Metal material, composition, electroconductive joining material, device, and method for producing conductive joining material

Abstract

The present invention addresses the problem of providing a metal material capable of forming an electroconductive joining material having high joining strength, a composition, an electroconductive joining material, a device, and a method for producing the electroconductive joining material. This metal material has a core material and protrusions present on at least a portion of the surface of the core material, wherein the arithmetic mean diameter of the metal material in a minimum enclosing sphere is 300 nm to 650 μm, the protrusions are metal wire parts having an arithmetic mean diameter of 10-200 nm and an arithmetic mean length of 0.3-300 μm, and the metal material has five or more metal wire parts per core material.

Description

Metallic material, composition, conductive bonding material, device, and method for producing conductive bonding material

[0001] The present invention relates to a metallic material, a composition, a conductive bonding material, a device, and a method for producing a conductive bonding material.

[0002] In recent years, as semiconductor chips have become more sophisticated, higher levels of properties such as heat dissipation and adhesion to substrates have been required, and various metal materials have been used to bond semiconductor elements to lead frames (supporting members) etc. As an example of such a metal material, Patent Document 1 describes a bonding copper paste containing metal particles including predetermined copper particles and a dispersion medium ([Claim 1]).

[0003] International Publication No. 2017 / 043545

[0004] The present inventors have investigated the copper paste for bonding described in Patent Document 1 and have found that when used to form a conductive bonding material (such as a material used to bond a semiconductor chip to a substrate), the bonding strength may not be sufficient.

[0005] Therefore, an object of the present invention is to provide a metal material, a composition, a conductive bonding material, a device, and a method for manufacturing a conductive bonding material that can form a conductive bonding material having high bonding strength.

[0006] As a result of intensive research to achieve the above object, the present inventors have discovered that a conductive bonding material with high bonding strength can be formed by providing a metal material having a core material and protrusions present on at least a portion of the surface of the core material, the protrusions having a predetermined arithmetic mean diameter of the smallest encompassing sphere, and metal wire portions having an arithmetic mean diameter of 10 to 200 nm and an arithmetic mean length of 0.3 to 300 μm, and have completed the present invention. In other words, the present inventors have discovered that the above object can be achieved by the following configuration.

[0007] [1] A metallic material having a core material and protrusions present on at least a portion of the surface of the core material, wherein the arithmetic mean diameter of the smallest encompassing sphere of the metallic material is 300 nm to 650 μm, the protrusions are metal wire portions having an arithmetic mean diameter of 10 to 200 nm and an arithmetic mean length of 0.3 to 300 μm, and the metallic material has five or more metal wire portions per core material. [2] The metallic material according to [1], wherein the core material is plate-shaped and the protrusions are present on only one surface of the core material. [3] The metallic material according to [1] or [2], wherein both the core material and the protrusions contain copper. [4] The metallic material according to [1] or [2], wherein the specific surface area is 300 to 8000 m ２ / kg. [5] The metallic material according to any one of [1] to [4], wherein the arithmetic mean value of the lengths of the convex portions is 5 μm or more. [6] The metallic material according to any one of [1] to [5], wherein the metallic material has 300 or more metal wire portions per core material. [7] The metallic material according to any one of [1] to [6], wherein the upper limit of the arithmetic mean diameter of the smallest including sphere of the metallic material is less than 200 μm. [8] The metallic material according to any one of [1] to [7], wherein the lower limit of the arithmetic mean diameter of the smallest including sphere of the metallic material is 25 μm or more. [9] A composition containing the metallic material according to any one of [1] to [8] and a dispersion medium, wherein the content of the metallic material is 30 mass% or more of the composition.

[10] The composition according to [9], wherein at least one of the dispersion mediums is a compound having a boiling point of 150°C or more.

[11] The composition according to [9] or

[10] , further containing conductive particles.

[12] The composition according to any one of [9] to

[11] , further containing a resin material.

[13] The composition according to any one of [9] to

[12] , further containing a curing agent.

[14] The composition according to any one of [9] to

[13] , used for conductive bonding material applications.

[15] A conductive bonding material formed using the composition according to

[14] .

[16] A device comprising the conductive bonding material according to

[15] and a member provided on at least one surface of the conductive bonding material, wherein the member is at least one selected from the group consisting of a semiconductor element, an electrode, and a wiring.

[17] A method for producing a conductive bonding material, comprising a step of supplying the composition according to

[14] to a surface of a substrate.

[0008] According to the present invention, it is possible to provide a metal material, a composition, a conductive bonding material, a device, and a method for manufacturing a conductive bonding material that can form a conductive bonding material having high bonding strength.

[0009] FIG. 1 is a schematic cross-sectional view showing an example of the metallic material of the present invention. FIG. 2 is a schematic cross-sectional view showing another example of the metallic material of the present invention. FIG. 3A is a schematic cross-sectional view of a valve metal substrate before the anodizing step, which is a procedure showing an example of the method for producing a metallic material of the present invention. FIG. 3B is a schematic cross-sectional view of a structure after the anodizing step, which is a procedure showing an example of the method for producing a metallic material of the present invention. FIG. 3C is a schematic cross-sectional view of a structure after the metal filling step, which is a procedure showing an example of the method for producing a metallic material of the present invention. FIG. 3D is a schematic cross-sectional view of a structure after the core material forming step, which is a procedure showing an example of the method for producing a metallic material of the present invention. FIG. 3E is a schematic cross-sectional view of a structure (metallic material of the present invention) after the isolation step, which is a procedure showing an example of the method for producing a metallic material of the present invention.

[0010] The present invention will be described in detail below. The following description of the constituent elements may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the upper and lower limits. In this specification, the upper or lower limit of a numerical range described in stages may be replaced with the upper or lower limit of another numerical range described in stages. In addition, the upper or lower limit of a numerical range described in this specification may be replaced with a value shown in an example.

[0011] [Metallic Material] The metallic material of the present invention is a metallic material having a core material and protrusions present on at least a portion of the surface of the core material. The metallic material of the present invention has an arithmetic mean diameter of the smallest encompassing sphere of 300 nm to 650 μm. The protrusions of the metallic material of the present invention are metal wire portions having an arithmetic mean diameter of 10 to 200 nm and an arithmetic mean length of 0.3 to 300 μm. The metallic material of the present invention has five or more protrusions (metallic wire portions) per core material.

[0012] Here, the smallest encompassing sphere refers to the sphere with the smallest volume among those containing a metallic material. The diameter of the smallest encompassing sphere is the real cube root of six times the volume of the smallest encompassing sphere divided by pi. The arithmetic mean diameter of the smallest encompassing sphere is the arithmetic mean of the diameters of 100 smallest encompassing spheres of the metallic material. For example, this can be determined by observing the cross section of a layer containing the metallic material in the thickness direction with a microscope (e.g., an electron microscope) and measuring the maximum diameter of 100 randomly selected microparticles. In the present invention, the lower limit of the arithmetic mean diameter of the smallest encompassing sphere is preferably 500 nm or more, more preferably 750 nm or more, even more preferably 1 μm or more, and particularly preferably 25 μm or more, because this further improves the bonding strength of the resulting conductive bonding material. Similarly, the upper limit of the arithmetic mean diameter of the smallest encompassing sphere is preferably 500 μm or less, more preferably 400 μm or less, and even more preferably 350 μm or less, and is particularly preferably less than 200 μm, because this further improves the bonding strength of the formed conductive bonding material and also increases the conductivity and heat dissipation properties.

[0013] Next, an overview of the metallic material of the present invention will be described using Figures 1 and 2. Here, Figures 1 and 2 are each a schematic cross-sectional view showing an independent example of the metallic material of the present invention. The metallic material 10 shown in Figure 1 has a core material 5 and a protrusion 4 present on a portion of one main surface of the core material 5. Furthermore, the metallic material 20 shown in Figure 2 has a core material 5 and a protrusion 4 present on a portion of both main surfaces of the core material 5. Of these, the embodiment shown in Figure 1, i.e., an embodiment in which the core material is plate-shaped and the protrusions are present on only one surface of the core material, is preferred.

