JP4901039B2 - Replacement bismuth plating bath - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides a substituted bismuth plating bath that is excellent in high temperature aging stability of the bath and can provide a bismuth film having a good appearance.
[0002]
[Prior art]
Examples of conventional techniques for bismuth plating baths that do not use an external power source include the following.
[0003]
(1) JP-A-5-214549 (Prior Art 1)
An electroless bismuth plating bath containing a soluble bismuth salt, a soluble stannous salt as a reducing agent, and ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA) or citrate as a complexing agent is disclosed. ing.
However, for citrate, plating unevenness is likely to occur when the concentration is 0.20 mol or less, and conversely, when it is 0.5 mol or more, there is an indication of bath decomposition, and a fine bismuth powder is formed. Secondly, with NTA, a film is deposited from a concentration of 0.03 mol, and the deposition rate increases with an increase in the amount added. Thirdly, it is described that precipitation is difficult, and thirdly, regarding EDTA, if the addition amount is small, the decomposition of the bath is severe, and conversely, if the addition amount is large, the precipitation reaction stops and there is little room for application. (See paragraphs 20 to 22 of the publication).
[0004]
(2) JP 7-258861 A (Prior Art 2)
An electroless bismuth plating bath containing a soluble bismuth salt, a soluble stannous salt as a reducing agent, EDTA, NTA or citrate as a complexing agent, and carbonate as a pH adjuster is disclosed. Yes.
[0005]
[Problems to be solved by the invention]
The electroless baths of the prior arts 1 and 2 are basically reduced types (that is, autocatalysts) in which electrons are supplied from a specific reducing agent to a bismuth salt to precipitate metal bismuth from bismuth ions in the bath. Type) plating bath.
On the other hand, when considering a case where copper or a copper alloy, which is a general base material for electronic parts, is an object to be plated, even if these copper base materials are immersed in a solution containing a soluble bismuth salt, the redox potential of bismuth is Since it is baser than copper, the substitution reaction between bismuth and copper does not occur as it is, and it is difficult to deposit bismuth on the copper base material.
[0006]
Thus, as can be seen from the fact that the electroless plating baths of the prior arts 1 and 2 are autocatalytic and not substitutional, a mechanism for receiving electrons between the object to be plated and the bismuth salt in the bath. This substitution bismuth plating bath can be inferred from the difficulty of the autocatalytic plating bath having a different basic principle, and it is not easy to develop a practical substitution bismuth plating bath.
For example, when the bismuth salt in the bath is to be stabilized with a complexing agent, as is clear from the description of the prior art, the precipitation rate is slowed down if the complexing with the bismuth salt is strong, and the weak complexing force The deposition of bismuth cannot be controlled and a practical film cannot be obtained.
In particular, in actual substitution bismuth plating, from the standpoint of improving productivity by maintaining a high deposition rate, it is generally performed at a high temperature of about 50 ° C. or higher, so the deposition rate of the bismuth salt is controlled. It is even more difficult to obtain a practical plating film.
It is a technical object of the present invention to develop a substitution-type bismuth plating bath that can provide a stable coating that is stable and does not decompose for a long period of time.
[0007]
[Means for Solving the Problems]
The applicant previously disclosed in JP-A-2000-87252 (A) a soluble stannous salt and a soluble bismuth salt, (B) an organic acid or an inorganic acid as a bath base, and (C) an amine series. Disclosed is an electroless tin-bismuth alloy plating bath containing a complexing agent comprising a mixture of a compound and a thiourea, and the amine compound (C) includes ethylenediaminetetraacetic acid, nitrilotriacetic acid, ethylenediamine, Examples include diethylenetriamine, diethanolamine, ethylenediaminetetramethylene phosphate, and benzylamine.
[0008]
As a result of intensive research on various amine compounds used in this bath, the inventors of the present invention, as a starting point, based on the above-described electroless tin-bismuth alloy plating bath technique, showed that aminocarboxylic acids and thioureas When the mixture is applied as a complexing agent to a substituted bismuth plating bath, it greatly contributes to the stabilization of bismuth in the bath and the promotion of the substitution reaction between the object to be plated (for example, the copper base material) and bismuth, When the aminocarboxylic acid is a polyvalent aminocarboxylic acid having 5 or more carboxyl groups in the molecule, or a hydroxyl group-containing aminocarboxylic acid having a hydroxyl group in the molecule, specifically, diethylenetriaminepentaacetic acid, triethylene Tetramine hexaacetic acid, hydroxyethylethylenediamine triacetic acid, etc. can be expected to further contribute to the stabilization and promotion of the substitution reaction The found, and have completed the present invention.
[0009]
That is, the present invention 1 includes (A) a soluble bismuth salt,
(B) Organic sulfonic acid, aliphatic carboxylic acid More selected Organic acids, borohydrofluoric acid, silicohydrofluoric acid, sulfamic acid , Selected from hydrochloric acid, sulfuric acid, perchloric acid At least one kind of inorganic acid,
(C) Complexing agent comprising a mixture of aminocarboxylic acids and thioureas
It is a substituted bismuth plating bath characterized by containing.
