US20200232099A1 - Plating bath composition for electroless plating of gold and a method for depositing a gold layer - Google Patents

Plating bath composition for electroless plating of gold and a method for depositing a gold layer Download PDF

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US20200232099A1
US20200232099A1 US15/758,754 US201615758754A US2020232099A1 US 20200232099 A1 US20200232099 A1 US 20200232099A1 US 201615758754 A US201615758754 A US 201615758754A US 2020232099 A1 US2020232099 A1 US 2020232099A1
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gold
plating bath
plating
alloys
gold plating
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Robert SPREEMANN
Christian Nöthlich
Sabrina GRUNOW
Dmytro VOLOSHYN
Boris Alexander JANSSEN
Donny LAUTAN
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Atotech Deutschland GmbH and Co KG
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Atotech Deutschland GmbH and Co KG
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Publication of US20200232099A1 publication Critical patent/US20200232099A1/en
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
    • C23C18/31—Coating with metals
    • C23C18/42—Coating with noble metals
    • C23C18/44—Coating with noble metals using reducing agents
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
    • C23C18/1601—Process or apparatus
    • C23C18/1633—Process of electroless plating
    • C23C18/1635—Composition of the substrate
    • C23C18/1637—Composition of the substrate metallic substrate
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
    • C23C18/18—Pretreatment of the material to be coated
    • C23C18/1803—Pretreatment of the material to be coated of metallic material surfaces or of a non-specific material surfaces
    • C23C18/1824—Pretreatment of the material to be coated of metallic material surfaces or of a non-specific material surfaces by chemical pretreatment
    • C23C18/1837—Multistep pretreatment
    • C23C18/1844—Multistep pretreatment with use of organic or inorganic compounds other than metals, first

Definitions

  • the present invention relates to electroless aqueous gold plating bath compositions for electroless plating of gold layers onto a substrate and a method for depositing gold.
  • the plating bath is particularly suitable in the manufacture of printed circuit boards, IC substrates, semiconducting devices, interposers made of glass and the like.
  • Gold layers are of paramount interest in the manufacturing of electronic components and in the semiconductor industry. Gold layers are frequently used as solderable and/or wire bondable surfaces in the manufacture of printed circuit boards, IC substrates, semiconducting devices and the like. Typically, they are used as a final finish before soldering and wire bonding. In order to provide electrical connections of sufficient conductivity and robustness between the copper lines and wires that are bonded thereto while providing a good strength for wire bonding, there are various layer assemblies which are used conventionally in the art. Among others, there are electroless nickel electroless gold (ENIG), electroless nickel electroless palladium immersion gold (ENEPIG), direct immersion gold (DIG), electroless palladium immersion gold (EPIG) and electroless palladium autocatalytic gold (EPAG).
  • ENIG electroless nickel electroless gold
  • ENEPIG electroless nickel electroless palladium immersion gold
  • DIG direct immersion gold
  • EPIG electroless palladium immersion gold
  • EPAG electroless palladium autocatalytic gold
  • Electroless plating generally describes methods without using external current sources for reduction of metal ions.
  • Plating processes using external current sources are commonly described as electrolytic or galvanic plating methods.
  • Non-metallic surfaces may be pretreated to make them receptive or catalytic for metal deposition. All or selected portions of a surface may suitably be pretreated.
  • the main components of electroless metal baths are the metal salt, a reducing agent, and, as optional ingredients, a complexing agent, a pH adjuster, and additives, as for example stabilising agents.
  • Complexing agents are used to chelate the metal being deposited and prevent the metal from being precipitated from solution (i.e. as the hydroxide and the like). Chelating metal renders the metal available to the reducing agent that converts the metal ions to metallic form.
  • a further form of metal deposition is immersion plating.
  • Immersion plating is another deposition of metal using neither external current sources nor chemical reducing agents.
  • the mechanism relies on the substitution of metals from an underlying substrate for metal ions present in the immersion plating solution. This is a distinct disadvantage of immersion plating because deposition of thicker layers is normally limited by the layer porosity.
