TWI726071B - Conductive adhesive - Google Patents

Abstract

The present invention provides a conductive adhesive, which can produce a sintered body that is not prone to cracks and cracks caused by sintering and has excellent mechanical strength. A conductive adhesive containing: first silver particles A, which has a first protective layer and an average particle size of 10nm~30nm; and second silver particles B, which has a second protective layer and an average particle size of 50nm~100nm Wherein, the second protective layer contains hydroxy fatty acid; and the mass ratio (A:B) of the first silver particles A and the second silver particles B is in the range of 5:95-40:60.

Description

Conductive adhesive

The present invention relates to a conductive adhesive, a manufacturing method thereof, a sintered body of the conductive adhesive, and a circuit or electrode having the sintered body between components.

BACKGROUND OF THE INVENTION Conductive adhesives, led by die bond and die attach agent, are used as bonding materials for semiconductors, LEDs, and power semiconductors. As a method of this, in general, bonding using pressure and heating, or bonding with a base material by sintering using heating or the like under no pressure is known. In recent years, based on the simplicity and efficiency of the manufacturing process, the development of bonding materials without pressure has been progressing day by day.

An example of a non-pressurized bonding material can be a conductive adhesive containing epoxy resin. The bonding material is cured by a low-temperature process to harden the epoxy resin for users, and can suppress void generation and improve the bonding strength with the base material (Patent Document 1). However, since the epoxy resin itself becomes a resistance, the resulting conductivity becomes lower.

On the other hand, a bonding material that does not contain epoxy resin may be a conductive adhesive composed of only silver. The bonding material uses micron silver or submicron silver (particle size 300~900nm) (Patent Document 2), but from the point of view that voids are prone to occur, it needs to be processed at 200~250°C in terms of general sintering reaction1 We seek to develop a bonding material that can obtain high shear strength (materials with high bonding properties) and suppress the occurrence of voids by processing at a lower temperature and a short time.

In recent years, the development of silver nano-particles keeps pace with the times, and silver nano-particles have the feature that they can be easily sintered by low-temperature and short-time heat treatment. In particular, when silver nano-particles with a particle size of about 20nm are used, it can be easily sintered at a relatively low temperature (below 200°C) and a dense film can be formed. However, when many particles of about 20 nm are blended in the bonding material, stress will occur in the coating film as the film thickness becomes thicker, resulting in cracks and cracks. Therefore, it is sought to develop a material that can suppress the occurrence of voids and has less stress in the coating film.

As a material that satisfies this requirement, a conductive adhesive containing nano-sized metal nano-particles has been proposed (for example, refer to Patent Document 3). Prior Art Documents Patent Documents

Patent Document 1: International Publication 2010/18712 Patent Document 2: International Publication 2014/104046 Patent Document 3: Japanese Patent Application Publication No. 2006-83377

SUMMARY OF THE INVENTION The problem to be solved by the invention is that a conductive adhesive containing nano-sized metal nano-particles is placed between components and heated and sintered into a sintered body at a high temperature (for example, 200°C or higher). At the same time, it has high conductivity.

However, the inventors of the present case have conducted a review and found that the conventional conductive adhesive containing nano-sized silver particles may crack and break in the obtained sintered body, which reduces the mechanical strength. In particular, if the heating time during sintering is increased or the heating temperature is increased from the viewpoint of further improving the conductivity, the sintered body cracks and cracks will occur remarkably.

Under such circumstances, the main purpose of the present invention is to provide a conductive adhesive, which can produce a sintered body that is less prone to cracks and cracks caused by sintering and has excellent mechanical strength. In addition, the object of the present invention is also to provide a method for producing a conductive adhesive, a sintered body of the conductive adhesive, and a circuit or electrode having the sintered body between components. Means to solve the problem

In order to solve the aforementioned problems, the inventor of this case has conducted research and review. As a result, it was found that the conductive adhesive used the first silver particles A with the first protective layer and the average particle size of 10nm~30nm and the second protective layer with the hydroxy fatty acid-containing second protective layer and the average particle size of 50nm~100nm. Silver particles B, and the mass ratio of the first silver particles A to the second silver particles B (A:B) is set in a specific range of 5:95~40:60, which can effectively suppress the sintered body of the conductive adhesive Cracks and breaks, and a sintered body with excellent mechanical strength is obtained. In addition, it has also been found that such a sintered body has high conductivity and is excellent in adhesiveness. The present invention is completed based on the above-mentioned insights and through repeated reviews.

