Dielectric Materials in Film Capacitors: Polyester vs. Polypropylene

Film capacitors are integral components in various electronic devices and help store and discharge electrical energy. They have all the hype due to their high performance and extended operational lifespan. Film caps are generally built using a dielectric material, typically a plastic sheet sandwiched between the conductive layers of the capacitor.


The dielectric material holds significant importance, as it dictates crucial electrical attributes of the capacitor. They range from capacitance and voltage rating to temperature stability. Multiple types of dielectric for film caps are available, yet polyester and polypropylene are the most notable choices.

In this article, we are going to offer in-depth insights into the two dielectric types used in film caps: polyester and polypropylene. Continue reading!


Role of Dielectric Material in Film Capacitors

The dielectric material placed in film caps determines its properties like:


  1. Voltage Rating

The dielectric material’s properties determine the maximum voltage film caps can withstand without breaking down.


  1. Capacitance

The dielectric material influences the capacitance of film caps. Different materials have varying dielectric constants, which affect the capacitor’s ability to store electrical charge.


  1. Frequency Response

Dielectric materials also influence capacitors’ behavior at different frequencies. Some materials are better suited for high-frequency applications, while others excel at low frequencies.


Types of Film Capacitor Dielectric Material

Here are the two common types of dielectric materials:


  • Polyester

Polyester film caps, or Mylar capacitors, utilize a dielectric made from polyester, a synthetic polymer. Their compact size, good insulation properties, and cost-effectiveness help them stand out. Commonly popular for their stable electrical performance and moderate capacitance values, they are used in various electronic applications – filtering, coupling, and energy storage.


  • Polypropylene 

Polypropylene film caps feature a thin dielectric film made of polypropylene, a thermoplastic material, and offer excellent insulation properties. Engineers often prefer polypropylene capacitors, looking at the caps’ high reliability, low loss, and wide temperature tolerance, making them suitable for applications like audio systems and power electronics.


Characteristics of Polyester Film Capacitors 

Polyester film caps are known for their affordability and versatility in electronic applications. A few characteristics that make them stand out from other types include;


  • Wide Temperature Range: Polyester film capacitors typically operate reliably in a broad temperature range, spanning from -55°C (-67°F) to +125°C (257°F). This wide operating temperature makes them suitable for various environmental conditions.
  • High Dielectric Constant:Polyester film caps typically exhibit a higher dielectric constant compared to some other dielectric materials. This characteristic contributes to their moderate capacitance values, which are suitable for various applications but may not be ideal for high-capacitance requirements.


Characteristics of Polypropylene Film Capacitors

Polypropylene film caps are recognized for their low dielectric losses and stable performance, making them perfect for applications where precision and accuracy are needed. Some characteristics of a polypropylene film cap are:


  • High Dielectric Strength:Polypropylene film caps exhibit strong dielectric strength and low dielectric constant, enabling them to withstand high voltage levels without breaking down.
  • Excellent Self-Healing Properties: Polypropylene film caps have excellent self-healing capabilities that allow them to repair small defects and faults, maintaining good performance over time.
  • High Insulation Resistance: Polypropylene film caps offer high insulation resistance, ensuring that the dielectric material doesn’t allow current leakage and maintains its insulating properties over time.


Comparison of Polyester and Polypropylene Film Caps 

Polyester capacitors employ a polyester dielectric, offering a moderate temperature stability range, typically spanning from -55°C to +125°C. They find versatility in various applications, including bypassing, decoupling, and certain noise suppression circuits. Polypropylene capacitors, on the other hand, are the preferred choice for precision applications, particularly in audio circuits, power supplies, and high-frequency electronics.


However, it’s important to note that polypropylene capacitors are usually slightly more expensive than their polyester counterparts due to their superior electrical characteristics and durability.


Top Polypropylene Film Capacitors You Should Try! 

DIN Electronics is among the best capacitor manufacturers, and we offer an extensive range of polypropylene film caps. Here are some top polypropylene film caps:


C13 Polypropylene Film Capacitors

The C13 Capacitors utilize durable polypropylene film/foil material and function reliably in a temperature range from -40°C to 105°C. Their voltage options are various, like 250V, 400V, 630V, and 800V, along with covering a capacitance range from 0.001μF to 0.1μF. This makes them versatile components for various high-pulse and high-current electronic applications.

C12 Plastic Case High Voltage Metallized Polypropylene Film Capacitors

The C12 Capacitors feature a robust polypropylene film/foil construction and have a wide temperature range of -40°C to 105°C. They are available in voltage ratings from 400V to 2000V and have a capacitance range of 0.00047μF to 0.68μF, which makes them a reliable option for power factor correction and various electronic applications.


Film capacitors, critical electronic components known for energy storage and discharge, rely on dielectric materials to define their properties. Polyester and polypropylene are prominent dielectric options, each with unique attributes. Polyester offers moderate temperature stability (-55°C to +125°C) and is cost-effective, while polypropylene excels in precision applications with high insulation resistance and high dielectric strength.


If you are searching for high-quality polypropylene film caps, there’s no option better than DIN Electronics. We have a wide range of polypropylene caps that perform efficiently and accurately in electronic systems. Get in touch and have your plastic film capacitor from us now!



Get a Quote