small, the thermal shock resistance may decrease. If the 90% volume particle size is too large, the bonding strength may decrease.

[0082] Furthermore, in this application, the central particle diameter (D) of the silver particle (B) ５０ ), 10% by volume particle size (D １０ ) and 90% volume particle size (D ９０ ) can be measured by a method compliant with JIS Z 8825:2022 (Particle size analysis - Laser diffraction and scattering), and specifically refers to the particle size based on the particle size distribution (volume distribution) measured using a laser diffraction scattering particle size distribution analyzer by the following method.

[0083] The particle size distribution can be measured using a laser diffraction / scattering particle size distribution analyzer (Microtrac MT-3000II, manufactured by Microtrac Bell Co., Ltd.). For details, the sample is subjected to the analyzer and the particle size distribution is determined using the accompanying analysis software. The sample used is a dispersion prepared by adding 0.1 g of silver particles to 40 mL of an isopropanol solution containing polyvinylpyrrolidone (PVP) at a concentration of 1 mass%, and dispersing it for 2 minutes using an ultrasonic homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd., model name: US-150T; 19.5 kHz, tip diameter 18 mm). During measurement, an SDC device is used as the circulation device of the analyzer, and the "flow rate (%)" setting of the circulation device is set to 60.

[0084] In this invention, the density and thermal shock resistance of the bonding layer can be improved by combining silver-containing metal nanoparticles (A) and silver particles (B).

[0085] In other words, using only one of the particles, either silver-containing metal nanoparticles (A) or silver particles (B), results in low dispersibility and difficulty in achieving high concentrations, leading to low packing efficiency (many gaps). However, by combining both particles, the silver-containing metal nanoparticles (A) can fill the gaps between the larger silver particles (B), allowing for close-packed arrangement of the silver particles. This enables the formation of a dense bonding layer (sintered body) after sintering.

[0086] Furthermore, active nanoparticles rapidly sinter even at low temperatures with sharp shrinkage, resulting in localized density but an overall sparse, porous, and low-density sintered body. In addition, nanoparticles generally contain a relatively large amount of organic matter as protective colloids, and this organic matter inhibits the densification of the sintered body. In contrast, by arranging silver-containing metal nanoparticles (A) in the gaps between large-diameter silver particles (B) that can be sintered gently, the voids in the overall sintered body are reduced, resulting in a highly dense sintered body.

[0087] Furthermore, because sintered bodies of nanoparticles are rigid and brittle, even if the initial bonding strength is high, a sudden crack formation and propagation can occur when thermal load is applied, leading to a rapid decrease in strength. In addition, because nanoparticles are reactive to heat, sintered bodies containing nanoparticles undergo migration (reconstruction) of crystal interfaces (grain boundaries), and tiny voids (micropores) can propagate into larger cavities (voids) and cracks, resulting in low thermal shock resistance. In contrast, silver particles (B) are relatively flexible, and do not undergo migration (reconstruction) of crystal interfaces (grain boundaries) even with some heat. Therefore, by combining silver particles (B) with silver-containing metal nanoparticles (A), a balance can be achieved between initial bonding strength and thermal shock resistance.

[0088] Examples of the shapes of the silver particles (B) include spherical (perfectly spherical or nearly spherical), ellipsoidal, rod-shaped or rod-shaped, cylindrical or conical, polyhedral (for example, polygonal prisms such as cubes and rectangular prisms; polygonal pyramidal shapes such as triangular pyramidal and square pyramidal), flake-shaped, fibrous, dendritic, and irregular shapes. Of these, spherical and flake-shaped are preferred, and flake-shaped are particularly preferred. When the shape of the silver particles (B) is flake-shaped, the density of the bonding layer can be improved, thereby further improving bonding strength and heat dissipation.

[0089] In this invention, "flake-like" includes forms (shapes) such as flattened, plate-like, flaky, and scale-like, and also includes forms (shapes) of three-dimensional silver particles (especially silver powder) such as spherical or lumpy shapes that have been rolled or crushed in one direction. When such flake-like silver particles are used, the contact efficiency between adjacent silver particles is high, and it is easy to form heat dissipation passages.

[0090] The mass ratio of silver-containing metal nanoparticles (A) to silver particles (B) can be selected from a range of approximately 90 / 10 to 1 / 99, for example, 80 / 20 to 5 / 95 (particularly 80 / 20 to 10 / 90), preferably 75 / 25 to 5 / 95, even more preferably 50 / 50 to 10 / 90, more preferably 45 / 55 to 20 / 80, and most preferably 45 / 55 to 35 / 65. If the ratio of silver particles (B) is too low, the low-temperature sinterability may decrease. If the ratio of silver particles (B) is too high, the thermal shock resistance may decrease.

[0091] (C) Silver ion scavenging agent In this invention, silver-containing metal nanoparticles (A) and silver particles (B) are made to coexist and combined with a silver ion scavenging agent (C). By doing so, as described above, a dense bonding layer can be formed after sintering. Furthermore, while ensuring the sinterability provided by the silver-containing metal nanoparticles (A), the occurrence and propagation of defects (voids and cracks) that lead to embrittlement of the bonding layer due to the silver-containing metal nanoparticles (A) can be suppressed by the action of the silver ion scavenging agent (C), thereby improving the thermal shock resistance of the bonding layer.

[0092] The silver ion scavenger (C) only needs to have the ability to capture silver ions, but inorganic fillers are preferred from the viewpoint of improving the thermal shock resistance of the bonding layer, and inorganic compounds having the ability to capture cations (cation scavenging ability) are particularly preferred. The inorganic compound having cation scavenging ability only needs to have cation scavenging ability, and may be an inorganic compound having only cation scavenging ability (cation scavenger or cation exchanger), or an inorganic compound having the ability to capture both cations and anions (dual ion scavenging ability) (dual ion scavenger or dual ion exchanger).

[0093] Examples of cation scavengers include (hydrated) oxides or hydroxides [e.g., metal hydroxides such as zirconium hydroxide; manganic acid (or manganese oxide hydrate) such as hydrated manganese dioxide; hydrated silicon oxide such as silica gel; antimony acids such as crystalline antimony acid and hydrated antimony pentoxide], and acidic salts of polyvalent metals [e.g., metal phosphate salts such as calcium phosphate, zinc calcium phosphate, titanium phosphate, zirconium phosphate, aluminum phosphate, and tin phosphate; metal polyphosphate salts such as zirconium polyphosphate; metal oxalate salts such as cerium(III) oxalate; metal silicate salts such as zirconium silicate; metal molybdate salts such as zirconium molybdate; metal tungstate salts such as zirconium tungstate; metal antimonate salts such as zirconium antimonate, aluminum antimonate, and tin antimonate; zirconium selenate, etc.]. Examples include metal selenite salts (such as zirconium tellurate), aluminosilicates or clay minerals (for example, synthetic zeolites (aluminosilicates) such as type A zeolite, type X zeolite, type Y zeolite, type T zeolite, etc.; natural zeolites (aluminosilicates) such as chabasite, erionite, mordenite, clinoptilolite, etc.; green sand such as natural green sand, stabilized green sand, manganese green sand, etc.), heteropolyphosphates (for example, ammonium phosphomolybdate such as ammonium dodecamolybdate; ammonium phosphotungstate such as ammonium dodecatungstrate; zirconium phosphosilicate, etc.), and ferrocyanide complexes (for example, potassium hexacyanoiron(III)cobalt(II), etc.).

[0094] The cation scavenger may be a commercially available product. Examples of commercially available cation scavengers include zirconium phosphate-based cation scavengers (such as "IXE®-100" manufactured by Toagosei Co., Ltd.), antimony oxide-based cation scavengers (such as "IXE-300" manufactured by Toagosei Co., Ltd.), and aluminum silicate-based ion scavengers (such as "Kyoword® 700" manufactured by Kyowa Chemical Industry Co., Ltd.).

[0095] These cation scavengers can be used individually or in combination of two or more.

[0096] Examples of both ion scavengers include (hydrated) oxides [e.g., aluminum oxide such as hydrated aluminum oxide (alumina); titanium oxide such as hydrated titanium oxide (titania); zirconium oxide such as hydrated zirconium oxide (zirconia)], silicates (e.g., metal silicate salts such as magnesium silicate), etc. Both ion scavengers may be a mixture of the cation scavenger and an inorganic compound (anion scavenger or anion exchanger) that has only anion scavenging ability. Examples of anion scavengers included in this mixture include (hydrated) oxides or hydroxides [e.g., metal hydroxides such as aluminum hydroxide; bismuth oxide such as hydrated bismuth oxide and hydrated bismuth nitrate; metal phosphate salts such as lead hydroxide phosphate], magnesium aluminum composite oxides (e.g., hydrotalcite), etc. Both ion scavengers can be used individually or in combination of two or more.

