Terminal

Abstract

To provide terminals employing plating films of a noble metal or a single metal, whose durability is improved even when operated under a high temperature environment, while a plating film made of a noble or single metal, such as a silver or tin plating film, is widely applied to contacts or terminal components used for the connectors, switches, or relays of electronic devices because of high conductivity.SOLUTION: A terminal includes a plating layer formed on the surface of a base material. The plating layer has a structure in which an intermetallic compound crystal including Sn, Cu, Cr, and Ni is dispersed in a parent layer including Sn and a Sn-Cu alloy. The terminal has a concentration gradient in the plating layer, in which the concentration of Cu and Sn changes from the base material toward the terminal surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a terminal suitable for use as a connecting portion for electronic components, a joining terminal, or the like. [Background technology]

[0002] Because of their high conductivity, plating films made of precious metals and single metals, such as silver and tin, are widely used for contacts and terminals in electronic devices such as connectors, switches, and relays. However, terminals made of such precious metals and single metals have issues with durability when operating in high-temperature environments.

[0003] The following Patent Document 1 discloses a tin contact terminal having a tin-copper intermetallic compound dispersed therein, characterized in that a tin plating layer having a tin-copper intermetallic compound dispersed therein is formed on the surface of a substrate made of copper or a copper alloy. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-82499 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a terminal that is excellent in durability when operating in a high-temperature environment. [Means for solving the problem]

[0006] The present invention provides a terminal having a plating layer formed on the surface of a substrate, the plating layer containing Cu and having a structure in which intermetallic compound crystals containing Sn, Cu, Cr, and Ni are dispersed in a matrix containing Sn and an Sn-Cu alloy, and the plating layer has a concentration gradient in which the concentrations of the substrate metal and Sn change from the substrate toward the surface of the terminal. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a terminal that is excellent in durability when operating in a high-temperature environment. The terminal of the present invention also has excellent impact resistance and abrasion resistance. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is an optical image of a cross section of the electroplating electrode of the present invention obtained in Example 1, thinly cut with a FIB (focused ion beam). [Figure 2] 1 is a cross-sectional SEM image of the obtained electroplating electrode of Example 1. [Figure 3A] 4 is a cross-sectional view of a plating layer for explaining measurement points in an elemental mapping analysis by EDS of the contact terminal obtained in Example 1. FIG. [Figure 3B] FIG. 3B is a diagram showing the results of elemental mapping analysis by EDS of region 001 in FIG. 3A. [Figure 3C] FIG. 3B is a diagram showing the results of elemental mapping analysis by EDS of region 002 in FIG. 3A. [Figure 3D] FIG. 3B is a diagram showing the results of elemental mapping analysis by EDS of region 003 in FIG. 3A. [Figure 3E] FIG. 3B is a diagram showing the results of elemental mapping analysis by EDS of region 004 in FIG. 3A. [Figure 3F] FIG. 3B is a diagram showing the results of elemental mapping analysis by EDS of region 005 in FIG. 3A. [Figure 3G] FIG. 3B is a diagram showing the results of elemental mapping analysis by EDS of region 006 in FIG. 3A. [Figure 4] FIG. 2 is a diagram illustrating an example of a manufacturing apparatus suitable for manufacturing metal particles of the present invention. [Figure 5] 4 is a photomicrograph showing the results of a 180-degree bending test of the contact terminal of Example 1. [Figure 6] 10 is a photomicrograph showing the results of a surface crack test on the contact terminal of Example 1. [Figure 7]1 is a micrograph showing the heat resistance test results of Example 1. [Figure 8] 10 is a photomicrograph showing the results of a 180-degree bending test of the contact terminal of Comparative Example 1. [Figure 9] 1 is a photomicrograph showing the results of a surface crack test for Comparative Example 1. [Figure 10] 1 is a photomicrograph showing the results of a heat resistance test of Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, the embodiments of the present invention will be described in more detail. First, the terminology used in this specification is as follows unless otherwise specified. (1) When we say metal, it can include not only single metallic elements but also alloys containing multiple metallic elements and intermetallic compound crystals. (2) When referring to a single metallic element, it does not mean only a substance consisting of the metallic element in its entirety, but also includes cases in which trace amounts of other substances are contained. In other words, it does not exclude substances containing trace amounts of impurities that have little effect on the properties of the metallic element. For example, when referring to a parent phase, it does not exclude a substance in which some of the atoms in a Sn crystal are replaced by other elements (e.g., Cu). For example, the other substances or other elements may be contained in the following terminals in amounts of 0 to 0.1 mass %. (3) Endotaxial bonding means that intermetallic compound crystals are precipitated in a material that will become a metal or alloy (the parent phase in this invention), and during this precipitation, the Sn-Cu alloy and the intermetallic compound crystals are bonded at the crystal lattice level to form crystal grains and crystal layers. The term endotaxial is well known and is described, for example, in Nature Chemistry 3(2): 160-6, 2011, page 160, left column, last paragraph.

