JP2709511B2 - Tin, lead, tin-lead alloy electroplating bath and electroplating method - Google Patents

Description

The present invention relates to a novel tin-lead alloy electroplating bath and an electroplating method using the bath.

[Problems to be solved by conventional technology and invention]

2. Description of the Related Art Tin, tin-lead alloy electroplating has been widely used in the fields of light current and electronics for mainly solderability.

Conventionally, an electroplating bath used for such tin, tin-lead alloy electroplating is mainly a sulfuric acid bath, an organic sulfonic acid bath or a borofluoric acid bath, and is a strongly acidic bath having a pH of 1 or less.

There is no particular problem in using these strongly acidic baths when the object to be plated is copper, steel, or the like. Recently, however, there have been many electronic components made of composite materials using metals and ceramics, glass, plastics, and the like as materials to be plated. For example, cerdip type IC packages sealed with lead glass, Chip capacitors are being used. Further, an increasing number of electronic components have been formed by depositing aluminum on ceramic and etching to form a circuit. If these parts are plated with tin or tin-lead alloy from the above-mentioned strong acid bath, the ceramic, glass or vapor-deposited aluminum and the like in the parts are eroded, and furthermore, the problem of bridging that plating is applied on the insulator occurs. was there.

Such a problem can be solved by adjusting the pH of the plating bath to 2 to 9. However, simply increasing the pH of the plating bath to 2-9
In this case, tin ions and lead ions precipitate as hydroxides, making plating impossible.

On the other hand, conventionally, as a tin, tin-lead alloy electroplating bath,
Various baths using citric acid, gluconic acid, pyrophosphoric acid, organic phosphonic acid, salts thereof and the like which can be used in the above pH range have been proposed (JP-A-49-93236, JP-A-53-5034).
Nos. 54-60230, 54-69533, 54-69534,
Nos. 57-63689, 61-194194, etc.), and a pH of 2 to
A plating bath capable of favorably performing tin-lead alloy plating in the region of No. 9 is desired.

The present invention has been made in view of the above circumstances, and is a tin-lead alloy plating bath that is stable in a pH range of 2 to 9, has high current efficiency, and can be used in a wide current density range, and an electroplating method using the plating bath. The purpose is to provide.

[Means and actions for solving the problem]

The present inventors have conducted intensive studies to achieve the above object, and as a result, the following formulas (1) and (2) were used as complexing agents for a plating bath containing tin ions and lead ions. (However, R represents a hydrogen atom, an alkyl group or a hydroxyalkyl group having 1 to 4 carbon atoms, M represents a hydrogen atom, an alkali metal atom or an NH ₄ group, n is an integer of 2 to 7, and m is an integer of 1 to 6. By using one or more aromatic polyhydroxysulfonic acids in which at least two OH groups are at ortho positions to each other, the compound is stable in the pH range of 2 to 9, and can be tin or lead. Can be plated without erosion of electronic parts made of a composite material with a metal using ceramic, lead glass, vapor-deposited aluminum, and the like. The present inventors have found that the bath No. 9 has a high current efficiency, can be used in a wide range of current density, and can obtain a good plating film, and has accomplished the present invention.

Accordingly, the present invention provides a tin-lead alloy plating bath containing tin ions and lead ions as a complexing agent in which at least two OH groups represented by the above formulas (1) and (2) are at ortho positions to each other. A compound comprising one or more compounds, and having a pH of 2 to 9;
A lead alloy electroplating bath and a tin-lead alloy electroplating method characterized by electroplating an object to be plated using the plating bath.

 Hereinafter, the present invention will be described in more detail.

In the plating bath of the present invention, the metal salt that provides tin ions and lead ions is not particularly limited. Examples of the tin salt include tin sulfate, tin chloride, tin nitrate, tin methanesulfonate, tin alkanol sulfonate, and tin phenol sulfonate. , Tin borofluoride, tin acetate, tin oxide and the like. In this case, the tin salt may be a divalent tin salt or a tetravalent tin salt. On the other hand, examples of the lead salt include lead nitrate, lead acetate, lead borofluoride, lead methanesulfonate, lead chloride, lead sulfate, and lead oxide.

The concentration of the above tin ions and lead ions in the plating bath is appropriately selected, but is usually 0.5 to 200 g / more preferably 1 to 100 g.
/.

The present invention provides the following formulas (1) and (2) as a complexing agent in a plating bath containing tin ions and / or lead ions. (However, R represents a hydrogen atom, an alkyl group or a hydroxyalkyl group having 1 to 4 carbon atoms, M represents a hydrogen atom, an alkali metal atom or an NH ₄ group, n is an integer of 2 to 7, and m is an integer of 1 to 6. Wherein at least two OH groups are ortho to each other, and one or more aromatic polyhydroxysulfonic acids are blended.

In this case, specific examples of these aromatic polyhydroxysulfonic acids include sodium catechol disulfonic acid, sodium 1,2-dihydroxy-4,5-naphthalene disulfonate, and 1,2,3-trihydroxy-5-benzenesulfonic acid. And sodium 1,2-dihydroxy-3-methyl-4,6-benzenedisulfonate.