[0097] The dual ion scavenger may be a commercially available product. Examples of commercially available dual ion scavengers include antimony oxide-bismuth oxide-based dual ion scavenger ("IXE-600" manufactured by Toagosei Co., Ltd.), antimony oxide-bismuth oxide-based dual ion scavenger ("IXE-633" manufactured by Toagosei Co., Ltd.), zirconium oxide-bismuth oxide-based dual ion scavenger ("IXE-6107" manufactured by Toagosei Co., Ltd.), zirconium oxide-bismuth oxide-based dual ion scavenger ("IXE-6136" manufactured by Toagosei Co., Ltd.), and Mg-Al-Zr composite compound-based dual ion scavenger. Examples include ion scavenging agents (such as "IXEPLAS-A1" manufactured by Toagosei Co., Ltd.), Mg / Al / Zr complex compound-based biion scavenging agents (such as "IXEPLAS-A2" manufactured by Toagosei Co., Ltd.), Bi / Zr complex compound-based biion scavenging agents (such as "IXEPLAS-B1" manufactured by Toagosei Co., Ltd.), magnesium silicate-based biion scavenging agents (such as "Kyoward 600" manufactured by Kyowa Chemical Industry Co., Ltd.), and aluminum oxide-magnesium oxide-based biion scavenging agents (such as "Kyoward KW-2000" manufactured by Kyowa Chemical Industry Co., Ltd.).

[0098] Among these silver ion scavengers, those containing zirconium compounds such as zirconium phosphate, zirconium antimonate, and zirconium oxide; antimony compounds such as antimony oxide (antimony acid); and aluminosilicates such as zeolites are preferred due to their excellent silver ion scavenging ability, and those containing zirconium compounds and / or aluminosilicates are particularly preferred.

[0099] The ion exchange capacity of the silver ion scavenger (C) may be 0.1 meq / g or more, for example, 0.1 to 20 meq / g, preferably 0.5 to 15 meq / g, more preferably 1 to 10 meq / g, more preferably 3 to 10 meq / g, and most preferably 5 to 8 meq / g. If the ion exchange capacity of the silver ion scavenger (C) is too low, there is a risk that the thermal shock resistance of the bonding layer cannot be greatly improved.

[0100] In this application, the ion exchange capacity of the silver ion scavenger (C) is defined as the ion exchange capacity in a 0.1 N NaOH aqueous solution.

[0101] Examples of the shape of the silver ion scavenger (C) include spherical, ellipsoidal, rod-shaped or rod-shaped, cylindrical or conical, polyhedral, flake-shaped, fibrous, arventic, and irregular shapes. Of these, ellipsoidal, polyhedral, and irregular shapes are commonly used.

[0102] Silver ion scavenger (C) central particle size (50% volume particle size) (D ５０ The particle size can be selected from a range of approximately 5 to 3000 nm, for example, 10 to 1000 nm, preferably 50 to 500 nm, more preferably 100 to 300 nm, more preferably 150 to 250 nm, and most preferably 180 to 220 nm. If the central particle size is too small, it may inhibit the silver sintering of the bonding layer, potentially reducing the bonding strength (initial strength) and heat dissipation of the bonding layer. If it is too large, the silver ion scavenger (C) may be unevenly distributed within the bonding layer, reducing the silver ion scavenging effect and potentially lowering the thermal shock resistance of the bonding layer.

[0103] The central particle size (D) of the silver ion scavenger (C) ５０ ) is the central particle diameter (D) of the silver-containing metal nanoparticle (A). ５０The ratio can be selected from a range of approximately 0.1 to 10 times (particularly 0.3 to 5 times) relative to the original particle size, for example, 0.5 to 3 times, preferably 0.7 to 2 times, more preferably 0.8 to 1.8 times, more preferably 0.9 to 1.6 times, and most preferably 1 to 1.5 times. The central particle diameters of both particles may be approximately the same (for example, 0.6 to 1.4 times, particularly 0.8 to 1.2 times). By adjusting the central particle diameters of both particles to these ranges, nanoparticles can be uniformly dispersed, and a high degree of compatibility between bonding strength and thermal shock resistance can be achieved.

[0104] In this application, the central particle diameter (D) of the silver ion scavenger (C) ５０ ) refers to the particle size based on the particle size distribution (volume distribution) measured using a laser diffraction scattering particle size distribution analyzer.

[0105] The proportion of the silver ion scavenger (C) can be selected from a range of approximately 0.005 to 10 parts by mass (particularly 0.01 to 5 parts by mass) per 100 parts by mass of silver-containing metal nanoparticles (A), for example, 0.03 to 3 parts by mass. However, from the viewpoint of excellent balance between bonding strength and thermal shock resistance, it is preferably 0.05 to 1 part by mass, more preferably 0.05 to 0.25 parts by mass, more preferably 0.07 to 0.2 parts by mass, and most preferably 0.08 to 0.15 parts by mass. If the proportion of the silver ion scavenger (C) is too low, there is a risk that the thermal shock resistance of the bonding layer cannot be greatly improved. If the proportion of the silver ion scavenger (C) is too high, there is a risk that the heat dissipation performance of the bonding layer will decrease.

[0106] (D) Organic solvent The organic solvent (D) is not particularly limited and can be any organic compound that imparts appropriate viscosity to the paste composition (especially silver sintering paste) and can be easily volatilized by drying after the paste composition is applied to the substrate, and may be an organic solvent with a high boiling point.

[0107] Examples of such organic solvents include aromatic hydrocarbons (paraxylene, ethylbenzene, trimethylbenzene, naphthalene, cumene, indene, etc.), aliphatic hydrocarbons (hexane, heptane, octane, nonane, etc.), esters (ethyl lactate, texanol, etc.), ketones (isophorone, etc.), amides (dimethylformamide, etc.), and aliphatic alcohols (ethanol, isopropanol, butanol, octanol, 2-ethylhexanol, decanol, diacetone alcohol). (etc.), cellosolves (methyl cellosolve, cellosolve, etc.), cellosolve acetates (methyl cellosolve acetate, cellosolve acetate, butyl cellosolve acetate, etc.), carbitols (methyl carbitol, ethyl carbitol, butyl carbitol, hexyl carbitol, etc.), carbitol acetates (methyl carbitol acetate, carbitol acetate, butyl carbitol acetate), triethylene glycol monoalkyl ethers (triethylene Examples of organic solvents include ethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, etc.), triethylene glycol monoalkyl ether acetates (triethylene glycol monomethyl ether acetate, triethylene glycol monobutyl ether acetate, etc.), aliphatic polyhydric alcohols (ethylene glycol, diethylene glycol, 1,3-propanediol, dipropylene glycol, butanediol, 1,5-pentanediol, triethylene glycol, glycerin, etc.), alicyclic alcohols [e.g., cycloalkanols such as cyclohexanol; terpene alcohols such as α-terpineol and dihydroterpineol (monoterpene alcohols, etc.)], aromatic alcohols (metacresol, etc.), aromatic carboxylic acid esters (dibutyl phthalate, dioctyl phthalate, etc.), and nitrogen-containing heterocyclic compounds (dimethylimidazole, dimethylimidazolidinone, etc.). These organic solvents can be used individually or in combination of two or more.

[0108] Of these organic solvents, cellosolves, cellosolve acetates, carbitols, carbitol acetates, triethylene glycol monoalkyl ethers, and triethylene glycol monoalkyl ether acetates are preferred because they do not volatilize at room temperature and have appropriate fluidity. C13 １－６ Alkyl carbitols; triethylene glycol monobutyl ether (butyl triglycol) and other triethylene glycol mono-C １－４ Alkyl ethers are particularly preferred, and triethylene glycol monoC ２－４ Alkyl ethers are most preferred.

[0109] The proportion of the organic solvent (D) can be selected from a range of about 0.01 to 50 parts by mass per 100 parts by mass of the total amount of silver-containing metal nanoparticles (A) and silver particles (B), for example, 1 to 30 parts by mass, preferably 3 to 20 parts by mass, more preferably 5 to 15 parts by mass, and most preferably 8 to 13 parts by mass. If the proportion of the organic solvent (D) is too low, the viscosity of the paste composition may increase and its handling properties may decrease. If the proportion of the organic solvent (D) is too high, the density of the bonding layer may decrease.

[0110] (E) Other metal components The paste composition of the present invention may further contain metal components other than silver-containing metal nanoparticles (A) and silver particles (B) (hereinafter referred to as "other metal components") (E).

