Tin ball and method for producing tin ball

Abstract

To provide a tin ball having a diameter larger than about 1 mm and excellent sphericity.SOLUTION: A method for manufacturing a tin ball, comprising: dropping molten metal tin into a liquid cooling medium; and forming a solid tin ball by cooling a droplet of the molten metal tin while the droplet of the molten metal tin falls in the liquid cooling medium, wherein the tin ball has a radius ranging from 1mm to 5mm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a tin ball with excellent sphericity and a method for producing the same. [Background technology]

[0002] The production of metal spheres on an industrial scale is an extremely important basic technology, and therefore, techniques for producing metal spheres on an industrial scale have been developed.

[0003] A common method for manufacturing metal balls is by mechanical processing such as pressing and polishing. However, because this involves machining, it is a method suitable for hard metal materials such as high-carbon chromium bearing steel and stainless steel. On the other hand, soft metal materials such as tin, lead, and their alloys (solder) are not suitable for mechanical processing such as polishing, so metal balls are manufactured by casting.

[0004] A classic example of the production of metal balls using soft metal materials is the production of shotgun shells. This method involves dropping molten lead from a high place (e.g., over 50 m) and collecting it in a water tank, and it was a large-scale method that required the construction of a tower for production. Of course, the lead balls obtained vary widely, and it is not a method intended to control purity or sphericity.

[0005] Patent Document 1 (JP Patent Publication No. 11-221662 A) discloses a technique for producing solder balls by dropping molten solder into soybean oil. However, Patent Document 1 does not mention the size, sphericity, or purity of the obtained solder balls, and discloses a classic technique that simply requires obtaining solder in a ball shape.

[0006] Patent Document 2 (Japanese Patent Laid-Open Publication No. 54-085171) discloses that metal spheres are obtained by spraying molten solder alloy metal from a nozzle into silicone oil while rotating a rotating plate with cutting holes. However, the size of the obtained metal spheres is 1 mm in diameter, and no technology is disclosed for obtaining metal spheres larger than this.

[0007] Patent Document 3 (Japanese Patent Laid-Open Publication No. 55-158875) discloses that iron balls are obtained by dropping droplets of molten iron into water. However, with this technique, the crack rate rises sharply when the diameter of the iron ball exceeds 1 mm, and for example, the crack rate reaches 70% when the diameter is 8 mm. Furthermore, there is no mention of the sphericity or purity of the obtained iron balls.

[0008] Patent Document 4 (JP 2001-226705 A) discloses a technique for producing minute metal spheres with a diameter of about 400 μm by ejecting molten solder into a chamber filled with nitrogen gas mixed with hydrogen gas while vibrating the molten solder with a piezoelectric element. The minute metal spheres obtained by this technique are small, about 400 μm in diameter, and there is a large variation in diameter and sphericity.

[0009] Thus, when forming particles by melting a soft metal such as tin, there has been no suitable technology to date for obtaining particles with an average particle diameter of more than 1 mm and excellent spherical shape accuracy (sphericity), and such a technology is needed. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 11-221662 [Patent Document 2] Japanese Patent Application Laid-Open No. 54-085171 [Patent Document 3] Japanese Patent Application Laid-Open No. 55-158875 [Patent Document 4] Japanese Patent Application Laid-Open No. 2001-226705 Summary of the Invention [Problem to be solved by the invention]

[0011] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a tin ball having a diameter greater than about 1 millimeter and excellent sphericity. [Means for solving the problem]

[0012] As a result of extensive research, the present inventors have found that the above object can be achieved by the means described below, and have arrived at the present invention.

[0013] Therefore, the present invention includes the following (1): (1) A method for producing tin balls, comprising the steps of: dripping the molten tin metal into a liquid cooling medium; a step in which the droplets of metallic tin are cooled as they fall through a liquid cooling medium to form solid tin spheres; A method for manufacturing a tin ball, comprising: [Effects of the Invention]

[0014] According to the present invention, high purity tin balls having a diameter of more than about 1 mm and excellent sphericity can be obtained. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is an explanatory diagram showing an outline of the manufacturing apparatus (tin ball manufacturing apparatus) used to manufacture the tin balls of Example 1. [Figure 2] FIG. 2 is an image illustrating the appearance of the tin ball (sample 1) of Example 1 obtained in Example 1. [Figure 3] FIG. 3 is an image illustrating the appearance of the tin ball of Example 2 (Sample 2) obtained in Example 2. [Figure 4] FIG. 4 is an image illustrating the appearance of the tin ball (sample 3) of Comparative Example 1 obtained in Example 3. [Figure 5] FIG. 5 is an image illustrating the appearance of the tin ball (sample 4) of Comparative Example 2 obtained in Example 4. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention will be described in detail below with reference to specific embodiments, but the present invention is not limited to the specific embodiments disclosed below.

