In the field of lithium battery composite current collectors and flexible electronics, substrate thickness is a physical quantity that is continuously compressed. The thickness of PET film has gradually decreased from the early 50 μ m and 25 μ m to 12 μ m, 6 μ m, and 4.5 μ m, and has now been advanced to 2.3 μ m.

What is the concept of 2.3 μ m? The diameter of a standard adult hair is approximately 60-80 μ m. The thickness of PET film with a thickness of 2.3 μ m is only about one thirtieth of the diameter of a hair. At this scale, PET film is approaching its physical limit as an independent film - thinner means facing significant process challenges in processes such as coating, slitting, and winding. Industry data shows that ultra-thin PET substrates suitable for copper plating typically have a thickness of 1.6 μ m or more. 2.3 μ m is located at the core of this limit range.

2、 Roll to roll vacuum magnetron sputtering: construction of precision conductive layer on 2.3 μ m substrate

The copper layer of 2.3 μ m PET copper plated film was prepared using roll to roll vacuum magnetron sputtering process. Place the rolled PET film into a vacuum chamber and use high-purity copper with a purity of 99.99% or higher as the target material. Through physical vapor deposition (PVD), copper atoms are uniformly deposited on the surface of PET to form a dense, low defect conductive seed layer. Subsequently, the copper layer was thickened to the target thickness through a water electroplating process, forming a direct composite structure of a non adhesive "PET substrate copper layer".

Copper plating on ultra-thin substrates with a thickness of 2.3 μ m faces a series of technical challenges that are far more stringent than conventional thickness substrates:

3、 Copper layer thickness: Performance range from 0.07 μ m to 0.7 μ m

Based on a 2.3 μ m PET substrate, copper plated film products with different copper layer thicknesses can be prepared by precisely controlling the sputtering and electroplating process parameters. The thickness of the copper layer varies from 0.07 μ m to 0.7 μ m, and different thicknesses correspond to different performance focuses:

Note: The thickness of the copper layer is the nominal reference value, and the specific performance is subject to the actual product specifications.

When selecting, engineers should weigh the requirements of conductivity, transparency, and current carrying capacity comprehensively: the thinner the copper layer (0.07-0.1 μ m), the better the flexibility and transparency, suitable for high-precision thin circuits and transparent applications; The thicker the copper layer (0.3-0.7 μ m), the lower the square resistance, and the stronger the conductivity and shielding effectiveness. Advanced Institute Technology can control the square resistance within the range of 0.01-1 Ω/□ by adjusting the sputtering power or chemical plating time, meeting the low resistance requirements of high-frequency circuits, electromagnetic shielding and other scenarios.

4、 Key performance: Technical boundary of 2.3 μ m specification

comprehensiveAdvanced Institute of TechnologyAccording to industry public information, the key performance characteristics of 2.3 μ m PET copper plated film are as follows:

• Substrate thickness.2.3 μ m is one of the ultra-thin specifications that can be mass-produced for PET film. The substrate thickness range of Advanced Institute Technology PET copper plated film covers 4.5 μ m to 100 μ m, with 2.3 μ m at the extreme low end of this range.
• Conductivity performance.The copper layer endows PET film with excellent conductivity. By adjusting the process parameters, the resistance can be controlled within the range of 0.01-1 Ω/□. The typical square resistance value for a copper layer thickness of 0.1 μ m is approximately ≤ 0.5 Ω/□.
• Coating adhesion.The adhesion of the coating reaches grade 5B (the highest grade of ASTM D3359), and the peel strength is ≥ 1.5N/mm.
• Bending resistance performance.The PET copper plated film of Advanced Institute Technology has a resistance change rate of less than 2% after 1000 cycles of bending. The design of microgrid copper structure can maintain conductivity continuity of the material under 30% tensile strain.
• Corrosion resistance.The surface of the copper layer can be treated by electroplating or chemical passivation, and it meets the 96 hour rust free standard in salt spray testing.
• Surface roughness.The ultra smooth copper layer surface treatment technology can reduce the surface roughness to Ra ≤ 50nm, significantly reducing high-frequency signal transmission loss.

5、 Core application scenario: From composite current collectors to transparent LEDs

6、 Selection considerations: from copper layer thickness to application scenarios

When engineers choose 2.3 μ m PET copper plated film, the following dimensions deserve special attention:

• Selection of copper layer thickness.The thinner the copper layer (0.07-0.1 μ m), the better the flexibility and transparency, making it suitable for high-precision thin circuits and transparent applications; The thicker the copper layer (0.3-0.7 μ m), the lower the square resistance, and the stronger the current carrying capacity and shielding effectiveness. 2.3 0.07PET is the thinnest copper layer specification in the product line, suitable for scenarios with extremely high requirements for transparency and flexibility.
• Bending life requirements.For dynamic applications that require frequent bending, thinner copper layer schemes should be preferred to reduce the risk of copper layer fatigue fracture. The PET copper plated film of Advanced Institute Technology has a resistance change rate of less than 2% after 1000 cycles of bending.
• Processing adaptability.The 2.3 μ m film requires high processing accuracy in subsequent etching, bonding, and other processes. Advanced Institute Technology supports flexible adjustment of copper layer thickness, PET substrate functionalization (such as anti-static and flame retardant), and patterned deposition, and can customize specifications such as square resistance, thickness, and width according to customer needs.
• Application scenario matching.The application of lithium battery composite current collectors usually chooses 2.3 0.3PET or 2.3 0.7PET specifications; High density FPC and transparent LED display applications can choose 2.3 0.1PET; For sensor electrode applications that require extremely high transparency and flexibility, 2.3 0.07PET can be considered.

7、 Conclusion

The essence of 2.3 μ m PET copper plated film is an engineering product that pushes the thickness of PET film to its physical limit. It is not simply "thinning" - at a scale of 2.3 μ m, material tension control, temperature management, perforation suppression, and coating uniformity all face engineering challenges that are far more stringent than conventional thickness substrates. It is precisely these boundary conditions that have been overcome one by one that enable the 2.3 μ m PET copper plated film to move from the laboratory to mass production, becoming the core material for applications such as lithium battery composite current collectors, high-density FPCs, and transparent electronics.

From the safety upgrade of power batteries to the thinning of transparent LED displays -2.3 μ m PET copper plated film is transforming the simple engineering goal of "thinner" into tangible performance improvement and cost optimization. For engineers, understanding the process constraints and performance opportunities behind the thickness of 2.3 μ m - why it is 2.3 μ m instead of thinner, and how to choose the thickness of the copper layer - is more valuable than simply remembering a specification.