TWI789698B - Copper oxide paste and method for producing electronic parts - Google Patents

Abstract

The present invention provides a copper-based paste, which can more firmly bond a chip component and a substrate, and obtain a copper-based bonding material with high thermal conductivity. The copper oxide paste of the present invention 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 that constitute Cu ₂ O and the copper elements that constitute CuO The total amount of copper element is more than 90%, the 50% cumulative particle size (D ₅₀ ) of the copper-containing particles is 0.20 μm or more and 5.0 μm or less, the 50% cumulative particle size (D ₅₀ ) and the 10% cumulative particle size (D ₁₀ ) satisfying 1.3≦D ₅₀ /D ₁₀ ≦4.9, 50% cumulative particle size (D ₅₀ ) and 90% cumulative particle size (D ₉₀ ) satisfying 1.2≦D ₉₀ /D ₅₀ ≦3.7, and BET specific surface area of copper-containing particles It is not less than 1.0 m ² /g and not more than 8.0 m ² /g.

Description

Copper oxide paste and method for producing electronic parts

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

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

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

[Patent Document 1] Japanese Patent No. 6529632

[Problem to be solved by the invention]

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

Moreover, copper (Cu) is mentioned as an inexpensive metal material which can be used for the bonding material of a wafer component and a board|substrate, for example. However, in conventional bonding using a copper-based paste containing copper powder, the adhesion between the chip component and the substrate is not sufficient. 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 of the present invention is to provide a copper-based paste that can more firmly bond a chip component and a substrate and obtain a copper-based bonding material with high thermal conductivity. [Technical means to solve the problem]

Regarding the copper oxide paste containing copper-containing particles, binder resin, and organic solvent, the present inventors focused on the content of copper elements constituting _Cu2O and CuO contained in the copper-containing particles, and the 10% cumulative particle size (D ₁₀ ), 50% cumulative particle size (D ₅₀ ) and 90% cumulative particle size (D ₉₀ ) related particle size distribution, BET specific surface area. As a result, it has been found that a copper oxide paste specifying these matters can firmly bond a chip part and a substrate among electronic parts, and provide a copper-based bonding material having high thermal conductivity, thereby completing the present invention. Specifically, the present invention includes aspects of the following (1) to (8). Furthermore, in this specification, the expression of "~" includes the numerical values at both ends. That is, "X to Y" has the same meaning as "X to Y and below".

(1) The first aspect is a copper oxide paste containing copper-containing particles, a binder resin, and an organic solvent. The above-mentioned copper-containing particles contain _Cu2O and CuO. Among the copper elements contained in the above-mentioned 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 to 5.0 μm, and the above-mentioned 50% cumulative particle size ( D ₅₀ ) and 10% cumulative particle size (D ₁₀ ) satisfy the formula (1) shown below, and the above-mentioned 50% cumulative particle size (D ₅₀ ) and 90% cumulative particle size (D ₉₀ ) satisfy the following formula ( 2), and the BET specific surface area of the above-mentioned copper-containing particles is not less than 1.0 m ² /g and not more than 8.0 m ² /g. 1.3≦D ₅₀ /D ₁₀ ≦4.9 ・・・Formula (1) 1.2≦D ₉₀ /D ₅₀ ≦3.7 ・・・Formula (2)

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

(3) The third aspect is a copper oxide paste, which is in the above (1) or (2), the above-mentioned copper-containing particles are 60% to 92% of the paste, and the shear rate is 1 sec ^-1 When the viscosity is above 50 Pa·s and below 2500 Pa·s.

(4) The fourth aspect is a method of manufacturing electronic parts, which includes the following steps: disposing the copper oxide paste as described in any one of the above (1) to (3) by coating or printing the surface of the substrate; and performing heat treatment at a temperature of 200° C. to 600° C. in a reducing gas atmosphere to obtain a copper sintered body on the above substrate.

(5) A fifth aspect is a method of manufacturing 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) The sixth aspect is a method of manufacturing an electronic component in the above (4) or (5), wherein the reducing gas atmosphere contains one or more selected from the group consisting of hydrogen, formic acid, and alcohol gas.

(7) The seventh aspect is a method of manufacturing an electronic component, which is in any one of the above (4) to (6), wherein the resistivity of the copper sintered body is not less than 2.5 μΩcm and not more than 12 μΩcm.

