Composition and method for electro-deposition of tin-bismuth alloy to metal substrate

Abstract

To provide a method for depositing a tin-bismuth alloy on a substrate.SOLUTION: A method includes: a step (1) in which a substrate and an anode are immersed in an electrolyte solution containing water, a tin salt, and at least one of a sulfuric acid and a sulfamic acid, whereas the anode includes tin and optional bismuth; and a step (2) in which a deposit is formed on the substrate by applying an electric current to between the substrate and the anode.SELECTED DRAWING: None

Description

Technical Field

[0001] The present application relates to depositing materials on a substrate, and more particularly, to compositions and methods for activating a metal substrate, and compositions and methods for electrodepositing a tin-bismuth alloy on a metal substrate.

[0002] Mechanical fasteners are widely used to join two or more components of a structural assembly. For example, mechanical fasteners are widely used to join the structural components of an aircraft fuselage.

[0003] Aircraft are subject to electromagnetic effects (EME) due to various factors such as lightning strikes and precipitation static electricity. Since metallic aircraft structures are directly conductive, they are relatively insensitive to electromagnetic effects. However, aircraft structures made of composite materials (such as carbon fiber reinforced plastics) do not immediately dissipate significant currents and electromagnetic forces resulting from electromagnetic effects. Therefore, when using mechanical fasteners in composite aircraft structures, it is necessary to take measures to protect against electromagnetic effects.

[0004] Protection from electromagnetic effects can be provided to mechanical fasteners in the form of a conductive metal surface deposit (such as a metal plating). While various metal surface deposits can provide appropriate conductivity to impart protection from electromagnetic effects, other factors such as lubricity and galvanic compatibility with carbon fiber reinforced plastics are also considered for mechanical fasteners intended for the aerospace industry.

[0005] Tin exists in the α-phase and β-phase. α-tin is gray in color, powdery, and forms a pest, while β-tin is white and has a tetragonal crystal structure. When tin is alloyed with bismuth at a concentration above 0.4 weight percent bismuth, the tin begins to exist as the β-phase. Tin-bismuth has been found to be promising as a metal surface deposit suitable for mechanical fasteners due to its conductivity, lubricity, and galvanic compatibility with carbon fiber reinforced plastics.

[0006] The embodiments include the following:

[0007] An electrolyte solution containing water, a tin salt, a bismuth salt, and an acid.

[0008] An electrolyte solution containing water, at least one of tin sulfate, tin chloride, and tin fluoride dissolved in water, at least one of bismuth sulfate, bismuth oxide, bismuth nitrate, bismuth chloride, and bismuth trifluoride dissolved in water, and at least one of sulfuric acid and sulfamic acid dissolved in water.

[0009] An electrolyte solution containing water, tin sulfate, bismuth sulfate, and sulfuric acid.

[0010] An electrolyte solution containing water, at least one of tin sulfate, tin chloride, and tin fluoride dissolved in water at a concentration of about 15 grams per liter to about 200 grams per liter based on the total volume of the electrolyte solution, at least one of bismuth sulfate, bismuth oxide, bismuth nitrate, bismuth chloride, and bismuth trifluoride dissolved in water at a concentration of about 0.25 grams per liter to about 10 grams per liter based on the total volume of the electrolyte solution, and at least one of sulfuric acid and sulfamic acid dissolved in water at a concentration of about 50 milliliters per liter to about 150 milliliters per liter based on the total volume of the electrolyte solution.

[0011] A method for producing an electrolyte solution, comprising: (1) A step of mixing at least one of sulfuric acid and sulfamic acid with water to obtain an acidic solution; (2) A step of dissolving a tin salt in the acidic solution; and (3) A step of dissolving a bismuth salt in the acidic solution. The method includes the above steps.

[0012] An electroplating system, comprising: A current source having a first terminal and a second terminal; A bath containing an electrolyte solution, the electrolyte solution being a bath containing water, a tin salt, a bismuth salt, and an acid, A substrate immersed in the electrolyte solution, the substrate being electrically connected to a first terminal of a current source, and An anode containing tin, the anode being immersed in the electrolyte solution and being electrically connected to a second terminal of a current source, A electroplating system comprising the above.

[0013] A method for depositing a tin-bismuth alloy on a substrate, (1) A step of immersing a substrate and an anode containing tin in an electrolyte solution containing water, a tin salt, a bismuth salt, and an acid, and (2) A step of forming a deposit on the substrate by passing an electric current between the substrate and the anode.

[0014] A method for depositing a tin-bismuth alloy on a substrate, (1) A step of activating the substrate, (2) A step of strike plating the substrate, (3) A step of immersing a substrate and an anode containing tin in an electrolyte solution containing water, a tin salt, a bismuth salt, and an acid, and (4) A step of forming a deposit on the substrate by passing an electric current between the substrate and the anode.

[0015] Other aspects of the disclosed compositions and methods for electrodepositing a tin-bismuth alloy onto a metal substrate will become apparent from the following detailed description, the accompanying drawings, and the appended claims.

Brief Description of the Drawings

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[0017] Disclosed herein are compositions, systems, and methods for activating a metal substrate (e.g., a metal fastener or other member / component), as well as compositions, systems, and methods for depositing a material on a metal substrate (e.g., a metal fastener or other member / component). The compositions, systems, and methods disclosed herein can be used separately or in various combinations to achieve a desired material deposit on a substrate.

[0018] Referring to FIG. 1, a method (generally indicated at 10) for depositing a material on a substrate is disclosed. Although only three general steps are shown, those skilled in the art will understand that various additional steps can be performed before, after, or during the steps presented herein, provided that the scope of the present disclosure is not departed from.

[0019] The first step (block 12) of method 10 includes pretreating the substrate to make it a substrate suitable for receiving a material (such as a metal deposit, or other metal / non-metal material) on the substrate. Various pretreatments (such as cleaning, degreasing, etching, etc.) can be performed. In particular, the pretreatment step (block 12) may include activation of the substrate surface (block 14). For example, in the case of a titanium substrate, in the step of activating the substrate surface (block 14), the strong oxide layer known to be formed on the substrate can be removed (or at least substantially reduced).

[0020] The intermediate step (block 16) of method 10 includes strike plating the pretreated substrate. By the step of strike plating the substrate surface (block 16), a thin metal layer can be formed on the substrate surface, whereby the substrate becomes one with a more suitable surface for receiving and bonding to a subsequent metal deposit. In a particular implementation, in the strike plating step (block 16), a thin nickel layer can be formed on the substrate surface.

