JP2022032970A - Method for producing bonded body - Google Patents

Abstract

To provide a method for producing a bonded body by using a metal paste that has excellent sinterability at low temperatures and allows a plurality of metal members to be bonded together, and a metal paste.SOLUTION: The present invention relates to a method for producing a bonded body, the method comprising a step for heating a metal paste by interposing it between a plurality of metal members. The metal paste contains a metal oxide A, a polymer B, and a diol C. The polymer B contains at least one selected from a carboxy group and an imino group, and a polyoxyalkylene group. The content of the metal oxide A in the metal paste is at least 50 mass%. The present invention further relates to a metal paste comprising a metal oxide A, a polymer B, and a diol C, where the polymer B contains at least one selected from a carboxy group and an imino group and a polyoxyalkylene group, and the content of the metal oxide A is at least 50 mass%.SELECTED DRAWING: None

Description

The present invention relates to a method for producing a bonded body using a metal paste, and a metal paste.

Since metal fine particles can form a coating film having electrical conductivity and metallic luster by sintering, formation of circuits and electrodes in various electronic components or joining of members, printing and painting that require the design of metallic luster, etc. It is used in.
Patent Document 1 describes a paste-like metal fine particle composition that becomes a solid metal having excellent adhesive strength, electrical conductivity, etc. by sintering metal fine particles at a relatively low temperature when heated, a method for joining metal members, and the like. For the purpose of providing, heat-sinterable metal fine particles having an average particle size of 0.005 μm to 0.2 μm and whose surface is coated with an organic substance having a polar group and having 3 to 24 carbon atoms and an acidic functional group. A paste-like metal fine particle composition obtained by mixing a polymer dispersant having a basic functional group and a volatile dispersion medium having a boiling point of 70 ° C. to 300 ° C. and then aging under predetermined conditions, said paste-like. A method for joining metal members using a metal fine particle composition and the like are described.
Further, in Patent Document 2, for the purpose of providing silver fine particles suitable as a pigment for metallic glossy ink and a dispersion liquid thereof, 1 to 15% by mass of a silver compound having an average particle size of 10 μm or less is dispersed in a polyol solvent. It is obtained by adding 5 to 80% by mass of a water-soluble polymer having excellent adsorptivity to silver as an agent with respect to the silver content in the silver compound, and then heating and reducing the solution at 100 ° C. or lower. A polyol solvent in a silver colloidal solution composed of silver fine particles having a coating layer made of a water-soluble polymer on the surface, an average particle size of 30 nm or less, and monodisperse, and silver fine particles. A silver fine particle dispersion prepared by substituting with a water or alcohol-based polar solvent is described.
Further, in Patent Document 3, for the purpose of providing a metal fine particle dispersion having excellent storage stability under high temperature, hydroxyacetone and propylene glycol are contained, and the cumulant average particle size of the metal fine particles is 0.01 μm or more and 0.1 μm or less. A dispersion of metal fine particles is described.

Japanese Unexamined Patent Publication No. 2014-111800 Japanese Unexamined Patent Publication No. 2010-285695 Japanese Unexamined Patent Publication No. 2020-105624

In recent years, with increasing awareness of energy saving and power saving, the demand for power semiconductor devices used for controlling or exchanging electric power is increasing.
The bonding of power semiconductor devices affects the quality and reliability of device functions, but there is a demand for bonding agents capable of low temperature bonding in place of conventional solder bonding for power semiconductor devices. As such a bonding agent, studies on metal sintering bonding using sintering of metal fine particles are underway.
However, in the technique of Patent Document 1, since the temperature of sintering and joining is as high as over 200 ° C., the requirements for sinterability and bonding property at low temperature are not satisfied. Further, since the technique of Patent Document 2 is a technique of silver fine particles used as a pigment for metallic luster ink, it does not contain silver fine particles in a high content and is difficult to apply to low temperature bonding.
Therefore, further improvement in sinterability and bondability of the metal paste at low temperatures is required.
An object of the present invention is to provide a method for producing a bonded body using a metal paste which is excellent in sinterability at a low temperature and can bond a plurality of metal members at a low temperature, and a metal paste.

The present inventors have described that a metal paste containing a metal oxide, a polymer containing a specific functional group, and a diol and having a metal oxide content in a specific range has a low heat treatment temperature. Also, paying attention to the rapid progress of sintering and joining, it was found that the above problems can be solved. That is, the present invention provides the following [1] and [2].
[1] A method for manufacturing a bonded body, which comprises a step of interposing a metal paste between a plurality of metal members and heating the bonded body.
The metal paste contains metal oxide A, polymer B, and diol C,
The polymer B contains at least one selected from a carboxy group and an imino group and a polyoxyalkylene group.
A method for producing a bonded body, wherein the content of the metal oxide A in the metal paste is 50% by mass or more.
[2] Containing metal oxide A, polymer B, and diol C,
The polymer B contains at least one selected from a carboxy group and an imino group and a polyoxyalkylene group.
A metal paste having a metal oxide A content of 50% by mass or more.

According to the present invention, it is possible to provide a method for producing a bonded body using a metal paste which is excellent in sinterability at a low temperature and can bond a plurality of metal members at a low temperature, and a metal paste.

[Metal paste]
The metal paste of the present invention contains a metal oxide A, a polymer B, and a diol C, wherein the polymer B contains at least one selected from a carboxy group and an imino group and a polyoxyalkylene group, and is metal oxidized. The content of the substance A is 50% by mass or more.
In the present invention, "sinterability at low temperature" means that metal sintering occurs in a normal pressure and a low temperature environment of 100 ° C. or lower to develop conductivity, and "low temperature sinterability". Also called. Further, the bondability of a plurality of metal members under normal pressure and a low temperature environment of 100 ° C. or lower is also referred to as "low temperature bondability". Further, in the present invention, "polyoxyalkylene" is also referred to as "polyalkylene oxide".

According to the present invention, it is excellent in low temperature sinterability and has an excellent effect that a plurality of metal members can be joined at a low temperature. The reason is not clear, but it can be considered as follows.
The metal paste of the present invention contains a polymer containing at least one selected from a metal oxide, a carboxy group and an imino group and a polyoxyalkylene group, and a diol, and the content of the metal oxide is within a specific range. be. Therefore, in the process of producing metal nanoparticles by reduction of metal oxide, aggregation of metal nanoparticles is suppressed, generation and sintering of metal nanoparticles having a uniform particle size proceed rapidly, and heat treatment at a low temperature is performed. Even so, it is possible to form a metal sintered body having high conductivity. Further, since the metal paste of the present invention goes through a process of forming metal nanoparticles from metal oxides, the metal nanoparticles present in the metal sintered body formed from the metal paste are close to a close-packed structure. It becomes a form. Therefore, it is considered possible to form a metal sintered body having a low volume resistivity despite the heat treatment at a low temperature.
Furthermore, heat is generated in the process of reducing metal oxides to metal nanoparticles. As a result, it is considered that the bonded temperature of the produced metal nanoparticles is reached and a plurality of metal members can be satisfactorily bonded despite the heat treatment at a low temperature. Further, since the bonding using the metal paste of the present invention is considered to be a process via metal nanoparticles, it is presumed that the bonding strength is increased due to the anchor effect on the metal member or the like.
Further, since the metal paste of the present invention can be bonded by heat treatment at a low temperature, it is considered that peeling is unlikely to occur due to a difference in expansion rate from the metal member.

