JP2021070858A - Substitution gold plating solution and substitution gold plating method - Google Patents
Substitution gold plating solution and substitution gold plating method Download PDFInfo
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Abstract
Description
本発明は、シアン化金化合物を用いた置換金めっき液および置換金めっき方法に関する。 The present invention relates to a replacement gold plating solution and a replacement gold plating method using a gold cyanide compound.
電子機器の電子部品に用いられる実装基板の接合部パッドには、通常金めっき層が形成されている。金は、銀、銅の次に高い電気導電率を有し、熱圧着による接合性などの物理的性質に優れると共に、耐酸化性や耐薬品性などの化学的性質にも優れる。そのため、金が高価であるにも関わらず、実装基板の接合部パッドに使用され続けている。このような実装基板のパターンは、電源リードに対する制約があり、また、めっき皮膜の形成が困難である独立したパターンがあることから、無電解金めっき法が多く採用されている。 A gold-plated layer is usually formed on a joint pad of a mounting substrate used for an electronic component of an electronic device. Gold has the second highest electrical conductivity after silver and copper, and is excellent in physical properties such as bondability by thermocompression bonding, and also in chemical properties such as oxidation resistance and chemical resistance. Therefore, despite the high cost of gold, it continues to be used as a joint pad for mounting boards. The electroless gold plating method is often used for such a mounting substrate pattern because there are restrictions on power supply leads and there is an independent pattern in which it is difficult to form a plating film.
置換金めっきは無電解金めっき法の一部として古くから知られている。置換金めっきは、金イオンの溶液中に金よりもイオン化傾向が卑な金属が存在すると、卑な金属の表面が溶液中に溶け出し、溶液中の金イオンが金金属として析出する原理を利用する技術である。 Replacement gold plating has long been known as part of the electroless gold plating method. Substitution gold plating utilizes the principle that when a metal with a lower ionization tendency than gold exists in the solution of gold ions, the surface of the base metal dissolves in the solution and the gold ions in the solution precipitate as gold metal. It is a technology to do.
置換金めっきは、金イオンが下地金属と置換して金金属が析出するという反応機構上、厚付けが困難である。厚付けをしようとして過度に浸漬時間を延長させると、膜厚ばらつきが大きくなると共に下地金属であるニッケル中間層の腐食が拡張するという欠点があった。このため無電解金めっきの処理方法では、置換型と自己触媒型（還元型）の二段処理を行うか、あるいは、液管理が困難ながらも、置換・自己触媒併用型（還元併用型）の一段処理を行う必要があった。 Replacement gold plating is difficult to thicken due to the reaction mechanism in which gold ions replace the base metal and gold metal is deposited. If the immersion time is excessively extended in an attempt to thicken the film, there is a drawback that the film thickness variation becomes large and the corrosion of the nickel intermediate layer, which is the base metal, expands. For this reason, in the electroless gold plating treatment method, a two-stage treatment of a substitution type and an autocatalytic type (reduction type) is performed, or a substitution / autocatalytic combination type (reduction combination type) is used although liquid management is difficult. It was necessary to perform one-step processing.
近年、電子機器の高機能化や多機能化が進展し、電子部品に用いられる実装基板の高密度化が進み、接合部パッドの微細化により電源リードの形成が更に困難になり、無電解金めっき技術の必要性が更に高まっている。しかしながら、置換金めっきは、上述したように、厚付けが困難であることから実用化が見送られていた。そして、置換金めっきプロセスは、置換型と自己触媒型の二段処理、または置換・自己触媒併用型の一段処理に取って代わられていた。ところが、生産拠点が日本国内からアジアの新興国に移行するのに伴って、ランニングコストの低減が求められ、作業性などについても重視されるようになったことから、置換金めっきプロセスが改めて見直されている。 In recent years, electronic devices have become more sophisticated and multifunctional, the density of mounting substrates used for electronic components has increased, and the miniaturization of joint pads has made it even more difficult to form power supply leads, resulting in electroless gold. The need for plating technology is increasing. However, as described above, the replacement gold plating has not been put into practical use because it is difficult to thicken it. The replacement gold plating process has been replaced by a two-step treatment of a substitution type and an autocatalytic type, or a one-step treatment of a substitution / autocatalytic combination type. However, as the production bases moved from Japan to emerging countries in Asia, it was required to reduce running costs, and workability was also emphasized, so the replacement gold plating process was reviewed again. It has been.
実装基板の接合部パッドに用いられる置換金めっきプロセスには、次の３種類の方法が知られている。すなわち、（１）銅上に直接置換金めっき皮膜を形成する直接置換金（Ｄｉｒｅｃｔ Ｉｍｍｅｒｓｉｏｎ Ｇｏｌｄ：ＤＩＧ）法、（２）下地無電解ニッケルめっき皮膜上に、置換金めっき皮膜を形成する無電解ニッケル／置換金（Ｅｌｅｃｔｒｏｌｅｓｓ Ｎｉｃｋｅｌ Iｍｍｅｒｓｉｏｎ Ｇｏｌｄ：ＥＮＩＧ）法、および（３）下地無電解ニッケルめっき皮膜と置換金めっき皮膜の間に無電解パラジウムめっき皮膜を設ける無電解ニッケル／無電解パラジウム／置換金（Ｅｌｅｃｔｒｏｌｅｓｓ Ｎｉｃｋｅｌ Ｅｌｅｃｔｒｏｌｅｓｓ Ｐａｌｌａｄｉｕｍ Ｉｍｍｅｒｓｉｏｎ Ｇｏｌｄ：ＥＮＥＰＩＧ）法である。 The following three types of methods are known for the replacement gold plating process used for the joint pad of the mounting substrate. That is, (1) the direct imaging gold (DIG) method for forming a direct substitution gold plating film on copper, and (2) the electroless nickel forming a substitution gold plating film on the base electroless nickel plating film. / Electroless Nickel Immersion Gold (ENIG) method, and (3) Electroless nickel / Electroless palladium / Electroless metal that provides an electroless palladium plating film between the base electroless nickel plating film and the replacement gold plating film. Nickel Electroless Palladium Imaging Gold (ENEPIG) method.
このうち（３）のＥＮＥＰＩＧ法では、ニッケルめっき皮膜は、銅回路が半田に浸食されないための半田バリア膜として使用され、パラジウムめっき皮膜は、ニッケルめっき皮膜が金めっき皮膜へ拡散するのを防止するための拡散バリア膜として使用される。そして、電気抵抗が低く、半田濡れ性が良好な金めっき皮膜が最終仕上げに適用される。したがって、ニッケル、パラジウムからなるパラジウム中間層／ニッケル中間層の積層構造のめっき皮膜と表層の金めっき皮膜とによって、半田付けやワイヤーボンディングなどの接合特性の優れた接合部を形成できる利点がある。 Of these, in the ENEPIG method of (3), the nickel plating film is used as a solder barrier film to prevent the copper circuit from being eroded by the solder, and the palladium plating film prevents the nickel plating film from diffusing into the gold plating film. Used as a diffusion barrier film for Then, a gold plating film having low electrical resistance and good solder wettability is applied to the final finish. Therefore, there is an advantage that a joint portion having excellent bonding characteristics such as soldering and wire bonding can be formed by a plating film having a laminated structure of a palladium intermediate layer / nickel intermediate layer composed of nickel and palladium and a gold plating film on the surface layer.
例えば、特許文献１（特開２０１２−４６７９２号公報）には「導電性金属からなる導体層上に、ニッケル層、パラジウム層、金層を順次積層してなる接合部を形成するための置換金めっき液であって、置換金めっき液は、シアン化金塩、錯化剤、銅化合物を含有するものであり、置換金めっき液中の錯化剤と銅化合物とのモル比が錯化剤／銅イオン＝１．０〜５００の範囲であり、錯化剤と銅化合物とから形成される化合物のｐＨ４〜６における安定度定数が８．５以上であることを特徴とする置換金めっき液」（特許請求の範囲請求項１）が開示されている。この置換金めっきは、「接合部を形成する部分が大小様々な面積のパッドを有する基板であっても、各パッドに形成した接合部の金層膜厚のバラツキが抑制でき、均一な厚みの金めっきの被膜を実現できる置換金めっき処理技術を提供する」（０００９段落）ものである。 For example, Patent Document 1 (Japanese Unexamined Patent Publication No. 2012-46792) states that "a replacement metal for forming a joint portion formed by sequentially laminating a nickel layer, a palladium layer, and a gold layer on a conductor layer made of a conductive metal. The plating solution contains a gold cyanide salt, a complexing agent, and a copper compound, and the molar ratio of the complexing agent to the copper compound in the replacement gold plating solution is the complexing agent. / Copper ion = 1.0 to 500, and the stability constant of the compound formed from the complexing agent and the copper compound at pH 4 to 6 is 8.5 or more. (Claim 1 of the scope of patent claims) is disclosed. In this replacement gold plating, "even if the portion forming the joint portion has pads of various sizes, the variation in the gold layer thickness of the joint portion formed on each pad can be suppressed, and the thickness is uniform. Provided is a replacement gold plating treatment technique capable of realizing a gold plating film ”(paragraph 0009).