[0017] [Manufacturing method of tin balls] The method for producing tin balls according to the present invention is as follows: A method for producing tin balls, comprising the steps of: dripping the molten tin metal into a liquid cooling medium; a step in which the droplets of metallic tin are cooled as they fall through a liquid cooling medium to form solid tin spheres; The present invention relates to a method for manufacturing a tin ball, which includes:

[0018] [Molten tin metal] Known means can be used to heat and melt metallic tin to form a molten metal of tin. For example, molten metallic tin can be prepared by heating and melting it by radiant heating or induction heating.

[0019] In a preferred embodiment, the raw material metallic tin used to prepare the molten metal of metallic tin can be any metallic tin that can be heated and melted to form a molten metal, but preferably high-purity metallic tin can be used. High-purity metallic tin that can be used as a raw material can have a tin purity of, for example, 99% by mass or more, preferably 99.9% by mass or more, preferably 99.99% by mass or more, preferably 99.995% by mass or more, preferably 99.999% by mass or more, preferably 99.9995% by mass or more, preferably 99.9995% by mass or more, preferably 99.9996% by mass or more, preferably 99.9997% by mass or more, preferably 99.9998% by mass or more, and preferably 99.9999% by mass or more.

[0020] [Liquid cooling medium] In a preferred embodiment, the liquid cooling medium that can be used is any liquid that is stable at temperatures higher than the melting point of metallic tin. More specifically, a liquid medium that does not have a boiling point or flash point at temperatures below the melting point of metallic tin can be used.

[0021] In a preferred embodiment, the boiling point of the liquid cooling medium can be, for example, 231.9° C. or higher, preferably 240° C. or higher, preferably 250° C. or higher, preferably 260° C. or higher, preferably 270° C. or higher, preferably 280° C. or higher, preferably 290° C. or higher, preferably 300° C. or higher, or preferably 310° C. In a preferred embodiment, a particularly preferred liquid cooling medium is one that has no boiling point.

[0022] In a preferred embodiment, the flash point temperature of the liquid cooling medium can be, for example, 231.9°C or higher, preferably 240°C or higher, preferably 250°C or higher, preferably 260°C or higher, preferably 270°C or higher, or preferably 280°C or higher.

[0023] In a preferred embodiment, the liquid cooling medium may be selected from the group consisting of mineral oil, vegetable oil, liquid paraffin, engine oil, and silicone oil, preferably selected from the group consisting of lubricating oil and silicone oil, and particularly preferably silicone oil.

[0024] [Drip] In a preferred embodiment, the means for introducing the molten metal tin into the liquid cooling medium is not particularly limited as long as it is dropwise, and any known means can be used, such as gravity dropwise or power dropwise, preferably natural dropwise or discharged by a pump, and particularly preferably natural dropwise due to gravity.

[0025] [Formation of solid tin balls] In a preferred embodiment, molten metal tin is dropped into a liquid cooling medium, and then cooled while falling through the liquid cooling medium to form a solid tin ball. The drop is due to gravity, and it is preferable to set the height of the liquid cooling medium so that the molten metal can fall a distance sufficient to form a solid tin ball.

[0026] [Fall distance] In a preferred embodiment, the distance that the metallic tin droplets fall in the liquid cooling medium can be, for example, 500 mm or more, preferably 600 mm or more, preferably 700 mm or more, preferably 800 mm or more, preferably 900 mm or more, or 1000 mm or more, 1100 mm or more, 1200 mm or more, 1300 mm or more, or 1400 mm or more.

[0027] In a preferred embodiment, the distance that the metallic tin droplets fall within the liquid cooling medium has no particular upper limit from the viewpoint of sufficient cooling, but can be, for example, 3000 mm or less, 2500 mm or less, 2000 mm or less, 1800 mm or less, 1600 mm or less, 1500 mm or less, or 1400 mm or less.

[0028] In a preferred embodiment, the distance that the metallic tin droplets fall within the liquid cooling medium can be, for example, in the range of 500 to 3000 mm, preferably 600 to 3000 mm, preferably 600 to 2500 mm, preferably 600 to 2000 mm, preferably 600 to 1800 mm, preferably 600 to 1600 mm, preferably 600 to 1500 mm, preferably 700 to 1500 mm, or preferably 800 to 1500 mm.

[0029] [Temperature of cooling liquid medium] In a preferred embodiment, the temperature of the liquid cooling medium at the position where the metallic tin droplets start to fall can be set to, for example, a range of 232 to 350°C, preferably a range of 232 to 330°C, or a range of 232 to 310°C, preferably a range of 232 to 290°C.