That is, the present invention provides inventions in the following forms. (1) A conductive adhesive, comprising: first silver particles A having a first protective layer and an average particle diameter of 10 nm to 30 nm; and second silver particles B having a second protective layer and an average particle diameter of 50nm~100nm; wherein the second protective layer contains hydroxy fatty acid; and the mass ratio (A:B) of the first silver particles A to the second silver particles B is in the range of 5:95-40:60. (2) The conductive adhesive according to (1), wherein the first protective layer contains at least one of fatty acid and alkylamine. (3) The conductive adhesive according to (1) or (2), wherein the total ratio of the first silver particles A and the second silver particles B is 80% by mass or more. (4) The conductive adhesive according to any one of (1) to (3), which further contains a solvent. (5) A method of manufacturing a conductive adhesive, which has the following steps: the first silver particles A and the second silver particles B are adjusted so that the mass ratio of the first silver particles A to the second silver particles B (A:B) The mixing is carried out in the range of 5:95~40:60, wherein the first silver particles A has a first protective layer and the average particle size is 10nm-30nm, and the second silver particles B has a second hydroxy fatty acid The protective layer has an average particle size of 50nm-100nm. (6) A sintered body of a conductive adhesive, the conductive adhesive being the conductive adhesive of any one of (1) to (4). (7) A circuit or electrode having parts where components have been bonded by the sintered body as in (6). Invention effect

According to the present invention, a conductive adhesive can be provided, which can produce a sintered body with excellent mechanical strength (shear strength) that is less likely to occur due to sintering cracks and cracks. Furthermore, according to the present invention, a method for manufacturing the conductive adhesive, a sintered body of the conductive adhesive, and a circuit or electrode with the sintered body between components can be provided.

Modes for Carrying Out the Invention The conductive adhesive of the present invention is characterized by containing: first silver particles A having a first protective layer and an average particle diameter of 10nm-30nm; and second silver particles B having a second The protective layer has an average particle size of 50nm~100nm; the second protective layer contains hydroxy fatty acid; and the mass ratio (A:B) of the first silver microparticle A to the second silver microparticle B (A:B) is 5:95~40:60 Within the range. Hereinafter, the conductive adhesive of the present invention, the manufacturing method of the conductive adhesive, the sintered body of the conductive adhesive, and the circuit or electrode with the sintered body between the members will be described in detail.

1. Conductive adhesive The conductive adhesive of the present invention contains the aforementioned first silver microparticle A and second silver microparticle B in a predetermined ratio (hereinafter "the first silver microparticle A and the second silver microparticle B" are collectively referred to as In the case of "silver particles").

The first silver fine particles A have a first protective layer on the surface layer of particles (silver particles) made of silver. The material for forming the first protective layer is not particularly limited as long as it can form a surface layer of silver particles and can function as a protective layer (for example, a layer that inhibits aggregation of the first silver particles A and the second silver particles B). From the viewpoint of effectively improving the mechanical strength of the sintered body of the conductive adhesive, for example, suitable fatty acids, alkyl amines, and hydroxy fatty acids are mentioned. The protective layer may be composed of one material or two or more materials.

Although the fatty acid is not particularly limited, it can be exemplified as follows: Preferably, the alkyl group has a carbon number of 3 or more and 18 or less, and preferably has an alkyl group that has a carbon number of 4 or more and 18 or less. Preferred specific examples of fatty acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, 2-ethylhexanoic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and oleic acid. , Linoleic acid and α-linolenic acid, etc. In addition, specific examples of fatty acids include cycloalkyl carboxylic acid such as cyclohexane carboxylic acid. Among them, from the viewpoint of effectively improving the mechanical strength of the sintered body of the conductive adhesive, hexanoic acid, 2-ethylhexanoic acid, oleic acid, linoleic acid, and α-linolenic acid are preferred. Fatty acids may be used individually by 1 type, and may be used in combination of 2 or more types.

Although the alkyl amine is not particularly limited, it can be exemplified as follows: Preferably, the alkyl amine has a carbon number of 3 or more and 18 or less, and preferably has an alkyl group of 4 or more and 12 or less carbon atoms. . In addition, with regard to the conductive adhesive of the present invention, when the first protective layer of silver particles A contains alkylamine, the alkylamine in the first protective layer will be separated from the silver when the conductive adhesive is sintered. The surface of the fine particles A is detached, so it will not have a substantial influence on the conductivity of the obtained sintered body.

Specific examples of ideal alkylamines include, for example, ethylamine, n-propylamine, isopropylamine, 1,2-dimethylpropylamine, n-butylamine, isobutylamine, secondary butylamine, tertiary butylamine, isoamylamine Amine, tertiary pentylamine, 3-pentylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, 2-octylamine, 2-ethylhexylamine, n-nonylamine, n-aminodecane, n- Aminoundecane, n-dodecylamine, n-tridecylamine, 2-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptaamine, n-octadecylamine, n-oleylamine (n-oleylamine), N-ethyl-1,3-diamine propane, N,N-diisopropylethylamine, N,N-dimethylamine propane, N,N-dibutylamine propane, N ,N-dimethyl-1,3-diaminepropane, N,N-diethyl-1,3-diaminepropane, N,N-diisobutyl-1,3-diaminepropane and N- Lauryl diamine propane and so on. For example, dibutylamine which is a secondary amine and cyclopropylamine which is a cycloalkylamine, cyclobutylamine, cyclopropylamine, cyclohexylamine, cycloheptylamine and cyclooctylamine etc. can also be mentioned. Among them, from the viewpoint of effectively improving the mechanical strength of the sintered body of the conductive adhesive, n-propylamine, isopropylamine, cyclopropylamine, n-butylamine, isobutylamine, secondary butylamine, and tertiary Butylamine, cyclobutylamine, n-pentylamine, n-hexylamine, cyclohexylamine, n-octylamine, 2-ethylhexylamine, n-dodecylamine, n-oleylamine, N,N-dimethyl-1,3- Diamine propane and N,N-diethyl-1,3-diamine propane are preferred, preferably n-butylamine, n-hexylamine, cyclohexylamine, n-octylamine, n-dodecylamine, N,N-diamine Methyl-1,3-diaminepropane and N,N-diethyl-1,3-diaminepropane. Alkylamine may be used individually by 1 type, and may be used in combination of 2 or more types.

