WO2022234113A1 - Method for producing an electrodeposited copper foil and copper foil obtained therewith - Google Patents
Method for producing an electrodeposited copper foil and copper foil obtained therewith Download PDFInfo
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- WO2022234113A1 WO2022234113A1 PCT/EP2022/062331 EP2022062331W WO2022234113A1 WO 2022234113 A1 WO2022234113 A1 WO 2022234113A1 EP 2022062331 W EP2022062331 W EP 2022062331W WO 2022234113 A1 WO2022234113 A1 WO 2022234113A1
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- copper foil
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- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 title claims abstract description 124
- 239000011889 copper foil Substances 0.000 title claims abstract description 105
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 21
- 239000003792 electrolyte Substances 0.000 claims abstract description 100
- 229920000642 polymer Polymers 0.000 claims abstract description 42
- 239000004721 Polyphenylene oxide Substances 0.000 claims abstract description 32
- 229920000570 polyether Polymers 0.000 claims abstract description 32
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 claims abstract description 30
- 229910052802 copper Inorganic materials 0.000 claims abstract description 23
- 239000010949 copper Substances 0.000 claims abstract description 23
- -1 halogen ion Chemical class 0.000 claims abstract description 20
- 229910052736 halogen Inorganic materials 0.000 claims abstract description 19
- 238000005323 electroforming Methods 0.000 claims abstract description 14
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical compound [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 claims abstract description 8
- 229910001431 copper ion Inorganic materials 0.000 claims abstract description 8
- 238000009751 slip forming Methods 0.000 claims abstract description 4
- 238000000034 method Methods 0.000 claims description 39
- 230000003746 surface roughness Effects 0.000 claims description 38
- 239000000203 mixture Substances 0.000 claims description 20
- 230000007547 defect Effects 0.000 claims description 17
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 10
- 230000000007 visual effect Effects 0.000 claims description 8
- 239000002202 Polyethylene glycol Substances 0.000 claims description 6
- 229920001223 polyethylene glycol Polymers 0.000 claims description 6
- 229920001451 polypropylene glycol Polymers 0.000 claims description 6
- 229910000365 copper sulfate Inorganic materials 0.000 claims description 5
- ARUVKPQLZAKDPS-UHFFFAOYSA-L copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 claims description 5
- CPELXLSAUQHCOX-UHFFFAOYSA-M Bromide Chemical compound [Br-] CPELXLSAUQHCOX-UHFFFAOYSA-M 0.000 claims description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 3
- 229920002873 Polyethylenimine Polymers 0.000 claims description 3
- 229940006460 bromide ion Drugs 0.000 claims description 3
- 238000010924 continuous production Methods 0.000 claims description 3
- 229920001577 copolymer Polymers 0.000 claims description 3
- 229920000083 poly(allylamine) Polymers 0.000 claims description 3
- 229920000036 polyvinylpyrrolidone Polymers 0.000 claims description 3
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 claims description 3
- 239000001267 polyvinylpyrrolidone Substances 0.000 claims description 3
- OBDVFOBWBHMJDG-UHFFFAOYSA-M 3-sulfanylpropane-1-sulfonate Chemical compound [O-]S(=O)(=O)CCCS OBDVFOBWBHMJDG-UHFFFAOYSA-M 0.000 abstract description 5
- 230000000052 comparative effect Effects 0.000 description 8
- 239000007857 degradation product Substances 0.000 description 8
- 238000000151 deposition Methods 0.000 description 8
- 239000003292 glue Substances 0.000 description 8
- 230000008021 deposition Effects 0.000 description 7
- 239000011888 foil Substances 0.000 description 7
- 208000012868 Overgrowth Diseases 0.000 description 6
- 230000015556 catabolic process Effects 0.000 description 6
- 238000006731 degradation reaction Methods 0.000 description 6
- 239000000654 additive Substances 0.000 description 5
- 238000012733 comparative method Methods 0.000 description 5
- 230000001747 exhibiting effect Effects 0.000 description 5
- 238000009825 accumulation Methods 0.000 description 4
- 239000004020 conductor Substances 0.000 description 4
- 230000000875 corresponding effect Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 230000007774 longterm Effects 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 3
- 230000001939 inductive effect Effects 0.000 description 3
- 238000010295 mobile communication Methods 0.000 description 3
- 238000002161 passivation Methods 0.000 description 3
