JPS6214639B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electroplating bath for tin, lead and tin-lead alloys using an alkane or alkanolsulfonic acid as a common soluble complex salt of divalent tin and lead. In recent years, tin and tin-lead alloy platings have been widely used as films for improving solderability and films for etching resists in parts for the light electrical industry and the electronic industry. However, industrially, borofluoride baths are widely used as baths for uniformly plating tin, lead, and tin-lead alloys at high speeds. However, borofluoride baths are highly corrosive and toxic, which not only puts a heavy burden on plating equipment and operations, but also makes wastewater treatment difficult. Although the problem of borofusate can be solved by using advanced processing technology, processing involves a large amount of expense and there is considerable economic loss. An object of the present invention is to provide a tin, lead, and tin-lead alloy plating bath that can provide uniform and dense plating at high speed without using boronic acid, which has many problems in terms of pollution control. The present inventor has developed an alkanesulfonic acid or alkanolsulfonic acid and their tin and/or
By using a plating bath mainly composed of lead salts, and adding certain surfactants and smoothing additives in combination, it has performance comparable to or better than that of borofusate baths. In addition, it can be carried out under a wide range of current conditions from high current areas to low current areas, and can be used at high speeds to produce homogeneous and dense tin, lead or tin.
We have discovered a plating bath that provides lead alloy plating (see Japanese Patent Application No. 176365/1983). As a result of further research, it was found that among the above-mentioned surfactants, certain nonionic surfactants are particularly effective. Therefore, the present invention provides a main plating bath containing an alkanesulfonic acid or an alkanolsulfonic acid and either or both of their divalent tin salt and divalent lead salt. The present invention relates to a tin, lead or tin-lead alloy plating bath in which one or more smoothing additives are added together with one or more smoothing additives. The main plating bath of the present invention basically comprises one or more alkanesulfonic acids or alkanolsulfonic acids, and one or more tin salts or lead salts of these sulfonic acids, or both. The alkanesulfonic acids or alkanolsulfonic acids that can be used are those having the following general formula. R-SO ₃ H [Here, R: alkyl group (C _1-12 )] HO-R-SO ₃ H _[ Here, R: alkyl group (C _1-12 ), hydrogen group is any alkyl group Examples of alkanesulfonic acids include methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid,
-Propanesulfonic acid, butanesulfonic acid, 2-
These include butanesulfonic acid, pentanesulfonic acid, hexanesulfonic acid, decanesulfonic acid, dodecanesulfonic acid, and the like. These alkanesulfonic acids can be used alone or as a mixture of two or more. Examples of alkanolsulfonic acids are isethionic acid (2-hydroxyethane-1-sulfonic acid), 2-
Hydroxypropane-1-sulfonic acid, 1-hydroxypropane-2-sulfonic acid, 3-hydroxypropane-1-sulfonic acid, 2-hydroxybutane-1-sulfonic acid, 4-hydroxybutane-
1-sulfonic acid, 2-hydroxypentane-1-
These are sulfonic acid, 2-hydroxyhexane-1-sulfonic acid, 2-hydroxydecane-1-sulfonic acid, and 2-hydroxydodecane-1-sulfonic acid. These hydroxy-containing alkanesulfonic acids can be used alone or as a mixture of two or more. In the case of a tin plating bath, it contains an alkanesulfonic acid or alkanolsulfonic acid and its tin salt as described above, and in the case of a lead plating bath, it also contains a sulfonic acid and its lead salt, and furthermore, a tin-lead alloy plating bath. contains sulfonic acid and its tin and lead salts. The total concentration of tin and/or lead salts is 0.5 to 200 g/metal, preferably 10 to 200 g/metal.