When alkylamine and fatty acid are used together in the first protective layer, the molar ratio of alkylamine to fatty acid (alkylamine: fatty acid) is, for example, preferably in the range of about 90:10 to about 99.9:0.1, preferably It is in the range of about 95:5 to about 99.5:0.5.

The hydroxy fatty acid that may be contained in the first protective layer may be the same as the hydroxy fatty acid contained in the second protective layer described later.

Although the ratio (mass %) of the first protective layer in the first silver particles A is not particularly limited, it protects the surface of the first silver particles A and also effectively improves the mechanical strength of the sintered body of the conductive adhesive From a viewpoint, for example, it is preferably about 0.1% by mass to about 10% by mass, and preferably about 1% by mass to about 8% by mass.

The average particle size of the first silver fine particles A is in the range of 10 nm to 30 nm. In the present invention, the first silver microparticles A having the specific particle size and the second silver microparticles A described later are used together at a specific mixing ratio, thereby effectively improving the mechanical strength of the sintered body of the conductive adhesive . Based on the same point of view, the average particle size of the first silver particles A should be in the range of 15-25 nm.

In the present invention, the average particle size of the first silver particles A is the average of the long side lengths of more than 30 particles contained in an image observed under a scanning electron microscope. In addition, when only the first silver microparticle A of the present invention is observed with a scanning electron microscope, it can be the average of the long side lengths of any 30 or more particles contained in the image. In addition, when calculating the average particle size of the first silver microparticles A for the conductive adhesive in which the first silver microparticles A and the second silver microparticles B described later are mixed, 30 or more were selected in sequence and measured under a scanning electron microscope. Observe the particles with the short long sides of the particles contained in the observed image, and use this as the average of the long sides of the 30 or more particles.

The second silver fine particles B have a second protective layer on the surface layer of particles (silver particles) made of silver. In the present invention, the second protective layer contains hydroxy fatty acid.

As the hydroxy fatty acid, a compound having 3 to 24 carbon atoms and one or more hydroxyl groups (for example, one) can be used. The hydroxy fatty acid may include, for example, 2-hydroxydecanoic acid, 2-hydroxydodecanoic acid, 2-hydroxytetradecanoic acid, 2-hydroxyhexadecanoic acid, 2-hydroxyoctadecanoic acid, 2-hydroxyeicosanic acid, 2-hydroxy two Dodecanoic acid, 2-hydroxytrichanoic acid, 2-hydroxy tetracosic acid, 3-hydroxyhexanoic acid, 3-hydroxyoctanoic acid, 3-hydroxynonanoic acid, 3-hydroxydecanoic acid, 3-hydroxyundecanoic acid, 3-hydroxydodecanoic acid, 3-hydroxytridecanoic acid, 3-hydroxytetradecanoic acid, 3-hydroxyhexadecanoic acid, 3-hydroxy seventeen acid, 3-hydroxyoctadecanoic acid, ω-hydroxy-2-decene Acid, ω-hydroxy pentadecanoic acid, ω-hydroxy seventeen acid, ω-hydroxy arachidic acid, ω-hydroxy behenic acid, 6-hydroxy octadecanoic acid, ricinoleic acid, 12-hydroxy stearic acid and [ R-(E)]-12-hydroxy-9-octadecenoic acid and the like. Among them, hydroxy fatty acids with 4 to 18 carbons and one hydroxyl group outside the ω position (especially at the 12 position) are preferred, and ricinoleic acid and 12-hydroxystearic acid are preferred. The hydroxy fatty acid contained in the second protective layer may be one type or two or more types.

The second protective layer includes hydroxy fatty acids, and may further include alkyl amines and fatty acids. The alkylamine and fatty acid may be the same as those exemplified in the first protective layer.

When alkylamine and fatty acid are used together in the second protective layer, the molar ratio of alkylamine to fatty acid (alkylamine: fatty acid) can be, for example, preferably in the range of about 90:10 to about 99.9:0.1 , Preferably in the range of about 95:5 to about 99.8:0.2.

Although the ratio (mass%) of the second protective layer in the second silver particles B is not particularly limited, it is based on protecting the surface of the second silver particles B and also effectively improving the mechanical strength of the sintered body of the conductive adhesive. The viewpoint, for example, is preferably about 0.1% by mass to about 10% by mass, and preferably about 0.1% by mass to about 5% by mass.

The average particle diameter of the second silver particles B is in the range of 50 nm to 100 nm. From the viewpoint of effectively improving the mechanical strength of the sintered body of the conductive adhesive, the average particle size of the second silver particles B is preferably in the range of 65 nm to 90 nm.

