JP2009280867A - Electrolytic alloy plating solution, and plating method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolytic alloy plating solution using no cyanide, which is applicable for hard gold plating and has good stability, and to provide an electrolytic alloy plating method using the same. <P>SOLUTION: This electrolytic gold alloy plating solution contains a gold ion, at least one metal ion other than gold including nickel or cobalt, a sulfite other than gold sulfite, and a thiosulfate and/or a thiocyanate. The bath composition does not contain a cyanide. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  TECHNICAL FIELD The present invention relates to an electrolytic alloy plating solution that does not use a cyanide and can be hard gold-plated and has a good plating solution stability, and an electrolytic alloy plating method using the same.

  Currently, a gold plating film called a hard gold plating film is widely used as an electrical contact material for parts requiring high reliability in connectors for electrical and electronic parts, small relays, printed wiring boards and the like. The hard gold plating film is a film containing gold and metals such as cobalt and nickel and having improved hardness without deteriorating the good conductivity and chemical stability of gold. This hard gold plating film has a fine structure in which fine crystals of gold (crystal grain size: 20 to 30 nm) are combined, and this fine structure is the minimum for obtaining the wear resistance required for contact materials. It is considered that the required hardness (Knoop hardness is about 170 Hk) can be obtained.

  Conventionally, a plating bath mainly containing a cyanide compound has been used as a method for obtaining a hard gold plating film. Since cyan forms a strong complex with gold, a gold plating bath containing a cyanide compound is extremely stable due to the strong complexing action of cyanide. Further, depending on the liquid composition, there is an advantage that cyan contributes to increasing the hardness of the film. However, cyan has a large burden on the environment such as toxicity and harmfulness to living organisms, and in the field of electronic materials, there is a problem of aggressiveness against materials. Accordingly, there is a strong demand for a plating solution that does not contain cyan, that is, a no-cyan gold plating solution.

  However, when cyan is removed from the plating solution, there is a problem that gold cannot exist stably as ions in the plating solution. Therefore, in order to achieve cyanidation, stabilization of the plating solution, that is, stabilization of the bath is important. Up to now, various gold plating solutions such as an electrolytic soft gold plating solution, an electroless gold plating solution, and a displacement gold plating solution have been proposed as the nocyan gold plating solution, and are partially put into practical use. However, in the case of hard gold plating, it is necessary to control the crystallinity of the film and the amount of sub-composition in the film. For example, in the case of gold alloy plating, unlike soft gold plating intended to deposit only gold, other metals (nickel, cobalt, etc.) and complexing agents (citric acid, etc.) are often included in the bath, These cause a decrease in bath stability. In particular, in a plating bath using sulfurous acid as a gold complexing agent, the destabilization of the bath becomes remarkable, so that hard gold plating is more difficult to realize than soft gold plating.

  Non-cyan electricity using gold complexes such as acetylcysteine gold complex, cysteine gold complex, and mercaptosuccinic acid gold complex as a source of gold, and acetylcysteine as a complexing agent for the problem of bath stability related to non-cyanide gold plating A gold plating bath has been reported (Patent Document 1). In addition, this document also describes that a metal other than gold is added and alloyed depending on the purpose such as hardening or color change. However, acetylcysteine is not sufficient as a complexing agent, and further improvement in stability is desired.

In addition, a gold plating film by a non-cyan hard gold plating method in which the crystal grain size is controlled by pulse electrolysis has been reported (Patent Document 2). However, this method refines the crystallite by passing a pulse current, thereby producing a high-hardness gold-plated film, and has a drawback that it is more difficult than constant-current electrolysis. Moreover, this method manufactures a gold plating film made of a single metal element, and does not mention gold alloy plating. Furthermore, an electrolytic hard gold plating solution containing a gold ion source (soluble gold salt or gold complex), an organic acid salt and / or an inorganic acid salt, a hardener (soluble salt of cobalt and nickel) and an aliphatic alcohol is reported. (Patent Document 3). However, although this document exemplifies potassium gold sulfite as a soluble gold salt and sulfite as an inorganic acid salt, the example shows only a plating solution using potassium gold cyanide and tripotassium citrate, which is feasible. No specific embodiment of a non-cyanide gold plating solution is shown.
Japanese Patent No. 3671102 JP 2007-177291 A Japanese Patent Laid-Open No. 2004-76026

  Accordingly, an object of the present invention is to provide an electrolytic alloy plating solution that does not use a cyanide compound and can be used for hard gold plating and has a stable plating solution, and an electrolytic alloy plating method using the same. .

