JP4599599B2 - Electroless gold plating solution - Google Patents

Electroless gold plating solution Download PDF

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JP4599599B2
JP4599599B2 JP2001025237A JP2001025237A JP4599599B2 JP 4599599 B2 JP4599599 B2 JP 4599599B2 JP 2001025237 A JP2001025237 A JP 2001025237A JP 2001025237 A JP2001025237 A JP 2001025237A JP 4599599 B2 JP4599599 B2 JP 4599599B2
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Prior art keywords
gold plating
electroless
plating solution
gold
electroless gold
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JP2002226975A (en
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薫 内藤
喜美子 工藤
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奥野製薬工業株式会社
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Description

【0001】
【発明の属する技術分野】
本発明は、無電解金めっき液に関する。
【0002】
【従来の技術】
プリント基板等の配線基板は、はんだ付性、ワイヤーボンディング性等の改善のために、配線回路の実装部分、端子部分等に金めっき皮膜を形成することが多い。この場合に、一般には、配線回路の耐食性向上、金の拡散防止等の目的で、金めっきの下地皮膜としてニッケルめっき皮膜が形成されている。
【0003】
近年、半導体素子の集積化が急速に進み、これを搭載する配線基板にも高い配線密度が要求されており、現在では電気的に独立した配線パターンが主流となっている。この様な場合、電気めっき法ではめっき皮膜を形成できない部分が発生するため、無電解めっき法が採用されており、通常は、無電解ニッケル−リン皮膜を形成した後、無電解金めっき皮膜が形成されている。
【0004】
無電解金めっき液としては、置換タイプの無電解金めっき液と自己触媒タイプの無電解金めっき液が知られている。これらの内で、置換タイプの無電解金めっき液は、ニッケル等の下地金属との置換反応によって金が析出するものであるが、一般に、下地金属の種類や作業条件等の要因の影響を受けやすく、ニッケル皮膜が過度に浸食されて析出した金皮膜の外観が赤みを帯びたり、金とニッケル等の下地金属との密着性の低下を引き起こすという問題がある。
【0005】
一方、自己触媒タイプの無電解金めっき液は、還元剤を含有するめっき液であり、形成された金めっき皮膜による自己触媒作用を利用して、還元作用で金を析出させるものである。この様な自己触媒タイプの無電解金めっき液は、下地金属に直接皮膜を形成することが難しく、下地金属に直接めっきを行うと、粗雑な析出になる場合や未析出部分が生じる場合があり、下地金属との密着性が不十分になりやすいという欠点がある。
【0006】
【発明が解決しようとする課題】
本発明の主な目的は、下地金属の腐食を極力抑えて、均一で密着性に優れた無電解金めっき皮膜を形成することが可能な無電解金めっき液を提供することである。
【0007】
【課題を解決するための手段】
本発明者は、上記問題点に鑑みて鋭意研究を重ねた結果、無電解金めっき液の還元剤として、スルホキシル酸塩のホルムアルデヒド誘導体及び亜二チオン酸塩から選ばれた少なくとも一種の化合物を用いる場合には、下地金属と金との置換反応で形成された金めっき皮膜上に、還元反応によって金めっき皮膜が形成されて下地金属の腐食を抑制でき、下地金属との密着性に優れた外観の良好な無電解金めっき皮膜を形成できることを見出した。更に、これらの還元剤を亜硫酸塩と組み合わせて用いる場合には、金の還元析出がより一層促進されて、下地金属の腐食を防止すると同時に、金めっき速度も向上し、比較的短時間に下地金属との密着性に優れた外観の良好な無電解金めっき皮膜が形成されることを見出し、ここに本発明を完成するに至った。
【0008】
即ち、本発明は、下記の無電解金めっき液を提供するものである。
1. (i)水溶液金塩、(ii)錯化剤、並びに(iii)スルホキシル酸塩のホルムアルデヒド誘導体及び亜二チオン酸塩から選ばれた少なくとも一種の化合物を含有する水溶液からなる無電解金めっき液。