[0010] The terminal of the present invention is a terminal having a plating layer formed on the surface of a substrate, and the plating layer contains Cu and has a structure in which intermetallic compound crystals containing Sn, Cu, Cr, and Ni are dispersed in a matrix phase containing Sn and a Sn-Cu alloy.

[0011] The following electrolytic plating electrode is applied to the plating bath for providing the plating layer. Hereinafter, the electrolytic plating electrode may be referred to as the "electrolytic plating electrode of the present invention."

[0012] The electrolytic plating electrode of the present invention has a structure having an intermetallic compound crystal containing Sn, Cu, Cr and Ni in a matrix containing Sn and an Sn-Cu alloy, and the composition of the structure is preferably Cu 5~85% by mass, Cr 0.001~1% by mass, Ni 0.01~5% by mass, The balance is Sn (however, unavoidable impurities may be contained in an amount of 0.1% by mass or less), The intermetallic compound crystals are present in a state of being contained in the matrix. The composition of the matrix phase is preferably 5 mass % or less of Cu, 1 mass % or less of Ni, 1 mass % or less of Cr, and the balance of Sn (however, unavoidable impurities may be contained at 0.1 mass % or less).

[0013] FIG. 1 is an optical image of a cross section of the electroplating electrode of the present invention obtained in Example 1 below, thinly cut with an FIB (focused ion beam).

[0014] The electrolytic plating electrode of the present invention may be a soluble electrode and may be produced by the following method. First, metal particles described below (hereinafter, sometimes referred to as metal particles of the present invention) are produced. Next, the obtained metal particles of the present invention are melted by high-frequency induction heating under vacuum, and then cast into a mold in a nitrogen gas atmosphere under atmospheric pressure, cooled and solidified, and formed into a rolled sheet.Multiple sheets of this can be stacked as needed (hereinafter sometimes referred to as bulk) to obtain an electrode for electroplating.

[0015] The metal particles of the present invention can be produced from raw materials having a composition of, for example, 8% by mass of Cu, 1% by mass of Cr, 1% by mass of Ni, and the remainder being Sn, by melting the raw materials, feeding them onto a dish-shaped disk rotating at high speed in a nitrogen gas atmosphere, scattering the molten metal as small droplets by centrifugal force, and cooling and solidifying them under reduced pressure.

[0016] An example of a manufacturing apparatus suitable for producing metal particles of the present invention will be described with reference to FIG. 4. The granulation chamber 1 has a cylindrical upper portion and a conical lower portion, and is fitted with a lid 2 on top. A nozzle 3 is inserted vertically into the center of the lid 2, and a dish-shaped rotating disk 4 is installed directly below the nozzle 3. Reference numeral 5 denotes a mechanism for supporting the dish-shaped rotating disk 4 so that it can move up and down. A discharge pipe 6 for the produced particles is connected to the lower end of the cone portion of the granulation chamber 1. The upper portion of the nozzle 3 is connected to a melting furnace 7 for melting the metal to be granulated. Ambient gas adjusted to a predetermined composition in a mixed gas tank 8 is supplied to the interior of the granulation chamber 1 and the upper part of the electric furnace 7 via pipes 9 and 10, respectively. The pressure within the granulation chamber 1 is controlled by a valve 11 and an exhaust device 12, and the pressure within the electric furnace 7 is controlled by a valve 13 and an exhaust device 14, respectively. The molten metal supplied from the nozzle 3 onto the dish-shaped rotating disk 4 is dispersed into fine droplets by the centrifugal force of the dish-shaped rotating disk 4, and is cooled under reduced pressure to form solid particles. The solid particles thus produced are supplied from the discharge pipe 6 to an automatic filter 15 where they are separated. Reference numeral 16 denotes a particulate recovery device.

