JP4186095B2

JP4186095B2 - Copper alloy for connector and its manufacturing method

Info

Publication number: JP4186095B2
Application number: JP2000127182A
Authority: JP
Inventors: 邦彦智原; 樂凌; 章菅原
Original assignee: Dowa Holdings Co Ltd; Dowa Mining Co Ltd
Current assignee: Dowa Holdings Co Ltd
Priority date: 2000-04-27
Filing date: 2000-04-27
Publication date: 2008-11-26
Anticipated expiration: 2020-04-27
Also published as: JP2001303159A

Description

【０００１】
【発明の属する技術分野】
本発明は、コネクタ等の電気・電子部品用材料として好適な強度導電性を有し、さらにヤング率の小さい銅合金とその製造法に関するものである。
【０００２】
【従来の技術】
近年のエレクトロニクスの発達により、種々の機械の電気配線は複雑化、高集積化が進み、それに伴いコネクタ等の電気・電子部品用として使用される伸銅品材料が増加している。
また、コネクタ等の電気・電子部品は、軽量化、高信頼性、低コスト化が要求されている。よって、これらの要求を満たすために、コネクタ用銅合金材料は薄肉化され、また複雑な形状にプレスされるため、強度、弾性、導電性及びプレス成形性が良好でなければならない。
【０００３】
具体的には、端子において、挿抜時や曲げに対して座屈や変形しない強度、電線の加締め、保持に対する強度として、圧延方向の引張強さは６００Ｎ／ｍｍ² 以上、できれば７００Ｎ／ｍｍ² 以上、ばね限界値は４５０Ｎ/ｍｍ²以上、できれば５００Ｎ／ｍｍ²以上が好ましい。さらに、通電によるジュール熱発生を抑えるため、導電率は１８％ＩＡＣＳ以上が好ましい。また、端子の小型化によりプレス成形性の要求も厳しくなり、曲げ部半径（Ｒ）と板厚（ｔ）の比Ｒ／ｔが１以下を満足するような加工性が必要である。
【０００４】
また、従来はコネクタが小型化され、小さい変位で大きな応力が得られるよう材料のヤング率が大きいことが求められていたが、端子自身の寸法精度が厳しくなり、金型技術やプレスの操業管理、または材料の板厚や残留応力のバラツキ等、管理基準が厳しくなり、逆にコストアップを招いていた。そこで、最近はヤング率の小さい材料を用い、ばねの変位を大きくとる構造とし、寸法のばらつきを許容できる設計が求められてきている。したがって、圧延方向のヤング率が１２０ｋＮ／ｍｍ² 以下、好ましくは１１５ｋＮ／ｍｍ² 以下であることが求められてきている。
【０００５】
上記に加え、金型のメンテナンスの頻度もコストに占める割合が大きく、クローズアップされてきている。金型のメンテナンスの大きな要因として、工具の摩耗があげられる。素材をプレス加工（打ち抜きや曲げ）する際に、パンチ、ダイス、ストリッパー等の工具が摩耗し、加工材のバリ発生や寸法不良につながる。この際、素材自身の摩耗に与える影響も大きい。従って、金型摩耗性に対する材料側の改善要求も高くなってきている。
【０００６】
更に、耐食性、耐応力腐食割れ性に優れていることが必要であり、またメス端子に至っては、熱的負荷が加わることから、耐応力緩和特性に優れていなければならない。
具体的には、応力腐食割れ寿命は従来の黄銅一種の３倍以上、応力緩和率は１５０℃×５００時間で緩和率が黄銅一種の半分の２５％以下であることが望ましい。
【０００７】
従来、黄銅やりん青銅等が、コネクタ材として一般的に使用されていた。黄銅は低コストの材料として使用されているが、圧延方向の引張強さは質別がＥＨでも６００Ｎ／ｍｍ^２を越えず、また耐食性、耐応力腐食割れ性、耐応力緩和特性で劣っている。りん青銅は、強度、耐食性、耐応力腐食割れ性、耐応力緩和特性のバランスに優れている。しかしながら、導電率が例えばばね用りん青銅で１２％ＩＡＣＳと小さく、かつコスト的にも不利である。そこで多くの銅合金が研究、開発され提案されている。しかしながら、提案された多くの銅合金は、銅に微量な添加元素を加え、強度、電気伝導性、耐応力緩和特性等の特性をバランスさせたものであり、ヤング率については圧延方向で１２０〜１３５ｋＮ／ｍｍ^２と大きな値であり、またコストも高かった。
【０００８】
ここで、黄銅、りん青銅共に圧延方向のヤング率は１１０〜１２０ｋＮ／ｍｍ^２であり、小さいヤング率が前述設計の要求に合致し、最近またこれらの材料が見直されてきている。よって、黄銅に近い価格で、圧延方向のばね限界値４５０Ｎ／ｍｍ^２以上、引張強さ６００Ｎ／ｍｍ^２以上、導電率が１８％ＩＡＣＳ以上、ヤング率が１２０ｋＮ／ｍｍ^２以下、好ましくは１１５ｋＮ／ｍｍ^２以下である材料が切に望まれている。
【０００９】
【発明が解決しようとする課題】
本発明は、エレクトロニクスの発達にともない、コネクタ等の電気・電子部品用材料に要求される上記のような諸特性、すなわち、強度、導電率、ヤング率、耐応力緩和特性、耐応力腐食割れ性、プレス成形性、コスト等に優れたコネクタ用銅合金とその製造法を提供するものである。
【００１０】
【課題を解決するための手段】
本発明は、銅より安価な成分を添加することにより低コスト化を図りつつ、組成および熱処理条件を限定することによって、コネクタ等の電気・電子部品用材料に要求される上記のような諸特性、すなわち、強度、導電率、ヤング率、耐応力緩和特性、耐応力腐食割れ性、プレス成形性、コスト等に優れたコネクタ用銅合金を提供するものである。
【００１１】
本発明に係る銅合金の特徴をあげれば、次の通りである。
【００１２】
すなわち、
（１）Ｚｎ：２０〜４１mass％、Ｓｎ：0.1 〜4.0 mass％、Ｎｉ：0.1〜5.0mass％、Ｐ：0.01〜0.3mass％の範囲でかつ次式を満たしてなるＮｉ，Ｐを含み、
5.0≦Ｎｉ／Ｐ≦５０
ただし、Ｎｉ：Ｎｉの含有量（mass％）
Ｐ：Ｐの含有量（mass％）
残部がＣｕおよび不可避不純物からなり、圧延方向の引張強さが６００Ｎ／ｍｍ^２以上、導電率が１８％ＩＡＣＳ以上、ヤング率が１２０ｋＮ／ｍｍ^２以下、ばね限界値が４５０Ｎ／ｍｍ^２以上であることを特徴とするコネクタ用銅合金。
【００１３】
（２）前記コネクタ用銅合金において、Ｚｎ：２０〜４１mass％、Ｓｎ：0.1〜4.0mass％の範囲でかつ次式を満たしてなることを特徴とする上記（１）記載のコネクタ用銅合金。
6.0≦0.25Ｘ＋Ｙ≦１２
ただし、Ｘ：Ｚｎの含有量（mass％）
Ｙ：Ｓｎの含有量（mass％）
【００１４】
（３）前記銅合金よりなる金属材料の表面に、Ｃｕ下地：0.3〜2.0μｍ、Ｓｎ：0.5〜5.0μｍの表面処理を施したことを特徴とする上記（１）〜（２）記載のコネクタ用銅合金。
【００１５】
（４）Ｚｎ：２０〜４１mass％、Ｓｎ：0.1 〜4.0 mass％、Ｎｉ：0.1〜5.0mass％、Ｐ：0.01〜0.3mass％の範囲で、かつ次式を満たしてなるＮｉ，Ｐを含み、
5.0≦Ｎｉ／Ｐ≦５０
ただし、Ｎｉ：Ｎｉの含有量（mass％）
Ｐ：Ｐの含有量（mass％）
残部がＣｕおよび不可避不純物からなる銅合金材料を、３００〜７５０℃の温度で１〜３６０分間の熱処理後、加工率１０％以上で冷間加工した後に、２００〜６００℃で５秒間〜１８０分間の熱処理を施すことを特徴とする圧延方向の引張強さが６００Ｎ／ｍｍ^２以上、導電率が１８％ＩＡＣＳ以上、ヤング率が１２０ｋＮ／ｍｍ^２以下、ばね限界値が４５０Ｎ／ｍｍ^２以上であるコネクタ用銅合金の製造法。
【００１６】
（５）Ｚｎ：２０〜４１mass％、Ｓｎ：0.1〜4.0mass％、Ｎｉ：0.1〜5.0mass％、Ｐ：0.01〜0.3mass％の範囲で、かつ次式を満たしてなるＮｉ：Ｐを含み、
5.0≦Ｎｉ／Ｐ≦５０
ただし、Ｎｉ：Ｎｉの含有量（mass％）
Ｐ：Ｐの含有量（mass％）
残部がＣｕおよび不可避不純物からなる銅合金材料を、３００〜７５０℃の温度で１〜３６０分間の熱処理後、加工率１０％以上で冷間加工した後に２００〜６００℃で５秒間〜１８０分間の熱処理を施すことによって、圧延方向の引張強さが６００Ｎ／ｍｍ^２以上、導電率が１８％ＩＡＣＳ以上、ヤング率が１２０ｋＮ／ｍｍ^２以上、導電率が１８％ＩＡＣＳ以上、ヤング率が１２０ｋＮ／ｍｍ^２以下、ばね限界値が４５０Ｎ／ｍｍ^２以上にした後、当該銅合金材料の表面にＣｕ下地：0.3〜2.0μｍ、Ｓｎ：0.5〜5.0μｍの表面処理をした後に、１００〜２８０℃の温度で１〜１８０分間の熱処理を施すことを特徴とするコネクタ用銅合金の製造法。
【００１７】
（６）前記コネクタ用銅合金において、Ｚｎ：２０〜４１mass％、Ｓｎ：0.1〜4.0mass％の範囲で、かつ次式を満たしてなることを特徴とする上記（４）又は（５）記載のコネクタ用銅合金の製造法。
6.0≦0.25Ｘ＋Ｙ≦１２
ただし、Ｘ：Ｚｎの含有量（mass％）
Ｙ：Ｓｎの含有量（mass％）
【００１８】
（７）前記ばね限界値がピークになる熱処理温度よりも高い温度で冷間加工後に熱処理することを特徴とする上記（４）〜（６）記載のコネクタ用銅合金の製造法。
【００１９】
（８）前記製造法において、上記発明合金にＳｎを表面処理した材料のプレス打ち抜きくずを原料とする場合は、このプレス打ち抜きくずを３００〜６００℃の温度で0.5〜２４時間大気中または不活性ガス雰囲気中であらかじめ熱処理した後に溶解する上記（４）〜（７）記載のコネクタ用銅合金の製造法。
【００２０】
【作用】
次に、本発明の内容を具体的に説明する。
先ず、本発明銅合金における成分量限定理由につき説明する。
Ｚｎ：
Ｚｎを添加することにより、強度、ばね性が向上し、かつＣｕより安価であるため多量に添加することが望ましいが、４１mass％を超えると加工性、耐食性、耐応力腐食割れ性が低下する。さらにめっき性、はんだ付性が低下する。また、２０mass％より少ないと強度、ばね性が不足し、ヤング率が大きくなり、さらにＳｎを表面処理したスクラップを原料とした場合、溶融時の水素ガス吸蔵が多くなり、インゴットのブローホールが発生しやすくなる。また、安価なＺｎが少なく経済的にも不利になる。したがって、Ｚｎは、２０〜４１mass％の範囲であれば良い。好ましい範囲としては、２２〜３８mass％である。更に好ましい範囲としては、２４〜３０mass％であると、溶解鋳造時の凝固組織と熱間圧延との兼ね合いで生じる熱間割れを抑制できる。
【００２１】
Ｓｎ：
Ｓｎは微量で強度、弾性をはじめとした機械的特性を向上させる効果がある。また、Ｚｎの共存下で多くの銅合金系に比較し小さいヤング率を満足することができる。さらに、Ｓｎめっき等のＳｎを表面処理した材料の再利用の点からも添加元素として含有するのが好ましい。しかし、Ｓｎ含有量が増すと導電率が急激に低下し、また熱間加工性も低下する。導電率１８％ＩＡＣＳを確保するためには、4.0 mass％を越えない範囲でなければならない。また、0.1 mass％より少ないと以上のような効果が望めない。したがって、Ｓｎは、0.1 〜4.0 mass％の範囲であれば良い。好ましい範囲としては、0.5〜2.0mass％である。更に好ましい範囲としては、0.7〜1.3mass％であると、溶解鋳造時の凝固組織と熱間圧延との兼ね合いで生じる熱間割れを抑制できる。
【００２２】
Ｎｉ：
ＮｉはＣｕマトリックス中に固溶して強度、弾性、耐応力緩和特性を向上させる。またＰと化合物を形成して分散析出する事により電気伝導性も向上する。しかし、0.1 mass％より少ないと所望の効果は得られず、5.0 mass％を超えると導電率が低くなり、また経済的に不利になる。更に好ましい範囲としては、0.2 〜2.0 mass％である。
【００２３】
Ｐ：
ＰはＺｎ含有合金の耐食性を向上させるとともに、Ｎｉと化合物を形成して分散析出することにより、強度、弾性、耐応力緩和特性、耐応力腐食割れ性、電気伝導性を向上させる。0.01 mass％より少ないと上記の効果が充分に得られず、0.3 mass％を超えると電気伝導性、半田耐候性の低下が厳しく、鋳造性、熱間加工性に悪影響を及ぼす。具体的にはＺｎ、ＳｎとＰが共存すると著しく熱間加工性を低下させる。このためＮｉの添加が必要である。Ｎｉの共存下においても過剰なＰは前述のように製造性を著しく低下させる。したがって0.01〜0.3mass％とする。更に好ましい範囲としては0.02〜0.1mass％である。
【００２４】
ＮｉおよびＰの組成比について
本発明に係る銅合金においては、添加したＮｉ、Ｐの一部がＮｉ−Ｐ系化合物を形成し、これが均一微細に分散析出することにより電気伝導性および強度、弾性、耐応力緩和特性、耐応力腐食割れ性を向上させることが出来る。従ってＮｉとＰの比を限定することが望ましい。ＮｉとＰの比が5.0より少ないと所望の効果は得られず、また熱間加工性が著しく低下し、５０より大きいとＮｉ−Ｐ系化合物が粗大に析出し、強度、導電率、成形加工性が低下するなどの悪影響を及ぼす。
【００２５】
（１）式について
6.0≦0.25Ｘ＋Ｙ≦１２…（１）
ただし、Ｘ：Ｚｎの含有量（mass％）
Ｙ：Ｓｎの含有量（mass％）
なお（１）式において式の値が6.0より少ないと引張強さ等の強度が低下し、所望のヤング率が得られず、１２より大きいと導電率や成形加工性が低下するなどの悪影響を及ぼすことになる。
【００２６】
以上のようにして成分の範囲を限定することで圧延方向の引張強さ６００Ｎ／ｍｍ² 以上、導電率が１８％ＩＡＣＳ以上、ヤング率が１２０ｋＮ／ｍｍ²以下、ばね限界値が４５０Ｎ／ｍｍ²以上、さらにコネクタ材として必要な諸特性、具体的には耐食性、耐応力腐食割れ性（アンモニア蒸気中での割れ寿命が黄銅一種の３倍以上）、耐応力緩和特性（８０〜１２０℃における緩和率が黄銅一種の半分以下、りん青銅並）、成形加工性（Ｒ／ｔ≦1.0 の９０°Ｗ曲げにもクラック発生無し）等を満足するコネクタ用銅基合金を製造できる。
【００２７】
次に、本発明に係る製造条件の限定理由につき説明する。
本銅合金材料を３００〜７５０℃の温度で１〜３６０分間の熱処理後、加工率１０％以上で冷間加工した後、２００〜６００℃の温度で５秒〜１８０分間の熱処理を施した材料の表面に、Ｃｕ下地0.3 〜2.0 μｍ、Ｓｎ0.5 〜5.0 μｍの表面処理した後に、１００〜２８０℃の温度で１〜１８０分間の熱処理を施すとさらにコネクタ用材料としての特性を向上させることができる。
【００２８】
最終冷間加工前の焼鈍において、結晶粒径を５〜２０μｍに制御すればプレス成形性が向上するが、この時の処理温度は３００〜７５０℃が好ましい。３００℃未満の温度では再結晶に必要な温度としては低すぎ、処理時間が長くなり経済的でなく、７５０℃を超える温度では短時間で結晶粒が粗大化し結晶粒径の制御が難しい。
【００２９】
また、時間については、１〜３６０分間が好ましい。処理時間が短すぎると再結晶による結晶粒の制御が十分でなく、長すぎると結晶粒の成長、粗大化が起りやすくまた経済的にも不利になる。
【００３０】
また、最終冷間加工率は１０％以上が好ましい。１０％未満では加工硬化による強度、硬さ等の向上が十分でない。ただし、加工率が大きすぎると加工性が低下するので、好ましい範囲としては１０〜９０％とする。
【００３１】
この後、２００〜６００℃の温度で５秒〜１８０分間熱処理する。この熱処理により、材料のばね限界値、耐応力緩和特性、耐応力腐食割れ性、導電率、曲げ加工性を向上させる。２００℃未満の温度ではこのような効果が充分でなく、６００℃を超える温度では急速に強度が低下する。また時間については、５秒〜１８０分間が好ましい。処理時間が短すぎると上記の効果が十分でなく、長すぎると経済的に不利になる。
【００３２】
この時ばね限界値がピークになる熱処理温度よりも高い温度で熱処理することで耐応力緩和特性、耐応力腐食割れ性、加工性を向上させることができる。ただし、熱処理温度が高すぎると引張強さ、ばね限界値が急激に低下するため、ばね限界値がピーク値の７０から１００％の間になるような熱処理条件が望ましい。
【００３３】
このようにして得られた材料に、表面処理としてＣｕ下地を0.3 から2.0 μｍ、Ｓｎ表面処理を0.5 〜5.0 μｍ施す。Ｃｕ下地は0.3 μｍ未満では、合金中のＺｎが表面処理層および表面に拡散し酸化することによる接触抵抗の増加やはんだ付け性の低下を防止する効果が少なく、2.0 μｍを超えても効果が飽和しまた経済的でもなくなる。ただし、Ｃｕ下地めっきは、純Ｃｕであることに限らず、Ｃｕ−ＦｅやＣｕ−Ｎｉ等の銅合金でも良い。
【００３４】
Ｓｎ表面処理層は、0.5 μｍ未満では耐食性、特に耐硫化水素性が不十分であり、また5.0 μｍを超えても効果が飽和し経済的にも不利となる。さらに、これらの表面処理は電気めっきによって実施すれば、膜厚の均一性、経済性の面から好ましい。表面処理後に光沢をだすためにリフロー処理を施してもよい。この処理はさらにウイスカ対策にも有効である。
【００３５】
この表面処理材を１００〜２８０℃の温度で１〜１８０分間熱処理する。この熱処理によって材料のばね限界値、加工硬化指数が向上する。加工硬化指数が増加すると、曲げ加工によりコネクタばね部を成形する際に、ばね部の硬化によってばね性が向上することになる。また素材の表面処理層に硬いＣｕ−Ｓｎ系金属間化合物層が形成されることで、コネクタとして用いた際に、耐磨耗性の向上および挿抜力の低下が実現でき、さらにウイスカ対策にも有効である。１００℃未満の温度ではこのような効果が十分でなく、２８０℃を超えると拡散や酸化により、接触抵抗、はんだ付け性、加工性が低下する。また、熱処理時間が１分間未満では効果が十分でなく、１８０分間を超えると拡散や酸化による前述の特性低下が起こりまた経済的でもない。
【００３６】
本発明合金にＳｎを表面処理した材料のプレス打ち抜きくずを原料として溶解するに際し、３００〜６００℃の温度で0.5〜２４時間、大気中または不活性雰囲気中で熱処理した後に溶解する。３００℃未満の温度では、プレスくずに付着したプレス油の燃焼が不十分であり、また保管中に吸着した水分の乾燥が不十分であり、この後急激に温度を上昇させ溶解作業に入ると、分解により生成した水素を溶湯中に吸収しブローホール発生の原因となる。
【００３７】
また、６００℃を超える温度では、酸化が急激に進みドロス発生の原因となる。このドロスは溶湯の粘性を高め鋳造性を低下させる。従って、熱処理温度は３００〜６００℃の範囲とする。0.5時間未満の時間では、プレス油の燃焼や水分の乾燥が十分でなく、２４時間を超えると母材のＣuがＳｎ表面処理層に拡散し酸化し、Ｃｕ−Ｓｎ−Ｏ系の酸化物を形成しドロスの原因となり、また経済的でもない。したがって熱処理時間は0.5〜２４時間の範囲とする。また、雰囲気は大気中で不十分であるが、不活性ガスでシールした方が酸化防止の面から好ましい。
ただし、還元ガス中では高温になると水分の分解による水素の吸収、拡散によって不利になる。次に本発明の実施の形態を実施例により説明する。
【００３８】
【発明の実施の形態】
実施例１
表１に化学成分（mass％）を示す銅合金Ｎｏ．１〜１６を高周波誘導溶解炉を用いて溶製し、４０×４０×１５０（ｍｍ）の鋳塊に鋳造した。ただし、溶解鋳造時の雰囲気はＡｒガス雰囲気とし、鋳造後直ちに水冷した。
その後、各鋳塊を熱間圧延後、冷間圧延と焼鈍を繰り返し、厚さ0.50ｍｍとした。そして、４５０℃の温度で６０分間熱処理材後、水急冷を行い、さらに酸洗を施した。上記のように得られた熱処理材を厚さ0.25ｍｍまで冷間圧延した後、各温度条件で３０分間の焼鈍を行い、酸洗を施したものを試験材とした。
【００３９】
以上のようにして得られた試験材を用いて圧延方向のビッカース硬さ、引張強さ、ヤング率、曲げ限界値および導電率を測定すると共に、応力緩和特性を調査した。また曲げ加工性に関しては圧延方向と、圧延方向に対して垂直な方向について調査した。ビッカース硬さ、引張強さ、ヤング率、ばね限界値および導電率の測定は、それぞれＪＩＳ−Ｚ−２２４４、ＪＩＳ−Ｚ−２２４１、ＪＩＳ−Ｈ−３１３０、ＪＩＳ−Ｈ−０５０５に従った。
【００４０】
応力緩和試験は試験片の中央部の応力が、４００Ｎ／ｍｍ^２になるようにアーチ状に曲げ１５０℃の温度で５００時間保持後の曲げぐせを応力緩和率として次式により算出した。
応力緩和率（％）＝［（Ｌ₁ −Ｌ₂ ）／（Ｌ₁ −Ｌ₀ ）］×１００
ただし、Ｌ₀ ：治具の長さ（ｍｍ）
Ｌ₁ ：開始時の試料長さ（ｍｍ）
Ｌ₂ ：処理後の試料端間の水平距離（ｍｍ）
【００４１】
曲げ加工性は、９０°Ｗ曲げ試験（ＣＥＳ−Ｍ−０００２−６、Ｒ＝ 0.25 ｍｍ、Ｒ／ｔ＝1.0 、Ｗ＝１０ｍｍ、圧延方向および垂直方向）を行い、中央部の山表面が、良好なものを○印、しわの発生したものを△印、割れの発生したものを×印として評価した。
【００４２】
【表１】