(8) The eighth aspect is a method of manufacturing electronic parts, which is in any one of the above (4) to (7), and further includes the following steps: before the above heat treatment, the above copper oxide paste is dried Chip parts are arranged on the surface of the above-mentioned chip parts, and a pressure of 2 MPa to 30 MPa 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 part and a substrate among electronic parts, 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 appropriately changed and implemented within the scope of the purpose 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. Furthermore, 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 the copper elements constituting Cu ₂ O and the copper elements constituting CuO is 90% or more. In addition, the 50% cumulative particle size (D ₅₀ ) of the copper-containing particles is 0.20 μm to 5.0 μm, and the 50% cumulative particle size (D ₅₀ ) and 10% cumulative particle size (D ₁₀ ) satisfy the following formula (1 ), the 50% cumulative particle size (D ₅₀ ) and the 90% cumulative particle size (D ₉₀ ) satisfy the following formula (2). Furthermore, the BET specific surface area of the copper-containing particles is not less than 1.0 m ² /g and not more than 8.0 m ² /g. 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 _Cu2O 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 form copper sintered body. For example, when a wafer component is bonded to a substrate using this copper oxide paste, the wafer component and the substrate can be firmly bonded.

Generally, to form a copper sintered body, a copper-based paste containing metallic copper particles as a main component is used. In the case of this type of copper-based paste, sintering is often performed in an inert gas atmosphere in order to prevent oxidation of the metal copper particles. 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 _Cu2O and CuO, it is possible to reduce copper oxide while heating in a reducing atmosphere. Metallic copper is formed, while the sintering reaction of copper-based particles is carried out, thereby obtaining a copper sintered body.

The copper oxide paste of the present invention can be easily sintered compared to copper-based pastes mainly composed of metallic copper particles. The reason for this is considered to be as follows. In general, 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 expressed by the formula "D=C _v D _v + C _i D _i ", which is the carrier of diffusion, that is, 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 inter-lattice atoms (D _i ), respectively, and then added together. Generally, the value of C _v D _v is much larger than the value of C _i D _i , so the above formula of diffusion coefficient D can be approximately expressed as D=C _v D _v .

When the copper-based paste containing metallic copper particles is sintered in a nitrogen atmosphere, the atomic vacancy concentration _Cv corresponds to the concentration in an 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 concentration of atomic vacancies _Cv is higher than that in the equilibrium state, which is higher than that of atomic vacancies in the case of metallic copper particles. Concentrations are two orders of magnitude higher. Therefore, the sintering of the copper-based paste containing copper oxide proceeds at a high speed even at a low temperature, compared with the copper-based paste containing metallic copper particles, and sintering can be performed very efficiently.

Therefore, when the copper oxide paste of the present invention is used as, for example, a bonding material for bonding a chip component to a substrate, it is obtained by sintering a copper oxide paste containing _Cu2O and CuO in a reducing atmosphere. Copper sintered bodies bond wafer parts to substrates very firmly. In this specification, the form used as the bonding material of a chip component and a board|substrate is taken as an example, and it demonstrates below. This description is an example of the use form of this invention, and the copper oxide paste of this invention is not limited to this use form.

Generally, the Cu ₂ O particles have a shape such as a cube or an octahedron, and the CuO particles have a fiber shape or a thin plate shape. Since the copper oxide paste of the present invention contains copper-containing particles including both Cu ₂ O and CuO, during the sintering process in a reducing atmosphere, gaps between cube-shaped or octahedral Cu ₂ O particles It is filled with fibrous or thin plate CuO particles for reduction and sintering. 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 component 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 bond the chip part and the substrate, and are responsible for the heat conduction between the two. In order to ensure sufficient thermal conductivity and joint strength in the copper sintered body, among the copper elements contained in the copper-containing particles, the total amount of the copper elements constituting _Cu2O 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 other than 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, Sb), even if contained in copper-containing particles, do not become oxides due to heating in a reducing gas atmosphere, and the content is small. As long as the total amount of the copper element constituting Cu ₂ O and the copper element constituting CuO is 90% or more, sufficient thermal conductivity and joint strength can be ensured, so the inclusion of elements other than copper is allowed.

[Molar ratio of Cu ₂ O to CuO] If the amount of Cu ₂ O contained in the copper-containing particles is determined by 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-shaped CuO particles becomes too large, so that the density of the obtained copper sintered body becomes small, and as a result, bonding strength and thermal conductivity decrease.

On the other hand, regarding 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 that promote sintering of the Cu2O particles arranged in the gaps between the _Cu2O particles becomes too small, so that the density of the obtained copper sintered body becomes small, and as a result, the joint strength and Reduced thermal conductivity.

Cu ₂ O and CuO contained in the copper-containing particles may exist as independent particles, respectively, or may exist in the form of particles in which both Cu ₂ O and CuO exist in one particle. In addition, it may be two or more kinds selected from the group consisting of particles containing _Cu2O and not containing CuO _, particles containing CuO and not containing _Cu2O , and particles containing both Cu2O and CuO. mixed presence.

[Content of Copper-Containing Particles] The content of copper-containing particles is not particularly limited. Since the content of copper-containing particles in the copper oxide paste affects the concentration of the vehicle in the paste, it is a factor closely related to the viscosity of the paste. The content of copper-containing particles in the copper oxide paste is 60% by mass to 92% by mass relative to the total amount of the copper oxide paste, so that the viscosity of the copper oxide paste at a shear rate of 1 sec ^-1 can be increased Above 50 Pa・s and below 2500 Pa・s. If the content of the copper-containing particles is less than 60% by 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 in 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 over 2500 Pa·s, and it is difficult to obtain a flat surface of the paste coated on 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, and the contact area with the substrate is reduced, resulting in a decrease in bonding strength and thermal conductivity.

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

[Particle Size of Copper-Containing Particles] The 50% cumulative particle size (D ₅₀ ) of the copper-containing particles is preferably from 0.20 μm to 5.0 μm. If 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 copper-containing particles below 5.0 μm, sintering at low temperature can be performed, and as a result, the obtained The sintered body endows higher thermal conductivity. If the 50% cumulative grain size (D ₅₀ ) exceeds 5.0 μm, the structure after sintering will produce more voids, which will reduce the thermal conductivity of the obtained copper sintered body. In addition, cracks will occur in the copper sintered body, resulting in joint Reduced strength. Therefore, the 50% cumulative particle size (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 will increase during sintering, and a large shear stress will be generated at the interface between the chip part and the substrate, which will cause the chip part to peel off 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 generated in the copper sintered body formed of the copper-containing particles to prevent a decrease in joint 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 copper-containing particles, and the 90% cumulative particle diameter (D ₉₀ ) and 10% cumulative particle diameter (D ₁₀ ) described below refer to 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 formula (1) represents the ratio of the 50% cumulative particle size (D ₅₀ ) to the 10% cumulative particle size (D ₁₀ ). 1.3≦D ₅₀ /D ₁₀ ≦4.9・・・Formula (1)

When the copper-containing particles in the copper oxide paste are sintered, the gaps between the large particles are filled with small particles, thereby obtaining a copper sintered body densely filled with copper particles, thereby improving the thermal conductivity of the copper sintered body and bonding strength. Therefore, it is effective to contain large particles and small particles to an appropriate degree. From this point of view, in order to broaden the particle size distribution of the copper-containing particles and 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 there are too many large particles in the copper-containing particles and the content of the coarse particles is increased, large voids may be generated due to sintering of the coarse particles, thereby causing cracks 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 being 4.9 or less can suppress the inclusion of coarse particles in the copper-containing particles, thereby suppressing the generation of larger voids and preventing the generation of cracks in the copper sintered body, so the copper sintered body can be improved. In terms of thermal conductivity and bonding strength between the chip component and the substrate, D ₅₀ /D ₁₀ is preferably 4.9 or less.

The value of D ₅₀ /D ₁₀ is not particularly limited as long as it satisfies the relationship of 1.3≦D ₅₀ /D ₁₀ ≦4.9. The upper limit of D ₅₀ /D ₁₀ is more preferably 4.5 or less, 4.0 or less, or 3.5 or less. The lower limit 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 formula (2) represents the ratio of the 90% cumulative particle size (D ₉₀ ) to the 50% cumulative particle size (D ₅₀ ). 1.2≦D ₉₀ /D ₅₀ ≦3.7・・・Formula (2)

By setting D ₉₀ /D ₅₀ to be 1.2 or more, the particle size distribution of the copper-containing particles can be broadened and both large particles and small particles can be contained to an appropriate degree. Therefore, the gaps between the large particles are filled with the small particles, whereby 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 point of view, 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 larger voids caused by sintering of coarse particles can be suppressed, and the generation of cracks in the copper sintered body can be prevented. Thereby, the thermal conductivity of the copper sintered body and the bonding strength between the chip parts and the substrate can be further improved. From this point of view, D ₉₀ /D ₅₀ is preferably 3.7 or less.

The value of D ₉₀ /D ₅₀ is not particularly limited as long as it satisfies the relationship of 1.2≦D ₉₀ /D ₅₀ ≦3.7. The upper limit of D ₉₀ /D ₅₀ is more preferably 3.0 or less, 2.9 or less, or 2.5 or less. The lower limit 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 not less than 1.0 m ² /g and not more than 8.0 m ² /g. By setting the BET specific surface area of copper-containing particles to 1.0 m ² /g or more, the contact between copper-containing particles can be increased, and the surface diffusion of copper atoms can be increased to activate sintering. In the case of damage to the chip 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 increases on the surface of the copper-containing particles, so the degree of contact between the copper-containing particles on the entire surface decreases, which may hinder the densification of the copper-containing particles. to sinter. From this point of view, by setting the BET specific surface area of the copper-containing particles to 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 bond between the chip component and the substrate can be improved. the bonding strength.

The BET specific surface area of the copper-containing particles is not particularly limited as long as it is not less than 1.0 m ² /g and not more than 8.0 m ² /g. 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 at most 8.0 m ² /g, more preferably at most 7.6 m ² /g, or at most 5.7 m ² /g.

[Binder Resin] The binder resin is a component that forms an organic vehicle in the copper oxide paste together with the following organic solvent. Binder resin is added to the copper oxide paste to give it an appropriate 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 by 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 used for sintering. Any resin may be used as long as it easily reacts with oxygen or carbon monoxide and tends to 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, butyral resins such as polyvinyl butyral, and the like may be mentioned.

The content of the binder resin is not particularly limited. The content of the binder resin is preferably at least 0.01% by mass or at least 0.05% by mass based on the copper oxide paste. In addition, the content of the binder resin is preferably 5.0% by mass or less, or 1.0% by mass or less.

In order to improve the viscosity or printability of the copper oxide paste, the content of the binder resin is preferably at least 0.01% by mass, and may be at least 0.05% by mass. On the other hand, in order to reduce the amount of resin remaining in the wiring after sintering and achieve lower resistivity, the content of the binder resin is preferably 5% by 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 appropriate boiling point, vapor pressure and viscosity. For example, hydrocarbon-based solvents, chlorinated hydrocarbon-based solvents, cyclic ether-based solvents, amide-based solvents, ethylene-based solvents, ketone-based solvents, alcohol-based compounds, polyol ester solvents, and polyol ethers solvents, terpene solvents, 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 use of the copper oxide paste Such as solvents with a boiling point of about 200°C.

The content of the organic solvent is not particularly limited. The organic solvent may be contained at 5 mass % or more, 7 mass % or more, or 10 mass % or more with respect to the copper oxide paste according to the use of the copper oxide paste. On the other hand, from the viewpoint of the upper limit of the content, the organic solvent may be contained at 40 mass % or less, 30 mass % or less, or 25 mass % or less with respect to the copper oxide paste.

[other ingredients] The copper oxide paste may contain optional components other than the components of the above-mentioned copper-containing particles, resin binder, and organic solvent. Metal salts and polyols are arbitrary 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 gaps between the particles and fill the gaps, which can further improve the thermal conductivity of the obtained copper sintered body and the bonding strength between the chip parts and the substrate.

As the metal salt, for example, a copper salt can be used, and specifically, one or more of copper (II) acetate, copper (II) benzoate, and copper (II) bis(acetylacetonate) can be used.

As said polyhydric alcohol, 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 semimetals other than copper, including compounds such as composite oxides formed by combining copper with metals and/or semimetals other than copper. The inorganic component may, for example, be gold, silver or platinum as a metal, boron as a semimetal, or glass frit as a metal oxide.

