DE1521894A1 - Process for the production of spherical bodies, preferably made of aluminum - Google Patents

Description

Dipl.-Ing. ERICHE. WALTHER

Patent attorney

Applicant: iM. V. PHILIPS 'GLQEILAMPENFARRIEKEN AWe ₈ PH 18,675

14 _# October 1963

Dr. Expl.

H "Y. H.ilips.aioeila.penfabrieken, Eindhoven / Holland

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Body made of hetall-n or

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9844/1647

^BAD OR'GINAL

to apply the pad and due to the surface tension to allow spherical bodies to contract. This procedure is unsuccessful when applied to aluminum, because the natural oxide skin prevents the free effect of surface tension

The invention, which aims, among other things, to overcome these disadvantages to avoid is that a number of out-of-round bodies made of metal covered with an oxide skin, e.g. aluminum, heated on a solid surface to above their melting point and only briefly a gaseous one Etching agent for the oxide skin is supplied, so that at least the connection between the oxide skin and the body is canceled take on a circular shape under the action of surface tension, whereupon they are cooled "

The oxyrl skin is generally of natural origin be.

In this process, a disadvantage of the oxide skin is eliminated, but the presence of this skin remains Advantage that it prevents the bodies from melting together to a great extent.

Hydrochloric acid gas is preferably used as the etchant.

The invention is explained in more detail using an exemplary embodiment.

From a wire with a thickness of 0.5 mm, which is made of aluminum with a purity of $ 99 »$ 999 will be bits of Cut off 0.5 mm long, resulting in several bodies that are roughly cylindrical with slight deformations at the cut

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909844/1647

BATH ORIGINAL

areas are. These bodies are scattered on a shell made of graphite, preferably lying next to one another in one layer, i.e. not on top of one another, whereupon the shell is placed in a furnace which is filled with a reducing gas such as a mixture of nitrogen and hydrogen. The furnace is brought to a temperature of 780 ^° C., so there is little change in the shape of the bodies above the melting point of aluminum · Sis. While about 1 liter of the mentioned gas is passed through the furnace per minute, 25 ecm of hydrochloric acid gas is fed in at the same time. As a result, the aluminum oxide is dissolved or at least loses its cohesion to such an extent that the molten aluminum contracts to form spherical bodies. Due to the way in which they were cut from the wire, all wires are almost the same weight and average. The invention is of course not limited to this type of production of the starting bodies. You can e.g. B. danced out of a plate or cut off from a tape.

Patent claims *

909844/1647 ^{BAD 0R! GINAL}

Claims (1)

Patent claims: 1. Process for the production of spherical from one spontaneously covered with an oxide skin by the action of air Made of metal or alloy, preferably aluminum * the body, particularly for use in the manufacture of semiconductor devices such as transistors and diodes, daduroh. characterized in that a number of non-round bodies made of a metal covered with an oxide skin on a solid base up to are heated above their melting point and then briefly supplied with a gaseous etchant for the metal oxide so that the connection of the oxide skin is little interrupted becomes, and the bodies assume a circular shape under the action of surface tension, whereupon they are cooled down. 2, method according to claim 1, characterized in that Hydrochloric acid gas is used as an itzmittel. 9098U / 16A7