【００４３】
表１に示した結果から、本発明に係るＮo.1〜９の銅合金は、引張強さ、ヤ
ング率、導電率のバランスに優れ、また曲げ加工性も良好である。したがって、コネクタ等の電気・電子用材料として非常に優れた特性を有する銅合金である。
また、Ｎo.５に比べて焼鈍温度を上昇させたりＮo.９は引張強さ、ばね限界値が減少している代わりに、ヤング率、耐応力緩和特性、曲げ加工性が向上していることが分る。
【００４４】
これに対して、Ｚｎ、Ｓｎ含有量が（１）式で規定するより小さいＮo.１０は、引張強さ、ヤング率に劣り、Ｚｎ、Ｓｎ含有量が（１）に規定する大きいＮo.１１は導電率、応力緩和率、曲げ加工性に劣っている。
本発明合金よりＮｉ：Ｐ比の大きいＮo.１２はヤング率が大きく、導電率が低い。
また、曲げ加工性にも劣っている。本発明合金よりＮｉ：Ｐ比の小さいＮo.１３は応力緩和率、曲げ加工性にも劣っている。これはＰ量が多く、Ｎｉ：Ｐ比が小さく、Ｎｉ−Ｐ系化合物の析出が過度に多くなり、曲げ加工性、応力緩和特性が低下したものと考えられる。また熱間圧延時にひび割れが入り、歩留り良く最終板厚まで圧延できなかった。
本発明合金よりＰ量の多い、Ｎo.１４は引張強さ、ばね限界値、ヤング率、導電率、曲げ加工性に劣っている。さらには著しい熱間加工性の低下により歩留りが極めて悪かった。本発明合金よりＮｉ量の多いＮo.１５はヤング率、導電率に劣っている。
Ｎo.１６はＮo.９よりさらに熱処理温度を高くした試料であるが、引張強さ、ばね限界値が大きく低下している。
【００４５】
実施例２
実施例１の表１中に示す本発明合金Ｎo.２と市販の黄銅１種（Ｃ２６００-ＥＨ）、りん青銅２種（Ｃ５１９１−ＥＨ）について、圧延方向の硬さ、引張強さ、ヤング率、導電率、応力緩和率及び応力腐食割れ寿命を試験測定した。また、圧延方向、圧延方向と垂直方向の曲げ加工性を調整した。
圧延方向の硬さ、引張強さ、ヤング率、導電率及び応力緩和率の測定試験は、実施例１と同様の測定法であり、応力腐食割れ時間は、試料に約４００Ｎ／ｍｍ^２の曲げ応力を負荷し、12.5％アンモニア水の入ったデシケータ内に暴露し割れが発生した時間である。
【００４６】
【表２】

