JP3685276B2 - Palladium / silver alloy plating bath - Google Patents
Palladium / silver alloy plating bath Download PDFInfo
- Publication number
- JP3685276B2 JP3685276B2 JP17138296A JP17138296A JP3685276B2 JP 3685276 B2 JP3685276 B2 JP 3685276B2 JP 17138296 A JP17138296 A JP 17138296A JP 17138296 A JP17138296 A JP 17138296A JP 3685276 B2 JP3685276 B2 JP 3685276B2
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- JP
- Japan
- Prior art keywords
- palladium
- silver
- silver alloy
- alloy plating
- plating bath
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Description
【0001】
【発明の属する技術分野】
本発明はパラジウム・銀合金めっき浴に関するものである。
【0002】
【従来の技術】
パラジウム−銀合金は均質な固溶体であり、耐変色性および耐腐食性が良好であることから、接点およびコネクター等の電子品用のめっきとして、使用されている。また、この合金は金と比べて材料コストが低いため、従来から用いられている金の代替材料として優れている。
【0003】
従来のパラジウム・銀合金めっき浴としては、パラジウム−アンモニウム錯体を含む浴、ピロリン酸錯体やチオシアン酸錯体を含む中性浴、エチレンジアミンパラジウム−シアン系銀浴、臭化物塩−亜硝酸塩浴などがある(参考資料として、特開平7−233496号公報参照)。
【0004】
【発明が解決しようとする課題】
しかしながら、このような従来のパラジウム・銀合金めっき浴により得られた析出物は、緻密な結晶を得ることができなかった。また、従来の浴においては、銀とパラジウムの析出電位が大きく離れているため、銀或いはパラジウムの析出過程が金属イオンの拡散支配となるため、密着性及び外観品質の面で問題があった。更に、浴自体の安定性も悪く、銀又はパラジウムの含有率が10%程度越えると析出物表面は粉末状或いは粗い突起状となった。
【0005】
この発明はこのような従来の技術に鑑みてなされたものであり、析出物の密着性及び外観品質、浴の安定性の面で優れたパラジウム・銀合金めっき浴を提供するものである。
【0006】
【課題を解決するための手段】
上記目的を達成するために、この発明のパラジウム・銀合金めっき浴は、パラジウム塩をPd量として1.0〜30g/l含有し、銀塩をAg量として0.01〜15g/l含有し、錯形成剤としてアミノポリカルボン酸を1.0〜300g/l含有して成るものである。
【0007】
【発明の実施の形態】
パラジウム塩としては、硝酸パラジウム、硫酸パラジウム、塩化パラジウム、ジアミノジクロロパラジウム、テトラアンミンパラジウムが好適である。パラジウム塩の含有量は、前述のように、Pd量として1.0〜30g/lであり、1.0g/l未満だと、有意な合金比率が得られず、30g/lを超えるとくみ出しによるPdの消費が多くなる。
【0008】
銀塩としては、硝酸銀、リン酸、酸化銀、硫酸銀が好適である。銀塩の含有量は、前述のように、0.01〜15g/lであり、0.01g/l未満だと、有意な合金比率が得られず、15g/lを超えるとコストが高くなり実用上不適となる。
【0009】
アミノポリカルボン酸としては、ジエチレントリアミン五酢酸、trans−1,2−シクロヘキサンジアミン四酢酸、エチレンジアミン四酢酸、イミノ二酢酸、ニトリロ三酢酸が好適である。アミノポリカルボン酸の含有量は、前述の通り、1.0〜300g/lであり、1.0未満だと浴が不安定となり、300g/lを超えるとくみ出しによる消費が多くなる。
【0010】
また、浴安定剤としてアミド系薬品を0.1〜100g/l含有しても良い。アミド系薬品としては、マロンアミド、グアニジン、プロピオンアミドが好適である。このアミド系薬品を添加することにより、パラジウム及び銀の第2の錯化剤となり、浴が高い温度及び高い電流密度においても安定する。
【0011】
また、pHは2.0〜14.0(より好ましくは、8〜13)が好適である。尚、pH調整剤として水酸化アルカリ金属を1.0〜300g/l程度添加しても良い。水酸化アルカリ金属としては、水酸化カリウム、水酸化ナトリウム等が好適である。
【0012】
