CN117677733A - Silver electrolyte for depositing silver dispersion layer - Google Patents

Silver electrolyte for depositing silver dispersion layer Download PDF

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Publication number
CN117677733A
CN117677733A CN202280051010.0A CN202280051010A CN117677733A CN 117677733 A CN117677733 A CN 117677733A CN 202280051010 A CN202280051010 A CN 202280051010A CN 117677733 A CN117677733 A CN 117677733A
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Prior art keywords
electrolyte
silver
graphite
amount
electrolyte according
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U·曼兹
A·彼得斯
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Umicore Galvanotechnik GmbH
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Umicore Galvanotechnik GmbH
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D3/00—Electroplating: Baths therefor
    • C25D3/02—Electroplating: Baths therefor from solutions
    • C25D3/46—Electroplating: Baths therefor from solutions of silver
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D7/00—Electroplating characterised by the article coated
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D7/00—Electroplating characterised by the article coated
    • C25D7/06—Wires; Strips; Foils
    • C25D7/0614—Strips or foils

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electroplating And Plating Baths Therefor (AREA)

Abstract

The present invention relates to silver electrolytes and corresponding methods for electrodepositing silver on conductive substrates. The silver electrolyte is characterized by specific additives that help prevent the electrolyte from foaming without negatively affecting electrodeposition.

Description

Silver electrolyte for depositing silver dispersion layer
Description
The present invention relates to silver electrolytes and corresponding methods for electrodepositing silver on conductive substrates. The silver electrolyte is characterized by specific additives that help prevent the electrolyte from foaming without negatively affecting electrodeposition.
Electrical contacts are currently used in almost all appliances. Electrical contacts have applications in the automotive industry or aerospace technology ranging from simple plug connectors to safety-related precision switching contacts in the communications field. The contact surfaces here need to have good electrical conductivity, a low contact resistance which is stable over a long period of time, and good corrosion and wear resistance at as low an insertion force as possible. In electrical engineering, the plug contacts are often coated with a hard gold alloy layer consisting of gold-cobalt, gold-nickel or gold-iron. These layers have good wear resistance, good solderability, long-term stability with low contact resistance, and good corrosion resistance. As gold prices rise, cheaper alternatives are being sought.
As an alternative to hard gold plating, a coating with silver has proven to be advantageous. Silver and silver alloys are among the most important contact materials in electrical engineering, not only due to their higher conductivity and good oxidation resistance. These silver layers have similar layer characteristics as the hard gold layers and layer combinations used so far, such as palladium-nickel with gold flash. Furthermore, the price of silver is relatively low compared to other noble metals, particularly hard gold alloys.
Special silver electrolytes are used for silver coating of substrates and for producing contact surfaces. These are typically cyanide-containing or cyanide-free silver-containing solutions for electrochemical plating of surfaces, in particular electroplating silver. In this case, the silver electrolyte solution may contain various other additives such as a grain refiner, a dispersant, a brightening agent, or a solid component. For applications in the electrical and electronic fields, in particular in plugs and plug and switch contacts, electrical conductivity, contact resistance and friction coefficient are particularly relevant.
If two silver-plated surfaces are moved over each other, a relatively high force is required for this purpose, which force depends on the normal force applied separately and the material specific friction coefficient of the surfaces. The disadvantages of contacts with silver surfaces are evident here, since these have a relatively high coefficient of friction, which leads to high plugging forces and tensile forces, in particular in the case of plug contacts. Due to the high friction coefficient, wear occurs in the case of silver surfaces, with the result that the number of possible plugging cycles is severely limited. In addition, there is a problem in that the silver surface is easily worn. However, the lowest possible contact resistance of the two silver plated surface system is particularly advantageous.
