TW202231398A - Copper oxide paste and method for producing electronic parts capable of bonding a chip component and a substrate more firmly - Google Patents

Abstract

The present invention provides a copper-based paste capable of bonding a chip component and a substrate more firmly and obtaining a copper-based bonding material with high thermal conductivity. The copper oxide paste of the present invention includes copper-containing particles, a binder resin, and an organic solvent. The copper-containing particles contain Cu2O and CuO. The total amount of the copper element constituting Cu2O and the copper element constituting CuO is 90% or more of the copper element contained in the copper-containing particles. The copper-containing particles have a 50% cumulative particle size (D50) of more than 0.20 [mu]m and less than 5.0 [mu]m inclusive. The 50% cumulative particle size (D50) and the 10% cumulative particle size (D10) satisfy 1.3≤D50/D10≤4.9, the 50% cumulative particle size (D50) and the 90% cumulative particle size (D90) satisfy 1.2≤D90/D50≤3.7, and the BET specific surface area of the copper-containing particles is more than 1.0 m2/g and less than 8.0 m2/g.

Description

Copper oxide paste and method for producing electronic parts

The present invention relates to a manufacturing method of copper oxide paste and electronic parts. Specifically, the present invention relates to a copper oxide paste suitable for bonding a chip component to a substrate, and a method of manufacturing an electronic component using the copper oxide paste.

Chip components used in electronic components generate heat during operation. For example, chip components such as power devices and laser diodes generate a large amount of heat during operation due to their high operating power. The heat generated in this way can adversely affect the operation of the chip components. Therefore, by bonding the chip component to the substrate having heat dissipation properties, the heat of the chip component is conducted to the substrate, and the heat is dissipated from the substrate. As a bonding material at the time of bonding, a solder alloy is usually used, and in the bonding step, an alloy paste obtained by mixing solder alloy powder with a binder is used. However, since the thermal conductivity of solder alloys such as Sn alloys is lower than that of copper-based materials constituting electrodes or substrates, the heat generated from the chip components cannot be sufficiently conducted to the substrates.

Regarding the solder alloy paste used for bonding of power devices and the like, for example, Patent Document 1 proposes a solder alloy which contains 0.03 to 0.09 mass % of nickel and the remainder is bismuth, and discloses that it contains the solder alloy powder According to the alloy paste, it is revealed that the obtained alloy material has a high melting point and excellent ductility. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 6529632

[Problems to be Solved by Invention]

However, as the solder alloy material in Patent Document 1 uses expensive nickel or bismuth as a raw material, the manufacturing cost tends to increase.

Moreover, as an inexpensive metal material which can be used for the bonding material of a chip part and a board|substrate, copper (Cu) is mentioned, for example. However, in the conventional bonding using the copper-based paste containing copper powder, the adhesion between the chip component and the substrate was insufficient. Therefore, there is room for further improvement in order to efficiently conduct the heat of the chip component to the substrate and to firmly bond the chip component and the substrate.

The present invention is made in view of the above-mentioned actual situation, and an object thereof is to provide a copper-based paste which can bond a chip component and a substrate more firmly and obtain a copper-based bonding material with high thermal conductivity. [Technical means to solve problems]

Regarding the copper oxide paste containing copper-containing particles, a binder resin and an organic solvent, the present inventors focused on the content of copper elements constituting Cu ₂ O and CuO contained in the copper-containing particles, and the 10% cumulative particle size (D ₁₀ ), particle size distribution and BET specific surface area related to 50% cumulative particle size (D ₅₀ ) and 90% cumulative particle size (D ₉₀ ). As a result, the inventors found that the copper oxide paste specifying these matters can firmly bond the chip part and the substrate in the electronic part, and provide a copper-based bonding material with high thermal conductivity, thereby completing the present invention. Specifically, the present invention includes the following aspects (1) to (8). Furthermore, in this specification, the expression of "~" includes the numerical values at both ends thereof. That is, "X to Y" has the same meaning as "X or more and Y or less".

(1) The first aspect is a copper oxide paste, which contains copper-containing particles, a binder resin and an organic solvent, the copper-containing particles contain Cu ₂ O and CuO, and among the copper elements contained in the copper-containing particles, The total amount of copper elements constituting Cu ₂ O and copper elements constituting CuO is 90% or more, the 50% cumulative particle size (D ₅₀ ) of the above-mentioned copper-containing particles is 0.20 μm or more and 5.0 μm or less, and the above-mentioned 50% cumulative particle size ( D ₅₀ ) and the 10% cumulative particle diameter (D ₁₀ ) satisfy the following formula (1), and the above-mentioned 50% cumulative particle diameter (D ₅₀ ) and 90% cumulative particle diameter (D ₉₀ ) satisfy the following formula ( 2), and the BET specific surface area of the copper-containing particles is 1.0 m ² /g or more and 8.0 m ² /g or less. 1.3≦D ₅₀ /D ₁₀ ≦4.9 ・・・Formula (1) 1.2≦D ₉₀ /D ₅₀ ≦3.7 ・・・Formula (2)

(2) A second aspect is a copper oxide paste according to the above (1), wherein the amount of Cu ₂ O contained in the copper-containing particles to the amount of CuO is 1.0 or more in molar ratio .

(3) The third aspect is a copper oxide paste according to (1) or (2) above, wherein the copper-containing particles are 60% or more and 92% or less of the paste, and the shear rate is 1 sec ⁻¹ The viscosity at that time is 50 Pa·s or more and 2500 Pa·s or less.

(4) A fourth aspect is a method for producing an electronic component, comprising the step of disposing the copper oxide paste according to any one of the above (1) to (3) by coating or printing on a The surface of the substrate; and heat treatment in a reducing gas atmosphere at a temperature of 200° C. to 600° C. to obtain a copper sintered body on the substrate.

(5) A fifth aspect is a method for producing an electronic component, in the above (4), wherein the substrate is a metal substrate, an organic polymer substrate, a ceramic substrate, or a carbon substrate.

(6) A sixth aspect is a method for producing an electronic component, in the above (4) or (5), wherein the reducing gas atmosphere contains at least one selected from the group consisting of hydrogen, formic acid and alcohol gas.

(7) A seventh aspect is a method for producing an electronic component in any one of (4) to (6) above, wherein the copper sintered body has a resistivity of 2.5 μΩcm or more and 12 μΩcm or less.

(8) The eighth aspect is a method for manufacturing an electronic component, which is in any one of the above (4) to (7), further comprising the step of: drying the above-mentioned copper oxide paste before the above-mentioned heat treatment A pressure of 2 MPa or more and 30 MPa or less is applied from the surface of the above-mentioned chip parts to the direction of the above-mentioned substrate. [Effect of invention]

According to the present invention, it is possible to provide a copper-based paste that can more firmly bond a chip component and a substrate in an electronic component and obtain a copper-based bonding material with high thermal conductivity.

Hereinafter, specific embodiments of the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention.