【００４７】
表２に示す結果から、本発明の銅合金は、従来の代表的なコネクタ等の電気・電子用材料である黄銅に比較して強度、ヤング率、曲げ加工性、応力緩和特性、耐応力腐食割れ性が向上していることがわかる。りん青銅に比較しても、強度、曲げ加工性、ヤング率、導電率、応力緩和特性に優れている。さらにコスト面でも成分と製造工程から優れているといえる。したがって、本発明銅合金は従来の黄銅、りん青銅に比較しても十分に優れているといえる。
【００４８】
実施例３
表３に示す本発明合金条材を作製後、Ｃu下地めっきを0.5μｍ、Ｓｎめっきを1.0μｍ実施した後に、プレス打ち抜きした材料を溶解鋳造用の原料として準備した。鋳造における目標組成は表３とし、また溶解用の原料としてプレスくずは約１ｔ、残りは電気Ｃu、Ｚｎ、Ｎｉ、Ｐにより成分調整し約２ｔのインゴットを６本得た。得られたインゴットの成分はほぼ表３と同じであった。
【００４９】
ここで３本は、原料のプレスくずを４５０℃で３時間大気中で加熱した。残り３本は何も処理しなかった。これを急速に溶解し２ｔのインゴットを鋳造し、熱間圧延、冷間圧延、焼鈍を繰り返し、0.25ｍｍに仕上げた。このようにして得られた材料の全長を検査し、インゴットのブローホールに起因した欠点の個数を数えた（表４）。
表４より、プレスくずを本発明法によって熱処理したものは欠点がなく優れていた。これに対して熱処理していないものは欠陥が発生しており、歩留まりに問題があるのが分かる。
【００５０】
【表３】

【００５１】
【表４】

【００５２】
実施例４
実施例１の表１中に示す本発明合金Ｎo.２に対してＣu下地めっき0.5μｍ、Ｓｎめっき1.1μｍを施した後、１９０℃の温度で６０ｍｉｎの熱処理を実施した。この材料とめっき処理後熱処理しなかったものに対して、圧延方向のばねの限界値を測定すると共に、９０°Ｗ曲げ試験（Ｒ＝ 0.25 ｍｍ、Ｒ／ｔ＝1.0、圧延方向）を行った後の試片の曲げ部断面の硬さの分布を調査した。また同様の調査を従来合金（黄銅１種比較材Ｃ２６００ＥＨ裸材）に対したものも行った。
【００５３】
【表５】

