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4 μ m PET copper plated film, composite current collector, and ultra-thin FPC
In the field of metalized thin films 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 4 μ m.
What is the concept of 4 μ m? As a reference, the diameter of a standard adult hair is approximately 60-80 μ m. The thickness of 4 μ m PET film is only about one fifteenth of the diameter of a hair. The thickness of PET film from Advanced Institute Technology can be accurately controlled within the range of 4-100 μ m, with 4 μ m being at the lower limit of this range. 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.
Core Insights:It is precisely this "extreme thinness" that makes the 4 μ m PET copper plated film irreplaceable in applications that require extreme lightweight, such as lithium battery composite current collectors, high-density FPCs, and precision electronics.
The copper layer preparation of 4 μ m PET copper plated film adopts roll to roll vacuum magnetron sputtering process. In a highly vacuum environment, high-purity oxygen free copper targets are bombarded with high-energy ions to sputter copper atoms, which are uniformly deposited on the surface of PET films under the action of electric and magnetic fields. The controllability of copper layer thickness reaches ± 0.1 μ m.
Magnetron sputtering copper plating on ultra-thin substrates with a thickness of 4 μ m faces a series of technical challenges that are far more stringent than conventional thickness substrates:
4 μ m PET has extremely low thermal capacity and requires precise control of sputtering power and cooling system to prevent shrinkage, warping, or melting.
The mechanical strength of extremely thin substrates is limited, and a precise low tension control system is the core threshold for mass production.
Multi target co sputtering system with a square resistance uniformity of ± 5%. First, sputter a 20-80nm copper seed layer, and then water electroplating to thicken it.
Optimization of plasma cleaning, with a peel strength of ≥ 1.5N/mm and a coating adhesion strength of 5B grade (the highest grade in ASTM D3359).
The application of 4 μ m PET copper plated film in the field of lithium battery composite current collectors is one of the most concerned technological directions in recent years.
Traditional lithium battery negative electrode current collectors use 6-8 μ m electrolytic copper foil. The composite copper foil adopts a sandwich structure of "polymer based film double-sided copper plating" - a PET film with a thickness of 4 μ m in the middle, and 1 μ m copper layers on both sides, with a total thickness of 6 μ m, which is consistent with the thickness of existing electrolytic copper foils. The battery factory can use it directly without changing the process. The key advantages of composite copper foil are reflected in three dimensions:
PET composite copper foil reduces the weight of the current collector by about 55%, increases the energy density of the battery pack by 5% -10%, and increases the range.
Polymer substrates are flame retardant, and when short circuited, the conductive layer melts to form a "point break", reducing the possibility of combustion, fire, and explosion.
The amount of copper used is much lower than that of pure copper foil, with significant material cost advantages, lower manufacturing costs, and greater gross profit margins.
Advanced Institute of Technology:We can provide customized PET copper plated film with a thickness of 4.5 μ m, a square resistance of 0.05 Ω/□, and a tensile strength of ≥ 200MPa. The resistance change rate after 1000 bends is less than 2%. >
Based on a 4 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 0.1 μ m to 1 μ m, and different thicknesses correspond to different performance focuses:
| Product Type | Copper layer thickness | Key Features | Typical Applications |
|---|---|---|---|
| 4 0.1PET copper plated film | ~0.1 μm | Extremely thin copper layer, highest flexibility, semi transparent | Ultra thin electromagnetic shielding layer, sensor electrode, precision optics |
| 4 0.3PET copper plated film | ~0.3 μm | Thin copper layer, good flexibility, moderate conductivity | High density FPC thin line, wearable device connection |
| 4 1PET copper plated film | ~1 μm | Thick copper layer, low square resistance, high conductivity | Lithium battery composite current collector, high-frequency signal transmission, electromagnetic shielding |
Note: The thickness of the copper layer is the nominal reference value, and the specific performance is subject to the actual product specifications. The typical value of square resistance for 4 μ m copper thickness is ≤ 4.5m Ω/□.
Selection suggestion:The thinner the copper layer (0.1-0.3 μ m), the better the flexibility and suitability for high-precision thin circuits; The thicker the copper layer (1 μ m), the stronger the conductivity and the lower the square resistance. 4 1PET is the standard specification for lithium battery composite current collectors.
4 μ m is one of the ultra-thin specifications that can be mass-produced for PET film, covering a customized range of 4-188 μ m, which is at the extreme low-end.
The resistance of Cu surface is ≤ 0.5 Ω/sq, and the square resistance can be controlled within the range of 0.01-1 Ω/□.
Adhesion ≥ 5B (ASTM D3359 highest grade), peel strength ≥ 1.5N/mm, 1000 fold resistance change<2%. <>
Long term temperature resistance of 120 ° C, the copper layer can withstand 96 hours of salt spray test without corrosion after passivation treatment.
The fastest growing field. 4 μ m PET base film double-sided plated with 1 μ m copper, replacing 6-8 μ m electrolytic copper foil, enhancing safety, energy density, and cost advantages.
Suitable for limited space scenarios such as wearable devices and foldable phones, achieving high-density wiring and ultimate slimness.
Ultra thin shielding layer can fit into narrow spaces that traditional shielding materials cannot enter, with low surface resistance.
Copper layer high thermal conductivity provides a thermal conduction path, and ultra-thin specifications do not add additional thickness.
0.1-0.3 μ m is suitable for high-precision fine lines; 1 μ m is used for composite current collectors and conductivity priority scenarios.
For dynamic bending applications, thin copper layers (0.1-0.3 μ m) are preferred to reduce the risk of fatigue fracture.
Choose a 1 μ m copper layer scheme for applications that require current carrying capacity.
The 4 μ m film requires high etching and bonding accuracy, and advanced technology supports flexible adjustment of copper layer thickness, PET functionalization, and patterned deposition.
The essence of 4 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 the 4 μ m scale, material tension control, temperature management, coating uniformity, and interfacial bonding strength 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 4 μ m PET copper plated film to move from the laboratory to mass production, becoming the core material for high-end applications such as lithium battery composite current collectors, high-density FPCs, and precision electronics.
From the safety upgrade of power batteries to the ultimate lightweight of consumer electronics, the 4 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 4 μ m - why it is 4 μ m instead of thinner, and how to choose the thickness of the copper layer - is more valuable than simply remembering a specification.
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