[0010]
Invention 2 is the invention 1, wherein the aminocarboxylic acid of (C) is ethylenediaminetetraacetic acid, ethylenediaminetetraacetic acid disodium salt, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, ethylenediaminetetrapropion Acid, nitrilotriacetic acid, iminodiacetic acid, iminodipropionic acid, metaphenylenediaminetetraacetic acid, 1,2-diaminocyclohexane-N, N, N ', N'-tetraacetic acid, diaminopropionic acid, glutamic acid, ornithine, cysteine, N, N-bis (2-hydroxyethyl) glycine More selected compounds It is a substituted bismuth plating bath characterized by being at least one of the following.
[0011]
The invention 3 is the invention 2, wherein the aminocarboxylic acid (C) is a polyvalent aminocarboxylic acid having 5 or more carboxyl groups in the molecule, or a hydroxyl group-containing aminocarboxylic acid having a hydroxyl group in the molecule. It is a substituted bismuth plating bath characterized by being an acid.
[0012]
Invention 4 is a substituted bismuth plating according to Invention 3, wherein the polyvalent aminocarboxylic acids are diethylenetriaminepentaacetic acid and triethylenetetraminehexaacetic acid, and the hydroxyl group-containing aminocarboxylic acids are hydroxyethylethylenediaminetriacetic acid. It is a bath.
[0013]
The present invention 5 is a group consisting of the non-ionic surfactant, the cationic surfactant, the anionic surfactant and the amphoteric surfactant in the displacement plating bath described in any one of the present inventions 1 to 4. It is a substituted bismuth plating bath characterized by containing at least one surfactant selected from
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is a substituted bismuth plating bath using a mixture of aminocarboxylic acids and thioureas as a complexing agent. Therefore, basically any reducing agent such as titanium halides, phosphate compounds, amine boranes, borohydride compounds, ascorbic acids, hydrazines and the like is not required.
The above thioureas refer to thiourea and thiourea derivatives.
The thiourea derivative basically refers to a compound in which various substituents are bonded to one or more of the nitrogen atom or sulfur atom of thiourea and the molecular volume is larger than that of thiourea. , 3-dimethylthiourea, trimethylthiourea, diethylthiourea (eg, 1,3-diethyl-2-thiourea), N, N'-diisopropylthiourea, allylthiourea, acetylthiourea, ethylenethiourea, 1,3-diphenyl Examples include thiourea, thiourea dioxide, and thiosemicarbazide.
[0015]
As the aminocarboxylic acids, as shown in the present invention 2, ethylenediaminetetraacetic acid (EDTA), ethylenediaminetetraacetic acid disodium salt (EDTA.2Na), hydroxyethylethylenediaminetriacetic acid (HEDTA), diethylenetriaminepentaacetic acid (DTPA), Triethylenetetramine hexaacetic acid (TTHA), ethylenediaminetetrapropionic acid, nitrilotriacetic acid (NTA), iminodiacetic acid (IDA), iminodipropionic acid (IDP), metaphenylenediaminetetraacetic acid, 1,2-diaminocyclohexane-N, N, N ′, N′-tetraacetic acid, diaminopropionic acid, glutamic acid, ornithine, cysteine, N, N-bis (2-hydroxyethyl) glycine and the like can be mentioned.
Among the aminocarboxylic acids, as shown in the present invention 3, polyvalent aminocarboxylic acids having 5 or more carboxyl groups in the molecule, or hydroxyl group-containing aminocarboxylic acids having a hydroxyl group in the molecule are preferable. Specifically, examples of the polyvalent aminocarboxylic acids include diethylenetriaminepentaacetic acid and triethylenetetraminehexaacetic acid, and examples of the hydroxyl group-containing aminocarboxylic acids include hydroxyethylethylenediaminetriacetic acid (see the present invention 4).
By the way, polyamines such as ethylenediamine and diethylenetriamine used in the electroless tin-bismuth alloy plating bath, amino alcohols such as diethanolamine and the like are common to the aminocarboxylic acids of the present invention in that they belong to amine compounds. Of course, it is excluded from the aminocarboxylic acids.
[0016]
The aminocarboxylic acids and thioureas can be used alone or in combination. The combination of aminocarboxylic acids and thioureas may be arbitrary, for example, DTPA and thiourea, DTPA and 1,3-dimethylthiourea, TTHA and thiourea, TTHA and 1,3-dimethylthiourea, TTHA and diethylthiourea, HEDTA and thiourea, HEDTA and methylthiourea, DTPA and TTHA and thiourea, DTPA and HEDTA and thiourea, TTHA and HEDTA and thiourea, thiourea derivatives such as DTPA, thiourea and ethylenethiourea, TTHA and thiourea and thio Urea derivatives, HEDTA and thiourea and thiourea derivatives, ethylenediaminetetrapropionic acid and thiourea, IDA and thiourea, 1,2-diaminocyclohexane-N, N, N ', N'-tetraacetic acid Thiourea, etc. Is preferred.
The addition amount of the complexing agent comprising a mixture of the aminocarboxylic acids and thioureas is 5-300 g / L in total, preferably 50-200 g / L.
