Fluorocarbon-Free Hierarchical Slippery Copper Surfaces via Solid-State Electrochemical Etching.

Area of Science:

• Materials Science
• Electrochemistry
• Surface Engineering

Background:

• Micro- and nanoscale copper patterns are critical for flexible electronics, thermal management, and functional surfaces.
• Current copper patterning methods are complex, chemically intensive, and multistep.
• Solid-state electrochemical etching with polymer electrolyte membranes (PEM) has been limited to shallow depths.

Purpose of the Study:

• To develop an efficient and scalable method for solid-state electrochemical etching of copper.
• To introduce a copper-ion-loaded PEM (CuSO4 PEM) stamp for enhanced copper patterning.
• To fabricate 3D hierarchical copper structures with advanced surface properties.

Main Methods:

• Utilized a copper-ion-loaded PEM (CuSO4 PEM) stamp for solid-state electrochemical etching.
• Employed high-humidity conditions (90%) and controlled voltage (500 mV) for deep etching of copper foils.
• Fabricated micro/nanohierarchical structures using a hierarchical PEM stamp.

Main Results:

• Achieved uniform through-etching of 10 μm copper foils and deep etching up to 30 μm.
• Transferred well-defined submillimeter-scale patterns (line-and-space, honeycomb, square-grid) with high fidelity.
• Created 3D copper micro/nanohierarchical structures with nanopillar arrays on surfaces and sidewalls.

Conclusions:

• The CuSO4 PEM stamp enables efficient, scalable, and high-resolution copper patterning via solid-state electrochemical etching.
• The fabricated hierarchical structures exhibit enhanced wetting control, enabling functional surfaces like slippery liquid-infused porous surfaces.
• This approach offers reduced environmental impact, lower processing costs, and broad potential in electronics, thermal management, and microfluidics.