Thin Copper Foils: From Electrodeposition Conditions to Adhesion Performances

Area of Science:

• Materials Science
• Electrochemistry
• Surface Engineering

Background:

• Thin copper foils (TCFs) are crucial in various electronic applications.
• Optimizing electrodeposition processes is key to achieving desired film properties and adhesion.

Purpose of the Study:

• Investigate cathodic electrodeposition of copper on molybdenum and stainless steel for TCF production.
• Evaluate the effect of additives on copper film characteristics and adhesion.

Main Methods:

• Galvanostatic electrodeposition from acidic sulfate electrolyte.
• Characterization using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and X-ray Diffraction (XRD).
• Adhesion assessment via a custom bending test machine measuring the critical cycle number (n_c).

Main Results:

• Nanocrystalline copper films were obtained with the addition of chloride ions, polyethylene glycol 6000, and 3-mercapto-1-propanesulfonic acid.
• Films produced with all additives showed significantly lower critical cycle numbers (n_c), indicating easier delamination.
• Microcrystalline films, obtained without or with partial additives, exhibited better adhesion.

Conclusions:

• The tested substrates (molybdenum and stainless steel) show high potential for TCF production.
• Nanocrystalline copper films, despite easier delamination, suggest a pathway for TCF manufacturing.
• Further research may focus on optimizing additive combinations to balance film properties and adhesion.