  As a result of intensive studies in view of the above object, the inventors of the present invention use an electroplating solution containing gold sulfite to keep the plating solution stable and perform electroplating at a predetermined cathode current density and temperature. As a result, it has been found that a gold alloy plating film having a high hardness of 120 Hk or more can be formed, and a non-cyanide hard gold alloy plating solution has been achieved.

  That is, the present invention contains gold ions, at least one metal ion other than gold containing nickel or cobalt, sulfites other than gold sulfites, thiosulfates and / or thiocyanates, The present invention relates to an electrolytic gold alloy plating solution that does not contain a cyanide compound.

The present invention also relates to the electrolytic gold alloy plating solution further comprising at least one selected from the group consisting of citric acid, glycine, succinic acid and salts thereof.
Furthermore, the present invention relates to the electrolytic gold alloy plating solution in which a gold alloy precipitate having a Knoop hardness (by the Knoop hardness test described in JIS Z2251—test method) of 120 Hk or more is obtained by constant current electrolysis.

The present invention also includes a gold ion, at least one metal ion other than gold containing nickel or cobalt, a sulfite other than gold sulfite, and a thiosulfate and / or thiocyanate, The present invention relates to an electrolytic gold alloy plating method using an electrolytic gold alloy plating solution not containing a cyanide compound in the composition.
Furthermore, the present invention relates to the electrolytic gold alloy plating method, wherein the working current density is 10 mA / cm ² or less.
The present invention also relates to the electrolytic gold alloy plating method, wherein the liquid temperature during plating is less than 50 ° C.

  Furthermore, the present invention relates to the electrolytic gold alloy plating method, wherein the plating solution further contains at least one selected from the group consisting of citric acid, glycine, succinic acid and salts thereof.

  The electrolytic gold alloy plating solution of the present invention contains no cyanide, contains gold ions, second metal elements (metal elements other than gold: nickel, cobalt, etc.) ions and complexing agents, and is a combination of complexing agents. By selecting this, it is possible to achieve a stable plating solution in which fine particles are not generated in the plating solution and to form a hard gold alloy plating film having a high hardness of 120 Hk or more.

[1] Electrolytic gold alloy plating solution The electrolytic gold alloy plating solution of the present invention comprises gold ions, at least one metal other than gold including nickel or cobalt or ions thereof, sulfites other than gold sulfites, and thios. Contains sulphate and / or thiocyanate and no cyanide. The plating solution of the present invention contains a solvent such as water, a hydrophilic organic solvent (alcohols such as methanol and ethanol, polyhydric alcohols such as ethylene glycol and glycerin, phenols such as phenol), and a mixture thereof. . The plating solution is preferably an aqueous solution.

The electrolytic gold alloy plating solution of the present invention preferably contains a water-soluble gold salt not containing cyan as gold ions. Examples of water-soluble gold salts containing no cyanide include sodium gold sulfite, potassium gold sulfite, ammonium gold sulfite, sodium chloroaurate, potassium chloroaurate, ammonium chloroaurate, etc., and the concentration is not particularly limited. However, it is preferably about 0.0001 to 0.5 mol / dm ³ , more preferably about 0.001 to 0.5 mol / dm ³ , and still more preferably about 0.01 to 0.1 mol / dm ³ on a gold basis. . If the gold concentration is too high, the bath tends to become unstable.