[0014] In the present invention, as described above, a conductive bonding material having high bonding strength can be formed by providing a metal material having a core material and protrusions present on at least a portion of the surface of the core material, the protrusions having an arithmetic mean diameter of 10 to 200 nm and an arithmetic mean length of 0.3 to 300 μm in a metal material having a core material and a protrusion having a diameter of 10 to 200 nm and a length of 0.3 to 300 μm. The reason why a conductive bonding material having high bonding strength can be formed is not clear in detail, but is presumed to be as follows. That is, the metal material of the present invention has not only a core material but also the metal wire portion as a protrusion. This increases the number of contact points between the metal materials compared to a metal material not having protrusions. Furthermore, aggregation can be suppressed compared to a metal material not having a core material (e.g., a metal wire). Therefore, it is believed that a conductive bonding material having high bonding strength can be formed.

[0015] [Core Material] The core material of the metal material of the present invention is not particularly limited as long as it can hold five or more metal wire portions (described below) per core material and the arithmetic mean diameter of the smallest encompassing sphere of the metal material is 300 nm to 650 μm, but the material is preferably a metal. The metal is not particularly limited, and examples include the same materials (metals) as the metal wire portions (described below). Of these, it is preferable that the metal be the same metal as the metal wire portions, and it is more preferable that both the core material and the metal wire portions contain copper. The method for forming such a core material is not particularly limited, but examples include plating, metal dispersion coating, screen printing coating, sputtering, and vapor deposition, as described below.

[0016] [Protrusions (Metal Wire Portions)] The protrusions of the metal material of the present invention are metal wire portions having an arithmetic mean diameter of 10 to 200 nm and an arithmetic mean length of 0.3 to 300 μm.

[0017] Here, the diameter and length of the metal wire portion can be determined, for example, by observing an SEM image using a field emission scanning electron microscope (FE-SEM). Specifically, the diameter and length of the metal wire portion are measured by observing 10 metal wire portions randomly selected from the photographed SEM image, and this is performed in 10 fields of view to measure the diameter and length of a total of 100 metal wire portions, and the average value of the measured diameter and length is referred to. In the present invention, the lower limit of the diameter (arithmetic mean value) of the metal wire portion is preferably 10 nm or more, more preferably 20 nm or more. Similarly, the upper limit of the diameter (arithmetic mean value) of the metal wire portion is preferably 100 nm or less, more preferably 50 nm or less. Furthermore, the lower limit of the length (arithmetic mean value) of the metal wire portion is preferably 5 μm or more, more preferably 10 μm or more, because this further improves the bonding strength of the formed conductive bonding material and also enhances conductivity and heat dissipation. Similarly, the upper limit of the length (arithmetic mean value) of the metal wire portion is preferably 200 μm or less, and more preferably 100 μm or less.

[0018] The metal material of the present invention has five or more of the above-mentioned metal wire portions per core material. Here, the number of metal wire portions, like the diameter and length of the metal wire portions, can be determined, for example, by observing SEM images using a field emission scanning electron microscope (FE-SEM). The number of metal wire portions can be calculated by observing one to five 500 nmφ regions on the surface of the core material, measuring the number of wires, and converting the results to calculate the number of wires in the entire metal material. In the present invention, the number of metal wire portions is preferably 300 or more, and more preferably 2000 or more, for reasons of improved conductivity and heat dissipation.

[0019] In the present invention, the metal constituting the metal wire portion is not particularly limited, but it is preferable that the metal has an electrical resistivity of 10 ３A material having a resistivity of Ω cm or less is preferred, and specific examples thereof include gold (Au), silver (Ag), copper (Cu), aluminum (Al), titanium (Ti), nickel (Ni), cobalt (Co), etc. Among these, from the viewpoint of electrical conductivity, Cu, Au, Al, Ni, and Co are preferred, Cu, Ni, and Co are more preferred, and Cu is even more preferred.

[0020] The specific surface area per unit mass of the metal material of the present invention having the above-described core material and protrusions is 100 to 50,000 m ２ / kg, and 100m ２ / kg over 50,000m ２ / kg or less is more preferable, and 1000m ２ / kg over 50,000m ２ / kg or less is more preferable, and ２ / kg over 30,000m ２ / kg or less is particularly preferable, and 3000m ２ / kg over 20,000m ２ / kg or less is most preferable. ２ Here, the specific surface area per unit mass can be measured by a known analytical method, but in the present invention, a value measured by a krypton gas adsorption method is used.

[0021] [Method for producing metal material] The method for producing a metal material of the present invention (hereinafter also formally abbreviated as "the method for producing the present invention") is not particularly limited, but is preferably a method having an anodizing step of forming an anodized film having pores on the surface of a valve metal substrate, a metal filling step of filling the pores with metal, a core material forming step of forming a core material made of metal on a part of the surface of the anodized film with the metal filled in the pores, and an isolation step of isolating the metal filled in the pores and the core material from the anodized film and the valve metal substrate.

[0022] Next, an outline of each step in the manufacturing method of the present invention will be explained using FIGS. 3A to 3E, and then each processing step will be described in detail.

[0023] As shown in Figures 3A and 3B, in the anodizing step, an anodizing treatment is performed on the surface of a valve metal substrate 1, and an anodized film 3 having pores (micropores) 2 is formed on the surface of the valve metal substrate 1. Next, as shown in Figure 3C, in the metal filling step, a metal 4 is filled into the pores 2. Next, as shown in Figure 3D, in the core material forming step, a core material 5 made of metal is formed on a part of the surface of the anodized film 3 with the metal 4 filled into the pores 2. Next, as shown in Figure 3E, in the isolation step, the filled metal 4 and core material 5 are isolated from the anodized film 3 and the valve metal substrate 1.

[0024] <Valve metal substrate> The valve metal substrate used in the manufacturing method of the present invention is not particularly limited as long as it is a substrate containing a valve metal. Specific examples of valve metals include aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony. Among these, aluminum is preferred because it has good dimensional stability and is relatively inexpensive. Therefore, in the manufacturing method of the present invention, it is preferred to use a substrate containing aluminum (hereinafter referred to as "aluminum substrate") as the valve metal substrate.

[0025] The aluminum substrate is not particularly limited, and specific examples thereof include a pure aluminum plate; an alloy plate containing aluminum as the main component and trace amounts of other elements; a substrate in which high-purity aluminum is vapor-deposited onto low-purity aluminum (for example, recycled material); a substrate in which the surface of a silicon wafer, quartz, glass, or the like is coated with high-purity aluminum by a method such as vapor deposition or sputtering; and a resin substrate laminated with aluminum.

[0026] In the valve metal substrate, the surface to be anodized in the anodizing step described below preferably has a valve metal purity of 99.5% by mass or more, more preferably 99.9% by mass or more, and even more preferably 99.99% by mass or more. When the valve metal purity is within the above range, the arrangement of the through-holes becomes sufficiently regular.

[0027] Furthermore, the surface of the valve metal substrate that is to be anodized in the anodizing step described below is preferably subjected to heat treatment, degreasing treatment, and mirror finish treatment in advance. Here, the heat treatment, degreasing treatment, and mirror finish treatment can be the same as those described in paragraphs

[0044] to

[0054] of JP 2008-270158 A.

[0028] <Anodizing Step> The anodizing step is a step of forming a porous anodic oxide film on the surface of the valve metal base by anodizing the surface of the valve metal base.

[0029] The anodizing treatment performed in the anodizing step can be a conventionally known method, but it is preferable to use a self-ordering method or constant voltage treatment because it allows the filled metal to be isolated with little variation in diameter in the isolation step described below. Here, the self-ordering method and constant voltage treatment of the anodizing treatment can be the same as the treatments described in paragraphs

[0056] to

[0108] and [Figure 3] of JP 2008-270158 A.

[0030] For example, anodizing treatment can be performed by passing a current through a solution having an acid concentration of 1 to 10% by mass, using the valve metal substrate as the anode. The solution used for anodizing treatment is preferably an acid solution, and more preferably sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, amidosulfonic acid, glycolic acid, tartaric acid, malic acid, citric acid, etc., with sulfuric acid, phosphoric acid, and oxalic acid being even more preferred, and oxalic acid being particularly preferred. These acids can be used alone or in combination of two or more.