[0021] The final step (block 18) of method 10 includes electrodepositing on the strike plated substrate. In the electrodeposition step (block 18), a metal deposit can be formed on the substrate surface. In a particular implementation, in the electrodeposition step (block 18), a tin-bismuth alloy can be deposited on the substrate surface.

[0022] Referring to FIG. 2, the disclosed method 10 was used to deposit a thin layer of a tin-bismuth alloy onto the surface of a titanium alloy (Ti-6Al-4V) substrate. As a result, an excellent bond was achieved between the tin-bismuth alloy deposit and the underlying titanium alloy substrate.

[0023] Although this disclosure mainly focuses on titanium substrates (substrates formed from titanium or titanium alloys, such as Ti-6Al-4V), the disclosed method 10 and each step of the disclosed method 10 (e.g., the activation step (block 14), the strike plating step (block 16), and / or the electroplating step (block 18)) may also be suitable for non-titanium substrates. Examples of non-titanium substrates that can benefit from this disclosure include, but are not limited to, iron alloys, copper alloys, and nickel alloys (such as Inconel).

[0024] Activation Three activation methods are disclosed, including related compositions and systems. A metal substrate, such as a titanium substrate, can be activated using only one of the disclosed activation methods. Alternatively, a metal substrate, such as a titanium substrate, can be activated using multiple activation methods (e.g., a series of activation methods), which may include one or more of the disclosed activation methods.

[0025] Referring to FIGS. 3 and 4, a first activation method, generally indicated at 100, may begin at block 110 (FIG. 3) and includes the step of preparing a bath 152 containing an activation solution 154, as shown in FIG. 4. The bath 152 and the activation solution 154 can comprise a first activation system 150.

[0026] The bath 152 can be any container suitable for receiving and containing the activation solution 154. In terms of composition, the material forming the bath 152 must be chemically compatible with the activation solution 154. Of course, the bath 152 must be of a size and shape that can receive the substrate 156 to be activated by the first activation system 150 within the bath.

[0027] The activation solution 154 contains water (H2O), an ammonium salt dissolved in water, and sulfuric acid (H2SO4) dissolved in water. The activation solution 154 can be maintained at atmospheric pressure (e.g., 1 atm) and at about 15°C to about 50°C (e.g., room temperature (about 21°C)). However, using higher and lower pressures, as well as higher and lower temperatures, are also conceivable as long as it does not deviate from the scope of the present disclosure.

[0028] The ammonium salt in the activation solution 154 can have a fluorine-containing anion. In one preparation, the ammonium salt in the activation solution 154 is ammonium bifluoride (NH4HF2). In another preparation, the ammonium salt in the activation solution 154 is ammonium tetrafluoroborate (NH4BF4). In yet another preparation, the ammonium salt in the activation solution 154 contains both ammonium bifluoride (NH4HF2) and ammonium tetrafluoroborate (NH4BF4).

[0029] The ammonium salt in the activation solution 154 may be present at a concentration in the range of about 10 grams per liter to about 150 grams per liter based on the total volume of the activation solution 154. In one alternative expression, the concentration of the ammonium salt is in the range of about 20 grams per liter to about 120 grams per liter based on the total volume of the activation solution 154. In another alternative expression, the concentration of the ammonium salt is in the range of about 30 grams per liter to about 110 grams per liter based on the total volume of the activation solution 154. In another alternative expression, the concentration of the ammonium salt is in the range of about 40 grams per liter to about 100 grams per liter based on the total volume of the activation solution 154. In another alternative expression, the concentration of the ammonium salt is in the range of about 50 grams per liter to about 100 grams per liter based on the total volume of the activation solution 154. In another alternative expression, the concentration of the ammonium salt is in the range of about 60 grams per liter to about 100 grams per liter based on the total volume of the activation solution 154. In another alternative expression, the concentration of the ammonium salt is in the range of about 70 grams per liter to about 90 grams per liter based on the total volume of the activation solution 154. In a further alternative expression, the concentration of the ammonium salt is about 80 grams per liter based on the total volume of the activation solution 154.

[0030] Sulfuric acid in the activation solution 154 may be present at a concentration in the range of about 1 volume percent to about 70 volume percent, based on the total volume of the activation solution 154. In one alternative expression, the concentration of sulfuric acid is in the range of about 2 volume percent to about 50 volume percent, based on the total volume of the activation solution 154. In another alternative expression, the concentration of sulfuric acid is in the range of about 3 volume percent to about 40 volume percent, based on the total volume of the activation solution 154. In another alternative expression, the concentration of sulfuric acid is in the range of about 4 volume percent to about 30 volume percent, based on the total volume of the activation solution 154. In another alternative expression, the concentration of sulfuric acid is in the range of about 5 volume percent to about 25 volume percent, based on the total volume of the activation solution 154. In another alternative expression, the concentration of sulfuric acid is in the range of about 5 volume percent to about 15 volume percent, based on the total volume of the activation solution 154. In a further alternative expression, the concentration of sulfuric acid is about 10 volume percent, based on the total volume of the activation solution 154.

[0031] In one specific, non-limiting example, the activation solution 154 contains water, 80 grams of ammonium bifluoride (NH4HF2) per liter, and 10 volume percent sulfuric acid (H2SO4).

[0032] The activation solution 154 can be manufactured in various ways, as long as it does not depart from the scope of the present disclosure. In one specific implementation, the disclosed method for manufacturing the activation solution 154 includes the following steps: (1) A step of mixing sulfuric acid (e.g., sulfuric acid at 66 degrees Baume) and water (e.g., deionized water) to obtain an acidic solution, (2) A step of dissolving an ammonium salt (e.g., ammonium bifluoride and / or ammonium tetrafluoroborate) in the acidic solution, and (3) A step of adding additional water, if necessary, to make the activation solution 154 the required total volume.

[0033] In block 120 (Figure 3), the substrate 156 is immersed (e.g., completely immersed) in the activation solution 154. The substrate 156 may be left immersed in the activation solution 154 for a predetermined time as shown in block 130 (Figure 3) before removing the substrate 156 from the activation solution 154. In the case of a titanium substrate (substrate 156), the predetermined time can be selected such that the activation solution 154 has sufficient time to reduce / eliminate a strong oxide layer on the substrate 156 without significantly damaging the oxide layer underlying the titanium / titanium alloy. In one representation, the predetermined time is from about 5 seconds to about 120 seconds. In another representation, the predetermined time is from about 10 seconds to about 100 seconds. In another representation, the predetermined time is from about 20 seconds to about 40 seconds. In yet another representation, the predetermined time is about 30 seconds.