  • electroless gold plating baths use one or both types of electroless plating. Even if reducing agents have been added to the plating bath, immersion- type plating may occur albeit in a significantly reduced proportion.
  • electroless plating is to be understood (mainly) as autocatalytic deposition with the aid of a chemical reducing agent (referred to as “reducing agent” herein).
  • US 2012/0129005 A1 discloses an electroless gold plating bath comprising a water-soluble gold compound and an alkylene diamine, dialkylene triamines or the like.
  • gold plating solution lack sufficient stability and plating rate and are thus not applicable in industrial processes (see example 4).
  • US 2008/0138507 A1 reports electroless gold plating baths which use aldehyde compounds as reducing agents and N-substituted ethylene diamine derivatives such as N 1 ,N 2 -dimethylethylenediamine and N 1 ,N 2 -bis-(methylol)ethylenediamine. But again, the plating baths described therein lack plating rate and stability (see example 4). It is typically sufficient that gold plating bath have plating rates of 150 nm/h or more, preferably of 200 nm/h or more or ideally, of 250 nm/h or more to comply with today's industrial requirements.
  • the electroless aqueous gold plating bath according to the invention which comprises at least one source of gold ions and at least one reducing agent for gold ions, and is characterized in that it comprises at least one ethylenediamine derivative as plating enhancer compound according to formula (I)
  • residues R 1 and R 2 comprise 2 to 12 carbon atoms and are selected from the group consisting of branched alkyl, unbranched alkyl, cycloalkyl or combinations thereof wherein the individual residues R 1 and R 2 are the same or different.
  • FIG. 1 shows a test substrate having a multitude of copper pads to be plated upon. Also depicted are 10 different spots where the layer thickness is measured (circles labelled 1 to 10).
  • the ethylenediamine derivative according to formula (I) will be referred to herein as plating enhancer compound.
  • residues R 1 and R 2 which comprise 2 to 12 carbon atoms and are selected from the group consisting of branched alkyl, unbranched alkyl, cycloalkyl or combinations thereof wherein the individual residues R 1 and R 2 are the same or different.
  • the amine moieties in the plating enhancer compound of formula (I) are secondary amine moieties. It was found by the inventors that the respective diamine or a derivative thereof with methyl residues for R 1 and R 2 do neither allow for sufficient plating rates nor for sufficiently stable gold plating baths (see example 4).
  • the residues R 1 and R 2 of the plating enhancer compound of formula (I) comprise 2 to 8 carbon atoms, more preferred 2 to 6 carbon atoms, even more preferred 2 to 4 carbon atoms.
  • residues R 1 and R 2 in formula (I) are the same.
  • the alkyl residues R 1 and R 2 in formula (I) are free of terminal hydroxy moieties (—OH) as the inventors have found that terminal hydroxy moieties bound thereto are detrimental to stability of the plating bath (see example 4).
  • the residues R 1 and R 2 in formula (I) are free of terminal primary amino moieties as the inventors have found that said terminal amino moieties bound thereto are also detrimental to stability of the plating bath (see example 4).
  • residues R 1 and R 2 are free of any further amino moieties and/or any hydroxy moieties. It is even more preferable that the alkyl residues are free of substituents and consist of carbon and hydrogen atoms only.
  • the plating enhancer compound from the following group consisting of N 1 ,N 2 -diethylethane-1,2-diamine, N 1 ,N 2 -dipropylethane-1,2-diamine, N 1 ,N 2 -di-iso-propylethane-1,2-diamine, N 1 ,N 2 -dibutylethane-1,2-diamine, N 1 ,N 2 -di-iso-butylethane-1,2-diamine, N 1 ,N 2 -di-tert-butylethane-1,2-diamine, N 1 ,N 2 -dipentylethane-1,2-diamine, N 1 ,N 2 -di-iso-pentylethane-1,2-diamine, N 1 ,N 2 -di-sec-pentylethane-1,2-diamine, N 1 ,N 2 -di-tert-pentylethanethane-1,
  • R 1 and R 2 are branched alkyl residues having 3 to 6 carbon atoms. It was surprisingly found that high plating rate in conjunction with even more improved bath stability are obtained when using branched alkyl residues having 3 to 6 carbon atoms for R 1 and R 2 (see example 5).
