CA1180674A - Gold electroplating bath and process - Google Patents
Gold electroplating bath and processInfo
- Publication number
- CA1180674A CA1180674A CA000394126A CA394126A CA1180674A CA 1180674 A CA1180674 A CA 1180674A CA 000394126 A CA000394126 A CA 000394126A CA 394126 A CA394126 A CA 394126A CA 1180674 A CA1180674 A CA 1180674A
- Authority
- CA
- Canada
- Prior art keywords
- gold
- bath
- electroplating bath
- alkali metal
- ammonium
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- 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
- C25D3/48—Electroplating: Baths therefor from solutions of gold
Landscapes
- 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
ABSTRACT OF THE DISCLOSURE
Electrolytes for the electrodeposition of gold metal on substrates containing alkali metal or ammonium gold cyanides, a conducting agent, optionally a buffering agent, and at least 30 grams per liter of a grain refiner selected from the group consisting of oxalic acid, formic acid, and the alkali metal or ammonium salts thereof.
The electroplating baths of the invention are operated at 2 pH of from 5 to 7.5, a temperature of 50° to 80°C., and a current density ranging from 1 to 20 ASF. The method of using the gold metal electroplating baths of this invention is also described and claimed.
Electrolytes for the electrodeposition of gold metal on substrates containing alkali metal or ammonium gold cyanides, a conducting agent, optionally a buffering agent, and at least 30 grams per liter of a grain refiner selected from the group consisting of oxalic acid, formic acid, and the alkali metal or ammonium salts thereof.
The electroplating baths of the invention are operated at 2 pH of from 5 to 7.5, a temperature of 50° to 80°C., and a current density ranging from 1 to 20 ASF. The method of using the gold metal electroplating baths of this invention is also described and claimed.
Description
GOLD ELECTROPLATING BATH
.
AND PROCESS
, FIELD OF THE INVENTION
The present invention rela-tes to compositions and methods for the electrodeposition of lemon yellow colored gold metal on substrates from baths having a pH of from about 5 to 7.5 wherein the source of the gold is al~ali metal or ammonium gold cyanides.
BACKGROUND OF THE INVENTION
_ . _ _ _ Mumerous electrolyt~ baths have been proposed in recent years for the electrodeposition of gold on -to substrates. Representative patents include the following U.S. Patents:
.
AND PROCESS
, FIELD OF THE INVENTION
The present invention rela-tes to compositions and methods for the electrodeposition of lemon yellow colored gold metal on substrates from baths having a pH of from about 5 to 7.5 wherein the source of the gold is al~ali metal or ammonium gold cyanides.
BACKGROUND OF THE INVENTION
_ . _ _ _ Mumerous electrolyt~ baths have been proposed in recent years for the electrodeposition of gold on -to substrates. Representative patents include the following U.S. Patents:
2~905j601 - Rinker et al
3,104,212 - Rinker et al 3,156,634 - Duva et al 3,156,635 - Foulke 3,367,853 - Schumpelt 3,373,094 ~ Foulke 3,423,295 - Greenspan 3,776,821 - Ba~e~
3,776,822 - Baker 3,833,487 - Reinheimer 3,878,066 - Dettke British Patent:
1,065,308 - Nobel et al It is apparent from these disclosures that in order to obtain the desired gold electroplating deposits special procedures and additives have to be employed when the electrolytes operate at a pH of from about 5 to 7.5 rather than at the lower pH range of from about 3 to 6. Thus, for example, at the higher pHs it has been customary to use grain refiners such as hydrazine~ arsenic, thallium, and the like. When such electrolyte baths are operated ~,lithout these grain refiners the deposits tend to have ;~
a bro-~nish appearance, and the electrolytes only operate over a very limited density rangeO Un~ortuna-tely, the conventional c3rain refiners employed heretofore have been found in some instances to be either carcinogenic and/or harmful to the integrity of the gold~ i.e. gold plate degradation, because o:E t~leir occ]usion in the deposits.
The ability to operate gold plating baths at a pll with-in the range of about 5-7.5, i~e,, at a substan-tially neutral p~l, is advantageous :Eor several reasons. When operated within such range ~ rather than lower or higher ranges, the amount of gold dissolved from the plated par-ts is significantly reduced. Additionally, there is a reduction in the amount of metal contaminants in the pla-ting bath and any codeposition of any such contaminants that may be present is minimized.
