JPH0499236A - Manufacture of extra low oxygen copper - Google Patents

Abstract

PURPOSE:To manufacture extra low oxygen copper capable of further thinning and forming into a thin wire by forming the molten metal of pure copper stock contg. specified amounts of oxygen and hydrogen into deoxidized hydrogen-enriched one under specified conditions, and thereafter successively executing primary dehydrogenating and secondary dehydrogenating heat treatment under specified conditions. CONSTITUTION:A reducing gas obtd. by mixing one or more kinds among N2, Ar and CO with H2 in the total ratio of 0.5 to 50vol.% is blown into the molten metal of pure copper stock with >=99.99% purity contg. 3 to 10ppm [O] and <=1ppm [H] to regulate the [O] content to <=1ppm and the [H] content to 0.8 to 3ppm. Next, this molten metal of deoxidized hydrogen-enriched pure copper is subjected to primary dehydrogenating treatment of bringing it into reaction with a reaction gas constituted of one or more kinds among N2, Ar and CO to regulate the [O] content to <=1ppm and the [H] content to 0.5 to 1.5ppm, and this primary dehydrogenated pure copper molten metal is cast into an ingot and is subjected to secondary dehydrogenating heat treatment under the conditions of holding in a nonoxidizing atmosphere to a prescribed temp. in the range of 700 to 900 deg.C for prescribed time, by which the extra low oxygen copper in which the [O] content is regulated to <=1ppm and the [H] content to <=0.3ppm is manufactured.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is applicable to oxygen (hereinafter referred to as [0]) content of 1
The present invention relates to a method for producing ultra-low oxygen copper of ppm or less. [Prior Art] Conventionally, oxygen-free copper, deoxidized copper, and vacuum melted copper have been known as pure copper with a purity of 99.99% or higher. , [0) has the lowest content, about 3 to 10 ppm, and has good ductility and workability, so it is used, for example, in ultrafine wires for bonding wires of semiconductor devices and foil strips for printed circuit boards. Used in manufacturing. Problems to be solved by the invention C] On the other hand, in recent years, the degree of integration of semiconductor devices has been remarkable, and with this, bonding wires and printed circuit boards are also required to be thinner and thinner. As mentioned above, oxygen-free copper has a low oxygen content of 3 to lop per million, but due to the oxygen content, it has sufficient ductility and workability to enable further thinning and thinning of the wire. Therefore, further thinning or thinning of the wire tends to cause disconnection or breakage, and it is not possible to satisfactorily meet the above requirements from a practical and economical point of view. In addition, conventional purification methods such as vacuum melting method and C
Attempts have been made to purify the oxygen-free copper using an O-containing gas atmosphere dissolution method, but it is currently impossible to reduce the [0] content to 2 ppω or less. [Means for Solving the Problems] Therefore, from the above-mentioned viewpoint, the present inventors set out to produce ultra-low oxygen copper with a lower CO) content than the conventional oxygen-free copper described above. As a result of research, []: 3 to 10 ppm. Hydrogen (hereinafter referred to as CHI): One or two of N2, Ar, and CO is added to a pure copper material molten metal corresponding to conventional oxygen-free copper containing 1 ppm or less and having a purity of 99.9996 or more. When a reducing gas made by mixing 0.5 to 50% by volume of H2 is injected into the molten pure copper material, the content of [0] or 1 in the pure copper material molten metal is blown.
- [H] in the molten metal of Rikishiki pure copper material is reduced to below ppm.
The content increases to 0.8 to 3 ppm, but this deoxygenated hydrogen-enriched pure copper molten metal is dehydrated by reacting with a reaction gas consisting of one or more of N2, Ar, and CO. When subjected to elementary (primary dehydrogenation) treatment, [0
] There was almost no change in the content, and the (H) content was reduced to 05 to 1.
