JP2012162791A - Plated material for terminal or connector and manufacturing method therefor - Google Patents
Plated material for terminal or connector and manufacturing method therefor Download PDFInfo
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本発明は、ステンレス鋼薄板の表面にＡｕめっきして形成する端子又はコネクタ用めっき材の製造方法、及び端子又はコネクタ用めっき材に関する。 The present invention relates to a method for producing a terminal or connector plating material formed by Au plating on the surface of a stainless steel thin plate, and a terminal or connector plating material.
端子、コネクタ用材料としてステンレス鋼にニッケル下地めっきを施した後、Ａｕめっきを施しためっき材料が使用されている。ところが、近年ニッケルアレルギーが問題になっていることから、人体に触れる可能性にある部品にはニッケルめっきを行うことができなくなっている。
そして、コネクト用途として、ステンレス鋼ストリップの表面に、電子ビーム蒸着（ＥＢ）によってＡｕ層を形成する技術（特許文献１）が開発されている。
又、燃料電池用セパレータ用途として、ステンレス鋼板の表面に、下地処理を施さずに酸性浴にてダイレクトに金めっきを施す技術（特許文献２）や、ステンレス鋼板の表面に酸化被膜を形成後に金めっきを施す技術（特許文献３）が報告されている。
一方、めっき浴に超音波振動を付与することで、高電流密度による高速めっきを行う技術（特許文献４）が報告されている。
As a material for terminals and connectors, a plating material obtained by performing nickel undercoating on stainless steel and then performing Au plating is used. However, since nickel allergy has become a problem in recent years, it is no longer possible to perform nickel plating on parts that may touch the human body.
As a connection application, a technique (Patent Document 1) for forming an Au layer on the surface of a stainless steel strip by electron beam evaporation (EB) has been developed.
In addition, as a separator for a fuel cell, a technique (PTL 2) in which a surface of a stainless steel plate is directly subjected to gold plating in an acid bath without applying a base treatment, or a gold plate after an oxide film is formed on the surface of a stainless steel plate. A technique for applying plating (Patent Document 3) has been reported.
On the other hand, a technique (Patent Document 4) that performs high-speed plating with a high current density by applying ultrasonic vibration to a plating bath has been reported.
しかしながら、金は高価であることから、金の使用量（金膜の厚さ）を低減していく必要があり、ステンレス鋼薄板に直接薄い（ストライク，20nm以下）金めっきを行う必要がある。ところが、金めっきの厚みが２０ｎｍ未満に薄くなると、被膜欠陥が生じ易くなり、耐食性を十分に確保できないという問題がある。一方、特許文献１記載の技術のように、蒸着等によってＡｕ層を成膜すると、生産コストが高くなるという問題がある。
すなわち、本発明は、ステンレス鋼薄板表面に形成するＡｕめっき層の厚みが薄くても耐食性に優れ、生産性も高い端子又はコネクタ用めっき材及びその製造方法の提供を目的とする。
However, since gold is expensive, it is necessary to reduce the amount of gold used (gold film thickness), and it is necessary to perform thin (strike, 20 nm or less) gold plating directly on a stainless steel sheet. However, when the thickness of the gold plating is reduced to less than 20 nm, film defects are likely to occur, and there is a problem that sufficient corrosion resistance cannot be ensured. On the other hand, when the Au layer is formed by vapor deposition or the like as in the technique described in Patent Document 1, there is a problem that the production cost increases.
That is, an object of the present invention is to provide a terminal or connector plating material having excellent corrosion resistance and high productivity even when the thickness of the Au plating layer formed on the surface of the stainless steel thin plate is thin, and a method for manufacturing the same.
本発明の端子又はコネクタ用めっき材は、ステンレス鋼薄板からなる基材の表面に、原子間力顕微鏡により測定した算術表面粗さ（Ra）が３．０ｎｍ以下であるＡｕめっき層を形成してなる。 The plating material for terminals or connectors of the present invention is obtained by forming an Au plating layer having an arithmetic surface roughness (Ra) measured by an atomic force microscope of 3.0 nm or less on the surface of a substrate made of a stainless steel thin plate. Become.
本発明の端子又はコネクタ用めっき材の製造方法は、前記端子又はコネクタ用めっき材の製造方法であって、ｐＨ１．０以下のＡｕめっき浴を用い、前記基材及び／又は前記Ａｕめっき浴に超音波振動を付与した状態で電解めっきして厚み２０ｎｍ以下のＡｕめっき層を形成する。 The method for producing a terminal or connector plating material according to the present invention is a method for producing the terminal or connector plating material, wherein an Au plating bath having a pH of 1.0 or less is used, and the substrate and / or the Au plating bath is used. An Au plating layer having a thickness of 20 nm or less is formed by electroplating in a state where ultrasonic vibration is applied.
前記超音波振動の発振周波数を２５〜６０ｋＨｚとすることが好ましい。
前記Ａｕめっき層をさらに封孔処理することが好ましい。
メルカプト系水溶液中で前記Ａｕめっき層を電解処理して前記封孔処理を行うことが好ましい。
The oscillation frequency of the ultrasonic vibration is preferably set to 25 to 60 kHz.