In the present invention, the average particle size of the second silver microparticles B is the average of the long side lengths of more than 30 particles contained in the image observed under a scanning electron microscope. In addition, when only the second silver microparticle B of the present invention is observed with a scanning electron microscope, it can be the average of the long side lengths of any 30 or more particles contained in the image. In addition, when calculating the average particle size of the second silver microparticles B for the conductive adhesive in which the second silver microparticles B and the aforementioned first silver microparticles A were mixed, 30 or more particles were selected in order and examined under a scanning electron microscope. Observe the particles with the long side length of the particles contained in the observed image, and use this as the average value for the long side lengths of the 30 or more particles.

For the conductive adhesive of the present invention, the mass ratio (A:B) of the first silver particles A to the second silver particles B is in the range of 5:95-40:60. In the present invention, by using the first silver microparticles A having a particle diameter within the predetermined range and the second silver microparticles A having a particle size larger than the first silver microparticle A and having a specific protective layer in the mass ratio, it is possible to Effectively improve the mechanical strength of the sintered body of the conductive adhesive. Although the details of this mechanism are not clear, for example, it can be presumed as follows. That is, we believe that when the conductive adhesive of the present invention is sintered, the first silver particles A with a small average particle size will be sintered first to fill the gaps between the second silver particles B, and thereafter, because they are protected by hydroxy fatty acids and The sintering of the second silver fine particles B with a large particle size progresses stably, so cracks and cracks during sintering are suppressed, and as a result, a sintered body with excellent mechanical strength can be obtained.

From the viewpoint of effectively improving the mechanical strength of the sintered body of the conductive adhesive, in the conductive adhesive of the present invention, the mass ratio (A:B) of the first silver particles A to the second silver particles B can be, for example, It should be about 10:90-40:60, 20:80-40:60, 5:95-30:70, 10:90-30:70, and 20:80-30:70.

In the conductive adhesive of the present invention, the total ratio of the first silver particles A and the aforementioned second silver particles B is not particularly limited, but for example, it is preferably 80% by mass or more, preferably 85% by mass~ About 95% by mass.

The conductive adhesive of the present invention includes the first silver particles A and the second silver particles B, and preferably further contains a solvent. Containing a solvent increases the fluidity and makes it easier to arrange the conductive adhesive of the present invention in a desired place.

烷等之醚類；1,2-丙二醇、1,2-丁二醇、1,3-丁二醇、1,4-丁二醇、2,3-丁二醇、1,2-己二醇、1,6-己二醇、1,2-戊二醇、1,5-戊二醇、2-甲基-2,4-戊二醇、3-甲基-1,5-戊二醇、1,2-辛二醇、1,8-辛二醇及2-乙基-1,3-己二醇等之二元醇類；甘油；碳數1~5之直鏈或分枝鏈的醇、環己醇、3-甲氧基-3-甲基-1-丁醇及3-甲氧基-1-丁醇等之醇類；乙酸乙酯、乙酸丁酯、丁酸乙酯及甲酸乙酯等之脂肪酸酯類；聚乙二醇、三甘醇單甲基醚、四甘醇單甲基醚、乙二醇單乙基醚、二乙二醇單乙基醚、二乙二醇二甲基醚、三甘醇二甲基醚、四甘醇二甲基醚、3-甲氧基乙酸丁酯、乙二醇單丁基醚、乙二醇單丁基醚乙酸酯、乙二醇單己基醚、乙二醇單辛基醚、乙二醇單-2-乙基己基醚、乙二醇單芐基醚、二乙二醇單甲基醚、二乙二醇單甲基醚乙酸酯、二乙二醇單乙基醚、二乙二醇單乙基醚乙酸酯、二乙二醇單丁基醚、二乙二醇單丁基醚乙酸酯、聚丙二醇、丙二醇單丙基醚、丙二醇單丁基醚、二丙二醇單甲基醚、二丙二醇單乙基醚、二丙二醇單丙基醚、二丙二醇單丁基醚、三丙二醇單甲基醚、三丙二醇單乙基醚、三丙二醇單丙基醚、三丙二醇單丁基醚等之二醇或二醇醚類；N,N-二甲基甲醯胺；二甲基亞碸；萜品醇等之萜[烯]類；乙腈；γ-丁內酯；四氫吡咯酮-[2]；N-甲基吡咯啶酮；及N-(2-胺乙基)哌

等。而於該等之中，從更加有效提高導電性黏著劑之燒結體的機械強度之觀點來看，宜為碳數3~5之直鏈或分枝鏈的醇、3-甲氧基-3-甲基-1-丁醇、3-甲氧基-1-丁醇、二乙二醇單丁基醚、二乙二醇單丁基醚乙酸酯及萜品醇。The solvent is not particularly limited as long as it can disperse the first silver fine particles A and the second silver fine particles B, but it is preferable to contain a polar organic solvent. Examples of polar organic solvents include ketones such as acetone, acetone and methyl ethyl ketone; diethyl ether, dipropyl ether, dibutyl ether, tetrahydrofuran and 1,4-di

