JP2004232049A

JP2004232049A - Cu PLATING TITANIUM COPPER

Info

Publication number: JP2004232049A
Application number: JP2003023461A
Authority: JP
Inventors: Hirotaka Yamazaki; 浩崇山崎; Takatsugu Hatano; 隆紹波多野
Original assignee: Nikko Metal Manufacturing Co Ltd
Current assignee: Nippon Mining Holdings Inc
Priority date: 2003-01-31
Filing date: 2003-01-31
Publication date: 2004-08-19

Abstract

<P>PROBLEM TO BE SOLVED: To provide Cu plating titanium copper having excellent corrosion resistance, oxidation resistance and thermal peelability of plating. <P>SOLUTION: The Cu plating titanium copper contains 1.5 to 4.5% (% is a ratio by mass, hereafter the same) Ti and consists of the balance Cu and inevitable impurities and is subjected to copper plating on its surface, in which the impurities are S≤30 ppm, P≤10 ppm and O≤100 ppm. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は耐食性、耐酸化性、めっき熱剥離性および半田付け性に優れたＣｕめっきチタン銅、およびその製造方法に関するものである。
【０００２】
【従来の技術】
電子機器の各種端子、コネクター、リレーまたはスイッチ等の電気伝導性とばね性が必要な材料は従来、コスト面を重視する用途で安価な「黄銅」が適用され、ばね特性が重視される用途では「りん青銅」が適用され、あるいは、ばね特性と耐食性が重視される用途では「洋白」が適用されていた。ところが、近年、電子機器類およびその部品の小型化、薄肉化傾向に伴って、これらの材料は強度を満足できないために、ベリリウム銅（以下「Ｃｕ−Ｂｅ合金」と称す）やチタン銅（以下「Ｃｕ−Ｔｉ合金」と称す）などの高強度を有する高級ばねの需要が増えている。ＣＤＡ合金番号Ｃ１９９００に代表されるＣｕ−Ｔｉ合金は、溶体化処理によりＴｉを固溶させた後、冷間圧延を行ない、最後に時効処理を行うプロセスにより製造される。最後の時効処理においてＣｕ_３ＴｉあるいはＣｕ_４Ｔｉの微細粒子が析出し、耐力、ばね限界値といった強度特性が向上する。
時効処理後のＣｕめっきチタン銅条は、その後、プレス加工によりコネクタ部品等に加工される（以下、ミルハードン材）。一方、溶体化処理し冷間圧延した条をコネクタ等にプレス加工し、その後に時効処理を行なう場合もある（以下、ノンミルハードン材）。
【０００３】
近年、電子機器類及びその部品の軽薄短小化がますます進み、材料の高強度化に対する要求は厳しくなっている。この要求に対応するために、例えば特許文献１では、Ｃｕ−Ｔｉ合金の結晶粒径および溶体化処理と冷間圧延の一連の製造条件を制御し、強度、曲げ加工性および応力緩和特性に優れた材料を得ている。
Ｃｕ−Ｔｉ合金の製造プロセスでは、溶体化処理によりＴｉを固溶させた後、冷間圧延を行い、その後、時効処理を行う。Ｃｕ−Ｔｉ合金は極めて活性な元素であるＴｉを含有するため、最終工程の時効処理において強固な酸化膜が生成し、はんだ濡れ性、めっき性等が著しく低下する。Ｃｕ−Ｔｉ合金の場合、水素を含有する雰囲気中で時効処理を行っても、表面酸化が進行する。この問題を回避するためには、時効後に酸洗・研磨工程を実施し、酸化膜を除去する必要がある。（非特許文献１参照）
Ｃｕ−Ｔｉ合金にＣｕめっきを施す場合、ミルハードン材では時効後の酸洗・研磨の後に、またノンミルハードン材では溶体化処理後の冷間圧延の後に、Ｃｕめっき工程が付加されることが多い。
【０００４】
【特許文献１】
特開平７−２５８８０３号公報
【非特許文献１】
日鉱金属株式会社倉見工場製品カタログ
【０００５】
【発明が解決しようとする課題】
耐酸化性の低下に伴い、熱処理等の際に表面が酸化すると、半田付け性やめっき性が劣化する。酸化の問題は、部品に加工後に時効熱処理を行うノンミルハードン材において、特に深刻である。複雑な形状の部品に対しては、時効の際に生成する強固な酸化膜を、酸洗処理や研磨処理で除去することが技術的に難しいためである。
Ｃｕ−Ｔｉ合金は活性なＴｉを含有するため、表面の酸化あるいは変色が容易に進行する。Ｃｕめっきには、この表面酸化や変色を抑制する効果が期待される。しかしながら、Ｃｕめっきを施しただけのめっき層はピンホールが多い。Ｃｕめっき層中にピンホールが存在すると、めっき表面よりＯがＣｕ−Ｔｉ合金表面に拡散してＴｉが酸化し、腐食を促進するため、Ｃｕめっきによる耐酸化性および耐食性の改善効果があまり認められない。
また、Ｃｕめっきの耐食性が低い場合、Ｃｕめっきの表面が腐食しやすくなるだけでなく、Ａｕめっき等の高耐食めっきを施しても、その防食効果が充分に得られない。
一方、Ｃｕめっきチタン銅の表面に、Ｓｎめっきやはんだめっきが施されることがある。Ｓｎめっき材を高温環境下に長期間晒すと、Ｓｎめっきが剥離する。このめっき剥離は、母材／めっき界面においてボイドや不純物偏析層が成長することによって生じる。Ｃｕめっき層中のピンホールは、ボイドや不純物偏析層の成長を促進し、Ｓｎめっき剥離の進行を助長する。また、Ｃｕめっき層中にＳ、Ｐ、Ｏといった不純物が増加することによっても、Ｓｎめっき剥離が早期に生じる。
