JP7068424B2 - Acidic water-based two-component silver-bismuth alloy electroplating composition and method - Google Patents

Description

An object of the present invention is an acidic aqueous two-component silver-bismuth alloy electroplating composition and method. More specifically, the present invention aims at an acidic aqueous two-component silver-bismas alloy electroplating composition and a method, wherein the acidic aqueous two-component silver-bismas alloy electroplating composition has low electrical contact resistance and. Contains a 5-membered aromatic heterocyclic nitrogen compound with a thiol functional group that allows electroplating of silver-rich two-component silver-bismas alloys with good wear resistance.

Silver and silver alloy plating baths are highly desirable for plating silver and silver alloys on substrates in applications intended for the manufacture of electronic components and jewelery. Due to its excellent electrical properties, especially its low electrical contact resistance, substantially pure silver is used as the contact finishing material. However, its poor resistance to mechanical wear and its high silver-silver coefficient of friction limit its use, for example as a contact finishing material for electrical connectors. As a result of poor resistance to mechanical wear, connectors are physically damaged after a relatively small number of connector insert-deinsert cycles. The high coefficient of friction contributes to this wear problem. If the connector has a high coefficient of friction, the force required to insert and remove the connector will be very high, which may damage the connector or limit connector design options. Plating of silver alloys such as silver-antimony and silver-tin provides improved wear resistance, but has unacceptably poor contact resistance, especially after prolonged exposure to high temperatures.

The plating industry is practical because many silver salts are substantially water-insoluble and water-soluble silver salts often form insoluble salts with various compounds commonly present in the plating bath. It faces many challenges of blending silver or silver alloy plating baths that are stable for long enough periods in various plating applications and at least address the aforementioned problems. Many silver and silver alloy plating baths contain cyanide to achieve practical applications. However, cyanide is extremely toxic. Therefore, special wastewater treatment is required. As a result, the processing cost increases. Moreover, since these baths can only be used in the alkaline range, most metals are not soluble in an alkaline environment, limiting the types of alloyed metals. Further, exposure of the substrate to an alkaline bath can result in passivation of the substrate surface, making the surface difficult to plate.

Therefore, there is a need for silver alloy plating baths that are stable, acidic, have low electrical contact resistance, and provide improved wear resistance resulting in plating with a low coefficient of friction.

式中、Ｑ_１～Ｑ_４は置換若しくは非置換窒素、又は置換若しくは非置換炭素であり得るが、但し、Ｑ_１～Ｑ_４のうち少なくとも２つは窒素であり、置換基としては、水素、（Ｃ_１～Ｃ_４）アルキル、アミノ基、アミノアルキル基、カルボキシル、カルボキシ（Ｃ_１～Ｃ_４）アルキル又はアルキルスルホネートが挙げられるが、これらに限定されず、ｐＨは７未満である。 An object of the present invention is a two-component silver-bismuth alloy electroplating composition containing a silver ion source, a bismuth ion source, and a 5-membered aromatic heterocyclic nitrogen compound having the following general formula.

In the formula, _Q1 to _Q4 may be substituted or unsubstituted nitrogen, or substituted or unsubstituted carbon, except that at least two of _Q1 to _Q4 are nitrogen, and the substituent is hydrogen. Examples include, but are not limited to, (C ₁ to C ₄ ) alkyl, amino group, aminoalkyl group, carboxyl, carboxy (C ₁ to C ₄ ) alkyl or alkyl sulfonate, and the pH is less than 7.

式中、Ｑ_１～Ｑ_４は置換若しくは非置換窒素、又は置換若しくは非置換炭素であり得るが、但し、Ｑ_１～Ｑ_４のうち少なくとも２つは窒素であり、置換基としては、水素、（Ｃ_１～Ｃ_４）アルキル、アミノ基、アミノアルキル基、カルボキシル、カルボキシ（Ｃ_１～Ｃ_４）アルキル又はアルキルスルホネートが挙げられるが、これらに限定されず、ｐＨは７未満である、ことと：
ｃ）二成分銀－ビスマス合金電気めっき組成物及び基材に電流を印加して、基材上に銀－ビスマス合金めっき層を電気めっきすることと、を含む方法を目的とする。 The present invention is also a method of electroplating a two-component silver-bismuth alloy on a substrate.
a) Providing a base material and
b) The substrate is contacted with a two-component silver-bismuth alloy electroplating composition comprising a silver ion source, a bismuth ion source, and a 5-membered aromatic heterocyclic nitrogen compound having the following general formula: hand,

In the formula, _Q1 to _Q4 may be substituted or unsubstituted nitrogen, or substituted or unsubstituted carbon, except that at least two of _Q1 to _Q4 are nitrogen, and the substituent is hydrogen. Examples include, but are not limited to, (C ₁ to C ₄ ) alkyl, amino group, aminoalkyl group, carboxyl, carboxy (C ₁ to C ₄ ) alkyl or alkyl sulfonate, and the pH is less than 7. :
c) A method comprising applying an electric current to a two-component silver-bismuth alloy electroplating composition and a substrate to electroplating a silver-bismuth alloy plating layer on the substrate.

The present invention is further intended for an article comprising a two-component silver-bismuth alloy layer adjacent to the surface of a substrate, wherein the two-component silver-bismuth alloy layer is 90% to 99% silver and 1% to 10%. It is equipped with bismuth and has a coefficient of friction of 1 or less.

In an acidic environment, a silver-rich two-component silver-by containing a five-membered aromatic heterocyclic nitrogen compound having the above formula (I) in an aqueous two-component silver-bismuth alloy electroplating composition. It is possible to plate the bismuth alloy onto the substrate, so that the silver-rich two-component silver-bismuth alloy has substantially good silver plating electrical properties, especially low electrical contact resistance. In addition, the silver-rich two-component silver-bismuth alloy plating layer has good mechanical wear resistance. The silver-rich two-component silver-bismuth- plated layer is homogeneous and has a matte to semi-glossy appearance. The two-component silver-bismuth alloy electroplating composition of the present invention is stable.

It is a scanning electron microscope image of 10,000 times a binary silver-bismuth alloy showing individual bismuth sectors in a silver matrix. It is a 2D profileometry diagram of the surface of the silver metal plating layer, and the x-axis and the y-axis are graduated in micrometer (μm) units. It is a 3D profileometry diagram of the surface of a silver metal plating layer, and the x-axis, y-axis, and z-axis are graduated in micrometer (μm) units. It is a 2D profileometry diagram of the surface of the silver-bismuth alloy plating layer of the present invention, the alloy is composed of 95% silver and 5% bismuth, and the x-axis, y-axis, and z-axis are in micrometer (μm) units. The scale is attached. It is a 3D profileometry diagram of the surface of the silver-bismuth alloy plating layer of the present invention, the alloy consists of 95% silver and 5% bismuth, and the x-axis, y-axis, and z-axis are in micrometer (μm) units. The scale is attached. It is a 2D profileometry diagram of the surface of the silver-bismuth alloy plating layer of the present invention, the alloy consists of 97% silver and 3% bismuth, and the x-axis, y-axis, and z-axis are in micrometer (μm) units. The scale is attached. It is a 3D profileometry diagram of the surface of the silver-bismuth alloy plating layer of the present invention, the alloy consists of 97% silver and 3% bismuth, and the x-axis, y-axis, and z-axis are in micrometer (μm) units. The scale is attached. It is a 2D profileometry diagram of the surface of the silver-bismuth alloy plating layer of the present invention, the alloy consists of 97% silver and 3% bismuth, and the x-axis, y-axis, and z-axis are in micrometer (μm) units. The scale is attached. It is a 3D profileometry diagram of the surface of the silver-bismuth alloy plating layer of the present invention, the alloy consists of 97% silver and 3% bismuth, and the x-axis, y-axis, and z-axis are in micrometer (μm) units. The scale is attached.