  • the concentration of the at least one plating enhancer compound according to formula (I) in the electroless aqueous gold plating bath according to the invention preferably ranges from 0.001-1 mol/L, more preferably from 10 to 100 mmol/L, even more preferably from 25 to 75 mmol/L. If more than one plating enhancer compound is contained in the electroless aqueous gold plating bath according to the invention the concentration is based on the total amount of substance of all plating enhancer compounds.
  • the electroless aqueous gold plating bath according to the invention is synonymously named an aqueous solution.
  • aqueous solution means that the prevailing liquid medium, which is the solvent in the solution, is water. Further liquids, that are miscible with water, as for example alcohols and other polar organic liquids, that are miscible with water, may be added. In principle, an aqueous solution comprises more than 50 percent water by weight.
  • the electroless plating bath according to the invention may be prepared by dissolving all components in aqueous liquid medium, preferably in water.
  • the electroless aqueous gold plating bath according to the invention comprises at least one source of gold ions.
  • Gold ions can be in either Au + , Au 3+ or both oxidation states.
  • the source of gold ions can be any water soluble gold salt having said oxidation states.
  • the source of gold ions is selected from the group consisting of gold cyanide, gold ammonium cyanide, gold (I) alkali cyanides including gold (I) potassium cyanide, gold (I) sodium cyanide, trisodium gold disulphite, tripotassium gold disulphite and triammonium gold disulphite, gold thiosulphate, gold thiocyanide, gold sulphate, gold chloride, and gold bromide.
  • the source of gold ions is a gold (I) alkali cyanide and may be added to the aqueous plating bath in the form of a solution containing this salt.
  • concentration of gold ions in the electroless aqueous gold plating bath according to the invention preferably ranges from 0.1 to 10 g/L, more preferably from 0.3 to 6 g/L.
  • the electroless aqueous gold plating bath further comprises at least one reducing agent for gold ions.
  • the reducing agents for gold ions is preferably selected from the group consisting of aliphatic aldehydes such as formaldehyde, acetoaldehyde, propionaldehyde, n-butylaldehyde, ⁇ -methylvaleraldehyde, ⁇ -methylvaleraldehyde, ⁇ -methylvaleraldehyde or the like; aliphatic dialdehydes such as glyoxal, succindialdehdye or the like; aliphatic unsaturated aldehydes such as croton aldehyde or the like; aromatic aldehydes such as benzaldehyde, o-nitrobenzaldehyde, m-nitrobenzaldehyde, p-nitrobenzaldehyde, o-tolylaldehyde, m-tolylalde
  • source of glyoxylic acid encompasses glyoxylic acid and all compounds that can be converted to glyoxylic acid in aqueous solution.
  • aqueous solution the aldehyde containing acid is in equilibrium with its hydrate.
  • a suitable source of glyoxylic acid is dihaloacetic acid, such as dichloroacetic acid, which will hydrolyse in an aqueous medium to the hydrate of glyoxylic acid.
  • An alternative source of glyoxylic acid is the bisulphite adduct as is a hydrolysable ester or other acid derivative. The bisulphite adduct may be added to the electroless aqueous gold plating bath according to the invention or formed in situ.
  • the bisulphite adduct may be made from glyoxylate and either bisulphite, sulphite or metabisulphite.
  • Formaldehyde, sources of glyoxylic acid and glyoxylic acid are preferred, most preferred is formaldehyde.
  • the concentration of the at least one reducing agent for gold ions preferably ranges 0.0001 to 0.5 mol/L, more preferably 0.001 to 0.3 mol/L, even more preferably 0.005 to 0.12 mol/L.
