TF-PET-6um-100mm

Choose PET over BOPP when: Higher temperature rating is required (up to 125C vs 105C for BOPP). DC applications where higher dielectric constant provides capacitance density advantage. Space-constrained designs where maximum capacitance per volume is needed. Applications with moderate ripple current at lower frequencies. Cost is secondary to performance and reliability. Avoid PET for: High-frequency AC applications (>1kHz) where dissipation factor is important. Applications requiring the lowest possible ESR. Very high frequency switching applications. The higher dissipation factor of PET (0.5% vs 0.02% for BOPP) results in more heat generation under AC conditions.

Select PET for high temperature DC applications and when maximum capacitance density is required. Select BOPP for AC applications and high frequency filtering.

PET film capacitors can operate at temperatures up to 125C, which is 20C higher than standard BOPP films (105C). However, for extended lifetime, it's recommended to operate at no more than 85-95C under normal conditions, with 125C reserved for short-term overload conditions. The temperature rating depends on the voltage stress and expected lifetime. At higher temperatures, the film's dielectric strength decreases and the self-healing properties change. For automotive applications with under-hood temperatures, PET's higher temperature rating provides valuable margin. Always consider the hottest spot temperature in the capacitor, which is typically at the center of the winding. Proper thermal design including adequate surface area and heat dissipation is essential for reliable high-temperature operation.

Use PET film for applications requiring 105-125C operation. Implement proper thermal management to ensure the capacitor operates within safe temperature limits.

PET film has slightly different mechanical properties compared to BOPP, which affects winding characteristics. PET has higher tensile strength and modulus, making it slightly stiffer than BOPP. This can result in: More stable windings with less tendency for looseness or sagging. Slightly higher tension requirements during winding. Better dimensional stability at elevated temperatures. Less stretch during winding, which can be beneficial for maintaining consistent capacitance. The higher stiffness may require adjustment of winding machine tension settings. Winding speed may need to be slightly reduced compared to BOPP to prevent film damage. End spray adhesion is generally good with both materials. Overall, PET winds well with proper machine setup and is widely used for high-reliability capacitors.

Adjust winding machine tension settings when switching between PET and BOPP films. Contact us for recommended winding parameters for Tongfeng films.

PET film has a dielectric constant of approximately 3.3, compared to 2.2 for BOPP. This means that for the same film thickness and capacitor dimensions, a PET capacitor will have approximately 50% higher capacitance than a BOPP capacitor. For example, a capacitor using 6um BOPP film might have 10uF capacitance, while the same design using 6um PET film would have approximately 15uF. This higher capacitance density can be significant for space-constrained applications. However, note that PET is typically not used for AC applications above a few hundred Hz due to higher dissipation factor. For DC applications, the higher capacitance density of PET is a significant advantage. When comparing voltage ratings, both materials have similar dielectric strength, so the voltage capability is comparable for the same thickness.

Use PET when maximum capacitance per unit volume is required for DC applications. The 50% higher capacitance density can significantly reduce capacitor size.

PET films have similar handling requirements to BOPP films with a few considerations: PET is more hygroscopic than BOPP, meaning it absorbs more moisture from the atmosphere. Store in controlled humidity conditions (40-60% RH). Higher stiffness means PET is slightly more susceptible to creasing if mishandled. Handle with care during loading onto winding machines. PET has higher static charge tendency than BOPP. Proper ionization equipment may be needed during unwinding. Recommended storage conditions are the same as BOPP: 5-35C, 40-60% RH, protected from UV light. Shelf life is typically 12-18 months under proper storage conditions. Once opened, use the roll within a reasonable time to prevent moisture absorption.

Handle PET films with care to prevent creasing. Store in controlled humidity conditions and use appropriate static control measures during processing.

Tongfeng offers various metallization patterns for PET films including: Full area metallization - complete coverage for maximum capacitance. Heavy edge - thicker metallization at edges for improved current handling. Segmented (pattern) metallization - discrete metallized sections for specific capacitor designs. Tapered metallization - gradually varying thickness for voltage grading. Custom patterns - designed to customer specifications for specialized applications. The heavy edge pattern is most common for standard capacitors. Segmented patterns are used for safety capacitors and specific high-voltage designs. Custom patterns can be developed for unique applications with minimum order quantity requirements. All patterns can be produced with various metallization thicknesses from light to heavy.

Contact us with your specific pattern requirements. Standard heavy edge patterns are available from stock, custom patterns require minimum order quantities.