100g/. Furthermore, the concentration of free alkanesulfonic acid or alkanolsulfonic acid present in the plating bath is at least stoichiometrically equivalent to divalent tin and/or lead ions in the bath. The nonionic surfactant added to the plating bath of the present invention not only improves the dispersibility of the plating bath, but also
It makes it possible to obtain a dense and smooth plating with good adhesion. It was also found that the nonionic surfactant has the effect of improving the throwing power in the low current section. In addition, as described below, by further using a certain type of smoothing additive, a further synergistic effect can be obtained, which can be applied to all plating methods such as barrel plating, ratchet plating, high-speed continuous plating, and through-hole plating. becomes possible. The plating bath of the present invention also contains a cationic surfactant that has the effect of suppressing discoloration and the growth of dendrites (resin-like) in high-current areas, for example,
Quaternary alkylammonium salts, pyridinium salts, imidazolinium salts, and betaine type cationic surfactants as described in Japanese Patent No. 176365 can be added. Therefore, in the present invention, plating can be performed under a wide range of current conditions by using both surfactants in combination depending on the current conditions. In the present invention, the nonionic surfactant found to be effective has the following general formula () (Here, A is a residue of a C _8-20 alkanol,
C _1-25 alkyl phenol residue, C _1-25 alkyl β-naphthol residue, C _3-22 fatty acid amide residue, C _1-25 alkoxylated phosphoric acid residue, C _8-
Represents the residue of a sorbitan ester esterified with a C ₂₂ higher fatty acid or the residue of a styrenated phenol (the hydrogen of the phenol nucleus may be substituted with a C _1-4 alkyl or phenyl group), R′ and R″ represents a hydrogen atom or a methyl group,
However, when R′ represents a hydrogen atom, R″ represents a methyl group, and when R′ represents a methyl group,
R'' represents a hydrogen atom, m represents an integer of 1 to 30, and n represents an integer of 1 to 30. Nonionic surfactant of formula () that can be used in the plating bath of the present invention are well known in the art, and are esterified with C _8-22 higher alcohols, alkyl phenols, alkyl β-naphthols, C _3-22 fatty acid amides, alkoxylated phosphoric acids, and C _8-22 higher fatty acids by well-known methods. It can be produced by addition condensation of ethylene oxide (or propylene oxide) to sorbitan or styrenated phenol, and further addition condensation of propylene oxide (or ethylene oxide). Examples of the alcohol include octanol, decanol, lauryl alcohol, tetradecanol, hexadecanol, stearyl alcohol, eicosanol, cetyl alcohol, oleyl alcohol, cetyl alcohol, and docosanol. Examples of the alkyl phenol include mono, di, and tri-alcohol. -alkyl-substituted phenols, such as p-butylphenol, p-isooctylphenol, p-nonylphenol, p-hexylphenol, 2.
Examples include 4-dibutylphenol, 2,4,6-tributylphenol, p-dodecylphenol, p-laurylphenol, and p-stearylphenol. The alkyl group of alkyl β-naphthol includes methyl, ethyl, propyl, butyl, hexyl, octyl, decyl, dodecyl,
Examples include octadecyl, which can be located at any position in the naphthalene nucleus. As a fatty acid amide,
propionic acid, butyric acid, caprylic acid, capric acid,
Amides include lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid. Alkoxylated phosphoric acid has the following formula: (Here, Ra and Rb are _C1-25 alkyl groups, one of which may be a hydrogen atom.) That is, one or two hydroxyl groups of phosphoric acid are esterified with an alcohol having an appropriate chain length (C ₁ to _{C 25} ). As a styrenated phenol, the following formula (Here, Rc: hydrogen, C _1-4 alkyl group or phenyl group x: 1-3)
It may be substituted with a C _1-4 alkyl group or a phenyl group. Suitable examples include mono-, di- or tristyrenated phenols, mono- or distyrenated cresols, mono- or distyrenated phenylphenols, and the like. It may be a mixture of these. Sorbitan esterified with higher fatty acids includes mono-, di- or tri-esterified 1,4-, 1,5 and 3,6-sorbitan, such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate. , sorbitan oleate, sorbitan dilaurate,
Examples include sorbitan dipalmitate, sorbitan distearate, sorbitan dioleate, and sorbitan mixed fatty ester. The above nonionic surfactants can be used alone or in combination. The concentration of nonionic surfactant used is generally from 0.01 to 50 g/, preferably from 0.03 to 20 g/. Additionally, the plating bath of the present invention contains certain smoothing additives to improve the smoothness of the plating surface. The smoothing additive exhibits a further synergistic effect when used in combination with the above-mentioned surfactant.
