JP3718036B2

JP3718036B2 - Extra fine copper wire and method for producing the same

Info

Publication number: JP3718036B2
Application number: JP31519997A
Authority: JP
Inventors: 貴朗市川; 正義青山; 和宏山田; 勉高橋; 秀寿長山
Original assignee: Hitachi Cable Ltd
Current assignee: Hitachi Cable Ltd
Priority date: 1997-11-17
Filing date: 1997-11-17
Publication date: 2005-11-16
Anticipated expiration: 2017-11-17
Also published as: JPH11152532A

Description

【０００１】
【発明の属する技術分野】
本発明は極細銅線、特に極細エナメル線の心線に適する極細銅線及びその製造方法に関する。
【０００２】
【従来の技術】
時計のステッピングモータ、磁気記録用の磁気ヘッド、ブラウン管用のフライバックトランス等のコイル等には、直径0.02ないし0.05ｍｍの極細エナメル線が用いられている。極細エナメル線の心線には、タフピッチ銅や無酸素銅のような酸素の含有量が0.1％以下の高純度の銅（以下、純銅と言う）からなる半軟化させた極細の軟銅線が用いられている。
【０００３】
その極細の軟銅線は、純銅の荒引線を冷間で伸線し、途中、何回かの焼鈍工程を経て最終線径まで伸線し、焼鈍工程を経て軟化された後、エナメル塗装されて製品となる。
【０００４】
この極細銅線の製造時に問題となる事項の一つに断線がある。この断線は素材中の介在物によって生じる場合もあるが、伸線中に材料と伸線ダイスとの摩擦熱によって材料が軟化し、伸線ダイスによる引き抜きの張力に耐えられなくなって生じる場合が多い。この種の断線は加工度（断面減少率）が９５％以上の場合に生じ易く、従って、線径が小さくなるほどその影響を受け易くなる。
【０００５】
断線以外の問題としては、最終線径まで伸線された銅線の引張り強度及び伸びが経時変化すること、すなわち保管時間とともに、それらの特性値が低下する問題である。これは伸線材の室温での再結晶による軟化が原因であり、酸素含有量が極端に少ない無酸素銅で特に顕著であり、酸素含有量が比較的多いタフピッチ銅でも、伸線加工度が高い場合にはこの現象が見られる。
【０００６】
このような室温における軟化の原因である再結晶は素材中に局部的に発生するもので、再結晶部分の金属組織を観察すると、特定の粒子が成長して粗大化するという特徴がある。このような状態の銅線をエナメル線の製造工程で焼鈍すると、新たに微細粒子が発生し、すでに存在する粗大粒との混在状態となり、室温での軟化が生じない銅素材を焼鈍したもの（金属組織は均一で微細な再結晶組織）と比較して引張強さや伸びが低下するという不具合が生じる。この伸線材の軟化は、伸線工程での加工度が高いほど、保管温度が高いほど、生じ易い。
【０００７】
【発明が解決しようとする課題】
伸線の際の断線や室温保管による軟化を軽減するためには、伸線の際の加工度を小さくし、伸線の間の焼鈍の回数を増やすことが考えられる。しかし、そのようにすることは製造コストを増大させることになる。
【０００８】
それ故、本発明の目的は、伸線材の室温における軟化が顕著でないタフピッチ銅をベースとし、その製造工程での伸線中の断線と、伸線の間の焼鈍回数の増加を抑制でき、製造コストの低い極細銅線を提供することにある。
【０００９】
本発明の他の目的は、室温保管での経時変化による引張り強度や伸びの減少が小さい極細銅線を提供することにある。
【００１０】
本発明のさらに他の目的は、上記のような極細銅線の製造方法を提供することにある。
【００１１】
【課題を解決するための手段】
本発明は、上記目的を達成するため、酸素含有量が２００〜４００ｐｐｍのタフピッチ銅に錫及びインジウムのうち１種以上の金属を５ｐｐｍ以上２００ｐｐｍ未満含有させた銅材を直径０．０２〜０．０４ｍｍに加工した軟銅線からなり、結晶粒が微細で、引張強さが３５ｋｇ／ｍｍ ^２未満であるという構成の極細銅線を提供する。
【００１２】
また、本発明は、上記の目的を達成するために、酸素含有量が２００〜４００ｐｐｍのタフピッチ銅の鋳造過程で、前記タフピッチ銅の溶湯に錫及びインジウムのうち１種以上の金属を５ｐｐｍ以上２００ｐｐｍ未満添加し、得られた銅材を直径０．０２〜０．０４ｍｍに冷間伸線した後、焼鈍するという製造方法を提供する。
【００１３】
タフピッチ銅とは、酸素を１００〜５００ｐｐｍ程度含む純度が９９．９０％以上の銅をいうが、通常は酸素を２００〜４００ｐｐｍ含む。
錫やインジウムは酸素との親和力の高い元素であり、これを純銅に添加したとき、固溶体を形成し、銅の軟化温度を上昇させる。しかし、酸素含有量が多いタフピッチ銅に添加した場合、添加元素が酸化して酸化物となり銅中に固溶せず、結果として軟化温度は向上しないと考えられていたが、冷却が急速であれば、微量が強制的に固溶して軟化温度を向上させることができる。その添加量は、含有量が重量で５ｐｐｍ以上、２００ｐｐｍ未満になるようにする。含有量が５ｐｐｍ未満であると、銅材の軟化温度の上昇が小さく、伸線の際の断線や、伸線後の室温保管での経時変化による引張り強度や伸びの減少を充分に防止することができない。一方、２００ｐｐｍ以上の含有量とすると、溶銅中の酸素存在下での固溶限度を超える添加となり、軟化温度は向上するが、添加元素の酸化物が増加し、伸線時の断線の要因になる恐れがあるので好ましくない。
【００１４】
添加元素は、鋳造の際、母材であるタフピッチ銅の溶湯に添加する。鋳造にはＳＣＲ（ Southwire Continuous Rod ）法のような連続鋳造装置を用いることが好ましい。連続鋳造は、鋳造工程で冷却が急速に行なわれるため、添加元素が強制固溶され添加元素の効果が大きい。
【００１５】
【発明の実施の形態】
以下に、本発明の実施例を詳細に説明する。
ＳＣＲ連続鋳造装置を用いて２００〜４００ｐｐｍの酸素を含むタフピッチ銅を鋳造し、得られた鋳造材を冷間圧延して直径８ｍｍの荒引き線を製作した。その鋳造の過程で溶銅中に錫とインジウムを量を変えて添加し、１２通りの試料を得た。
比較のため別に、６Ｎの純銅を小型連続鋳造機で鋳造して冷間圧延し、直径８ｍｍの荒引き線を製作した。
【００１６】
得られた各試料の錫及びインジウムの含有量をＩＣＰ分析により定量した結果、表１の通りであった。なお、タフピッチ銅をベースにした試料 No. １〜１２の酸素含有量は２００〜４００ｐｐｍの範囲内であった。
【００１７】
【表１】

【００１８】
得られた荒引き線の各試料を直径２．６ｍｍまで冷間伸線し、一旦焼鈍した後、直径０．９ｍｍまで冷間伸線し、焼鈍後、さらに直径０．０４ｍｍまで冷間伸線した。その後、最大５０日まで室温で保管し、焼鈍して極細エナメル線（１ＵＥＷ 0.04 ）とした。
【００１９】
No. １〜５、および No. ９〜１２のものは伸線の過程で断線を全く生じなかったが、添加元素を含有しないか添加元素の量の少ないNo.６、７、８およびNo.１３のものは軟化による断線を生じた。
【００２０】
直径２．６ｍｍまで冷間伸線して得られた各試料を１２０℃から４００℃の間の温度で１時間、ソルトバス中で熱処理し、引張り試験機を用いて引張り速度20mm／minで引張り強さを測定した。その結果の一部を図１に示す。
図１はNo. ４と No. ６の結果であり、図中、σ_Ｂ（20℃）は伸線したままの銅材（温度20℃）の引張り強さを、σ_Ｂ（400℃）は完全焼鈍材（熱処理温度４００℃）の引張り強さをそれぞれ表わす。引張り強さが伸線したままの銅材（σ_Ｂ（20℃））と完全焼鈍材（σ_Ｂ（400℃））のちょうど中間の値［σ_Ｂ（20℃）＋σ_Ｂ（400℃）］／２になるような熱処理温度を半軟化温度とすると、本発明によるNo. ４のものは、タフピッチ銅だけのNo.６よりも半軟化温度が２０℃高い。このようにして半軟化温度により各試料を評価すると共に、各試料について導電率を測定した。それらの結果を表２に示す。
【００２１】
【表２】