．． It can be reduced to 5 ppm or less, and furthermore, in the state where it is cast into an ingot, it is heated by vacuum or N 2 ,
When secondary dehydrogenation treatment is carried out under the conditions of holding at a predetermined temperature within the range of 700 to 900°C for a predetermined time in a non-oxidizing atmosphere such as Ar, there is almost no change in the [0] content, and (H ) content 0.3pp+n
Moreover, when this ultra-low oxygen copper is made into an ultra-fine wire, the diameter of the ultra-fine wire is 60 mm, which is easy to draw practically and economically with conventional oxygen-free copper. On the other hand, it is easy to draw wire up to a diameter of 50, and as for the foil material, the rolled copper foil made of ultra-low oxygen copper has a lower temperature than the rolled copper foil made of oxygen-free copper. Research results showed that the material had extremely good flexibility. Therefore, this invention was made based on the above research results, [01):3~lOppm. A pure copper material molten metal containing (H) + 1 ppm or less and a purity of 99.999 o or more is added with one or more of N2, Ar, and CO in a total proportion of 0.5 to 50. A reducing gas prepared by mixing H2 of volume ffi % is blown in to reduce the [O] and (H) content to [Q]:1
ppm or less\ [H): 0.8 to 3 ppm, and then N 2 is added to this deoxygenated hydrogen-enriched pure copper molten metal.
, A r , and a reaction gas consisting of one or more of CO, [0] and (
H) content: [0): 1 ppm or less, (H) + 0.5 to 1.5 ppm. Next, this primary dehydrogenated pure copper melt is cast into an ingot, and this ingot is subjected to secondary dehydrogenation under the following conditions: held at a predetermined temperature within the range of 700 to 900°C for a predetermined time in a non-oxidizing atmosphere. After heat treatment, [0] and (H
) content of [0): 1 ppm or less, [H): 0.3 ppm or less] This method is characterized by a method for producing ultra-low oxygen copper. In addition, in the method of this invention, the [○] and (H) contents in the deoxygenated hydrogen-enriched pure copper molten metal are necessarily determined, and in other words, the content is 3 to 10pp of the pure copper material molten metal.
m [0] content, the above H2: 0.5 to 50% by volume
When reducing the content to 1 ppI11 or less using the containing reducing gas, the [H) content inevitably increases from 0.8 to 3 pp111.
If this level of [H] is present, the next primary and secondary dehydrogenation treatments will reduce the (H) content to 0 and 3 without increasing the (0) content. ppm
This was determined based on experimental results showing that it can be reduced to below. In addition, in the method of the present invention, the reason why the 82% in the reducing gas is determined to be 15 to 50% by volume of O is that 0.
If the volume is less than 5% by volume, the desired [O] reduction effect will not be exhibited, while if the proportion exceeds 50% by volume, the [H] content in the deoxygenated hydrogen-enriched pure copper molten metal will exceed 3 ppm and become high. This was reduced to 0.3pp in the next step of dehydrogenation treatment.
This is because reducing the number to below m requires a considerable amount of processing time, which is not economical. Furthermore, the reason why the secondary dehydrogenation heat treatment temperature was limited to 700 to 900°C is that if the temperature is lower than 700°C, it will take a long time to perform the specified dehydrogenation, whereas if the temperature is lower than 700°C,
This is based on the reason that if the temperature exceeds .degree. C., the crystal grains will become coarser, the strength and ductility will decrease, and breakage or disconnection will easily occur during the production of foil materials and ultrafine wires. [Examples] Next, the method of the present invention will be specifically explained using examples. In a normal melting furnace, using oxygen-free copper as the raw material,
Each 10 kg of pure copper material molten metal having the purity shown in the table and the [0] and [H) content is melted, and the composition shown in Table 1 is added to this pure copper material molten metal at a temperature of 150°C. A reducing gas of 1g/1n was blown into the molten metal for 10 minutes to obtain a deoxygenated hydrogen-enriched pure copper molten metal with the [0) and [H] contents shown in Table 1. A primary dehydrogenation treatment is carried out by blowing a reaction gas having a composition of
Subsequently, this primary dehydrogenation pure copper molten metal was cast into an ingot with a diameter of +70 mm, and this ingot was subjected to secondary dehydrogenation heat treatment under the same conditions shown in Table 1 (holding time: 60 minutes). Inventive methods 1 to 9 and comparative methods 1 to 9 were carried out to produce ultra-low oxygen copper of the present invention 1 to 9 and comparative low oxygen copper having the purity and [O] and [H] content shown in Table 2. Coppers 1 to 9 were produced respectively. In the above example, a batch method was adopted to clearly capture the changes in each process, but in actual operation, a melting furnace is used to melt the pure copper material, and a reducing gas is blown into the molten pure copper material to eliminate oxygen in the molten metal. A deoxidizer that reacts with and removes it, and a dehydrogenator that performs a primary dehydrogenation treatment by blowing a reaction gas into the resulting deoxygenated hydrogen-enriched pure copper m& or exposing it to the reaction gas. , using a continuous refining device that airtightly connects a continuous casting device that casts molten metal through a molten metal flow path (gutter), and performs a secondary dehydrogenation heat treatment on the ingot from this continuous refining device, which produces ultra-low oxygen copper. It is desirable to manufacture In addition, in all of Comparative Methods 1 to 9, one of the manufacturing conditions (marked with * in Table 1) is outside the scope of the present invention. Next, the various ultra-low oxygen copper ingots obtained as a result are hot rolled at a hot rolling start temperature of 800°C to form a hot rolled plate with a width of 0 mm x thickness + 10 mm, and then this hot rolling process is performed. The rolled plate is cold rolled to a width of 70+l1mXthickness+
A cold-rolled sheet of 0.5 mm was applied to the cold-rolled sheet in a vacuum for 40 minutes.