As used throughout the specification, the abbreviation shall have the following meanings, unless the context explicitly indicates otherwise: ° C = Siemens degree, ppm = parts per million, 1 ppm = 1 mg / L, g. = Gram, mg = milligram, L = liter, mL = milliliter, mm = millimeter, cm = centimeter, μm = micrometer, DI = deion, A = ampere, ASD = ampere / dm ² = plating rate, DC = DC; v = volt (this is the SI unit of electromotive force), mΩ = milliohm = contact resistance, cN = sentin Newton = unit of force, N = Newton, COF = friction coefficient, rpm = number of revolutions per minute, s = sec, 2D = 2D, 3D = 3D, Ag = Silver, Bi = Siemens, Au = Gold, Cu = Copper, Ag ⁺ Molecular Weight = 107.868g / mol, 3,6-Dithia-1,8- The molecular weight of octanediol = 182.3 g / mol.

The term "alkyl" means an organic functional group having the general formula C _n H _{2n + 1} , in which C is carbon, H is hydrogen and n is an integer. The term "aliphatic" means that the carbon atom is associated with or represents an organic compound that forms an open chain (as in alkanes) rather than an aromatic ring. The term "two-component" when referring to an alloy means a metallic solid consisting of a homogeneous mixture of two metals. The dashed line "----" in the chemical structure means an optional covalent bond. The term "adjacent" means that the two metal layers are in direct contact so as to have a common interface. The term "contact resistance" means electrical resistance as a function of applied force. The term "Newton" is the SI unit of force, which is equal to the force giving an acceleration of 1 meter per second squared to a mass of 1 kilogram, and is equivalent to 100,000 dynes. The term "coefficient of friction" is a value indicating the relationship between the frictional force between two objects and the normal force between the objects involved, and is indicated by F _f = μF _n , where F _f is in the equation. Friction force, μ is the coefficient of friction, and F _n is the normal force. The term "normal force" means a force applied perpendicular to the contact surface between two objects. The term "individual" means that they are individually separated and different from each other. The term "sector" means an area or part that is different from other areas. The term "matrix" means more than 50% of the surrounding metal or most metals, ie metal alloys. The term "proviso" means a condition or constraint. The term "tribology" refers to the science and engineering of surfaces that interact in relative motion and includes the study and application of the principles of lubrication, friction and wear. The term "cold weld" means a solid phase welding process in which a junction occurs without melting or heating at the interface between the two parts to be welded and there is no molten liquid or molten phase at the junction. The term "water-based" means water, or water-based. The terms "composition" and "bath" are used interchangeably throughout this specification. The terms "welded layer" and "layer" are used interchangeably throughout this specification. The terms "electroplating,""plating," and "welding" are used interchangeably throughout this specification. The term "matte" means dull or dull. The terms "a" and "an" can refer to both singular and plural throughout the specification. Unless otherwise specified, all percent values and ranges refer to percent weight. All numerical ranges are inclusive and can be combined in any order, with the exception of the case where it is logical to constrain the sum of such numerical ranges to be 100%. And.

式中、Ｑ_１～Ｑ_４は置換若しくは非置換窒素、又は置換若しくは非置換炭素であり得るが、但し、Ｑ_１～Ｑ_４のうち少なくとも３つは窒素であり、置換基としては、水素、（Ｃ_１～Ｃ_４）アルキル、アミノ基、アミノアルキル基、カルボキシル基、カルボキシ（Ｃ_１～Ｃ_４）アルキル又はアルキルスルホネートが挙げられるが、これらに限定されず、ｐＨは７未満である。好ましくは、置換基は、水素、（Ｃ_１～Ｃ_２）アルキル、ＮＨ_２などの第１級アミノ基、ＮＨ－ＮＨ_２などの第２級アミノ基、又はアミノ（Ｃ_１～Ｃ_４）アルキルであり、更に好ましくは、置換基は水素、メチル、又はＮＨ_２であり、より好ましくは、環の窒素が水素若しくはメチル基で置換されるか、又は環の窒素がＮＨ_２で置換され、或いは環の炭素がＮＨ_２で置換され、最も好ましくは、環の窒素が水素又はメチルで置換される。 The present invention aims at an aqueous acidic two-component silver-bismuth alloy electroplating composition, and the aqueous acidic two-component silver-bismuth alloy electroplating composition has a silver ion source, a bismuth ion source, and the following general formula5. Contains aromatic heterocyclic nitrogen compounds with a member ring,

In the formula, _Q1 to _Q4 may be substituted or unsubstituted nitrogen, or substituted or unsubstituted carbon, except that at least three of _Q1 to _Q4 are nitrogen, and the substituent is hydrogen. Examples thereof include, but are not limited to, (C ₁ to C ₄ ) alkyl, amino group, aminoalkyl group, carboxyl group, carboxy (C ₁ to C ₄ ) alkyl or alkyl sulfonate, and the pH is less than 7. Preferably, the substituent is hydrogen, a primary amino group such as (C ₁ to C ₂ ) alkyl, NH ₂ , a secondary amino group such as NH-NH ₂ , or an amino (C ₁ to C ₄ ) alkyl. More preferably, the substituent is hydrogen, methyl, or NH ₂ , and more preferably, the nitrogen in the ring is substituted with hydrogen or a methyl group, or the nitrogen in the ring is substituted with NH ₂ . The carbon of the ring is replaced with NH ₂ , and most preferably the nitrogen of the ring is replaced with hydrogen or methyl.

The matte to semi-glossy, homogeneous and silver-rich two-component silver-bismuth alloy plated layer has substantially good electrical properties such as low electrical contact resistance. The silver-rich two-component silver-bismuth alloy plated layer has a low coefficient of friction, so that the silver-rich two-component silver-bismuth alloy layer has good mechanical wear resistance. The acidic aqueous two-component silver-bismuth alloy electroplating composition of the present invention is stable. Aqueous two-component silver-bismas alloy electroplating compositions include antimony, tin, copper, nickel, cobalt, cadmium, gold, lead, indium, iron, palladium, platinum, rhodium, ruthenium, tellurium, tarium, selenium, and zinc. It does not include any additional alloyed metals, but not limited to these. Preferably, the acidic aqueous silver-bismuth alloy electroplating composition is cyanide-free.

３－メルカプト－１，２，４－トリアゾール、

３－アミノ－１，２，４－トリアゾール－５－チオール、

４－アミノ－３－ヒドラジノ－５－メルカプト－１，２，４－トリアゾール、

３－メルカプト－４－メチル－４Ｈ－１，２，４－トリアゾール、

１Ｈ－イミダゾール－２－チオール、及び
チオール官能基を有する５員環の芳香族複素環式窒素化合物の塩。より好ましくは、本発明のチオール官能基を有する５員環の芳香族複素環式窒素化合物は、３－メルカプト－１，２，４－トリアゾール、３－アミノ－１，２，４－トリアゾール－５－チオール、３－アミノ－５－メルカプト－１，２，４－トリアゾール、３－メルカプト－４－メチル－４Ｈ－１，２，４－トリアゾール、及びチオール官能基を有する５員環の芳香族複素環式窒素化合物の塩のうちの１つ以上から選択され、更により好ましくは、本発明のチオール官能基を有する５員環の芳香族複素環式窒素化合物は、３－メルカプト－１，２，４－トリアゾール、３－アミノ－１，２，４－トリアゾール－５－チオール、３－アミノ－５－メルカプト－１，２，４－トリアゾール、３－メルカプト－４－メチル－４Ｈ－１，２，４－トリアゾール、及び本発明のチオール官能基を有する５員環の芳香族複素環式窒素化合物の塩のうちの１つ以上から選択され、更に好ましくは、本発明のチオール官能基を有する５員環の芳香族複素環式窒素化合物は、３－メルカプト－１，２，４－トリアゾール、３－メルカプト－４－メチル－４Ｈ－１，２，４－トリアゾール、及び本発明のチオール官能基を有する５員環の芳香族複素環式窒素化合物の塩のうちの１つ以上から選択される。本発明のチオール官能基を有する５員環の芳香族複素環式窒素化合物の塩としては、ナトリウム、カリウム、及びリチウム塩、アンモニウム塩、テトラアルキルアンモニウム塩、マグネシウム塩、銀塩、並びにビスマス塩などのアルカリ金属塩が挙げられるが、これらに限定されない。 Examples of preferred 5-membered aromatic heterocyclic nitrogen compounds of the present invention are as follows.