このＥＮＥＰＩＧ法において、置換金めっきの様々な膜厚仕様に適用させるため、金の膜厚を高めることが要求される。しかし、金の析出膜厚を高めようとして処理時間を延長させたり、液温を上昇させたりすると、金の膜厚ばらつきが大きくなるという新たな欠点が露呈した。これは、貴なパラジウム金属の方が上層にあり、卑なニッケル金属の方が下層に存在するため、腐食が不安定になる傾向が生じるためである。更に、微細な接合部パッドになればなるほど、下層のニッケル中間層の異常腐食が進行して、半田接合やワイヤーボンディング接合を低下させるという深刻な課題へと繋がっていくことがわかった。 In this ENEPIG method, it is required to increase the film thickness of gold in order to apply it to various film thickness specifications of replacement gold plating. However, if the treatment time is extended or the liquid temperature is raised in an attempt to increase the deposited film thickness of gold, a new drawback is exposed that the variation in the film thickness of gold becomes large. This is because the noble palladium metal is in the upper layer and the base nickel metal is in the lower layer, which tends to make the corrosion unstable. Furthermore, it was found that the finer the joint pad, the more abnormal corrosion of the lower nickel intermediate layer progresses, leading to a serious problem of lowering solder bonding and wire bonding bonding.
本発明者らは先に、シアン化金化合物およびタリウム化合物を含むシアン系置換金めっき液であって、ｐＨが２．０〜４．４であること、および水酸基を有するアミノカルボン酸系キレート剤を含有することを特徴とする置換金めっき液を発明した。また、シアン化金化合物およびタリウム化合物を含む置換金めっき液であって、ｐＨが２．０〜４．４であり、水酸基を有するアミノカルボン酸系キレート剤を含有するシアン系置換金めっき液を用いて、銅、ニッケル、パラジウムのいずれかの中間層上、またはそれらの中間層からなる積層構造上に金表層を形成することを特徴とする置換金めっき方法を発明した（特許６５２１５５３号公報（後述する特許文献２））。特に、この置換金めっき方法の発明は、上記シアン系置換金めっき液を用いて銅金属上に無電解ニッケルめっき皮膜を形成し、更に無電解パラジウムめっき皮膜を形成した中間層からなる積層構造上に金表層を形成することを特徴とする。 The present inventors have previously prepared a cyanide-based gold plating solution containing a gold cyanide compound and a tallium compound, which has a pH of 2.0 to 4.4 and an aminocarboxylic acid-based chelating agent having a hydroxyl group. Invented a replacement gold plating solution, which is characterized by containing. Further, a replacement gold plating solution containing a gold cyanide compound and a tarium compound, which has a pH of 2.0 to 4.4 and contains an aminocarboxylic acid-based chelating agent having a hydroxyl group, is used. Invented (Patent No. 6521553), which comprises forming a gold surface layer on an intermediate layer of copper, nickel, or palladium, or on a laminated structure composed of the intermediate layers thereof (Patent No. 6521553). Patent Document 2)) described later. In particular, the invention of this substitution gold plating method is based on a laminated structure composed of an intermediate layer in which an electroless nickel plating film is formed on a copper metal using the cyan-based substitution gold plating solution, and an electroless palladium plating film is further formed. It is characterized by forming a gold surface layer.
これらの発明は、析出速度が速く、かつ、実装基板の接合部パッドの面積の差異に伴う膜厚ばらつきが小さい置換金めっき液および置換金めっき方法を提供することを目的としたものである。特に、従来ＥＮＥＰＩＧ法において、パラジウム中間層／ニッケル中間層の積層構造の上層のパラジウム中間層の腐食よりも下層のニッケル中間層の腐食比率が高いことを改善した、積層構造における下層のニッケル中間層の腐食が少ない置換金めっき液および置換金めっき方法を提供することを目的としたものである（同公報００１１段落） An object of these inventions is to provide a replacement gold plating solution and a replacement gold plating method in which the precipitation rate is high and the film thickness variation due to the difference in the area of the joint pad of the mounting substrate is small. In particular, in the conventional ENEPIG method, the corrosion ratio of the lower nickel intermediate layer is improved to be higher than the corrosion of the upper palladium intermediate layer of the laminated structure of the palladium intermediate layer / nickel intermediate layer, and the lower nickel intermediate layer in the laminated structure is improved. It is an object of the present invention to provide a replacement gold plating solution and a replacement gold plating method with less corrosion (paragraph 0011 of the same publication).
これらの発明は次の知見に基づくものである。すなわち、シアン系置換金めっき液における局部電池作用は、一般的に金＞パラジウム＞ニッケルの順で貴な金属であることが知られている。本発明者らが研究したところ、卑な金属である中間めっき層の腐食が溶液中のｐＨに大きく依存することがわかった。そして、本発明者らは、中性〜アルカリ性の溶液中で安定なシアン化金化合物を酸性側で不安定な化合物とすることによって、卑な金属の中間めっき層の腐食を抑制するとともに析出速度を向上させ、かつ、実装基板の接合部パッドの面積の差異に伴う膜厚ばらつきを小さくすることに成功したものである（同公報００１２段落）。 These inventions are based on the following findings. That is, it is known that the local battery action in the cyan-based substituted gold plating solution is generally a noble metal in the order of gold> palladium> nickel. As a result of research by the present inventors, it was found that the corrosion of the intermediate plating layer, which is a base metal, largely depends on the pH in the solution. Then, the present inventors suppress the corrosion of the intermediate plating layer of a base metal and the precipitation rate by converting the gold cyanide compound, which is stable in a neutral to alkaline solution, into an unstable compound on the acidic side. And succeeded in reducing the variation in film thickness due to the difference in the area of the joint pad of the mounting substrate (paragraph 0012 of the same publication).
特に、銅または銅合金パッド上の中間めっき層がパラジウム層とニッケル層の積層構造である場合、シアン系置換金めっき液における局部電池作用は、ｐＨが中性領域では金≒パラジウム＞ニッケルの傾向にあるが、他方、ｐＨが酸性領域では金＞パラジウム＞ニッケルの傾向になることがわかった。したがって、シアン系置換金めっき液を酸性領域とすることにより上層のパラジウム中間層の腐食比率を高くすることができ、それにより、ニッケル中間層の腐食の抑制、析出速度の向上、面積の差異に伴う膜厚ばらつきの低減が可能となる（同公報００１３段落）。 In particular, when the intermediate plating layer on the copper or copper alloy pad has a laminated structure of a palladium layer and a nickel layer, the local battery action in the cyan-based substituted gold plating solution tends to be gold ≈ palladium> nickel in the neutral pH region. On the other hand, it was found that the tendency of gold> palladium> nickel in the acidic region of pH. Therefore, by setting the cyanide-based gold plating solution in the acidic region, the corrosion ratio of the upper palladium intermediate layer can be increased, thereby suppressing the corrosion of the nickel intermediate layer, improving the precipitation rate, and increasing the area difference. It is possible to reduce the accompanying film thickness variation (paragraph 0013 of the same publication).
この置換金めっき液は、建浴した直後にめっき作業を開始すれば所望の結果が得られることは特許文献２に記載されたとおりである。しかしながら、この特許文献２に記載された置換金めっき液は、ｐＨが２．０〜４．４の酸性領域で用いるため液自体が不安定である。このため建浴後置換金めっき液を放置すると、置換金めっき液が自己分解し始めるという新たな課題のあることがわかった。 As described in Patent Document 2, the desired result can be obtained by starting the plating operation of this replacement gold plating solution immediately after the bath is built. However, the replacement gold plating solution described in Patent Document 2 is unstable because it is used in an acidic region having a pH of 2.0 to 4.4. Therefore, it was found that if the replacement gold plating solution is left unattended after the bath, there is a new problem that the replacement gold plating solution starts to self-decompose.
本発明は、置換金めっきにおける上記の課題に鑑みなされたものであり、建浴してから長期間放置しても自己分解しない、液保存性に優れた置換金めっき液を提供することを目的とする。また、本発明は、特許文献２に記載された発明と同様、めっき作業の開始からめっき作業が完了するまでの間の液安定性に優れ、また、析出速度が速く、かつ、実装基板の接合部パッドの面積の差異に伴う膜厚ばらつきが小さいシアン系置換金めっき液および置換金めっき方法を提供することを目的とする。特に、本発明は、液保存性に優れ、しかも、従来ＥＮＥＰＩＧ法において、パラジウム中間層／ニッケル中間層の積層構造の上層のパラジウム中間層の腐食よりも下層のニッケル中間層の腐食比率が高いことを改善した、積層構造における下層のニッケル中間層の腐食が少ない、液安定性が高い置換金めっき液および置換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 problems in substitution gold plating, and an object of the present invention is to provide a substitution gold plating solution having excellent liquid storage stability, which does not self-decompose even if it is left for a long period of time after being bathed. And. Further, as in the invention described in Patent Document 2, the present invention is excellent in liquid stability from the start of the plating operation to the completion of the plating operation, has a high precipitation rate, and joins the mounting substrate. It is an object of the present invention to provide a cyan-based replacement gold plating solution and a replacement gold plating method in which the thickness variation due to the difference in the area of the part pad is small. In particular, the present invention has excellent liquid storage stability, and in the conventional ENEPIG method, the corrosion ratio of the lower nickel intermediate layer is higher than that of the upper palladium intermediate layer of the laminated structure of the palladium intermediate layer / nickel intermediate layer. It is an object of the present invention to provide a replacement gold plating solution and a replacement gold plating method having high liquid stability with less corrosion of the lower nickel intermediate layer in a laminated structure.
本発明の置換金めっき液は、シアン化金化合物およびタリウム化合物を含むシアン系置換金めっき液において、ｐＨが２．０〜４．４であること、水酸基を有するアミノカルボン酸系キレート剤を含有すること、および保存剤としてマロノニトリルまたはスクシノニトリルを含有することを特徴とする。 The substituted gold plating solution of the present invention is a cyanide-based gold plating solution containing a gold cyanide compound and a tarium compound, which has a pH of 2.0 to 4.4 and contains an aminocarboxylic acid-based chelating agent having a hydroxyl group. It is characterized by the fact that it contains malononitrile or succinonitrile as a preservative.