[0017]
The soluble bismuth salt is not limited, and Bi in the bath ³⁺ Any salt can be used as long as it is a soluble salt that forms bismuth methanesulfonate, bismuth ethanesulfonate, p-phenol, and the like. Examples thereof include bismuth sulfonate, bismuth nitrate, and bismuth chloride.
The converted addition amount of the soluble bismuth salt as a metal salt is 0.1 to 200 g / L, preferably 1 to 80 g / L.
[0018]
Various acids or salts thereof can be used as the base of the substituted bismuth plating bath of the present invention. Specific examples of the acid include organic compounds such as alkane sulfonic acid, alkanol sulfonic acid, and aromatic sulfonic acid that are relatively easy to treat waste water. A sulfonic acid or an organic acid such as an aliphatic carboxylic acid is preferred, but an inorganic acid such as borohydrofluoric acid, silicohydrofluoric acid, sulfamic acid, hydrochloric acid, sulfuric acid or perchloric acid may be used.
The acid or salt thereof can be used alone or in combination, and the addition amount is 0.1 to 300 g / L, preferably 20 to 150 g / L.
[0019]
The alkanesulfonic acid has the chemical formula C _n H _{2n + 1} SO _Three Those represented by H (for example, n = 1 to 5, preferably 1 to 3) can be used. Specifically, methanesulfonic acid, ethanesulfonic acid, 1-propanesulfonic acid, 2-propanesulfonic acid, 1 -In addition to butanesulfonic acid, 2-butanesulfonic acid, pentanesulfonic acid, etc., hexanesulfonic acid, decanesulfonic acid, dodecanesulfonic acid, etc. may be mentioned
.
[0020]
The alkanol sulfonic acid has the chemical formula
C _m H _{2m + 1} -CH (OH) -C _p H _2p -SO _Three H (for example, m = 0 to 6, p = 1 to 5)
In particular, 2-hydroxyethane-1-sulfonic acid, 2-hydroxypropane-1-sulfonic acid, 2-hydroxybutane-1-sulfonic acid, 2-hydroxypentane-1- In addition to sulfonic acid, etc. 1-hydroxypropane-2-sulfonic acid, 3-hydroxypropane-1-sulfonic acid, 4-hydroxybutane-1-sulfonic acid, 2-hydroxyhexane-1-sulfonic acid, 2-hydroxydecane -1-sulfonic acid, 2-hydroxydodecane-1-sulfonic acid and the like.
[0021]
The aromatic sulfonic acid is basically benzene sulfonic acid, alkyl benzene sulfonic acid, phenol sulfonic acid, naphthalene sulfonic acid, alkyl naphthalene sulfonic acid, etc., specifically 1-naphthalene sulfonic acid, 2-naphthalene. Examples include sulfonic acid, toluenesulfonic acid, xylenesulfonic acid, p-phenolsulfonic acid, cresolsulfonic acid, sulfosalicylic acid, nitrobenzenesulfonic acid, sulfobenzoic acid, diphenylamine-4-sulfonic acid, and the like.
[0022]
Generally as said aliphatic carboxylic acid, a C1-C6 carboxylic acid can be used. Specific examples include acetic acid, propionic acid, butyric acid, citric acid, tartaric acid, gluconic acid, sulfosuccinic acid, and trifluoroacetic acid.
[0023]
In addition to the above-mentioned components, the substituted bismuth plating bath of the present invention includes known surfactants, pH adjusters, smoothing agents, brighteners, semi-brighteners, stabilizing auxiliary complexing agents, and hiding complexing agents. Of course, additives commonly used in plating baths and the like can be mixed.
[0024]
The surfactant is contained for the purpose of assisting improvement of the denseness, smoothness, adhesion, etc. of the deposited bismuth film, and is a nonionic surfactant, an amphoteric surfactant, a cationic surfactant, or an anion. A system surfactant can be used alone or in combination.
The addition amount is 0.01 to 100 g / L, preferably 0.1 to 50 g / L.
[0025]
Specific examples of the nonionic surfactant include C ₁ ~ C ₂₀ Alkanol, phenol, naphthol, bisphenols, C ₁ ~ C _{twenty five} Alkylphenol, arylalkylphenol, C ₁ ~ C _{twenty five} Alkyl naphthol, C ₁ ~ C _{twenty five} Alkoxylated phosphoric acid (salt), sorbitan ester, polyalkylene glycol, C ₁ ~ C _{twenty two} Aliphatic amine, C ₁ ~ C _{twenty two} An aliphatic amide or the like obtained by addition condensation of 2-300 mol of ethylene oxide (EO) and / or propylene oxide (PO), C ₁ ~ C _{twenty five} Examples thereof include alkoxylated phosphoric acid (salt).
[0026]
C for addition condensation of the above ethylene oxide (EO) and / or propylene oxide (PO) ₁ ~ C ₂₀ Examples of the alkanol include methanol, ethanol, n-butanol, t-butanol, n-hexanol, octanol, decanol, lauryl alcohol, tetradecanol, hexadecanol, stearyl alcohol, eicosanol, oleyl alcohol, docosanol and the like.
Similarly, examples of the bisphenols include bisphenol A, bisphenol B, and bisphenol F.
C above ₁ ~ C _{twenty five} Alkylphenols include mono-, di- or trialkyl-substituted phenols such as p-methylphenol, p-butylphenol, p-isooctylphenol, p-nonylphenol, p-hexylphenol, 2,4-dibutylphenol, 2,4, Examples include 6-tributylphenol, dinonylphenol, p-dodecylphenol, p-laurylphenol, and p-stearylphenol.
Examples of the arylalkylphenol include 2-phenylisopropylphenol, cumylphenol, (mono, di or tri) styrenated phenol, (mono, di or tri) benzylphenol and the like.
C above ₁ ~ C _{twenty five} Examples of the alkyl group of the alkyl naphthol include methyl, ethyl, propyl, butyl, hexyl, octyl, decyl, dodecyl, octadecyl and the like, which may be at any position of the naphthalene nucleus.
Examples of the polyalkylene glycol include polyoxyethylene glycol, polyoxypropylene glycol, and polyoxyethylene polyoxypropylene copolymer.
[0027]
C above ₁ ~ C _{twenty five} The alkoxylated phosphoric acid (salt) is represented by the following general formula (a).
R _a ・ R _b ・ (MO) P = O (a)
(In formula (a), R _a And R _b Are the same or different C ₁ ~ C _{twenty five} Alkyl, one of which may be H. M represents H or an alkali metal. )
[0028]
Examples of the sorbitan ester include mono-, di- or triesterized 1,4-, 1,5- or 3,6-sorbitan such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan distearate, sorbitan dioleate And sorbitan mixed fatty acid ester.
C above ₁ ~ C _{twenty two} Examples of the aliphatic amine include saturated and unsaturated fatty acid amines such as propylamine, butylamine, hexylamine, octylamine, decylamine, laurylamine, myristylamine, stearylamine, oleylamine, beef tallow amine, ethylenediamine, and propylenediamine.
C above ₁ ~ C _{twenty two} Examples of the aliphatic amide include amides such as propionic acid, butyric acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, behenic acid, coconut oil fatty acid, and beef tallow fatty acid.
[0029]
Furthermore, as the nonionic surfactant,
R ₁ N (R ₂ ) ₂ → O
(In the above formula, R ₁ Is C _Five ~ C _{twenty five} Alkyl or RCONHR _Three (R _Three Is C ₁ ~ C _Five Alkylene)), R ₂ Are the same or different C ₁ ~ C _Five Indicates alkyl. )
The amine oxide shown by these etc. can be used.
[0030]
As the cationic surfactant, a quaternary ammonium salt represented by the following general formula (b)
(R ₁ ・ R ₂ ・ R _Three ・ R _Four N) ⁺ X ^- ... (b)
(In the formula (b), X is halogen, hydroxy, C ₁ ~ C _Five Alkanesulfonic acid or sulfuric acid, R ₁ , R ₂ , R _Three And R _Four Are the same or different C ₁ ~ C ₂₀ Indicates alkyl, aryl or benzyl. )
Or the pyridinium salt etc. which are represented with the following general formula (c) are mentioned.
R ₆ -(C _Five H _Five N-R _Five ) ⁺ ・ X ^- ... (c)
(In formula (c), C _Five H _Five N is pyridine ring, X is halogen, hydroxy, C ₁ ~ C _Five Alkanesulfonic acid or sulfuric acid, R _Five Is C ₁ ~ C ₂₀ Alkyl, R ₆ Is H or C ₁ ~ C _Ten Indicates alkyl. )
[0031]
Examples of cationic surfactants in the form of salts include lauryl trimethyl ammonium salt, stearyl trimethyl ammonium salt, lauryl dimethyl ethyl ammonium salt, octadecyl dimethyl ethyl ammonium salt, dimethyl benzyl lauryl ammonium salt, cetyl dimethyl benzyl ammonium salt, octadecyl dimethyl Benzylammonium salt, trimethylbenzylammonium salt, triethylbenzylammonium salt, dimethyldiphenylammonium salt, benzyldimethylphenylammonium salt, hexadecylpyridinium salt, laurylpyridinium salt, dodecylpyridinium salt, stearylamine acetate, laurylamine acetate, octadecylamine acetate, etc. Is mentioned.
[0032]
Examples of the anionic surfactant include alkyl sulfates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl phenyl ether sulfates, alkyl benzene sulfonates, {(mono, di, tri) alkyl} naphthalene sulfonates, etc. Is mentioned. Examples of the alkyl sulfate include sodium lauryl sulfate and sodium oleyl sulfate. Examples of the polyoxyethylene alkyl ether sulfate include sodium polyoxyethylene (EO5) nonyl ether sulfate and sodium polyoxyethylene (EO15) dodecyl ether sulfate. Examples of the polyoxyethylene alkylphenyl ether sulfate include polyoxyethylene (EO15) nonylphenyl ether sulfate. Examples of the alkyl benzene sulfonate include sodium dodecylbenzene sulfonate. Examples of the {(mono, di, tri) alkyl} naphthalene sulfonate include naphthalene sulfonate, sodium dibutyl naphthalene sulfonate, and naphthalene sulfonate formalin condensate.
[0033]
Examples of the amphoteric surfactant include carboxybetaine, imidazoline betaine, sulfobetaine, and aminocarboxylic acid. Further, sulfation of a condensation product of ethylene oxide and / or propylene oxide and an alkylamine or diamine, or a sulfonated adduct can also be used.
[0034]
Representative carboxybetaines or imidazoline betaines are lauryldimethylaminoacetic acid betaine, myristyldimethylaminoacetic acid betaine, stearyldimethylaminoacetic acid betaine, coconut oil fatty acid amidopropyldimethylaminoacetic acid betaine, 2-undecyl-1-carboxymethyl-1 -Hydroxyethyl imidazolinium betaine, 2-octyl-1-carboxymethyl-1-carboxyethyl imidazolinium betaine, and the like. Sulfated and sulfonated adducts include sulfated adducts of ethoxylated alkylamines, sulfonated Examples thereof include lauric acid derivative sodium salt.
[0035]
Examples of the sulfobetaines include coconut oil fatty acid amidopropyldimethylammonium-2-hydroxypropanesulfonic acid, N-cocoylmethyl taurine sodium, and N-palmitoylmethyl taurine sodium.
Examples of the aminocarboxylic acid include dioctylaminoethylglycine, N-laurylaminopropionic acid, octyldi (aminoethyl) glycine sodium salt, and the like.
[0036]
As conditions for plating in the substituted bismuth bath, the bath temperature is 45 to 90 ° C., and 50 to 70 ° C. is preferable from the viewpoint of increasing the deposition rate.
The plating film obtained from the substituted bismuth bath is effective for applications such as surface treatment of electronic parts such as printed circuit boards and film carriers.
[0037]
[Action]
The case where bismuth plating is performed on an object to be plated with copper or a copper alloy as a base will be described as a representative example. When the object to be plated is immersed in a substituted bismuth bath, the copper as the base dissolves into the bath and emits electrons. The basic principle is that the bismuth ions inside receive these electrons and precipitate as metallic bismuth.
In this case, the substituted bismuth plating bath of the present invention is characterized in that aminocarboxylic acids and thioureas are used in combination as a complexing agent, but these aminocarboxylic acids are complexed with the bismuth salt in the bath to convert bismuth ions. Since it can be estimated that the concentration of aminocarboxylic acids increases, the precipitation rate of bismuth decreases, and when the concentration decreases, the rate increases, so aminocarboxylic acids are greatly related to the control of the film thickness of the resulting bismuth film.
On the other hand, the oxidation-reduction potential of bismuth is lower than that of copper, but the thioureas are complexed with copper as a base material, so that the oxidation-reduction potential of copper is shifted in the direction of the base. It can be estimated that the reaction is accelerated. Therefore, since the rate of the substitution reaction can be controlled by adjusting the concentration of thioureas, thioureas still affect the film thickness of the bismuth film, and the film-forming effects such as the denseness and smoothness of the bismuth film, Or it affects the adhesion and contributes to the improvement of the film appearance. The thioureas also have a function of concealing copper ions eluted in the bath by a substitution reaction and stabilizing the bath.
[0038]
【Effect of the invention】
Since a mixture of aminocarboxylic acids and thioureas is used as a complexing agent, the bath does not decompose, turbidity or precipitation occurs, the bath can be stabilized for a long time even at high temperatures, and the color tone is uniform. Plating film with excellent properties, gloss, adhesion, etc. is obtained, and the film appearance is also excellent.
In particular, when the aminocarboxylic acid is diethylenetriaminepentaacetic acid or triethylenetetraminehexaacetic acid having 5 or more carboxyl groups in the molecule, or hydroxyethylethylenediaminetriacetic acid having a hydroxyl group in the molecule, the temperature of the bath is high. The stability over time and the appearance of the film are further improved, and in particular, the uniformity and gloss of the film are improved.
In addition, as shown in the test examples described later, the substituted bismuth bath of the present invention has stability over time at a high temperature of about 65 ° C., and therefore, when performing a continuous heating operation at a high temperature for a long time from the viewpoint of productivity. Can be applied to the market, and plating baths that have cleared practical standards can be provided to the market.
On the other hand, in the present invention 5, since various surfactants are added to the bismuth plating bath, further improvement of the appearance of the bismuth film can be expected, and the denseness and smoothness of the film are improved.
[0039]
【Example】
Hereinafter, examples of the substituted bismuth plating bath will be described sequentially, and various test examples of the high temperature aging stability of the plating bath of each example and the appearance of the coating obtained from each plating bath will be described.
It should be noted that the present invention is not limited to the following embodiments, and can of course be modified arbitrarily within the scope of the technical idea of the present invention.
[0040]
Of the following Examples 1 to 12, Example 1 is an example of using DTPA and thiourea, Example 2 is an example of using HEDTA and a thiourea derivative, Example 3 is an example of using TTHA and a thiourea derivative, Example Example 4 uses TTHA and thiourea derivatives, Example 5 uses DTPA, thiourea and thiourea derivatives, Example 6 uses TTHA and thiourea derivatives, Example 7 uses DTPA and thiourea derivatives Examples, Example 8 uses HEDTA and thiourea, Example 9 uses ethylenediaminetetrapropionic acid and thiourea, Example 10 uses 1,2-diaminocyclohexane-N, N, N ', N'- Example of use of tetraacetic acid and thiourea, Example 11 is an example of use of IDA, thiourea and thiourea derivatives, and Example 12 is an example of use of DTPA, TTHA and thiourea.
On the other hand, among Comparative Examples 1 to 5, Comparative Example 1 is a blank example that does not contain both aminocarboxylic acids and thioureas, and Comparative Example 2 contains only aminocarboxylic acids and is a blank example that does not contain thioureas. Example 3 is an example containing sodium citrate and EDTA as complexing agents for bismuth salt and soluble stannous salt as reducing agent, respectively, and Comparative Example 4 is based on thioureas only in accordance with the prior art 1 described above. In Comparative Example 5, a blank example containing no aminocarboxylic acids and Comparative Example 5 is an example in which ethylenediamine which is common to amine compounds is used instead of aminocarboxylic acids, and thiourea is used in combination.
[0041]
Example 1
A substituted bismuth plating bath was constructed with the following composition.
-Bismuth methanesulfonate (Bi ³⁺ As): 5g / L
・ Methanesulfonic acid: 70 g / L
・ Thiourea: 100 g / L
・ Diethylenetriaminepentaacetic acid (DTPA): 50 g / L
-Octylphenol polyethoxylate (EO 10 mol): 8 g / L
[0042]
Example 2
A substituted bismuth plating bath was constructed with the following composition.
・ 2-hydroxypropane
-1-Bismuth sulfonate (Bi ³⁺ As): 7g / L
2-hydroxypropane-1-sulfonic acid: 100 g / L
・ Methylthiourea: 105 g / L
・ Hydroxyethylethylenediaminetriacetic acid (HEDTA): 55 g / L
[0043]
Example 3
A substituted bismuth plating bath was constructed with the following composition.
-Bismuth ethanesulfonate (Bi ³⁺ As): 1g / L
・ 2-Butanesulfonic acid: 80 g / L
・ 1,3-Dimethylthiourea: 80 g / L
・ Triethylenetetramine hexaacetic acid (TTHA): 80 g / L
・ Nonylphenol polyethoxylate (EO15 mol): 5g / L
[0044]
Example 4
A substituted bismuth plating bath was constructed with the following composition.
-Bismuth p-phenolsulfonate (Bi ³⁺ As): 8g / L
・ Ethanesulfonic acid: 30 g / L
・ Diethylthiourea: 45 g / L
・ Triethylenetetramine hexaacetic acid (TTHA): 30 g / L
・ N-lauryl-N, N-dimethyl
-N-carboxymethylbetaine: 3 g / L
[0045]
Example 5
A substituted bismuth plating bath was constructed with the following composition.
-Bismuth methanesulfonate (Bi ³⁺ As): 10g / L
・ 2-Hydroxypropane-1-sulfonic acid: 75 g / L
・ Thiourea: 80 g / L
・ Ethylenethiourea: 30 g / L
・ Diethylenetriaminepentaacetic acid (DTPA): 55 g / L
・ N-Myristyl-N, N
-Dimethyl-N-carboxymethylbetaine: 4 g / L
[0046]
Example 6
A substituted bismuth plating bath was constructed with the following composition.
-Bismuth ethanesulfonate (Bi ³⁺ As): 3g / L
-Ethanesulfonic acid: 65 g / L
・ Thiourea: 95g / L
・ Triethylenetetramine hexaacetic acid (TTHA): 55 g / L
・ Dibutyl-β-naphthol
-Polyethoxylate (EO15 mol): 6g / L
[0047]
Example 7
A substituted bismuth plating bath was constructed with the following composition.
-Bismuth methanesulfonate (Bi ³⁺ As): 5g / L
・ Methanesulfonic acid: 70 g / L
・ 1,3-Dimethylthiourea: 60 g / L
・ Diethylenetriaminepentaacetic acid (DTPA): 90 g / L
・ Lauryl alcohol polyethoxylate (EO15 mol): 7g / L
[0048]
Example 8
A substituted bismuth plating bath was constructed with the following composition.
-Bismuth p-phenolsulfonate (Bi ³⁺ As): 8g / L
・ P-phenolsulfonic acid: 95 g / L
・ Thiourea: 50 g / L
・ Hydroxyethylethylenediaminetriacetic acid (HEDTA): 30 g / L
・ N-myristyl-N, N
-Dimethyl-N-carboxymethylbetaine: 6 g / L
[0049]
Example 9
A substituted bismuth plating bath was constructed with the following composition.
・ Bismuth nitrate (Bi ³⁺ As): 5g / L
・ Methanesulfonic acid: 100 g / L
・ Thiourea: 100 g / L
・ Ethylenediaminetetrapropionic acid: 50 g / L
[0050]
Example 10
A substituted bismuth plating bath was constructed with the following composition.
・ Bismuth chloride (Bi ³⁺ As): 2g / L
・ Methanesulfonic acid: 70 g / L
・ Thiourea: 80 g / L
・ 1,2-Diaminocyclohexane
-N, N, N ', N'-tetraacetic acid: 20 g / L
[0051]
Example 11
A substituted bismuth plating bath was constructed with the following composition.