The Au plating layer is preferably further sealed.
It is preferable to perform the sealing treatment by electrolytically treating the Au plating layer in a mercapto-based aqueous solution.
本発明によれば、ステンレス鋼薄板表面に形成するＡｕめっき層の厚みが薄くても耐食性に優れ、生産性も高い端子又はコネクタ用めっき材が得られる。 ADVANTAGE OF THE INVENTION According to this invention, even if the thickness of the Au plating layer formed in the stainless steel thin plate surface is thin, the plating material for terminals or connectors which is excellent in corrosion resistance and high in productivity can be obtained.
以下、本発明の実施形態に係る端子又はコネクタ用めっき材について説明する。なお、本発明において％とは、特に断らない限り、質量％を示すものとする。 Hereinafter, the terminal or connector plating material according to the embodiment of the present invention will be described. In the present invention, “%” means “% by mass” unless otherwise specified.
＜基材＞
端子又はコネクタ用めっき材は耐食性と導電性が要求され、その基材には耐食性が求められる。このため基材には耐食性が良好で比較的低コストなステンレス鋼薄板を用い、好ましくはオーステナイト系ステンレス鋼薄板を用いる。
オーステナイト系ステンレス鋼薄板の種類は特に制限されないが、例えば、ＪＩＳに規格するＳＵＳ２０１、ＳＵＳ３０４、ＳＵＳ３０４Ｌ、ＳＵＳ３０４ＬＮ、ＳＵＳ３１６、ＳＵＳ３１６Ｌ、ＳＵＳＸＭ７を挙げることができる。ここで、耐食性に優れる点で、ＳＵＳ３１６Ｌ（Ｍｏを２．５％程度添加したステンレス鋼）が好ましい。
基材の形状も特に制限されず、Ａｕをめっきできる形状であればよいが、端子やコネクタ等の部品形状にプレス成形することから、薄板の厚みが０．０５〜０．３ｍｍであることが好ましい。
<Base material>
The plating material for terminals or connectors is required to have corrosion resistance and conductivity, and the base material is required to have corrosion resistance. For this reason, a stainless steel sheet having good corrosion resistance and relatively low cost is used for the base material, and preferably an austenitic stainless steel sheet is used.
The type of the austenitic stainless steel sheet is not particularly limited, and examples thereof include SUS201, SUS304, SUS304L, SUS304LN, SUS316, SUS316L, and SUSXM7, which are compliant with JIS. Here, SUS316L (stainless steel to which Mo is added by about 2.5%) is preferable in terms of excellent corrosion resistance.
The shape of the substrate is not particularly limited as long as it is a shape that can be plated with Au, but the thickness of the thin plate may be 0.05 to 0.3 mm because it is press-formed into a component shape such as a terminal or a connector. preferable.
又、Ａｕめっき層を平滑に成膜する観点から、基材表面も平滑化した方がよい。ステンレス鋼薄板の表面仕上げ法としては、従来からＢＡ（光輝焼鈍）、研磨仕上げ等が知られているが、２０ｎｍ以下の薄いＡｕめっき層を形成する本発明においては、ＢＡ処理したステンレス鋼薄板が好ましい。
さらに、基材の表面粗さがRa≦0.08μmであると、Ａｕめっき層を平滑に成膜する観点から好ましい。電解めっきは基材表面の凹凸の凸部に付きやすいため、基材の表面粗さRaを0.08μm以下とすることで均一にめっきが付き、ピンホールなどの欠陥が少なくすることができる。
Further, from the viewpoint of forming the Au plating layer smoothly, it is better to smooth the surface of the base material. As surface finishing methods for stainless steel thin plates, BA (bright annealing), polishing finish, etc. are conventionally known. In the present invention for forming a thin Au plating layer of 20 nm or less, a stainless steel thin plate treated with BA is used. preferable.
Furthermore, when the surface roughness of the substrate is Ra ≦ 0.08 μm, it is preferable from the viewpoint of forming the Au plating layer smoothly. Since electrolytic plating tends to attach to the uneven surface of the base material surface, the surface roughness Ra of the base material is set to 0.08 μm or less so that plating is uniformly applied and defects such as pinholes can be reduced.
＜Ａｕめっき層＞
Ａｕめっき層は、基材表面にＡｕを電解めっきして形成され、原子間力顕微鏡により測定した算術表面粗さ（Ra）が３．０ｎｍ以下である。
本発明者らの検討により、薄い（厚み２０ｎｍ以下の）Ａｕめっき層においては、表面のＲａが大きくなるほど、基材からの金属溶出量も多くなることが判明した。この原因は明確ではないが、Ａｕめっき層のＲａが大きいものは、電気めっき時に基材の特定の位置に集中して電析し、その分だけめっき層の厚みが薄い部分が生じ、被膜欠陥に至ることが考えられる。
２０ｎｍ以下の薄く柔らかい、Ａｕめっき層の平滑性を評価する際、接触式表面粗さ計で測定するとナノレベルの凹凸の評価は困難となり、ステンレス鋼等の基材の粗さを測定することとなってしまう。そのため、本発明において、薄いＡｕ層の平滑性の評価に非接触の原子間力顕微鏡（ＡＦＭ）を用いる。
ＡＦＭにより測定したＡｕめっき層のＲａが３．０ｎｍ以下になると、大幅に金属溶出量が少なくなる。Ａｕめっき層のＲａは小さいほど好ましいが、Ｒａが０．５ｎｍ未満のめっき層を形成するのは実用上難しい。
<Au plating layer>
The Au plating layer is formed by electroplating Au on the substrate surface, and has an arithmetic surface roughness (Ra) measured by an atomic force microscope of 3.0 nm or less.