また、本発明の置換金めっき液は、シアン化金化合物およびタリウム化合物を含むシアン系置換金めっき液において、ｐＨが２．０〜４．４であること、水酸基を有するアミノカルボン酸系キレート剤を含有すること、腐食抑制剤としてポリエチレングリコール（平均分子量２００〜２００００）、アミド硫酸またはアミド硫酸塩の少なくとも１種以上を含有すること、および保存剤としてマロノニトリルまたはスクシノニトリルを含有することを特徴とする。 Further, the substituted gold plating solution of the present invention is a cyanide-based gold plating solution containing a gold cyanide compound and a thalium compound, and has a pH of 2.0 to 4.4 and an aminocarboxylic acid-based chelating agent having a hydroxyl group. It is characterized by containing polyethylene glycol (average molecular weight 200 to 20000) as a corrosion inhibitor, at least one of amid sulfate or amid sulfate, and containing malononitrile or succinonitrile as a preservative. And.
本発明の置換金めっき方法は、シアン化金化合物およびタリウム化合物を含む置換金めっき液であって、ｐＨが２．０〜４．４であること、水酸基を有するアミノカルボン酸系キレート剤を含有すること、および保存剤としてマロノニトリルまたはスクシノニトリルを含有するシアン系置換金めっき液を用いて、銅、ニッケル、パラジウムのいずれかの中間層上、またはそれらの中間層からなる積層構造上に金表層を形成することを特徴とする。 The substitution gold plating method of the present invention is a substitution gold plating solution containing a gold cyanide compound and a tarium compound, which has a pH of 2.0 to 4.4 and contains an aminocarboxylic acid-based chelating agent having a hydroxyl group. And using a cyanide-based gold plating solution containing malononitrile or succinonitrile as a preservative, gold on an intermediate layer of copper, nickel, palladium, or on a laminated structure consisting of the intermediate layers. It is characterized by forming a surface layer.
また、本発明の置換金めっき方法は、シアン化金化合物およびタリウム化合物を含む置換金めっき液であって、ｐＨが２．０〜４．４であること、水酸基を有するアミノカルボン酸系キレート剤を含有すること、腐食抑制剤としてポリエチレングリコール（平均分子量２００〜２００００）、アミド硫酸またはアミド硫酸塩の少なくとも１種以上を含有すること、および保存剤としてマロノニトリルまたはスクシノニトリルを含有するシアン系置換金めっき液を用いて、銅、ニッケル、パラジウムのいずれかの中間層上、またはそれらの中間層からなる積層構造上に金表層を形成することを特徴とする。 Further, the substitution gold plating method of the present invention is a substitution gold plating solution containing a gold cyanide compound and a thalium compound, having a pH of 2.0 to 4.4, and an aminocarboxylic acid-based chelating agent having a hydroxyl group. Cyan-based substitution containing polyethylene glycol (average molecular weight 200 to 20000) as a corrosion inhibitor, at least one of amid sulfate or amid sulfate, and malononitrile or succinonitrile as a preservative. It is characterized in that a gold surface layer is formed on an intermediate layer of copper, nickel, or palladium, or on a laminated structure composed of the intermediate layers, using a gold plating solution.
特に、本発明の置換金めっき方法は、上記シアン系置換金めっき液を用いて、銅金属上に無電解ニッケルめっき皮膜を形成し、更に無電解パラジウムめっき皮膜を形成した中間層からなる積層構造上に金表層を形成することを特徴とする。 In particular, the substitution gold plating method of the present invention has a laminated structure composed of an intermediate layer in which an electroless nickel plating film is formed on a copper metal using the above cyan-based substitution gold plating solution, and an electroless palladium plating film is further formed. It is characterized by forming a gold surface layer on top.
本発明のシアン化金化合物およびタリウム化合物を含むシアン系置換金めっき液または置換金めっき方法において、上記めっき液のｐＨを２．０〜４．４とし、水酸基を有するアミノカルボン酸系キレート剤を含有することとした。これは、シアン化金化合物のシアンイオンと金イオンとの錯体の結合力を弱め、かつ、酸性領域で安定なマロノニトリル（ＣＨ２（ＣＮ）２）またはスクシノニトリル（Ｃ２Ｈ４（ＣＮ）２）のシアノ基を、金イオンまたは金金属に配位しやすくするとともに、穏やかな還元作用を有するキレート剤の析出機構によって全面均一な金金属皮膜を析出させるためである。 In the cyanide-based gold plating solution or the substitution gold plating method containing the gold cyanide compound and the tallium compound of the present invention, the pH of the plating solution is set to 2.0 to 4.4, and an aminocarboxylic acid-based chelating agent having a hydroxyl group is used. It was decided to contain it. This weakens the binding force of the complex of the cyanide and gold ions of the gold cyanide compound, and is stable in the acidic region, malononitrile (CH 2 (CN) 2 ) or succinonitrile (C 2 H 4 (CN)). This is because the cyano group of 2) can be easily coordinated with gold ions or gold metal, and a gold metal film having a uniform entire surface is precipitated by a precipitation mechanism of a chelating agent having a gentle reducing action.
本発明のシアン系置換金めっき液または置換金めっき方法において、金イオンは、一般的に０．１〜１０ｇ／Ｌを用いることができる。実用的な上限値は５ｇ／Ｌである。金地金の滞留を避けるためである。金イオン濃度の下限値未満では、置換速度が遅くなり十分な置換めっき層を形成しにくくなる。また、１０ｇ／Ｌの上限値は、高価な金地金が被めっき物に付着して水洗槽へ汲み出される（ドラッグアウト）などの無駄なコストを省くためである。実用的な観点からは、金イオンの濃度の上限値は、５ｇ／Ｌが好ましく、３ｇ／Ｌが特に好ましい。また、下限値は、析出皮膜の置換速度を速くするため０．５ｇ／Ｌが好ましく、０．８ｇ／Ｌが特に好ましい。 In the cyan-based substituted gold plating solution or the substituted gold plating method of the present invention, 0.1 to 10 g / L of gold ion can be generally used. The practical upper limit is 5 g / L. This is to avoid the retention of gold bullion. If the gold ion concentration is less than the lower limit, the substitution rate becomes slow and it becomes difficult to form a sufficient substitution plating layer. Further, the upper limit of 10 g / L is for eliminating unnecessary costs such as expensive gold bullion adhering to the object to be plated and being pumped out to the washing tank (drag out). From a practical point of view, the upper limit of the concentration of gold ions is preferably 5 g / L, and particularly preferably 3 g / L. The lower limit is preferably 0.5 g / L and particularly preferably 0.8 g / L in order to increase the replacement rate of the precipitated film.
本発明のシアン系置換金めっき液または置換金めっき方法においては、保存剤としてマロノニトリルまたはスクシノニトリルを添加する。これらの保存剤を添加する理由は、ｐＨの範囲が２．０〜４．４というシアン化金化合物の不安定な領域であっても、これらの保存剤がシアン化金化合物中のＣＮ基を安定させ自己分解を抑制する効果があるためである。これらの保存剤は、腐食抑制剤が存在しない場合でも、シアン化金化合物中のＣＮ基を長期間安定させることができる効果がある。この作用は次のように理解することができる。 In the cyanide-based gold-substituted gold plating solution or gold-substituted gold plating method of the present invention, malononitrile or succinonitrile is added as a preservative. The reason for adding these preservatives is that even in the unstable region of the gold cyanide compound in the pH range of 2.0 to 4.4, these preservatives add CN groups in the gold cyanide compound. This is because it has the effect of stabilizing and suppressing self-decomposition. These preservatives have the effect of stabilizing the CN groups in the gold cyanide compound for a long period of time even in the absence of a corrosion inhibitor. This action can be understood as follows.
すなわち、本発明の酸性シアン系置換金めっき液では、ｐＨが４．４以下でシアン化金化合物のシアンイオンと金イオンとの錯体の結合力を弱め、かつ、酸性領域で安定なマロノニトリル（ＣＨ２（ＣＮ）２）またはスクシノニトリル（Ｃ２Ｈ４（ＣＮ）２）のシアノ基を、金イオンまたは金金属に配位しやすくするためである。ＣＮ基の交換作用によりシアン系置換金めっき液の金化合物が液中で安定して存在することができる。また、この２個のＣＮ基の存在によってシアン系置換金めっき液が外部からの熱エネルギーや光エネルギーを受けても自己分解することがなくなる。また、シアン系置換金めっき液中で金金属化合物が安定して存在しているため、パラジウム金属よりも卑なニッケル金属の腐食が不安定になることがなくなる。 That is, in the acidic cyanide-based substituted gold plating solution of the present invention, the binding force of the complex of cyanide and gold ion of the gold cyanide compound is weakened at a pH of 4.4 or less, and malononitrile (CH) is stable in the acidic region. This is to facilitate coordination of the cyano group of 2 (CN) 2 ) or succinonitrile (C 2 H 4 (CN) 2) to gold ions or gold metals. The gold compound of the cyanide-based substituted gold plating solution can stably exist in the solution due to the exchange action of the CN group. Further, due to the presence of these two CN groups, the cyanide-based gold plating solution does not self-decompose even if it receives thermal energy or light energy from the outside. Further, since the gold metal compound is stably present in the cyanide-based substituted gold plating solution, the corrosion of nickel metal, which is more base than palladium metal, is not unstable.