  The second metal element contained in the electrolytic gold alloy plating solution of the present invention is a metal that contains at least nickel or cobalt and can form an alloy with gold, preferably a metal belonging to Groups 6 to 13 of the periodic table It is. Preferable examples of the second metal element other than nickel or cobalt include titanium, iron, copper, zinc, molybdenum, ruthenium, rhodium, palladium, silver, indium, tin, tungsten, rhenium, platinum and the like. When the second metal element is a combination of two or more elements, preferable examples thereof include nickel and titanium, iron, cobalt, copper, zinc, molybdenum, ruthenium, rhodium, palladium, silver, indium, tin, tungsten, A combination of rhenium or platinum, a combination of cobalt and titanium, iron, nickel, copper, zinc, molybdenum, ruthenium, rhodium, palladium, silver, indium, tin, tungsten, rhenium, or platinum can be given.

The electrolytic gold alloy plating solution of the present invention preferably contains a water-soluble salt of a second metal element as a metal ion other than gold. For example, when nickel is used as the second metal element, examples of the water-soluble nickel salt include nickel sulfate, nickel chloride, nickel nitrate and the like, and the concentration thereof is about 0.001 to 1 mol / dm ^{3 on the} nickel basis, preferably About 0.01 to 0.5 mol / dm ³ . The ratio of gold to nickel (Au / Ni) in the plating solution is preferably about 0.1 to 2, more preferably about 0.2 to 0.7 as a molar ratio. In the case of using cobalt as the second metal element, the concentration of about 0.001 to 1 mol / dm ³ of cobalt basis, preferably about 0.01 to 0.5 mol / dm ^3. The molar ratio of gold to cobalt (Au / Co) in the plating solution is preferably about 0.01 to 2, more preferably about 0.05 to 0.5. When the amount of the second metal element is small, the plating film does not increase in hardness.

The electrolytic gold alloy plating solution of the present invention may contain gold sulfite as a gold salt as described above, but separately contains sulfite other than gold sulfite as a complexing agent. Examples of the sulfites include alkali metal salts of sulfites such as lithium sulfite, sodium sulfite and potassium sulfite, alkaline earth metal salts of sulfites such as calcium sulfite and magnesium sulfite, and ammonium sulfite. The concentration of sulfite in the electrolytic gold alloy plating solution is preferably about 0.01 to 2.0 mol / dm ³ , more preferably about 0.1 to 1.0 mol / dm ³ . The molar ratio of sulfite to gold (sulfite / gold) in the plating solution is preferably in the range of 1 to 200, more preferably in the range of 2 to 100.

  The electrolytic gold alloy plating solution of the present invention further contains thiosulfate and / or thiocyanate capable of forming a complex with monovalent or trivalent gold ions. The thiosulfate and / or thiocyanate is preferably a salt other than a gold salt (such as gold thiosulfate). Preferred examples of the thiosulfate include alkali metal salts of thiosulfuric acid such as sodium thiosulfate and potassium thiosulfate, alkaline earth metal salts of thiosulfuric acid such as calcium thiosulfate and magnesium thiosulfate, and ammonium thiosulfate. Preferable examples of thiocyanate include alkali metal salts of thiocyanic acid such as sodium thiocyanate and potassium thiocyanate, alkaline earth metal salts of thiocyanic acid such as calcium thiocyanate and magnesium thiocyanate, ammonium thiocyanate, and the like. .

The use concentration of thiosulfate and / or thiocyanate in the plating solution is preferably in the range of about 0.001 to 2.0 mol / dm ³ , more preferably about 0.01 to 1.5 mol / dm ^3. . The thiosulfate and / or thiocyanate is preferably in the range of about 0.5 to 200, more preferably in the range of about 1 to 30 in terms of molar ratio to gold (thiosulfate and / or thiocyanate / gold). Can be used. Sulphites, thiosulfates and thiocyanates have a high complexing ability with respect to gold ions, and these salts are also referred to herein as gold complexing agents for convenience. If the concentration of the gold complexing agent is low, the bath tends to become unstable. Although there is no particular problem even if the concentration of the gold complexing agent is high, it is desirable to avoid excessive addition from the viewpoint of solubility and waste liquid treatment.