  • reaction products of certain ethyleneamine derivatives such as triethylenetetraamine and reducing agents for gold ions such as formaldehyde (or its oxidised product formic acid) can be formed causing precipitation and reduced plating rates as a consequence.
  • Typical reaction products are for example the respective aminal, enamine and amide derivatives. Therefore, it is preferable to limit the possible extent of undesired reaction product formation by choosing a molar ratio of plating enhancer compound according to formula (I) to reducing agent for gold ions in the electroless aqueous gold plating bath according to the invention to range from 0.5 to 9, preferably from 0.8 to 3.0, more preferably from 1.0 to 2.0 (see Example 6).
  • this ratio is calculated based on the total mass of substance of all respective individual compounds.
  • the electroless aqueous gold plating bath according to the invention optionally further comprises at least one complexing agent.
  • the optional at least one complexing agent present in the electroless aqueous gold plating bath according to the invention is preferably selected from the group consisting of carboxylic acids, hydroxycarboxylic acids, aminocarboxylic acids, aminophosphonic acids or a salt of the aforementioned.
  • the optional at least one complexing agent serves as a complexing agent for gold ions as well as for metal ions dissolved from the substrate during plating, e.g., nickel ions or copper ions.
  • a preferred carboxylic acid is for example oxalic acid or a salt thereof.
  • Preferred hydroxycarboxylic acids are for example tartaric acid, citric acid, lactic acid, malic acid, gluconic acid and salts of the aforementioned.
  • Preferred aminocarboxylic acids are for example glycine, cysteine, methionine and salts of the aforementioned.
  • Preferred aminophosphonic acids are nitrilotri(methylphosphonic acid) (commonly abbreviated as ATMP), diethylenetriaminepentakis(methylphosphonic acid) (commonly abbreviated as DTPMP) and ethylenediaminetetra(methylenphosphonic acid) (commonly abbreviated as EDTMP).
  • ATMP nitrilotri(methylphosphonic acid)
  • DTPMP diethylenetriaminepentakis(methylphosphonic acid)
  • EDTMP ethylenediaminetetra(methylenphosphonic acid)
  • the concentration of the optional at least one complexing agent preferably ranges from 0.1 to 50 g/L, more
  • the electroless aqueous gold plating bath according to the invention comprises two different complexing agents and/or salts thereof, such as a hydroxycarboxylic acid or a salt thereof and an aminocarboxylic acid or a salt thereof.
  • the electroless aqueous gold plating bath according to the invention optionally comprises a crystal adjuster which is selected from the group consisting of thallium ions, arsenic ions, selenium ions and lead ions.
  • crystal adjuster is preferably added to the electroless aqueous gold plating bath according to the invention in a concentration range of 0.00001 to 0.1 g/L.
  • Useful sources for said ions can be water-soluble salts thereof such as the respective nitrates, sulphates and halides.
  • the electroless aqueous gold plating bath according to the invention optionally comprises at least one stabilising agent selected from the group consisting of sources of cyanide ions, hydantoin and alkyl derivatives thereof such as alkylhydantoin and dialkylhydantoin wherein alkyl residues in this context comprise C 1 to C 8 alkyls, preferably methyl, which can be cyclic and/or alicyclic, branched or unbranched, sulphur compounds such as 2-mercaptobenzothiazole, 2-mercaptobenzoimidazole, mercaptoacetic acid, 3-(2-benzthiazolylthio)-1-propanesulphonic acid, mercaptosuccinic acid, thiosulphuric acid, thioglycol, thiourea, thiomalic acid and the like, and aromatic nitrogen compounds such as benzotriazole,1,2,4-aminotriazole and the like.
  • Suitable source of cyanide ions
  • the concentration of the optional stabilising agent can be selected dependant on its chemical structure and can be determined in routine experiments by anyone known in the art.
  • the concentration of the optional stabilising agent preferably ranges 0.0000001 to 0.2 mol/L, it ranges more preferably from 0.000001 to 0.1 mol/L.
  • Such stabilising agents are conventionally added to electroless gold plating baths to improve their lifetime and to prevent plate-out.