[0034] In block 140 (Figure 3), the substrate 156 removed from the activation solution 154 can be rinsed with a rinsing fluid. As one example, the rinsing fluid can be water, such as deionized water.

[0035] Referring to FIGS. 5 and 6, a second activation method (generally indicated at 200) may begin at block 202 (Figure 5) and includes the step of preparing a bath 252 containing an activation solution 254 as shown in FIG. 6. The bath 252 and the activation solution 254 can comprise a second activation system 250.

[0036] The bath 252 can be any container suitable for receiving and containing the activation solution 254. In terms of composition, the material forming the bath 252 must be chemically compatible with the activation solution 254. Of course, the bath 252 must be of a size and shape capable of receiving the substrate 256 to be activated by the second activation system 250 therein.

[0037] The activation solution 254 contains water (H2O), a fluoride salt dissolved in water, hydrofluoric acid (HF) dissolved in water, and sulfuric acid (H2SO4) dissolved in water. The activation solution 254 can be maintained at atmospheric pressure (e.g., 1 atm) and at about 15°C to about 50°C (e.g., room temperature (about 21°C)). However, higher and lower pressures, as well as higher and lower temperatures, can also be considered as long as they do not deviate from the scope of the present disclosure.

[0038] The fluoride salt in the activation solution 254 can have an alkali metal cation and / or an alkaline earth metal cation. In one preparation, the fluoride salt in the activation solution 254 is potassium fluoride (KF). In another preparation, the fluoride salt in the activation solution 254 is lithium fluoride (LiF). In another preparation, the fluoride salt in the activation solution 254 is sodium fluoride (NaF). In another preparation, the fluoride salt in the activation solution 254 is rubidium fluoride (RuF). In another preparation, the fluoride salt in the activation solution 254 is barium fluoride (BaF2). In another preparation, the fluoride salt in the activation solution 254 is strontium fluoride (SrF2). In yet another preparation, the ammonium salt in the activation solution 254 contains at least two of potassium fluoride (KF), lithium fluoride (LiF), sodium fluoride (NaF), rubidium fluoride (RuF), barium fluoride (BaF2), and strontium fluoride (SrF2).

[0039] The fluoride salt in the activation solution 254 may be present at a concentration in the range of about 5 grams per liter to about 120 grams per liter, based on the total volume of the activation solution 254. In one alternative expression, the concentration of the fluoride salt is in the range of about 10 grams per liter to about 100 grams per liter, based on the total volume of the activation solution 254. In another alternative expression, the concentration of the fluoride salt is in the range of about 15 grams per liter to about 75 grams per liter, based on the total volume of the activation solution 254. In another alternative expression, the concentration of the fluoride salt is in the range of about 15 grams per liter to about 50 grams per liter, based on the total volume of the activation solution 254. In another alternative expression, the concentration of the fluoride salt is in the range of about 15 grams per liter to about 30 grams per liter, based on the total volume of the activation solution 254. In a further alternative expression, the concentration of the fluoride salt is about 20 grams per liter, based on the total volume of the activation solution 254.

[0040] Hydrofluoric acid in the activation solution 254 may be present at a concentration in the range of about 5 milliliters per liter to about 250 milliliters per liter, based on the total volume of the activation solution 254. In one alternative expression, the concentration of hydrofluoric acid is in the range of about 10 milliliters per liter to about 200 milliliters per liter, based on the total volume of the activation solution 254. In another alternative expression, the concentration of hydrofluoric acid is in the range of about 15 milliliters per liter to about 150 milliliters per liter, based on the total volume of the activation solution 254. In another alternative expression, the concentration of hydrofluoric acid is in the range of about 20 milliliters per liter to about 150 milliliters per liter, based on the total volume of the activation solution 254. In another alternative expression, the concentration of hydrofluoric acid is in the range of about 30 milliliters per liter to about 100 milliliters per liter, based on the total volume of the activation solution 254. In another alternative expression, the concentration of hydrofluoric acid is in the range of about 40 milliliters per liter to about 80 milliliters per liter, based on the total volume of the activation solution 254. In a further alternative expression, the concentration of hydrofluoric acid is about 60 milliliters per liter, based on the total volume of the activation solution 254.

[0041] Sulfuric acid in the activation solution 254 may be present at a concentration in the range of about 1 volume percent to about 45 volume percent, based on the total volume of the activation solution 254. In one alternative expression, the concentration of sulfuric acid is in the range of about 2 volume percent to about 35 volume percent, based on the total volume of the activation solution 254. In another alternative expression, the concentration of sulfuric acid is in the range of about 2 volume percent to about 20 volume percent, based on the total volume of the activation solution 254. In another alternative expression, the concentration of sulfuric acid is in the range of about 3 volume percent to about 15 volume percent, based on the total volume of the activation solution 254. In another alternative expression, the concentration of sulfuric acid is in the range of about 3 volume percent to about 10 volume percent, based on the total volume of the activation solution 254. In a further alternative expression, the concentration of sulfuric acid is about 5 volume percent, based on the total volume of the activation solution 254.

[0042] In one specific, non-limiting example, the activation solution 254 includes water, 20 grams of potassium fluoride (KF) per liter, 60 milliliters of hydrofluoric acid (HF) per liter, and 5 volume percent sulfuric acid (H2SO4).

[0043] The activation solution 254 can be manufactured in various ways without departing from the scope of the present disclosure. In one specific implementation, the disclosed method for manufacturing the activation solution 254 includes the following steps: (1) Mixing sulfuric acid (e.g., sulfuric acid at 66 degrees Baume) and water (e.g., deionized water) to obtain a first acidic solution; (2) Mixing hydrofluoric acid (e.g., 48 wt% in water) and the first acidic solution to obtain a second acidic solution; (3) Dissolving a fluoride salt (e.g., potassium fluoride) in the second acidic solution; and (4) Adding additional water if necessary to bring the activation solution 254 to the required total volume.

[0044] In block 204 (Figure 5), the substrate 256 is immersed (e.g., completely immersed) in the activation solution 254. The substrate 256 may be left immersed in the activation solution 254 for a predetermined time as shown in block 206 (Figure 5) before removing the substrate 256 from the activation solution 254. In the case of a titanium substrate (substrate 256), the predetermined time can be selected such that the activation solution 254 has sufficient time to reduce / eliminate a strong oxide layer on the substrate 256 without significantly damaging the oxide layer underlying the titanium / titanium alloy. In one expression, the predetermined time is from about 5 seconds to about 120 seconds. In another expression, the predetermined time is from about 10 seconds to about 100 seconds. In another expression, the predetermined time is from about 20 seconds to about 40 seconds. In yet another expression, the predetermined time is about 30 seconds.