- 238000007747 plating Methods 0.000 description 3
- 230000001629 suppression Effects 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 150000001879 copper Chemical class 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 230000008025 crystallization Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 239000000428 dust Substances 0.000 description 2
- 230000002500 effect on skin Effects 0.000 description 2
- 230000002708 enhancing effect Effects 0.000 description 2
- 150000004676 glycans Chemical class 0.000 description 2
- 239000003112 inhibitor Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229920002959 polymer blend Polymers 0.000 description 2
- 229920001282 polysaccharide Polymers 0.000 description 2
- 239000005017 polysaccharide Substances 0.000 description 2
- 230000000644 propagated effect Effects 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 230000007847 structural defect Effects 0.000 description 2
- 239000004094 surface-active agent Substances 0.000 description 2
- UMGDCJDMYOKAJW-UHFFFAOYSA-N thiourea Chemical compound NC(N)=S UMGDCJDMYOKAJW-UHFFFAOYSA-N 0.000 description 2
- 239000010936 titanium Substances 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Natural products NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 229910003460 diamond Inorganic materials 0.000 description 1
- 239000010432 diamond Substances 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000004070 electrodeposition Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000005305 interferometry Methods 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- VFZWCTYGZWDQGK-UHFFFAOYSA-N n-benzylhexan-1-amine Chemical class CCCCCCNCC1=CC=CC=C1 VFZWCTYGZWDQGK-UHFFFAOYSA-N 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 150000002898 organic sulfur compounds Chemical class 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 230000003381 solubilizing effect Effects 0.000 description 1
- 238000012358 sourcing Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D1/00—Electroforming
- C25D1/04—Wires; Strips; Foils
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D21/00—Processes for servicing or operating cells for electrolytic coating
- C25D21/12—Process control or regulation
- C25D21/14—Controlled addition of electrolyte components
-
- 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
- C25D3/38—Electroplating: Baths therefor from solutions of copper
Definitions
- the present invention generally relates to the field of electrodeposited copper foils and more specifically to electrodeposited copper foils with low surface roughness.
- the process and production of electrodeposited copper foil for use in printed circuit boards is basically a plating technique, as it involves arranging two electrodes (a cathode and an anode) in an electrolyte containing a copper salt, passing current between the electrodes and depositing copper on the cathode with a desired thickness.
- the electrodeposited copper foil is then peeled off from the surface of the cathode, and coiled onto a storage reel.
- the cathode is generally a rotating drum-shaped cathode and is arranged in the electrolyte to face a stationary anode.
- the profile (mountain/valley) shape of the surface of the copper foil that is in contact with the electrolyte is deformed, which results in an increased surface roughness.
- Matte sides of electrodeposited copper foils generally present a surface roughness (as of Rz ISO) well above 0.80 pm, and commonly above 3.0 pm.
- a higher surface roughness of a copper foil induces a higher signal loss in high speed/high frequency applications. This is due to the fact that at high frequency the signal is propagated only at the surface of the conductor (due to a so-called “skin effect”). On a smoother conductor, the propagation route of the signal is therefore shorter, inducing lower loss.
- chloride ions may, e.g., be added to the electrolyte and the dust and/or oil may be removed by passing the electrolyte through a filter containing active carbon or the like.
- glue in order to adjust the surface roughness of the matte side and prevent micro porosities, it has long been the practice to add glue to the electrolyte and various organic and inorganic additives, apart from glue, have also been proposed.
- Lowering of the profile of the matte side can also be achieved by adding to the electrolyte large quantities of a so-called brightener, such as glue and/or thiourea, for example, but as the amount of these additives is increased, there is an abrupt lowering of the room-temperature elongation rate and high-temperature elongation rate of the electrodeposited copper foil, thus resulting in a degradation of its mechanical properties.