<Metal oxide A>
The metal paste of the present invention contains a metal oxide A from the viewpoint of improving low-temperature sinterability and low-temperature bondability.
The metal (metal atom) constituting the metal oxide A is a Group 4 transition metal such as titanium and zirconium, a Group 5 transition metal such as vanadium and niob, and a Group 6 transition metal such as chromium, molybdenum and tungsten. Group 7 transition metals such as metals, manganese, technetium and renium, Group 8 transition metals such as iron and ruthenium, Group 9 transition metals such as cobalt, rhodium and iridium, and group 9 transition metals such as nickel, palladium and platinum. Group 10 transition metals, Group 11 transition metals such as copper, silver and gold, Group 12 transition metals such as zinc and cadmium, Group 13 metals such as aluminum, gallium and indium, germanium, tin and lead. 14th group metal and the like can be mentioned. As the metal constituting the metal oxide A, one kind may be used as a single metal, or two or more kinds may be used in combination as an alloy. Above all, from the viewpoint of improving low-temperature sinterability and low-temperature bondability, the metal oxide A preferably contains oxides of transition metals of Group 4 to Group 11 and of the 4th to 6th periods, and is more preferable. Contains oxides of noble metals such as copper, gold, silver, platinum and palladium, more preferably contains at least one oxide selected from gold, silver, copper and palladium, and even more preferably gold oxide and silver oxide. And at least one selected from copper oxide, more preferably at least one selected from silver oxide and copper oxide, still more preferably containing silver oxide, and even more preferably silver oxide. The type of metal can be confirmed by high frequency inductively coupled plasma emission spectrometry.
The total content of gold oxide, silver oxide and copper oxide in the metal oxide A is preferably 80% by mass or more, more preferably 90% by mass or more, and further, from the viewpoint of improving low-temperature sinterability and low-temperature bonding property. It is preferably 95% by mass or more, more preferably 98% by mass or more, and even more preferably substantially 100% by mass.
The total content of silver oxide and copper oxide in the metal oxide A is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95, from the viewpoint of improving low-temperature sinterability and low-temperature bonding property. It is by mass or more, more preferably 98% by mass or more, and even more preferably substantially 100% by mass.
The content of silver oxide in the metal oxide A is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, from the viewpoint of improving low-temperature sinterability and low-temperature bonding property. It is even more preferably 98% by mass or more, and even more preferably substantially 100% by mass.
Here, "substantially 100% by mass" means that components contained unintentionally may be contained. Examples of unintentionally contained components include unavoidable impurities.

<Polymer B>
The metal paste of the present invention suppresses the aggregation of metal nanoparticles, promotes the generation and sintering of metal nanoparticles having a uniform particle size, and improves low-temperature sinterability and low-temperature bondability. Contains. Polymer B contains at least one selected from a carboxy group and an imino group, and a polyoxyalkylene group.
The polymer B is preferably selected from at least a polymer BI containing a carboxy group and a polyoxyalkylene group and a polymer BII containing an imino group and a polyoxyalkylene group from the viewpoint of improving low temperature sinterability and low temperature bonding property. It is one kind. As the polymer B, the polymer BI is preferable from the viewpoint of improving the low temperature sinterability and the low temperature bonding property.

(Polymer BI)
The polymer BI contains a carboxy group and a polyoxyalkylene group.
Examples of the basic structure of the polymer BI include vinyl-based polymers such as acrylic resin, styrene-based resin, styrene-acrylic resin, and acrylic silicone-based resin; and condensation-based polymers such as polyester and polyurethane. A vinyl-based polymer is preferable from the viewpoint of improving low-temperature bondability.
From the viewpoint of improving low-temperature sinterability and low-temperature bondability, the polymer BI includes a structural unit derived from a monomer (b-1) having a carboxy group and a structural unit derived from a monomer (b-2) having a polyoxyalkylene group. A vinyl polymer containing is preferable. The polymer BI can be obtained by copolymerizing a raw material monomer containing a monomer (b-1) and a monomer (b-2). The polymer BI may be a block copolymer, a random copolymer, or an alternating copolymer.

[Monomer having a carboxy group (b-1)]
Examples of the monomer (b-1) include unsaturated monocarboxylic acids such as (meth) acrylic acid, crotonic acid, and 2-methacryloyloxymethylsuccinic acid; unsaturated dicarboxylic acids such as maleic acid, itaconic acid, fumaric acid, and citraconic acid. And so on. The unsaturated dicarboxylic acid may be anhydrous.
The monomer (b-1) may be used alone or in combination of two or more.
The monomer (b-1) is preferably at least one selected from (meth) acrylic acid and maleic acid from the viewpoint of improving low-temperature sinterability and low-temperature bondability.
As used herein, the term "(meth) acrylic acid" means at least one selected from acrylic acid and methacrylic acid. "(Meta) acrylic acid" in the following is also synonymous.

[Monomer having a polyoxyalkylene group (b-2)]
Examples of the monomer (b-2) include polyalkylene glycol (meth) acrylate, alkoxypolyalkylene glycol (meth) acrylate, and phenoxypolyalkylene glycol (meth) acrylate. The monomer (b-2) may be used alone or in combination of two or more.
As used herein, "(meth) acrylate" is at least one selected from acrylates and methacrylates. The "(meth) acrylate" in the following is also synonymous.

The monomer (b-2) is preferably at least one selected from polyalkylene glycol (meth) acrylate and alkoxypolyalkylene glycol (meth) acrylate from the viewpoint of improving low-temperature sinterability and low-temperature bondability. More preferably, it is an alkoxypolyalkylene glycol (meth) acrylate. From the same viewpoint as described above, the alkoxy group of the alkoxypolyalkylene glycol (meth) acrylate preferably has 1 or more and 8 or less carbon atoms, and more preferably 1 or more and 4 or less carbon atoms.
Examples of the alkoxypolyalkylene glycol (meth) acrylate include methoxypolyalkylene glycol (meth) acrylate, ethoxypolyalkylene glycol (meth) acrylate, propoxypolyalkylene glycol (meth) acrylate, butoxypolyalkylene glycol (meth) acrylate, and octoxy. Examples thereof include polyalkylene glycol (meth) acrylate.

The polyoxyalkylene group of the monomer (b-2) preferably contains a unit derived from an alkylene oxide having 2 or more and 4 or less carbon atoms from the viewpoint of improving low temperature sinterability and low temperature bonding property. Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, and the like, preferably one or more selected from ethylene oxide and propylene oxide, and more preferably ethylene oxide.
The number of units derived from the alkylene oxide in the polyoxyalkylene group is preferably 2 or more, more preferably 5 or more, still more preferably 7 or more, and from the viewpoint of improving low temperature sinterability and low temperature bonding property. It is preferably 100 or less, more preferably 70 or less, still more preferably 50 or less, still more preferably 40 or less, still more preferably 30 or less, still more preferably 20 or less, still more preferably 15 or less.
The polyoxyalkylene group may be a copolymer containing a unit derived from ethylene oxide and a unit derived from propylene oxide from the viewpoint of improving low temperature sinterability and low temperature bonding property. The molar ratio [EO / PO] of the unit (EO) derived from ethylene oxide and the unit (PO) derived from propylene oxide is preferably 60/40 or more, more preferably 65/35 or more, still more preferably 70/30 or more. Yes, and preferably 90/10 or less, more preferably 85/15 or less, still more preferably 80/20 or less.
The copolymer containing a unit derived from ethylene oxide and a unit derived from propylene oxide may be a block copolymer, a random copolymer, or an alternate copolymer.

Specific examples of the commercially available monomer (b-2) include NK Ester AM-90G, AM-130G, AMP-20GY, NK Ester M-20G, and 40G manufactured by Shin-Nakamura Chemical Industry Co., Ltd. , 90G, 230G, etc., Blemmer PE-90, 200, 350, etc. manufactured by NOF CORPORATION, Brenmer PME-100, 200, 400, 1000, 4000, etc., Brenmer PP-500, same. Examples thereof include 800, 1000 and the like, Blemmer AP-150, 400, 550 and the like, Blemmer 50PEP-300, 50PEEP-800B, 43PAPE-600B and the like.

[Hydrophobic monomer (b-3)]
The polymer BI may contain a structural unit derived from the hydrophobic monomer (b-3) from the viewpoint of improving low temperature sinterability and low temperature bonding property.
As used herein, the term "hydrophobic monomer" means that when the monomer is dissolved in 100 g of ion-exchanged water at 25 ° C. until it is saturated, the amount of the monomer dissolved is less than 10 g. The amount of the monomer (b-3) dissolved is preferably 5 g or less, more preferably 1 g or less, from the viewpoint of low-temperature sinterability and low-temperature bonding property.
The monomer (b-3) is preferably at least one selected from an aromatic group-containing monomer and a (meth) acrylate having a hydrocarbon group derived from an aliphatic alcohol.