表５より、熱処理を行なうことで本発明合金のばね限界値は更に向上していることがわかる。また、変形しなかった定常部の硬さと変形した曲げ部の最大硬さを比べると、熱処理を行わなかった場合よりも硬化が大きく、コネクタばね部に有利であることがわかる。また黄銅と比較しても本発明合金はコネクタ用銅合金として十分に優れているといえる。
【発明の効果】
以上の実施例から明らかなように、本発明に係る銅基合金または本発明法によって得られた材料は、従来の黄銅やりん青銅等に比較して、強度、導電率、ヤング率のバランスや成形加工性をはじめ耐環境性、耐熱性、耐応力緩和特性、金型摩耗等に優れるため黄銅やりん青銅に代わる安価なコネクタ等の電気・電子材料として最適なものである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a copper alloy having strength conductivity suitable as a material for electrical and electronic parts such as connectors and having a low Young's modulus and a method for producing the same.
[0002]
[Prior art]
With the recent development of electronics, the electrical wiring of various machines has become more complex and highly integrated, and along with this, the number of copper products used for electrical and electronic parts such as connectors has increased.
In addition, electrical and electronic parts such as connectors are required to be lightweight, highly reliable, and low in cost. Therefore, in order to satisfy these requirements, the copper alloy material for connectors is thinned and pressed into a complicated shape, so that the strength, elasticity, conductivity and press formability must be good.
[0003]
Specifically, in the terminal, the tensile strength in the rolling direction is 600 N / mm ² or more, preferably 700 N / mm ² as the strength against buckling or deformation during insertion / extraction or bending, and the strength against crimping and holding of the wire. above, the spring limit value is 450 N / mm ² or more, 500 N / mm ² or more if possible is preferred. Furthermore, in order to suppress the generation of Joule heat due to energization, the conductivity is preferably 18% IACS or more. Further, the demand for press formability becomes stricter due to the miniaturization of the terminals, and workability is required so that the ratio R / t of the bending portion radius (R) to the plate thickness (t) satisfies 1 or less.
[0004]
Conventionally, the connector has been downsized, and it has been required that the Young's modulus of the material be large so that a large stress can be obtained with a small displacement. Or, the management standards such as the thickness of the material and the variation of the residual stress became stricter, and the cost was increased. Therefore, recently, there has been a demand for a design that uses a material having a small Young's modulus and has a structure in which the displacement of the spring is large, and can tolerate variation in dimensions. Accordingly, it has been demanded that the Young's modulus in the rolling direction is 120 kN / mm ² or less, preferably 115 kN / mm ² or less.
[0005]
In addition to the above, the frequency of maintenance of molds is a large part of the cost and has been highlighted. Tool wear is a major factor in mold maintenance. When a material is pressed (punched or bent), tools such as punches, dies, strippers, etc. wear, leading to burrs on the workpiece and dimensional defects. At this time, the influence on the wear of the material itself is great. Accordingly, there is an increasing demand for improvement on the material side with respect to mold wear.
[0006]
Furthermore, it is necessary to have excellent corrosion resistance and stress corrosion cracking resistance, and the female terminal must be excellent in stress relaxation resistance because a thermal load is applied.
Specifically, it is desirable that the stress corrosion cracking life is at least three times that of a conventional brass, the stress relaxation rate is 150 ° C. × 500 hours, and the relaxation rate is 25% or less, which is half that of a brass.
[0007]
Conventionally, brass, phosphor bronze, and the like have been generally used as connector materials. Brass is used as a low-cost material, but the tensile strength in the rolling direction does not exceed 600 N / mm ² even when the grade is EH, and is inferior in corrosion resistance, stress corrosion cracking resistance, and stress relaxation characteristics. . Phosphor bronze has an excellent balance of strength, corrosion resistance, stress corrosion cracking resistance, and stress relaxation resistance. However, for example, the phosphor bronze for springs is as small as 12% IACS and is disadvantageous in terms of cost. Therefore, many copper alloys have been researched, developed and proposed. However, many proposed copper alloys are obtained by adding a small amount of additive elements to copper and balancing the properties such as strength, electrical conductivity, and stress relaxation resistance, and the Young's modulus is 120 to 120 in the rolling direction. It was a large value of 135 kN / mm ² and the cost was high.
[0008]
Here, for both brass and phosphor bronze, the Young's modulus in the rolling direction is 110 to 120 kN / mm ² , and the small Young's modulus meets the requirements of the above-mentioned design, and these materials have recently been reviewed. Therefore, in the near brass price, the rolling direction of the spring limit value 450 N / mm ² or more, a tensile strength of 600N / mm ² or more, conductivity of 18% IACS or more, a Young's modulus of 120 kN / mm ² or less, preferably 115KN / Materials that are mm ² or less are highly desired.
[0009]
[Problems to be solved by the invention]
With the development of electronics, the present invention has the above-mentioned characteristics required for materials for electrical and electronic parts such as connectors, that is, strength, conductivity, Young's modulus, stress relaxation resistance, and stress corrosion cracking resistance. The present invention provides a copper alloy for connectors excellent in press formability, cost, and the like, and a method for producing the same.
[0010]
[Means for Solving the Problems]
The present invention provides various properties as described above required for materials for electrical and electronic parts such as connectors by limiting the composition and heat treatment conditions while reducing the cost by adding components cheaper than copper. That is, the present invention provides a copper alloy for connectors excellent in strength, electrical conductivity, Young's modulus, stress relaxation resistance, stress corrosion cracking resistance, press formability, cost, and the like.
[0011]
The characteristics of the copper alloy according to the present invention are as follows.
[0012]
That is,
(1) Zn: 20-41 mass%, Sn: 0.1-4.0 mass%, Ni: 0.1-5.0 mass%, P: In the range of 0.01-0.3 mass% and satisfying the following formula, Ni and P are included,
5.0 ≦ Ni / P ≦ 50
However, Ni: Ni content (mass%)
P: P content (mass%)
The balance is made of Cu and inevitable impurities, the tensile strength in the rolling direction is 600 N / mm ² or more, the conductivity is 18% IACS or more, the Young's modulus is 120 kN / mm ² or less, and the spring limit value is 450 N / mm ² or more. A copper alloy for connectors.
[0013]
In (2) the connector copper alloy, Zn: 20~41mass%, Sn: 0.1~4.0mass% range at and above characterized by comprising meets the following equation (1) connector copper alloy according.
6.0 ≦ 0.25X + Y ≦ 12
However, X: Zn content (mass%)
Y: Sn content (mass%)
[0014]
(3) The connector according to ( 1) to (2) above, wherein the surface of the metal material made of the copper alloy is subjected to a surface treatment of Cu base: 0.3 to 2.0 μm, Sn: 0.5 to 5.0 μm. Copper alloy.
[0015]
(4) Zn: 20 to 41 mass%, Sn: 0.1 to 4.0 mass%, Ni: 0.1 to 5.0 mass%, P: 0.01 to 0.3 mass%, including Ni and P satisfying the following formula,
5.0 ≦ Ni / P ≦ 50
However, Ni: Ni content (mass%)
P: P content (mass%)
After the heat treatment for 1 to 360 minutes at a temperature of 300 to 750 ° C. and the cold working at a processing rate of 10% or more, the copper alloy material consisting of the remainder consisting of Cu and inevitable impurities is then cold processed at 200 to 600 ° C. for 5 seconds to 180 minutes. The tensile strength in the rolling direction is 600 N / mm ² or more, the electrical conductivity is 18% IACS or more, the Young's modulus is 120 kN / mm ² or less, and the spring limit value is 450 N / mm ² or more. Manufacturing method of copper alloy for connectors.
[0016]
(5) Zn: 20 to 41 mass%, Sn: 0.1 to 4.0 mass%, Ni: 0.1 to 5.0 mass%, P: 0.01 to 0.3 mass%, and Ni: P formed by satisfying the following formula:
5.0 ≦ Ni / P ≦ 50
However, Ni: Ni content (mass%)
P: P content (mass%)
After the heat treatment for 1 to 360 minutes at a temperature of 300 to 750 ° C. and the cold processing at a processing rate of 10% or more, the copper alloy material consisting of Cu and inevitable impurities as the balance is 200 to 600 ° C. for 5 seconds to 180 minutes. By performing heat treatment, the tensile strength in the rolling direction is 600 N / mm ² or more, the conductivity is 18% IACS or more, the Young's modulus is 120 kN / mm ² or more, the conductivity is 18% IACS or more, and the Young's modulus is 120 kN / mm. ² or less, after the spring limit value is 450 N / mm ² or more, the surface of the copper alloy material is subjected to a surface treatment of Cu underlayer: 0.3 to 2.0 μm, Sn: 0.5 to 5.0 μm, and then a temperature of 100 to 280 ° C. The manufacturing method of the copper alloy for connectors characterized by performing heat processing for 1 to 180 minutes.
[0017]
(6) In the copper alloy for connectors, Zn: 20 to 41 mass%, Sn: 0.1 to 4.0 mass%, and satisfying the following formula, (4) or (5) Manufacturing method of copper alloy for connectors.
6.0 ≦ 0.25X + Y ≦ 12
However, X: Zn content (mass%)
Y: Sn content (mass%)
[0018]
(7) The method for producing a copper alloy for connectors according to the above (4) to (6) , wherein the heat treatment is performed after cold working at a temperature higher than the heat treatment temperature at which the spring limit value reaches a peak.
[0019]
(8) In the above production method, when the stamped scrap of a material obtained by surface-treating Sn to the above-mentioned alloy is used as a raw material, this stamped scrap is in the atmosphere or inert at a temperature of 300 to 600 ° C. for 0.5 to 24 hours. The method for producing a copper alloy for connectors according to any one of (4) to (7) , wherein the copper alloy is melted after heat treatment in a gas atmosphere in advance.
[0020]
[Action]
Next, the contents of the present invention will be specifically described.
First, the reason for limiting the amount of components in the copper alloy of the present invention will be described.
Zn:
Addition of Zn improves strength and springiness and is cheaper than Cu, so it is desirable to add a large amount. However, if it exceeds 41 mass%, workability, corrosion resistance, and stress corrosion cracking resistance are reduced. Further, the plating property and solderability are deteriorated. On the other hand, if it is less than 20 mass%, strength and springiness are insufficient, Young's modulus is increased, and when scraps with Sn surface treatment are used as raw materials, hydrogen gas occlusion increases during melting, and ingot blowholes are generated. It becomes easy to do. Moreover, there is little inexpensive Zn and it becomes economically disadvantageous. Therefore, Zn should just be the range of 20-41 mass%. A preferable range is 22 to 38 mass%. Furthermore, as a preferable range, when it is 24 to 30 mass%, it is possible to suppress hot cracking that occurs due to the balance between the solidification structure during hot casting and hot rolling.
[0021]
Sn:
Sn is effective in improving mechanical properties such as strength and elasticity in a small amount. Moreover, a small Young's modulus can be satisfied in the presence of Zn as compared with many copper alloy systems. Furthermore, it is preferable to contain it as an additive element also from the point of reuse of the material which surface-treated Sn, such as Sn plating. However, when the Sn content is increased, the conductivity is drastically lowered and the hot workability is also lowered. In order to ensure the electrical conductivity of 18% IACS, it must be within a range not exceeding 4.0 mass%. Further, if the amount is less than 0.1 mass%, the above effect cannot be expected. Therefore, Sn should just be the range of 0.1-4.0 mass%. A preferable range is 0.5 to 2.0 mass%. Furthermore, as a preferable range, when it is 0.7 to 1.3 mass%, it is possible to suppress hot cracking that occurs due to the balance between the solidification structure and hot rolling during melting and casting.
[0022]
Ni:
Ni is dissolved in the Cu matrix to improve strength, elasticity, and stress relaxation resistance. In addition, by forming a compound with P to disperse and precipitate, the electrical conductivity is also improved. However, if it is less than 0.1 mass%, the desired effect cannot be obtained, and if it exceeds 5.0 mass%, the electrical conductivity is lowered, which is economically disadvantageous. A more preferable range is 0.2 to 2.0 mass%.
[0023]
P:
P improves the corrosion resistance of the Zn-containing alloy and forms a compound with Ni to disperse and precipitate, thereby improving strength, elasticity, stress relaxation resistance, stress corrosion cracking resistance, and electrical conductivity. If the amount is less than 0.01 mass%, the above effects cannot be obtained sufficiently. If the amount exceeds 0.3 mass%, the electrical conductivity and solder weatherability are severely deteriorated, which adversely affects castability and hot workability. Specifically, when Zn, Sn and P coexist, hot workability is remarkably lowered. For this reason, addition of Ni is necessary. Even in the presence of Ni, excessive P significantly reduces the productivity as described above. Therefore, it is set to 0.01 to 0.3 mass%. A more preferable range is 0.02 to 0.1 mass%.
[0024]
About the composition ratio of Ni and P In the copper alloy according to the present invention, a part of the added Ni and P forms a Ni-P-based compound, which is uniformly and finely dispersed and precipitated, whereby electric conductivity, strength, elasticity , Stress relaxation resistance and stress corrosion cracking resistance can be improved. Therefore, it is desirable to limit the ratio of Ni and P. If the ratio of Ni and P is less than 5.0, the desired effect cannot be obtained, and hot workability is remarkably reduced. If it is greater than 50, Ni—P compounds are coarsely precipitated, and the strength, conductivity, and molding process are reduced. Adverse effects such as decreased sex.
[0025]
(1) About the formula
6.0 ≦ 0.25X + Y ≦ 12 (1)
However, X: Zn content (mass%)
Y: Sn content (mass%)
In addition, in formula (1), when the value of the formula is less than 6.0, the strength such as tensile strength is lowered, and a desired Young's modulus cannot be obtained, and when it is greater than 12, the electrical conductivity and molding processability are adversely affected. Will be affected.
[0026]
By limiting the range of the components as described above, the tensile strength in the rolling direction is 600 N / mm ² or more, the electrical conductivity is 18% IACS or more, the Young's modulus is 120 kN / mm ² or less, and the spring limit value is 450 N / mm ^2. Furthermore, various characteristics required for connector materials, specifically corrosion resistance, stress corrosion cracking resistance (cracking life in ammonia vapor is more than three times that of brass), stress relaxation resistance (relaxation at 80 to 120 ° C) It is possible to produce a copper-based alloy for a connector that satisfies a rate of less than half of one kind of brass, comparable to phosphor bronze), moldability (no cracking even in 90 ° W bending with R / t ≦ 1.0).
[0027]
Next, the reasons for limiting the manufacturing conditions according to the present invention will be described.
This copper alloy material is heat-treated at a temperature of 300 to 750 ° C. for 1 to 360 minutes, then cold worked at a processing rate of 10% or more, and then subjected to a heat treatment at a temperature of 200 to 600 ° C. for 5 seconds to 180 minutes. If the surface of the substrate is subjected to surface treatment of 0.3 to 2.0 μm Cu base and 0.5 to 5.0 μm Sn and then heat-treated at a temperature of 100 to 280 ° C. for 1 to 180 minutes, the characteristics as a connector material are further improved. Can do.
[0028]
In the annealing before the final cold working, if the crystal grain size is controlled to 5 to 20 μm, the press formability is improved, but the processing temperature at this time is preferably 300 to 750 ° C. If the temperature is lower than 300 ° C., the temperature required for recrystallization is too low, and the treatment time becomes longer and is not economical. If the temperature exceeds 750 ° C., the crystal grains become coarse in a short time and it is difficult to control the crystal grain size.
[0029]
The time is preferably 1 to 360 minutes. If the treatment time is too short, the control of crystal grains by recrystallization is not sufficient, and if the treatment time is too long, crystal grains are likely to grow and become coarse, and this is economically disadvantageous.
[0030]
Further, the final cold working rate is preferably 10% or more. If it is less than 10%, improvement in strength, hardness, etc. by work hardening is not sufficient. However, if the processing rate is too large, the workability deteriorates, so a preferable range is 10 to 90%.
[0031]
Thereafter, heat treatment is performed at a temperature of 200 to 600 ° C. for 5 seconds to 180 minutes. This heat treatment improves the spring limit value, stress relaxation resistance, stress corrosion cracking resistance, conductivity, and bending workability of the material. Such effects are not sufficient at temperatures below 200 ° C., and the strength rapidly decreases at temperatures above 600 ° C. The time is preferably 5 seconds to 180 minutes. If the treatment time is too short, the above effect is not sufficient, and if it is too long, it is economically disadvantageous.
[0032]
At this time, by performing the heat treatment at a temperature higher than the heat treatment temperature at which the spring limit value reaches a peak, the stress relaxation resistance, the stress corrosion cracking resistance, and the workability can be improved. However, if the heat treatment temperature is too high, the tensile strength and the spring limit value are sharply lowered. Therefore, it is desirable that the heat treatment conditions are such that the spring limit value is between 70 and 100% of the peak value.
[0033]
The material obtained in this manner is subjected to surface treatment with a Cu underlayer of 0.3 to 2.0 μm and an Sn surface treatment of 0.5 to 5.0 μm. If the Cu substrate is less than 0.3 μm, Zn in the alloy diffuses and oxidizes on the surface treatment layer and the surface, and is less effective in preventing an increase in contact resistance and a decrease in solderability. Saturated and not economical. However, the Cu base plating is not limited to pure Cu, but may be a copper alloy such as Cu—Fe or Cu—Ni.
[0034]
If the Sn surface treatment layer is less than 0.5 μm, the corrosion resistance, particularly hydrogen sulfide resistance is insufficient, and if it exceeds 5.0 μm, the effect is saturated and economically disadvantageous. Furthermore, if these surface treatments are carried out by electroplating, it is preferable in terms of film thickness uniformity and economy. A reflow treatment may be performed after the surface treatment to give gloss. This process is also effective for whisker countermeasures.
[0035]
This surface treatment material is heat-treated at a temperature of 100 to 280 ° C. for 1 to 180 minutes. This heat treatment improves the spring limit value and work hardening index of the material. When the work hardening index is increased, when the connector spring portion is formed by bending, the spring property is improved by hardening of the spring portion. In addition, by forming a hard Cu-Sn intermetallic compound layer on the surface treatment layer of the material, when used as a connector, it is possible to improve wear resistance and decrease insertion / extraction force, and also to prevent whisker It is valid. Such effects are not sufficient at temperatures below 100 ° C., and contact resistance, solderability, and workability deteriorate due to diffusion and oxidation at temperatures above 280 ° C. In addition, if the heat treatment time is less than 1 minute, the effect is not sufficient, and if it exceeds 180 minutes, the above-described characteristic deterioration due to diffusion or oxidation occurs, and it is not economical.
[0036]
When the stamped scrap of the surface-treated material Sn is melted as a raw material in the alloy of the present invention, it is melted after heat treatment in the air or in an inert atmosphere at a temperature of 300 to 600 ° C. for 0.5 to 24 hours. When the temperature is lower than 300 ° C., the press oil adhering to the press scrap is not sufficiently burned, and the moisture adsorbed during storage is insufficiently dried. The hydrogen generated by the decomposition is absorbed into the molten metal and causes blowholes.
[0037]
Further, at a temperature exceeding 600 ° C., oxidation rapidly proceeds and causes dross generation. This dross increases the viscosity of the melt and lowers the castability. Accordingly, the heat treatment temperature is in the range of 300 to 600 ° C. If the time is less than 0.5 hours, the combustion of the press oil and the drying of moisture are not sufficient, and if the time exceeds 24 hours, the base material Cu diffuses and oxidizes in the Sn surface treatment layer, and Cu—Sn—O-based oxides are formed. It forms, causes dross, and is not economical. Accordingly, the heat treatment time is in the range of 0.5 to 24 hours. In addition, the atmosphere is insufficient in the air, but sealing with an inert gas is preferable from the viewpoint of preventing oxidation.
However, when the temperature of the reducing gas is high, it is disadvantageous due to the absorption and diffusion of hydrogen due to the decomposition of moisture. Next, embodiments of the present invention will be described by way of examples.
[0038]
DETAILED DESCRIPTION OF THE INVENTION
Example 1
Table 1 shows the chemical composition (mass%) of copper alloy No. 1-16 were melted using a high frequency induction melting furnace and cast into a 40 × 40 × 150 (mm) ingot. However, the atmosphere during melting and casting was an Ar gas atmosphere, and water cooling was performed immediately after casting.
Then, after hot rolling each ingot, cold rolling and annealing were repeated to obtain a thickness of 0.50 mm. And after heat-processing material for 60 minutes at the temperature of 450 degreeC, water quenching was performed, and also the pickling was performed. The heat-treated material obtained as described above was cold-rolled to a thickness of 0.25 mm, annealed for 30 minutes at each temperature condition, and subjected to pickling as a test material.
[0039]
Using the test material obtained as described above, Vickers hardness, tensile strength, Young's modulus, bending limit value and electrical conductivity in the rolling direction were measured, and stress relaxation characteristics were investigated. Regarding the bending workability, the rolling direction and the direction perpendicular to the rolling direction were investigated. The measurements of Vickers hardness, tensile strength, Young's modulus, spring limit value, and conductivity were in accordance with JIS-Z-2244, JIS-Z-2241, JIS-H-3130, and JIS-H-0505, respectively.
[0040]
The stress relaxation test was calculated according to the following equation as the stress relaxation rate after bending for 500 hours at a temperature of 150 ° C. in an arch so that the stress at the center of the test piece was 400 N / mm ² .
Stress relaxation rate (%) = [(L ₁ −L ₂ ) / (L ₁ −L ₀ )] × 100
L ₀ : Jig length (mm)
L ₁ : Sample length at start (mm)
L ₂ : Horizontal distance between sample ends after processing (mm)
[0041]
The bending workability is 90 ° W bending test (CES-M-0002-6, R = 0.25 mm , R / t = 1.0, W = 10 mm, rolling direction and vertical direction). A good one was evaluated as a mark ◯, a wrinkled one was evaluated as a △ mark, and a cracked one was evaluated as a x mark.
[0042]
[Table 1]