マロノニトリルまたはスクシノニトリルの上記効果はシアン化金化合物に作用するので、シアン系置換金めっき液における腐食抑制剤の効果とは独立して作用する。腐食抑制剤と併用せずにマロノニトリルまたはスクシノニトリルを単独で用いると、０．０１ｇ／L以下でもシアン系置換金めっき液が自己分解しない効果がみられた。なお、２０ｇ／Lを超えてマロノニトリルまたはスクシノニトリルを添加しても、依然として自己分解の抑制効果が発揮された。 Since the above-mentioned effect of malononitrile or succinonitrile acts on the gold cyanide compound, it acts independently of the effect of the corrosion inhibitor in the cyanide-based gold plating solution. When malononitrile or succinonitrile was used alone without being used in combination with a corrosion inhibitor, the effect that the cyanide-based gold plating solution did not self-decompose was observed even at 0.01 g / L or less. Even if malononitrile or succinonitrile was added in excess of 20 g / L, the effect of suppressing autolysis was still exhibited.
本発明のシアン系置換金めっき液または置換金めっき方法においてはタリウム化合物を含有させる。タリウムイオンが存在すると、金イオンが金金属として析出する平衡電位よりも貴な電位領域で下地金属上に析出するというアンダーポテンシャル析出現象が起き、金めっき液の置換反応を促進することが知られている。本発明に係るｐＨが２．０〜４．４の領域でもタリウムイオンは有効に作用する。タリウムイオンは、一般的なシアン系置換金めっき液において用いられるタリウム化合物の濃度範囲である０．１〜１００ｍｇ／Ｌで用いることができる。 In the cyanide-based gold plating solution or the gold substitution method of the present invention, a tarium compound is contained. It is known that the presence of tallium ions causes an underpotential precipitation phenomenon in which gold ions are deposited on the base metal in a potential region noble than the equilibrium potential in which gold ions are deposited as gold metal, and promotes the substitution reaction of the gold plating solution. ing. Thallium ions act effectively even in the pH range of 2.0 to 4.4 according to the present invention. The thallium ion can be used in a concentration range of 0.1 to 100 mg / L of the thallium compound used in a general cyanide-based gold plating solution.
本発明のシアン系置換金めっき液または置換金めっき方法において、タリウム化合物の実質的な上限値はタリウムイオンとして８０ｍｇ／Ｌである。タリウム化合物は少量でも金めっき液の置換反応を促進することができる。ただし、タリウム化合物をタリウムイオンとして５ｍｇ／Ｌ以上加えても、置換反応の促進効果はタリウムイオンの濃度に比例して向上するわけではない。タリウム化合物は、様々な化合物として添加することができる。硫酸タリウム、酢酸タリウム、硝酸タリウム、ギ酸タリウムなどの水溶性タリウム塩が望ましい。 In the cyanide-based gold-substituted gold plating solution or the gold-substituted gold plating method of the present invention, the substantially upper limit of the thallium compound is 80 mg / L as thallium ions. Even a small amount of the thallium compound can accelerate the substitution reaction of the gold plating solution. However, even if the thallium compound is added as thallium ions in an amount of 5 mg / L or more, the effect of promoting the substitution reaction does not improve in proportion to the concentration of thallium ions. The thallium compound can be added as various compounds. Water-soluble thallium salts such as thallium sulfate, thallium acetate, thallium nitrate, and thallium formate are desirable.
本発明のシアン系置換金めっき液または置換金めっき方法において、ｐＨの下限値を２．０とした。これは、２．０未満ではシアン化金化合物のシアンイオンと金イオンとの錯体の結合力が弱くなりすぎて、置換金めっき液中で金金属が析出してしまい高価な金地金のロスが高くなるためである。また、ｐＨの上限値を４．４としたのは、４．４以上ではシアン化金化合物のシアンイオンと金イオンとの錯体の結合力が強くなりすぎるためである。結合力が強くなりすぎると、金金属が析出しにくくなって、パラジウム金属よりも卑なニッケル金属の腐食が不安定になる。このため、金皮膜の実装基板の接合部パッドの面積の差異で厚さがばらつくようになる。好ましい上限値は４．０であり、更に好ましくは３．８であり、最も好ましくは３．６である。また、好ましい下限値は２．２であり、更に好ましくは２．４であり、最も好ましくは２．６である。 In the cyan-based substituted gold plating solution or the substituted gold plating method of the present invention, the lower limit of pH was set to 2.0. This is because if it is less than 2.0, the binding force of the complex between the cyan ion and the gold ion of the gold cyanide compound becomes too weak, and the gold metal is precipitated in the substituted gold plating solution, resulting in the loss of expensive gold metal. This is because it will be expensive. Further, the upper limit of pH is set to 4.4 because the binding force of the complex of the cyanide and gold ions of the gold cyanide compound becomes too strong at 4.4 or more. If the bonding force becomes too strong, it becomes difficult for gold metal to precipitate, and the corrosion of nickel metal, which is more base than palladium metal, becomes unstable. Therefore, the thickness varies depending on the area of the joint pad of the gold film mounting substrate. The preferred upper limit is 4.0, more preferably 3.8, and most preferably 3.6. The lower limit is preferably 2.2, more preferably 2.4, and most preferably 2.6.
本発明のシアン系置換金めっき液または置換金めっき方法において、水酸基を有するアミノカルボン酸系キレート剤を金金属の析出作用を穏やかにするために含有させる。水酸基を有するアミノカルボン酸系キレート剤の含有量は０．１〜１００ｇ／Ｌである。水酸基を有するアミノカルボン酸系キレート剤の所定量を金イオンと共存させることによって、実装基板の接合部パッドの面積の差異に伴う膜厚ばらつきを抑制させることができる。下限値未満では、タリウムイオンを錯形成させることができず膜厚ばらつきが大きくなる。また、上限値を超えると、膜厚ばらつきに対する効果が頭打ちとなる。 In the cyan-based substituted gold plating solution or the substituted gold plating method of the present invention, an aminocarboxylic acid-based chelating agent having a hydroxyl group is contained in order to moderate the precipitation action of the gold metal. The content of the aminocarboxylic acid-based chelating agent having a hydroxyl group is 0.1 to 100 g / L. By coexisting a predetermined amount of the aminocarboxylic acid-based chelating agent having a hydroxyl group with the gold ion, it is possible to suppress the variation in film thickness due to the difference in the area of the joint pad of the mounting substrate. If it is less than the lower limit, thallium ions cannot be complexly formed and the film thickness variation becomes large. Further, when the upper limit value is exceeded, the effect on the film thickness variation reaches a plateau.
水酸基を有するアミノカルボン酸系キレート剤としては、ＤＨＥＧ（Ｄｉｈｙｄｒｏｘｙｅｔｈｙｌ Ｇｌｙｃｉｎｅ）、ＨＩＤＡ（Ｈｙｄｒｏｘｙｅｔｈｙｌ Ｉｍｉｎｏ Ｄｉａｃｅｔｉｃ Ａｃｉｄ）、ＨＥＤＴＡ（Ｈｙｄｒｏｘｙｅｔｈｙｌ Ｅｔｈｙｌｅｎｅ Ｄｉａｍｉｎｅ Ｔｒｉａｃｅｔｉｃ Ａｃｉｄ）、ＤＰＴＡ−ＯＨ（１、３−Ｄｉａｍｉｎｏ−２−ｈｙｄｒｏｘｙｐｒｏｐａｎｅ Ｔｅｔｒａａｃｅｔｉｃ Ａｃｉｄ）などが挙げられる。その中で最も有効なものはＨＥＤＴＡである。 Examples of the aminocarboxylic acid-based chelating agent having a hydroxyl group include DHEG (Dihydroxyethyl Glycine), HIDA (Hydroxythyl Imino Diacetic Acid), HEADTA (Hydroxyethyl EthyleneDiamineTacne-DiaceticAdiamineTri) ) And so on. The most effective of these is HEAD.
本発明のシアン系置換金めっき液または置換金めっき方法においては、更にｐＨ緩衝剤を添加することができる。ｐＨ緩衝剤を添加することにより、置換金めっき作業中のｐＨ２．０〜４．４の範囲をより安定的に保持することができ、ｐＨの範囲を２．０〜４．４の間で安定的に保持することによって、ＥＮＥＰＩＧ法であってもパラジウム金属の腐食が促進して、結果的に卑なニッケル金属の腐食が抑制できる。 In the cyan-based gold-substituted gold plating solution or the gold-substituted gold plating method of the present invention, a pH buffer can be further added. By adding a pH buffer, the pH range of 2.0 to 4.4 can be more stably maintained during the replacement gold plating operation, and the pH range is stable between 2.0 and 4.4. Even in the ENEPIG method, the corrosion of the palladium metal is promoted, and as a result, the corrosion of the base nickel metal can be suppressed.
具体的なｐＨ緩衝剤としては、リン酸、グリシン、シアノ酢酸、マロン酸、フタル酸、クエン酸、ギ酸、グリコール酸、乳酸、コハク酸、酢酸、酪酸、プロピオン酸、およびそれらの塩の少なくとも１種以上が挙げられる。この中では、マロン酸、マロン酸塩、ギ酸、ギ酸塩、酢酸または酢酸塩が好ましく、最も有効なものはマロン酸またはマロン酸塩である。これらの群から選択される少なくとも１種以上を合計で０．１〜１００ｇ／Ｌ含むことが好ましい。 Specific pH buffers include at least one of phosphoric acid, glycine, cyanoacetic acid, malonic acid, phthalic acid, citric acid, formic acid, glycolic acid, lactic acid, succinic acid, acetic acid, butyric acid, propionic acid, and salts thereof. More than seeds can be mentioned. Of these, malonic acid, malonate, formic acid, formate, acetic acid or acetate are preferred, with the most effective being malonic acid or malonate. It is preferable that at least one selected from these groups is contained in a total of 0.1 to 100 g / L.