SU~ RY OF THE INVENTION
In accordance ~ith the present invention it has now been found that the use of special grain refiners, and especially in at least certain prescribed amounts, in gold electrolyte baths formulated to operate with a pH ranging from about 5.0 to 7.5, will lead to lemon yellow gold deposits without the problems noted above. More particu-larly, the problems attendant upon the use of conventional grain refiners are avoided by the present invention through the use of formic acid, o~alic acid, as well as the al~ali metal or ammonium salts of such acids, in a concentration of at least 30 grams per liter, calculated as the acid.
T~e electropla-ting baths of this invention are generally operated at current densities of from about 1 to 20 ASF.
DETAILED DESCRIPTION OF THE INVENTION
The gold electrolytes or electroplating baths of the ~resent invention ~ill be operated under slightly acid to suhstantially neutral conditions, i.e. from aL~out 5 to 7.5 p~, and ~ill utilize a al~ali metal or ar~lonium gold cyzride as source of the gold metal. The gold metal corit~nt of the electrolyte ~ill be at least sufficient to deposit gold on the substrate when the bath is electro lyzed and may be up to the maximum solubility of the gold in the bath. In general, however, the use of very ailute or very concentrated gold solutions provide no particular advantages and may t in some instances, increase the over~
all cost of the process. Accordingly, it is normally desirable that the gold metal content of the electrQlyte range from about 2 to 10 g/l, and preferably from about
3,776,822 - Baker 3,833,487 - Reinheimer 3,878,066 - Dettke British Patent:
1,065,308 - Nobel et al It is apparent from these disclosures that in order to obtain the desired gold electroplating deposits special procedures and additives have to be employed when the electrolytes operate at a pH of from about 5 to 7.5 rather than at the lower pH range of from about 3 to 6. Thus, for example, at the higher pHs it has been customary to use grain refiners such as hydrazine~ arsenic, thallium, and the like. When such electrolyte baths are operated ~,lithout these grain refiners the deposits tend to have ;~
a bro-~nish appearance, and the electrolytes only operate over a very limited density rangeO Un~ortuna-tely, the conventional c3rain refiners employed heretofore have been found in some instances to be either carcinogenic and/or harmful to the integrity of the gold~ i.e. gold plate degradation, because o:E t~leir occ]usion in the deposits.
The ability to operate gold plating baths at a pll with-in the range of about 5-7.5, i~e,, at a substan-tially neutral p~l, is advantageous :Eor several reasons. When operated within such range ~ rather than lower or higher ranges, the amount of gold dissolved from the plated par-ts is significantly reduced. Additionally, there is a reduction in the amount of metal contaminants in the pla-ting bath and any codeposition of any such contaminants that may be present is minimized.
SU~ RY OF THE INVENTION
In accordance ~ith the present invention it has now been found that the use of special grain refiners, and especially in at least certain prescribed amounts, in gold electrolyte baths formulated to operate with a pH ranging from about 5.0 to 7.5, will lead to lemon yellow gold deposits without the problems noted above. More particu-larly, the problems attendant upon the use of conventional grain refiners are avoided by the present invention through the use of formic acid, o~alic acid, as well as the al~ali metal or ammonium salts of such acids, in a concentration of at least 30 grams per liter, calculated as the acid.
T~e electropla-ting baths of this invention are generally operated at current densities of from about 1 to 20 ASF.
DETAILED DESCRIPTION OF THE INVENTION
The gold electrolytes or electroplating baths of the ~resent invention ~ill be operated under slightly acid to suhstantially neutral conditions, i.e. from aL~out 5 to 7.5 p~, and ~ill utilize a al~ali metal or ar~lonium gold cyzride as source of the gold metal. The gold metal corit~nt of the electrolyte ~ill be at least sufficient to deposit gold on the substrate when the bath is electro lyzed and may be up to the maximum solubility of the gold in the bath. In general, however, the use of very ailute or very concentrated gold solutions provide no particular advantages and may t in some instances, increase the over~
all cost of the process. Accordingly, it is normally desirable that the gold metal content of the electrQlyte range from about 2 to 10 g/l, and preferably from about
4 to 8 g/l. The use of potassium and al~lonium gold cya-nides, is especially preferred, but it will be understood that neither the amount of gold metal nor the particular yold cyanide complex employed is critical.