The aromatic group-containing monomer preferably has an aromatic group having 6 or more and 22 or less carbon atoms, which may have a substituent containing a heteroatom, from the viewpoint of improving low-temperature sinterability and low-temperature bonding property. It is a vinyl monomer, and more preferably one or more selected from a styrene-based monomer and an aromatic group-containing (meth) acrylate. The molecular weight of the aromatic group-containing monomer is preferably less than 500.
Examples of the styrene-based monomer include styrene, α-methylstyrene, 2-methylstyrene, 4-vinyltoluene (4-methylstyrene), divinylbenzene, etc., from the viewpoint of improving low-temperature sinterability and low-temperature bonding property. , Styrene, α-methylstyrene is preferable.
As the aromatic group-containing (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate and the like are preferable, and benzyl (meth) acrylate is preferable from the viewpoint of improving low-temperature sinterability and low-temperature bonding property. ) Acrylate is more preferred.

The (meth) acrylate having a hydrocarbon group derived from an aliphatic alcohol preferably has a hydrocarbon group derived from an aliphatic alcohol having 1 or more and 22 or less carbon atoms from the viewpoint of improving low-temperature sinterability and low-temperature bonding property. Is. For example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, (Meta) acrylates having a linear alkyl group such as stearyl (meth) acrylate; isopropyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, isopentyl (meth) acrylate, isooctyl (meth) acrylate, (Meta) acrylate having a branched chain alkyl group such as isodecyl (meth) acrylate, isododecyl (meth) acrylate, isostearyl (meth) acrylate, 2-ethylhexyl (meth) acrylate; alicyclic alkyl such as cyclohexyl (meth) acrylate. Examples thereof include (meth) acrylate having a group. Among these, those having an alkyl group having 6 or more and 10 or less carbon atoms are more preferable.
The monomer (b-3) may be used alone or in combination of two or more.

The monomer (b-3) is preferably an aromatic group-containing monomer, more preferably a styrene-based monomer, and further preferably styrene or α-methylstyrene, from the viewpoint of improving low-temperature sinterability and low-temperature bonding property. , 2-Methylstyrene and 4-vinyltoluene (4-methylstyrene), and even more preferably at least one selected from styrene and α-methylstyrene.

(Content of each monomer in the raw material monomer of polymer BI or content of each structural unit in polymer BI)
When the polymer BI contains a structural unit derived from the monomer (b-1) and a structural unit derived from (b-2) and does not contain a structural unit derived from the monomer (b-3), the monomer (at the time of producing the polymer BI) The content of b-1) and (b-2) in the raw material monomer (content as an unneutralized amount; the same shall apply hereinafter) or the structural unit derived from the monomer (b-1) and (b-2) in the polymer BI. The content of the constituent units derived from) is as follows from the viewpoint of improving the low-temperature sintering property and the low-temperature bonding property.
The content of the monomer (b-1) is preferably 5 mol% or more, more preferably 10 mol% or more, still more preferably 15 mol% or more, still more preferably 20 mol% or more, still more preferably 25 mol%. And more preferably 50 mol% or less, more preferably 45 mol% or less, still more preferably 40 mol% or less, still more preferably 35 mol% or less.
The content of the monomer (b-2) is preferably 50 mol% or more, more preferably 55 mol% or more, still more preferably 60 mol% or more, still more preferably 65 mol% or more, and preferably 95 mol% or more. It is mol% or less, more preferably 90 mol% or less, still more preferably 85 mol% or less, still more preferably 80 mol% or less, still more preferably 75 mol% or less.
The molar ratio of the monomer (b-1) to the monomer (b-2) [monomer (b-1) / monomer (b-2)] is preferably 0.1 or more, more preferably 0.2 or more, and further. It is preferably 0.3 or more, and preferably 2 or less, more preferably 1.5 or less, still more preferably 1 or less, still more preferably 0.7 or less, still more preferably 0.5 or less.

When the polymer BI further contains a structural unit derived from the monomer (b-3), the content (as an unneutralized amount) of the monomers (b-1) to (b-3) in the raw material monomer at the time of producing the polymer BI. The content of the constituent units derived from the monomers (b-1) to (b-3) in the polymer BI is as follows from the viewpoint of improving the low-temperature sinterability and low-temperature bondability. Is.
The content of the monomer (b-1) is preferably 5 mol% or more, more preferably 10 mol% or more, still more preferably 15 mol% or more, and preferably 40 mol% or less, more preferably 30 mol. % Or less, more preferably 20 mol% or less.
The content of the monomer (b-2) is preferably 3 mol% or more, more preferably 5 mol% or more, still more preferably 7 mol% or more, and preferably 30 mol% or less, more preferably 20 mol. % Or less, more preferably 15 mol% or less.
The content of the monomer (b-3) is preferably 50 mol% or more, more preferably 60 mol% or more, still more preferably 70 mol% or more, and preferably 90 mol% or less, more preferably 85 mol. % Or less, more preferably 80 mol% or less.
The molar ratio of the monomer (b-1) to the monomer (b-2) [monomer (b-1) / monomer (b-2)] is preferably 0.5 or more, more preferably 1 or more, still more preferably. It is 1.5 or more, and preferably 3 or less, more preferably 2.5 or less, still more preferably 2 or less.

The polymer BI is a structural unit derived from a monomer (b-1) having at least a carboxy group and a structural unit derived from a monomer (b-2) having a polyoxyalkylene group from the viewpoint of improving low temperature sinterability and low temperature bonding property. A vinyl polymer containing and is preferable, a structural unit derived from at least one selected from (meth) acrylic acid and maleic acid as the monomer (b-1), and an alkoxypolyalkylene glycol (meth) as the monomer (b-2). It is more preferable to include a structural unit derived from acrylate.
When the polymer BI contains at least a structural unit derived from the monomer (b-1) and a structural unit derived from the monomer (b-2), the content molar ratio of the monomer (b-1) and the monomer (b-2) [monomer (b-2). b-1) / monomer (b-2)] is preferably 0.1 or more, more preferably 0.2 or more, still more preferably 0.3 or more, and preferably 0.3 or more, from the same viewpoint as described above. 3 or less, more preferably 2.5 or less, still more preferably 2 or less, still more preferably 1.5 or less, still more preferably 1 or less, still more preferably 0.7 or less, still more preferably 0.5 or less. Is.
When the polymer BI contains a structural unit derived from the monomer (b-1) and a structural unit derived from the monomer (b-2), the structural unit derived from the monomer (b-1) and the structural unit derived from the monomer (b-2). From the same viewpoint as described above, the total content of the above is preferably 20 mol% or more, more preferably 30 mol% or more, still more preferably 50 mol% or more, still more preferably 70 mol% or more, still more preferably 90. It is greater than or equal to mol%, and preferably less than or equal to 100 mol%.
As the polymer BI, one synthesized by a known method may be used, or a commercially available product may be used. Examples of commercially available polymer BI products include DISPERBYK-190 and 2015 manufactured by BYK.

The number average molecular weight Mn of the polymer BI is preferably 1,000 or more, more preferably 2,000 or more, still more preferably 3,000 or more, and more preferably 3,000 or more, from the viewpoint of improving low temperature sinterability and low temperature bonding property. It is preferably 100,000 or less, more preferably 50,000 or less, still more preferably 30,000 or less, still more preferably 10,000 or less, still more preferably 7,000 or less. The number average molecular weight Mn is measured by the method described in Examples.

The acid value of the polymer BI is preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g or more, still more preferably 15 mgKOH / g or more, and preferably 15 mgKOH / g or more, from the viewpoint of improving low-temperature sinterability and low-temperature bondability. It is 200 mgKOH / g or less, more preferably 100 mgKOH / g or less, still more preferably 70 mgKOH / g or less, still more preferably 50 mgKOH / g or less.
The acid value of the polymer B can be measured by the method described in Examples, but can also be calculated from the mass ratio of the constituent monomers.