本発明のシアン系置換金めっき液または置換金めっき方法においては、腐食抑制剤を更に添加することができる。腐食抑制剤を添加する理由は、ｐＨ緩衝剤と同様、置換金めっき作業中の卑な銅金属やニッケル金属の腐食をより抑制するためである。腐食抑制剤としては、ポリエチレングリコール（平均分子量２００〜２００００)が好ましい。置換金めっき作業中のｐＨ２．０〜４．４を安定的に保持するからである。また、アミド硫酸またはアミド硫酸塩も同様の効果を発揮することがわかった。これらの化合物を好ましくは１種もしくは２種以上合計で０．１〜１００ｇ／Ｌ含むことができる。 In the cyan-based substitution gold plating solution or the substitution gold plating method of the present invention, a corrosion inhibitor can be further added. The reason for adding the corrosion inhibitor is to further suppress the corrosion of the base copper metal and nickel metal during the replacement gold plating operation, as in the case of the pH buffer. As the corrosion inhibitor, polyethylene glycol (average molecular weight 200 to 20000) is preferable. This is because the pH of 2.0 to 4.4 during the replacement gold plating operation is stably maintained. It was also found that amidosulfate or amidosulfate exerts the same effect. These compounds can preferably be contained in an amount of 0.1 to 100 g / L in total of one type or two or more types.
本発明のシアン系置換金めっき液または置換金めっき方法において、めっき液のｐＨを調整するには、希硫酸などの無機酸や酢酸などの有機酸、あるいは水酸化アルカリを用いることができる。また液温は、高温になればなるほど金の析出速度は速くなるが、蒸発ロスも激しくなる。一般的には６０〜９０℃の範囲でめっき作業が行われる。 In the cyan-based substituted gold plating solution or the substituted gold plating method of the present invention, an inorganic acid such as dilute sulfuric acid, an organic acid such as acetic acid, or an alkali hydroxide can be used to adjust the pH of the plating solution. In addition, the higher the liquid temperature, the faster the gold precipitation rate, but the greater the evaporation loss. Generally, the plating operation is performed in the range of 60 to 90 ° C.
本発明のシアン系置換金めっき液には、建浴後長期間放置してもめっき液が自己分解することがなく液を保存できる液保存性の効果がある。更に、長期間放置後にめっき作業を開始しても、建浴直後と同様にばらつきのないめっき皮膜が得られるという効果もある。すなわち、本発明のシアン系置換金めっき液を用いると、めっき作業の開始時期にかかわらず、金金属の析出速度が速くなり、実装基板の接合部パッドの面積の差異に伴う膜厚ばらつきが小さい析出皮膜を形成させることができる。また、本発明のシアン系置換金めっき液によれば、パラジウム中間層／ニッケル中間層の積層構造における下層のニッケル中間層の腐食を少なくした置換金めっきの析出皮膜が形成される効果がある。 The cyan-based substituted gold plating solution of the present invention has a liquid storage effect that allows the solution to be stored without self-decomposition even when left for a long period of time after the construction bath. Further, even if the plating operation is started after being left for a long period of time, there is an effect that a plating film having no variation can be obtained as in the case immediately after the construction bath. That is, when the cyan-based substituted gold plating solution of the present invention is used, the precipitation rate of gold metal is increased regardless of the start time of the plating operation, and the film thickness variation due to the difference in the area of the joint pad of the mounting substrate is small. A precipitation film can be formed. Further, according to the cyan-based substituted gold plating solution of the present invention, there is an effect that a precipitation film of the substituted gold plating with less corrosion of the lower nickel intermediate layer in the laminated structure of the palladium intermediate layer / nickel intermediate layer is formed.
また、本発明のシアン系置換金めっき方法には、めっき作業の開始時期にかかわらず、中間層の腐食を抑制するとともに、速い析出速度で置換金めっき層を形成させる効果がある。更に、本発明のシアン系置換金めっき方法によれば、実装基板の接合部パッドの面積の差異に伴う膜厚ばらつきを小さくすることができる。また、本発明のシアン系置換金めっき方法によれば、パラジウム中間層／ニッケル中間層の積層構造上に金表層を形成させる場合、下層のニッケル中間層の腐食が低減されるという効果がある。 Further, the cyan-based substituted gold plating method of the present invention has the effect of suppressing corrosion of the intermediate layer and forming the substituted gold plating layer at a high precipitation rate regardless of the start time of the plating operation. Further, according to the cyan-based substituted gold plating method of the present invention, it is possible to reduce the variation in film thickness due to the difference in the area of the joint pad of the mounting substrate. Further, according to the cyan-based substituted gold plating method of the present invention, when the gold surface layer is formed on the laminated structure of the palladium intermediate layer / nickel intermediate layer, there is an effect that the corrosion of the nickel intermediate layer of the lower layer is reduced.
以下、本発明に係るシアン系置換金めっき液および置換金めっき方法の実施の形態を更に詳しく説明する。本発明の被めっき物としては、従来の置換金めっき方法と同様に特に制限はない。すなわち、各種金属材料、またプラスチックやセラミックなどの絶縁基材上に形成された銅などの金属皮膜（電気的に独立した回路を含む）の表面に用いることができる。 Hereinafter, embodiments of the cyanide-based gold plating solution and the gold substitution method according to the present invention will be described in more detail. The object to be plated of the present invention is not particularly limited as in the conventional replacement gold plating method. That is, it can be used for various metal materials and the surface of a metal film (including an electrically independent circuit) such as copper formed on an insulating base material such as plastic or ceramic.
本発明の置換金めっき工程を施す前の前処理工程は、従来の置換金めっき方法の場合と同様に、周知の前処理工程を用いることができる。例えば、基材の脱脂、ソフトエッチング、硫酸活性、パラジウム触媒付与などを行うことができる。また必要に応じて、前処理が施された各種金属材料、またプラスチックやセラミックなどの絶縁基材上に形成された銅などの接合部パッドの表面にニッケルめっき皮膜、パラジウムめっき皮膜などの中間層を成膜することができる。本発明の置換金めっき方法においては、銅、ニッケルまたはパラジウムからなる中間層上に金表層を形成することができる。 As the pretreatment step before performing the replacement gold plating step of the present invention, a well-known pretreatment step can be used as in the case of the conventional replacement gold plating method. For example, degreasing of the base material, soft etching, sulfuric acid activity, addition of a palladium catalyst and the like can be performed. If necessary, an intermediate layer such as a nickel plating film or a palladium plating film is formed on the surface of various pretreated metal materials or a joint pad such as copper formed on an insulating base material such as plastic or ceramic. Can be formed. In the replacement gold plating method of the present invention, a gold surface layer can be formed on an intermediate layer made of copper, nickel or palladium.
本発明に係るシアン系置換金めっき工程の析出条件は、従来の条件と大きな違いはない。めっき速度を向上させる観点から、液温はできるだけ高い方が好ましい。好ましくは８０℃以上であり、より好ましくは８５℃以上である。めっき時間は一般的に５〜３０分程度である。また、通常のＥＮＥＰＩＧ法ではニッケル中間層が０．０８〜８μｍの膜厚で形成され、パラジウム中間層は０．０３〜０．３μｍの膜厚で形成される。好ましい置換金めっき皮膜の膜厚は０．０３〜０．３μｍである。 The precipitation conditions of the cyanide-based gold plating step according to the present invention are not significantly different from the conventional conditions. From the viewpoint of improving the plating speed, it is preferable that the liquid temperature is as high as possible. It is preferably 80 ° C. or higher, and more preferably 85 ° C. or higher. The plating time is generally about 5 to 30 minutes. Further, in the usual ENEPIG method, the nickel intermediate layer is formed with a film thickness of 0.08 to 8 μm, and the palladium intermediate layer is formed with a film thickness of 0.03 to 0.3 μm. The film thickness of the preferred replacement gold plating film is 0.03 to 0.3 μm.
本発明の置換金めっき液によって金皮膜を形成した後、熱処理を行うことができる。熱処理は、周知の置換金めっき方法の後処理工程で行うことができる。例えば、バッチ式の熱処理炉、開放型のトンネル炉、雰囲気をコントロールできるオートクレーブ炉などを用いることができる。熱処理を施すと、膨れのない置換金めっき皮膜を安定して得ることができる。 After forming a gold film with the replacement gold plating solution of the present invention, heat treatment can be performed. The heat treatment can be performed in a post-treatment step of a well-known replacement gold plating method. For example, a batch type heat treatment furnace, an open tunnel furnace, an autoclave furnace capable of controlling the atmosphere, and the like can be used. When the heat treatment is applied, a gold-plated gold plating film without swelling can be stably obtained.
以下、実施例、参考例、および比較例を挙げて、本発明をより具体的に説明するが、下記実施例に本発明が限定されるものではないのは勿論である。
なお、参考例は、本発明者らの先のシアン系置換金めっき液および置換金めっき方法の発明（前述の特許文献２）における実施例であり、先の発明と比べた本発明の効果をより明確にするために記載するものである。
Hereinafter, the present invention will be described in more detail with reference to Examples, Reference Examples, and Comparative Examples, but it goes without saying that the present invention is not limited to the following Examples.
The reference example is an example in the invention of the above-mentioned cyan-based substituted gold plating solution and the substituted gold plating method (Patent Document 2 described above) of the present inventors, and the effect of the present invention as compared with the previous invention is exhibited. It is described for the sake of clarity.