【００２２】
本発明による銅材No.１からNo.５までは、いずれもタフピッチ銅だけのNo.６より半軟化温度が１０〜２０℃高かった。添加元素含有量の少ない銅材No.７とNo.８の半軟化温度はNo.６と同じであり、添加元素含有量が多くても極端に多い場合（ No. １２）を除き、 No. ４及び No. ５と同等であった。一方、添加元素の錫を極端に多く添加した銅材No.１２の半軟化温度は大きく向上した。これは酸化物とならなかった錫が固溶したためである。しかし、この場合には導電率の低下をまねいた。また、このもののように半軟化温度が高いと、極細エナメル線用の軟銅線として用いる場合に、焼鈍が難しくなるという問題が生じる。
【００２３】
次に、直径０．０４ｍｍまで冷間伸線した試料の一部のもの（ No. ２、３、５〜７及び１３）について、保管前後での機械的特性（引張り強さ、伸び）を測定すると共に、それらを焼鈍してエナメル線（１ＵＥＷ0.04）としたときの機械的特性を測定した。その結果を表３及び表４に示す。
【００２４】
【表３】

【００２５】
【表４】

【００２６】
表３に見られるように、本発明によるものは冷間伸線後５０日室温で保管しても機械的特性がほとんど低下しなかった。これに対して、比較例によるものは著しく低下した。
【００２７】
また、表４に見られるように、本発明によるものは５０日保管後に焼鈍しても、保管による機械的特性の低下は僅かであった。これに対し、比較例のものの機械的特性は大幅に低下した。
【００２８】
本発明によるものの金属組織は、冷間伸線後、５０日保管後、極細線焼鈍後、いずれも微細な結晶粒から成っていた。これに対し、比較例によるものの金属組織は、粗大粒と微細粒が混在していた。
【００２９】
【発明の効果】
本発明によれば、冷間伸線、伸線後の保管、極細線の焼鈍、どの過程でも金属組織に粗大粒が発生しないから、冷間伸線で軟化による断線が発生せず、断線を避けるために冷間伸線途中での焼鈍の回数を増やす必要もなく、製造コストを抑えることができる。また、伸線後の保管や極細線の焼鈍による線材の機械的特性の劣化がない。このことから本発明発明の極細銅線は極細エナメル線用の心線として有効である。
【図面の簡単な説明】
【図１】銅材の熱処理温度と引張強さの関係を示すグラフである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an extra fine copper wire, particularly an extra fine copper wire suitable for a core wire of an extra fine enamel wire, and a method of manufacturing the same.
[0002]
[Prior art]
Ultra fine enamel wires with a diameter of 0.02 to 0.05 mm are used for coils such as a stepping motor of a watch, a magnetic head for magnetic recording, and a flyback transformer for a cathode ray tube. The core of the ultra-fine enameled wire uses semi-softened ultra-fine annealed copper wire made of high-purity copper (hereinafter referred to as pure copper) with an oxygen content of 0.1% or less, such as tough pitch copper and oxygen-free copper. It has been.
[0003]
The ultra-thin annealed copper wire is drawn by drawing a rough drawn wire of pure copper in the cold, and after several annealing steps, it is drawn to the final wire diameter, softened through the annealing step, and then enameled. Become a product .
[0004]
One of the problems that arises when manufacturing this ultrafine copper wire is disconnection. Although this disconnection may be caused by inclusions in the material, the material softens due to frictional heat between the material and the wire drawing die during wire drawing, and may not be able to withstand the tension of drawing by the wire drawing die. Many. This type of disconnection is likely to occur when the degree of processing (cross-sectional reduction rate) is 95% or more. Therefore, the smaller the wire diameter, the more likely it is affected .
[0005]
As a problem other than disconnection, there is a problem that the tensile strength and elongation of the copper wire drawn to the final wire diameter change with time, that is , their characteristic values decrease with storage time . This is due to the softening of the wire drawing material due to recrystallization at room temperature, particularly noticeable with oxygen-free copper with extremely low oxygen content , and even with tough pitch copper with relatively high oxygen content , the degree of wire drawing is high. In some cases this phenomenon is seen.
[0006]
Such recrystallisation is responsible for softening at room temperature by way of locally generated during the material and observing the metal structure of the recrystallization portion is characterized in that a particular particle to coarsen to grow. Annealing a copper material that does not cause softening at room temperature when a copper wire in such a state is annealed in the enamel wire manufacturing process, and fine particles are newly generated and mixed with coarse particles that already exist ( The metal structure has a problem that the tensile strength and elongation are reduced as compared with a uniform and fine recrystallized structure. The softening of the wire drawing material is more likely to occur as the degree of processing in the wire drawing process is higher and the storage temperature is higher.
[0007]
[Problems to be solved by the invention]
In order to reduce disconnection during wire drawing and softening due to room temperature storage, it is conceivable to reduce the degree of processing during wire drawing and increase the number of annealings during wire drawing . However, doing so will increase the production cost.