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

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

On the other hand, if the viscosity of the paste is too high, it may be difficult for the paste coated on the substrate 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] When analyzing generally available copper oxide paste, for example, the method described below can be used. In order to obtain the weight ratio of the vehicle and the binder resin contained in the vehicle to the solvent, the paste was heated at a rate of 10° C. per minute using a thermogravimetric analysis (TGA) device, and the weight loss was measured. The weight reduction in the first stage is the weight ratio of the solvent to the copper oxide paste, and the weight reduction in 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 copper-containing particles. Furthermore, in order to specify the type of solvent and binder resin, it can be known by using a CHNS analyzer to obtain the composition ratio of carbon, hydrogen, nitrogen, and sulfur, and using thermogravimetric-mass analysis (TGA- MS) device to determine the molecular weight of molecules released from the paste during the first and second stages of heating. In addition, in order to obtain information related to copper-containing particles, it is only necessary to dilute the copper oxide paste with an organic solvent such as isopropanol, use a centrifuge to separate the copper-containing particles from the medium, and analyze the obtained by various analysis methods. The copper-containing particles can be analyzed. For example, in order to know the ratio of Cu ₂ O and CuO, X-ray diffraction method can be used for analysis, and it can be obtained from the intensity of diffraction peaks originating 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 obtained by measuring the adsorption amount of helium.

[How to make paste] In the copper oxide paste, the above-mentioned binder resin and a solvent are mixed, copper particles are added, and kneading is performed using a mixing device such as a planetary mixer. Moreover, in order to improve the dispersibility of a particle, you may use a three-roll mill as needed.

The copper oxide paste of this embodiment is used, for example, in the following electronic component manufacturing method, and can form a copper sintered body between the chip component and the substrate to firmly bond the chip component and the substrate. This kind of copper sintered body has high thermal conductivity, which can conduct the heat generated by the chip parts to the substrate for heat dissipation.

Since the copper oxide paste of this embodiment has high heat dissipation, low resistivity, and high adhesion to the substrate, it can be used to bond chip components such as power devices or laser diodes to the substrate. Furthermore, it can be used for any purpose 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 comprises the following steps: coating or printing the above-mentioned copper oxide paste on the surface of the substrate; and performing heat treatment at a temperature of 200°C to 600°C in a reducing gas atmosphere. A copper sintered body was obtained on the substrate.

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

[Coating or printing of paste] The manufacturing method of the electronic component of this embodiment first coats or prints the said copper oxide paste on the surface of a board|substrate.

The type 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. Also, regarding the properties of the substrate, a substrate having heat dissipation properties can be used.

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

[Drying of Substrate] In the manufacturing method of the electronic component of this embodiment, it is preferable to dry the substrate coated or printed with the copper oxide paste at a temperature of not less than 60°C and not more than 120°C as needed. This drying treatment is performed 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 coated 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 hot plate or the heating furnace set to 60-120 degreeC is mentioned.

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

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

The applied pressure is preferably not less than 2 MPa and not less than 30 MPa. If the pressure is less than 2 MPa, the copper-containing particles cannot be sufficiently filled, and the thermal conductivity and joint strength of the obtained copper sintered body cannot be sufficiently improved. On the other hand, since the wafer parts may be damaged if the pressure is too high, 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 it is applied to the bonding of a chip component and a substrate, it is preferable to dry the substrate coated or printed with the copper oxide paste, press the substrate, and then perform specific heat treatment. When applying to the case of forming printed wiring, it is not necessary to pressurize the board|substrate.

Various chip components such as resistors, diodes, inductors, and capacitors can be used as chip components. For example, various semiconductor wafers such as Si wafers and SiC wafers can be used. It can be a chip component 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 whose one side length is 2 mm to 20 mm, or a rectangle or substantially rectangular shape whose short side is 2 mm to 20 mm in length can be used.

[Heat treatment of substrate] In the manufacturing method of the electronic component of this embodiment, it is preferable to perform heat treatment at a temperature of not less than 200°C and not more than 600°C in a reducing gas atmosphere to 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, and the thermal conductivity and bonding strength of the obtained copper sintered body can be improved.

The reducing gas atmosphere is not particularly limited. Preferably, it is a reducing gas atmosphere containing one or two or more gases selected from the group consisting of hydrogen, formic acid, and alcohol.

For the sake of safety, it is more convenient to use the reducing gas mixed with the inert gas. As the inert gas, nitrogen, argon, or the like can be used. The concentration of the reducing gas contained in the mixed gas is not particularly limited. In order to fully reduce Cu ₂ O and CuO contained in the copper oxide paste, it is preferably at least 0.5 volume %, and may be at least 1 volume %, or may be at least 2 volume %.