Ethers such as alkanes; 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,2-hexanedi Alcohol, 1,6-hexanediol, 1,2-pentanediol, 1,5-pentanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol Alcohol, 1,2-octanediol, 1,8-octanediol, 2-ethyl-1,3-hexanediol and other dihydric alcohols; glycerin; straight chain or branched carbon number 1~5 Chain alcohols, cyclohexanol, 3-methoxy-3-methyl-1-butanol and 3-methoxy-1-butanol and other alcohols; ethyl acetate, butyl acetate, ethyl butyrate Fatty acid esters such as esters and ethyl formate; polyethylene glycol, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, two Ethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 3-methoxy butyl acetate, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetic acid Ester, ethylene glycol monohexyl ether, ethylene glycol monooctyl ether, ethylene glycol mono-2-ethylhexyl ether, ethylene glycol monobenzyl ether, diethylene glycol monomethyl ether, diethylene glycol Monomethyl ether acetate, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, Polypropylene glycol, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, Glycol or glycol ethers such as tripropylene glycol monoethyl ether, tripropylene glycol monopropyl ether, and tripropylene glycol monobutyl ether; N,N-dimethylformamide; dimethyl sulfoxide; terpineol And other terpenes [enes]; acetonitrile; γ-butyrolactone; tetrahydropyrrolidone-[2]; N-methylpyrrolidone; and N-(2-aminoethyl)piperidine

Wait. Among these, from the viewpoint of more effectively improving the mechanical strength of the sintered body of the conductive adhesive, it is preferably a straight or branched chain alcohol with a carbon number of 3 to 5, and 3-methoxy-3 -Methyl-1-butanol, 3-methoxy-1-butanol, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate and terpineol.

Solvents including polar organic solvents may also contain non-polar or hydrophobic solvents. Examples of non-polar organic solvents include linear, branched or cyclic saturated hydrocarbons such as hexane, heptane, octane, nonane, decane, 2-ethylhexane, and cyclohexane; carbon number 6 or more Alcohols such as linear or branched chain alcohols; aromatic compounds such as benzene, toluene, and benzonitrile; halogenated hydrocarbons such as dichloromethane, chloroform and dichloroethane; methyl n-amyl ketone; Methyl ethyl ketoxime; and glycerol triacetate, etc. Among them, saturated hydrocarbons and straight or branched chain alcohols with 6 or more carbons are preferred, preferably hexane, octane, decane, octanol, decanol and dodecanol . One type of solvent can be used alone, or two or more types can be mixed for use.

When both a polar organic solvent and a non-polar organic solvent are contained, the ratio of the polar organic solvent with respect to the total amount of the solvent is preferably 5% by volume or more, preferably 10% by volume or more, and more preferably 15% by volume or more. In addition, it may be 60% by volume or less, 55% by volume or less, or 50% by volume or less. The solvent can also be made up of only polar organic solvents. When the conductive adhesive of the present invention contains many polar organic solvents in this way, the dispersibility of the first silver particles A and the second silver particles B is also good.

Regarding the conductive adhesive of the present invention, although the ratio of the solvent is not particularly limited, it may be, for example, preferably 20% by mass or less, and preferably about 5 to 15% by mass.

In the conductive adhesive of the present invention, additives usually contained in the conductive adhesive can also be added.

2. Manufacturing method of conductive adhesive The conductive adhesive of the present invention can be easily manufactured by a method having the following steps. This step is to combine the first silver particles A and the second silver particles B to make the first silver particles The mass ratio of A and the second silver particles B (A:B) is mixed in the range of 5:95~40:60, wherein the first silver particles A has a first protective layer and the average particle size is 10nm~ 30nm, the second silver particles B have a second protective layer containing hydroxy fatty acid and have an average particle size of 50nm-100nm. Here, the detailed description of the first silver microparticle A and the second silver microparticle B is as described in the aforementioned "1. Conductive Adhesive".

In the manufacturing method of the conductive adhesive of the present invention, the mixing of the first silver microparticles A and the second silver microparticles B is preferably performed by mixing the dispersion liquid of the first silver microparticles A and the dispersion liquid of the second silver microparticles B. The average particle size of the first silver particles A is 10nm~30nm, and the average particle size of the second silver particles B is 50nm~100nm. Since both particles have nano-sized particle sizes, it can be said that if they are not equal If it is mixed in a state of being dispersed in a solvent, it is difficult to obtain a conductive adhesive in which the particles are uniformly dispersed. In addition, the solvent is preferably one that has been exemplified in the aforementioned "1. Conductive Adhesive".

The manufacturing method of the first silver microparticle A and the second silver microparticle B is not particularly limited, and each can be manufactured by a well-known method. As these manufacturing methods, the method described in JP 2015-40319 A, etc. can be mentioned, for example. An example of the manufacturing method of the first silver microparticles A and the second silver microparticles B is disclosed below.

First, a composition for manufacturing the first silver microparticle A or the second silver microparticle B (a composition for preparing silver microparticles) is prepared. Specifically, it prepares silver compounds (preferably silver oxalate, etc.) that will become the raw material of silver particles, components that constitute the first protective layer or the second protective layer (the aforementioned fatty acids, alkyl amines, and hydroxy fatty acids, etc.), and organic Solvent. Next, these components are mixed to prepare a composition for preparing silver fine particles. The ratio of each component in this composition should just be suitably adjusted so that it may become the structure of the said 1st silver microparticle A and the 2nd silver microparticle B. For example, the content of silver oxalate in the composition is preferably about 20 to 70% by mass relative to the total amount of the composition. In addition, when fatty acids are used in the first protective layer, the content of fatty acids is preferably about 0.1% by mass to 20% by mass relative to the total composition. When an alkylamine is used in the first protective layer, the content of the alkylamine relative to the total composition is preferably about 5% to 55% by mass. When the hydroxy fatty acid is used in the second protective layer, the content of the hydroxy fatty acid relative to the total composition is preferably about 0.1% by mass to 15% by mass.