1. Copper oxide paste The copper oxide paste of the present embodiment contains copper-containing particles, a binder resin, and an organic solvent. Further, the copper-containing particles contain Cu ₂ O and CuO, and the total amount of the copper elements constituting Cu ₂ O and the copper elements constituting CuO among the copper elements contained in the copper-containing particles is 90% or more. In addition, the 50% cumulative particle diameter (D ₅₀ ) of the copper-containing particles is 0.20 μm or more and 5.0 μm or less, and the 50% cumulative particle diameter (D ₅₀ ) and the 10% cumulative particle diameter (D ₁₀ ) satisfy the following formula (1) ), the 50% cumulative particle diameter (D ₅₀ ) and the 90% cumulative particle diameter (D ₉₀ ) satisfy the following formula (2). Furthermore, the BET specific surface area of the copper-containing particles is 1.0 m ² /g or more and 8.0 m ² /g or less. 1.3≦D ₅₀ /D ₁₀ ≦4.9 ・・・Formula (1) 1.2≦D ₉₀ /D ₅₀ ≦3.7 ・・・Formula (2)

When the above-mentioned copper oxide paste is heated in a reducing atmosphere, both Cu ₂ O and CuO in the copper-containing particles contained in the copper oxide paste are reduced to become metallic copper, and the copper-containing particles are sintered to become copper sintered body. For example, when the wafer components are bonded to the substrate using this copper oxide paste, the wafer components and the substrate can be firmly bonded.

In general, in order to form a copper sintered body, a copper-based paste containing metal copper particles as a main component is used. In the case of this type of copper-based paste, in order to prevent oxidation of metal copper particles, sintering is often performed in an inert gas atmosphere. On the other hand, since the copper oxide paste of the present invention is a paste containing copper-based particles mainly composed of copper oxide containing Cu ₂ O and CuO, it is possible to reduce copper oxide while heating in a reducing atmosphere. A copper sintered body is obtained by performing a sintering reaction of copper-based particles while forming metallic copper.

The copper oxide paste of the present invention can be sintered more easily than the copper-based paste containing metal copper particles as a main component. The reason for this is considered as follows. Generally speaking, the sintering of adjacent particles is achieved by the diffusion of atoms constituting the particles, so it can be said that the higher the diffusion coefficient of the atoms, the easier the sintering. Here, the diffusion coefficient (D) of atoms is represented by the formula "D=C _v D _v +C _i D _i ", and the above formula is the carrier of diffusion, namely the concentration of atomic vacancies (C _v ) and the concentration of atoms between lattices (Ci ) are multiplied by the diffusion coefficient of atomic vacancies (D _v ) and the diffusion coefficient of atoms between lattices (D _i ), respectively, and then added together. In general, the value of C _v D _v is much larger than the value of C _{i Di} , so the above formula of the diffusion coefficient D can be approximately expressed as D=C _v D _v .

In the case of sintering the copper-based paste containing metal copper particles in a nitrogen atmosphere, the atomic vacancy concentration _Cv corresponds to the concentration in the equilibrium state. On the other hand, in the case of reducing Cu ₂ O and CuO, oxygen ions are removed from Cu ₂ O and CuO, so the atomic vacancy concentration C _v is higher than the concentration in the equilibrium state, which is higher than that in the case of metallic copper particles. The concentration is two orders of magnitude higher. Therefore, compared with the copper-based paste containing metal copper particles, the sintering of the copper-based paste containing copper oxide proceeds at a high speed even at a low temperature, and the sintering can be performed very efficiently.

Therefore, when the copper oxide paste of the present invention is used, for example, as a bonding material for bonding chip parts to a substrate, it is obtained by sintering the copper oxide paste containing Cu ₂ O and CuO in a reducing atmosphere. The copper sintered body can bond the wafer part to the substrate very firmly. In this specification, the form used as a bonding material of a chip component and a board|substrate is demonstrated as an example below. This description is an example of the use form of the present invention, and the copper oxide paste of the present invention is not limited to this use form.

In general, Cu ₂ O particles have shapes such as cubes or octahedrons, and CuO particles have fibrous or thin plate shapes. Since the copper oxide paste of the present invention contains copper-containing particles including both Cu ₂ O and CuO, in the sintering process in a reducing atmosphere, there are gaps between Cu ₂ O particles such as cube-shaped or octahedral-shaped. Reduction and sintering are carried out by filling with fibrous or thin-plate CuO particles. Therefore, the density of copper atoms can be increased. As a result, the copper sintered body formed by the copper oxide paste has high thermal conductivity and extremely high bonding strength between the chip part and the substrate.

[Copper-Containing Particles] As described above, the copper-containing particles are one of the components contained in the copper oxide paste of the present invention, and are sintered in a reducing atmosphere to form a copper sintered body. The chip part and the substrate copper sintered body firmly joins the chip part and the substrate, and is responsible for the heat conduction between the two. In order to secure sufficient thermal conductivity and bonding strength in the copper sintered body, among the copper elements contained in the copper-containing particles, the total amount of the copper elements constituting Cu ₂ O and the copper elements constituting CuO is preferably 90 atomic %. % or more, more preferably 95% or more, 97% or more, or 98% or more.

The copper element contained in the copper-containing particles may be contained in the form of metallic copper or other copper compounds in addition to the copper element constituting Cu ₂ O and the copper element constituting CuO. The other copper compound is preferably a compound that becomes metallic copper in a reducing gas atmosphere. Elements other than copper (for example, Co, Ag, Sn, Ni, and Sb), even if contained in the copper-containing particles, do not become oxides by heating in a reducing gas atmosphere, and the content thereof is small. As long as the total amount of copper elements constituting Cu ₂ O and copper elements constituting CuO is 90% or more, thermal conductivity and bonding strength can be sufficiently ensured, so elements other than copper are allowed to be contained.

[Mole ratio of Cu ₂ O and CuO] If the amount of Cu ₂ O contained in the copper-containing particles is the molar ratio of the amount of Cu ₂ O contained in the copper-containing particles to the amount of CuO (Cu ₂ O/ The value of CuO) is preferably 1.0 or more, and more preferably 2.0 or more. If the molar ratio is less than 1.0, the amount of fibrous or thin-plate-like CuO particles becomes too large, so that the density of the obtained copper sintered body decreases, and as a result, the bonding strength and thermal conductivity decrease.

On the other hand, as for the molar ratio, the amount of CuO is preferably 100 or less, more preferably 50 or less, or 40 or less. If the molar ratio exceeds 100, the amount of CuO particles arranged in the gaps of the Cu ₂ O particles to promote the sintering of the Cu ₂ O particles becomes too small, so that the density of the obtained copper sintered body becomes low, and as a result, the bonding strength and Thermal conductivity is reduced.

Cu ₂ O and CuO contained in the copper-containing particles may exist in the form of separate particles, respectively, or may exist in the form of both Cu ₂ O and CuO in one particle. Moreover, it may be two or more kinds selected from the group consisting of particles including Cu ₂ O and not including CuO, particles including CuO and not including Cu ₂ O, and particles including both Cu ₂ O and CuO mixed existence.