[0017] The process of cooling and solidifying the molten metal from a high-temperature melt is important for forming the metal particles of the present invention. For example, the following conditions can be mentioned: The melting temperature of the metal in the melting furnace 7 is set to 800° C. to 1000° C., and while maintaining this temperature, the molten metal is supplied from the nozzle 3 onto the dish-shaped rotating disk 4 . The dish-shaped rotating disk 4 has an inner diameter of 35 mm and a rotor thickness of 5 mm, and rotates at 80,000 to 100,000 revolutions per minute. Granulation chamber 1: 9 x 10 -2After the pressure was reduced using a vacuum chamber capable of reducing the pressure to about 1×10 Pa, nitrogen gas at 15 to 50°C was supplied while simultaneously evacuating the gas. -1 Pa or less.

[0018] The metal particles of the present invention are obtained in this manner. The particle diameter of the metal particles of the present invention is approximately 5 μm, but the particle diameter of the metal particles of the present invention is preferably in the range of 1 μm to 50 μm, for example.

[0019] Next, the obtained metal particles of the present invention are melted by high-frequency induction heating under vacuum, cast into a mold in a nitrogen gas atmosphere under atmospheric pressure, cooled and solidified, and formed into a rolled sheet, and multiple sheets of this are stacked as necessary to obtain a bulk. The high-frequency induction heating and cooling and solidification conditions are important for forming the electrolytic plating electrode of the present invention. For example, the following conditions can be mentioned: High frequency induction heating: 9 x 10 -2 A crucible for high-frequency melting is placed in a vacuum chamber capable of reducing the pressure to about Pa, and the metal particles of the present invention are introduced into the crucible. While the pressure is reduced to about the aforementioned reduced pressure, high-frequency induction heating is performed on the metal particles of the present invention, the heating temperature is raised to 800°C to 1000°C, and the metal particles of the present invention are melted, and this temperature is maintained for 5 to 15 minutes. Cooling and solidification: Next, while nitrogen gas at 15 to 50°C is flowed into the tank, the heating temperature is set to about 400°C or higher under atmospheric pressure, the mixture is poured into a mold, and the mixture is cooled and solidified at 30°C or lower.

[0020] The electroplating electrode of the present invention preferably has, for example, the following composition: Cu 5~85% by mass, Cr 0.001~1% by mass, Ni 0.01~5% by mass, The balance is Sn (however, it may contain unavoidable impurities of 0.1 mass % or less). The composition is the same as that of the metal particles of the present invention.

[0021] The composition of the matrix phase in the electroplating electrode can be 5 mass % or less (e.g., 0.1 to 5 mass %) of Cu, 1 mass % or less (e.g., 0.01 to 1 mass %) of Ni, 1 mass % or less (e.g., 0.01 to 1 mass %) of Cr, and the remainder being Sn. The composition of the matrix is ​​the same as that of the metal particles of the present invention.

[0022] The composition of the intermetallic compound crystal in the electroplating electrode of the present invention is as follows: Sn 50~70% by mass, Cu 30~50% by mass, Cr 0.001~3% by mass, Ni 0.01~6.5% by mass It is preferable that: The proportion of the intermetallic compound crystals in the electrolytic plating electrode of the present invention is, for example, 20 to 60 mass %, and preferably 30 to 40 mass %, based on the entire electrolytic plating electrode. The intermetallic compound crystals are present in a state of being contained in the matrix.

[0023] The composition and ratio of the matrix and intermetallic compound crystals in the electrolytic plating electrode of the present invention can be satisfied by following the manufacturing conditions for the electrolytic plating electrode. The inventors have confirmed that the structure of the electrolytic plating electrode of the present invention is maintained even after rolling into a sheet and bulking.

[0024] In the electroplating electrode of the present invention, it is preferable that at least a portion of the matrix and the intermetallic compound crystals are endotaxially bonded. As described above, endotaxial bonding is a phenomenon in which intermetallic compound crystals are precipitated in a substance that will become a metal or alloy (the matrix in the present invention), and during this precipitation, the Sn-Cu alloy and the intermetallic compound crystals are bonded at the crystal lattice level to form crystal grains. The formation of endotaxial bonding can solve the problem of the brittleness of intermetallic compound crystals and suppress the decrease in mechanical strength due to changes in the crystal structure of Sn, thereby providing a contact terminal with excellent durability. The endotaxial bonding of the electrolytic plating electrode of the present invention can be formed in accordance with the manufacturing conditions of the electrolytic plating electrode described above.