As a result of studies by the present inventors, it has been found that in a thin Au plating layer (thickness of 20 nm or less), the amount of metal elution from the base material increases as the surface Ra increases. The cause of this is not clear, but when the Ra of the Au plating layer is large, electrodeposition is concentrated at a specific position on the base material during electroplating, resulting in a thin portion of the plating layer, and film defects. It can be thought of that.
When evaluating the smoothness of a thin and soft Au plating layer of 20 nm or less, it is difficult to evaluate nano-level irregularities when measured with a contact-type surface roughness meter, and measuring the roughness of a substrate such as stainless steel turn into. Therefore, in the present invention, a non-contact atomic force microscope (AFM) is used for evaluating the smoothness of a thin Au layer.
When the Ra of the Au plating layer measured by AFM is 3.0 nm or less, the metal elution amount is greatly reduced. The smaller the Ra of the Au plating layer, the better. However, it is practically difficult to form a plating layer with an Ra of less than 0.5 nm.
なお、基材表面へのＡｕの電着状態は、基材の結晶粒内と結晶粒界とで異なる。具体的には、基材の粒界部分では電着が凹状となるので、基材の粒界を含む部分のＲａを原子間力顕微鏡（ＡＦＭ）で測定すると、Ｒａの測定値は大きくなる。そのため，本発明においては，基材の結晶粒内で測定したＲａをＡｕめっき層のＲａとして採用する。
又、省金化の観点から、めっき材料を端子やコネクタ等の電気、電子部品に加工した際に電気が流れる（導電性が必要となる）面にのみにＡｕめっきを施したり、他の面のＡｕめっき厚を薄くすることも可能である。さらに、端子やコネクタ等の電気、電子部品において、接点など導電性を要する部分（アクティブエリア）のみにＡｕめっきしてもよい。
In addition, the electrodeposition state of Au on the substrate surface is different between the crystal grains of the substrate and the crystal grain boundaries. Specifically, since electrodeposition is concave at the grain boundary portion of the substrate, the measured value of Ra increases when the Ra of the portion including the grain boundary of the substrate is measured with an atomic force microscope (AFM). Therefore, in this invention, Ra measured in the crystal grain of a base material is employ | adopted as Ra of Au plating layer.
Also, from the viewpoint of saving money, Au plating is applied only to the surface where electricity flows (conductivity is required) when the plating material is processed into electricity and electronic parts such as terminals and connectors, or other surfaces. It is also possible to reduce the thickness of the Au plating. Further, in electrical and electronic parts such as terminals and connectors, Au plating may be applied only to portions (active areas) that require electrical conductivity such as contacts.
図１は、後述する発明例１−３の燃料電池用セパレータ材料の断面のＴＥＭ像を示す。又、図２は、同様にして発明例１−５の燃料電池用セパレータ材料の断面のＴＥＭ像を示す。 FIG. 1 shows a TEM image of a cross section of a fuel cell separator material of Invention Example 1-3 described later. FIG. 2 shows a TEM image of a cross section of the fuel cell separator material of Invention Example 1-5 in the same manner.
Ａｕめっき層のＲａを３．０ｎｍ以下にする方法としては、Ａｕめっき浴に硫酸水素ナトリウムを伝導塩として添加することが挙げられる。この場合、Ａｕめっき浴の組成としては、Ａｕ塩、硫酸水素ナトリウム、及び必要に応じてその他の添加剤を含むものを用いることができる。又、硫酸水素ナトリウムの濃度は、５０〜１００ｇ／Ｌ程度とすることができる。 As a method for setting the Ra of the Au plating layer to 3.0 nm or less, sodium hydrogen sulfate is added as a conductive salt to the Au plating bath. In this case, as the composition of the Au plating bath, one containing Au salt, sodium hydrogen sulfate, and other additives as required can be used. Moreover, the density | concentration of sodium hydrogensulfate can be about 50-100 g / L.
＜Ａｕめっき層の厚み＞
基材表面（片面または両面）に形成するＡｕめっき層の厚さは，コストの点から２０ｎｍ以下とするが、耐食性と電気特性（セパレータとMEAの接触抵抗）の観点から２ｎｍ以上とするとよい。好ましくはＡｕめっき層の厚みを５〜２０ｎｍとし、より好ましくはＡｕめっき層の厚みを５〜１０ｎｍにすると、耐食性が良好でかつコストを低減することができる。Ａｕめっき層の厚みは、電解法や断面のＴＥＭ（透過型電子顕微鏡）像で算出することができる。
<Au plating layer thickness>
The thickness of the Au plating layer formed on the substrate surface (one side or both sides) is 20 nm or less from the viewpoint of cost, but is preferably 2 nm or more from the viewpoint of corrosion resistance and electrical characteristics (contact resistance between separator and MEA). Preferably, the thickness of the Au plating layer is 5 to 20 nm, and more preferably, the thickness of the Au plating layer is 5 to 10 nm, the corrosion resistance is good and the cost can be reduced. The thickness of the Au plating layer can be calculated by an electrolysis method or a cross-sectional TEM (transmission electron microscope) image.
