JPH09296274A - Aqueous solution for formation of metal complex, tin-silver alloy plating bath and production of plated material using the plating bath - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a tin-silver alloy plating liquid having excellent characteristics and harmless for a human body by adding a pyrophosphoric acid compd. and an iodine compd. as a complexing agent for tin and silver to a soln. containing a tin compd. and a silver compd. SOLUTION: After a photosensitive resin film is applied to form a specified pattern on the surface of a body to be plated, the material is subjected to electric plating using a tin-silver alloy plating liquid. This plating liquid consists of a soln. which contains a tin compd. of inorg. acid tin such as tin chloride and Org. tin such as tin methasulfonate, inorg. silver such as silver chloride and org. silver such as silver alkanol sulfonate and further contains a pyrophosphoric acid compd. such as pyrophosphate and an iodine compd. such as iodate as a complexing agent for tin and silver. This plating liquid does not contain a cyanide compd. which is harmful for a human body. Thus, a tin-silver alloy plating film showing comparable sulfurization resistance to a conventional tinlead alloy plating film can be formed with high current efficiency, and the obtd. film has such a compd. that the proportion of silver and tin can be largely changed.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an aqueous solution for forming a metal complex for forming a metal complex, a tin-silver alloy plating bath, and a method for producing a plated product using this plating solution.

[0002]

2. Description of the Related Art The technique of forming a metal complex is always required in the fields of plating and analysis. Therefore, conventionally, cyanide compounds, ammonia, organic acids, etc. have been used as complexing agents. However, there is no effective complexing agent for all metals, and the cyanide compound, which is excellent as a complexing agent, has been harmful to the human body and has problems in wastewater treatment. Therefore, it has been demanded to provide a complex-forming product which is harmless to the human body and is effective for a larger amount of metals.

On the other hand, when pollution of groundwater due to lead becomes a problem and regulations for lead-containing products are tightened, there is an increasing tendency to replace the tin-lead solder conventionally used for soldering with a lead-free solder. Under such circumstances, it is necessary to change the tin-lead solder coating by plating to a solder containing no lead.

Tin-silver alloys are regarded as promising tin-lead alternative solder alloys, and recently Matsushita Electric Industrial Co., Ltd. has announced the practical application of tin-silver solder pastes (Nikkei Sangyo Shimbun February 1996). 1 day). Therefore, a technique for forming a tin-silver solder film by plating has been a problem. Further, the tin-silver alloy is also used as a silver substitute material as a sulfur-resistant alloy.

However, since the standard oxidation-reduction potentials of silver and tin are 900 mV or more apart from each other, when a conventional tin-silver alloy plating film is prepared, a cyanide compound such as potassium cyanide is used so that silver and tin are co-deposited. Was used. Therefore, for work safety or wastewater treatment,
There are many problems, and it has been desired to develop a tin-silver alloy plating bath containing no cyanide.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides an aqueous solution for forming a metal complex containing no cyanide compound, a tin-silver alloy plating bath capable of arbitrarily changing the composition of a tin-silver alloy, and an effective use of this plating bath. An object of the present invention is to provide a method for manufacturing a plated product.

[0007]

In order to achieve the above object, the metal complex forming aqueous solution of the present invention is characterized by containing at least a pyrophosphate compound and an iodine compound as basic compositions. The tin-silver alloy plating bath is characterized by containing at least a tin compound, a silver compound, and a pyrophosphoric acid compound and an iodine compound as a complexing agent for these, as a basic composition. As the above-mentioned pyrophosphate compound, pyrophosphate and / or pyrophosphate such as potassium pyrophosphate and sodium pyrophosphate can be contained. Further, as the above iodine compound, potassium iodide,
Iodide such as sodium iodide, potassium iodate,
It may contain iodate and / or iodine such as sodium iodate.

The tin-silver alloy plating bath according to the present invention is characterized by containing at least a tin compound, a silver compound, and a pyrophosphoric acid compound and an iodine compound as complexing agents thereof. As the above-mentioned pyrophosphate compound, pyrophosphate and / or pyrophosphate such as potassium pyrophosphate and sodium pyrophosphate can be contained. Further, as the above iodine compound, iodide, iodite and / or iodine can be contained.