- WO 97/11210 A1 discloses an electrolyte comprising 3-mercapto-1 -propane sulfonate, chloride ions, a high molecular weight polysaccharide and a low molecular weight glue.
- Produced copper foils exhibit good tensile strength and elongation, both at room-temperature and at high temperature.
- copper foils electrodeposited using the electrolyte of WO 97/11210 A1 hardly present a surface roughness (Rz) in the order of 1.3 pm, and the electrodeposition process may be difficult to control due to variations in naturally-sourced glue and polysaccharide used as additives.
- EP 1 574599 A1 and EP 1 568802 A1 disclose the use of electrolytes comprising an organosulfur compound and a quaternary amine salt to obtain low-profile electrolytic copper foils, exhibiting a low surface roughness on their matte side. However, only surface roughness (Rz) in the order of 1-1.3 pm was achieved.
- CN 111394754 A discloses an electrolyte and a process using the electrolyte for the production of copper foils suitable for application in the field of the Fifth- Generation of mobile communication.
- the electrolyte of CN 111394754 A proposes the use of hexylbenzylamine salt as so-called leveler in order to improve the smoothness of the matte side. While good mechanical properties, such as satisfying bonding forces, have been achieved for the copper foils, their respective surface roughness (Rz) was not decreased below 1.15 pm.
- the present invention proposes a method for producing an electrodeposited copper foil, the electrodeposited copper foil being continuously formed in an electroforming cell comprising a rotating drum-shaped cathode, a stationary anode and an electrolyte.
- the present method allows forming in the electroforming cell an electrodeposited copper foil with a matte side having a roughness Rz ISO of 0.8 pm and below.
- Rz ISO refers to the roughness Rz determined according to ISO standard, as compared e.g. to Rz JIS determined according to Japanese standard.
- the electrolyte comprises:
- a nitrogen-containing polymer leveler at a concentration comprised between 5 and 12 ppm, the nitrogen-containing polymer having an average molecular weight Mw comprised between 1 000 and 30000 g/mol;
- polyether suppressor at a concentration comprised between 15 and 30 ppm, the polyether suppressor having an average molecular weight Mw comprised between 500 and 12000 g/mol.
- the expression average molecular weight Mw refers to the weight average molecular weight of a polymer, by opposition to its number average molecular weight Mn or its viscosity average molecular weight Mv.
- the weight average molecular weight of a polymer depends not only on the number of molecules present, but also on the weight of each molecule, so a larger molecule will have a larger contribution than a smaller molecule.
- the average molar weight Mw is conventionally calculated as follows: where Ni is the number of molecules of molecular weight Mi, i being an integer.
- concentrations correspond to the concentrations of the respective various components of the electrolyte being provided to the electroforming cell.
- the electrolyte is continuously supplied with the various components during operation of the electroforming cell to ensure that the concentrations of the various components are always in the prescribed respective ranges.
- Copper ions, halogen ions, 3-mercapto-1 -propane sulfonate, nitrogen-containing polymer leveler and polyether suppressor can be added to the electrolyte as such, or they can be added to the electrolyte as any suitable derivative compounds resulting in the obtention of the desired respective component in the electrolyte. This applies for copper ions and halogen ions, which are commonly added to the electrolyte as a copper salt or halogen salt respectively, but also for any other component comprised in the electrolyte according to the invention.
- 3-mercapto-1 -propane sulfonate may be referred to as MPS or as brightener.
- a brightener is more generally known in the field of copper deposition as an accelerant, and increases the rate of copper deposition during production of an electrodeposited copper foil.
- the electrolyte further comprises a nitrogen-containing polymer leveler.
- a leveler exerts a strong suppression effect on copper deposition reactions in the presence of halogen ions.
- the polyether suppressor may be simply referred to as suppressor, or surfactant.
- a suppressor also exerts a strong suppression effect on copper deposition reactions in the presence of halogen ions, however with respect to a leveler, the suppressor acts in a relatively wider copper deposition current region, and can be deactivated by the use of the brightener (or accelerant).
- Suppressors are inhibitors which are weakly adsorbed on the surface of electrodeposited copper foils in combination with halogen ions and are not consumed or chemically transformed on the metal surface.