[0111] Other metallic components (E) include, for example, metallic components (elemental metals, metallic compounds) of metallic elements selected from the group consisting of Mn, Fe, Cu, Pd, Al, Ni, Mo, W, Pt, Au, Co, Ti, Zr, Sn, etc., and Ag compounds. The elemental metal may be an alloy. The metallic compound (or Ag compound) may be a compound of a metal (or Ag) and a nonmetal (for example, a metal oxide, metal hydroxide, metal sulfide, metal carbide, metal nitride, metal boride, etc.).

[0112] Other metallic components (E) can take the following shapes, for example: spherical, ellipsoidal or rod-shaped, cylindrical or conical, polyhedral, flake-shaped, rod-shaped or rod-shaped, fibrous, dendritic, or irregular shape. Of these, metallic components such as ellipsoidal, polyhedral, and irregular shapes are commonly used.

[0113] The central particle diameter (D) of the particles formed by other metal components (E) ５０ The thickness of the particles is, for example, 0.5 to 30 μm, preferably 1 to 10 μm, and more preferably 1 to 5 μm.

[0114] In this application, the central particle diameter (D) of particles formed with other metal components (E) is specified. ５０ ) refers to the particle size based on the particle size distribution (volume distribution) measured using a laser diffraction scattering particle size distribution analyzer.

[0115] The proportion of other metal components (E) is 5 parts by mass or less (for example, about 0.01 to 5 parts by mass) per 100 parts by mass of the total amount of silver-containing metal nanoparticles (A) and silver particles (B).

[0116] (F) Conventional Additives The paste composition of the present invention may further contain conventional additives (F) to the extent that they do not impair the effects of the present invention. Examples of conventional additives (F) include binder resins, glass particles, curing agents (such as curing agents for acrylic resins), colorants (such as dyes and pigments), hue modifiers, dye fixatives, gloss enhancers, metal corrosion inhibitors, stabilizers (such as antioxidants and UV absorbers), surfactants or dispersants (such as anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants), dispersion stabilizers, viscosity modifiers or rheology modifiers, humectants, thixotropy enhancers, leveling agents, defoamers, bactericides, and fillers. These other components can be used individually or in combination of two or more.

[0117] The total proportion of conventional additives (F) is 10 parts by mass or less (for example, about 0.01 to 10 parts by mass) per 100 parts by mass of the total amount of silver-containing metal nanoparticles (A) and silver particles (B).

[0118] In particular, the paste composition of the present invention is preferably substantially free of binder resin (such as thermoplastic resin or thermosetting resin) and especially preferably completely free of binder resin, as this can improve the thermal shock resistance of the bonding layer.

[0119] [Method for preparing the paste composition] As a method for preparing the paste composition of the present invention (in particular, silver sintering paste), a conventional mixing machine can be used to uniformly disperse each component, and a device with a grinding function (for example, a three-roll mortar and pestle, a mill, etc.) may also be used. Each component may be added all at once and mixed, or added in portions and mixed.

[0120] [Laminate and Method for Manufacturing the Same] The paste composition of the present invention may be a bonding composition used to bond a first member to be bonded and a second member to be bonded. The members to be bonded may be members used in the field of electronics, etc., and are not particularly limited, but since the bonding layer, which is a sintered body of the paste composition of the present invention, has excellent heat dissipation properties, members used in high-temperature environments are preferred. At least one of the first member to be bonded and the second member to be bonded used in a high-temperature environment may be, for example, a component of an electronic device including a semiconductor chip whose operating temperature is 200°C or higher, and the first member to be bonded or the second member to be bonded may be a component of the electronic device. The combination of the first member to be bonded and the second member to be bonded may be, for example, a combination of the semiconductor chip and an electronic substrate, or a combination of the electronic substrate and a cooler (heat sink). Furthermore, since the paste composition of the present invention can be sintered at low temperatures, high heat resistance is not required for the members to be bonded, and the members to be bonded are not limited to inorganic materials, but may be applied to members to be bonded made of organic materials. However, in terms of improving bonding strength, the paste composition of the present invention is preferably applied to members to be bonded, at least on the surface of which is made of metal. When a member to be joined, whose surface is made of metal, is joined with the paste composition of the present invention, a strong metallic bond can be formed at the interface between the member to be joined and the joining layer.

[0121] The laminate of the present invention can be manufactured by a manufacturing method that includes a coating step of applying a paste composition onto a first member to be joined, a placement step of placing a second member to be joined on the applied paste composition, and a firing step of firing the paste composition interposed between the first member to be joined and the second member to be joined to obtain a laminate in which a bonding layer, which is a sintered body, is interposed between the first member to be joined and the second member to be joined.

[0122] In the coating process, the method of applying the paste composition is not particularly limited and can be any method of applying the paste composition to the surface of the first member to be bonded, such as a substrate; therefore, conventional coating methods can be used. Conventional coating methods include, for example, drop coating methods such as dispenser coating and pin transfer coating; printing coating methods such as screen printing, flexographic printing, gravure printing, mask printing, and inkjet printing; flow coating; spin coating; spray coating; casting; bar coating; curtain coating; roll coating; dipping; slitting; and photolithography.

[0123] Of these, the drop-coating method and the printing method are preferred, and the drop-coating method is particularly preferred.

[0124] In the placement process, the method for placing the second member to be joined on the applied paste composition is not particularly limited and can be any method in which the second member to be joined is placed on the paste composition applied to the surface of the first member to be joined to form a laminate of the first member to be joined, the paste composition, and the second member to be joined. If the second member to be joined is a semiconductor chip, the method for placing the semiconductor chip can be, for example, a method using a die bonder (mounter).

[0125] In the firing process, the laminate obtained in the previous setting process is fired, causing the organic solvent (D) to volatilize and the silver-containing metal component of the paste composition to sinter and form a sintered body (bonding layer). In particular, when the surfaces of the first and second members to be joined are made of metal, the metal surface of the first member to be joined, the bonding layer, and the metal surface of the second member to be joined are joined by a strong metallic bond, resulting in high bonding strength as well as excellent heat dissipation and conductivity.

[0126] In the firing process, conventional firing methods can be used, such as continuous firing using a tunnel furnace or batch firing using an oven.

[0127] In the firing process, the firing method may be either a method in which the members to be joined are fired without pressure during firing (no-pressure firing method), or a method in which the members to be joined are fired while under pressure during firing (pressure firing method).

[0128] In the case of pressurized firing, methods such as pressurized firing using a hot press can be used. The pressure may be, for example, 1 to 100 MPa (especially 5 to 30 MPa).

[0129] The firing temperature (maximum temperature reached) can be selected according to the type of firing method. For example, in the case of non-pressure firing, it may be 100 to 300°C (particularly 150 to 250°C), and in the case of pressure firing, it may be 150 to 350°C (particularly 250 to 330°C). The paste composition of the present invention has excellent low-temperature sinterability because its metal components include silver-containing metal nanoparticles (A) and silver particles (B), so a dense bonding layer can be formed by firing at about 100 to 350°C. The heating rate during firing and the cooling rate after firing are not particularly limited and may be, for example, about 1 to 10°C / min (particularly 3 to 8°C / min). The firing time (heating time at the maximum temperature reached) is also not particularly limited and may be, for example, about 20 to 180 minutes (particularly 30 to 120 minutes).

[0130] For example, in the firing process of the non-pressurized firing method, firing may be performed according to the following temperature profile.

[0131] (1) Heat from room temperature (25°C) to 200°C at a rate of 5°C / min, (2) maintain at 200°C for 60 minutes, (3) cool from 200°C to room temperature (25°C) at a rate of 5°C / min.

[0132] On the other hand, in the firing process of the pressurized firing method, firing may be carried out according to the following temperature profile.

[0133] (1) Using a hot press machine, apply a uniform pressure of 10 MPa to a hot plate preheated to 310°C for 150 seconds, and (2) release the hot plate and allow to cool at room temperature (25°C) for 60 minutes.

[0134] Furthermore, from the viewpoint of ensuring uniform metal sintering within the bonding layer, a step of pre-drying the organic solvent (pre-drying step) may be included before the firing step. The pre-drying step is a process of drying the silver sintering paste by heating it to a temperature that does not cause the sintering of the metal components to progress, thereby volatilizing the organic solvent (D). In the pre-drying step, the heating temperature may be, for example, around 50 to 180°C (particularly 70 to 150°C), and the heating time may be, for example, around 10 to 120 minutes (particularly 20 to 60 minutes).

[0135] Furthermore, the pre-drying step may be the step following the placement step (the step before the firing step) in the non-pressure firing method, and may be the step following the coating step (the step before the placement step) in the pressure firing method.

[0136] For example, in the firing process including the pre-drying step in the non-pressure firing method, firing may be performed according to the following temperature profile.

