Research on Copper Foil Tensile Testing

Abstract ： This article introduces the use of the Kunpeng BOYI 2025 electronic universal testing machine and pneumatic foil-specific fixtures to perform tensile tests on copper foil samples, referring to standards such as "GB/T 5230-1995 Electrolytic Copper Foil Tensile Strength, Elastic Modulus, and Elongation at Break Test", "SJ/T 11483-2014 Electrolytic Copper Foil for Lithium-ion Batteries", "YB/T 4334-2013 Metal Foil Room Temperature Tensile Test Method", and "GB/T 29847-2013 Copper Foil Test Method for Printed Circuit Boards". The mechanical properties of copper foil, including tensile strength and elongation at break, are evaluated.

Keywords BOYI 2025 Precision Universal Testing Machine, Copper Foil, Tensile Test

Lithium battery copper foil, as the negative electrode current collector of lithium batteries, accounts for 5%-8% of the battery cost and is an important lithium battery material. Copper foil serves both as the carrier of the negative electrode active material and as the collector and conductor of electrons in the negative electrode. Therefore, the tensile strength, ductility, density, surface roughness, thickness uniformity, and appearance quality of electrolytic copper foil greatly affect the manufacturing process of lithium-ion battery negative electrodes and the electrochemical performance of lithium-ion batteries.

Copper foil is an ultra-thin copper strip or sheet with a thickness below 200μm. Thinner copper foil in lithium batteries helps improve battery energy density. Copper foil can be classified by thickness into thick copper foil (>70μm), conventional copper foil (18-70μm), thin copper foil (12-18μm), ultra-thin copper foil (6-12μm), and ultra-thin copper foil (≤6μm).

Copper-clad laminates and printed circuit boards have become essential main components in most electronic products. Metal conductor foils are conductor materials used in flexible copper-clad laminates, including copper foil, aluminum foil, and copper-beryllium alloy foil. Currently, most use copper foil, including electrolytic copper foil (ED) and rolled copper foil (RA). Copper foil is an important material for copper-clad laminates (CCL), printed circuit boards (PCB), and lithium-ion battery manufacturing.

Copper foil thickness is usually several tens of microns and is commonly used on rigid and flexible copper-clad laminates and printed circuit boards. Rigid boards require mechanical strength to provide support; copper foil on flexible boards is often used in bending, folding, and winding states, where mechanical strength is especially important. In recent years, due to the development of curved screens and foldable electronic products, the usage range has expanded and frequency increased. In the future, copper foil will develop towards fewer defects, higher smoothness, greater strength, better ductility, and thinner profiles.

This report refers to national and industry standards for tensile testing of copper foil samples. The GB standard requirements are:

1. Testing machine with a range of 1kN and accuracy class 0.5 for tensile force;

2. Sample width of 13±0.1 mm, length approximately 200 mm strip samples;

3. Initial distance between fixtures of 50±0.1 mm, test speed of 50±10 mm/min.

4. Evaluation results: tensile strength and elongation at break.

1.1 Instruments and Fixtures

BOYI 2025-001 Electronic Universal Testing Machine

500N Pneumatic Foil-Specific Fixture

1.2 Analysis Conditions

Test temperature: room temperature around 25°C

Load sensor: 1000N (class 0.5)

Test speed: 50 mm/min

Fixture distance: 50 mm