JP5526462B2 - Electroless gold plating solution and electroless gold plating method - Google Patents
Electroless gold plating solution and electroless gold plating method Download PDFInfo
- Publication number
- JP5526462B2 JP5526462B2 JP2007109773A JP2007109773A JP5526462B2 JP 5526462 B2 JP5526462 B2 JP 5526462B2 JP 2007109773 A JP2007109773 A JP 2007109773A JP 2007109773 A JP2007109773 A JP 2007109773A JP 5526462 B2 JP5526462 B2 JP 5526462B2
- Authority
- JP
- Japan
- Prior art keywords
- plating solution
- gold plating
- electroless gold
- polyethylene glycol
- salt
- 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
Links
- 238000007747 plating Methods 0.000 title claims description 303
- 239000010931 gold Substances 0.000 title claims description 208
- 229910052737 gold Inorganic materials 0.000 title claims description 205
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 title claims description 204
- 238000000034 method Methods 0.000 title claims description 30
- 239000002202 Polyethylene glycol Chemical class 0.000 claims description 70
- 229920001223 polyethylene glycol Chemical class 0.000 claims description 70
- 150000003839 salts Chemical class 0.000 claims description 45
- 239000003638 chemical reducing agent Substances 0.000 claims description 44
- 150000001875 compounds Chemical class 0.000 claims description 40
- 229910001385 heavy metal Inorganic materials 0.000 claims description 35
- 239000003795 chemical substances by application Substances 0.000 claims description 20
- 239000008139 complexing agent Substances 0.000 claims description 16
- SDKPSXWGRWWLKR-UHFFFAOYSA-M sodium;9,10-dioxoanthracene-1-sulfonate Chemical compound [Na+].O=C1C2=CC=CC=C2C(=O)C2=C1C=CC=C2S(=O)(=O)[O-] SDKPSXWGRWWLKR-UHFFFAOYSA-M 0.000 claims description 12
- 125000000217 alkyl group Chemical group 0.000 claims description 11
- 229910021645 metal ion Inorganic materials 0.000 claims description 11
- 125000003277 amino group Chemical group 0.000 claims description 9
- 125000002887 hydroxy group Chemical group [H]O* 0.000 claims description 9
- 150000003475 thallium Chemical class 0.000 claims description 8
- XTHFKEDIFFGKHM-UHFFFAOYSA-N Dimethoxyethane Chemical compound COCCOC XTHFKEDIFFGKHM-UHFFFAOYSA-N 0.000 claims description 7
- 125000004435 hydrogen atom Chemical group [H]* 0.000 claims description 6
- 125000004432 carbon atom Chemical group C* 0.000 claims description 5
- 239000006174 pH buffer Substances 0.000 claims description 5
- XNWFRZJHXBZDAG-UHFFFAOYSA-N 2-METHOXYETHANOL Chemical compound COCCO XNWFRZJHXBZDAG-UHFFFAOYSA-N 0.000 claims description 4
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- AOBIOSPNXBMOAT-UHFFFAOYSA-N 2-[2-(oxiran-2-ylmethoxy)ethoxymethyl]oxirane Chemical compound C1OC1COCCOCC1CO1 AOBIOSPNXBMOAT-UHFFFAOYSA-N 0.000 claims description 3
- MUHFRORXWCGZGE-KTKRTIGZSA-N 2-hydroxyethyl (z)-octadec-9-enoate Chemical compound CCCCCCCC\C=C/CCCCCCCC(=O)OCCO MUHFRORXWCGZGE-KTKRTIGZSA-N 0.000 claims description 3
- RFVNOJDQRGSOEL-UHFFFAOYSA-N 2-hydroxyethyl octadecanoate Chemical compound CCCCCCCCCCCCCCCCCC(=O)OCCO RFVNOJDQRGSOEL-UHFFFAOYSA-N 0.000 claims description 3
- ADPOBOOHCUVXGO-UHFFFAOYSA-H dioxido-oxo-sulfanylidene-$l^{6}-sulfane;gold(3+) Chemical compound [Au+3].[Au+3].[O-]S([O-])(=O)=S.[O-]S([O-])(=O)=S.[O-]S([O-])(=O)=S ADPOBOOHCUVXGO-UHFFFAOYSA-H 0.000 claims description 3
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- JOOSFXXMIOXKAZ-UHFFFAOYSA-H [Au+3].[Au+3].[O-]C(=O)CC(S)C([O-])=O.[O-]C(=O)CC(S)C([O-])=O.[O-]C(=O)CC(S)C([O-])=O Chemical compound [Au+3].[Au+3].[O-]C(=O)CC(S)C([O-])=O.[O-]C(=O)CC(S)C([O-])=O.[O-]C(=O)CC(S)C([O-])=O JOOSFXXMIOXKAZ-UHFFFAOYSA-H 0.000 claims description 2
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- 239000000203 mixture Substances 0.000 description 25
- UMGDCJDMYOKAJW-UHFFFAOYSA-N thiourea Chemical compound NC(N)=S UMGDCJDMYOKAJW-UHFFFAOYSA-N 0.000 description 23
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- 238000001953 recrystallisation Methods 0.000 description 3
- YXIWHUQXZSMYRE-UHFFFAOYSA-N 1,3-benzothiazole-2-thiol Chemical compound C1=CC=C2SC(S)=NC2=C1 YXIWHUQXZSMYRE-UHFFFAOYSA-N 0.000 description 2
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- 235000021317 phosphate Nutrition 0.000 description 1
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- 229920000573 polyethylene Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- NNFCIKHAZHQZJG-UHFFFAOYSA-N potassium cyanide Chemical compound [K+].N#[C-] NNFCIKHAZHQZJG-UHFFFAOYSA-N 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 229940079877 pyrogallol Drugs 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 235000010378 sodium ascorbate Nutrition 0.000 description 1
- PPASLZSBLFJQEF-RKJRWTFHSA-M sodium ascorbate Substances [Na+].OC[C@@H](O)[C@H]1OC(=O)C(O)=C1[O-] PPASLZSBLFJQEF-RKJRWTFHSA-M 0.000 description 1
- 229960005055 sodium ascorbate Drugs 0.000 description 1
- PPASLZSBLFJQEF-RXSVEWSESA-M sodium-L-ascorbate Chemical compound [Na+].OC[C@H](O)[C@H]1OC(=O)C(O)=C1[O-] PPASLZSBLFJQEF-RXSVEWSESA-M 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-L sulfite Chemical class [O-]S([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-L 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- XHGGEBRKUWZHEK-UHFFFAOYSA-L tellurate Chemical compound [O-][Te]([O-])(=O)=O XHGGEBRKUWZHEK-UHFFFAOYSA-L 0.000 description 1
- SITVSCPRJNYAGV-UHFFFAOYSA-L tellurite Chemical compound [O-][Te]([O-])=O SITVSCPRJNYAGV-UHFFFAOYSA-L 0.000 description 1
- BKVIYDNLLOSFOA-UHFFFAOYSA-N thallium Chemical compound [Tl] BKVIYDNLLOSFOA-UHFFFAOYSA-N 0.000 description 1
- GBECUEIQVRDUKB-UHFFFAOYSA-M thallium monochloride Chemical class [Tl]Cl GBECUEIQVRDUKB-UHFFFAOYSA-M 0.000 description 1
- YTQVHRVITVLIRD-UHFFFAOYSA-L thallium sulfate Chemical class [Tl+].[Tl+].[O-]S([O-])(=O)=O YTQVHRVITVLIRD-UHFFFAOYSA-L 0.000 description 1
- 150000004764 thiosulfuric acid derivatives Chemical class 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- CENHPXAQKISCGD-UHFFFAOYSA-N trioxathietane 4,4-dioxide Chemical compound O=S1(=O)OOO1 CENHPXAQKISCGD-UHFFFAOYSA-N 0.000 description 1
Description
本発明は無電解金めっき液及び無電解金めっき方法に関する。 The present invention relates to an electroless gold plating solution and an electroless gold plating method.
従来の高温、高アルカリ性無電解金めっき液に代わる、中性及び低温で使用可能な無電解金めっき液が近年開発されている。かかる無電解金めっき液は、めっき可能なレジストや電子部品の使用範囲を広げることを目的として開発されたものである。ところが、既に実用化されている無電解金めっき液ではめっき液の安定性が不十分であり、めっき付き回り性も十分とはいえない。 In recent years, electroless gold plating solutions that can be used at neutral and low temperatures have been developed in place of conventional high-temperature, highly alkaline electroless gold plating solutions. Such an electroless gold plating solution has been developed for the purpose of expanding the use range of resists and electronic components that can be plated. However, the electroless gold plating solution that has already been put to practical use has insufficient stability of the plating solution, and it cannot be said that the revolving property with plating is sufficient.
このような安定性低下の原因としては、（１）無電解金めっき液自体の安定性が不十分であること、及び（２）めっき処理による不純物金属混入により液安定性が低下すること、の２つが想定されている。そこで、これらの観点からめっき液を改良する試みがなされている。 The reasons for such a decrease in stability are (1) the stability of the electroless gold plating solution itself is insufficient, and (2) the solution stability is reduced due to impurity metal contamination by the plating process. Two are envisioned. Therefore, attempts have been made to improve the plating solution from these viewpoints.
例えば、特許文献１には、シアン化合物を使用することなく、中性付近での無電解金めっきを実現するために、還元剤としてアスコルビン酸を使用することが開示されている。また、特許文献２、３には、めっき処理による不純物金属混入の抑制や液安定性向上のために、無電解金めっき液にメルカプトベンゾチアゾ−ル系化合物の金属隠蔽剤を添加する手法が提案されている。 For example, Patent Document 1 discloses that ascorbic acid is used as a reducing agent in order to realize electroless gold plating near neutrality without using a cyanide compound. Patent Documents 2 and 3 disclose a technique of adding a metal concealing agent of a mercaptobenzothiazol compound to an electroless gold plating solution in order to suppress impurity metal contamination by plating treatment and improve the liquid stability. Proposed.
特許文献４には、無電解金めっき液の還元剤としてヒドラジン化合物を使用することが記載されている。このめっき液によると、上記のアスコルビン酸を使用しためっき液と比較して、低濃度で実用的な析出速度が得られるとされている。また、特許文献５には、ベンゾトリアゾール系化合物の金属隠蔽剤を無電解金めっき液に添加する改良が提案されている。これにより、めっき処理による不純物金属混入の抑制や液安定性の向上が可能となるとされている。また、特許文献５に記載の金属隠蔽剤は、上記メルカプトベンゾチアゾール系隠蔽剤よりも無電解金めっき液における使用可能な濃度範囲が広く実用的であるとされている。 Patent Document 4 describes the use of a hydrazine compound as a reducing agent for an electroless gold plating solution. According to this plating solution, it is said that a practical deposition rate can be obtained at a low concentration as compared with the plating solution using the above ascorbic acid. Patent Document 5 proposes an improvement in which a metal masking agent of a benzotriazole compound is added to an electroless gold plating solution. Thereby, it is said that impurity metal contamination by plating treatment and improvement of liquid stability can be achieved. Further, the metal masking agent described in Patent Document 5 has a wider usable range in the electroless gold plating solution than the mercaptobenzothiazole masking agent and is practical.