[0137] (1) Heat from room temperature (25°C) to 80°C at a rate of 5°C / min, (2) maintain at 80°C for 30 minutes, (3) heat from 80°C to 200°C at a rate of 5°C / min, (4) maintain at 200°C for 60 minutes, (5) cool from 200°C to room temperature (25°C) at a rate of 5°C / min.

[0138] On the other hand, in the firing process including the pre-drying step in the pressure firing method, firing may be carried out according to the following temperature profile.

[0139] (1) Place in an oven preheated to 130°C for 30 minutes, (2) Allow to cool at room temperature (25°C) for 60 minutes, (3) Using a hot press, apply a uniform pressure of 10 MPa to a hot plate preheated to 310°C for 150 seconds, (4) Release the hot plate and allow to cool at room temperature (25°C) for 60 minutes.

[0140] The laminate obtained in this manner has excellent bonding strength, and the bonding strength between the first member to be bonded and the second member to be bonded by the bonding layer may be, for example, 50 MPa or more, preferably 70 MPa or more, more preferably 80 MPa or more, more preferably 90 MPa or more, and most preferably 100 MPa or more (for example, about 100 to 150 MPa).

[0141] In this application, the bonding strength of the laminate can be measured using a bond tester, and in detail, it can be measured by the method described in the examples below.

[0142] The laminate of the present invention has excellent thermal shock resistance (bonding reliability), so even when subjected to repeated thermal loads (thermal shock) due to rapid heating and cooling caused by changes in ambient temperature, the bonding layer can maintain high bonding strength. Specifically, because the laminate of the present invention has excellent thermal shock resistance, for example, when the operation of rapidly heating and cooling by holding a low temperature range (e.g., -55°C to -35°C, preferably around -50°C to -40°C) and a high temperature range (e.g., 140 to 160°C, preferably around 145 to 155°C) for about 30 minutes each is considered as one cycle, and this operation is repeated, high bonding strength can be maintained even after repeating the operation for, for example, 1000 cycles or more (e.g., 1000 to 10000 cycles).

[0143] Therefore, in the laminate of the present invention, the bonding strength after the thermal shock test may be 50% or more of the bonding strength before the thermal shock test, preferably 70% or more, more preferably 80% or more, more preferably 90% or more, and most preferably 95% or more.

[0144] In this application, a thermal shock test (heat cycle test), which is a method for evaluating thermal shock resistance by applying a thermal load to a sample by rapid heating and rapid cooling, can be carried out in accordance with JIS C 60068-2-14:2011, and in detail, it can be carried out by the method described in the examples below.

[0145] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0146] [Materials used] (Silver particles) Silver powder B1: Flake form, particle size distribution (D １０ ~D ９０ ) 2.0-8.9 μm, 10 volume % particle size (D １０ ) 2.0 μm, 50 volume % particle size (D ５０ ) 3.8 μm, 90% volume particle size (D ９０ ) 8.9 μm Silver powder B2: flake-like, particle size distribution (D １０ ~D ９０ ) 1.3-1.8 μm, 10 volume % particle size (D １０ ) 1.3 μm, 50% volume particle size (D ５０ ) 1.5 μm, 90% volume particle size (D ９０ ) 1.8 μm Silver powder B3: Flake-like, particle size distribution (D １０ ~D ９０ ) 5.0–23.0 μm, 10 volume % particle size (D １０ ) 5.0 μm, 50% volume particle size (D ５０ ) 12.0 μm, 90% volume particle size (D ９０ )23.0μm Silver powder B4: flake-like, particle size distribution (D １０ ~D ９０ ) 9.0-41.0 μm, 10 volume % particle size (D １０ ) 9.0 μm, 50% volume particle size (D ５０ ) 20.0 μm, 90% volume particle size (D ９０ ) 41.0 μm Silver powder B5: Flake-like, particle size distribution (D １０ ~D ９０ ) 15.0–64.0 μm, 10 volume % particle size (D １０ ) 15.0 μm, 50 volume % particle size (D ５０ ) 30.0 μm, 90% volume particle size (D ９０)64.0μm Silver powder B6: spherical, particle size distribution (D １０ ~D ９０ ) 2.0-8.9 μm, 10 volume % particle size (D １０ ) 2.0 μm, 50 volume % particle size (D ５０ ) 3.8 μm, 90% volume particle size (D ９０ ) 8.9 μm

[0147] (Silver ion scavenger) Silver ion scavenger C1: "Zeoal 4A" manufactured by Nakamura Choko Co., Ltd., aluminosilicate (zeolite) type silver ion scavenger, 50% by volume particle size (D ５０ ) 100 nm Silver ion scavenger C2: "IXEPLAS-A2" manufactured by Toagosei Co., Ltd., Mg / Al / Zr composite compound-based silver ion scavenger, 50 volume% particle size (D ５０ ) 200 nm Silver ion scavenger C3: "Zeoal 4A" manufactured by Nakamura Choko Co., Ltd., aluminosilicate (zeolite) type silver ion scavenger, 50% by volume particle size (D ５０ ) 300 nm Silver ion scavenger C4: "IXEPLAS-B1" manufactured by Toagosei Co., Ltd., Bi / Zr composite compound-based silver ion scavenger, 50 volume% particle size (D ５０ ) 400 nm Silver ion scavenger C5: "IXE-100" manufactured by Toagosei Co., Ltd., zirconium phosphate-based silver ion scavenger, 50% by volume Particle size (D ５０ ) 1000 nm Silver ion scavenger C6: "SP#2300" manufactured by Nitto Funka Kogyo Co., Ltd., aluminosilicate (zeolite) type silver ion scavenger, 50% by volume particle size (D ５０ ) 1000nm

[0148] (Other materials) Carboxyl group-containing polymer dispersant: "Disperbic 190" manufactured by Bic Chemie, solution of high molecular weight block copolymer containing carboxyl groups, solvent: water, non-volatile component 40%, acid value 10 mg KOH / g, amine value 0 Silica particles: spherical, 50% by volume particle size (D ５０ ) 500 nm Bi-Zn-B composite oxide particles: bismuth-based glass particles, 50 volume% particle size (D ５０ ) 400 nm Butyl triglycol: Manufactured by Fujifilm Wako Pure Chemical Corporation

[0149] [Preparation of composite nanoparticle dispersions (A1-A6)] Composite nanoparticles A1-A6 (silver nanoparticles coated with a polymeric dispersant having carboxyl groups) were prepared according to the following procedure.

[0150] (Composite Nanoparticles A1) First, 66.8 g of silver nitrate and 1.6 g of a polymeric dispersant having carboxyl groups were added to 100 g of deionized water and vigorously stirred to obtain a suspension. To this suspension, 100 g of dimethylaminoethanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was gradually added so that the water temperature did not exceed 50°C. Then, the mixture was heated and stirred in a water bath at 50°C for 4 hours to obtain a composite nanoparticle A1 dispersion.

[0151] Next, an excess amount of methanol was added to the obtained composite nanoparticle A1 dispersion and stirred. Then, the composite nanoparticles were allowed to settle by centrifugation, and the supernatant was removed. Methanol was added again and stirred, and then the composite nanoparticles were allowed to settle by centrifugation, and the supernatant was removed. Methanol was added again and stirred, and then the composite nanoparticles were allowed to settle by centrifugation, and the supernatant was removed. Butyl triglycol was added to the methanol solution containing the obtained precipitate, and the mixed methanol was removed using an evaporator to obtain a composite nanoparticle dispersion with a silver content of 90% by mass in the dispersion.

[0152] When the particle size of the silver nanoparticles A1 constituting the composite nanoparticle A1 was confirmed using a transmission electron microscope (manufactured by JEOL Ltd.) for this dispersion, the particle size at 10 volume percent was found to be D １０ ) is 55 nm, 50 volume % particle size (D ５０ ) is 102 nm, 90 volume % particle size (D ９０ The wavelength was 200 nm. Furthermore, when the composite nanoparticle dispersion was vacuum-dried and the resulting composite nanoparticle dry material was subjected to thermal analysis using a thermogravimetric differential thermal analysis (TG-DTA) apparatus to determine the content of the organic protective colloid component, the content of the organic protective colloid component relative to 100 parts by mass of the metal component (silver nanoparticle A1) in the composite nanoparticle A1 was 1.5 parts by mass.

[0153] (Composite nanoparticles A2) A dispersion of composite nanoparticles A2 was prepared in the same manner as the method for synthesizing the dispersion of composite nanoparticles A1, except that the amount of the polymer dispersant used was changed to 6.9 g. For this dispersion, in the same manner as for composite nanoparticles A1, the particle diameter of silver nanoparticles A2 constituting composite nanoparticles A2 and the content of the organic protective colloid component were confirmed, and the 10 volume % particle diameter (D １０ ) was 14 nm, the 50 volume % particle diameter (D ５０ ) was 20 nm, and the 90 volume % particle diameter (D ９０ ) was 29 nm. The content of the organic protective colloid component relative to 100 parts by mass of the metal component (silver nanoparticles A2) in composite nanoparticles A2 was 6.5 parts by mass.