Smoothening additives that have been found to be particularly effective include those having the following general formulas (A) to (H). (A) [Here, R: hydrogen, alkyl group ( _C1-4 ) or phenyl group, R': hydrogen, hydroxyl group, or when absent, R'': alkylene group ( _C1-4 ), phenylene group or benzyl group R: Hydrogen or alkyl group (C _0-4 )〕 (B) [Here, X: hydrogen or alkyl group ( _C1-4 ), R: hydrogen or _-CH3 , n: an integer from 2 to 15] (C) [Here, X: halogen or alkyl group (C _1-4 ), R: hydrogen or hydroxyl group, n: integer from 0 to 10] (D) [Here, _R1 : hydrogen or _-CH3 , _R2 : alkyl group ( _C1-5 ) or hydroxyl group-containing alkyl group ( _C1-5 )] (E) [Here, R: nitro group, amino group or alkyl group (C _1-5 )] (F) [Here, R, R': alkyl group (C _1-18 )] (G) [Here, R: hydrogen, an alkyl group (C _1-4 ) or a phenyl group] (H) R-CH=CH-C≡N [Here, R: hydrogen, a phenyl group or an alkyl group (C _1-8 ) Among these smoothing additives, N-
(3-hydroxybutylidene)-p-sulfanilic acid, N-butylidenesulfanilic acid, N-cinnamoylidenesulfanilic acid, 8-propylquinoyl ether, 1-(3-hydroxybutene-1)
Benzotriazole, N・N'-dibutylidene-
o-phenylenediamine, N·N'-diisobutylidene-o-phenylenediamine, N·N'-di(3-hydroxybutylidene)-o-phenylenediamine, m-nitrobenzaldehyde, 2,4-
Diamino-6-[2'-methylimidazolyl (1')]
Ethyl-1,3,5-triazine, 2,4-diamino-6-[2'-ethyl-4-methylimidazolyl(1')]ethyl-1,3,5-triazine,
Examples include 2,4-diamino-6-[2'-undecylimidazolyl (1')]ethyl-1,3,5-triazine, phenyl salicylate, and styryl cyanide. The concentration of the smoothing additive is between 0.01 and 30 g/, preferably between 0.03 and 5 g/. As mentioned above, examples of the cationic surfactants that can be added include lauryltrimethylammonium salt, cetyltrimethylammonium salt, stearyltrimethylammonium salt, lauryldimethylethylammonium salt, octadecenyldimethyl-ethylammonium salt, lauryldimethylammonium betaine, stearyldimethylammonium betaine, dimethyl-benzyllauryl ammonium salt, cetyldimethylbenzylammonium salt, octadecyldimethylbenzylammonium salt, trimethylbenzylammonium salt, triethylbenzylammonium salt,
hexadecylpyridinium salt, laurylpyridinium salt, dodecylpicolinium salt, laurylimidazolinium salt, oleylimidazolinium salt,
Examples include stearylamine acetate, laurylamine acetate, octadecylamine acetate, and the like. The concentration of cationic surfactant used is generally from 0.01 to 50 g/, preferably from 0.03 to 20 g/. The concentrations of the above-mentioned components in the plating bath of the present invention can be arbitrarily selected depending on barrel plating, loose plating, high-speed continuous plating, through-hole plating, etc. The applicable temperature range is room temperature, and in high-speed plating, the temperature is raised to about 50 to 60 degrees Celsius. Furthermore, the plating bath of the present invention can provide homogeneous and dense plating over a wide range of current densities. Next, the composition of the plating solution and the plating work conditions according to examples of the present invention will be shown, but the present invention is not limited to these few examples, and the main purpose is to obtain homogeneous and dense plating at high speed, which is the above-mentioned objective. The composition of the plating bath and the plating conditions can be changed as desired. The coverage and appearance of the plating in Examples were evaluated by the Hull Cell test. The results are shown in Tables 1-3. Example 1 Divalent tin (used as stannous 2-hydroxypropanesulfonic acid) 20g/free 2-hydroxypropanesulfonic acid