めっき条件としては、浴温10〜90℃(より好ましくは20〜60℃)で、電流密度0.1〜50A/dm2 (より好ましくは、0.5〜10A/dm2 )が好適である。
【0013】
【実施例】
実施例1:
【0014】
まず、銅製のテストピースに下記表1に示す組成のパラジウム・銀合金めっき浴で電解めっきを行った。
【0015】
【表1】
【0016】
めっき条件は以下の通りである。
・pH………………………………………11
・電流密度…………………………………1A/dm2
・浴温………………………………………40℃
・時間………………………………………20分
・攪拌………………………………………一定
【0017】
得られた析出物をフレームレス原子吸光法により調べたところ、実施例1〜11はどの析出物も確実にPdとAgの合金組成になっていた。また、析出物の表面は金属光沢で、外観品質に優れていた。これに対し、比較対象としての実施例12、13の場合は、ともに表面が粉末状或いは黒い皮膜で外観品質の面で劣っている。
【0018】
そして、得られた析出物に対して、接着テープによるピーリングテストを行った。実施例1〜11の場合は、どのテストピースも析出物が剥がれず、密着性に優れていることが判明した。これに対して、比較対象としての実施例12、13場合は、析出物の剥離が生じ、密着性の面で劣っていた。
【0019】
実施例2:
次に、同じテストピースを使用して、下記表2に示す組成の浴で電解めっきを行った。そして、浴安定剤としてのアミド系薬品を添加した浴(実施例14、15、16)と、添加しない浴(実施例17、18、19)の浴安定について調べてみた。
【0020】
【表2】
【0021】
結果は表2に示すように、アミド系薬品を添加したものの方が、添加しないものに比べて、浴自身が安定であった。これは、アミド系薬品が、第2の錯化剤として作用しているものと思われる。
【0022】
実施例3:
次ぎに、浴中のAg量/(Pd量+Ag量)と、析出物中のAg量/(Pd量+Ag量)との関係を調べた。浴には安定剤としてマロンアミドをPd量+Ag量に応じて添加した。また、電流密度は1A/dm2 とした。
【0023】
結果として、浴中のAg量/(Pd量+Ag量)に応じて、析出物中のAg量/(Pd量+Ag量)が高まることが分かった。そして、浴中のPd量/(Pd量+Ag量)を変化させることにより、Ag量/(Pd量+Ag量)が20〜80%の範囲のパラジウム・銀合金を得られることが判明した。
【0024】
【発明の効果】
本発明に係るパラジウム・銀合金めっき浴によれば、外観及び密着性に優れたパラジウム・銀合金析出物を得ることができ、またアミド系薬品を浴に添加することにより、浴の安定性を向上させることができるため、産業上大変に有益である。特に、このめっき浴から得られためっき物は、リードフレームやコネクター等の電子部品として好適である。
【図面の簡単な説明】
【図1】浴中Ag量と析出物中Ag量の関係を示すグラフ。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a palladium / silver alloy plating bath.
[0002]
[Prior art]
Palladium-silver alloys are homogeneous solid solutions and have good discoloration resistance and corrosion resistance, and are therefore used as plating for electronic products such as contacts and connectors. In addition, since this alloy has a lower material cost than gold, it is excellent as an alternative material for gold used conventionally.
[0003]
Conventional palladium / silver alloy plating baths include a bath containing a palladium-ammonium complex, a neutral bath containing a pyrophosphate complex or a thiocyanate complex, an ethylenediamine palladium-cyanide silver bath, a bromide salt-nitrite bath, and the like ( As a reference material, refer to Japanese Patent Laid-Open No. 7-233696).