[0154] (Composite nanoparticles A3) A dispersion of composite nanoparticles A3 was prepared in the same manner as the method for synthesizing the dispersion of composite nanoparticles A1, except that the amount of the polymer dispersant used was changed to 5.8 g. For this dispersion, in the same manner as for composite nanoparticles A1, the particle diameter of silver nanoparticles A3 constituting composite nanoparticles A3 and the content of the organic protective colloid component were confirmed, and the 10 volume % particle diameter (D １０ ) was 22 nm, the 50 volume % particle diameter (D ５０ ) was 30 nm, and the 90 volume % particle diameter (D ９０ ) was 41 nm. The content of the organic protective colloid component relative to 100 parts by mass of the metal component (silver nanoparticles A3) in composite nanoparticles A3 was 5.5 parts by mass.

[0155] (Composite nanoparticles A4) A dispersion of composite nanoparticles A4 was prepared in the same manner as the method for synthesizing the dispersion of composite nanoparticles A1, except that the amount of the polymer dispersant used was changed to 2.7 g. For this dispersion, in the same manner as for composite nanoparticles A1, the particle diameter of silver nanoparticles A4 constituting composite nanoparticles A4 and the content of the organic protective colloid component were confirmed, and the 10 volume % particle diameter (D １０ ) was 48 nm, the 50 volume % particle diameter (D ５０ ) was 70 nm, and the 90 volume % particle diameter (D ９０ ) was 104 nm. The content of the organic protective colloid component relative to 100 parts by mass of the metal component (silver nanoparticles A4) in composite nanoparticles A4 was 2.5 parts by mass.

[0156] (Composite Nanoparticle A5) A dispersion of composite nanoparticle A5 was prepared in the same manner as the method for synthesizing the dispersion of composite nanoparticle A1, except that the amount of the polymer dispersant used was changed to 1.1 g. For this dispersion, the particle diameter of silver nanoparticles A5 constituting composite nanoparticle A5 and the content of the organic protective colloid component were confirmed in the same manner as for composite nanoparticle A1. The 10 volume % particle diameter (D １０ ) was 122 nm, the 50 volume % particle diameter (D ５０ ) was 204 nm, and the 90 volume % particle diameter (D ９０ ) was 344 nm. The content of the organic protective colloid component relative to 100 parts by mass of the metal component (silver nanoparticles A5) in composite nanoparticle A5 was 1.0 part by mass.

[0157] (Composite Nanoparticle A6) A dispersion of composite nanoparticle A6 was prepared in the same manner as the method for synthesizing the dispersion of composite nanoparticle A1, except that the amount of the polymer dispersant used was changed to 0.3 g. For this dispersion, the particle diameter of silver nanoparticles A6 constituting composite nanoparticle A6 and the content of the organic protective colloid component were confirmed in the same manner as for composite nanoparticle A1. The 10 volume % particle diameter (D １０ ) was 400 nm, the 50 volume % particle diameter (D ５０ ) was 600 nm, and the 90 volume % particle diameter (D ９０ ) was 750 nm. The content of the organic protective colloid component relative to 100 parts by mass of the metal component (silver nanoparticles A6) in composite nanoparticle A6 was 0.3 part by mass.

[0158] Although the particle diameters of each of the composite nanoparticles A1 to A6 are as described above, in Examples 9 to 11 and 18 to 25, two types of silver nanoparticles (silver nanoparticles A1 and silver nanoparticles A5) were used as a mixture. Specifically, the mixing ratio of silver nanoparticles A1 to silver nanoparticles A5 was A1 / A5 = 80 / 20 in Example 9, A1 / A5 = 60 / 40 in Example 10 and Examples 18 to 25, and A1 / A5 = 20 / 80 in Example 11. Therefore, the "average particle diameter D of silver nanoparticles" in Tables 5 to 9 and 13 to 14 ５０In the example where two types of silver nanoparticles are mixed, the central particle diameter D of the mixture is obtained by mixing silver nanoparticle A1 and silver nanoparticle A5 in the same mass ratio as above. ５０ This represents the central particle size D obtained from the image obtained by observing the mixture with a transmission electron microscope. For example, in Example 10, a dispersion of composite nanoparticles A1 and a dispersion of composite nanoparticles A5 were mixed in a mass ratio of A1 / A5 = 60 / 40, and the central particle size D was measured from the image obtained by observing the mixture with a transmission electron microscope. ５０ The central particle size of silver nanoparticles is 143 nm. ５０ This is shown in Table 6.

[0159] [Preparation of Silver Sintering Paste Compositions] Silver sintering pastes for the examples and comparative examples were prepared to have the compositions shown in Tables 5-9 and 13-14. Specifically, first, the composite nanoparticle dispersion, each powder material, and organic solvent (butyl triglycol) were weighed into containers in predetermined amounts using an electronic balance. Subsequently, each material was uniformly mixed in a planetary (rotating and revolving) defoaming agitator, and then passed through a three-roller to obtain each silver sintering paste composition.

[0160] Furthermore, the particle size distribution (volume distribution) of the composite nanoparticles A1 to A5 dispersions and silver powder used in the examples and comparative examples was measured using a laser diffraction scattering particle size distribution analyzer (Microtrac-Bell "MT3000II"). As a result, no particles larger than 1 μm were detected from silver nanoparticle A1 contained in the composite nanoparticle A1 dispersion. Similarly, no particles larger than 1 μm were detected from each of the silver nanoparticles A2 to A5 contained in the composite nanoparticles A2 to A5 dispersions. On the other hand, no particles smaller than 1 μm were detected from the silver powder. In other words, each of the silver nanoparticles A1 to A5 contained in the composite nanoparticles A1 to A5 dispersions as raw materials corresponds to silver nanoparticles with a particle size of less than 1 μm in the composition. The silver powder corresponds to silver powder with a particle size of 1 μm or more in the composition.

[0161] [Particle size distribution of the silver sintering paste composition prepared in Example 23] Figure 1 and Table 1 show the results of measuring the particle size distribution of the silver sintering paste composition prepared in Example 23.

[0162]

[0163] As is clear from Figure 1, in the silver sintering paste composition prepared in Example 23, the particle distribution is such that small particle groups (silver nanoparticles) with a particle diameter of less than 1 μm and large particle groups (silver powder) with a particle diameter of 1 μm or more exist separately. The central particle diameter (D) of silver particles (B) (silver powder) with a particle diameter of 1 μm or more. ５０ The central particle diameter of the raw material is the same as that of 3.8 μm. Furthermore, as can be seen from Table 1, the central particle diameter of the silver particles (B) in the silver sintering paste composition prepared in Example 23 (the particle diameter of the cumulative 75% in Figure 1 and Table 1) is in the range of 3.27 to 3.89 μm.

[0164] On the other hand, as is clear from Table 1, in the silver sintering paste composition prepared in Example 23, the silver-containing metal nanoparticles (A) (silver nanoparticles) with a particle size of less than 1 μm have a 10 volume% particle size (5% cumulative particle size in Figure 1 and Table 1) in the range of 61 to 72 nm, a 50 volume% particle size (25% cumulative particle size in Figure 1 and Table 1) in the range of 122 to 145 nm, and a 90 volume% particle size (45% cumulative particle size in Figure 1 and Table 1) in the range of 240 to 290 nm.

[0165] <Examples using the non-pressure firing method> [Preparation of evaluation samples] In the evaluation samples (Examples 1 to 25 and Comparative Examples 1 to 5), a sintered body of each silver sintering paste was used as a bonding material to bond an Au / Ni / Pd plated Si chip [1 mm square (1 mm x 1 mm square)] to a Cu substrate that had been subjected to Au / Ni / Pd plating by the procedure (coating step, placement step, firing step) described in the section [Modes for Carrying Out the Invention] above. Specifically, evaluation samples were prepared by the following procedure and used as evaluation samples.

[0166] Twenty evaluation samples (chips bonded to a substrate) were prepared for each silver sintering paste. Ten of these samples were used for the evaluation of the initial bonding strength, as described below. The remaining ten samples were subjected to thermal shock testing and used to evaluate the bonding strength after the thermal shock test.

[0167] (Coating Process) In the coating process, a dispenser (ML-6000X, manufactured by Musashi Engineering Co., Ltd.) was used to drop silver sintering paste onto the surface of a Cu substrate that had been plated with Au / Ni / Pd. The amount dropped was 0.1 μL.

