JPH04354808A - Production of metallic microbead - Google Patents

Abstract

PURPOSE:To efficiently obtain metallic microbeads of an extremely small volume with good dimensional precision by chemically etching the microbeads obtained by melting the cut fine pieces of a metallic thin wire. CONSTITUTION:The thin wire (e.g. 0.15mm in diameter) of a metal (e.g. Ag-Cu alloy) is cut to a requisite length (e.g. 0.23mm) to obtain the cut fine pieces. The pieces are melted to obtain the microbeads (e.g. 0.20mm in length and 40mug in weight). The microbeads are then dipped in a liq. etchant (e.g. cyanide soln.) and etched to obtain the metallic microbeads of requisite size (e.g. 0.16mm in diameter and 21mug in weight).

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a method for producing microscopic metal spheres, and more particularly to a method for producing microscopic metallic spheres suitable for producing brazing material for microspherical microspheres used in the production of lead pins with brazing material for ICs. .

0002

[Prior Art] Conventionally, in order to manufacture microspherical brazing material used in the production of lead pins with brazing material for ICs, the following steps were taken: How to melt and make microspheres. ■A by atomization method
g. A method of making brazing filler metal granules and classifying these granules into the required particle size. ■Method of making microspheres by melting Ag wax powder. and so on. By the way, method (2) above is technically difficult when the Ag wax volume is small (30 μg or less). This is because the diameter of the Ag brazing wire is small and the cutting dimension is short, so there is a mechanical limit to cutting. In addition, method (2) has a poor yield, is uneconomical, and has irregular shapes. Furthermore, in method (2), since the grain size of the Ag solder powder is not constant, the volume is not constant and the dimensional accuracy is poor. On the other hand, with the recent miniaturization of IC lead pins, the current situation is that the Ag solder used for manufacturing lead pins with solder metal is also required to have a very small volume.

0003

[Problems to be Solved by the Invention] Therefore, the present invention solves the problem of Ag
The object of the present invention is to provide a method for producing metal microspheres that can accurately and efficiently produce microspheres with extremely small wax volumes.

0004

[Means for Solving the Problems] In order to solve the above-mentioned problems, the method for producing metal microspheres of the present invention involves cutting a thin metal wire to a required length to obtain micropieces, and then cutting the microspheres into It is characterized by melting to form microspheres and then chemically etching the microspheres to form microspheres.

[0005]

[Function] As described above, the method for producing metal microspheres of the present invention involves chemically etching the microspheres after they are made, so that the outer surface of the microspheres is uniformly etched, resulting in highly dimensionally accurate metal microspheres. can be obtained efficiently.

[0006]

[Embodiment] An embodiment of the method for producing metal microspheres of the present invention will be described with reference to the case where a brazing material for microspheres used in manufacturing lead pins with brazing material for IC is produced. A thin wire 1 made of 28% Ag-Cu with a wire diameter of 0.15 mm shown in Fig. 1 is
．． The fine pieces 2 shown in FIG. 2 were cut into pieces of 23 mm, and the fine pieces 2 were placed in a jig (not shown) and melted at 850°C in an electric furnace to obtain the ball diameter of 0.0 mm as shown in FIG. 20mm, 4
0 μg microspheres 3 were prepared, and then, as shown in FIG. 4, the microspheres 3 were immersed in a cyan-based etching solution 4 at room temperature for 12 minutes to be etched, resulting in a ball diameter of 0.16 mm as shown in FIG.
, 21 μg of microspheres 5 were obtained. When we measured the volume and sphericity of 100 microspheres 5 out of 100,000 thus obtained, we found that the volume was 21±2 μg, and it was 0.16±0.
．． The sphericity was 0.004, and the dimensional accuracy was high. In addition, this microscopic sphere 5 could be melted and attached to the tip (head) of a rivet-shaped lead pin with a head diameter of 0.18 mm and a total length of 1.0 mm, making it possible to obtain a small-sized brazed lead pin. In addition, although the above example deals with making a brazing material of microscopic spheres, the invention is not limited to this, and microscopic spheres for ornaments made of precious metals may also be produced.In short, microspheres are made into microscopic particles by chemical etching. The material does not matter as long as it can be made into small balls.

[0007]

Effects of the Invention As described above, according to the method for producing metal microspheres of the present invention, metal microspheres with very small volumes for use as brazing filler metals, ornaments, and other applications can be produced with high dimensional accuracy and efficiency. It can be easily manufactured, and in particular, by manufacturing microscopic spheres of Ag solder, it can contribute to the manufacture of small lead pins with solder metal. Further, in the method for producing metal microspheres of the present invention, microspheres of a desired size can be freely produced by appropriately selecting the concentration of the chemical etching solution and the time.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the steps of an embodiment of the method for producing metal microspheres of the present invention.

FIG. 2 is a diagram showing the steps of an embodiment of the method for producing metal microspheres of the present invention.

FIG. 3 is a diagram showing steps of an embodiment of the method for producing metal microspheres of the present invention.

FIG. 4 is a diagram showing the steps of an embodiment of the method for producing metal microspheres of the present invention.

FIG. 5 is a diagram showing the steps of an embodiment of the method for producing metal microspheres of the present invention.

[Explanation of symbols]

1 Thin line 2. Microscopic pieces 3 Microspheres 4 Cyan-based etching liquid 5 Microscopic sphere

Claims (1)

[Claims] Claim 1: A fine metal wire is cut to a required length to obtain minute pieces, then the minute pieces are melted to make microspheres, and then the microspheres are chemically etched to become microspheres. A method for producing metal microspheres, characterized by: