Copper Foil and Copper Strip: A Comprehensive Analysis from Production Processes to Application Scenarios

In the field of copper-based material processing, “copper foil” and “copper strip” are frequently used technical terms. For non-professionals, the difference between the two may seem only linguistic, but in industrial production, this distinction directly affects material selection, process routes, and final product performance. This article systematically analyzes their fundamental differences from three key perspectives: technical standards, production processes, and industry applications.

1. Thickness Standard: The Industrial Logic Behind the 0.1mm Threshold

From a thickness perspective, 0.1mm is the critical dividing line between copper strips and copper foils. The International Electrotechnical Commission (IEC) standard clearly defines:

• Copper Strip: Continuously rolled copper material with a thickness ≥ 0.1mm
• Copper Foil: Ultra-thin copper material with a thickness < 0.1mm

This classification is not arbitrary but is based on material processing characteristics:
When the thickness exceeds 0.1mm, the material achieves a balance between ductility and mechanical strength, making it suitable for secondary processing such as stamping and bending. When the thickness falls below 0.1mm, the processing method must shift to precision rolling, where surface quality and thickness uniformity become critical indicators.

In modern industrial production, mainstream copper strip materials typically range between 0.15mm and 0.2mm. For example, in new energy vehicle (NEV) power batteries, 0.18mm electrolytic copper strip is used as the raw material. Through more than 20 passes of precision rolling, it is ultimately processed into ultra-thin copper foil ranging from 6μm to 12μm, with a thickness tolerance of ±0.5μm.

2. Surface Treatment: Technology Differentiation Driven by Functionality

Standard Treatment for Copper Strip:

1. Alkaline Cleaning – Removes rolling oil residues
2. Chromate Passivation – Forms a 0.2-0.5μm protective layer
3. Drying and Shaping

Enhanced Treatment for Copper Foil:

In addition to copper strip processes, copper foil undergoes:

1. Electrolytic Degreasing – Uses 3-5A/dm² current density at 50-60°C
2. Nano-Level Surface Roughening – Controls Ra value between 0.3-0.8μm
3. Anti-Oxidation Silane Treatment

These additional processes cater to specialized end-use requirements:
In Printed Circuit Board (PCB) manufacturing, copper foil must form a molecular-level bond with resin substrates. Even micron-level oil residue can cause delamination defects. Data from a leading PCB manufacturer shows that electrolytic degreased copper foil improves peel strength by 27% and reduces dielectric loss by 15%.

3. Industry Positioning: From Raw Material to Functional Material

Copper strip serves as a “basic material supplier” in the supply chain, mainly used in:

• Power Equipment: Transformer windings (0.2-0.3mm thick)
• Industrial Connectors: Terminal conductive sheets (0.15-0.25mm thick)
• Architectural Applications: Roofing waterproof layers (0.3-0.5mm thick)

In contrast, copper foil has evolved into a “functional material” that is irreplaceable in:

Taking power batteries as an example, copper foil accounts for 10-15% of the cell material cost. Every 1μm reduction in thickness increases battery energy density by 0.5%. This is why industry leaders like CATL are pushing copper foil thickness to 4μm.

4. Technological Evolution: Merging Boundaries and Functional Breakthroughs

With advancements in material science, the traditional boundary between copper foil and copper strip is gradually shifting:

1. Ultra-Thin Copper Strip: 0.08mm “quasi-foil” products are now used for electromagnetic shielding.
2. Composite Copper Foil: 4.5μm copper + 8μm polymer substrate forms a “sandwich” structure that breaks physical limits.
3. Functionalized Copper Strip: Carbon-coated copper strips are opening new frontiers in fuel cell bipolar plates.

These innovations demand higher production standards. According to a major copper producer, using magnetron sputtering technology for composite copper strips has reduced unit-area resistance by 40% and improved bending fatigue life by 3 times.

Conclusion: The Value Behind the Knowledge Gap

Understanding the difference between copper strip and copper foil is fundamentally about grasping the “quantitative to qualitative” shifts in materials engineering. From the 0.1mm thickness threshold to micron-level surface treatments and nanometer-scale interface control, each technological breakthrough is reshaping the industry landscape.

In the carbon neutrality era, this knowledge will directly influence a company’s competitiveness in the new materials sector. After all, in the power battery industry, a 0.1mm gap in understanding could mean an entire generation of technological difference.