Jiangsu Yuxing Film Technology Co., Ltd.

BOPET film delivers exceptional electrical insulation with dielectric strength up to 300 kV/mm and thermal stability from -40°C to 150°C. This biaxially oriented polyester film combines superior electrical properties with mechanical durability, making it the preferred choice for transformers, motors, and high-voltage applications where insulation failure costs exceed $2 million per incident.

Modern electrical systems demand insulation materials that perform reliably under extreme conditions. BOPET polyester film meets these requirements through its unique molecular structure and manufacturing process, offering consistent performance that traditional insulation materials cannot match.

Key Takeaways

• BOPET film provides dielectric strength up to 300 kV/mm, significantly higher than paper-based insulation (20-30 kV/mm)

• Thermal stability ranges from -40°C to 150°C, ensuring reliable performance across temperature extremes

• Moisture absorption below 0.4% prevents insulation degradation in humid environments

• Chemical resistance protects against oils, solvents, and aging compounds commonly found in electrical equipment

• Mechanical durability with tensile strength exceeding 200 MPa reduces installation damage and extends service life

BOPET Film Overview

What Is BOPET Film?

BOPET film (Biaxially Oriented Polyethylene Terephthalate) is a specialized polyester film created through a biaxial orientation process. This manufacturing technique stretches the film simultaneously in both machine and transverse directions, aligning polymer chains to create superior electrical and mechanical properties.

The biaxial orientation process transforms standard polyester into a high-performance insulation material. During production, the film undergoes controlled stretching at elevated temperatures, creating a uniform molecular structure that enhances dielectric strength and thermal stability.

For a comprehensive understanding of BOPET film fundamentals, technical specifications and manufacturing processes are detailed in industry documentation.

Note: BOPET polyester film's unique molecular alignment provides consistent electrical properties across the entire film thickness, eliminating weak spots that cause insulation failure.

Performance Characteristics

How BOPET Film Works

BOPET film functions as electrical insulation through its molecular structure and processing method. The biaxial orientation creates a dense, uniform film with excellent barrier properties and electrical characteristics.

Key functional advantages include:

• Uniform thickness ensures consistent dielectric properties across large surface areas

• High breakdown voltage prevents electrical failures under stress conditions

• Low dissipation factor minimizes energy losses in high-frequency applications

• Excellent corona resistance maintains insulation integrity under partial discharge conditions

Understanding dielectric strength principles is crucial for selecting appropriate insulation materials for specific voltage requirements.

Tip: The crystalline structure of BOPET polyester film provides superior tracking resistance compared to amorphous materials, making it ideal for outdoor electrical applications.

Components of BOPET Film Insulation

Base Material Properties

BOPET film starts with high-quality polyethylene terephthalate resin. The base material provides inherent electrical insulation properties, while the biaxial orientation process enhances these characteristics. Pure PET resin ensures consistent electrical performance without additives that could compromise insulation integrity.

The molecular weight and crystallinity of the base material directly impact final film properties. Higher molecular weight polymers provide better mechanical strength, while controlled crystallinity ensures optimal electrical characteristics.

Detailed polyester film properties explain why these materials excel in electrical insulation applications.

Surface Treatments and Coatings

Thickness Variations

BOPET film is available in multiple thickness options to meet specific insulation requirements. Standard thicknesses range from 6 microns to 350 microns, with each thickness offering different electrical and mechanical properties.

Thickness Selection Guide:

• 6-12 microns: Capacitor applications, high-frequency circuits

• 25-50 microns: Motor windings, transformer insulation

• 75-125 microns: Cable wrapping, high-voltage applications

• 175-350 microns: Structural insulation, mechanical barriers

Thicker films provide higher breakdown voltage and better mechanical protection, while thinner films offer flexibility and cost advantages in space-constrained applications.

Professional testing standards provide guidelines for evaluating dielectric strength performance.

Benefits in Electrical Applications

Dielectric Performance

BOPET film excels in electrical applications through superior dielectric properties. The film maintains consistent electrical characteristics across wide temperature ranges and frequency spectrums. Dielectric strength typically exceeds 280 kV/mm, providing reliable insulation even under electrical stress.

The low dissipation factor (typically 0.002-0.005 at 1 kHz) minimizes energy losses in AC applications. This characteristic is particularly valuable in high-frequency transformers and capacitors where energy efficiency is critical.

Studies demonstrate that BOPET polyester film maintains 90% of its dielectric strength after 1000 hours of thermal aging at 130°C, significantly outperforming traditional paper insulation. Advanced research studies show BOPET films achieving energy densities of 9.11 J/cm³ with 95% charge-discharge efficiency.