The heating temperature of the heat treatment is preferably not less than 200°C and not more than 600°C. If the heating temperature is lower 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, there is a possibility that the characteristics of the wafer component will be lowered, so the heating temperature is preferably 600° C. or lower.

The heating time of this heat treatment is not specifically limited. The lower limit 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, you can choose a heating condition of about 1 hour, and at 600°C, you can choose a heating condition of about 3 minutes.

By the above manufacturing method, a copper sintered body with very low resistivity and high thermal conductivity can be obtained. For example, the obtained copper sintered body has the following characteristics: the resistivity is not less than 2.5 μΩcm and not more than 12 μΩcm, and the thermal conductivity is not less than 55 WK ^-1 m ^{-1 and} not more than 250 WK ^-1 m ^-1 . [Example]

The following examples are given to further describe the present invention in detail. The present invention is not limited by these Examples.

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

Also, other types 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 with different shapes such as cubes or octahedrons can be obtained.

[Preparation 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. Also, other types 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 in the form of thin plates or fibers can be obtained.

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

The particle size distribution of the copper-containing particles is measured by a laser diffraction scattering particle size distribution analysis method. In addition, the BET specific surface area of the copper-containing particles was measured for the copper-containing particles in which CuO particles and Cu ₂ O particles were mixed at a specific ratio by a gas adsorption method.

[Preparation of copper oxide paste] With respect to the total mass of the copper oxide paste, about 70% by mass of _Cu2O particles, about 5% by mass of CuO particles, 0.1% by mass of ethyl cellulose as a binder resin, and After 24.9% by mass of terpineol as an organic solvent, these were kneaded with a planetary mixer to obtain an oxide paste for evaluation test. In this Example 1, the copper oxide paste of Example 1-1 - Example 1-6 and the copper oxide paste of Comparative Example 1-1 - Comparative Example 1-4 were produced as shown in Table 1.

[Production of electronic parts samples] Next, the preparation method of the samples used in the evaluation test will be described. The obtained copper oxide paste was applied to a copper substrate by screen printing, and dried on a hot plate heated to 100° C. for 10 minutes in the air. Next, a square 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 sequence 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, heat treatment was carried out at 350° C. for 40 minutes in a heating furnace in an atmosphere mixed with 3 vol % hydrogen in nitrogen to produce Sintered samples. The obtained samples were subjected to the following evaluation tests of bonding strength, electrical resistivity, and the like.

[Evaluation of Bonding Strength] Die shear strength was measured by applying a shear stress to the edge of the SiC wafer using a die shear device. The shear test speed is 500 μms ^-1 , and the shear height from the substrate is 100 μm. The measured wafer shear strength can be classified into the following 3 grades of standards A to C. Based on this standard, the joint strength of the copper sintered body was evaluated. When the standard 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: More than 10 MPa and less than 20 MPa C: Less than 10 MPa

[Evaluation of resistivity] In the evaluation test of resistivity, instead of the SiC wafer, a glass wafer made of a glass plate having the same size as the SiC wafer was used to prepare a sample for the evaluation test. The reason for this is as follows. In the case of a sample of a SiC wafer formed with a Ni thin film, since the SiC wafer is bonded to the substrate via the copper sintered body, it is difficult to measure the electrical characteristics of the copper sintered body with the copper sintered body exposed. 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 electrical characteristics of the copper sintered body can be measured by exposing it.

In the same procedure as the sample using the SiC wafer, a sample laminated with the substrate, copper oxide paste, and glass wafer was produced, and then pressure and heat treatment were performed under the same conditions to obtain a laminated body with a copper sintered body . After the heat treatment, the glass wafer was peeled off to expose the surface of the copper sintered body, and 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 3 grades from A to C as shown below. The values in the parentheses noted above in the criteria of A to C are the values obtained by converting the resistivity into thermal conductivity. When the standard 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 (less than 74 Wm ^-1 K ^-1 )

Resistivity (ρ) can be converted into thermal conductivity (κ) using the well-known Wiedemann-Franz formula represented by the following formula (3). κ＝LT/ρ ・・・Formula (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 standard of A~C represents the numerical value obtained by converting the resistivity in the case of T=300K by formula (3). Thus, resistivity (ρ) can be said to be an index that is inversely proportional to 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.

