TW201936818A - Composition for bonding - Google Patents

Abstract

The invention provides a composition for bonding, which enables bonding without pressurization at relatively low temperatures, and which enables the achievement of excellent bonding strength. A composition for bonding according to the invention contains first metal particles that have an average particle diameter of 20-100 nm and a dispersion medium; and the content of the dispersion medium relative to the entire amount of the composition for bonding is 1.0% by weight or more but less than 5.0% by weight.

Description

Composition for bonding

The present invention relates to a bonding composition containing metal particles.

Conventionally, a joining material is used for mechanically, electrically, and / or thermally joining a metal part to a metal part. Examples of the bonding material include solder, a conductive adhesive, a silver paste, and an anisotropic conductive film. These joining materials are used not only for joining metal parts to each other, but also for joining metal parts, ceramic parts, resin parts, and the like. For example, in recent years, a bonding material is sometimes used for a purpose of bonding a light emitting element such as a light emitting diode (LED), a semiconductor wafer, or the like to a substrate, or a purpose of bonding these substrates to a heat radiation member.

High-luminance lighting devices or light-emitting devices including light-emitting elements such as LEDs, and semiconductor devices including semiconductor devices that perform high-efficiency operations at high temperatures, such as power devices, tend to have high driving temperatures during device use. The melting point of solder is lower than the driving temperature of these devices, so it is not suitable for bonding light-emitting elements such as LEDs and semiconductor wafers. Furthermore, in recent years, lead-free bonding has been required from the viewpoints of environmental protection or "European Parliament and Council Directive (RoHS) concerning restrictions on the use of certain hazardous substances contained in electrical and electronic equipment". material.

As a new bonding material having high heat resistance and containing no lead, a bonding composition containing metal nano particles has been studied (for example, refer to Patent Documents 1 to 3).

Patent Document 1 discloses a metal paste in which a solid content containing silver particles and a solvent are kneaded, and the solid content includes a particle size of 100 nm or more and a particle size of 100 nm or more. Silver particles of ~ 200 nm silver particles, the average particle diameter of the solid silver particles as a whole is 60 nm to 800 nm, and the total of the silver particles constituting the solid content and the carbon number as the protective agent is 4 to 8 amine The compounds are bonded, and the thermal peak caused by sintering of silver particles in Thermogravimetry-Differential Thermal Analysis (TG-DTA) appears at less than 200 ° C.

Patent Document 2 discloses a composition for metal bonding, which is characterized by containing an average particle diameter of two or more kinds of metal particles having different average particle diameters, an organic component, and a dispersant, and the smallest average particle diameter of metal particles S D _S and the maximum average particle diameter of metal particles of an average particle diameter D _L L diameter ratio (D _S / D _L) of 1 × 10 ^-4 ~ 0.5.

Patent Document 3 discloses a silver fine particle composition including silver fine particles, a dispersant containing an alkoxyamine, and a dispersion medium, and the content of the dispersant relative to the content of the silver fine particles is 0.1% to 7.0% by mass, and the weight loss when heated from room temperature to 200 ° C is 70% by mass or more of all organic components contained.
[Prior Art Literature]
[Patent Literature]

[Patent Document 1] Japanese Patent No. 5795096
[Patent Document 2] International Publication No. 2014/185073
[Patent Document 3] International Publication No. 2016/166948

[Problems to be Solved by the Invention]
Conventionally, in the bonding using metal nano particles, the bonding may be performed while applying pressure in an inert environment at 300 ° C to 350 ° C. In addition, in the bonding of light-emitting elements such as LEDs, semiconductor wafers, and the like, from the viewpoint of preventing damage to these devices at the time of bonding, it is desirable that they can be sintered at a firing temperature of less than 300 ° C.

Furthermore, in recent years, devices including light-emitting elements such as LEDs, semiconductor wafers, and the like have been required to increase their output, and they have been required to be highly integrated or have increased power input. Therefore, the driving temperature of these devices is further increased, and the use environment of the bonding material tends to be more severe. Therefore, high bonding strength is required for the bonding of light-emitting elements such as LEDs and semiconductor wafers. The Patent Documents 1 to 3 disclose metal pastes and the like containing silver nano particles, and also disclose that sintering can be performed at a relatively low temperature, but there is room for further research in order to achieve higher bonding strength.

The present invention has been made in view of the problems described above, and an object thereof is to provide a bonding composition that can be bonded without pressure even at a relatively low temperature and can obtain excellent bonding strength.
[Means for solving problems]

The present inventors paid attention to the fact that the concentration of solid components derived from the metal particles in the bonding composition is important in order for the sintered body of the bonding composition to exhibit excellent bonding strength, and found that by reducing the bonding The content of the dispersion medium contained in the composition allows sufficient bonding strength to be obtained even when used for bonding light emitting elements such as LEDs and semiconductor wafers. The present inventors and the like have conducted further research and found that the density of the sintered body of the bonding composition can be increased by reducing the amount of the dispersion medium in the bonding composition. On the other hand, if the amount of the dispersion medium is too small, the bonding The viscosity of the composition is increased, and the handleability is reduced, and the present invention has been achieved.

That is, the present invention is a bonding composition containing first metal particles having an average particle diameter of 20 nm to 100 nm and a dispersion medium, and the content of the dispersion medium with respect to the entire bonding composition is 1.0% by weight or more and less than 5.0% by weight.

The coefficient of variation of the primary particle size represented by the following formula (1) of the first metal particle is preferably 25.0% or more and 50.0% or less.

Coefficient of variation (%) = standard deviation of primary particle size / average primary particle size × 100 (1)

It is preferable to further contain the second metal particles having an average particle diameter of 200 nm to 500 nm.

The weight ratio of the first metal particles to the second metal particles is preferably 20:80 to 80:20.

Preferably, the first metal particles are covered with an organic protective component.

Preferably, the organic protective component contains at least one amine having a boiling point of 150 ° C or lower.

The bonding composition preferably further contains a polymer dispersant.
[Effect of the invention]

According to the present invention, it is possible to provide a bonding composition that can be bonded without pressure even at a relatively low temperature and can obtain excellent bonding strength.

The bonding composition according to this embodiment is a bonding composition containing first metal particles having an average particle diameter of 20 nm to 100 nm and a dispersion medium, and the dispersion medium is relative to the bonding composition. The total content is 1.0% by weight or more and less than 5.0% by weight.

The first metal particles have an average particle diameter of 20 nm to 100 nm. The bonding composition can sinter metal particles with each other at a firing temperature exceeding 200 ° C. However, by setting the average particle diameter of the first metal particles to 20 nm to 100 nm, the melting point decreases, even if the The metal particles can also be sintered at a relatively low temperature (for example, 200 ° C. or lower, preferably about 150 ° C.). In addition, the dispersibility of the first metal particles in the bonding composition can be made less likely to change with time. When the average particle diameter of the first metal particles is less than 20 nm, the surface area of the first metal particles becomes larger, the viscosity of the bonding composition becomes higher, and the handleability decreases. In addition, when the surface of the first metal particles is covered with an organic protective component, the amount of the organic protective component increases, and organic matter remains after firing, and the density of the sintered body decreases, so the bonding strength decreases. On the other hand, if the average particle diameter of the first metal particles exceeds 100 nm, it is difficult to cause a decrease in the melting point, and it is difficult for the metal particles to sinter at a relatively low temperature. A preferred lower limit of the average particle diameter of the first metal particles is 25 nm, and a preferred upper limit is 80 nm. In the present specification, the "average particle diameter" refers to the primary average particle diameter of the metal particles and is an exponential average particle diameter. The number-average particle diameter can be obtained by using an image processing software (for example, Mitani Corporation (for example, Mitani Corporation ( MITANI CORPORATION), WinROOF).