[0025] Furthermore, the endotaxial bonding is preferably 30% or more, and more preferably 60% or more, of the total bonding surface between the Sn—Cu alloy and the intermetallic compound crystal in the parent phase, taken as 100%. The endotaxial bonding ratio can be calculated, for example, as follows. The cross section of the electrode for electroplating is photographed using an electron microscope, and 50 locations of the bonding surface between the Sn-Cu alloy and the intermetallic compound crystal are randomly sampled. The bonding surface is then image-analyzed to determine the extent to which endotaxial bonding, as shown in the following examples, exists on the sampled bonding surface.

[0026] The electrolytic plating electrode of the present invention is also useful as an electrolytic plating electrode (anode) for forming the plating layer. The electrolytic plating electrode of the present invention disperses nano-sized (1 μm or less) intermetallic compound crystals contained in the electrolytic plating electrode in a plating bath, and is plated onto the substrate surface together with the matrix while being charged, forming a plating layer. The formed plating layer preferably has a structure in which intermetallic compound crystals containing Sn, Cu, Cr, and Ni are dispersed in a matrix made of an Sn-Cu alloy, and at least a portion of the matrix and the intermetallic compound crystals are endotaxy-bonded. Furthermore, epitaxial bonding is preferably formed between the electrode and the substrate.

[0027] The plating bath for providing the plating layer may contain the electrolytic plating electrode of the present invention and may have, for example, the following composition: Copper sulfate 180~250g / L Stannous sulfate 30~50g / L Sulfuric acid 80~120g / L Various additives (adhesion inhibitors, interface complexing agents, film forming agents, electrodiffusion and consumption forming agents)

[0028] In addition to the above-mentioned exemplary plating bath components, known dispersants, brighteners, antioxidants, etc. may be added as needed. Examples include dispersants such as polyoxyethylene cumyl phenyl ether and polyoxyethylene lauryl ether, brighteners such as cresol sulfonic acid, acetaldehyde, and acetylacetone, and antioxidants such as formalin, catechol, and hydroquinone.

[0029] The plating temperature is, for example, 30°C or lower, and preferably 15 to 20°C.

[0030] The current density is, for example, 1 to 10 A / dm 2 The value is adjusted appropriately within the range.

[0031] The composition of the plating layer and the composition of the intermetallic compound crystals contained in the plating layer are the same as those of the electrode for electroplating of the present invention. The composition of the plating layer is Cu 5~85% by mass, Cr 0.001~1% by mass, Ni 0.01~5% by mass, The balance is Sn (however, it may contain unavoidable impurities of 0.1 mass % or less). The composition of the intermetallic compound crystal is: Sn 50~70% by mass, Cu 30~50% by mass, Cr 0.001~3% by mass, Ni 0.01~6.5% by mass is. The amount of intermetallic compound crystals contained in the plating layer is, for example, 20 to 60 mass %. The composition of the matrix is ​​also the same as that of the electrolytic plating electrode of the present invention. That is, the matrix composition is 5 mass % or less of Cu, 1 mass % or less of Ni, 1 mass % or less of Cr, and the balance is Sn (however, unavoidable impurities may be contained at 0.1 mass % or less). The above-described composition and structure of the entire plating layer, the parent phase, and the intermetallic compound can be formed under the above-described plating conditions using the electrolytic plating electrode of the present invention.

[0032] The plated substrate is then heat-treated. The heat treatment conditions are, for example, a temperature of 200°C to 220°C in an inert gas atmosphere for a heating time of, for example, about 60 to 120 minutes. In particular, these heat treatment conditions cause the plating layer to have a concentration gradient in which the concentrations of Cu and Sn change from the substrate toward the terminal surface.