[0031] The conditions for the anodizing treatment cannot be determined in general because they vary depending on the electrolyte used, but generally, the electrolyte concentration is 0.1 to 20 mass%, the solution temperature is −10 to 30° C., and the current density is 0.01 to 20 A / dm ２ The voltage is preferably 3 to 300 V, the electrolysis time is preferably 0.5 to 30 hours, the electrolyte concentration is 0.5 to 15 mass %, the solution temperature is −5 to 25° C., and the current density is 0.05 to 15 A / dm ２, the voltage is 5 to 250 V, the electrolysis time is 1 to 25 hours, the electrolyte concentration is 1 to 10 mass%, the solution temperature is 0 to 20°C, and the current density is 0.1 to 10 A / dm ２ More preferably, the voltage is 10 to 200 V and the electrolysis time is 2 to 20 hours.

[0032] The treatment time for the anodizing treatment is preferably 0.5 minutes to 16 hours, more preferably 1 minute to 12 hours, and even more preferably 2 minutes to 8 hours.

[0033] The thickness of the anodic oxide film formed by the anodization step is not particularly limited, but is preferably 0.3 to 300 μm, more preferably 0.5 to 120 μm, and even more preferably 0.5 to 100 μm, from the viewpoint of adjusting the length of the metal wire portion. The thickness of the anodic oxide film can be calculated, for example, by cutting the anodic oxide film in the thickness direction with a focused ion beam (FIB), taking a surface photograph (magnification 50,000 times) of the cross section with a field emission scanning electron microscope (FE-SEM), and averaging the measurements at 10 points.

[0034] The density of the pores formed by the anodization process is not particularly limited, but is preferably 2 million / mm ２ It is preferable that the density is 10 million / mm or more. ２ More preferably, it is 50 million particles / mm or more. ２ More preferably, it is 100 million / mm or more. ２ The density of the porous structure can be measured and calculated by the method described in paragraphs

[0168] and

[0169] of JP-A-2008-270158.

[0035] The average opening diameter of the pores formed by the anodization step is not particularly limited, but from the viewpoint of adjusting the diameter of the metal wire portion, it is preferably 5 to 500 nm, more preferably 20 to 400 nm, even more preferably 40 to 200 nm, and particularly preferably 50 to 100 nm. The average opening diameter of the pores can be calculated, for example, by taking a surface photograph (magnification 50,000 times) using an FE-SEM and measuring 50 points, as the average value.

[0036] <Metal Filling Step> The metal filling step is a step of filling the interior of the pores with metal after the anodizing step.

[0037] The metal may be the same as the metal constituting the metal wire portion.

[0038] Examples of methods for filling the interior of the pores with the metal include methods similar to those described in paragraphs

[0123] to

[0126] and [FIG. 4] of JP-A-2008-270158.

[0039] In the manufacturing method of the present invention, the metal filling step preferably includes a plating step, because this reduces the likelihood of hollow portions being included in the metal wire portion produced. Specifically, electrolytic plating is preferably used as a method for filling the interior of the porous structure with the metal. For example, electrolytic plating or electroless plating can be used. Here, conventional electrolytic plating methods used for coloring, etc., have difficulty selectively depositing (growing) metal in pores with a high aspect ratio. This is thought to be because the deposited metal is consumed within the pores, and plating does not grow even after electrolysis for a certain period of time. Therefore, in the manufacturing method of the present invention, when filling metal using electrolytic plating, a rest period must be provided during pulse electrolysis or constant-potential electrolysis. The rest period must be at least 10 seconds, preferably 30 to 60 seconds. It is also desirable to apply ultrasound to promote stirring of the electrolyte. Furthermore, the electrolysis voltage is usually 20 V or less, preferably 10 V or less. However, it is preferable to measure the deposition potential of the target metal in the electrolyte in advance and perform constant-potential electrolysis within +1 V of that potential. When performing constant potential electrolysis, it is desirable to use a device that can also be used with cyclic voltammetry, and potentiostat devices such as those manufactured by Solartron, BAS, Hokuto Denko, and IVIUM can be used.

[0040] A conventionally known plating solution can be used. Specifically, when depositing copper, an aqueous copper sulfate solution is generally used, with the copper sulfate concentration preferably being 1 to 300 g / L, and more preferably being 100 to 200 g / L. The addition of hydrochloric acid to the electrolytic solution can also promote deposition. In this case, the hydrochloric acid concentration is preferably 10 to 20 g / L. When depositing gold, it is desirable to use a sulfuric acid solution of gold tetrachloride and perform plating using AC electrolysis.

[0041] In the electroless plating method, it takes a long time to completely fill the pores of high aspect ratio porous material with metal, so in the manufacturing method of the present invention, it is preferable to fill the metal by electrolytic plating.

[0042] In the manufacturing method of the present invention, it is preferable to use a treatment method that combines AC electroplating and DC electroplating in this order as the electroplating treatment method. Here, in AC electroplating, for example, a voltage is applied that is modulated into a sine wave at a predetermined frequency. Note that the waveform when modulating the voltage is not limited to a sine wave, and can also be, for example, a square wave, a triangular wave, a sawtooth wave, or an inverted sawtooth wave. In addition, in DC electroplating, the treatment method in the electroplating method described above can be used as appropriate.

[0043] In the manufacturing method of the present invention, because it is possible to shorten the time required to manufacture the metal wire portion, as shown in Figure 3C, it is preferable that the metal filling in the metal filling step is a process performed on the region from the bottom of the hole to halfway through the opening, out of the entire region from the bottom of the hole to the opening.

[0044] <Core Material Forming Step> The core material forming step is a step of forming a metal core material on a portion of the surface of the anodized oxide film whose pores have been filled with metal, after the metal filling step. Here, the region where the core material is formed is a portion of the surface of the anodized oxide film, but the core material may be formed on the entire surface of the anodized oxide film as long as the arithmetic mean diameter of the smallest encompassing sphere of the metal material to be produced is 300 nm to 650 μm. Furthermore, the region where the core material is formed needs to be formed so as to cover five or more metal-filled pores, because the core material needs to hold five or more metal wire portions.

[0045] The method for forming such a core material is not particularly limited, but examples include plating, metal dispersion coating, screen printing coating, sputtering, vapor deposition, etc. Of these, it is preferable to form the core material by plating. For example, a photoresist is formed in advance in the area of ​​the surface of the anodized film with the metal filled into the pores where the core material is not to be formed, and then a processing step similar to the plating step in the metal filling process described above is performed, so that the area where the photoresist is not formed is plated with the same type of metal as the metal filled into the pores. On the other hand, when producing the metal material shown in Figure 2, it is preferable to form the core material by screen printing coating.

[0046] <Isolation process> The isolation process is a process of isolating the filled metal and core material from the anodized film and the valve metal substrate after the metal filling process, thereby obtaining a metal material having the filled metal (metal wire portion) and the core material. Here, the method of isolating the filled metal and core material from the anodized film and the valve metal substrate is not particularly limited, and a suitable example is a method of removing (for example, dissolving, peeling, etc.) the anodized film and the valve metal substrate, and then isolating the filled metal and core material. Therefore, the embodiment after the isolation process also includes, for example, an embodiment in which the filled metal and core material are dispersed in an isolated state in the treatment liquid used in the dissolution process (dissolution treatment) described below.

[0047] In the manufacturing method of the present invention, the method for removing the anodic oxide film and the valve metal substrate is not particularly limited, and for example, they may be removed by polishing. However, in order to ensure that the length of the metal wire portion (convex portion) produced is uniform, it is preferable that the isolation step includes a dissolution step, that is, that at least a portion of the anodic oxide film and the valve metal substrate is removed by dissolution treatment.

[0048] In the manufacturing method of the present invention, in order to maintain the shape and size of the metal wire portion (protrusion) to be produced, it is preferable that the isolation step includes a single-stage removal step of removing the anodic oxide film and the valve metal base material, and it is more preferable that the anodic oxide film is removed by dissolution treatment. Also, for the same reason, the isolation step may include a two-stage removal step of removing the valve metal base material and then removing the anodic oxide film, and in this case, it is more preferable that both of the two removal steps are removed by dissolution treatment.

[0049] The removal of the valve metal substrate is preferably a dissolution treatment using a treatment liquid that is difficult to dissolve an anodized film but is easy to dissolve a valve metal. Such a treatment liquid preferably has a dissolution rate for the valve metal of 1 μm / min or more, more preferably 3 μm / min or more, and even more preferably 5 μm / min or more. Similarly, the dissolution rate for the anodized film is preferably 0.1 nm / min or less, more preferably 0.05 nm / min or less, and even more preferably 0.01 nm / min or less. Specifically, the treatment liquid preferably contains at least one metal compound with a lower ionization tendency than the valve metal, and has a pH of 4 or less or 8 or more, more preferably 3 or less or 9 or more, and even more preferably 2 or less or 10 or more.