100g / 5 moles of propylene oxide added to 7 moles of ethylene oxide adduct of lauryl alcohol 5 g / Temperature 25 (℃) Current density range 1 to 10 A/dm ² Comparative example 1 Addition of 7 moles of ethylene oxide to lauryl alcohol Furthermore, instead of the substance to which 5 moles of propylene oxide were added, a 7 mole adduct of ethylene oxide to lauryl alcohol was used. Others are the same as in Example 1. Example 2 100 g of divalent tin (used as stannous methanesulfonic acid) / 120 g of free methanesulfonic acid / 14 moles of ethylene oxide adduct of 2,4,6-tristyrenated phenol was further added with 10 moles of propylene oxide. Substance 7.5g / Temperature 35 (°C) Current density range 5-40A/dm ² Comparative example 2 Substituted with a substance obtained by adding 10 moles of propylene oxide to the 14 moles of ethylene oxide adduct of 2,4,6-tristyrenated phenol 2.
A 14 mole ethylene oxide adduct of 4,6-tristyrenated phenol was used. Others are the same as in Example 2. Example 3 40 g of divalent tin (used as stannous 2-hydroxypropanesulfonic acid) / 120 g of free ethanesulfonic acid / 2 moles of propylene oxide adduct of 2,4,6-tristyrenated phenol plus 5 ethylene oxide Mole added substance 2g/N-(3-hydroxybutylidene)-P-sulfanilic acid 0.5g/Temperature 25 (℃) Current density range 0.1-15A/dm ² Comparative example 3 2.4.6-tristyrenation Instead of a substance obtained by adding 5 moles of ethylene oxide to a 2 mole adduct of phenol with propylene oxide, 2.
A 2 mol propylene oxide adduct of 4,6-tristyrenated phenol was used. Other details are the same as in Example 3. Example 4 20 g of divalent tin (used as stannous ethanesulfonic acid) / 100 g of free ethanesulfonic acid / 10 moles of ethylene oxide added to 2 moles of prolene oxide adduct of 2,4,6-tributylphenol 2g/2,4-diamino-6-[2'-undecylimidazolyl(1')]ethyl-1,3,5-triazine
2 g / Temperature 40 (℃) Current density range 5 - 20 A / dm ² Comparative example 4 In place of the substance obtained by adding 10 moles of ethylene oxide to the 3 moles of propylene oxide adduct of 2,4,6-tributylphenol, 2. 4.6
- Using a 2 mole propylene oxide adduct of tributylphenol. Other details are the same as in Example 4. Example 5 Divalent tin (used as stannous 2-hydroxyethanesulfonic acid) 80g/Free 2-hydroxyethanesulfonic acid 120g/Substance obtained by adding 10 moles of propylene oxide to 7 moles of ethylene oxide adduct of pentadecylamide 7.5g/ N・N'-diisobutylidene-O-phenylenediamine 0.5g/ 1-(3-hydroxybutene-1)benzotriazole 0.1g/ Temperature 30 (℃) Current density range 5 to 30 A/dm ² Comparative Example 5 A 7 mole adduct of pentadecylamide with ethylene oxide was used instead of a substance obtained by adding 10 moles of propylene oxide to a 7 mole adduct of pentadecylamide with ethylene oxide. The rest is the same as in Example 5. Example 6 Divalent tin (used as stannous 2-hydroxypropanesulfonic acid) 60g/free 2-hydroxypropanesulfonic acid
150g/ A substance obtained by adding 10 moles of propylene oxide to an adduct of 4-styrenated phenol with 7 moles of ethylene oxide 3 g/ A substance obtained by adding an additional 10 moles of propylene oxide to a 7 mole adduct of 2,4-distyrenated phenol with ethylene oxide 3 g/ Substance obtained by adding 10 moles of propylene oxide to 7 moles of ethylene oxide adduct of 2,4,6-tristyrenated phenol 3g/N-(3-hydroxybutylidene)-P-sulfanilic acid 0.1g/2,4-diamino -6-[2'-undecylimidazolyl(1')]ethyl-1,3,5-triazine
2g/Temperature 30 (℃) Current density range 5-40A/dm ² Comparative example 6 Addition of 7 moles of ethylene oxide to 4-styrenated phenol plus 10 mols of propylene oxide
A substance obtained by adding 10 moles of propylene oxide to a 7 mole ethylene oxide adduct of 2,4-distyrenated phenol, and a 2.