In addition, the mixing method of each component is not particularly limited. For example, a mechanical stirrer, a magnetic stirrer, a vortex mixer, a planetary mill, a ball mill, a three-roll mill, and a pipeline mixer (LINE MIXER) can be used. , Planetary mixer, dissolver and other general-purpose devices for mixing. The temperature of the composition will rise due to the influence of heat of dissolution and frictional heat during mixing. In order to prevent the thermal decomposition reaction of the silver particles, it is advisable to keep the temperature of the composition below 60°C, especially below 40°C. mixing.

Next, the composition for preparing silver microparticles is reacted in a reaction vessel, usually by supplying it to a reaction by heating to initiate a thermal decomposition reaction of the silver compound to generate silver microparticles. During the reaction, the composition can be introduced into the reaction vessel that has been heated in advance, or the composition can be heated after the composition has been introduced into the reaction vessel.

The reaction temperature may be a temperature at which the thermal decomposition reaction proceeds to produce silver fine particles, and it may be, for example, about 50 to 250°C. Moreover, the reaction time only needs to be appropriately selected according to the desired average particle size and the composition of the corresponding composition. The reaction time can be, for example, 1 minute to 100 hours.

The silver particles produced by the thermal decomposition reaction are obtained as a mixture containing unreacted raw materials, so it is preferable to refine the silver particles. Examples of the purification method include a solid-liquid separation method and a precipitation method that utilizes the difference in the specific gravity of unreacted raw materials such as silver particles and organic solvents. The solid-liquid separation method can include filter filtration, centrifugal separation, cyclone or decanter and other methods. In order to facilitate the handling during refining, the viscosity of the mixture containing silver particles can be adjusted by diluting the mixture with low boiling point solvents such as acetone and methanol.

The average particle diameter of the obtained silver particles can be adjusted by adjusting the composition of the composition for producing silver particles and the reaction adjustment.

3. Sintered body of conductive adhesive The sintered body of the conductive adhesive of the present invention can be prepared by sintering the conductive adhesive of the present invention described in the aforementioned "1. Conductive Adhesive". Regarding the sintered body of the conductive adhesive of the present invention, most of the components constituting the first protective layer and the second protective layer of the conductive adhesive are detached due to the high heat during sintering, so the sintered body is essentially made of silver Constituted.

Although the sintering temperature is not particularly limited, from the viewpoint that the obtained sintered body exhibits high electrical conductivity and high adhesive force while also effectively improving the mechanical strength, for example, it is preferably about 150°C to 200°C, preferably Around 150℃~185℃. Based on the same viewpoint, the sintering time can be, for example, preferably about 0.4 hours to about 2.0 hours, and preferably about 0.5 hours to about 1.2 hours. Sintering can be carried out in the atmosphere and inert gas (nitrogen and argon) and other gas environments. The sintering method is not particularly limited, and examples include ovens, hot-air drying ovens, infrared drying ovens, laser irradiation, flash lamp irradiation, and microwaves.

4. Circuit or electrode The circuit or electrode of the present invention respectively has a part where the components have been bonded by the sintered body of the present invention. That is, in the circuit or electrode of the present invention, the conductive adhesive of the present invention described in the aforementioned "1. Conductive Adhesive" is arranged between the components of the circuit or the electrode, and the conductive adhesive is sintered to sinter the components. The glue between.

As mentioned above, the sintered body of the present invention exerts high conductivity and high adhesive force while effectively improving its mechanical strength. Therefore, even for circuits or electrodes with this sintered body, there will be excellent inter-components. Electrical conductivity and adhesion, and excellent mechanical strength. Example

The present invention is explained in more detail in the following examples, but the present invention is not limited to these examples.

The details of the components used in the examples are as follows. ･Silver oxalate ((COOAg) ₂ ) was synthesized by the method described in Patent Document 1 (Japanese Patent No. 5574761). ･Ricinoleic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) ･oleic acid (manufactured by Wako Pure Chemical Industries Co., Ltd.) ･N,N-dimethyl-1,3-diaminopropane (Wako Pure Chemical Industries, Ltd.) ･Cyclohexylamine (manufactured by Wako Pure Chemical Industries Co., Ltd.) ･Dodecylamine (manufactured by Wako Pure Chemical Industries Co., Ltd.) ･butylamine (manufactured by Wako Pure Chemical Industries Co., Ltd.) ･butanol (and Ko Pure Chemical Industry Co., Ltd.) ･Octylamine (Wako Pure Chemical Industry Co., Ltd.)