[Content of Copper-Containing Particles] The content of the copper-containing particles is not particularly limited. Since the content of copper-containing particles in the copper oxide paste has an influence on the concentration of the vehicle in the paste, it is a factor closely related to the viscosity of the paste. The content of the copper-containing particles in the copper oxide paste is 60 mass % or more and 92 mass % or less with respect to the total amount of the copper oxide paste, so that the viscosity of the copper oxide paste when the shear rate is 1 sec ^-1 can be obtained 50 Pa·s or more and 2500 Pa·s or less. If the content of the copper-containing particles is less than 60 mass %, the viscosity decreases to less than 50 Pa·s, so the paste tends to be thinly spread and coated on the substrate. Therefore, the copper sintered body after sintering cannot be formed into a sufficient thickness, resulting in a decrease in bonding strength and thermal conductivity. On the other hand, if the content of copper-containing particles in the copper oxide paste exceeds 92% by mass, the viscosity of the paste increases to more than 2500 Pa·s, making it difficult to obtain a flat surface for the paste applied to the substrate. . Therefore, when the chip component is mounted on the substrate, the paste is prevented from spreading over the entire mounting surface of the chip component, the contact area with the substrate decreases, and the bonding strength and thermal conductivity decrease.

Thus, in order to ensure high bonding strength and high thermal conductivity, the content of the copper-containing particles in the copper oxide paste is preferably 60% or more and 92% or less with respect to the total amount of the copper oxide paste. The lower limit of the content is more preferably 65% by mass or more, or 70% by mass or more. On the other hand, the upper limit of the content is more preferably 90 mass % or less, or 85 mass % or less.

[Particle Size of Copper-Containing Particles] The 50% cumulative particle size (D ₅₀ ) of the copper-containing particles is preferably 0.20 μm or more and 5.0 μm or less. When the particle size of the copper-containing particles is small, the sintering of the particles is promoted. By making the 50% cumulative particle size (D ₅₀ ) of the copper-containing particles to be 5.0 μm or less, sintering at a low temperature can be performed. The sintered body imparts higher thermal conductivity. If the 50% cumulative particle size (D ₅₀ ) exceeds 5.0 μm, many voids are generated in the structure after sintering, and the thermal conductivity of the obtained copper sintered body is lowered. In addition, cracks are generated in the copper sintered body, resulting in bonding Intensity decreases. Therefore, the 50% cumulative particle diameter (D ₅₀ ) is preferably 5.0 μm or less, more preferably 4.9 μm or less, or 2.9 μm or less.

On the other hand, if the particle size of the copper-containing particles is too small, the sintering may proceed rapidly and cracks may be generated in the sintered body. If the 50% cumulative particle size (D ₅₀ ) is less than 0.20 μm, the volume shrinkage of the copper-containing particles becomes larger during sintering, and a large shear stress is generated at the interface between the chip part and the substrate, which is the reason for the peeling of the chip part from the substrate. . By setting the 50% cumulative particle size (D ₅₀ ) to 0.20 μm or more, rapid sintering of the copper-containing particles can be suppressed, and cracks can be prevented from occurring in the copper sintered body formed of the copper-containing particles, thereby preventing a decrease in the bonding strength. Therefore, the 50% cumulative particle diameter (D ₅₀ ) is preferably 0.20 μm or more. More preferably, it is 0.23 μm or more, or 0.32 μm or more.

Furthermore, the 50% cumulative particle diameter (D ₅₀ ) of the copper-containing particles, as well as the 90% cumulative particle diameter (D ₉₀ ) and 10% cumulative particle diameter (D ₁₀ ) described below are those obtained by laser diffraction The value measured by the particle size distribution meter.

The 50% cumulative particle diameter (D ₅₀ ) and the 10% cumulative particle diameter (D ₁₀ ) of the copper-containing particles preferably satisfy the following formula (1). "D ₅₀ /D ₁₀ " in the formula (1) represents the ratio of the 50% cumulative particle diameter (D ₅₀ ) to the 10% cumulative particle diameter (D ₁₀ ). 1.3≦D ₅₀ /D ₁₀ ≦4.9 ・・・Formula (1)

When sintered by the copper-containing particles in the copper oxide paste, the gaps between the large particles are filled with small particles, whereby a copper sintered body densely filled with copper particles can be obtained, thereby improving the thermal conductivity of the copper sintered body and bonding strength. Therefore, it is effective to include large and small particles to an appropriate extent. From this viewpoint, in order to widen the particle size distribution of the copper-containing particles and to include both large particles and small particles to an appropriate degree, D ₅₀ /D ₁₀ is preferably 1.3 or more.

On the other hand, if the large particles in the copper-containing particles become excessive and the content of the coarse particles increases, large voids may be generated by sintering of the coarse particles, and thus cracks may be generated in the copper sintered body. Therefore, it is effective to suppress the inclusion of coarse particles. From this point of view, D ₅₀ /D ₁₀ of 4.9 or less can suppress the content of coarse particles in the copper-containing particles, thereby suppressing the generation of large voids, and preventing the generation of cracks in the copper sintered body, so that the copper sintered body can be improved. D ₅₀ /D ₁₀ is preferably 4.9 or less in terms of thermal conductivity and bonding strength between the chip component and the substrate.

The value of D ₅₀ /D ₁₀ is not particularly limited as long as the relationship of 1.3≦D ₅₀ /D ₁₀ ≦4.9 is satisfied. The upper limit value of D ₅₀ /D ₁₀ is more preferably 4.5 or less, 4.0 or less, or 3.5 or less. The lower limit value of D ₅₀ /D ₁₀ is more preferably 2.8 or more, 2.9 or more, or 3.0 or more.

The 50% cumulative particle diameter (D ₅₀ ) and the 90% cumulative particle diameter (D ₉₀ ) of the copper-containing particles preferably satisfy the following formula (2). "D ₉₀ /D ₅₀ " in the formula (2) represents the ratio of the 90% cumulative particle diameter (D ₉₀ ) to the 50% cumulative particle diameter (D ₅₀ ). 1.2≦D ₉₀ /D ₅₀ ≦3.7 ・・・Formula (2)

By making D ₉₀ /D ₅₀ 1.2 or more, the particle size distribution of the copper-containing particles can be widened to include both large particles and small particles to an appropriate degree. Therefore, the gaps between the large particles are filled with small particles, so that a copper sintered body densely filled with copper particles can be obtained, and the thermal conductivity and bonding strength of the copper sintered body can be improved. From this viewpoint, D ₉₀ /D ₅₀ is preferably 1.2 or more.

On the other hand, if D ₉₀ /D ₅₀ is 3.7 or less, the inclusion of coarse particles in the copper-containing particles can be suppressed, the generation of large voids caused by sintering of the coarse particles can be suppressed, and the generation of cracks in the copper sintered body can be prevented, Thus, the thermal conductivity of the copper sintered body and the bonding strength between the chip component and the substrate can be further improved. From this viewpoint, D ₉₀ /D ₅₀ is preferably 3.7 or less.

The value of D ₉₀ /D ₅₀ is not particularly limited as long as the relationship of 1.2≦D ₉₀ /D ₅₀ ≦3.7 is satisfied. The upper limit value of D ₉₀ /D ₅₀ is more preferably 3.0 or less, 2.9 or less, or 2.5 or less. The lower limit value of D ₉₀ /D ₅₀ is more preferably 1.3 or more, 1.5 or more, or 1.7 or more.