Instead of the substance obtained by adding 10 moles of propylene oxide to the 7 moles of ethylene oxide adduct of 4,6-tristyrenated phenol, 7 moles of ethylene oxide adduct of 4-styrenated phenol and ethylene of 2,4-distyrenated phenol were used. A 7 mole oxide adduct and a 7 mole ethylene oxide adduct of 2,4,6-tristyrenated phenol were used. Same as other Example 6. Example 7 Lead (used as lead 2-hydroxypropanesulfonic acid) 20g/free 2-hydroxypropanesulfonic acid
100g/stearyl alcohol propylene oxide 2
Substance obtained by adding 10 moles of ethylene oxide to the molar adduct 1 g/N-N'-diisobutylidene-O-phenylenediamine 2 g/Temperature 40 (℃) Current density range 1 to 10 A/dm ² Comparative example 7 Stearyl alcohol Instead of the substance obtained by adding 10 moles of ethylene oxide to the 2 mole adduct of propylene oxide, a 2 mole adduct of stearyl alcohol with propylene oxide was used. The rest is the same as in Example 7. Example 8 Lead (used as lead methanesulfonate) 10g/free methanesulfonic acid 100g/substance obtained by adding 15 moles of propylene oxide to 10 moles of ethylene oxide of P-nonylphenol 5g/1-(3-hydroxybutene- 1) Benzotriazole 0.5g/Temperature 25 (℃) Current density range 1-20A/dm ² Comparative example 8 P-nonylphenol ethylene oxide 10
Instead of a substance obtained by adding 15 moles of propylene oxide to the molar adduct, an adduct of P-nonylphenol with 10 moles of ethylene oxide was used. Others are the same as in Example 8. Example 9 Lead (used as lead 2-hydroxyethanesulfonate) 20g/free 2-hydroxyethanesulfonic acid 150g/8 mole adduct of ethylene oxide of P-isooctylphenol plus 15 more propylene oxide
Added substance in moles: 3g/4 moles of ethylene oxide adduct of sorbitan monostearate, plus 2 mols of propylene oxide
Mole added substance 3g/2,4-diamino-6-[2'-undecylimidazolyl(1')]ethyl-1,3,5-triazine
1g/Temperature: 30 (℃) Current density range: 1 to 15A/dm ² Comparative example 9 Addition of 8 moles of ethylene oxide to P-isooctylphenol plus propylene oxide
P-
Ethylene oxide of isooctylphenol 8
A molar adduct and a 4 molar ethylene oxide adduct of sorbitan monostearate were used. The rest is the same as in Example 9. Example 10 Divalent tin (used as stannous 2-hydroxypropanesulfonate) 12g/Lead (used as lead 2-hydroxypropanesulfonate) 8g/free hydroxypropanesulfonic acid 100g/2,4,6-tri Substance obtained by adding 5 moles of propylene oxide to 7 moles of ethylene oxide adduct of styrenated phenol 5 g / 1-(3-hydroxybutene-1)benzotriazole 0.5 g / 2,4-diamino-6-[2'-undecyl imidazolyl(1')]ethyl-1,3,5-triazine
3g/Temperature 20 (℃) Current density range 0.1 to 10A/dm ² Comparative example 10 Instead of a substance obtained by adding 5 moles of propylene oxide to the 7 moles of ethylene oxide adduct of 2,4,6-tristyrenated phenol, 2・
A 7 mol ethylene oxide adduct of 4,6-tristyrenated phenol was used. Same as other Example 10. Example 11 18 g of divalent tin (used as stannous methanesulfonate) / 12 g of lead (used as lead ethanesulfonate) / 150 g of free methanesulfonic acid / 10 moles of ethylene oxide adduct of 6-ethylnaphthol plus propylene Substance with 2 moles of oxide added 2g/Substance with 5 moles of ethylene oxide added to undecylamide with 2 moles of propylene oxide 2g/N-(3-hydroxybutylidene)-P-sulfanilic acid 0.1g/Temperature 25 ( ℃) Current density range 1 to 10 A/dm ² Comparative example 11 6-ethylnaphthol ethylene oxide 10