[0045] In block 208 (FIG. 5), the substrate 256 taken out from the activation solution 254 can be rinsed with a rinsing fluid. As one example, the rinsing fluid can be water, such as deionized water.

[0046] Referring to FIGS. 7 and 8, a third activation method (generally denoted 300) may begin at block 302 (FIG. 7) and includes the step of preparing a bath 352 containing an activation solution 354, as shown in FIG. 8. The bath 352 and the activation solution 354 can comprise a third activation system 350 together with a graphite electrode 358 and a current source 360, which can be used to perform an anodic sulfuric acid method (the third activation method 300) as described herein.

[0047] The bath 352 can be any container suitable for receiving and containing the activation solution 354. In terms of composition, the material forming the bath 352 must be chemically compatible with the activation solution 354. Of course, the bath 352 must be of a size and shape capable of receiving in the bath the graphite electrode 358 and the substrate 356 to be activated by the third activation system 350.

[0048] The activation solution 354 contains water (H2O) and sulfuric acid (H2SO4) dissolved in the water. The activation solution 354 can be maintained at atmospheric pressure (e.g., 1 atm) and at about 15°C to about 50°C (e.g., room temperature (about 21°C)). However, higher and lower pressures, as well as higher and lower temperatures, can also be considered without departing from the scope of the present disclosure.

[0049] Sulfuric acid in the activation solution 354 may be present at a concentration in the range of about 5 volume percent to about 45 volume percent, based on the total volume of the activation solution 354. In one alternative expression, the concentration of sulfuric acid is in the range of about 5 volume percent to about 35 volume percent, based on the total volume of the activation solution 354. In another alternative expression, the concentration of sulfuric acid is in the range of about 5 volume percent to about 30 volume percent, based on the total volume of the activation solution 354. In another alternative expression, the concentration of sulfuric acid is in the range of about 5 volume percent to about 25 volume percent, based on the total volume of the activation solution 354. In another alternative expression, the concentration of sulfuric acid is in the range of about 10 volume percent to about 20 volume percent, based on the total volume of the activation solution 254. In a further alternative expression, the concentration of sulfuric acid is about 15 volume percent, based on the total volume of the activation solution 354.

[0050] In one specific, non-limiting example, the activation solution 354 comprises water and 15 volume percent sulfuric acid (H2SO4).

[0051] In block 304 (FIG. 7), the substrate 356 is immersed (e.g., completely immersed) in the activation solution 354. The conductor 368 can electrically connect the immersed substrate 356 and the first terminal 364 of the current source 360.

[0052] In block 306 (FIG. 7), the graphite electrode 358 is immersed (e.g., completely immersed) in the activation solution 354. The conductor 366 can electrically connect the immersed graphite electrode 358 and the second terminal 362 of the current source 360.

[0053] In block 308 (FIG. 7), the current source 360 is operated so that current passes between the substrate 356 and the graphite electrode 358. The current source 360 may be configured such that the substrate 356 is etched by acting as an anode. In the case of a titanium substrate (substrate 356), the anodic sulfuric acid method (the third activation method 300) can reduce / eliminate a strong oxide layer on the substrate 356 without significantly damaging the oxide layer under the titanium / titanium alloy.

[0054] The step of passing an electric current (block 308) can be performed at various current densities, provided that it does not depart from the scope of the present disclosure. One of ordinary skill in the art will positively evaluate that the current density is a controllable parameter, and in order to select an appropriate current density, various factors (among other factors, for example, the duration of the step of passing an electric current (block 308)) need to be considered. In one expression, the electric current passed during the step of passing an electric current (block 308) can have a current density ranging from about 10 amperes per square foot to about 80 amperes per square foot based on the surface area of the substrate 356. In another expression, the electric current passed during the step of passing an electric current (block 308) can have a current density ranging from about 20 amperes per square foot to about 60 amperes per square foot based on the surface area of the substrate 356. In another expression, the electric current passed during the step of passing an electric current (block 308) can have a current density ranging from about 20 amperes per square foot to about 40 amperes per square foot based on the surface area of the substrate 356. In yet another expression, the electric current passed during the step of passing an electric current (block 308) can have a current density of about 30 amperes per square foot based on the surface area of the substrate 356.

[0055] The step of passing an electric current (block 308) can be performed for various durations without departing from the scope of the present disclosure. One skilled in the art will positively evaluate that the current density is a controllable parameter and that various factors (such as, among other factors, the current density) need to be considered in order to select an appropriate duration. In one expression, the step of passing an electric current (block 308) can be performed over a period of about 5 seconds to about 120 seconds. In another expression, the step of passing an electric current (block 308) can be performed over a period of about 10 seconds to about 100 seconds. In another expression, the step of passing an electric current (block 308) can be performed over a period of about 10 seconds to about 60 seconds. In another expression, the step of passing an electric current (block 308) can be performed over a period of about 15 seconds to about 45 seconds. In yet another expression, the step of passing an electric current (block 308) can be performed over a period of about 20 seconds to about 30 seconds.

[0056] In block 310 (FIG. 7), the substrate 356 is disconnected from the current source 360 and removed from the activation solution 354.

[0057] In block 312 (FIG. 7), the substrate 356 can be rinsed with a rinsing fluid. As one example, the rinsing fluid can be water, such as deionized water.

[0058] Strike plating Various strike plating processes (including nickel strike plating processes: e.g., Wood's bath nickel strike) are known in the art and can be used in the method 10 of FIG. 1 without departing from the scope of the present disclosure. However, a specific nickel strike plating method is disclosed, and this method has provided excellent bonding with the substrate by subsequent plating (see FIG. 2).

[0059] Referring to FIG. 9, a strike plating system (generally denoted 450) includes a bath 452, an electrolyte solution 454 received in the bath 452, a nickel anode 458 immersed in the electrolyte solution 454, and a current source 460. The current source 460 can include a first terminal 462 and a second terminal 464. The nickel anode 458 may be electrically connected to the second terminal 464 by a conducting wire 468.

[0060] The bath 452 can be any container suitable for receiving and containing the electrolyte solution 454. In terms of composition, the material forming the bath 452 must be chemically compatible with the electrolyte solution 454. Of course, the bath 452 must be of a size and shape capable of receiving the substrate 456 and the nickel anode 458 therein.