[0030] In a preferred embodiment, the temperature of the cooling liquid medium at the position where the falling of the metallic tin droplets ends can be, for example, 100°C or less, preferably 80°C or less, preferably 50°C or less, and can be, for example, in the range of 100 to -20°C, or 80 to -20°C, preferably 60 to -20°C, or 50 to 0°C, preferably 40 to 0°C, preferably 40 to 10°C, preferably 40 to 15°C, preferably 40 to 20°C.

[0031] In a preferred embodiment, the temperature of the cooling liquid medium at the position where the falling of the metallic tin droplets ends can be a temperature near the room temperature of the location where the manufacturing apparatus is installed, for example, within a range of +30°C to -30°C from the room temperature of the location where the manufacturing apparatus is installed, preferably within a range of +20°C to -20°C, and preferably within a range of +10°C to -10°C. In a preferred embodiment, the room temperature of the location where the manufacturing apparatus is installed can be, for example, -10 to 40°C, alternatively 0 to 35°C, alternatively 5 to 35°C, alternatively 10 to 35°C, alternatively 15 to 35°C, alternatively 20 to 35°C, or alternatively 20 to 30°C.

[0032] [Tin ball] According to the present invention, high-purity tin metal spheres having a diameter of more than about 1 mm and excellent sphericity can be produced. The present invention also relates to high-purity tin metal spheres produced by the above-mentioned production method. "Excellent sphericity" means that the diameter variation ratio, which will be described later, is smaller than the value described later, and preferably equal to or less than the value described later.

[0033] [Tin ball diameter] In a preferred embodiment, the diameter of the metallic tin ball of the present invention can be greater than about 1 millimeter. The diameter of the metallic tin ball can be measured by the means described later in the Examples. For a particular tin ball to be measured, 10 diameter measurement points are selected and measured, and the measured values ​​at these 10 points are averaged to calculate the average diameter of the individual tin ball to be measured.

[0034] In a preferred embodiment, the diameter of the metal tin ball of the present invention can be, for example, 1 mm to 5 mm, preferably 1 mm to 4.5 mm, preferably 1 mm to 4.3 mm, or 1 mm to 4.2 mm, 1 mm to 4.1 mm, 1 mm to 4.0 mm, 1 mm to 3.9 mm, 1 mm to 3.8 mm, 1 mm to 3.7 mm, 1 mm to 3.6 mm, or 1 mm to 3.5 mm.

[0035] In a preferred embodiment, the diameter of the metal tin ball of the present invention can be, for example, 1.1 mm to 5 mm, 1.2 mm to 5 mm, 1.3 mm to 5 mm, or 1.4 mm to 5 mm.

[0036] In a preferred embodiment, the diameter of the metal tin ball of the present invention can be, for example, 1.5 mm to 5 mm, preferably 1.5 mm to 4.5 mm, preferably 1.5 mm to 4.3 mm, or 1.5 mm to 4.2 mm, 1.5 mm to 4.1 mm, 1.5 mm to 4.0 mm, 1.5 mm to 3.9 mm, 1.5 mm to 3.8 mm, 1.5 mm to 3.7 mm, 1.5 mm to 3.6 mm, or 1.5 mm to 3.5 mm.

[0037] In a preferred embodiment, the diameter of the metal tin ball of the present invention can be, for example, 1.6 mm to 5 mm, or 1.7 mm to 5 mm.

[0038] In a preferred embodiment, the diameter of the metal tin ball of the present invention can be, for example, 1.8mm to 5mm, preferably 1.8mm to 4.5mm, preferably 1.8mm to 4.3mm, or 1.8mm to 4.2mm, 1.8mm to 4.1mm, 1.8mm to 4.0mm, 1.8mm to 3.9mm, 1.8mm to 3.8mm, 1.8mm to 3.7mm, 1.8mm to 3.6mm, or 1.8mm to 3.5mm.

[0039] In a preferred embodiment, the diameter of the metal tin ball of the present invention can be, for example, 1.9mm to 5mm, preferably 1.9mm to 4.5mm, preferably 1.9mm to 4.3mm, or 1.9mm to 4.2mm, 1.9mm to 4.1mm, 1.9mm to 4.0mm, 1.9mm to 3.9mm, 1.9mm to 3.8mm, 1.9mm to 3.7mm, 1.9mm to 3.6mm, or 1.9mm to 3.5mm.

[0040] In a preferred embodiment, the diameter of the metal tin ball of the present invention can be, for example, 2.0 mm to 5 mm, preferably 2.0 mm to 4.5 mm, preferably 2.0 mm to 4.3 mm, or 2.0 mm to 4.2 mm, 2.0 mm to 4.1 mm, 2.0 mm to 4.0 mm, 2.0 mm to 3.9 mm, 2.0 mm to 3.8 mm, 2.0 mm to 3.7 mm, 2.0 mm to 3.6 mm, or 2.0 mm to 3.5 mm.

