【発明の詳細な説明】[Detailed description of the invention]
本発明は、軟化温度が低くて製造容易な高導電
用銅材に関する。
周知の如く純銅及び銅合金は導電性に優れ且つ
良好な加工性を有することから導電用細線、プリ
ント配線基板用圧延箔、フラツトケーブル用銅箔
条等多様な用途に用いられている。
従来このような用途には、無酸素銅のような純
銅や銅−銀合金等の銅合金が多く用いられてい
る。
近年省資源の為上記材料の薄肉化が求められて
いるため、これら材料を上記用途に供するまでの
冷間加工率が増大し、従つてこれらの製造過程に
おいて必要とされる焼鈍処理の回数も増加してき
ている。この焼鈍処理回数を減少させたり、焼鈍
処理温度自身を低くすることができれば省エネル
ギーの趨勢などの見地から好ましい。
本発明者等は上記の事情に鑑み、導電率が少な
くとも純銅のそれより低下することなく、軟化温
度が上記材料より大幅に低い銅上を提供すべく、
まず純銅に種々の第二元素を微量添加して得られ
た銅合金の中で、第二元素として硼素、バナジウ
ム、クロム、ハフニウムおよびジルコニウムを添
加したものを提案した（特願昭58−35515号及び
同58−124115号）。その後、引続いて純銅に上記
第二元素であるバナジウムとジルコニウムにチタ
ンを加えた３種の元素を内割りのモルにて約
30ppm（以下、ppmは内割りのモルによるもの
とする）添加した銅合金について、これらの合金
の軟化温度が低下する機構を検討した結果、次の
知見を得た。
即ち、電気銅にバナジウム、ジルコニウム、チ
タンを無添加から単味で約30ppmの範囲で添加
した合金を通常の真空溶解で溶製、鋳造し、20mm
×40mm×60mmの鋳塊を得た後、これを１mm厚さま
で冷間圧延後、直径0.5mmまで引抜加工した。こ
うして得られた線材の一部を、更に800℃で30分
焼鈍した後、水冷した。前記の引抜加工材及び焼
鈍急冷材の比抵抗を測定した。その結果を試料の
組成と共に図示したのが第１図である。
この結果から、どの添加元素の場合もその添加
量が7ppm以下の極微量範囲では、比抵抗が引抜
加工材も焼鈍急冷材も、無添加の値と殆んど変わ
らないことが見出された。このことは、7ppm以
下のパナジウム、ジルコニウム、チタンは純銅中
に固溶していないことを示している。本発明者等
は、上記現象は純銅中に含まれている不可避不純
物と上記添加元素が何らかの化合物を形成し、そ
の不可避不純物が銅の軟化温度を高める作用を上
記添加元素が7ppmを超えないと減殺するに至ら
ないことを示すものと考え、更にはこのように不
可避不純物が硫黄ではないかと着意するに至つ
た。
そこで本発明者等は次に、電気銅から低硫黄純
銅を作成し、この低硫黄純銅の軟化温度について
鋭意研究を行なつた結果、驚くべきことに、硫黄
含有量を1ppm以下とした低硫黄純銅が、通常
の、電気銅、無酸素銅のような純銅よりも著しく
低い軟化温度を示すことを見出し、本発明に到達
した。
以下、本発明を更に説明する。
本発明銅材において、硫黄の含有量を1ppm以
下に限定したのは、1ppmを超えると脱硫黄によ
る軟化温度の低下が、通常の従来の純銅より充分
でないからである。
通常の純銅には硫黄が数ppmもしくはそれ以
上含有されているが、この硫黄を1ppm以下にす
るには、通常の純銅を硝酸銅浴電解による電解採
取、帯域精製、水素ガスなどによる乾式脱硫など
の方法によつて更に精製すれば良い。
また、通常の純銅の酸素含有量は500ppm以下
であるが、本発明銅材においても、酸素の含有量
は500ppm程度もしくはそれ以下で本発明の目的
を充分達成することができる。
更に、本発明銅材の溶解及び鋳造の雰囲気とし
ては、特に限定することなく、通常行なわれてい
る方法が採用できる。
次に、本発明の実施例を比較例と共に説明す
る。
実施例
まず、電気銅、電気銅を硫酸酸性硫酸銅浴で再
電解して採取した高純度銅、及び電気銅を硫酸酸
性硝酸銅浴で再電解して採取した低硫黄純銅を、
真空度を５×10-3Torr以下に調整した真空チヤ
ンバー中の黒鉛ルツボで高周波溶解した後、該溶
解と同一の雰囲気下で金型に鋳造して厚さ20mm、
幅60mm、長さ100mmの鋳塊を製造した。
得られた鋳塊の組成（ppm）は第１表のよう
であつた。
The present invention relates to a highly conductive copper material that has a low softening temperature and is easy to manufacture. As is well known, pure copper and copper alloys have excellent conductivity and good workability, and are therefore used in a variety of applications, such as thin conductive wires, rolled foils for printed wiring boards, and copper foil strips for flat cables. Conventionally, pure copper such as oxygen-free copper and copper alloys such as copper-silver alloys have often been used for such uses. In recent years, there has been a demand for thinner materials for the above-mentioned materials in order to conserve resources, so the rate of cold working of these materials before they are used for the above-mentioned purposes has increased, and the number of annealing treatments required in the manufacturing process has also increased. It is increasing. It is preferable from the standpoint of energy saving if the number of times of this annealing treatment can be reduced or the annealing treatment temperature itself can be lowered. In view of the above circumstances, the inventors of the present invention aimed to provide a copper surface whose conductivity is at least as low as that of pure copper and whose softening temperature is significantly lower than that of the above-mentioned materials.
First, among the copper alloys obtained by adding trace amounts of various secondary elements to pure copper, we proposed one in which boron, vanadium, chromium, hafnium, and zirconium were added as secondary elements (Japanese Patent Application No. 58-35515). and No. 58-124115). After that, three kinds of elements (vanadium, which is the second element mentioned above, zirconium, and titanium) are added to pure copper in a molar amount of about