[0033] Through the above operations, the metal contained in the substrate (substrate metal) diffuses into the plating layer, and Sn contained in the parent phase migrates, resulting in a concentration gradient in which the concentrations of the substrate metal and Sn change from the substrate toward the terminal surface. The plating layer has a thickness of, for example, 2 μm to 10 μm. In addition, a Sn diffusion layer is formed in a range of 0.1 μm to 10 μm from the contact point between the substrate and the plating layer toward the interior of the substrate. The following explanation takes the case where the substrate metal is Cu as an example. Specifically, the plating layer preferably has at least a first region with a high Cu concentration and a low Sn concentration, and a second region with a lower Cu concentration and a higher Sn concentration than the first region, arranged in this order from the substrate surface toward the terminal surface (composition condition 1). Furthermore, the Sn diffusion layer preferably has a concentration gradient in which the Sn concentration decreases from the contact point between the substrate and the plating layer toward the interior of the substrate. This Sn concentration gradient reduces the likelihood of vertical cracking of the substrate and also enhances the Sn's peeling, heat resistance, pressure resistance, chemical resistance, and pressure resistance. More specifically, it is preferable that a concentration gradient of Cu and Sn be formed in the plating layer from the substrate surface to the terminal surface, as shown in the following table: Note that ranges other than the first and second regions in the table below can take any value as long as the above composition condition 1 is satisfied.

[0034] [Table 1]

[0035] The substrate may be aluminum, an aluminum alloy, copper, a copper alloy, or stainless steel, and may be selected from known materials without particular limitation. For example, copper alloys include brass and phosphor bronze. When the present invention is used as a microbump, it is preferable to use Si, SiC or GaN as the semiconductor substrate and to provide Ti / Cu plating as the underlayer. Another embodiment of the present invention provides a bump. The bump of the present invention has the same composition as the terminal of the present invention. That is, the bump of the present invention comprises a plating layer formed on the surface of a substrate, the plating layer having a structure in which intermetallic compound crystals containing Sn, Cu, Cr, and Ni are dispersed in a matrix containing Sn and an Sn-Cu alloy, and the plating layer has a concentration gradient in which the concentrations of Cu and Sn change from the substrate to the bump surface. The details of the plating layer of the bump of the present invention are the same as those of the plating layer of the terminal of the present invention, and the method for forming the plating layer on the bump surface is also the same as those of the terminal of the present invention, so detailed explanations are omitted.

[0036] In the terminal and bump of the present invention, by adjusting the concentration gradient of the plating layer as described above, and in particular by diffusing Cu into the terminal surface side of the plating layer, the Vickers hardness of the plating layer surface can be set to a range of 10 (Hv) to 500 (Hv). Having such hardness has the advantage of improving impact resistance, abrasion resistance, etc. A more preferred range of hardness is 150 to 400 Hv. The Vickers hardness is measured in accordance with JIS Z 2244-1:2020.

[0037] A titanium, nickel, or nickel alloy layer can be formed as the base of the plating layer to further improve heat resistance. Nickel alloys that can be used include those containing one or two of the following elements: iron, tin, zinc, copper, cobalt, phosphorus, silver, boron, etc. The thickness of this base layer is preferably, for example, about 0.1 μm to 1.5 μm. [Example]

[0038] The present invention will be further described below with reference to examples and comparative examples, but the present invention is not limited to the following examples. Example 1 Using raw materials having a composition consisting of 8 mass % Cu, 1 mass % Cr, 1 mass % Ni, and the remainder Sn, metal particles 1 having a diameter of approximately 3 to 50 μm were produced by the production apparatus shown in FIG. In this case, the following conditions were adopted: A melting crucible was placed in a melting furnace 7, and the raw materials were placed therein and melted at 900°C. While maintaining this temperature, the molten metal was supplied from the nozzle 3 onto the dish-shaped rotating disk 4. The dish-shaped rotating disk 4 used was a dish-shaped disk with a diameter of 35 mm and a rotating disk thickness of 3 to 5 mm, and was rotated at 80,000 to 100,000 revolutions per minute. Granulation chamber 1: 9 x 10 -2 After the pressure was reduced using a vacuum chamber capable of reducing the pressure to about 1×10 Pa, nitrogen gas at 15 to 50°C was supplied while simultaneously evacuating the gas. -1 Pa or less. The obtained metal powder 1 was used to prepare an electrode for electrolytic plating of the present invention. In this case, the following conditions were adopted: High frequency induction heating: 9 x 10 -2 A crucible for high-frequency melting was placed in a vacuum chamber capable of reducing the pressure to approximately Pa, and the metal particles 1 of the present invention were introduced into the crucible.While the pressure was reduced to approximately the above-mentioned reduced pressure, high-frequency induction heating was performed on the metal particles 1 of the present invention, the heating temperature was raised to 900°C, and the metal particles 1 of the present invention were melted, and the temperature was maintained for 5 minutes. Cooling and solidification: Next, nitrogen gas at 15 to 50°C was flowed into the tank for 10 minutes, and the heating temperature of the raw material was set to about 400°C under atmospheric pressure, followed by casting into a mold and cooling and solidification at room temperature. The obtained material was rolled into a sheet, which was then placed in a cutter heated to 150°C and cut into 1 cm to 3 cm squares to obtain the electroplating electrode of Example 1, which was then placed in the following plating bath.