The first metal particles are not particularly limited, and for example, particles of at least one metal selected from the group consisting of gold, silver, copper, nickel, bismuth, tin, and platinum group elements are preferred. The first metal particles are more preferably particles of copper or a metal having a smaller (more expensive) ionization tendency than copper, that is, at least one metal of gold, platinum, silver, and copper. These metals may be used alone or in combination of two or more. As a method of using two or more metals in combination, there are a case where an alloy particle containing a plurality of metals is used, or a metal particle having a core-shell structure or a multilayer structure is used.

When silver fine particles are used as the first metal particles, the electrical conductivity of the sintered body (sintered layer) formed using the bonding composition of the present embodiment is good. By using particles containing other metals in combination with the silver fine particles, it is difficult to cause migration. As the "other metal", the metal having a higher ionization tendency than hydrogen, that is, gold, copper, platinum, and palladium is preferable.

The bonding composition contains a dispersion medium. By containing a dispersion medium, the viscosity of the bonding composition can be adjusted and the handleability can be made good.

Content of the said dispersion medium with respect to the whole bonding composition is 1.0 weight% or more and less than 5.0 weight%. When the content of the dispersion medium is less than 1.0% by weight, the shear viscosity of the bonding composition is too high, the handling properties are poor, and it is difficult to apply it to the member to be bonded. On the other hand, if the content of the dispersion medium is 5.0% by weight or more, the weight reduction rate obtained by thermal analysis up to 25 ° C to 550 ° C will increase. In addition, since the content of metal particles in the bonding composition is reduced, the density of the sintered body is reduced, and sufficient bonding strength cannot be obtained.

As said dispersion medium, various dispersion media can be used in the range which does not impair the effect of this invention, For example, water or an organic solvent can be used. Examples of the organic solvent include hydrocarbons and alcohols.

Examples of the hydrocarbon include aliphatic hydrocarbons, cyclic hydrocarbons, and alicyclic hydrocarbons. These hydrocarbons may be used alone or in combination of two or more kinds.

Examples of the aliphatic hydrocarbon include tetradecane, octadecane, heptamethylnonane, tetramethylpentadecane, hexane, heptane, octane, nonane, decane, and tridecane. Saturated or unsaturated aliphatic hydrocarbons such as methylpentane, normal paraffin, and isoparaffin.

Examples of the cyclic hydrocarbon include toluene and xylene.

Examples of the alicyclic hydrocarbon include limonene, dipentene, terpinene, terpinene (also referred to as terpinene), nesol, cinene, Orange flavor, terpineolene, isoterpinene (also known as terpineolene), phellandrene, menthadiene, terebene, dihydroumbrene Dihydrocymene, γ-terpinene (moslene), isoterpinene, isoterpinene (also known as isoterpinene), crienmene, kautschin, lutein (Cajeputene), eulimen, pinene, turpentine, menthane, pinane, terpene, cyclohexane and the like.

The alcohol is a compound containing one or more OH groups in a molecular structure, and examples thereof include aliphatic alcohols, cyclic alcohols, and alicyclic alcohols, which may be used individually or in combination of two or more. In addition, a part of the OH group may be derived from ethoxyl or the like within a range that does not impair the effect of the present invention.

Examples of the aliphatic alcohol include heptanol, octanol (1-octanol, 2-octanol, 3-octanol, etc.), decanol (1-decanol, etc.), and tridecanol (isodecyl alcohol) Triol, etc.), lauryl alcohol, tetradecyl alcohol, cetyl alcohol, 2-ethyl-1-hexanol, stearyl alcohol, hexadecenol, oleyl alcohol, etc. 6 to 30 saturated or unsaturated aliphatic alcohols.

Examples of the cyclic alcohol include cresol, eugenol, and the like. Further, as the alicyclic alcohol, for example, a cycloalkanol such as cyclohexanol, terpineol (including α, β, γ isomers, or any of these mixtures), and dihydroterpineol are exemplified. Isoterpenols (monoterpene alcohols, etc.), dihydroterpineol, myrtenol, sobrerol, menthol, carveol, perillyl alcohol), pinocarveol, sobrerol, verbenol, etc.

The weight reduction rate W of the bonding composition when heated at 25 ° C. at a heating rate of 10 ° C./minute to 550 ° C. is preferably 0.6% ≦ W ≦ 5.5%. When the composition for bonding is heated to 550 ° C., the dispersion medium evaporates, and the organic matter covering the metal particles is oxidatively decomposed, and most of it vaporizes and disappears. Therefore, the weight reduction rate W obtained by heating to 550 ° C. corresponds to the sum of the amount of the dispersion medium and the amount of the organic matter in the solid content. The smaller the weight reduction rate W, the higher the content of metal particles in the bonding composition. By setting the weight reduction rate W to 0.6% ≦ W ≦ 5.5%, the content of metal particles in the bonding composition is high, and a high-density sintered body can be obtained, so that more excellent bonding strength can be achieved. When the weight reduction rate W is less than 0.6%, the fluidity of the bonding composition may be reduced, and the handleability may be reduced. On the other hand, when the weight reduction rate W exceeds 5.5%, since the content of the metal particles in the bonding composition is small, the density of the sintered body may decrease and the bonding strength may decrease. The preferable lower limit of the weight reduction rate W is 1%, the more preferable lower limit is 2%, and the preferable upper limit is 5.4%. The weight reduction rate can be measured by a thermogravimetric method.

The first metal particles are preferably such that the coefficient of variation of the primary particle size represented by the following formula (1) is 25.0% or more and 50.0% or less. The standard deviation of the following primary particle diameter can be calculated from the image data used in the measurement of the average particle diameter.

Coefficient of variation (%) = standard deviation of primary particle size / average primary particle size × 100 (1)

The large coefficient of variation means a wide particle size distribution. When the average particle diameter of the first metal particles is the same, when the metal particles having a large coefficient of variation are used, the fluidity of the bonding composition is improved compared with the case where the metal particles having a small coefficient of variation are used. The reason is considered to be that the specific surface area of the metal particles is reduced, and thereby the interaction between the metal particles is reduced. When the coefficient of variation of the primary particle diameter of the first metal particles is 25.0% or more, the fluidity of the obtained bonding composition is improved. As a result, the amount of the viscosity adjustment solvent (dispersion medium) to be input can be reduced, and the solid content concentration in the bonding composition can be further increased. If the coefficient of variation is less than 25.0%, the effect of improving the fluidity of the bonding composition may not be sufficiently obtained in some cases. The upper limit of the coefficient of variation is not particularly limited. In terms of manufacturing problems of the first metal particles, the coefficient of variation is preferably 50.0% or less. A more preferable lower limit of the coefficient of variation is 27.0%, and a more preferable upper limit is 45.0%. The fluidity of the bonding composition also changes according to the average particle diameter of the first metal particles, and the smaller the average particle diameter of the first metal particles, the higher the shear viscosity of the bonding composition and the lower the fluidity, but By adjusting the coefficient of variation of the first metal particles, an appropriate fluidity can be obtained even when the first metal particles having a small average particle diameter are used.