As a result of examining the mechanism by which the softening temperature of copper alloys containing 30 ppm (ppm hereinafter refers to the internal molar ratio) of these alloys is lowered, the following findings were obtained. In other words, an alloy containing vanadium, zirconium, and titanium added to electrolytic copper in a range of about 30 ppm from no additives to about 30 ppm is melted and cast using normal vacuum melting, and a 20 mm
After obtaining an ingot measuring 40 mm x 60 mm, it was cold rolled to a thickness of 1 mm and then drawn to a diameter of 0.5 mm. A portion of the wire rod thus obtained was further annealed at 800° C. for 30 minutes, and then cooled with water. The specific resistance of the above-mentioned drawn material and annealed and quenched material was measured. FIG. 1 shows the results along with the composition of the sample. From this result, it was found that for any additive element, in the extremely small range of 7 ppm or less, the resistivity of both the drawn material and the annealed and quenched material is almost the same as the value without additives. . This indicates that panadium, zirconium, and titanium of 7 ppm or less are not dissolved in pure copper. The inventors believe that the above phenomenon is caused by the unavoidable impurities contained in pure copper and the added elements forming some kind of compound, and that the unavoidable impurities have the effect of increasing the softening temperature of copper unless the added elements exceed 7 ppm. We thought this to be an indication that it was not enough to reduce the amount of oxidation, and we also came to the conclusion that the unavoidable impurity may be sulfur. Therefore, the present inventors next created low-sulfur pure copper from electrolytic copper, conducted extensive research on the softening temperature of this low-sulfur pure copper, and surprisingly found a low-sulfur product with a sulfur content of 1 ppm or less. The present invention was achieved by discovering that pure copper exhibits a significantly lower softening temperature than ordinary pure copper such as electrolytic copper and oxygen-free copper. The present invention will be further explained below. The reason why the sulfur content in the copper material of the present invention is limited to 1 ppm or less is that if it exceeds 1 ppm, the softening temperature due to desulfurization will not be lowered as much as in conventional pure copper. Ordinary pure copper contains several ppm or more of sulfur, but in order to reduce this sulfur to 1 ppm or less, ordinary pure copper must be electrowinning using copper nitrate bath electrolysis, zone refining, and dry desulfurization using hydrogen gas, etc. It may be further purified by the method described below. Further, although the oxygen content of ordinary pure copper is 500 ppm or less, the purpose of the present invention can be sufficiently achieved in the copper material of the present invention with an oxygen content of about 500 ppm or less. Furthermore, the atmosphere for melting and casting the copper material of the present invention is not particularly limited, and commonly used methods can be employed. Next, examples of the present invention will be described together with comparative examples. Example First, electrolytic copper, high purity copper collected by re-electrolyzing electrolytic copper in a sulfuric acid acidic copper sulfate bath, and low sulfur pure copper collected by re-electrolyzing electrolytic copper in a sulfuric acid acidic copper nitrate bath,
After high-frequency melting in a graphite crucible in a vacuum chamber with the degree of vacuum adjusted to 5 × 10 -3 Torr or less, it was cast into a mold in the same atmosphere as the melting to a thickness of 20 mm.