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

[Table 1] Comparative example 1-1 Comparative example 1-2 Example 1-1 Example 1-2 Example 1-3 Example 1-4 Example 1-5 Examples 1-6 Comparative example 1-3 Comparative example 1-4 _D50 (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 size (D ₅₀ ) and 50% cumulative particle size/10% of the copper-containing particles contained therein Cumulative particle size (D ₅₀ /D ₁₀ ), 90% cumulative particle size/50% cumulative particle size (D ₉₀ /D ₅₀ ), and BET specific surface area (m ² /g) are all included in the scope of the present invention. Furthermore, the copper sintered body produced by these copper oxide pastes exhibits the characteristics that the bonding strength and resistivity satisfy the A or B standard. Therefore, it was confirmed that the copper oxide paste included in the scope of the present invention can provide a good bonding material.

On the other hand, in Comparative Example 1-1, Comparative Example 1-2, Comparative Example 1-3, and Comparative Example 1-4, the particle size distribution D ₅₀ , D ₅₀ /D ₁₀ , and D ₉₀ /D of the copper-containing particles ₅₀ are outside the scope of the present invention. Therefore, the bonding strength of the copper sintered body produced by these copper oxide pastes is at a relatively low level on the basis of C, and is not suitable as a bonding material. In addition, regarding Comparative Examples 1-4, the electrical resistivity and thermal conductivity are also shown on the basis of C.

<Example 2> Effect of BET specific surface area The particles obtained by precipitation from the copper salt aqueous solution can adjust the degree of agglomeration of the primary precipitated particles 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 roughness, and can provide particles with different BET specific surface areas. In addition, the electric field copper particles are adjusted in the same manner as above to adjust the degree of aggregation to form secondary particles with different surface unevenness, and then perform oxidation treatment to adjust the BET specific surface area. On the other hand, the particles obtained by high-pressure water atomization etc. are close to spherical in shape, so the overall BET specific surface area can be adjusted by adding needle-shaped or plate-shaped CuO particles for mixing.

According to the same procedure as in Example 1, relative to the total mass of the copper oxide paste, about 70% by mass of _Cu2O particles, about 5% by mass of CuO particles, 0.1% by mass of resin, and 24.9% by mass of solvent were weighed. Type mixer for kneading to make copper oxide paste. In this Example 2, the copper oxide paste of Example 2-1 - Example 2-8, and the copper oxide paste of Comparative Example 2-1 - Comparative Example 2-5 were produced. Thereafter, in the same procedure as in Example 1, samples for evaluation tests were produced, and the wafer shear strength and resistivity of the samples were measured.

Table 2 shows the measurement results of the particle size distribution and BET specific surface area (m ² /g) of the copper-containing particles, and the evaluation results of the bonding strength and electrical 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 Example 2-6 Example 2-7 Example 2-8 Comparative example 2-4 Comparative example 2-5 _D50 (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 size (D ₅₀ ) and 50% cumulative particle size/10% of the copper-containing particles contained therein Cumulative particle size (D ₅₀ /D ₁₀ ), 90% cumulative particle size/50% cumulative particle size (D ₉₀ /D ₅₀ ), and BET specific surface area (m ² /g) are all included in the scope of the present invention. Furthermore, the copper sintered body produced by these copper oxide pastes exhibits the characteristics that the bonding strength and resistivity satisfy the A or B standard. Therefore, it was confirmed that the copper oxide paste included in the scope of the present invention can provide a good bonding material.

On the other hand, in Comparative Example 2-1 to Comparative Example 2-5, the BET specific surface area of the copper-containing particle was outside the range of the present invention. Also, regarding Comparative Example 2-1, Comparative Example 2-2, Comparative Example 2-4, and Comparative Example 2-5, "D ₅₀ ", "D ₅₀ /D ₁₀ ", and Any one or more of the indicators of "D ₉₀ /D ₅₀ " is out of the scope of the present invention. Therefore, the bonding strength of the copper sintered body produced by these copper oxide pastes is at a relatively low level on the basis of C, and is not suitable as a bonding material.

<Example 3> Influence of the molar ratio of CuO/ _Cu2O Except having changed the mixing ratio (molar ratio) of _Cu2O particle and CuO particle, copper oxide paste was produced by the procedure similar to Example 1. In this Example 3, the copper oxide paste of Example 3-1 - Example 3-3, and the copper oxide paste of Comparative Example 3-1 - Comparative Example 3-3 were produced. Thereafter, in the same procedure as in Example 1, samples for evaluation tests were produced, and the wafer shear strength and resistivity of the samples were measured.