As the above tin compounds, tin chloride, tin sulfate, tin pyrophosphate, tin iodide, stannic acid, potassium stannate, tin acetate,
An inorganic acid such as tin methane sulfonate, tin alkanol sulfonate, tin phenol sulfonate or an organic acid tin can be contained. Further, as the above-mentioned silver compound, an inorganic acid or an organic acid such as silver iodide, silver chloride, silver nitrate, silver sulfate, silver pyrophosphate, silver iodate, silver acetate, silver methanesulfonate, silver alkanolsulfonate, silver phenolsulfonate, etc. It can contain silver. The pyrophosphoric acid compound and the iodine compound may be added in amounts necessary for tin and silver to exist as complex ions.

Further, in the method for producing a plated product according to the present invention, a tin-silver alloy plating containing a tin compound, a silver compound, and a pyrophosphoric acid compound and an iodine compound as a complexing agent for these compounds on the object to be plated is used. The method is characterized in that electrolytic plating is performed with a liquid to form a tin-silver alloy plated portion. Furthermore, in the method for manufacturing a plated product according to the present invention, a step of forming a resin film on the plated object, a step of forming the resin film in a required pattern, and a resin film of the pattern as a mask are used as a mask on the plated object. A tin compound, a silver compound, and a step of forming a tin-silver alloy plated portion by electrolytic plating with a tin-silver alloy plating solution containing a pyrophosphate compound and an iodine compound as a basic composition as a complexing agent thereof. It is characterized by including. A photosensitive resin film can be used as the resin film, and the photosensitive resin film can be formed into a desired pattern by photolithography. As the above-mentioned pyrophosphate compound, pyrophosphate and / or pyrophosphate such as potassium pyrophosphate and sodium pyrophosphate can be contained. Further, as the iodine compound, iodide such as potassium iodide and sodium iodide, iodite such as potassium iodate and sodium iodate and / or iodine can be contained. As the tin compound, an inorganic or organic acid such as tin chloride, tin sulfate, tin pyrophosphate, tin iodide, tin acid, potassium stannate, tin acetate, tin methanesulfonate, tin alkanolsulfonate, tin phenolsulfonate, etc. It may contain tin. Further, as the above-mentioned silver compound, an inorganic acid or an organic acid such as silver iodide, silver chloride, silver nitrate, silver sulfate, silver pyrophosphate, silver iodate, silver acetate, silver methanesulfonate, silver alkanolsulfonate, silver phenolsulfonate, etc. It can contain silver.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In an aqueous solution for forming a metal complex, the amount of the pyrophosphate compound added is such that, in order to further stabilize the pyrophosphate complex ion of the metal to be formed, pyrophosphate is added to the metal in accordance with the coordination number of the metal. It is effective to add ions in an equimolar amount or in a double molar amount or more. Similarly in the tin-silver alloy plating bath, the addition amount of the pyrophosphate compound is such that the pyrophosphate ion is added to the metal in accordance with the coordination number of the metal in order to make the pyrophosphate complex ion of the generated metal more stable. . It is more effective to add the pyrophosphate ion in an amount of 2 times the mole or more of tin. For these pyrophosphate compounds, pyrophosphate salts such as potassium pyrophosphate and sodium pyrophosphate and pyrophosphate can be used alone or in combination.

In the aqueous solution for forming a metal complex, the addition amount of the iodine compound can be arbitrarily changed within a range in which the metal stably exists as a complex ion, but in order to make the iodide complex ion of the generated metal more stable, the iodine compound is added. Ions are added so that the concentration of the ions (I ⁻ ) is 0.5 mol / l or more. It is more effective to add iodide ion (I ⁻ ) in an amount of 1.5 mol / l or more. Also in the tin-silver alloy plating bath, similarly, the addition amount of the iodine compound can be arbitrarily changed within a range in which silver stably exists as a complex ion, but in order to make the iodide complex ion of the generated metal more stable, It is added so that the concentration of iodine ion (I ⁻ ) is 0.5 mol / l or more. It is more effective to add iodide ion (I ⁻ ) in an amount of 1.5 mol / l or more. As these iodine compounds, iodide such as potassium iodide and sodium iodide, iodite such as potassium iodate and sodium iodate, and iodine can be used alone or in combination of two or more.