[0050] Such treatment solutions are preferably based on an acid or alkaline aqueous solution and contain, for example, compounds of manganese, zinc, chromium, iron, cadmium, cobalt, nickel, tin, lead, antimony, bismuth, copper, mercury, silver, palladium, platinum, or gold (e.g., chloroplatinic acid), their fluorides, or their chlorides. Among these, an acid aqueous solution base is preferred, and blending of chlorides is preferable. In particular, treatment solutions blended with mercury chloride in a hydrochloric acid solution (hydrochloric acid / mercury chloride) and treatment solutions blended with copper chloride in a hydrochloric acid solution (hydrochloric acid / copper chloride) are preferred from the viewpoint of treatment latitude. The composition of such treatment solutions is not particularly limited, and examples that can be used include a bromine / methanol mixture, a bromine / ethanol mixture, and aqua regia.

[0051] The acid or alkali concentration of such a treatment solution is preferably 0.01 to 10 mol / L, more preferably 0.05 to 5 mol / L. Furthermore, the treatment temperature using such a treatment solution is preferably −10° C. to 80° C., more preferably 0° C. to 60° C.

[0052] The valve metal substrate is removed by contacting the valve metal substrate after the metal filling step with the treatment solution. The contact method is not particularly limited, and examples thereof include immersion and spraying. Of these, the immersion method is preferred. The contact time is preferably 10 seconds to 5 hours, more preferably 1 minute to 3 hours.

[0053] The anodic oxide film can be removed using a solvent that selectively dissolves the anodic oxide film but does not dissolve the metal or core material filled in the pores, and either an aqueous alkaline solution or an aqueous acid solution can be used.

[0054] When an alkaline aqueous solution is used, it is preferable to use an aqueous solution of at least one alkali selected from the group consisting of sodium hydroxide, potassium hydroxide, and lithium hydroxide, and it is more preferable to use an aqueous solution of potassium hydroxide. The concentration of the alkaline aqueous solution is preferably 1 to 30% by mass. The temperature of the alkaline aqueous solution is preferably 10 to 60°C, more preferably 20 to 60°C, and even more preferably 30 to 60°C. On the other hand, when an acid aqueous solution is used, it is preferable to use an aqueous solution of an inorganic acid such as chromic acid, sulfuric acid, phosphoric acid, nitric acid, or hydrochloric acid; an organic acid such as oxalic acid; or a mixture thereof, and it is more preferable to use an aqueous solution of chromic acid. The concentration of the acid aqueous solution is preferably 1 to 30% by mass. The temperature of the acid aqueous solution is preferably 15 to 80°C, more preferably 20 to 60°C, and even more preferably 30 to 50°C.

[0055] The anodic oxide film is removed by contacting the substrate with the alkaline or acidic aqueous solution described above after the metal filling step (preferably after the valve metal substrate is removed). The contacting method is not particularly limited, and examples thereof include immersion and spraying. Of these, the immersion method is preferred. The immersion time in the alkaline or acidic aqueous solution is preferably 1 to 120 minutes, more preferably 2 to 90 minutes, even more preferably 3 to 60 minutes, and particularly preferably 3 to 30 minutes. Of these, 3 to 20 minutes is preferred, and 3 to 10 minutes is more preferred.

[0056] <Crushing Step> The manufacturing method of the present invention may include a crushing step in which the metal material (particularly the metal wire portion) obtained by isolation in the isolation step is crushed. The method for crushing the metal material is not particularly limited, but a suitable example is a method in which the metal material is crushed by impacting it in a liquid. The liquid (solvent) used for crushing is not particularly limited as long as it does not alter or dissolve the metal material. Examples include water, ethanol, methanol, acetone, methyl ethyl ketone, butanol, ethyl acetate, butyl acetate, tetrahydrofuran, toluene, dimethylformamide, cyclohexane, and cyclohexanone. Of these, water is preferred from the perspective of safety. Furthermore, the crushing step is preferably performed in water or an aqueous solution with an alkali or acid concentration of less than 1% by mass, from the perspective of producing a metal wire portion with high bonding strength upon bonding. Examples of crushing treatments include a crushing treatment using cavitation and a crushing treatment using ceramic balls. Devices such as an ultrasonic cleaner, ultrasonic homogenizer, jet mill, and wet atomizer can be used. Among these, the crushing treatment using cavitation or the crushing treatment using ceramic balls is preferred, and the crushing treatment using cavitation is more preferred.

[0057] In the present invention, the concentration of the metal material in the liquid during pressure-disintegration in the liquid is preferably 0.1 to 50 mass % because this results in uniform processing and improved productivity, and more preferably 0.5 to 30 mass %, and even more preferably 1 to 10 mass %, because this allows for the production of metal wire parts with higher bonding strength during bonding.

[0058] <Drying step> In the manufacturing method of the present invention, it is preferable to further include a drying step of drying the metal material between the isolation step and the crushing step, because this makes it possible to obtain an electrically conductive bonding material having high bonding strength when bonded. Here, the method of drying the metal material is not particularly limited, but after removing the anodized film and the valve metal base material, the metal material can be recovered and dried by performing a separation operation such as filtration using a filter or centrifugation.

[0059] <Protective Layer Forming Step> The manufacturing method of the present invention preferably further includes a step of forming a protective layer containing a corrosion inhibitor on the metal material after the isolation step (after the drying step in the case where the drying step is included), because this allows a conductive bonding material with low connection resistance to be obtained.

[0060] The corrosion inhibitor is not particularly limited, and known corrosion inhibitors can be used. Examples of corrosion inhibitors include compounds containing at least one of a nitrogen atom, an oxygen atom, and a sulfur atom. From the viewpoint of durability, the corrosion inhibitor is preferably a heterocyclic compound containing at least one of a nitrogen atom and an oxygen atom, more preferably a compound containing a five-membered ring structure containing one or more nitrogen atoms, and particularly preferably at least one compound selected from the group consisting of compounds containing a triazole structure, compounds containing a benzimidazole structure, and compounds containing a thiadiazole structure. The five-membered ring structure containing one or more nitrogen atoms may be a monocyclic structure or a partial structure constituting a fused ring.

[0061] Furthermore, the corrosion inhibitor is preferably a compound containing at least one of a polar group-containing acid and a polar group-containing base, because this facilitates adsorption to the surface of the metal material. Examples of the polar group contained in the polar group-containing acid and the polar group-containing base include a carboxylic acid group (carboxy group), a sulfonic acid group (sulfo group), a phosphonic acid group, a phosphate group, a primary to quaternary ammonium base, a carboxylate group, a sulfonate group, a phosphonate group, and a phosphate group.

[0062] Furthermore, the corrosion inhibitor is preferably a compound containing a carboxy group, since it bonds with metal ions to form complex ions, which makes it easier to protect the surface of the metal material.

[0063] Specific examples of the corrosion inhibitor include imidazole, benzimidazole, 1,2,4-triazole, benzotriazole (BTA), tolyltriazole (TTA), butylbenzyltriazole, alkyldithiothiadiazole, alkylthiol, 2-aminopyrimidine, 5,6-dimethylbenzimidazole, 2-amino-5-mercapto-1,3,4-thiadiazole, 2,5-dimercapto-1,3,4-thiadiazole (DMTDA), 2-mercaptopyrimidine, 2-mercaptobenzoxazole, 2-mercaptobenzothiazole (MBT), 2-mercaptobenzimidazole, and the like.

[0064] Other specific examples of the corrosion inhibitor include aliphatic carboxylic acids such as acetic acid, propionic acid, palmitic acid, stearic acid, lauric acid, arachidic acid, terephthalic acid, and oleic acid; carboxylic acids such as glycolic acid, lactic acid, oxalic acid, malic acid, tartaric acid, and citric acid; aminopolycarboxylic acids such as ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), iminodiacetic acid (IDA), ethylenediaminediacetic acid (EDDA), and ethylene glycol diethyl ether diaminetetraacetic acid (GEDA); uric acid; and gallic acid.