本発明は、耐食性、耐酸化性、めっき熱剥離性、半田付け性に優れたＣｕめっきチタン銅を提供することを課題とする。
【０００６】
【課題を解決するための手段】
発明者は、めっき層の不純物およびピンホールとめっき熱剥離性、耐食性、耐酸化性、半田付け性との関係を鋭意研究し、本発明を見出した。
すなわち、
（１）Ｔｉを１．５〜４．５％含有し、残部がＣｕおよび不可避的不純物からなり、表面に銅めっきを施したチタン銅において、銅めっき層中の不純物が、Ｓ≦３０ｐｐｍ、Ｐ≦１０ｐｐｍ、Ｏ≦１００ｐｐｍであることを特徴とするＣｕめっきチタン銅、
（２）Ｔｉを１．５〜４．５％含有し、残部がＣｕおよび不可避的不純物からなり、表面に銅めっきを施したチタン銅において、めっき後に圧延にて５％以上の加工を施すことを特徴とするＣｕめっきチタン銅、
（３）上記（１）及び（２）記載のＣｕめっきチタン銅
（４）Ｃｕめっき後にめっき層を再結晶させる熱処理を施すことを特徴とする上記（１）または（２）記載のＣｕめっきチタン銅、
である。
【０００７】
【発明の実施の形態】
以下に本発明の限定理由を説明する。
Ｃｕめっきを施しただけのめっき層にはピンホールが多く、その影響でＳ、Ｐ、Ｏが多い。ピンホール中に捕捉されためっき液等が、Ｓ、Ｐ、Ｏの混入源になるためであると考えられる。したがってＳ、Ｐ、Ｏが少ないめっき層であれば、ピンホールが少ないともいえる。浴の組成に応じた電流密度等のめっき条件を選択することにより、めっき層中のピンホールが少なく、Ｓ、Ｐ、Ｏが少ないめっき層を製造することが可能である。めっき条件を最適化することによりＳ≦３０ｐｐｍ、Ｐ≦１０ｐｐｍ、Ｏ≦１００ｐｐｍにできる。Ｓ＞３０ｐｐｍ、Ｐ＞１０ｐｐｍまたはＯ＞１００ｐｐｍの場合、めっき層中のピンホールが多く、耐食性、耐酸化性およびめっき熱剥離性が悪い。
【０００８】
一方、めっき浴の組成の選択およびその組成に応じた電流密度等のめっき条件を選択するだけでは、めっき層中のピンホールを皆無にすることは不可能である。
そこで本発明においては、Ｃｕめっき後のチタン銅に圧延を施すことにより、めっき層中のピンホールをさらに減少させる。ただし、加工度が５％以下では効果が不十分である。また、８０％を超える加工度ではピンホールが低減するものの、母材の曲げ性が劣化し、電子機器の各種端子、コネクター、リレーまたはスイッチ等の材料には適さない。ここで、圧延加工度（Ｒ）は次式で定義される。
Ｒ（％）＝（ｔ_０−ｔ）／ｔ_０×１００
ｔ_０：圧延前の板厚、ｔ：圧延後の板厚
Ｃｕめっきを施したチタン銅を非酸化雰囲気で加熱し、Ｃｕめっき層を再結晶させることにより、Ｃｕめっきの性能はさらに向上する。
Ｃｕめっきの厚さについては本発明の構成要件ではないが、厚さを０．３〜３μｍの間に調整することが望ましい。Ｃｕめっき後に冷間圧延を行う場合については、圧延加工度を考慮し、冷間圧延後のＣｕめっき厚みが０．３〜３μｍになるように、Ｃｕめっきを施す際のめっき厚みを決定する。めっきの厚みが０．３μｍを下回ると、Ｃｕめっきによる耐酸化性および耐食性の改善効果が低下する。また、Ｃｕめっき厚みが３μｍを超えると、製造コストの増大が無視できなくなる。なお、めっきの厚みが０．３〜３μｍの範囲から外れても、本発明の効果は得られる。
【０００９】
【実施例】
本実施例では、ノンミルハードン材を想定し、時効以前の工程でＣｕめっきを実施する例を示すが、時効以後にＣｕめっきを実施する場合（ミルハードン材）についても同様の効果が得られる。
各実施例に用いられたチタン銅は、電気銅あるいは無酸素銅を原料とし、高周波真空溶解炉にて、Ｔｉ濃度が３％のＣｕ−Ｔｉ合金インゴット（厚さ１５０ｍｍ）を製造し、このインゴットを熱間圧延で１０ｍｍまで圧延したもので、それ以降の工程は実施例の目的に合わせて加工を行った。
【００１０】
（１）実施例１
上記のチタン銅を冷間圧延により厚さ０．２ｍｍに加工し、７８０℃で溶体化処理を行って結晶粒径を約１０μｍに仕上げ、冷間圧延で厚さ０．１５ｍｍまで加工した。その後、Ｃｕめっきを１μｍの厚さで施した。Ｃｕめっきの際には、めっき条件を変化させることにより、めっき層中のＳ、Ｐ、Ｏを調整した。
Ｃｕめっき上がり試料に対し、Ｃｕめっき層中のＳ、Ｐ、Ｏ濃度を分析した。また、めっき層のピンホールの分布状況をＳＥＭ観察した。
つぎに、Ｃｕめっき後の試料を５％水素−９５％窒素ガス中で４２０℃で３時間加熱した後、ＧＤＳ（グロー放電発光分光分析）により酸化膜の厚さ測定し、この酸化膜厚により耐酸化性を評価した。なお、この加熱は時効処理に相当し、ノンミルハードン材では条を部品にプレス加工した後に実施される。
【００１１】
さらに、４２０℃で３時間加熱後の試料に対して、Ｓｎめっきの耐熱剥離性、はんだ濡れ性および耐食性を評価した。
めっき熱剥離性：試料表面を１０％硫酸水溶液中で洗浄した後、厚さ１．５μｍのＳｎめっきを施した。その後、大気中で１０５℃で加熱し、５０時間ごとに短冊試験片に９０°曲げを加えてＳｎめっきの剥離の有無を観察し、Ｓｎめっきが剥離するまでの時間を求めた。
耐食性：試料表面を１０％硫酸水溶液中で洗浄した後、Ｎｉ下地の金めっき（Ｎｉ：１．５μｍ、Ａｕ：０．３μｍ）を施した。その後、ＪＩＳ−Ｃ００２３に準じて塩水噴霧試験（噴霧液：５ｗｔ％塩化ナトリウム溶液、噴霧量：１．０〜２．０ｍｌ／ｈ、試料室温度：３５±２℃、試料セット角度：２０°）を行った。２４時間曝露しめっき表面に変色がみられないものを○、変色が観察されたものを×とした。
半田付け性：幅１０ｍｍの短冊試験片を採取し、１０％硫酸水溶液中で洗浄した。ＪＩＳ−Ｃ００５３に準じ、メニスコグラフ法により、ロジン−エタノールフラックスを使用し、半田濡れ時間を測定した。
表１はめっき層に含まれるＳ、Ｐ、Ｏを変化させた例である。
【００１２】
【表１】