-Bismuth 2-butanesulfonate (Bi ³⁺ As): 3g / L
・ P-phenolsulfonic acid: 50 g / L
・ Thiourea: 65 g / L
・ Allylthiourea: 20 g / L
・ Iminodiacetic acid (IDA): 40 g / L
[0052]
Example 12
A substituted bismuth plating bath was constructed with the following composition.
-Bismuth p-phenolsulfonate (Bi ³⁺ As): 10g / L
・ Cresol sulfonic acid: 20 g / L
・ Thiourea: 90g / L
・ Diethylenetriaminepentaacetic acid (DTPA): 30 g / L
・ Triethylenetetramine hexaacetic acid (TTHA): 4 g / L
・ N-lauryl-N, N-dimethyl
-N-carboxymethylbetaine: 5 g / L
[0053]
<< Comparative Example 1 >>
A substituted bismuth plating bath was constructed with the following composition.
-Bismuth methanesulfonate (Bi ³⁺ As): 5g / L
・ Methanesulfonic acid: 50 g / L
[0054]
<< Comparative Example 2 >>
A substituted bismuth plating bath was constructed with the following composition.
-Bismuth methanesulfonate (Bi ³⁺ As): 5g / L
・ Methanesulfonic acid: 50 g / L
・ Nitrilotriacetic acid (NTA): 20 g / L
[0055]
<< Comparative Example 3 >>
A substituted bismuth plating bath was constructed with the following composition.
・ Bismuth trichloride (Bi ³⁺ As): 15g / L
・ Sodium citrate: 100 g / L
・ Ethylenediaminetetraacetic acid (EDTA): 30 g / L
: Stannous chloride (Sn ²⁺ As): 5g / L
[0056]
<< Comparative Example 4 >>
A substituted bismuth plating bath was constructed with the following composition.
-Bismuth methanesulfonate (Bi ³⁺ As): 8g / L
・ Methanesulfonic acid: 60 g / L
・ Thiourea: 70 g / L
[0057]
<< Comparative Example 5 >>
A substituted bismuth plating bath was constructed with the following composition.
-Bismuth methanesulfonate (Bi ³⁺ As): 10g / L
・ Methanesulfonic acid: 50 g / L
・ Thiourea: 50 g / L
・ Ethylenediamine: 30 g / L
[0058]
《Test example for high temperature aging stability of displacement plating bath》
Therefore, each substituted bismuth plating solution of Examples 1 to 12 and Comparative Examples 1 to 5 is accommodated in a 1 L beaker, and this is placed in a water bath set at a constant temperature of 65 ° C. and kept at a high temperature for 200 hours, The change of the plating solution after 200 hours under the heating condition was observed, and the degree of deterioration (decomposition) state of each plating solution was evaluated.
The evaluation criteria for the high temperature aging stability are as follows.
○: Turbidity and precipitation were not observed in the plating bath, the transparency of the bath was high, and there was no change from the bath state at the time of the initial construction bath.
X: Turbidity and precipitation occurred in the plating bath, and the bath was decomposed.
[0059]
The center column of FIG. 1 shows the test results.
In Examples 1 to 12 in which aminocarboxylic acids and thioureas were used as complexing agents, good bath stability was exhibited, and all were evaluated as good. In contrast, in Comparative Example 1 lacking both aminocarboxylic acids and thioureas, and in Comparative Example 4 containing only thioureas and lacking aminocarboxylic acids, the bath decomposes, and ethylenediamine and thiourea are complexed. The same result was obtained in Comparative Example 5 used for the agent. The bath stability of Comparative Example 2 containing only aminocarboxylic acids and lacking thioureas was good.
Therefore, it has been found that in a substituted bismuth bath, the addition of aminocarboxylic acids that have a complexing action to a bismuth salt greatly contributes to the stability of the bath. In addition, since the evaluation of Comparative Example 5 using ethylenediamine, which is common to amine compounds instead of aminocarboxylic acids, was poor, the aminocarboxylic acids were significantly selective in terms of stabilizing the substituted bismuth bath. The effectiveness became clear.
Comparative Example 3 is a reference example of Prior Art 1 and contains EDTA, which is an aminocarboxylic acid. On the other hand, since it contains a reducing agent, the system becomes thermodynamically unstable and stability is evaluated. The reduced bismuth bath is considered to have difficulty in maintaining bath stability.
[0060]
Therefore, each of the replacement plating baths of Examples 1 to 12 and Comparative Examples 1 to 5 was held at 50 ° C., and a TAB film carrier test piece patterned with VLP (a type of electrolytic copper foil) was immersed for 10 minutes. And substituted bismuth plating.
The appearance of each bismuth plating film obtained was visually observed, and the film thickness (μm) of the film was measured with an instrument.
[0061]
<Film thickness of bismuth plating film>
The right column of FIG. 1 shows each plating film thickness.