Examples of complexing agents for the second metal element include citric acid, tartaric acid, malic acid, succinic acid, glycine, ethylenediaminetetraacetic acid or salts thereof, for example, alkali metal salts such as sodium and potassium, and alkaline earth such as calcium and magnesium. Metal salts, ammonium salts such as triammonium citrate, and the like can be used. Of these, citric acid, glycine, succinic acid, and salts thereof are preferable. The concentration range of the complexing agent of the second metal element is preferably about 0 to ³ mol / dm ³ , more preferably about 0.01 to 0.5 mol / dm ³ . The complexing agent of the second metal element is preferably in a molar ratio with the second metal in the plating solution (complexing agent of the second metal element / second metal), preferably about 0 to 50, more preferably about It can be used in the range of 0.5 to 10. If the complexing agent concentration of the second metal element is too high, the amount of precipitation of the second metal element decreases, and a high-hardness plating film cannot be obtained.

  The plating solution of the present invention contains other components as necessary, for example, buffering agents such as phosphoric acid, boric acid, and carbonic acid, pH adjusting agents such as hydrochloric acid, sulfuric acid, sodium hydroxide, and potassium hydroxide, ammonium sulfate, and the like. These salts and the like may be added as long as the object of the present invention is not impaired. The pH of the plating solution is preferably about 5.5-11, more preferably about 6-9.

  One preferred embodiment of the plating solution of the present invention includes gold ions (such as sodium gold sulfite), second metal ions (such as nickel ions and cobalt ions), sulfites (such as potassium potassium sulfite), and thiosulfate and / or Alternatively, thiocyanate (sodium thiosulfate, potassium thiocyanate, etc.) is contained in the plating solution. The concentration ratio of the complexing agent (sulfite: thiosulfate and / or thiocyanate) is preferably about 1: 0.0005-40, more preferably about 1: 0.01-15, and even more preferably about 1. : 0.1-5.

  Another embodiment of the plating solution of the present invention includes gold ions (such as sodium gold sulfite), second metal ions (such as nickel ions and cobalt ions), sulfites (such as potassium gold sulfite), thiosulfates and / or thiocyanates. An acid salt (sodium thiosulfate, potassium thiocyanate, etc.) and a complexing agent of a second metal element (citric acid, glycine, succinic acid, salts thereof, etc.) are contained in the plating solution. The preferable concentration range of the gold ion, the second metal ion and the complexing agent in the plating solution, and the concentration ratio of sulfite to thiosulfate and / or thiocyanate are the same as the above ranges.

[2] Electrolytic gold alloy plating method In the plating method of the present invention, electrolytic plating is performed by immersing an object to be plated in the above plating solution as a cathode. As the anode, an insoluble anode such as platinum or platinum-coated titanium or a water-soluble anode such as nickel can be used. In the plating method of the present invention, the temperature of the plating solution is 10 ° C to 70 ° C, preferably 20 ° C to less than 50 ° C, and particularly preferably 25 ° C to 40 ° C. When the temperature of the plating solution is low, the plating rate is slow, and when the temperature of the plating solution is high, a stable plating bath cannot be obtained. Cathode current density is 50 mA / cm ² or less, preferably 1~10mA / cm ^2. For example, in the case of a gold alloy plating solution using gold and nickel, if the cathode current density is high, the nickel ratio in the plating film increases and the hardness increases, but the plating solution becomes unstable and fine particles are likely to be generated. . If the cathode current density is low, the bath is stabilized, but the nickel ratio in the film tends to decrease and the hardness tends to decrease. The gold alloy plating film obtained by using the plating solution of the present invention preferably contains 30% by weight or more of gold and preferably has a hardness of 120Hk or more.

One preferred embodiment of the plating method of the present invention is that the plating solution contains at least one non-cyanide gold compound and a water-soluble nickel salt or a water-soluble cobalt salt, and metal fine particle generation or bath decomposition occurs in a bath. In order to suppress the reaction, each of the following conditions: (1) a) sulfite, b) thiosulfate and / or thiocyanate, and c) citrate, glycine, succinic acid, and at least one of these salts, respectively 0.01-2 mol / dm ³ included, (2) the current density used is 1-10 mA / cm ² , (3) the pH of the plating solution during plating is 5.5-11 and the temperature of the plating solution is 10-10 It includes two or more conditions among those set to less than 50 ° C., and more preferably includes all of the above conditions (1) to (3).