- levelers are inhibitors that are strongly adsorbed and are consumed on the metal surface.
- the invention is based on the findings by the inventors that a specific combination of brightener, leveler and suppressor of different kinds at prescribed concentrations make it possible to obtain electrodeposited copper foils exhibiting the low surface roughness which has been sought for a long time, while being free of visual/surface defects, such as e.g. overgrowth, grooves, holes, craters and loss of brightness.
- the method according to the invention uses prescribed brightener, leveler and suppressor in specific concentrations to produce electrodeposited copper foils, which are free from surface defects and have a surface roughness Rz ISO of 0.8 pm and below ( ⁇ 0.8 pm) on the matte side.
- the inventors have found that the process reliably can be improved by replacing conventional low-molecular weight glue by a polyether.
- the production process is easier to control since the behavior of polyether is more consistent than the one of a low molecular weight glue.
- the inventors also discovered that the problem of too high roughness of known electrodeposited copper foils is solved by the use of a nitrogen- containing polymer leveler in the electrolyte.
- the copper foils produced with the inventive method have a significantly reduced surface roughness compared to what was obtained in the prior art. Indeed, copper foils produced with the inventive method have a surface roughness Rz ISO of no more than 0.8 pm, corresponding to a surface roughness Rz JIS of no more than 0.6 pm.
- the surface developed ratio (SDR) of an electrodeposited copper foil produced by the present inventive method is also reduced from 0.4% for prior art to 0.15% or even below, such as 0.1%.
- the surface developed ratio (SDR) corresponds to the ratio between the area of the real developed surface and the area of the projected surface.
- the real surface is the surface of the produced electrolytic copper foil considering its surface roughness while the projected surface is the surface of a corresponding flat, completely smooth foil.
- the SDR can be calculated as follows:
- the obtained electrodeposited copper foils may generally be subjected to further subsequent treatment steps.
- a surface bond enhancing treatment and a passivation are deposited on the matte side of the electrodeposited copper foil.
- the reduction of surface roughness allows a more homogenous deposition of the treatment and passivation, inducing improved properties for the final product (such as an increased peel strength with insulating resin substrate, higher shelf life of copper foil).
- the reduced roughness of copper foils produced according to the inventive method induces lower signal loss in high speed/high frequency applications. This is due to the fact that at high frequency the signal is propagated only at the surface of the conductor (skin effect). On a smooth conductor the propagation route of the signal is therefore shorter, inducing lower loss. This enable the fabrication of effective transmission lines for applications at frequencies of 77 GHz and above (5G, etc.)
- the ultra-low roughness electrodeposited copper foils produced according to the invention have mechanical properties similar to conventional copper foils.
- the obtained electrodeposited copper foils may have an elongation of between 10 and 25 % at 20°C for foils having a thickness of 18 pm, and between 15 and 35 % at 20°C for foils having a thickness of 35 pm.
- the tensile strength may be between 28 and 37 kgf/mm 2 at 20°C regardless of the thickness.
- Electrodeposited copper foils produced by the method according to the invention or using an electrolyte according to the invention are however not limited to these two thicknesses, and copper foils of various thickness may be obtained. According to some embodiments, copper foils having a thickness of 9 to 70 pm may be produced.
- the drum side of electrodeposited copper foil has a roughness that depends on the drum itself.
- the electrodeposited copper foil may have a conventional roughness, e.g. in the order of 0.9 to 1.8 pm.
- polyether suppressor having an average molecular weight Mw comprised between 500 and 12000 g/mol reduces the formation of insoluble degradation products responsible for the degradation of the electrodeposited copper foil after several days of operating the production method, while ensuring a sufficient suppression effect to reduce the surface roughness of the copper foil.
- polyether suppressor concentration in the electrolyte from 15 to 30 ppm, allows to achieve the target surface roughness of electrodeposited copper foils while ensuring the long-term stability of the electrolyte, also by avoiding the accumulation of degradation products which lead to a degradation of copper foil aspect within several days.
- Formation of overgrowth defects on electrodeposited copper foils is advantageously prevented by controlling the formation of nitrogen-containing polymer leveler degradation products.