2. スルホキシル酸塩のホルムアルデヒド誘導体及び亜二チオン酸塩から選ばれた少なくとも一種の化合物が、ホルムアルデヒドナトリウムスルホキシラート、ホルムアルデヒド亜鉛スルホキシラート、亜二チオン酸ナトリウム、亜二チオン酸カリウム及び亜二チオン酸アンモニウムから選ばれた少なくとも一種の化合物である上記項1に記載の無電解金めっき液。
3. 水溶性金塩を金イオン濃度として0.001〜0.03mol/l、錯化剤を0.01mol/l以上、並びにスルホキシル酸塩のホルムアルデヒド誘導体及び亜二チオン酸塩から選ばれた少なくとも一種の化合物を0.0005〜0.2mol/l含有する水溶液である上記項1又は2に記載の無電解金めっき液。
4. 更に、亜硫酸塩を含有する水溶液である上記項1〜3のいずれかに記載の無電解金めっき液。
5. 亜硫酸塩を0.001〜0.2mol/l含有する水溶液である上記項4に記載の無電解金めっき液。
【0009】
【発明の実施の形態】
本発明の無電解金めっき液は、(i)水溶液金塩、(ii)錯化剤、並びに(iii)スルホキシル酸塩のホルムアルデヒド誘導体及び亜二チオン酸塩から選ばれた少なくとも一種の化合物を含有する水溶液である。
【0010】
上記した成分の内で、スルホキシル酸塩のホルムアルデヒド誘導体及び亜二チオン酸塩から選ばれた少なくとも一種の化合物は、還元剤として作用するものであり、該化合物を還元剤として用いることによって、下地金属との置換反応によって形成された金めっき皮膜上に、還元反応によって良好な金めっき皮膜が形成され、下地金属の腐食が抑制されて、均一で密着性に優れた金めっき皮膜を形成することが可能となる。
【0011】
更に、本発明の無電解金めっき液では、上記した(i)〜(iii)の成分に加えて亜硫酸塩を配合する場合には、金めっきの速度が向上して、下地金属の腐食をより一層有効に抑制でき、短時間で密着性に優れた均一な金めっき皮膜を形成することが可能となる。
【0012】
本発明の無電解金めっき液で用いることができる亜二チオン酸塩の具体例としては、亜二チオン酸ナトリウム、亜二チオン酸カリウム、亜二チオン酸アンモニウム等を挙げることができる。また、スルホキシル酸塩のホルムアルデヒド誘導体としては、ロンガリットC、ロンガリットZなどの名称で市販されているホルムアルデヒドナトリウムスルホキシラート(ナトリウムホルムアルデヒドスルホキシレート)、ホルムアルデヒド亜鉛スルホキシラート(亜鉛ホルムアルデヒドスルホキシレート)等を用いることができる。スルホキシル酸塩のホルムアルデヒド誘導体と亜二チオン酸塩は、一種単独又は二種以上混合して用いることができる。
【0013】
スルホキシル酸塩のホルムアルデヒド誘導体及び亜二チオン酸塩から選ばれた少なくとも一種の化合物の添加量は、0.0005〜0.2mol/l程度とすることが好ましく、0.001〜0.03mol/l程度とすることがより好ましい。これらの化合物の添加量が少なすぎる場合には、金めっきの析出性が低下し易く、一方、添加量が多すぎると金めっき液が不安定になり易いので好ましくない。但し、亜二チオン酸塩については、配合量が多くなるとめっき液の安定性が低下し易いので、添加量の上限は0.05mol/l程度とすることが好ましい。
【0014】
本発明の無電解金めっき液では、水溶性金塩としては、公知の金めっき液において金供給源として用いられている各種化合物を用いることができる。具体的には、シアン化金第一カリウム、シアン化金第二カリウム等のシアン化金塩、塩化金酸、塩化金酸のカリウム塩、アンモニウム塩等の水溶性金化合物を用いることができるが、その他に、シアン化金、酸化金、水酸化金等の比較的溶解度の低い金化合物であっても、シアン化合物と混合して水中でシアン錯体を形成することによって金イオン源として使用できる。これらの金化合物は、一種単独または二種以上混合して用いることができる。
【0015】
金イオン濃度は、0.001〜0.03mol/l程度とすることが好ましい。金イオン濃度が低すぎる場合には析出速度が低下しやすく、一方、金イオン濃度が高すぎると、汲み出しなどによる経済的損失が大きくなるので好ましくない。
【0016】
錯化剤としては、公知の無電解金めっき液で用いられているものが使用できる。具体的には、リン酸、ホウ酸等の無機酸、その塩類(ナトリウム塩、カリウム塩、アンモニウム塩等);クエン酸、グルコン酸、酒石酸、乳酸、リンゴ酸等のカルボン酸、その塩類(ナトリウム塩、カリウム塩、アンモニウム塩等);エチレンジアミン、トリエタノールアミン等のアミン化合物;グリシン、アラニン、エチレンジアミン四酢酸、ニトリロトリ酢酸等のアミノカルボン酸、その塩類(ナトリウム塩、カリウム塩、アンモニウム塩等);アミノトリメチレンホスホン酸、エチレンジアミンテトラメチレンホスホン酸等のホスホン酸、その塩類(ナトリウム塩、カリウム塩、アンモニウム塩等)などを用いることができる。錯化剤の含有量は、特に限定的ではないが、0.01mol/l程度以上とすることが好ましく、0.05〜0.5mol/l程度とすることがより好ましい。錯化剤の配合量が少なすぎると、置換反応が遅くなって充分な金めっき皮膜を形成できないので好ましくない。