The amount of addition of these aromatic polyhydroxysulfonic acids is also variously selected, but is usually 1 to 600 g /, more preferably 20 to 200 g /.

In the plating bath of the present invention, other complexing agents such as citric acid, pyrophosphoric acid, gluconic acid and salts thereof may be added in addition to the above complexing agents.

If necessary, a conductive salt, a pH buffer, a surfactant, a brightener and the like can be further added to the plating bath of the present invention.

Here, as the conductive salt, ammonium methanesulfonate, ammonium sulfate, ammonium chloride, sodium sulfate, potassium chloride, ammonium acetate, ammonium ascorbate, sodium alkanolsulfonate, sodium phenolsulfonate and the like can be used. The addition can lower the plating voltage and improve the throwing power. The blending amount can be 0 to 800 g /, preferably 10 to 800 g /
, More preferably 50 to 300 g /.

Examples of the pH buffer include boric acid, ammonium chloride, ammonium sulfate, ammonium acetate, sodium phosphate, potassium phosphate, sodium borate, potassium borate, sodium formate, potassium formate, ammonium citrate, sodium citrate and the like. No. The addition amount is preferably 0 to 100 g /, particularly preferably 10 to 50 g /.

Furthermore, nonionic, cationic, and
Zwitterionic or anionic surfactants can be used.
In this case, these surfactants are not particularly limited and variously selected, but those having a high clouding point or no clouding point are preferred.

More preferably, nonionic surfactants obtained by adding 15 mol of ethylene oxide to nonylphenol, alkyl β-naphthol (alkyl group having 1 to 1 carbon atoms)
25) to which 25 mol of ethylene oxide is added, and polynuclear phenol ethoxylates (for example, Adecitol PC-10 and PC-13 manufactured by Asahi Denka Kogyo KK) and the like. Also,
As the cationic surfactant, those obtained by adding 10 mol of ethylene oxide to laurylamine, those obtained by adding 15 mol of ethylene oxide to tallow alkylamine, and the like are suitably used. Further, as the zwitterionic surfactant, imidazoline-based surfactants, in particular, the following formula (However, R ¹ is an alkyl group having 3 to 25 carbon atoms, and R ² is an alkyl group having 1 carbon atom.
(For example, Amogen No. 8 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) is preferable.

The addition of the above-mentioned nonionic, cationic and amphoteric surfactants has the effect of smoothing and densifying the plating film, but the addition amount of these surfactants is 0.01 to 30 g /
It can be.

As a leveling agent, polyethylene glycol such as Carbowax 1500 can be added together with or instead of the above surfactant.

On the other hand, anionic surfactants have the effect of particularly eliminating gas pits in plating and increasing the cloud point of nonionic surfactants. Examples of anionic surfactants include sodium lauryl sulfate and sodium alkylbenzene sulfonate. , Sulfosuccinic acid alkyl esters and the like can be used. The amount of the anionic surfactant added is 0.1 to 5
It can be 0 g /.

When bright plating is required, a brightener is added. As brighteners, aliphatic aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, glyoxal, succinaldehyde, caproaldehyde, and aldol, benzaldehyde, salicylaldehyde aryl ether , p-Tolualdehyde, 1-naphthaldehyde, salicylaldehyde, veratraldehyde, anisaldehyde, piperonal, vanillin and other aromatic aldehydes can be used. Further, sulfanilic acid derivatives,
Triazine derivatives, acrylic acid, methacrylic acid, crotonic acid, and other α-unsaturated carboxylic acids can also be used. The addition amount of these brighteners is 0.01 to 30 g /,
In particular, it can be 0.03 to 5 g /.

The pH of the plating bath of the present invention is 2 to 9, preferably 3 to 8.5, more preferably 5 to 8. In this case, ammonia water, caustic, or the like can be used to adjust the pH.

When performing electroplating using the above-mentioned plating bath, the power source is such that when a matte or semi-glossy plating film is obtained, the appearance of the plating film (parts where plating crystals become large and the parts become black) is considered. Full DC, three-phase full wave,
It is recommended to use single-phase full-wave or single-phase half-wave rectification rather than three-phase half-wave rectification, and a pulse power supply or the like is also used. on the other hand,
When obtaining a bright plating film, conversely, a single-phase full-wave
It is recommended to use full DC, three-phase full-wave, three-phase half-wave rectification rather than single-phase half-wave rectification.

The plating bath of the present invention can be used not only for ordinary rack plating, but also for barrel plating, and can also be applied to high-speed plating, through-hole plating, and the like. Plating conditions are selected according to the type of plating and the like. According to the plating bath of the present invention, a uniform and dense plating film can be obtained over a wide range of current densities. In particular,
The plating temperature can be 5 to 90 ° C., more preferably 10 to 60 ° C., and the cathode current density can be 0.001 to 30 A / dm ² , more preferably 0.1 to 10 A / dm ² . In addition, agitation, barrel rotation, cathode locking, pump flow,
It can be performed by liquid flow, air agitation or the like by supercooling, and in some cases, no agitation may be used. Depending on the type of plating bath, metallic tin, metallic lead, or, in the case of tin-lead alloy plating, a combination of metallic tin and metallic lead or a tin-lead alloy depending on the composition of the plating film However, an insoluble anode may be used.