[0168] (Placement Process) In the placement process, a die bonder (Dr. Tresky "T-3000-FC3") was used to place Au / Ni / Pd plated Si chips (1 mm square) onto the substrate surface coated with silver sintering paste. The average thickness (wet thickness) of the silver sintering paste after the Si chips were placed was 60 μm.

[0169] (Firing Process) In the firing process, the substrate on which the chips were placed was fired using an oven. The firing was performed without pressure, and the firing temperature profiles of the oven were as follows (1) to (3).

[0170] (1) Heat from room temperature (25°C) to 200°C at a rate of 5°C / min, (2) maintain at 200°C for 60 minutes, (3) cool from 200°C to room temperature (25°C) at a rate of 5°C / min.

[0171] During the firing process, the silver sintering paste was sintered, forming a sintered body (bonding layer). The average thickness of the bonding layer (sintering thickness) was 30 μm.

[0172] [Evaluation and Judgment] For each evaluation sample (Examples 1 to 25 and Comparative Examples 1 to 5), the bonding strength (die shear strength) and thermal shock resistance (bonding strength after thermal shock test) were verified to determine whether a silver sintering paste capable of solving the problem of the present invention was obtained.

[0173] [Bonding Strength (Initial)] (Test Method) The bonding strength (die shear strength) of the silver sintering paste sintered body was measured using a bond tester (Sigma, manufactured by xyztec). The bonding strength of the silver sintering paste (bonding strength between the Cu substrate and the Si chip) was evaluated from the measured values ​​according to the criteria shown in Table 2. For each evaluation sample, the average value of 10 samples was calculated and evaluated according to the criteria shown in Table 2. From the viewpoint of bonding strength for actual use in this application, silver sintering paste with a rating of c or higher was considered acceptable.

[0174] (Judgment criteria)

[0175]

[0176] [Thermal Shock Resistance (Bond Strength After Thermal Shock Test)] (Test Method) A thermal shock test (heat cycle test in accordance with JIS C 60068-2-14:2011) was performed using a thermal shock tester (WINTECH NT1020 manufactured by Tokyo Rikakikai Co., Ltd.) in the following cycle: holding at -55°C for 30 minutes, heating to 125°C, holding at 125°C for 30 minutes, and cooling to -55°C. This cycle was considered one cycle and was repeated 1000 times.

[0177] After this thermal shock test (1000 cycles), the joint strength was measured using the same method as described above, and the average of the joint strengths of 10 samples was evaluated as the joint strength after the thermal shock test according to the criteria shown in Table 3. From the viewpoint of thermal shock resistance in actual use for this application, silver sintering paste with a rating of C or higher was considered acceptable.

[0178] (Judgment criteria)

[0179]

[0180] [Overall Assessment] Based on the assessment of each evaluation item, an overall assessment was made according to the criteria shown in Table 4.

[0181]

[0182] [Verification Results and Discussion] The verification results are shown in Tables 5 to 9. In Tables 5 to 9, the "parts by mass" indicating the proportion of silver nanoparticles A1 to A6 does not include the mass of the protective colloid, and refers to the mass of silver nanoparticles only.

[0183]

[0184] (Comparative Example 1) Comparative Example 1 is a conventional example in which the silver component is a blend of silver nanoparticles A1 (small particle size component) and silver powder (large particle size component), with a mass ratio of 40 / 60, and does not contain inorganic fillers. In Comparative Example 1, although the bonding strength (initial) was judged as b, which is at a level that is not problematic for practical use, the bonding strength decreased after the thermal shock test, resulting in a d (failure) in the thermal shock resistance item, and thus the overall judgment was a D rank. It can be presumed that the crystal grains of the silver nanoparticles grew due to the thermal load of the thermal shock test, and the crystal interface (grain boundary) moved (reconstructed), causing minute voids (micropores) in the bonding layer to propagate into cavities (voids) and cracks, which in turn caused defects in the bonding layer and led to embrittlement.

[0185] (Example 2) Example 2 is a comparative example of Comparative Example 1 with a particle size (center particle size) of 50% by volume (D ５０ This example involves adding 0.1 parts by mass of a 200 nm silver ion scavenger (zirconium compound-based silver ion scavenger) per 100 parts by mass of silver nanoparticles. In Example 2, the bonding strength after the thermal shock test was improved to a practically acceptable level, a B rating. It is presumed that this improvement is due to the inclusion of the silver ion scavenger in the silver sintering paste, which suppresses the reaction caused by silver ions originating from the silver nanoparticles (a reaction that leads to the growth of crystal grains of the silver nanoparticles) by the silver ion scavenger capturing the silver ions. As a result, the aggregation of minute voids (micropores) in the bonding layer is suppressed, thereby preventing the bonding layer from becoming brittle. Furthermore, the bonding strength (initial) remained at a practically acceptable level (B rating), resulting in an overall B rank.

[0186] Here, X-ray radiographs of evaluation samples from Example 2 and Comparative Example 1 before and after the thermal shock test are shown in Figures 2 to 5, observed using an X-ray transmission inspection device (TI-X500s manufactured by Techno Horizon Co., Ltd.). In Example 2, no change was observed in the X-ray radiograph before (Figure 2) and after (Figure 3) the thermal shock test. On the other hand, in Comparative Example 1, a shadow was observed in the X-ray radiograph after (Figure 5) the thermal shock test compared to before (Figure 4) in the area where the chip was placed. This shadow is thought to be due to the observation of voids and cracks in the bonding layer beneath the chip. In other words, in Comparative Example 1, it can be estimated that the bonding layer became brittle due to the thermal load applied to the bonding layer during the thermal shock test, causing minute voids inside the bonding layer to aggregate and coarseen, leading to the propagation of large voids and cracks, and thus reducing the bonding strength after the thermal shock test. In contrast, in Example 2, by including a silver ion scavenging agent in the silver sintering paste, the aggregation of minute voids (micropores) within the bonding layer was suppressed. As a result, no large voids or cracks were observed after the thermal shock test, and it can be estimated that the bonding strength after the thermal shock test was maintained at the same level as before the thermal shock test.

[0187] (Comparative Examples 2-3) Comparative Example 2 is an example based on Example 2, in which the inorganic filler was changed to silica particles that do not have a silver ion trapping effect. In Comparative Example 2, similar to Comparative Example 1, the bonding strength after the thermal shock test decreased, resulting in a d rating (failure) in the thermal shock resistance item, and thus an overall rating of D. It can be presumed that the aggregation of minute voids (micropores) in the bonding layer due to the thermal load of the thermal shock test was not suppressed, and the voids (micropores) progressed into cavities (voids) and cracks (cracks), causing the bonding layer to become brittle.

[0188] Comparative Example 3 is an example based on Example 2, in which the inorganic filler was changed to Bi-Zn-B composite oxide particles (bismuth-based glass particles) that do not have a silver ion scavenging effect. In Comparative Example 3, the bonding strength before thermal shock was low, and the bonding strength after the thermal shock test also decreased, resulting in a d rating (failure) in the thermal shock resistance item, and thus an overall rating of D.

[0189] (Examples 1 and 3-5) These are examples based on Example 2, in which the particle size of the silver ion scavenger was changed. As the particle size of the silver ion scavenger decreased, the bonding strength (initial) decreased. Conversely, as the particle size of the silver ion scavenger increased, the bonding strength after the thermal shock test decreased, and there was a tendency for the thermal shock resistance to decrease.

[0190] In detail, the central particle size (D) of the silver ion scavenger ５０ Example 1, in which the central particle size (D) of the silver ion scavenger is 100 nm, is ５０ Compared to Example 2, where the central particle size (D) of the silver ion scavenger was 200 nm, the initial bonding strength was slightly reduced, and consequently, the bonding strength after the thermal shock test was also slightly reduced. However, both remained at a level that poses no practical problems (grade b), so the overall evaluation was B. From these results, it can be inferred that the smaller the central particle size of the silver ion scavenger, the more it negatively affects the low-temperature sinterability of the silver sintering paste, thereby inhibiting the sintering of a dense bonding layer, and thus reducing the initial bonding strength. Furthermore, from the results of Example 1, it can be inferred that the central particle size (D) of the silver ion scavenger is important. ５０ It can be estimated that the bonding strength (initial) will further decrease when the central particle diameter (D) of the silver ion scavenger falls below 100 nm. ５０ ) is preferably 100 nm or more.