3-Mercapto-1,2,4-triazole,

3-Amino-1,2,4-Triazole-5-thiol,

4-Amino-3-hydrazino-5-mercapto-1,2,4-triazole,

3-Mercapt-4-methyl-4H-1,2,4-triazole,

A salt of 1H-imidazole-2-thiol and a 5-membered aromatic heterocyclic nitrogen compound having a thiol functional group. More preferably, the 5-membered aromatic heterocyclic nitrogen compound having a thiol functional group of the present invention is 3-mercapto-1,2,4-triazole and 3-amino-1,2,4-triazole-5. -Thiol, 3-amino-5-mercapto-1,2,4-triazole, 3-mercapto-4-methyl-4H-1,2,4-triazole, and 5-membered aromatic complex with thiol functional group. The 5-membered aromatic heterocyclic nitrogen compound selected from one or more of the salts of the cyclic nitrogen compound, and even more preferably the thiol functional group of the present invention, is 3-mercapto-1,2, 4-Triazole, 3-amino-1,2,4-triazole-5-thiol, 3-amino-5-mercapto-1,2,4-triazole, 3-mercapto-4-methyl-4H-1,2, It is selected from one or more of 4-triazole and a salt of a 5-membered aromatic heterocyclic nitrogen compound having a thiol functional group of the present invention, and more preferably 5 members having a thiol functional group of the present invention. The ring aromatic heterocyclic nitrogen compound has 3-mercapto-1,2,4-triazole, 3-mercapto-4-methyl-4H-1,2,4-triazole, and the thiol functional group of the present invention. It is selected from one or more of the salts of 5-membered aromatic heterocyclic nitrogen compounds. Examples of the salt of the 5-membered aromatic heterocyclic nitrogen compound having a thiol functional group of the present invention include sodium, potassium, lithium salt, ammonium salt, tetraalkylammonium salt, magnesium salt, silver salt, bismuth salt and the like. Alkaline metal salts, but are not limited to these.

The 5-membered aromatic heterocyclic nitrogen compound having a thiol functional group and a salt thereof in the present invention are in sufficient quantity to enable electroplating of a silver-rich two-component silver-bismuth alloy in an aqueous acid environment. Included in. Preferably, the 5-membered aromatic heterocyclic nitrogen compound having a thiol functional group of the present invention is in an amount of 50 ppm or more, more preferably 100 ppm to 100 g / L, still more preferably 100 ppm to 20 g / L, further. More preferably, it is contained in an amount of 100 ppm to 10 g / L, and most preferably 100 ppm to 5 g / L.

The aqueous silver acid-bismuth alloy electroplating composition of the present invention comprises a silver ion source. Silver ion sources include, but are not limited to, silver halide, silver gluconate, silver citrate, silver lactate, silver nitrate, silver sulfate, silver alkane sulfonate, silver alkanol sulfonate, or mixtures thereof. Can be provided. When silver halide is used, the halide is preferably chloride. Preferably, the silver salt is silver sulfate, silver alkanesulfonate, silver nitrate, or a mixture thereof, and more preferably, the silver salt is silver sulfate, silver methanesulfonate, or a mixture thereof. A mixture of silver salts may also be included in the composition. Silver salts are generally commercially available or can be prepared by the methods described in the literature. Preferably, the silver salt is water-soluble.

The amount of silver salt in the aqueous acid two-component silver-bismas alloy electroplating composition is sufficient to provide a semi-glossy and homogeneous silver-rich two-component silver-bismas alloy plating layer from the desired matte. The amount is preferably 90% to 99.8% silver, more preferably 90% to 99.7%, and most preferably 95% in the silver content of the silver-rich two-component silver-bismuth alloy plating layer. It contains ~ 99.7% silver and the balance of the alloyed metal is bismuth, excluding unavoidable impurities here. Preferably, the silver salt is included in the composition to provide silver ions at a concentration of at least 10 g / L, more preferably the silver salt has a silver ion concentration in an amount of 10 g / L to 100 g / L. It is contained in the composition in an amount provided, more preferably the silver salt is contained in an amount providing a silver ion concentration of 20 g / L to 80 g / L, and most preferably the silver salt is contained in an amount of 20 g / L to 20 g / L. Included in an amount that provides silver ions at a concentration of 60 g / L.

The aqueous silver acid-bismuth alloy electroplating composition comprises a bismuth ion source that provides an electroplating bath containing Bi ³⁺ ions in the solution. Examples of the bismuth ion source include bismuth salts of alkan sulfonic acid such as bismuth methanesulfonic acid, bismuth ethanesulfonic acid, bismuth propanesulfonic acid, 2-bismus propanesulfonic acid, and bismuth p-phenolsulfonic acid, and bismuth hydroxymethanesulfonic acid. Examples thereof include bismuth salts of alkanolsulfonic acid such as 2-hydroxyethane-1-sulfonic acid bismuth and 2-hydroxybutane-1-sulfonic acid bismuth, and bismuth salts such as bismuth nitrate, bismuth sulfate, and bismuth chloride. Not limited to. A mixture of bismuth salts may also be included in the composition. Preferably, the bismuth salt is water soluble.

The amount of bismuth salt contained in the aqueous acid two-component silver-bismuth alloy electroplating composition is sufficient to provide a semi-glossy and homogeneous silver-rich two-component silver-bismuth alloy plating layer from the desired matte. The amount, preferably, the bismuth content of the silver-rich two-component silver-bismuth alloy plating layer is 0.2% to 10% bismuth, more preferably 0.3% to 10% bismuth, most preferably. Contains 0.3% to 5% bismuth. Preferably, the bismuth salt is added to the silver-bismuth composition so as to provide the bismuth (III) ion in an amount of 50 ppm to 10 g / L, more preferably 100 ppm to 5 g / L, most preferably 200 ppm to 5 g / L. included. Such bismuth salts are commercially available or can be prepared as disclosed in the chemical literature. They are generally commercially available from various sources such as the Aldrich Chemical Company (Milwaukee, Wisconsin).

Preferably, in the aqueous silver acid-bismuth alloy electroplating composition of the present invention, the water contained as a solvent is at least one of deionization and distillation to limit incidental impurities.

Optionally, the acid may be included in the two-component silver-bismuth alloy electroplating composition to aid in providing conductivity to the composition. Examples of the acid include organic acids such as acetic acid and citric acid, alkane sulfonic acid such as aryl sulfonic acid, methane sulfonic acid, ethane sulfonic acid, or propane sulfonic acid, aryl sulfonic acid such as phenyl sulfonic acid or trill sulfonic acid, and sulfuric acid. , Sulfamic acid, hydrochloric acid, hydrobromic acid, or inorganic acids such as hydroborofluoric acid, but are not limited thereto. The water-soluble salts of the above acids may also be included in the two-component silver-bismuth alloy electroplating compositions of the present invention. Preferably, the acid is acetic acid, citric acid, alkane sulfonic acid, aryl sulfonic acid, or a salt thereof, and more preferably, the acid is acetic acid, citric acid, methane sulfonic acid, or a salt thereof. Examples of such salts include, but are not limited to, sodium, potassium, silver, bismuth, magnesium, tetraalkylammonium, and ammonium salts. A mixture of acids may be used, but preferably a single acid is used when used. Acids are generally commercially available or can be prepared by methods known in the literature. Such acids may be included in an amount such that they provide the desired conductivity. Preferably, the acid or salt thereof is in an amount of at least 5 g / L, more preferably 10 g / L to 250 g / L, even more preferably 30 g / L to 150 g / L, most preferably 30 g / L to 125 g / L. included.

