electroless plating solution

Abstract

Precious metal and single-metal plating, such as silver and tin, are widely used in electronic equipment connectors, switches, relays, and other contact and terminal components due to their high conductivity. However, terminals using such precious metals or single metals have had durability issues. [Solution] The above problem was solved by an electroless plating solution containing a metal ion source in which intermetallic compound crystals containing Sn, Cu, Cr, and Al are dispersed in a matrix phase containing Sn and a Sn-Cu alloy.

Description

[Technical Field]

[0001] This invention relates to an electroless plating solution. [Background technology]

[0002] Precious metal and single-metal plating films, such as silver and tin, are widely used in electronic devices for connectors, switches, relays, semiconductor bumps, and circuit board wiring coatings, as well as for contacts, terminals, and component coatings. However, terminals using such precious metals or single metals have had issues with durability over time.

[0003] Furthermore, Patent Document 1 discloses a tin-copper intermetallic compound dispersed tin contact terminal, characterized in that a tin plating layer in which a tin-copper intermetallic compound is dispersed 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 Publication No. 2003-82499 [Overview of the project] [Problems that the invention aims to solve]

[0005] The object of the present invention is to provide an electroless plating solution that can produce a plated film with improved durability over time. [Means for solving the problem]

[0006] The present invention provides an electroless plating solution containing a metal ion source in which intermetallic compound crystals containing Sn, Cu, Cr, and Al are dispersed in a matrix phase containing Sn and a Sn-Cu alloy. The present invention also provides an electroless plating solution containing a metal ion source in which intermetallic compound crystals containing Sn, Cu, Cr, Al, and Ni are dispersed in a matrix phase containing Sn and a Sn-Cu alloy. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an electroless plating solution that can obtain a plated film with improved durability over time. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional SEM image of bulk 1 from Example 1. [Figure 2] This figure shows the results of elemental mapping analysis by EDS on one cross-section of bulk 1. [Figure 3] This figure shows the results of elemental mapping analysis by EDS at a specific location in one cross-section of bulk material 1. [Figure 4] This figure shows the results of elemental mapping analysis by EDS at a specific location in one cross-section of bulk material 1. [Figure 5] This figure shows the results of elemental mapping analysis by EDS at a specific location in one cross-section of bulk material 1. [Figure 6] This figure shows the results of elemental mapping analysis by EDS at a specific location in one cross-section of bulk material 1. [Figure 7] This figure shows the results of elemental mapping analysis by EDS at a specific location in one cross-section of bulk material 1. [Figure 8] This figure shows the results of elemental mapping analysis by EDS at a specific location in one cross-section of bulk material 1. [Figure 9] This is a cross-sectional SEM image of bulk 2 from Example 2. [Figure 10] This figure shows the results of elemental mapping analysis by EDS on one cross-section of bulk 2. [Figure 11] This figure shows the results of elemental mapping analysis by EDS at a specific location in one cross-section of bulk 2. [Figure 12] This figure shows the results of elemental mapping analysis by EDS at a specific location in one cross-section of bulk 2. [Figure 13] This figure shows the results of elemental mapping analysis by EDS at a specific location in one cross-section of bulk 2. [Figure 14] It is a figure showing the result of elemental mapping analysis by EDS at a specific location of one cross-section of bulk 2. [Figure 15] It is a figure showing the result of elemental mapping analysis by EDS at a specific location of one cross-section of bulk 2. [Figure 16] It is a figure showing the result of elemental mapping analysis by EDS at a specific location of one cross-section of bulk 2. [Figure 17] It is a figure for explaining an example of a manufacturing apparatus suitable for manufacturing the metal particles of the present invention. [Figure 18] It is a figure showing the results of the durability of the articles of Examples 1 and 2.

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in more detail. First, the terminology in this specification is as follows even without special explanation. (1) When referring to a metal, it may include not only a single metal element but also an alloy containing a plurality of metal elements and an intermetallic compound crystal. (2) When referring to a single metal element, it does not mean only a substance consisting entirely of the metal element, but also includes cases where it contains a tiny amount of other substances. That is, it is not meant to exclude those containing trace amounts of impurities that hardly affect the properties of the metal element. For example, in the case of a matrix phase, it is not meant to exclude those in which some of the atoms in the Sn crystal are replaced by other elements (for example, Cu). For example, the other substance or other element may be contained in the following electrodes in an amount of 0 to 0.1% by mass.