Various cyanide-containing silver electrolytes for producing contact surfaces have been identified in the prior art (DE 2543082A1, WO9114808A1, DE10346206A1, DE102008030988A1, DE102015102453A1, CN 105297095A). DE102018005352A1 also describes cyanide-containing silver electrolytes for producing contact surfaces into which solid components are dispersed as dry lubricants. These solids are intended to be incorporated into the silver layer in a manner that is as highly dispersed and easily distributed as possible. The aim is to ensure the highest possible self-lubricating properties of the silver layer by means of a uniform dispersion of the solid components therein (Arnet, R. Et al, "Silberdispersionsschichten mit selbstschmierenden Eigenschaften" [ Silver dispersion layers with self-lubricating properties ], galvanotechnik 2021, volume 1, page 21 and subsequent pages). A problem is that the known silver electrolytes tend to foam, especially when significant electrolyte movement is used, such as when a dispersing device is used (total volume of electrolyte increases by about 40%). However, significant electrolyte movement is necessary for high available current densities and thus rapid deposition. This has a particularly disadvantageous effect during the coating process:
a) Uniformly incorporating the solid into the silver layer;
b) Electrolyte loss due to foam being discharged from the process vessel; and
c) A marbled effect is generated on a part of the surface due to the adhesion of foam during extension and lifting of the component;
and thus cause adverse product or process problems. It is therefore an object of the present invention to specify a possibility by means of which foam formation is suppressed to the greatest extent in such electrolytes during silver deposition and at the same time as no adverse effect on the uniform deposition of the silver-dispersed layer is possible.
These and other objects evident in the prior art are achieved by the use of an electrolyte according to the present claim 1. Advantageous embodiments relating to the electrolyte according to the invention are set forth in the dependent claims 2 to 7 depending on claim 1. Claims 8 to 11 relate to a method comprising preferred embodiments thereof.
By providing an aqueous silver electrolyte for electrodepositing a silver layer on a conductive substrate, the aqueous silver electrolyte comprises the following components:
a) At least one soluble silver compound;
b) Free cyanide in an amount of 20g/l to 200g/l;
c) At least one gloss additive in an amount of from 0.2g/l to 10g/l;
d) At least one wetting agent in an amount of 0.1ml/l to 15ml/l;
e) At least one solid component in an amount of from 2g/l to 200g/l;
wherein the electrolyte additionally has:
f) At least one defoamer in an amount of from 0.2g/l to 20g/l,
surprisingly, the object is easily achieved.
During deposition of the silver layer from the electrolyte according to the invention, the electrolyte should be kept in constant motion in order to prevent precipitation of solid components and to ensure the highest possible current density. Foam formation is reliably prevented/greatly reduced by the defoamer. It is also surprising that the addition of the corresponding defoamers does not significantly adversely affect the desired properties of the layer (solid incorporation) and silver layer (such as contact resistance).
In principle, all compounds which are obtainable by the person skilled in the art and which have an antifoaming effect and are inert in the given system can be used as defoamers(http://de.wikipedia.org/w/index.phptitle＝Entsch％C3％ A4umer&oldid＝187879609). Examples include the polyether (BASF)E Series), fatty alcohol alkoxylates (BASF +.>SD 20), phosphate (BASF +.>SD 40) or alkyl polyethylene glycol ether carbonate (CLARIANT>100A defoamer of the group consisting of. The use of polyether-based defoamers is particularly advantageous. In this case, those selected from the group of polyalkylene glycols, in particular polyethylene glycols, are advantageoushttp:// de.wikipedia.org/w/index.phptitle＝Polyethylenglycol&oldid＝210432692). These are available under different trade names, for example +.>Series E200 to E9000 are commercially available, the numerical code corresponding to the average molecular weight of the substance. It has also proved to be advantageous if the polyalkylene glycols used, in particular polyethylene glycols, have a relatively high average molar mass of more than 200g/mol, preferably at least 400 g/mol. The average molar mass of the polyethylene glycols used is very preferably between 1000g/mol and 9000g/mol, and very particularly preferably between 4000g/mol and 8000 g/mol. Average molar mass of Polymer [ (]http://de.wikipedia.org/w/index.phptitle＝ Mittlere_molare_Masse&oldid＝188125754) Determination of @ by methods known to those skilled in the arthttp://www.chemgapedia.de/vsengine/vlu/vsc/de/ch/9/mac/charakterisierung/d3/ gpc/gpc.vlu/Page/vsc/de/ch/9/mac/charakterisierung/d3/gpc/ auswertung.vscml.html). The amount of defoamer in the electrolyte can be defined by one skilled in the art. It is in the range from 0.2g/l to 20g/l, preferably from 1g/l to 10g/l, and particularly preferably from 1g/l to 5 g/l.