Another preferred embodiment of the plating method of the present invention is that the plating solution contains at least one non-cyanide gold compound and a water-soluble nickel salt or a water-soluble cobalt salt, and metal fine particle generation or bath decomposition occurs in a bath. for the reaction inhibition, the following conditions: (1) a) 0.01~2mol a sulfite / ^dm 3, b) thiosulfate and / or thiocyanate to 0.001~2mol / dm ^3, and c) Citrate, glycine, succinic acid and at least one of these salts each contain 0.001 to ³ mol / dm ³ , (2) the current density used is 0.1 to 50 mA / cm ² , (3) plating The pH of the plating solution is 6-9 and the temperature of the plating solution is 10-70 ° C.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

In each example and comparative example, the analysis or measurement method and conditions are as follows.
(A) Metal composition:
The Au / Ni or Co ratio was measured with a fluorescent X-ray microelement monitor SEA-5100 manufactured by Seiko Nanotechnology.
(B) Knoop hardness:
It measured by Shimadzu Corporation HMV-2000. A cross section of a plating film with a thickness of 30 μm formed on a nickel-coated copper or nickel plate was measured with a load of 5 gf, a load holding time of 30 seconds.
(C) Corrosion resistance: Corrosion potential was measured (anode partial polarization measurement) in a 25 wt% NaCl aqueous solution.
HZ-5000 manufactured by Hokuto Denko was used, and the scanning range was -1 to +0.5 V, the scanning speed was 10 mV / sec, the counter electrode Pt, the reference electrode Ag / AgCl, room temperature (20 to 30 ° C.), and nitrogen atmosphere.
(D) Observation of fine particles in plating solution: Fine particles were observed with a particle counter.

Example 1
0.035 mol / dm ³ , NiSO ₄ .6H ₂ O is 0.076 mol / dm ³ , triammonium citrate is 0.21 mol / dm ³ , and (NH ₄ ) ₂ SO ₄ is 0.0. _{^{015mol / dm 3, K 2 SO}} 3 and 0.35 mol / dm ^3, and _{Na 2 S 2 O 3 · 5H} 2 O and 0.07 mol / dm ³ and _containing, adjusted to pH 8 by H 2 SO ₄ or KOH A gold-nickel alloy plating film was formed on nickel, titanium, or a gold plate having a purity of 99.99% at a temperature of 30 ° C. and a current density of 5 mA / cm ² . A platinum-coated titanium plate was used for the anode, and the plating solution was stirred with a magnetic stirrer. The bath scale was carried out in the range of 0.1 to 1L.

  The composition of the obtained gold-nickel alloy plating film was analyzed. It was 237Hk when the Knoop hardness of the plating film was measured. When the corrosion potential was measured in a 25 wt% NaCl aqueous solution using the film obtained on the metal plate as the working electrode, the same good corrosion resistance as that of the 99.99% metal plate was exhibited. Before and after use, there was no fine particle in the plating solution and it was stable. The results are shown in Tables 1 and 2.

Example 2
0.035 mol / dm ³ , NiSO ₄ .6H ₂ O 0.076 mol / dm ³ , succinic acid 0.21 mol / dm ³ , (NH ₄ ) ₂ SO ₄ 0.33 mol / m Electroplating containing dm ³ , K ₂ SO ₃ of 0.35 mol / dm ³ , Na ₂ S ₂ O ₃ .5H ₂ O of 0.07 mol / dm ³ and adjusting the pH to 8 with H ₂ SO ₄ or KOH A gold-nickel alloy plating film was formed in the same manner as in Example 1 except that the liquid was used, and the obtained plating film was analyzed and measured. It was 221Hk when the Knoop hardness of the plating film was measured. Before and after use, there was no fine particle in the plating solution and it was stable. The results are shown in Tables 1 and 2.