An ingot with a width of 60 mm and a length of 100 mm was produced. The composition (ppm) of the obtained ingot was as shown in Table 1.
【表】
次に、(1)既に得た真空溶解した低硫黄純銅を一
部採取し、この低硫黄純銅を前回と同様にして溶
解し硫化第一銅を添加して所望量の硫黄を合金溶
解させた後、前回と同様にして鋳造した硫黄添加
銅、(2)この硫黄添加銅を一部採取し、この硫黄添
加銅を前回と同様にして溶解し所望量のチタンを
合金溶解させた後、前回と同様にして鋳造した硫
黄チタン添加銅並びに(3)既に得た真空溶解した低
硫黄純銅の他の一部を採取し、この低硫黄純銅を
黒鉛ルツボで高周波大気溶解した後、該溶解と同
一の雰囲気下で金型に鋳造した酸素含有銅を製造
した。
得られた鋳塊の組成（ppm）は第２表のよう
であつた。[Table] Next, (1) Take a portion of the vacuum-melted low-sulfur pure copper that has already been obtained, melt this low-sulfur pure copper in the same manner as before, and add cuprous sulfide to alloy the desired amount of sulfur. After melting, sulfur-added copper was cast in the same manner as before. (2) A portion of this sulfur-added copper was collected, and this sulfur-added copper was melted in the same manner as before to melt the desired amount of titanium into an alloy. After that, the sulfur-titanium-added copper cast in the same manner as before and (3) another part of the already obtained vacuum-melted low-sulfur pure copper were collected, and this low-sulfur pure copper was melted in a graphite crucible under high-frequency atmospheric pressure. Oxygenated copper was produced which was cast into molds under the same atmosphere as melting. The composition (ppm) of the obtained ingot was as shown in Table 2.
【表】
以上のような鋳塊試料を準備した後、これらの
鋳塊表面を片側１mmずつ面削し、850℃で熱間圧
延して厚さ10mmとした。この圧延材から導電率を
測定する試料を採取した。更にこの熱間圧延材を
片側１mmずつ面削した後、厚さ８mmから0.5mmま
で冷間圧延を行なつた。得られた板材から一辺20
mmの正方形の板片を裁断して作成し、軟化温度を
測定する試料とした。
軟化温度の測定は、40、80、120、160、200、
240及び300℃に設定した油浴中に30分間浸漬加熱
された試料のビツカース硬度を測定することによ
り行なつた。得られた結果を第３表に示す。第３
表のビツカース硬度を加熱温度に対してプロツト
して第２図に示した。[Table] After preparing the ingot samples as described above, the surfaces of these ingots were milled 1 mm on each side and hot rolled at 850°C to a thickness of 10 mm. A sample for measuring electrical conductivity was taken from this rolled material. Furthermore, this hot-rolled material was faceted by 1 mm on each side, and then cold-rolled from 8 mm to 0.5 mm in thickness. 20 per side from the obtained board material
A square plate piece of mm size was cut and used as a sample for measuring the softening temperature. Softening temperature measurements are 40, 80, 120, 160, 200,
This was done by measuring the Vickers hardness of samples that were immersed and heated in oil baths set at 240 and 300°C for 30 minutes. The results obtained are shown in Table 3. Third
The Vickers hardness shown in the table is plotted against the heating temperature and is shown in FIG.