  • two or more stabilising agents are used. More preferably, a source of cyanide ions in a concentration of 0.0003 to 5 mmol/L and one or more of hydantoin and alkyl derivatives thereof in a concentration of 10 to 100 mmol/L and/or sulphur compounds in a concentration of 0.000001 to 0.05 mol/L is selected.
  • the electroless aqueous gold plating bath according to the invention is free of intentionally added second sources of reducible metal ions (disregarding trace of impurities commonly present in technical raw materials) allowing for pure gold deposits to be formed.
  • Pure gold deposits are soft, malleable, and particularly suitable for wire bonding and soldering. Traces of impurities are understood as compounds present in a technical raw material of 1 wt.-% or less.
  • the pH of the electroless aqueous gold plating bath according to the invention preferably ranges from 5 to 9, more preferably from 6 to 8, even more preferably from 6.5 to 7.5.
  • the target pH value is adjusted by using for example acids such as phosphoric acid or bases such as sodium hydroxide or potassium hydroxide. It is advantageous and thus preferable to continuously control and adjust the pH value during plating as this also improves the plating bath lifetime.
  • aqueous gold plating baths can be electroless gold plating baths including immersion-type gold plating baths, autocatalytic gold plating baths and gold plating baths using a mixture of autocatalytic and immersion-type plating and electrolytic plating baths.
  • the plating enhancer compound is used in electroless plating baths, preferably comprising at least one source of gold ions and at least one reducing agent for gold ions.
  • the method for depositing a gold layer onto a substrate comprising, in this order, the steps
  • This contacting is preferably accomplished by dipping the substrate or the at least a portion of the surface of substrate into the plating bath or by spraying the plating bath onto the substrate or onto the at least a portion of surface of the substrate.
  • the at least a portion of the surface of the substrate preferably consists of a metal or metal alloy and gold is then deposited onto the at least a portion of the surface of the substrate consisting of a metal or metal alloy, selected from the group consisting of nickel, nickel alloys such as nickel phosphorous alloys, nickel boron alloys, cobalt, cobalt alloys such as cobalt phosphorous alloys, cobalt molybdenum phosphorous alloys, cobalt molybdenum boron alloys, cobalt molybdenum boron phosphorous alloys, cobalt tungsten phosphorous alloys, cobalt tungsten boron alloys, cobalt tungsten boron phosphorous alloys, palladium, palladium alloys such as palladium phosphorous alloys, palladium boron alloys, copper and copper alloys and gold or gold alloys.
  • the electroless aqueous gold plating bath according to the invention can be used to deposit gold layers on gold substrates and
  • the substrates can be pretreated prior to plating, as it is known in the art.
  • Such pretreatment includes cleaning steps with solvents and/or surfactants to remove mostly organic contaminants, etching steps with acids and optionally, oxidising or reducing agents to remove oxides and activation steps.
  • the latter are to deposit a noble metal on the surface or a part thereof to make it more receptive for plating.
  • noble metal can be palladium which can be deposited as a salt before it is reduced to elementary palladium on the surface. Or it can be deposited in a colloidal form and—where appropriate—be subjected to an acceleration step with an acid such as hydrochloric acid to remove any protective colloids such as tin colloids.
  • Such an activation layer normally is not a discrete layer but an aggregation of island structures of palladium. However, activation layers are considered as metal substrates in the context of the present invention.
  • the temperature of the electroless aqueous gold plating bath according to the invention is preferably in the range of 30 to 95° C., more preferably from 70 to 90° C., even more preferably from 75 to 85° C., yet even more preferably from 77 to 84° C. during plating.
  • the plating time is preferably in the range of 1 to 60 min, more preferably in the range of 5 to 30 min. However, if thinner or thicker deposits are desired, the plating time can be outside above-described ranges and adjusted accordingly.
  • components which are being used during plating.
  • Such components are inter alia the source of gold ions, the reducing agent for gold ions, the at least one stabilising agent and the plating enhancer compound.