【００１３】
発明例Ｎｏ．１〜３、５〜６、８〜１０については、Ｓ、Ｐ、Ｏが請求の範囲にあり、ピンホールが少なかった。また、酸化膜厚は１０ｎｍ未満であり、このためはんだ濡れ時間は３秒未満であった。また、Ａｕめっき後の塩水噴霧試験でも変色が生じなかった。めっき熱剥離時間については、３００〜４００ｈまでＳｎめっきが剥離しなかった。
一方、Ｓ、Ｐ、Ｏが請求の範囲外である比較例Ｎｏ．４、７、１１については、ピンホールが多く見られ、酸化膜厚は１０ｎｍを超え、１０秒間の浸漬でははんだと濡れなかった。また、Ａｕめっき後の塩水噴霧試験で変色が生じ、１００ｈ以内にＳｎめっきが剥離した。
【００１４】
（２）実施例２
熱間圧延したチタン銅（Ｃｕ−３％Ｔｉ）を冷間圧延で０．５ｍｍまで圧延し、溶体化処理を行い、厚さ２μｍのＣｕめっきを施した。発明例及び比較例Ｎｏ．１２〜１８のＣｕめっき層のＳ、Ｐ、Ｏ濃度はそれぞれ２４、８、７８ｐｐｍであった。Ｎｏ．１９、２０のＣｕめっき層のＳ、Ｐ、Ｏ濃度はそれぞれ３２、１２、１２０ｐｐｍ、Ｎｏ．２１は、３５、１５、１５０であった。その後、所定の加工度の圧延を実施した。
この圧延材を５％水素−９５％窒素ガス中４２０℃で３時間加熱した後の酸化膜厚（耐酸化性）、耐熱剥離性、耐食性、半田付け性を、実施例１と同様の方法で評価した。
【００１５】
【表２】

