JP2004300524A

JP2004300524A - Copper or copper alloy member with Sn coating and method of manufacturing the same

Info

Publication number: JP2004300524A
Application number: JP2003095313A
Authority: JP
Inventors: Hiroto Narueda; 宏人成枝
Original assignee: Dowa Mining Co Ltd
Current assignee: Dowa Holdings Co Ltd
Priority date: 2003-03-31
Filing date: 2003-03-31
Publication date: 2004-10-28

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copper or copper alloy member which has an inexpensive coating excellent in electric reliability, leakage resistance, corrosion resistance, solderability and heat resistance on the surface which has been exposed through molding of copper or a copper alloy material into a desired shape. <P>SOLUTION: On at least a part of the surface which has been exposed through molding of the copper or copper alloy member 14 into the desired shape, an Ni-containing layer 16 with a thickness of 0.1-5 μm is formed, a Cu-containing layer 18 with a thickness of 0.2-3 μm is formed on the Ni-containing layer 16, and an Sn-containing layer 20 with a thickness of 0.2-10 μm is formed on the Cu-containing layer 16 to achieve a ratio (thickness ratio of Cu/Sn) of the thickness of the Sn-containing layer 20 to the thickness of the Cu-containing layer 18 of ≤2. After forming the Ni-containing layer 16, the Cu-containing layer 18 and the Sn-containing layer 20 through electroplating, the member is subjected to heating and melting or dipped into molten Sn. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、Ｓｎ被覆を施した銅または銅合金部材に関し、特に、自動車用コネクタ端子、バスバー、電気電子部品の端子などに使用される銅または銅合金部材に関する。
【０００２】
【従来の技術】
端子やバスバーなどの電気電子部品材料として、電気伝導性に優れ、コスト面でも優れた銅または銅合金が広く利用されている。このような端子材料の最表面には、電気的信頼性、耐食性、はんだ付け性、外観およびコスト面の観点から、Ｓｎ被覆が施されることが多い。この被覆では、耐ウイスカ性に優れた溶融加熱処理や溶融Ｓｎ浸漬処理が広く利用されている。
【０００３】
また、従来、自動車用ジャンクションブロック（以下「Ｊ／Ｂ」という）内のバスバーとリレーやヒューズなどとの接続には、両側が雌構造の中継端子が使用されていたが、近年、部品の小型化や低コスト化の観点から中継端子がない構造になり、バスバー内に成形された音叉型端子によってバスバーにリレーやヒューズなどが接続されるようになっている。このバスバーはＳｎめっきが施された銅または銅合金条から成形され、音叉型端子の表面にもＳｎめっきが施されているが、リレーやヒューズなどの脚部と接続される部分では、プレス時に打ち抜かれて素材が露出した切断面がそのまま接触するようになっている。また、小型化や電気制御品の増加に伴う高密度化により、バスバー間の隙間が狭くなっており、このようなバスバー間の対向する面もプレス打ち抜き面であり、素材が露出した面になっている。
【０００４】
また、自動車用や民生用の端子においても、小型化や多極化により端面接触させる構造が増えている。この場合、Ｊ／Ｂの音叉型端子よりも接圧が小さいことから（Ｊ／Ｂの音叉型端子の場合は接圧が１０Ｎ以上であり、小型端子の場合は接圧が０．１〜２０Ｎ程度）、電気的信頼性を保つために、プレス後に素材の表面および端面にＮｉ下地Ａｕめっき、はんだめっきまたは光沢Ｓｎめっきなどが施されている。さらに、端子の電線接合方式として、端面で電線の被覆を破って電線芯と接続する圧接方式も広く利用されている。この端面にも、電線との電気的信頼性を保つために、プレス後にはんだめっきまたは光沢Ｓｎめっきが施されることが多い。
【０００５】
また、銅または銅合金部材の被覆については、タンタルコンデンサー用リードフレーム材の耐熱剥離性およびはんだ濡れ性を向上させるために、洋白（Ｃｕ−Ｎｉ−Ｚｎ系合金）からなる基材上に、Ｎｉめっき層、０．２〜２．０μｍの厚さのＣｕ−Ｓｎ合金層およびＳｎめっき層（またははんだめっき層）を順次形成することが知られている（例えば、特許文献１参照）。また、銅合金などの素材表面の耐熱性、成形加工性、はんだ付け性などを向上させるために、銅合金などの素材表面に、表面側から順にＮｉまたはＮｉ合金層、Ｃｕ層、ＳｎまたはＳｎ合金層を被覆した後にリフロー処理を施すことが知られている（例えば、特許文献２参照）。さらに、バスバーの表面の耐リーク性を向上させるために、銅または銅合金板条にＮｉまたはＮｉ合金めっき層を形成し、その上にＳｎまたはＳｎ合金層を形成することが知られている（例えば、特許文献３参照）。
【０００６】
【特許文献１】
特開平６−１９６３４９号公報（段落番号０００７−０００８）
【特許文献２】
特開２００２−２２６９８２号公報（段落番号０００４）
【特許文献３】
特開２００１−２０３０２０号公報（段落番号０００７）
【０００７】
【発明が解決しようとする課題】
しかし、従来のＪ／Ｂでは、音叉型端子の端面において素材が露出しており、接圧によって電気的信頼性を補完するために、挿入力が増大したり、耐応力緩和特性の素材依存度が大きいなどの問題があった。また、バスバー間の隙間の狭幅化や素材の露出面の対向によって、結露による水分や外部環境からの混入水などによるリークの発生が問題となっていた。そのため、プレス後の音叉型端子の端面およびバスバーの端面に電気的信頼性が高く且つ耐リーク性に優れた表面処理が施されれば、素材の選定において、より導電性の高い材料や低コストの材料を選択することができる。
【０００８】
また、小型端子では、Ｎｉ下地Ａｕめっきの場合にはコストが高く、はんだめっきの場合にはＰｂを含むため環境負荷が大きく、光沢Ｓｎめっきの場合には耐ウイスカ性および耐熱性が悪いという問題がある。この場合、ウイスカ対策としてＳｎめっき後に加熱溶融処理を行ったとしても、自動車のエンジンルームなどの高温環境では、十分な耐熱性を確保することはできない。そのため、Ｎｉ下地Ａｕめっきよりも低コストで、Ｐｂなどの有害元素を含まず、耐ウイスカ性に優れ、通常のＳｎめっきよりも耐熱性に優れた表面処理を端面に施した銅または銅合金部材が求められていた。
【０００９】
また、特許文献１は、銅合金部材の耐熱剥離性およびはんだ濡れ性を向上させることについて開示しているが、電気的信頼性、耐リーク性、耐食性および耐熱性を向上させることについては開示していない。また、特許文献２は、銅合金などの素材の表面の耐熱性、成形加工性、はんだ付け性などを向上させることについて開示しているが、端面の電気的信頼性、耐リーク性および耐食性を向上させることについては開示していない。さらに、特許文献３に開示された方法では、バスバーの表面の耐リーク性の向上を目的としているが、下地層のＮｉが表層に拡散して高温保持後の接触抵抗が増加するため、耐熱性が十分ではない。また、端面の電気的信頼性、耐リーク性および耐食性を向上させることについても開示していない。
【００１０】