In the context of the present invention, a gloss additive is a substance that converts the grain size of silver deposit to a smaller grain size. Gloss additives selected from the group consisting of substituted and unsubstituted mononuclear aryl sulphonic acids and thioalkyl carboxylic acids, thiourea have proven successful as such additives. Particularly preferred in this case are aryl sulphonic acids such as phenol sulphonic acid and benzene sulphonic acid, toluene sulphonic acid. However, in particular thiolactic acid, thiobarbituric acid and 1-phenyl-1H-tetrazole-5-thione have also proven to be advantageous. Those compounds which do not adversely affect solids deposition are advantageous. The brighteners B are used in the electrolyte according to the invention in concentrations of from 0.2g/l to 10g/l, preferably from 0.5g/l to 10g/l, and particularly preferably from 1.0g/l to 5 g/l. It is particularly highly advantageous if naphthalene sulfonic acid, naphthalene sulfonic acid derivatives (e.g. condensation products of naphthalene sulfonic acid with aldehydes) or mixtures thereof are not present in the electrolyte according to the invention. In contrast, na or K salts of aryl sulfonic acids are highly preferred, wherein the aryl group is a benzene ring, such as benzenesulfonic acid. The aryl group may be optionally substituted. In particular with regard to the above-mentioned polyether-based defoamers, in particular polyethylene glycol ethers, the latter lead to the occurrence of only small amounts of foam and to significant electrolyte movement despite the high current density and thus the solid components can be well dispersed in the silver deposit (see examples).
The electrolyte contains a solid component. Its function is well recognized in the prior art. Within the meaning of the present invention, "solid component" means a component that is not present in solution but is present in the electrolyte in solid form. In particular, such solid components mentioned in DE102018005352A1 in this connection can be used. These solid components are preferably those selected from the group consisting of: graphite, graphite fluoride, graphite oxide, coated graphite, graphene, carbon black, fullerene, diamond, and Al 2 O 3 Cubic boron nitride or mixtures thereof, preferably graphite, graphite fluoride, graphite oxide, al 2 O 3 Coated graphite or mixtures thereof, more preferably graphite, graphite oxide or mixtures thereof, and even more preferably graphite. The manner in which the substances are appropriately adjusted is well described in the literature and has only a small effect, if any, on the invention described herein. The solid component is present in the electrolyte in a dispersed, in particular physically dispersed, manner. This is especially achieved by corresponding means such as stirrers, dispersing means (e.g.,) Or a dispersion disk. The amount of solid component used may be specified by those skilled in the art at their discretion. In general, the concentration here is from 2g/l to 200g/l, preferably from 20g/l to 150g/l, and particularly preferably from 80g/l to 130g/l. The diameter of the solid component must be chosen by the person skilled in the art according to the application profile. In principle, average particle size [ ]http://de.wikipedia.org/w/index.phptitle＝ Partikelgr％C3％B6％C3％9Fenverteilung&oldid＝186369602) Between 1 μm and 50 μm, preferably between 2 μm and 20 μm, and particularly preferably between 2 μm and 10 μm. For this purpose, the average particle size (d 50 of the Q3 distribution) was measured according to ISO 13320-1 (latest version of day of submission) with a Tornado dry dispersion module from Beckmann company. In the sense of the present invention, the average particle size (d 50) indicates that 50% of the solid component particles have a smaller diameter than the indicated value.