[0191] Furthermore, the central particle size (D) of the silver ion scavenging agent ５０ In Example 4, where the central particle size (D) of the silver ion scavenger was 400 nm, the bonding strength (initial) was at the same level as Example 2, receiving a B rating. However, the bonding strength decreased after the thermal shock test, resulting in a C rating for thermal shock resistance. Furthermore, the central particle size (D) of the silver ion scavenger was also affected. ５０ In Example 5, where the central particle diameter (D) of the silver ion scavenger was increased to 1000 nm, the bonding strength after the thermal shock test was further reduced. From the results of Examples 4 and 5, it can be inferred that the larger the central particle diameter of the silver ion scavenger, the more unevenly the silver ion scavenger is distributed within the bonding layer, making it difficult for the silver ion scavenging effect to be exerted and the brittleness suppression effect of the bonding layer to be exerted, thus reducing the bonding strength after the thermal shock test. Therefore, from the viewpoint of thermal shock resistance, the central particle diameter (D) of the silver ion scavenger should be increased. ５０ ) is preferably 300 nm or less.

[0192] Based on the above results, from the viewpoint of achieving a balance between bonding strength (initial) and thermal shock resistance, the central particle size (D) of the silver ion scavenger is considered to be the optimal size. ５０ The range of ) is preferably 100 to 300 nm.

[0193] (Example 6) This is an example in which the type of silver ion scavenger was changed compared to Example 5, but no difference was observed from Example 5. In other words, there was no difference due to the type of silver ion scavenger, and the difference in evaluation of Examples 1 to 6 was due to the central particle size (D) of the silver ion scavenger. ５０ This can be attributed to the difference in ).

[0194]

[0195] (Comparative Example 4 and Examples 7-13) Central particle diameter (D) of silver nanoparticles (silver-containing metal nanoparticles (A)) ５０ Compared to Example 2, where the central particle diameter (D) of the silver nanoparticles (silver-containing metal nanoparticles (A)) is 102 nm, ５０ This is an example of changing the silver nanoparticle D. ５０ The bonding strength (initial) improved up to about 143 nm, but as the wavelength increased further, there was a tendency for the bonding strength (initial) to decrease.

[0196] In detail, the D of silver nanoparticles ５０ Comparative Example 4, with a particle size of 20 nm, showed insufficient bonding strength (initial) (rated D), resulting in an overall rating of D. Silver nanoparticles D ５０ Example 7 (30 nm), which had a larger size, achieved a practical passing level (C rating) for both bonding strength (initial) and thermal shock resistance, resulting in an overall rating of C. Furthermore, Examples 8 (70 nm), 2 (102 nm), 9 (122 nm), 10 (143 nm), 11 (184 nm), 12 (204 nm), and 13 (600 nm) all achieved a rating of B or higher for both bonding strength (initial) and thermal shock resistance, resulting in an overall rating of A or B. Therefore, the D of silver nanoparticles ５０ When the wavelength was within the range of 30 to 600 nm, both the bonding strength (initial) and thermal shock resistance achieved a practical acceptable level (grade C or higher).

[0197] On the other hand, the silver ion scavenger D５０ and silver nanoparticles ５０ Focusing on the relationship, the silver ion scavenger D ５０ is silver nanoparticle D ５０ In Examples 8 to 13, which were within the range of 0.3 to 3 times the target, both the bonding strength (initial) and thermal shock resistance were at a high level (rated a or b), resulting in an overall rating of A or B. Silver ion scavenger D ５０ is silver nanoparticle D ５０ When the ratio is within the range of 0.3 to 3 times, it is presumed that the silver nanoparticles and silver ion scavenger are not unevenly distributed within the bonding layer, and the particles of the silver ion scavenger can be uniformly dispersed within the bonding layer. Therefore, it is thought that the low-temperature sinterability of the bonding layer can be maximized, and a high degree of balance between bonding strength and thermal shock resistance can be achieved.

[0198]

[0199] (Examples 14-16 and Comparative Example 5) The central particle diameter (D) of silver powder (silver particles (B) ５０ Compared to Example 2, where the central particle diameter (D) of the silver powder (silver particles (B)) is 3.8 μm, ５０ This is an example of a change made to silver powder D. ５０ The bonding strength (initial) improved up to about 3.8 μm, but as the thickness increased further, there was a tendency for the bonding strength (initial) to decrease.

[0200] In detail, Examples 14 (1.5 μm), 2 (3.8 μm), and 15 (12.0 μm) all received a B rating for both initial bonding strength and thermal shock resistance, resulting in an overall B rank. In contrast, Example 16 (20.0 μm) saw a decrease in both initial bonding strength and thermal shock resistance to a C rating, resulting in an overall C rank. Furthermore, Comparative Example 5 (30.0 μm) had insufficient initial bonding strength (d rating), resulting in an overall D rank. Therefore, the silver powder D ５０ When the thickness was within the range of 1.5 to 20.0 μm, both the bonding strength (initial) and thermal shock resistance achieved a practical acceptable level (grade C or higher).

[0201] (Example 17) This example shows a change in the shape of the silver powder (silver particles (B)) compared to Example 2. However, the bonding strength (initial) and thermal shock resistance were both rated as B, similar to Example 2, and the overall rating was B.

[0202] <Summary of Tables 5-7> From the results in Tables 5-7, silver-containing metal nanoparticles with a particle diameter of less than 1 μm (A), silver particles with a particle diameter of 1 μm or more (B), a silver ion scavenger, and an organic solvent are included, and the central particle diameter of the silver-containing metal nanoparticles (D ５０ The diameter is 30 to 600 nm, and the central particle diameter (D) of the silver particle (B) is 30 to 600 nm. ５０ It was found that when the thickness is 1.5 to 20 μm, the problem of the present invention is solved and a paste composition (silver sintering paste) that can improve thermal shock resistance is provided.

[0203]

[0204] (Examples 18-21) These are examples in which the ratio of silver ion scavenger to silver nanoparticles (silver-containing metal nanoparticles (A)) was changed compared to Example 10. As the ratio of silver ion scavenger increased, the bonding strength (initial) tended to decrease, while the thermal shock resistance tended to improve. Examples 19 (0.05 parts by mass), 10 (0.1 parts by mass), and 20 (1 part by mass), in which the ratio of silver ion scavenger to 100 parts by mass of silver nanoparticles was in the range of 0.05 to 1 part by mass, both achieved an A rating for bonding strength (initial) and thermal shock resistance, and were found to be suitable from the viewpoint of having an excellent balance between bonding strength and thermal shock resistance (overall rating A rank). On the other hand, both Example 21 (5 parts by mass), which had a large ratio of silver ion scavenger, and Example 18 (0.025 parts by mass), which had a small ratio of silver ion scavenger, maintained a practical acceptable level, and the overall rating was B rank.

[0205]

[0206] (Examples 22-25) These are examples in which the mass ratio of silver nanoparticles (silver-containing metal nanoparticles (A)) and silver powder (silver particles (B)) was varied compared to Example 10. In a wide range of silver nanoparticle / silver powder ratios from 75 / 25 to 5 / 95, both bonding strength and thermal shock resistance were achieved at a high level. Example 22 (75 / 25, B rank), Example 23 (50 / 50, A rank), Example 10 (40 / 60, A rank), Example 24 (10 / 90, A rank), and Example 25 (5 / 95, B rank) all received an overall rating of B rank or higher.

[0207] <Examples using the pressure firing method> [Preparation of evaluation samples] In the evaluation samples (Examples 2-2, 4-2, 7-2, 10-2, 12-2, 16-2, 19-2, 20-2, 23-2, 24-2 and Comparative Examples 1-2, 2-2), the sintered bodies of each silver sintering paste were used as bonding materials to join Au-plated Si chips [3 mm square (3 mm x 3 mm)] to Cu substrates that had been subjected to Au plating treatment by the procedure (coating step, pre-drying step, placement step, firing step) described in the above section [Modes for Carrying Out the Invention]. Specifically, the evaluation samples were prepared by the following procedure.

[0208] Twenty evaluation samples (chips bonded to a substrate) were prepared for each silver sintering paste. Ten of these samples were used for the evaluation of the initial bonding strength, as described below. The remaining ten samples were subjected to thermal shock testing and used to evaluate the bonding strength after the thermal shock test.

[0209] (Coating process) Using a metal mask (200 μm thick) configured to form a 5 mm square pattern (5 mm x 5 mm), silver sintering paste was printed and applied to the surface of a copper-plated Cu substrate.

[0210] (Pre-drying process) The substrate coated with silver sintering paste was placed in an oven heated to 130°C and left to stand for 30 minutes to pre-dry the silver sintering paste.

[0211] (Placement Process) Using a die bonder (Dr. Tresky "T-3000-FC3"), a Si chip (3 mm square) with Au plating was placed on the substrate surface to which dry silver sintering paste had been applied.

[0212] (Firing Process) Si chips placed on silver sintering paste were pressure-fired using a pressure firing device (HTM-3000, manufactured by Meisho Kiko Co., Ltd.) by pressing a preheated hot plate at 310°C onto them at a pressure of 10 MPa for 110 seconds. After that, the hot plate was released and the chips were allowed to cool at room temperature (25°C) for at least 60 minutes.