[BET specific surface area] The BET specific surface area of the copper-containing particles is preferably 1.0 m ² /g or more and 8.0 m ² /g or less. By setting the BET specific surface area of the copper-containing particles to be 1.0 m ² /g or more, the contact between the copper-containing particles can be increased, and the surface diffusion of the copper atoms can be increased to activate the sintering. In the case of damage to the wafer parts caused by high temperature sintering, high thermal conductivity is imparted to the obtained copper sintered body. On the other hand, if the BET specific surface area of the copper-containing particles is too large, the ratio of unevenness on the surface of the copper-containing particles increases, so that the degree of contact between the copper-containing particles over the entire surface decreases, which may prevent the copper-containing particles from being dense. sintered. From this point of view, by setting the BET specific surface area of the copper-containing particles to be 8.0 m ² /g or less, the copper-containing particles can be densely sintered, and the thermal conductivity of the obtained copper sintered body and the gap between the chip part and the substrate can be improved. the bonding strength.

The copper-containing particles are not particularly limited as long as they have a BET specific surface area of 1.0 m ² /g or more and 8.0 m ² /g or less. The BET specific surface area is more preferably 1.1 m ² /g or more, or 1.2 m ² /g or more. On the other hand, the BET specific surface area of the copper-containing particles is preferably 8.0 m ² /g or less, more preferably 7.6 m ² /g or less, or 5.7 m ² /g or less.

[Binder resin] The binder resin is a component that forms an organic vehicle in the copper oxide paste together with the following organic solvent. Add a binder resin to the copper oxide paste to give it a moderate viscosity and improve printability. The copper oxide paste of this embodiment is heated in an oxygen-free reducing gas atmosphere in the sintering step. However, the binder resin is oxidized due to the oxygen derived from Cu ₂ O and CuO in the copper-containing particles, and thus is removed in the form of gases such as CO and CO ₂ during sintering.

The binder resin is not particularly limited as long as it is decomposed by the heating step for sintering. Any resin may be used as long as it has a tendency to easily react with oxygen or carbon monoxide and disappear from the copper oxide paste. For example, cellulose resins, such as methyl cellulose, ethyl cellulose, and carboxymethyl cellulose, acrylic resins, such as polymethyl methacrylate, and butyraldehyde resins, such as polyvinyl butyral, etc. are mentioned.

The content of the binder resin is not particularly limited. The content of the binder resin is preferably 0.01 mass % or more, or 0.05 mass % or more with respect to the copper oxide paste. Moreover, it is preferable that content of a binder resin is 5.0 mass % or less, or 1.0 mass % or less.

In order to improve the viscosity or printability of the copper oxide paste, the content of the binder resin is preferably 0.01% by mass or more, and may be 0.05% by mass or more. On the other hand, in order to reduce the amount of resin remaining in the wiring after sintering and achieve a lower resistivity, the content of the binder resin is preferably 5 mass % or less.

[Organic solvents] The organic solvent is a component that disperses the copper-containing particles in the copper oxide paste and imparts fluidity and coatability to the copper oxide paste.

The organic solvent is not particularly limited as long as it has an appropriate boiling point, vapor pressure, and viscosity. For example, a hydrocarbon-based solvent, a chlorinated hydrocarbon-based solvent, a cyclic ether-based solvent, an amide-based solvent, a sulfite-based solvent, a ketone-based solvent, an alcohol-based compound, an ester-based solvent of a polyhydric alcohol, and an ether of a polyhydric alcohol may be mentioned. solvent, terpene-based solvent, etc. A mixture of two or more selected from these can also be used. It is preferable to use TEXANOL (boiling point = 244°C), butyl carbitol (231°C), butyl carbitol acetate (247°C), terpineol (219°C) according to the application of the copper oxide paste Such as a solvent with a boiling point of about 200 ℃.

The content of the organic solvent is not particularly limited. The organic solvent may be contained in 5 mass % or more, 7 mass % or more, or 10 mass % or more with respect to the copper oxide paste, depending on the application of the copper oxide paste. On the other hand, from a viewpoint of the upper limit of this content, an organic solvent may contain 40 mass % or less, 30 mass % or less, or 25 mass % or less with respect to a copper oxide paste.

[other ingredients] The copper oxide paste may contain arbitrary components in addition to the above-mentioned components of the copper-containing particles, the resin binder, and the organic solvent. The metal salt and the polyol are optional components contained in the conventional conductive paste, and may be used in combination. During sintering, the polyol will reduce the metal salt, and the reduced metal will precipitate in the space between the particles to fill the space, which can further improve the thermal conductivity of the obtained copper sintered body and the bonding strength between the chip part and the substrate.

As said metal salt, a copper salt can be used, for example, Specifically, 1 type or 2 or more types of copper acetate (II), copper (II) benzoate, bis(acetylacetone) copper (II), etc. can be used.

As said polyol, 1 type or 2 or more types of ethylene glycol, diethylene glycol, 1, 3- propanediol, 1, 2- propanediol, and tetraethylene glycol can be used, for example.

The copper oxide paste of the present embodiment may contain copper compounds such as Cu ₂ O and CuO contained in the copper-containing particles, or inorganic components other than metallic copper, or may not contain them. The inorganic components refer to inorganic components containing metals and/or semi-metals other than copper, including compounds such as complex oxides formed by compounding copper and metals and/or semi-metals other than copper. Examples of the inorganic component include gold, silver, or platinum as metals, boron as semimetals, and glass frits as metal oxides.

In order to maintain the properties of the copper sintered body obtained by the copper oxide paste of this embodiment, such as bonding strength, electrical conductivity, and low cost, the total amount of inorganic components containing metals and/or semimetals other than copper is relatively The inorganic component in the copper oxide paste may be 30 mass % or less, 20 mass % or less, 10 mass % or less, 6 mass % or less, or 1 mass % or less. Also, unavoidable impurities are allowed to be included.

[Viscosity of Copper Oxide Paste] The viscosity of the copper oxide paste when the shear rate is 1 sec ^-1 is not particularly limited. In order to uniformly coat the copper oxide paste on the substrate, the viscosity of the copper oxide paste is preferably 50 Pa·s or more and 2500 Pa·s or less. If the viscosity of the paste is too small, the thickness of the paste applied on the substrate becomes thin, and it is difficult to obtain a copper sintered body with a sufficient thickness. Therefore, the lower limit of the viscosity of the copper oxide paste is preferably 50 Pa·s or more, and may be 100 Pa·s or more, 150 Pa·s or more, 200 Pa·s or more, or 300 Pa·s depending on the embodiment. above.

On the other hand, if the viscosity of the paste is too large, there is a possibility that the paste applied on the substrate will be difficult to form a flat surface, resulting in uneven thickness of the copper sintered body. Therefore, the upper limit of the viscosity of the copper oxide paste is preferably 2500 Pa·s or less, and may be 1000 Pa·s or less, 800 Pa·s or less, or 600 Pa·s or less according to the embodiment. By uniformly coating the copper oxide paste on the substrate, the thermal conductivity of the obtained copper sintered body and the bonding strength between the chip part and the substrate can be improved.