したがって、本発明は、このような従来の問題点に鑑み、銅または銅合金の素材を所望の形状に成形することにより露出した面に、電気的信頼性、耐リーク性、耐食性、はんだ付け性および耐熱性に優れた安価な被覆を施した銅または銅合金部材を提供することを目的とする。また、本発明は、上記の特性に加えて耐ウイスカ性にも優れた被覆を施した銅または銅合金部材を提供することを目的とする。
【００１１】
【課題を解決するための手段】
本発明者らは、上記課題を解決するために鋭意研究した結果、銅または銅合金の素材を所望の形状に成形することにより露出した面の少なくとも一部に、厚さ０．１〜５μｍのＮｉ含有層を形成し、このＮｉ含有層の上に厚さ０．２〜３μｍのＣｕ含有層を形成し、このＣｕ含有層の上に厚さ０．２〜１０μｍのＳｎ含有層を形成し、Ｓｎ含有層の厚さに対するＣｕ含有層の厚さの比（Ｃｕ／Ｓｎ厚さ比）が２以下になるようにすることにより、素材の成形により露出した面の少なくとも一部において、電気的信頼性、耐リーク性、耐食性、はんだ付け性および耐熱性に優れた安価な被覆を施した銅または銅合金部材を提供することができることを見出し、本発明を完成するに至った。
【００１２】
すなわち、本発明によるＳｎ被覆を施した銅または銅合金部材は、銅または銅合金の素材を所望の形状に成形することにより露出した面の少なくとも一部に、厚さ０．１〜５μｍのＮｉ含有層が形成され、このＮｉ含有層の上に厚さ０．２〜３μｍのＣｕ含有層が形成され、このＣｕ含有層の上に厚さ０．２〜１０μｍのＳｎ含有層が形成され、Ｓｎ含有層の厚さに対するＣｕ含有層の厚さの比（Ｃｕ／Ｓｎ厚さ比）が２以下であることを特徴とする。
【００１３】
このＳｎ被覆を施した銅または銅合金部材において、露出した面がプレス、ワイヤカットまたはエッチング加工により露出した面であり、露出した面の少なくとも一部が、他の部材と電気的に接触する端面または耐リーク性が必要な端面であるのが好ましい。また、Ｃｕ含有層の一部または全部がＣｕ_６Ｓｎ_５やＣｕ_３ＳｎなどのＣｕ−Ｓｎ合金層を含むのが好ましい。また、Ｎｉ含有層がＮｉからなる層であり、Ｃｕ含有層がＣｕからなる層であり、Ｓｎ含有層がＳｎからなる層にしてもよい。あるいは、Ｎｉ含有層がＮｉに加えてＣｏ、Ｃｕ、ＰおよびＳの１種以上を０〜１０重量％含有し、Ｃｕ含有層がＣｕに加えてＺｎ、ＮｉおよびＳｎの１種以上を０〜１０重量％含有し、Ｓｎ含有層がＳｎに加えてＰｂ、Ｚｎ、Ｎｉ、ＣｕおよびＡｇの１種以上を０〜２０重量％含有してもよい。
【００１４】
また、本発明によるＳｎ被覆を施した銅または銅合金部材の製造方法は、銅または銅合金の素材を所望の形状に成形し、この成形により露出した面の少なくとも一部に厚さ０．１〜５μｍのＮｉ含有層を形成し、このＮｉ含有層の上に厚さ０．２〜３μｍのＣｕ含有層を形成し、このＣｕ含有層の上に厚さ０．２〜１０μｍのＳｎ含有層を形成し、Ｓｎ含有層の厚さに対するＣｕ含有層の厚さの比（Ｃｕ／Ｓｎ厚さ比）を２以下にすることを特徴とする。
【００１５】
このＳｎ被覆を施した銅または銅合金部材の製造方法において、銅または銅合金の素材の成形が、プレス、ワイヤカットまたはエッチング加工により行われるのが好ましい。また、露出した面の少なくとも一部が、他の部材と電気的に接触する端面または耐リーク性が必要な端面であるのが好ましい。また、Ｎｉ含有層とＣｕ含有層とＳｎ含有層を形成した後に、プレスなどの二次加工を行うのが好ましい。また、Ｎｉ含有層とＣｕ含有層とＳｎ含有層を電気めっきにより形成するのが好ましい。さらに、Ｓｎ含有層を電気めっきした後に加熱溶融処理または溶融Ｓｎ浸漬処理を行うのが好ましい。
【００１６】
さらに、本発明による電気または電子部材は、銅または銅合金の素材を所望の形状に成形することにより露出した面の少なくとも一部に、厚さ０．１〜５μｍのＮｉ含有層が形成され、このＮｉ含有層の上に厚さ０．２〜３μｍのＣｕ含有層が形成され、このＣｕ含有層の上に厚さ０．２〜１０μｍのＳｎ含有層が形成され、Ｓｎ含有層の厚さに対するＣｕ含有層の厚さの比（Ｃｕ／Ｓｎ厚さ比）が２以下であることを特徴とする。
【００１７】
この電気または電子部材において、露出した面がプレス、ワイヤカットまたはエッチング加工により露出した面であるのが好ましく、露出した面の少なくとも一部が、他の端子、バスバーまたは電線と電気的に接触する端面または耐リーク性が必要な端面であるのが好ましい。
【００１８】
【発明の実施の形態】
本発明によるＳｎ被覆を施した銅または銅合金部材の製造方法の実施の形態では、まず、銅または銅合金の板または条の端面において電気的接続の信頼性、耐リーク性、耐食性およびはんだ付け性が必要な端子やバスバーなどの端面を、プレス、ワイヤーカットまたはエッチング加工などにより露出させる。次いで、表面および露出した端面をめっきや蒸着などにより厚さ０．１〜５μｍのＮｉ含有層で被覆した後、厚さ０．２〜３μｍのＣｕ含有層で被覆する。その上を厚さ０．２〜１０μｍのＳｎ含有層でめっき、蒸着または溶融金属浸漬処理などにより被覆する。このＳｎ含有層の厚さは、Ｓｎ含有層の厚さに対するＣｕ含有層の厚さの比（以下、「Ｃｕ／Ｓｎ厚さ比」という）が２以下になるようにする。Ｓｎ含有層の被覆方法がＳｎ浸漬以外の場合には、その後に加熱溶融処理を行って、Ｓｎ被覆した銅または銅合金部材を形成する。なお、上述した被覆層の厚さは、端子やバスバーなどに成形されて、他の端子、バスバーまたは電線などと電気的に接触する端面や、耐リーク性、耐食性およびはんだ付け性が必要な端面における被覆層の厚さであるが、端面以外の表面でも他の電気部品と接続される部分がある場合には、電気的信頼性、耐熱性、耐食性およびはんだ付け性などの観点から、上述した厚さで被覆するのが好ましい。
【００１９】
Ｎｉ含有層は、Ｎｉの他にＣｏ、Ｃｕ、ＰおよびＳの１種以上を０〜１０重量％含有してもよい。また、Ｃｕ含有層は、Ｚｎ、ＮｉおよびＳｎの１種以上を０〜１０重量％含有してもよい。さらに、Ｓｎ含有層は、Ｐｂ、Ｚｎ、Ｎｉ、ＣｕおよびＡｇの１種以上を０〜２０重量％含有してもよい。
【００２０】
次に、Ｎｉ含有層の厚さを０．１〜５μｍとした理由を説明する。Ｎｉ含有層で被覆する主な目的は、素材である銅および銅合金の成分の表層への拡散防止と、耐リーク性の向上である。Ｎｉ含有層の厚さが０．１μｍ未満では、拡散防止および耐リーク性の向上の効果が小さく、一方、Ｎｉ含有層の厚さが５μｍを超えると、経済的に不利になり、端面と同時に被覆した平面部において追加の曲げ加工を行った際にＮｉ含有層が起点となってクラックが生じる場合がある。なお、上記の目的を達成するためには、Ｎｉの他にＣｏ、Ｃｕ、ＰおよびＳの１種以上を０〜１０重量％含有してもよいが、１０重量％を超えて含有すると、５μｍ以下の厚さでもクラックが生じ易くなる。
【００２１】
次に、Ｃｕ含有層の厚さを０．２〜３μｍとした理由を説明する。Ｃｕ含有層で被覆する主な目的は、下被覆層のＮｉと上被覆層のＳｎとの合金化の抑制である。Ｃｕ含有層がない場合、ＮｉとＳｎが合金化し、経時変化によってＮｉが被覆の最表面に拡散して電気比抵抗の大きい酸化物を形成するため、電気的信頼性が低下する。Ｃｕ含有層の厚さが０．２μｍ未満では、Ｎｉ−Ｓｎ合金化の抑制効果が十分ではない。また、Ｃｕ含有層のＣｕは、上層のＳｎに拡散してＣｕ_６Ｓｎ_５やＣｕ_３ＳｎなどのＣｕ−Ｓｎ合金層を形成する。Ｃｕが過剰に存在すると、残ったＣｕが表層に拡散してＳｎ酸化物よりも電気比抵抗の大きい酸化物を形成するため、電気的信頼性が低下する。そのため、Ｃｕ含有層の厚さの上限を３μｍとし、Ｃｕ／Ｓｎ厚さ比を２以下にする。
【００２２】
次に、Ｓｎ含有層の厚さを０．２〜１０μｍとした理由を説明する。Ｓｎ含有層は、本来、電気的接続信頼性、耐食性およびはんだ付け性などを確保するために施されるものであり、Ｓｎ含有層の厚さが０．２μｍ未満では、その機能を保つことができず、一方、１０μｍを超えると、経済的に不利となる。
【００２３】
なお、Ｓｎ含有層の被覆方法を、電気めっき後に加熱溶融処理を行う方法または溶融Ｓｎ浸漬処理による方法とした理由は、耐ウイスカ性を向上させるためである。但し、耐ウイスカ性を必要としない場合は、加熱溶融処理や溶融Ｓｎ浸漬処理を行わなくてもよい。
【００２４】
また、本発明によるＳｎ被覆を施した銅または銅合金部材を音叉型端子に適用した例を図１および図２に示す。図１および図２に示すように、音叉型端子１０の対向する端面間に舌片型端子１２が挿入されて嵌合することにより、両者の電気的接続が行われるようになっている。舌片型端子１２と嵌合する音叉型端子１０の端部の被覆構造は、図３（ａ）および図３（ｂ）に示すように、素材としての銅または銅合金部材１４の端部の表面をＮｉ層で被覆し、その上をＣｕ−Ｓｎ層（またはＣｕ層＋Ｃｕ−Ｓｎ層）１８で被覆し、その上をＳｎ層２０で被覆する構造になっている。ここで、図３（ａ）は、銅または銅合金の素材をプレスなどによって音叉型端子１０の内側の部分（舌片型端子１２と電気的接続が行われる部分を含む）を成形した後に、上記の被覆を施し、その後、プレスなどによって音叉型端子１０の外側の部分を成形して、舌片型端子１２と電気的接続が行われる部分と反対側の部分を除去した例を示し、図３（ｂ）は、銅または銅合金の素材をプレスなどによって音叉型端子１０の形状に成形した後に、上記の被覆を施した例を示している。なお、上記の被覆を施す必要がない部分に上記の被覆を施さないで、舌片型端子１２と電気的接続が行われる部分のみに上記の被覆を施してもよい。