The electroplating bath will al50 contain a convention-al conducting agent such as the alkali metal or ammonium salts of citrates, phosphates, sulphamates, acetates, or the like. In general, the preferred conducting agents for the present purposes include dibasic potassium phosphate, tri-potassium phosphate, and ammonium citrate~ The amount of conducting agent employed will be at least that which will provide sufficient conductivity to the bath to effect the gold electrodeposition, up to the maximum solubility of the conducting agent in the bath. Typically, the conducting agent will be present in an amount from about 2.5 to 200 g/l~
and preferably from about 5 to 50 g/l.
In many instances pH adjustment is necessary to achieve the desired value in the bath of about 5 to 7.5. Such compounds as phosphoric acid, po-tassium hydro~ide, sulphamic acid, ammonium hydroxide, mixtures thereof, and the li~e may be utilized for adjusting the pH to 5 to 7.5, preferably 6.5 to 7.5. Alkali metal hydroxides, other than potassium hydroxide, may also be used for this purpose.
As ~7ill be understood by those skilled in the art, a buffering agent may also be emp~oyed in formulating the gold electroplating baths of the present invention.
The same materials listed ahove as being suitable conduc-ting salts may also be used as buffering agents. The amo~mt of the buffering agents or agents used will be at least sufficient to provide the desired buffering of the plating bath, up to the ma~imum solubility of the bu~fer in the bath. Desirably, the amount of buffering agent will range ~rom a~out 2.5 to 200 g/l, and will preferably be from about 5 to 50 g/l. It will, of course, be appreciated that the same material may be usecl to provide both the desired conductivity and buffering. Alternatively, differ-ent materials may be used to achieve each of these functions~
In either case~ the amount used will be that which is required to provide the necessary buffering and/or conduc-tivity.
In accordance with the foregoing discussion, it will be understood that the essential feature of the present invention is the selection of the grain refiner agent7 Thus, disadvantages associated with the use of previously employed agents have been overcome by utilizing specific grain refiners; namely, oxlic acid, formic acid, and the alkali metal or ammonium salts of these particular carboxylic acids.
The sspecially preferred agents are oxalic acid as well as its potassium and ammonium salts. In general, the amount of grain refiner will be at least 30 g/l, since lower amounts will not achieve the desired resultsO Althougn amounts up to the maximum solubility in the bath may be used, for most purposes, the amount of grain refiner will range from about 30 to 200 g/l, ~alculated as the acid.
Preferred amounts will range from about 35 to 80 ~/1.
It will be further understood that the electroplating process of this invention will generally be operated at current densities ranging from about 1 to 20 ASF and temperatures of from about 50 degrees to ~0 degrees C~, preferably 60 degrees to 70 degrees C. Although bath temperatures above 90 degxees C., eg, up to the boiling point of the bath, can be used, at such higher temper atures r excessive evaporation of the bath often occu s, so that use of these higher temperatures are generally not preferred. These conditions~ plus the pH range of from 5 to 7.5, describe the operating parameters used with the present gold electroplating baths.
It is a further feature of the present invention to use speci~ic brigheners which will readily achieve lemon yellow gold deposits, while a~oiding the difficulties or the limitations as described above, attendant upon the use of the conventional brighteners heretofore employed in gold electroplating baths.
AlthOugh the gold plating baths of this invention may be used effectively for the deposition of gold on many different substrates, its use for plating integrated circuits has been found to be especially outstanding. In this regard, such integrated circuits require that the gold deposits be of very high purity and contain a minimum amount of codeposited metallic element impurities. The gold plating baths of the present invention are unique in their ability to fulfill this requirement without encounter-ing the difficulties and problems attendant with the prior art gold plating baths.
The invention will be more fully understood by reference to the following illustrative er~bodiments.