  • the pH value can be adjusted continuously or in intervals as well.
  • the electroless aqueous gold plating bath according to the invention may be used with horizontal, vertical and spray plating equipment.
  • the aqueous gold plating baths according to the invention allows for sufficient plating rates (deposited thickness of the plated metal layer over time) of 250 nm/h or more (see examples 1 to 3 and 5). Most plating baths known in the art which are somewhat stable do not allow for sufficient plating rates.
  • the aqueous gold plating baths according to the invention form homogeneous gold deposits with little layer thickness diversion.
  • the standard deviation of the gold layer thickness is below 10% or even below 8%. This little deviation is advantageously achievable even when plating on various substrates having different sizes.
  • Pallabond® CLN, Pallabond® ME, PalleBond® Pre Dip, PallaBond® Aktivator and PallaBond® ACT V3 STD are products available from Atotech GmbH.
  • the source of gold ions was in all cases K[Au(CN)2].
  • Printed circuit test boards having a multitude of copper pads of different sizes ranging from 0.25 to 49 mm 2 on both sides were used in all experiments as substrates. They were cleaned and etched prior to activation with palladium. Then, palladium was deposited on the copper surfaces before the gold layer was plated thereon.
  • the different pads where the layer thickness was determined are shown in FIG. 1 .
  • the individual pads had the following areas 1: 0.25 mm 2 , 2: 0.52 mm 2 , 3: 0.68 mm 2 , 4: 0.97 mm 2 , 5: 1.33 mm 2 , 6: 1.35 mm 2 , 7: 3.3 mm 2 , 8: 6.7 mm 2 , 9: 25 mm 2 , 10: 49 mm 2 .
  • the deposit thickness was measured at 10 copper pads on each side of the test boards.
  • the chosen copper pads had different sizes and are used to determine the layer thickness by XRF using the XRF instrument Fischerscope XDV-SDD (Helmut Fischer GmbH, Germany).
  • XRF instrument Fischerscope XDV-SDD Helmut Fischer GmbH, Germany.
  • the plating rate was calculated by dividing the obtained layer thickness by the time necessary to obtain said layer thickness.
  • the layer thickness homogeneity was determined as the standard deviation from the average thickness value.
  • Example 1 (Inventive): N 1 , N 2 -di-iso-propylethane-1,2-diamine as Plating Enhancer Compound
  • a gold plating baths containing the following components was prepared by dissolution of all components in water:
  • potassium hydroxide to adjust pH to range from 7.9 to 8.1 plating enhancer compound 50 mmol/L complexing agent 89 mmol/L 5,5-dimethylhydantoin 47 mmol/L thallium ions 0.01 mmol/L potassium cyanide 0.6 mmol/L Formaldehyde 34.5 mmol/L gold ions 5.1 mmol/L
  • a substrate was subjected to the following process steps (Table 1) by dipping the substrates into the respective solutions employing the given parameters:
  • the gold layers were of lemon yellow colour. Also, the plating rate was very high and well above the desired minimum of 250 nm/h. The layer thickness distribution was very homogeneous, too, with only 5.6% deviation.
  • Example 2 The process as described in Example 1 was repeated wherein the gold plating bath contained 50 mmol/L N 1 ,N 2 -dipropylethane-1,2-diamine instead of 50 mmol/L N 1 ,N 2 -di-iso-propylethane-1,2-diamine.
  • the results are summarized in the following table:
  • the gold layers were of lemon yellow colour. Also, the plating rate was very high and above the desired minimum of 250 nm/h. The layer thickness distribution was very homogeneous, too, with only 6.6% deviation.
  • Example 2 The process as described in Example 1 was repeated wherein the gold plating bath contained N 1 ,N 2 -diethylethane-1,2-diamine instead of N 1 ,N 2 -di-iso-propylethane-1,2-diamine but in the same concentration.
  • the results are summarized in the following table:
  • the gold layers were of lemon yellow colour. Also, the plating rate was very high and clearly above the desired minimum of 250 nm/h. The layer thickness distribution was very homogeneous, too, with only 6.4% deviation.
