Metal founding – Means to shape metallic material
Patent
1997-01-24
1998-07-14
Lin, Kuang Y.
Metal founding
Means to shape metallic material
164129, 264 13, 425 6, B29B 910
Patent
active
057789649
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a solid spherical body manufacturing apparatus for manufacturing solid spherical solder alloy or the like.
BACKGROUND TECHNOLOGY
In a conventional soldering process for a printed-circuit board, the printed-circuit board with chips mounted on it by using solder paste is mounted in a reflow soldering furnace in general. In this conventional process, however, it is difficult to make the interval of lead terminals in the electronic circuit on the printed-circuit board less than 0.5 mm. On the other hand, the junction by BGA (Ball Grid Array) method has been popular of late. For this reason, Sn-Pb solder alloy spherical bodies are in great demand. At Present, a manufacturer of such spherical bodies expects the sale of a million spherical bodies per a unit of mass production. These spherical bodies are manufactured by using a spray process in which they are manufactured from molten solder alloy through quenching or a centrifugal process.
In the conventional manufacturing process described above, however, the disunity of the diameter of the solder spherical body is unavoidable and it is extremely difficult to sift relatively uniform spherical bodies from all with high accuracy, for example with sphericity of .+-.0.02 mm resulting in a problem of high cost.
Thus the purpose of the present invention is to propose a solid spherical body manufacturing apparatus which can manufacture spherical bodies such as solder spherical bodies with high sphericity and high dimensional accuracy and enables the omission of solid spherical body sifting process.
DISCLOSURE OF THE INVENTION
The solid spherical body manufacturing apparatus according to the present invention is characterized in that it consists of a flat plate in which plurality of holes penetrate said flat plate and open at its upper and lower surfaces, said upper surface being made of material which is not easily wetted by molten or semimolten substance, a space which is to be filled with said molten or semi-molten substance, a cylinder which is connected with said space, a piston which can elevate within said cylinder pressing said substance upwards and ejecting it at said upper surface of said flat plate through said plurality of holes, and a driving device which can move said piston up and down and in that spherical bodies of said substance are manufactured by the action of the surface tension of said substance. Furthermore, the solid spherical body manufacturing apparatus according to the present invention may include a heating device for heating said ejected substance or metal paste by heating said flat plate, and as an alternative to this may include another type of heating device for heating the environment around said ejected substance or metal paste up to the temperature at which the surface tension of said ejected substance or metal paste can act to make it spherical.
According to the present invention, a piston can elevate within the cylinder pressing molten or semimolten substance upwards in said space and ejecting it at the upper surface through the plurality of holes. As the flat plate is made of material which is not easily wetted by said substance or metal paste, that is, as the contact angle constituted therebetween is big, in case the surface tension of the ejected substance or metal paste is big enough, spherical bodies can be manufactured, but in case the surface tension is not big enough, spherical bodies cannot be manufactured easily.
In case this ejected substance or metal paste forms a cylindrical shape, it can be transformed in a sphere by the exertion of surface tension growing through heating.
Particularly in case metal paste is used, solvent is evaporated by heating.
According to the manufacturing processes described above, as the unit weight of molten or semimolten substance or metal paste can be controlled with extreme accuracy, solid spherical bodies of solder alloy can be manufactured with high sphericity and high dimensional accuracy after cooling, resulting in the omission of a s
Kawaguchi Toranosuke
Maezono Akikazu
Lin Kuang Y.
Nihon Almit Co., Ltd.
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