JP4057162B2

JP4057162B2 - High strength, high conductivity, high Cr content copper alloy

Info

Publication number: JP4057162B2
Application number: JP26453798A
Authority: JP
Inventors: 毅樋口
Original assignee: THE FURUKAW ELECTRIC CO., LTD.
Current assignee: THE FURUKAW ELECTRIC CO., LTD.
Priority date: 1998-09-18
Filing date: 1998-09-18
Publication date: 2008-03-05
Anticipated expiration: 2018-09-18
Also published as: JP2000096163A

Description

【０００１】
【発明の属する技術分野】
本発明は高強度、かつ高導電性の銅合金に関する。
【０００２】
【従来の技術】
半導体リードフレーム、種々の電気電子機器、車載用端子・コネクター、リレースイッチ等の電子部品端子材、電極材、ヒートシンク材には、銅が有する高導電性に加えて高強度が必要とされるため、高強度、高導電性を有する銅合金の開発が要望されている。さらに、機器の小型化、高性能化などに伴い、高導電性と共にさらなる強度の向上及び耐熱性が要求されている。しかし、従来の固溶強化、析出強化を中心とした銅合金は、高導電率のものは強度が低く、高強度のものは導電率が低いという関係があった。
これに対し、特開平９−１０４９３５号には高Ｃｒ含有銅合金が提案されている。この銅合金は、Ｃｒを１０重量％以上含有し、凝固時に晶出したＣｒを冷間加工によりファイバー状にすることによって高強度高導電性を達成した銅合金（以下、Ｃｕ−Ｃｒ複相合金と称す）である。この銅合金は２相であるため、冷間加工時に加工歪みが多く蓄積され、冷間加工後の高強度を達成している。しかし、これは、導電率回復等のために熱処理を行うと、蓄積された加工歪み状態が一気に解放されるため、強度が落ちてしまうという問題がある。
また、Ｃｕ−Ｃｒ複相合金は２相であるため、合金材に高強度を発現させるには９９％以上の強加工を行い加工歪みを蓄積する必要があった。
【０００３】
【発明が解決しようとする課題】
したがって本発明は、Ｃｕ−Ｃｒ複相合金において高温耐熱性の改善と所望の強度を得るために必要な冷間加工率を低減させ（以下、冷間加工の低減と称す）、実用上好適な高強度、高導電性の高Ｃｒ含有銅合金を提供することを目的とする。
【０００４】
【課題を解決するための手段】
すなわち本発明は、
（１）Ｃｒを５〜３０質量％含有し、その金属組織において凝固時に晶出したＣｒがアスペクト比５以上のファイバー状であり、かつ、そのＣｒファイバー間のＣｕ母相に、粒径１００μｍ以下の、炭化物、酸化物、窒化物及びホウ化物からなる群から選ばれた少なくとも１種を０．０１〜１質量％の量分散させた組織を有してなることを特徴とする高Ｃｒ含有銅合金、および
（２）Ｃｒを５〜３０質量％含有し、その金属組織において凝固時に晶出したＣｒがアスペクト比５以上のファイバー状であり、かつ、そのＣｒファイバー間のＣｕ母相に、粒径１００μｍ以下の、炭化物、酸化物、窒化物及びホウ化物からなる群から選ばれた少なくとも２種を０．０１〜１質量％の量分散させた組織を有してなり、残部がＣｕであることを特徴とする高Ｃｒ含有銅合金
を提供するものである。
【０００５】
なお本明細書中、高温耐熱性とは熱処理後の強度が低下しないことをいい、アスペクト比とは、長さ／等価直径（晶出物と同じ断面積を有する円の直径）の比を表すものとする。
【０００６】
【発明の実施の形態】
本発明の銅合金はＣｒを５〜３０質量％、好ましくは１０〜２０質量％含有する。その金属組織において、Ｃｒは、アスペクト比が５以上、好ましくは２０以上のファイバー状で含有される。Ｃｒの含有量が５質量％未満では良好なファイバー状態を得ることができず、また３０質量％を越えると健全な鋳塊組織が得られず、熱間加工で割れてしまう。
【０００７】
本発明の銅合金において、Ｃｒファイバー間のＣｕ母相には、炭化物、酸化物、窒化物、ホウ化物又はこれらのうち２種類以上の混合物が分散されている。この炭化物として好ましくは、Ｃｒ₃Ｃ₂、Ｃｒ₇Ｃ₃、ＳｉＣ、ＴｉＣ、酸化物として好ましくは、Ｃｒ₂Ｏ₃、Ａｌ₃Ｏ₃、ＳｉＯ₂、ＣａＯ、ＭｇＯ、窒化物として好ましくは、ＣｒＮ、ＢＮ、Ｓｉ−Ｎ、ホウ化物として好ましくは、ＣｒＢ、ＢＮがある。これらは、粒径が通常１００μｍ以下である。径の下限は特に制限はない。０．１μｍ程度でも効果があり、それ以下でもよい。また、これらは、合金中に通常０．０１〜１質量％、好ましくは０．０５〜０．２質量％の割合で含有される。
【０００８】
これらの添加物はＣｕ母相側に分散されることによって、冷間加工時においてはＣｕ母相の動的回復を抑制し、また冷間加工によって導入される加工歪みを蓄積しやすくする。そのため本発明の銅合金は、低加工率でも高強度材とすることができる。また、熱処理時においては、前記添加物はＣｕ母相の再結晶を抑制することによって加工歪みを解放しにくくさせ、耐熱性を向上させる。これらの効果は添加物の粒径がＣｕ母相の銅の粒径以上では効果が小さいので、１００μｍ以下が効果的となる。
【０００９】
本発明で用いられる上記の添加物が合金中、０．０１質量％未満では加工率の低減及び耐熱性向上の効果が認められず、また含有率が１質量％を越えると冷間加工で変形するＣｒの変形に支障を及ぼすため、加工が困難になってしまう。なお、本発明で用いられる添加物の種類によるこれらの効果の差異はほとんどない。
【００１０】
本発明の高Ｃｒ含有銅合金の製造方法について説明する。
銅、高純度Ｃｒと所定の炭化物、酸化物、窒化物又はホウ化物の粉末を所定割合で溶製し、次いで鋳塊とする。
次いで例えば９００℃で再加熱後７０％以上の減面率で熱間加工、溶体化処理（例えば１０００℃、１時間）を行い、ついで冷間加工を行う。冷間加工率ならびに添加粒子量を適宜制御することによって、所望のアスペクト比にすることができる。また溶湯中に添加した粒子は、熱間加工により、均一に分散させる。
本発明の銅合金を加工して得られる加工材の形状としては特に制限はないが、例えば線材、板材、棒材が挙げられる。
【００１１】
【実施例】
次に、本発明を実施例に基づきさらに詳細に説明する。
高周波真空溶解炉にて電気銅、高純度Ｃｒと所定の炭化物、酸化物、窒化物、ホウ化物又はこれらのうち２種類以上からなる混合物の粉末を銅箔に包んで添加して溶製し、４５ｍｍ×４５ｍｍ×１２０ｍｍの約２ｋｇの鋳塊を作製した。ここでは、Ｃｒ₃ Ｃ₂ 、Ｃｒ₇ Ｃ₃ 、ＳｉＣ、ＴｉＣ、Ｃｒ₂ Ｏ₃ 、Ａｌ₃ Ｏ₃ 、ＳｉＯ₂ 、ＣａＯ、ＭｇＯ、ＣｒＮ、ＢＮ、ＳｉＮ、ＣｒＢのそれぞれ＃３２０メッシュ（＜４４μｍ）の粉体を準備した。これらの鋳塊を９００℃にて減面率７５％の熱間加工を行い、１０００℃、１時間の溶体化処理を施した後、２０ｍｍ×２０ｍｍ×４００ｍｍの試供材を作製した。試供材は溝ロールとダイスを用いて、後記の表１に示す冷間加工率で冷間加工を行い、線材へ加工した。ここで加工率は、加工限界に達する直前の加工率、すなわち、内径ｄ₁ 、ｄ₂ 、・・・ｄ_n 、ｄ_n+1 、・・・のダイスを順次通過させて冷間加工するに際して、ｄ_n+1 のダイス通過時に断線したとすると、ｄ_n のダイス通過時までの加工率である。この線材に４００〜６００℃で０．５〜３時間の熱処理（真空度：＜１０^-4Ｔｏｒｒ）を加え試験材を作製した。
【００１２】
作製した試験材の組成及び各特性の評価結果を表１に示す。
表中、熱間加工性試験において、各試験材を熱間加工して、加工中に割れた場合を×、割れなかった場合を○と表記した。また、冷間加工性試験において、各試験材を冷間加工して、加工中に６０％以下の加工率で割れた場合を×、６０％以上９９％までの加工率で割れた場合を△、９９％以上の加工率での加工が可能であった場合を○と表記した。
また、冷間加工が６０％以上の加工率で可能であった試験材は加工限界直前の試験材から引張試験片を作製し、引張強さをＪＩＳ−Ｚ２２４１に準じて測定した。また、真空焼鈍炉（真空度：＜１０^-4Ｔｏｒｒ）で５００℃で１時間の等時時効を行った材料を準備し、各材料の導電率を四端子法を用いて端子間距離＝２００ｍｍ、２９３Ｋの恒温槽中で測定した。なお、Ｃｒ含有率、添加物の含有率及びアスペクト比を変えた以外は同様にして作製した比較例の組成及び各特性の評価結果も表１にあわせて示した。
【００１３】
【表１】