[0065] The corrosion inhibitor may be used alone or in combination of two or more. In order to improve stability over time, the corrosion inhibitor preferably contains a compound containing a nitrogen atom (nitrogen-containing compound), more preferably a nitrogen-containing compound, and even more preferably a heterocyclic compound containing at least one of a nitrogen atom and a sulfur atom.

[0066] The method for forming such a protective layer containing a corrosion inhibitor is not particularly limited, and examples thereof include a method in which the metal material recovered in the drying step is added to an aqueous solution containing a corrosion inhibitor and stirred; and a method in which the corrosion inhibitor is added to a washing solvent used to wash the metal material recovered in the drying step.

[0067] <Reduction or Removal Step> Because a conductive bonding material having low connection resistance can be obtained, the manufacturing method of the present invention preferably further includes a step of reducing or removing the surface oxide layer of the metal material between the isolation step and the crushing step (or before the drying step if the drying step is included). Examples of the reduction or removal step include a step of performing an immersion treatment using an alkaline aqueous solution or an acid aqueous solution, as described in the above-mentioned treatment for removing an anodic oxide film.

[0068] <Dehydration step> The manufacturing method of the present invention preferably further comprises a dehydration step of dehydrating the metal material as the final step of the method for producing a metal material. Here, the method for drying the metal material is not particularly limited, but examples thereof include reduced pressure drying, air drying, and vibration drying.

[0069] [Composition] The composition of the present invention is a composition containing the above-described metallic material of the present invention and a dispersion medium. The content of the metallic material in the composition of the present invention is 30% by mass or more, and more preferably 30 to 90% by mass, based on the composition.

[0070] [Dispersion Medium] The dispersion medium contained in the composition of the present invention is mainly an organic solvent, and in particular, one that has been dehydrated with various dehydrating agents is preferably used. In the present invention, in order to improve application in the coating process when forming a conductive film, it is preferable that at least one of the dispersion mediums is a compound with a boiling point of 150°C or higher, and it is more preferable to use only compounds with a boiling point of 150°C or higher as the dispersion medium. As such a compound, an alcohol-based compound is preferably used. The alcohol-based compound is not particularly limited and can be selected appropriately depending on the purpose. Specific examples include polyethylene glycol, polypropylene glycol, alkylene glycol, glycerol, etc. These may be used alone or in combination of two or more. Specifically, dispersion media with a small number of carbon atoms, such as ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, and 2,3-butanediol, which have low viscosity at room temperature, are preferred, but dispersion media with a large number of carbon atoms, such as pentanediol, hexanediol, 1,8-octanediol, and polyethylene glycol, can also be used. Of these, the most preferred dispersion medium, which has a boiling point of 150° C. or higher, is diethylene glycol.

[0071] [Surfactant] The composition of the present invention preferably contains a surfactant because it improves dispersion stability. Examples of the surfactant include nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, and fluorine-containing surfactants. These surfactants may be used alone or in combination of two or more.

[0072] The nonionic surfactant is not particularly limited, and conventionally known surfactants can be used. Examples thereof include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene polystyrylphenyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, glycerin fatty acid partial esters, sorbitan fatty acid partial esters, pentaerythritol fatty acid partial esters, propylene glycol monofatty acid esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, polyglycerin fatty acid partial esters, polyoxyethylenated castor oils, polyoxyethylene glycerin fatty acid partial esters, fatty acid diethanolamides, N,N-bis-2-hydroxyalkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid esters, trialkylamine oxide, polyethylene glycol (e.g., polyethylene glycol monostearate), and copolymers of polyethylene glycol and polypropylene glycol.

[0073] The anionic surfactant is not particularly limited, and conventionally known surfactants can be used. For example, fatty acid salts, abietic acid salts, hydroxyalkanesulfonates, alkanesulfonates, dialkylsulfosuccinate salts, linear alkylbenzenesulfonates, branched alkylbenzenesulfonates, alkylnaphthalenesulfonates, alkylphenoxypolyoxyethylenepropylsulfonates, polyoxyethylene alkylsulfophenyl ether salts, N-methyl-N-oleyl taurine sodium salt, N-alkylsulfosuccinic acid monoamide disodium salt, petroleum sulfonates, sulfated beef tallow oil, sulfate ester salts of fatty acid alkyl esters, alkane sulf ... dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate Examples of such esters include alkyl sulfate salts, polyoxyethylene alkyl ether sulfate salts, fatty acid monoglyceride sulfate salts, polyoxyethylene alkylphenyl ether sulfate salts, polyoxyethylene styrylphenyl ether sulfate salts, alkyl phosphate salts, polyoxyethylene alkyl ether phosphate salts, polyoxyethylene alkylphenyl ether phosphate salts, partially saponified products of styrene / maleic anhydride copolymers, partially saponified products of olefin / maleic anhydride copolymers, and naphthalenesulfonate formalin condensates.

[0074] The cationic surfactant is not particularly limited, and conventionally known surfactants can be used, such as alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, and polyethylene polyamine derivatives.

[0075] The amphoteric surfactant is not particularly limited, and conventionally known surfactants can be used, such as carboxybetaines, aminocarboxylic acids, sulfobetaines, aminosulfuric acid esters, and imitazolines.

[0076] In addition, among the above surfactants, "polyoxyethylene" can also be read as "polyoxyalkylene" such as polyoxymethylene, polyoxypropylene, polyoxybutylene, etc., and these surfactants can also be used in the present invention.

[0077] In the present invention, preferred surfactants include fluorine-based surfactants containing a perfluoroalkyl group in the molecule. Examples of such fluorine-based surfactants include anionic types such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and perfluoroalkyl phosphates; amphoteric types such as perfluoroalkyl betaines; cationic types such as perfluoroalkyl trimethyl ammonium salts; and nonionic types such as perfluoroalkyl amine oxides, perfluoroalkyl ethylene oxide adducts, oligomers containing perfluoroalkyl groups and hydrophilic groups, oligomers containing perfluoroalkyl groups and lipophilic groups, oligomers containing perfluoroalkyl groups, hydrophilic groups, and lipophilic groups, and urethanes containing perfluoroalkyl groups and lipophilic groups. Also suitable are the fluorine-based surfactants described in JP-A-62-170950, JP-A-62-226143, and JP-A-60-168144.

[0078] Furthermore, in the present invention, it is desirable to use surfactants among these surfactants with an HLB value of 10 or more, because this further improves dispersion stability. Here, the HLB (Hydrophile-Lipophile Balance) value is a value that represents the degree of affinity of a surfactant for water and oil (a water-insoluble organic compound). The HLB value ranges from 0 to 20, with values ​​closer to 0 indicating higher lipophilicity and values ​​closer to 20 indicating higher hydrophilicity.

[0079] In the present invention, these surfactants may be used alone or in combination of two or more. The content of these surfactants is preferably 0.001 to 10 mass %, more preferably 0.01 to 5 mass %, based on the mass of the metal material of the present invention.

[0080] [Conductive Particles] The composition of the present invention may further contain conductive particles in addition to the metal material of the present invention. Here, the conductive particles preferably contain a metal, more preferably at least one metal selected from the group consisting of gold, silver, copper, aluminum, nickel, zinc, and cobalt. Furthermore, the conductive particles may contain one or more conductive components other than metals.

[0081] In the present invention, the shape of the conductive particles is not particularly limited and may be either solid or hollow. The average major axis of the smallest enclosing ellipsoid of the conductive particles is preferably 0.01 μm or more and 50 μm or less, more preferably 0.1 μm or more and 20 μm or less, because this allows for more dense metal filling of the space relative to the thickness of the conductive bonding material described below. The average major axis of the smallest enclosing ellipsoid of the conductive particles is preferably 1 to 10 times the average minor axis, because this allows for the selection of a shape that efficiently fills the space. Here, the smallest enclosing ellipsoid refers to the ellipsoid that has the smallest volume among those that contain the conductive particles, and includes ellipsoids whose major and minor axes are the same (i.e., spheres). The average major axis of the smallest enclosing ellipsoid can be determined by observing the cross section of a layer formed using the dispersion in the thickness direction with a microscope (e.g., an electron microscope), measuring the major axes of 100 randomly selected fine particles, and calculating the average. Similarly, the average minor axis of the smallest enclosing ellipsoid can be determined by observing the cross section of a layer formed using the dispersion in the thickness direction with a microscope (e.g., an electron microscope), measuring the minor axes of 100 randomly selected microparticles, and calculating and averaging these.