[0041] In a preferred embodiment, the diameter of the metal tin ball of the present invention can be, for example, 2.1 mm to 5 mm, preferably 2.1 mm to 4.5 mm, preferably 2.1 mm to 4.3 mm, or 2.1 mm to 4.2 mm, 2.1 mm to 4.1 mm, 2.1 mm to 4.0 mm, 2.1 mm to 3.9 mm, 2.1 mm to 3.8 mm, 2.1 mm to 3.7 mm, 2.1 mm to 3.6 mm, or 2.1 mm to 3.5 mm.

[0042] In a preferred embodiment, the diameter of the metal tin ball of the present invention can be, for example, 2.2 mm to 5 mm, preferably 2.2 mm to 4.5 mm, preferably 2.2 mm to 4.3 mm, or 2.2 mm to 4.2 mm, 2.2 mm to 4.1 mm, 2.2 mm to 4.0 mm, 2.2 mm to 3.9 mm, 2.2 mm to 3.8 mm, 2.2 mm to 3.7 mm, 2.2 mm to 3.6 mm, or 2.2 mm to 3.5 mm.

[0043] In a preferred embodiment, the diameter of the metal tin ball of the present invention can be, for example, 2.3 mm to 5 mm, preferably 2.3 mm to 4.5 mm, preferably 2.3 mm to 4.3 mm, or 2.3 mm to 4.2 mm, 2.3 mm to 4.1 mm, 2.3 mm to 4.0 mm, 2.3 mm to 3.9 mm, 2.3 mm to 3.8 mm, 2.3 mm to 3.7 mm, 2.3 mm to 3.6 mm, or 2.3 mm to 3.5 mm.

[0044] In a preferred embodiment, the diameter of the metal tin ball of the present invention can be, for example, 2.4 mm to 5 mm, preferably 2.4 mm to 4.5 mm, preferably 2.4 mm to 4.3 mm, or 2.4 mm to 4.2 mm, 2.4 mm to 4.1 mm, 2.4 mm to 4.0 mm, 2.4 mm to 3.9 mm, 2.4 mm to 3.8 mm, 2.4 mm to 3.7 mm, 2.4 mm to 3.6 mm, or 2.4 mm to 3.5 mm.

[0045] In a preferred embodiment, the diameter of the metal tin ball of the present invention can be, for example, 2.6 mm to 5 mm, preferably 2.6 mm to 4.5 mm, preferably 2.6 mm to 4.3 mm, or 2.6 mm to 4.2 mm, 2.6 mm to 4.1 mm, 2.6 mm to 4.0 mm, 2.6 mm to 3.9 mm, 2.6 mm to 3.8 mm, 2.6 mm to 3.7 mm, 2.6 mm to 3.6 mm, or 2.6 mm to 3.5 mm.

[0046] In a preferred embodiment, the diameter of the metal tin ball of the present invention can be, for example, 2.8 mm to 5 mm, preferably 2.8 mm to 4.5 mm, preferably 2.8 mm to 4.3 mm, or 2.8 mm to 4.2 mm, 2.8 mm to 4.1 mm, 2.8 mm to 4.0 mm, 2.8 mm to 3.9 mm, 2.8 mm to 3.8 mm, 2.8 mm to 3.7 mm, 2.8 mm to 3.6 mm, or 2.8 mm to 3.5 mm.

[0047] In a preferred embodiment, the diameter of the metal tin ball of the present invention can be, for example, 2.9 mm to 5 mm, preferably 2.9 mm to 4.5 mm, preferably 2.9 mm to 4.3 mm, or 2.9 mm to 4.2 mm, 2.9 mm to 4.1 mm, 2.9 mm to 4.0 mm, 2.9 mm to 3.9 mm, 2.9 mm to 3.8 mm, 2.9 mm to 3.7 mm, 2.9 mm to 3.6 mm, or 2.9 mm to 3.5 mm.

[0048] In a preferred embodiment, the diameter of the metal tin ball of the present invention can be, for example, 3.0 mm to 5 mm, preferably 3.0 mm to 4.5 mm, preferably 3.0 mm to 4.3 mm, or 3.0 mm to 4.2 mm, 3.0 mm to 4.1 mm, 3.0 mm to 4.0 mm, 3.0 mm to 3.9 mm, 3.0 mm to 3.8 mm, 3.0 mm to 3.7 mm, 3.0 mm to 3.6 mm, or 3.0 mm to 3.5 mm.