一方、特許文献６には、還元剤にチオ尿素又はフェニル系化合物を使用した無電解金めっき液が開示されている。この特許文献６には、チオ尿素が低濃度で金を還元できる旨、示されている。また、特許文献７には、無電解金めっき浴の還元剤にチオ尿素化合物及びフェニル化合物の両方を使用する方法が記載されている。このめっき液を使用すれば、チオ尿素の副生成物がフェニル化合物系還元剤で還元されるため、液安定性が向上するとされている。更に、特許文献８には、無電解金めっき液にベンゾトリアゾール系化合物の金属隠蔽剤を添加することが提案されている。この手法によれば、上記めっき液への不純物金属混入の抑制や液安定性向上を図ることができるとされている。
しかしながら、上記従来の無電解金めっき液には以下のような問題が存在する。特許文献１に記載されたアスコルビン酸による還元は、還元効率が低く、実用析出速度を確保するために、アスコルビン酸ナトリウムを高い濃度になるように配合する。そのため、無電解金めっき液の安定性が不十分となる。また、特許文献２、３で提案されたメルカプトベンゾチアゾ−ル系化合物の金属隠蔽剤は、無電解金めっき液における使用管理範囲が非常に狭く（０．１〜５ｐｐｍ）、作業効率が低い。この金属隠蔽剤の無電解金めっき液への添加量が多くなると、析出速度が極端に低くなり、めっき付き回り不良が発生するという問題がある。 However, the conventional electroless gold plating solution has the following problems. The reduction with ascorbic acid described in Patent Document 1 has low reduction efficiency, and sodium ascorbate is blended at a high concentration in order to ensure a practical precipitation rate. Therefore, the stability of the electroless gold plating solution is insufficient. Further, the metal concealing agent of mercaptobenzothiazol compound proposed in Patent Documents 2 and 3 has a very narrow use management range in an electroless gold plating solution (0.1 to 5 ppm) and low working efficiency. . When the amount of the metal masking agent added to the electroless gold plating solution increases, there is a problem that the deposition rate becomes extremely low, resulting in defective plating.
一方、特許文献４に記載のように還元剤としてヒドラジン化合物を使用すると、ヒドラジン化合物自体の安定性が低く、無電解金めっき液の安定性が確保できないという問題がある。また、ベンゾトリアゾール系化合物の金属隠蔽剤を添加する改良が試みられた特許文献５に記載の無電解金めっき液は、上述のように、還元剤であるヒドラジン自体の安定性が低いため、実用には不十分である。 On the other hand, when a hydrazine compound is used as a reducing agent as described in Patent Document 4, there is a problem that the stability of the hydrazine compound itself is low and the stability of the electroless gold plating solution cannot be ensured. Further, as described above, the electroless gold plating solution described in Patent Document 5, which has been attempted to improve by adding a metal masking agent of a benzotriazole-based compound, has a low stability of hydrazine itself as a reducing agent. Is not enough.
さらに、特許文献６、７に開示された無電解金めっき液は、チオ尿素の副生成物をフェニル化合物系還元剤で還元することで、液安定性の向上を図ったものであるが、結果的には、チオ尿素の副生成物を完全に元の還元剤に戻すことが困難である。このため、残留副生成物がめっき付き回り不良や不安定化の原因となり、十分なめっき液の安定性を保持できない場合がある。また、フェニル化合物系還元剤は、中性（ｐＨ７〜７．５）において還元力が小さいため実用的な析出速度が得られ難い。さらにフェニル化合物系還元剤は、弱アルカリ性領域（ｐＨ９．０付近）で、めっき浴による皮膜外観が悪い上に、めっき処理中に液が分解する問題がある。そして、特許文献８で提案されたベンゾトリアゾール系化合物の金属隠蔽剤を添加した無電解金めっき液であっても、実用面において安定性にまだ改善の余地があり、中性且つ低温でもより優れた析出速度を有するめっき液が求められている。 Furthermore, the electroless gold plating solutions disclosed in Patent Documents 6 and 7 are intended to improve the liquid stability by reducing the by-product of thiourea with a phenyl compound-based reducing agent. Specifically, it is difficult to completely return the thiourea by-product to the original reducing agent. For this reason, the residual by-product may cause defective plating or instability, and may not maintain sufficient plating solution stability. In addition, since the reducing power of the phenyl compound-based reducing agent is neutral (pH 7 to 7.5), a practical precipitation rate is difficult to obtain. Furthermore, the phenyl compound-based reducing agent has a weak alkaline region (around pH 9.0) and has a problem that the film appearance by the plating bath is poor and the solution decomposes during the plating process. And even if it is the electroless gold plating solution which added the metal masking agent of the benzotriazole type compound proposed by patent document 8, there is still room for improvement in stability in practice, and it is more excellent at neutral and low temperature. There is a need for a plating solution having a high deposition rate.
本発明は上記事情にかんがみてなされたものであり、液温６０〜８０℃程度の低温であっても十分な析出速度を発揮し、皮膜外観が良好であり、且つ、めっき液の安定性が特に優れた無電解金めっき液、及びこれを用いた無電解金めっき方法を提供することを目的とする。 The present invention has been made in view of the above circumstances, exhibits a sufficient deposition rate even at a liquid temperature of about 60 to 80 ° C., has a good film appearance, and has stability of the plating solution. An object of the present invention is to provide a particularly excellent electroless gold plating solution and an electroless gold plating method using the same.
本発明者らは、更なるめっき液の特性向上を目指して検討した結果、フェニル化合物系還元剤を含む無電解金めっき液に重金属塩を添加することにより、金めっきの析出速度が向上し、また皮膜外観を大幅に改善できるという知見を得た。しかしながら、本発明者らは、重金属塩を添加することによって、めっき液の安定性が若干低下することも同時に見出した。 As a result of studies aimed at further improving the properties of the plating solution, the inventors have improved the deposition rate of gold plating by adding a heavy metal salt to an electroless gold plating solution containing a phenyl compound-based reducing agent, Moreover, the knowledge that a film | membrane external appearance could be improved significantly was acquired. However, the present inventors have also found that the stability of the plating solution is slightly reduced by adding a heavy metal salt.
そして、更に鋭意研究を重ねた結果、特定の還元剤、重金属塩及び安定剤を組み合わせた無電解金めっき液により、上記目的が達成可能であることを見出し、本発明を完成するに至った。 As a result of further earnest research, the inventors have found that the above object can be achieved by an electroless gold plating solution in which a specific reducing agent, heavy metal salt and stabilizer are combined, and have completed the present invention.
本発明は、金塩と、下記一般式（１）で表される還元剤と、重金属塩と、ポリエチレングリコール系化合物とを含む無電解金めっき液を提供する。
ここで、式（１）中、Ｒ１は水酸基又はアミノ基を示し、Ｒ２、Ｒ３及びＲ４はそれぞれ独立に水酸基、アミノ基、水素原子又はアルキル基を示す。
The present invention provides an electroless gold plating solution containing a gold salt, a reducing agent represented by the following general formula (1), a heavy metal salt, and a polyethylene glycol compound.
Here, in Formula (1), R 1 represents a hydroxyl group or an amino group, and R 2 , R 3, and R 4 each independently represent a hydroxyl group, an amino group, a hydrogen atom, or an alkyl group.
本発明の無電解金めっき液は、金塩と組み合わせる還元剤として上記一般式（１）で表される化合物を採用し、析出速度促進剤として重金属塩を併用し、更に安定剤としてポリエチレングリコール系化合物を含んでいる。これにより、本発明の無電解金めっき液は、低温であっても十分な析出速度を発揮し、皮膜外観が良好であり、且つ、めっき液の安定性が特に優れるものとなる。 The electroless gold plating solution of the present invention employs the compound represented by the general formula (1) as a reducing agent combined with a gold salt, uses a heavy metal salt in combination as a deposition rate accelerator, and further uses a polyethylene glycol-based stabilizer as a stabilizer. Contains compounds. As a result, the electroless gold plating solution of the present invention exhibits a sufficient deposition rate even at a low temperature, has a good coating appearance, and has a particularly excellent stability of the plating solution.
また、上記一般式（１）で表される還元剤は、下記一般式（２）で表される還元剤を含むことが好ましい。かかる化学構造の還元剤を使用することにより、金の析出速度及びめっき液の安定性がより優れるものとなる。
ここで、式（２）中、Ｒ２１は水酸基又はアミノ基を示し、Ｒ２２は水素原子又は炭素数１〜４のアルキル基を示す。
Moreover, it is preferable that the reducing agent represented by the said General formula (1) contains the reducing agent represented by following General formula (2). By using a reducing agent having such a chemical structure, the deposition rate of gold and the stability of the plating solution are further improved.
Here, in Formula (2), R 21 represents a hydroxyl group or an amino group, and R 22 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
本発明における重金属塩は、タリウム塩、鉛塩、砒素塩、アンチモン塩、テルル塩及びビスマス塩からなる群より選ばれる少なくとも１種の重金属塩を含むことが好ましく、タリウム塩であることが特に好ましい。重金属塩として上記化合物を用いると、金の析出速度を更に速めることができる。 The heavy metal salt in the present invention preferably contains at least one heavy metal salt selected from the group consisting of thallium salt, lead salt, arsenic salt, antimony salt, tellurium salt and bismuth salt, and particularly preferably thallium salt. . When the above compound is used as the heavy metal salt, the deposition rate of gold can be further increased.
また、本発明におけるポリエチレングリコール系化合物は、ポリエチレングリコール、ポリエチレングリコールモノオレエート、ポリエチレングリコールモノステアレート、ポリエチレングリコールモノメチルエーテル、ポリエチレングリコールモノラウレート、ポリエチレングリコールジメチルエーテル、及びポリエチレングリコールジグリシジルエーテルからなる群より選ばれる少なくとも１種のポリエチレングリコール系化合物を含むことが好ましい。ポリエチレングリコール系化合物がかかる化合物である場合、めっき液の安定性が特に向上する。 The polyethylene glycol compound in the present invention is a group consisting of polyethylene glycol, polyethylene glycol monooleate, polyethylene glycol monostearate, polyethylene glycol monomethyl ether, polyethylene glycol monolaurate, polyethylene glycol dimethyl ether, and polyethylene glycol diglycidyl ether. It is preferable to contain at least one polyethylene glycol compound selected from the above. When the polyethylene glycol compound is such a compound, the stability of the plating solution is particularly improved.
本発明の無電解金めっき液は、錯化剤を更に含むことが好ましく、ｐＨ緩衝剤を更に含むことが好ましく、金属イオン隠蔽剤を更に含むことが好ましい。無電解金めっき液がこのような成分を含有することにより、めっき液の安定性が更に優れるようになる。 The electroless gold plating solution of the present invention preferably further contains a complexing agent, preferably further contains a pH buffer, and preferably further contains a metal ion concealing agent. When the electroless gold plating solution contains such a component, the stability of the plating solution is further improved.
本発明の無電解金めっき液はｐＨが５〜１０であることが好ましい。無電解金めっき液のｐHが上記範囲である場合には、様々な被めっき体に対して中性且つ低温での無電解金めっきが可能となる。したがって、めっき可能なレジストや電子部品の使用範囲を広げることが可能となる。 The electroless gold plating solution of the present invention preferably has a pH of 5-10. When the pH of the electroless gold plating solution is in the above range, it is possible to perform electroless gold plating at various temperatures and at a low temperature on various objects to be plated. Therefore, it is possible to expand the use range of resists and electronic components that can be plated.
本発明は更に、上述の無電解金めっき液に浸漬した被めっき体の表面に金皮膜を形成させる工程を有する無電解金めっき方法を提供するものである。本発明の無電解金めっき方法によって、液温６０〜８０℃程度の低温であっても十分な析出速度を発揮し、且つ皮膜外観よくめっきを行うことが可能となる。 The present invention further provides an electroless gold plating method including a step of forming a gold film on the surface of an object to be plated immersed in the above electroless gold plating solution. By the electroless gold plating method of the present invention, it is possible to perform a sufficient deposition rate and perform plating with a good film appearance even at a liquid temperature of about 60 to 80 ° C.