[0061] The electrolyte solution 454 contains water (H2O), nickel chloride (NiCl2) dissolved in water, and hydrochloric acid (HCl) dissolved in water. The electrolyte solution 454 can be maintained at atmospheric pressure (e.g., 1 atm) and at a temperature of about 15°C to about 50°C (e.g., room temperature (about 21°C)). However, higher and lower pressures, as well as higher and lower temperatures, can also be considered without departing from the scope of the present disclosure.

[0062] Nickel chloride in the electrolyte solution 454 may be present at a concentration in the range of about 50 grams per liter to about 400 grams per liter based on the total volume of the activation solution 354. In one alternative expression, the concentration of nickel chloride is in the range of about 75 grams per liter to about 350 grams per liter based on the total volume of the activation solution 354. In another alternative expression, the concentration of nickel chloride is in the range of about 100 grams per liter to about 300 grams per liter based on the total volume of the activation solution 354. In another alternative expression, the concentration of nickel chloride is in the range of about 125 grams per liter to about 275 grams per liter based on the total volume of the activation solution 354. In another alternative expression, the concentration of nickel chloride is in the range of about 150 grams per liter to about 250 grams per liter based on the total volume of the activation solution 354. In another alternative expression, the concentration of nickel chloride is in the range of about 175 grams per liter to about 225 grams per liter based on the total volume of the activation solution 354.

[0063] Hydrochloric acid in the electrolyte solution 454 may be present at a concentration in the range of about 25 milliliters per liter to about 300 milliliters per liter based on the total volume of the electrolyte solution 454. In one alternative expression, the concentration of hydrochloric acid is in the range of about 50 milliliters per liter to about 250 milliliters per liter based on the total volume of the electrolyte solution 454. In another alternative expression, the concentration of hydrochloric acid is in the range of about 75 milliliters per liter to about 225 milliliters per liter based on the total volume of the electrolyte solution 454. In another alternative expression, the concentration of hydrochloric acid is in the range of about 100 milliliters per liter to about 200 milliliters per liter based on the total volume of the electrolyte solution 454. In another alternative expression, the concentration of hydrochloric acid is in the range of about 125 milliliters per liter to about 175 milliliters per liter based on the total volume of the electrolyte solution 454.

[0064] In one specific, non-limiting example, the electrolyte solution 454 includes water, 200 grams of nickel chloride (NiCl2) per liter, and 150 milliliters of hydrochloric acid (HCl) per liter.

[0065] As shown in FIG. 9, the substrate 456 is immersed (e.g., completely immersed) in the electrolyte solution 454 in the bath 452. The substrate 456 is electrically connected to the first terminal 462 of the current source 460 by a conducting wire 466.

[0066] To initiate the strike plating, the current source 460 is activated so that current passes between the substrate 456 and the nickel anode 458 and a deposit is formed on the substrate 456. Optionally, an anodic strike (where the substrate 456 acts as the anode) can be performed to etch the substrate 456 before starting the cathodic strike.

[0067] The anodic strike (etching) can be performed at various current densities and durations without departing from the scope of the present disclosure. In one representation, the anodic strike can be performed at a current density in the range of about 25 amperes per square foot to about 75 amperes per square foot, based on the surface area of the substrate 456, for a duration of about 1 second to about 30 seconds. For example, the anodic strike can be performed at a current density of about 120 amperes per square foot, based on the surface area of the substrate 456, for about 10 seconds.

[0068] The cathodic strike (strike plating) can be performed at various current densities and durations without departing from the scope of the present disclosure. In one representation, the cathodic strike can be performed at a current density in the range of about 80 amperes per square foot to about 160 amperes per square foot, based on the surface area of the substrate 456, for a duration of about 30 seconds to about 10 minutes. For example, the cathodic strike can be performed at a current density of about 120 amperes per square foot, based on the surface area of the substrate 456, for about 5 minutes.

[0069] Once the current source 460 stops operating, the substrate 456 can be disconnected from the current source 460 and removed from the electrolyte solution 454. Then, the substrate 356 can be rinsed with a rinsing fluid (e.g., deionized water).

[0070] Electroplating Various electroplating processes can be used in the method 10 of FIG. 1 without departing from the scope of the present disclosure. However, a specific tin-bismuth electroplating method is disclosed, and this method, when used following any of the activation methods according to the present disclosure and the disclosed nickel strike plating method, results in excellent bonding to the substrate by subsequent plating (see FIG. 2).

[0071] Referring to FIGS. 10 and 11, the disclosed electroplating method (generally indicated at 500) can begin at block 502 (FIG. 10) and includes the step of preparing a bath 552 containing an electrolyte solution 554 as shown in FIG. 11. The bath 552 and the activation solution 554 can be provided with the disclosed electroplating system 550 together with an anode 558 and a current source 560, and this electroplating system can be used to deposit a tin-bismuth alloy on the substrate 556.

[0072] The substrate 556 can be a titanium substrate, such as a titanium mechanical fastener. Other metal substrates 556 (e.g., iron substrates, copper substrates, and nickel substrates (e.g., Inconel)) can also be used by the disclosed electroplating method 500 and system 550 without departing from the scope of the present disclosure.

[0073] The anode 558 of the disclosed electroplating system 550 can be a tin anode (e.g., 99.99 percent pure tin), or a tin-bismuth anode. As one general example, the anode 558 can contain from about 2 weight percent to about 5 weight percent bismuth, with the balance being substantially tin. As one specific example, the anode 558 can contain about 3 weight percent bismuth, with the balance being substantially tin.

[0074] The bath 552 can be any container suitable for receiving and containing the electrolyte solution 554. In terms of composition, the material forming the bath 552 must be chemically compatible with the activation solution 554. Of course, the bath 552 must be of a size and shape capable of receiving the anode 558 and the substrate 556 therein.

[0075] The electrolyte solution 554 contains water (H2O), a tin salt dissolved in water, a bismuth salt dissolved in water, and an acid. The electrolyte solution 554 can be maintained at atmospheric pressure (e.g., 1 atm) and at about 15°C to about 50°C (e.g., room temperature (about 21°C)). However, higher and lower pressures, as well as higher and lower temperatures, can also be considered without departing from the scope of the present disclosure.

[0076] The tin salt in the electrolyte solution 554 supplies tin (tin (II) 2+ ) ions. In one preparation, the tin salt in the electrolyte solution 554 is tin sulfate (SnSO4). In another preparation, the tin salt in the electrolyte solution 554 is tin chloride (SnCl2). In another preparation, the tin salt in the electrolyte solution 554 is tin fluoride (SnF2). In yet another preparation, the tin salt in the electrolyte solution 554 includes at least two of tin sulfate (SnSO4), tin chloride (SnCl2), and tin fluoride (SnF2).