（実施例１〜５、参考例１〜１５）
置換金めっきを行ったテストピースは、ガラス繊維で強化されたエポキシ樹脂製の実装基板（３０ｍｍ×２０ｍｍ×厚さ１ｍｍ）を使用して、次のように前処理を行った。なお、この実装基板の表面には、独立した３種類の銅パッド（０．４ｍｍ×０．４ｍｍ□、０．８ｍｍ×０．８ｍｍ□、３．０ｍｍ×３．０ｍｍ□）と、銅回路（１００μｍ幅）で接続された３種類の銅パッド（０．４ｍｍ×０．４ｍｍ□、０．８ｍｍ×０．８ｍｍ□、３．０ｍｍ×３．０ｍｍ□）の合計６種類の銅パッドが形成されている。
(Examples 1 to 5, Reference Examples 1 to 15)
The test piece subjected to the replacement gold plating was pretreated as follows using a mounting substrate (30 mm × 20 mm × thickness 1 mm) made of epoxy resin reinforced with glass fiber. In addition, on the surface of this mounting substrate, three types of independent copper pads (0.4 mm × 0.4 mm □, 0.8 mm × 0.8 mm □, 3.0 mm × 3.0 mm □) and a copper circuit ( A total of 6 types of copper pads are formed, including 3 types of copper pads (0.4 mm x 0.4 mm □, 0.8 mm x 0.8 mm □, 3.0 mm x 3.0 mm □) connected by a width of 100 μm). ing.
酸性脱脂（日本エレクトロプレイティング・エンジニヤース株式会社（以下「ＥＥＪＡ」と略す）製・イートレックス１５、４５℃、５分）、ソフトエッチング（三菱ガス化学株式会社製・ＮＰＥ−３００、２５℃、１分）、硫酸活性（１０％硫酸、２５℃、１分）、パラジウム触媒付与（ＥＥＪＡ製・レクトロレスＡＣ２、２５℃、１分）、無電解ニッケルめっき（ＥＥＪＡ製・レクトロレスＮＰ７６００、８５℃、２７分、Ｎｉ５μｍ）、無電解パラジウムめっき（ＥＥＪＡ製・レクトロレスＰｄ２０００Ｓ、５２℃、１０分、Ｐｄ０．１μｍ）を行った。 Acid degreasing (manufactured by Nippon Electroplating Engineers Co., Ltd. (hereinafter abbreviated as "EEJA"), Eatrex 15, 45 ° C, 5 minutes), soft etching (manufactured by Mitsubishi Gas Chemical Co., Ltd., NPE-300, 25 ° C, 1 minute), sulfuric acid activity (10% sulfuric acid, 25 ° C, 1 minute), palladium catalyst addition (EEJA Rectroless AC2, 25 ° C, 1 minute), electroless nickel plating (EEJA Rectroless NP7600, 85 ° C, 27) Minutes, Ni 5 μm), electroless palladium plating (manufactured by EEJA, Lectroless Pd2000S, 52 ° C., 10 minutes, Pd 0.1 μm) was performed.
次に、実施例１〜５、参考例１〜１５として、表１に示すシアン系置換金めっき液組成と処理条件で、この実装基板のパラジウム中間層／ニッケル中間層の積層構造上に置換金めっきを行った。 Next, as Examples 1 to 5 and Reference Examples 1 to 15, the substitution gold was applied on the laminated structure of the palladium intermediate layer / nickel intermediate layer of this mounting substrate under the cyanide-based gold plating solution composition and treatment conditions shown in Table 1. Plating was performed.
表１に示す実施例１〜５、参考例１〜１５の置換金めっきに用いたシアン系置換金めっき液の性状、置換金めっきにより形成された金皮膜の膜厚、膜厚ばらつき、および置換金めっきによる下地のニッケル皮膜の腐食について表２にまとめた。 Properties of the cyan-based substituted gold plating solution used for the replacement gold plating of Examples 1 to 5 and Reference Examples 1 to 15 shown in Table 1, the film thickness of the gold film formed by the substitution gold plating, the variation in film thickness, and the substitution. Table 2 summarizes the corrosion of the underlying nickel film due to gold plating.
＜液保存性＞
表１に示すシアン系置換金めっき液組成と条件で、建浴後放置し、置換金めっき液の自己分解（金沈殿物または容器内壁への金析出）が目視確認されるまでの時間、日数を調べた。それにより、建浴後１２時間以内に分解したものをバツ印（×）、１２時間〜２４時間以内に分解したものを三角印（△）、１日〜７日間以内に分解したものを丸印（〇）、７日間経過後も分解しなかったものを二重丸印（◎）で評価した。
実施例１〜５において、実施例２の置換金めっき液は、保存剤の含有量が他のものと比べて少ないことから丸印（〇）となりやや劣るものの、他は二重丸印（◎）であり、いずれも優れた液保存性を示すものであるといえる。なお、実施例２は、腐食抑制剤と併用せずにマロノニトリルを用いた例であり、単独であっても自己分解の抑制効果が発揮されることがみてとれる。
これに対して、保存剤を含有しない参考例１〜１５の置換金めっき液は、金めっき液を建浴後１日経過すると、すべてのめっき浴で金沈殿物または容器内壁への金析出が目視確認されバツ印（×）または三角印（△）となり、実施例１〜５のものと比較して液保存性に劣ることがわかる。これらの金沈殿物や容器内壁への金析出物は置換金めっき液の自己分解によるものである。自己分解は時間の経過とともに進行していく傾向を示す。このような置換金めっき液では、建浴直後のめっき作業が安定していても高価な金地金が浪費される結果、還元金粉の付着率を下げる一因となる。
<Liquid storage stability>
Under the cyan-based substituted gold plating solution composition and conditions shown in Table 1, the time and number of days until the self-decomposition (gold precipitate or gold precipitation on the inner wall of the container) of the substituted gold plating solution is visually confirmed after being left in the bath. Examined. As a result, those decomposed within 12 hours after bathing are marked with a cross (x), those decomposed within 12 to 24 hours are marked with a triangle (△), and those decomposed within 1 to 7 days are marked with a circle (circle). 〇), those that did not decompose even after 7 days were evaluated by double circles (◎).
In Examples 1 to 5, the replacement gold plating solution of Example 2 has a circle mark (○) because the content of the preservative is smaller than that of the others, and is slightly inferior, but the others are double circle marks (◎). ), And it can be said that all of them show excellent liquid storage stability. In addition, Example 2 is an example in which malononitrile was used without being used in combination with a corrosion inhibitor, and it can be seen that the effect of suppressing autolysis is exhibited even when it is used alone.
On the other hand, in the replacement gold plating solutions of Reference Examples 1 to 15 that do not contain a preservative, gold deposits or gold deposits on the inner wall of the container are visually observed in all the plating baths one day after the gold plating solution is built. It was confirmed that the marks were crossed (x) or triangular (Δ), indicating that the liquid storage stability was inferior to that of Examples 1 to 5. These gold precipitates and gold precipitates on the inner wall of the container are due to autolysis of the replacement gold plating solution. Autolysis tends to progress over time. In such a replacement gold plating solution, even if the plating operation immediately after the bath is stable, the expensive gold bullion is wasted, which contributes to lowering the adhesion rate of the reduced gold powder.
＜液安定性＞
金めっき液を建浴直後に置換金めっき作業を行い、めっき作業後の置換金めっき液を目視で観察して、金沈殿物と容器内壁への金析出がないものを丸印（〇）、金沈殿物や容器内壁への金析出のあったものをバツ印（×）で評価した。
実施例１〜５、参考例１〜１５において、表２に示されるように、いずれも金沈殿物と容器内壁への金析出がみられず、丸印（〇）となっている。すなわち、実施例１〜５、参考例１〜１５の置換金めっき液は、置換金めっき作業の開始から終了までのめっき液の安定性に優れていることがわかる。
<Liquid stability>
Substitution gold plating work is performed on the gold plating solution immediately after the construction bath, and the gold plating solution after the plating work is visually observed, and those without gold deposits and gold deposits on the inner wall of the container are marked with a circle (○). Gold deposits and gold deposits on the inner wall of the container were evaluated with a cross (x).
In Examples 1 to 5 and Reference Examples 1 to 15, as shown in Table 2, neither gold precipitate nor gold precipitate on the inner wall of the container was observed, and the marks are circled (◯). That is, it can be seen that the replacement gold plating solutions of Examples 1 to 5 and Reference Examples 1 to 15 are excellent in the stability of the plating solution from the start to the end of the replacement gold plating operation.
＜平均膜厚＞＜膜厚ばらつき＞
独立した３種類の銅パッドと銅回路で接続された３種類の銅パッドの計６種類の銅パッドに形成した置換金めっき皮膜の膜厚を、蛍光Ｘ線膜厚計（エスアイアイ・ナノテクノロジー株式会社製・ＳＦＴ−９５５０）で測定した。この測定結果から実施例１〜５、参考例１〜１５の平均膜厚と膜厚ばらつきを算出し、表２にその結果を示す。平均膜厚、膜厚ばらつきの評価は、平均膜厚が０．１μｍ未満のものは、ワイヤーボンディングの信頼性が不適であるからバツ印（×）と、また、膜厚ばらつきが２０％を超えるものは、ワイヤーボンディングの信頼性が不安定になりやすくなるためバツ印（×）とした。
<Average film thickness><Variation of film thickness>
The film thickness of the replacement gold plating film formed on a total of 6 types of copper pads, 3 types of independent copper pads and 3 types of copper pads connected by a copper circuit, is measured by a fluorescent X-ray film thickness meter (SI Nanotechnology). It was measured by SFT-9550) manufactured by SFT Co., Ltd. From this measurement result, the average film thickness and the film thickness variation of Examples 1 to 5 and Reference Examples 1 to 15 were calculated, and the results are shown in Table 2. As for the evaluation of the average film thickness and the film thickness variation, those with an average film thickness of less than 0.1 μm are marked with a cross (x) because the reliability of wire bonding is unsuitable, and the film thickness variation exceeds 20%. Those marked with a cross (x) because the reliability of wire bonding tends to be unstable.