- used nitrogen-containing polymer leveler has an average molecular weight Mw comprised between 1000 and 30000 g/mol, and its concentration should not exceed 12 ppm.
- the electrolyte comprises at least 5 ppm of nitrogen-containing polymer leveler.
- the average molecular weight Mw of the nitrogen-containing polymer leveler is comprised between 1 500 and 15000 g/mol, preferably between 2000 and 5000 g/mol. Additionally or alternatively, the nitrogen- containing polymer leveler is present in the electrolyte at a concentration comprised between 6 and 11 ppm, preferably between 7 and 10 ppm.
- the nitrogen-containing polymer leveler may comprise or consist of one or more polymers.
- the nitrogen-containing polymer leveler is selected from polyvinylpyrrolidone, polyallylamine, polyethyleneimine, and mixtures thereof.
- the concentration of nitrogen-containing polymer leveler in the electrolyte corresponds to the total concentration of all polymers forming the mixture, and each one of the polymer forming the mixture has an average molecular weight Mw comprised between 1000 and 30000 g/mol, preferably between 1500 and 15000 g/mol, more preferably between 2000 and 5000 g/mol.
- polymers forming the mixture may have higher or lower average molecular weights, but the polymer mixture has an average molecular weight Mw comprised between 1000 and 30000 g/mol, preferably between 1500 and 15000 g/mol, more preferably between 2000 and 5000 g/mol.
- the average molecular weight Mw of the polyether suppressor is comprised between 500 and 6000 g/mol, preferably between 1000 and 3500 g/mol. Additionally or alternatively, the polyether suppressor is present at a concentration comprised between 12 and 28 ppm, preferably between 15 and 25 ppm.
- the polyether suppressor may comprise or consist of one or more polymers.
- the polyether suppressor is selected from polyethylene glycol, polypropylene glycol, copolymers of polyethylene glycol and polypropylene glycol, and mixtures thereof.
- the concentration of polyether suppressor in the electrolyte corresponds to the total concentration of all polymers forming the mixture, and each one of the polymer forming the mixture has an average molecular weight Mw comprised between 500 and 12000 g/mol, preferably between 500 and 6000 g/mol, more preferably between 1000 and 3500 g/mol.
- polymers forming the mixture may have higher or lower average molecular weights, but the polymer mixture has an average molecular weight Mw comprised between 500 and 12000 g/mol, preferably between 500 and 6000 g/mol, more preferably between 1000 and 3500 g/mol.
- copper is added to the electrolyte as copper sulfate.
- the copper is present in the electrolyte at a concentration comprised between 60 and 100 g/L, preferably between 70 and 90 g/L.
- the halogen ion is a chloride and/or bromide ion, and/or the halogen ion is present in the electrolyte at a concentration comprised between 35 and 50 ppm.
- the electrolyte may further comprise sulfuric acid at a concentration comprised between 65 and 85 g/L, preferably between 70 and 80 g/L.
- sulfuric acid at such concentrations has the advantageous effect of reducing the electric resistance between the anode and the cathode, thereby decreasing the electric power and electric consumption needed to produce the electrodeposited copper foil. Production costs may therefore be reduced.
- the electrodeposited copper foil is formed by applying a current density between the cathode and the anode, the current density being comprised between 40 and 80 A/dm 2 , preferably between 40 and 60 A/dm 2 , more preferably between 45 and 55 A/dm 2 .
- Such current densities advantageously allow for a strong levelling effect of the electrolyte used in the method according to the invention. Moreover, using such current densities advantageously allow for a faster copper deposition, with respect to the use of lower current densities, which enhances the productivity.
- the electrolyte preferably is maintained at a temperature higher than 50 °C to prevent copper sulfate crystallization in the electrolyte. More preferably the temperature of the electrolyte is comprised between 50 and 60 °C, in order to simultaneously enhance copper dissolution and to both prevent copper sulfate crystallization and degradation of the surface roughness of the electrodeposited copper foil.