[0010] The electroless plating solution of the present invention exists in the following two forms. (1) It contains a metal ion source in which intermetallic compound crystals containing Sn, Cu, Cr, and Al are dispersed in a matrix phase containing Sn and an Sn-Cu alloy. (2) It contains a metal ion source in which intermetallic compound crystals containing Sn, Cu, Cr, Al, and Ni are dispersed in a matrix phase containing Sn and an Sn-Cu alloy.

[0011] The metal ion source in the present invention can be manufactured as follows.

[0012] First, the metal particles described below (hereinafter sometimes referred to as the metal particles of the present invention) are manufactured. 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 to form a rolled sheet, and multiple sheets of this sheet are stacked as needed (hereinafter sometimes referred to as bulk), and then crushed to obtain the material.

[0013] In the embodiment of the present invention, the metal particles can be produced from raw materials having a composition of, for example, 8 mass% Cu, 0.5 mass% Cr, 0.2 mass% Al, and the remainder being Sn. Furthermore, in the embodiment of (2) above, it can be manufactured from raw materials having a composition of, for example, 8 mass% Cu, 0.5 mass% Cr, 0.5 mass% Al, 0.5 mass% Ni, and the remainder being Sn. For example, the metal particles of the present invention can be obtained by melting the raw material, supplying it to a dish-shaped disc rotating at high speed in a nitrogen gas atmosphere, scattering the molten metal as droplets by centrifugal force, and cooling and solidifying it under reduced pressure.

[0014] An example of a suitable manufacturing apparatus for producing metal particles of the present invention will be described with reference to Figure 17. The granulation chamber 1 has a cylindrical upper part and a cone-shaped lower part, and has a lid 2 on the upper part. A nozzle 3 is inserted vertically into the center of the lid 2, and a dish-shaped rotating disk 4 is provided directly below the nozzle 3. Reference numeral 5 denotes a mechanism that supports the dish-shaped rotating disk 4 so that it can move up and down. A discharge pipe 6 for the generated particles is connected to the lower end of the cone portion of the granulation chamber 1. The upper part of the nozzle 3 is connected to an electric furnace (high-frequency furnace: conventionally a ceramic crucible was used, but in the present invention a carbon crucible is used) 7 for melting the metal to be granulated. The atmospheric gas, which has been adjusted to a predetermined composition in the mixed gas tank 8, is supplied to the inside of the granulation chamber 1 and the upper part of the electric furnace 7, respectively, by pipes 9 and 10. The pressure inside the granulation chamber 1 is controlled by valve 11 and exhaust device 12, and the pressure inside the electric furnace 7 is controlled by valve 13 and exhaust device 14. Molten metal supplied from nozzle 3 onto dish-shaped rotating disk 4 is dispersed in the form of fine droplets by centrifugal force from the dish-shaped rotating disk 4, and then cooled under reduced pressure to become solid particles. The generated solid particles are supplied from discharge pipe 6 to automatic filter 15 for separation. Reference numeral 16 denotes a particulate matter recovery device.

[0015] The process of melting the molten metal at high temperatures and then cooling and solidifying it is important for forming the metal particles of the present invention. For example, the following conditions can be cited. The melting temperature of the metal in the melting furnace 7 is set to 800°C to 1000°C, and while maintaining that temperature, the molten metal is supplied from the nozzle 3 onto the dish-shaped rotating disk 4. As the disc-shaped rotating disk 4, a disc-shaped disk with an inner diameter of 35 mm and a rotating body thickness of 5 mm is used, and it is set to rotate at 80,000 to 100,000 revolutions per minute. Granulation chamber 1 is 9 × 10 -2 Using a vacuum chamber capable of reducing pressure to approximately Pa, the pressure is reduced, and simultaneously, nitrogen gas at 15-50°C is supplied while the chamber is evacuated, resulting in a pressure of 1 × 10⁻¹⁶ in the granulation chamber 1. -1 It should be Pa or less.

[0016] As described above, the metal particles of the present invention in forms (1) and (2) are obtained. The particle size of the metal particles of the present invention is approximately 5 μm, but the particle size of the metal particles of the present invention is preferably in the range of 1 μm to 50 μm.