【表】
第３表から明らかなように、硫黄含有量を
1ppm以下に抑えた純銅は酸素含有量の僅少な真
空溶解した低硫黄純銅（試験No.3）でもそれの
比較的多い酸素添加銅（試験No.8）でも導電率
が104％I.AC.S.で、真空溶解した電気銅（試験
No.1）や高純度銅（試験No.2）のような純銅と
同程度かむしろ高目であり、且つ軟化温度が85℃
とか87℃程度で前記と同様の比較で70℃程度低
い。一方、硫黄含有量が1ppmを超えると、その
増大と共に軟化温度も高くなる（試料No.4、
５、６）。また、試験No.6と同No.7とはTi添加の
有無が相違しているとほぼ考えられるが、軟化温
度に大きな相違がみられる。
第３図は試験No.7の試料の走査型電子顕微鏡
による組織であり、第４図は第３図矢印で示す微
小介在物をエネルギー分散式Ｘ線分析装置により
測定した結果であるが、これらの図から明らかな
ように、上記微小介在物が硫化物であることが判
る。従つて、前記試験No.6と同７の軟化温度に
おける大幅な相違は、銅中の硫黄が固溶している
のと、添加されたチタンによつて硫化物として析
出しているのとの相違に相当するものと判断さ
れ、この硫化物の析出によつて軟化温度が低くな
ることが判つた。このような事実と硫黄を1ppm
以下に抑えた本発明銅材の軟化温度が低くなる現
象とによつて、銅中の微量の硫黄が軟化温度を高
める重大な役割を演じることが判明した。
本発明は、導電率が通常の純銅よりむしろ高目
で、軟化温度が通常の純銅より大幅に低い銅材で
あるので、導電用軟銅線やフラツトケーブル用銅
箔条の製造工程において焼鈍温度を大幅に下げた
り（時間の経過が許されれれば室温から100℃程
度の乾燥器中に保存するのみで良い）、焼鈍時間
を大幅に短縮したりできる。[Table] As is clear from Table 3, the sulfur content
Pure copper with a content of less than 1 ppm has a conductivity of 104% I.AC, whether it is vacuum melted low-sulfur pure copper with a small oxygen content (Test No. 3) or copper with a relatively high oxygen content (Test No. 8). Vacuum melted electrolytic copper (test
No. 1) and high-purity copper (Test No. 2), which are comparable to or even higher than pure copper, and have a softening temperature of 85℃.
It is about 87℃, which is about 70℃ lower in the same comparison as above. On the other hand, when the sulfur content exceeds 1 ppm, the softening temperature also increases as the sulfur content increases (sample No. 4,
5, 6). Furthermore, although it is most likely that Test No. 6 and Test No. 7 differ in the presence or absence of Ti addition, there is a large difference in softening temperature. Figure 3 shows the structure of the test No. 7 sample taken with a scanning electron microscope, and Figure 4 shows the results of measuring the minute inclusions indicated by the arrows in Figure 3 using an energy dispersive X-ray analyzer. As is clear from the figure, it can be seen that the minute inclusions mentioned above are sulfides. Therefore, the large difference in softening temperature between Test No. 6 and Test No. 7 is due to sulfur being dissolved in the copper and precipitated as sulfide due to the added titanium. It was determined that this corresponds to a difference, and it was found that the softening temperature was lowered due to the precipitation of this sulfide. 1ppm sulfur with these facts
It has been found that a trace amount of sulfur in copper plays an important role in increasing the softening temperature due to the phenomenon that the softening temperature of the copper material of the present invention is lowered to below. The present invention is a copper material whose conductivity is higher than that of ordinary pure copper and whose softening temperature is significantly lower than that of ordinary pure copper. It is possible to significantly reduce the temperature (if time permits, it is sufficient to store the material in a dryer at room temperature to about 100°C), and to significantly shorten the annealing time.
【図面の簡単な説明】[Brief explanation of the drawing]
第１図は比抵抗に及ぼす硫黄含有量の影響を引
抜加工材と焼鈍急冷材とについて示したグラフ、
第２図は第１表における供試合金の加熱軟化の様
子を示したグラフ、第３図は試験No.7の試料の
組織の走査型電子顕微鏡写真図、第４図は第３図
矢印部分をエネルギー分散式Ｘ線分析装置によつ
て測定して得られたＸ線強度とエネルギーとの関
係図である。
Figure 1 is a graph showing the influence of sulfur content on resistivity for drawn materials and annealed and rapidly cooled materials.
Figure 2 is a graph showing the state of heat softening of the test gold in Table 1, Figure 3 is a scanning electron micrograph of the structure of the sample in test No. 7, and Figure 4 is the area indicated by the arrow in Figure 3. FIG. 2 is a diagram showing the relationship between X-ray intensity and energy obtained by measuring with an energy dispersive X-ray analyzer.