【００１６】
表２に各特性の評価結果を示す。表２に記載している発明例及び比較例Ｎｏ．１２〜１８は請求項３に対するものであり、全ての例とも請求項１の発明例に該当する。
Ｓ、Ｐ、Ｏを規制した上で冷間圧延を施すことにより（Ｎｏ．１４〜１７）、圧延を行っていないＮｏ．１２に対し、加熱後の酸化膜厚が減少し、はんだ濡れ時間が短くなり、めっき剥離までの時間が長くなっている。しかし、加工度が５％未満のＮｏ．１３では、冷間圧延の効果は認められない。一方、Ｎｏ．１８はめっき熱剥離性、耐食性、耐酸化性、半田付け性に問題はないものの、高加工度の圧延により曲げ性が著しく劣化しているため、電子機器の各種端子、コネクター、リレーまたはスイッチ等の使用時に曲げ変形が加わる用途には適さない。
また、発明例Ｎｏ．１９〜２１はＳ、Ｐ、Ｏ濃度において請求項１の範囲を満たさないが、圧延加工を施すことにより、圧延をしない比較例Ｎｏ．１２或いは加工度の小さい比較例Ｎｏ．１３に比べてめっき剥離時間において良好な結果が得られている。しかしながら、Ｓ、Ｐ、Ｏ濃度が請求項１を満たす発明例Ｎｏ．１５，１６と比べると劣っていることがわかる。
【００１７】
（３）実施例３
実施例２におけるＮｏ．１６に用いた試料について、圧延後に、時効処理に相当する４２０℃で３時間の加熱を５％水素−９５％窒素ガス中で行い、酸化膜厚（耐酸化性）、耐熱剥離性、耐食性、半田付け性を、実施例１と同様の方法で評価した。
【００１８】
【表３】