＜Ａｕめっき方法＞
基材表面にＡｕめっき層を電解めっきするため、ｐＨ１．０以下のＡｕめっき浴を用いる。ステンレス鋼薄板に直接Ａｕをめっきするためには、めっき浴のｐＨが１以下である必要があり、ｐＨ１．０以下のＡｕめっき浴を用いると、基材であるステンレス鋼表面のＣｒ酸化皮膜が除去されやすく、Ａｕめっき層の密着性が向上する。
また、酸性Ａｕめっき浴を用い、基材表面に直接（ダイレクトに）Ａｕめっきすることで、めっき密着性が向上する。これは、従来からコネクタ材では基材にＮｉ下地めっきを行った後、Ａｕめっきを施しているが、Ｎｉの耐酸性が弱いため、腐食性の雰囲気に曝されるとＮｉめっきが剥がれてしまうからである。さらに、ｐＨ１．０以下の酸性Ａｕめっき浴は高電流密度でめっきが可能であるため、めっきの際に基材表面に水素が発生してステンレス表面が活性化され、Ａｕが付きやすくなる。
一方、Ａｕめっき浴のｐＨが１．０を超えると基材へのめっき密着性が低下する。なお、Ａｕめっき浴のｐＨが０．２未満になると、電解めっきの際に水素が過多に発生してめっき電流効率が低下するため、ｐＨは０．２以上が好ましい。
ｐＨ１．０以下のＡｕめっき浴としては硫酸水素ナトリウとシアン化金カリウムを主成分とする浴などが挙げられる。又、Ａｕ塩としては、シアン化金塩、等を用いることができ、Ａｕ塩の金濃度は２〜７ｇ／Ｌ程度とすることができる。
<Au plating method>
In order to electroplat the Au plating layer on the substrate surface, an Au plating bath having a pH of 1.0 or less is used. In order to directly plate Au on a stainless steel thin plate, the pH of the plating bath needs to be 1 or less. When an Au plating bath having a pH of 1.0 or less is used, the Cr oxide film on the surface of the stainless steel as a substrate is formed. It is easily removed and the adhesion of the Au plating layer is improved.
In addition, plating adhesion is improved by directly (directly) Au plating on the surface of the substrate using an acidic Au plating bath. Conventionally, in connector materials, Ni base plating is applied to a base material and then Au plating is applied to the base material. However, since the acid resistance of Ni is weak, the Ni plating peels off when exposed to a corrosive atmosphere. Because. Furthermore, since an acidic Au plating bath having a pH of 1.0 or less can be plated at a high current density, hydrogen is generated on the surface of the base material during the plating, the stainless steel surface is activated, and Au is easily attached.
On the other hand, when the pH of the Au plating bath exceeds 1.0, the plating adhesion to the substrate is lowered. If the pH of the Au plating bath is less than 0.2, excessive hydrogen is generated during electroplating and the plating current efficiency is lowered. Therefore, the pH is preferably 0.2 or more.
Examples of the Au plating bath having a pH of 1.0 or less include a bath mainly composed of sodium hydrogen sulfate and potassium gold cyanide. As the Au salt, a gold cyanide salt or the like can be used, and the gold concentration of the Au salt can be about 2 to 7 g / L.
Ａｕめっきの条件としては、電流密度が低いと基材の凸部に電流が集中してめっき層が平坦になり難く、又、めっき浴温が低いとめっき層が平坦になり難い傾向にある。
又、めっき液中の金濃度は１〜４ｇ／Ｌが好ましく、より好ましくは１〜２ｇ／Ｌである。金濃度が１ｇ／Ｌ未満であると、電流効率が低下してめっき層が平坦になり難い傾向にある。Ａｕめっきの電流密度は１〜８Ａ／ｄｍ２、好ましくは電流密度４〜８Ａ／ｄｍ２とするとよい。
Ａｕめっき浴の金濃度や電流密度を上記範囲に管理することでＡｕめっき層のＲａを３．０ｎｍ以下に小さくすることができ，Ａｕめっき層の厚さが薄い場合にもピンホールを少なくすることができる。
又、Ａｕめっきの厚みは、端子又はコネクタの耐食性と接触抵抗の製品規格を満たす最小限であればよい。
As conditions for Au plating, when the current density is low, current concentrates on the convex portion of the substrate and the plating layer is difficult to flatten, and when the plating bath temperature is low, the plating layer tends to be difficult to flatten.