【００２５】
【実施例】
以下、本発明によるＳｎ被覆を施した銅または銅合金部材およびその製造方法の実施例について詳細に説明する。
【００２６】
［実施例１］
まず、ビッカース硬さＨＶ１０５、厚さ０．８ｍｍ、幅１０ｍｍ、長さ６０ｍｍのＣ１０２０（無酸素銅）からなる試験片をプレス金型で打ち抜いて作製した。この試験片の表面および端面を電解脱脂と酸洗により活性化した後、試験片の一端から３０ｍｍまでの部分を、厚さ０．５μｍのＮｉ層、厚さ０．５μｍのＣｕ層および厚さ２μｍのＳｎ層で順次被覆し、加熱溶融処理を行った。これらの層の被覆は、厚さの制御に優れ且つコスト的にも有利な電気めっきにより行った。Ｎｉめっきはスルファミン酸Ｎｉ浴、Ｃｕめっきは硫酸銅浴、Ｓｎめっきは硫酸錫浴によって行った。各めっき浴にはいずれも光沢剤を添加せず、無光沢めっきを行った。また、表面と端面のめっき厚が等しくなるように陽極板の位置を調整した。加熱溶融処理は、対向させたバーナー間で試験片のめっき部を熱して、表面全体に光沢が広がった直後に、バーナーの下に設置した水槽内に落下させて水冷する方法によって行った。
【００２７】
Ｎｉ被覆層の厚さは、上記と同じめっき条件によりＮｉのみでめっきした試験片を、端面が水平になるように固定し、コリメーターをφ０．１ｍｍとして蛍光Ｘ線膜厚測定器によって測定した。Ｓｎ被覆層の厚さも同様に測定した。Ｃｕ被覆層の厚さは、Ｎｉめっき後にＣｕめっきした試験片を樹脂に埋め込んだ後に研磨し、その断面を走査型電子顕微鏡（ＳＥＭ）で１万倍に拡大して観察することによって測定した。
【００２８】
次に、この実施例で得られた試験片について、大気雰囲気中において１６０℃で１２０時間保持した後の接触抵抗値によって耐熱性を評価した。この接触抵抗値は、マイクロオームメーターを使用し、開放電圧２０ｍＶ、電流１０ｍＡ、０．５φｍｍのＵ型金線プローブ、最大荷重１００ｇｆ、摺動無しの条件で、試験数Ｎ＝３回測定し、その平均値を求めた。この測定の際にプローブが試験片の端面に垂直に接触するように試験片をジグで固定した。なお、この実施例で得られた試験片の耐熱性の評価の前に測定した接触抵抗値は５ｍΩであった。
【００２９】
また、図３に示すように、この実施例で得られた一対の同じ試験片１００を１ｍｍ離間して対向するように樹脂板１０２に固定した。この試験片１００の先端１０ｍｍの部分を、純水に亜硫酸ナトリウムを加えて８５μＳ／ｃｍに調整した０．５Ｌの試験水溶液１０４中に浸漬し、直流電源１０６により両極に直流電圧１４Ｖを印加した状態でリークした電流を電流計１０８により測定した。この測定をリーク電流が１Ａを超えるまで行い、要した時間により試験片１００の耐リーク性を評価した。なお、１２０分経過してもリーク電流が１Ａを超えない場合は測定を終了した。
【００３０】
また、この実施例で得られた試験片について、９０゜Ｗ曲げ試験（内側曲げ半径０．８ｍｍ）を行った後、曲げ部の表面を観察し、割れの有無により曲げ加工性を評価した。
【００３１】
これらの試験の結果、大気雰囲気中において１６０℃で１２０時間保持した後の接触抵抗値が５ｍΩであり、耐リーク性の評価において１２０分経過してもリーク電流が１Ａを超えず、曲げ加工性の評価において割れが観察されなかった。したがって、この実施例で得られた試験片は、耐熱性、耐リーク性、曲げ加工性のいずれも優れていることがわかった。
【００３２】
［実施例２］
Ｎｉ層の厚さを０．１μｍ、Ｃｕ層の厚さを０．２μｍ、Ｓｎ層の厚さを０．５μｍとした以外は実施例１と同様の方法により試験片を作製し、実施例１と同様の試験を行った。なお、この実施例で得られた試験片の耐熱性の評価の前に測定した接触抵抗値は５ｍΩであった。
【００３３】
この実施例では、大気雰囲気中において１６０℃で１２０時間保持した後の接触抵抗値が８２ｍΩであり、耐リーク性の評価において１２０分経過してもリーク電流が１Ａを超えず、曲げ加工性の評価において割れが観察されなかった。したがって、この実施例で得られた試験片は、耐熱性、耐リーク性、曲げ加工性のいずれも優れていることがわかった。
【００３４】
［実施例３］
Ｎｉ層の厚さを２μｍ、Ｃｕ層の厚さを１μｍ、Ｓｎ層の厚さを１．５μｍとした以外は実施例１と同様の方法により試験片を作製し、実施例１と同様の試験を行った。なお、この実施例で得られた試験片の耐熱性の評価の前に測定した接触抵抗値は５ｍΩであった。
【００３５】
この実施例では、大気雰囲気中において１６０℃で１２０時間保持した後の接触抵抗値は１７ｍΩであり、耐リーク性の評価において１２０分経過してもリーク電流が１Ａを超えず、曲げ加工性の評価において割れが観察されなかった。したがって、この実施例で得られた試験片は、耐熱性、耐リーク性、曲げ加工性のいずれも優れていることがわかった。
【００３６】
［比較例１］
被覆を行わなかった以外は実施例１と同様の試験片（裸材）を用意し、実施例１と同様の試験を行った。なお、この比較例の試験片の耐熱性の評価の前に測定した接触抵抗値は１８ｍΩであった。
【００３７】
この比較例では、大気雰囲気中において１６０℃で１２０時間保持した後の接触抵抗値が２０００ｍΩを超え、接触信頼性に欠けていた。また、耐リーク性の評価において１８分で１Ａを超え、耐リーク性に劣っていた。接触抵抗値が２０００ｍΩを超えた原因は、素材のＣｕが酸化したためであり、耐リーク性に劣っていた原因は、陽極側から溶出したＣｕが容易に陰極に析出して陽極−陰極間にブリッジを形成したためである。
【００３８】
［比較例２］
厚さ１μｍのＳｎ層のみで被覆した以外は実施例１と同様の試験片を作製し、実施例１と同様の試験を行った。なお、この比較例の試験片の耐熱性の評価の前に測定した接触抵抗値は５ｍΩであった。
【００３９】
この比較例では、大気雰囲気中において１６０℃で１２０時間保持した後の接触抵抗値が２７７ｍΩであり、接触信頼性に欠けていた。また、耐リーク性の評価において１００分で１Ａを超え、耐リーク性に劣っていた。接触抵抗値が１００ｍΩを超えた原因は素材のＣｕが最表層に拡散してＣｕ酸化物を形成したためである。
【００４０】
［比較例３］
Ｎｉ層の厚さを１μｍ、Ｓｎ層の厚さを１μｍとし、Ｃｕ被覆を施さなかった以外は実施例１と同様の試験片を作製し、実施例１と同様の試験を行った。なお、この比較例の試験片の耐熱性の評価の前に測定した接触抵抗値は５ｍΩであった。
【００４１】
この比較例では、大気雰囲気中において１６０℃で１２０時間保持した後の接触抵抗値が２０５ｍΩであり、接触信頼性に欠けていた。接触抵抗値が１００ｍΩを超えた原因は、下地の被覆層中のＮｉが最表層に拡散してＮｉ酸化物を形成したためである。
【００４２】
［比較例４］
Ｎｉ層の厚さを６μｍ、Ｃｕ層の厚さを０．５μｍ、Ｓｎ層の厚さを１μｍとした以外は実施例１と同様の方法により試験片を作製し、実施例１と同様の試験を行った。なお、この比較例で得られた試験片の耐熱性の評価の前に測定した接触抵抗値は５ｍΩであった。
【００４３】
この比較例では、大気雰囲気中において１６０℃で１２０時間保持した後の接触抵抗値が２４ｍΩであり、耐リーク性の評価において１２０分経過してもリーク電流が１Ａを超えなかった。したがって、この比較例で得られた試験片は、耐熱性および耐リーク性には優れていた。しかし、Ｎｉ層が厚すぎるため、曲げ加工性の評価において割れが観察された。
【００４４】
［比較例５］
Ｎｉ層の厚さを０．５μｍ、Ｃｕ層の厚さを０．１μｍ、Ｓｎ層の厚さを０．１μｍとした以外は実施例１と同様の方法により試験片を作製し、実施例１と同様の試験を行った。なお、この比較例で得られた試験片の耐熱性の評価の前に測定した接触抵抗値は１５ｍΩであった。
【００４５】
この比較例では、大気雰囲気中において１６０℃で１２０時間保持した後の接触抵抗値が２０００ｍΩを超え、接触信頼性に欠けていた。接触抵抗値が１００ｍΩを超えた原因は、Ｓｎ被覆層が薄く、下地の被覆層の成分（Ｎｉ、Ｃｕ）が最表層で酸化物を形成したためである。
【００４６】
［比較例６］
Ｎｉ層の厚さを１μｍ、Ｃｕ層の厚さを２μｍ、Ｓｎ層の厚さを０．５μｍとした以外は実施例１と同様の方法により試験片を作製し、実施例１と同様の試験を行った。なお、この比較例で得られた試験片の耐熱性の評価の前に測定した接触抵抗値は５ｍΩであった。
【００４７】
この比較例では、大気雰囲気中において１６０℃で１２０時間保持した後の接触抵抗値が３１１ｍΩであり、接触信頼性に欠けていた。接触抵抗値が１００ｍΩを超えた原因は、Ｃｕ／Ｓｎ厚さ比が大きく、過剰に残ったＣｕ被覆層の成分が最表層に拡散してＣｕ酸化物を形成したためである。
【００４８】
なお、実施例１〜３および比較例１〜６の結果を表１に示す。
【００４９】
【表１】

