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EP-4735673-A1 - ELECTROPLATING APPARATUS AND METHOD FOR PRODUCING AN ELECTROPLATED COPPER FOIL USING THE SAME

EP4735673A1EP 4735673 A1EP4735673 A1EP 4735673A1EP-4735673-A1

Abstract

The invention relates to a method for producing an electrolytic copper foil, comprising the steps of forming a copper foil in an electroplating cell comprising a tank with a copper electrolyte, a rotating cathode drum made of titanium or of a titanium alloy and an anode, wherein the copper foil is continuously formed on the cathode and removed therefrom, further comprising a treatment step, wherein a plasma jet is applied onto the exposed surface of the rotating cathode drum during production of the copper foil. The present invention also relates to an electroplating apparatus for performing such a method and comprising a metallic drum-shaped rotating cathode made of titanium or of a titanium alloy, a stationary anode, and a tank for an electrolyte wherein the cathode and the anode are arranged spaced apart from each other in the tank. According to the invention, the apparatus further comprises a plasma generating device configured to generate an atmospheric plasma in a plasma chamber having an outlet facing the cathode such that a plasma jet irradiates at least a portion of a surface of the cathode to treat the latter against hydride corrosion.

Inventors

  • MAUCHAUFFÉ, Rodolphe
  • CHOQUET, PATRICK
  • DEVAHIF, Thomas
  • LEMAIRE, Alexandre
  • MOUZON, Julie

Assignees

  • Circuit Foil Luxembourg
  • Luxembourg Institute of Science and Technology

Dates

Publication Date
20260506
Application Date
20240626

Claims (20)

  1. 1 . A method for producing an electrolytic copper foil, comprising forming a copper foil in an electroplating cell comprising a tank with a copper electrolyte, a rotating cathode drum and an anode, wherein the copper foil is continuously formed on the cathode drum and removed therefrom, wherein the cathode drum is made of titanium or of a titanium alloy, characterized by performing an anti-hydride treatment step during the production of the copper foil, wherein an atmospheric plasma jet is applied onto the exposed surface of the rotating cathode drum.
  2. 2. The method according to claim 1 , wherein the plasma jet has an electron temperature comprised between 4000 and 11000 K, preferably between 6500 and 9000 K.
  3. 3. The method according to claim 1 or 2, wherein the plasma jet is continuously applied onto the exposed surface of the rotating cathode drum during the production of the copper foil.
  4. 4. The method according to claim 1 or 2, wherein the plasma jet is periodically applied onto the exposed surface of the rotating cathode drum during the production of the copper foil, preferably during about 50 to 75% of production time.
  5. 5. The method according to any one of the preceding claims, wherein the plasma jet is generated by an atmospheric plasma generating device from a process gas comprising at least 60 %-vol of nitrogen, preferably at least 70%-vol. or 75%-vol of nitrogen.
  6. 6. The method according to claim 5, wherein the process gas is air, preferably supplied at a flow rate of between 1 and 1000 L/min, preferably between 1 and 100 L/min, more preferably between 1 and 50 L/min to the plasma generating device.
  7. 7. The method according to any one of the preceding claims, wherein the plasma jet comprises nitrogen, oxygen and hydrogen, preferably nitrogen oxides and/or hydroxyl radicals.
  8. 8. The method according to any one of the preceding claims, wherein plasma jet is generated by a discharge generated with a total power of 25000 to 75000 W, preferably 35000 to 65000 W, more preferably 40000 to 60000 W.
  9. 9. The method according to any one of the preceding claims, wherein the plasma jet is generated by a plasma generating device mounted on a mobile support configured to move the plasma generating device relative to the cathode and the plasma jet is continuously scanned over the exposed surface of the cathode drum.
  10. 10. The method according to claim 9, wherein the plasma jet is moved along the direction of the cathode drum axis.
  11. 11 .The method according to any one of claims 1 to 8, wherein the plasma jet is generated by a plasma jet generating device fixedly mounted with respect to the electroplating cell.
  12. 12. The method according to 11 , wherein the treatment area of the cathode, which is irradiated by the plasma jet, has a length along the direction of the cathode axis of at least 90% of the length of the cathode, preferably at least 95% and more preferably 99% to 100%.
  13. 13. The method according to claim 11 or 12, wherein the treatment area has a width along a tangential direction relative to the cathode surface, lying between 1 and 10 cm, e.g. of about 2 or 3 cm.
  14. 14. The method according to any one of the preceding claims, wherein a distance between an outlet of the plasma generating device, through which the plasma jet is ejected, and the surface of the cathode drum is between 1 and 20 cm, preferably between 1 and 15 cm, more preferably between 1 and 5 cm, even more preferably between 1 and 3 cm, and most preferably between 1 and
  15. 15. Use of an atmospheric plasma generating device to remove and/or prevent hydrogen corrosion on a metallic cathode made of titanium or of a titanium alloy, wherein a surface of the metallic cathode is irradiated in an open-air environment with a plasma jet produced by the plasma generating device.
  16. 16. An electroplating apparatus, in particular configured for performing a method according to any one of claims 1 to 14, the apparatus comprising: - a metallic drum-shaped rotating cathode made of titanium or of a titanium alloy; - a stationary anode; - a tank for an electrolyte, wherein the drum-shaped cathode and the anode are arranged spaced apart from each other in the tank; and - a plasma generating device configured to generate an atmospheric plasma in a plasma chamber, the plasma chamber having an outlet facing the drum-shaped cathode such that a plasma jet irradiates at least a portion of a surface of the drum-shaped cathode to treat the latter against hydride corrosion.
  17. 17. The electroplating apparatus according to claim 16, wherein the plasma generating device comprises a process gas inlet to said plasma chamber and at least one pair of electrodes to create a discharge.
  18. 18. The electroplating apparatus according to claim 16 or 17, wherein the plasma chamber is designed as a plasma torch.
  19. 19. The electroplating apparatus according to any one of claims 16 to 18, wherein the plasma jet has an electron temperature comprised between 4000 and 11000 K, preferably between 6500 and 9000 K.
  20. 20. The electroplating apparatus according to any one of claims 16 to 19, wherein the plasma jet is generated in the plasma chamber from process gas comprising at least 60 %-vol of nitrogen, preferably at least 70%-vol. or 75%- vol of nitrogen, in particular the process gas is air.