The gold concentration in the plating solution is preferably 1 to 4 g / L, more preferably 1 to 2 g / L. If the gold concentration is less than 1 g / L, the current efficiency tends to decrease and the plating layer tends not to be flat. The current density of Au plating is 1 to 8 A / dm 2 , preferably 4 to 8 A / dm 2 .
By managing the gold concentration and current density of the Au plating bath within the above ranges, the Ra of the Au plating layer can be reduced to 3.0 nm or less, and pin holes are reduced even when the Au plating layer is thin. be able to.
The thickness of the Au plating may be a minimum that satisfies the product standards of the corrosion resistance and contact resistance of the terminal or connector.
＜超音波振動の付与＞
また２０ｎｍを超えるＡｕめっき厚みでは問題とならないが、Ａｕめっきを厚み２０ｎｍ以下とすると、上記したＡｕめっきのｐＨや浴組成の調整だけでは十分ではなく、めっき被膜のピンホールが増えて耐食性が低下する。このため、厚さ２０ｎｍ以下のＡｕめっきでは、超音波の照射が有効である。この理由は、Ａｕめっきの際に超音波を用いることで、Ａｕめっき浴が均一に攪拌され、浴中の金イオンが基材表面に均一に供給されるので，ピンホールを低減することができるからである。又、超音波によりＡｕめっき浴中にキャビテーションを起こさせ，基材表面に滞留する水素や不純物を浮き上がらせ，これらを起点としためっき欠陥（ピンホールなど）を低減することができる。
なお、超音波振動は、基材及び／又はＡｕめっき浴に付与すればよく、例えば超音波振動子をめっき浴中の基材に接触させたり、Ａｕめっき浴に超音波振動子を接触させることで、超音波振動を付与することができる。又、超音波振動の発振周波数によりＡｕめっき浴の攪拌状態、キャビテーションの状態が変わるが、周波数を２５〜６０ｋＨｚとすると、超音波の効果を安定して発揮することができる。
超音波振動子としては、例えばチタンやハステロイを外殻とした圧電セラミックなどを用いることができる。
<Applying ultrasonic vibration>
Also, if the Au plating thickness exceeds 20 nm, there is no problem, but if the Au plating thickness is 20 nm or less, it is not sufficient to adjust the pH and bath composition of the Au plating described above, and the pinholes of the plating film increase and the corrosion resistance decreases. To do. For this reason, ultrasonic wave irradiation is effective in Au plating with a thickness of 20 nm or less. The reason for this is that by using ultrasonic waves during Au plating, the Au plating bath is uniformly stirred and the gold ions in the bath are uniformly supplied to the surface of the substrate, so that pinholes can be reduced. Because. Further, cavitation is caused in the Au plating bath by ultrasonic waves, hydrogen and impurities staying on the surface of the base material are lifted, and plating defects (pinholes and the like) starting from these can be reduced.
The ultrasonic vibration may be applied to the base material and / or the Au plating bath. For example, the ultrasonic vibrator is brought into contact with the base material in the plating bath, or the ultrasonic vibrator is brought into contact with the Au plating bath. Thus, ultrasonic vibration can be applied. Moreover, although the stirring state and cavitation state of the Au plating bath change depending on the oscillation frequency of the ultrasonic vibration, when the frequency is 25 to 60 kHz, the effect of the ultrasonic wave can be stably exhibited.
As the ultrasonic vibrator, for example, a piezoelectric ceramic having titanium or hastelloy as an outer shell can be used.
＜封孔処理＞
Ａｕめっき層が封孔処理されていることが好ましい。Ａｕめっき層に被膜欠陥（ピンホール部）が存在しても、封孔処理によってこの欠陥を埋め、耐食性を維持することができる。Ａｕめっきの封孔処理は各種の方法が知られているが、メルカプト系水溶液中でＡｕめっき層を電解処理するのが好ましい。メルカプト系水溶液は、メルカプト基含有化合物を水に溶解したものであり、メルカプト基含有化合物としては、例えば特開２００４−２６５６９５号公報に記載されたメルカプトベンゾチアゾール誘導体が挙げられる。メルカプト系化合物はピンホール部に吸着、結合し，耐食性を向上させる。
<Sealing treatment>
The Au plating layer is preferably sealed. Even if a film defect (pinhole part) exists in the Au plating layer, the defect can be filled by the sealing treatment and the corrosion resistance can be maintained. Various methods are known for sealing the Au plating, but it is preferable to electrolyze the Au plating layer in a mercapto-based aqueous solution. The mercapto aqueous solution is obtained by dissolving a mercapto group-containing compound in water. Examples of the mercapto group-containing compound include mercaptobenzothiazole derivatives described in JP-A No. 2004-265695. Mercapto compounds are adsorbed and bonded to the pinholes to improve corrosion resistance.