【００５０】
【発明の効果】
上述したように、本発明によるＳｎ被覆を施した銅または銅合金部材は、特に成形によって露出した端面の耐熱性および耐リーク性に優れているため、部材の端面が端子、バスバー、電線などに電気的に接続される部位を含むコネクタ端子やバスバー、耐リーク性が要求されるバスバーやリードフレームなどの電気電子部品用材料として優れている。また、部材の端面の耐食性およびはんだ付け性も向上させることができるので、ＰＣＢ端子などの端子の端面の耐食性やはんだ付け性が要求される分野にも応用できる。
【図面の簡単な説明】
【図１】本発明によるＳｎ被覆を施した銅または銅合金部材を利用した音叉型端子とその音叉型端子に挿入される舌片型端子を示す斜視図。
【図２】図１の音叉型端子の平面図。
【図３】図１の音叉型端子の被覆構造の例を示す、図１のＩＩＩ−ＩＩＩ線断面図。
【図４】実施例および比較例における耐リーク性の試験を説明する図。
【符号の説明】
１０音叉型端子
１２舌片型端子
１４銅または銅合金部材
１６Ｎｉ層
１８Ｃｕ−Ｓｎ層（またはＣｕ層＋Ｃｕ−Ｓｎ層）
２０Ｓｎ層
１００試験片
１０２樹脂板
１０４試験水溶液
１０６直流電源（１４Ｖ）
１０８電流計[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a copper or copper alloy member coated with Sn, and more particularly to a copper or copper alloy member used for a connector terminal for an automobile, a bus bar, a terminal of an electric / electronic component, and the like.
[0002]
[Prior art]
Copper or copper alloys, which are excellent in electric conductivity and low in cost, are widely used as materials for electric and electronic parts such as terminals and bus bars. The outermost surface of such a terminal material is often coated with Sn from the viewpoints of electrical reliability, corrosion resistance, solderability, appearance and cost. In this coating, a melting heat treatment and a molten Sn immersion treatment having excellent whisker resistance are widely used.
[0003]
Conventionally, a relay terminal having a female structure on both sides has been used to connect a bus bar and a relay or a fuse in a junction block (hereinafter referred to as “J / B”) for an automobile. From the viewpoint of cost reduction and cost reduction, a structure without a relay terminal is adopted, and a relay, a fuse, or the like is connected to the bus bar by a tuning fork type terminal formed in the bus bar. This busbar is formed from Sn-plated copper or copper alloy strip, and the surface of the tuning fork type terminal is also Sn-plated. The cut surface, which is punched and the material is exposed, comes into contact with it. In addition, the gap between the bus bars is becoming narrower due to the miniaturization and the increase in the density due to the increase in the number of electric control products, and the opposing surface between such bus bars is also a press punched surface, and the material is exposed. ing.
[0004]
Further, also for terminals for automobiles and consumer use, a structure for bringing the end surfaces into contact with each other has been increasing due to miniaturization and multipolarization. In this case, since the contact pressure is smaller than that of the J / B tuning fork type terminal (the contact pressure is 10 N or more for the J / B tuning fork type terminal and 0.1 to 20 N for the small terminal). In order to maintain electrical reliability, the surface and the end face of the material are subjected to Au plating, solder plating, bright Sn plating, or the like on the Ni base after pressing. Further, as a wire joining method of terminals, a pressure welding method of breaking a sheath of an electric wire at an end face and connecting to a wire core is also widely used. This end face is also often subjected to solder plating or bright Sn plating after pressing in order to maintain electrical reliability with the electric wire.
[0005]
Regarding the coating of copper or a copper alloy member, in order to improve the heat-peeling resistance and solder wettability of the lead frame material for a tantalum capacitor, on a base material made of nickel silver (Cu-Ni-Zn-based alloy), It is known that a Ni plating layer, a Cu—Sn alloy layer having a thickness of 0.2 to 2.0 μm, and a Sn plating layer (or a solder plating layer) are sequentially formed (for example, see Patent Document 1). In addition, in order to improve heat resistance, molding workability, solderability, and the like of the surface of the material such as a copper alloy, a Ni or Ni alloy layer, a Cu layer, Sn or Sn It is known to perform a reflow treatment after coating an alloy layer (for example, see Patent Document 2). Further, it is known to form a Ni or Ni alloy plating layer on a copper or copper alloy plate and form an Sn or Sn alloy layer thereon to improve the leak resistance of the surface of the bus bar ( For example, see Patent Document 3).
[0006]
[Patent Document 1]
JP-A-6-196349 (paragraphs 0007-0008)
[Patent Document 2]
JP-A-2002-226982 (paragraph number 0004)
[Patent Document 3]
JP 2001-203020 A (Paragraph No. 0007)
[0007]
[Problems to be solved by the invention]
However, in the conventional J / B, the material is exposed at the end face of the tuning fork-type terminal, and in order to supplement the electrical reliability by the contact pressure, the insertion force is increased, and the material dependence of the stress relaxation resistance is increased. There was a problem such as large. Also, due to the narrowing of the gap between the bus bars and the facing of the exposed surface of the material, the occurrence of leaks due to moisture due to dew condensation or water mixed in from the external environment has been a problem. Therefore, if the end face of the tuning fork type terminal and the end face of the bus bar after pressing are subjected to a surface treatment with high electrical reliability and excellent leak resistance, in selecting a material, a material having higher conductivity and a lower cost can be used. Material can be selected.
[0008]
In the case of small terminals, the cost is high in the case of Au plating over Ni, the environmental load is large because Pb is contained in the case of solder plating, and the whisker resistance and heat resistance are poor in the case of bright Sn plating. There is. In this case, even if heat melting treatment is performed after Sn plating as a measure for whisker, sufficient heat resistance cannot be ensured in a high temperature environment such as an engine room of an automobile. Therefore, a copper or copper alloy member which has been subjected to a surface treatment that is lower in cost than Ni-base Au plating, does not contain harmful elements such as Pb, has excellent whisker resistance, and has better heat resistance than ordinary Sn plating. Was required.
[0009]
Patent Document 1 discloses improving the heat-peeling resistance and solder wettability of a copper alloy member, but discloses improving electrical reliability, leak resistance, corrosion resistance and heat resistance. Not. Patent Document 2 discloses improving the heat resistance, molding workability, solderability, and the like of the surface of a material such as a copper alloy. However, the electrical reliability, leak resistance, and corrosion resistance of the end face are disclosed. No improvement is disclosed. Further, the method disclosed in Patent Document 3 aims at improving the leak resistance of the surface of the bus bar. However, since the Ni of the underlayer diffuses into the surface layer to increase the contact resistance after holding at a high temperature, the heat resistance is increased. Is not enough. Moreover, it does not disclose improving the electrical reliability, leak resistance, and corrosion resistance of the end face.
[0010]
Accordingly, the present invention has been made in view of the above-mentioned conventional problems, and it has been found that electrical reliability, leak resistance, corrosion resistance, and solderability can be provided on a surface exposed by molding a copper or copper alloy material into a desired shape. Another object of the present invention is to provide an inexpensive copper or copper alloy member having excellent heat resistance. Another object of the present invention is to provide a copper or copper alloy member coated with excellent whisker resistance in addition to the above characteristics.
[0011]
[Means for Solving the Problems]
The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, at least a part of a surface exposed by molding a copper or copper alloy material into a desired shape has a thickness of 0.1 to 5 μm. A Ni-containing layer is formed, a Cu-containing layer having a thickness of 0.2 to 3 μm is formed on the Ni-containing layer, and a Sn-containing layer having a thickness of 0.2 to 10 μm is formed on the Cu-containing layer. By controlling the ratio of the thickness of the Cu-containing layer to the thickness of the Sn-containing layer (Cu / Sn thickness ratio) to be 2 or less, at least a part of the surface exposed by molding of the material is electrically connected. The present inventors have found that it is possible to provide an inexpensive coated copper or copper alloy member having excellent reliability, leak resistance, corrosion resistance, solderability, and heat resistance, and have completed the present invention.
[0012]
That is, the copper or copper alloy member provided with the Sn coating according to the present invention has a Ni or Ni alloy having a thickness of 0.1 to 5 μm on at least a part of a surface exposed by molding a copper or copper alloy material into a desired shape. A Cu-containing layer having a thickness of 0.2 to 3 μm is formed on the Ni-containing layer; a Sn-containing layer having a thickness of 0.2 to 10 μm is formed on the Cu-containing layer; The ratio of the thickness of the Cu-containing layer to the thickness of the Sn-containing layer (Cu / Sn thickness ratio) is 2 or less.
[0013]
In the copper or copper alloy member provided with the Sn coating, an exposed surface is a surface exposed by pressing, wire cutting or etching, and at least a part of the exposed surface is an end surface which is in electrical contact with another member. Alternatively, it is preferable that the end surface has leak resistance. In addition, it is preferable that a part or the whole of the Cu-containing layer includes a Cu—Sn alloy layer such as Cu ₆ Sn ₅ or Cu ₃ Sn. Further, the Ni-containing layer may be a layer made of Ni, the Cu-containing layer may be a layer made of Cu, and the Sn-containing layer may be a layer made of Sn. Alternatively, the Ni-containing layer contains 0 to 10% by weight of one or more of Co, Cu, P and S in addition to Ni, and the Cu-containing layer contains one or more of Zn, Ni and Sn in addition to Cu. 10% by weight, and the Sn-containing layer may contain 0 to 20% by weight of one or more of Pb, Zn, Ni, Cu and Ag in addition to Sn.