When the polymer B contains a vinyl-based polymer containing a structural unit derived from a monomer (b-1) having a carboxy group and a structural unit derived from a monomer (b-2) having a polyoxyalkylene group, the polymer B has the carboxy group. The content of the vinyl-based polymer containing the structural unit derived from the monomer (b-1) and the structural unit derived from the monomer (b-2) having a polyoxyalkylene group in the polymer B is low temperature sinterability and low temperature bonding property. From the viewpoint of improving, it is preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, still more preferably 98% by mass or more, still more preferably substantially 100% by mass. .. Here, "substantially 100% by mass" means that components contained unintentionally may be contained. The unintentionally contained component means that, for example, a polymer B component other than the vinyl-based polymer contained in the vinyl-based polymer as a raw material can be contained.

(Polymer BII)
Polymer BII contains an imino group and a polyoxyalkylene group.
The polymer BII is preferably a polyalkyleneimine (hereinafter, also referred to as “PAI”) chain and a polyoxyalkylene (polyalkylene oxide) (hereinafter, also referred to as “PAO”) from the viewpoint of improving low-temperature sinterability and low-temperature bondability. ) A polyalkyleneimine / polyalkylene oxide copolymer having a chain (PAI / PAO copolymer), more preferably a PAI / PAO graft copolymer having a PAI chain as a trunk and a PAO chain as a branch, and a PAI / PAO graft copolymer. It is at least one selected from PAI / PAO block copolymers having a PAI chain and a PAO chain, and more preferably a PAI / PAO graft copolymer.

Examples of the alkyleneimine constituting the PAI / PAO copolymer include ethyleneimine, propyleneimine, 1,2-butyleneimine, 2,3-butyleneimine, and 1,1-dimethylethyleneimine having 2 or more and 8 or less carbon atoms. Examples thereof include alkyleneimine, but ethyleneimine is preferable from the viewpoint of improving low-temperature sintering property and low-temperature bonding property. The alkyleneimine may be used alone or in combination of two or more.
The polyalkylene oxide chain constituting the PAI / PAO copolymer is a unit derived from an alkylene oxide having 2 or more and 4 or less carbon atoms such as ethylene oxide, propylene oxide and butylene oxide from the viewpoint of improving low temperature sinterability and low temperature bonding property. Is preferable, and a polyethylene oxide chain containing a unit derived from ethylene oxide is more preferable.

Examples of the form of the PAI / PAO graft copolymer include a form in which the PAI chain as a stem is linear and a form in which the PAI chain as a stem is branched. Among them, a branched PAI / PAO graft copolymer having a branched PAI chain as a trunk is preferable from the viewpoint of improving low-temperature sinterability and low-temperature bondability.
When the PAI chain constituting the PAI / PAO graft copolymer has a branched structure, it has a secondary amino group (imino group), a tertiary amino group, and a primary amino group in the structure. May be.
Examples of the bonding form of the polymer block of the PAI / PAO block copolymer include diblock and triblock, and specific examples of the PAI / PAO block copolymer include PAI / PAO diblock copolymer and PAI /. Examples thereof include PAO / PAI triblock copolymers.

The weight average molecular weight Mw of the PAI chain constituting the PAI / PAO copolymer is preferably 3,000 or more, more preferably 5,000 or more, still more preferably 5,000 or more, from the viewpoint of improving low-temperature sinterability and low-temperature bondability. 7,000 or more, more preferably 10,000 or more, and preferably 100,000 or less, more preferably 70,000 or less, still more preferably 50,000 or less, still more preferably 30,000 or less. be.
The weight average molecular weight Mw of the PAO chain constituting the PAI / PAO copolymer is preferably 300 or more, more preferably 500 or more, still more preferably 1,000 or more, from the viewpoint of improving low-temperature sinterability and low-temperature bondability. It is preferably 50,000 or less, more preferably 30,000 or less, still more preferably 20,000 or less, still more preferably 10,000 or less, still more preferably 7,000 or less.
The above weight average molecular weight Mw is determined by measuring the weight average molecular weight Mw of the raw material PAI chain compound and PAO chain compound used in the production of the PAI / PAO copolymer using gel permeation chromatography (GPC). Can be done.

In the PAI / PAO graft copolymer, the average number of grafted PAO chains per PAI chain is preferably 5 or more, more preferably 10 or more, from the viewpoint of improving low temperature sinterability and low temperature bonding property. It is more preferably 13 or more, and preferably 50 or less, more preferably 40 or less, still more preferably 35 or less.

In the PAI / PAO graft copolymer, the ratio of the total number of alkyleneimine units having grafted PAO chains to the total number of alkyleneimine units (total number of alkyleneimine units having grafted PAO chains / total number of alkyleneimine units) is From the viewpoint of improving low-temperature sinterability and low-temperature bondability, it is preferably 0.01 or more, more preferably 0.015 or more, still more preferably 0.02 or more, and preferably 0.1 or less. It is preferably 0.07 or less, more preferably 0.05 or less. The above ratio (total number of alkyleneimine units having grafted PAO chains / total number of alkyleneimine units) can be measured by ¹ H-NMR.

As the PAI / PAO copolymer, one synthesized by a known method may be used, or a commercially available product may be used. Examples of the method for synthesizing the PAI / PAO copolymer include a method of reacting polyalkyleneimine with a polyoxyalkylene having a functional group capable of reacting with the nitrogen atom of the polyalkyleneimine, and a method of reacting the nitrogen atom of the polyalkyleneimine with an alkylene. It can be obtained by a method of adding an oxide or the like. Examples of the polyoxyalkylene having a functional group capable of reacting with the nitrogen atom of the polyalkyleneimine include methoxypolyethylene glycol acetic acid and the like.
Examples of commercially available products of the polymer BII include the PPE series manufactured by Creative PEG Works.

When the polymer B contains a PAI / PAO copolymer, the content of the PAI / PAO copolymer in the polymer B is preferably 80% by mass or more from the viewpoint of improving low-temperature sinterability and low-temperature bondability. , More preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably 98% by mass or more, still more preferably substantially 100% by mass. Here, "substantially 100% by mass" means that components contained unintentionally may be contained. The unintentionally contained component means that, for example, a polymer B component other than the PAI / PAO copolymer contained in the PAI / PAO copolymer as a raw material can be contained.

A vinyl-based polymer containing a structural unit derived from a monomer (b-1) having a carboxy group and a structural unit derived from a monomer (b-2) having a polyoxyalkylene group in the polymer B, a polyalkyleneimine chain, and a polyoxyalkylene. The total content of the polyalkyleneimine / polyalkylene oxide copolymer having a chain is preferably 80% by mass or more, more preferably 90% by mass or more, and further, from the viewpoint of improving low-temperature sinterability and low-temperature bonding property. It is preferably 95% by mass or more, more preferably 98% by mass or more, and even more preferably substantially 100% by mass. Here, "substantially 100% by mass" means that components contained unintentionally may be contained. The unintentionally contained component means that, for example, the vinyl-based polymer as a raw material, the vinyl-based polymer contained in the copolymer, and the polymer B component other than the copolymer can be included.