E ~LE 1 G/L
Gold as Potassium Gold Cyanide 6 Dibasic Potassium Phosphate 100 oxalic Acid 60 The pH of the bath was adjusted to pH 7.0 with phosphoric acid or potassium hydroxide. A grain refined~
lemon yellow gold deposit was obtained on a nickel plated substrate. The bath was operated at a temperature of 65 degrees C. and a current density of up to 10 ASF.
--6~
EVAMP~E 2 -The bath of Example 1 was formulated with the excep-tion -that the oxalic acid was excluded. When operating this bath at current densities o~ up to 3 ASF a yellow gold deposit was obtainedl but at about 3 ASF the deposit had an undesirable brown color.
EXAMPI,E 3 _ Another ba-th was prepared Erom -the following compon-ents:
G/L
Gold as Potassium Gold Cyatlide8 Potassium Sulphama-te 42 Tripotassium Phospllate 16 Oxalic Acid, added as Potassium Oxalate 120 The bath was adjusted with sulphamic acid to a pH of 6. At an opera-ting temperature of 60 degrees C. a grain refined, lemon yellow gold deposit was obtained up to 10 ASF; without the potassium oxalate the deposit had an undesirable brown color at 6 ASF or higher.
A gold electroplating bath was formulated as follows:
G/L
Gold as Ammonium Gold Cyanide 4 Ammonium Citrate 100 oxalic Acid added as Ammonium Oxalate 80 ~mmonium Hydroxide to pH 7.5 ~ t hath operating temperatures of 65 de~rees C. grain-refined, lemon yellow gold deposits were obtained up to 10 ASF.
EX~i~lPLE 5 Another plating bath ~JaS formulated ~rom the follo~!in~
inaredients:
G/L
Gold as Po` assium Gold C~anide Dibasic Potassium Phospnat~ 25 Eormic Acid addea as Potassi-lm Forr,tate G0 The pH ~las ad justed to 7.5 with ortho-phosphoric acid.
Lernon yold deposts ~lere obtained utilizing -this electro-plating ~,ath under the abo~-e described conditions.
-7~
It will be understood, moreover, that the aboveembodiments are illustrative only and that the invention is subject to moaifications and variations within its broader concepts.
The electroplating bath will al50 contain a convention-al conducting agent such as the alkali metal or ammonium salts of citrates, phosphates, sulphamates, acetates, or the like. In general, the preferred conducting agents for the present purposes include dibasic potassium phosphate, tri-potassium phosphate, and ammonium citrate~ The amount of conducting agent employed will be at least that which will provide sufficient conductivity to the bath to effect the gold electrodeposition, up to the maximum solubility of the conducting agent in the bath. Typically, the conducting agent will be present in an amount from about 2.5 to 200 g/l~
and preferably from about 5 to 50 g/l.
In many instances pH adjustment is necessary to achieve the desired value in the bath of about 5 to 7.5. Such compounds as phosphoric acid, po-tassium hydro~ide, sulphamic acid, ammonium hydroxide, mixtures thereof, and the li~e may be utilized for adjusting the pH to 5 to 7.5, preferably 6.5 to 7.5. Alkali metal hydroxides, other than potassium hydroxide, may also be used for this purpose.
As ~7ill be understood by those skilled in the art, a buffering agent may also be emp~oyed in formulating the gold electroplating baths of the present invention.
The same materials listed ahove as being suitable conduc-ting salts may also be used as buffering agents. The amo~mt of the buffering agents or agents used will be at least sufficient to provide the desired buffering of the plating bath, up to the ma~imum solubility of the bu~fer in the bath. Desirably, the amount of buffering agent will range ~rom a~out 2.5 to 200 g/l, and will preferably be from about 5 to 50 g/l. It will, of course, be appreciated that the same material may be usecl to provide both the desired conductivity and buffering. Alternatively, differ-ent materials may be used to achieve each of these functions~
In either case~ the amount used will be that which is required to provide the necessary buffering and/or conduc-tivity.
In accordance with the foregoing discussion, it will be understood that the essential feature of the present invention is the selection of the grain refiner agent7 Thus, disadvantages associated with the use of previously employed agents have been overcome by utilizing specific grain refiners; namely, oxlic acid, formic acid, and the alkali metal or ammonium salts of these particular carboxylic acids.