[0039] The obtained electroplating electrode of Example 1 had a cross section as shown in Fig. 1. Fig. 2 is a cross-sectional SEM image of the obtained electroplating electrode of Example 1, which confirmed that intermetallic compound crystals (dark color) containing Sn, Cu, Cr, and Ni were present within a matrix phase (light color) containing Sn and an Sn-Cu alloy. Furthermore, elemental mapping analysis by EDS of a cross section of the electroplating electrode revealed that the composition was 8 mass % Cu, 1 mass % Cr, 1 mass % Ni, and the balance Sn. It was also found that the electroplating electrode of Example 1 contained intermetallic compound crystals contained in the matrix, and that at least a portion of the matrix and the intermetallic compound crystals were endotaxy bonded. The composition of the electrolytic plating electrode is as follows: Cu 5~85% by mass, Cr 0.001~1% by mass, Ni 0.01~5% by mass, The balance was Sn. In addition, the composition including the intermetallic compound crystal and the endotaxial bonding portion is Sn 50~70% by mass, Cu 30~50% by mass, Cr 0.001~3% by mass, Ni 0.01~6.5% by mass It turned out to be. Furthermore, the intermetallic compound crystals in the electrolytic plating electrode accounted for 30 to 35 mass %.

[0040] (Preparation of contact terminals) A phosphor bronze or brass plate (thickness 0.30 mm) was used as the substrate (cathode). Electrolytic plating was carried out on the substrate under the following conditions using the electrolytic plating electrode of the present invention as the electrolytic plating electrode, to obtain a plated sheet metal.

[0041] Plating bath composition (concentration per liter of water): Copper sulfate 180~250g / L Stannous sulfate 30~50g / L Sulfuric acid 80~120g / L A known reference electrode was used and an appropriate amount of additive was added.

[0042] Plating temperature: 70℃ Current density: 3A / dm 2 Heat treatment temperature of the substrate after plating: 200℃ Heat treatment time of the substrate after plating: 300 seconds (in a nitrogen atmosphere)

[0043] The composition of the contact terminal obtained was the same as that of the electrode for electrolytic plating of the present invention.

[0044] The contact terminals thus obtained were heated under the following conditions. Heating temperature: 217℃ Cooking time: 60 minutes

[0045] The plating layer of the contact terminal was disassembled, and the concentrations of Cu and Sn in the direction from the substrate toward the surface of the contact terminal were measured by EDS, yielding the results shown in Figure 3. Figure 3A is a photograph of a cross section of the plating layer and substrate subjected to EDS analysis, with numbers 001-002 on the substrate side and numbers 003-006 from the substrate surface toward the terminal. Figures 3B-G are diagrams showing the results of elemental mapping analysis by EDS of the contact terminal obtained in Example 1. The concentrations of Cu and Sn in each region, especially the first region (region 003 in Figure 3) and the second region (region 006 in Figure 3), are as shown in Table 2 below.

[0046] [Table 2]

[0047] The Cu and Sn concentration measuring device is as follows. Measuring equipment name: JSM-IT300HR Manufacturer: JEOL Ltd. Measurement mode: ANALYTICAL SCANNING ELECTRON, MICROSCOPE

[0048] The durability of the contact terminal obtained in Example 1 was examined by the following experiment. <Durability testing method> (180° bending test) A contact terminal using a brass plate as the substrate was subjected to a 180-degree bending test, and the presence or absence of cracks in the plating layer was observed. The thickness of the plating layer was 5 μm. Figure 5 shows micrographs showing the results of the 180-degree bending test of the contact terminal of Example 1 (a is a photograph of the entire contact terminal, and b is an enlarged photograph of the bent portion). As a result, no cracks were observed in the plating layer of the contact terminal of Example 1. (Surface crack test) The resulting contact terminal was punched from the backside and subjected to a surface crack test. Fig. 6 is a micrograph showing the results of the surface crack test for the contact terminal of Example 1. As a result, no surface cracks due to punching were observed in the plating layer of the contact terminal of Example 1. (Heat resistance test) The obtained contact terminal was left standing at a temperature of 230°C for 500 hours, and the surface condition of the plating layer was observed under a microscope. Fig. 7 is a micrograph showing the heat resistance test results of Example 1. No change was observed in the plating layer of the contact terminal of Example 1 before and after the heat resistance test.