<Glycol C>
The metal paste of the present invention contains diol C from the viewpoint of improving low temperature sinterability and low temperature bonding property.
The diol C is not particularly limited as long as it is a compound having two alcoholic hydroxyl groups in one molecule. Examples of the diol C include ethylene glycol (boiling point 197 ° C.), propylene glycol (1,2-propanediol) (boiling point 188 ° C.), 1,2-butanediol (boiling point 193 ° C.), and 1,2-pentanediol (boiling point 206 ° C.). 1,2-Alcandiol such as 1,2-hexanediol (boiling point 223 ° C); diethylene glycol (boiling point 245 ° C), triethylene glycol (boiling point 287 ° C), tetraethylene glycol (boiling point 314 ° C), polyethylene glycol , Dipropylene glycol (boiling point 232 ° C), polyalkylene glycol such as tripropylene glycol (boiling point 271 ° C); 1,3-propanediol (boiling point 210 ° C), 1,4-butanediol (boiling point 230 ° C), 1, Α, ω-Alcandiol such as 5-pentanediol (boiling point 242 ° C.); 1,3-butanediol (boiling point 208 ° C.), 3-methyl-1,3-butanediol (boiling point 203 ° C.), 2-methyl- Examples thereof include 2,4-pentanediol (boiling point 196 ° C.). The diol C can be used alone or in combination of two or more.
The boiling point of diol C is preferably 70 ° C. or higher, more preferably 90 ° C. or higher, still more preferably 110 ° C. or higher, still more preferably 130 ° C. or higher, still higher, from the viewpoint of improving low-temperature sinterability and low-temperature bondability. It is preferably 150 ° C. or higher, and preferably 300 ° C. or lower, more preferably 250 ° C. or lower, still more preferably 230 ° C. or lower, still more preferably 200 ° C. or lower.
When two or more kinds of polyols C are used in combination, the boiling point of the polyol C is a weighted average value weighted by the content (mass%) of each polyol.
Diol C is preferably at least selected from 1,2-alkanediol and polyalkylene glycol from the viewpoint of promoting the reduction reaction from the metal oxide to the metal nanoparticles and improving the low temperature sinterability and low temperature bonding property. It contains one, more preferably 1,2-alkanediol, still more preferably at least one selected from propylene glycol and ethylene glycol, and even more preferably propylene glycol.

The metal paste of the present invention may contain various additives as components other than the above-mentioned components as long as the effects of the present invention are not impaired. Examples of the additive include a surfactant, an antifoaming agent, a filler and the like.

The metal paste of the present invention can be produced by mixing metal oxide A, polymer B, and diol C by a known method. There is no particular limitation on the mixing order.
The content of each component of the metal paste of the present invention is as follows from the viewpoint of improving low-temperature sinterability and low-temperature bonding property, and from the viewpoint of productivity and handleability of the metal paste.
The content of the metal oxide A in the metal paste of the present invention is 50% by mass or more, preferably 55% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, still more preferably. It is 75% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less, and further preferably 85% by mass or less.
The content of the polymer B in the metal paste of the present invention is preferably 2% by mass or more, more preferably 2.5% by mass or more, and preferably from the viewpoint of improving low temperature sinterability and low temperature bonding property. Is 6% by mass or less, more preferably 5% by mass or less, still more preferably 4% by mass or less.
The mass ratio of polymer B to metal oxide A in the metal paste of the present invention (polymer B / metal oxide A) is preferably 1/100 or more from the viewpoint of improving low-temperature sinterability and low-temperature bondability. It is more preferably 2/100 or more, still more preferably 3/100 or more, and preferably 10/100 or less, more preferably 7/100 or less, still more preferably 5/100 or less.
The content of diol C in the metal paste of the present invention is preferably 3% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, from the viewpoint of improving low-temperature sinterability and low-temperature bonding property. And, preferably 30% by mass or less, more preferably 25% by mass or less, still more preferably 20% by mass or less.
The mass ratio of diol C to metal oxide A in the metal paste of the present invention (diol C / metal oxide A) is preferably 3/100 or more from the viewpoint of improving low-temperature sinterability and low-temperature bondability. It is more preferably 5/100 or more, still more preferably 10/100 or more, still more preferably 15/100 or more, and preferably 50/100 or less, more preferably 40/100 or less, still more preferably 30/100. Below, it is even more preferably 25/100 or less.

When the diol C contains 1,2-alkanediol, the content of the 1,2-alkanediol in the diol C promotes the reduction reaction from the metal oxide to the metal nanoparticles, resulting in low temperature sinterability and low temperature. From the viewpoint of improving the bondability, it is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, still more. It is preferably 98% by mass or more, and even more preferably substantially 100% by mass. Here, "substantially 100% by mass" means that components contained unintentionally may be contained. Examples of the component unintentionally contained include a diol C component other than the 1,2-alkanediol contained in the 1,2-alkanediol as a raw material.
When the diol C contains propylene glycol, the content of the propylene glycol in the diol C is preferable from the viewpoint of promoting the reduction reaction from the metal oxide to the metal nanoparticles and improving the low temperature sinterability and the low temperature bonding property. Is 10% by mass or more, more preferably 20% by mass or more, further preferably 30% by mass or more, still more preferably 50% by mass or more, still more preferably 70% by mass or more, still more preferably 80% by mass or more, and more. It is more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably 98% by mass or more, and even more preferably substantially 100% by mass. Here, "substantially 100% by mass" means that components contained unintentionally may be contained. Examples of the component unintentionally contained include a diol C component other than the propylene glycol contained in the propylene glycol as a raw material.

Since the metal paste of the present invention has excellent low-temperature sinterability, it can be used for forming conductive members of various electronic and electrical devices. The conductive member is a bonding agent such as solder; an antenna such as an RFID (radio frequency identifier) tag; a capacitor such as MLCC (laminated ceramic capacitor); electronic paper; an image display device such as a liquid crystal display or an organic EL display; organic. It is preferable to use it for an EL element; an organic transistor; a wiring board such as a printed wiring board and a flexible wiring board; an organic solar cell; a sensor such as a flexible sensor. Among these, the metal paste of the present invention is preferably used for joining a plurality of metal members from the viewpoint of low temperature bonding.

[Manufacturing method of bonded body]
The method for producing a bonded body of the present invention is a method for producing a bonded body including a step of interposing a metal paste between a plurality of metal members and heating the bonded body, wherein the metal paste is the above-mentioned metal paste of the present invention. be.
When the metal paste of the present invention is used for joining a plurality of metal members, it is preferably used in a method for producing a bonded body, which comprises a step of interposing the metal paste between the plurality of metal members and heating the metal paste.
The temperature of the heat treatment in the above step is, from the viewpoint of bonding strength and volume resistance, under normal pressure, preferably 30 ° C. or higher, more preferably 35 ° C. or higher, still more preferably 37 ° C. or higher, and fine metal nanoparticles. From the viewpoint of forming particles, reducing voids in the metal sintered body, and improving low-temperature sinterability and low-temperature bonding property, the temperature is preferably 130 ° C. or lower, more preferably 110 ° C. or lower, still more preferably 100 ° C. or lower. It is even more preferably 90 ° C. or lower, still more preferably 70 ° C. or lower, still more preferably 60 ° C. or lower, still more preferably 50 ° C. or lower, and even more preferably 45 ° C. or lower.
The pressure of the heat treatment in the above step can be under reduced pressure, normal pressure or pressurized, but from the viewpoint of productivity, normal pressure is preferable.
The time of the heat treatment in the above step can be appropriately adjusted depending on the temperature of the heat treatment, but is preferably 1 minute or longer, more preferably 5 minutes or longer, still more preferably 10 minutes or longer, still more preferably 30 minutes or longer. Yes, and preferably 6 hours or less, more preferably 3 hours or less, still more preferably 2 hours or less.
The heat treatment in the above step may be performed under an air atmosphere or an inert gas atmosphere such as nitrogen gas, but when the metal member to be joined is a metal that is easily oxidized, the nitrogen gas atmosphere may be used. It is preferably below.

Examples of the metal member to be joined in the present invention include a gold substrate, a gold-plated substrate, a silver substrate, a silver-plated metal substrate, a copper substrate, a palladium substrate, a palladium-plated metal substrate, a platinum substrate, a platinum-plated metal substrate, an aluminum substrate, and a nickel substrate. Examples thereof include metal-based substrates such as nickel-plated metal substrates, tin substrates, tin-plated metal substrates, or metal substrates; metal parts such as electrodes of electrically insulating substrates. The plurality of metal members used in the present invention may be the same type of metal member or different types of metal member.
Among these, the metal member is preferably a gold substrate, a gold-plated substrate, a silver substrate, a silver-plated metal substrate, a copper substrate, a palladium substrate, a palladium-plated metal substrate, a platinum substrate, a platinum-plated metal substrate, an aluminum substrate, a nickel substrate, and nickel. Includes at least one selected from metal parts of plated metal substrates, tin substrates, tin plated metal substrates, and electrically insulating substrates.
The bonding of metal members in the present invention is a bonding between a chip component such as a capacitor or a resistor and a circuit board; a bonding between a semiconductor chip such as a memory, a diode, a transistor, an IC, or a CPU and a lead frame or a circuit board; a semiconductor having high heat generation. It can be used for joining a chip and a cooling plate.