＜試料の作製＞
表１に示す組成のオーステナイト系ステンレス鋼板（表１にＪＩＳ規格で記載）に対して冷間圧延と焼鈍を繰り返し、厚みが０．１０ｍｍの基材を得た。なお、表面粗さを小さくし、表面の清浄度を上げてめっき欠陥を抑制するため、仕上げ圧延はロール粗さＲａ≦０．０８μｍに制御した幅４５０ｍｍのロールを用い、表面酸化を抑制するため、焼鈍は全て水素90％以上の雰囲気内で行った。ロールの表面粗さは触針式粗さ計（ミツトヨ社製のＳＪ−４００）を用い、ＪＩＳ Ｂ ０６０１に準拠して測定した。
この基材に、前処理として市販の脱脂液を用いて電解脱脂後、水洗し、さらに電解酸洗後、水洗を施した。電解脱脂は、水酸化ナトリウム40g/Lと非イオン系界面活性剤5g/Lとを含有する脱脂液を使用し，基材を陰極にして10秒間電解した。電解酸洗は硫酸50g/Lを含有する水溶液を使用し，基材を陰極にして10秒間電解した。
<Preparation of sample>
Cold rolling and annealing were repeated on an austenitic stainless steel sheet having the composition shown in Table 1 (described in Table 1 in JIS standards) to obtain a base material having a thickness of 0.10 mm. In order to reduce the surface roughness, increase the surface cleanliness and suppress plating defects, the finish rolling uses a roll having a width of 450 mm controlled to a roll roughness Ra ≦ 0.08 μm, and suppresses surface oxidation. All annealing was performed in an atmosphere of 90% hydrogen or more. The surface roughness of the roll was measured according to JIS B 0601 using a stylus roughness meter (SJ-400 manufactured by Mitutoyo Corporation).
This substrate was subjected to electrolytic degreasing using a commercially available degreasing solution as a pretreatment, followed by washing with water, followed by electrolytic pickling and then washing with water. For electrolytic degreasing, a degreasing solution containing 40 g / L of sodium hydroxide and 5 g / L of a nonionic surfactant was used, and electrolysis was performed for 10 seconds using the substrate as a cathode. For the electrolytic pickling, an aqueous solution containing 50 g / L of sulfuric acid was used, and electrolysis was performed for 10 seconds using the base material as the cathode.
次に、前処理後の基材に直接Ａｕめっきを所定厚み（表１参照）行い、めっき材を作製した。ここで、図３に示すように、Ａｕめっき槽６の底部にハステロイを外殻とした超音波振動子（株式会社サンテック製）４を配置し、Ａｕめっき槽６内のＡｕめっき浴に超音波振動を与えつつ、アノード８に対向する基材２に電解めっきを行った。なお、Ａｕめっき槽６の側面にはシール構造６ａが設けられ、基材２（ステンレス条）はシール構造６ａを通ってＡｕめっき槽６の側面を通過しつつ、めっきされるようになっている。
Ａｕめっき液（シアン系）は、シアン化金カリウム（ＩＩＩ）（金濃度：１〜２ｇ／Ｌ）、硫酸水素ナトリウム５０〜１００ｇ／Ｌのものを用い、ｐＨを表１のように変化させた。ｐＨの調整は硫酸水素ナトリウムの添加量を変えて行った。なお、Ａｕめっきの際、めっき浴の金濃度１〜４ｇ／Ｌ、電流密度１〜８Ａ／ｄｍ２、の範囲に管理すれば特に問題はなかった。
Next, Au plating was directly performed on the base material after the pretreatment with a predetermined thickness (see Table 1) to prepare a plating material. Here, as shown in FIG. 3, an ultrasonic transducer 4 (manufactured by Suntech Co., Ltd.) 4 having Hastelloy as the outer shell is disposed at the bottom of the Au plating tank 6, and ultrasonic waves are applied to the Au plating bath in the Au plating tank 6. Electrolytic plating was performed on the substrate 2 facing the anode 8 while applying vibration. A seal structure 6a is provided on the side surface of the Au plating tank 6, and the base material 2 (stainless steel strip) is plated while passing through the side surface of the Au plating tank 6 through the seal structure 6a. .
The Au plating solution (cyanide) used was potassium gold cyanide (III) (gold concentration: 1 to 2 g / L) and sodium hydrogen sulfate 50 to 100 g / L, and the pH was changed as shown in Table 1. . The pH was adjusted by changing the amount of sodium hydrogen sulfate added. In the Au plating, there was no particular problem if the gold concentration in the plating bath was controlled within the range of 1 to 4 g / L and the current density of 1 to 8 A / dm 2 .
さらに、一部のめっき材（表１の発明例3-1,3-2）については、Ａｕめっきを行った後に封孔処理を行った。封孔処理はメルカプトベンゾチアゾールのナトリウム塩を1g/L含有する水溶液（発明例３−１），ベンゾトリアゾールのナトリウム塩を1g/L含有する水溶液（発明例３−２）を使用し，めっき材を陽極にして10秒間電解処理して行った。 Further, some plating materials (Invention Examples 3-1 and 3-2 in Table 1) were subjected to sealing treatment after Au plating. Sealing treatment uses an aqueous solution containing 1 g / L of a mercaptobenzothiazole sodium salt (Invention Example 3-1) and an aqueous solution containing 1 g / L of a sodium salt of benzotriazole (Invention Example 3-2). Was subjected to an electrolytic treatment for 10 seconds using as a positive electrode.