The pH of the aqueous acidic two-component silver-bismuth alloy electroplating composition is less than 7. Preferably, the pH is 0 to 6, more preferably 0 to 5, even more preferably 0 to 3, and even more preferably 0 to 2.5. Most preferably, the pH is 0-2.

Optionally, the aqueous acid two-component silver-bismuth alloy electroplating composition of the present invention may contain a pH adjuster. Examples of such a pH adjuster include inorganic acids, organic acids, inorganic bases, or organic bases, and salts thereof. Examples of such acids include, but are not limited to, inorganic acids such as sulfuric acid, hydrochloric acid, sulfamic acid, boric acid, phosphoric acid, or salts thereof. Examples of the organic acid include, but are not limited to, acetic acid, citric acid, aminoacetic acid, and ascorbic acid, or salts thereof. Examples of such salts include, but are not limited to, trisodium citrate. Inorganic bases such as sodium hydroxide and potassium hydroxide, as well as organic bases such as various types of amines can be used. Preferably, the pH regulator is selected from acetic acid, citric acid, aminoacetic acid, or salts thereof, and most preferably from acetic acid, citric acid, or salts thereof. The pH regulator may be added as needed in an amount to maintain the desired pH range.

Optionally, but preferably, thioether is included in the aqueous acid two-component silver-bismuth alloy electroplating composition of the present invention. Such thioethers include 2,2'-thiodiethanol, 4,4'-thiodiphenol, and 4,4'-thiobis (2-methyl-6-tert-butylphenol), dihydroxybis-sulfide compounds, or these. Mixtures include, but are not limited to. Examples of such dihydroxybis-sulfide compounds include 2,4-dithia-1,5-pentanediol, 2,5-dithia-1,6-hexanediol, 2,6-dithia-1,7-heptanediol, 2, 7-Dithia-1,8-octanediol, 2,8-Dithia-1,9-nonanediol, 2,9-Dithia-1,10-decanediol, 2,11-dithia-1,12-dodecanediol, 5,8-Dithia-1,12-dodecanediol, 2,15-Dithia-1,16-hexadecanediol, 2,21-Dithia-1,2-dodecanediol, 3,5-Dithia-1,7 -Heptanediol, 3,6-dithia-1,8-octanediol, 3,8-dithia-1,10-decanediol, 3,10-dithia-1,8-dodecanediol, 3,13-dithia-1 , 15-Pentadecanediol, 3,18-dithia-1,20-eicosandiol, 4,6-dithia-1,9-nonanediol, 4,7-dithia-1,10-decanediol, 4,11- Dithia-1,14-tetradecanediol, 4,15-dithia-1,18-octadecanediol, 4,19-dithia-1,2-dodecanediol, 5,7-dithia-1,11-undecanediol, 5,9-dithia-1,13-tridecanediol, 5,13-dithia-1,17-heptadecanediol, 5,17-dithia-1,21-uneicosanediol, and 1,8 Includes, but is not limited to, -dimethyl-3,6-dithia-1,8-octanediol. Preferably, the dihydroxybis-sulfide compound is 3,6-dithia-1,8-octanediol, 3,8-dithia-1,10-decanediol, 2,4-dithia-1,5-pentanediol, 2 , 5-Dithia-1,6-hexanediol, 2,6-Dithia-1,7-heptanediol, 2,7-Dithia-1,8-octanediol, more preferably 3,6-Dithia-1. , 8-octanediol, 2,4-dithia-1,5-pentanediol, 2,5-dithia-1,6-hexanediol, 2,6-dithia-1,7-heptanediol, or 2,7- From dithia-1,8-octanediol, even more preferably 3,6-dithia-1,8-octanediol, 2,6-dithia-1,7-heptanediol, or 2,7-dithia-1, It is selected from 8-octanediol, most preferably from 3,6-dithia-1,8-octanediol.

Preferably, the thioether compound is at least 1 mol thioether vs 1 mol silver, more preferably 1-5 mol thioether vs 1 mol silver, even more preferably 2-4 mol thioether vs 1 mol silver, most preferably. It may be included in an aqueous acid two-component silver-bismuth alloy electroplating composition in a molar ratio of 2.5-4 mol thioether to 1 mol silver, preferably silver.

Optionally, but preferably, the aqueous acid two-component silver-bismuth alloy electroplating composition of the present invention can comprise an aliphatic thiol-terminated compound. Examples of such aliphatic thiol terminal compounds include thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, cysteine, mercaptosuccinic acid, 3-mercapto-1-propanesulfonic acid, 2-mercaptoethanesulfonic acid, and the like. Salt, but is not limited to these. Examples of the salt of the aliphatic thiol terminal compound of the present invention include, but are not limited to, alkali metal salts such as sodium and potassium salts, and ammonium salts.

Preferably, the aliphatic thiol-terminated aliphatic compound of the present invention is contained in an amount of 1 g / L or more, and more preferably, the aliphatic thiol-terminated compound is 1 g / L to 100 g / L, most preferably 1 g / L. Included in an amount of ~ 60 g / L.

Optionally, the aqueous silver acid-bismuth alloy electroplating composition of the present invention may contain one or more surfactants. Examples of such surfactants include, but are not limited to, cationic and anionic surfactants, nonionic surfactants, and ionic surfactants such as amphoteric surfactants. The surfactant may be contained in a conventional amount such as 0.05 g / L to 30 g / L.

Examples of anionic surfactants are sodium di (1,3-dimethylbutyl) sulfosuccinate, sodium 2-ethylhexyl sulfate, sodium diamil sulfosuccinate, sodium lauryl sulfate, sodium lauryl ether sulfate, sodium dialkyl sulfosuccinate, and dodecyl. Sodium benzenesulfonate. Examples of cationic surfactants are quaternary ammonium salts such as perfluorinated quaternary amines.

Further optional additives, such as biocides, may be included in the silver-bismuth alloy electroplating compositions of the present invention. Conventional biocides well known in the art may be included in the silver-bismuth alloy electroplating compositions of the present invention. The biocide is included in conventional amounts well known to those of skill in the art. Preferably, the compounds acting as levelers are excluded from the silver-bismuth alloy electroplating compositions of the present invention.

式中、Ｑ_１～Ｑ_４は置換若しくは非置換窒素、又は置換若しくは非置換炭素であり得るが、但し、Ｑ_１～Ｑ_４のうち少なくとも２つは窒素であり、置換基としては、水素、（Ｃ_１～Ｃ_４）アルキル、アミノ基、アミノアルキル基、カルボキシル、カルボキシ（Ｃ_１～Ｃ_４）アルキル又はアルキルスルホネート、任意選択的にチオエーテル、任意選択的に脂肪族チオール末端化合物又はその塩、任意選択的に酸又はその塩、任意選択的にｐＨ調整剤、任意選択的に殺生物剤、及び任意選択的に界面活性剤が挙げられるが、これらに限定されず、ｐＨは７未満である。 Preferably, the acidic aqueous two-component silver-bismuth alloy electroplating composition of the present invention comprises water, silver ion and counter anion, bismuth (III) ion and counter anion, a 5-membered aromatic complex having the following general formula. Consists of cyclic nitrogen compounds

In the formula, _Q1 to _Q4 may be substituted or unsubstituted nitrogen, or substituted or unsubstituted carbon, except that at least two of _Q1 to _Q4 are nitrogen, and the substituent is hydrogen. (C ₁ to C ₄ ) alkyl, amino group, aminoalkyl group, carboxyl, carboxy (C ₁ to C ₄ ) alkyl or alkyl sulfonate, optionally thioether, optionally aliphatic thiol terminal compound or salt thereof, Examples include, but are not limited to, an acid or a salt thereof, optionally a pH adjuster, optionally a killing agent, and optionally a surfactant, but the pH is less than 7. ..