Various coating methods such as slot die coating, dip coating, spray coating, spin coating, doctor braiding, knife edge coating, and bar coating; screen printing, flexographic printing, and gravure printing are used as methods for applying the metal paste to metal members. , Offset printing, dispenser printing, inkjet printing and various other patterning printing methods.
The amount of the metal paste applied to the metal member can be appropriately adjusted according to the size and type of the metal member to be joined.

The volumetric resistance ρv of the metal sintered body formed in the bonded body is preferably 55 μΩ · cm or less, more preferably 40 μΩ · cm or less, still more preferably 30 μΩ · cm or less, still more preferably 20 μΩ · cm or less. , More preferably 10 μΩ · cm or less, even more preferably 7 μΩ · cm or less, and from the viewpoint of the productivity of the bonded body, preferably 1 μΩ · cm or more, more preferably 2 μΩ · cm or more, still more preferably. It is 3 μΩ · cm or more.
The volume resistivity ρv can be measured by the method described in Examples.
The bonding strength of the bonded body is preferably 30 MPa or more, more preferably 40 MPa or more, still more preferably 50 MPa or more.
The joint strength can be measured by the method described in Examples.

With respect to the above embodiments, the present invention further discloses the following embodiments.
<1>
A method for manufacturing a bonded body, which comprises a step of interposing a metal paste between a plurality of metal members and heating the bonded body.
The metal paste contains metal oxide A, polymer B, and diol C,
The polymer B contains at least one selected from a carboxy group and an imino group and a polyoxyalkylene group.
A method for producing a bonded body, wherein the content of the metal oxide A in the metal paste is 50% by mass or more.
<2>
A method for manufacturing a bonded body, which comprises a step of interposing a metal paste between a plurality of metal members and heating the bonded body.
The metal paste contains metal oxide A, polymer B, and diol C,
The polymer B contains at least one selected from a carboxy group and an imino group and a polyoxyalkylene group.
The content of the metal oxide A in the metal paste is 50% by mass or more, and the content is 50% by mass or more.
Metal oxide A contains at least one selected from gold oxide, silver oxide and copper oxide.
A vinyl-based polymer containing a structural unit derived from a monomer (b-1) in which polymer B has a carboxy group and a structural unit derived from a monomer (b-2) having a polyoxyalkylene group, and a polyalkyleneimine chain and a polyoxyalkylene chain. Contains one or more selected from polyalkyleneimine / polyalkylene oxide copolymers having
The method for producing a conjugate according to <1>, wherein the diol C contains 1,2-alkanediol.
<3>
A method for manufacturing a bonded body, which comprises a step of interposing a metal paste between a plurality of metal members and heating the bonded body.
The metal paste contains metal oxide A, polymer B, and diol C,
The polymer B contains at least one selected from a carboxy group and an imino group and a polyoxyalkylene group.
The content of the metal oxide A in the metal paste is 50% by mass or more, and the content is 50% by mass or more.
Metal oxide A contains silver oxide
The polymer B contains a vinyl-based polymer containing a structural unit derived from a monomer (b-1) having a carboxy group and a structural unit derived from a monomer (b-2) having a polyoxyalkylene group.
The method for producing a conjugate according to <1> or <2>, wherein the diol C contains propylene glycol.
<4>
The content of the metal oxide A in the metal paste is 50% by mass or more and 95% by mass or less.
The mass ratio of polymer B to metal oxide A in the metal paste (polymer B / metal oxide A) is 1/100 or more and 10/100 or less.
The bonding according to any one of <1> to <3>, wherein the content mass ratio (diol C / metal oxide A) of the diol C in the metal paste to the metal oxide A is 3/100 or more and 50/100 or less. How to make a body.
<5>
The content of the metal oxide A in the metal paste is 70% by mass or more and 90% by mass or less.
The mass ratio of polymer B to metal oxide A in the metal paste (polymer B / metal oxide A) is 2/100 or more and 7/100 or less.
The junction according to any one of <1> to <4>, wherein the content mass ratio (diol C / metal oxide A) of the diol C in the metal paste to the metal oxide A is 10/100 or more and 30/100 or less. How to make a body.
<6>
A vinyl-based polymer containing a structural unit derived from a monomer (b-1) having a carboxy group and a structural unit derived from a monomer (b-2) having a polyoxyalkylene group in the polymer B, a polyalkyleneimine chain, and a polyoxyalkylene. The method for producing a conjugate according to any one of <2> to <5>, wherein the total content of the polyalkyleneimine / polyalkylene oxide copolymer having a chain is 80% by mass or more.
<7>
The method for producing a conjugate according to any one of <2> to <6>, wherein the content of 1,2-alkanediol in the diol C is 70% by mass or more.
<8>
The method for producing a bonded body according to any one of <3> to <7>, wherein the content of propylene glycol in the diol C is 70% by mass or more.
<9>
The method for producing a bonded body according to any one of <1> to <8>, wherein the temperature of the heat treatment in the heating step is 30 ° C. or higher and 130 ° C. or lower.
<10>
The method for producing a bonded body according to <9>, wherein the temperature of the heat treatment in the step is 50 ° C. or lower.
<11>
The method for producing a bonded body according to any one of <1> to <10>, wherein the heat treatment time in the heating step is 1 minute or more and 6 hours or less.
<12>
The method for producing a bonded body according to any one of <1> to <11>, wherein the heat treatment in the heating step is under any atmosphere selected from an air atmosphere and an inert gas atmosphere.
<13>
Metal parts are gold substrate, gold-plated substrate, silver substrate, silver-plated metal substrate, copper substrate, palladium substrate, palladium-plated metal substrate, platinum substrate, platinum-plated metal substrate, aluminum substrate, nickel substrate, nickel-plated metal substrate, tin substrate, The method for producing a bonded body according to any one of <1> to <12>, which comprises at least one selected from a tin-plated metal substrate and a metal portion of an electrically insulating substrate.
<14>
The joining of the metal member is selected from the joining of the chip component and the circuit board, the joining of the semiconductor chip and the lead frame or the circuit board, and the joining of the high heat generation semiconductor chip and the cooling plate, <1> to The method for manufacturing a bonded body according to any one of <13>.
<15>
The use of metal paste for joining multiple metal parts,
The metal paste contains metal oxide A, polymer B, and diol C,
The polymer B contains at least one selected from a carboxy group and an imino group and a polyoxyalkylene group.
Used in which the content of metal oxide A in the metal paste is 50% by mass or more.
<16>
The use of metal paste for joining multiple metal parts,
The metal paste contains metal oxide A, polymer B, and diol C,
The polymer B contains at least one selected from a carboxy group and an imino group and a polyoxyalkylene group.
The content of the metal oxide A in the metal paste is 50% by mass or more, and the content is 50% by mass or more.
Metal oxide A contains at least one selected from gold oxide, silver oxide and copper oxide.
A vinyl-based polymer containing a structural unit derived from a monomer (b-1) in which polymer B has a carboxy group and a structural unit derived from a monomer (b-2) having a polyoxyalkylene group, and a polyalkyleneimine chain and a polyoxyalkylene chain. Contains one or more selected from polyalkyleneimine / polyalkylene oxide copolymers having
The use according to <15>, wherein the diol C contains 1,2-alkanediol.
<17>
The use of metal paste for joining multiple metal parts,
The metal paste contains metal oxide A, polymer B, and diol C,
The polymer B contains at least one selected from a carboxy group and an imino group and a polyoxyalkylene group.
The content of the metal oxide A in the metal paste is 50% by mass or more, and the content is 50% by mass or more.
Metal oxide A contains silver oxide
The polymer B contains a vinyl-based polymer containing a structural unit derived from a monomer (b-1) having a carboxy group and a structural unit derived from a monomer (b-2) having a polyoxyalkylene group.
The use according to <15> or <16>, wherein the diol C contains propylene glycol.
<18>
The content of the metal oxide A in the metal paste is 50% by mass or more and 95% by mass or less.
The mass ratio of polymer B to metal oxide A in the metal paste (polymer B / metal oxide A) is 1/100 or more and 10/100 or less.
The use according to any one of <15> to <17>, wherein the content mass ratio (diol C / metal oxide A) of the diol C in the metal paste to the metal oxide A is 3/100 or more and 50/100 or less. ..
<19>
The content of the metal oxide A in the metal paste is 70% by mass or more and 90% by mass or less.
The mass ratio of polymer B to metal oxide A in the metal paste (polymer B / metal oxide A) is 2/100 or more and 7/100 or less.
The use according to any one of <15> to <18>, wherein the content mass ratio (diol C / metal oxide A) of the diol C in the metal paste to the metal oxide A is 10/100 or more and 30/100 or less. ..
<20>
A vinyl-based polymer containing a structural unit derived from a monomer (b-1) having a carboxy group and a structural unit derived from a monomer (b-2) having a polyoxyalkylene group in the polymer B, a polyalkyleneimine chain, and a polyoxyalkylene. The use according to any one of <16> to <19>, wherein the total content of the polyalkyleneimine / polyalkylene oxide copolymer having a chain is 80% by mass or more.
<21>
The use according to any one of <16> to <20>, wherein the content of 1,2-alkanediol in the diol C is 70% by mass or more.
<22>
The use according to any one of <17> to <21>, wherein the content of propylene glycol in the diol C is 70% by mass or more.
<23>
Containing metal oxide A, polymer B, and diol C,
The polymer B contains at least one selected from a carboxy group and an imino group and a polyoxyalkylene group.
A metal paste having a metal oxide A content of 50% by mass or more.
<24>
The metal paste contains metal oxide A, polymer B, and diol C,
The polymer B contains at least one selected from a carboxy group and an imino group and a polyoxyalkylene group.
The content of the metal oxide A in the metal paste is 50% by mass or more, and the content is 50% by mass or more.
Metal oxide A contains at least one selected from gold oxide, silver oxide and copper oxide.
A vinyl-based polymer containing a structural unit derived from a monomer (b-1) in which polymer B has a carboxy group and a structural unit derived from a monomer (b-2) having a polyoxyalkylene group, and a polyalkyleneimine chain and a polyoxyalkylene chain. Contains one or more selected from polyalkyleneimine / polyalkylene oxide copolymers having
The metal paste according to <23>, wherein the diol C contains 1,2-alkanediol.
<25>
Containing metal oxide A, polymer B, and diol C,
The polymer B contains at least one selected from a carboxy group and an imino group and a polyoxyalkylene group.
The content of the metal oxide A in the metal paste is 50% by mass or more, and the content is 50% by mass or more.
Metal oxide A contains silver oxide
The polymer B contains a vinyl-based polymer containing a structural unit derived from a monomer (b-1) having a carboxy group and a structural unit derived from a monomer (b-2) having a polyoxyalkylene group.
The metal paste according to <23> or <24>, wherein the diol C contains propylene glycol.
<26>
The content of the metal oxide A in the metal paste is 50% by mass or more and 95% by mass or less.
The mass ratio of polymer B to metal oxide A in the metal paste (polymer B / metal oxide A) is 1/100 or more and 10/100 or less.
The metal according to any one of <23> to <25>, wherein the content mass ratio (diol C / metal oxide A) of the diol C in the metal paste to the metal oxide A is 3/100 or more and 50/100 or less. paste.
<27>
The content of the metal oxide A in the metal paste is 70% by mass or more and 90% by mass or less.
The mass ratio of polymer B to metal oxide A in the metal paste (polymer B / metal oxide A) is 2/100 or more and 7/100 or less.
The metal according to any one of <23> to <26>, wherein the content mass ratio (diol C / metal oxide A) of the diol C in the metal paste to the metal oxide A is 10/100 or more and 30/100 or less. paste.
<28>
A vinyl-based polymer containing a structural unit derived from a monomer (b-1) having a carboxy group and a structural unit derived from a monomer (b-2) having a polyoxyalkylene group in the polymer B, a polyalkyleneimine chain, and a polyoxyalkylene. The metal paste according to any one of <24> to <27>, wherein the total content of the polyalkyleneimine / polyalkylene oxide copolymer having a chain is 80% by mass or more.
<29>
The metal paste according to any one of <24> to <28>, wherein the content of 1,2-alkanediol in the diol C is 70% by mass or more.
<30>
The metal paste according to any one of <25> to <29>, wherein the content of propylene glycol in the diol C is 70% by mass or more.