[0017] 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 to form a rolled sheet. Multiple sheets of this sheet are then stacked as needed to obtain a bulk material. Examples of the aforementioned high-frequency induction heating and cooling solidification conditions include the following: High-frequency induction heating: 9 × 10 -2 A high-frequency induction melting crucible is placed in a vacuum chamber capable of reducing the pressure to approximately Pa. The metal particles of the present invention are introduced into the crucible, and high-frequency induction heating is performed on the metal particles of the present invention while the pressure is reduced to approximately the aforementioned degree of reduced pressure. The heating temperature is set to 800°C to 1000°C to melt the metal particles of the present invention, and this temperature is maintained for 5 to 15 minutes. Cooling and solidification: Next, while flowing nitrogen gas at 15-50°C into the tank, the heating temperature is set to approximately 400°C or higher under atmospheric pressure, the material is poured into the mold, and then cooled and solidified at 30°C or lower.

[0018] In the present invention, the bulk, for example in embodiment (1), has the following composition: Cu 0.7~15% by mass, Cr 2~0.02% by mass, Al 3~0.02% by mass, The remainder is Sn (however, it may contain unavoidable impurities of 0.1% by mass or less). Furthermore, the bulk in the present invention, for example, in embodiment (2), has the following composition: Cu 0.7~15% by mass, Cr 2~0.02% by mass, Al 3~0.02% by mass, Ni 1~0.02% by mass, The remainder is Sn (however, it may contain unavoidable impurities of 0.1% by mass or less). The above composition is the same as that of the metal particles of the present invention.

[0019] Furthermore, the composition of the bulk matrix in embodiment (1) of the present invention is Cu 5~0.02% by mass, Cr 0.001~18% by mass, Al 3~0.02% by mass, The remainder can be Sn. The composition of the matrix phase is the same as that of the metal particles of the present invention.

[0020] Furthermore, the composition of the matrix of the bulk in embodiment (2) of the present invention is Cu 5~0.02% by mass, Cr 0.001~18% by mass, Al 3~0.02% by mass Ni 1~0.02% by mass, The remainder can be Sn. The composition of the matrix phase is the same as that of the metal particles of the present invention.

[0021] Furthermore, the composition of the bulk intermetallic compound crystal in embodiment (1) of the present invention is: Cu 5~50% by mass, Cr 0.001~10% by mass, Al 0.1~20% by mass, The remainder can be Sn.

[0022] Furthermore, the composition of the bulk intermetallic compound crystal in embodiment (2) of the present invention is: Cu 5~50% by mass, Cr 0.001~18% by mass, Al 0.1~20% by mass, Ni 0.1~6.5% by mass, The remainder can be Sn.

[0023] Furthermore, in the bulk of embodiments (1) and (2) described above, the proportion of intermetallic compound crystals is, for example, 20 to 60% by mass, and preferably 30 to 40% by mass. The intermetallic compound crystal is contained within the matrix phase.

[0024] The composition and proportions of the matrix and intermetallic compound crystals of the present invention can be achieved by following the manufacturing conditions of the bulk material. The inventors have confirmed that the structure of the bulk material and the metal particles of the present invention are the same.

[0025] Furthermore, in the plating method using the electroless plating solution of the present invention, intermetallic compound crystals and matrix phase contained in the crushed bulk dissolve in the plating bath as metal ion sources, and these are plated onto the substrate surface to form a plating layer. The formed plating layer has a structure in which intermetallic compound crystals containing Sn, Cu, Cr and Al or Sn, Cu, Cr, Al and Ni are dispersed in a matrix phase made of Sn-Cu alloy.

[0026] The electroless plating solution of the present invention can contain, for example, various additives that have been conventionally known as reducing plating solutions. For example, reducing agents include hypophosphate, formaldehyde, paraformaldehyde, ammonium boro hydroxide, and dimethylamine borane. Examples of complexing agents include acetic acid, lactic acid, glycine, citric acid, malonic acid, malic acid, oxalic acid, succinic acid, tartaric acid, thioglycolic acid, ammonia, alanine, glutamic acid, and ethylenediamine. As pH adjusters, alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, and hydroxide solutions of alkali metals or alkaline earth metals such as ammonia water can be used. As acids, hydrochloric acid, sulfuric acid, nitric acid, etc. can be used. Examples of stabilizers include nitrates of lead, bismuth, thallium, etc.