Example 3
0.035 mol / dm ³ , NiSO ₄ .6H ₂ O 0.076 mol / dm ³ , glycine 0.21 mol / dm ³ , (NH ₄ ) ₂ SO ₄ 0.33 mol / dm ^3, _K 2 SO ₃ and _{^{0.35mol / dm 3, Na 2 S}} 2 O 3 · 5H 2 O and 0.07 mol / dm ³ and containing _{electroplating} solution and the pH was adjusted to 8 by H 2 SO ₄ or KOH A gold-nickel alloy plating film was formed in the same manner as Example 1 except that the obtained plating film was analyzed and measured. The Knoop hardness of the plating film was measured and found to be 230 Hk. Before and after use, there was no fine particle in the plating solution and it was stable. The results are shown in Tables 1 and 2.

Example 4
0.06 mol / dm ³ , NiSO ₄ .6H ₂ O 0.076 mol / dm ³ , citric acid 0.21 mol / dm ³ , K ₂ SO ₃ 0.42 mol / dm ³ The same as in Example 1 except that an electroplating solution containing 1.26 mol / dm ^{3 of} Na ₂ S ₂ O ₃ .5H ₂ O and adjusting the pH to 8 with H ₂ SO ₄ or KOH was used at 60 ° C. A gold-nickel alloy plating film was formed, and the obtained plating film was analyzed and measured. It was 164Hk when the Knoop hardness of the plating film was measured. Before and after use, there was no fine particle in the plating solution and it was stable. The results are shown in Tables 1 and 2.

Example 5
0.06 mol / dm ³ , NiSO ₄ .6H ₂ O 0.076 mol / dm ³ , citric acid 0.21 mol / dm ³ , (NH ₄ ) ₂ SO ₄ 0.33 mol / dm _{^3, K} 2 SO ³ containing 1.26 mol / dm ³ to _{^{0.42mol / dm 3, Na 2 S}} 2 O 3 · 5H 2 O _, and electroplating was adjusted to pH 8 by H 2 SO ₄ or KOH A gold-nickel alloy plating film was formed in the same manner as in Example 1 except that the liquid was used at 60 ° C., and the obtained plating film was analyzed and measured. The Knoop hardness of the plating film was measured and found to be 140 Hk. Before and after use, there was no fine particle in the plating solution and it was stable. The results are shown in Tables 1 and 2.

Example 6
0.035 mol ^/ dm 3 sodium gold sulfite solution as gold, CoSO ₄ · 7H ₂ O and 0.076 mol / dm ^3, 0.21 mol ^/ dm 3 of citric acid 3 _{ammonium, (NH 4) 2 SO 4 0} . 015 mol / dm ³ , K ₂ SO ₃ containing 0.35 mol / dm ³ , Na ₂ S ₂ O ₃ .5H ₂ O containing 0.07 mol / dm ^3, and the pH was adjusted to 8 with H ₂ SO ₄ or KOH. A gold-cobalt alloy plating film was formed in the same manner as in Example 1 except that the electroplating solution was used, and the obtained plating film was analyzed and measured. Moreover, when the Knoop hardness of the plating film was measured, it was 128 Hk. Before and after use, there was no fine particle in the plating solution and it was stable. The results are shown in Tables 1 and 2.

Example 7
0.035 mol ^/ dm 3 sodium gold sulfite solution as gold, CoSO ₄ · 7H ₂ O and 0.207 mol / dm ^3, 0.21 mol ^/ dm 3 of citric acid 3 _{ammonium, (NH 4) 2 SO 4 0} . 015 mol / dm ³ , K ₂ SO ₃ containing 0.35 mol / dm ³ , Na ₂ S ₂ O ₃ .5H ₂ O containing 0.07 mol / dm ^3, and the pH was adjusted to 8 with H ₂ SO ₄ or KOH. A gold-cobalt alloy plating film was formed in the same manner as in Example 1 except that the electroplating solution was used, and the obtained plating film was analyzed and measured. Moreover, it was 121Hk when the Knoop hardness of the plating film was measured. Before and after use, there was no fine particle in the plating solution and it was stable. The results are shown in Tables 1 and 2.

Example 8
A gold-nickel alloy plating film was formed in the same manner as in Example 1 except that the temperature of the plating solution was 70 ° C., and the obtained plating film was analyzed and measured. The Au / Ni ratio (wt) was 99.5 / 0.5. Even if heating was continued for 3 hours after use, fine particles were not generated in the bath, and the bath was stable. Knoop hardness was 196Hk. Compared with Comparative Example 2, it was clear that the bath was stabilized by sulfite and thiosulfate. Before and after use, there was no fine particle in the plating solution and it was stable. The results are shown in Tables 1 and 2.