In the present invention, the object to be plated is not limited and may be any as long as it can be electroplated. In particular, the present invention is suitable for plating of electronic components made of a composite material of metal and ceramic, glass, and the like. It is.

Hereinafter, the present invention will be described in detail with reference to Examples,
The present invention is not limited to the following examples.

[Example 1] Stannous methanesulfonate (as Sn) 10 g / lead methanesulfonate (as Pb) 1 ナ ト リ ウ ム sodium 1,2-dihydroxy-3,5-benzenedisulfonate 50 〃 boric acid 30 牛 tallow amine using a plating bath of ethylene oxide 15 mol adduct 1 〃 (adjusted with aqueous ammonia) methanesulfonic acid 100 〃 pH 7 the composition, 40 ° C. on a copper plate by single-phase full-wave rectification, the condition of D _K 1A / dm ² Plated for 10 minutes.

As a result, a smooth dense white semi-gloss tin-lead alloy plating film was obtained. The Pb content in the film was 10%, and the current efficiency was 99%.

In addition. D _K 1A / d for IC parts with lead glass by the above plating bath
Although plating of about 7 μm was performed at m ² , a tin-lead alloy plating film having a good white semi-gloss was obtained without attacking the lead glass.

In addition, after performing a zinc substitution treatment on a ceramic plate having an aluminum vapor-deposited film by a conventional method, a 10 μm tin-lead alloy plating was performed using the above plating bath, but without dissolving and eroding the vapor-deposited aluminum. Then, a tin-lead alloy plating film was formed on the evaporated aluminum with good adhesion.

[Example 2] Stannous sulfate (as Sn) 10 g / lead methanesulfonate (as Pb) 1 {sodium 1,2,3-trihydroxy-5-benzenedisulfonate 50} boric acid 30} ethylene in tallowamine 15 mol of oxide adduct 1 物 ammonium sulfate 50〃pH (adjusted with ammonia water) 7 Plating was carried out in the same manner as in Example 1 using the plating bath having the above composition, and the same results as in Example 1 were obtained.

Example 3 In the plating bath of Example 1, 1,2-dihydroxy-
When plating was performed using sodium 1,2-dihydroxy-4,5-naphthalene disulfonate instead of sodium 3,5-disulfonate, the same results as in Example 1 were obtained.

[Example 4] Stannous 3-hydroxy-1-propanesulfonate (as Sn) 20 g / sodium 1,2-dihydroxy-3-methyl-4,6-benzenedisulfonate 100 {triammonium citrate 30} adecitol PC-10 3 ナ ト リ ウ ム Sodium sulfate 50 ベ ン Benzalacetone 0.1 〃 pH 6 25 ° C, D
Plating was performed for 5 minutes under the conditions of _K 2A / dm ² .

As a result, a smooth and dense bright tin plating film was obtained.
The current efficiency was 99%.

In addition, D _K 2A / d
Although plating of about 8 μm was performed at m ² , a good bright tin plating film was obtained without attacking the lead glass.

[Example 5] Lead acetate (as Pb) 10 g / potassium phenolsulfonate 50 {sodium catechol disulfonate 70} Ammogen No. 83 {N- (3-hydroxybutylidene) -p-sulfanilic acid 0.2} pH 7.5 50% on a copper plate by single-phase half-wave rectification using a plating bath
° C., was performed 5 minutes plating under the condition of D _K 3A / dm ^2.

As a result, a smooth and dense semi-bright lead plating film was obtained. The current efficiency was 98%.

〔The invention's effect〕

According to the present invention, a good tin, lead, or tin-lead alloy plating film is provided in the pH range of 2 to 9, and the current efficiency is high, and it can be used in a wide current density range. It is preferably used.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Taichi Nakamura, 1-5-1 Exit, Hirakata City, Osaka Prefecture Inside Central Research Laboratory, Uemura Industries Co., Ltd. (72) Inventor Kiyoshi Asakawa, 1-1-5-1 Exit, Hirakata City, Osaka Prefecture Uemura Industrial Co., Ltd. Central Research Laboratory (56) References JP-A-49-29240 (JP, A) JP-A-50-118934 (JP, A) JP-A-47-33732 (JP, A) 16176 (JP, B2) JP-B 55-29159 (JP, B2)

Claims (2)

(57) [Claims] (1) The following formulas (1) and (2) are used as a complexing agent in a tin-lead alloy plating bath containing tin ions and lead ions. (However, R represents a hydrogen atom, an alkyl group or a hydroxyalkyl group having 1 to 4 carbon atoms, M represents a hydrogen atom, an alkali metal atom or an NH ₄ group, n is an integer of 2 to 7, and m is an integer of 1 to 6. And at least two OH groups are in the ortho position with respect to each other.
Is a tin-lead alloy electroplating bath of 2 to 9. 2. A tin-lead alloy electroplating method, comprising electroplating an object to be plated using the electroplating bath according to claim 1.