[0027] In the electroless plating solution of the present invention, the metal ion source concentration is preferably, for example, 10 to 200 g / liter, and the plating temperature is preferably 25 to 65°C.

[0028] The composition of the intermetallic compound crystals contained in the resulting plating layer is the same as that of the bulk material used. Furthermore, the amount of intermetallic compound crystals contained in the plating layer is, for example, 20 to 60% by mass. The composition of the matrix phase is the same as that of the bulk material used. The composition and structure of the entire plating layer, the matrix phase, and the intermetallic compound can be formed by the plating conditions.

[0029] After plating, the substrate is heat-treated as needed. For example, the heat treatment conditions are a temperature of 100-300°C and a heating time of approximately 5-300 seconds.

[0030] Through the above procedure, a plating layer is formed on the surface of the substrate. The thickness of the plating layer is, for example, 2 μm to 10 μm.

[0031] The base material can be any metal such as aluminum, aluminum alloys, copper, copper alloys, or stainless steel, or any resin such as glass epoxy. These can be selected without any particular limitations from among known materials. For example, copper alloys can include brass and phosphor bronze.

[0032] Furthermore, a titanium, nickel, or nickel alloy layer can be formed as a base layer for the plating layer to further enhance heat resistance. Nickel alloys containing one or two elements such as iron, tin, zinc, copper, cobalt, phosphorus, silver, and boron can be used. The thickness of this base layer is preferably, for example, around 0.1 μm to 1.5 μm.

[0033] Articles having a plating film formed by the electroless plating solution in the above embodiment (1) are particularly useful, for example, as bumps or millimeter-wave radar antennas. By forming a film that does not contain the magnetic metal Ni that causes transmission loss, it has the effect of suppressing transmission loss. Furthermore, while the undercoat plating on the substrate typically has irregularities of around 5 microns, it has been confirmed that forming the plating film according to the present invention can improve the surface roughness to around 100 nanometers, which is useful as it does not cause significant transmission loss and is expected to enable high-performance transmission. Furthermore, an article having a plating film formed by the electroless plating solution in the above embodiment (2) is particularly useful as, for example, a terminal. [Examples]

[0034] 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.

[0035] Example 1 Example 1 is an example to illustrate one form of electroless plating solution, which contains a metal ion source in which intermetallic compound crystals containing Sn, Cu, Cr, and Al are dispersed in a matrix phase containing Sn and a Sn-Cu alloy. Using raw materials with a composition of 8% by mass of Cu, 0.5% by mass of Cr, 0.2% by mass of Al, and the remainder being Sn, metal particles 1 with a diameter of approximately 3 to 50 μm were produced using the manufacturing apparatus shown in Figure 17. The following conditions were adopted at that time. A molten metal crucible was placed in the melting furnace 7, the above raw materials were placed inside, and the mixture was melted at 900°C. While maintaining that temperature, the molten metal was supplied from the nozzle 3 onto the dish-shaped rotating disc 4. As the disc-shaped rotating disc 4, a disc-shaped disc with a diameter of 35 mm and a rotating surface thickness of 3 to 5 mm was used, and the rotation speed was set to 80,000 to 100,000 revolutions per minute. Granulation chamber 1 is 9 × 10 -2 Using a vacuum chamber capable of reducing pressure to approximately Pa, the pressure is reduced, and simultaneously, nitrogen gas at 15-50°C is supplied while the chamber is evacuated, resulting in a pressure of 1 × 10⁻¹⁶ in the granulation chamber 1. -1 It was set to Pa or less. A bulk material was prepared using the obtained metal powder 1. The following conditions were adopted at that time. High-frequency induction heating: 9 × 10 -2A high-frequency induction melting crucible was placed in a vacuum chamber capable of reducing the pressure to approximately Pa. The metal particles of the present invention were introduced into the crucible, and high-frequency induction heating was performed on the metal particles of the present invention while maintaining the reduced pressure to approximately the above degree. The heating temperature was set to 900°C to melt the metal particles of the present invention, and this temperature was maintained for 5 minutes. Cooling and solidification: Next, while circulating nitrogen gas at 15-50°C into the tank for 10 minutes, the raw material was heated to approximately 400°C under atmospheric pressure, cast into a mold, and then cooled and solidified at room temperature. The obtained material was rolled into sheets, and multiple sheets were stacked to produce bulk material 1. Subsequently, bulk material 1 was heated to 150°C and crushed into small pieces, and the resulting pulverized material was placed in the plating bath described below.