【0017】
本発明では、亜硫酸塩としては、亜硫酸ナトリウム、亜硫酸カリウムなどを用いることができる。本発明のめっき液中の亜硫酸塩の含有量は、0.001〜0.2mol/l程度とすることが好ましい。亜硫酸塩の配合量が少なすぎる場合には、金の還元析出反応を促進する効果が充分には得られず、一方、亜硫酸塩の配合量が多すぎると、汲み出しなどによる経済的な損失が生じるので好ましくない。
【0018】
本発明の無電解金めっき液には、必要に応じて、公知の無電解金めっき液で用いられている安定剤を配合することができる。具体的には、シアン化ナトリウム、シアン化カリウムなどのシアン化合物、2−メルカプトベンゾチアゾール、2−メルカプトベンゾチアゾール等の含硫黄有機化合物、ベンゾトリアゾールなどの含窒素化合物などを用いることができる。安定剤の含有量は特に限定的ではないが、0.0001〜0.02mol/l程度とすることが好ましい。安定剤の配合量が少なすぎる場合には、浴の安定性を充分に向上させることができない。一方、安定剤の配合量が多すぎると金の析出性が低下するので好ましくない。
【0019】
また、本発明の無電解金めっき液では、液中に金コロイドが生成した場合には、空気撹拌を行うことによって、金コロイドを酸化し再溶解させて、浴を安定化させることができる。
【0020】
めっき浴のpHは、5〜10程度とすることが好ましい。pHが低すぎると、還元剤の自己分解が生じ、一方、pHが高すぎると還元力が強くなり、共に浴の安定性が低下するので好ましくない。pH調整剤としては特に限定はなく、公知のめっき液で使用されている水酸化ナトリウム、水酸化カリウムなどの水酸化アルカリ、水酸化アンモニウムなどのアルカリ性化合物、硫酸、リン酸、ホウ酸などの鉱酸等を使用することができる。
【0021】
本発明の無電解金めっき液では、浴温度は40℃〜75℃程度が好ましい。浴温度が低すぎると金の析出速度が不充分となり、浴温度が高すぎると浴の安定性が低下するので好ましくない。
【0022】
本発明の無電解金めっき液では、下地金属の種類については特に限定的ではなく、従来の置換型無電解金めっき液によって金めっき皮膜を析出させることが可能な金属であれば、何れも下地金属とすることができる。特に、プリント基板等の様に下地金属がニッケル金属や無電解ニッケルめっき皮膜の場合には、本発明の無電解金めっき液を用いることによって、ニッケル金属や無電解ニッケルめっき皮膜の腐食が抑制され、均一で密着性に優れた無電解金めっき皮膜を形成できる点で非常に有利である。この場合、無電解ニッケルめっき皮膜の種類は特に限定されず、例えば、Ni−P系無電解めっき皮膜、Ni−B系無電解めっき皮膜等を下地金属とすることができる。
【0023】
【発明の効果】
本発明の無電解金めっき液によれば、下地金属の腐食を抑制して、均一で密着性に優れた無電解金めっき皮膜を形成できる。
【0024】
【実施例】
以下に実施例及び比較例を示し更に詳細に説明する。
【0025】
実施例1〜7及び比較例1〜2
銅による回路パターンを形成したプリント配線基板(5×5cm)(めっき有効面積15cm2)を被処理物として用い、これを脱脂液(商標:ICPクリーンS−135:奥野製薬工業(株))に浸漬して脱脂処理し、100g/l過硫酸ナトリウム水溶液に浸漬してソフトエッチングを行い、次いで10%硫酸水溶液に浸漬してスマット除去を行った。
【0026】
続いて、触媒液(商標:ICPアクセラ:奥野製薬工業(株))に浸漬して、無電解ニッケル−リンめっき(商標:ICPニコロン:奥野製薬工業(株))を行った。これにより、膜厚5μmの無電解ニッケル−リンめっき皮膜が形成された。
【0027】
次いで、下記組成の無電解金めっき液を用いて、処理温度60℃、処理時間10分で金めっき皮膜を形成した。尚、比較例2については、処理温度85℃で10分間無電解金めっきを行った。
【0028】
(無電解金めっき組成)
シアン化第一金カリウム 0.007mol/l
EDTA・2Na 0.05 mol/l
亜硫酸ナトリウム 表1に記載の濃度
ホルムアルデヒドナトリウムスルホキシラート 表1に記載の濃度
亜二チオン酸ナトリウム 表1に記載の濃度
シアン化カリウム 0.003mol/l
(20%水酸化カリウム溶液でpH7に調整)
形成されためっき皮膜について、析出速度及びニッケル皮膜の腐食状態を調べた。めっき皮膜の厚さは、蛍光X線微小部膜厚計(「SFT−8000」セイコー電子工業(株)製)により測定した。ニッケル皮膜の腐食状態については、形成した金めっき皮膜を金剥離剤(商標:トップリップPD:奥野製薬工業(株))で剥離後、走査型電子顕微鏡(「JSM−5800」:日本電子(株)製)でニッケル表面を観察して評価した。また、無電解金めっき液の分解による金の析出の有無を観察して、無電解めっき液の安定性を評価した。結果を下記表1に示す。
