What is the relationship between copper foil’s tensile strength and elongation？

The tensile strength and elongation of copper foil are two important physical property indicators, and there is a certain relationship between them, which directly affects the quality and reliability of the copper foil.

Tensile strength refers to the ability of copper foil to resist tensile fracture under the action of force, usually expressed in megapascals (MPa). Elongation refers to the ability of the material to undergo plastic deformation during the stretching process, expressed as a percentage. The tensile strength and elongation of copper foil are simultaneously affected by thickness and grain size, and the description of this size effect must introduce the dimensionless thickness-grain size ratio (T/D) as a comparison parameter. The variation pattern of tensile strength is different in different thickness-grain size ratio ranges, while the elongation decreases with the reduction of thickness when the thickness-grain size ratio is the same.

In practical applications, such as in the manufacture of printed circuit boards (PCBs), reasonable standards for tensile strength and elongation can ensure that the product is not prone to fracture or deformation during use, thereby ensuring the quality and reliability of the product. For the tensile testing of copper foil, there are various standards and methods to determine these properties, such as the IPC-TM-650 2.4.18.1A standard, which is specifically formulated for the copper foil of printed circuit boards and provides detailed testing methods and points.

When testing the tensile strength and elongation of copper foil, factors to consider include the size of the sample, testing speed, temperature conditions, etc. For example, the ASTM E345-16 standard provides methods for tensile testing of metallic foil, including detailed parameters such as sample size, testing speed, etc. The GB/T 5230-1995 standard, on the other hand, stipulates the testing requirements for electrolytic copper foil, including sample size, gauge length, distance between clamps, and test machine clamp speed.

In summary, the tensile strength and elongation of copper foil are key indicators for measuring its physical properties, and their relationship and testing methods are crucial for ensuring the quality and application performance of copper foil materials.