A wetting agent is also present in the electrolyte. Those skilled in the art know how to select these. Typically, ionic and nonionic surfactants are used as wetting agents, such as polyethylene glycol adducts, fatty alcohol sulfates (e.g., sodium lauroyl sulfate), alkyl sulfates, alkyl sulfonates, aryl sulfonates, alkylaryl sulfonates, sulfonated castor oil (see also: kanani, N: galvanotechnik; hanser Verlag, munich Vienna,2000; pages 84 and subsequent). Silver coatings deposited using baths equipped in this way are generally white and glossy to high gloss. The wetting agent results in a non-porous layer. Alkyl sulfate based compounds are preferred as wetting agents. These may be of the type C 1 -C 25 Linear or branched alkyl sulphates of alkyl groups, which may preferably be unsubstituted or optionally substituted, having C 2 -C 20 Linear or branched alkyl sulfates of alkyl groups. The wetting agent preferably contains a compound which may be unsubstituted or optionally substituted and has C 3 -C 15 Linear or branched alkyl sulphates of alkyl groups, which may preferably be unsubstituted or optionally substituted, having C 3 -C 12 Linear or branched alkyl sulfates of alkyl groups. The wetting agents may also be present in the form of their salts, for example sodium salts, potassium salts. In this connection, very particular preference is given to using a salt selected from the group consisting of 2-ethylhexyl sulfate-Na-salt, lauryl ether sulfate-Na-salt, sodium monoalkylsulfate (e.g.sodium tetradecyl sulfate, sodium dodecyl sulfate, sodium ethylhexyl sulfate, decyl sulfate)Sodium, sodium octyl sulfate) and mixtures thereof. The content of the at least one wetting agent is between 0.1ml/l and 15ml/l, preferably between 0.2ml/l and 10ml/l, more preferably between 0.5ml/l and 7ml/l, and even more preferably between 1ml/l and 6 ml/l.
Optionally, salts comprising Se or Te may also be present in the electrolyte. The selenium or tellurium compound used in the electrolyte may be selected accordingly by those skilled in the art. Suitable selenium and tellurium compounds are those in which selenium or tellurium is present in the form of anions in the oxidation state +4 or +6. Selenium and tellurium compounds are advantageously used in electrolytes in which selenium or tellurium is present in the oxidation state +4. The selenium and tellurium compounds are particularly preferably selected from tellurites, selenites, tellurites, selenates, selenocyanates, tellurites and selenates and tellurites. In this case, it is generally preferable to use a selenium compound instead of a tellurium compound. Very particular preference is given to adding selenium to the electrolyte in the form of selenite, for example in the form of potassium selenite. It is highly preferred to add it in the form of potassium selenocyanate. The amount of these compounds in the electrolyte may be selected as desired by those skilled in the art. Selenium or tellurium, which is in the range of 0.1mg-500mg/l, preferably 0.5mg-100mg, and particularly preferably between 0.5mg-10 mg/l.
In addition to the above components, the electrolyte contains a certain amount of free cyanide. This is preferably added to the electrolyte in the form of a water-soluble salt of hydrocyanic acid. Alkali metal salts are advantageous and very particular preference is given to using potassium cyanide. The amount of free cyanide in the electrolyte may be set according to values known to those skilled in the art. Typically, the free cyanide is present in the electrolyte (based in each case on CN ions) in a concentration of from 20g/l to 200g/l, preferably from 80g/l to 180g/l, and particularly preferably from 100g/l to 150 g/l. The cyanide salts used can also be used as conductive salts.