[Analysis of Copper Oxide Paste] In the case of analyzing a generally available copper oxide paste, for example, the method described below can be used. In order to know the vehicle and the weight ratio of the binder resin and the solvent contained in the vehicle, the paste was heated at a rate of 10°C per minute using a thermogravimetric analysis (TGA) apparatus to measure the weight loss. The weight reduction of the first stage is the weight ratio of the solvent to the copper oxide paste, and the weight reduction of the second stage is the weight ratio of the binder resin to the copper oxide paste. In addition, the remaining amount is the weight ratio of the copper-containing particles. Furthermore, in order to specify the type of the solvent and the binder resin, it can be obtained by using a CHNS analyzer to obtain the composition ratios of carbon, hydrogen, nitrogen, and sulfur, and using thermogravimetric-mass analysis (TGA- MS) device to measure the molecular weight of molecules released from the paste in the first and second stages of heating. In addition, in order to obtain information on the copper-containing particles, the copper oxide paste is diluted with an organic solvent such as isopropanol, the copper-containing particles and the vehicle are separated using a centrifugal separator, and the obtained particles are analyzed by various analytical methods. The copper-containing particles can be analyzed. For example, in order to know the ratio of Cu ₂ O to CuO, X-ray diffraction can be used for analysis, which is obtained from the intensities of diffraction peaks derived from Cu ₂ O and CuO. The particle size distribution can be known using a laser diffraction method. The BET specific surface area can be known by measuring the adsorption amount of helium.

[Manufacturing method of paste] The copper oxide paste can be kneaded by mixing the above-mentioned binder resin and a solvent, adding copper particles, and using a mixing device such as a planetary mixer. Moreover, in order to improve the dispersibility of particle|grains, a three-roll mill may be used as needed.

The copper oxide paste of this embodiment is applied to, for example, the following electronic component manufacturing method, and a copper sintered body can be formed between the chip component and the substrate, and the chip component and the substrate can be firmly bonded. This copper sintered body has high thermal conductivity, and can conduct heat generated by the chip components to the substrate to dissipate heat.

Since the copper oxide paste of this embodiment has high heat dissipation, low resistivity, and high adhesion to the substrate, it can be used for bonding chip components such as power devices or laser diodes to the substrate. Furthermore, it can be used for any application as a substitute for a conductive copper-based paste.

2. Manufacturing method of electronic parts The manufacturing method of the electronic component of the present embodiment includes the following steps: coating or printing the above-mentioned copper oxide paste on the surface of the substrate; A copper sintered body was obtained on the substrate.

In addition, in this specification, the "electronic component" refers to a product including a form in which a chip component is arranged on a substrate, and a form of a so-called wiring board in which conductive wiring is arranged on the substrate.

[Paste coating or printing] The manufacturing method of the electronic component of this embodiment first coats or prints the above-mentioned copper oxide paste on the surface of the substrate.

The types and properties of the substrate are not particularly limited. For example, a metal substrate, an organic polymer substrate, a ceramic substrate, a carbon substrate, or the like can be used. Moreover, regarding the property of a board|substrate, the board|substrate which has heat dissipation can be used.

As the metal substrate, a substrate containing metal materials such as copper, copper-molybdenum alloy, and aluminum can be used. In addition, as the organic polymer substrate, a substrate containing a resin material such as polyimide, liquid crystal polymer, fluororesin, polyethylene terephthalate, polyethylene naphthalate, and epoxy glass can be used. The ceramic substrate can be a substrate containing ceramic materials such as inorganic oxides, inorganic carbides, inorganic nitrides, inorganic oxynitrides, etc., for example, SiO ₂ , SiOCH, SiN _x , Si ₃ N ₄ , SiON, AlN, Al ₂ O can be used _3. Inorganic materials such as silicon.

[Drying of substrates] In the manufacturing method of the electronic component of this embodiment, it is preferable to dry the board|substrate on which the copper oxide paste was coated or printed as needed at the temperature of 60 degreeC or more and 120 degrees C or less. This drying treatment is performed in order to evaporate at least a part of the organic solvent contained in the copper oxide paste. In the subsequent heat treatment step, the bumping of the organic solvent can be suppressed, and the damage of the copper sintered body can be prevented.

The drying method is not particularly limited as long as it is a method of keeping the substrate on which the copper oxide paste is applied or printed on the surface at a temperature of 60° C. or higher and 120° C. or lower. For example, the method of setting this board|substrate on the hotplate set to 60 degreeC or more and 120 degrees C or less or in a heating furnace is mentioned.

The heating time of the drying step is not particularly limited. The lower limit of the heating time may be 2 minutes or longer, or 3 minutes or longer. On the other hand, the upper limit of the heating time may be 1 hour or less, or 0.5 hour or less. Depending on the type of organic solvent used, for example, it can be heated at 60° C. for about 30 minutes and at 120° C. for about 5 minutes.

[Pressure of the substrate] In order to densely fill the copper-containing particles in the copper oxide paste and improve the thermal conductivity of the obtained copper sintered body and the bonding strength between the chip part and the substrate, it is preferable to arrange the chip part on the surface of the dried paste Afterwards, a specific pressure is applied to the substrate. As the direction of pressing, the direction of the laminated chip parts can be selected, that is, the direction perpendicular to the surface of the substrate.

The applied pressure is preferably 2 MPa or more and 30 MPa or more. If the pressure is less than 2 MPa, the copper-containing particles cannot be sufficiently filled, and the thermal conductivity and bonding strength of the obtained copper sintered body cannot be sufficiently improved. On the other hand, if the pressure is too large, the wafer parts may be damaged, so it is preferably 30 MPa or less.

The copper oxide paste of this embodiment can be used in various applications as a substitute for the conventional conductive paste. For example, it can be used to bond chip components such as power devices or laser diodes to substrates, or to form printed wiring. When applied to the bonding of chip components and substrates, it is preferable to dry the substrate coated or printed with the copper oxide paste, then pressurize the substrate, and then perform a specific heat treatment. When applied to the case of forming printed wiring, the substrate may not be pressurized.

As the chip parts, various chip parts such as resistors, diodes, inductors, and capacitors can be used. For example, various semiconductor wafers such as Si wafers and SiC wafers can be used. Can be chip parts for power devices or laser diodes, etc.

The size and shape of the chip components are not particularly limited. For example, a square or substantially square with a length of 2 mm to 20 mm on one side, or a rectangle or a substantially rectangular shape with a length of 2 mm to 20 mm on a short side can be used.

[Heat treatment of substrate] In the manufacturing method of the electronic component of this embodiment, it is preferable to perform a heat treatment at a temperature of 200° C. or more and 600° C. or less in a reducing gas atmosphere, and obtain a copper sintered body on the substrate. By this heat treatment, the organic solvent contained in the copper oxide paste is volatilized, and the binder resin reacts with the oxygen of the copper oxide to be decomposed and removed. As a result, the copper oxide paste can be sufficiently sintered, thereby improving the thermal conductivity and the bonding strength of the obtained copper sintered body.

The reducing gas atmosphere is not particularly limited. A reducing gas atmosphere containing one or more gases selected from the group consisting of hydrogen, formic acid, and alcohols is preferred.

For safety reasons, it is convenient to use the reducing gas in a state of being mixed with an inert gas. As the inert gas, nitrogen gas, argon gas, or the like can be used. The concentration of the reducing gas contained in the mixed gas is not particularly limited. In order to sufficiently reduce Cu ₂ O and CuO contained in the copper oxide paste, 0.5 vol % or more is preferable, 1 vol % or more, or 2 vol % or more.