The pH of the aqueous solution for forming the metal complex and the tin-silver alloy plating bath can be adjusted by adding an acid such as pyrophosphoric acid or hydrochloric acid or an alkali such as potassium hydroxide or sodium hydroxide. It is preferable to adjust the pH to a range of 5 to 10, but the pH can be arbitrarily adjusted as long as the pyrophosphate compound or the iodine compound does not deteriorate or decompose.

The aqueous solution for forming a metal complex can form a complex with one or more metals such as nickel, bismuth, copper, zinc, tin and silver. At this time, depending on the purpose, glycine, tartrate, oxalate, citrate, sulfite, thiosulfate, saccharin, butynediol, formaldehyde, polyethylene glycol, sodium lauryl sulfate, polyoxyethylene nonylphenyl ether, dicyclohexylammonium. Night light or the like can be added alone or in combination.

Similarly, in the above tin-silver alloy plating bath, glycine, tartrate, oxalate, citrate, sulfite, thiosulfate, saccharin, butynediol, formaldehyde, polyethylene glycol, lauryl sulfate are also used according to the purpose. Sodium, polyoxyethylene nonylphenyl ether, dicyclohexyl ammonium nitrite and the like can be added alone or in combination. Further, a complexing agent, a brightening agent, an antioxidant, a surfactant and the like can be added. As the complexing agent, oxalate, sulfite, thiosulfate, tartrate or the like can be added alone or in combination. As brighteners, peptone, β-naphthol, amine aldehyde, formaldehyde, acetaldehyde,
Polyethylene glycol, acrylic acid, methyl acrylate, bismuth oxide, triethanolamine, 2-diethylaminoethanol, salicylic acid, N, N'-dimethylformamide, hexaethylenetetramine, malonic acid and the like can be added alone or in combination. Further, particularly as an antioxidant of tin, L-ascorbic acid, phenol, hydroquinone, resorcin or the like can be added alone or in combination. As the surfactant, sodium lauryl sulfate, polyoxyethylene nonylphenyl ether, benzalkonium chloride and the like can be added alone or in combination.

The tin compound to be added to the above tin-silver alloy plating bath is not particularly limited, and tin chloride, tin chloride dihydrate, tin sulfate, tin pyrophosphate, stannic acid, tin methanesulfonate, etc. may be used. Inorganic acid or organic acid tin can be used alone or in combination of two or more kinds.

The silver compound to be added to the tin-silver alloy plating bath is not particularly limited, and silver iodide, silver chloride, silver nitrate,
The above-mentioned inorganic acid or organic acid tin such as silver sulfate and silver methanesulfonate can be used alone or in combination of two or more kinds.

The mixing ratio of the silver compound and the tin compound to be mixed in the tin-silver alloy plating bath of the present invention may be arbitrary. When obtaining an alloy film having a high silver content, the compounding ratio of the silver compound is increased, and when obtaining an alloy film having a high tin content, the compounding ratio of the tin compound is increased.

However, in the tin-silver alloy plating bath of the present invention, the composition of the alloy film obtained can be changed depending on the conditions such as the current density even in the plating bath having the same composition. can get. It has been found that, with the same composition, the silver content in the alloy film tends to decrease as the current density increases, and the composition of the alloy film becomes almost constant above a certain current density.

To carry out plating using the above tin-silver alloy plating bath, any ordinary electroplating method can be adopted. For example, other than the direct current method, a pulse plating method, a current reversal method or the like may be used. The plating conditions include, for example, a bath temperature of 2
The plating may be performed at a constant current or a constant potential with or without stirring at about 0 to 80 ° C. As the anode, for example, tin, silver, tin-silver alloy, platinum, platinum-plated titanium, carbon or the like can be used.

When plating is performed in the tin-silver alloy plating bath of the present invention, the object to be plated is not particularly limited, and any material can be used as long as it can be electroplated.

[0022]

EXAMPLES Examples of the aqueous solution for forming a metal complex will be described below in Examples 1 to 4, and examples of a tin-silver alloy plating bath and a method for producing a plated product will be described in Examples 5 to 28. The invention is not limited to these few examples,
The components of the aqueous solution for forming a metal complex, the composition of the tin-silver alloy plating solution, and the plating conditions can be arbitrarily changed according to the purpose of the above-mentioned purpose.