The bonding composition preferably further contains second metal particles having an average particle diameter of 200 nm to 500 nm. By using the second metal particles having an average particle diameter of 200 nm to 500 nm in combination, volume shrinkage during firing can be suppressed, cracks are hardly generated, and a sintered body having a higher density can be obtained. If the average particle diameter of the second metal particles is less than 200 nm, the volume shrinkage during firing may not be sufficiently suppressed in some cases. On the other hand, if the average particle diameter of the second metal particles exceeds 500 nm, when the bonding composition of the present embodiment is held between the members to be bonded, voids may be generated due to the metal particles having a large particle diameter. , And the joint strength is reduced. A more preferable lower limit of the average particle diameter of the second metal particles is 250 nm, and a more preferable upper limit is 400 nm. The average particle diameter of the second metal particles can be measured by the same method as the average particle diameter of the first metal particles.

As the second metal particles, metal particles of the same type as the metal particles exemplified in the first metal particles can be used. The metal constituting the second metal particles may be the same as or different from the first metal particles.

The weight ratio of the first metal particles to the second metal particles is preferably 20:80 to 80:20. Thereby, low-temperature sinterability can be achieved, and the bonding strength can be further improved. If the weight of the first metal particles is less than 20 parts by weight with respect to 80 parts by weight of the second metal particles, the proportion of the first metal particles having an average particle diameter in the bonding composition of 20 nm to 100 nm changes. It is low, and metal particles are difficult to sinter with each other at a relatively low temperature. On the other hand, if the weight of the first metal particles exceeds 80 parts by weight with respect to 20 parts by weight of the second metal particles, the volume shrinkage during firing becomes large, and cracks easily occur in the sintered body, so that there is joint strength. Reduced tendency. A better weight ratio of the first metal particles to the second metal particles is 30:70 to 60:40. If the weight of the second metal particles is greater than the weight of the first metal particles, the fluidity and handling properties of the bonding composition are reduced, and the weight reduction rate tends to decrease. Therefore, The weight ratio of the first metal particles to the second metal particles can be determined in consideration of the balance between the handleability and the weight reduction rate.

The first metal particles are preferably coated with an organic protective component. The organic protective component is a component that is bonded to at least a part of the surface of the first metal particle and forms a colloid. The organic protective component does not need to cover the entire surface of the first metal particles, as long as it covers at least a part of the surface of the first metal particles to such an extent that a colloid can be formed. By coating the first metal particles with an organic protective component, the dispersion stability of the first metal particles can be improved and aggregation can be prevented. If the organic protective component remains during the firing, the metal particles are prevented from being welded to each other. Therefore, as the organic protective component, a component that evaporates or decomposes during the firing is preferably used. From such a viewpoint, it is desirable that the organic protective component is an amine used to be detached from the surface of the first metal particle at a relatively low temperature. The second metal particles are also preferably covered with an organic protective component.

The organic protective component preferably contains at least one amine having a boiling point of 150 ° C or lower. When the boiling point of the amine exceeds 150 ° C, when the composition for bonding is calcined at a relatively low temperature (for example, 200 ° C or lower, preferably about 150 ° C), organic protection which does not volatilize remains in the sintered body. Composition, and there is a concern that the metal particles are not sufficiently sintered with each other. It is also considered that the amine is chemically or physically bonded to the metal particles, or is changed to an anion or a cation. In this embodiment, the amine may also adopt an ion, an ion, or an ion derived from the amine.组合 等等。 State and so on.

The amine having a boiling point of 150 ° C. or lower may be linear or branched, and may have a side chain. Specific examples include methylamine, ethylamine, and propylamine. Among these, an alkylamine or an alkoxyamine is preferable.

The amine may be, for example, a compound containing a functional group other than an amine such as a hydroxyl group, a carboxyl group, an alkoxy group, a carbonyl group, an ester group, and a mercapto group. In this case, the number of nitrogen atoms derived from the amine is preferably at least the number of functional groups other than the amine. The amines may be used alone or in combination of two or more.

The organic protective component is more preferably an amine having a boiling point of 150 ° C. or lower and a carbon number of 1 to 3. The carbon number of the amine refers to the carbon number of the main chain and does not include the carbon number of the functional group.

Examples of the amine having a boiling point of 150 ° C. or lower and a carbon number of 1 to 3 include 3-ethoxypropylamine, 3-methoxypropylamine, and the like.

The content of the organic protective component in the bonding composition is preferably from 0.1% by weight to 15% by weight. When the content of the organic protective component is 0.1% by weight or more, the conductivity of the obtained bonding composition tends to be good, and when it is 15% by weight or less, the dispersion stability of the bonding composition is good. tendency. A more preferable lower limit of the content of the organic protective component is 0.2% by weight, a more preferable upper limit is 5% by weight, a further preferable lower limit is 0.3% by weight, and a more preferable upper limit is 4% by weight. The content of the organic protective component can be measured by thermogravimetric analysis.

The bonding composition of the present embodiment preferably further contains a polymer dispersant. Thereby, the dispersibility of a metal particle can be improved.

A commercially available one can be used as the polymer dispersant. Examples of the commercially available products include: Sonupas 11200, Sonupas 13940, Sonupas 16000, Sonupas 17000, Sonupas 18000, Sonupas 20000, Sonupas 21000, Sonupas 24000, Sonupas 26000, Sonupas 27000, Sonupas 28000 (manufactured by Lubrizol (Japan)); DISPERBYK ) 142, Disparb 160, Disparb 161, Disparb 162, Disparb 163, Disparb 166, Disparb 170, Disparbike 180, Disparb 182, Disparb 184, Disparb 190, Disparb 2155 (manufactured by BYK-Chemie Japan (stock)); Efka ( EFKA) -46, EFKA-47, EFKA-48, EFKA-49 (manufactured by EFKA Chemical Company); polymer 100, polymer 120, polymer 150, polymer 400, polymer 401 , Polymer 402, polymer 403, polymer 450, polymer 451, polymer 452, polymer 453 (manufactured by EFKA Chemical Company); Ajisper PB711, Agispa PA111, Agispa PB811, Agispa PW911 (manufactured by Ajinomoto); Flolen DOPA-15B, Floren DOPA-22, Floren DOPA-17 , Floren TG-730W, Floren G-700, Floren TG-720W (manufactured by Kyoeisha Chemical Industry Co., Ltd.), etc.

From the viewpoint of low-temperature sinterability, the polymer dispersant is preferably Sonupas 11200, Sonupas 13940, Sonupas 16000, Sonupas 17000, Sonupas 18000, Sonup Perth 21000, Sonupas 28000, Despatch 142 or Despatch 2155.