式中、Ｑ_１～Ｑ_４は置換若しくは非置換窒素、又は置換若しくは非置換炭素であり得るが、但し、Ｑ_１～Ｑ_４のうち少なくとも２つは窒素であり、置換基としては、水素、（Ｃ_１～Ｃ_４）アルキル、アミノ基、アミノアルキル基、カルボキシル、カルボキシ（Ｃ_１～Ｃ_４）アルキル又はアルキルスルホネート、チオエーテル、任意選択的に脂肪族チオール末端化合物又はその塩、任意選択的に酸又はその塩、任意選択的にｐＨ調整剤、任意選択的に殺生物剤、及び任意選択的に界面活性剤が挙げられるが、これらに限定されず、ｐＨは０～６である。 More preferably, the acidic aqueous two-component silver-bismuth alloy electroplating composition of the present invention comprises water, silver ion and counter anion, bismuth (III) ion and counter anion, and a 5-membered ring aromatic having the following general formula. Consists of heterocyclic nitrogen compounds

In the formula, _Q1 to _Q4 may be substituted or unsubstituted nitrogen, or substituted or unsubstituted carbon, except that at least two of _Q1 to _Q4 are nitrogen, and the substituent is hydrogen. (C ₁ to C ₄ ) alkyl, amino group, aminoalkyl group, carboxyl, carboxy (C ₁ to C ₄ ) alkyl or alkyl sulfonate, thioether, optionally aliphatic thiol terminal compound or salt thereof, optionally Examples include, but are not limited to, acids or salts thereof, optionally pH adjusters, optionally killing agents, and optionally surfactants, the pH is 0-6.

式中、Ｑ_１～Ｑ_４は置換若しくは非置換窒素、又は置換若しくは非置換炭素であり得るが、但し、Ｑ_１～Ｑ_４のうち少なくとも２つは窒素であり、置換基としては、水素、（Ｃ_１～Ｃ_４）アルキル、アミノ基、アミノアルキル基、カルボキシル、カルボキシ（Ｃ_１～Ｃ_４）アルキル又はアルキルスルホネート、ジヒドロキシビス－スルフィド化合物、脂肪族チオール末端化合物又はその塩、酸又はその塩、任意選択的にｐＨ調整剤、任意選択的に殺生物剤、及び任意選択的に界面活性剤が挙げられるが、これらに限定されず、ｐＨは０～６である。 More preferably, the acidic aqueous two-component silver-bismuth alloy electroplating composition of the present invention comprises water, silver ion and counter anion, bismuth (III) ion and counter anion, a 5-membered ring aromatic having the following general formula. Consists of heterocyclic nitrogen compounds

In the formula, _Q1 to _Q4 may be substituted or unsubstituted nitrogen, or substituted or unsubstituted carbon, except that at least two of _Q1 to _Q4 are nitrogen, and the substituent is hydrogen. (C ₁ to C ₄ ) Alkyl, amino group, aminoalkyl group, carboxyl, carboxy (C ₁ to C ₄ ) alkyl or alkyl sulfonate, dihydroxybis-sulfide compound, aliphatic thiol terminal compound or salt thereof, acid or salt thereof. , Optionally include, but are not limited to, pH adjusters, optionally killing agents, and optionally surfactants, the pH is 0-6.

Even more preferably, the acidic aqueous two-component silver-bismas alloy electroplating composition of the present invention comprises water, silver ions and counter anions, bismus (III) ions and counter anions, 3-mercapto-1,2,4-triazole. , 3-Amino-1,2,4-Triazole-5-thiol, 3-Amino-5-Mercapto-1,2,4-Triazole, 3-Mercapto-4-methyl-4H-1,2,4-Triazole , 1H-imidazole-2-thiol, a salt of a 5-membered aromatic heterocyclic nitrogen compound having a thiol functional group, and a compound selected from the group consisting of a mixture thereof, a dihydroxybis-sulfide compound, a thioglycolic acid. , 2-Mercaptopropionic acid, 3-Mercaptopropionic acid, cysteine, mercaptosuccinic acid, 3-mercapto-1-propanesulfonic acid, 2-mercaptoethanesulfonic acid, and aliphatic thiols selected from the group consisting of salts thereof. It consists of a terminal compound, an acid or a salt thereof, optionally a pH adjuster, optionally a killing agent, and optionally a surfactant, with a pH of 0-3.

The acidic aqueous two-component silver-bismuth alloy electroplating composition of the present invention can be used to plate a two-component silver-bismuth alloy layer on various substrates, both conductive and semiconductor substrates. Preferably, the substrate on which the silver-bismas alloy layer is plated is a nickel, nickel alloy, copper, and copper alloy substrate. Examples of such a nickel alloy base material include, but are not limited to, nickel-phosphorus and nickel-boron. Examples of such a copper alloy base material include, but are not limited to, brass and bronze.

The temperature of the electroplating composition during plating may be in the range of room temperature to 70 ° C., preferably 30 ° C. to 60 ° C., more preferably 40 ° C. to 60 ° C. The two-component silver-bismuth alloy electroplating composition is preferably under continuous stirring during the electroplating process.

The acidic aqueous two-component silver-bismuth alloy electroplating method of the present invention provides a substrate, provides an acidic aqueous two-component silver-bismuth alloy electroplating composition of the present invention, and comprises a substrate. The substrate is brought into contact with the acidic aqueous two-component silver-bismuth alloy electroplating composition by immersing it in or spraying the composition onto the substrate, and applying an electric current with a conventional rectifier. The substrate functions as a cathode and there is a counter electrode or an anode. The anode may be any conventional soluble or insoluble anode used for electroplating a two-component silver-bismuth alloy. The two-component silver-bismas alloy is plated adjacent to the surface of the substrate and the surface of the substrate is nickel, nickel alloy, copper, or copper alloy.

The acidic aqueous two-component silver-bismuth alloy electroplating composition of the present invention allows plating of matte to semi-glossy and homogeneous silver-rich silver-bismuth alloy layers over a wide range of current densities. Silver-rich two-component silver-bismuth alloys, excluding unavoidable impurities in the alloy, have 90% to 99.8% silver and 0.2% to 10% bismuth, preferably 90% to 99. It contains 7% silver and 0.3% to 10% bismuth, most preferably 95% to 99.7% silver and 0.3% to 5% bismuth.

The current density for electroplating a semi-glossy and homogeneous silver-rich silver-bismuth alloy from the mat of the present invention may be in the range of 0.1 ASD or more. Preferably, the current density is in the range of 0.5 ASD to 70 ASD, more preferably 1 ASD to 40 ASD, more preferably 1 ASD to 30 ASD, and even more preferably 1 ASD to 15 ASD.

The thickness of the two-component silver-bismuth alloy layer of the present invention may vary depending on the function of the silver-bismuth alloy layer and the type of substrate on which it is plated. Preferably, the two-component silver-bismuth alloy layer spans a range of 1 μm or more. More preferably, the two-component silver-bismuth alloy layer has a thickness of 1 μm to 100 μm, more preferably 1 μm to 50 μm, even more preferably 1 μm to 10 μm, and most preferably 1 μm to 5 μm.

It is assumed that the acidic aqueous two-component silver-bismuth alloy electroplating composition of the present invention can be used for plating various substrates such as a silver-bismuth alloy layer, but the present invention is preferable. The acidic aqueous two-component silver-bismas alloy electroplating composition of the present invention is used for electroplating the top layer or coating of an electrical connector where substantial contact force and wear are expected to be superior. The silver-rich two-component silver-bismuth alloy plating layer is a highly desirable alternative to the traditional silver coatings found on conventional connectors. The silver-bismuth alloy plating layer has low electrical contact resistance. Further, the silver-bismuth alloy plating layer of the present invention has a low COF, preferably 1 or less, more preferably 0.6 or less. The COF of the silver-bismuth alloy plated layer of the present invention is preferably 40% or lower than that of a substantially pure silver plated layer, so that the two-component silver-bismuth alloy of the present invention is substantially. Has a substantial improvement in wear resistance over pure silver. Surface wear of the metal plating layer can be determined according to conventional friction and profileometry measurements well known in the art.