- the method is a continuous process and the electrolyte has an endless life time, i.e. degradation products and by-products formed during the use of the electrolyte in the method according to the invention do not affect the quality of the produced electrolytic copper foil, in particular the brightness of the electrolytic copper foil is not altered.
- the quality of the produced electrolytic copper foil in particular its brightness and its surface roughness, is not impaired by accumulation in the electrolyte of reaction by-products or degradation products, such as e.g. degradation products of the leveler, the suppressor or the brightener.
- the electrolyte has a life-time of more than three days, preferably more than seven days, more preferably more than fifteen days. Such a long life-time of the electrolyte enables the production of electrodeposited copper foils with constant properties, i.e. without any quality loss in the production over a few days of utilization of the electrolyte.
- the invention concerns an electrolyte for the production of an electrodeposited copper foil comprising:
- the invention also concerns an electrodeposited copper foil, in particular as produced by the inventive method or produced by using the inventive electrolyte, the electrodeposited copper foil having a bright electrolyte side, with a surface roughness Rz of 0.8 pm and below, a surface developed ratio below 0.15%, preferably of 0.1%, and being free of structural defects.
- any given numeric value covers a range of values form - 10 % to + 10% of said numeric value, preferably a range of values form -5 % to +5 % of said numeric value, more preferably a range of values form -1 % to +1 % of said numeric value.
- Figure 1 is a schematic view of an electroforming cell
- Figure 2 is a SEM (Scanning Electron Microscope) view of an electrodeposited copper foil produced by a method according to the invention
- Figure 3 is a SEM view of an electrodeposited copper foil produced by a first comparative method and exhibiting overgrowth defects
- Figure 4 is a SEM view of an electrodeposited copper foil produced by a second comparative method and exhibiting craters.
- the present invention provides a method for producing an electrodeposited copper foil, the electrodeposited copper foil being continuously formed in an electroforming cell, as well as an electrolyte for the production of an electrodeposited copper foil, the produced copper foil having a very low surface roughness and being free of defects.
- An electrodeposited copper foil is produced by using an electroforming cell 10 (referred as plating machine in the industry) as shown in Fig.1 to produce a copper foil 18.
- an electrolyte 12 is passed through an apparatus comprising a drum-shaped cathode 14 (the surface of which is made of stainless steel or titanium) which is rotating and a stationary anode 16 (a lead or a titanium electrode covered by a precious metal oxide) which is provided opposite the cathode 14.
- An electric current is passed through both electrodes 14, 16 to deposit copper on the surface of the cathode 14 with a desired thickness, thus forming an electrodeposited copper foil 18.
- the electrodeposited copper foil 18 is then peeled off from the surface of the cathode 14 and coiled onto a storage reel 20.
- the foil thus prepared is generally referred to as untreated copper foil.
- the electrodeposited copper foil 18 may be subjected to an electrochemical or chemical surface treatment, such as a bond enhancing treatment and/or a passivation treatment (not shown).
- Electrodeposited copper foils were produced using either a method according to the invention (examples 1 to 6) or a comparative method (comparative examples 1 to 6) not forming part of the invention.
- the method according to the invention and the comparative method differ from each other only by the composition of the electrolyte. According to both methods, the electrolyte is maintained at a temperature of 55 °C and the current density applied between the cathode and the anode is 50 A/dm 2 .
- Electrolyte compositions for the various examples are presented in Table 1, and electrolyte compositions for various comparative examples are presented in Table 2.
- MPS stands for 3-mercapto-1 -propane sulfonate in Table 1 and Table 2.
- each electrolyte is prepared by solubilizing, in a suitable amount of water, the compounds shown in Table 1 and Table 2.
- Each electrolyte also includes copper, which is dissolved in the electrolyte with sulfuric acid by oxidizing metallic copper.
- the copper concentration is 80 g/l.
- the obtained electrodeposited copper foils were then analysed to determine their surface characteristics at the matte side, such as surface roughness (as of Rz ISO) and surface developed ratio (SDR) and to detect the presence of visual defects.
- surface characteristics at the matte side such as surface roughness (as of Rz ISO) and surface developed ratio (SDR) and to detect the presence of visual defects.