The other major component of the electrolyte is silver to be deposited in dissolved form. This may be introduced into the electrolyte in the form of a water-soluble salt, as required by the person skilled in the art. Those from the group consisting of silver methanesulfonate, silver carbonate, silver phosphate, silver pyrophosphate, silver nitrate, silver oxide, silver lactate, silver fluoride, silver bromide, silver chloride, silver iodide, silver thiocyanate, silver thiosulfate, hydantoin, silver sulfate, silver cyanide and alkaline silver cyanide are possible. Silver potassium cyanide is very particularly advantageous in this case. The initial concentration of silver salt in the electrolyte is between 2g/l and 200g/l, preferably between 10g/l and 100g/l, and particularly preferably between 20g/l and 50g/l (based in each case on Ag metal).
It should be noted that in a preferred embodiment, additional ions may also be present in the electrolyte in dissolved form at low concentrations. These are in particular those which lead to a harder layer compared to the deposition of a pure silver layer, known as hard silver. These are ions selected from the group consisting of Sb, bi, in, sn, W, mo, pb, as, cu, ni. These are generally added in concentrations of from 0.001g/l to 30g/l, preferably from 0.01g/l to 20g/l, and particularly preferably from 0.1g/l to 10g/l (based in each case on the corresponding metal).
The invention also relates to a method of electrodepositing a silver layer on a conductive substrate, wherein the conductive substrate is immersed in an electrolyte according to the invention and an electrical current is established between an anode in contact with the electrolyte and the substrate as a cathode.
The main temperature during deposition of the dispersed layer can be chosen by the person skilled in the art as desired or it can be established by itself due to external influences (frictional heat from the dispersed module). This will be guided by the adequate deposition rate and usable current density range on the one hand and economic considerations or stability of the electrolyte on the other hand. It is advantageous to set the temperature of the electrolyte to 10 to 70 ℃, preferably 15 to 40 ℃ and particularly preferably 20 to 30 ℃.
In principle, the pH of the electrolyte can be adjusted as desired by the person skilled in the art. However, in this case, the person skilled in the art will conduct the guidance taking into account the least possible additional substances that may negatively affect the deposition of the respective layer into the electrolyte. Thus, in a particularly preferred embodiment, the pH is set solely by the addition of a base. Thus, all compounds suitable for the respective application from the point of view of the person skilled in the art can be used. This is preferably an alkali metal hydroxide, oxide or carbonate. During electrolysis, the electrolyte according to the invention is preferably set in the alkaline pH range > 8. The best results can be achieved at a pH in the electrolyte of 8-13, more preferably 9-11. In principle, the pH can be adjusted as desired by the person skilled in the art. However, in this case, the person skilled in the art will conduct the guidance taking into account the least possible additional substances that may negatively affect the deposition of the respective layer into the electrolyte. Thus, in a particularly preferred embodiment, the pH is set solely by the addition of a base. Thus, all compounds suitable for the respective application from the point of view of the person skilled in the art can be used. Fluctuations in relation to the electrolyte pH may occur during electrolysis. In a preferred embodiment of the process of the invention, the person skilled in the art therefore continues to let them monitor the pH during electrolysis and, if necessary, adjust it to the setpoint value. Those skilled in the art will know how to proceed here.
The current density established in the electrolyte according to the invention between the cathode and the anode during the deposition process can be chosen by the person skilled in the art based on the deposition efficiency and quality. The current density in the electrolyte is advantageously set to 0.2A/dm, depending on the application and the type of coating system 2 To 100A/dm 2 . If desired, the current density can be increased or decreased by adjusting system parameters such as the design of the coating unit, flow rates, anode or cathode relationships, and the like. 0.2A/dm 2 -50A/dm 2 The current density of (2) is advantageously, preferably 0.2A/dm 2 -10A/dm 2 And very particularly preferably 1A/dm 2 -5A/dm 2 。
Instead of direct current, pulsed direct current or reverse pulse plating may also be applied. In this case, the current is thereby interrupted for a certain period of time (pulse plating), or the current is reversed. The use of pulse plating in the form of current interruption and reverse pulse plating for silver graphite dispersion deposition is described in the literature (Arnet, R et al, "Silberdispersionsschichten mit selbstschmierenden Eigenschaften", [ Silver dispersion layers with self-lubricating properties ], galvanotechnik 2021, vol.1, page 21 and subsequent pages).