実施例１〜５の平均膜厚は０．１６μｍ〜０．２１μｍの範囲にあることから、めっき析出速度が速いことがわかる。また、膜厚ばらつきは９．１％〜１６．３％の範囲にあり、Ｎｉ腐食性も少ないことが示唆される。実施例１〜５の平均膜厚、膜厚ばらつきは、参考例１〜１５の平均膜厚、膜厚ばらつきと比べても遜色のないものである。
このことから、実施例１〜５、参考例１〜１５の置換金めっき液はいずれも、置換金めっき作業の開始から終了までのめっき液の安定性に優れ、しかも、析出速度が速く、かつ、実装基板の接合パッドの面積の差異があっても膜厚ばらつきが小さい析出皮膜を得られたことがわかる。
Since the average film thickness of Examples 1 to 5 is in the range of 0.16 μm to 0.21 μm, it can be seen that the plating deposition rate is high. Further, the film thickness variation is in the range of 9.1% to 16.3%, suggesting that the Ni corrosiveness is also small. The average film thickness and film thickness variation of Examples 1 to 5 are comparable to the average film thickness and film thickness variation of Reference Examples 1 to 15.
From this, the replacement gold plating solutions of Examples 1 to 5 and Reference Examples 1 to 15 are all excellent in the stability of the plating solution from the start to the end of the replacement gold plating work, and the precipitation rate is high. It can be seen that a precipitated film having a small variation in film thickness was obtained even if there was a difference in the area of the bonding pad of the mounting substrate.
＜ニッケル腐食性＞
置換金めっきされた実装基板を金剥離剤（ＥＥＪＡ製・ゴールドストリッパー・コンセントレイトＮ、２５℃、３０秒）を用いて置換金めっき層のみを剥離して、下地金属（パラジウム中間層／ニッケル中間層／銅パッドの積層構造）の表面を露呈させた。その後、走査型電子顕微鏡（株式会社・日立ハイテクノロジーズ製・Ｓ−４７００、２０ｋＶ、×１００００）を用いて下地金属の腐食状況を確認した。
ニッケル中間層がパラジウム中間層よりも優先的に腐食されるというニッケル優先腐食が観察されなかったものを丸印（〇）、ニッケル優先腐食が観察されたものをバツ印（×）で評価した。
<Nickel corrosive>
Only the replacement gold plating layer is peeled off using a gold stripping agent (made by EEJA, Gold Stripper Concentrate N, 25 ° C., 30 seconds) on the mounting substrate plated with the replacement gold, and the base metal (palladium intermediate layer / nickel intermediate layer) is peeled off. / The surface of the laminated structure of copper pads) was exposed. Then, the corrosion state of the base metal was confirmed using a scanning electron microscope (S-4700, 20 kV, × 10000 manufactured by Hitachi High-Technologies Corporation).
Those in which nickel-priority corrosion was not observed, in which the nickel intermediate layer was preferentially corroded over the palladium intermediate layer, were evaluated with a circle (◯), and those in which nickel-priority corrosion was observed were evaluated with a cross (x).
具体的な例として図１を示す。
図１は、実施例３の置換金めっき層のみを剥離して、下地金属の表面を露呈させたものである。パラジウムめっき皮膜に形成した略四角形の細かな粒界（０．５μｍ×０．５μｍ）と下層のニッケルめっき皮膜に形成した略四角形の大きな粒界（５μｍ×５μｍ）が観察される。置換金めっきは、液中の金イオンと金よりも卑な下地金属との電位差によって進行するので、これらの粒界模様は下地金属が置換反応によって腐食された痕跡を示すものである。図１に示すパラジウムめっき皮膜は強固な皮膜強度を有していた。
FIG. 1 is shown as a specific example.
FIG. 1 shows the surface of the base metal exposed by peeling off only the replacement gold plating layer of Example 3. Fine quadrangular grain boundaries (0.5 μm × 0.5 μm) formed on the palladium plating film and large quadrangular grain boundaries (5 μm × 5 μm) formed on the underlying nickel plating film are observed. Since the replacement gold plating proceeds by the potential difference between the gold ions in the liquid and the base metal which is lower than gold, these grain boundary patterns show traces of the base metal being corroded by the substitution reaction. The palladium-plated film shown in FIG. 1 had a strong film strength.
図１に示すパラジウムめっき皮膜には、細かな腐食パターンが観察されることから、実施例３の置換金めっき液では、パラジウムめっき皮膜が全面で比較的均一に置換されたことが示唆される。パラジウムめっき皮膜が腐食された分だけ相対的にニッケルめっき皮膜の腐食が少なくなるため、ニッケルめっき皮膜に形成した略四角形の大きな粒界を示す境界線は、これまでの置換金めっき液から得られたものよりも、薄く細くなっている。すなわち、パラジウムめっき皮膜の腐食と、パラジウムめっき皮膜のピンホールやクラック等から侵入しためっき液によるニッケルめっき皮膜の腐食が同時進行してニッケルめっき皮膜の腐食が少なくなっていることがわかる。 Since a fine corrosion pattern is observed in the palladium plating film shown in FIG. 1, it is suggested that the palladium plating film was relatively uniformly replaced in the entire surface of the gold plating solution of Example 3. Since the corrosion of the nickel plating film is relatively reduced by the amount of corrosion of the palladium plating film, the boundary line showing the large grain boundary of the substantially square shape formed on the nickel plating film can be obtained from the conventional replacement gold plating solution. It is thinner and thinner than the plating. That is, it can be seen that the corrosion of the palladium plating film and the corrosion of the nickel plating film due to the plating solution invading from the pinholes and cracks of the palladium plating film proceed simultaneously, and the corrosion of the nickel plating film is reduced.
他の実施例の置換金めっき皮膜も実施例３と同様にして調べた。その結果、実施例１〜５の置換金めっき皮膜は、いずれもニッケル中間層がパラジウム中間層よりも優先的に腐食されるという顕著なニッケル優先腐食は観察されなかった。これにより表２中の「Ｎｉ腐食性」の項目は丸印（〇）で示される。 The replacement gold plating film of another example was also examined in the same manner as in Example 3. As a result, no remarkable nickel-priority corrosion in which the nickel intermediate layer was preferentially corroded over the palladium intermediate layer was not observed in any of the substituted gold plating films of Examples 1 to 5. As a result, the item of "Ni corrosiveness" in Table 2 is indicated by a circle (○).
また、参考例１〜１５における具体例として図２を示す。
図２は、参考例２の置換金めっき層のみを剥離して、下地金属の表面を露呈させたものである。図１と同様に、パラジウムめっき皮膜に形成した略四角形の細かな粒界（０．５μｍ×０．５μｍ）と下層のニッケルめっき皮膜に形成した略四角形の大きな粒界（５μｍ×５μｍ）が観察される。このことから、参考例１〜１５のシアン系置換金めっき液であっても、実施例１〜５の腐食状況と同様に、パラジウム中間層／ニッケル中間層の積層構造における下層のニッケル中間層の腐食が極めて少ない置換金めっきの析出皮膜を形成することができたことがわかる。したがって、実施例１〜５と同様に、表２中の「Ｎｉ腐食性」の項目は丸印（〇）で示される。
Further, FIG. 2 is shown as a specific example in Reference Examples 1 to 15.
FIG. 2 shows the surface of the base metal exposed by peeling off only the replacement gold plating layer of Reference Example 2. Similar to FIG. 1, fine quadrangular grain boundaries (0.5 μm × 0.5 μm) formed on the palladium plating film and large quadrangular grain boundaries (5 μm × 5 μm) formed on the underlying nickel plating film are observed. Will be done. From this, even with the cyan-based substituted gold plating solutions of Reference Examples 1 to 15, the nickel intermediate layer of the lower layer in the laminated structure of the palladium intermediate layer / nickel intermediate layer is similar to the corrosion state of Examples 1 to 5. It can be seen that a precipitation film of replacement gold plating with extremely little corrosion could be formed. Therefore, as in Examples 1 to 5, the item of "Ni corrosiveness" in Table 2 is indicated by a circle (◯).
（比較例１〜５）
実施例１〜５、参考例１〜１５と同様にして、表３に示す液組成と条件で比較例１〜５の置換金めっきを行った。すなわち、実施例、参考例と同様のテストピースを使用して前処理を行い、パラジウム中間層／ニッケル中間層の積層構造を形成した後、表３に示す比較例１〜５のシアン系置換金めっき液組成と条件で置換金めっきを行った。
(Comparative Examples 1 to 5)
Substitution gold plating of Comparative Examples 1 to 5 was performed under the liquid composition and conditions shown in Table 3 in the same manner as in Examples 1 to 5 and Reference Examples 1 to 15. That is, after pretreatment using the same test pieces as in Examples and Reference Examples to form a laminated structure of palladium intermediate layer / nickel intermediate layer, the cyanated substitution gold of Comparative Examples 1 to 5 shown in Table 3 is formed. Substitution gold plating was performed under the plating solution composition and conditions.