In the following synthesis examples, examples and comparative examples, "parts" and "%" are "parts by mass" and "% by mass" unless otherwise specified.

[Measurement of number average molecular weight Mn of polymer B]
Gel permeation chromatography method using a solution prepared by dissolving phosphoric acid and lithium bromide in N, N-dimethylformamide at concentrations of 60 mmol / L and 50 mmol / L, respectively, as an eluent [GPC device (HLC) manufactured by Tosoh Corporation). -8320GPC), Tosoh Corporation column (TSKgel SuperAWM-H, TSKgel SuperAW3000, TSKgel guardcolumn Super AW-H), flow velocity: 0.5 mL / min], monodisperse polystyrene kit [PStQuickB] with a known molecular weight as a standard material. F-550, F-80, F-10, F-1, A-1000), PStQuick C (F-288, F-40, F-4, A-5000, A-500), manufactured by Tosoh Corporation] Was measured using.
For the measurement sample, 0.1 g of the polymer was mixed with 10 mL of the eluent in a glass vial, stirred at 25 ° C. for 10 hours with a magnetic stirrer, and a syringe filter (DISMIC-13HP PTFE 0.2 μm, manufactured by Advantech Toyo Co., Ltd.). ) Was filtered.

[Measurement of acid value of polymer B]
The acid value of Polymer B was measured according to the method of JIS K 0070. However, only the measurement solvent was changed from the mixed solvent of ethanol and ether specified in JIS K 0070 to the mixed solvent of acetone and toluene (acetone: toluene = 4: 6 (volume ratio)).

Synthesis Example 1 (Synthesis of Polymer BI-1)
Put 100 g of ion-exchanged water in a 1000 mL four-necked round-bottom flask equipped with a thermometer, one 200 mL dropping funnel with nitrogen bypass (1), one 50 mL dropping funnel with nitrogen bypass (2), and a reflux device, and magnetic. The flask was stirred with a stirrer, and the internal temperature of the flask was heated to 80 ° C. in an oil bath. Separately, after performing nitrogen bubbling for 10 minutes, 98% acrylic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent) 6 g, methoxypolyethylene glycol (EO 9 mol) acrylate (manufactured by Shin-Nakamura Chemical Industries, Ltd. "NK Ester AM" -90G ") 94g, 3-mercaptopropionic acid (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was dissolved in a polybeaker and placed in a dropping funnel (1). Further, 20 g of ion-exchanged water and 2 g of ammonium peroxodisulfate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., a special grade reagent) were dissolved in a polybeaker and placed in a dropping funnel (2). Then, the mixture in the dropping funnel (1) and the dropping funnel (2) was simultaneously added dropwise to the flask over 90 minutes. Then, after raising the internal temperature of the flask to 90 degreeC, stirring was continued for another 1 hour. Then, the mixture was cooled to room temperature, and the obtained polymer solution was freeze-dried to obtain polymer BI-1 (Mn: 4,200, acid value: 47 mgKOH / g).

Comparative Synthesis Example 1 (Synthesis of Polymer BC1)
In Synthesis Example 1, the same synthesis was carried out except that methoxypolyethylene glycol (EO9 mol) acrylate was changed to 100 g without using 98% acrylic acid to obtain polymer BC1 (Mn: 4,400).