【0029】
【表1】
【0030】
以上の結果から明らかなように、ホルムアルデヒドナトリウムスルホキシラートを還元剤とする実施例1の無電解金めっき液によれば、下地の無電解ニッケルめっき皮膜に腐食を生じることなく、良好な無電解金めっき皮膜を形成できた。また、ホルムアルデヒドナトリウムスルホキシラート又は亜二チオン酸ナトリウムと亜硫酸塩を含有する実施例2〜7の無電解金めっき液によれば、下地の無電解ニッケルめっき皮膜に腐食を生じることなく、より速い析出速度で良好な無電解金めっき皮膜を形成できた。
【0031】
これに対して、還元剤と亜硫酸ナトリウムを無添加の比較例1によれば、金めっき皮膜の析出速度が遅く、しかも下地の無電解ニッケルめっき皮膜にピット状の腐食が多数生じた。また、このめっき液の液温を上昇させて析出速度を上昇させた比較例2の場合にも、下地の無電解ニッケルめっき皮膜にピット状の腐食が多数生じた。
[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electroless gold plating solution.
[0002]
[Prior art]
A wiring board such as a printed circuit board is often formed with a gold plating film on a mounting portion of a wiring circuit, a terminal portion or the like in order to improve solderability, wire bonding property, and the like. In this case, generally, a nickel plating film is formed as an undercoat film for gold plating for the purpose of improving the corrosion resistance of the wiring circuit and preventing gold diffusion.
[0003]
In recent years, integration of semiconductor elements has progressed rapidly, and a wiring board on which the semiconductor elements are mounted is required to have a high wiring density. At present, electrically independent wiring patterns are mainstream. In such a case, an electroless plating method is adopted because a portion where an electroplating method cannot form a plating film is generated. Usually, after an electroless nickel-phosphorus film is formed, an electroless gold plating film is formed. Is formed.
[0004]
As the electroless gold plating solution, a substitution type electroless gold plating solution and an autocatalytic type electroless gold plating solution are known. Of these, substitution-type electroless gold plating solutions are those in which gold is deposited by a substitution reaction with a base metal such as nickel, but are generally affected by factors such as the type of base metal and working conditions. There is a problem in that the appearance of the gold film deposited easily due to excessive erosion of the nickel film is reddish, or the adhesion between the gold and the underlying metal such as nickel is reduced.