The electrolyte according to the invention and the method according to the invention can be used for electrodeposition of silver layers, preferably for technical applications such as electrical plug connectors and printed circuit boards. For technical applications, coatings in continuous flow systems may also be used.
Layer thicknesses in the range from 0.1 μm to 100 μm are generally deposited in the case of the electrification operation, in particular for current densities of 0.5A/dm 2 To 50A/dm 2 Application of the technology in the scope. For technical applications, layer thicknesses of up to 200 μm or even 500 μm thick are sometimes deposited in continuous equipment as well. For this purpose, the current density is within the above-mentioned range.
Various anodes may be employed when using an electrolyte. The soluble anode or insoluble anode is just as suitable as the combination of soluble anode and insoluble anode. If soluble anodes are used, silver anodes are particularly preferably used (DE 1228887, praktische Galvanotechnik, 5 th edition, eugen G.Leuze Verlag, page 342 and subsequent pages, 1997).
Preferred insoluble anodes are those made of a material selected from the group consisting of: platinized titanium, graphite, stainless steel, mixed metal oxides, glassy carbon anodes and special carbon materials ("diamond-like carbon", DLC), or combinations of these anodes. Insoluble anodes of platinized titanium or titanium coated with mixed metal oxides, preferably selected from iridium oxide, ruthenium oxide, tantalum oxide and mixtures thereof, are advantageous. Iridium-transition metal mixed oxide anodes composed of iridium-ruthenium mixed oxide, iridium-ruthenium-titanium mixed oxide or iridium-tantalum mixed oxide are also advantageously used in the practice of the present invention. More information can be found in Cobley, a.j. Et al (The use of insoluble anodes in acid sulphate copper electrodeposition solutions, trans IMF,2001,79 (3), pages 113 and 114).
Possible electrically conductive substrates are those which can be coated with an electrolyte according to the invention in the acidic pH range. These are preferably noble metal-containing substrates or even non-noble metal substrates, such as nickel or copper surfaces. Preferably, the silver layer according to the invention is deposited on a nickel or nickel alloy layer, or a copper or copper alloy layer. Suitable base materials for use advantageously herein are copper-based materials such as pure copper, brass, bronze (e.g. CuSn, cuSnZn) or specialty copper alloys for plug connectors such as alloys containing silicon, beryllium, tellurium, phosphorus; or iron-based materials such as iron or stainless steel; or nickel alloys, such as NiP, niW, niB; gold or silver. The substrate material may also be a multi-layer system that has been galvanically coated or coated using other coating techniques. For example, this involves a ferrous material that has been nickel-plated or copper-plated and then optionally gold-plated, preplating, or precoated with silver. Thus, the intermediate layer for nickel plating or copper plating can also be made of a corresponding alloy electrolyte, such as NiP, niW, niMo, niCo, niB, cu, cuSn, cuSnZn, cuZn and the like. Another substrate material may be a wax core that has been pre-coated with a conductive silver paint (electroforming).
According to the invention, the term "electrolytic bath" is understood to mean an aqueous solution which is placed in a respective container and is used for electrolysis under electric current together with an anode and a cathode. In this case, only the solid component used represents an exception here.
The electrolyte according to the invention is aqueous. In addition to the added solid components and possibly insoluble heterogeneous defoamers, the compounds used in the electrolyte are soluble in the electrolyte. The term "soluble" refers to those compounds that dissolve in the electrolyte at the operating temperature. Thus, the operating temperature is the temperature at which electrodeposition occurs. In the context of the present invention, a substance is considered to be soluble if at least 1mg/l of the substance is soluble in the electrolyte at the operating temperature.
The electrolyte according to the present invention has long-term stability. By combining the use of the gloss additive for silver deposition and an antifoaming agent, a coating suitable for the application can be obtained. These have a sufficiently low contact resistance and, in addition, maintain a surprisingly high surface integrity in the contact circuit even after multiple plugging and rubbing processes and thus a low contact resistance. This is not to be expected from the state of the art available.