[0014]
In addition, the method of manufacturing a copper or copper alloy member coated with Sn according to the present invention comprises forming a copper or copper alloy material into a desired shape, and forming at least a part of a surface exposed by this molding to a thickness of 0.1%. Forming a Ni-containing layer having a thickness of 0.2 to 3 μm, forming a Cu-containing layer having a thickness of 0.2 to 3 μm on the Ni-containing layer, and forming a Sn-containing layer having a thickness of 0.2 to 10 μm on the Cu-containing layer. Is formed, and the ratio of the thickness of the Cu-containing layer to the thickness of the Sn-containing layer (Cu / Sn thickness ratio) is set to 2 or less.
[0015]
In the method for producing a copper or copper alloy member coated with Sn, it is preferable that the copper or copper alloy material is formed by pressing, wire cutting, or etching. It is preferable that at least a part of the exposed surface is an end surface that is in electrical contact with another member or an end surface that requires leak resistance. After forming the Ni-containing layer, the Cu-containing layer, and the Sn-containing layer, it is preferable to perform secondary processing such as pressing. Further, it is preferable to form the Ni-containing layer, the Cu-containing layer and the Sn-containing layer by electroplating. Further, it is preferable to perform a heat melting treatment or a molten Sn immersion treatment after electroplating the Sn-containing layer.
[0016]
Further, in the electric or electronic member according to the present invention, a Ni-containing layer having a thickness of 0.1 to 5 μm is formed on at least a part of a surface exposed by molding a copper or copper alloy material into a desired shape, A Cu-containing layer having a thickness of 0.2 to 3 μm is formed on the Ni-containing layer, and a Sn-containing layer having a thickness of 0.2 to 10 μm is formed on the Cu-containing layer. The ratio of the thickness of the Cu-containing layer to the thickness (Cu / Sn thickness ratio) is 2 or less.
[0017]
In this electric or electronic member, the exposed surface is preferably a surface exposed by pressing, wire cutting or etching, and at least a part of the exposed surface is in electrical contact with another terminal, bus bar or electric wire. The end face or the end face that requires leak resistance is preferable.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
In the embodiment of the method for producing a copper or copper alloy member provided with a Sn coating according to the present invention, first, the reliability of electrical connection, leakage resistance, corrosion resistance, and soldering at the end face of a copper or copper alloy plate or strip are described. An end face of a terminal or a bus bar or the like which requires properties is exposed by pressing, wire cutting or etching. Next, the surface and the exposed end face are coated with a Ni-containing layer having a thickness of 0.1 to 5 μm by plating or vapor deposition, and then coated with a Cu-containing layer having a thickness of 0.2 to 3 μm. The surface is coated with a Sn-containing layer having a thickness of 0.2 to 10 μm by plating, vapor deposition, molten metal immersion, or the like. The thickness of the Sn-containing layer is such that the ratio of the thickness of the Cu-containing layer to the thickness of the Sn-containing layer (hereinafter referred to as “Cu / Sn thickness ratio”) is 2 or less. When the method of coating the Sn-containing layer is other than Sn immersion, heat melting treatment is performed thereafter to form a Sn-coated copper or copper alloy member. The thickness of the above-mentioned coating layer is determined by forming an end face which is formed on a terminal or a bus bar, etc., and which electrically contacts another terminal, a bus bar, an electric wire, or the like, or an end face which requires leak resistance, corrosion resistance and solderability. Although it is the thickness of the coating layer in the case where there is a portion connected to other electric components even on the surface other than the end surface, from the viewpoint of electrical reliability, heat resistance, corrosion resistance and solderability, the above-mentioned is described. It is preferable to coat with a thickness.
[0019]
The Ni-containing layer may contain 0 to 10% by weight of one or more of Co, Cu, P and S in addition to Ni. Further, the Cu-containing layer may contain 0 to 10% by weight of at least one of Zn, Ni and Sn. Further, the Sn-containing layer may contain 0 to 20% by weight of at least one of Pb, Zn, Ni, Cu and Ag.
[0020]
Next, the reason why the thickness of the Ni-containing layer is set to 0.1 to 5 μm will be described. The main purpose of coating with the Ni-containing layer is to prevent the components of copper and copper alloy, which are raw materials, from diffusing into the surface layer and to improve leak resistance. When the thickness of the Ni-containing layer is less than 0.1 μm, the effects of preventing diffusion and improving the leak resistance are small. On the other hand, when the thickness of the Ni-containing layer exceeds 5 μm, it becomes economically disadvantageous, When an additional bending process is performed on the covered plane portion, a crack may occur from the Ni-containing layer as a starting point. In order to achieve the above object, one or more of Co, Cu, P and S may be contained in addition to Ni in an amount of 0 to 10% by weight. Cracks are likely to occur even with the following thickness.
[0021]
Next, the reason why the thickness of the Cu-containing layer is set to 0.2 to 3 μm will be described. The main purpose of coating with the Cu-containing layer is to suppress alloying between Ni of the lower coating layer and Sn of the upper coating layer. When there is no Cu-containing layer, Ni and Sn are alloyed, and Ni diffuses to the outermost surface of the coating due to aging to form an oxide having a large electric resistivity, so that the electrical reliability is reduced. When the thickness of the Cu-containing layer is less than 0.2 μm, the effect of suppressing the Ni—Sn alloying is not sufficient. Further, Cu in the Cu-containing layer diffuses into the upper Sn to form a Cu—Sn alloy layer such as Cu ₆ Sn ₅ or Cu ₃ Sn. If there is an excessive amount of Cu, the remaining Cu diffuses into the surface layer to form an oxide having an electrical resistivity higher than that of the Sn oxide, and thus the electrical reliability is reduced. Therefore, the upper limit of the thickness of the Cu-containing layer is set to 3 μm, and the Cu / Sn thickness ratio is set to 2 or less.
[0022]
Next, the reason why the thickness of the Sn-containing layer is set to 0.2 to 10 μm will be described. The Sn-containing layer is originally provided to ensure electrical connection reliability, corrosion resistance, solderability, and the like. If the thickness of the Sn-containing layer is less than 0.2 μm, its function may be maintained. On the other hand, if it exceeds 10 μm, it is economically disadvantageous.
[0023]
The reason why the method of coating the Sn-containing layer is a method of performing a heat melting treatment after electroplating or a method of applying a molten Sn immersion treatment is to improve whisker resistance. However, when whisker resistance is not required, the heat melting treatment or the molten Sn immersion treatment may not be performed.
[0024]
FIGS. 1 and 2 show examples in which a copper or copper alloy member coated with Sn according to the present invention is applied to a tuning fork type terminal. As shown in FIGS. 1 and 2, the tongue-shaped terminal 12 is inserted between the opposed end surfaces of the tuning-fork type terminal 10 and fitted to each other, so that the electrical connection between them is made. As shown in FIGS. 3 (a) and 3 (b), the end of the tuning fork type terminal 10 fitted with the tongue-shaped terminal 12 has a coating structure of the end of the copper or copper alloy member 14 as a raw material. The surface is covered with a Ni layer, the upper surface is covered with a Cu-Sn layer (or Cu layer + Cu-Sn layer) 18, and the upper surface is covered with a Sn layer 20. Here, FIG. 3A shows a state in which a portion of the inside of the tuning fork type terminal 10 (including a portion to be electrically connected to the tongue type terminal 12) is formed by pressing a copper or copper alloy material by pressing or the like. FIG. 7 shows an example in which the above-mentioned coating is applied, and then the outer portion of the tuning fork type terminal 10 is formed by pressing or the like, and the portion on the opposite side of the portion to be electrically connected to the tongue type terminal 12 is removed. FIG. 3B shows an example in which the above-mentioned coating is applied after forming a material of copper or copper alloy into the shape of the tuning fork type terminal 10 by pressing or the like. Note that the above-mentioned coating may not be applied to a portion that does not need to be applied, and the above-described coating may be applied only to a portion to be electrically connected to the tongue-shaped terminal 12.
[0025]
【Example】
Hereinafter, embodiments of a copper or copper alloy member coated with Sn and a method of manufacturing the same according to the present invention will be described in detail.
[0026]
[Example 1]