[0082] When the composition of the present invention contains conductive particles, the content of the conductive particles is not particularly limited, but is preferably 5 to 70 parts by mass, and more preferably 10 to 45 parts by mass, per 100 parts by mass of the metal material of the present invention.

[0083] [Resin Material] From the viewpoint of improving adhesion, the composition of the present invention preferably further contains a resin material. Examples of the resin material include polyether resin, polyurethane resin, (unsaturated) polyester resin, alkyd resin, butyral resin, acetal resin, polyamide resin, (meth)acrylic resin, styrene / (meth)acrylic resin, polystyrene resin, nitrocellulose, benzyl cellulose, cellulose (tri)acetate, casein, shellac, gelatin, Gilsonite, rosin, rosin ester, polyvinyl alcohol, vinyl alcohol / vinyl acetate copolymer, acetoacetyl-modified polyvinyl alcohol, acetoacetyl-modified vinyl alcohol / vinyl acetate copolymer, polyvinylpyrrolidone, polyacrylamide, polyallylamine, polyethyleneimine, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, ethyl cellulose, and hydroxyethyl methyl cellulose. Examples of the resin include cellulose, hydroxypropyl methylcellulose, carboxymethyl cellulose, carboxymethyl ethyl cellulose, carboxymethyl nitrocellulose, ethylene / vinyl alcohol resin, styrene / maleic anhydride resin, polybutadiene resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinylidene fluoride resin, polyvinyl acetate resin, ethylene / vinyl acetate resin, vinyl chloride / vinyl acetate resin, vinyl chloride / vinyl acetate / maleic acid resin, fluororesin, silicone resin, epoxy resin, phenoxy resin, phenolic resin, maleic acid resin, urea resin, melamine resin, benzoguanamine resin, ketone resin, petroleum resin, chlorinated polyolefin resin, modified chlorinated polyolefin resin, chlorinated polyurethane resin, etc. These may be used alone or in combination of two or more. Among these, urethane-based resins are preferred from the viewpoint of flexibility, and epoxy-based resins are preferred from the viewpoint of heat resistance when used as electronic components.Specific examples of epoxy resins include epoxy resins having a naphthalene skeleton, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, phenol novolac-type epoxy resins, alicyclic epoxy resins, siloxane-type epoxy resins, biphenyl-type epoxy resins, glycidyl ester-type epoxy resins, glycidyl amine-type epoxy resins, and hydantoin-type epoxy resins, and these may be used alone or in combination of two or more. In particular, from the viewpoint of film formability, the epoxy resin is preferably an epoxy resin having a naphthalene skeleton, a bisphenol A-type epoxy resin, or a bisphenol F-type epoxy resin that is liquid at room temperature.

[0084] The resin material may be one that cures by itself or by reacting with an appropriate curing agent. The resin material is preferably a water-insoluble resin. The term "water-insoluble" here refers to a resin that is visually precipitation-confirmed when 1 g of the resin is added to 100 g of water and stirred at 25°C for 24 hours.

[0085] [Curing Agent] The composition of the present invention may further contain a curing agent. For example, when the composition of the present invention contains an epoxy resin, it preferably contains an epoxy resin curing agent, i.e., a catalyst that promotes the curing reaction of the epoxy resin. Examples of epoxy resin curing agents that can be used include imidazole-based, phenol-based, amine-based, acid anhydride-based, and organic peroxide-based curing agents. In particular, from the viewpoint of the storage life (life) of the composition of the present invention at room temperature, the epoxy resin curing agent is preferably a latent curing agent, and more preferably an encapsulated latent imidazole-based curing agent. The good storage life at room temperature can simplify the management of the supply and use of the composition of the present invention. Specifically, as the epoxy resin curing agent, a microencapsulated latent curing agent composed of a latent imidazole-modified core and its surface coated with polyurethane can be used. Commercially available products include, for example, Novacure 3941 (manufactured by Asahi Kasei E-Materials Corporation). The epoxy resin curing agents may be used alone or in combination of two or more types.

[0086] When the composition of the present invention contains an epoxy resin and an epoxy resin curing agent, the total content of these is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 10 to 20% by mass, relative to the total mass of the composition of the present invention.

[0087] [Reducing Agent] The composition of the present invention may contain a reducing agent. Examples of the reducing agent include hydrazine compounds such as hydrazine, hydrazine derivatives, hydrazine hydrochloride, hydrazine sulfate, and hydrazine hydrate; hydroxylamine compounds such as hydroxylamine and hydroxylamine derivatives; and sodium compounds such as sodium borohydride, sodium sulfite, sodium bisulfite, sodium thiosulfate, and sodium hypophosphite. These may be used alone or in combination of two or more.

[0088] The use of the composition of the present invention is not particularly limited, but suitable examples include use as a conductive bonding material.

[0089] [Conductive bonding material] The conductive bonding material of the present invention is a conductive bonding material formed using the composition of the present invention described above. The shape of the conductive bonding material is not particularly limited, and may be, for example, a paste or a sheet. Furthermore, the conductive bonding material of the present invention can be suitably used as a conductive bonding material for, for example, semiconductor bonding members, touch panels, electrode bonding materials for displays, electromagnetic wave shields, sintering materials, electrode materials for thin-layer ceramic capacitors, and various other devices.

[0090] [Method for Manufacturing Conductive Bonding Material] The method for manufacturing a conductive bonding material of the present invention includes a step of supplying the composition of the present invention to a substrate surface. The substrate is not particularly limited, and examples of the material include polyethylene terephthalate, polytetrafluoroethylene, polyimide, PEEK (polyether ether ketone), aluminum, glass, alumina, silicon nitride, and stainless steel. A cloth coated or impregnated with the above material may also be used as the substrate. The substrate may also be a temporary support that can be peeled off after the composition is applied. Examples of methods for applying the composition of the present invention include inkjet printing, screen printing, jet printing, a dispenser, a jet dispenser, a comma coater, a slit coater, a die coater, a gravure coater, a slit coater, letterpress printing, intaglio printing, gravure printing, stencil printing, a bar coater, an applicator, a spray coater, and electrocoating.

[0091] The method for producing a conductive bonding material of the present invention may include a step of drying the composition of the present invention supplied to a substrate. By drying the composition of the present invention, it can be separated from the substrate as a free-standing sheet. The drying method may include drying at room temperature, drying by heating, or drying under reduced pressure. For drying by heating or drying under reduced pressure, a hot plate, a warm air dryer, a warm air heating furnace, a nitrogen dryer, an infrared dryer, an infrared heating furnace, a far-infrared heating furnace, a microwave heating device, a laser heating device, an electromagnetic heating device, a heater heating device, a steam heating furnace, a hot plate press, or the like may be used. The drying temperature and time are preferably adjusted appropriately depending on the type and amount of the dispersion medium used. For example, drying at 50 to 300°C for 1 to 180 minutes is preferred. Furthermore, drying may be performed in a non-oxidizing or reducing atmosphere to prevent oxidation of the metal. Examples of suitable methods include substitution with a non-oxidizing gas such as argon, nitrogen, or water vapor, hydrogen, or formic acid, or spraying.

[0092] [Device] The device of the present invention comprises the conductive bonding material of the present invention described above and a member provided on at least one surface of the conductive bonding material, the member being at least one selected from the group consisting of semiconductor elements, electrodes, and wiring. Examples of the member include semiconductor elements, electrodes, and wiring used in the applications of the conductive bonding material of the present invention described above, such as semiconductor bonding members, touch panels, electrode bonding materials for displays, electromagnetic wave shields, sintering materials, electrode materials for thin-layer ceramic capacitors, and various other devices. The device of the present invention may also have an underfill. A typical example of a composition forming the underfill is a composition containing an epoxy resin, a curing agent, and an inorganic filler. Examples of such compositions include those described in JP-A-2014-091744, JP-A-2014-192238, JP-A-2015-021122, JP-A-2015-032639, JP-A-2015-053436, JP-A-2015-056464, JP-A-2015-140389, and JP-A-2017-008312.

[0093] The present invention will be described in more detail below with reference to examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the examples shown below.