[0077] The tin salt in the electrolyte solution 554 may be present at a concentration of about 15 grams per liter to about 200 grams per liter, based on the total volume of the activation solution 554. In one alternative expression, the concentration of the tin salt is in the range of about 15 grams per liter to about 150 grams per liter, based on the total volume of the electrolyte solution 554. In another alternative expression, the concentration of the tin salt is in the range of about 15 grams per liter to about 100 grams per liter, based on the total volume of the electrolyte solution 554. In another alternative expression, the concentration of the tin salt is in the range of about 20 grams per liter to about 100 grams per liter, based on the total volume of the electrolyte solution 554. In another alternative expression, the concentration of the tin salt is in the range of about 20 grams per liter to about 50 grams per liter, based on the total volume of the electrolyte solution 554. In yet another alternative expression, the concentration of the tin salt is in the range of about 25 grams per liter to about 35 grams per liter, based on the total volume of the electrolyte solution 554.

[0078] The bismuth salt in the electrolyte solution 554 supplies bismuth (Bi 3+ ) ions. In one preparation, the bismuth salt in the electrolyte solution 554 is bismuth sulfate (Bi2(SO4)3). In another preparation, the bismuth salt in the electrolyte solution 554 is bismuth oxide (Bi2O3). In another preparation, the bismuth salt in the electrolyte solution 554 is bismuth nitrate (Bi(NO3)3). In another preparation, the bismuth salt in the electrolyte solution 554 is bismuth chloride (BiCl3). In another preparation, the bismuth salt in the electrolyte solution 554 is bismuth trifluoride (BiF3). In yet another preparation, the bismuth salt in the electrolyte solution 554 contains at least two of bismuth sulfate (Bi2(SO4)3), bismuth oxide (Bi2O3), bismuth nitrate (Bi(NO3)3), bismuth chloride (BiCl3), and bismuth trifluoride (BiF3).

[0079] The bismuth salt in the electrolyte solution 554 may be present at a concentration of about 0.25 grams per liter to about 10 grams per liter, based on the total volume of the activation solution 554. In one alternative expression, the concentration of the bismuth salt is in the range of about 0.25 grams per liter to about 5 grams per liter, based on the total volume of the electrolyte solution 554. In another alternative expression, the concentration of the bismuth salt is in the range of about 0.25 grams per liter to about 2.5 grams per liter, based on the total volume of the electrolyte solution 554. In another alternative expression, the concentration of the bismuth salt is in the range of about 0.25 grams per liter to about 1 gram per liter, based on the total volume of the electrolyte solution 554. In another alternative expression, the concentration of the bismuth salt is in the range of about 0.3 grams per liter to about 0.8 grams per liter, based on the total volume of the electrolyte solution 554. In another alternative expression, the concentration of the bismuth salt is in the range of about 0.4 grams per liter to about 4 grams per liter, based on the total volume of the electrolyte solution 554. In a further alternative expression, the concentration of the bismuth salt is in the range of about 0.4 grams per liter to about 0.7 grams per liter, based on the total volume of the electrolyte solution 554.

[0080] The acid reduces the pH of the electrolyte solution 554. In one preparation, the acid in the electrolyte solution 554 is sulfuric acid (H2SO4). In another preparation, the acid in the electrolyte solution 554 is sulfamic acid (H3NSO3). In yet another preparation, the acid in the activation solution 554 contains both sulfuric acid (H2SO4) and sulfamic acid (H3NSO3).

[0081] The acid in the electrolyte solution 554 may be present at a concentration in the range of about 50 milliliters per liter to about 150 milliliters per liter based on the total volume of the electrolyte solution 554. In one alternative expression, the concentration of the acid is in the range of about 60 milliliters per liter to about 140 milliliters per liter based on the total volume of the electrolyte solution 554. In another alternative expression, the concentration of the acid is in the range of about 70 milliliters per liter to about 130 milliliters per liter based on the total volume of the electrolyte solution 554. In another alternative expression, the concentration of the acid is in the range of about 75 milliliters per liter to about 125 milliliters per liter based on the total volume of the electrolyte solution 554. In another alternative expression, the concentration of the acid is in the range of about 80 milliliters per liter to about 120 milliliters per liter based on the total volume of the electrolyte solution 554. In yet another alternative expression, the concentration of the acid is in the range of about 90 milliliters per liter to about 110 milliliters per liter based on the total volume of the electrolyte solution 554.

[0082] Additional components may be included in the electrolyte solution 554, so long as they do not depart from the scope of the present disclosure. Various carriers and / or additives may be included in the electrolyte solution 554. As one specific, non-limiting example, the electrolyte solution 554 can include TIN MAC HT STARTER A (a surfactant protected by intellectual property rights, commercially available from MacDermid of Waterbury, Connecticut). As another specific, non-limiting example, the electrolyte solution 554 can include TIN MAC HT STARTER B (a source of methacrylic acid protected by intellectual property rights, commercially available from MacDermid of Waterbury, Connecticut). As yet another specific, non-limiting example, the electrolyte solution 554 can include TIN MAC HT REPLENISHER (a source of dipropylene glycol methyl ether and a surfactant protected by intellectual property rights, commercially available from MacDermid of Waterbury, Connecticut). In one embodiment, the electrolyte solution further contains at least one of a surfactant, methacrylic acid, and dipropylene glycol methyl ether.

[0083] As one specific, non-limiting example, the electrolyte solution 554 includes water, 30 grams of stannous sulfate (SnSO4) per liter, 0.58 grams of bismuth sulfate (Bi2(SO4)3) per liter, 105 milliliters of sulfuric acid (H2SO4) per liter, 20 milliliters of TIN MAC HT STARTER A per liter, 5 milliliters of TIN MAC HT STARTER B per liter, and 3 milliliters of TIN MAC HT REPLENISHER per liter.

[0084] The electrolyte solution 554 can be manufactured in various ways, so long as it does not depart from the scope of the present disclosure. In one specific implementation, the method according to the present disclosure for manufacturing the electrolyte solution 554 includes the following steps: (1) Mix at least a part of an acid (e.g., sulfuric acid at 66 degrees Baume) and water (e.g., deionized water) to obtain an acidic solution. (2) Dissolve a tin salt (e.g., tin sulfate (SnSO4)) in the acid solution. (3) Dissolve a bismuth salt (e.g., bismuth sulfate (Bi2(SO4)3)) in the acidic solution. (4) Optionally, add one or more additives / carriers (e.g., TIN MAC HT STARTER A, TIN MAC HT STARTER B, and / or TIN MAC HT REPLENISHER), and (5) Add additional water if necessary to bring the electrolyte solution 554 to the required total volume. It includes.