[0004]
[Problems to be solved by the invention]
However, the precipitates obtained by such a conventional palladium / silver alloy plating bath cannot obtain dense crystals. Further, in the conventional bath, since the deposition potential of silver and palladium is greatly separated, the deposition process of silver or palladium is governed by the diffusion of metal ions, and there is a problem in terms of adhesion and appearance quality. Furthermore, the stability of the bath itself was poor, and when the silver or palladium content exceeded about 10%, the surface of the precipitate became powdery or rough protrusions.
[0005]
The present invention has been made in view of such a conventional technique, and provides a palladium / silver alloy plating bath that is excellent in the adhesion and appearance quality of precipitates and the stability of the bath.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the palladium / silver alloy plating bath of the present invention contains a palladium salt in an amount of 1.0 to 30 g / l as a Pd amount and a silver salt in an amount of 0.01 to 15 g / l as an Ag amount. And 1.0 to 300 g / l of aminopolycarboxylic acid as a complexing agent.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
As the palladium salt, palladium nitrate, palladium sulfate, palladium chloride, diaminodichloropalladium, and tetraamminepalladium are suitable. As described above, the content of the palladium salt is 1.0 to 30 g / l as the amount of Pd, and if it is less than 1.0 g / l, a significant alloy ratio cannot be obtained, and if it exceeds 30 g / l, the amount of the palladium salt squeezes out. Pd consumption due to increases.
[0008]
As the silver salt, silver nitrate, phosphoric acid, silver oxide, and silver sulfate are suitable. As described above, the silver salt content is 0.01 to 15 g / l. If it is less than 0.01 g / l, a significant alloy ratio cannot be obtained, and if it exceeds 15 g / l, the cost increases. It becomes unsuitable for practical use.
[0009]
As the aminopolycarboxylic acid, diethylenetriaminepentaacetic acid, trans-1,2-cyclohexanediaminetetraacetic acid, ethylenediaminetetraacetic acid, iminodiacetic acid, and nitrilotriacetic acid are suitable. As described above, the content of aminopolycarboxylic acid is 1.0 to 300 g / l, and if it is less than 1.0, the bath becomes unstable, and if it exceeds 300 g / l, the consumption due to pumping increases.
[0010]
Moreover, you may contain 0.1-100 g / l of amide type chemical | medical agents as a bath stabilizer. As the amide chemical, malonamide, guanidine, and propionamide are preferable. By adding this amide chemical, it becomes a second complexing agent of palladium and silver, and the bath is stable even at high temperature and high current density.
[0011]
The pH is preferably 2.0 to 14.0 (more preferably 8 to 13). In addition, you may add about 1.0-300 g / l of alkali metal hydroxide as a pH adjuster. As the alkali metal hydroxide, potassium hydroxide, sodium hydroxide and the like are preferable.
[0012]
As plating conditions, a bath temperature of 10 to 90 ° C. (more preferably 20 to 60 ° C.) and a current density of 0.1 to 50 A / dm 2 (more preferably 0.5 to 10 A / dm 2 ) are suitable. .
[0013]
【Example】
Example 1:
[0014]
First, electrolytic plating was performed on a copper test piece using a palladium / silver alloy plating bath having the composition shown in Table 1 below.
[0015]
[Table 1]
[0016]
The plating conditions are as follows.
・ PH ………………………………………… 11
・ Current density …………………………………… 1A / dm 2
・ Bath temperature ………………………………………… 40 ℃
・ Time ………………………………………… 20 minutes ・ Stirring ………………………………………… Constant [0017]
When the obtained precipitates were examined by flameless atomic absorption spectroscopy, all the precipitates in Examples 1 to 11 had an alloy composition of Pd and Ag. Moreover, the surface of the deposit was metallic luster and was excellent in appearance quality. On the other hand, in the case of Examples 12 and 13 as comparative objects, the surface is inferior in terms of appearance quality because the surface is a powdery or black film.
[0018]
And the peeling test by an adhesive tape was done with respect to the obtained deposit. In the case of Examples 1 to 11, it was found that no deposits were peeled off from any test piece and the adhesion was excellent. On the other hand, in Examples 12 and 13 as comparative objects, the separation of the precipitates occurred and the adhesiveness was inferior.