- Electrodeposited copper foils are analysed as follows:
- the roughness of copper foils is measured with a contact profilometer consisting of a diamond needle (stylus) sliding on the surface. From this measurement a 2D profile of the surface is created, and Rz is calculated as the average distance between the highest peak and lowest valley over 8 sampling lengths.
- the surface roughness Rz refers to ISO 4287:1997.
- SDR surface developed ratio
- the principle is to divide a light beam in two paths, directing one to a reference mirror and the other one to the sample surface. This measurement beam travel different distances depending on the surface profile.
- the two waveforms are then recombined and create specific interference patterns depending on their phase difference. Those patterns are analyzed to calculate the height of the sample at each point (pixel) scanned. Roughness parameters are then calculated from this 3D profile.
- the surface roughness SDR refers to ISO 2517 and is typically measured on a 200 x 1000 pm sample surface. Determining visual defects
- Produced electrodeposited copper foils are controlled using an optical microscope to detect whether they present structural defects. Scanning electron microscope might be used afterwards to identify the type of defect ( craters and/or overgrowth defects). The loss of brightness is controlled through the visual aspect of the foil and is correlated with an abrupt increase of Rz (above 2.0 pm).
- All copper foils produced by using electrolytes according to the invention have a surface roughness comprised between 0.7 and 0.8 pm, a SDR comprised between 0.10 and 0.15 %, and are free of visual and surface defects (see Table 1 and Fig.2, corresponding to example 5).
- overgrowth defects is also observed when using nitrogen- containing polymer with an average molecular weight higher than 30000 g/mol (comparative example 4). Moreover, in this case, target surface roughness could not be achieved and produced copper foil had a surface roughness Rz ISO of 5.1 pm and a SDR of 10.8 %.
- electrolyte compositions corresponding to the present invention i.e. comprising a halogen ion, a polyether (as suppressor agent) and a nitrogen- containing polymer (as leveller agent) with the prescribed average molecular weights Mw, and within the prescribed concentrations, allow to achieve the desired reduction in the surface roughness of electrodeposited copper foils without the appearance of visual / surface defects.
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- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Automation & Control Theory (AREA)
- Electrolytic Production Of Metals (AREA)
- Electroplating And Plating Baths Therefor (AREA)
Abstract
Description
Claims
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN202280033267.3A CN117280080A (en) | 2021-05-07 | 2022-05-06 | Method for producing electrodeposited copper foil and copper foil obtained by the method |
EP22727926.2A EP4334511A1 (en) | 2021-05-07 | 2022-05-06 | Method for producing an electrodeposited copper foil and copper foil obtained therewith |
JP2023568151A JP2024517002A (en) | 2021-05-07 | 2022-05-06 | Method for producing electrodeposited copper foil and copper foil obtained by the method |
KR1020237042061A KR20240021780A (en) | 2021-05-07 | 2022-05-06 | Method for manufacturing electrolytic copper foil and copper foil obtained thereby |
US18/289,024 US20240209537A1 (en) | 2021-05-07 | 2022-05-06 | Method for producing an electrodeposited copper foil and copper foil obtained therewith |
Applications Claiming Priority (2)
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LU500134A LU500134B1 (en) | 2021-05-07 | 2021-05-07 | Method for producing an electrodeposited copper foil and copper foil obtained therewith |
LULU500134 | 2021-05-07 |
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WO2022234113A1 true WO2022234113A1 (en) | 2022-11-10 |
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PCT/EP2022/062331 WO2022234113A1 (en) | 2021-05-07 | 2022-05-06 | Method for producing an electrodeposited copper foil and copper foil obtained therewith |