【００１９】
表３に示すように発明例Ｎｏ．２２は、時効処理を施していない発明例Ｎｏ．１６と比較し、耐食性、耐酸化性、半田付け性、めっき熱剥離性がさらに向上した。
【発明の効果】
電子機器の各種端子、コネクター、リレーまたはスイッチ等の電気伝導性とばね性が必要な材料であるチタン銅において、耐食性、耐酸化性、めっき熱剥離性、半田付け性に優れたＣｕめっき銅合金を提供する。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a Cu-plated titanium copper excellent in corrosion resistance, oxidation resistance, plating heat peelability and solderability, and a method for producing the same.
[0002]
[Prior art]
For materials that require electrical conductivity and spring properties, such as various terminals, connectors, relays, and switches of electronic devices, inexpensive "brass" has conventionally been used in applications where cost is important, and in applications where spring characteristics are important. “Phosphor bronze” has been applied, or “Western” has been applied in applications where spring characteristics and corrosion resistance are important. However, in recent years, as electronic devices and their components have become smaller and thinner, these materials cannot satisfy the strength. Therefore, beryllium copper (hereinafter, referred to as “Cu—Be alloy”) and titanium copper (hereinafter, referred to as “Cu—Be alloy”) There is an increasing demand for high-grade springs having high strength, such as “Cu—Ti alloy”. A Cu-Ti alloy represented by CDA alloy number C19900 is produced by a process of solid-dissolving Ti by solution treatment, cold rolling, and finally aging treatment. In the final aging treatment, fine particles of Cu ₃ Ti or Cu ₄ Ti are precipitated, and strength characteristics such as proof stress and spring limit value are improved.
After the aging treatment, the Cu-plated titanium copper strip is thereafter processed into a connector part or the like by press working (hereinafter, mill hardened material). On the other hand, there is a case where a strip that has been subjected to solution treatment and cold-rolled is pressed into a connector or the like and then subjected to an aging treatment (hereinafter, non-mill-hardened material).
[0003]
In recent years, electronic devices and their components have become increasingly light and thin, and the demand for higher strength materials has become more stringent. In order to respond to this demand, for example, in Patent Document 1, the crystal grain size of a Cu—Ti alloy and a series of manufacturing conditions of a solution treatment and a cold rolling are controlled, and the strength, bending workability, and stress relaxation characteristics are excellent. Have gotten the material.
In the production process of a Cu—Ti alloy, after solid solution of Ti by solution treatment, cold rolling is performed, and then aging treatment is performed. Since the Cu-Ti alloy contains Ti, which is an extremely active element, a strong oxide film is formed in the aging treatment in the final step, and the solder wettability, the plating property and the like are significantly reduced. In the case of a Cu-Ti alloy, surface oxidation proceeds even when aging treatment is performed in an atmosphere containing hydrogen. In order to avoid this problem, it is necessary to perform an acid washing and polishing step after aging to remove the oxide film. (See Non-Patent Document 1)
When applying Cu plating to a Cu-Ti alloy, a Cu plating step may be added after pickling and polishing after aging in a mill hardened material, and after cold rolling after a solution treatment in a non-milled hardened material. Many.
[0004]
[Patent Document 1]
JP-A-7-258803 [Non-Patent Document 1]
Nippon Mining & Metals Co., Ltd. Kurami Factory Product Catalog [0005]
[Problems to be solved by the invention]
If the surface is oxidized during heat treatment or the like with a decrease in the oxidation resistance, the solderability and the plating property are deteriorated. The problem of oxidation is particularly acute in non-milled hardened materials that undergo aging heat treatment after processing the part. This is because it is technically difficult for a component having a complicated shape to remove a strong oxide film generated during aging by pickling or polishing.
Since the Cu-Ti alloy contains active Ti, oxidation or discoloration of the surface proceeds easily. Cu plating is expected to have the effect of suppressing surface oxidation and discoloration. However, a plated layer that has only been subjected to Cu plating has many pinholes. If pinholes are present in the Cu plating layer, O diffuses from the plating surface to the Cu-Ti alloy surface and Ti is oxidized to promote corrosion. Therefore, the effect of improving the oxidation resistance and corrosion resistance by Cu plating is not so much recognized. I can't.
Further, when the corrosion resistance of Cu plating is low, not only does the surface of Cu plating easily corrode, but even if high corrosion resistance plating such as Au plating is applied, its anticorrosion effect cannot be sufficiently obtained.
On the other hand, Sn plating or solder plating may be applied to the surface of Cu-plated titanium copper. When the Sn plating material is exposed to a high temperature environment for a long time, the Sn plating peels off. This plating exfoliation is caused by the growth of voids and impurity segregation layers at the base material / plating interface. The pinholes in the Cu plating layer promote the growth of voids and impurity segregation layers, and promote the progress of Sn plating peeling. Also, Sn plating peeling occurs early due to an increase in impurities such as S, P, and O in the Cu plating layer.
An object of the present invention is to provide a Cu-plated titanium copper excellent in corrosion resistance, oxidation resistance, plating heat peelability, and solderability.
[0006]
[Means for Solving the Problems]
The inventor has conducted intensive studies on the relationship between the impurities and pinholes of the plating layer and the plating heat peelability, corrosion resistance, oxidation resistance, and solderability, and found the present invention.
That is,
(1) In titanium copper containing 1.5 to 4.5% of Ti, the balance being Cu and unavoidable impurities, and copper plating on the surface, impurities in the copper plating layer are S ≦ 30 ppm, P ≦ 10 ppm, O ≦ 100 ppm, Cu-plated titanium copper,