以上のようにして作製しためっき材表面の算術平均粗さＲａ、及び各種特性を以下のように測定した。 The arithmetic average roughness Ra and various characteristics of the surface of the plating material produced as described above were measured as follows.
＜表面粗さ＞
めっき前基材の表面粗さＲａはＪＩＳ Ｂ ０６０１に準拠し、非接触式三次元測定装置（三鷹光器社製、型式ＮＨ−３）を用い、カットオフ０．２５ｍｍ、測定長さ１．５０ｍｍ、ｎ＝５で測定し、その平均値をＲａ値とした。めっき後のＡｕめっき層の表面粗さＲａは、原子間力顕微鏡（島津製作所社製のＳＰＭ−９６００）を用い、ダイナミックモード（非接触方式）で、走査範囲１μｍ×１μｍ、走査速度０．８Ｈｚで、Ａｕめっき前の基材の結晶粒内に相当する場所をｎ＝３で測定し、その平均値をＲａの値として用いた。
<Surface roughness>
The surface roughness Ra of the base material before plating is based on JIS B 0601, using a non-contact type three-dimensional measuring device (manufactured by Mitaka Kogyo Co., Ltd., model NH-3), with a cutoff of 0.25 mm and a measurement length of 1. Measurement was performed at 50 mm and n = 5, and the average value was defined as the Ra value. The surface roughness Ra of the Au plating layer after plating is 1 μm × 1 μm in scanning range and scanning speed of 0.8 Hz in dynamic mode (non-contact method) using an atomic force microscope (SPM-9600 manufactured by Shimadzu Corporation). Then, the place corresponding to the crystal grains of the base material before Au plating was measured at n = 3, and the average value was used as the value of Ra.
＜Ａｕめっき層の密着性＞
Ａｕめっき材を９０度の角度に折り曲げ、次に曲げ部を０度に戻し、曲げ部にセロテープ（登録商標）を貼り付けてすぐに剥がし、Ａｕめっき層の剥離の有無を光学顕微鏡を用いて調査した。テープにＡｕめっき層が付着していないものを密着性が良好（ＯＫ）とした。
<Adhesion of Au plating layer>
The Au plating material is bent at an angle of 90 degrees, then the bent portion is returned to 0 degree, and a cello tape (registered trademark) is attached to the bent portion and peeled off immediately. The presence or absence of peeling of the Au plating layer is checked using an optical microscope. investigated. Adhesion was good (OK) when the Au plating layer did not adhere to the tape.
＜耐食性＞
試験片に０．８Ｖ（ＳＨＥ）の電位を印加させた状態で、９０℃，ｐＨ３の硫酸溶液に浸漬し、２０時間経過時に試験片に流れる電流を測定した。そして、以下の基準で耐食性を評価した。評価が◎〜△であれば実用上問題はない。
◎：腐食電流密度が1×10-7(A/cm2)未満
○：腐食電流密度が1×10-7(A/cm2)以上1×10-6(A/cm2)未満
△：腐食電流密度が1×10-6(A/cm2)以上1×10-5(A/cm2)未満
×：腐食電流密度が1×10-5(A/cm2)以上
<Corrosion resistance>
In a state where a potential of 0.8 V (SHE) was applied to the test piece, the test piece was immersed in a sulfuric acid solution at 90 ° C. and pH 3, and the current flowing through the test piece when 20 hours passed was measured. And corrosion resistance was evaluated according to the following criteria. If the evaluation is A to B, there is no practical problem.
◎: Corrosion current density is less than 1 × 10 -7 (A / cm 2 ) ○: Corrosion current density is 1 × 10 -7 (A / cm 2 ) or more and less than 1 × 10 -6 (A / cm 2 ) △: Corrosion current density is 1 × 10 -6 (A / cm 2 ) or more and less than 1 × 10 -5 (A / cm 2 ) ×: Corrosion current density is 1 × 10 -5 (A / cm 2 ) or more
＜外観＞
Ａｕめっき層の表面の外観を目視し、以下の基準で評価した。評価が○であれば実用上問題はない。
○：Ａｕめっき層の表面全体が一様に光沢を有する
×：Ａｕめっき層の表面に光沢部と無光沢部が混在する
<Appearance>
The appearance of the surface of the Au plating layer was visually observed and evaluated according to the following criteria. If the evaluation is ○, there is no practical problem.
○: The entire surface of the Au plating layer is uniformly glossy. X: The glossy portion and the matte portion are mixed on the surface of the Au plating layer.
得られた結果を表１に示す。なお、耐食性の評価は各めっき材の表面でのみ行った。 The obtained results are shown in Table 1. The corrosion resistance was evaluated only on the surface of each plating material.