The following examples are included to further illustrate the invention, but are not intended to limit its scope.

Two-component silver-bismuth alloy electroplating treatment Examples 1 to 22:
Electroplating process Unless otherwise noted, in all cases the electroplating substrate was a 5 cm x 5 cm brass (70% copper, 30% zinc) cut-out specimen. Prior to electroplating, the cut pieces were electrolyzed for 30 seconds in a RONACLEAN ™ GP-300 LF Electrical Cleaner Alkaline Degreaser (available from DuPont) at 80 ° C. using DC with a current density of 5 ASD. .. After electrolytic cleaning, the cut specimen was rinsed with DI water, activated in 10% sulfuric acid for 30 seconds, rinsed again with DI water, and then placed in an electroplating bath. The electroplating process was performed for 6 minutes using DC with a current density of 1 ASD (actual current applied is 0.56 A). The electroplating process was performed using a platinum plated titanium anode in a square glass beaker. Stirring was provided by a 5 cm long TEFLON ™ coated stir bar at a rotation speed of 400 rpm. The electroplating treatment was carried out at a temperature of 55 ° C. The two-component silver-bismuth alloy plating layer had a thickness of about 6 μm. All two-component silver-bismuth alloy electroplating baths were water-based. Water was added to each bath until the desired volume was reached. The pH of the electroplating bath was adjusted with potassium hydroxide or methanesulfonic acid.

The thickness and elemental composition of the electroplated two-component silver-bismuth alloy was measured using a Bowman Series PX-Ray Fluorimeter (XRF) available from Bowman (Schaumburg, IL). XRF is calibrated using pure element thickness standards of silver and bismuth available from Hitachi, Ltd. (Chiyoda-ku, Tokyo, Japan), Fisher GmbH (Sindelfingen, Germany) and Veeco (Planinview, New York, USA). The composition and thickness of the alloys were calculated by combining pure elemental standards with basic parameter (FP) calculations using a software package with Bowman Series PX-Ray Fluorimeter.

Contact Resistance Measurements Contact resistance was evaluated using custom designed equipment including the Starrett MTH-550 manual force tester stand equipped with the Starrett DFC-20 digital force gauge (Athol, MA, USA). The digital force gauge was equipped with a gold-plated copper probe with a hemispherical tip with a diameter of 2.5 mm. The electrical resistance of the contact between the gold-plated probe and the flat cut piece plated with the silver alloy of interest was measured using 4-wire resistance measurement when the contact force changed. The current source was a Keithley 6220 DC Current Source operating at 10 mA, and the voltmeter was a Keithley 2182A Nanovoltagemeter (Cleveland, OH, USA). These devices were operated in thermoelectric compensation mode for maximum accuracy.

Abrasion resistance measurements Friction measurements were performed using an Antonio Pair TRB3 pin-on-disk friction meter (available from Antonio Par GmbH (Graz, Australia)) equipped with a linear reciprocating table. All tests were performed with a load of 1N, a stroke length of 10 mm, and a slide speed of 5 mm / sec. All tests were performed "like-on-like". This means that flat cut pieces and spherical balls are plated with the same silver (SILVER GLO ™ 3K Bright Silver plating bath, cyanide product available from DuPont) or a metal plating layer of silver-bismas alloy, respectively. It means that it has been processed. The balls used were made of C260 brass (70% copper, 30% zinc), had a diameter of 5.55 mm, and were electroplated with about 5 μm of silver. The flat cut piece was also made of C260 brass and was electroplated with about 2 μm of silver or silver-bismuth alloy. During the test, the coefficient of friction was monitored using a friction meter. The wear trace depth was measured using a laser profileometry. Measurements were performed for either 100 or 500 cycles as specified in each case.

The cycle was one round trip of the tribometer. The sample was moved in one direction and then reversed to return the tribometer to its original position, during which the sample was under a 1N load and was in contact with a spherical ball. This was one cycle.

Profilerometry measurements were performed using a Keyence VK-X Laser Scanning Confocal Microscope (available from Keyence Corporation of America (Elmwood Park, NJ)). Abrasion traces were measured using a laser profileometry at a magnification of 200x. 3D and 2D profileometry diagrams were generated from these measurements using Keyence's VK-X Multianalyzer software.

Example 1 (invention)
An aqueous acid two-component silver-bismuth alloy electroplating bath having the following composition was prepared.
Silver methanesulfonate for supplying 20 g / L of silver ions 3,6-dithia-1,8-octanediol: 102 g / L
Bismuth methanesulfonate for supplying 0.8 g / L bismuth ion Bismuth cysteine: 1.4 g / L
3-Mercapto-1,2,4-triazole: 1.5 g / L
Adjust pH to 1.6

After the plating treatment, the electroplating coating became semi-glossy and had a composition of 98.9% silver and 1.1% bismuth.

Example 2 (invention)
An aqueous acid two-component silver-bismuth alloy electroplating bath having the following composition was prepared.
Silver methanesulfonate for supplying 20 g / L of silver ions 3,6-dithia-1,8-octanediol: 102 g / L
Bismuth methanesulfonate for supplying 5 g / L bismuth ion Bismuth cysteine: 9 g / L
2-Mercapt-1,2,4-triazole: 400 ppm
Adjust pH to 2

After the plating treatment, the electroplating coating became metallic and semi-glossy, and the composition was 95% silver and 5% bismuth. FIG. 1 is a scanning electron microscope image of a two-component silver-bismuth alloy showing a zone of individual bismuth represented by bright spots in a silver matrix at a magnification of 10,000 times.

Example 3 (invention)
An aqueous acid two-component silver-bismuth alloy electroplating bath having the following composition was prepared.
Silver methanesulfonate for supplying 20 g / L of silver ions 3,6-dithia-1,8-octanediol: 102 g / L
Bismuth 3-mercapto-1-propanesulfonate for supplying 5 g / L bismuth ion, sodium salt: 13.2 g / L
3-Mercapto-1,2,4-triazole: 400 ppm
Adjust pH to 2

After the plating treatment, the electroplating coating became metallic and semi-glossy, and the composition was 96% silver and 4% bismuth.

Example 4 (invention)
An aqueous acid two-component silver-bismuth alloy electroplating bath having the following composition was prepared.
Silver methanesulfonate for supplying 20 g / L of silver ions 3,6-dithia-1,8-octanediol: 102 g / L
Bismuth 3-mercapto-1-ethanesulfonate for supplying 5 g / L bismuth ion, sodium salt: 12.2 g / L
3-Mercapto-1,2,4-triazole: 400 ppm
Adjust pH to 2

After the plating treatment, the electroplated coating became metallic and semi-glossy and had a composition of 96% silver and 4% bismuth.

Example 5 (invention)
An aqueous acid two-component silver-bismuth alloy electroplating bath having the following composition was prepared.
Silver methanesulfonate for supplying 20 g / L of silver ions 3,6-dithia-1,8-octanediol: 102 g / L
Bismuth methanesulphonate for supplying 5 g / L bismuth mercaptosuccinic acid: 11.1 g / L
3-Mercapto-1,2,4-triazole: 400 ppm
Adjust pH to 2

After the plating treatment, the electroplating coating became metallic and matte, and the composition was 98% silver and 2% bismuth.