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US (1) | US20240209537A1 (en) |
EP (1) | EP4334511A1 (en) |
JP (1) | JP2024517002A (en) |
KR (1) | KR20240021780A (en) |
CN (1) | CN117280080A (en) |
LU (1) | LU500134B1 (en) |
WO (1) | WO2022234113A1 (en) |
Citations (8)
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WO1997011210A1 (en) | 1995-09-22 | 1997-03-27 | Circuit Foil S.A. | Method for producing electrodeposited copper foil and copper foil obtained by same |
EP1257693A1 (en) * | 2000-02-24 | 2002-11-20 | Circuit Foil Luxembourg Trading S.a.r.l. | Composite copper foil and manufacturing method thereof |
EP1568802A1 (en) | 2002-10-21 | 2005-08-31 | Nikko Materials Company, Limited | Copper electrolytic solution containing organic sulfur compound and quaternary amine compound of specified skeleton as additives and electrolytic copper foil produced therewith |
EP1574599A1 (en) | 2002-12-18 | 2005-09-14 | Nikko Materials Co., Ltd. | Copper electrolytic solution and electrolytic copper foil produced therewith |
US20060191798A1 (en) * | 2003-04-03 | 2006-08-31 | Fukuda Metal Foil & Powder Co., Ltd. | Electrolytic copper foil with low roughness surface and process for producing the same |
US20070287020A1 (en) * | 2006-06-07 | 2007-12-13 | Furukawa Circuit Foil Co., Ltd. | Surface treated electrodeposited copper foil, the production method and circuit board |
CN110629257A (en) * | 2019-07-05 | 2019-12-31 | 九江德福科技股份有限公司 | Manufacturing method of high-tensile-strength lithium-ion battery copper foil |
CN111394754A (en) | 2020-04-30 | 2020-07-10 | 东强(连州)铜箔有限公司 | Copper foil additive for fifth-generation mobile communication board, copper foil and production process of copper foil |
-
2021
- 2021-05-07 LU LU500134A patent/LU500134B1/en active IP Right Grant
-
2022
- 2022-05-06 EP EP22727926.2A patent/EP4334511A1/en active Pending
- 2022-05-06 WO PCT/EP2022/062331 patent/WO2022234113A1/en active Application Filing
- 2022-05-06 US US18/289,024 patent/US20240209537A1/en active Pending
- 2022-05-06 CN CN202280033267.3A patent/CN117280080A/en active Pending
- 2022-05-06 KR KR1020237042061A patent/KR20240021780A/en unknown
- 2022-05-06 JP JP2023568151A patent/JP2024517002A/en active Pending
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1997011210A1 (en) | 1995-09-22 | 1997-03-27 | Circuit Foil S.A. | Method for producing electrodeposited copper foil and copper foil obtained by same |
EP1257693A1 (en) * | 2000-02-24 | 2002-11-20 | Circuit Foil Luxembourg Trading S.a.r.l. | Composite copper foil and manufacturing method thereof |
EP1568802A1 (en) | 2002-10-21 | 2005-08-31 | Nikko Materials Company, Limited | Copper electrolytic solution containing organic sulfur compound and quaternary amine compound of specified skeleton as additives and electrolytic copper foil produced therewith |
EP1574599A1 (en) | 2002-12-18 | 2005-09-14 | Nikko Materials Co., Ltd. | Copper electrolytic solution and electrolytic copper foil produced therewith |
US20060191798A1 (en) * | 2003-04-03 | 2006-08-31 | Fukuda Metal Foil & Powder Co., Ltd. | Electrolytic copper foil with low roughness surface and process for producing the same |
US20070287020A1 (en) * | 2006-06-07 | 2007-12-13 | Furukawa Circuit Foil Co., Ltd. | Surface treated electrodeposited copper foil, the production method and circuit board |
CN110629257A (en) * | 2019-07-05 | 2019-12-31 | 九江德福科技股份有限公司 | Manufacturing method of high-tensile-strength lithium-ion battery copper foil |
CN111394754A (en) | 2020-04-30 | 2020-07-10 | 东强(连州)铜箔有限公司 | Copper foil additive for fifth-generation mobile communication board, copper foil and production process of copper foil |
Also Published As
Publication number | Publication date |
---|---|
EP4334511A1 (en) | 2024-03-13 |
US20240209537A1 (en) | 2024-06-27 |
CN117280080A (en) | 2023-12-22 |
KR20240021780A (en) | 2024-02-19 |
JP2024517002A (en) | 2024-04-18 |
LU500134B1 (en) | 2022-11-08 |
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