[0049] In a preferred embodiment, the diameter of the metal tin ball of the present invention can be, for example, 3.1 mm to 5 mm, preferably 3.1 mm to 4.5 mm, preferably 3.1 mm to 4.3 mm, or 3.1 mm to 4.2 mm, 3.1 mm to 4.1 mm, 3.1 mm to 4.0 mm, 3.1 mm to 3.9 mm, 3.1 mm to 3.8 mm, 3.1 mm to 3.7 mm, 3.1 mm to 3.6 mm, or 3.1 mm to 3.5 mm.

[0050] In a preferred embodiment, the diameter of the metal tin ball of the present invention can be, for example, 3.2 mm to 5 mm, preferably 3.2 mm to 4.5 mm, preferably 3.2 mm to 4.3 mm, or 3.2 mm to 4.2 mm, 3.2 mm to 4.1 mm, 3.2 mm to 4.0 mm, 3.2 mm to 3.9 mm, 3.2 mm to 3.8 mm, 3.2 mm to 3.7 mm, 3.2 mm to 3.6 mm, or 3.2 mm to 3.5 mm.

[0051] In a preferred embodiment, the diameter of the metal tin ball of the present invention can be, for example, 3.3 mm to 5 mm, 3.4 mm to 5 mm, 3.5 mm to 5 mm, 3.6 mm to 5 mm, 3.7 mm to 5 mm, 3.8 mm to 5 mm, or 3.9 mm to 5 mm.

[0052] [Diameter disparity] In a preferred embodiment, the tin ball of the present invention can have a diameter variation ratio calculated by the following formula of, for example, 0.15 or less: "Diameter variation ratio" = "Diameter variation (mm) measured in accordance with the JIS B1509:2009 standard" / "Average diameter (mm)"

[0053] The diameter variation (mm) and average diameter (mm) of the tin balls in the present invention can be measured in accordance with the provisions of JIS B1509:2009 by the means disclosed in the examples described below.

[0054] In a preferred embodiment, the diameter variation ratio of the tin ball of the present invention can be, for example, 0.15 or less, or 0.14 or less, 0.13 or less, 0.12 or less, 0.11 or less, 0.10 or less, 0.09 or less, 0.08 or less, 0.07 or less, 0.06 or less, 0.05 or less, or 0.04 or less. There is no lower limit to the preferred diameter variation ratio value, but it can be, for example, 0.001 or more, 0.005 or more, 0.01 or more, 0.02 or more, or 0.03 or more.

[0055] [Purity of tin balls] In a preferred embodiment, the purity of the metallic tin in the tin balls can be, for example, 99.99% by mass or more, preferably 99.995% by mass or more, preferably 99.999% by mass or more, preferably 99.9995% by mass or more, preferably 99.9995% by mass or more, preferably 99.9996% by mass or more, preferably 99.9997% by mass or more, preferably 99.9998% by mass or more, preferably 99.9999% by mass or more.

[0056] [Preferred embodiment of the present invention] As a preferred embodiment, the present invention includes the following (1) and the following. (1) A method for producing tin balls, comprising the steps of: dripping the molten tin metal into a liquid cooling medium; a step in which the droplets of metallic tin are cooled as they fall through a liquid cooling medium to form solid tin spheres; A method for manufacturing a tin ball, comprising: (2) The manufacturing method according to (1), wherein the liquid medium for cooling is a liquid medium that has neither a boiling point nor a flash point at a temperature below the melting point of metallic tin. (3) The manufacturing method according to (1), wherein the liquid cooling medium is selected from the group consisting of mineral oil, vegetable oil, liquid paraffin, engine oil, and silicone oil. (4) The manufacturing method according to (1), wherein the distance that the metallic tin droplets fall in the liquid cooling medium is 500 mm or more. (5) The manufacturing method according to (1), wherein the temperature of the liquid cooling medium is in the range of 232 to 350°C at the position where the falling of the metallic tin droplets starts, and is in the range of 100°C or less at the position where the falling of the tin droplets ends. (6) The manufacturing method according to any one of (1) to (5), wherein the diameter of the tin ball is in the range of 1 mm to 5 mm. (7) The manufacturing method according to any one of (1) to (5), wherein the diameter variation ratio of the tin balls calculated by the following formula is 0.15 or less: "Diameter variation ratio" = "Diameter variation (mm) measured in accordance with the provisions of JIS B1509:2009" / "Average diameter value (mm)". (8) The manufacturing method according to any one of (1) to (5), wherein the purity of the metallic tin in the tin balls is 99.999% by mass or more. (9) Tin balls with diameters ranging from 1mm to 5mm. (10) The tin balls according to (9) have a diameter variation ratio of 0.15 or less, calculated by the following formula: "Diameter variation ratio" = "Diameter variation (mm) measured in accordance with the provisions of JIS B1509:2009" / "Average diameter value (mm)". (11) The tin ball according to (9), wherein the purity of the metallic tin in the tin ball is 99.999% by mass or more. [Example]

[0057] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the examples illustrated below.