First, a test piece made of C1020 (oxygen-free copper) having a Vickers hardness of HV105, a thickness of 0.8 mm, a width of 10 mm, and a length of 60 mm was punched out using a press die. After activating the surface and the end face of this test piece by electrolytic degreasing and pickling, a portion from one end of the test piece to 30 mm was formed by a 0.5 μm thick Ni layer, a 0.5 μm thick Cu layer and a 0.5 μm thick Cu layer. It was sequentially covered with a 2 μm Sn layer and subjected to a heat melting treatment. The coating of these layers was performed by electroplating, which was excellent in thickness control and advantageous in cost. Ni plating was performed using a nickel sulfamate bath, Cu plating was performed using a copper sulfate bath, and Sn plating was performed using a tin sulfate bath. Bright plating was performed without adding a brightener to each plating bath. Further, the position of the anode plate was adjusted so that the plating thickness on the surface and the end face was equal. The heat melting treatment was performed by heating the plated portion of the test piece between the opposed burners, and immediately after the gloss spread over the entire surface, dropped into a water tank installed under the burner and cooled with water.
[0027]
The thickness of the Ni coating layer was measured using a fluorescent X-ray film thickness measuring instrument with a collimator having a diameter of 0.1 mm, with a test piece plated with Ni only under the same plating conditions as described above, with the end face horizontal. . The thickness of the Sn coating layer was measured in the same manner. The thickness of the Cu coating layer was measured by embedding a Ni-plated Cu-plated test piece in a resin, polishing the resin, and observing the cross section at a magnification of 10,000 with a scanning electron microscope (SEM).
[0028]
Next, the test piece obtained in this example was evaluated for heat resistance by a contact resistance value after holding at 160 ° C. for 120 hours in an air atmosphere. The contact resistance value was measured using a micro-ohm meter under the conditions of an open-circuit voltage of 20 mV, a current of 10 mA, a U-shaped metal wire probe of 0.5 mm, a maximum load of 100 gf, and no sliding. The average was determined. At the time of this measurement, the test piece was fixed with a jig such that the probe was in vertical contact with the end face of the test piece. The contact resistance measured before the evaluation of the heat resistance of the test piece obtained in this example was 5 mΩ.
[0029]
Further, as shown in FIG. 3, a pair of the same test pieces 100 obtained in this example were fixed to a resin plate 102 so as to face each other at a distance of 1 mm. A portion of the test piece 100 having a tip of 10 mm was immersed in a 0.5 L test aqueous solution 104 adjusted to 85 μS / cm by adding sodium sulfite to pure water, and a DC voltage of 14 V was applied to both electrodes by a DC power supply 106. Was measured by the ammeter 108. This measurement was performed until the leak current exceeded 1 A, and the leak resistance of the test piece 100 was evaluated based on the time required. If the leak current did not exceed 1 A even after 120 minutes, the measurement was terminated.
[0030]
Further, the test piece obtained in this example was subjected to a 90 ° W bending test (inner bending radius: 0.8 mm), and then the surface of the bent portion was observed, and the bending workability was evaluated based on the presence or absence of cracks.
[0031]
As a result of these tests, the contact resistance after holding at 160 ° C. for 120 hours in the air atmosphere was 5 mΩ, and the leakage current did not exceed 1 A even after 120 minutes in the leak resistance evaluation. No crack was observed in the evaluation of. Therefore, it was found that the test pieces obtained in this example were excellent in heat resistance, leak resistance, and bending workability.
[0032]
[Example 2]
A test piece was prepared in the same manner as in Example 1 except that the thickness of the Ni layer was 0.1 μm, the thickness of the Cu layer was 0.2 μm, and the thickness of the Sn layer was 0.5 μm. The same test was performed. The contact resistance measured before the evaluation of the heat resistance of the test piece obtained in this example was 5 mΩ.
[0033]
In this example, the contact resistance after holding at 160 ° C. for 120 hours in the air atmosphere was 82 mΩ, and the leak current did not exceed 1 A even after 120 minutes had passed in the evaluation of leak resistance. No crack was observed in the evaluation. Therefore, it was found that the test pieces obtained in this example were excellent in heat resistance, leak resistance, and bending workability.
[0034]
[Example 3]
A test piece was prepared in the same manner as in Example 1 except that the thickness of the Ni layer was 2 μm, the thickness of the Cu layer was 1 μm, and the thickness of the Sn layer was 1.5 μm. Was done. The contact resistance measured before the evaluation of the heat resistance of the test piece obtained in this example was 5 mΩ.
[0035]
In this example, the contact resistance after holding at 160 ° C. for 120 hours in the air atmosphere was 17 mΩ, and the leak current did not exceed 1 A even after 120 minutes had passed in the leak resistance evaluation. No crack was observed in the evaluation. Therefore, it was found that the test pieces obtained in this example were excellent in heat resistance, leak resistance, and bending workability.
[0036]
[Comparative Example 1]
A test piece (bare material) similar to that of Example 1 was prepared except that the coating was not performed, and the same test as that of Example 1 was performed. In addition, the contact resistance value measured before the heat resistance evaluation of the test piece of this comparative example was 18 mΩ.
[0037]
In this comparative example, the contact resistance after holding at 160 ° C. for 120 hours in the air atmosphere exceeded 2000 mΩ, and the contact reliability was lacking. In addition, in the evaluation of leak resistance, it exceeded 1 A in 18 minutes, and was inferior in leak resistance. The reason why the contact resistance value exceeded 2000 mΩ was that Cu of the material was oxidized, and the reason for the poor leak resistance was that Cu eluted from the anode side was easily deposited on the cathode and a bridge was formed between the anode and the cathode. Is formed.
[0038]
[Comparative Example 2]
A test piece similar to that of Example 1 was prepared except that the test piece was covered with only the Sn layer having a thickness of 1 μm, and a test similar to that of Example 1 was performed. The contact resistance measured before the evaluation of the heat resistance of the test piece of this comparative example was 5 mΩ.
[0039]
In this comparative example, the contact resistance after holding at 160 ° C. for 120 hours in the air atmosphere was 277 mΩ, and the contact reliability was lacking. In addition, in the evaluation of leak resistance, it exceeded 1 A in 100 minutes, and was inferior in leak resistance. The reason why the contact resistance value exceeds 100 mΩ is that Cu of the material diffused into the outermost layer to form Cu oxide.
[0040]
[Comparative Example 3]
A test piece similar to that of Example 1 was prepared except that the thickness of the Ni layer was 1 μm and the thickness of the Sn layer was 1 μm, and the Cu coating was not applied, and the same test as in Example 1 was performed. The contact resistance measured before the evaluation of the heat resistance of the test piece of this comparative example was 5 mΩ.
[0041]
In this comparative example, the contact resistance after holding at 160 ° C. for 120 hours in the air atmosphere was 205 mΩ, and the contact reliability was lacking. The reason why the contact resistance value exceeds 100 mΩ is that Ni in the underlying coating layer diffused into the outermost layer to form Ni oxide.
[0042]
[Comparative Example 4]
A test piece was prepared in the same manner as in Example 1 except that the thickness of the Ni layer was 6 μm, the thickness of the Cu layer was 0.5 μm, and the thickness of the Sn layer was 1 μm. Was done. The contact resistance measured before the evaluation of the heat resistance of the test piece obtained in this comparative example was 5 mΩ.
[0043]
In this comparative example, the contact resistance after holding at 160 ° C. for 120 hours in the air atmosphere was 24 mΩ, and the leak current did not exceed 1 A even after 120 minutes in the leak resistance evaluation. Therefore, the test piece obtained in this comparative example was excellent in heat resistance and leak resistance. However, since the Ni layer was too thick, cracks were observed in the evaluation of bending workability.
[0044]
[Comparative Example 5]
A test piece was prepared in the same manner as in Example 1 except that the thickness of the Ni layer was 0.5 μm, the thickness of the Cu layer was 0.1 μm, and the thickness of the Sn layer was 0.1 μm. The same test was performed. In addition, the contact resistance measured before the heat resistance evaluation of the test piece obtained in this comparative example was 15 mΩ.
[0045]
In this comparative example, the contact resistance after holding at 160 ° C. for 120 hours in the air atmosphere exceeded 2000 mΩ, and the contact reliability was lacking. The reason why the contact resistance value exceeded 100 mΩ was that the Sn coating layer was thin and the components (Ni, Cu) of the underlying coating layer formed an oxide on the outermost layer.
[0046]
[Comparative Example 6]
A test piece was prepared in the same manner as in Example 1 except that the thickness of the Ni layer was 1 μm, the thickness of the Cu layer was 2 μm, and the thickness of the Sn layer was 0.5 μm, and the same test as in Example 1 was performed. Was done. The contact resistance measured before the evaluation of the heat resistance of the test piece obtained in this comparative example was 5 mΩ.
[0047]
In this comparative example, the contact resistance after holding at 160 ° C. for 120 hours in the air atmosphere was 311 mΩ, and the contact reliability was lacking. The reason why the contact resistance value exceeds 100 mΩ is that the Cu / Sn thickness ratio is large and the excessively remaining components of the Cu coating layer diffused into the outermost layer to form Cu oxide.
[0048]
Table 1 shows the results of Examples 1 to 3 and Comparative Examples 1 to 6.
[0049]
[Table 1]