【００１４】
表１において、Ｃｒ含有率を５質量％未満、かつ、アスペクト比を５未満とした試験材Ｎｏ．２６は熱間加工性、冷間加工性は良好であるが、冷間加工率が９９％以上であり、引張強さも劣っている。また、Ｃｒ含有率を３０質量％より大とした試験材Ｎｏ．２８はファイバー状の金属組織が得られず、熱間加工性及び冷間加工性に劣り、実用上使用できない。また、添加物含有率を０．０１質量％未満とした試験材Ｎｏ．２９は、添加物を添加していない試験材Ｎｏ．２７と比べても引張強さの改善はほとんど見られず、さらに、添加物を０．０１質量％以上添加した本発明の試験材（例えばＮｏ．６）と比べると、添加物を添加したことによる冷間加工率の低減及び引張強さの改善の効果がないことが明確にわかる。また、添加物含有率を１質量％より大とした試験材Ｎｏ．３０及びＮｏ．３１は、いずれも熱間加工性及び冷間加工性に劣り、実用上使用できない。一方、本発明の銅合金は、試験材Ｎｏ．１〜２５の結果からわかるように、冷間加工率を低減させ、高導電性かつ引張強さに優れた高Ｃｒ含有銅合金材に加工できる。
【００１５】
耐熱性を調べるために試験材Ｎｏ．１〜８、１０、１３、１６〜２５、２６、２７及び２９を不活性ガス雰囲気中で４００℃、４５０℃、５００℃、５５０℃、６００℃、６５０℃、７００℃で１時間焼鈍して、次いで湿式研磨により鏡面に仕上げて硬度測定を行った結果を表２に示す。硬度測定は、焼鈍を行っていない試験材（Ａｓ）と、それぞれの温度での焼鈍後材とをＪＩＳＺ２２４４に準じて荷重３００ｇｆで測定することにより行った。
【００１６】
【表２】