Example 1 K ₄ P ₂ O ₇ 165 g / l KI 166 g / l The above aqueous solution for forming a metal complex was prepared. In this aqueous solution
When NiSO ₄ .6H ₂ O 53g and AgNO ₃ 2.4g were added, all the metals dissolved as complex ions and became a yellow green transparent aqueous solution. The pH was 9.1. In addition, no change in appearance was observed even after the storage test for one month or more.

Example 2 K ₄ P ₂ O ₇ 165 g / l KI 250 g / l The above aqueous solution for forming a metal complex was prepared. In this aqueous solution
When CuSO ₄ .5H ₂ O (12.5 g) and AgI (4.7 g) were added, all the metals dissolved as complex ions and became a deep blue and transparent aqueous solution. The pH was 9.2. In addition, no change in appearance was observed even after the storage test for one month or more.

Example 3 K ₄ P ₂ O ₇ 165 g / l KI 330 g / l The above aqueous solution for forming a metal complex was prepared. The aqueous solution was colorless and transparent, and no change in appearance was observed even after the standing test for 3 months or more. The pH was 8.9. In this aqueous solution
When SnP ₂ O ₇ 42 g, CuP ₂ O ₇ 0.5 g and AgI 1.2 g were added, all the metals were dissolved as complex ions, and a pale blue and transparent aqueous solution was obtained. In addition, no change in appearance such as precipitation was observed after the storage test for more than 3 months.

Example 4 K ₄ P ₂ O ₇ 180 g / l KI 350 g / l The above aqueous solution for forming a metal complex was prepared. The aqueous solution was colorless and transparent, and no change in appearance was observed even after the standing test for 3 months or more. The pH was 9.0. In this aqueous solution
When 42 g of SnP ₂ O ₇ , 1.5 g of ZnSO ₄ .7H ₂ O and 0.5 g of AgI were added, all the metals dissolved as complex ions, forming a colorless and transparent aqueous solution. In addition, no change in appearance such as precipitation was observed after the storage test for more than 3 months.

Example 5 SnCl ₂ .2H ₂ O 45 g / l K ₄ P ₂ O ₇ 200 g / l AgI 1.2 g / l KI 330 g / l A tin-silver alloy plating bath having the above composition was prepared. The bath was colorless and transparent, and no change in appearance such as precipitation was observed even after the storage test for 3 months. Moreover, pH was 8.9. Using this bath, temperature 25 ℃, no stirring, current density 0.1
DC plating was performed on a pure copper substrate under the condition of ~ 1A / dm ² . Table 1 shows the silver content (% by weight), current efficiency, and appearance of the tin-silver alloy film obtained at each current density. From this result, it can be seen from the bath of this composition that tin with a high current efficiency of 5 to 19% silver content
It can be seen that a silver alloy film is obtained.

[0028]

[Table 1]

Example 6 SnCl ₂ .2H ₂ O 45 g / l K ₄ P ₂ O ₇ 200 g / l AgI 4.7 g / l KI 330 g / l A tin-silver alloy plating bath having the above composition was prepared. The bath was colorless and transparent, and no change in appearance such as precipitation was observed even after the storage test for 3 months. Moreover, pH was 8.9. Using this bath, temperature 25 ℃, no stirring, current density 0.1
DC plating was performed on a pure copper substrate under the condition of ~ 1A / dm ² . Table 2 shows the silver content (% by weight), current efficiency, and appearance of the tin-silver alloy film obtained at each current density. From this result, it can be seen that a tin-silver alloy film having a silver content of 20 to 75% can be obtained from a bath having this composition with high current efficiency.

[0030]

[Table 2]

Example 7 Sn ₂ P ₂ O ₇ 74 g / l K ₄ P ₂ O ₇ 120 g / l AgI 4.7 g / l KI 330 g / l A tin-silver alloy plating bath having the above composition was prepared. This bath was colorless and transparent and had a pH of 7.0, and no change in appearance such as precipitation after the 1-month storage test was observed. With this bath,
DC plating was performed on a pure copper substrate at a temperature of 25 ° C. without stirring and a current density of 0.1 to 1 A / dm ² . Table 3 shows the silver content (% by weight), current efficiency, and appearance of the tin-silver alloy film obtained at each current density. From this result, it can be seen that a tin-silver alloy film having a silver content of 20 to 75% can be obtained from a bath having this composition with high current efficiency.