[0049] Comparative Example 1 Example 1 was repeated except that the electrolytic plating electrode in Example 1 was changed to a tin metal, and the 180° C. bending test, surface crack test, and heat resistance test were carried out. 8 shows micrographs showing the results of a 180-degree bending test of the contact terminal of Comparative Example 1 (a is a photograph of the entire contact terminal, and b is a magnified photograph of the bent portion). As a result, cracks occurred in the plating layer and peeling occurred between the plating layer and the base material during the 180-degree bending test. 9 is a photomicrograph showing the results of the surface crack test of Comparative Example 1. As a result, surface cracks due to punching were confirmed in the plating layer of the contact terminal of Comparative Example 1. 10 is a micrograph showing the results of the heat resistance test of Comparative Example 1. As a result, it was confirmed that partial dissolution occurred in the plating layer of the contact terminal of Comparative Example 1 under the heating condition of leaving it at a temperature of 250°C for 500 hours.

[0050] Comparative Example 2 Example 1 was repeated except that the heating temperature for the contact terminal obtained in Example 1 was changed to 190° C., and the above-mentioned 180-degree bending test, surface crack test, and heat resistance test were carried out. As a result, in the 180-degree bending test, cracks occurred in the plating layer and peeling occurred between the plating layer and the base material. In the surface crack test, surface cracks due to punching were confirmed in the plating layer of the contact terminal. In the heat resistance test, it was confirmed that partial dissolution occurred in the plating layer of the contact terminal when it was left standing at a temperature of 250°C for 500 hours. The plating layer did not have a concentration gradient in which the concentrations of the base metal and Sn changed from the base material toward the terminal surface.

[0051] The present invention has been described in detail above with reference to the accompanying drawings, but the present invention is not limited to these, and it is obvious that a person skilled in the art can come up with various modifications based on the basic technical ideas and teachings thereof. [Explanation of symbols]

[0052] 1 Granulation chamber 2 lid 3 nozzles 4-plate rotating disc 5 Rotating disk support mechanism 6 Particle discharge pipe 7 Melting furnace 8 Mixed Gas Tank 9 Piping 10 Piping 11 Valve 12 Exhaust system 13 Valve 14 Exhaust system 15 Automatic Filter 16. Particle collection device

Claims

1. A terminal having a plating layer formed on the surface of a substrate, the plating layer contains Cu and has a structure in which intermetallic compound crystals containing Sn, Cu, Cr, and Ni are dispersed in a matrix containing Sn and a Sn—Cu alloy; the plating layer has a concentration gradient in which the concentrations of the base metal and Sn change from the base material toward the terminal surface; Terminal.

2. 2. The terminal according to claim 1, wherein the substrate has a Sn diffusion layer extending from a contact point between the substrate and the plating layer toward the interior of the substrate in a range of 0.1 μm to 10 μm.

3. The composition of the plating layer is Cu 5-85% by mass, Cr 0.001 to 1% by mass, Ni 0.01 to 5% by mass, The balance is Sn (however, inevitable impurities may be contained in an amount of 0.1% by mass or less), The terminal according to claim 1 .

4. The composition of the intermetallic compound crystal is Sn 50-70% by mass, Cu 30-50% by mass, Cr 0.001 to 3% by mass, Ni 0.01-6.5% by mass The terminal according to claim 1 ,

5. 2. The terminal according to claim 1, wherein the Vickers hardness of the surface of said plating layer is in the range of 10 (Hv) to 500 (Hv).

6. A bump having a plating layer formed on the surface of a substrate, the plating layer contains Cu and has a structure in which intermetallic compound crystals containing Sn, Cu, Cr, and Ni are dispersed in a matrix containing Sn and a Sn—Cu alloy; the plating layer has a concentration gradient in which the concentrations of the base metal and Sn change from the base material toward the bump surface; bump.

7. 7. The bump according to claim 6, wherein the plating layer has a diffusion layer of the base metal in a range of 0.1 μm to 10 μm from the base material toward the terminal surface.

8. 7. The bump according to claim 6, wherein the Vickers hardness of the surface of the plating layer is in the range of 10 (Hv) to 500 (Hv).

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