ここで、比較例１〜５の置換金めっき液の組成は、実施例１〜５のものと比べ保存剤を含有しないほか、次の点で相違している。
比較例１：タリウム化合物を含まない。
比較例２：水酸基を有するアミノカルボン酸系キレート剤を含有しない。
比較例３：水酸基を有するアミノカルボン酸系キレート剤の代わりに、還元剤としてアスコルビン酸を用いている。
比較例４：ｐＨが下限値の２．０を下回っている。
比較例５：ｐＨが上限値の４．４を上回っている。
Here, the compositions of the replacement gold plating solutions of Comparative Examples 1 to 5 do not contain a preservative as compared with those of Examples 1 to 5, and are different in the following points.
Comparative Example 1: Does not contain a thallium compound.
Comparative Example 2: Does not contain an aminocarboxylic acid-based chelating agent having a hydroxyl group.
Comparative Example 3: Ascorbic acid is used as a reducing agent instead of the aminocarboxylic acid-based chelating agent having a hydroxyl group.
Comparative Example 4: The pH is below the lower limit of 2.0.
Comparative Example 5: The pH exceeds the upper limit of 4.4.
表３に示す比較例１〜５の置換金めっきに用いたシアン系置換金めっき液の性状、置換金めっきにより形成された金皮膜の膜厚、膜厚ばらつき、および置換金めっきによる下地のニッケル皮膜の腐食について表４にまとめた。 Properties of the cyan-based substitution gold plating solution used for the substitution gold plating of Comparative Examples 1 to 5 shown in Table 3, the film thickness of the gold film formed by the substitution gold plating, the variation in the film thickness, and the nickel undercoat by the substitution gold plating. Table 4 summarizes the corrosion of the film.
表４から明らかなように、比較例１〜５のシアン系置換金めっき液では、液保存性が悪いことがわかる。また、液安定性が悪くなったり、析出速度が遅くなったり、実装基板の接合パッドの面積の差異があると膜厚ばらつきが大きくなったり、あるいは、パラジウム中間層／ニッケル中間層の積層構造における下層のニッケル中間層の腐食が大きくなったりすることがわかる。 As is clear from Table 4, it can be seen that the cyan-based substituted gold plating solutions of Comparative Examples 1 to 5 have poor liquid storage stability. Further, the liquid stability is deteriorated, the precipitation rate is slowed down, the film thickness variation becomes large when there is a difference in the area of the bonding pad of the mounting substrate, or in the laminated structure of the palladium intermediate layer / nickel intermediate layer. It can be seen that the corrosion of the lower nickel intermediate layer increases.
具体的には次のとおりである。
タリウム化合物を含まない比較例１の置換金めっきでは、浸漬時間を６０分としても平均膜厚が０．０６μｍと非常に薄い。しかも、膜厚ばらつきが２２．６と大きく、極端に薄い膜が存在するので、実装基板・接合部パッドには不適である。
Specifically, it is as follows.
In the replacement gold plating of Comparative Example 1 containing no thallium compound, the average film thickness is as thin as 0.06 μm even if the immersion time is 60 minutes. Moreover, since the film thickness variation is as large as 22.6 and an extremely thin film is present, it is not suitable for a mounting substrate / joint pad.
また、水酸基を有するアミノカルボン酸系キレート剤を含有しない比較例２の置換金めっき液は、めっき終了後の容器壁面に金金属が析出し、容器が変色していた。また、パラジウム中間層／ニッケル中間層の積層構造における下層のニッケル中間層の腐食が激しく、独立した銅パッド上のパラジウム中間層が一部剥離していた。 Further, in the substituted gold plating solution of Comparative Example 2 containing no aminocarboxylic acid-based chelating agent having a hydroxyl group, gold metal was deposited on the wall surface of the container after the plating was completed, and the container was discolored. Further, in the laminated structure of the palladium intermediate layer / nickel intermediate layer, the nickel intermediate layer of the lower layer was severely corroded, and the palladium intermediate layer on the independent copper pad was partially peeled off.
アスコルビン酸を含有した比較例３の置換金めっき液は、著しく液安定性が悪くなっていた。
また、ｐＨが下限値を下回る比較例４の置換金めっき液も液安定性が悪くなっている。更に、ポリエチレングルコール無添加のため下層のニッケル中間層の腐食が拡張していた。
また、ｐＨが上限値を超える比較例５の置換金めっき液は、膜厚ばらつきが極めて大きくなった。また、パラジウム中間層／ニッケル中間層の積層構造における下層のニッケル中間層の腐食が激しく、独立した銅パッド上のパラジウム中間層が一部剥離していた。
The replacement gold plating solution of Comparative Example 3 containing ascorbic acid had significantly deteriorated liquid stability.
Further, the replacement gold plating solution of Comparative Example 4 in which the pH is lower than the lower limit value also has poor liquid stability. Furthermore, since polyethylene glucol was not added, the corrosion of the lower nickel intermediate layer was expanded.
Further, the substitution gold plating solution of Comparative Example 5 in which the pH exceeded the upper limit value had an extremely large variation in film thickness. Further, in the laminated structure of the palladium intermediate layer / nickel intermediate layer, the nickel intermediate layer of the lower layer was severely corroded, and the palladium intermediate layer on the independent copper pad was partially peeled off.
次に、実施例３と同様にして、比較例２の置換金めっき層のみを剥離して下地金属の腐食状況を確認した。これを図３に示す。
図３の写真を観察すると、ニッケルめっき皮膜に形成した略四角形の大きな粒界（５μｍ×５μｍ）だけがみえる。パラジウムめっき皮膜には、図１のような細かな粒界は観察されず、液中の金イオンとパラジウムめっき皮膜との置換反応が起きていないことが示唆される。このパラジウムめっき皮膜をピンセットで突くと、パラジウムめっき皮膜が割れて下層のニッケルめっき皮膜が露呈した。露呈したニッケルめっき皮膜は、略四角形の大きな粒界が激しく腐食されて、大きな空洞が形成していた。すなわち、比較例２の置換金めっき液では、ニッケルめっき皮膜の一部分、略四角形の大きな粒界だけで置換反応が起きていたことが示唆される。
Next, in the same manner as in Example 3, only the replacement gold plating layer of Comparative Example 2 was peeled off to confirm the corrosion state of the base metal. This is shown in FIG.
When observing the photograph of FIG. 3, only the large grain boundaries (5 μm × 5 μm) of substantially quadrangular shapes formed on the nickel plating film can be seen. No fine grain boundaries as shown in FIG. 1 were observed in the palladium plating film, suggesting that the substitution reaction between the gold ions in the liquid and the palladium plating film did not occur. When this palladium plating film was pierced with tweezers, the palladium plating film cracked and the underlying nickel plating film was exposed. In the exposed nickel plating film, large quadrangular grain boundaries were severely corroded to form large cavities. That is, it is suggested that in the replacement gold plating solution of Comparative Example 2, the substitution reaction occurred only in a part of the nickel plating film and the large grain boundaries of substantially quadrangles.
以上の実施例、参考例および比較例から明らかなとおり、本発明のシアン系置換金めっき液を使用すると、液保存性に優れ、建浴後も長期間にわたり自己分解作用が生じないことがわかる。また、本発明のシアン系置換金めっき液は、参考例のめっき液と同様に、めっき終了後の金沈殿物と容器内壁への金析出がなく、めっき液が安定していることがわかる。更に保存剤としてマロノニトリルまたはスクリノニトリルを含有する置換金めっき液では、金金属の析出速度が速く、ＥＮＥＰＩＧ法などにおける実装基板の接合部パッドの面積の差異による膜厚ばらつきをより小さくすることができる。更に、特に、本発明のシアン系置換金めっき方法によれば、下層のニッケル中間層を激しく腐食させることなく、パラジウム中間層／ニッケル中間層の積層構造上に金表層を形成することができる。 As is clear from the above Examples, Reference Examples and Comparative Examples, it can be seen that when the cyan-based substituted gold plating solution of the present invention is used, the solution storage stability is excellent and the self-decomposition action does not occur for a long period of time even after the bath is built. Further, it can be seen that the cyan-based substituted gold plating solution of the present invention is stable because there is no gold precipitate after completion of plating and no gold precipitation on the inner wall of the container, as in the case of the plating solution of the reference example. Further, in the substituted gold plating solution containing malononitrile or scrinonitrile as a preservative, the precipitation rate of gold metal is high, and the film thickness variation due to the difference in the area of the joint pad of the mounting substrate in the ENEPIG method or the like can be further reduced. it can. Further, in particular, according to the cyan-based substituted gold plating method of the present invention, a gold surface layer can be formed on the laminated structure of the palladium intermediate layer / nickel intermediate layer without violently corroding the nickel intermediate layer of the lower layer.
本発明の製造方法により製造されたシアン系置換金めっき液は、金属、プラスチック、セラミックなどの被めっき物にスポットめっきや全面めっきなどの置換金めっきを行うことができる。その結果、電極、電気・電子部材、半導体部材などの用途に利用することができる。 The cyan-based replacement gold plating solution produced by the production method of the present invention can perform replacement gold plating such as spot plating or full surface plating on an object to be plated such as metal, plastic, or ceramic. As a result, it can be used for applications such as electrodes, electrical / electronic members, and semiconductor members.
Claims (9)
The replacement gold plating method according to claim 8, wherein the laminated structure is a laminated structure of an intermediate layer in which an electroless nickel plating film is formed on a copper metal and an electroless palladium plating film is further formed.
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| TW108141249A TW202033827A (en) | 2018-12-26 | 2019-11-13 | Substituted gold plating solution and substituted gold plating method having a high precipitation rate and a small variation in the film thickness of the precipitated film |
| KR1020190174476A KR20200080185A (en) | 2018-12-26 | 2019-12-24 | Substituted gold plating solution and substituted gold plating method |
| CN201911362917.5A CN111378962A (en) | 2018-12-26 | 2019-12-26 | Replacement gold plating solution and replacement gold plating method |
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