[0094] [Example 1] <Preparation of Aluminum Substrate> A molten aluminum alloy containing 0.06% by mass of Si, 0.30% by mass of Fe, 0.005% by mass of Cu, 0.001% by mass of Mn, 0.001% by mass of Mg, 0.001% by mass of Zn, and 0.03% by mass of Ti, with the remainder being Al and inevitable impurities, was prepared. The molten aluminum alloy was then treated and filtered, and an ingot having a thickness of 500 mm and a width of 1200 mm was produced by DC (Direct Chill) casting. The surface was then scraped off to an average thickness of 10 mm using a facing mill, and the ingot was then soaked at 550°C for about 5 hours. When the temperature was lowered to 400°C, it was rolled into a 2.7 mm thick plate using a hot rolling mill. Further, the aluminum substrate was subjected to heat treatment at 500°C using a continuous annealing machine, and then finished to a thickness of 1.0 mm by cold rolling, thereby obtaining an aluminum substrate conforming to JIS (Japanese Industrial Standards) 1050. The aluminum substrate was formed into a wafer having a diameter of 200 mm (8 inches), and then subjected to the following treatments.

[0095] <Electrolytic Polishing Treatment> The above-mentioned aluminum substrate was subjected to electrolytic polishing treatment using an electrolytic polishing solution of the following composition under conditions of a voltage of 25 V, a solution temperature of 65°C, and a solution flow rate of 3.0 m / min. A carbon electrode was used as the cathode, and a GP0110-30R (manufactured by Takasago Machinery Co., Ltd.) was used as the power source. The flow rate of the electrolyte was measured using a vortex flow monitor FLM22-10PCW (manufactured by AS ONE Corporation). (Electrolytic Polishing Solution Composition) 85% by mass phosphoric acid (reagent manufactured by Wako Pure Chemical Industries, Ltd.) 660 mL Pure water 160 mL Sulfuric acid 150 mL Ethylene glycol 30 mL

[0096] <Anodic oxidation process> Next, the aluminum substrate after electrolytic polishing treatment was subjected to anodizing treatment by the self-ordering method according to the procedure described in JP 2007-204802 A. The aluminum substrate after electrolytic polishing treatment was subjected to a 5-hour pre-anodizing treatment in a 0.50 mol / L oxalic acid electrolyte solution under conditions of a voltage of 40 V, a liquid temperature of 16 ° C, and a liquid flow rate of 3.0 m / min. Thereafter, the aluminum substrate after pre-anodizing treatment was subjected to a film removal treatment by immersing it in a mixed aqueous solution of 0.2 mol / L chromic anhydride and 0.6 mol / L phosphoric acid (liquid temperature: 50 ° C) for 12 hours. Thereafter, a re-anodizing treatment was performed for 2 hours and 30 minutes in a 0.50 mol / L oxalic acid electrolyte solution under conditions of a voltage of 40 V, a liquid temperature of 16 ° C, and a liquid flow rate of 3.0 m / min, to obtain an anodized film with a film thickness of 20 μm. In both the pre-anodizing treatment and the re-anodizing treatment, a stainless steel electrode was used as the cathode, and a GP0110-30R power supply (manufactured by Takasago Machinery Co., Ltd.) was used. A NeoCool BD36 (manufactured by Yamato Scientific Co., Ltd.) was used as the cooling device, and a Pair Stirrer PS-100 (manufactured by EYELA Tokyo Rikakikai Co., Ltd.) was used as the stirring / heating device. Furthermore, the flow rate of the electrolyte was measured using a vortex flow monitor FLM22-10PCW (manufactured by AS ONE Corporation).

[0097] <Metal Filling Step> Next, electrolytic plating was performed using the aluminum substrate as the cathode and platinum as the cathode. Specifically, a copper plating solution having the composition shown below was used, and constant-current electrolysis was performed to produce a metal-filled microstructure in which copper was filled into the porous (micropore) interior. Here, constant-current electrolysis was performed using a plating device manufactured by Yamamoto Plating Tester Co., Ltd. and a power supply (HZ-3000) manufactured by Hokuto Denko Corporation. After confirming the deposition potential by performing cyclic voltammetry in the plating solution, the process was performed under the conditions shown below. (Copper Plating Solution Composition and Conditions) Copper sulfate 100 g / L Sulfuric acid 50 g / L Hydrochloric acid 15 g / L Temperature 25°C Current density 10 A / dm ２

[0098] The surface of the anodized film after filling the pores with metal was observed with an FE-SEM, and the presence or absence of sealing with metal in 1,000 pores was observed, and the sealing rate (number of sealed pores / 1,000) was calculated to be 96%. In addition, the anodized film after filling the pores with metal was cut in the thickness direction with an FIB, and the surface of the cross section was photographed (magnification 50,000 times) with an FE-SEM to check the inside of the pores. It was found that the filling height from the bottom of the sealed pores was 20 μm.

[0099] <Core material forming process> A resin layer with an opening diameter of 5 μmφ, an opening pitch of 20 μm, and a height of 10 μm was formed on the porous opening surface after metal filling by screen printing. Then, plating was performed under the same conditions as the metal filling process, filling the upper part of the pores present in the openings of the resin layer (a region 6 μm deep from the surface) with metal, and then continuing the plating process to form copper (core material) with a height of 5 μm in the openings of the resin layer. Then, only the resin layer was removed using a solvent.

[0100] <Isolation step> The structure (metal material) consisting of the filled metal and core material was isolated from the anodized film and aluminum substrate by immersing it in an aqueous potassium hydroxide solution (concentration: 5 mol / L) at 60°C for 300 seconds, thereby obtaining a metal material. Specifically, the anodized film was dissolved by immersing it in an aqueous potassium hydroxide solution (concentration: 5 mol / L) at 60°C for 300 seconds, and the aluminum substrate was peeled off simultaneously with the dissolution of the anodized film (after 300 seconds had elapsed), thereby isolating the filled metal and core material.

[0101] <Drying Step> Next, the metal material was recovered by suction filtration using a membrane (0.4 μm, PTFE, manufactured by Omnipore), and the metal material was dried.

[0102] <Cleaning / Protective Layer Formation Step / Reduction or Removal Step> Next, the metal material recovered on the membrane was washed for 1 minute using the cleaning solvent shown below. In Example 1, a corrosion inhibitor was added to the cleaning solvent, so the protective layer was formed simultaneously with the cleaning. In Example 1, citric acid was used as the corrosion inhibitor, so the surface oxide layer of the metal material was also removed simultaneously with the formation of the protective layer. Thereafter, the metal material on the membrane was recovered. (Cleaning Solvent) An aqueous solution containing 1% by mass of citric acid

[0103] <Dehydration Step> The recovered metal material was dried under reduced pressure at 50° C. for 12 hours to produce the metal material of Example 1.

[0104] <Preparation of Composition (Paste)> The produced metal material was added to polyethylene glycol (molecular weight 200) so as to give a concentration of 80 wt %, and a paste was prepared by centrifugal stirring using a Mixer (ARE-400TWIN, manufactured by Thinky Corporation).

[0105] [Example 2] A metal material was produced and a composition was prepared in the same manner as in Example 1, except that the re-anodizing treatment time in the anodizing step was set to 12 hours and the filling height in the metal filling step was set to 100 μm.

[0106] [Example 3] A metal material was produced and a composition was prepared in the same manner as in Example 1, except that the re-anodizing treatment time in the anodizing step was set to 7.5 minutes and the filling height in the metal filling step was set to 1 μm.

[0107] [Example 4] A photoresist film was formed on the porous opening surface after the anodization process (before the metal filling process), and exposure and development were carried out to form a resist pattern with an opening diameter of 1 μmφ and an opening pitch of 5 μm. Thereafter, a metal filling process was carried out, and a metal material was produced and a composition was prepared in the same manner as in Example 1, except for the addition of a process of removing the photoresist film.

[0108] Example 5 A metal material was produced and a composition was prepared in the same manner as in Example 4, except that the opening diameter of the resist pattern was set to 200 nmφ.

[0109] [Example 6] A metal material was produced and a composition was prepared in the same manner as in Example 1, except that a resin layer with an opening diameter of 5 μmφ, an opening pitch of 20 μm, and a height of 50 μm was formed by screen printing on the porous opening surface after metal filling in the core material formation process.

[0110] [Example 7] A metal material was produced and a composition was prepared in the same manner as in Example 1, except that a resin layer with an opening diameter of 5 μmφ, an opening pitch of 20 μm, and a height of 1 μm was formed by screen printing on the porous opening surface after metal filling in the core material formation process.