本発明の無電解金めっき液及び無電解金めっき方法によれば、液温６０〜８０℃程度の低温であっても十分な析出速度を発揮し、皮膜外観が良好であり、且つ、めっき液の安定性が特に優れた無電解金めっき液を提供することが可能となる。 According to the electroless gold plating solution and the electroless gold plating method of the present invention, a sufficient deposition rate is exhibited even at a low temperature of about 60 to 80 ° C., the film appearance is good, and the plating solution It is possible to provide an electroless gold plating solution with particularly excellent stability.
以下、本発明の好適な実施形態について詳細に説明する。本発明の無電解金めっき液は、金塩、還元剤、重金属塩、及びポリエチレングリコール系化合物を含有するものである。まず、これらの成分について詳細に説明する。 Hereinafter, preferred embodiments of the present invention will be described in detail. The electroless gold plating solution of the present invention contains a gold salt, a reducing agent, a heavy metal salt, and a polyethylene glycol compound. First, these components will be described in detail.
（金塩）
本発明の無電解金めっき液に使用可能な金塩は特に限定されない。金塩はシアン系金塩と非シアン金塩とに区別される。シアン系金塩としては、例えば、シアン化第一金カリウム及びシアン化第二金カリウムが例示できる。非シアン系金塩としては、例えば、塩化金酸塩、亜硫酸金塩、チオ硫酸金塩、及びチオリンゴ酸金塩が挙げられる。これらの金塩は１種のみを用いてもよく、２種以上を組み合わせて用いてもよい。
(Gold salt)
The gold salt that can be used in the electroless gold plating solution of the present invention is not particularly limited. Gold salts are classified into cyan and non-cyanide gold salts. Examples of the cyan gold salt include potassium primary cyanide and potassium potassium cyanide. Examples of non-cyanide gold salts include chloroaurate, gold sulfite, gold thiosulfate, and gold thiomalate. These gold salts may be used alone or in combination of two or more.
上記金塩としては、非シアン系金塩である亜硫酸金塩及びチオ硫酸金塩が好ましい。非シアン系金塩は、シアン系金塩と比較して、概して毒性が低いため、取り扱いがより容易となる。 As the gold salt, gold sulfite and gold thiosulfate which are non-cyanide gold salts are preferable. Non-cyanide gold salts are easier to handle because they are generally less toxic than cyanide gold salts.
また、金塩の含有量は、無電解金めっき液中の金濃度が１〜１０ｇ／Ｌとなるように調整されることが好ましい。金濃度が１ｇ／Ｌ未満である場合は、金の析出反応速度が低下し金が析出し難くなる傾向にある。また、金濃度が１０ｇ／Ｌを超える場合は、無電解金めっき液の安定性が低下すると共に、金使用量の増加につながるため、経済的に好ましくない。更に、同様の観点から、金塩の含有量は、金濃度が２〜５ｇ／Ｌの範囲となるように調整されることがより好ましい。 The content of the gold salt is preferably adjusted so that the gold concentration in the electroless gold plating solution is 1 to 10 g / L. When the gold concentration is less than 1 g / L, the gold precipitation reaction rate tends to be low, and gold tends to be difficult to precipitate. On the other hand, when the gold concentration exceeds 10 g / L, the stability of the electroless gold plating solution is lowered and the amount of gold used is increased, which is not economically preferable. Furthermore, from the same viewpoint, the content of the gold salt is more preferably adjusted so that the gold concentration is in the range of 2 to 5 g / L.
（還元剤）
本発明の無電解金めっき液において用いる還元剤は、下記一般式（１）で表される化合物（以下「化合物Ｉ」という。）である。
(Reducing agent)
The reducing agent used in the electroless gold plating solution of the present invention is a compound represented by the following general formula (1) (hereinafter referred to as “Compound I”).
化合物Ｉにおいて、Ｒ１は水酸基又はアミノ基、Ｒ２、Ｒ３及びＲ４はそれぞれ独立に水酸基、アミノ基、水素原子又はアルキル基を示す。アルキル基としては直鎖又は分岐状の炭素数１〜６のアルキル基が好ましく、直鎖又は分岐状の炭素数１〜４のアルキル基がより好ましい。そのようなアルキル基としては、例えばメチル基、エチル基及びｔ−ブチル基が挙げられる。 In Compound I, R 1 represents a hydroxyl group or an amino group, and R 2 , R 3 and R 4 each independently represent a hydroxyl group, an amino group, a hydrogen atom or an alkyl group. As the alkyl group, a linear or branched alkyl group having 1 to 6 carbon atoms is preferable, and a linear or branched alkyl group having 1 to 4 carbon atoms is more preferable. Examples of such an alkyl group include a methyl group, an ethyl group, and a t-butyl group.
化合物Ｉの具体例としては、例えば、フェノール、ｏ−クレゾール、ｐ−クレゾール、ｏ−エチルフェノール、ｐ−エチルフェノール、ｔ−ブチルフェノール、ｏ−アミノフェノール、ｐ−アミノフェノール、ヒドロキノン、カテコール、ピロガロール、メチルヒドロキノン、アニリン、ｏ−フェニレンジアミン、ｐ−フェニレンジアミン、ｏ−トルイジン、ｐ−トルイジン、ｏ−エチルアニリン及びｐ−エチルアニリンが挙げられる。これらは１種を単独で又は２種以上を組み合わせて用いられる。 Specific examples of compound I include, for example, phenol, o-cresol, p-cresol, o-ethylphenol, p-ethylphenol, t-butylphenol, o-aminophenol, p-aminophenol, hydroquinone, catechol, pyrogallol, Mention may be made of methylhydroquinone, aniline, o-phenylenediamine, p-phenylenediamine, o-toluidine, p-toluidine, o-ethylaniline and p-ethylaniline. These are used singly or in combination of two or more.
めっき液の安定性及び金の析出速度の観点からは、化合物Ｉで表される化合物は、下記一般式（２）で表される化合物（以下「化合物ＩＩ」という）を含むことが好ましい。 From the viewpoint of the stability of the plating solution and the deposition rate of gold, the compound represented by Compound I preferably contains a compound represented by the following general formula (2) (hereinafter referred to as “Compound II”).
化合物ＩＩにおいて、２つのＲ２１は水酸基又はアミノ基を示し、Ｒ２２は水素原子又は炭素数１〜４のアルキル基を示す。このアルキル基としては、例えばメチル基、エチル基及びｔ−ブチル基が挙げられる。化合物ＩＩの具体例としては、ｐ−フェニレンジアミン、メチルヒドロキノン及びヒドロキノンが挙げられる。これらは１種を単独で又は２種以上を組み合わせて用いられる。 In Compound II, two R 21 represent a hydroxyl group or an amino group, and R 22 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, and a t-butyl group. Specific examples of compound II include p-phenylenediamine, methylhydroquinone and hydroquinone. These are used singly or in combination of two or more.
上記還元剤の含有量は、無電解金めっき液の全容量を基準として０．５〜５０ｇ／Ｌであると好ましい。還元剤の含有量が０．５ｇ／Ｌ未満であると、実用的な析出速度を得るのが困難となる傾向にある。また、還元剤の含有量が５０ｇ／Ｌを超えると、めっき液の安定性は低下する傾向にある。同様の観点から、還元剤の含有量は、２〜１０ｇ／Ｌであることがより好ましく、２〜５ｇ／Ｌであることが特に好ましい。 The content of the reducing agent is preferably 0.5 to 50 g / L based on the total capacity of the electroless gold plating solution. When the content of the reducing agent is less than 0.5 g / L, it tends to be difficult to obtain a practical deposition rate. Moreover, when content of a reducing agent exceeds 50 g / L, it exists in the tendency for stability of a plating solution to fall. From the same viewpoint, the content of the reducing agent is more preferably 2 to 10 g / L, and particularly preferably 2 to 5 g / L.
（重金属塩）
更に、本発明の無電解金めっき液は重金属塩を含む。析出速度を更に促進し、皮膜外観を一層改善する観点から、重金属塩は、タリウム塩、鉛塩、砒素塩、アンチモン塩、テルル塩及びビスマス塩からなる群より選ばれる少なくとも１種を含むことが好ましい。
(Heavy metal salt)
Furthermore, the electroless gold plating solution of the present invention contains a heavy metal salt. From the viewpoint of further promoting the deposition rate and further improving the film appearance, the heavy metal salt may contain at least one selected from the group consisting of thallium salt, lead salt, arsenic salt, antimony salt, tellurium salt and bismuth salt. preferable.
ここで、タリウム塩としては、例えば、硫酸タリウム塩、塩化タリウム塩、酸化タリウム塩及び硝酸タリウム塩等の無機化合物塩、並びに、マロン酸二タリウム塩等の有機錯体塩が挙げられる。また、鉛塩としては、硫酸鉛塩及び硝酸鉛塩等の無機化合物塩、並びに酢酸鉛等の有機錯体塩が挙げられる。 Here, examples of the thallium salt include inorganic compound salts such as thallium sulfate salt, thallium chloride salt, thallium oxide salt and thallium nitrate salt, and organic complex salts such as malaric acid dithallium salt. Examples of the lead salt include inorganic compound salts such as lead sulfate salt and lead nitrate salt, and organic complex salts such as lead acetate.
砒素塩としては、亜砒素塩、砒酸塩及び三酸化砒素等の無機化合物塩並びに有機錯体塩が挙げられる。アンチモン塩としては、酒石酸アンチモニル塩等の有機錯体塩、並びに塩化アンチモン塩類、オキシ硫酸アンチモン塩及び三酸化アンチモン等の無機化合物塩が挙げられる。 Examples of arsenic salts include inorganic compound salts such as arsenite, arsenate, and arsenic trioxide, and organic complex salts. Examples of the antimony salt include organic complex salts such as antimony tartrate, and inorganic compound salts such as antimony chloride salts, antimony oxysulfate and antimony trioxide.
テルル塩としては、亜テルル酸塩及びテルル酸塩等の無機化合物塩並びに有機錯体塩が挙げられる。また、ビスマス塩としては、硫酸ビスマス（ＩＩＩ）、塩化ビスマス（ＩＩＩ）及び硝酸ビスマス（ＩＩＩ）等の無機化合物塩、並びにシュウ酸ビスマス（ＩＩＩ）などの有機錯体塩が挙げられる。 Examples of tellurium salts include inorganic compound salts such as tellurite and tellurate, and organic complex salts. Examples of the bismuth salt include inorganic compound salts such as bismuth sulfate (III), bismuth chloride (III) and bismuth nitrate (III), and organic complex salts such as bismuth oxalate (III).
本発明の無電解金めっき液に用いる重金属塩は、タリウム塩（好ましくはタリウム無機化合物又はタリウム有機錯体塩）を用いることが好ましい。重金属塩として、タリウム塩を用いることにより、金の析出速度を更に速めることができる。 The heavy metal salt used in the electroless gold plating solution of the present invention is preferably a thallium salt (preferably a thallium inorganic compound or a thallium organic complex salt). By using a thallium salt as the heavy metal salt, the deposition rate of gold can be further increased.