The content of the polymer dispersant in the bonding composition is preferably 0.01 to 15% by weight. When the content of the polymer dispersant is 0.01% by weight or more, the dispersion stability of the obtained bonding composition tends to be good, and when it is 15% by weight or less, the conductivity of the bonding composition is changed. Good tendency. The more preferable lower limit of the polymer dispersant is 0.1% by weight, the more preferable upper limit is 5% by weight, the more preferable lower limit is 0.2% by weight, and the more preferable upper limit is 4% by weight.

In addition to the components described above, the bonding composition of the present embodiment may add, for example, an oligomer component, a resin component, and an organic solvent (which can make Partially dissolve or disperse), surfactant, thickener, or surface tension adjuster, etc. to impart appropriate viscosity, adhesion, drying, or printability functions to the purpose of use. The arbitrary component is not particularly limited.

Examples of the resin component include polyurethane resins such as polyester resins and block isocyanates, polyacrylate resins, polypropylene resins, polyether resins, melamine resins, These terpene-based resins may be used alone, or two or more of them may be used in combination.

The organic solvent is excluding those listed as the dispersion medium, and examples thereof include methyl alcohol, ethyl alcohol, n-propyl alcohol, 2-propyl alcohol, 1,3-propanediol, and 1,2- Propylene glycol, 1,4-butanediol, 1,2,6-hexanetriol, 1-ethoxy-2-propanol, 2-butoxyethanol, ethylene glycol, diethylene glycol, triethyl Glycol, polyethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol in a weight average molecular weight range of 200 to 1,000, and polypropylene glycol, N, N-diethylene glycol in a weight average molecular weight range of 300 to 1,000. Methylformamide, dimethylmethane, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, glycerol, acetone, etc. These can be used individually or in combination. More than that.

Examples of the thickener include clay minerals such as clay, bentonite, and hectorite, such as polyester-based emulsion resins, acrylic-based emulsion resins, polyurethane-based emulsion resins, or Emulsions such as block isocyanate, cellulose derivatives such as methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, xanthan gum, or Polysaccharides such as guar gum can be used individually or in combination of two or more.

The surfactant is not particularly limited, and any of anionic surfactants, cationic surfactants, and nonionic surfactants can be used, and examples thereof include alkylbenzenesulfonate and quaternary ammonium salts. Since the effect is obtained with a small amount of addition, a fluorine-based surfactant is preferred.

In the bonding composition of the present embodiment, the first metal particles are preferably present as metal colloidal particles. Examples of the form of the metal colloidal particles include metal colloidal particles composed of an organic substance attached to a part of the surface of the first metal particle, and metal colloids composed of the first metal particle as a core and whose surface is covered with an organic substance There are no particular restrictions on particles, metal colloidal particles, or the like formed by mixing them. Among these, metal colloidal particles having the first metal particle as a core and the surface of which is coated with an organic substance are preferred. The second metal particles are also preferably present as metal colloid particles. The organic protective component can be used as an organic substance covering the surfaces of the first metal particles and / or the second metal particles.

The shear viscosity of the bonding composition may be appropriately adjusted within a range that does not impair the effects of the present invention. The shear viscosity at 25 ° C is preferably 15 Pa · S to 120 Pa at a shear rate of 10 s ^-1 · S. By setting it as the said range, it can use suitably, for example, the use which joins light emitting elements, such as LED, a semiconductor wafer, etc. to a board | substrate, and this board | substrate further to a heat radiation member. The more preferable lower limit of the shear viscosity is 25 Pa · S, and the more preferable upper limit is 100 Pa · S.

The adjustment of the shear viscosity can be performed by adjusting the particle diameter of the metal particles, adjusting the content of organic matter, adjusting the addition amount of components other than the dispersion medium, adjusting the mixing ratio of each component, adding a thickener, and the like. get on. The shear viscosity can be measured using a cone plate type viscometer (for example, a Rheometer MCR301 manufactured by Anton Paar).

The joining strength when joining the members to be joined with the joining composition is preferably 20 MPa to 150 MPa. When the bonding strength is 20 MPa to 150 MPa, it can be suitably used for bonding light-emitting elements such as LEDs, semiconductor wafers and the like to a substrate, and bonding the substrate and a heat-radiating member. The more preferable lower limit of the bonding strength is 30 MPa, and the more preferable lower limit is 50 MPa. The bonding strength can be evaluated by applying a composition for bonding to one of the members to be bonded, attaching the other member to be bonded, and then calcining, and using the obtained laminated body, for example, a bonding tester ( A bond tester (manufactured by Rhesca) performs a bond strength test.

The bonding composition of this embodiment has excellent thermal cycle reliability. The above-mentioned thermal cycle has good reliability, and can be suitably used for bonding of light-emitting elements such as LEDs and semiconductor wafers in the manufacture of devices with high driving temperatures. The thermal cycle reliability can be evaluated, for example, by holding a laminated body formed by sintering a composition for joining and a member to be joined in an atmospheric environment at -40 ° C and 150 ° C for 10 minutes each. For 1 cycle, a 500-cycle thermal cycle test was performed. The thermal cycle test can be performed using, for example, a hot and cold impact tester (manufactured by Futec). The reduction rate of the bonding strength of the laminated body after the thermal cycle test with respect to the initial strength of the laminated body is preferably less than 20%, and more preferably less than 5%.

<Preparation of a bonding composition>
The method for producing the bonding composition according to this embodiment is not particularly limited. First, by adjusting the metal particle dispersion, mixing the metal particle dispersion and the dispersion medium, and the various components as necessary, the present invention can be obtained. The bonding composition of the embodiment.

As the method for preparing the metal particle dispersion, a method including the following steps: a first step of preparing a metal compound which can be decomposed and reduced to generate metal atoms and a mixed solution with an organic protective component; and a second step By reducing the metal compound in the mixed solution, metal particles having an organic protective component attached to at least a part of the surface are generated. Hereinafter, as a specific manufacturing method, a case where the first metal particles are made of silver fine particles and an amine is used as an organic protective component will be described as an example.

In the first step, it is preferable to add 2 mol or more of amine to 1 mol of silver. By setting the addition amount of the amine to be 2 mol or more with respect to 1 mol of silver, an appropriate amount of the amine can be attached to the surface of the silver fine particles generated by reduction, and the silver fine particles can be provided with various properties. Excellent dispersibility and low-temperature sinterability of the dispersion medium.

The composition of the mixed solution in the first step and the reduction conditions (for example, heating temperature and heating time) in the second step are such that the particle size of the obtained silver fine particles is 20 nm ～ 100 nm. The method for taking out silver fine particles from the metal particle dispersion obtained in the second step is not particularly limited, and examples thereof include a method of washing the metal particle dispersion and the like.

As a starting material for obtaining the silver fine particles coated with the organic component, various known silver compounds can be used, and for example, a silver salt or a hydrate of a silver salt can be used. Specific examples include silver salts such as silver nitrate, silver sulfate, silver chloride, silver oxide, silver acetate, silver oxalate, silver formate, silver nitrite, silver chlorate, and silver sulfide. These are not particularly limited as long as they can be reduced, and they may be dissolved in an appropriate solvent, or they may be dispersed in a solvent and used directly. These may be used alone or in combination. Among them, silver oxalate is preferred. Silver oxalate is the simplest silver dicarboxylate, and the silver oxalate amine complex synthesized using silver oxalate is reduced at a low temperature and in a short time. Therefore, it is suitable for the synthesis of the first metal particles in this embodiment. Furthermore, when silver oxalate is used, by-products are not generated during synthesis, and only carbon dioxide derived from oxalate ions is discharged to the outside of the system. Therefore, there is less time for purification after synthesis.