Examples:
aqueous electrolyte composition a:
30g/l silver potassium cyanide
130g/l potassium cyanide
5g/l potassium carbonate
2mg/l Se (calculated as potassium selenocyanate)
4g/l ethylhexyl sulfate
1g/l benzenesulfonic acid
100g/l of graphite powder having an average particle size (d 50) of 2 μm to 4. Mu.m
The current density was 1.5A/dm 2
Temperature: 25 DEG C
Anode: soluble pure silver anode
The addition of the defoamer component does not adversely affect graphite incorporation.
Aqueous electrolyte composition B：
30g/l silver potassium cyanide
130g/l potassium cyanide
5g/l potassium carbonate
2mg/l Se (calculated as potassium selenocyanate)
5g/l ethylhexyl sulfate
1g/l benzenesulfonic acid
100g/l graphite powder having an average particle size (d 50) of 2 μm to 4 μm and a current density of 1.5A/dm 2
Temperature: 25 DEG C
Anode: soluble pure silver anode
The addition of the defoamer component does not adversely affect graphite incorporation.

Claims (11)

1. An aqueous silver electrolyte for electrodepositing a silver layer on a conductive substrate, the aqueous silver electrolyte comprising:
a) At least one soluble silver compound;
b) Free cyanide in an amount of 20g/l to 200g/l;
c) At least one gloss additive in an amount of from 0.2g/l to 10g/l;
d) At least one wetting agent in an amount of 0.1ml/l to 15ml/l;
e) At least one solid component in an amount of from 2g/l to 200g/l;
wherein the electrolyte additionally has:
f) At least one defoamer in an amount of 0.2g/l to 20g/l.
2. The electrolyte according to claim 1,
it is characterized in that
The defoamer is selected from the group of polyalkylene glycols.
3. The electrolyte according to claim 2,
it is characterized in that
The defoamer has an average molar mass of at least 200 g/mol.
4. The electrolyte according to claim 1 to 3,
it is characterized in that
The gloss additive is selected from the group consisting of aryl sulfonic acids.
5. The electrolyte according to any one of claim 1 to 4,
it is characterized in that
The solid component is selected from graphite, graphite fluoride, graphite oxide, diamond, al 2 O 3 Coated graphite or a mixture thereof.
6. The electrolyte according to any one of claim 1 to 5,
it is characterized in that
The wetting agent is selected from the group of alkyl sulfates.
7. The electrolyte according to any one of claim 1 to 6,
it is characterized in that
It additionally comprises at least 0.1mg/l to 500mg/l of a salt of Se or Te anions (based on selenium or tellurium).
8. A method for electrodepositing a silver layer on a conductive substrate,
it is characterized in that
Immersing a conductive substrate in the electrolyte according to claims 1 to 7 and establishing an electrical current between an anode in contact with the electrolyte and the substrate as a cathode.
9. The method according to claim 8, wherein the method comprises,
it is characterized in that
The temperature of the electrolyte is 20-90 ℃.
10. The method according to claim 8 and/or claim 9,
it is characterized in that
The current density during electrolysis was between 0.2A/dm 2 -100A/dm 2 Between them.
11. The method according to any one of the preceding claims 8 to 10,
it is characterized in that
The pH during electrolysis was constantly set to a value of > 8.
CN202280051010.0A 2021-07-21 2022-07-20 Silver electrolyte for depositing silver dispersion layer Pending CN117677733A (en)

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DE102021118820.2A DE102021118820A1 (en) 2021-07-21 2021-07-21 silver electrolyte
PCT/EP2022/070294 WO2023001868A1 (en) 2021-07-21 2022-07-20 Silver electrolyte for separating silver dispersion layers

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JP (1) JP2024526925A (en)
KR (1) KR20240031423A (en)
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DE (1) DE102021118820A1 (en)
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