[0008]
It is therefore an object of the present invention, a tough pitch copper softening is not noticeable at a room temperature of drawn wire based, it is possible to suppress the breakage in wire drawing in the production process, the increase in annealing times during wire drawing, production The object is to provide ultra-fine copper wire at a low cost.
[0009]
Another object of the present invention is to provide a small small thin copper wires decrease in tensile strength and elongation by aging at room temperature storage.
[0010]
Still another object of the present invention is to provide a method for producing the ultrafine copper wire as described above .
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a copper material in which one or more metals of tin and indium are contained in a tough pitch copper having an oxygen content of 200 to 400 ppm in a range of 5 ppm to less than 200 ppm in diameter of 0.02 to 0.0. Provided is an ultrafine copper wire composed of an annealed copper wire processed to 04 mm, with fine crystal grains, and a tensile strength of less than 35 kg / mm ² .
[0012]
Further, in order to achieve the above object , the present invention provides a tough pitch copper casting process in which oxygen content is 200 to 400 ppm, and at least 5 ppm to 200 ppm of one or more metals among tin and indium in the molten tough pitch copper. The production method of adding less than this, cold-drawing the obtained copper material to a diameter of 0.02-0.04 mm, and then annealing is provided.
[0013]
Tough pitch copper means copper having a purity of about 99 to 90% or more containing oxygen of about 100 to 500 ppm, but usually contains 200 to 400 ppm of oxygen.
Tin or indium is an element having a high affinity for oxygen, and when added to pure copper, it forms a solid solution and raises the softening temperature of copper. However, when added to tough pitch copper with a high oxygen content, it was thought that the additive element oxidized and became an oxide and did not dissolve in the copper, resulting in a softening temperature not improving. In this case, a small amount can be forcibly dissolved to improve the softening temperature. The addition amount is set so that the content is 5 ppm or more and less than 200 ppm by weight. If the content is less than 5 ppm, the increase in softening temperature of the copper material is small, and it is possible to sufficiently prevent disconnection during wire drawing and decrease in tensile strength and elongation due to changes over time in room temperature storage after wire drawing. I can't. Meanwhile, 200 ppm or more content and result becomes a added exceeding a solid solubility limit in the presence of oxygen in the molten copper, the softening temperature is improved, increased oxide of additive elements, causes breakage during wire drawing It is not preferable because there is a risk of becoming .
[0014]
The additive element is added to the molten tough pitch copper as a base material during casting. Preferably Rukoto using a continuous casting apparatus, such as a SCR (Southwire Continuous Rod) method for casting. In continuous casting, cooling is rapidly performed in the casting process, so that the additive element is forcibly solid-solved and the effect of the additive element is great.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the present invention will be described in detail below.
Tough pitch copper containing 200 to 400 ppm of oxygen was cast using an SCR continuous casting apparatus, and the resulting cast material was cold-rolled to produce a rough drawn wire having a diameter of 8 mm. During the casting process, tin and indium were added in various amounts to the molten copper to obtain 12 samples .
Separately, 6N pure copper was cast by a small continuous casting machine and cold-rolled to produce a rough drawing wire having a diameter of 8 mm .
[0016]
The tin and indium contents of the obtained samples were quantified by ICP analysis. In addition, oxygen content of sample No. 1-12 based on tough pitch copper was in the range of 200-400 ppm .
[0017]
[Table 1]