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

[table 3] Comparative example 3-1 Example 3-1 Example 3-2 Example 3-3 Comparative example 3-2 Comparative example 3-3 _D50 (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 molar 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 size (D ₅₀ ) and 50% cumulative particle size/10% of the copper-containing particles contained therein Cumulative particle size (D ₅₀ /D ₁₀ ), 90% cumulative particle size/50% cumulative particle size (D ₉₀ /D ₅₀ ), and specific surface area (m ² /g) are all included in the scope of the present invention. Moreover, the mixing ratio (molar ratio) of the _Cu2O particle and CuO particle of the copper-containing particle of these copper oxide pastes is 1.0 or more. The copper sintered body produced by the copper oxide paste exhibits the characteristics of joint strength and electrical resistivity satisfying A or B standards, and is suitable for joint materials.

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

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

Using the copper-containing particles, the ratio of the copper-containing particles and the vehicle (resin and organic solvent) is changed to copper-containing particles in terms of mass ratio: vehicle = x: 1-x, except that it is the same as in Example 1 Make copper oxide paste in the following order. Hereinafter, said "x" is called "content of copper-containing particle|grains." The vehicle used was fixed at a ratio (0.1:24.9) corresponding to "0.1% resin, 24.9% solvent" in Example 1. In this Example 4, the copper oxide pastes of Examples 4-1 to 4-5, and Comparative Example 4-1 and Comparative Example 4-2 were produced. Thereafter, in the same procedure as in Example 1, samples for evaluation tests were produced, and the wafer shear strength and resistivity of the samples were measured.

Table 4 shows the evaluation results of the content (% by mass) of the copper-containing particles, the bonding strength, and the electrical 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 within the scope of the present invention. Moreover, as shown in Table 4, content of the copper-containing particle|grains was included in the range of 60-92 mass % with respect to the total amount of copper oxide paste. The copper sintered body produced by the copper oxide paste exhibits the characteristics of joint strength and electrical resistivity satisfying A or B standards, and is suitable for joint materials.

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 joint strength and electrical resistivity of the copper sintered bodies produced by these copper oxide pastes are at a relatively low level on the basis of C, and are not suitable as joint materials.

Claims (8)

A copper oxide paste, which contains copper-containing particles, a binder resin, and an organic solvent, the above-mentioned copper-containing particles contain _Cu2O and CuO, and among the copper elements contained in the above-mentioned copper-containing particles, copper elements constituting _Cu2O and The total amount of copper elements constituting CuO is more than 90%, the 50% cumulative particle size (D ₅₀ ) of the above-mentioned copper-containing particles is 0.20 μm to 5.0 μm, and 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 above-mentioned 50% cumulative particle diameter (D ₅₀ ) and 90% cumulative particle diameter (D ₉₀ ) satisfy the following formula (2), and the above-mentioned copper-containing particles The BET specific surface area is 1.0m ² /g or more and 8.0m 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 above-mentioned copper-containing particles relative to the amount of CuO is 1.0 or more in terms of molar ratio. The copper oxide paste according to claim 1 or 2, wherein the amount of the copper-containing particles relative to the total amount of the copper oxide paste is 60% by mass or more and 92% by mass or less. A method of manufacturing an electronic component, comprising the following steps: disposing the copper oxide paste according to any one of claims 1 to 3 on the surface of a substrate by coating or printing; coating or printing the above-mentioned copper oxide paste The above-mentioned substrate of the paste is dried; on the surface of the above-mentioned dried copper oxide paste, a chip part is arranged, and from the above-mentioned chip part Apply a pressure of 2 MPa to 30 MPa on the surface toward the above-mentioned substrate; and heat-treat the above-mentioned substrate with the above-mentioned pressure applied at a temperature of 200°C to 600°C in a reducing gas atmosphere, and obtain copper sintering on the above-mentioned substrate body. The method of manufacturing an electronic component according to claim 4, wherein the above-mentioned substrate is a metal substrate, an organic polymer substrate, a ceramic substrate or a carbon substrate. The method of manufacturing 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 of manufacturing 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 of manufacturing an electronic component according to any one of claims 4 to 7, wherein the resistivity of the copper sintered body is not less than 2.5 μΩcm and not more than 12 μΩcm.