(2) Titanium copper containing 1.5 to 4.5% of Ti, the balance being Cu and unavoidable impurities, and having a surface plated with copper; Characterized by Cu-plated titanium copper,
(3) Cu-plated titanium copper according to (1) or (2), wherein a heat treatment for recrystallizing the plating layer is performed after Cu plating. copper,
It is.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the reasons for limitation of the present invention will be described.
There are many pinholes in the plating layer that has only been subjected to Cu plating, and S, P, and O are many due to the effect. It is considered that the plating solution or the like captured in the pinhole becomes a source of S, P, and O contamination. Therefore, it can be said that a pinned layer having few S, P, and O has few pinholes. By selecting plating conditions such as current density according to the composition of the bath, it is possible to produce a plating layer with few pinholes in the plating layer and with few S, P, and O. By optimizing the plating conditions, S ≦ 30 ppm, P ≦ 10 ppm, and O ≦ 100 ppm can be achieved. When S> 30 ppm, P> 10 ppm or O> 100 ppm, there are many pinholes in the plating layer, and the corrosion resistance, oxidation resistance and plating heat peeling property are poor.
[0008]
On the other hand, it is not possible to eliminate pinholes in the plating layer only by selecting the composition of the plating bath and the plating conditions such as the current density according to the composition.
Therefore, in the present invention, by rolling titanium copper after Cu plating, pinholes in the plating layer are further reduced. However, if the working ratio is 5% or less, the effect is insufficient. Further, when the working ratio exceeds 80%, the pinholes are reduced, but the bendability of the base material is deteriorated, and it is not suitable for materials such as various terminals, connectors, relays or switches of electronic devices. Here, the rolling degree (R) is defined by the following equation.
R (%) = (t ₀ −t) / t ₀ × 100
t ₀ : Plate thickness before rolling, t: Plate thickness after rolling By heating the Cu-plated titanium copper in a non-oxidizing atmosphere to recrystallize the Cu plating layer, the performance of Cu plating is further improved.
Although the thickness of the Cu plating is not a constituent requirement of the present invention, it is desirable to adjust the thickness between 0.3 and 3 μm. In the case of performing cold rolling after Cu plating, the plating thickness at the time of performing Cu plating is determined such that the Cu plating thickness after cold rolling is 0.3 to 3 μm in consideration of the degree of rolling. If the thickness of the plating is less than 0.3 μm, the effect of improving the oxidation resistance and corrosion resistance by the Cu plating decreases. If the Cu plating thickness exceeds 3 μm, the increase in manufacturing cost cannot be ignored. The effect of the present invention can be obtained even if the plating thickness is out of the range of 0.3 to 3 μm.
[0009]
【Example】
In the present embodiment, a non-mil-hardened material is assumed, and an example in which Cu plating is performed in a step before aging is shown. However, a similar effect can be obtained when Cu plating is performed after aging (mil-hardened material).
The titanium copper used in each of the examples was made of electrolytic copper or oxygen-free copper as a raw material, and a Cu-Ti alloy ingot (thickness: 150 mm) having a Ti concentration of 3% was produced in a high-frequency vacuum melting furnace. Was rolled to 10 mm by hot rolling, and the subsequent steps were processed according to the purpose of the examples.
[0010]
(1) Example 1
The titanium copper was cold-rolled to a thickness of 0.2 mm, subjected to a solution treatment at 780 ° C. to finish the crystal grain size to about 10 μm, and cold-rolled to a thickness of 0.15 mm. Thereafter, Cu plating was applied to a thickness of 1 μm. At the time of Cu plating, S, P, and O in the plating layer were adjusted by changing plating conditions.
The S, P, and O concentrations in the Cu plating layer were analyzed for the sample after the Cu plating. The distribution of pinholes in the plating layer was observed by SEM.
Next, the sample after the Cu plating was heated in a 5% hydrogen-95% nitrogen gas at 420 ° C. for 3 hours, and then the thickness of the oxide film was measured by GDS (glow discharge emission spectroscopy). The oxidation resistance was evaluated. This heating corresponds to the aging treatment, and is performed after the strip is pressed into a part in a non-mill hardened material.
[0011]
Further, the sample after heating at 420 ° C. for 3 hours was evaluated for Sn plating heat resistance, solder wettability, and corrosion resistance.
Plating thermal peelability : After the sample surface was washed in a 10% aqueous sulfuric acid solution, a 1.5 μm-thick Sn plating was applied. Thereafter, the strip test piece was heated at 105 ° C. in the air, and the strip test piece was bent at 90 ° every 50 hours to observe the presence or absence of peeling of the Sn plating, and the time until the Sn plating peeled was obtained.
Corrosion resistance : After the sample surface was washed in a 10% sulfuric acid aqueous solution, gold plating (Ni: 1.5 μm, Au: 0.3 μm) under Ni was applied. Thereafter, a salt spray test according to JIS-C0023 (spray liquid: 5 wt% sodium chloride solution, spray amount: 1.0 to 2.0 ml / h, sample room temperature: 35 ± 2 ° C., sample set angle: 20 °) Was done. The sample was exposed for 24 hours and no discoloration was observed on the plating surface.
Solderability : A strip test piece having a width of 10 mm was collected and washed in a 10% aqueous sulfuric acid solution. According to JIS-C0053, a solder wetting time was measured by a meniscograph method using a rosin-ethanol flux.
Table 1 is an example in which S, P, and O contained in the plating layer were changed.
[0012]
[Table 1]