[0085] In block 504 (Figure 10), immerse the substrate 556 in the electrolyte solution 554 (e.g., completely immerse it). The conducting wire 566 can electrically connect the immersed substrate 556 and the first terminal 562 of the current source 560.

[0086] In block 506 (Figure 10), immerse the anode 558 in the electrolyte solution 554 (e.g., completely immerse it). The conducting wire 568 can electrically connect the immersed anode 558 and the second terminal 564 of the current source 560.

[0087] In block 508 (Figure 10), activate the current source 560 so that current passes between the substrate 556 and the anode 558. A tin-bismuth alloy will be deposited on the substrate 556 by the current.

[0088] The step of passing a current (block 508) can be performed at various current densities, so long as it does not depart from the scope of the present disclosure. One of ordinary skill in the art would positively evaluate that the current density is a controllable parameter and that various factors (including, among other factors, for example, the duration of the step of passing a current (block 508)) need to be considered in order to select an appropriate current density. In one representation, the current passed during the step of passing a current (block 508) can have a current density ranging from about 10 amperes per square foot to about 80 amperes per square foot, based on the surface area of the substrate 556. In another representation, the current passed during the step of passing a current (block 508) can have a current density ranging from about 10 amperes per square foot to about 50 amperes per square foot, based on the surface area of the substrate 556. In another representation, the current passed during the step of passing a current (block 508) can have a current density ranging from about 20 amperes per square foot to about 40 amperes per square foot, based on the surface area of the substrate 556. In another representation, the current passed during the step of passing a current (block 508) can have a current density ranging from about 15 amperes per square foot to about 30 amperes per square foot, based on the surface area of the substrate 556. In yet another representation, the current passed during the step of passing a current (block 508) can have a current density of about 30 amperes per square foot, based on the surface area of the substrate 556.

[0089] The step of passing a current (block 508) can be performed for various durations without departing from the scope of the present disclosure. A person skilled in the art would positively evaluate that the current density is a controllable parameter and that various factors (including, among other factors, for example, the current density) need to be considered in order to select an appropriate duration. In one expression, the step of passing a current (block 508) can be performed over a period of about 5 minutes to about 120 minutes. In another expression, the step of passing a current (block 508) can be performed over a period of about 5 minutes to about 60 minutes. In another expression, the step of passing a current (block 508) can be performed over a period of about 10 minutes to about 30 minutes. In another expression, the step of passing a current (block 508) can be performed over a period of about 10 minutes to about 20 minutes. In yet another expression, the step of passing a current (block 508) can be performed over a period of about 15 minutes.

[0090] In block 510 (FIG. 10), the substrate 556 is disconnected from the current source 560 and removed from the electrolyte solution 554.

[0091] In block 512 (FIG. 10), the substrate 556 can be rinsed with a rinsing fluid. As one example, the rinsing fluid can be water, such as deionized water.

[0092] Examples of the present disclosure can be described with reference to the aircraft manufacturing and operating method 1000 shown in FIG. 12 and the aircraft 1002 shown in FIG. 13. During pre-manufacture, the aircraft manufacturing and operating method 1000 can include the specifications and design 1004 of the aircraft 1002 and the material procurement 1006. During manufacture, the fabrication 1008 of components / subassemblies and the system integration 1010 of the aircraft 1002 are performed. Thereafter, the aircraft 1002 can be inspected, transported 1012, and transferred to operation 1014. While being operated by a customer, the aircraft 1002 is schedule-managed for periodic maintenance and operation 1016 (which can include modifications, reconstructions, retrofits, etc.).

[0093] Each step of the operation method 1000 can be implemented or performed by a system integrator, a third party, and / or an operator (such as a customer). For the purposes of this specification, the system integrator may include, but is not limited to, any number of aircraft manufacturers and subcontractors of major systems, the third party may include, but is not limited to, any number of vendors, subcontractors, and suppliers, and the operator may be an airline, a leasing company, a military organization, a service agency, etc.

[0094] As shown in FIG. 13, the aircraft 1002 manufactured by the exemplary method 1000 can include a fuselage 1018 having a plurality of systems 1020 and an interior 1022. Examples of the plurality of systems 1020 may include one or more of one or more propulsion systems 1024, an electrical system 1026, a hydraulic system 1028, and an environmental system 1030. Other systems may be included singly or in plurality.

[0095] The compositions and methods disclosed herein can be used during one or more stages in aircraft manufacturing and operation method 1000. As one example, the components or subassemblies 1008 corresponding to component / subassembly manufacturing, system integration 1010, and / or maintenance and operation 1016 can be fabricated or manufactured using the compositions and methods disclosed herein. As another example, the fuselage 1018 may be constructed using the compositions and methods disclosed herein. Also, one or more examples of devices, examples of methods, or combinations thereof can also be utilized during component / subassembly fabrication 1008 and / or system integration 1010, for example, by significantly accelerating the assembly of an aircraft or by reducing the cost of an aircraft 1002 (such as the fuselage 1018 and / or the interior 1022), for example. Similarly, one or more examples of systems, examples of methods, or combinations thereof can be utilized during the operation of the aircraft 1002, for example, for maintenance and operation 1016, but not limited thereto.

[0096] The present disclosure further includes the following illustrative and non-limiting examples, which may or may not be included in the claims.

[0097] Example 1: A method for producing an electrolyte solution, comprising: mixing at least one of sulfuric acid and sulfamic acid with at least a portion of water to obtain an acidic solution; dissolving a tin salt in the acidic solution; and dissolving a bismuth salt in the acidic solution. A method comprising the above steps.

[0098] Example 2: An electrodeposition system, comprising: a current source having a first terminal and a second terminal; a bath containing the electrolyte solution of Example 1; a substrate immersed in the electrolyte solution and electrically connected to the first terminal of the current source; and an anode containing tin, immersed in the electrolyte solution and electrically connected to the second terminal of the current source. An electrodeposition system comprising the above components.

[0099] Example 3: The electrodeposition system according to Example 1 or 2, wherein the anode further contains bismuth.

[0100] Example 4: The electrodeposition system according to any one of Examples 1 to 3, wherein the anode further contains from about 2 wt% to about 5 wt% of bismuth, and substantially the remainder of the anode is tin.

[0101] Example 5: A method for depositing a tin-bismuth alloy on a substrate, comprising: immersing the substrate and an anode containing tin in the electrolyte solution of Example 1; and passing a current between the substrate and the anode to form a deposit on the substrate. A method comprising the above steps.