[0032]

[Table 3]

Example 8 Sn ₂ P ₂ O ₇ 103 g / l K ₄ P ₂ O ₇ 330 g / l AgI 1.2 g / l KI 330 g / l A tin-silver alloy plating bath having the above composition was prepared. This bath was colorless and transparent and had a pH of 8.9, and no change in appearance such as precipitation was observed even after a standing test for one month or more. Using this bath, direct current plating was performed on a pure copper substrate under the conditions of a temperature of 25 ° C., stirring and a current density of 0.2 to 2.2 A / dm ² . Silver content (% by weight) of the tin-silver alloy coating obtained at each current density, current efficiency,
The appearance is shown in Table 4. From this result, it can be seen that a tin-silver alloy coating having a silver content of 2 to 18% can be obtained from a bath having this composition with high current efficiency. In particular, the tin-silver alloy used as the solder alloy is preferably a composition having a silver content of about 3.5% from the viewpoint of the melting point of the alloy, etc.
A tin-silver alloy coating with a silver content of 2-5% was obtained in the range of 2.2 A / dm ² .

[0034]

[Table 4]

Examples 9 to 13 The plating baths described in 9 to 13 of Table 5 below were prepared (the addition amount of each component was g / l). All of these plating baths were colorless and transparent, and no change in appearance was observed even after a standing test for one month or more.

[Table 5] Using these plating baths, a copper plate was used as the cathode and a platinum plate was used as the anode, and direct current plating was performed under conditions of a current density of 0.1 to 2.5 A / dm ² , a temperature of 45 ° C., and no stirring. Table 6 to Table 9 show the silver content (% by weight) and appearance (Δ: gray matte, ◯: white matte, ⊚ white semigloss) of the alloy plating film obtained under each current density condition. The current efficiency was 90% or more in all cases.

[Table 6]

[Table 7]

[Table 8]

[Table 9]

Example 14 Na ₄ P ₂ O ₇ 10H ₂ 0 224 g / l SnCl ₂ · 2H ₂ O 45.2 g / l AgNO ₃ 0.5 g / l KI 250 g / l A tin-silver alloy plating bath having the above composition was constructed. Took a bath The bath was clear and colorless, pH = 8.2. Using this bath, the temperature 6
DC plating was performed on a pure copper substrate under the conditions of 0 ℃, no stirring, and current density of 0.1 to 2.5 A / dm ² . Tin obtained at each current density
Table 10 shows the silver content (% by weight) of the silver alloy coating and the appearance (Δ: gray matte, ◯: white matte, ⊚: white semigloss). From this result, the silver content from the main plating bath under the above conditions
It can be seen that a tin-silver alloy film of 1.5 to 6.2% is obtained.

[Table 10]

Example 15 K ₄ P ₂ O ₇ 166 g / l SnCl ₂ · 2H ₂ O 45.2 g / l Ag ₂ SO ₄ 0.42 g / l KI 250 g / l A tin-silver alloy plating bath having the above composition was prepared. did. This bath was colorless and transparent, and had a pH of 9.0. Using this bath, the temperature is 8
DC plating was performed on a pure copper substrate under conditions of 0 ° C, no stirring, and current density of 0.5 to 3.0 A / dm ² . Tin obtained at each current density
Table 11 shows the silver content (% by weight) and appearance (Δ: gray matte, ◯: white matte, ⊚: white semigloss) of the silver alloy film. From this result, the silver content from the main plating bath under the above conditions
It can be seen that a tin-silver alloy film of 2.5 to 4.8% is obtained.

[Table 11]

Example 16 K ₄ P ₂ O ₇ 330 g / l Sn ₂ P ₂ O ₇ 103 g / l AgI 1.2 g / l KI 250 g / l sodium lauryl sulfate 0.5 g / l Tin-silver alloy plating bath having the above composition Took a bath. The bath was colorless and transparent, and had a pH of 9.2. Using this bath, the temperature is 8
DC plating was performed on a pure copper substrate under conditions of 0 ° C, no stirring, and current density of 0.5 to 3.0 A / dm ² . Tin obtained at each current density
Table 12 shows the silver content (% by weight) of the silver alloy film and the appearance (Δ: gray matte, ◯: white matte, ⊚: white semigloss). From this result, the silver content from the main plating bath under the above conditions
It can be seen that a tin-silver alloy film of 1.4 to 5.2% is obtained.