[0036] Figure 1 shows a cross-sectional SEM image of bulk 1 from Example 1. Figure 1 confirms that intermetallic compound crystals (dark color) are embedded within the matrix phase (light color). Furthermore, elemental mapping analysis of one cross-section of bulk 1 using EDS (see Figure 2) revealed that its composition was Cu 6.9 mass%, Cr 0.59 mass%, Al 0.15 mass%, and the remainder being Sn. Furthermore, the composition of the matrix phase was determined by elemental mapping analysis using EDS at points 005-006 in Figures 7-8. Sn 86~90.9% by mass, Cu 2.06~4.14% by mass, Al 1.1% by mass or less The presence of Sn and Sn-Cu alloys was confirmed. Furthermore, the composition of the intermetallic compound crystal was determined by elemental mapping analysis using EDS at points 001 to 004 in Figures 3 to 6. Sn 62.69~74.72% by mass, Cu 5.35~33.17% by mass, Cr 7.8% by mass or less, Al 3.29% by mass or less, It was found that this was the case. Furthermore, intermetallic compound crystals accounted for 30-35% by mass in bulk 1.

[0037] A ceramic substrate with copper wiring, copper antennas, and copper bumps formed on it was used as the base material, and electroless plating was performed on the copper plating. The details of the electroless plating bath are as follows.

[0038] Electroless plating bath composition (concentration per liter of water): Metal ion source: Intermetallic compound crystals and matrix contained in the bulk 1. Sn concentration=10g / L Cu concentration=1g / L Cr concentration=0.1g / L Al concentration=0.1g / L

[0039] The electroless plating conditions are as follows: Plating temperature: 50℃ Plating time: 120 minutes Heat treatment temperature of the substrate after plating: 200℃ Heat treatment time for substrate after plating: 300 seconds (under nitrogen atmosphere)

[0040] The composition of the plating layer of the obtained article was the same as that of bulk material 1. The thickness of the plating layer was 5 μm.

[0041] The articles obtained in Example 1 were immersed in a 5% NaCl aqueous solution for 120 hours, and their condition was observed. The results are shown in Figure 18. Figure 18(a) shows the results of Example 1, where no corrosion was observed on the surface. Figure 18(b) shows an article with conventional Sn-Cu plating, where corrosion was observed on the surface.

[0042] Example 2 Example 2 is an example to illustrate one form of electroless plating solution containing a metal ion source in which intermetallic compound crystals containing Sn, Cu, Cr, Al, and Ni are dispersed in a matrix phase containing Sn and a Sn-Cu alloy. Using raw materials with a composition of 8% by mass of Cu, 0.5% by mass of Cr, 0.5% by mass of Al, 0.5% by mass of Ni, and the remainder being Sn, metal particles 2 with a diameter of approximately 3 to 50 μm were produced using the manufacturing apparatus shown in Figure 17. At that time, the following conditions were adopted. A melting crucible was installed in the melting furnace 7, the above raw materials were put therein, melted at 900 °C, and while maintaining that temperature, the molten metal was supplied from the nozzle 3 onto the dish-shaped rotating disk 4. As the dish-shaped rotating disk 4, a dish-shaped disk with a diameter of 35 mm and a rotating disk thickness of 3 to 5 mm was used, and it was rotated at 80,000 to 100,000 revolutions per minute. As the granulation chamber 1, after depressurizing using a vacuum chamber having a performance of depressurizing to about 9×10 -2 Pa, while supplying nitrogen gas at 15 to 50 °C and exhausting simultaneously, the atmospheric pressure in the granulation chamber 1 was set to 1×10 -1 Pa or less. Using the obtained metal powder 1, a bulk was manufactured. At that time, the following conditions were adopted. High-frequency induction heating: A high-frequency melting crucible was installed in a vacuum chamber having a performance of being able to depressurize to about 9×10 -2 Pa, the metal particles of the present invention were introduced into the crucible, high-frequency induction heating was performed on the metal particles of the present invention while maintaining the degree of depressurization to the above degree of depressurization, the heating temperature was set to 900 °C to melt the metal particles of the present invention, and that temperature was maintained for 5 minutes. Cooling and solidification: Subsequently, while flowing nitrogen gas at 15 to 50 °C into the tank for 10 minutes, the heating temperature of the raw materials was set to about 400 °C under atmospheric pressure, and casting was performed into a mold and cooled and solidified at room temperature. Using the obtained material, it was rolled into sheets, a plurality of sheets were stacked, and a bulk 2 was manufactured. Subsequently, the bulk 2 was put into a cutting machine heated to 150 °C, crushed into a size of 1 cm to 3 cm × 1 mm to 5 mm, and the obtained crushed material was placed in the following plating bath.