【００１７】
表２において、試験材Ｎｏ．２６、２７及び２９と、本発明の銅合金を加工した試験材Ｎｏ．１〜８、１０、１３及び１６〜２５を比較すると、本発明の銅合金を加工した合金材は硬度に優れており、特に６００〜７００℃の熱処理による硬度の低下が効果的に抑制されることがわかる。
【００１８】
【発明の効果】
本発明の高強度、高導電性の高Ｃｒ含有銅合金材は、冷間加工率の低減ができるのでコスト面で有利であり、また低加工率で高強度材が得られることはサイズの大きい材料を提供できることになり、実際の生産上も極めて有利である。また本発明のＣｒ含有銅合金は、耐熱性の向上により、実用上必要な各種熱処理を加えることができる。さらに、銅合金材を熱条件下で使用しても、硬度の劣化が小さい。したがって、本発明の合金は半導体リードフレームや様々な電気電子機器及び車載用端子・コネクターあるいはリレースイッチ等の電子部品端子材にも好適である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a copper alloy having high strength and high conductivity.
[0002]
[Prior art]
Semiconductor lead frames, various electrical and electronic equipment, terminal parts and connectors for automobiles, terminal materials for electronic components such as relay switches, electrode materials and heat sink materials require high strength in addition to the high conductivity of copper There is a demand for the development of a copper alloy having high strength and high conductivity. Furthermore, along with the downsizing and high performance of equipment, further improvement in strength and heat resistance are required in addition to high conductivity. However, the conventional copper alloys centering on solid solution strengthening and precipitation strengthening have a relationship that those having high conductivity have low strength and those having high strength have low conductivity.
In contrast, Japanese Patent Application Laid-Open No. 9-104935 proposes a high Cr content copper alloy. This copper alloy contains 10% by weight or more of Cr, and a copper alloy (hereinafter referred to as a Cu-Cr multiphase alloy) which achieves high strength and high conductivity by forming Cr as a fiber by cold working during solidification. It is called). Since this copper alloy has two phases, a lot of processing strain is accumulated during cold working, and high strength after cold working is achieved. However, there is a problem in that when heat treatment is performed to restore the conductivity, the accumulated work strain state is released at once, and the strength decreases.
Further, since the Cu—Cr double phase alloy has two phases, it is necessary to accumulate 99% or more of the hard work and accumulate work strain in order to develop high strength in the alloy material.
[0003]
[Problems to be solved by the invention]
Therefore, the present invention reduces the cold work rate required for improving the high temperature heat resistance and obtaining the desired strength in the Cu—Cr double phase alloy (hereinafter referred to as “reduction of cold work”), and is suitable for practical use. An object is to provide a high Cr-containing copper alloy having high strength and high conductivity.
[0004]
[Means for Solving the Problems]
That is, the present invention
(1) Containing 5 to 30% by mass of Cr, and Cr crystallized at the time of solidification in the metal structure is in a fiber shape with an aspect ratio of 5 or more, and the Cu matrix between the Cr fibers has a particle size of 100 μm or less. A high Cr content copper comprising a structure in which at least one selected from the group consisting of carbides, oxides, nitrides and borides is dispersed in an amount of 0.01 to 1% by mass. Alloys , and
(2) 5 to 30% by mass of Cr, and Cr crystallized at the time of solidification in the metal structure is in a fiber shape with an aspect ratio of 5 or more, and the Cu matrix between the Cr fibers has a particle size of 100 μm or less. A structure in which at least two selected from the group consisting of carbides, oxides, nitrides and borides are dispersed in an amount of 0.01 to 1% by mass, with the balance being Cu. A high Cr content copper alloy is provided.
[0005]
In this specification, high-temperature heat resistance means that strength after heat treatment does not decrease, and aspect ratio means a ratio of length / equivalent diameter (diameter of a circle having the same cross-sectional area as a crystallized product). Shall.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Copper alloy of the present invention is 5 to 30 mass% of Cr, preferably contain from 10 to 20 wt%. In the metal structure, Cr is contained in a fiber form having an aspect ratio of 5 or more, preferably 20 or more. If the Cr content is less than 5% by mass , a good fiber state cannot be obtained, and if it exceeds 30% by mass , a sound ingot structure cannot be obtained and cracking occurs during hot working.
[0007]
In the copper alloy of the present invention, a carbide, oxide, nitride, boride, or a mixture of two or more of these is dispersed in the Cu matrix between the Cr fibers. This carbide is preferably Cr ₃ C ₂ , Cr ₇ C ₃ , SiC, TiC, oxide is preferably Cr ₂ O ₃ , Al ₃ O ₃ , SiO ₂ , CaO, MgO, and nitride is preferably CrN , BN, Si—N, and boride are preferably CrB and BN. These usually have a particle size of 100 μm or less. There is no particular lower limit to the diameter. Even about 0.1 μm is effective, and it may be less. These are usually contained in the alloy in a proportion of 0.01 to 1% by mass , preferably 0.05 to 0.2% by mass .
[0008]
These additives are dispersed on the side of the Cu matrix phase, thereby suppressing the dynamic recovery of the Cu matrix phase during cold working and making it easy to accumulate processing strain introduced by cold working. Therefore, the copper alloy of the present invention can be made a high strength material even at a low processing rate. In addition, during the heat treatment, the additive suppresses recrystallization of the Cu matrix, thereby making it difficult to release the processing strain and improving the heat resistance. Since these effects are small when the particle diameter of the additive is equal to or larger than the copper particle diameter of the Cu parent phase, 100 μm or less is effective.
[0009]
If the additive used in the present invention is less than 0.01% by mass in the alloy, the effect of reducing the processing rate and improving the heat resistance is not recognized, and if the content exceeds 1% by mass , the alloy is deformed by cold working. This makes it difficult to work because it interferes with the deformation of Cr. In addition, there is almost no difference in these effects by the kind of additive used by this invention.
[0010]
The manufacturing method of the high Cr content copper alloy of this invention is demonstrated.
Copper, high-purity Cr and a predetermined carbide, oxide, nitride or boride powder are melted at a predetermined ratio and then formed into an ingot.
Next, for example, after reheating at 900 ° C., hot working and solution treatment (for example, 1000 ° C., 1 hour) are performed at a reduction in area of 70% or more, and then cold working is performed. A desired aspect ratio can be obtained by appropriately controlling the cold working rate and the amount of added particles. Further, the particles added to the molten metal are uniformly dispersed by hot working.
Although there is no restriction | limiting in particular as a shape of the processed material obtained by processing the copper alloy of this invention, For example, a wire, a board | plate material, and a bar are mentioned.
[0011]
【Example】
Next, the present invention will be described in more detail based on examples.
In a high-frequency vacuum melting furnace, electrolytic copper, high-purity Cr and a predetermined carbide, oxide, nitride, boride, or a mixture of two or more of these are wrapped in a copper foil, added and melted, An ingot of about 2 kg of 45 mm × 45 mm × 120 mm was produced. Here, Cr ₃ C ₂ , Cr ₇ C ₃ , SiC, TiC, Cr ₂ O ₃ , Al ₃ O ₃ , SiO ₂ , CaO, MgO, CrN, BN, SiN, and CrB are each # 320 mesh (<44 μm) Of powder was prepared. These ingots were hot-worked at 900 ° C. with a reduction in area of 75%, subjected to solution treatment at 1000 ° C. for 1 hour, and then 20 mm × 20 mm × 400 mm specimens were prepared. The sample material was subjected to cold working at a cold working rate shown in Table 1 to be processed into a wire rod using a groove roll and a die. Here, the processing rate is a processing rate immediately before reaching the processing limit, that is, when cold processing is performed by sequentially passing dies having inner diameters d ₁ , d ₂ ,..., D _n , d _{n + 1} ,. , D _{n + 1} , when the wire breaks, it is the processing rate until _dn passes. A heat treatment (vacuum degree: <10 ⁻⁴ Torr) at 400 to 600 ° C. for 0.5 to 3 hours was added to this wire to prepare a test material.
[0012]
Table 1 shows the composition of the prepared test material and the evaluation results of each characteristic.
In the table, in the hot workability test, each test material was hot-worked, and the case where it cracked during processing was indicated as x, and the case where it did not crack was indicated as ◯. Further, in the cold workability test, each test material was cold worked, and when it was cracked at a working rate of 60% or less during processing, x, when it was cracked at a working rate of 60% or more and 99%, Δ The case where processing at a processing rate of 99% or more was possible was indicated as ◯.
Moreover, the test material in which cold working was possible with the processing rate of 60% or more produced the tensile test piece from the test material just before a process limit, and measured the tensile strength according to JIS-Z2241. In addition, materials that were subjected to isochronous aging at 500 ° C. for 1 hour in a vacuum annealing furnace (vacuum degree: <10 ⁻⁴ Torr) were prepared, and the electrical conductivity of each material was measured using a four-terminal method. It measured in a 293K thermostat. Table 1 also shows the compositions of Comparative Examples prepared in the same manner except that the Cr content, the additive content, and the aspect ratio were changed, and the evaluation results of the characteristics.
[0013]
[Table 1]