[0043]
From the results shown in Table 1, the copper alloys of Nos. 1 to 9 according to the present invention are excellent in the balance of tensile strength, Young's modulus, and electrical conductivity, and also have good bending workability. Therefore, it is a copper alloy having very excellent characteristics as an electrical / electronic material such as a connector.
In addition, the annealing temperature is increased compared to No.5, and the tensile strength and spring limit value of No.9 are reduced, but the Young's modulus, stress relaxation resistance and bending workability are improved. I understand.
[0044]
On the other hand, the smaller No. 10 in which the Zn and Sn contents are defined by the formula (1) is inferior in tensile strength and Young's modulus, and the larger No. 11 in which the Zn and Sn contents are defined in (1). Is inferior in electrical conductivity, stress relaxation rate and bending workability.
No. 12, which has a Ni : P ratio larger than the alloy of the present invention, has a large Young's modulus and a low electrical conductivity.
Moreover, it is inferior also in bending workability. No. 13 having a smaller Ni: P ratio than the alloy of the present invention is inferior in stress relaxation rate and bending workability. This number P amount, Ni: P ratio is small, precipitation of Ni-P compound is excessively large, bendability, it is considered that the stress relaxation property is lowered. In addition, cracks occurred during hot rolling, and it was not possible to roll to the final thickness with good yield.
No. 14, which has a larger amount of P than the alloy of the present invention, is inferior in tensile strength, spring limit value, Young's modulus, electrical conductivity, and bending workability. Furthermore, the yield was extremely poor due to a significant decrease in hot workability. No. 15 having a larger amount of Ni than the alloy of the present invention is inferior in Young's modulus and electrical conductivity.
No. 16 is a sample in which the heat treatment temperature is higher than No. 9, but the tensile strength and spring limit value are greatly reduced.
[0045]
Example 2
Regarding the alloy No. 2 of the present invention shown in Table 1 of Example 1, commercially available brass (C2600-EH) and phosphor bronze (C5191-EH), the hardness in the rolling direction, the tensile strength, and the Young's modulus The electrical conductivity, the stress relaxation rate and the stress corrosion cracking life were tested and measured. Further, the bending direction and the bending workability in the direction perpendicular to the rolling direction were adjusted.
The measurement tests of hardness, tensile strength, Young's modulus, electrical conductivity, and stress relaxation rate in the rolling direction are the same measurement methods as in Example 1, and the stress corrosion cracking time is about 400 N / mm ^{2 in} the sample. This is the time when cracks occurred when stress was applied and exposed in a desiccator containing 12.5% aqueous ammonia.
[0046]
[Table 2]