Description

Electroplating apparatus and method for producing an electroplated copper foil using the same FIELD OF THE INVENTION The present invention generally relates to the field of electrodeposited copper foils and more specifically to an apparatus and method to produce electrodeposited copper foils. The invention particularly addresses the treatment of hydride corrosion, which may form during electroplating. BACKGROUND OF THE INVENTION The process and production of electrodeposited (or electrolytic) copper foils 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 drumshaped cathode and is arranged in the electrolyte to face a stationary anode. The side of the electrolytic copper foil contacting the surface of the drum is referred to as the shiny or drum side, and the opposite side of the copper foil is referred to as the matte or electrolyte side. The surface aspect, and in particular the surface roughness, of the matte side can be controlled by adjusting the composition of the electrolyte while the surface roughness of the shiny side reflects the surface of the drum-shaped cathode. Defects such as local increased rugosity of the surface of the drum therefore strongly impact the quality of the produced electroplated copper foil. Over the past decades, drum-shaped cathodes made of titanium have been developed, as this metal is relatively stable in acidic solutions, such as copper sulfate solutions used as electrolytes for the production of electroplated copper foils. Moreover, titanium drums are lighter than drums made of stainless steel and therefore easier to handle. Unfortunately, after a certain time a brownish titanium hydride layer is forming on the titanium drum, leading to increased roughness of the drum surface which is reflected on the shiny side of the produced copper foils and thus leads to the deposition of lower quality copper foils. Currently, the most common method used to limit the formation of the layer is polishing: the titanium drum surface is polished with a brush at regular intervals, during a production stop. Such on-site polishing methods are disclosed e.g. in patent application JPH 10-330984 A. However, when the on-site polishing is no longer sufficient to maintain a good drum surface state, the drum is removed for off-site fine polishing of its surface in order to restore suitable surface properties, in particular a suitable surface roughness, thus temporarily stopping the copper foil production. Moreover, the polishing leads to the reduction of the thickness of the titanium drum, shortening its lifespan. Another solution is disclosed in US 2003/116241 A1. This patent application proposes to manufacture titanium drum-shaped cathodes with a lower hydrogen content to delay the growth of the original hydride layer, in order to require less polishing. This approach however involves fully replacing the drum to limit the problem, which represents an important investment, and does not fully prevent but only delays the formation of the hydride layer. JP2003328177A in turn suggests improving the lifetime of a cathode electrode by coating the latter with a ceramic layer of titanium nitride (TiN) layer or chromium nitride (CrN). This ceramic coating is formed before installation of the cathode in the electrolysis cell. This document recommends the use of cathode made of stainless steel to avoid hydride corrosion issues. Further, to form the ceramic layer, it is recommended to use the hollow cathode ion plating method as the most stable method for forming a droplet-free ceramic layer. In contrast, the arc plasma ion plating method is said to be less desirable in that when the constituent materials evaporate from the target, some spots on the target surface reach extremely high temperatures of over 5000 K, causing instantaneous evaporation from those areas, resulting in a splash phenomenon in which the material turns into droplets and scatters, and the spherical titanium adheres to the surface of the formed ceramic layer as droplets. Finally, CN 115 360 357 A addresses safety performance of the lithium ion secondary cycle life battery. For improved safety, it is proposed to use a negative electrode and negative electrode current collector copper foil for, in which silicon active material is physically embedded in the copper foil during the production process of the electrolytic copper foil. Specifically, a method is disclosed where first a silicon nanowire powder or suspension is prepared, and the powder/suspension is blown by a plasma wind onto the free surface of the cathode drum, upon which the electrolytic copper foil is then formed. Thereby, the silicon