[0014]
In Table 1, a test material No. 1 having a Cr content of less than 5% by mass and an aspect ratio of less than 5 was used. No. 26 has good hot workability and cold workability, but has a cold work rate of 99% or more and inferior tensile strength. Moreover, test material No. which made Cr content larger than 30 mass %. No. 28 does not give a fiber-like metal structure, is inferior in hot workability and cold workability, and cannot be used practically. Moreover, test material No. which made additive content rate less than 0.01 mass %. No. 29 is a test material No. to which no additive was added. The improvement in tensile strength was hardly seen even when compared with 27, and further, the additive was added as compared with the test material of the present invention to which the additive was added in an amount of 0.01 mass % or more (for example, No. 6) It can be clearly seen that there is no effect of reducing the cold working rate and improving the tensile strength by. In addition, the test material No. having an additive content greater than 1% by mass was used. 30 and no. No. 31 is inferior in hot workability and cold workability and cannot be used practically. On the other hand, the copper alloy of the present invention has a test material No. As can be seen from the results of 1 to 25, the cold working rate can be reduced, and the copper alloy material can be processed into a high Cr content copper alloy material having high conductivity and excellent tensile strength.
[0015]
In order to investigate the heat resistance, the test material No. 1-8, 10, 13, 16-25, 26, 27 and 29 were annealed at 400 ° C, 450 ° C, 500 ° C, 550 ° C, 600 ° C, 650 ° C and 700 ° C for 1 hour in an inert gas atmosphere. Table 2 shows the results of the hardness measurement after finishing a mirror surface by wet polishing. The hardness was measured by measuring a test material (As) that was not annealed and a material after annealing at each temperature with a load of 300 gf according to JIS Z 2244.
[0016]
[Table 2]