  • Example 2 The process as described in Example 1 was repeated wherein the gold plating bath contained other compounds as listed in Table 5 instead of N 1 ,N 2 -di-iso-propylethane-1,2-diamine.
  • Table 5 The results for 20 min gold plating are summarized in this table:
  • Layer Plating thickness rate Complete Compound Concentration [nm] [nm/h] plate-out A. 5.61 g/L 6 18 — B. 5.11 g/L 10 30 — C. 5.86 g/L 20 60 — D. 5.26 g/L 28 84 — E. 3.00 g/L 7 21 — F. 4.40 g/L 50 150 ⁇ 3 d G. 7.40 g/L 200 600 ⁇ 1 d H. 7.30 g/L 140 420 3 h
  • Compound A comprised only tertiary amine moieties and did not bear any alkyl residues R 1 and R 2 . Hardly any gold plating took place when using this compound as substitute for a plating enhancer compound in a gold plating bath. The gold layers were also very inhomogeneous and the standard deviation of the layer thickness was 58%.
  • Compound B was an alkylene diamine derivative comprising only primary and tertiary amino moieties (with only methyl residues).
  • the gold plating was very slow when using this compound as substitute for a plating enhancer compound in a gold plating bath.
  • the gold layers were also very inhomogeneous and the standard deviation of the layer thickness was 53%.
  • Compounds C and D are alkanolamine with a tertiary amino moiety only or with only one secondary amino moieties.
  • the gold plating was slow when using these compounds as substitutes for a plating enhancer compound in a gold plating bath.
  • the gold layers were also very inhomogeneous and the standard deviation of the layer thickness was 24% for compound C and 33% for compound D.
  • Compounds E and F did not contain any alkyl residues of sufficient length and when using these compounds as substitutes for a plating enhancer compound in a gold plating bath the plating was slow.
  • Compounds E and F are of similar structure as the plating enhancer compound according to formula (I) but they either have no alkyl residues at all or the alkyl residues are short.
  • the gold layer thicknesses were inhomogeneous having a standard deviation of 14.4% while for compound F the deviation was 6.4%.
  • Compound G bore two terminal hydroxy moieties.
  • the plating rate was high but the stability of the gold plating bath was insufficient. Within less than 1 day the gold plating baths was irrevocably degraded and could not be used for gold plating anymore. The standard deviation of the gold layer thickness was 6.3%.
  • Compound H bore two terminal primary amino moieties. When using this compound as substitute for a plating enhancer compound in a gold plating bath the plating rate was sufficiently high but the stability of the gold plating bath was poor. Within 3 h the gold plating baths was irrevocably degraded. The standard deviation of the gold layer thicknesses was 8.5%.
  • comparative compounds A to F did not allow for sufficient plating rates of gold baths containing these compounds.
  • the plating rates were always even below 200 nm/h and thus not sufficient for today's industrial demands.
  • Example 5 Stability and Life-Time of Gold Plating Baths
  • the gold plating baths of examples 1 to 3 were used to deposit gold on substrates for a prolonged time.
  • the stability of the gold plating baths and the plating rate were monitored over time. If a plate-out occurred the solution was filtered and re-used. Every day during the experiment, the pH value was measured and adjusted to 7.1 with KOH and/or H 3 PO 4 if necessary.
  • the source of gold ions, the source of cyanide ions and the plating enhancer compound were continuously replenished.
  • Table 6 provides information on the stability of gold plating baths containing different plating enhancer compounds.
  • the plating baths were visually inspected directly after make-up (day 0) and for one week on a daily basis.
  • the gold plating baths were also used to deposit gold on substrates every day during this test period. These results are summarized in Table 7.
  • the values given in said table are the deposit thickness in nanometres obtained after 20 min of plating.
  • N 1 ,N 2 -diethylethane-1,2-diamine and N 1 ,N 2 -dipropylethane-1,2-diamine slight precipitates occurred, the plating baths were still able to deposit gold layers without any plating rate reduction.
