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3.1 μ m PET aluminum plated film · ultra-thin capacitor substrate
In the design of metalized film capacitors, the thickness of the dielectric film directly determines the volumetric efficiency of the capacitor - the thinner the film, the greater the capacitance per unit volume. Over the past few decades, 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 advanced to 3.1 μ m.
What is the concept of 3.1 μ m? As a reference, the diameter of a standard adult hair is approximately 60-80 μ m. The thickness of PET film with a thickness of 3.1 μ m is only about one twenty fifth of the diameter of a hair. The thickness of PET film from Advanced Institute Technology can be controlled within the range of 4-100 μ m, with 3.1 μ m being at the extreme low end 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 3.1 μ m PET aluminum plated film irreplaceable in metalized thin film capacitors and precision electronic applications that require extreme miniaturization.
The aluminum layer preparation of 3.1 μ m PET aluminum plated film adopts vacuum evaporation process - in a highly vacuum environment, high-purity aluminum is heated to the evaporation temperature (about 1200-1400 ° C), and the aluminum vapor is condensed and deposited on the surface of the high-speed running PET film, forming a layer of metallic aluminum. The thickness of the aluminum layer is usually in the range of 20-100 nanometers. The vacuum evaporation process can accurately control the thickness and uniformity of the aluminum layer, ensuring stable material properties.
Vacuum deposition on ultra-thin substrates with a thickness of 3.1 μ m faces a series of technical challenges that are far more stringent than conventional thickness substrates:
3.1 μ m PET has extremely low thermal capacity and requires precise control of evaporation temperature, speed, and substrate speed 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.
Any small defect can become a penetrating pinhole, and low pinhole aluminum coating is a core requirement for high-end applications.
Accurately regulate the evaporation rate and substrate speed to achieve nanoscale control of aluminum layer thickness.
PET is one of the most common dielectric materials in metallized film capacitors. PET film has a high dielectric constant and excellent self-healing properties, with a working temperature of up to 120 ° C. The PET dielectric layer thickness of ultra-thin metallized capacitor film can be as low as 1.2-2.8 μ m, with 3.1 μ m being in this ultra-thin range.
The core engineering value of 3.1 μ m PET substrate lies in its volumetric efficiency. The capacitance of a capacitor is inversely proportional to the thickness of the dielectric - the thinner the film, the greater the capacitance within the same volume. For thin film capacitors that require stable operation in high current and high ripple scenarios, a 3.1 μ m ultra-thin PET substrate can achieve higher capacitance density in a limited space.
Process collaboration:The internal electrodes of metallized film capacitors are ultra-thin metal layers deposited on the surface of the film through vacuum coating technology. The combination of 3.1 μ m PET substrate and nanoscale aluminum coating has pushed the miniaturization of capacitors to a new height.
Based on a 3.1 μ m PET substrate, aluminum plated film products with different aluminum layer thicknesses can be prepared by precisely controlling the evaporation process parameters. The thickness of the aluminum layer (characterized by optical density OD value) ranges from 0.1 to 1.0, and different thicknesses correspond to different performance focuses:
| Product Type | Optical density (OD) | Aluminum layer thickness | Key Features | Typical Applications |
|---|---|---|---|---|
| 3.1 0.1PET aluminum plated film | ~0.1 OD | Ultra thin aluminum layer (<20nm)<> | Extremely flexible, semi transparent, and lowest material cost | Ultra thin capacitors, precision optical films, low barrier packaging |
| 3.1 0.3PET aluminum plated film | ~0.3 OD | Thin aluminum layer (~30nm) | Good flexibility and moderate barrier properties | Metallized film capacitors, electronic shielding |
| 3.1 0.7PET aluminum plated film | ~0.7 OD | Medium aluminum layer (~70nm) | High reflectivity, strong conductivity, and high barrier properties | High reliability capacitors, electromagnetic shielding |
| 3.1 1PET aluminum plated film | ~1.0 OD | Thicker aluminum layer (~100nm) | High reflectivity, low surface resistance, high barrier properties | High end capacitors, X-ray detectors, EMI shielding |
Note: The higher the optical density (OD) value, the thicker the aluminum layer, and the higher the barrier and reflectivity. The thickness of the aluminum layer is usually in the range of 20-100 nanometers.
Selection suggestion:The lower the OD value, the better the flexibility and the stronger the winding adaptability; The higher the OD value, the stronger the conductivity and barrier properties. Balancing capacitance density, flexibility, and barrier requirements comprehensively.
3.1 μ m is one of the ultra-thin specifications that can be mass-produced for PET film, covering 3.1-188 μ m, which is at the extreme low-end.
20-100 nanometers, the thicker the barrier and conductivity, but the flexibility decreases.
Oxygen/water vapor permeability can be reduced by over 99%, and food packaging can extend shelf life by 3-5 times.
Visible light reflectance ≥ 90%, surface resistance<1 ω>
The long-term use temperature of PET is 120 ° C.
Core applications. Metallized PET film with a thickness of 2-12 μ m is the standard specification, and 3.1 μ m achieves higher capacitance density, widely used in consumer electronics, automotive electronics, and industrial power supplies.
Ultra thin shielding layer, can fit in narrow spaces, surface resistance<1 ω>
Used for thin film capacitor electrodes, antennas, sensors, as well as optical reflective films and sensor substrates.
Low surface resistance effectively dissipates static electricity and is suitable for packaging electrostatic sensitive electronic components.
The higher the OD value, the stronger the barrier and conductivity. Capacitor selection based on voltage/capacity; The shielding needs to ensure that the surface resistance meets the requirements.
Ultra thin substrate pinhole control is a core quality indicator, and high-end applications such as high-voltage capacitors have strict requirements for pinhole density.
3.1 μ m film is prone to wrinkling and fracture, and its compatibility with existing winding equipment needs to be evaluated.
The long-term use temperature of PET is 120 ° C, and if it exceeds this, higher temperature resistant substrates such as PEN or PI should be considered.
The essence of 3.1 μ m PET aluminum coated 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 3.1 μ m, material tension control, temperature management, pinhole 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 have enabled 3.1 μ m PET aluminum coated film to move from the laboratory to mass production, becoming the core material for high-end applications such as metalized thin film capacitors and precision electronics.
For engineers, understanding the process constraints and performance opportunities behind the thickness of 3.1 μ m - why it is 3.1 μ m instead of thinner, and how to choose the OD value - is more valuable than simply remembering a specification.
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