After annealing at 0° C. for 1 hour, a foil material having a thickness of +35 mm was produced by cold rolling. Also, 800 for an ingot with a diameter of near 0+++m
Hot forged at a hot forging start temperature of ℃, diameter: 20
This round bar was made into a wire rod with a diameter of 20.9 degrees by cold drawing, and after annealing it in a vacuum at 400°C for 1 hour, it was subjected to cold wire drawing. Diameter =
A 50-un ultrafine wire was manufactured. Next, regarding the foil material obtained as a result, JIS
- Conducted a bending strength test based on P8115,
The number of times a test piece having dimensions of width 15m1IX length llo+om was cut back and forth until it broke was measured. In addition, regarding the ultra-fine wire, the number of wire breaks per 100 kg of wire drawing when drawing the wire from diameter = 60LfH1 to the final size of diameter: 50tI# was determined as mj. The results of these measurements are shown in Table 2. [Effect of the invention] From the results shown in Tables 1 and 2, it is clear that methods 1 to 1 of the present invention
According to 9, [O] content + 1 ppIIl or less, (H3
It is possible to produce ultra-low oxygen copper with content fit: 0.3+) pIII or less, and the ultra-low oxygen copper obtained as a result has such a low [0] content, so for example, the thickness is 35 Door foil material and diameter: 50t! Even when producing ultra-fine wires, there are very few breakages or disconnections, and these foil materials and ultra-fine wires can be manufactured economically.
As seen in Comparative Methods 1 to 9, if any of the production conditions falls outside the scope of the present invention, at least any of the [03 and [H] contents in the ultra-low oxygen copper produced Because the content is high,
In the production of foil materials and ultra-fine wires, breakage and disconnection occur significantly, and it is clear that it is virtually impossible to manufacture foil materials with a thickness of 351 EIl and ultra-fine wires with a diameter of 50 mm. As described above, according to the method of the present invention, it is possible to produce ultra-low oxygen copper with a [0] content of 1 ppm or less, which was previously impossible to produce. Ultra-low oxygen copper has excellent ductility and workability, so when producing foil materials or ultra-fine wires from it, for example,
Compared to the conventional case of using oxygen-free copper, it is possible to achieve significantly thinner walls and thinner wires, and therefore, for example, it can contribute to higher integration of semiconductor devices.
This brings about a useful effect on the beam.

Claims (1)

[Claims] (1) A pure copper material molten metal with a purity of 99.99% or more, containing oxygen: 3 to 10 ppm, hydrogen: 1 ppm or less,
A reducing gas made by mixing one or more of N_2, Ar, and CO with H_2 in a total proportion of 0.5 to 50% by volume is blown to reduce the oxygen and hydrogen content. : 1 ppm or less, hydrogen: 0.8 to 3 ppm, and then to this deoxygenated hydrogen-enriched pure copper molten metal, N_2,
A primary dehydrogenation treatment is performed to react with a reactive gas consisting of one or more of Ar and CO, and the oxygen and hydrogen contents are reduced to: Oxygen: 1 ppm or less, Hydrogen: 0.5 to 1.5 ppm After that, it is cast, and then this primary dehydrogenated pure copper ingot is subjected to secondary dehydrogenation heat treatment under the following conditions: held at a predetermined temperature within the range of 700 to 900°C for a predetermined time in a non-oxidizing atmosphere. A method for producing ultra-low oxygen copper, characterized in that the oxygen and hydrogen contents are: oxygen: 1 ppm or less; hydrogen: 0.3 ppm or less.