上述した重金属塩は、１種を単独で又は２種以上を組み合わせて用いられる。重金属塩の含有量は、質量基準で無電解金めっき液の全量に対して１〜１００ｐｐｍであると好ましく、１〜１０ｐｐｍであるとより好ましい。重金属塩の含有量が１ｐｐｍ未満であると、析出速度の向上効果が低下する傾向がある。また、重金属塩の含有量が１００ｐｐｍを超えると、めっき液安定性が悪くなる傾向がある。 The above-mentioned heavy metal salts are used singly or in combination of two or more. The content of the heavy metal salt is preferably 1 to 100 ppm and more preferably 1 to 10 ppm with respect to the total amount of the electroless gold plating solution on a mass basis. There exists a tendency for the improvement effect of precipitation rate to fall that content of heavy metal salt is less than 1 ppm. Moreover, when content of heavy metal salt exceeds 100 ppm, there exists a tendency for plating solution stability to worsen.
（ポリエチレングリコール系化合物）
本発明の無電解金めっき液は、ポリエチレングリコール系化合物を更に含む。フェニル化合物系還元剤及び重金属塩を含む無電解金めっき液中に、ポリエチレングリコール系化合物を更に含有させた無電解金めっき液は、液温６０〜８０℃程度の低温であっても十分な析出速度が得られ、皮膜外観も良好である上、めっき液の安定性が特に優れるようになる。
(Polyethylene glycol compounds)
The electroless gold plating solution of the present invention further contains a polyethylene glycol compound. An electroless gold plating solution containing a polyethylene glycol compound in an electroless gold plating solution containing a phenyl compound reducing agent and a heavy metal salt is sufficiently precipitated even at a low temperature of about 60 to 80 ° C. The speed is obtained, the film appearance is good, and the stability of the plating solution is particularly excellent.
上述のポリエチレングリコール系化合物はエーテル型、エステル型、エーテル・エステル型等のいずれであってもよい。ポリエチレングリコール系化合物であれば、上述の一定の効果を得ることができる。特に有効なポリエチレングリコール系化合物としては、ポリエチレングリコール、ポリエチレングリコールモノオレエート、ポリエチレングリコールモノステアレート、ポリエチレングリコールモノメチルエーテル、ポリエチレングリコールモノラウレート、ポリエチレングリコールジメチルエーテル及びポリエチレングリコールジグリシジルエーテルが例示される。 The above-mentioned polyethylene glycol compounds may be any of ether type, ester type, ether / ester type and the like. If it is a polyethylene glycol-type compound, the above-mentioned fixed effect can be acquired. Particularly effective polyethylene glycol compounds include polyethylene glycol, polyethylene glycol monooleate, polyethylene glycol monostearate, polyethylene glycol monomethyl ether, polyethylene glycol monolaurate, polyethylene glycol dimethyl ether and polyethylene glycol diglycidyl ether.
本発明のポリエチレングリコール系化合物は、単独で用いてもよく、２種類以上を組み合わせてもよい。ポリエチレングリコール系化合物の重量平均分子量は、特に限定されないが、２０００以下の低分子量であることが好ましく、１０００以下の低分子量であることが更に好ましい。この重量平均分子量が２０００を超える場合、ポリエチレングリコール系化合物の含有量が少なくても析出速度が容易に低下する傾向にある。このため、管理範囲が狭くなり析出速度を安定に保つことが困難になる傾向にある。なお、本明細書において、重量平均分子量は、ゲルパーミエーションクロマトグラフィーにより測定されかつ標準ポリスチレンの検量線を使用して換算されたものである。 The polyethylene glycol compound of the present invention may be used alone or in combination of two or more. The weight average molecular weight of the polyethylene glycol compound is not particularly limited, but it is preferably a low molecular weight of 2000 or less, and more preferably 1000 or less. When this weight average molecular weight exceeds 2000, the precipitation rate tends to easily decrease even if the content of the polyethylene glycol compound is small. For this reason, the management range is narrowed, and it tends to be difficult to keep the deposition rate stable. In the present specification, the weight average molecular weight is measured by gel permeation chromatography and converted using a standard polystyrene calibration curve.
また、ポリエチレングリコール系化合物の含有量は、質量基準で無電解金めっき液の全量に対して１〜５００ｐｐｍであることが好ましく、１〜３０ｐｐｍであることがより好ましく、１〜１０ｐｐｍであることが特に好ましい。ポリエチレングリコール系化合物の含有量が１ｐｐｍ未満の場合には、無電解金めっき液の安定性向上効果が小さくなり、濃度管理が困難になる傾向にある。また、ポリエチレングリコール系化合物の含有量が１０ｐｐｍを超えると、析出速度が遅くなり、めっき付き回り不良の抑制効果が低下し、皮膜外観が良好ではなくなる傾向がある。 Further, the content of the polyethylene glycol compound is preferably 1 to 500 ppm, more preferably 1 to 30 ppm, and more preferably 1 to 10 ppm with respect to the total amount of the electroless gold plating solution on a mass basis. Particularly preferred. When the content of the polyethylene glycol compound is less than 1 ppm, the effect of improving the stability of the electroless gold plating solution tends to be small, and the concentration control tends to be difficult. Moreover, when content of a polyethyleneglycol type compound exceeds 10 ppm, there exists a tendency for the precipitation rate to become slow, the inhibitory effect of a plating periphery defect will fall, and a film | membrane external appearance will become favorable.
ポリエチレングリコール系化合物の重量平均分子量が２００以下の低分子量である場合、本発明による効果をより有効に発揮するために、その含有量は、無電解金めっき液の全質量を基準として５ｐｐｍ以上であることが好ましい。また、ポリエチレングリコール系化合物の重量平均分子量が１０００以上の高分子量である場合、その含有量は０．１〜１ｐｐｍ程度の少量であっても、本発明による効果を十分奏することができる。 When the weight average molecular weight of the polyethylene glycol-based compound is a low molecular weight of 200 or less, the content is 5 ppm or more based on the total mass of the electroless gold plating solution in order to more effectively exhibit the effects of the present invention. Preferably there is. Moreover, when the weight average molecular weight of a polyethyleneglycol type compound is 1000 or more high molecular weight, the effect by this invention can fully be show | played even if the content is a small amount about 0.1-1 ppm.
本発明の無電解金めっき液には、上述した金塩、還元剤、重金属塩及びポリエチレングリコール系化合物に加えて、錯化剤、ｐＨ緩衝剤及び金属イオン隠蔽剤からなる群より選ばれる少なくとも１種を含有することが好ましく、これらの全てを含有することがより好ましい。以下、これらの成分について説明する。 The electroless gold plating solution of the present invention includes at least one selected from the group consisting of a complexing agent, a pH buffering agent, and a metal ion concealing agent in addition to the above-described gold salt, reducing agent, heavy metal salt and polyethylene glycol compound. It is preferred to contain seeds, more preferably all of these. Hereinafter, these components will be described.
（錯化剤）
本発明の無電解金めっき液には、錯化剤を含有させることが好ましい。当該成分を含有させることにより、金イオン（Ａｕ＋）が安定的に錯体化されて、Ａｕ＋の不均化反応（３Ａｕ＋→Ａｕ３＋＋２Ａｕ）の発生を低下させ、液がより安定に保たれる。錯化剤は１種類のみを用いてもよく２種類以上を用いてもよい。好適な錯化剤としては、例えば、シアン化ナトリウム及びシアン化カリウム等のシアン系錯化剤、並びに、亜硫酸塩、チオ硫酸塩及びチオリンゴ酸塩等の非シアン系錯化剤が挙げられる。
(Complexing agent)
The electroless gold plating solution of the present invention preferably contains a complexing agent. By containing this component, gold ions (Au + ) are stably complexed, the generation of Au + disproportionation reaction (3Au + → Au 3+ + 2Au) is reduced, and the liquid is kept more stable. Be drunk. Only one type of complexing agent may be used, or two or more types may be used. Suitable complexing agents include, for example, cyanate complexing agents such as sodium cyanide and potassium cyanide, and non-cyanide complexing agents such as sulfite, thiosulfate and thiomalate.
安全性及び使い易さの観点から、上述の錯化剤のうち、亜硫酸塩又はチオ硫酸塩が特に好ましい。錯化剤の含有量は、無電解金めっき液の全容量を基準として１〜２００ｇ／Ｌであることが好ましい。錯化剤の含有量が１ｇ／Ｌ未満である場合、金錯化力が低下し、安定性が低下する傾向がある。錯化剤の含有量が２００ｇ／Ｌを超えると、めっき液の安定性は向上するが、液中で再結晶化が発生し、経済的に負担となる。同様の観点から、錯化剤の含有量は２０〜５０ｇ／Ｌとすることがより好ましい。 Of the above complexing agents, sulfites or thiosulfates are particularly preferred from the viewpoint of safety and ease of use. The content of the complexing agent is preferably 1 to 200 g / L based on the total capacity of the electroless gold plating solution. When the content of the complexing agent is less than 1 g / L, the gold complexing power tends to decrease and the stability tends to decrease. When the content of the complexing agent exceeds 200 g / L, the stability of the plating solution is improved, but recrystallization occurs in the solution, which is an economical burden. From the same viewpoint, the content of the complexing agent is more preferably 20 to 50 g / L.
（ｐＨ緩衝剤）
本発明の無電解金めっき液には、ｐＨ緩衝剤を含有させることが好ましい。ｐＨ緩衝剤を含有させることにより、析出速度を所望の値に調整すること、及びめっき液のｐＨを一定に保つことができる。ｐＨ緩衝剤は１種のみを用いてもよく、２種以上を組み合わせて用いてもよい。好適なｐＨ緩衝剤としては、リン酸塩、酢酸塩、炭酸塩、硼酸塩、クエン酸塩及び硫酸塩が挙げられる。これらの中では、硼酸塩及び／又は硫酸塩が特に好ましい。
(PH buffer)
The electroless gold plating solution of the present invention preferably contains a pH buffer. By containing a pH buffer, the deposition rate can be adjusted to a desired value, and the pH of the plating solution can be kept constant. Only one type of pH buffer may be used, or two or more types may be used in combination. Suitable pH buffering agents include phosphates, acetates, carbonates, borates, citrates and sulfates. Of these, borates and / or sulfates are particularly preferred.
ｐＨ緩衝剤の含有量は、無電解金めっき液の全容量を基準として１〜１００ｇ／Ｌであることが好ましい。ｐＨ緩衝剤の含有量が１ｇ／Ｌ未満であると、ｐＨの緩衝効果が低下し、めっき液の状態が変化しやすくなる傾向にある。また、ｐＨ緩衝剤の含有量が１００ｇ／Ｌを超えると、めっき液中で再結晶化が進行する傾向がある。同様の観点から、ｐＨ緩衝剤の含有量は２０〜５０ｇ／Ｌであることがより好ましい。 The content of the pH buffering agent is preferably 1 to 100 g / L based on the total capacity of the electroless gold plating solution. When the content of the pH buffering agent is less than 1 g / L, the pH buffering effect tends to decrease, and the state of the plating solution tends to change. Moreover, when content of a pH buffering agent exceeds 100 g / L, there exists a tendency for recrystallization to advance in a plating solution. From the same viewpoint, the content of the pH buffering agent is more preferably 20 to 50 g / L.
（金属イオン隠蔽剤）
本発明の無電解金めっき液には、金属イオン隠蔽剤を含有させることが好ましい。当該成分を含有させることにより、以下の効果が得られる。すなわち、この無電解金めっき液を用いた作業中に、めっき装置の錆や金属破片などが持ち込まれたり、あるいは、被めっき物の付き回り不足により下地金属がめっき液中に混入したりする。その結果、銅、ニッケル、鉄等の不純物イオンが無電解めっき液中に混入することがある。このような不純物イオンが混入すると、めっき液の異状反応が進行して、めっき液の分解が発生する場合がある。しかし、無電解金めっき液中に金属イオン隠蔽剤を含有させることで、このような異状反応の抑制が可能となり、めっき液の分解を低減することができる。
(Metal ion concealing agent)
The electroless gold plating solution of the present invention preferably contains a metal ion concealing agent. The following effects are acquired by containing the said component. That is, during work using this electroless gold plating solution, rust, metal fragments, etc. of the plating apparatus are brought in, or the base metal is mixed into the plating solution due to insufficient attachment of the object to be plated. As a result, impurity ions such as copper, nickel and iron may be mixed in the electroless plating solution. When such impurity ions are mixed, an abnormal reaction of the plating solution may proceed and decomposition of the plating solution may occur. However, by including a metal ion concealing agent in the electroless gold plating solution, it is possible to suppress such abnormal reactions and reduce the decomposition of the plating solution.