[0047]
From the results shown in Table 2, the copper alloy of the present invention has strength, Young's modulus, bending workability, stress relaxation characteristics, stress corrosion resistance compared to brass, which is a conventional electrical / electronic material such as a connector. It can be seen that the cracking property is improved. Compared to phosphor bronze, it is excellent in strength, bending workability, Young's modulus, electrical conductivity, and stress relaxation characteristics. Furthermore, it can be said that it is excellent from the component and manufacturing process also in terms of cost. Therefore, it can be said that the copper alloy of the present invention is sufficiently superior to conventional brass and phosphor bronze.
[0048]
Example 3
After producing the alloy strips of the present invention shown in Table 3, Cu undercoating was performed at 0.5 μm and Sn plating was performed at 1.0 μm, and then the press-punched material was prepared as a raw material for melt casting. The target composition in the casting was shown in Table 3, and about 1 ton of press scrap was used as a raw material for melting, and the remainder was adjusted with electric Cu, Zn, Ni, and P to obtain six ingots of about 2 t. The components of the obtained ingot were almost the same as in Table 3.
[0049]
Here, as for three pieces, the press scrap of the raw material was heated at 450 degreeC for 3 hours in air | atmosphere. The remaining three were not processed. This was melted rapidly to cast a 2t ingot, and hot rolling, cold rolling and annealing were repeated to finish to 0.25 mm. The total length of the material thus obtained was inspected, and the number of defects due to ingot blowholes was counted (Table 4).
From Table 4, the heat-treated press waste by the method of the present invention was excellent without defects. On the other hand, those not heat-treated have defects and it can be seen that there is a problem in yield.
[0050]
[Table 3]