The method of reducing the silver compound is preferably a method of heating. The heating method is not particularly limited. Examples of the method for reducing the silver compound by heating include a method of heating a compound formed from a silver compound such as silver oxalate and an organic component such as an amine to heat the compound contained in the compound. Metal compounds such as oxalate ions decompose and condense the generated atomic silver. By this method, silver fine particles coated with an organic protective component such as amine can be produced.

As described above, in the metal amine complex decomposition method for producing amine-coated silver fine particles by thermally decomposing a silver compound complex compound in the presence of an amine, the decomposition of a silver amine complex which is a single type of molecule is used. The reaction generates atomic silver, so atomic silver can be uniformly generated in the reaction system. Therefore, as compared with the case where silver atoms are generated by the reaction between a plurality of components, the non-uniformity of the reaction due to the composition fluctuation of the components constituting the reaction is suppressed, which is particularly advantageous when a large amount of silver powder is produced on an industrial scale.

In addition, it is presumed that in the metal amine complex decomposition method, the amine molecule is coordinated and bonded with the generated silver atom, and the movement of the silver atom during aggregation is controlled by the action of the amine molecule coordinated to the silver atom. . As a result, very fine metal particles with a narrow particle size distribution can be produced by the metal amine complex decomposition method.

Furthermore, a large number of amine molecules also produce a relatively weak coordination bond on the surface of the produced silver fine particles. The surfaces of the silver fine particles form a dense protective coating, so that they can be manufactured with excellent storage stability and clean surfaces. Organic Coated Silver Particles. In addition, since the amine molecules forming the coating can be easily removed by heating or the like, silver fine particles that can be sintered at a very low temperature can be produced.

In addition, when a solid silver compound is mixed with an amine to form a compound such as a compound, an amine is mixed with a dispersant having an acid value that constitutes a film covering the silver fine particles, thereby easily generating a compound such as a compound. A composite compound is produced by short-term mixing. In addition, by using the amine in combination, coated silver fine particles having characteristics corresponding to various uses can be produced.

In the dispersion liquid containing silver fine particles coated with an organic protective component such as amine, in addition to the silver fine particles, a counter ion, a dispersant, and the like of a metal salt also exist in the dispersion liquid, and the electrolyte concentration or the organic substance concentration of the entire liquid High tendency. Liquids in this state cause coagulation of metal particles due to reasons such as high electrical conductivity and are liable to precipitate. Moreover, even if it does not precipitate, if there exists a counter ion of a metal salt, an excessive dispersing agent, etc. which are more than the amount required for dispersion, there exists a possibility that electrical conductivity may deteriorate. Therefore, the silver fine particle-containing solution can be reliably obtained by washing the solution containing the silver fine particles to remove excess residues.

As the cleaning method, for example, a method of repeating the following steps can be mentioned: a dispersion liquid containing silver fine particles coated on the surface with an organic protective component is allowed to stand for a fixed time, the supernatant is removed, and a solvent for precipitating the silver fine particles is added. (For example, water, methanol, methanol / water mixed solvent, etc.) and stir the frame, let it stand for a fixed period again, and remove the supernatant. Examples of the other methods include a method of performing centrifugation instead of the standing, a method of desalting using an ultrafiltration device, an ion exchange device, or the like. By using such cleaning to remove excess residues and remove organic solvents, silver fine particles whose surface is covered with an organic protective component can be obtained.

The method of mixing the metal particle dispersion and the dispersion medium is not particularly limited, and it can be performed by a conventionally known method using a stirrer, stirrer, or the like. It can be stirred with items such as spatula, and an ultrasonic homogenizer with appropriate output can be selected.

＜ Joining method ＞
When the bonding composition of this embodiment is used, high bonding strength can be obtained even at a relatively low temperature (for example, 200 ° C. or lower, and preferably about 150 ° C.) for bonding members to be heated. That is, the bonding composition is applied to the bonding composition coating step between the first bonding member and the second bonding member, and the first bonding member and the second bonding member are coated. The bonding composition between the bonding members is subjected to a bonding step of firing and bonding at a desired temperature (for example, 200 ° C. or lower, preferably about 150 ° C.), so that the first bonded member and the second bonded member can be bonded. The joining member is joined.

In the joining step, the first member to be joined and the second member to be joined may be pressed in opposite directions, but in particular, it is an advantage of the present invention that sufficient joint strength can be obtained without pressing. One. The calcination may also be carried out stepwise or stepwise. The surface of the member to be joined may be coated with a surfactant or a surfactant on the surface in advance.

The "coating" is a concept that includes both the case where the bonding composition is applied in a planar shape and the case where the composition is applied (drawn) in a linear shape. The shape of the coating film including the bonding composition in a state before being fired by heating can be a desired shape. Therefore, the shape of the sintered body (bonding layer) obtained by firing the composition for joining may be planar or linear. The planar bonding layer and the linear bonding layer may be continuous or discontinuous, and may include a continuous portion and a discontinuous portion.

The first to-be-joined member and the second to-be-joined member are not particularly limited as long as they are members that can be coated with a composition for joining and fired and joined by heating. The heat-resistant member is damaged to the extent of temperature.

Examples of the material constituting the first joined member and the second joined member include polyamide (PA), polyimide (PI), and polyamide-imide imide (PAI), Polyethylene Terephthalate (PET), Polybutylene Terephthalate (PBT), Polyethylene Naphthalate (PEN), etc. Ester, Polycarbonate (PC), Polyether Sulfone (PES), vinyl resin, fluororesin, liquid crystal polymer, ceramic, glass, metal, etc.

The member to be joined may have various shapes such as a plate shape or a strip shape, and may be rigid or flexible. The thickness of the substrate can also be appropriately selected. For the purpose of improving adhesion or adhesion, or other purposes, a member having a surface layer formed thereon or a member having a surface treatment such as a hydrophilization treatment may be used.

Examples of the first to-be-joined member and the second to-be-joined member include resin substrates, metal plates, light-emitting elements such as LEDs, semiconductor wafers, and ceramic substrates on which electronic circuits are formed. Since the bonding composition of the present embodiment has high bonding strength of the sintered body obtained, it can also be suitably used for bonding a light-emitting element such as an LED, a semiconductor wafer, and the like to a metal substrate, a ceramic substrate, and the like.

Various methods can be used as the step of applying the bonding composition to the first member to be joined and the second member to be joined, and for example, dipping, screen printing, spray type, bar coating type, and spin coating can be used. Type, inkjet type, dispenser type, pin transfer method, stamping method, coating method using a brush, cast type, flexo type, gravure type, plate method, transfer method, Hydrophilic and hydrophobic pattern method, syringe type, needle transfer, stencil printing, etc. Among these, the bonding composition of the present embodiment can be suitably used in dispenser type, needle transfer, and stencil printing because of its high solid content concentration.