Thermal Stability

Temperature cycling tests show BOPET film maintains electrical integrity from -40°C to 150°C. The film's thermal stability prevents insulation degradation during equipment operation, extending service life and reducing maintenance costs.

The glass transition temperature (Tg) of 78°C and the melting point of 255°C provide adequate thermal margins for most electrical applications. The film's dimensional stability under thermal stress prevents mechanical failure and maintains insulation gaps.

Specialized thermal variants of BOPET film extend operating temperatures to 180°C for demanding applications.

Moisture Resistance

BOPET film's low moisture absorption (

The film's barrier properties protect underlying components from moisture ingress, maintaining electrical performance in outdoor and marine applications. Hydrolysis resistance ensures long-term stability in wet conditions.

BOPET Film Types for Electrical Insulation

Standard Electrical Grade

Standard electrical grade BOPET film provides reliable insulation for general electrical applications. This grade offers balanced electrical and mechanical properties suitable for motors, transformers, and switching equipment.

Key specifications include:

• Dielectric strength: 280-300 kV/mm

• Thermal class: B (130°C)

• Thickness tolerance: ±5%

• Surface smoothness: Ra

Technical specifications for electrical grade BOPET films include breakdown voltage and electrical resistivity data.

High-Temperature Variants

High-temperature BOPET polyester film extends operating temperatures to 180°C through modified polymer chemistry and processing conditions. These variants maintain electrical properties at elevated temperatures where standard grades would fail.

Applications include:

• Traction motor insulation

• Aerospace electrical systems

• High-performance transformers

• Renewable energy equipment

Specialized Formulations

BOPET Film Selection and Application

Choosing the Right Film

Selection depends on specific application requirements, including voltage levels, temperature range, mechanical stress, and environmental conditions. Key factors to consider:

Voltage Requirements: Higher voltages demand thicker films with superior dielectric strength. Calculate the required thickness using safety factors of 2-3 times the operating voltage.

Temperature Range: Match film thermal class to maximum operating temperature plus safety margin. Consider thermal cycling effects on dimensional stability.

Mechanical Stress: Evaluate tensile strength requirements for winding tension and vibration resistance. Higher stress applications need thicker films or reinforced grades.

Environmental Conditions: Assess exposure to moisture, chemicals, UV radiation, and contamination. Select appropriate surface treatments and barrier properties.

The comprehensive application guide covers various BOPET film types and their specific applications in electrical systems.

Installation Considerations

Proper installation ensures optimal performance and longevity. Key installation factors include:

• Handling procedures to prevent mechanical damage and contamination

• Winding tension control to avoid film stress and wrinkles

• Temperature conditions during installation to prevent thermal shock

• Surface preparation to ensure proper adhesion and contact

Professional installation teams with experience in BOPET film handling deliver superior results and minimize installation defects.

Maintenance and Monitoring

Regular inspection maintains insulation effectiveness and identifies potential issues before failure. Recommended maintenance includes:

• Visual inspection for physical damage, discoloration, or contamination

• Electrical testing to verify insulation resistance and dielectric strength

• Thermal monitoring to detect overheating and thermal degradation

• Moisture assessment to evaluate barrier property effectiveness

Industry standards provide guidelines for proper insulation resistance measurement and interpretation.

Tip: Infrared thermography can detect insulation degradation before electrical failure occurs, preventing costly equipment damage.

When selecting electrical insulation materials, consider BOPET film's proven performance advantages. For reliable supply and expert technical support, choose YUXING as your trusted BOPET film supplier for high-performance electrical insulation solutions.

FAQ

What makes BOPET film superior to traditional insulation materials?

BOPET film offers dielectric strength up to 300 kV/mm compared to 20-30 kV/mm for paper insulation. It also provides better thermal stability, moisture resistance, and mechanical durability.

Can BOPET polyester film withstand high-voltage applications?

Yes, BOPET film's high dielectric strength and excellent electrical properties make it suitable for high-voltage applications, including power transformers and switching equipment.

How does temperature affect BOPET film performance?

BOPET film maintains electrical properties from -40°C to 150°C (180°C for high-temperature grades). Performance remains stable across this range with minimal property degradation.

Is BOPET film environmentally friendly?

BOPET film is recyclable and produces fewer environmental emissions during manufacturing compared to traditional insulation materials. Its longer service life also reduces replacement frequency.

What thickness should I choose for my application?

Thickness depends on voltage requirements, mechanical stress, and space constraints. Consult technical specifications and consider safety factors of 2-3 times the operating voltage.