[0051]
[Table 4]

[0052]
Example 4
After subjecting the alloy No. 2 of the present invention shown in Table 1 of Example 1 to 0.5 μm of Cu undercoat and 1.1 μm of Sn, heat treatment was performed at 190 ° C. for 60 minutes. The material and the material that was not heat-treated after plating were measured for the spring limit value in the rolling direction and subjected to a 90 ° W bending test ( R = 0.25 mm , R / t = 1.0, rolling direction). The distribution of the hardness of the cross section of the bent part of the later specimen was investigated. The same investigation was conducted on a conventional alloy (brass type 1 comparative material C2600 EH bare material).
[0053]
[Table 5]

From Table 5, it can be seen that the spring limit value of the alloy of the present invention is further improved by heat treatment. Moreover, when comparing the hardness of the stationary part that has not been deformed with the maximum hardness of the bent part that has been deformed, it can be seen that the hardening is greater than when the heat treatment is not performed, which is advantageous for the connector spring part. Moreover, even if compared with brass, it can be said that the alloy of the present invention is sufficiently excellent as a copper alloy for connectors.
【The invention's effect】
As is clear from the above examples, the copper-based alloy according to the present invention or the material obtained by the method of the present invention has a balance of strength, electrical conductivity, Young's modulus and the like compared to conventional brass, phosphor bronze and the like. It is ideal for electrical and electronic materials such as inexpensive connectors that replace brass and phosphor bronze because it excels in formability, environment resistance, heat resistance, stress relaxation resistance, and mold wear.

Claims

Zn: 20-41 mass %, Sn: 0.1 ~ 4.0mass %, Ni: 0.1 ~ 5.0mass %, P: 0.01 ~ 0.3mass %, And Ni and P satisfying the following formula,
5.0 ≦ Ni / P ≦ 50
However, Ni: Ni content ( mass %)
P: P content ( mass %)
The balance consists of Cu and inevitable impurities, and the tensile strength in the rolling direction is 600 N / mm. ^２2 Above, electrical conductivity is 18% IACS or more, Young's modulus is 120kN / mm ^２2 Hereinafter, the spring limit value is 450 N / mm ^２2 The copper alloy for connectors characterized by the above.

The said copper alloy for connectors WHEREIN: It is the range of Zn: 20-41 mass%, Sn: 0.1-4.0 mass%, and satisfy | fills following Formula, The copper alloy for connectors of Claim 1 characterized by the above-mentioned.
6.0 ≦ 0.25X + Y ≦ 12
However, X: Zn content (mass%)
Y: Sn content (mass%)

The copper alloy for connectors according to claim 1 or 2, wherein a surface treatment of Cu base: 0.3 to 2.0 µm, Sn: 0.5 to 5.0 µm is performed on the surface of the metal material made of the copper alloy.

Zn: 20 to 41 mass%, Sn: 0.1 to 4.0 mass%, Ni : 0.1 to 5.0 mass%, P: 0.01 to 0.3 mass%, including Ni and P satisfying the following formula,
5.0 ≦ Ni / P ≦ 50
However, Ni: Ni content (mass%)
P: P content (mass%)
After the heat treatment for 1 to 360 minutes at a temperature of 300 to 750 ° C. and the cold processing at a processing rate of 10% or more, the copper alloy material consisting of Cu and inevitable impurities as the balance is 200 to 600 ° C. for 5 seconds to 180 minutes. wherein the heat treatment, rolling direction of the tensile strength of 600N / mm ² or more, conductivity of 18% IACS or more, a Young's modulus of 120 kN / mm ² or less, the spring limit value 450 N / mm ² or more connectors Of manufacturing copper alloys.

Zn: 20 to 41 mass%, Sn: 0.1 to 4.0 mass%, Ni: 0.1 to 5.0 mass%, P: 0.01 to 0.3 mass%, including Ni and P satisfying the following formula,
5.0 ≦ Ni / P ≦ 50
However, Ni: Ni content (mass%)
P: P content (mass%)
After the heat treatment for 1 to 360 minutes at a temperature of 300 to 750 ° C. and the cold processing at a processing rate of 10% or more, the copper alloy material consisting of Cu and inevitable impurities as the balance is 200 to 600 ° C. for 5 seconds to 180 minutes. by heat treatment, the tensile strength of the rolling direction 600N / mm ² or more, conductivity of 18% IACS or more, a Young's modulus of 120 kN / mm ² or less, after the spring limit value is set to 450 N / mm ² or more, the The copper for connector, characterized by subjecting the surface of the copper alloy material to a Cu base: 0.3-2.0 μm and Sn: 0.5-5.0 μm, followed by heat treatment at a temperature of 100-280 ° C. for 1-180 minutes Alloy manufacturing method.

The said copper alloy for connectors WHEREIN: It is the range of Zn: 20-41mass%, Sn: 0.1-4.0mass%, and satisfy | fills following Formula, The manufacture of the copper alloy for connectors of Claim 4 or 5 characterized by the above-mentioned. Law.
6.0 ≦ 0.25X + Y ≦ 12
However, X: Zn content (mass%)
Y: Sn content (mass%)

The method for producing a copper alloy for a connector according to any one of claims 4, 5 and 6 , wherein the heat treatment is performed after cold working at a temperature higher than a heat treatment temperature at which the spring limit value reaches a peak.

In the above manufacturing method, press punched scraps of a material obtained by surface-treating Sn on the above-described alloy are used as raw materials, and the press punched scraps are preheated in air or in an inert gas atmosphere at 300 to 600 ° C. for 0.5 to 24 hours. The manufacturing method of the copper alloy for connectors in any one of Claim 4, 5, 6 or 7 which melt | dissolves later.