[0013]
Invention Example No. About 1-3, 5-6, 8-10, S, P, and O were in the claim, and there were few pinholes. Further, the oxide film thickness was less than 10 nm, and therefore, the solder wetting time was less than 3 seconds. No discoloration occurred in the salt spray test after Au plating. Regarding the plating heat stripping time, the Sn plating did not strip until 300 to 400 h.
On the other hand, in Comparative Example No. where S, P, and O were out of the claims. Regarding 4, 7, and 11, many pinholes were observed, and the oxide film thickness exceeded 10 nm, and did not wet with the solder after immersion for 10 seconds. Further, discoloration occurred in the salt spray test after Au plating, and the Sn plating was peeled off within 100 hours.
[0014]
(2) Example 2
The hot-rolled titanium copper (Cu-3% Ti) was rolled to 0.5 mm by cold rolling, subjected to a solution treatment, and plated with 2 μm thick Cu. Invention Example and Comparative Example No. The S, P, and O concentrations of the Cu plating layers 12 to 18 were 24, 8, and 78 ppm, respectively. No. The S, P, and O concentrations of the Cu plating layers of Nos. 19 and 20 were 32, 12, and 120 ppm, respectively. 21 was 35, 15, 150. Thereafter, rolling at a predetermined working degree was performed.
The rolled material was heated at 420 ° C. for 3 hours in 5% hydrogen-95% nitrogen gas for 3 hours to determine the oxide film thickness (oxidation resistance), heat-peeling resistance, corrosion resistance, and solderability in the same manner as in Example 1. evaluated.
[0015]
[Table 2]