Comparative Synthesis Example 2 (Synthesis of Polymer BC2)
In Synthesis Example 1, the same synthesis was carried out except that 98% acrylic acid was changed to 100 g without using methoxypolyethylene glycol (EO9 mol) acrylate, and the polymer BC2 (Mn: 1,100, acid value: 780 mgKOH / g) was synthesized. ) Was obtained.

Example 1
As the metal oxide A, 100 g of silver oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent), 4 g of polymer BI-14, and 20 g of propylene glycol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent) were mixed. By treating the obtained mixture with a kneading defoaming machine (“Awatori Rentaro ARE-310” manufactured by Shinky Co., Ltd.) under the treatment conditions (stirring mode 2,000 rpm, treatment time 60 seconds). Metal paste 1 was obtained.
The obtained metal paste 1 is used as one of two experimental silver plates (manufactured by KENIS, thickness 2 mm, purity 99.96%) using a metal mask (manufactured by Hirai Precision Industry Co., Ltd., mask thickness 100 μm). After coating on the silver plate, the other silver plate was further superposed on the coated surface to obtain a laminated body in which a metal paste was interposed between the two silver plates. Next, the obtained laminate was placed in an oven and heat-treated at 40 ° C. for 1 hour to obtain a bonded body I on which a metal sintered body layer was formed.

Examples 2 to 10 and Comparative Examples 1 to 5
In Example 1, metal pastes 2 to 10 and C1 to C5 were obtained in the same manner except that the composition was changed to the composition shown in Table 1. Next, in Example 1, metal pastes 2 to 10 and C1 to C5 were used instead of the metal paste 1, and the same was applied except that the heat treatment temperatures of Examples 5 and 9 were changed to 100 ° C. and 120 ° C., respectively. The pastes II to X and CI to CV were obtained.
The details of each component in Table 1 are as follows.
Gold Oxide: Made by Fujifilm Wako Junyaku Co., Ltd., Special Grade Copper Oxide (II): Made by Fujifilm Wako Junyaku Co., Ltd., Chemical Silver Nitrate: Made by Fujifilm Wako Junyaku Co., Ltd., Special Grade Polymer BI-2: Acrylic Acid / Maleic acid / alkoxy (polyethylene glycol / polypropylene glycol) acrylate (number of units derived from alkylene oxide: 32 mol, molar ratio [EO / PO] = 75/25) / styrene / α-methylstyrene copolymer [solid content 40%] (Mn: 4,500, acid value: 24 mgKOH / g) of the above-mentioned polymer aqueous solution (“DISPERBYK-2015” manufactured by BYK, acid value: 10 mgKOH / g) in an absolutely dry state].
PG: Propylene Glycol EG: Ethylene Glycol Polymer BII-1: Linear Polyethylene Imine / Polyethylene Oxide Graft Copolymer (“PPE-401” manufactured by Creative PEGWorks, MW of polyethylene oxide chain: 2,000, MW of polyethylene imine chain : 22,000, average number of grafted polyethylene oxide chains to one polyethyleneimine chain = 15, ratio (total number of ethyleneimine units having grafted polyethyleneimine chains / total number of ethyleneimine units): 0.027 )
Polymer BII-2: Branched polyethyleneimine / polyethylene oxide graft copolymer (“Branched PEI-g-PEG” manufactured by Merck Co., Ltd., Mn of polyethylene oxide chain: 5,000, Mw of polyethyleneimine chain: 25,000, 1 Average number of grafted polyethylene oxide chains to book polyethyleneimine chains = 15, ratio (total number of ethyleneimine units with grafted polyethyleneimine chains / total number of ethyleneimine units): 0.023)

<Evaluation>
[Volume resistivity ρv]
The bonded bodies obtained in Examples and Comparative Examples were processed using a cross-section sample preparation device "IB-19520CCP" (manufactured by JEOL Ltd.) to obtain a sample sample in which a smooth cut surface was prepared on the bonded body. ..
Next, the sample sample was attached to an SEM sample table (Nissin EM Co., Ltd., Type-T) with an aluminum base carbon double-sided tape for SEM (Nisshin EM Co., Ltd., catalog number 732), and a field emission scanning electron microscope was used. Using "FE-SEM" (manufactured by Hitachi, Ltd., model: S-4800), the cut surface was observed under the conditions of SEM mode and an acceleration voltage of 10 kV to obtain a secondary electron image. The thickness of the metal sintered body layer was measured at 10 points of the metal sintered body layer in the secondary electron image, and the thickness t of the metal sintered body layer was obtained by arithmetic mean.
Next, the sample obtained above was measured using a resistivity meter (main body: Loresta-GP, four probe probe: PSP probe, both manufactured by Nittoseiko Analytech Co., Ltd.), and the metal measured above was measured. The volume resistivity was displayed by inputting the thickness t of the sintered body layer into the resistivity meter. The same measurement was performed at other places of the above sample, and the volume resistivity ρv was obtained by the arithmetic mean of a total of 10 places. The results are shown in Table 1. The lower the volume resistivity ρv, the better the sinterability.

[Joint strength]
The bonded bodies obtained in Examples and Comparative Examples were measured for the bonded strength under the conditions of a shear height of 50 μm, a test speed of 5 mm / min, and 25 ° C. according to JIS Z 3198-5: 2003. rice field. The results are shown in Table 1.

From Table 1, it can be seen that Examples 1 to 10 are excellent in low temperature sinterability because the volume resistivity ρv is low and excellent in low temperature bonding property because the bonding strength is high as compared with Comparative Examples 1 to 5. ..

According to the present invention, since it is possible to provide a metal paste having excellent low-temperature sinterability and low-temperature bonding property, it can be used for forming circuits and electrodes in various electronic components or joining members.

Claims (13)

A method for manufacturing a bonded body, which comprises a step of interposing a metal paste between a plurality of metal members and heating the bonded body.
The metal paste contains metal oxide A, polymer B, and diol C,
The polymer B contains at least one selected from a carboxy group and an imino group and a polyoxyalkylene group.
A method for producing a bonded body, wherein the content of the metal oxide A in the metal paste is 50% by mass or more. The method for producing a bonded body according to claim 1, wherein the metal oxide A contains at least one selected from gold oxide, silver oxide and copper oxide. The method for producing a conjugate according to claim 1 or 2, wherein the diol C contains 1,2-alkanediol. The method for producing a bonded body according to any one of claims 1 to 3, wherein the temperature of the heat treatment in the heating step is 30 ° C. or higher and 130 ° C. or lower. The method for producing a bonded body according to claim 4, wherein the temperature of the heat treatment in the step is 50 ° C. or lower. The method for producing a bonded body according to any one of claims 1 to 5, wherein the heat treatment time in the heating step is 1 minute or more and 6 hours or less. The method for producing a bonded body according to any one of claims 1 to 6, wherein the heat treatment in the heating step is under any atmosphere selected from an air atmosphere and an inert gas atmosphere. Metal parts are gold substrate, gold-plated substrate, silver substrate, silver-plated metal substrate, copper substrate, palladium substrate, palladium-plated metal substrate, platinum substrate, platinum-plated metal substrate, aluminum substrate, nickel substrate, nickel-plated metal substrate, tin substrate, The method for producing a bonded body according to any one of claims 1 to 7, which comprises at least one selected from a tin-plated metal substrate and a metal portion of an electrically insulating substrate. Claims 1 to 1, wherein the joining of the metal member is selected from the joining of a chip component and a circuit board, the joining of a semiconductor chip and a lead frame or a circuit board, and the joining of a high heat generation semiconductor chip and a cooling plate. 8. The method for producing a bonded body according to any one of 8. Containing metal oxide A, polymer B, and diol C,
The polymer B contains at least one selected from a carboxy group and an imino group and a polyoxyalkylene group.
A metal paste having a metal oxide A content of 50% by mass or more. The metal paste according to claim 10, wherein the metal oxide A contains at least one selected from gold oxide, silver oxide and copper oxide. The metal paste according to claim 10 or 11, wherein the diol C comprises 1,2-alkanediol. The metal paste according to any one of claims 10 to 12, which is used for joining a plurality of metal members.