[0102] Example 6: The method according to Example 5, wherein the anode further comprises from about 2 weight percent to about 5 weight percent bismuth, and substantially the balance of the anode is tin.

[0103] Example 7: The method according to Example 5 or 6, wherein the current has a current density of from about 10 amperes per square foot to about 50 amperes per square foot based on the surface area of the substrate.

[0104] Example 8: The method according to Example 7, wherein the current has a current density of from about 15 amperes per square foot to about 30 amperes per square foot based on the surface area of the substrate.

[0105] Example 9: The method according to Example 8, wherein the current has a current density of from about 15 amperes per square foot to about 30 amperes per square foot based on the surface area of the substrate.

[0106] Example 10: The method according to any one of Examples 5 to 9, wherein the current is passed for a duration, and the duration is from about 5 minutes to about 120 minutes.

[0107] Example 11: The method according to Example 10, wherein the current is passed for a duration, and the duration is from about 10 minutes to about 20 minutes.

[0108] Example 12: The method according to any one of Examples 5 to 11, further comprising activating the substrate prior to dipping and passing the current.

[0109] Example 13: The method according to any one of Examples 5 to 12, wherein activation comprises dipping the substrate in an activation solution for a predetermined time, and the activation solution comprises water, an ammonium salt containing a fluorine-containing anion, and sulfuric acid.

[0110] Example 14: The method according to any one of Examples 5 to 13, wherein activation comprises dipping the substrate in an activation solution for a predetermined time, and the activation solution comprises water, a fluoride salt, hydrofluoric acid, and sulfuric acid.

[0111] Example 15: The method according to any one of Examples 5 to 14, wherein the activation comprises subjecting the substrate to an anodic sulfuric acid process.

[0112] Example 16: The method according to any one of Examples 5 to 15, further comprising strike plating the substrate prior to immersing and passing an electric current.

[0113] Example 17: The method according to any one of Examples 5 to 16, wherein the strike plating comprises nickel strike plating.

[0114] Example 18: The strike plating comprises immersing the substrate and a nickel anode in a strike plating electrolyte solution containing nickel chloride, hydrochloric acid and water, and passing an electric current between the substrate and the nickel anode The method according to any one of Examples 5 to 17.

[0115] Example 19: The strike plating electrolyte solution comprises nickel chloride at about 100 grams per liter to about 300 grams per liter based on the total volume of the strike plating electrolyte solution, and hydrochloric acid at about 50 milliliters per liter to about 250 milliliters per liter based on the total volume of the strike plating electrolyte solution. The method according to any one of Examples 5 to 18.

[0116] Example 20: An electrolyte solution containing water, a tin salt, a bismuth salt, and at least one of sulfuric acid and sulfamic acid.

[0117] Example 21: The electrolyte solution according to Example 20, wherein the tin salt comprises tin sulfate.

[0118] Example 22: The electrolyte solution according to Example 20 or 21, wherein the tin salt is present at a concentration in the range of 20 grams per liter to 100 grams per liter based on the total volume of the electrolyte solution.

[0119] Example 23: An electrolyte solution according to any one of Examples 20 to 22, wherein the bismuth salt comprises bismuth sulfate.

[0120] Example 24: An electrolyte solution according to any one of Examples 20 to 23, wherein the bismuth salt is present at a concentration in the range of 0.4 grams per liter to 4 grams per liter based on the total volume of the electrolyte solution.

[0121] Example 25: An electrolyte solution according to any one of Examples 20 to 24, wherein at least one of sulfuric acid and sulfamic acid is present at a concentration in the range of 75 milliliters per liter to 125 milliliters per liter based on the total volume of the electrolyte solution.

[0122] Example 26: An electroplating system comprising a current source having a first terminal and a second terminal, a bath containing the electrolyte solution of Example 20, a substrate immersed in the electrolyte solution, the substrate being electrically connected to the first terminal of the current source, and a tin-containing anode immersed in the electrolyte solution and electrically connected to the second terminal of the current source. The electroplating system.

[0123] Example 27: The electroplating system according to Example 26, wherein the anode further comprises bismuth.

[0124] The compositions and methods disclosed herein are described in the context of aircraft, but one of ordinary skill in the art will immediately understand that the disclosed compositions and methods are applicable to a variety of uses. For example, the disclosed compositions and methods can be implemented in a variety of types of vehicles, including, for example, helicopters, passenger ships, automobiles, marine products (ships, motors, etc.).

[0125] Although various aspects of the compositions and methods disclosed for electrodepositing a tin-bismuth alloy onto a metal substrate have been shown and described, those skilled in the art who have read this specification can make appropriate modifications. Such modifications are included in this application, and this application is limited only by the claims.

Claims

1. An electrolyte solution comprising: water, a tin salt, a bismuth salt, and at least one of sulfuric acid and sulfamic acid. The electrolyte solution.

2. The electrolyte solution according to claim 1, wherein the tin salt contains at least one of tin sulfate, tin chloride, and tin fluoride.

3. The electrolyte solution according to claim 1 or 2, wherein the tin salt is present at a concentration in the range of 15 grams per liter to 200 grams per liter based on the total volume of the electrolyte solution.

4. The electrolyte solution according to claim 1, wherein the bismuth salt contains at least one of bismuth sulfate, bismuth oxide, bismuth nitrate, bismuth chloride, and bismuth trifluoride.

5. The electrolyte solution according to any one of claims 1 to 4, wherein the bismuth salt is present at a concentration in the range of 0.25 grams per liter to 10 grams per liter based on the total volume of the electrolyte solution.

6. The electrolyte solution according to claim 1, wherein at least one of sulfuric acid and sulfamic acid is present at a concentration in the range of 50 milliliters per liter to 150 milliliters per liter based on the total volume of the electrolyte solution.

7. The electrolyte solution according to claim 1, containing tin sulfate, bismuth sulfate, and sulfuric acid.

8. The electrolyte solution according to any one of claims 1 to 7, further containing at least one of a surfactant, methacrylic acid, and dipropylene glycol methyl ether.

9. An electrodeposition system comprising: a current source having a first terminal and a second terminal, a bath containing the electrolyte solution according to claim 1, a substrate immersed in the electrolyte solution and electrically connected to the first terminal of the current source, and an anode containing tin, immersed in the electrolyte solution and electrically connected to the second terminal of the current source. The electrodeposition system.

10. The electrodeposition system according to claim 9, wherein the anode further contains about 2 wt% to about 5 wt% bismuth, and substantially the remainder of the anode is tin.

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