表１から明らかなように、ｐＨ１．０以下のＡｕめっき浴を用い、超音波振動を付与した状態で電解めっきした各実施例の場合、Ａｕめっき層の厚みが２０ｎｍ以下であっても、Ａｕめっき層の密着性に優れ、耐食性にも優れていた。
なお、Ａｕめっき厚及びめっき浴のｐＨを同一とした発明例２−１〜２−４において、超音波振動の発振周波数をそれぞれ２５、６０ｋＨｚとした発明例２−１、２−２は他の発明例よりも腐食電流密度が小さく、耐食性がより優れていた。
又、Ａｕめっき後に封孔処理を施した発明例３−１、３−２の場合、Ａｕめっき厚、めっき浴のｐＨ及び超音波振動の発振周波数を同一とした発明例１−４に比べ、腐食電流密度が小さく、耐食性がより優れていた。
又、基材の表裏でＡｕめっき厚をそれぞれ変えた発明例４−１〜４−３の場合も、耐食性に優れていた。
As is clear from Table 1, in the case of each example in which an Au plating bath having a pH of 1.0 or less was used and electrolytic plating was performed with ultrasonic vibration applied, the Au plating layer had a thickness of 20 nm or less. Excellent adhesion of the plating layer and excellent corrosion resistance.
Inventive Examples 2-1 and 2-4 in which the Au plating thickness and the pH of the plating bath are the same, Inventive Examples 2-1 and 2-2 in which the oscillation frequency of ultrasonic vibration is 25 and 60 kHz, respectively, The corrosion current density was smaller than that of the inventive examples, and the corrosion resistance was more excellent.
Further, in the case of Invention Examples 3-1 and 3-2 subjected to sealing treatment after Au plating, compared to Invention Example 1-4 in which the Au plating thickness, the pH of the plating bath, and the oscillation frequency of the ultrasonic vibration are the same. Corrosion current density was small and corrosion resistance was more excellent.
Moreover, also in the case of invention examples 4-1 to 4-3 in which the Au plating thicknesses were changed on the front and back of the base material, the corrosion resistance was excellent.
なお、ロール粗さがＲａ＞０．０８μｍのロールで基材を仕上げ圧延し、基材の表面粗さＲａも０．０８μｍを超えた発明例５−１の場合、他の条件が同一の発明例１−３に比べ、腐食電流密度が大きくなったが実用上は問題ない。
又、Ａｕめっき浴中の金濃度を５．０ｇ／Ｌとした発明例６−１の場合、金濃度が１〜４ｇ／Ｌでありその他の条件が同一の発明例１−４に比べ、腐食電流密度が大きくなったが実用上は問題ない。
In addition, in the case of Invention Example 5-1, in which the base material is finish-rolled with a roll having a roll roughness Ra> 0.08 μm, and the surface roughness Ra of the base material also exceeds 0.08 μm, the other conditions are the same. Compared with Example 1-3, although the corrosion current density became large, there is no problem in practical use.
Further, in the case of Invention Example 6-1 in which the gold concentration in the Au plating bath was 5.0 g / L, the gold concentration was 1 to 4 g / L, and the other conditions were corrosive compared to Invention Example 1-4. Although the current density has increased, there is no practical problem.
一方、Ａｕめっき浴のｐＨが１．０を超えた比較例１−１の場合、Ａｕめっき層の密着性及び耐食性がいずれも劣った。
超音波振動を付与せずにＡｕめっきを行った比較例１−２の場合、耐食性が劣った。
又、超音波振動を付与せずにＡｕめっきを行った後、封孔処理を施した比較例３−１の場合も、耐食性が劣った。
Ａｕめっき浴中のＡｕ濃度を１０ｇ／Ｌとしてめっきした比較例６−１の場合、Ａｕめっき層のＲａが３．０ｎｍを超え、外観が劣った。
On the other hand, in the case of Comparative Example 1-1 in which the pH of the Au plating bath exceeded 1.0, both the adhesion and corrosion resistance of the Au plating layer were inferior.
In the case of Comparative Example 1-2 in which Au plating was performed without applying ultrasonic vibration, the corrosion resistance was inferior.
Further, in Comparative Example 3-1, in which Au plating was performed without applying ultrasonic vibration and then sealing treatment was performed, the corrosion resistance was inferior.
In Comparative Example 6-1 plated with an Au concentration of 10 g / L in the Au plating bath, the Ra of the Au plating layer exceeded 3.0 nm, and the appearance was poor.
２ 基材
４ 超音波振動子
６ Ａｕめっき槽
８ アノード
2 Substrate 4 Ultrasonic vibrator 6 Au plating tank 8 Anode
Claims (5)
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| JP2011026027A JP2012162791A (en) | 2011-02-09 | 2011-02-09 | Plated material for terminal or connector and manufacturing method therefor |
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| JP2017179558A (en) * | 2016-03-31 | 2017-10-05 | 古河電気工業株式会社 | Metallic material for thin film plating and method for producing the same |
| WO2024047466A1 (en) * | 2022-08-30 | 2024-03-07 | Molex, Llc | Connector and connector pair |
| WO2024047467A1 (en) * | 2022-08-30 | 2024-03-07 | Molex, Llc | Connector and connector pair |
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| JP2017179558A (en) * | 2016-03-31 | 2017-10-05 | 古河電気工業株式会社 | Metallic material for thin film plating and method for producing the same |
| WO2024047466A1 (en) * | 2022-08-30 | 2024-03-07 | Molex, Llc | Connector and connector pair |
| WO2024047467A1 (en) * | 2022-08-30 | 2024-03-07 | Molex, Llc | Connector and connector pair |
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