[0111] [Example 8] A sintered copper paste with a diameter of 5 μmφ, a pitch of 20 μm, and a thickness of 10 μm was formed by screen printing on the porous opening surface after metal filling in the core material formation process, and a separately prepared plate that had been subjected to the metal filling process was placed on top of it so that the porous opening surface faced the copper paste, and the plate was heated at 250°C for 60 minutes in a nitrogen atmosphere. A metal material was produced and a composition was prepared in the same manner as in Example 1, except for this.

[0112] Example 9 A composition (paste) was prepared by adding 68 mass% of metal material recovered in the same manner as in Example 1, 7.2 mass% of bisphenol A-type epoxy resin (YD014, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), and 4.8 mass% of a microcapsule-type latent curing agent (Novacure 3941, manufactured by Asahi Kasei E-materials Corporation) which has an imidazole-modified core and the surface of which is coated with polyurethane, to the composition, and polyethylene glycol (molecular weight 200) was added in an amount of 20 mass% relative to the total amount.

[0113] [Example 10] A composition (paste) was prepared in the same manner as in Example 9, except that the content of the metal material was changed to 56 mass% and 12 mass% of copper particles having an arithmetic mean diameter of 5 μm was further added.

[0114] Comparative Example 1 Copper particles having an arithmetic mean diameter of 5 μm were added to polyethylene glycol (molecular weight 200) so as to give a concentration of 80 wt %, and a composition (paste) was prepared by centrifugal stirring using a Mixer (ARE-400TWIN, manufactured by Thinky Corporation).

[0115] [Evaluation] For the metal materials produced or used in Examples 1 to 10, the diameter (arithmetic mean value), length (arithmetic mean value), and number of convex portions (metal wire portions), as well as the arithmetic mean diameter of the smallest encompassing sphere of the metal material, were measured using the methods described above. These results are shown in Table 1 below. The type of core material and the components of the composition (paste) are also shown in Table 1 below.

[0116] [Conductivity] The pastes prepared in Examples 1 to 10 and Comparative Example 1 were applied to a Cu plate (10 mm x 10 mm x 0.5 mm) using a metal mask (opening: 1 x 1 mm x 0.2 mm) with a squeegee, and a Cu plate (5 mm x 5 mm x 0.5 mm) was placed on the applied paste. Subsequently, using a bonding device (WP-100, manufactured by PMT), the atmosphere inside the device was replaced with reducing gas (85% N2, 15% formic acid), and then thermocompression bonding was performed at 250°C for 1 minute and 5 MPa to produce samples in which the Cu plate and paste (sheet) were bonded. Next, using a Loresta GP manufactured by Dia Instruments, the measuring terminals (pins) were placed 3 mm apart on the upper and lower copper plates, and the pressing pressure (spring pressure) of the measuring terminals was set to 200 g, and the connection resistance was measured and evaluated according to the following criteria. The results are shown in Table 1 below. <Evaluation criteria> A: 120% or less of copper resistance B: Over 120% to 150% of copper resistance C: Over 150% of copper resistance

[0117] [Bonding Strength] The die shear strength of the samples for which the connection resistance had been measured was measured using a Nordson 4000 universal bond tester, and the results were evaluated according to the following criteria. The results are shown in Table 1 below. <Evaluation Criteria> A: 15 MPa or more B: 10 MPa or more but less than 15 MPa C: Less than 10 MPa

[0118] [Heat Dissipation] The thermal conductivity of the pastes prepared in Examples 1 to 10 and Comparative Example 1 was measured by the following method and evaluated according to the following criteria. The results are shown in Table 1 below. Specifically, the prepared paste or sheet was placed on the flat side of an aluminum heat sink, measuring 20 mm x 20 mm. At this time, the paste was applied with a squeegee using a metal mask (opening: 20 x 20 mm x 0.2 mm), and then the paste was bonded by a room-temperature bonding machine (WP-100, manufactured by PMT) using a reducing gas (N ２ After using a gas containing 85% acetic acid and 15% formic acid, the atmosphere inside the device was replaced with reducing gas and then heated at 250°C for 1 minute under non-pressurized conditions. The sheet was cut into a size of 20mm x 20mm and attached to a heat sink using thermal grease. After attaching both the paste and the sheet to the heat sink, a power semiconductor TO-247 was attached as a heat source using thermal grease. Next, the temperature difference between the heat source and the heat sink surface was divided by the power consumption to calculate the thermal resistance, which was then converted into thermal conductivity. <Evaluation criteria> A: 50 W / mK or more B: 10 or more but less than 50 W / mK C: Less than 10 W / mK

[0119]

[0120] The results shown in Table 1 indicate that when a metal material without protrusions (metal wires) was used, the resulting conductive bonding material had poor conductivity, bonding strength, and heat dissipation (Comparative Example 1). In contrast, when a metal material with five or more metal wires having an arithmetic mean diameter of 10 to 200 nm and an arithmetic mean length of 0.3 to 300 μm was used as the protrusions, the resulting conductive bonding material had high bonding strength (Examples 1 to 10). In particular, a comparison of Examples 1 to 3 indicated that when the length of the metal wires was 5 μm or more, the resulting conductive bonding material had improved bonding strength, conductivity, and heat dissipation. Furthermore, a comparison of Examples 1, 4, and 5 indicated that when the number of metal wires was 300 or more, the resulting conductive bonding material had high conductivity and heat dissipation. Furthermore, a comparison between Example 1 and Example 6 revealed that when the upper limit of the arithmetic mean diameter of the smallest inclusive sphere of the metallic material is less than 200 μm, the bonding strength of the formed conductive bonding material is further improved, and the conductivity and heat dissipation are also enhanced. Furthermore, a comparison between Example 1 and Example 7 revealed that when the lower limit of the arithmetic mean diameter of the smallest inclusive sphere of the metallic material is 25 μm or more, the bonding strength of the formed conductive bonding material is further improved.

[0121] REFERENCE SIGNS LIST 1 Valve metal substrate 2 Porous (micropore) 3 Anodic oxide film 4 Convex portion (metal wire portion) 5 Core material 10, 20 Metal material

Claims

1. A metallic material having a core material and a convex portion present on at least a part of the surface of the core material, wherein the arithmetic mean diameter of the smallest inclusive sphere of the metallic material is 300 nm to 650 μm, the convex portions are metal wire portions having an arithmetic mean diameter of 10 to 200 nm and an arithmetic mean length of 0.3 to 300 μm, and the metallic material has five or more metal wire portions per core material.

2. The metallic material according to claim 1, wherein the core material is plate-shaped and the protrusions are present on only one surface of the core material.

3. The metallic material according to claim 1, wherein both the core material and the protrusions contain copper.

4. Specific surface area: 300 to 8,000 m ２ The metallic material according to claim 1, wherein the metal content is 1 / kg.

5. The metallic material according to claim 1, wherein the arithmetic mean value of the lengths of the projections is 5 μm or more.

6. The metallic material according to claim 1, wherein the metallic material has 300 or more metallic wire portions per core material.

7. The metallic material according to claim 1, wherein the upper limit of the arithmetic mean diameter of the smallest inclusive sphere of said metallic material is less than 200 μm.

8. The metallic material according to claim 1, wherein the lower limit of the arithmetic mean diameter of the smallest inclusive sphere of said metallic material is 25 μm or more.

9. A composition comprising the metallic material according to claim 1 and a dispersion medium, the metallic material being present in an amount of 30 mass% or more relative to the composition.

10. The composition according to claim 9, wherein at least one of said dispersion media is a compound having a boiling point of 150° C. or higher.

11. The composition of claim 9, further comprising conductive particles.

12. The composition of claim 9, further comprising a resin material.

13. The composition of claim 9, further comprising a curing agent.

14. The composition according to any one of claims 9 to 13, which is used as an electrically conductive bonding material.

15. A conductive adhesive formed using the composition according to claim 14.

16. A device comprising the conductive bonding material according to claim 15 and a member provided on at least one surface of the conductive bonding material, the member being at least one member selected from the group consisting of a semiconductor element, an electrode and wiring.

17. A method for producing a conductive bonding material, comprising the step of supplying the composition according to claim 14 to a surface of a substrate.

Images