The heating temperature of the heat treatment is preferably 200°C or higher and 600°C or lower. If the heating temperature is less than 200°C, the volatilization of the organic solvent contained in the paste and the decomposition and removal of the binder resin cannot be sufficiently performed. On the other hand, if the heating temperature is too high, the properties of the wafer parts may be degraded, so the heating temperature is preferably 600° C. or lower.

The heating time of this heat treatment is not particularly limited. The lower limit value of the heating time is preferably 3 minutes or more, or 5 minutes or more. On the other hand, the upper limit of the heating time is preferably 1 hour or less, or 0.5 hour or less. For example, at 220°C, a heating condition of about 1 hour can be selected, and if it is 600°C, a heating condition of about 3 minutes can be selected.

By the above manufacturing method, a copper sintered body with very low electrical resistivity and high thermal conductivity can be obtained. For example, the obtained copper sintered body has the following characteristics: the electrical resistivity is 2.5 μΩcm or more and 12 μΩcm or less, and the thermal conductivity is 55 WK ^-1 m ^-1 or more and 250 WK ^-1 m ^-1 or less. [Example]

The following examples are given to further illustrate the present invention. The present invention is not limited to these examples.

<Example 1> Influence of particle size distribution [Preparation of Cu ₂ O particles] Cu ₂ O particles can be obtained by reacting a copper salt aqueous solution containing copper ions with an alkaline solution to precipitate copper hydroxide particles, Hydrazine hydrate as a reducing agent and an aqueous ammonia solution as a pH adjuster were added.

Moreover, other kinds of Cu ₂ O particles can be obtained by oxidizing electrolytic copper powder at a temperature of 180° C. in an oxidizing gas atmosphere, and pulverizing with a jet mill. By changing the oxygen concentration in the oxidizing gas, Cu ₂ O particles of different shapes such as cube or octahedron can be obtained.

[Production of CuO Particles] CuO particles can be obtained by stirring the Cu ₂ O particles obtained by the above method in hot water heated to 70° C. for 30 minutes. Moreover, other kinds of CuO particles can be obtained by oxidizing electrolytic copper powder at a temperature of 300° C. in an oxidizing gas atmosphere, and pulverizing with a jet mill. By changing the oxygen concentration in the oxidizing gas, CuO particles such as thin plates or fibers are obtained.

[Adjustment of particle size distribution] The particle size distribution of Cu ₂ O particles and CuO particles is mainly classified into a cyclone type centrifugal classification device, an air classification type centrifugal classification device, etc., with D ₅₀ in the range of 0.08 μm to 10 μm The 8 grades of particles are appropriately mixed and adjusted.

The particle size distribution of the copper-containing particles was measured by a laser diffraction scattering particle size distribution analysis method. In addition, the BET specific surface area of the copper-containing particle was measured by the gas adsorption method with respect to the copper-containing particle which mixed _CuO particle and Cu2O particle in a specific ratio.

[Preparation of copper oxide paste] With respect to the total mass of the copper oxide paste, about 70 mass % of Cu ₂ O particles, about 5 mass % of CuO particles, 0.1 mass % of ethyl cellulose as a binder resin, After 24.9 mass % of terpineol as an organic solvent, these were kneaded with a planetary mixer to obtain an oxide paste for evaluation tests. In this Example 1, as shown in Table 1, the copper oxide pastes of Examples 1-1 to 1-6 and the copper oxide pastes of Comparative Examples 1-1 to 1-4 were prepared.

[Production of electronic parts sample] Next, the preparation method of the sample used for the evaluation test is demonstrated. The obtained copper oxide paste was applied to a copper substrate by a screen printing method, and a drying treatment was performed for 10 minutes on a hot plate heated to 100° C. in the atmosphere. Next, a square-shaped SiC wafer with a length of 10 mm on one side was placed on the dried copper oxide paste, and a laminate in which the substrate, the copper oxide paste, and the SiC wafer were stacked in this order was produced. Furthermore, a Ni thin film with a thickness of about 0.5 μm before lamination was formed on the surface of the SiC wafer in contact with the copper oxide paste.

Then, after applying a pressure of 5 MPa to both sides of the produced laminate, in a heating furnace, in an atmosphere in which 3 vol % of hydrogen was mixed with nitrogen, heat treatment was performed at 350° C. for 40 minutes to produce copper Sample of sintered body. The obtained samples were subjected to the following evaluation tests of bonding strength, resistivity, and the like.

[Evaluation of Bonding Strength] Using a wafer shearing device, a shear stress was applied to the end portion of the SiC wafer, and the die shear strength was measured. The shear test speed was 500 μms ^-1 , and the shear height from the substrate was 100 μm. The measured wafer shear strength can be divided into three grades A to C as shown below. Based on this standard, the bonding strength of the copper sintered body was evaluated. When this criterion is "A" or "B", it is judged that the copper sintered body has high bonding strength and is a copper oxide paste that can provide a good bonding material.

A: Above 20 MPa B: 10 MPa or more and less than 20 MPa C: less than 10 MPa

[Evaluation of Resistivity] In the evaluation test of the resistivity, a glass wafer composed of a glass plate having the same size as the SiC wafer was used instead of the SiC wafer, and a sample for the evaluation test was produced. The reason for this is as follows. In the case of the sample of the SiC wafer on which the Ni thin film was formed, since the SiC wafer was in a state of being bonded to the substrate through the copper sintered body, it was difficult to expose the copper sintered body to measure the electrical properties of the copper sintered body. On the other hand, since the glass wafer is not bonded to the copper sintered body, it can be easily peeled off after sintering. Therefore, the copper sintered body can be exposed and its electrical properties can be measured.

In the same procedure as in the case of the sample using the SiC wafer, a sample in which the substrate, the copper oxide paste, and the glass wafer were laminated was produced, and thereafter, pressurization and heat treatment were performed under the same conditions to obtain a laminated body having a copper sintered body. . After the heat treatment, the glass wafer was peeled off to expose the surface of the copper sintered body. Then, four electrodes were arranged on the surface, and the resistivity of the copper sintered body was measured by the DC four-probe method. The measured resistivity can be divided into three grades A to C as shown below. The numerical values in parentheses remarked on the above-mentioned benchmarks A to C are values obtained by converting electrical resistivity into thermal conductivity. When the criterion is "A" or "B", it is determined that the copper sintered body has low electrical resistivity and high thermal conductivity, and is a copper oxide paste that can provide a good bonding material.

A: Less than 5.0 μΩcm (more than 134 Wm ^-1 K ^-1 ) B: More than 5.0 μΩcm and less than 9.0 μΩcm (more than 74 Wm ^-1 K ^-1 and less than 134 Wm ^-1 K ^-1 ) C: More than 9.0 μΩcm (below 74 Wm ^-1 K ^-1 )

The electrical resistivity (ρ) can be converted into the thermal conductivity (κ) using the known Wiedemann-Franz equation represented by the following equation (3). κ=LT/ρ ・・・Equation (3)

L in the above formula (3) is a Lorenz constant. In the case of copper, L=2.23×10 ^-8 WΩK ^-2 . T is temperature (K), the unit of ρ is Ωcm, and the unit of κ is Wm ^-1 K ^-1 . The numerical value of the thermal conductivity in the above-mentioned reference of A to C represents the numerical value obtained by converting the electrical resistivity in the case of T=300 K according to the formula (3). In this way, the electrical resistivity (ρ) can be said to be an index that is inversely proportional to the thermal conductivity (κ). Therefore, in this Example, the thermal conductivity can also be evaluated using the measurement result of the resistivity of the copper sintered body.