[0019]
Example 2:
Next, using the same test piece, electrolytic plating was performed in a bath having the composition shown in Table 2 below. And it investigated about the bath stability of the bath (Examples 14, 15, and 16) which added the amide type chemical | medical agent as a bath stabilizer, and the bath (Examples 17, 18, and 19) which do not add.
[0020]
[Table 2]
[0021]
As a result, as shown in Table 2, the bath itself was more stable when the amide chemical was added than when the amide chemical was not added. This is probably because the amide chemical is acting as the second complexing agent.
[0022]
Example 3:
Next, the relationship between the Ag amount in the bath / (Pd amount + Ag amount) and the Ag amount in the precipitate / (Pd amount + Ag amount) was examined. As a stabilizer, malonamide was added to the bath according to the amount of Pd + Ag. The current density was set to 1A / dm 2.
[0023]
As a result, it was found that the Ag amount in the precipitate / (Pd amount + Ag amount) increased according to the Ag amount in the bath / (Pd amount + Ag amount). It was found that a palladium / silver alloy having an Ag amount / (Pd amount + Ag amount) in the range of 20 to 80% can be obtained by changing the amount of Pd in the bath / (Pd amount + Ag amount).
[0024]
【The invention's effect】
According to the palladium / silver alloy plating bath according to the present invention, a palladium / silver alloy deposit excellent in appearance and adhesion can be obtained, and the stability of the bath can be improved by adding an amide-based chemical to the bath. Because it can be improved, it is very useful in industry. In particular, the plated product obtained from this plating bath is suitable as an electronic component such as a lead frame or a connector.
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between the amount of Ag in a bath and the amount of Ag in a precipitate.
Claims (8)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP17138296A JP3685276B2 (en) | 1996-07-01 | 1996-07-01 | Palladium / silver alloy plating bath |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP17138296A JP3685276B2 (en) | 1996-07-01 | 1996-07-01 | Palladium / silver alloy plating bath |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH1018077A JPH1018077A (en) | 1998-01-20 |
JP3685276B2 true JP3685276B2 (en) | 2005-08-17 |
Family
ID=15922150
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP17138296A Expired - Fee Related JP3685276B2 (en) | 1996-07-01 | 1996-07-01 | Palladium / silver alloy plating bath |
Country Status (1)
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JP (1) | JP3685276B2 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2807450B1 (en) * | 2000-04-06 | 2002-07-05 | Engelhard Clal Sas | ELECTROLYTIC BATH FOR ELECTROCHEMICAL DEPOSITION OF PALLADIUM OR ITS ALLOYS |
JP2008081765A (en) * | 2006-09-26 | 2008-04-10 | Tanaka Kikinzoku Kogyo Kk | Palladium alloy plating solution and method for plating using the same |
TWI354716B (en) * | 2007-04-13 | 2011-12-21 | Green Hydrotec Inc | Palladium-containing plating solution and its uses |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2657925A1 (en) * | 1976-12-21 | 1978-06-22 | Siemens Ag | AMMONIA-FREE, AQUATIC BATH FOR GALVANIC DEPOSITION OF PALLADIUM OR. PALLADIUM ALLOYS |
FR2403399A1 (en) * | 1977-09-19 | 1979-04-13 | Oxy Metal Industries Corp | SHINY PALLADIUM ELECTROLYTIC COATING BATHS |
JPS5776196A (en) * | 1980-10-30 | 1982-05-13 | Kumamotoken | Silver-palladium alloy plating liquid |
US4478692A (en) * | 1982-12-22 | 1984-10-23 | Learonal, Inc. | Electrodeposition of palladium-silver alloys |
KR0171685B1 (en) * | 1994-02-26 | 1999-02-18 | 문성수 | Palladium alloy plating compositions comprising two or three components |
-
1996
- 1996-07-01 JP JP17138296A patent/JP3685276B2/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
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JPH1018077A (en) | 1998-01-20 |
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