The sspecially preferred agents are oxalic acid as well as its potassium and ammonium salts. In general, the amount of grain refiner will be at least 30 g/l, since lower amounts will not achieve the desired resultsO Althougn amounts up to the maximum solubility in the bath may be used, for most purposes, the amount of grain refiner will range from about 30 to 200 g/l, ~alculated as the acid.
Preferred amounts will range from about 35 to 80 ~/1.
It will be further understood that the electroplating process of this invention will generally be operated at current densities ranging from about 1 to 20 ASF and temperatures of from about 50 degrees to ~0 degrees C~, preferably 60 degrees to 70 degrees C. Although bath temperatures above 90 degxees C., eg, up to the boiling point of the bath, can be used, at such higher temper atures r excessive evaporation of the bath often occu s, so that use of these higher temperatures are generally not preferred. These conditions~ plus the pH range of from 5 to 7.5, describe the operating parameters used with the present gold electroplating baths.
It is a further feature of the present invention to use speci~ic brigheners which will readily achieve lemon yellow gold deposits, while a~oiding the difficulties or the limitations as described above, attendant upon the use of the conventional brighteners heretofore employed in gold electroplating baths.
AlthOugh the gold plating baths of this invention may be used effectively for the deposition of gold on many different substrates, its use for plating integrated circuits has been found to be especially outstanding. In this regard, such integrated circuits require that the gold deposits be of very high purity and contain a minimum amount of codeposited metallic element impurities. The gold plating baths of the present invention are unique in their ability to fulfill this requirement without encounter-ing the difficulties and problems attendant with the prior art gold plating baths.
The invention will be more fully understood by reference to the following illustrative er~bodiments.
E ~LE 1 G/L
Gold as Potassium Gold Cyanide 6 Dibasic Potassium Phosphate 100 oxalic Acid 60 The pH of the bath was adjusted to pH 7.0 with phosphoric acid or potassium hydroxide. A grain refined~
lemon yellow gold deposit was obtained on a nickel plated substrate. The bath was operated at a temperature of 65 degrees C. and a current density of up to 10 ASF.
--6~
EVAMP~E 2 -The bath of Example 1 was formulated with the excep-tion -that the oxalic acid was excluded. When operating this bath at current densities o~ up to 3 ASF a yellow gold deposit was obtainedl but at about 3 ASF the deposit had an undesirable brown color.
EXAMPI,E 3 _ Another ba-th was prepared Erom -the following compon-ents:
G/L
Gold as Potassium Gold Cyatlide8 Potassium Sulphama-te 42 Tripotassium Phospllate 16 Oxalic Acid, added as Potassium Oxalate 120 The bath was adjusted with sulphamic acid to a pH of 6. At an opera-ting temperature of 60 degrees C. a grain refined, lemon yellow gold deposit was obtained up to 10 ASF; without the potassium oxalate the deposit had an undesirable brown color at 6 ASF or higher.
A gold electroplating bath was formulated as follows:
G/L
Gold as Ammonium Gold Cyanide 4 Ammonium Citrate 100 oxalic Acid added as Ammonium Oxalate 80 ~mmonium Hydroxide to pH 7.5 ~ t hath operating temperatures of 65 de~rees C. grain-refined, lemon yellow gold deposits were obtained up to 10 ASF.
EX~i~lPLE 5 Another plating bath ~JaS formulated ~rom the follo~!in~
inaredients:
G/L
Gold as Po` assium Gold C~anide Dibasic Potassium Phospnat~ 25 Eormic Acid addea as Potassi-lm Forr,tate G0 The pH ~las ad justed to 7.5 with ortho-phosphoric acid.
Lernon yold deposts ~lere obtained utilizing -this electro-plating ~,ath under the abo~-e described conditions.
-7~
It will be understood, moreover, that the aboveembodiments are illustrative only and that the invention is subject to moaifications and variations within its broader concepts.
Claims (8)
1. An electroplating bath for the electrodeposi-tion of gold metal deposits, which consists essentially of a three-component system comprising an alkali metal or ammonium gold cyanide in an amount at least suffi-cient to deposit gold on a substrate when the bath is electrolyzed, a conducting agent in an amount at least sufficient to provide conductivity to the bath, and a grain refiner selected from the group consisting of oxalic acid, formic acid and the alkali metal or ammo-nium salts of said acids, in an amount of at least about 30 grams per liter calculated as the acid, which bath has a pH within the range of from about 6.5 to 7.5.