Table 1 shows the 50% cumulative particle diameter (D ₅₀ ), 50% cumulative particle diameter/10% cumulative particle diameter (D ₅₀ /D ₁₀ ), 90% cumulative particle diameter/50% cumulative particle diameter of the copper-containing particles (D ₉₀ /D ₅₀ ), measurement results of BET specific surface area (m ² /g), and evaluation results of bonding strength and resistivity.

[Table 1] Comparative Example 1-1 Comparative Example 1-2 Example 1-1 Example 1-2 Examples 1-3 Examples 1-4 Examples 1-5 Examples 1-6 Comparative Example 1-3 Comparative Example 1-4 D ₅₀ (μm) 0.08 0.14 0.20 0.23 0.32 0.92 2.82 4.88 6.20 9.18 D ₅₀ /D ₁₀ 2.1 2.6 1.3 2.7 3.2 3.1 4.3 4.9 4.7 5.4 D ₉₀ /D ₅₀ 1.1 1.1 3.1 1.2 1.8 2.7 3.1 3.7 4.3 4.2 BET specific surface area (m ² /g) 7.5 7.2 6.7 6.2 5.9 2.0 1.8 1.8 1.3 0.7 joint strength C C B B A A B B C C Resistivity A A A A A A A B B C

As shown in Table 1, regarding the copper oxide pastes of Examples 1-1 to 1-6, the 50% cumulative particle diameter (D ₅₀ ) and 50% cumulative particle diameter/10% of the copper-containing particles contained therein Cumulative particle diameter (D ₅₀ /D ₁₀ ), 90% cumulative particle diameter/50% cumulative particle diameter (D ₉₀ /D ₅₀ ), and BET specific surface area (m ² /g) are all included within the scope of the present invention. In addition, the copper sintered body produced from these copper oxide pastes exhibits the characteristics that the bonding strength and the resistivity satisfy the A or B criteria. Therefore, it can be confirmed that the copper oxide paste included in the scope of the present invention can provide a good bonding material.

On the other hand, with respect to Comparative Example 1-1, Comparative Example 1-2, Comparative Example 1-3, and Comparative Example 1-4, the particle size distributions D ₅₀ , D ₅₀ /D ₁₀ , and D ₉₀ /D of the copper-containing particles ₅₀ is outside the scope of the present invention. Therefore, the bonding strength of the copper sintered body produced from these copper oxide pastes is at the low level of the C standard, and it is not suitable as a bonding material. Moreover, about the comparative example 1-4, the electrical resistivity and thermal conductivity are also shown as a C standard.

<Example 2> Influence of BET specific surface area For the particles obtained by precipitation from the copper salt aqueous solution, the degree of aggregation of the primary precipitated particles can be adjusted by changing the type and concentration of the particle dispersant contained in the solution. Therefore, secondary particles formed by agglomeration of primary particles can obtain particles with different surface irregularities, and can provide particles with different BET specific surface areas. In addition, the BET specific surface area can be adjusted by adjusting the degree of aggregation of the electric field copper particles in the same manner as described above to prepare secondary particles with different surface irregularities, and then performing an oxidation treatment. On the other hand, since the particle shape of the particle obtained by high-pressure water atomization is close to spherical, the overall BET specific surface area can be adjusted by adding needle-shaped or plate-shaped CuO particles and mixing.

In the same procedure as in Example 1, with respect to the total mass of the copper oxide paste, about 70 mass % of Cu ₂ O particles, about 5 mass % of CuO particles, 0.1 mass % of resin, and 24.9 mass % of solvent were weighed. Type mixer for kneading to make copper oxide paste. In this Example 2, the copper oxide pastes of Examples 2-1 to 2-8 and the copper oxide pastes of Comparative Examples 2-1 to 2-5 were prepared. Then, according to the same procedure as Example 1, a sample for evaluation test was produced, and the wafer shear strength and resistivity of the sample were measured.

Table 2 shows the particle size distribution of the copper-containing particles, the measurement results of BET specific surface area (m ² /g), and the evaluation results of bonding strength and resistivity.

[Table 2] Comparative Example 2-1 Comparative Example 2-2 Comparative Example 2-3 Example 2-1 Example 2-2 Example 2-3 Example 2-4 Example 2-5 Examples 2-6 Example 2-7 Examples 2-8 Comparative Example 2-4 Comparative Example 2-5 D ₅₀ (μm) 4.6 2.1 1.2 1.1 1.2 0.71 0.65 0.52 0.44 0.28 0.23 0.23 0.13 D ₅₀ /D ₁₀ 8.2 5.1 4.9 4.9 3.9 3.7 3.1 3.1 2.3 2.1 1.5 1.4 1.5 D ₉₀ /D ₅₀ 1.8 1.8 2.1 2.7 2.8 3.1 3.7 3.7 3.2 3.5 3.7 4.1 5.3 BET specific surface area (m ² /g) 0.4 0.6 0.7 1.1 1.2 2.1 2.2 3.1 3.6 5.7 7.6 8.4 8.7 joint strength C C C B A A A A A A B C C Resistivity B B B A A A A A A A B B B

As shown in Table 2, regarding the copper oxide pastes of Examples 2-1 to 2-8, the 50% cumulative particle diameter (D ₅₀ ) and 50% cumulative particle diameter/10% of the copper-containing particles contained therein Cumulative particle diameter (D ₅₀ /D ₁₀ ), 90% cumulative particle diameter/50% cumulative particle diameter (D ₉₀ /D ₅₀ ), and BET specific surface area (m ² /g) are all included within the scope of the present invention. In addition, the copper sintered body produced from these copper oxide pastes exhibits the characteristics that the bonding strength and the resistivity satisfy the A or B criteria. Therefore, it can be confirmed that the copper oxide paste included in the scope of the present invention can provide a good bonding material.

In contrast, in Comparative Examples 2-1 to 2-5, the BET specific surface areas of the copper-containing particles were all outside the scope of the present invention. In addition, with respect to Comparative Example 2-1, Comparative Example 2-2, Comparative Example 2-4, and Comparative Example 2-5, “D _{50 ”, “D 50 /D 10 ”, “D 50} ”, “D ₅₀ /D ₁₀ ”, Any one or more of each index of "D ₉₀ /D ₅₀ " is outside the scope of the present invention. Therefore, the bonding strength of the copper sintered body produced from these copper oxide pastes is at the low level of the C standard, and it is not suitable as a bonding material.

<Example 3> Influence of _CuO /Cu2O molar ratio Except that the mixing ratio (molar ratio) of Cu2O particle and _CuO particle was changed, the copper oxide paste was produced in the same procedure as Example 1. In this Example 3, the copper oxide pastes of Examples 3-1 to 3-3 and the copper oxide pastes of Comparative Examples 3-1 to 3-3 were prepared. Then, according to the same procedure as Example 1, a sample for evaluation test was produced, and the wafer shear strength and resistivity of the sample were measured.