[0016]
Table 2 shows the evaluation results of each characteristic. Inventive Examples and Comparative Example Nos. 12 to 18 correspond to claim 3, and all examples correspond to the invention of claim 1.
By performing cold rolling after regulating S, P, and O (Nos. 14 to 17), No. In contrast to No. 12, the oxide film thickness after heating was reduced, the solder wetting time was shortened, and the time until plating peeling was increased. However, when the working degree was less than 5%, In No. 13, the effect of cold rolling is not recognized. On the other hand, No. No. 18 has no problems in plating heat peelability, corrosion resistance, oxidation resistance, and solderability, but the bending property has been significantly degraded by rolling at a high degree of processing, so various terminals, connectors, relays, switches, etc. of electronic equipment It is not suitable for applications where bending deformation is added during use.
In addition, Invention Example No. Comparative Examples Nos. 19 to 21 do not satisfy the range of claim 1 in S, P, and O concentrations, but are not rolled by rolling. 12 or Comparative Example No. As compared with No. 13, a better result was obtained in the plating stripping time. However, in the case of Invention Example No. 1 in which the concentrations of S, P and O satisfy claim 1, It turns out that it is inferior compared with 15,16.
[0017]
(3) Example 3
In the second embodiment, No. After rolling, the sample used in No. 16 was heated at 420 ° C. for 3 hours in a 5% hydrogen-95% nitrogen gas atmosphere corresponding to the aging treatment, and the oxide film thickness (oxidation resistance), heat peeling resistance, corrosion resistance, Solderability was evaluated in the same manner as in Example 1.
[0018]
[Table 3]

[0019]
As shown in Table 3, Invention Example No. Invention Example No. 22 not subjected to aging treatment. Compared with No. 16, the corrosion resistance, the oxidation resistance, the soldering property, and the plating heat peeling property were further improved.
【The invention's effect】
A copper-plated copper alloy with excellent corrosion resistance, oxidation resistance, plating heat peelability, and solderability for titanium copper, which is a material that requires electrical conductivity and spring properties for various terminals, connectors, relays, and switches of electronic equipment I will provide a.

Claims

In the case of titanium copper containing 1.5 to 4.5% of Ti (% is a mass ratio, the same applies hereinafter) and the balance being Cu and unavoidable impurities, the impurities in the copper plating layer of titanium copper having a surface plated with copper , S ≦ 30 ppm, P ≦ 10 ppm, O ≦ 100 ppm, Cu-plated titanium copper.

In the case of titanium copper containing 1.5 to 4.5% of Ti and the balance being Cu and unavoidable impurities, the surface of which is copper-plated is subjected to a rolling process of 5% or more after plating. Cu-plated titanium copper.

The Cu-plated titanium copper according to claim 1.

3. The Cu-plated titanium copper according to claim 1, wherein a heat treatment for recrystallizing the plating layer is performed after the Cu plating.