[0005]
On the other hand, the autocatalytic electroless gold plating solution is a plating solution containing a reducing agent, and deposits gold by a reducing action using the autocatalytic action of the formed gold plating film. Such an autocatalytic electroless gold plating solution is difficult to form a film directly on the underlying metal, and when directly plated on the underlying metal, rough precipitation or undeposited parts may occur. There is a drawback that the adhesion to the base metal tends to be insufficient.
[0006]
[Problems to be solved by the invention]
The main object of the present invention is to provide an electroless gold plating solution capable of forming an electroless gold plating film that is uniform and excellent in adhesion while suppressing corrosion of a base metal as much as possible.
[0007]
[Means for Solving the Problems]
As a result of intensive studies in view of the above problems, the present inventor uses at least one compound selected from a formaldehyde derivative of sulfoxylate and a dithionite as a reducing agent for an electroless gold plating solution. In this case, the gold plating film is formed by a reduction reaction on the gold plating film formed by the substitution reaction between the base metal and gold, so that the corrosion of the base metal can be suppressed and the appearance excellent in adhesion to the base metal. It was found that a good electroless gold plating film can be formed. Furthermore, when these reducing agents are used in combination with sulfites, the reduction and deposition of gold is further promoted to prevent corrosion of the base metal, and at the same time, the gold plating rate is improved, and the base is made in a relatively short time. The present inventors have found that an electroless gold plating film having an excellent appearance with excellent adhesion to a metal is formed, and the present invention has been completed here.
[0008]
That is, the present invention provides the following electroless gold plating solution.
1. An electroless gold plating solution comprising an aqueous solution containing at least one compound selected from (i) an aqueous gold salt, (ii) a complexing agent, and (iii) a formaldehyde derivative of sulfoxylate and a dithionite.
2. At least one compound selected from formaldehyde derivatives of sulfoxylate and dithionite is sodium formaldehyde sulfoxylate, formaldehyde zinc sulfoxylate, sodium dithionite, potassium dithionite and dithionite Item 2. The electroless gold plating solution according to Item 1, which is at least one compound selected from ammonium.
3. Water-soluble gold salt as a gold ion concentration of 0.001 to 0.03 mol / l, complexing agent of 0.01 mol / l or more, and at least one selected from a formaldehyde derivative of sulfoxylate and dithionite Item 3. The electroless gold plating solution according to Item 1 or 2, which is an aqueous solution containing 0.0005 to 0.2 mol / l of a compound.
4). The electroless gold plating solution according to any one of Items 1 to 3, which is an aqueous solution containing a sulfite.
5). Item 5. The electroless gold plating solution according to Item 4, which is an aqueous solution containing 0.001 to 0.2 mol / l of sulfite.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The electroless gold plating solution of the present invention contains at least one compound selected from (i) an aqueous gold salt, (ii) a complexing agent, and (iii) a formaldehyde derivative of sulfoxylate and a dithionite. It is an aqueous solution.
[0010]
Among the above-described components, at least one compound selected from the formaldehyde derivatives of sulfoxylate and dithionite acts as a reducing agent, and by using the compound as a reducing agent, the base metal A good gold plating film is formed by a reduction reaction on the gold plating film formed by the substitution reaction with the above, and the corrosion of the base metal is suppressed to form a uniform gold plating film with excellent adhesion. It becomes possible.
[0011]
Furthermore, in the electroless gold plating solution of the present invention, when sulfite is added in addition to the components (i) to (iii) described above, the speed of gold plating is improved and corrosion of the base metal is further improved. It can be suppressed more effectively and a uniform gold plating film having excellent adhesion can be formed in a short time.
[0012]
Specific examples of dithionite that can be used in the electroless gold plating solution of the present invention include sodium dithionite, potassium dithionite, and ammonium dithionite. Examples of formaldehyde derivatives of sulfoxylate include formaldehyde sodium sulfoxylate (sodium formaldehyde sulfoxylate), formaldehyde zinc sulfoxylate (zinc formaldehyde sulfoxylate), etc., which are commercially available under names such as Rongalit C and Rongalit Z. Can be used. The formaldehyde derivative of sulfoxylate and dithionite can be used singly or in combination of two or more.