Example 6 (invention)
An aqueous acid two-component silver-bismuth alloy electroplating bath having the following composition was prepared.
Silver methanesulfonate for supplying 20 g / L of silver ions 3,6-dithia-1,8-octanediol: 102 g / L
Bismuth methanesulfonate for supplying 5 g / L bismuth ion Bismuth cysteine: 9 g / L
3-Mercapt-4-methyl-4H-1,2,4-triazole: 400 ppm
Adjust pH to 2

After the plating treatment, the electroplating coating became metallic and semi-glossy, and the composition was 95% silver and 5% bismuth.

Example 7 (invention)
An aqueous acid two-component silver-bismuth alloy electroplating bath having the following composition was prepared.
Silver methanesulfonate for supplying 20 g / L of silver ions 3,6-dithia-1,8-octanediol: 34 g / L
Mercaptosuccinic acid: 35 g / L
Bismuth 3-mercapto-1,2,4-triazole for supplying 2 g / L bismuth ions: 400 ppm
Adjust pH to 2

After the plating treatment, the electroplating coating became metallic and semi-glossy, and the composition was 97% silver and 3% bismuth.

Example 8 (invention)
An aqueous acid two-component silver-bismuth alloy electroplating bath having the following composition was prepared.
Silver methanesulfonate for supplying 20 g / L of silver ions 3,6-dithia-1,8-octanediol: 34 g / L
Mercaptosuccinic acid: 35 g / L
Bismuth 3-mercapto-4-methyl-4H-1,2,4-triazole for supplying 2 g / L bismuth ion: 400 ppm
Adjust pH to 2

After the plating treatment, the electroplating coating became metallic and semi-glossy, and the composition was 97% silver and 3% bismuth.

Example 9 (invention)
An aqueous acid two-component silver-bismuth alloy electroplating bath having the following composition was prepared.
Silver methanesulfonate for supplying 20 g / L of silver ions 3,6-dithia-1,8-octanediol: 34 g / L
Mercaptosuccinic acid: 35 g / L
Bismuth methanesulfonate for supplying 2 g / L bismuth ion 1H-imidazol-2-thiol: 400 ppm
Adjust pH to 2

After the plating treatment, the electroplating coating became metallic and semi-glossy, and the composition was 97% silver and 3% bismuth.

Example 10 (Comparative Example)
An aqueous acid two-component silver-bismuth alloy electroplating bath having the following composition was prepared.
Silver Methanesulfonic Acid for Supplying 20 g / L Silver Ion Bismuth Methanesulfonic Acid for Supplying 10 g / L Bismuth Sulfonic Acid: 150 g / L
PLURONIC ™ L-44 Surfactant (purchased from BASF): 10 g / L
O-chlorobenzaldehyde: 100 ppm
3,6-dithia-1,8-octanediol: 80 g / L
pH <1

After the plating procedure, the electroplated coating was metallic and semi-glossy, with a composition of 46% silver and 54% bismuth.

Example 11 (Comparative Example)
An aqueous acid two-component silver-bismuth alloy electroplating bath having the following composition was prepared.
Silver methanesulfonate for supplying 20 g / L of silver ions 3,6-dithia-1,8-octanediol: 102 g / L
Bismuth methanesulfonate for supplying 5 g / L bismuth ion Bismuth cysteine: 9 g / L
4-Amino-1,2,4-triazole: 400 ppm
Adjust pH to 2

After the plating treatment, the electroplating coating became metallic and matte, and the composition was 97% silver and 3% bismuth.

Example 12 (Comparative Example)
An aqueous acid two-component silver-bismuth alloy electroplating bath having the following composition was prepared.
Silver methanesulfonate for supplying 20 g / L of silver ions 3,6-dithia-1,8-octanediol: 102 g / L
Bismuth methanesulfonate for supplying 5 g / L bismuth ion Bismuth cysteine: 9 g / L
1,2,4-Triazole: 400ppm
Adjust pH to 2

After the plating treatment, the electroplating coating became metallic and matte, and the composition was 97% silver and 3% bismuth.

Example 13 (Comparative Example)
An aqueous alkaline cyanide-based silver electroplating bath having the following composition was prepared.
Potassium cyanide for supplying 40 g / L of silver ions Potassium cyanide: 120 g / L
Potassium carbonate: 15 g / L
Potassium selenocyanate; 7 mg / L

After the plating treatment, the electroplating coating became metallic and glossy, and the composition was 100% silver.

Example 14 (Comparative Example)
An aqueous alkaline cyanide-based two-component silver-antimony electroplating bath having the following composition was prepared.
Potassium cyanide for supplying 40 g / L of silver ions Potassium cyanide: 120 g / L
Potassium carbonate: 15 g / L
Potassium selenocyanate; 6 mg / L
Potassium sodium tartrate: 10 g / L
Tripotassium citrate: 19 g / L
Potassium tartrate antimony: 7.8 g / L

After the plating treatment, the electroplating coating became metallic and glossy, and the composition was 98% silver and 2% antimony.

Example 15
The contact resistance measurement test was performed with silver from Comparative Example 13 of about 3 μm, silver-antimon alloy (98% silver, 2% antimon) from Comparative Example 14, and Examples 2, 8 and 9 above. It was carried out using a flat nickel cutting sample electroplated with a two-component silver-bismas alloy from an aqueous acid two-component silver-bismuth alloy electroplating bath disclosed in the invention). Prior to the measurement, the cut piece was heated in an oven at 150 ° C. for 100 hours. The contact resistance of the cut piece is shown in Table 1 below.

Example 16 (Comparative Example)
Abrasion resistance measurements were performed on the electroplated silver metal plating layer using the bath described in Example 13 (comparison). The test was carried out for 100 cycles. FIG. 2 is a 2D profileometry diagram of a silver- plated layer showing large-scale surface wear of silver 600 μm to 800 μm along the x-axis and +2 μm to −5 μm along the y-axis. FIG. 3 is a 3D profileometry diagram of the silver- plated layer, further demonstrating significant surface wear of the silver- plated layer after 100 cycles. Inspection of the balls showed material deposits and marked plow formation was observed at the end of the wear marks, indicating cold welding during the wear process. The coefficient of friction was determined to be about 1.6 throughout the experiment. The coefficient of friction was measured by a friction counting sensor that measures the coefficient of friction and then divides the coefficient of friction by the reported downward force to obtain the coefficient of friction.

Example 17 (Comparative Example)
Abrasion resistance measurements were performed on the electroplated silver-bismuth alloy plating layer using the bath described in Example 10 (comparison). The test was carried out for 500 cycles. The coefficient of friction was determined to be about 0.3 throughout the experiment. However, the observed wear traces were substantially the same as those observed in Example 16 above, which showed significant wear.

Example 18 (Comparative Example)
Abrasion resistance measurements were performed on the electroplated silver-bismuth alloy plating layer using the bath described in Example 11 (comparison). The test was carried out for 500 cycles. The coefficient of friction was determined to be about 0.7 throughout the experiment. However, the observed wear traces were substantially the same as those observed for silver metals in Example 16 above, which showed significant wear.

Example 19 (Comparative Example)
Abrasion resistance measurements were performed on the electroplated silver-bismuth alloy plating layer using the bath described in Example 12 (comparison). The test was carried out for 500 cycles. The coefficient of friction was determined to be about 0.7 throughout the experiment. However, the observed wear traces were substantially the same as those observed in Example 16 above, which showed significant wear.

Example 20 (invention)
Abrasion resistance measurements were carried out on the silver-bismuth alloy plating layer electroplated using the bath described in Example 2 (the present invention). The test was carried out for 500 cycles. FIG. 4 is a 2D profileometry diagram of a silver-bismuth alloy plated layer showing no observable wear of the silver-bismuth alloy along the width of the sample. FIG. 5 is a 3D profileometry diagram of a silver-bismuth alloy plated layer showing no further observable surface wear of the silver-bismuth alloy plated layer after 500 cycles. Inspection of the spherical ball showed no material deposition and no observable plow formation at the end of the wear mark, indicating that no cold welding occurred during the wear process. .. The coefficient of friction was determined to be about 0.6 throughout the experiment. These results showed a significant improvement over the comparative examples.