[Table 12]

Example 17 K ₄ P ₂ O ₇ 250 g / l Sn ₂ P ₂ O ₇ 62 g / l AgI 0.7 g / l KI 250 g / l salicylic acid 50 g / l A tin-silver alloy plating bath having the above composition was constructed. Took a bath This bath was colorless and transparent and had a pH of 6.6. Using this bath, temperature 2
DC plating was performed on a pure copper substrate under the conditions of 5 ° C. without stirring and a current density of 0.1 to 1.5 A / dm ² . Tin obtained at each current density
Table 13 shows the silver content (% by weight) and appearance (Δ: gray matte, ◯: white matte, ⊚: white semigloss) of the silver alloy film. From this result, it is understood that a white semi-gloss tin-silver alloy film can be obtained from the present plating bath under the above conditions.

[Table 13]

Example 18 K ₄ P ₂ O ₇ 250 g / l SnCl ₂ · 2H ₂ O 68 g / l AgI 0.7 g / l KI 250 g / l N, N′-dimethylformamide 100 ml / l Tin-silver having the above composition An alloy plating bath was set up. This bath was colorless and transparent and had a pH of 8.9. Using this bath, temperature 2
DC plating was performed on a pure copper substrate under the conditions of 5 ° C. without stirring and a current density of 0.1 to 1.0 A / dm ² . Tin obtained at each current density
Table 14 shows the silver content (% by weight) of the silver alloy film and the appearance (Δ: gray matte, ◯: white matte, ⊚: white semi-gloss, star: gloss). From this result, it can be seen that a bright tin-silver alloy film can be obtained from the present plating bath.

[Table 14]

Example 19 Using a plating bath having the composition described in Example 8, at a temperature of 25 ° C.
DC plating was performed on a pure copper plate under the condition of stirring with a stirrer. Current density, film composition (silver content wt%), current efficiency,
Table 1 shows the results of appearance (○: white matte, ⊚: white semi-gloss)
It is shown in FIG. Further, no change in the appearance of the plating bath was observed even after stirring.

[Table 15]

Example 20 Pyrophosphoric acid was added to a plating bath having the composition described in Example 8.
After adjusting the pH to 8.9 to 7, direct current plating was performed on a pure copper plate at a temperature of 25 ° C. under non-stirring and stirrer stirring conditions. The film thickness is 6-7 μm. Table 16 shows the results of current density, film composition (silver content: wt%), current efficiency, and appearance (◯: white matte, ⊚: white semi-gloss). Also, pH
No change in appearance of the plating bath due to adjustment and stirring was observed.

[Table 16]

Example 21 As a result of stirring the plating bath described in Example 8 with air, no change in appearance was observed. Further, using the plating bath described in Example 8, air stirring conditions and temperature were measured by a Hull cell test.
DC plating was performed on a pure copper plate at 25 ° C. Current density, film composition (silver content: wt%), appearance (○: white matte, ◎:
Table 17 shows the white semi-glossiness.

[Table 17]

Example 22 The cross-section of a tin-silver alloy coating (silver content: 3.3 wt%) plated to a thickness of about 80 μm using the plating bath described in Example 8 was surface-analyzed with an electron beam microanalyzer. . as a result,
The obtained film had a uniform composition in the thickness direction.

Example 23 Using the plating bath described in Example 8, a tin-silver alloy coating film was deposited on a pure copper plate by a Hull cell test at 25 ° C. under stirring (stirrer stirring, air stirring) conditions. JI adhesion test
As a result of the bending test method described in SH 8504, no peeling or swelling of the film was observed at any place.

Example 24 A tin-silver alloy rod (made by Senju Metal Co., Ltd.) having a silver content of 3.5% produced by a casting method and a tin-silver alloy coating (silver content 2 A melting point of ~ 5 wt%) was measured using a thermal analyzer (DSC). As a result, the plated alloy coatings were all tin-made by casting.
Like the silver alloy (containing 3.5 wt% silver), it had a melting point (melting start temperature) of 221 ° C.

