CS242775B1 - A method for producing an aluminum alloy foil - Google Patents

Abstract

The solution relates to an aluminum-silicon alloy foil and a method of producing it, using continuous upward casting of a waist-shaped semi-finished product with a thickness of 5 to 15 mm, followed by rolling it with a reduction of 30 to 95% and intermediate annealing at a temperature of 200 to 560 °C for 0.25 to 15 hours to produce an aluminum alloy foil with 10 to 20% by weight of silicon and a maximum of 0.1% by weight of accompanying elements, with a thickness of 0.02 to 0.12 mm.

Description

The invention relates to a process for the production of an aluminum-silicon alloy film having a silicon content of from 10 to 20% by weight.

For electrotechnical purposes, it is necessary to use steamed intermediate layers before soldering silicon wafers to metal substrates. For this intermediate layer, foils made of eutectic or possibly nadutectic silumin, which is an aluminum alloy with 12 to 20% by weight of silicon, can be used. This is essentially a conventional foundry alloy used for casting.

However, the inadequate plastic properties of the alloy do not make it possible, by conventional rolling processes, to produce the 20 to 120 µm film desired by the electrical industry. Indeed, the plasticity of this alloy is greatly influenced by the inappropriately excluded large primary silicon crystals and the iron-containing intermetallic phases, which are always present as an accompanying element in the alloy. In view of this fact, the classical method of hot and cold rolling from semi-products cast by conventional methods would mean a completely inefficient process, in which it would be necessary to include inter-operational annealing already after slight deformation. Otherwise it would necessarily lead to cracking of the semi-finished product.

The above-mentioned drawbacks are eliminated by the aluminum-silicon alloy according to the invention, which consists in that the alloy consists in a concentration by weight of 10 to 20% silicon, at most 0.1% of accompanying elements such as iron, copper, magnesium, strontium, zinc or manganese, the rest being aluminum.

According to the invention, the method for producing a film from a preform consists in continuously casting a 5-15 mm thick waist into a graphite crystallizer of a continuous casting device upwards. By continuously casting a 5-15 mm thick waist into a graphite crystallizer, the heat dissipation is so great that the material crystallizes quickly enough to prevent the formation of unwanted coarse primary silicon crystals. The resulting preform is then sufficiently plastic for the subsequent production of a 0.02 to 0.12 mm thick film by rolling. The low content of accompanying elements, below 0.1% by weight, eliminates the possibility of undesirable formation of iron-containing intermetallic phases and at the same time allows the use of this alloy in the manufacture of semiconductor devices. The alloy is then sufficiently ductile and can be processed by hot and cold rolling with a reduction of 30 to 95% and an annealing at 200 to 560 ° C for 0.25 to 15 hours.

Example 1

An alloy of 11.7% by weight silicon, the remainder aluminum, was cast by continuous casting upwards in the form of 10 mm thick belts at a speed of 15 m.hl. The waist was further hot rolled with a total reduction of 70%, then annealed at 350 ° C / 45 min, cold rolled with a reduction of 80%, annealed 350 ° C / 45 min, then alternated cold rolling with reductions of about 80% s by annealing at 350 ° C / 45 min to a desired film thickness of 0.05 mm.

Example 2

The 13% silicon alloy, the rest aluminum, was cast as described in Example 1. The waist was annealed at 530 ° C / 15 h and rolled with total reductions of 50 to 90 °, with an annealing of 330 to 370 ° C / 0.5 to 1 h up to the required film thickness of 0.03 mm.

Example 3

An alloy of 12% by weight silicon, the remainder aluminum, was cast as described in Example 1. The waist was further cold rolled with a 40% reduction. An intermediate annealing of 400 ° C / 30 min followed by alternating cold rolling with reductions of 5.5 to 80% with an annealing of 400 ° C / 30 min to a final desired film thickness of 0.025 mm.

Claims (1)

SUBJECT OF THE INVENTION The use of continuous up-casting of a 5 to 15 mm waist blank, followed by rolling with 30 to 95% reduction and annealing at 200 to 560 ° C for 0.25 to 15 hours, for the production of aluminum alloy foil, with 10 to 20% by weight of silicon and a maximum of 0.1% by weight of the accompanying elements, with a thickness of 0.02 to 0.12 mm.