Example 21 (invention)
Abrasion resistance measurements were carried out on the electroplated silver-bismuth alloy plating layer using the bath described in Example 8 (the present invention). The test was carried out for 500 cycles. FIG. 6 is a 2D profileometry diagram of the silver- plated layer showing small wear of the silver-bismuth alloy along the width of the sample, but significantly lower than in the comparative examples. FIG. 7 is a 3D profileometry diagram of a silver-bismuth alloy plated layer further showing small wear of the silver-bismuth plated layer after 500 cycles. Inspection of the spherical balls showed no material deposition and no plow formation was observed at the end of the wear marks, indicating that no cold welding occurred during the wear process. The coefficient of friction was determined to be about 0.9 throughout the experiment. These results showed a significant improvement over the comparative examples.

Example 22 (invention)
Abrasion resistance measurements were carried out on the electroplated silver-bismuth alloy plating layer using the bath described in Example 10 (the present invention). The test was carried out for 500 cycles. FIG. 8 is a 2D profileometry diagram of the silver- plated layer showing minimal wear of the silver-bismuth alloy along the width of the sample. FIG. 9 is a 3D profileometry diagram of the silver-bismuth alloy plated layer further showing the slightest surface wear of the silver-bismuth plated layer after 500 cycles. Inspection of the spherical balls showed no material deposition and no plow formation was observed at the end of the wear marks, indicating that no cold welding occurred during the wear process. The coefficient of friction was determined to be about 0.5 throughout the experiment. These results showed a significant improvement over the comparative examples.

Claims (7)

(I) Silver ion source, (ii) Bismus ion source, (iii) Dihydroxybis-sulfide compound, or mixture of dihydroxybis-sulfide compound, wherein the dihydroxybis-sulfide compound is 2,4-dithia-1, 5-Pentanediol, 2,5-Dithia-1,6-hexanediol, 2,6-Dithia-1,7-Heptanediol, 2,7-Dithia-1,8-octanediol, 2,8-Dithia- 1,9-Nonandiol, 2,9-dithia-1,10-decanediol, 2,11-dithia-1,12-dodecanediol, 5,8-dithia-1,12-dodecanediol, 2,15- Dithia-1,16-hexadecanediol, 2,21-dithia-1,2-dodecanediol, 3,5-dithia-1,7-heptanediol, 3,6-dithia-1,8-octanediol, 3,8-Dithia-1,10-decanediol, 3,10-dithia-1,8-dodecanediol, 3,13-dithia-1,15-pentadecanediol, 3,18-dithia-1,20-eiko Sandiol, 4,6-dithia-1,9-nonanediol, 4,7-dithia-1,10-decanediol, 4,11-dithia-1,14-tetradecanediol, 4,15-dithia-1, 18-Octadecanediol, 4,19-dithia-1,2-dodecanediol, 5,7-dithia-1,11-undecanediol, 5,9-dithia-1,13-tridecanediol, 5,13 -Selected from the group consisting of 1,17-heptadecanediol, 5,17-dithia-1,21-uneicosandiol, and 1,8-dimethyl-3,6-dithia-1,8-octanediol. A two-component silver-bismuth alloy electroplating composition comprising a 5-membered aromatic heterocyclic nitrogen compound having the following general formula (iv) .

In the formula, _Q1 to _Q4 may be substituted or unsubstituted nitrogen, or substituted or unsubstituted carbon, except that at least two of _Q1 to _Q4 are nitrogen, and the substituent is (C). ₁ to C ₄ ) Alkyl, amino group, aminoalkyl group, carboxyl, carboxy (C ₁ to C ₄ ) alkyl, or alkyl sulfonate , pH is less than 7, two-component silver-bismuth alloy electroplating composition. thing. The 5-membered aromatic heterocyclic nitrogen compound is 3-mercapto-1,2,4-triazole, 3-amino-1,2,4-triazole-5-thiol, 3-amino-5-mercapto-. 1,2,4-triazole, 3-mercapto-4-methyl-4H-1,2,4-triazole, 1H-imidazole-2-thiol, the salt of the 5-membered aromatic heterocyclic nitrogen compound, and The two-component silver-bismuth alloy electroplating composition according to claim 1, which is selected from the group consisting of these mixtures. The two-component silver-bismuth alloy electroplating composition according to claim 1, further comprising an aliphatic thiol-terminated compound or a mixture thereof. The aliphatic thiol-terminated compounds include thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, cysteine, mercaptosuccinic acid, 3-mercapto-1-propanesulfonic acid, 2-mercaptoethanesulfonic acid, and the aliphatic. The two-component silver-bismuth alloy electroplating composition according to claim 3 , which is selected from the group consisting of salts of thiol-terminated compounds and mixtures thereof. It is a method of electroplating a two-component silver-bismuth alloy on a base material.
a) Providing the base material and
b) The substrate is a mixture of (i) silver ion source, (ii) bismuth ion source, (iii) dihydroxybis-sulfide compound, or dihydroxybis-sulfide compound, wherein the dihydroxybis-sulfide compound is 2. , 4-Dithia-1,5-pentanediol, 2,5-Dithia-1,6-hexanediol, 2,6-Dithia-1,7-Heptanediol, 2,7-Dithia-1,8-octanediol 2,8-Dithia-1,9-nonandiol, 2,9-Dithia-1,10-decanediol, 2,11-dithia-1,12-dodecanediol, 5,8-dithia-1,12- Dodecanediol, 2,15-dithia-1,16-hexadecanediol, 2,21-dithia-1,2-dodecanediol, 3,5-dithia-1,7-heptanediol, 3,6-dithia- 1,8-octanediol, 3,8-dithia-1,10-decanediol, 3,10-dithia-1,8-dodecanediol, 3,13-dithia-1,15-pentadecanediol, 3,18- Dithia-1,20-eicosandiol, 4,6-dithia-1,9-nonanediol, 4,7-dithia-1,10-decanediol, 4,11-dithia-1,14-tetradecanediol, 4 , 15-Dithia-1,18-octadecanediol, 4,19-Dithia-1,2-dodecanediol, 5,7-Dithia-1,11-undecanediol, 5,9-Dithia-1,13- Tridecanediol, 5,13-dithia-1,17-heptadecanediol, 5,17-dithia-1,21-uneicosandiol, and 1,8-dimethyl-3,6-dithia-1,8- By contacting with a two-component silver-bismuth alloy electroplating composition selected from the group consisting of dodecane diols and comprising (iv) a 5-membered aromatic heterocyclic nitrogen compound having the following general formula: ,

In the formula, _Q1 to _Q4 may be substituted or unsubstituted nitrogen, or substituted or unsubstituted carbon, except that at least two of _Q1 to _Q4 are nitrogen, and the substituent is (C). ₁ to C ₄ ) Alkyl, amino group, aminoalkyl group, carboxyl, carboxy (C ₁ to C ₄ ) alkyl, or alkyl sulfonate can be mentioned , and the pH is less than 7.
c) A method comprising applying an electric current to the two-component silver-bismas alloy electroplating composition and a substrate to electroplat the two-component silver-bismas plating layer on the substrate. The 5-membered aromatic heterocyclic nitrogen compound is 3-mercapto-1,2,4-triazole, 3-amino-1,2,4-triazole-5-thiol, 3-amino-5-mercapto-. 1,2,4-triazole, 3-mercapto-4-methyl-4H-1,2,4-triazole, 1H-imidazole-2-thiol, the salt of the 5-membered aromatic heterocyclic nitrogen compound, and The method of claim 5 , selected from the group consisting of these mixtures. The method of claim 5 , wherein the two-component silver-bismuth alloy electroplating composition further comprises an aliphatic thiol-terminated compound or a mixture thereof.

Images