[0013]
The addition amount of at least one compound selected from the formaldehyde derivative of sulfoxylate and dithionite is preferably about 0.0005 to 0.2 mol / l, preferably 0.001 to 0.03 mol / l. More preferably, it is about. If the addition amount of these compounds is too small, the deposition properties of the gold plating are likely to be lowered, whereas if the addition amount is too large, the gold plating solution tends to become unstable, which is not preferable. However, with respect to dithionite, the stability of the plating solution tends to decrease as the blending amount increases, so the upper limit of the addition amount is preferably about 0.05 mol / l.
[0014]
In the electroless gold plating solution of the present invention, as the water-soluble gold salt, various compounds used as a gold supply source in a known gold plating solution can be used. Specifically, gold cyanide salts such as gold potassium cyanide and potassium potassium cyanide, and water-soluble gold compounds such as chloroauric acid, potassium chloroauric acid and ammonium salts can be used. In addition, even a gold compound having a relatively low solubility such as gold cyanide, gold oxide, and gold hydroxide can be used as a gold ion source by mixing with a cyan compound to form a cyan complex in water. These gold compounds can be used singly or in combination of two or more.
[0015]
The gold ion concentration is preferably about 0.001 to 0.03 mol / l. If the gold ion concentration is too low, the deposition rate tends to decrease. On the other hand, if the gold ion concentration is too high, economic loss due to pumping or the like increases, which is not preferable.
[0016]
As the complexing agent, those used in known electroless gold plating solutions can be used. Specifically, inorganic acids such as phosphoric acid and boric acid, salts thereof (sodium salt, potassium salt, ammonium salt, etc.); carboxylic acids such as citric acid, gluconic acid, tartaric acid, lactic acid, malic acid, salts thereof (sodium) Salts, potassium salts, ammonium salts, etc.); amine compounds such as ethylenediamine, triethanolamine; aminocarboxylic acids such as glycine, alanine, ethylenediaminetetraacetic acid, nitrilotriacetic acid, salts thereof (sodium salts, potassium salts, ammonium salts, etc.); Phosphonic acids such as aminotrimethylenephosphonic acid and ethylenediaminetetramethylenephosphonic acid, and salts thereof (sodium salt, potassium salt, ammonium salt, etc.) can be used. The content of the complexing agent is not particularly limited, but is preferably about 0.01 mol / l or more, and more preferably about 0.05 to 0.5 mol / l. If the amount of the complexing agent is too small, the substitution reaction is slow and a sufficient gold plating film cannot be formed.
[0017]
In the present invention, sodium sulfite, potassium sulfite and the like can be used as the sulfite. The content of sulfite in the plating solution of the present invention is preferably about 0.001 to 0.2 mol / l. If the amount of sulfite is too small, the effect of promoting the reduction and precipitation reaction of gold cannot be obtained sufficiently. On the other hand, if the amount of sulfite is too large, economic loss due to pumping out or the like occurs. Therefore, it is not preferable.
[0018]
The electroless gold plating solution of the present invention can be blended with a stabilizer used in a known electroless gold plating solution, if necessary. Specifically, cyanide compounds such as sodium cyanide and potassium cyanide, sulfur-containing organic compounds such as 2-mercaptobenzothiazole and 2-mercaptobenzothiazole, nitrogen-containing compounds such as benzotriazole, and the like can be used. The content of the stabilizer is not particularly limited, but is preferably about 0.0001 to 0.02 mol / l. When the amount of the stabilizer is too small, the stability of the bath cannot be sufficiently improved. On the other hand, when the amount of the stabilizer is too large, the gold precipitation is reduced, which is not preferable.
[0019]
Further, in the electroless gold plating solution of the present invention, when gold colloid is generated in the solution, the gold colloid can be oxidized and re-dissolved by air stirring to stabilize the bath.
[0020]
The pH of the plating bath is preferably about 5 to 10. If the pH is too low, self-decomposition of the reducing agent occurs. On the other hand, if the pH is too high, the reducing power becomes strong, and the stability of the bath is lowered. There is no particular limitation on the pH adjuster, and alkali hydroxides such as sodium hydroxide and potassium hydroxide, alkaline compounds such as ammonium hydroxide, minerals such as sulfuric acid, phosphoric acid and boric acid, which are used in known plating solutions. An acid or the like can be used.
[0021]
In the electroless gold plating solution of the present invention, the bath temperature is preferably about 40 ° C to 75 ° C. If the bath temperature is too low, the gold deposition rate becomes insufficient, and if the bath temperature is too high, the stability of the bath decreases, which is not preferable.