<Synthesis example 1> Put ricinoleic acid (0.03g), N,N-dimethyl-1,3-diaminepropane (2.6g) and butanol into a 50mL glass centrifuge tube containing a magnetic stirring element (4.8g), and after stirring for about 1 minute, silver oxalate (3.2g) was added and stirred for about 10 minutes to prepare a composition for preparing silver fine particles. After that, the glass centrifuge tubes were set upright on a hot stirrer (HHE-19G-U manufactured by Koike Precision Machinery Co., Ltd.) with aluminum bricks, and stirred in a water bath at 40°C for 30 minutes, and further heated at 90°C. Stir in the oil bath for 30 minutes. After radiation cooling, the magnetic stirrer was taken out, and 1.5 g of methanol was added to each composition and stirred with a vortex mixer, and then centrifuged (CF7D2 manufactured by Hitachi Koki Co., Ltd.) at 3000 rpm (approximately 1600×G) Perform a centrifugal precipitation operation for 1 minute, and remove the supernatant by tilting the centrifuge tube. Repeat the steps of adding 15g of methanol, stirring, centrifuging and removing the supernatant twice, and recover the produced silver particles.

<Synthesis example 2> Put oleic acid (0.06g), n-octylamine (1.40g), and N,N-dimethyl-1,3-diaminepropane into a 50mL glass centrifuge tube containing a magnetic stirrer (0.43g), n-dodecylamine (0.16g), cyclohexylamine (0.12g) and n-butylamine (0.64g), and after stirring for about 1 minute, put in silver oxalate (3.2g) and stir for about 10 Minutes, thereby preparing a composition for preparing silver fine particles. After that, the glass centrifuge tubes were set upright on a hot stirrer (HHE-19G-U manufactured by Koike Precision Machinery Co., Ltd.) with aluminum bricks, and stirred in a water bath at 40°C for 30 minutes, and further heated at 90°C. Stir in the oil bath for 30 minutes. After radiation cooling, the magnetic stirrer was taken out, and 15 g of methanol was added to each composition and stirred with a vortex mixer, and then centrifuged (CF7D2 manufactured by Hitachi Koki Co., Ltd.) at 3000 rpm (approximately 1600×G) Perform a centrifugal precipitation operation for 1 minute, and remove the supernatant by tilting the centrifuge tube. Repeat the steps of adding 15g of methanol, stirring, centrifuging and removing the supernatant twice, and recover the produced silver particles.

<Synthesis example 3> Put oleic acid (0.1g), N,N-dimethyl-1,3-diaminepropane (3.25g) and butanol ( 6.0 g), and after stirring for about 1 minute, silver oxalate (4.0 g) was put in and stirred for about 10 minutes to prepare a composition for preparing silver fine particles. After that, the glass centrifuge tubes were set upright on a hot stirrer (HHE-19G-U manufactured by Koike Precision Machinery Co., Ltd.) with aluminum bricks, and stirred in a water bath at 40°C for 30 minutes, and further heated at 90°C. Stir in the oil bath for 30 minutes. After radiation cooling, the magnetic stirrer was taken out, and 15 g of methanol was added to each composition and stirred with a vortex mixer, and then centrifuged (CF7D2 manufactured by Hitachi Koki Co., Ltd.) at 3000 rpm (approximately 1600×G) Perform a centrifugal precipitation operation for 1 minute, and remove the supernatant by tilting the centrifuge tube. Repeat the steps of adding 15g of methanol, stirring, centrifuging and removing the supernatant twice, and recover the produced silver particles.

(Measurement of average particle size) The silver particles obtained in Synthesis Examples 1 to 3 were observed with a scanning electron microscope (S-4500 manufactured by Hitachi High-Technologies Corporation), and the edges of any 30 particles contained in the image were measured Long length and find the average value. And the results are shown in Table 1.

[Table 1]

(Examples 1 to 5 and Comparative Examples 1 to 5) The silver microparticles obtained in Synthesis Example 1 and the silver microparticles obtained in Synthesis Example 2 were mixed in the predetermined ratio shown in Table 2, and added 10% of the total weight Of terpineol to obtain a dispersion. Using MAZERUSTAR manufactured by KURABO INDUSTRIES LTD., the liquid was mixed in the secondary stirring priority mode to prepare each conductive adhesive.

Next, prepare a base material with 0.5μm electroless silver plating applied on the copper plate, and coat each conductive adhesive evenly on it so that the thickness of the coating film becomes 50μm, and the back side (with the conductive adhesive The contact surface) a silicon wafer (size 2mm×2mm) with gold plating or gold sputtering treatment is placed on it. The sintered conductive adhesive film was prepared by heating the material at a predetermined temperature (150°C, 175°C) in a dryer (circulation type) for 60 minutes.

(Evaluation of Mechanical Strength) The shear strength of each coating film obtained in each example was measured by die shear test using a bonding strength tester (SS30-WD manufactured by Nishijin Shoji Co., Ltd.). And the results are shown in Table 2.

(Evaluation of cracking and cracking of coating film) The surface of each coating film obtained in each example was visually observed, and the presence or absence of cracking and cracking of the coating film was evaluated. The results are shown in Table 2.