The method for performing the firing is not particularly limited. For example, a temperature of the bonding composition applied (painted) on the first member to be joined and the second member to be joined may be using a conventionally known oven or the like. For example, firing is performed at a temperature of 200 ° C. or lower, thereby bonding. The lower limit of the firing temperature is not necessarily limited, but is preferably a temperature at which the first joined member and the second joined member can be joined to each other, and a temperature in a range that does not impair the effect of the present invention. The lower limit of the calcination temperature is, for example, 100 ° C.

In addition, the bonding composition of this embodiment is different from a conventional composition that obtains the bonding strength after firing by thermal curing of an epoxy resin or the like. As described above, sufficient bonding can be obtained by sintering metal particles. strength. Therefore, even if the remaining organic matter is degraded, decomposed, or disappeared in a use environment where the temperature is higher than the temperature at the time of joining (calcination temperature) after joining, there is no fear of lowering the joint strength and the heat resistance is excellent.

According to the bonding composition of the present embodiment, even if it is calcined by low-temperature heating at a temperature of 200 ° C. or lower, and preferably about 150 ° C., excellent bonding strength can be obtained. Therefore, relatively heat-resistant bonded members can be bonded to each other. Join. In addition, the firing time is not particularly limited, and depending on the firing temperature, any firing time that can be joined may be used.

In this embodiment, since the adhesiveness between the first joined member and / or the second joined member and the bonding layer is further improved, the first joined member and / or the second joined member can also be performed. Surface treatment. Examples of the surface treatment method include a method of performing a dry treatment such as a corona treatment, a plasma treatment, an ultra violet (UV) treatment, an electron beam treatment, or a base coat or a bonding agent provided in advance on the substrate. The method of using the receiving layer of the composition.

As mentioned above, although embodiment of this invention was described, this invention is not limited only by these contents. The bonding composition according to this embodiment may further contain, for example, inorganic particles such as tin-doped indium oxide, aluminum oxide, barium titanate, and lithium iron phosphate which are excellent in electrical conductivity, thermal conductivity, dielectric properties, and ion conductivity.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited only by these examples.
[Example]

＜ First metal particle ＞
(1-1) Metal particles A1
11.0 g of 3-ethoxypropylamine (Fuji Soft Tablets and Kogyo Pure Chemicals Co., Ltd.) with 11.0 g of 3-methoxypropylamine (Fuji Soft Tablets and Kogyo Pure Chemicals Co., Ltd.) One stage, boiling point 120 ° C) 7.0 g are mixed and stirred thoroughly with a magnetic stirrer. While stirring, 10.0 g of silver oxalate was added thereto, and the obtained sticky substance was added to a thermostatic bath at 120 ° C., and reacted for about 15 minutes to obtain a reactant. After 10 ml of methanol was added to the reaction product and stirred, the silver fine particles were precipitated and separated by centrifugation, and the supernatant was discarded. This operation was repeated once more to obtain 6 g of metal fine particles A1.

The number-average primary particle size (arithmetic average primary particle size) of the obtained metal fine particles A1 was calculated using a particle image taken by a SEM (S-4800 type manufactured by Hitachi, Ltd.). The arithmetic average primary particle size is calculated using image processing software (MITANI CORPORATION, WinROOF) for a total of 200 or more particles from images of 5 or more points obtained at different shooting points. FIG. 1 is a graph showing the particle size distribution of the metal fine particles A1. The arithmetic mean primary particle size of the metal fine particles A1 is 50 nm, and the standard deviation is 14.2 nm. The coefficient of variation obtained by the following formula (1) was 28.4%.

Coefficient of variation (%) = standard deviation of primary particle size / average primary particle size × 100 (1)

(1-2) Metal particles A2
Except that silver oxalate was added to a mixed solution prepared by mixing 5.0 g of 3-ethoxypropylamine and 11.0 g of 3-methoxypropylamine, metal fine particles A2 were produced in the same manner as in the method for producing metal fine particles A1. FIG. 2 is a graph showing a particle size distribution of the metal fine particles A2. The arithmetic mean primary particle size of metal microparticles A2 was 28 nm, the standard deviation was 11.1 nm, and the coefficient of variation was 39.6%.

(1-3) Metal particles A3
Except that silver oxalate was added to a mixed solution obtained by mixing 13.0 g of 3-ethoxypropylamine and 11.0 g of 3-methoxypropylamine, metal fine particles A3 were produced in the same manner as in the method for producing metal fine particles A1. FIG. 3 is a graph showing a particle size distribution of the metal fine particles A3. The arithmetic average primary particle size of metal microparticles A3 was 34 nm, the standard deviation was 14.8 nm, and the coefficient of variation was 43.5%.

(1-4) Metal particles A4
Metal microparticles A4 were produced in the same manner as in the method for producing metal microparticles A1 except that silver oxalate was added to 15.0 g of 3-ethoxypropylamine instead of formulating 3-methoxypropylamine. FIG. 4 is a graph showing a particle size distribution of the metal fine particles A4. The arithmetic mean primary particle size of the metal fine particles A4 was 27 nm, the standard deviation was 6.0 nm, and the coefficient of variation was 22.2%.

(1-5) Metal particles A5
Metal microparticles A5 were produced in the same manner as in the method for producing metal microparticles A1, except that silver oxalate was added to 10.0 g of 3-ethoxypropylamine instead of 3-methoxypropylamine. FIG. 5 is a graph showing a particle size distribution of the metal fine particles A5. The arithmetic average primary particle size of metal microparticles A5 was 30 nm, the standard deviation was 5.9 nm, and the coefficient of variation was 19.7%.

(1-6) Metal particles A6
Silver oxalate was added to a mixed solution prepared by mixing 10.0 g of 3-ethoxypropylamine with 5.0 g of 2- (2-aminoethoxy) ethanol (Fuji film and reagent grade manufactured by Kosuke Pharmaceutical Co., Ltd.). Except for this, metal fine particles A6 were produced in the same manner as in the method for producing metal fine particles A1. FIG. 6 is a graph showing a particle size distribution of the metal fine particles A6. The arithmetic average primary particle size of the metal fine particles A6 was 45 nm, the standard deviation was 23.1 nm, and the coefficient of variation was 51.3%.

(1-7) Metal particles A7
Metal microparticles A7 were produced in the same manner as in the method for producing metal microparticles A1, except that silver oxalate was added to 15.0 g of 3-methoxypropylamine instead of 3-ethoxypropylamine. FIG. 7 is a graph showing a particle size distribution of the metal fine particles A7. The arithmetic average primary particle size of the metal fine particles A7 was 83 nm, the standard deviation was 29.1 nm, and the coefficient of variation was 35.1%.

(1-8) Metal particles A8
Metal microparticles A8 were produced in the same manner as in the method for producing metal microparticles A1, except that silver oxalate was added to 20.0 g of 3-ethoxypropylamine instead of formulating 3-methoxypropylamine. FIG. 8 is a graph showing a particle size distribution of the metal fine particles A8. The arithmetic average primary particle size of metal microparticles A8 was 19 nm, the standard deviation was 4.9 nm, and the coefficient of variation was 25.8%.

(1-9) Metal particles A9
Metal fine particles A9 were produced in the same manner as in the method for producing metal fine particles A1, except that silver oxalate was added to 20.0 g of 3-methoxypropylamine instead of formulating 3-ethoxypropylamine. FIG. 9 is a graph showing a particle size distribution of the metal fine particles A9. The arithmetic mean primary particle size of metal fine particles A9 was 112 nm, the standard deviation was 44.9 nm, and the coefficient of variation was 40.1%.