[0022]
In the electroless gold plating solution of the present invention, the type of the base metal is not particularly limited, and any base metal can be used as long as it can deposit a gold plating film with a conventional substitutional electroless gold plating solution. It can be metal. In particular, when the base metal is nickel metal or an electroless nickel plating film such as a printed circuit board, the corrosion of the nickel metal or electroless nickel plating film is suppressed by using the electroless gold plating solution of the present invention. It is very advantageous in that an electroless gold plating film having a uniform and excellent adhesion can be formed. In this case, the type of electroless nickel plating film is not particularly limited, and for example, a Ni-P electroless plating film, a Ni-B electroless plating film, or the like can be used as a base metal.
[0023]
【The invention's effect】
According to the electroless gold plating solution of the present invention, it is possible to suppress the corrosion of the base metal and form an electroless gold plating film having excellent uniformity and adhesion.
[0024]
【Example】
Hereinafter, examples and comparative examples will be described in more detail.
[0025]
Examples 1-7 and Comparative Examples 1-2
A printed wiring board (5 × 5 cm) (plating effective area 15 cm 2 ) on which a circuit pattern of copper is formed is used as an object to be processed, and this is used as a degreasing solution (trademark: ICP Clean S-135: Okuno Pharmaceutical Co., Ltd.). It was immersed and degreased, immersed in a 100 g / l sodium persulfate aqueous solution for soft etching, and then immersed in a 10% aqueous sulfuric acid solution for smut removal.
[0026]
Subsequently, it was immersed in a catalyst solution (trademark: ICP Axela: Okuno Pharmaceutical Industry Co., Ltd.), and electroless nickel-phosphorous plating (trademark: ICP Nicolon: Okuno Pharmaceutical Industry Co., Ltd.) was performed. As a result, an electroless nickel-phosphorous plating film having a thickness of 5 μm was formed.
[0027]
Next, a gold plating film was formed using an electroless gold plating solution having the following composition at a processing temperature of 60 ° C. and a processing time of 10 minutes. In Comparative Example 2, electroless gold plating was performed at a treatment temperature of 85 ° C. for 10 minutes.
[0028]
(Electroless gold plating composition)
Potassium cyanide potassium 0.007 mol / l
EDTA · 2Na 0.05 mol / l
Sodium sulfite Concentration formaldehyde sodium sulfoxylate described in Table 1 Concentration sodium dithionite described in Table 1 Concentration potassium cyanide described in Table 1 0.003 mol / l
(Adjusted to pH 7 with 20% potassium hydroxide solution)
For the formed plating film, the deposition rate and the corrosion state of the nickel film were examined. The thickness of the plating film was measured with a fluorescent X-ray microscopic part thickness meter (“SFT-8000” manufactured by Seiko Electronics Industry Co., Ltd.). Regarding the corrosion state of the nickel film, the formed gold plating film was peeled off with a gold release agent (trademark: Top Lip PD: Okuno Pharmaceutical Co., Ltd.), and then a scanning electron microscope (“JSM-5800”: JEOL Ltd. The surface of nickel was observed and evaluated. In addition, the presence or absence of gold deposition due to decomposition of the electroless gold plating solution was observed to evaluate the stability of the electroless plating solution. The results are shown in Table 1 below.
[0029]
[Table 1]
[0030]
As is clear from the above results, according to the electroless gold plating solution of Example 1 using sodium formaldehyde sulfoxylate as the reducing agent, the electroless nickel plating film of the base is not corroded, and good electroless A gold plating film could be formed. In addition, according to the electroless gold plating solution of Examples 2 to 7 containing sodium formaldehyde sulfoxylate or sodium dithionite and sulfite, the underlying electroless nickel plating film is faster without causing corrosion. A good electroless gold plating film could be formed at the deposition rate.
[0031]
On the other hand, according to Comparative Example 1 in which no reducing agent and sodium sulfite were added, the deposition rate of the gold plating film was slow, and many pit-like corrosions occurred in the underlying electroless nickel plating film. In the case of Comparative Example 2 in which the deposition temperature was increased by increasing the temperature of the plating solution, many pit-like corrosions occurred in the underlying electroless nickel plating film.