Table 3 shows the particle size distribution of the copper-containing particles, the measurement results of BET specific surface area (m ² /g), and the evaluation results of bonding strength and resistivity.

[table 3] Comparative Example 3-1 Example 3-1 Example 3-2 Example 3-3 Comparative Example 3-2 Comparative Example 3-3 D ₅₀ (μm) 0.58 0.62 0.57 0.64 0.61 0.72 D ₅₀ /D ₁₀ 4.9 4.5 3.1 3.3 2.7 1.8 D ₉₀ /D ₅₀ 2.8 3.1 2.9 1.9 3.2 2.3 BET specific surface area (m ² /g) 4.3 4.2 5.1 4.7 5.5 5.9 Cu ₂ O/CuO mol ratio (without CuO) 30 3 1 0.43 0.1 joint strength B A A B C C Resistivity C A A A B C

As shown in Table 3, regarding the copper oxide pastes of Examples 3-1 to 3-3, the 50% cumulative particle diameter (D ₅₀ ) and 50% cumulative particle diameter/10% of the copper-containing particles contained therein Cumulative particle diameter (D ₅₀ /D ₁₀ ), 90% cumulative particle diameter/50% cumulative particle diameter (D ₉₀ /D ₅₀ ), and specific surface area (m ² /g) are all included within the scope of the present invention. Moreover, the mixing ratio (molar ratio) of Cu2O particle|grains and _CuO particle|grains of copper-containing particle|grains of these copper oxide pastes is 1.0 or more. The copper sintered body produced from this copper oxide paste exhibits the characteristics that the bonding strength and the resistivity satisfy the A or B criteria, and are suitable for use as a bonding material.

On the other hand, in Comparative Examples 3-1 to 3-3, the mixing ratio (molar ratio) of Cu ₂ O particles and CuO particles containing copper particles was less than 1.0. The bonding strength of the copper sintered body produced from these copper oxide pastes is at the low level of the C standard, and is not suitable as a bonding material.

<Example 4> Influence of ratio and viscosity of copper-containing particles in copper oxide paste The copper-containing particles classified in Example 1 were mixed to prepare D ₅₀ =0.32 μm, D ₅₀ /D ₁₀ =3.2 , D ₉₀ /D ₅₀ =2.4 particle size distribution and copper-containing particles with a BET specific surface area of 3.5 m ² /g.

Using the copper-containing particles, the ratio of the copper-containing particles to the mediator (resin and organic solvent) was changed to copper-containing particles by mass ratio: mediator=x: 1-x, except that it was the same as in Example 1. The order of making copper oxide paste. Hereinafter, the above-mentioned "x" is referred to as "content of copper-containing particles". The used vehicle was prepared at a ratio (0.1:24.9) corresponding to "resin 0.1%, solvent 24.9%" in Example 1. In this Example 4, the copper oxide pastes of Examples 4-1 to 4-5, and the copper oxide pastes of Comparative Example 4-1 and Comparative Example 4-2 were produced. Then, according to the same procedure as Example 1, a sample for evaluation test was produced, and the wafer shear strength and resistivity of the sample were measured.

Table 4 shows the evaluation results of the content (mass %) of the copper-containing particles, the bonding strength and the resistivity.

[Table 4] Comparative Example 4-1 Example 4-1 Example 4-2 Example 4-3 Example 4-4 Example 4-5 Comparative Example 4-2 Content of copper-containing particles (mass %) 50 60 70 80 90 92 95 joint strength C B A A B B C Resistivity C A A A A B B

The particle size distribution and BET specific surface area of the copper-containing particles of the copper oxide pastes of Examples 4-1 to 4-5 are included in the scope of the present invention. Moreover, as shown in Table 4, with respect to the total amount of copper oxide paste, the content of the copper-containing particle was all included in the range of 60-92 mass %. The copper sintered body produced from this copper oxide paste exhibits the characteristics that the bonding strength and the resistivity satisfy the A or B criteria, and are suitable for use as a bonding material.

On the other hand, in Comparative Example 4-1 and Comparative Example 4-2, the content of the copper-containing particles was outside the range of 60 to 92 mass % with respect to the total amount of the paste. Therefore, the bonding strength and resistivity of the copper sintered body produced from these copper oxide pastes are at the low level of the C standard, and are not suitable as a bonding material.

Claims (10)

A copper oxide paste, which contains copper-containing particles, a binder resin and an organic solvent, the copper-containing particles contain Cu ₂ O and CuO, among the copper elements contained in the copper-containing particles, the copper elements constituting Cu ₂ O and The total amount of copper elements constituting CuO is 90% or more, the 50% cumulative particle size (D ₅₀ ) of the above-mentioned copper-containing particles is 0.20 μm or more and 5.0 μm or less, the above-mentioned 50% cumulative particle size (D ₅₀ ) and 10% cumulative particle size The diameter (D ₁₀ ) satisfies the formula (1) shown below, the 50% cumulative particle diameter (D ₅₀ ) and the 90% cumulative particle diameter (D ₉₀ ) satisfy the formula (2) shown below, and the copper-containing particles The BET specific surface area is 1.0 m ² /g or more and 8.0 m ² /g or less: 1.3≦D ₅₀ /D ₁₀ ≦4.9 ・・・Formula (1) 1.2≦D ₉₀ /D ₅₀ ≦3.7 ・・・Formula (2) . The copper oxide paste according to claim 1, wherein the amount of Cu ₂ O contained in the copper-containing particles to the amount of CuO is 1.0 or more in molar ratio. The copper oxide paste according to claim 1 or 2, wherein the copper-containing particles are 60 mass % or more and 92 mass % or less with respect to the total amount of the copper oxide paste. A method of manufacturing an electronic component, comprising the steps of: disposing the copper oxide paste according to any one of claims 1 to 3 on the surface of a substrate by coating or printing; and The said board|substrate is heat-processed at the temperature of 200 degreeC or more and 600 degrees C or less in a reducing gas atmosphere, and a copper sintered body is obtained on the said board|substrate. The method for producing an electronic component according to claim 4, wherein the substrate is a metal substrate, an organic polymer substrate, a ceramic substrate or a carbon substrate. The method for producing an electronic component according to claim 4, wherein the reducing gas atmosphere contains at least one gas selected from the group consisting of hydrogen, formic acid, and alcohol. The method for producing an electronic component according to claim 5, wherein the reducing gas atmosphere contains at least one gas selected from the group consisting of hydrogen, formic acid, and alcohol. The method for producing an electronic component according to any one of claims 4 to 7, wherein the resistivity of the copper sintered body is 2.5 μΩcm or more and 12 μΩcm or less. The method for manufacturing an electronic component according to any one of claims 4 to 7, further comprising the steps of: before the above heat treatment, A chip component is placed on the surface of the dried copper oxide paste, and a pressure of 2 MPa to 30 MPa is applied from the surface of the chip component to the direction of the substrate. The method for manufacturing an electronic component of claim 8, further comprising the steps of: before the above-mentioned heat treatment, A chip component is placed on the surface of the dried copper oxide paste, and a pressure of 2 MPa to 30 MPa is applied from the surface of the chip component to the direction of the substrate.