＜ Second metal particle ＞
(2-1) Metal particles B1
10.0 g of 3-ethoxypropylamine was mixed with 20.0 g of 2- (2-aminoethoxy) ethanol (Fuji film and reagent grade manufactured by Kosuke Pharmaceutical Co., Ltd.), and the mixture was thoroughly stirred with a magnetic stirrer . While stirring, 10.0 g of silver oxalate was added thereto, and the obtained viscous substance was added to a thermostatic bath at 120 ° C. and reacted for about 15 minutes to obtain a reactant. After 10 ml of methanol was added to the reaction product and stirred, the silver fine particles were precipitated and separated by centrifugation, and the supernatant was discarded. This operation was repeated once more to obtain 6 g of metal fine particles B1. FIG. 10 is a graph showing a particle size distribution of the metal fine particles B1. The arithmetic mean primary particle diameter of metal fine particles B1 is 300 nm, the standard deviation is 180 nm, and the coefficient of variation is 60.0%.

(2-2) Metal particles B2
Silver fine particles having an arithmetic average primary particle diameter of 340 nm, a standard deviation of 81.6 nm, and a coefficient of variation of 24.0% manufactured by the Institute of Rare Metal Materials were set as metal fine particles B2. FIG. 11 is a graph showing a particle size distribution of the metal fine particles B2.

(2-3) Metal particles B3
The silver oxalate was added to a mixed solution prepared by mixing 10.5 g of 2- (2-aminoethoxy) ethanol (Fuji film and Kogyo Pure Chemical Co., Ltd. reagent grade 1) with 10.0 g of silver oxalate. The same method as the metal fine particles B1 was used to obtain the metal fine particles B3. FIG. 12 is a graph showing a particle size distribution of the metal fine particles B3. The arithmetic average primary particle size of metal microparticles B3 was 150 nm, the standard deviation was 60 nm, and the coefficient of variation was 40.0%.

(2-4) Metal particles B4
Metal was obtained by the same method as that of metal fine particles B1 except that 10.0 g of 2- (2-aminoethoxy) ethanol (1st grade reagent manufactured by Fujifilm and Kogyo Pure Chemicals Co., Ltd.) was added with silver oxalate. Microparticle B4. The arithmetic mean primary particle diameter of metal fine particles B4 was 450 nm, the standard deviation was 189 nm, and the coefficient of variation was 42.0%.

<Composition for bonding>
(Example 1)
4 g of the metal fine particles A1 as the first metal particles and 4 g of the metal fine particles B1 as the second metal particles were mixed, and 0.32 g of 1-decanol as a dispersion medium and 0.016 g of a polymer dispersant were added. Sonupas 16000 was stirred and degassed to prepare a bonding composition of Example 1.

(Example 2)
Except that 3.2 g of the metal fine particles A1 as the first metal particles and 4.8 g of the metal fine particles B1 as the second metal particles were mixed, a bonding composition of Example 2 was prepared in the same manner as in Example 1.

(Example 3)
Except that 2.4 g of the metal fine particles A1 as the first metal particles and 5.6 g of the metal fine particles B1 as the second metal particles were mixed, a bonding composition of Example 3 was prepared in the same manner as in Example 1.

(Example 4)
Except that 4 g of the metal fine particles A2 as the first metal particles and 4 g of the metal fine particles B1 as the second metal particles were mixed, a bonding composition of Example 4 was prepared in the same manner as in Example 1.

(Example 5)
Except that 3.2 g of the metal fine particles A2 as the first metal particles and 4.8 g of the metal fine particles B1 as the second metal particles were mixed, a bonding composition of Example 5 was prepared in the same manner as in Example 1.

(Example 6)
A bonding composition of Example 6 was produced in the same manner as in Example 1 except that metal fine particles B2 were used as the second metal particles.

(Example 7)
Except that 3.2 g of the metal fine particles A1 as the first metal particles and 4.8 g of the metal fine particles B2 as the second metal particles were mixed, a bonding composition of Example 7 was prepared in the same manner as in Example 1.

(Example 8)
A bonding composition of Example 8 was prepared in the same manner as in Example 1 except that 0.23 g of 1-decanol was added as a dispersion medium.

(Example 9)
A bonding composition of Example 9 was prepared in the same manner as in Example 1 except that 0.15 g of 1-decanol was added as a dispersion medium.

(Example 10)
Except that 4.0 g of the metal fine particles A1 as the first metal particles and 4.0 g of the metal fine particles B3 as the second metal particles were mixed, a bonding composition of Example 10 was prepared in the same manner as in Example 1.

(Example 11)
A bonding composition of Example 11 was produced in the same manner as in Example 1 except that metal fine particles A4 were used as the first metal particles.

(Example 12)
A bonding composition of Example 12 was produced in the same manner as in Example 1 except that metal fine particles A5 were used as the first metal particles.

(Example 13)
A bonding composition of Example 13 was produced in the same manner as in Example 1 except that metal fine particles A3 were used as the first metal particles.

(Example 14)
A bonding composition of Example 14 was produced in the same manner as in Example 1 except that metal fine particles A6 were used as the first metal particles.

(Example 15)
A bonding composition of Example 15 was produced in the same manner as in Example 1 except that metal fine particles A7 were used as the first metal particles.

(Example 16)
Except that 4.0 g of the metal fine particles A2 as the first metal particles and 4.0 g of the metal fine particles B4 as the second metal particles were mixed, a bonding composition of Example 16 was produced in the same manner as in Example 1.

(Example 17)
Instead of adding the second metal particles, 6.0 g of the metal fine particles A1 as the first metal particles, 0.24 g of 1-decanol as the dispersion medium, and 0.012 g of Sonopas 16000 as the polymer dispersant were mixed. Other than that, the bonding composition of Example 17 was produced in the same manner as in Example 1.

(Comparative Example 1)
A bonding composition of Comparative Example 1 was produced in the same manner as in Example 1 except that the dispersion medium was not added.

(Comparative Example 2)
A joining composition of Comparative Example 2 was produced in the same manner as in Example 1 except that 0.016 g of 1-decanol was added as a dispersion medium.

(Comparative Example 3)
A bonding composition of Comparative Example 3 was produced in the same manner as in Example 1 except that 0.41 g of 1-decanol was added as a dispersion medium.

(Comparative Example 4)
A bonding composition of Comparative Example 4 was prepared in the same manner as in Example 1 except that 0.97 g of 1-decanol was added as a dispersion medium.

(Comparative Example 5)
Instead of adding the second metal particles, 4 g of the metal fine particles A2 as the first metal particles, 0.31 g of 1-decanol as the dispersion medium, and 0.035 g of Sonopas 16000 as the polymer dispersant, Other than that, the bonding composition of Comparative Example 5 was produced in the same manner as in Example 1.

(Comparative Example 6)
Rather than adding the second metal particles, 4 g of the metal fine particles A1 as the first metal particles, 0.31 g of 1-decanol as the dispersion medium, and 0.035 g of Sonopas 16000 as the polymer dispersant, Other than that, the bonding composition of Comparative Example 6 was produced in the same manner as in Example 1.