Example 9
0.035 mol / dm ³ , NiSO ₄ .6H ₂ O is 0.076 mol / dm ³ , triammonium citrate is 0.21 mol / dm ³ , and (NH ₄ ) ₂ SO ₄ is 0.0. _{^{015mol / dm 3, K 2 SO}} 3 and 0.35 mol ^/ dm 3, containing 0.35 mol / dm ³ to _KSCN, except that the electroplating solution and the pH was adjusted to 8 by H 2 SO ₄ or KOH, example In the same manner as in No. 1, a gold-nickel alloy plating film was formed, and the obtained plating film was analyzed and measured. Moreover, it was 421Hk when the Knoop hardness of the plating film was measured. Before and after use, there was no fine particle in the plating solution and it was stable. The results are shown in Tables 1 and 2.

Comparative Example 1
Sodium gold sulfite solution _{^{0.06mol / dm 3, K 2 SO}} 3 and ^{_{0.42mol / dm 3, Na 2 S}} 2 a _{O 3 · 5H 2 O 1.26mol /} dm 3 and containing as _gold, H 2 SO ₄ Alternatively, a gold plating film was formed in the same manner as in Example 1 except that an electroplating solution adjusted to pH 8 with KOH was used at 60 ° C., and the obtained plating film was analyzed and measured. The Knoop hardness of the plating film deposited on the nickel was measured and found to be 92 Hk. The results are shown in Tables 1 and 2.

Comparative Example 2
0.035 mol / dm ³ , NiSO ₄ .6H ₂ O is 0.076 mol / dm ³ , triammonium citrate is 0.21 mol / dm ³ , and (NH ₄ ) ₂ SO ₄ is 0.0. Gold-nickel alloy plating in the same manner as in Example 1 except that an electroplating solution containing 015 mol / dm ³ and adjusted to pH 7 with H ₂ SO ₄ or KOH was used at 70 ° C. and a current density of 50 mA / cm ^2. A film was formed, and the resulting plated film was analyzed and measured. It was 261 Hk when the Knoop hardness of the plating film was measured. The plating solution was unstable because fine particles were generated in the bath when used for about 30 minutes. The results are shown in Tables 1 and 2.

Comparative Example 3
A gold-nickel alloy plating film was formed in the same manner as in Comparative Example 2 except that the temperature of the plating solution was 30 ° C. and the current density was 5 mA / cm ² , and the obtained plating film was analyzed and measured. . 30 min. The bath was unstable due to the generation of fine particles in the bath. The results are shown in Tables 1 and 2.

Claims (7)

  Containing a gold ion, at least one metal ion other than gold including nickel or cobalt, a sulfite other than gold sulfite, and a thiosulfate and / or thiocyanate, and adding a cyanide compound to the bath composition No electrolytic gold alloy plating solution.   The electrolytic gold alloy plating solution according to claim 1, further comprising at least one selected from the group consisting of citric acid, glycine, succinic acid and salts thereof.   The gold alloy plating solution according to claim 1 or 2, wherein a gold alloy precipitate having a Knoop hardness (according to JIS Z2251) of 120 Hk or more is obtained by constant current electrolysis.   Containing a gold ion, at least one metal ion other than gold including nickel or cobalt, a sulfite other than gold sulfite, and a thiosulfate and / or thiocyanate, and adding a cyanide compound to the bath composition An electrolytic gold alloy plating method using an electrolytic gold alloy plating solution not contained. The electrolytic gold alloy plating method according to claim 4, wherein the current density used is 10 mA / cm ² or less.   The electrolytic gold alloy plating method according to claim 4 or 5, wherein the liquid temperature during plating is less than 50 ° C.   The electrolytic gold alloy plating method according to any one of claims 4 to 6, wherein the plating solution further contains at least one selected from the group consisting of citric acid, glycine, succinic acid and salts thereof.