[0058] [Example 1: Production of tin balls (Example 1)] [Tin ball manufacturing equipment] As the raw material tin, high-purity metallic tin with a purity of 99.999% by mass was prepared. The tin balls of Example 1 were manufactured using this high-purity metallic tin (purity 99.999% by mass) as a raw material. FIG. 1 is an explanatory diagram showing an outline of the manufacturing apparatus (tin ball manufacturing apparatus) used to manufacture the tin balls of Example 1.

[0059] The tin ball manufacturing apparatus shown in Figure 1 is equipped with a melting vessel 14 for melting and storing tin, the raw material used to manufacture tin balls. The tin in the melting vessel 14 is heated and melted by a heater 15. The molten tin in the melting vessel 14 drips under its own weight through a tin delivery pipe 16 into the silicone oil filled in the granulation vessel 12. A heater 13 is installed above the granulation vessel 12, and the molten tin is maintained in a molten state above the granulation vessel 12. The space within the manufacturing apparatus is filled with argon gas rather than air, preventing oxidation of the molten tin. The molten tin droplets introduced through the tin delivery pipe 16 and dropped into the silicone oil filled in the granulation vessel 12 become spherical as they freely fall through the silicone oil filled in the granulation vessel 12, then cool and solidify, becoming tin balls 11 that accumulate at the bottom of the granulation vessel 12.

[0060] [Procedure for manufacturing tin balls using tin ball manufacturing equipment] Using high-purity tin (purity 99.999% by mass), tin balls were manufactured using a tin ball manufacturing apparatus as follows.

[0061] 2,000 g of small pieces of high-purity tin (purity 99.999% by mass) that had been pickled and washed with water were placed in the melting vessel of a quartz tin sphere manufacturing device. Meanwhile, the granulation vessel was filled with silicone oil (Shin-Etsu Silicone Co., Ltd.: KF-96, boiling point: no boiling point, flash point: 300°C or higher). The lids of the melting vessel and granulation vessel were closed, and high-purity argon gas was allowed to flow at a flow rate of 1 L / min until the oxygen concentration inside the granulation vessel fell to 0.1 vol% or less.

[0062] The melting vessel was heated with an external heater to 280°C, exceeding the melting point of tin, 231.9°C. The upper part of the granulation vessel was heated to 280°C, exceeding the melting point of tin, 231.9°C. The lower part of the granulation vessel was not heated and was maintained at approximately 20°C, which was the room temperature during the experiment.

[0063] High-purity tin was melted in the melting vessel, and the molten tin was discharged from the melting vessel into the granulating vessel by its own weight, and allowed to drip and fall freely. During this free-fall process, the molten tin became spherical due to surface tension. Since the lower part of the granulating vessel was not heated, the molten tin solidified and accumulated while remaining spherical.

[0064] After the discharge was completed, the heater was turned off, the mixture was allowed to cool, the flow of argon gas was stopped, and the tin ball was removed.

[0065] The removed tin ball was washed with toluene to remove the silicone oil, and then washed with dilute hydrochloric acid to obtain a tin ball (sample 1) produced in Example 1.

[0066] From the tin balls (sample 1) produced in Example 1, tin balls to be measured were randomly selected, and impurity analysis was performed using a GD-MS (AstruM manufactured by Nu Corporation) with a resolution of 4000 or higher. The tin purity was calculated by the difference method and was found to be 99.999 mass% or higher.

[0067] [Example 2: Production of tin balls (Example 2)] As the raw material tin, high-purity metallic tin with a purity of 99.9999% by mass was prepared. This high-purity metallic tin (purity 99.9999% by mass) was used as a raw material to manufacture tin balls using the above-mentioned tin ball manufacturing apparatus in the same manner as in the manufacture of tin balls in Example 1. In this way, tin balls (sample 2) manufactured according to Example 2 were obtained.

[0068] From the tin balls (sample 2) produced in Example 2, tin balls to be measured were randomly selected, and impurity analysis was performed in the same manner as the impurity analysis and calculation of tin purity for the tin balls in Example 1, and the tin purity was calculated to be 99.9999 mass% or more.

[0069] [Example 3: Production of tin balls (Comparative Example 1)] [Procedure for manufacturing tin balls using tin ball manufacturing equipment] Tin balls were produced by the tin ball production apparatus used in Example 1 using high-purity tin (purity 99.999% by mass).

[0070] However, while silicone oil was used as the cooling liquid medium in the production of tin balls in Example 1, pure water was used as the cooling liquid medium instead of silicone oil in the production of tin balls in Example 3.