金属イオン隠蔽剤としては、ベンゾトリアゾール系化合物を好適に用いることができる。ベンゾトリアゾール系化合物としては、例えば、ベンゾトリアゾールナトリウム、ベンゾトリアゾールカリウム、テトラヒドロベンゾトリアゾール、メチルベンゾトリアゾール及びニトロベンゾトリアゾール等が例示できる。これらは１種を単独で又は２種以上を組み合わせて用いられる。 As the metal ion concealing agent, a benzotriazole-based compound can be suitably used. Examples of the benzotriazole compounds include benzotriazole sodium, benzotriazole potassium, tetrahydrobenzotriazole, methylbenzotriazole, and nitrobenzotriazole. These are used singly or in combination of two or more.
金属イオン隠蔽剤の含有量は、無電解金めっき液の全容量を基準として０．５〜１００ｇ／Ｌであることが好ましい。金属イオン隠蔽剤の含有量が０．５ｇ／Ｌ未満であると、不純物の隠蔽効果が少なく、液安定性が低下する傾向がある。一方、金属イオン隠蔽剤の含有量が１００ｇ／Ｌを超えると、めっき液中で再結晶化が生じる場合がある。同様の観点並びにコスト低減の観点からは、金属イオン隠蔽剤の含有量は２〜１０ｇ／Ｌであることがより好ましい。 The content of the metal ion concealing agent is preferably 0.5 to 100 g / L based on the total capacity of the electroless gold plating solution. When the content of the metal ion concealing agent is less than 0.5 g / L, the effect of concealing impurities is small, and the liquid stability tends to decrease. On the other hand, if the content of the metal ion concealing agent exceeds 100 g / L, recrystallization may occur in the plating solution. From the same viewpoint and cost reduction viewpoint, the content of the metal ion concealing agent is more preferably 2 to 10 g / L.
本発明の無電解金めっき液には、本発明による上記目的を達成できる範囲内において、上述の各成分の他、通常の無電解金めっき液に含まれる各種成分を含んでもよい。ただし、本発明の無電解金めっき液は、チオ尿素化合物を含まないことが好ましい。チオ尿素化合物を含まなければ、チオ尿素を含んだ場合と比較して、本発明による無電解金めっき液の液安定性が向上すると共に、めっき付き回り性もより良好なものとなる。 The electroless gold plating solution of the present invention may contain various components contained in a normal electroless gold plating solution, in addition to the above-described components, within the range in which the above object according to the present invention can be achieved. However, the electroless gold plating solution of the present invention preferably does not contain a thiourea compound. If the thiourea compound is not included, the liquid stability of the electroless gold plating solution according to the present invention is improved and the revolving property with plating is also improved as compared with the case where thiourea is included.
（無電解金めっき液のｐＨ）
本発明の無電解金めっき液のｐＨは５〜１０であることが好ましい。無電解金めっき液のｐＨが５未満であると、めっき液が錯化剤を含む場合に錯化剤である亜硫酸塩やチオ硫酸塩が分解し、毒性の亜硫酸ガスが発生する虞がある。ｐＨが１０を超える場合、めっき液の安定性が低下する傾向がある。還元剤の析出効率を向上させ、速い析出速度を得るためには、無電解金めっき液のｐＨは８〜１０とすることがより好ましい。
(PH of electroless gold plating solution)
The pH of the electroless gold plating solution of the present invention is preferably 5-10. If the pH of the electroless gold plating solution is less than 5, when the plating solution contains a complexing agent, sulfite or thiosulfate which are complexing agents may be decomposed, and toxic sulfite gas may be generated. When the pH exceeds 10, the stability of the plating solution tends to decrease. In order to improve the deposition efficiency of the reducing agent and obtain a fast deposition rate, the pH of the electroless gold plating solution is more preferably 8-10.
（無電解金めっき方法）
次に、本発明の無電解金めっき方法の好適な実施形態について説明する。本実施形態の無電解金めっき方法は、上述した本発明の無電解金めっき液に被めっき体を浸漬する工程と、浸漬した該被めっき体の表面に金皮膜を形成させる工程とを有するものである。
(Electroless gold plating method)
Next, a preferred embodiment of the electroless gold plating method of the present invention will be described. The electroless gold plating method of the present embodiment includes a step of immersing the object to be plated in the above-described electroless gold plating solution of the present invention and a step of forming a gold film on the surface of the immersed object to be plated. It is.
上述の無電解金めっき方法において、無電解金めっき液のｐＨは５〜１０に調整されることが好ましく、８〜１０に調整されることがより好ましい。また、金皮膜を形成させる工程において、無電解金めっき液の液温は５０〜９５℃であることが好ましく、６５〜７０℃であることがより好ましい。該工程での無電解金めっき液の液温が５０℃未満である場合は、金皮膜の析出速度が遅くなり、金皮膜の形成効率が低下する傾向にある。また、液温が９５℃を超えると液安定性が低下する傾向がある。 In the above electroless gold plating method, the pH of the electroless gold plating solution is preferably adjusted to 5 to 10, and more preferably 8 to 10. In the step of forming the gold film, the temperature of the electroless gold plating solution is preferably 50 to 95 ° C, and more preferably 65 to 70 ° C. When the liquid temperature of the electroless gold plating solution in this step is less than 50 ° C., the deposition rate of the gold film is slowed and the formation efficiency of the gold film tends to decrease. Further, when the liquid temperature exceeds 95 ° C., the liquid stability tends to decrease.
以上、本発明の好適な実施形態について説明したが、本発明は上記実施形態に限定されるものではない。本発明は、その要旨を逸脱しない範囲で様々な変形が可能である。 The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment. The present invention can be variously modified without departing from the gist thereof.
以下、実施例によって本発明を更に詳細に説明するが、本発明はこれらの実施例に制限されるものではない。 EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not restrict | limited to these Examples.
（試料の作成）
めっき試験用サンプル板には３ｃｍ×３ｃｍ×０．３ｍｍの圧延銅板を使用した。まず、サンプル板表面の錆や有機物等を除去するために、５０℃に調整された酸性脱脂液ＣＬＣ−５０００（日立化成工業（株）製、商品名）にサンプル板を３分間浸漬した。更に、余分な界面活性剤を除去するために、そのサンプル板を５０℃の純水で１分間湯洗した。続いて、水洗処理を１分間行った。そして、表面の形状を均一化するために、サンプル板を過硫酸アンモニウム溶液（１２０ｇ／Ｌ）に室温で３分間浸漬してソフトエッチング処理を行った後、１分間の水洗処理を実施した。更に、表面の酸化銅を除去するために、サンプル板を硫酸（１０％）に室温で１分間浸漬し、その後、水洗処理を１分間行った。そして、置換パラジウムめっき液であるＳＡ−１００（日立化成工業（株）製、商品名）に室温でサンプル板を５分間浸漬した後、水洗処理を１分間行った。
(Sample preparation)
A rolled copper plate of 3 cm × 3 cm × 0.3 mm was used for the sample plate for plating test. First, in order to remove rust, organic matter, and the like on the surface of the sample plate, the sample plate was immersed in an acidic degreasing solution CLC-5000 (trade name, manufactured by Hitachi Chemical Co., Ltd.) adjusted to 50 ° C. for 3 minutes. Further, in order to remove excess surfactant, the sample plate was washed with pure water at 50 ° C. for 1 minute. Subsequently, washing with water was performed for 1 minute. Then, in order to make the surface shape uniform, the sample plate was immersed in an ammonium persulfate solution (120 g / L) at room temperature for 3 minutes to perform a soft etching process, followed by a 1-minute water washing process. Furthermore, in order to remove the copper oxide on the surface, the sample plate was immersed in sulfuric acid (10%) for 1 minute at room temperature, and then washed with water for 1 minute. And after immersing a sample board for 5 minutes at room temperature in SA-100 (Hitachi Chemical Industry Co., Ltd. make, brand name) which is a substituted palladium plating solution, the water washing process was performed for 1 minute.
次に、置換パラジウムめっき後のサンプル板を無電解Ｎｉ−Ｐめっき液であるＮＩＰＳ−１００（日立化成工業（株）製、製品名）に８５℃で、２５分間浸漬して、５μｍ程度の膜厚を有するニッケル−リンの合金めっき皮膜を形成した後、水洗処理を１分間行った。次いで、サンプル板を置換金めっき液であるＨＧＳ−５００（日立化成工業（株）製、製品名）に８５℃で１０分間浸漬して、０．０５〜０．１μｍ程度の膜厚の金めっき皮膜を形成させた後、水洗処理を１分間行った。こうして、無電解金めっき液の各種特性を評価するための試料を得た。 Next, the sample plate after substitution palladium plating is immersed in NIPS-100 (product name, manufactured by Hitachi Chemical Co., Ltd.) which is an electroless Ni-P plating solution at 85 ° C. for 25 minutes, and a film having a thickness of about 5 μm. After forming a nickel-phosphorus alloy plating film having a thickness, washing with water was performed for 1 minute. Next, the sample plate is dipped in HGS-500 (product name, manufactured by Hitachi Chemical Co., Ltd.), which is a displacement gold plating solution, at 85 ° C. for 10 minutes, and gold plating with a film thickness of about 0.05 to 0.1 μm is obtained. After the film was formed, washing with water was performed for 1 minute. Thus, a sample for evaluating various characteristics of the electroless gold plating solution was obtained.
無電解金めっき液の各種特性を評価する方法は下記のとおりである。 A method for evaluating various characteristics of the electroless gold plating solution is as follows.
（無電解金めっき液安定性評価方法）
無電解金めっき液の安定性評価に用いるめっき槽には、ＰＰ（ポリプロピレン製）樹脂製の１Ｌビーカーを使用した。また、評価に用いるめっき槽は、めっき槽内に付着している不純物を予め除去したものを使用した。めっき槽からの不純物除去方法を以下に説明する。まず、めっき槽内を常温の王水（１：３＝硝酸：塩酸、５０％に純水で希釈）で６時間以上洗浄した。その後、水洗、純水洗を順次、十分に行い、８０℃で乾燥させた。
(Electroless gold plating solution stability evaluation method)
A 1 L beaker made of PP (polypropylene) resin was used as a plating tank used for evaluating the stability of the electroless gold plating solution. Moreover, what removed the impurity adhering in the plating tank beforehand was used for the plating tank used for evaluation. A method for removing impurities from the plating tank will be described below. First, the inside of the plating tank was washed with normal aqua regia (1: 3 = nitric acid: hydrochloric acid, diluted with 50% pure water) for 6 hours or more. Thereafter, washing with water and washing with pure water were sufficiently carried out sequentially and dried at 80 ° C.