[0017]
In Table 2, test material No. Nos. 26, 27 and 29, and test materials No. 1 processed from the copper alloy of the present invention. Comparing 1 to 8, 10, 13 and 16 to 25, the alloy material obtained by processing the copper alloy of the present invention is excellent in hardness, and in particular, a decrease in hardness due to heat treatment at 600 to 700 ° C. is effectively suppressed. I understand that.
[0018]
【The invention's effect】
The high-strength, high-conductivity, high Cr-containing copper alloy material of the present invention is advantageous in terms of cost because it can reduce the cold work rate, and the fact that a high strength material can be obtained at a low work rate is large. Material can be provided, which is extremely advantageous in actual production. Further, the Cr-containing copper alloy of the present invention can be subjected to various heat treatments necessary for practical use due to the improvement of heat resistance. Furthermore, even when the copper alloy material is used under thermal conditions, the deterioration of hardness is small. Therefore, the alloy of the present invention is also suitable for semiconductor lead frames, various electric and electronic devices, and electronic component terminal materials such as in-vehicle terminals / connectors or relay switches.

Claims

Carbides containing 5-30% by mass of Cr, the Cr crystallized during solidification in the metal structure is in the form of fibers having an aspect ratio of 5 or more, and the Cu matrix between the Cr fibers has a particle size of 100 μm or less. , oxides, Ri name at least one member selected from the group consisting of nitrides and borides have 0.01 wt% of the amount distributed so tissue balance and wherein Cu der Rukoto High Cr content copper alloy.

Carbides containing 5-30% by mass of Cr, the Cr crystallized during solidification in the metal structure is in the form of fibers having an aspect ratio of 5 or more, and the Cu matrix between the Cr fibers has a particle size of 100 μm or less. And a structure in which at least two selected from the group consisting of oxides, nitrides and borides are dispersed in an amount of 0.01 to 1% by mass, and the balance is Cu. Cr-containing copper alloy.