[0071] The melting vessel was heated with an external heater to 280°C, exceeding the melting point of tin, which is 231.9°C. The upper part of the granulation vessel was heated to 85°C. The lower part of the granulation vessel was not heated and was maintained at approximately 20°C, which was the room temperature during the experiment.

[0072] Thus, tin balls were produced and removed in the same manner as in Example 1, except that pure water was used as the cooling liquid medium and the temperature of the granulation vessel was controlled.

[0073] The removed tin ball was washed with dilute hydrochloric acid to obtain the tin ball produced in Example 3 (Sample 3).

[0074] [Example 4: Production of tin balls (Comparative Example 2)] [Procedure for manufacturing tin balls using tin ball manufacturing equipment] Tin balls were produced by the tin ball production apparatus used in Example 1 using high-purity tin (purity 99.999% by mass).

[0075] However, while silicone oil was used as the cooling liquid medium in the production of tin balls in Example 1, ethanol was used as the cooling liquid medium instead of silicone oil in the production of tin balls in Example 4.

[0076] The melting vessel was heated with an external heater to 280°C, exceeding the melting point of tin, which is 231.9°C. The upper part of the granulation vessel was not heated, but was maintained by heat transferred from the melting vessel. The lower part of the granulation vessel was not heated, but was maintained at approximately 20°C, the room temperature during the experiment.

[0077] Thus, tin balls were produced and removed in the same manner as in Example 1, except that ethanol was used as the cooling liquid medium and the temperature of the granulation vessel was controlled.

[0078] The removed tin ball was washed with dilute hydrochloric acid to obtain the tin ball produced in Example 4 (Sample 4).

[0079] [Example 5: Evaluation of tin balls] The tin ball of Example 1 (Sample 1) obtained in Example 1, the tin ball of Example 2 (Sample 2) obtained in Example 2, the tin ball of Comparative Example 1 (Sample 3) obtained in Example 3, and the tin ball of Comparative Example 2 (Sample 4) obtained in Example 4 were each evaluated using the following procedure.

[0080] [Evaluation of the tin balls of Example 1 obtained in Example 1] The evaluation of the tin balls of Example 1 (Sample 1) obtained in Example 1 was carried out by randomly selecting five tin balls to be measured from the group of tin balls obtained as the tin balls of Example 1 (Sample 1) obtained in Example 1 and measuring them.

[0081] Specifically, the measurement was carried out for each of the tin balls (measurement objects 1 to 5) to be measured, in accordance with the provisions of JIS B1509:2009, using a micrometer instead of a measurement plane and a probe perpendicular to it, and measuring 10 times for each ball while changing the measurement point, and the maximum and minimum values ​​were identified from the 10 measured values, and the diameter variation was calculated as the difference between the maximum and minimum values. In the present invention, the arithmetic mean value of the 10 measured values ​​measured for each ball was taken as the average diameter value of each ball, and the diameter variation ratio was calculated as the ratio of the diameter variation to the average diameter value.

[0082] The results obtained are summarized in Table 1 below.

[0083] [Table 1]

[0084] The diameter variation ratio of all of the tin balls measured in Example 1 was 0.14 or less, indicating excellent sphericity. Furthermore, one of the tin balls measured in Example 1 had a diameter variation ratio of 0.04 or less, indicating excellent sphericity. The average diameter variation ratio of the tin balls in Example 1 in Table 1 was 0.0987, indicating excellent sphericity.

[0085] An image illustrating the appearance of the tin ball of Example 1 (Sample 1) obtained in Example 1 is shown in FIG.

[0086] [Evaluation of the tin balls of Example 2 obtained in Example 2] The evaluation of the tin balls of Example 2 (Sample 2) obtained in Example 2 was carried out by randomly selecting five tin balls to be measured from the group of tin balls obtained as the tin balls of Example 2 (Sample 2) obtained in Example 2. The evaluation of the tin balls of Example 2 (Sample 2) obtained in Example 2 was carried out in the same manner as the operation performed on the tin balls of Example 1 (Sample 1) obtained in Example 1.

[0087] The results obtained are summarized in Table 2 below.

[0088] [Table 2]

[0089] The diameter variation ratio of the tin balls measured in Example 2 was 0.14 or less for all of the tin balls measured, indicating excellent sphericity. Furthermore, the diameter variation ratio of two of the tin balls measured in Example 2 was 0.04 or less, indicating excellent sphericity. The average diameter variation ratio of the tin balls measured in Example 2 in Table 2 was 0.0828, indicating excellent sphericity.

[0090] An image illustrating the appearance of the tin ball of Example 2 (Sample 2) obtained in Example 2 is shown in FIG.