無電解金めっき液の安定性は、３つの条件下において評価した。まず、上述の方法で不純物を除去しためっき槽に、後述のようにして調整した無電解金めっき液を注入した。次いで、その無電解金めっき液の温度を６５℃に設定して１時間放置した。その直後の無電解金めっき液の安定性を評価した。次に、無電解金めっき液を所定温度に調整した後に、上述の試料をその無電解金めっき液に浸漬した。そして、０．３６ｄｍ２／Ｌのめっき負荷で１時間（６５℃）めっき処理を行い、試料の表面上に無電解金めっき皮膜を形成した。その直後の無電解金めっき液の安定性を評価した。次に、試料を取り出した後、その無電解金めっき液を自然冷却し、そのまま室温で無電解金めっき液を１日放置した。その直後の無電解金めっき液の安定性を評価した。 The stability of the electroless gold plating solution was evaluated under three conditions. First, an electroless gold plating solution adjusted as described below was poured into a plating tank from which impurities were removed by the above-described method. Next, the temperature of the electroless gold plating solution was set to 65 ° C. and left for 1 hour. Immediately thereafter, the stability of the electroless gold plating solution was evaluated. Next, after adjusting the electroless gold plating solution to a predetermined temperature, the above-described sample was immersed in the electroless gold plating solution. And the plating process was performed for 1 hour (65 degreeC) with the plating load of 0.36 dm < 2 > / L, and the electroless gold plating film | membrane was formed on the surface of the sample. Immediately thereafter, the stability of the electroless gold plating solution was evaluated. Next, after taking out the sample, the electroless gold plating solution was naturally cooled, and the electroless gold plating solution was allowed to stand at room temperature for one day. Immediately thereafter, the stability of the electroless gold plating solution was evaluated.
無電解金めっき液の安定性の評価は、めっき槽の底面の全面積に対して、異常析出物（金）が覆った底面の面積の割合を数値化して行った（これを「槽内異常析出発生面積（％）」とする。）。この数値が小さい程、無電解金めっき液の安定性が高いことになる。評価基準は表１に示す通りである。
（皮膜外観及びめっき付き回り性評価方法）
上述のようにして形成された無電解金めっき皮膜の外観（これを「皮膜外観」とする。）は、その色により評価した。電解金めっき皮膜（膜厚０．５μｍ相当）に近い外観を「レモンイエロー」とした。また、それよりも濃い色である場合を「褐色」とした。めっき付き回り性については、めっき端部を顕微鏡（２０〜５０倍相当）で目視観察して評価した。めっき付き回り不良が認められる場合を「あり」、認められない場合を「なし」とした。
(Evaluation method for coating appearance and plating rotation)
The appearance of the electroless gold plating film formed as described above (hereinafter referred to as “film appearance”) was evaluated by its color. The appearance close to an electrolytic gold plating film (equivalent to a film thickness of 0.5 μm) was designated as “lemon yellow”. Moreover, the case where the color was darker than that was defined as “brown”. With respect to the wraparound property with plating, the plating end was visually observed with a microscope (equivalent to 20 to 50 times) for evaluation. The case where there was a plating failure was “Yes”, and the case where it was not recognized was “None”.
（無電解金めっき液の調製及び評価）
（実施例１〜４）
表２に示す組成となるように各成分をイオン交換水中に配合し、実施例１〜４の無電解金めっき液を調製した。実施例１〜４では、還元剤であるヒドロキノンの含有量を、無電解金めっき液の全容量に対して５ｇ／Ｌと一定にした。また、重金属塩として硝酸タリウムを用い、その含有量はタリウムイオン濃度が質量基準（以下同様）で１ｐｐｍとなるように調整した。
(Preparation and evaluation of electroless gold plating solution)
(Examples 1-4)
Each component was mix | blended in ion-exchange water so that it might become a composition shown in Table 2, and the electroless gold plating solution of Examples 1-4 was prepared. In Examples 1 to 4, the content of hydroquinone as a reducing agent was kept constant at 5 g / L with respect to the total capacity of the electroless gold plating solution. Further, thallium nitrate was used as the heavy metal salt, and the content thereof was adjusted so that the thallium ion concentration was 1 ppm on a mass basis (hereinafter the same).
また、ポリエチレングリコール系化合物として、実施例１では重量平均分子量２００のポリエチレングリコールを３ｐｐｍ、実施例２では重量平均分子量１０００のポリエチレングリコールを０．５ｐｐｍ用いた。また、実施例３ではポリエチレングリコールジメチルエーテルを、実施例４ではポリエチレングリコールモノメチルエーテルをそれぞれ３ｐｐｍ用いた。 In addition, in Example 1, 3 ppm of polyethylene glycol having a weight average molecular weight of 200 was used in Example 1, and 0.5 ppm of polyethylene glycol having a weight average molecular weight of 1000 was used in Example 2. In Example 3, polyethylene glycol dimethyl ether was used, and in Example 4, 3 ppm of polyethylene glycol monomethyl ether was used.
実施例１〜４で得られた無電解金めっき液について、上述した評価方法に基づいて、無電解金めっき液安定性、皮膜外観及びめっき付き回り性を評価した。また、併せて金めっき皮膜の析出速度を測定した。これらの結果を表３に示す。また、めっき処理時のｐＨ、めっき負荷及びめっき液温度も表３に示す。 The electroless gold plating solutions obtained in Examples 1 to 4 were evaluated on the electroless gold plating solution stability, coating appearance, and plating revolving property based on the evaluation methods described above. In addition, the deposition rate of the gold plating film was also measured. These results are shown in Table 3. Table 3 also shows the pH, plating load, and plating solution temperature during the plating process.
（実施例５〜９）
表４に示す組成となるように各成分をイオン交換水中に配合し、実施例５〜９の無電解金めっき液を調製した。実施例５〜９では、還元剤であるヒドロキノンの含有量を、無電解金めっき液の全容量に対して５ｇ／Ｌと一定にした。また、重金属塩として硝酸タリウムを用い、その含有量はタリウムイオン濃度が１ｐｐｍとなるように調整した。
(Examples 5 to 9)
Each component was mix | blended in ion-exchange water so that it might become a composition shown in Table 4, and the electroless gold plating solution of Examples 5-9 was prepared. In Examples 5 to 9, the content of hydroquinone as a reducing agent was fixed at 5 g / L with respect to the total capacity of the electroless gold plating solution. Further, thallium nitrate was used as the heavy metal salt, and the content thereof was adjusted so that the thallium ion concentration was 1 ppm.
また、実施例５〜９では、ポリエチレングリコール系化合物として重量平均分子量２００のポリエチレングリコールを用いた。また、ポリエチレングリコールの含有量は、実施例５〜９で、それぞれ１、３、６、１２及び２４ｐｐｍとなるように調整した。 In Examples 5 to 9, polyethylene glycol having a weight average molecular weight of 200 was used as the polyethylene glycol compound. Moreover, content of polyethyleneglycol was adjusted so that it might be 1, 3, 6, 12, and 24 ppm in Examples 5-9, respectively.
実施例５〜９で得られた無電解金めっき液について、上述した評価方法に基づいて、無電解金めっき液安定性、皮膜外観及びめっき付き回り性を評価した。また、併せて金めっき皮膜の析出速度を測定した。これらの結果を表５に示す。また、めっき処理時のｐＨ、めっき負荷及びめっき液温度も表５に示す。 The electroless gold plating solutions obtained in Examples 5 to 9 were evaluated on the electroless gold plating solution stability, film appearance, and plating revolving property based on the evaluation methods described above. In addition, the deposition rate of the gold plating film was also measured. These results are shown in Table 5. Table 5 also shows the pH, plating load, and plating solution temperature during the plating process.
実施例５〜９の無電解金めっき液では、ポリエチレングリコール（重量平均分子量２００）の含有量を実施例１の２〜８倍に増やすことで、析出速度が徐々に低下した。しかしながら、ポリエチレングリコールの含有量が２４ｐｐｍと高い場合であっても、１．２１μｍ／ｈｒと速い析出速度を確保できた。 In the electroless gold plating solutions of Examples 5 to 9, the deposition rate was gradually decreased by increasing the content of polyethylene glycol (weight average molecular weight 200) to 2 to 8 times that of Example 1. However, even when the polyethylene glycol content was as high as 24 ppm, a fast deposition rate of 1.21 μm / hr could be secured.
（実施例１０〜１４）
表６に示す組成となるように各成分をイオン交換水中に配合し、実施例１０〜１４の無電解金めっき液を調製した。実施例１０〜１４は、還元剤であるヒドロキノンの含有量を、無電解金めっき液の全容量に対して５ｇ／Ｌと一定にした。また、重金属塩として硝酸タリウムを用い、その含有量はタリウムイオン濃度が１ｐｐｍとなるように調整した。
(Examples 10 to 14)
Each component was mix | blended in ion-exchange water so that it might become a composition shown in Table 6, and the electroless gold plating solution of Examples 10-14 was prepared. In Examples 10 to 14, the content of hydroquinone as a reducing agent was kept constant at 5 g / L with respect to the total capacity of the electroless gold plating solution. Further, thallium nitrate was used as the heavy metal salt, and the content thereof was adjusted so that the thallium ion concentration was 1 ppm.
また、実施例１０〜１４では、ポリエチレングリコール系化合物として重量平均分子量１０００のポリエチレングリコールを用いた。また、ポリエチレングリコールの含有量は、実施例１０〜１４で、それぞれ０．２５、０．５、１、３、及び５ｐｐｍとなるように調整した。 In Examples 10 to 14, polyethylene glycol having a weight average molecular weight of 1000 was used as the polyethylene glycol compound. Moreover, content of polyethyleneglycol was adjusted so that it might be set to 0.25, 0.5, 1, 3, and 5 ppm in Examples 10-14, respectively.
実施例１０〜１４で得られた無電解金めっき液について、上述した評価方法に基づいて、無電解金めっき液安定性、皮膜外観及びめっき付き回り性を評価した。また、併せて金めっき皮膜の析出速度を測定した。これらの結果を表７に示す。また、めっき処理時のｐＨ、めっき負荷及びめっき液温度も表７に示す。
実施例１０〜１４の無電解金めっき液では、ポリエチレングリコール（重量平均分子量１０００）の含有量を実施例２の２〜１０倍に増やすことで、析出速度が徐々に低下した。しかしながら、ポリエチレングリコールの含有量が５ｐｐｍと高い場合であっても、０．８５μｍ／ｈｒと速い析出速度を確保できた。
The electroless gold plating solutions obtained in Examples 10 to 14 were evaluated on the electroless gold plating solution stability, film appearance, and plating revolving property based on the evaluation methods described above. In addition, the deposition rate of the gold plating film was also measured. These results are shown in Table 7. Table 7 also shows the pH, plating load, and plating solution temperature during the plating process.
In the electroless gold plating solutions of Examples 10 to 14, the deposition rate was gradually decreased by increasing the content of polyethylene glycol (weight average molecular weight 1000) to 2 to 10 times that of Example 2. However, even when the polyethylene glycol content was as high as 5 ppm, a fast deposition rate of 0.85 μm / hr could be secured.
（実施例１５〜１９）
表８に示す組成となるように各成分をイオン交換水中に配合し、実施例１３〜１６の無電解金めっき液を調製した。実施例１５〜１９では、還元剤であるヒドロキノンの含有量を、無電解金めっき液の全容量に対して５ｇ／Ｌと一定にした。また、重金属塩として硝酸タリウムを用い、その含有量はタリウムイオン濃度が１ｐｐｍとなるように調整した。
(Examples 15 to 19)
Each component was mix | blended in ion-exchange water so that it might become a composition shown in Table 8, and the electroless gold plating solution of Examples 13-16 was prepared. In Examples 15 to 19, the content of hydroquinone as a reducing agent was kept constant at 5 g / L with respect to the total capacity of the electroless gold plating solution. Further, thallium nitrate was used as the heavy metal salt, and the content thereof was adjusted so that the thallium ion concentration was 1 ppm.