Instead of a substance obtained by adding 2 moles of propylene oxide to the molar adduct and a substance obtained by adding 5 moles of ethylene oxide to the 2 mole adduct of propylene oxide of undecylamide, add a 10 mole adduct of ethylene oxide to 6-ethylnaphthol and undecylamide. 2 mole adduct of propylene oxide is used. Others are the same as in Example 11. Example 12 Divalent tin (used as stannous 2-hydroxypropanesulfonic acid) 12g/lead (used as lead 2-hydroxypropanesulfonate) 8g/free 2-hydroxypropanesulfonic acid
200g/ 6 moles of propylene oxide added to GAFAC-RS710* (manufactured by Toho Chemical Industry Co., Ltd.) 5g/ 1-(3-hydroxybutene-1)benzotriazole 0.2g/ Temperature 20 (℃) Current density range 1 to 15A /dm ² * Ethylene oxide is added to phosphoric acid diester. Comparative Example 12 GAFAC-RS710 was used instead of a substance obtained by adding 6 moles of propylene oxide to GAFAC-RS710 (manufactured by Toho Chemical Industry Co., Ltd.). The rest is the same as Example 12. About tin plating

[Table] ◎: Excellent ○: Good △: Fair ×: Poor Foaming test Pour 40ml of the plating solution into a 100ml graduated cylinder with a stopper, shake vigorously for 5 seconds, and measure the foaming height after 10 minutes. . About lead plating

【table】 About soldering

【table】

Claims (1)

[Claims] 1. A main plating bath containing alkanesulfonic acid or alkanolsulfonic acid and their divalent tin salt or divalent lead salt, or both tin salt and lead salt,
The following general formula () (Here, A is a residue of a C _8-22 higher alcohol,
Residues of C _1-25 alkyl phenols, residues of C _1-25 alkyl β-naphthol, residues of C _3-22 fatty acid amides, residues of _{C 1-25 alkoxylated} phosphoric acids, C ₈
~Represents the residue of sorbitan esterified with _C22 higher fatty acid or the residue of styrenated phenol (the hydrogen of the phenol nucleus may be substituted with _C1-4 alkyl or phenyl group), R′ and R″ represents a hydrogen atom or a methyl group,
However, when R′ represents a hydrogen atom, R″ represents a methyl group, and when R′ represents a methyl group,
R'' represents a hydrogen atom, m represents an integer of 1 to 30, and n represents an integer of 1 to 30), and further one type of smoothing additive is added. Tin, lead or tin-lead alloy plating bath made by adding the above. 2 Concentration of nonionic surfactant is 0.01 to 50 g/
The plating bath according to claim 1. 3. The plating bath according to claim 1, wherein the concentration of the smoothing additive is 0.01 to 30 g/. 4. The plating bath according to claim 1, wherein the total concentration of the tin salt and/or lead salt of alkanesulfonic acid or alkanolsulfonic acid is 0.5 to 200 g/metal. 5. The plating bath according to claim 1, wherein the concentration of free alkanesulfonic acid or alkanolsulfonic acid is at least stoichiometrically equivalent to divalent tin and/or lead ions.