What is the difference between Mylar and Kapton?

Introduction to Mylar and Kapton

Mylar and Kapton are two popular materials used in various industries for their unique properties. Both materials are known for their high tensile strength, thermal stability, and electrical insulation properties. However, there are some key differences between the two that make them suitable for different applications.

What is Mylar?

Mylar is a trademarked name for a type of polyester film developed by DuPont. It is made from stretched polyethylene terephthalate (PET) and is known for its high tensile strength, excellent electrical insulation properties, and good chemical resistance. Mylar is transparent, flexible, and has a smooth surface, making it ideal for a wide range of applications.

What is Kapton?

Kapton is a trademarked name for a type of polyimide film developed by DuPont. It is known for its exceptional thermal stability, high tensile strength, and excellent electrical insulation properties. Kapton maintains its properties over a wide temperature range, from -269°C to +400°C, making it suitable for applications in extreme environments.

Properties of Mylar and Kapton

Tensile Strength

Both Mylar and Kapton have high tensile strength, but Kapton has a slightly higher strength than Mylar. The tensile strength of Mylar is around 25,000 psi, while Kapton has a tensile strength of approximately 30,000 psi. This makes Kapton more suitable for applications that require higher mechanical strength.

Thermal Stability

Kapton has a significantly higher thermal stability compared to Mylar. Kapton can maintain its properties over a wide temperature range, from -269°C to +400°C, while Mylar has a maximum continuous operating temperature of around 150°C. This makes Kapton the preferred choice for applications that involve exposure to high temperatures.

Electrical Insulation

Both Mylar and Kapton have excellent electrical insulation properties. Mylar has a dielectric strength of around 7,000 volts per mil, while Kapton has a dielectric strength of approximately 7,700 volts per mil. This makes both materials suitable for applications that require electrical insulation, such as in capacitors and transformers.

Chemical Resistance

Mylar and Kapton have good chemical resistance, but Kapton has a slightly better resistance to certain chemicals. Mylar is resistant to most solvents, oils, and acids, but can be affected by strong alkaline solutions. Kapton, on the other hand, is resistant to most solvents, oils, acids, and alkaline solutions.

Applications of Mylar and Kapton

Mylar Applications

Mylar is used in a wide range of applications due to its unique properties. Some of the common applications of Mylar include:

  1. Food packaging: Mylar is used in food packaging to preserve the freshness and flavor of the food.
  2. Insulation: Mylar is used as an insulation material in transformers, capacitors, and other electrical devices.
  3. Printing: Mylar is used as a printing substrate for labels, tags, and other printed materials.
  4. Balloons: Mylar is used to make metallic balloons for parties and celebrations.
  5. Solar panels: Mylar is used as a reflective material in solar panels to increase their efficiency.

Kapton Applications

Kapton is used in various industries for its exceptional thermal stability and electrical insulation properties. Some of the common applications of Kapton include:

  1. Aerospace: Kapton is used in the aerospace industry for its ability to withstand extreme temperatures and radiation.
  2. Electronics: Kapton is used as an insulation material in printed circuit boards (PCBs), flex circuits, and other electronic devices.
  3. 3D printing: Kapton tape is used as a build surface in 3D printing to improve the adhesion of the printed material.
  4. Medical devices: Kapton is used in medical devices, such as catheters and endoscopes, for its biocompatibility and resistance to sterilization methods.
  5. Automotive: Kapton is used in the automotive industry for its ability to withstand high temperatures and provide electrical insulation.

Kapton in PCB Manufacturing

Kapton is widely used in the manufacturing of printed circuit boards (PCBs) due to its excellent thermal stability and electrical insulation properties. Kapton is used as a substrate material for flexible PCBs and as a cover lay material for rigid PCBs.

Advantages of Using Kapton in PCBs

  1. High temperature resistance: Kapton can withstand high temperatures up to 400°C, making it suitable for applications that involve soldering and other high-temperature processes.
  2. Excellent electrical insulation: Kapton has a high dielectric strength, which makes it an excellent insulation material for PCBs.
  3. Flexibility: Kapton is flexible and can be bent and folded without losing its properties, making it suitable for flexible PCBs.
  4. Dimensional stability: Kapton has a low coefficient of thermal expansion, which means it maintains its dimensions even when exposed to temperature changes.
  5. Resistance to chemicals: Kapton is resistant to most chemicals used in PCB manufacturing, such as solvents and cleaning agents.

Types of Kapton Used in PCBs

There are different types of Kapton used in PCB manufacturing, each with its own unique properties and applications.

Type of Kapton Properties Applications
Kapton HN General-purpose, high temperature resistance Cover lay for rigid PCBs, flexible PCBs
Kapton FN Low coefficient of friction, high temperature resistance Flexible PCBs, LCD connectors
Kapton FPC Ultra-thin, high flexibility, high temperature resistance High-density flexible PCBs, wearable electronics
Kapton MT High modulus, high temperature resistance High-speed flexible PCBs, aerospace applications
Kapton CR High chemical resistance, high temperature resistance Chemical processing, fuel cells, batteries

Mylar vs. Kapton: Which One to Choose?

When it comes to choosing between Mylar and Kapton, it depends on the specific application and the required properties. Here are some factors to consider when choosing between the two materials:

  1. Temperature resistance: If the application involves exposure to high temperatures, Kapton is the better choice due to its higher thermal stability.
  2. Mechanical strength: If the application requires higher mechanical strength, Kapton is the better choice due to its higher tensile strength.
  3. Chemical resistance: If the application involves exposure to strong alkaline solutions, Kapton is the better choice due to its better chemical resistance.
  4. Cost: Mylar is generally less expensive than Kapton, so if cost is a major factor, Mylar may be the better choice.

Frequently Asked Questions (FAQ)

  1. Can Mylar be used in high-temperature applications?
  2. Mylar has a maximum continuous operating temperature of around 150°C, so it is not suitable for applications that involve exposure to very high temperatures. For high-temperature applications, Kapton is the better choice.

  3. Is Kapton suitable for use in medical devices?

  4. Yes, Kapton is biocompatible and resistant to sterilization methods, making it suitable for use in medical devices such as catheters and endoscopes.

  5. Can Kapton be used in flexible PCBs?

  6. Yes, Kapton is widely used in the manufacturing of flexible PCBs due to its flexibility, high temperature resistance, and excellent electrical insulation properties.

  7. Is Mylar transparent?

  8. Yes, Mylar is transparent, which makes it suitable for applications that require clarity, such as in food packaging and printing.

  9. Can Kapton be used in 3D printing?

  10. Yes, Kapton tape is commonly used as a build surface in 3D printing to improve the adhesion of the printed material to the build plate.

Conclusion

Mylar and Kapton are two popular materials used in various industries for their unique properties. While both materials have high tensile strength and excellent electrical insulation properties, they differ in their thermal stability, chemical resistance, and cost. Mylar is generally less expensive and has good chemical resistance, while Kapton has exceptional thermal stability and slightly better chemical resistance. The choice between the two materials depends on the specific application and the required properties. In the PCB industry, Kapton is widely used as a substrate material for flexible PCBs and as a cover lay material for rigid PCBs due to its excellent thermal stability, electrical insulation properties, and flexibility.