2. The electroplating bath of claim 1, wherein said conducting agent is alkali metal or ammonium citrate, phosphate, sulphamate or acetate salt.
3. The electroplating bath of claim 1, wherein the pH range is from about 6.5 to 7Ø
4. The electroplating bath of claim 1, wherein the grain refiner is oxalic acid.
5. The electroplating bath of claim 1, wherein the grain refiner is an alkali metal salt of oxalic acid.
6. The electroplating bath of claim 5, wherein the alkali metal salt is potassium oxalate.
7. The electroplating bath of claim 1, wherein the grain refiner is ammonium oxalate.
8. A method of depositing gold on a substrate which comprises passing an electric current through an electroplating bath as defined in claims 1, 2 or 3, between a cathode and an anode, for a period of time sufficient to produce the desired gold deposit.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US23532981A | 1981-02-17 | 1981-02-17 | |
| US235,329 | 1981-02-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1180674A true CA1180674A (en) | 1985-01-08 |
Family
ID=22885037
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000394126A Expired CA1180674A (en) | 1981-02-17 | 1982-01-14 | Gold electroplating bath and process |
Country Status (10)
| Country | Link |
|---|---|
| JP (1) | JPS57152484A (en) |
| BE (1) | BE892161A (en) |
| CA (1) | CA1180674A (en) |
| DE (1) | DE3203000A1 (en) |
| FR (1) | FR2500012B1 (en) |
| GB (1) | GB2093069B (en) |
| HK (1) | HK67586A (en) |
| IT (1) | IT8247798A0 (en) |
| NL (1) | NL8200347A (en) |
| SE (1) | SE8200927L (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1987005339A1 (en) * | 1986-03-05 | 1987-09-11 | Vanguard Research Associates, Inc. | Electrolyte solution and process for high speed gold plating |
| ES2166660B1 (en) * | 1999-05-06 | 2003-02-16 | Torres Josep Ferre | PROCEDURE AND EQUIPMENT FOR THE ELECTRODEPOSITION OF GOLD OR GOLD ALLOYS. |
| JP5559455B2 (en) * | 2007-06-29 | 2014-07-23 | 日本高純度化学株式会社 | Electrolytic gold plating solution and gold film obtained using the same |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3776821A (en) * | 1972-05-12 | 1973-12-04 | Engelhard Min & Chem | Gold plating electrolyte |
-
1982
- 1982-01-14 CA CA000394126A patent/CA1180674A/en not_active Expired
- 1982-01-29 NL NL8200347A patent/NL8200347A/en not_active Application Discontinuation
- 1982-01-29 DE DE19823203000 patent/DE3203000A1/en not_active Ceased
- 1982-02-15 IT IT8247798A patent/IT8247798A0/en unknown
- 1982-02-16 BE BE0/207332A patent/BE892161A/en not_active IP Right Cessation
- 1982-02-16 SE SE8200927A patent/SE8200927L/en not_active Application Discontinuation
- 1982-02-16 FR FR8202499A patent/FR2500012B1/en not_active Expired
- 1982-02-17 JP JP57024259A patent/JPS57152484A/en active Granted
- 1982-02-17 GB GB8204707A patent/GB2093069B/en not_active Expired
-
1986
- 1986-09-11 HK HK675/86A patent/HK67586A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| SE8200927L (en) | 1982-08-18 |
| IT8247798A0 (en) | 1982-02-15 |
| GB2093069B (en) | 1984-01-11 |
| DE3203000A1 (en) | 1982-08-19 |
| HK67586A (en) | 1986-09-18 |
| FR2500012A1 (en) | 1982-08-20 |
| JPS57152484A (en) | 1982-09-20 |
| BE892161A (en) | 1982-08-16 |
| NL8200347A (en) | 1982-09-16 |
| FR2500012B1 (en) | 1985-12-27 |
| JPS6123878B2 (en) | 1986-06-07 |
| GB2093069A (en) | 1982-08-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEC | Expiry (correction) | ||
| MKEX | Expiry |