[0043] The cross-sectional SEM image of the bulk 2 of Example 2 obtained is shown in FIG. 9. According to FIG. 9, it was confirmed that intermetallic compound crystals (dark color) were included and present in the matrix phase (light color). Further, when elemental mapping analysis by EDS of one cross-section of the above bulk 2 was performed (see FIG. 10), it was found that its composition was 7.22 mass% of Cu, 0.54 mass% of Cr, 0.28 mass% of Al, 0.24 mass% of Ni, and the balance was Sn. Furthermore, the composition of the matrix phase was determined by elemental mapping analysis using EDS at points 005-006 in Figures 15-16. Sn 74.38% by mass ~ 85.74% by mass, Cu 4.11% by mass ~ 4.49% by mass, Al 0.78% by mass ~ 1.77% by mass, Ni 0.61% by mass to 0.86% by mass, The presence of Sn and Sn-Cu alloys was confirmed. Furthermore, the composition of the intermetallic compound crystal was determined by elemental mapping analysis using EDS at points 001 to 004 in Figures 11 to 14. Sn 30.61% by mass ~ 68.66% by mass Cu 7.48% by mass ~ 27.37% by mass Cr 15.67% by mass or less, Al 7.38% by mass or less, Ni 10.74% by mass or less, It was found that this was the case. Furthermore, intermetallic compound crystals accounted for 30-35% by mass in bulk 2.

[0044] Copper springs were used as the base material, and electroless plating was performed. Details of the electroless plating bath are as follows.

[0045] Electroless plating bath composition (concentration per liter of water): Metal ion source: Intermetallic compound crystals and matrix contained in the bulk 2. Sn concentration of plating solution = 10 g / L Cu concentration of plating solution = 1 g / L Cr concentration of plating solution = 0.1 g / L Ni concentration in plating solution = 0.1 g / L Al concentration of plating solution = 0.1 g / L

[0046] The electroless plating conditions are as follows: Plating temperature: 50℃ Plating time: 120 minutes Heat treatment temperature of the substrate after plating: 200℃ Heat treatment time for substrate after plating: 300 seconds (under nitrogen atmosphere)

[0047] The composition of the plating layer of the obtained article was the same as that of bulk material 2. The thickness of the plating layer was 5 μm.

[0048] The articles obtained in Example 2 were immersed in a 5% NaCl aqueous solution for 120 hours, and their condition was observed. The same results as in Example 1 were obtained (see Figure 18(a)).

[0049] Although the present invention has been described in detail above with reference to the attached drawings, the present invention is not limited thereto, and it will be obvious to those skilled in the art that various modifications can be conceived based on the basic technical concept and teachings. [Explanation of symbols]

[0050] 1 Granulation chamber 2 lid 3 nozzles 4. Turntable discs 5. Rotating disk support mechanism 6 Particle discharge pipe 7 Electric Furnace 8. Mixed gas tank 9 Piping 10 Piping 11 valves 12 Exhaust system 13 valves 14 Exhaust system 15 Automatic Filter 16. Particulate matter collection device

Claims

1. An electroless plating solution containing a metal ion source in which intermetallic compound crystals containing Sn, Cu, Cr, and Al are dispersed in a matrix phase containing Sn and a Sn-Cu alloy.

2. An electroless plating solution containing a metal ion source in which intermetallic compound crystals containing Sn, Cu, Cr, Al, and Ni are dispersed in a matrix phase containing Sn and a Sn-Cu alloy.

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