また、実施例１３〜１６では、ポリエチレングリコール系化合物としてポリエチレングリコールジメチルエーテルを用いた。また、ポリエチレングリコールジメチルエーテルの含有量は、実施例１３〜１６で、それぞれ１、３、６、１２及び２４ｐｐｍとなるようにした。 In Examples 13 to 16, polyethylene glycol dimethyl ether was used as the polyethylene glycol compound. Moreover, content of polyethyleneglycol dimethyl ether was made into 1, 3, 6, 12, and 24 ppm in Examples 13-16, respectively.
実施例１３〜１６で得られた無電解金めっき液について、上述した評価方法に基づいて、無電解金めっき液安定性、皮膜外観及びめっき付き回り性を評価した。また、併せて金めっき皮膜の析出速度を測定した。これらの結果を表９に示す。また、めっき処理時のｐＨ、めっき負荷及びめっき液温度も表９に示す。 The electroless gold plating solutions obtained in Examples 13 to 16 were evaluated on the electroless gold plating solution stability, coating appearance, and plating revolving property based on the evaluation methods described above. In addition, the deposition rate of the gold plating film was also measured. These results are shown in Table 9. Table 9 also shows the pH, plating load, and plating solution temperature during the plating process.
実施例１３〜１６の無電解金めっき液では、ポリエチレングリコールジメチルエーテルの含有量を実施例３の２〜８倍に増やすことで、析出速度が徐々に低下した。しかしながら、ポリエチレングリコールジメチルエーテルの含有量が２４ｐｐｍと高い場合であっても、０．７２μｍ／ｈｒと速い析出速度を確保できた。 In the electroless gold plating solutions of Examples 13 to 16, the deposition rate was gradually decreased by increasing the content of polyethylene glycol dimethyl ether to 2 to 8 times that of Example 3. However, even when the content of polyethylene glycol dimethyl ether was as high as 24 ppm, a fast deposition rate of 0.72 μm / hr could be secured.
（比較例１〜４）
表１０に示す組成となるように各成分をイオン交換水中に配合し、比較例１〜４の無電解金めっき液を調製した。比較例１〜４の無電解金めっき液は、ポリエチレングリコール系化合物及び重金属塩を含有しないものとした。また、比較例１の無電解金めっき液には還元剤であるヒドロキノンを添加せず、また、比較例２〜４の無電解金めっき液には、それぞれヒドロキノンを、その含有量が無電解金めっき液の全容量に対してそれぞれ１、３及び５ｇ／Ｌになるように添加した。
(Comparative Examples 1-4)
Each component was mix | blended in ion-exchange water so that it might become a composition shown in Table 10, and the electroless gold plating solution of Comparative Examples 1-4 was prepared. The electroless gold plating solutions of Comparative Examples 1 to 4 did not contain a polyethylene glycol compound and a heavy metal salt. Moreover, hydroquinone which is a reducing agent is not added to the electroless gold plating solution of Comparative Example 1, and hydroquinone is contained in each of the electroless gold plating solutions of Comparative Examples 2 to 4 with an electroless gold content. It added so that it might become 1, 3 and 5 g / L, respectively with respect to the total volume of a plating solution.
比較例１〜４で得られた無電解金めっき液について、上述した評価方法に基づいて、無電解金めっき液安定性、皮膜外観及びめっき付き回り性を評価した。また、併せて金めっき皮膜の析出速度を測定した。これらの結果を表１１に示す。また、めっき処理時のｐＨ、めっき負荷及びめっき液温度も表１１に示す。 The electroless gold plating solutions obtained in Comparative Examples 1 to 4 were evaluated on the electroless gold plating solution stability, coating appearance, and plating coverage with the above-described evaluation methods. In addition, the deposition rate of the gold plating film was also measured. These results are shown in Table 11. Table 11 also shows the pH, plating load, and plating solution temperature during the plating process.
還元剤であるヒドロキノンを添加しなかった比較例１の無電解金めっき液では、サンプル板を１時間めっき液中に浸漬しても、金めっき皮膜の膜厚はほとんど増加せず、析出が進行しない結果となった。一方、還元剤としてヒドロキノンを添加した比較例２〜４の無電解金めっき液では、ヒドロキノンの添加量を１、３及び５ｇ／Ｌと増加させるに従い、析出速度が増加した。特にヒドロキノンを５ｇ／Ｌ含有する比較例４の無電解金めっき液を用いると、析出速度は０．１５２μｍ／ｈｒと、還元剤を添加しない場合の２．５倍を示した。しかしながら、この析出速度は一般的な無電解金めっき液（約０．２〜１．０μｍ／ｈｒ又はこれ以上）と比較して遅い結果となっている。このため、パッケージ基板等のワイヤボンディング基板に適用すると、生産性が悪くなると考えられる。 In the electroless gold plating solution of Comparative Example 1 in which hydroquinone as a reducing agent was not added, even when the sample plate was immersed in the plating solution for 1 hour, the film thickness of the gold plating film was hardly increased, and precipitation proceeded. The result was not. On the other hand, in the electroless gold plating solutions of Comparative Examples 2 to 4 in which hydroquinone was added as a reducing agent, the deposition rate increased as the amount of hydroquinone added was increased to 1, 3 and 5 g / L. In particular, when the electroless gold plating solution of Comparative Example 4 containing 5 g / L of hydroquinone was used, the deposition rate was 0.152 μm / hr, 2.5 times that when no reducing agent was added. However, this deposition rate is slower than a general electroless gold plating solution (about 0.2 to 1.0 μm / hr or more). For this reason, when applied to a wire bonding substrate such as a package substrate, it is considered that productivity is deteriorated.
（比較例５〜９）
表１２に示す組成となるように各成分をイオン交換水中に配合し、比較例５〜９の無電解金めっき液を調製した。比較例５〜９の無電解金めっき液は、ポリエチレングリコール系化合物を含有しないものとした。また、これらの無電解金めっき液には、還元剤であるヒドロキノンを、その含有量が無電解金めっき液の全容量に対して５ｇ／Ｌとなるように添加した。更に、比較例５〜８の無電解金めっき液には重金属塩を添加しなかった。また、比較例９の無電解金めっき液には重金属塩として硝酸タリウムをタリウムイオンの濃度が１ｐｐｍになるように添加した。なお、比較例５〜７の無電解金めっき液は、１ＮのＮａＯＨ水溶液を用いて、金めっき液のｐＨがそれぞれ、８、９及び１０となるよう調整した。
(Comparative Examples 5-9)
Each component was mix | blended in ion-exchange water so that it might become a composition shown in Table 12, and the electroless gold plating solution of Comparative Examples 5-9 was prepared. The electroless gold plating solutions of Comparative Examples 5 to 9 did not contain a polyethylene glycol compound. Moreover, hydroquinone as a reducing agent was added to these electroless gold plating solutions so that the content thereof was 5 g / L with respect to the total capacity of the electroless gold plating solution. Further, no heavy metal salt was added to the electroless gold plating solutions of Comparative Examples 5 to 8. Further, thallium nitrate as a heavy metal salt was added to the electroless gold plating solution of Comparative Example 9 so that the concentration of thallium ions was 1 ppm. The electroless gold plating solutions of Comparative Examples 5 to 7 were adjusted using a 1N NaOH aqueous solution so that the pH of the gold plating solution was 8, 9, and 10, respectively.
比較例５〜９で得られた無電解金めっき液について、上述した評価方法に基づいて、無電解金めっき液安定性、皮膜外観及びめっき付き回り性を評価した。また、併せて金めっき皮膜の析出速度を測定した。これらの結果を表１３に示す。また、めっき処理時のｐＨ、めっき負荷及びめっき液温度も表１３に示す。 The electroless gold plating solutions obtained in Comparative Examples 5 to 9 were evaluated on the electroless gold plating solution stability, film appearance, and plating revolving property based on the above-described evaluation methods. In addition, the deposition rate of the gold plating film was also measured. These results are shown in Table 13. Table 13 also shows the pH, plating load, and plating solution temperature during the plating process.
比較例５の無電解金めっき液（ｐＨ８）を用いると、皮膜外観は良好で、めっき付き回り不良は生じなかったが、析出速度が０．３６μｍ／ｈｒと低い結果となった。また、比較例６及び７の無電解金めっき液（ｐＨ９、１０）を用いると、析出速度が比較例５に対して著しく増加したものの、槽内に異常析出が発生する結果となった。また、めっき付き回り不良も発生しなかったが、皮膜外観は褐色の外観不良となった。 When the electroless gold plating solution (pH 8) of Comparative Example 5 was used, the appearance of the film was good and no defective rotation with plating occurred, but the deposition rate was as low as 0.36 μm / hr. Further, when the electroless gold plating solutions (pH 9, 10) of Comparative Examples 6 and 7 were used, although the deposition rate was remarkably increased with respect to Comparative Example 5, abnormal precipitation occurred in the tank. In addition, there was no defect with plating, but the appearance of the film was brown.
比較例８の無電解金めっき液を用いて、ｐＨ９、めっき浴温度８０℃の条件でめっきを行ったところ、皮膜外観が褐色の外観不良となり、めっき液の安定性も悪く、加温中にめっき槽内全面に異常析出が発生した。 When plating was performed using the electroless gold plating solution of Comparative Example 8 at a pH of 9 and a plating bath temperature of 80 ° C., the appearance of the film was brown, the stability of the plating solution was poor, and during heating Abnormal precipitation occurred on the entire surface of the plating tank.
比較例９の無電解金めっき液は、比較例６の無電解金めっき液に重金属塩として硝酸タリウムをタリウムイオン濃度で１ｐｐｍになるよう加えたものである。その結果、析出速度が増加した。また、皮膜外観は均一なレモンイエローで、めっき付き回り不良の発生もなく良好であった。しかし、めっき前の加温中に槽内の一部に異常析出が発生し、さらにめっき中に異常析出が促進されて、実用上適用困難な結果となった。 The electroless gold plating solution of Comparative Example 9 is obtained by adding thallium nitrate as a heavy metal salt to the electroless gold plating solution of Comparative Example 6 so that the thallium ion concentration is 1 ppm. As a result, the deposition rate increased. Further, the film appearance was uniform lemon yellow, and it was good with no occurrence of defects with plating. However, abnormal precipitation occurred in a part of the tank during heating before plating, and the abnormal precipitation was promoted during plating, resulting in practically difficult application.
（比較例１０〜１２）
表１４に示す組成となるように各成分をイオン交換水中に配合し、比較例１０〜１２の無電解金めっき液を調製した。比較例１０〜１２の無電解金めっき液は、重金属炎を添加しない以外は実施例５、１０、１５と同様の組成であった。
(Comparative Examples 10-12)
Each component was mix | blended in ion-exchange water so that it might become a composition shown in Table 14, and the electroless gold plating liquid of Comparative Examples 10-12 was prepared. The electroless gold plating solutions of Comparative Examples 10 to 12 had the same composition as Examples 5, 10, and 15 except that no heavy metal flame was added.
比較例１０〜１２で得られた無電解金めっき液について、上述した評価方法に基づいて、無電解金めっき液安定性、皮膜外観及びめっき付き回り性を評価した。また、併せて金めっき皮膜の析出速度を測定した。これらの結果を表１５に示す。また、めっき処理時のｐＨ、めっき負荷及びめっき液温度も表１５に示す。重金属塩（タリウムイオン）を添加しなかった比較例１０〜１２では、重金属塩を添加した実施例５、１０、及び１５に比べて析出速度が低下した。また、めっき外観については、褐色の外観不良となった。 The electroless gold plating solutions obtained in Comparative Examples 10 to 12 were evaluated on the electroless gold plating solution stability, film appearance, and plating revolving property based on the evaluation methods described above. In addition, the deposition rate of the gold plating film was also measured. These results are shown in Table 15. Table 15 also shows the pH, plating load, and plating solution temperature during the plating process. In Comparative Examples 10 to 12 in which the heavy metal salt (thallium ion) was not added, the deposition rate was lower than those in Examples 5, 10 and 15 in which the heavy metal salt was added. Moreover, about the plating external appearance, it became a brown external appearance defect.
