Cold-rolled aluminum foil

1. Definitions and Classifications

Cold-rolled aluminum foil is an ultra-thin aluminum product manufactured from aluminum ingots through processes such as melting, casting, hot rolling, cold rolling, and finishing (thickness range: 0.01 to 0.2 mm). Based on alloy composition, it can be classified into:

• 1XXX series(Pure Aluminum Foil, e.g., 1060/1100): High conductivity and ductility; ideal for the electronics industry.

• 3XXX Series(Aluminum foil with anti-rust coating, e.g., 3003/3105): Highly corrosion-resistant; used in food packaging and pharmaceuticals.

• XXX Series(5005/5705): Combines strength with machinability; targets the construction and home appliance markets.

• 6XXX Series(6061/6063): High-strength alloy for aerospace and precision instruments.

II. Production Process Flow

1. Melting and Ingot Casting

• Al ingot purity ≥ 99.5%, melting temperature 750~780°C, and ingot cooling rate controlled at ≤ 15°C/min to prevent grain coarsening.

• Hot rolling

  • Heat the ingot to 470~530°C, roll it to a thickness of 2~5 mm to eliminate casting defects and optimize the grain structure.

• Cold Rolling

  • Rolling temperature: 0~30°C (low-temperature rolling enhances strength)

  • Rolling speed: 0.1~3m/s (cooling and lubrication required for high-speed rolling)

  • Thickness tolerance: ±0.005mm (for precision foil)

  • Key Parameters：

  • Multi-pass rolling (8–20 passes) with up to 90% reduction, achieving a final thickness of 0.01mm.

• Finishing Process

  • Brightening: Electro-polishing (current density 10~20 A/dm²), surface roughness Ra ≤ 0.1 μm.

  • Coating treatment: Fluorocarbon coating (PVDF film thickness ≥ 20 μm) enhances weather resistance.

  • Annealing: Eliminate residual stress and restore plasticity (Temperature 300~450°C, Duration 1~5 hours).

  • Surface Finish：

III. Core Technical Features

1. Mechanical Properties

• Tensile Strength: 100~300 MPa (5XXX series reaches up to 270MPa)

• Elongation: ≥15% (1XXX series can reach 50%)

• HardnessHV 30~80 (depending on alloy and annealing condition)

• Surface Quality

• Glossy Foil: Mirror Reflectivity ≥ 85%

• Heat-seal foil: Ra roughness 0.5~3 μm (optimized for heat sealing)

• Surface Condition：

• Cleanliness: Metal impurity content < 10 ppm, oxygen content ≤ 0.15%.

• Corrosion Resistance

• natural oxidationForms a dense oxide film (thickness 10~20 nm) with neutral salt spray resistance exceeding 96 hours.

• AnodizingCorrosion resistance after electrolytic coloring increases 5~10 times (e.g., black oxide film withstands chloride ion penetration for >5000 h).

4. Typical Application Areas

1. Packaging Industry

• Food Packaging: 3003 series aluminum foil (thickness 0.03mm), blocks oxygen and moisture to extend shelf life.

• Drug Packaging: 1060 is a sterile aluminum foil that complies with FDA certification.

• Cigarette pack printing: 5005 series aluminum foil, suitable for printing fine patterns on the surface.

• Electronics Industry

• capacitor electrode foil: 1100 series ultra-thin foil (thickness 0.01mm), high dielectric constant (> 100).

• Electromagnetic Shielding: 6061 series aluminum foil (copper-plated treatment), shielding effectiveness > 40 dB.

• Architecture and Transportation

• Insulation material: Aluminum foil composite (thickness 0.05mm), reflecting infrared energy savings up to 30%.

• Car Air Conditioning:5XXX series aluminum foil (thermal conductivity 237W/m·K) for efficient heat dissipation.

• New Energy Sector

• Lithium-ion battery current collector: 6063 series aluminum foil (surface microstructure treatment) to reduce interface resistance.

• Hydrogen Fuel Cell: Platinum-coated aluminum foil (thickness 0.1 mm), catalyst support material.

5. Technical Standards and Testing

1. International Standard

• ASTM B221: Specifies foil thickness, mechanical properties, and dimensional tolerances.

• ISO 5725: Surface defect grading (e.g., pinholes, scratch levels).

• Domestic Standards

• GB/T 3198Aluminum foil thickness tolerance (±3%).

• GB/T 1629Anodized film thickness measurement (ellipsometry).

VI. Future Development Trends

1. Ultra-thin: Develop aluminum foil with thickness < 0.005mm nm for flexible electronic devices.

2. Functional：

• Conductive Coating: Graphene-composite aluminum foil (conductivity > 10⁶ S/cm).

• Self-healing coating: Microcapsule technology for repairing surface scratches.

• Green Manufacturing：

• Recycled aluminum foil: Waste recycling rate exceeds 95%, carbon emission intensity reduced by 40%.

• acid-free rolling: Replace traditional mineral oil with eco-friendly lubricants.

Cold-rolled aluminum foil, with its superior comprehensive performance, has become an essential base material for high-end manufacturing. Its continuous technological evolution will drive innovation breakthroughs in packaging, electronics, and new energy sectors.