[0050]
【The invention's effect】
As described above, the copper or copper alloy member coated with Sn according to the present invention is particularly excellent in heat resistance and leak resistance of the end face exposed by molding, so that the end face of the member is used for terminals, bus bars, electric wires, and the like. It is excellent as a material for electrical and electronic parts such as connector terminals and bus bars including parts to be electrically connected, and bus bars and lead frames requiring leak resistance. In addition, since the corrosion resistance and solderability of the end face of the member can be improved, the present invention can be applied to a field where the corrosion resistance and solderability of the end face of a terminal such as a PCB terminal are required.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a tuning fork type terminal using a copper or copper alloy member coated with Sn according to the present invention and a tongue type terminal inserted into the tuning fork type terminal.
FIG. 2 is a plan view of the tuning fork type terminal of FIG. 1;
FIG. 3 is a sectional view taken along line III-III of FIG. 1, showing an example of a coating structure of the tuning fork type terminal of FIG. 1;
FIG. 4 is a view for explaining a leak resistance test in Examples and Comparative Examples.
[Explanation of symbols]
Reference Signs List 10 tuning fork type terminal 12 tongue type terminal 14 copper or copper alloy member 16 Ni layer 18 Cu-Sn layer (or Cu layer + Cu-Sn layer)
Reference Signs List 20 Sn layer 100 Test piece 102 Resin plate 104 Test aqueous solution 106 DC power supply (14 V)
108 ammeter