  • the branched plating enhancer compounds, N 1 ,N 2 -di-iso-propylethane-1,2-diamine showed no precipitates over 7 days and provided good plating rates over the entire tested period. It is thus deduced that plating enhancer compounds having branched alkyl residues result in improved bath stability.
  • a gold plating baths containing the following components was prepared by dissolving all components in water:
  • the gold plating bath was adjusted with KOH/H 3 PO 4 to a pH value of 7.1.
  • a substrate was subjected to the process as described in table 1 wherein the electroless gold plating step was carried out for 10 min only.
  • the highest plating rates can be obtained if the molar ratio of plating enhancer compound and reducing agent for gold ions ranges between 1 or 2 to 1. The plating rate dropped upon further increasing the amount of plating enhancer compound.

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US10975475B2 (en) * 2019-03-06 2021-04-13 C. Uyemura & Co., Ltd. Electroless gold plating bath

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ES2834877T3 (es) * 2018-01-26 2021-06-21 Atotech Deutschland Gmbh Baño de enchapado en oro electrolítico
JP6945050B1 (ja) * 2020-12-01 2021-10-06 日本エレクトロプレイテイング・エンジニヤース株式会社 非シアン系の置換金めっき液及び置換金めっき方法
CN114003009B (zh) * 2021-10-29 2024-01-12 中国联合网络通信集团有限公司 沉铜控制方法、沉铜控制模型的训练方法及装置

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4978559A (en) * 1989-11-03 1990-12-18 General Electric Company Autocatalytic electroless gold plating composition
JP2003277942A (ja) * 2002-03-25 2003-10-02 Okuno Chem Ind Co Ltd 無電解金めっき液
US20090252923A1 (en) * 2006-07-13 2009-10-08 Telecom Italia S.P.A. Ink jet cartridge comprising a layer made by a curable resin composition
US20130116172A1 (en) * 2010-05-13 2013-05-09 Marcadia Biotech, Inc. Glucagon superfamily peptides exhbiting g protein coupled receptor activity
WO2016031723A1 (ja) * 2014-08-25 2016-03-03 小島化学薬品株式会社 還元型無電解金めっき液及び当該めっき液を用いた無電解金めっき方法

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5526459B2 (ja) 2006-12-06 2014-06-18 上村工業株式会社 無電解金めっき浴及び無電解金めっき方法
JP5013077B2 (ja) * 2007-04-16 2012-08-29 上村工業株式会社 無電解金めっき方法及び電子部品
JP4831710B1 (ja) * 2010-07-20 2011-12-07 日本エレクトロプレイテイング・エンジニヤース株式会社 無電解金めっき液及び無電解金めっき方法

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4978559A (en) * 1989-11-03 1990-12-18 General Electric Company Autocatalytic electroless gold plating composition
JP2003277942A (ja) * 2002-03-25 2003-10-02 Okuno Chem Ind Co Ltd 無電解金めっき液
US20090252923A1 (en) * 2006-07-13 2009-10-08 Telecom Italia S.P.A. Ink jet cartridge comprising a layer made by a curable resin composition
US20130116172A1 (en) * 2010-05-13 2013-05-09 Marcadia Biotech, Inc. Glucagon superfamily peptides exhbiting g protein coupled receptor activity
WO2016031723A1 (ja) * 2014-08-25 2016-03-03 小島化学薬品株式会社 還元型無電解金めっき液及び当該めっき液を用いた無電解金めっき方法
US20160230287A1 (en) * 2014-08-25 2016-08-11 Kojima Chemicals Co., Ltd. Reductive electroless gold plating solution, and electroless gold plating method using the plating solution

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10975475B2 (en) * 2019-03-06 2021-04-13 C. Uyemura & Co., Ltd. Electroless gold plating bath

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WO2017050662A1 (en) 2017-03-30
TWI709663B (zh) 2020-11-11
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TW201720955A (zh) 2017-06-16

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