[Table 2]

(Comparative Example 6) The silver particles obtained in Synthesis Example 1 and the silver particles obtained in Synthesis Example 3 were mixed so that the content ratio (weight) of the silver particles became 30:70, and 10% of the total weight was added. Terpineol to obtain a dispersion. Using MAZERUSTAR manufactured by KURABO INDUSTRIES LTD., the liquid was mixed in the secondary stirring priority mode to prepare each conductive adhesive.

Next, prepare a base material with 0.5μm electroless silver plating applied to the copper plate, and coat each conductive adhesive evenly on it so that the thickness of the coating film becomes 50μm, and the back side (adhesive to the conductive The silicon wafer (size 2mm×2mm) with gold plating or gold sputtering treatment is placed on it. The sintered coating film of each conductive adhesive is prepared by heating the material at a predetermined temperature for 60 minutes in a dryer (circulation type). For the obtained coating film, the evaluation of mechanical strength and the evaluation of cracks and breakage of the coating film were performed in the same manner as in Examples 1 to 5 and Comparative Examples 1 to 5. And the results are shown in Table 3.

[table 3]

As is clear from the results shown in Table 2, the mixing ratio of 5:95~40:60 in mass ratio contains silver particles (20nm) using oleic acid for the protective layer and ricinoleic acid for the protective layer. The conductive adhesives of Examples 1 to 5 of silver particles (80nm), at a sintering temperature of 150°C and 175°C, are equivalent to those of Comparative Examples 1 to 5 outside the range of the mixing ratio. In contrast, the shear strength of the coating film is high, and there is no cracking and cracking of the coating film. In addition, in the case of a mass ratio of 45:55 (Comparative Example 2) and 50:50 (Comparative Example 3), although the shear strength of the coating film can also obtain the same value as the example, the coating film has turtles. Crack and rupture. It is speculated that this is because the content of 20nm particles will exert stress on the sintered coating film. In addition, in Comparative Example 6, although the mixing ratio of mass 70:30 contains silver particles (70nm) using oleic acid as a protective layer and silver particles (80nm) using ricinoleic acid as a protective layer, it is different from Compared with the lower coating film, the shear strength of Examples 1 to 5 is lower, and the coating film is cracked and broken.

(Comparative Examples 7~14) The silver particles obtained in Synthesis Example 2 and the silver particles obtained in Synthesis Example 3 were mixed at the predetermined ratio shown in Table 4, and 10% of the total weight of terpineol was added to obtain dispersion liquid. Using MAZERUSTAR manufactured by KURABO INDUSTRIES LTD., the liquid was mixed in the secondary stirring priority mode to prepare each conductive adhesive.

Next, prepare a base material with 0.5μm electroless silver plating applied on the copper plate, and coat each conductive adhesive evenly on it so that the thickness of the coating film becomes 50μm, and the back side (with the conductive adhesive The contact surface) a silicon wafer (size 2mm×2mm) with gold plating or gold sputtering treatment is placed on it. The sintered conductive adhesive film was prepared by heating the material at a predetermined temperature (150°C, 175°C) in a dryer (circulation type) for 60 minutes. For the obtained coating film, the evaluation of mechanical strength and the evaluation of cracks and breakage of the coating film were performed in the same manner as in Examples 1 to 5 and Comparative Examples 1 to 5. And the results are shown in Table 4.

如從表4所示之結果清楚得知，於混合了將油酸用於保護層之銀微粒子(20nm)與將油酸用於保護層之銀微粒子(70nm)之比較例7~14中，不論於任一混合比率下塗膜之剪切強度皆低且皆有塗膜之龜裂及破裂。[Table 4]

As is clear from the results shown in Table 4, in Comparative Examples 7 to 14 in which silver particles (20nm) using oleic acid as a protective layer and silver particles (70nm) using oleic acid as a protective layer were mixed, Regardless of the mixing ratio, the shear strength of the coating film is low and there are cracks and cracks in the coating film.

(no)

Claims (9)

A conductive adhesive containing: first silver particles A, which has a first protective layer and an average particle size of 10nm~30nm; and second silver particles B, which has a second protective layer and an average particle size of 50nm~100nm Wherein, the second protective layer contains hydroxy fatty acid; and the mass ratio (A:B) of the first silver particles A and the second silver particles B is in the range of 5:95-40:60. The conductive adhesive of claim 1, wherein the first protective layer contains at least one of fatty acid and alkylamine. The conductive adhesive of claim 1 or 2, wherein the total ratio of the first silver particles A and the second silver particles B is 80% by mass or more. Such as the conductive adhesive of claim 1 or 2, which further contains a solvent. Such as the conductive adhesive of claim 3, which further contains a solvent. A method of manufacturing a conductive adhesive includes the following steps: the first silver microparticle A and the second silver microparticle B so that the mass ratio (A:B) of the first silver microparticle A to the second silver microparticle B is 5: Mixing in the range of 95-40:60, wherein the first silver particles A has a first protective layer and an average particle size of 10nm-30nm, and the second silver particles B have a second protective layer containing hydroxy fatty acid and The average particle size is 50nm~100nm. A sintered body of a conductive adhesive, the conductive adhesive being the conductive adhesive according to any one of claims 1 to 5. A circuit having parts where components have been bonded by a sintered body as in Claim 7. An electrode having a part where members have been bonded by a sintered body as in Claim 7.