Claims

A Ni-containing layer having a thickness of 0.1 to 5 μm is formed on at least a part of the exposed surface by molding a copper or copper alloy material into a desired shape. A Cu-containing layer having a thickness of 2 to 3 μm is formed, a Sn-containing layer having a thickness of 0.2 to 10 μm is formed on the Cu-containing layer, and the ratio of the thickness of the Cu-containing layer to the thickness of the Sn-containing layer (Cu / Sn thickness ratio) is 2 or less, the copper or copper alloy member coated with Sn.

The copper or copper alloy member coated with Sn according to claim 1, wherein the exposed surface is a surface exposed by pressing, wire cutting, or etching.

The Sn or copper-coated copper or copper alloy member according to claim 1, wherein at least a part of the exposed surface is an end surface that is in electrical contact with another member.

The copper or copper alloy member coated with Sn according to any one of claims 1 to 3, wherein at least a part of the exposed surface is an end surface requiring leak resistance.

The copper or copper alloy member provided with Sn coating according to any one of claims 1 to 4, wherein a part or the whole of the Cu-containing layer includes a Cu-Sn alloy layer.

The Cu-Sn alloy layer is characterized by comprising the _Cu 6 Sn ₅ or _Cu 3 Sn, copper or copper alloy member subjected to the Sn coating of claim 5.

The Ni-containing layer is a layer made of Ni, the Cu-containing layer is a layer made of Cu, and the Sn-containing layer is a layer made of Sn. A copper or copper alloy member coated with the Sn coating as described above.

The Ni-containing layer contains 0 to 10% by weight of one or more of Co, Cu, P and S in addition to Ni, and the Cu-containing layer contains one or more of Zn, Ni and Sn in addition to Cu. 7% by weight, and the Sn-containing layer contains 0 to 20% by weight of at least one of Pb, Zn, Ni, Cu and Ag in addition to Sn. 4. A copper or copper alloy member provided with a Sn coating according to 4.

A material of copper or a copper alloy is formed into a desired shape, and a Ni-containing layer having a thickness of 0.1 to 5 μm is formed on at least a part of the exposed surface by this forming. A Cu-containing layer having a thickness of 0.2 to 3 μm is formed, a Sn-containing layer having a thickness of 0.2 to 10 μm is formed on the Cu-containing layer, and the ratio of the thickness of the Cu-containing layer to the thickness of the Sn-containing layer ( Cu / Sn thickness ratio (Cu / Sn thickness ratio) 2 or less.

The method for producing a copper or copper alloy member coated with Sn according to claim 9, wherein the forming of the copper or copper alloy material is performed by pressing, wire cutting, or etching.

The method according to claim 9 or 10, wherein at least a part of the exposed surface is an end surface that is in electrical contact with another member.

The method for manufacturing a copper or copper alloy member coated with Sn according to any one of claims 9 to 11, wherein at least a part of the exposed surface is an end surface requiring leak resistance.

After forming the Ni-containing layer, the Cu-containing layer, and the Sn-containing layer, secondary processing is performed, and the Sn-coated copper or copper alloy according to any one of claims 9 to 12, A method for manufacturing a member.

The method for producing a copper or copper alloy member with a Sn coating according to claim 13, wherein the secondary processing is a press.

The method for producing a copper or copper alloy member with a Sn coating according to any one of claims 9 to 14, wherein the Ni-containing layer, the Cu-containing layer, and the Sn-containing layer are formed by electroplating. .

The method for producing a copper or copper alloy member coated with Sn according to claim 15, wherein a heat melting treatment or a molten Sn immersion treatment is performed after the Sn-containing layer is electroplated.

A Ni-containing layer having a thickness of 0.1 to 5 μm is formed on at least a part of the exposed surface by molding a copper or copper alloy material into a desired shape. A Cu-containing layer having a thickness of 2 to 3 μm is formed, a Sn-containing layer having a thickness of 0.2 to 10 μm is formed on the Cu-containing layer, and the ratio of the thickness of the Cu-containing layer to the thickness of the Sn-containing layer (Cu / Sn thickness ratio) is 2 or less.

The electric or electronic member according to claim 17, wherein the exposed surface is a surface exposed by pressing, wire cutting, or etching.

The electric or electronic member according to claim 17, wherein at least a part of the exposed surface is an end surface that is in electrical contact with another terminal, a bus bar, or an electric wire.

20. The electric or electronic member according to claim 17, wherein at least a part of the exposed surface is an end surface requiring leak resistance.