（比較例１３〜１６）
表１６に示す組成となるように各成分をイオン交換水中に配合し、比較例１３〜１６の無電解金めっき液を調製した。比較例１３、１４は還元剤にチオ尿素、アリルチオ尿素を使用した。また、比較例１５、１６は比較例１３、１４と同様の組成に安定剤として重量平均分子量１０００のポリエチレングリコールを添加した組成とした。
(Comparative Examples 13 to 16)
Each component was mix | blended in ion-exchange water so that it might become a composition shown in Table 16, and the electroless gold plating solution of Comparative Examples 13-16 was prepared. In Comparative Examples 13 and 14, thiourea and allylthiourea were used as reducing agents. In Comparative Examples 15 and 16, compositions similar to Comparative Examples 13 and 14 were added with polyethylene glycol having a weight average molecular weight of 1000 as a stabilizer.
比較例１３〜１６で得られた無電解金めっき液について、上述した評価方法に基づいて、無電解金めっき液安定性、皮膜外観及びめっき付き回り性を評価した。また、併せて金めっき皮膜の析出速度を測定した。これらの結果を表１７に示す。また、めっき処理時のｐＨ、めっき負荷及びめっき液温度も表１７に示す。還元剤にチオ尿素、アリルチオ尿素を使用した場合、十分な析出速度が得られなかった。無電解金めっき液の安定性についても、比較例１４では、めっき中は安定であったが、めっき後１日経過すると異常析出が発生し、めっき液が不安定になった。更に、比較例１４の組成に安定剤として重量平均分子量１０００のポリエチレングリコールを１ｐｐｍ添加した比較例１６の組成でも、安定剤の効果は小さく、１日経過後には多量の異常析出が発生して、液が分解してしまった。 The electroless gold plating solutions obtained in Comparative Examples 13 to 16 were evaluated on the electroless gold plating solution stability, film appearance, and plating revolving property based on the evaluation methods described above. In addition, the deposition rate of the gold plating film was also measured. These results are shown in Table 17. Table 17 also shows the pH, plating load, and plating solution temperature during the plating process. When thiourea or allylthiourea was used as the reducing agent, a sufficient precipitation rate could not be obtained. The stability of the electroless gold plating solution was also stable during plating in Comparative Example 14, but abnormal deposition occurred after 1 day after plating, and the plating solution became unstable. Furthermore, even in the composition of Comparative Example 16 in which 1 ppm of polyethylene glycol having a weight average molecular weight of 1000 was added as a stabilizer to the composition of Comparative Example 14, the effect of the stabilizer was small, and a large amount of abnormal precipitation occurred after 1 day. The liquid has decomposed.
（比較例１７〜２０）
表１８に示す組成となるように各成分をイオン交換水中に配合し、比較例１７〜２０の無電解金めっき液を調製した。比較例１７、１８は還元剤にチオ尿素、アリルチオ尿素を使用し、還元促進剤にヒドロキノンを使用した。また、比較例１９、２０は比較例１７、１８と同様の組成に安定剤として重量平均分子量１０００のポリエチレングリコールを添加した組成とした。
(Comparative Examples 17-20)
Each component was mix | blended in ion-exchange water so that it might become a composition shown in Table 18, and the electroless gold plating liquid of Comparative Examples 17-20 was prepared. In Comparative Examples 17 and 18, thiourea and allylthiourea were used as the reducing agent, and hydroquinone was used as the reduction accelerator. In Comparative Examples 19 and 20, compositions similar to Comparative Examples 17 and 18 were added with polyethylene glycol having a weight average molecular weight of 1000 as a stabilizer.
比較例１７〜２０で得られた無電解金めっき液について、上述した評価方法に基づいて、無電解金めっき液安定性、皮膜外観及びめっき付き回り性を評価した。また、併せて金めっき皮膜の析出速度を測定した。これらの結果を表１９に示す。また、めっき処理時のｐＨ、めっき負荷及びめっき液温度も表１９に示す。還元剤にチオ尿素、アリルチオ尿素を使用し、還元促進剤にヒドロキノンを使用した場合、皮膜外観は良好であったが、めっき付き回り不良が発生した。また、無電解金めっき液の安定性についても、比較例１７、１８では、めっき中は安定であったが、めっき後１日経過すると異常析出が発生して、めっき液が不安定になった。更に、比較例１７、１８の組成に安定剤として重量平均分子量１０００のポリエチレングリコールを１ｐｐｍ添加した比較例１９、２０の組成でも、安定剤の効果は小さかった。 The electroless gold plating solutions obtained in Comparative Examples 17 to 20 were evaluated on the electroless gold plating solution stability, coating appearance, and plating revolving property based on the evaluation methods described above. In addition, the deposition rate of the gold plating film was also measured. These results are shown in Table 19. Table 19 also shows the pH, plating load, and plating solution temperature during the plating process. When thiourea or allyl thiourea was used as the reducing agent and hydroquinone was used as the reduction accelerator, the film appearance was good, but poor plating rotation occurred. Further, the stability of the electroless gold plating solution was also stable during plating in Comparative Examples 17 and 18. However, abnormal deposition occurred after 1 day after plating, and the plating solution became unstable. . Furthermore, the effects of the stabilizers were small even in the compositions of Comparative Examples 19 and 20 in which 1 ppm of polyethylene glycol having a weight average molecular weight of 1000 was added as a stabilizer to the compositions of Comparative Examples 17 and 18.
以上の結果から、本発明の無電解金めっき液においては、ポリエチレングリコール系化合物を添加することによって、めっき液の安定性を大幅に向上させることが可能であることがわかった。また、本発明の無電解金めっき液は、低い温度条件（６０〜７０℃）において実用的な析出速度でめっきを行うことが可能であった。更に、めっき後の皮膜外観も均一なレモンイエローで、めっき付き回り不良も発生しなかった。 From the above results, it was found that the stability of the plating solution can be greatly improved by adding a polyethylene glycol compound in the electroless gold plating solution of the present invention. In addition, the electroless gold plating solution of the present invention can be plated at a practical deposition rate under low temperature conditions (60 to 70 ° C.). Furthermore, the appearance of the film after plating was uniform lemon yellow, and there was no defect with plating.
すなわち、本発明の無電解金めっき液は、液温６０〜８０℃程度の低温であっても十分な析出速度を発揮し、皮膜外観が良好であり、かつ、めっき液の安定性が特に優れており、適用できる材料や電子部品等の範囲は大幅に拡大されることが明らかになった。 That is, the electroless gold plating solution of the present invention exhibits a sufficient deposition rate even when the solution temperature is as low as about 60 to 80 ° C., the film appearance is good, and the stability of the plating solution is particularly excellent. It has become clear that the range of applicable materials and electronic components will be greatly expanded.
Claims (7)
前記金塩が、塩化金酸塩、亜硫酸金塩、チオ硫酸金塩、及びチオリンゴ酸金塩からなる群より選ばれる少なくとも１種の金塩を含み、
前記一般式（１）で表される還元剤が、下記一般式（２）で表される還元剤を含み、
前記重金属塩が、タリウム塩、鉛塩、砒素塩、アンチモン塩、テルル塩及びビスマス塩からなる群より選ばれる少なくとも１種の重金属塩を含み、
前記ポリエチレングリコール系化合物が、ポリエチレングリコール、ポリエチレングリコールモノオレエート、ポリエチレングリコールモノステアレート、ポリエチレングリコールモノメチルエーテル、ポリエチレングリコールモノラウレート、ポリエチレングリコールジメチルエーテル、及びポリエチレングリコールジグリシジルエーテルからなる群より選ばれる少なくとも１種のポリエチレングリコール系化合物を含む、無電解金めっき液。
［式（１）中、Ｒ１は水酸基又はアミノ基を示し、Ｒ２、Ｒ３及びＲ４はそれぞれ独立に水酸基、アミノ基、水素原子又はアルキル基を示す。］
［式（２）中、Ｒ ２１ は水酸基又はアミノ基を示し、Ｒ ２２ は水素原子又は炭素数１〜４のアルキル基を示す。］ And gold salts, see containing a reducing agent represented by the following general formula (1), and heavy metal salts, polyethylene glycol compounds, and,
The gold salt includes at least one gold salt selected from the group consisting of chloroaurate, gold sulfite, gold thiosulfate, and gold thiomalate,
The reducing agent represented by the general formula (1) includes a reducing agent represented by the following general formula (2),
The heavy metal salt includes at least one heavy metal salt selected from the group consisting of thallium salt, lead salt, arsenic salt, antimony salt, tellurium salt and bismuth salt;
The polyethylene glycol-based compound is at least selected from the group consisting of polyethylene glycol, polyethylene glycol monooleate, polyethylene glycol monostearate, polyethylene glycol monomethyl ether, polyethylene glycol monolaurate, polyethylene glycol dimethyl ether, and polyethylene glycol diglycidyl ether. An electroless gold plating solution containing one type of polyethylene glycol compound .
[In formula (1), R 1 represents a hydroxyl group or an amino group, and R 2 , R 3 and R 4 each independently represent a hydroxyl group, an amino group, a hydrogen atom or an alkyl group. ]
[In Formula (2), R 21 represents a hydroxyl group or an amino group, and R 22 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ]
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| KR20100034336A (en) * | 2008-09-23 | 2010-04-01 | 삼성전기주식회사 | Electroless plating solution |
| US20190010609A1 (en) * | 2015-12-23 | 2019-01-10 | Uniwersytet Warszawski | Means for carrying out electroless metal deposition with atomic sub-monolayer precision |
| JP6842475B2 (en) | 2016-12-27 | 2021-03-17 | 関東化学株式会社 | Cyan-free substituted gold plating solution composition |
| JP7080781B2 (en) | 2018-09-26 | 2022-06-06 | 株式会社東芝 | Porous layer forming method, etching method, article manufacturing method, semiconductor device manufacturing method, and plating solution |
| CN113862736B (en) * | 2021-10-22 | 2024-01-26 | 深圳市潮尊珠宝首饰有限公司 | Cyanide-free sulfite system electro-gold plating solution and application thereof |
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| JP2874088B2 (en) * | 1993-03-26 | 1999-03-24 | 上村工業株式会社 | Electroless gold plating bath |
| JPH0971871A (en) * | 1995-09-06 | 1997-03-18 | Merutetsukusu Kk | Electroless gold plating liquid |
| JP3565302B2 (en) * | 1996-11-18 | 2004-09-15 | 日立化成工業株式会社 | Electroless gold plating method |
| JP2003268559A (en) * | 2002-03-15 | 2003-09-25 | Hitachi Chem Co Ltd | Electroless gold plating solution and electroless gold plating method |
| JP2004010964A (en) * | 2002-06-06 | 2004-01-15 | Hitachi Chem Co Ltd | Electroless gold plating liquid and electroless gold plating method |
| JP2004190075A (en) * | 2002-12-10 | 2004-07-08 | Kanto Chem Co Inc | Electroless gold plating solution |
| JP4078977B2 (en) * | 2002-12-27 | 2008-04-23 | 日立化成工業株式会社 | Electroless gold plating solution and electroless gold plating method |
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