[0091] [Evaluation of the tin balls of Comparative Example 1 obtained in Example 3] In order to evaluate the tin balls of Comparative Example 1 (Sample 3) obtained in Example 3, we attempted to randomly extract five tin balls to be measured from the group of tin balls obtained as tin balls of Comparative Example 1 (Sample 3) obtained in Example 3. However, the tin balls of Comparative Example 1 (Sample 3) obtained in Example 3 contained many irregularly shaped metallic tin balls, and it was not possible to extract such balls to be measured.

[0092] An image illustrating the appearance of the tin ball (sample 3) of Comparative Example 1 obtained in Example 3 is shown in FIG.

[0093] [Evaluation of the tin balls of Comparative Example 2 obtained in Example 4] In order to evaluate the tin balls of Comparative Example 2 (Sample 4) obtained in Example 4, we attempted to randomly extract five tin balls to be measured from the group of tin balls obtained as tin balls of Comparative Example 2 (Sample 4) obtained in Example 4.However, the tin balls of Comparative Example 2 (Sample 4) obtained in Example 4 contained many metallic tin balls that had become irregular in shape, and it was not possible to extract such balls to be measured.

[0094] An image illustrating the appearance of the tin ball (sample 4) of Comparative Example 2 obtained in Example 4 is shown in FIG.

[0095] [Evaluation of tin balls in Examples and Comparative Examples] For example, water is an excellent cooling solvent, often used to cool objects at temperatures exceeding 100°C. Ethanol is also used as an excellent cooling solvent. It is unclear why such a large difference occurs between excellent cooling solvents such as water and ethanol and silicone oil. However, in the present invention, which aims to form tin spheres from molten tin, the inventor believes that simple cooling is insufficient, and that the very tiny bubbles that occur during cooling, or the phenomenon of localized tiny bubbles themselves, may hinder the formation of tin spheres with excellent sphericity. In other words, the inventor believes that the fact that silicone oil, in relation to its boiling point, does not cause the phenomenon of localized tiny bubbles to occur, may have made it possible to form tin spheres with excellent sphericity.

[0096] [Potential contribution to SDGs] According to one embodiment of the present invention, tin balls with large diameters and excellent sphericity are provided. Because high-precision materials and components are important for the development of IoT and AI technologies, one embodiment of the present invention may contribute to the development of IoT and AI technologies. Therefore, one embodiment of the present invention may contribute to Goal 9 of the United Nations-led Sustainable Development Goals (SDGs), which is to "Build resilient infrastructure, promote inclusive and sustainable industrialization, and foster innovation." [Industrial Applicability]

[0097] The present invention provides a tin ball with a large diameter and excellent sphericity, and is an industrially useful invention.

Claims

1. A method for producing tin balls, comprising the steps of: dripping the molten tin metal into a liquid cooling medium; a step in which the droplets of metallic tin are cooled as they fall through a liquid cooling medium to form solid tin spheres; A method for manufacturing a tin ball, comprising:

2. 2. The method according to claim 1, wherein the cooling liquid medium is a liquid medium that has neither a boiling point nor a flash point at a temperature below the melting point of metallic tin.

3. 2. The method according to claim 1, wherein the cooling liquid medium is selected from the group consisting of mineral oil, vegetable oil, liquid paraffin, engine oil, and silicone oil.

4. 2. The method according to claim 1, wherein the distance that the metallic tin droplets fall in the cooling liquid medium is 500 mm or more.

5. 2. The manufacturing method according to claim 1, wherein the temperature of the cooling liquid medium is in the range of 232 to 350°C at the position where the falling of the metallic tin droplets starts, and is in the range of 100°C or less at the position where the falling of the tin droplets ends.

6. The manufacturing method according to any one of claims 1 to 5, wherein the diameter of the tin ball is in the range of 1 mm to 5 mm.

7. The manufacturing method according to any one of claims 1 to 5, wherein the diameter variation ratio of the tin balls calculated by the following formula is 0.15 or less: "Diameter variation ratio" = "Diameter variation (mm) measured in accordance with the provisions of JIS B1509:2009" / "Average diameter (mm)".

8. The manufacturing method according to any one of claims 1 to 5, wherein the purity of the metallic tin in the tin ball is 99.999% by mass or more.

9. A tin ball with a diameter ranging from 1mm to 5mm.

10. The tin ball according to claim 9, wherein the diameter variation ratio of the tin ball calculated by the following formula is 0.15 or less: "Diameter variation ratio" = "Diameter variation (mm) measured in accordance with the provisions of JIS B1509:2009" / "Average diameter (mm)".

11. The tin ball according to claim 9, wherein the purity of the metallic tin in the tin ball is 99.999% by mass or more.

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