[0213] During the firing process, the silver sintering paste was sintered, forming a sintered body (bonding layer). The average thickness of the bonding layer (sintering thickness) was 55 μm.

[0214] [Evaluation and Judgment] For each evaluation sample (examples, comparative examples), the bonding strength (die shear strength) and thermal shock resistance (bonding strength after thermal shock test) were verified to determine whether a silver sintering paste capable of solving the problem of the present invention was obtained.

[0215] [Bonding Strength (Initial)] (Test Method) A bond tester (Sigma, manufactured by xyztec) was used to measure the bonding strength (die shear strength) of the silver sintering paste sintered body. The bonding strength of the silver sintering paste (bonding strength between the Cu substrate and the Si chip) was evaluated from the measured values ​​according to the criteria shown in Table 10. For each evaluation sample, the average value of 10 samples was calculated and evaluated according to the criteria shown in Table 10. From the viewpoint of bonding strength for actual use in this application, silver sintering paste with a rating of c or higher was considered acceptable.

[0216] Furthermore, in the evaluation of the example using the pressure firing method, it was used for a larger area joint (3 mm square) than in the example using the non-pressure firing method (1 mm square), making it difficult to obtain high joint strength and indicating that the conditions were more stringent.

[0217] (Judgment criteria)

[0218]

[0219] [Thermal Shock Resistance (Bond Strength After Thermal Shock Test)] (Test Method) After a thermal shock test (1000 cycles) similar to that used in the example with no-pressure firing method, the bond strength was measured using the same method as above, and the average value of the bond strength of 10 samples was evaluated as the bond strength after the thermal shock test according to the criteria shown in Table 11. From the viewpoint of thermal shock resistance in actual use for this application, silver sintering paste with a rating of c or higher was considered acceptable.

[0220] Furthermore, in the evaluation of the example using the pressure firing method, a larger area joint (3 mm square) was used compared to the example using the non-pressure firing method (1 mm square), which means that a decrease in strength is more likely to occur in the thermal shock test, indicating that the conditions are more stringent.

[0221] (Judgment criteria)

[0222]

[0223] [Overall Assessment] Based on the assessment of each evaluation item, an overall assessment was made according to the criteria shown in Table 12.

[0224]

[0225] [Verification Results and Discussion] The verification results are shown in Tables 13 and 14. In Tables 13 and 14, the "mass portion" indicating the proportions of silver nanoparticles A1, A3, and A5 means the mass of silver nanoparticles only, and does not include the mass of the protective colloid.

[0226]

[0227] (Comparative Examples 1-2, 2-2) Comparative Example 1-2 is an example in which the paste composition of Comparative Example 1 was used by the pressure firing method, and Comparative Example 2-2 is an example in which the paste composition of Comparative Example 2 was used by the pressure firing method. However, similar to the example in which it was used by the non-pressure firing method, the strength decreased significantly in the thermal shock test, and the thermal shock resistance was insufficient (rated D), resulting in an overall rating of D.

[0228] (Examples 2-2, 4-2) Example 2-2 is an example in which the paste composition of Example 2, in which 0.1 parts by mass of silver ion scavenging agent C2 was added to 100 parts by mass of silver nanoparticles compared to Comparative Example 1, was used by a pressure firing method. Similar to the example in which it was used by a non-pressure firing method, the decrease in strength in the thermal shock test was suppressed compared to Comparative Examples 1-2 and 2-2, the thermal shock resistance improved to a B rating, and the overall rating was B rank. Therefore, it was found that the effects of the present invention can be obtained even when used by a pressure firing method, and a paste composition (silver sintering paste) that can improve thermal shock resistance is provided.

[0229] In Example 4-2, similar to the example using the non-pressure firing method (Example 4), the bonding strength was rated as b, the thermal shock resistance as c, and the overall rating was C.

[0230]

[0231] (Examples 7-2, 10-2, 12-2, 16-2, 19-2, 20-2, 23-2, 24-2) Examples 7, 10, 12, 16, 19, 20, 23, and 24 were used in a pressure firing method, but the evaluation results (ranks) were the same as those for the non-pressure firing method, and the overall judgment was C rank or higher. Therefore, it was found that the effects of the present invention can be obtained and thermal shock resistance can be improved even when Examples 1 to 25, verified in Tables 5 to 9, are used in a pressure firing method. Furthermore, it can be said that the preferred embodiments based on the evaluation results (ranks) verified in Tables 5 to 9 are the same even when used in a pressure firing method.

[0232] (Effects Obtained) From the above verification results, it was found that when a silver ion scavenger is included in a silver sintering paste containing silver-containing metal nanoparticles (A) with a particle size of less than 1 μm and silver particles (B) with a particle size of 1 μm or more, the problem of this invention is solved and thermal shock resistance can be improved. Furthermore, the central particle size (D) of the silver ion scavenger ５０ If the size is 100-300 nm, the central particle size (D) of the silver ion scavenger is 100-300 nm. ５０ ) is the central particle diameter (D) of the silver-containing metal nanoparticle (A). ５０It was found that when the ratio is 0.3 to 3 times the amount of silver ion scavenger, and when the proportion of silver ion scavenger is 0.05 to 1 part by mass per 100 parts by mass of silver-containing metal nanoparticles (A), a silver sintering paste with a better balance in terms of bonding strength and thermal shock resistance can be obtained.

[0233] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2025-054483 filed on 27 March 2025 and Japanese Patent Application No. 2026-035429 filed on 5 March 2026, the contents of which are incorporated herein by reference.

[0234] The paste composition of the present invention can be used as a bonding paste composition for laminates in the field of electronics, such as circuit boards, electronic components, thermal substrates, substrates for LED packages, semiconductor substrates, thin-film circuit boards, and resistor substrates, and has excellent heat dissipation properties. For this reason, the paste composition of the present invention is preferably used as a die-attach paste for forming a bonding layer in a laminate on which semiconductor chips with an operating temperature of 200°C or higher, such as power semiconductors, are mounted (for example, a paste interposed between an electronic substrate and a semiconductor chip and / or a cooler (heat sink)).

Claims

1. The material comprises silver-containing metal nanoparticles (A) having a particle diameter of less than 1 μm, silver particles (B) having a particle diameter of 1 μm or more, a silver ion scavenger (C), and an organic solvent (D), wherein the central particle diameter (D) of the silver-containing metal nanoparticles (A) ５０ The diameter is 30 to 600 nm, and the central particle diameter (D) of the silver particle (B) is 30 to 600 nm. ５０ A paste composition in which the particle size is 1.5 to 20 μm.

2. The paste composition according to claim 1, wherein the silver ion scavenging agent (C) is an inorganic compound having cation scavenging ability.

3. The central particle size (D) of the silver ion scavenging agent (C). ５０ The paste composition according to claim 1 or 2, wherein the n is 100 to 300 nm.

4. The central particle size (D) of the silver ion scavenging agent (C). ５０ ) is the central particle diameter (D) of the silver-containing metal nanoparticle (A). ５０ The paste composition according to any one of claims 1 to 3, wherein the ratio is 0.3 to 3 times.

5. The paste composition according to any one of claims 1 to 4, wherein the proportion of the silver ion scavenger (C) is 0.05 to 1 part by mass per 100 parts by mass of the silver-containing metal nanoparticles (A).

6. The paste composition according to any one of claims 1 to 5, wherein the mass ratio of the silver-containing metal nanoparticles (A) to the silver particles (B) is former / latter = 75 / 25 to 5 / 95.

7. A paste composition according to any one of claims 1 to 6, which does not contain a binder resin.

8. A paste composition according to any one of claims 1 to 7, which is a die attach paste.

9. A method for manufacturing a laminate, comprising: a coating step of applying a paste composition according to any one of claims 1 to 8 onto a first member to be joined; a placing step of placing a second member to be joined on the applied paste composition; and a firing step of firing the paste composition interposed between the first member to be joined and the second member to be joined to obtain a laminate in which a bonding layer, which is a sintered body, is interposed between the first member to be joined and the second member to be joined.

10. The manufacturing method according to claim 9, wherein in the firing step, the paste composition is fired at a firing temperature of 100 to 300°C without pressure.

11. The manufacturing method according to claim 9 or 10, wherein in the firing step, the paste composition is subjected to pressure firing at a firing temperature of 150 to 350°C.

12. A laminate comprising a first member to be joined, a second member to be joined, and a bonding layer interposed between the first member to be joined and the second member to be joined, wherein the bonding layer is a sintered body of the paste composition according to any one of claims 1 to 8.

13. The laminate according to claim 12, wherein the first member to be joined or the second member to be joined is a component of an electronic device, and the electronic device includes a semiconductor chip whose operating temperature is 200°C or higher.

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