(Comparative Example 7)
A bonding composition of Comparative Example 7 was produced in the same manner as in Example 1 except that the metal fine particles A8 were used as the first metal particles.

(Comparative Example 8)
A bonding composition of Comparative Example 8 was produced in the same manner as in Example 1 except that metal fine particles A9 were used as the first metal particles.

＜ Evaluation ＞
(1) Measurement of weight reduction rate The weight reduction rate was measured by the thermogravimetric analysis method using a differential type differential thermal balance (TG8120, manufactured by Rigaku Corporation) for the bonding compositions of the examples and comparative examples. Specifically, the bonding composition was heated at a temperature rising rate of 10 ° C./minute in an atmospheric environment, and the weight reduction rate up to 25 ° C. to 550 ° C. was measured.

(2) Shear Viscosity For the compositions for bonding of Examples and Comparative Examples, a cone-plate viscometer (rheometer manufactured by Anton Paar, MCR301) was used to measure the shear rate under the following measurement conditions: Shear viscosity at s ^-1 (Pa · s).
(Measurement conditions)
Measurement mode: Shear mode Shear speed: 10 s ^-1
Measuring fixture: cone plate CP-50-2
(50 mm diameter, 2 ° angle, 0.045 mm clearance)
Measurement temperature: 25 ° C

(3) Bonding strength On a silver plated copper plate (20 mm square, 1 mm thick) with silver plating on the surface, 10 μg was placed using a die bonder (made by Hisol). A bonding composition, and a commercially available blue LED wafer (ES-CADBV24H manufactured by Epistar Corporation, bottom area: 600 μm × 600 μm, height: 150 μm) is laminated on the bonding composition, In addition, for each of the examples and comparative examples, a laminated body including a copper plate on which silver plating was applied, a composition for bonding, and a blue LED wafer was produced.

The obtained laminated body was put into a hot-air circulation type oven, heated from 25 ° C to 190 ° C in the atmosphere for 40 minutes, and calcined for 90 minutes. During the firing treatment, the laminated body is not pressurized. After taking out the laminated body, the bonding strength test was performed at room temperature using a bonding tester (bonding tester PTR1102 manufactured by Rhesca Co., Ltd.). In the bonding strength test, a tool having a width of 1.2 mm mounted on the weight sensor of the bonding tester was placed at a height of 10.0 μm from the surface of the copper plate, and the tool was set at 0.01 mm / sec. A tool is moved, and a bonding portion to be bonded by the bonding composition is pressed to measure a weight when the blue LED wafer is peeled from the copper plate, and is set as a bonding strength at the time of peeling. The bonding strength at the time of peeling was divided by the bottom area of the wafer to calculate the bonding strength (MPa) per unit area.

(4) Reliability of thermal cycle The laminated body calcined in the joint strength test was added to a cold and thermal shock tester (made by Futec), and each was maintained at -40 ° C and 150 ° C in an atmospheric environment for 10 minutes. This operation was set to 1 cycle for 500 minutes, and the laminated body after 500 cycles was taken out. The joint strength of the taken-out laminated body was measured, and when the reduction rate of the joint strength after the thermal cycle test from the initial strength before the thermal cycle test was 0 to less than 5%, it was ○, and 5% or more to When it is less than 20%, it is set to Δ, and when it is 20% or more, it is set to ×.

The composition and evaluation result of the bonding composition of an Example and a comparative example are put together in the following Table 1, Table 2, and Table 3.

[Table 1]

[Table 2]

[table 3]

The bonding compositions of Examples 1 to 17 all had moderate shear viscosity, good handling properties, and a weight reduction rate of 5.5% or less. The sintered bodies obtained from the bonding compositions of Examples 1 to 17 have excellent bonding strength and high thermal cycle reliability.

Comparing Example 1 to Example 3, Example 4 and Example 5, Example 6 and Example 7, respectively, it was confirmed that the example of the example in which the weight of the second metal particles is greater than the weight of the first metal particles The shear viscosity is lowered and the fluidity is increased. On the other hand, the weight reduction rate tends to decrease. From the results of Examples 1, 4, and 11 to 15, it was confirmed that even if the average particle diameter of the first metal particles is small, appropriate fluidity can be obtained by adjusting the coefficient of variation.

On the other hand, in Comparative Example 7 in which the average particle diameter of the first metal particles was less than 20 μm and Comparative Example 8 in which the average particle diameter of the first metal particles was more than 100 μm, sufficient thermal cycle reliability was not obtained.

When focusing on the content of the dispersion medium and comparing Example 1, Example 9, and Comparative Examples 1 to 4, the weight reduction amount decreases as the content of the dispersion medium becomes lower, but the content of the dispersion medium is less than 1.0. In Comparative Examples 1 and 2 by weight%, the viscosity of the bonding composition was too high to measure the shear viscosity. Comparative Example 1 was inferior in handleability, and the composition for bonding could not be formed into a film, and thus a sample for measurement could not be prepared. On the other hand, in Comparative Examples 3 and 4 in which the content of the dispersion medium was 5.0% by weight or more, the weight reduction rate exceeded 5.5%.

no

FIG. 1 is a graph showing the particle size distribution of the metal fine particles A1.

FIG. 2 is a graph showing a particle size distribution of the metal fine particles A2.

FIG. 3 is a graph showing a particle size distribution of the metal fine particles A3.

FIG. 4 is a graph showing a particle size distribution of the metal fine particles A4.

FIG. 5 is a graph showing a particle size distribution of the metal fine particles A5.

FIG. 6 is a graph showing a particle size distribution of the metal fine particles A6.

FIG. 7 is a graph showing a particle size distribution of the metal fine particles A7.

FIG. 8 is a graph showing a particle size distribution of the metal fine particles A8.

FIG. 9 is a graph showing a particle size distribution of the metal fine particles A9.

FIG. 10 is a graph showing a particle size distribution of the metal fine particles B1.

FIG. 11 is a graph showing a particle size distribution of the metal fine particles B2.

FIG. 12 is a graph showing a particle size distribution of the metal fine particles B3.

Claims (7)

A bonding composition is a bonding composition containing first metal particles having an average particle diameter of 20 nm to 100 nm and a dispersion medium, and is characterized in that: The content of the dispersion medium with respect to the entire bonding composition is 1.0% by weight or more and less than 5.0% by weight. The bonding composition according to item 1 of the scope of patent application, wherein the coefficient of variation of the primary particle size represented by the following formula (1) of the first metal particle is 25.0% or more and 50.0% or less, Coefficient of variation (%) = standard deviation of primary particle size / average primary particle size × 100 (1). The bonding composition according to claim 1 or claim 2, further comprising second metal particles having an average particle diameter of 200 nm to 500 nm. The bonding composition according to item 3 of the scope of patent application, wherein a weight ratio of the first metal particles to the second metal particles is 20:80 to 80:20. The bonding composition according to any one of claims 1 to 4, wherein the first metal particles are covered with an organic protective component. The bonding composition according to item 5 of the patent application range, wherein the organic protective component includes at least one amine having a boiling point of 150 ° C. or lower. The bonding composition according to any one of claims 1 to 6 of the scope of patent application, further comprising a polymer dispersant.