[0018]
Each sample of the resulting rough drawing wire was cold-drawn to a diameter of 2.6 mm, once annealed, then cold-drawn to a diameter of 0.9 mm, and after annealing, the wire was further drawn to a diameter of 0.04 mm. did. Thereafter , it was stored at room temperature for up to 50 days and annealed to obtain an ultra-fine enameled wire (1UEW 0.04 ) .
[0019]
No. 1-5 and No. 9-12 did not break at all in the process of wire drawing, but No. 6, 7, 8 and No. 13 those yielded disconnection due softened.
[0020]
Each sample obtained by cold drawing to a diameter of 2.6 mm was heat-treated in a salt bath at a temperature between 120 ° C. and 400 ° C. for 1 hour, and pulled at a pulling rate of 20 mm / min using a tensile tester. Strength was measured. A part of the result is shown in FIG.
Fig. 1 shows the results of No. 4 and No. 6. In the figure, σ _B (20 ° C) is the tensile strength of the drawn copper material (temperature 20 ° C), and σ _B (400 ° C) is Represents the tensile strength of a fully annealed material (heat treatment temperature 400 ° C.) . The intermediate value between the copper material (σ _B (20 ° C)) and the fully annealed material (σ _B (400 ° C)) with the tensile strength being drawn [σ _B (20 ° C) + σ _B (400 ° C)] Assuming that the heat treatment temperature to be / 2 is the semi-softening temperature, the semi-softening temperature of No. 4 according to the present invention is 20 ° C. higher than that of No. 6 consisting only of tough pitch copper . Thus, each sample was evaluated by the semi-softening temperature , and the conductivity was measured for each sample. The results are shown in Table 2.
[0021]
[Table 2]

[0022]
In the copper materials No. 1 to No. 5 according to the present invention, the semi-softening temperature was 10 to 20 ° C. higher than No. 6 containing only tough pitch copper . The semi-softening temperatures of copper materials No. 7 and No. 8 with low additive element content are the same as No. 6 , except for cases where the additive element content is high but extremely high ( No. 12) . 4 and No. 5. On the other hand, the semi-softening temperature of copper material No. 12 to which an extremely large amount of the additive element tin was added was greatly improved . This is because tin that did not become an oxide was dissolved. However, in this case, the electrical conductivity was reduced. Moreover, when the semi-softening temperature is high like this, there is a problem that annealing becomes difficult when used as an annealed copper wire for an ultrafine enamel wire .
[0023]
Next, mechanical properties (tensile strength, elongation) before and after storage were measured for some of the samples ( No. 2, 3, 5-7 and 13) that were cold-drawn to a diameter of 0.04 mm . At the same time, the mechanical properties were measured when they were annealed to obtain enameled wire (1 UEW 0.04). The results are shown in Tables 3 and 4 .
[0024]
[Table 3]

[0025]
[Table 4]

[0026]
As seen in Table 3, by the present invention the mechanical properties even when stored at room temperature 50 days after cold drawing was not substantially decrease. On the other hand, the value according to the comparative example was significantly reduced.
[0027]
Further, as seen in Table 4 , even when the sample according to the present invention was annealed after storage for 50 days, the mechanical properties were not significantly decreased by storage. On the other hand, the mechanical properties of the comparative example were significantly reduced.
[0028]
The metal structures according to the present invention consisted of fine crystal grains after cold drawing, after storage for 50 days, and after ultrafine wire annealing. On the other hand, in the metal structure of the comparative example , coarse grains and fine grains were mixed.
[0029]
【The invention's effect】
According to the present invention , since cold grain drawing, storage after drawing, annealing of ultra fine wire, coarse grains do not occur in the metal structure in any process, disconnection due to softening does not occur in cold drawing, In order to avoid this, it is not necessary to increase the number of times of annealing in the middle of cold drawing, and the manufacturing cost can be suppressed. Further, there is no deterioration of the mechanical properties of the wire due to storage after drawing or annealing of the fine wire. Therefore, the ultrafine copper wire of the present invention is effective as a core wire for an ultrafine enamel wire.
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between the heat treatment temperature and tensile strength of a copper material.

Claims

A tough pitch copper having an oxygen content of 200 to 400 ppm is composed of an annealed copper wire obtained by processing a copper material containing one or more metals of tin and indium from 5 ppm to less than 200 ppm into a diameter of 0.02 to 0.04 mm. Is an ultrafine copper wire characterized by being fine and having a tensile strength of less than 35 kg / mm ² .

Oxygen content in the casting process of tough pitch copper 200～400Ppm, added below the tough pitch copper melt one or more metals of 5ppm or more of tin and indium 200 ppm, diameter 0.02 the resulting copper material A method for producing an ultrafine copper wire, characterized by annealing after cold drawing to 0.04 mm .

3. The method for producing an ultrafine copper wire according to claim 2 , wherein the casting in the casting process is casting using a continuous casting apparatus.