Example 25 Using the plating bath of Example 8 above, 5 × 30 × under the following conditions:
A 0.5 mm pure copper plate was plated. About the obtained tin-silver-plated copper plate, a tin-silver solder (containing 3.5 wt% silver) bath, temperature 250 ° C., 30% W was used by using a solder wetting tester (Solder Checker: (Leska SAT-2000)).
A solder wettability test was performed under the condition of applying flux of W rosin or a commercially available non-cleaning type flux. As a result, good solder wettability was obtained without observing solder repellency.

Cathode current density 1.5 to 2.5 A / dm ² bath temperature 20 ° C. or 50 ° C. No stirring or stirrer stirring Film thickness about 6 μm

Example 26 Using the plating bath described in Example 8, plating was performed on the entire surface from the end of a 5 × 30 × 0.5 mm pure copper plate to 30 mm. About the obtained tin-silver-plated copper plate, a tin-silver eutectic solder (silver content: 3.5 wt%) tank was used at a temperature of 25 with a solder wetting tester (Solder Checker: (Leska SAT-2000)).
A solder wettability test was conducted under conditions of 0 ° C., 30% WW rosin coating, immersion depth 4 mm, and atmospheric conditions. Table 18 shows the relationship between the thickness of the tin-silver alloy plating having a silver content of 3.0 wt% and the wetting time, and Table 19 shows the relationship between the composition of the tin-silver alloy coating (thickness: about 6 μm) and the wetting time. The appearance of the dipped portion after the wettability test was good, with no solder repelling and the like, and glossy.

[0050]

[Table 18]

[Table 19]

Example 27 A photosensitive resin film (resist film) having a thickness of about 25 μm was formed on a pure copper plate, and holes of 100 μm in diameter were formed in the resist film by photolithography every 50 μm in length and width, 2500 in total. The copper plate as the base was exposed. Using the plating bath described in Example 8 in this hole, the current density was 1.5.
Tin-silver plating was performed to a thickness of about 25 μm under conditions of A / dm ² , stirring and 25 ° C. After plating, the resist film was peeled off, and the plated product (tin-silver alloy plated part) was observed with an electron microscope. As a result, the plated product was formed faithfully to the shape of the holes in the resist. As a result of analyzing the composition of this plated product with an electron beam analyzer, the plated product had a silver content of 2.8.
It was made of a tin-silver alloy at a weight percentage, and no compositional variation was observed in the thickness direction. The plating bath of Example 8 was P
Although it was H8.9, no peeling of the resist film was observed even when the resist film was immersed in this plating solution for plating. The resist film does not have to be photosensitive. In this case, the resist film can be formed into a desired pattern by laser processing such as excimer laser.

Example 28 A photosensitive resin film (resist film) having a thickness of about 25 μm was formed on a pure copper plate, and holes of 100 μm in diameter were formed in the resist film by photolithography every 50 μm in length and width, 2500 in total. The copper plate as the base was exposed. First, nickel plating is performed in this hole by about 5 μm, and then a current density of 2.0 A / dm ² , using the plating bath described in Example 8.
Tin-free under conditions of stirring, 25 ° C, and an electric current of 50 C / cm ^2.
It was silver plated. After plating, the resist film was peeled off, and the plated product was observed with an electron microscope. As a result, the plated product grew more than the thickness of the resist film and was mushroom-shaped (the part protruding above the resist film had a hemispherical shape larger than the hole diameter Form). This mushroom-shaped plated product was melted in a hydrogen atmosphere and the appearance was observed again with an electron microscope.
A shape having an overall size of 00 μm and a height of 70 μm and having a substantially hemispherical shape was obtained. As a result of cross-section analysis of this hemispherical shape with an electron beam microanalyzer, silver and tin were uniformly distributed in this hemispherical shape, and the silver content was 3 w.
t%. The resist film does not have to be photosensitive. In this case, the resist film can be formed into a desired pattern by laser processing such as excimer laser.

[0053]

As described above, the aqueous solution for forming a metal complex of the present invention can convert various kinds of metals into stable complex ions. That is, the present invention is novel in that it has found out a combination of two kinds of compounds which do not adversely affect each other and have an effective complexing effect on other kinds of metals, and is very epoch-making. . On the other hand, the tin-silver alloy plating bath of the present invention can obtain a tin-silver alloy coating of any composition with high current efficiency without using any cyanide which is harmful to the human body. Superior to silver plating bath. In addition, the main plating bath withstands air agitation, is very stable, and the tin-silver alloy coating plated from the main plating bath has good appearance, adhesion, and solder wettability, and does not contain lead. As an alloy, it is harmless to the human body and superior to the conventional tin-lead solder plating alloy.