Claims (5)

  1. (i)水溶液金塩、(ii)錯化剤、及び(iii)スルホキシル酸塩のホルムアルデヒド誘導体を含有する水溶液からなる無電解金めっき液。(I) an aqueous solution gold salts, (ii) a complexing agent, and (iii) sulfoxyl electroless gold plating solution comprising an aqueous solution containing formaldehyde induction of salt.
  2. スルホキシル酸塩のホルムアルデヒド誘導体が、ホルムアルデヒドナトリウムスルホキシラート及びホルムアルデヒド亜鉛スルホキシラートから選ばれた少なくとも一種の化合物である請求項1に記載の無電解金めっき液。Formaldehyde induction of sulfoxylate salt is an electroless gold plating solution according to claim 1 is at least one compound selected or et sodium formaldehyde sulfoxylate and formaldehyde zinc Suruhokishira bets.
  3. 水溶性金塩を金イオン濃度として0.001〜0.03mol/l、錯化剤を0.01mol/l以上、及びスルホキシル酸塩のホルムアルデヒド誘導体を0.0005〜0.2mol/l含有する水溶液である請求項1又は2に記載の無電解金めっき液。0.001~0.03mol / l of water-soluble gold salt as a gold ion concentration, the complexing agent 0.01 mol / l or more, and containing 0.0005~0.2mol / l formaldehyde induction of sulfoxylate salt The electroless gold plating solution according to claim 1 or 2, which is an aqueous solution.
  4. 更に、亜硫酸塩を含有する水溶液である請求項1〜3のいずれかに記載の無電解金めっき液。The electroless gold plating solution according to any one of claims 1 to 3, which is an aqueous solution containing a sulfite.
  5. 亜硫酸塩を0.001〜0.2mol/l含有する水溶液である請求項4に記載の無電解金めっき液。The electroless gold plating solution according to claim 4, which is an aqueous solution containing 0.001 to 0.2 mol / l of sulfite.
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Publication number Priority date Publication date Assignee Title
US9611550B2 (en) 2012-12-26 2017-04-04 Rohm And Haas Electronic Materials Llc Formaldehyde free electroless copper plating compositions and methods

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JP4521228B2 (en) 2003-07-28 2010-08-11 寛二 増井 Gold plating method by light deposition and gold plating film forming apparatus
JP5526459B2 (en) * 2006-12-06 2014-06-18 上村工業株式会社 Electroless gold plating bath and electroless gold plating method
JP5526458B2 (en) * 2006-12-06 2014-06-18 上村工業株式会社 Electroless gold plating bath and electroless gold plating method
JP4941650B2 (en) * 2007-01-11 2012-05-30 上村工業株式会社 Plating ability maintenance management method of electroless gold plating bath
JP5526440B2 (en) * 2007-01-17 2014-06-18 奥野製薬工業株式会社 Printed wiring board formed using reduced deposition type electroless gold plating solution for palladium film
JP5013077B2 (en) * 2007-04-16 2012-08-29 上村工業株式会社 Electroless gold plating method and electronic component

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JP2000012015A (en) * 1998-06-10 2000-01-14 Jurgen Otto Besenhard Nonaqueous secondary battery
JP2000087250A (en) * 1998-09-10 2000-03-28 Hitachi Chem Co Ltd Electroless gold plating liquid
JP2000144441A (en) * 1998-11-05 2000-05-26 Nippon Riironaaru Kk Electroless gold plating method and electroless gold plating solution used therefor

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JPH0533148A (en) * 1991-02-22 1993-02-09 Okuno Seiyaku Kogyo Kk Electroless gold plating method
JP2000012015A (en) * 1998-06-10 2000-01-14 Jurgen Otto Besenhard Nonaqueous secondary battery
JP2000087250A (en) * 1998-09-10 2000-03-28 Hitachi Chem Co Ltd Electroless gold plating liquid
JP2000144441A (en) * 1998-11-05 2000-05-26 Nippon Riironaaru Kk Electroless gold plating method and electroless gold plating solution used therefor

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9611550B2 (en) 2012-12-26 2017-04-04 Rohm And Haas Electronic Materials Llc Formaldehyde free electroless copper plating compositions and methods
US9809883B2 (en) 2012-12-26 2017-11-07 Rohm And Haas Electronic Materials Llc Formaldehyde free electroless copper plating compositions and methods

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