According to the figure, in Examples 1-12, it turns out that the bismuth film | membrane of various film thickness is obtained. As described mainly in the above item of action, the film thickness of the bismuth film is basically related to the deposition rate, and the deposition rate is the complexing strength to bismuth salt corresponding to the concentration of aminocarboxylic acids, and thioureas. As shown in Examples 1 to 12, the bismuth film can be formed into a desired film thickness by changing the concentration of aminocarboxylic acids and thioureas. Can be controlled. For example, in Example 6, the bismuth film deposited is relatively thick by increasing the thiourea content relative to the bismuth salt and controlling the TTHA content. On the contrary, in Example 4, the content of the thiourea derivative relative to the bismuth salt is moderately suppressed, and the deposited bismuth film thickness is relatively thin due to the suppression of the TTHA content.
On the other hand, in Comparative Example 1 lacking aminocarboxylic acids and thioureas, the bath was decomposed, so that a bismuth film was not formed, and in Comparative Example 2 lacking thioureas responsible for the substitution reaction between the copper base and bismuth. Was stable, but no film was deposited.
[0062]
<< Example of appearance evaluation test of bismuth plating film >>
The appearance of the bismuth plating film was evaluated based on the following criteria.
○: It had a uniform gloss.
Δ: Spots and unevenness such as brown and brown were observed.
X: Swelling and peeling were observed, and adhesion was poor.
[0063]
The left column of FIG. 1 shows the result.
Although Examples 1-12 were evaluation of (circle)-(triangle | delta), all of Comparative Examples 3-5 were evaluation of x. In Comparative Examples 1 and 2, as described above, no bismuth film was deposited, and evaluation was impossible.
That is, in Comparative Examples 3 to 5, the bismuth film obtained also had poor adhesion, and the quality was naturally far from the practical level, as can be judged from the poor stability of the plating bath. This revealed the importance of using aminocarboxylic acids and thioureas in combination with complexing agents for improving the film appearance.
[0064]
On the other hand, looking at Examples 1-12, Examples 1, 3-7, 12, or DTPA and TTHA, which are polyvalent aminocarboxylic acids having 5 or more carboxyl groups in the molecule, are used alone or in combination. In Examples 2 and 8 using HEDTA, which is a hydroxyl group-containing aminocarboxylic acid having a hydroxyl group in the molecule, a film with excellent color uniformity and glossiness was obtained, and the film appearance was evaluated as ◯. In Examples 9 to 11 using aminocarboxylic acids other than these, uneven color tone and spots were observed on the film.
Therefore, it has been clarified that the polyvalent aminocarboxylic acids or the hydroxyl group-containing aminocarboxylic acids have a significant advantage over the other aminocarboxylic acids in terms of ensuring a high level of film appearance. As described above, the applicant of the present invention disclosed various aminocarboxylic acids, polyamines, amino alcohols and the like as amine compounds effective as complexing agents in the electroless tin-bismuth alloy plating bath disclosed above. As the complexing agent applied to the substituted bismuth plating bath, aminocarboxylic acids are preferable among the amine compounds, and among them, the above polyvalent aminocarboxylic acids and hydroxyl group-containing aminocarboxylic acids are particularly preferable. (That is, the selective effectiveness among aminocarboxylic acids) was confirmed by this test example.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a chart showing the test results of high temperature aging stability of each substituted bismuth plating bath of Examples 1 to 12 and Comparative Examples 1 to 5, and the appearance and film thickness of the bismuth film obtained from each plating bath.

Claims (5)

(A) a soluble bismuth salt,
(B) at least one inorganic acid selected from organic sulfonic acids, organic acids selected from aliphatic carboxylic acids, borohydrofluoric acid, silicofluoric acid, sulfamic acid , hydrochloric acid, sulfuric acid, perchloric acid ,
(C) A substituted bismuth plating bath comprising a complexing agent comprising a mixture of aminocarboxylic acids and thioureas. (C) aminocarboxylic acids are ethylenediaminetetraacetic acid, ethylenediaminetetraacetic acid disodium salt, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, ethylenediaminetetrapropionic acid, nitrilotriacetic acid, iminodiacetic acid, iminodia Propionic acid, metaphenylenediaminetetraacetic acid, 1,2-diaminocyclohexane-N, N, N ', N'-tetraacetic acid, diaminopropionic acid, glutamic acid, ornithine, cysteine, N, N-bis (2-hydroxyethyl) The substituted bismuth plating bath according to claim 1, which is at least one compound selected from glycine. 3. The aminocarboxylic acid (C) is a polyvalent aminocarboxylic acid having 5 or more carboxyl groups in the molecule or a hydroxyl group-containing aminocarboxylic acid having a hydroxyl group in the molecule. The substituted bismuth plating bath described in 1. The substituted bismuth plating bath according to claim 3, wherein the polyvalent aminocarboxylic acids are diethylenetriaminepentaacetic acid and triethylenetetraminehexaacetic acid, and the hydroxyl group-containing aminocarboxylic acids are hydroxyethylethylenediaminetriacetic acid. 5. At least one selected from the group consisting of a nonionic surfactant, a cationic surfactant, an anionic surfactant, and an amphoteric surfactant in the displacement plating bath according to claim 1. A substituted bismuth plating bath characterized by containing a surfactant.

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