Claims (18)

[Claims] 1. An aqueous solution for forming a metal complex, which contains at least a pyrophosphate compound and an iodine compound as a basic composition. 2. The aqueous solution for forming a metal complex according to claim 1, which contains a pyrophosphate salt and / or pyrophosphoric acid as the pyrophosphate compound. 3. The aqueous solution for forming a metal complex according to claim 1, wherein the iodine compound contains iodide, iodite and / or iodine. 4. A tin-silver alloy plating bath containing at least a tin compound, a silver compound, and a pyrophosphoric acid compound and an iodine compound as a complexing agent thereof as a basic composition. 5. The tin-silver alloy plating bath according to claim 4, which contains a pyrophosphate and / or pyrophosphate as the pyrophosphate compound. 6. The tin-silver alloy plating bath according to claim 4 or 5, which contains iodide, iodite and / or iodine as the iodine compound. 7. The method according to claim 4, wherein the tin compound contains at least a tin inorganic acid or organic acid compound, and the silver compound contains a silver inorganic acid or organic acid compound. Tin-silver alloy plating bath. 8. As the tin compound, tin chloride, tin sulfate, tin pyrophosphate, tin iodide, stannic acid, potassium stannate, tin acetate,
8. An inorganic acid or an organic acid tin selected from the group consisting of tin methanesulfonate, tin alkanolsulfonate and tin phenolsulfonate.
The described tin-silver alloy plating bath. 9. Silver iodide, silver chloride, as the above silver compound,
Silver nitrate, silver sulfate, silver pyrophosphate, silver iodate, silver acetate,
8. An inorganic or organic acid silver salt of at least one selected from silver methanesulfonate, silver alkanolsulfonate, and silver phenolsulfonate.
The described tin-silver alloy plating bath. 10. The tin according to claim 4, which contains a pyrophosphate compound and an iodine compound in an amount necessary for allowing tin and silver to exist as complex ions. -A silver alloy plating bath. 11. A tin-silver alloy is electroplated on an object to be plated with a tin-silver alloy plating solution containing a tin compound, a silver compound, and a pyrophosphoric acid compound and an iodine compound as a complexing agent for these compounds as a basic composition. A method for producing a plated product, which comprises forming an alloy plated portion. 12. A step of forming a resin film on an object to be plated, a step of forming the resin film into a required pattern, and a step of forming the resin film of the pattern as a mask on the object to be plated.
A tin compound, a silver compound, and a step of electrolytically plating a tin-silver alloy plating solution containing a pyrophosphoric acid compound and an iodine compound as a complexing agent thereof as a basic composition to form a tin-silver alloy plating part. And a method for producing a plated product. 13. The method for producing a plated product according to claim 12, wherein the resin film is a photosensitive resin film, and the photosensitive resin film is formed into a desired pattern by photolithography. 14. The method for producing a plated product according to claim 11, 12 or 13, characterized by containing a pyrophosphate and / or pyrophosphate as the pyrophosphate compound. 15. The iodine compound as the above iodine compound,
The method for producing a plated product according to claim 11, 12, 13 or 14, which contains iodite and / or iodine. 16. At least a tin inorganic acid or organic acid compound is contained as a tin compound, and a silver inorganic acid or organic acid compound is contained as a silver compound. Or the method for producing a plated product according to item 15. 17. A tin chloride, a tin sulfate, or the like as the tin compound.
Tin pyrophosphate, tin iodide, stannic acid, potassium stannate, tin acetate, tin methanesulfonate, tin alkanolsulfonate,
The method for producing a plated product according to claim 16, further comprising at least one inorganic acid or tin organic acid selected from tin phenolsulfonate. 18. Silver iodide, silver chloride, silver nitrate, silver sulfate, silver pyrophosphate, silver iodate, silver acetate, silver methanesulfonate, silver alkanolsulfonate, as the silver compound.
The method for producing a plated product according to claim 16, further comprising at least one inorganic acid or organic acid silver selected from silver phenolsulfonate.