Can PI Heater Works at Temperatures Above 150°C?

Polyimide (PI) heaters are widely used in industries that demand precise and stable heating. Known for their flexibility, thin structure, and excellent insulation, these heaters are common in electronics, medical devices, aerospace equipment, and lithium battery systems.

However, many engineers often ask a key question — can a PI heater operate above 150°C? This article will explore how PI heaters work, their temperature limits, and what options are available for higher heat requirements.

What Is a PI Heater and How Does It Work?

A PI heater is a flexible heating element made by etching a thin metal foil (often copper or nickel alloy) into a specific circuit pattern, then laminating it between layers of polyimide film.

When voltage passes through the metal circuit, it converts electrical energy into heat. Because polyimide has excellent dielectric strength and thermal stability, the heat spreads evenly across the surface. The thin profile of the film ensures fast response and efficient thermal transfer.

PI heaters are often used in applications where space is limited or precise temperature control is critical.

What Materials Are Used in PI Heaters?

A typical PI heater consists of three main components:

• Polyimide Film (PI): Acts as the insulation layer. It resists chemicals and provides mechanical strength.
• Etched Foil Heating Element: Usually made from copper, nickel-chrome (NiCr), or constantan alloy.
• Adhesive Layer: Bonds the polyimide and metal foil together. The choice of adhesive affects flexibility and maximum working temperature.

Some designs also include pressure-sensitive adhesive (PSA) for easy installation on target surfaces.

What Is the Typical Operating Temperature of a PI Heater?

In most cases, a standard PI heater is made from polyimide film laminated with an etched foil circuit, usually copper or nickel alloy. These heaters are stable, compact, and capable of precise heating control.

The recommended continuous working temperature is below 130°C, while short-term exposure can reach up to 150°C. Within this range, the heater maintains excellent insulation and mechanical strength without delamination or performance loss.

Why Can’t PI Heaters Exceed 150°C for Long-Term Use?

Although PI heaters have impressive heat tolerance, several technical barriers prevent them from operating stably above 150°C:

• Film degradation: Standard polyimide film begins to lose strength and flexibility when the temperature exceeds its rated thermal limit.
• Adhesive failure: The bonding adhesive used during lamination may soften, weaken, or chemically break down at higher temperatures.
• Equipment limitation: Manufacturing a high-temperature PI heater requires special high-temp pressing equipment that can sustain greater pressure and heat, which most factories currently lack.

Because of these reasons, PI heaters are generally not suitable for continuous operation above 150°C under normal conditions.

Are High-Temperature PI Films Possible?

Yes, but they are still under development and testing. Advanced material suppliers are experimenting with enhanced polyimide films that can maintain stability beyond 150°C and potentially reach 200°C or higher.

However, this improvement also requires compatible adhesives, etching materials, and production equipment capable of handling such conditions. Until these materials become standardized and reliable, mass production of high-temperature PI heaters remains challenging.

What Happens If a PI Heater Overheats?

When a PI heater exceeds its rated temperature for too long, several issues can occur:

• The polyimide film may darken or become brittle.
• The adhesive layer can lose bonding strength, causing delamination.
• The resistance pattern may change, leading to uneven heating or electrical failure.

In extreme cases, continuous overheating could result in short circuits or insulation breakdown. That’s why proper temperature control is essential when operating near the upper limit.

What’s the Difference Between Standard PI and High-Temperature PI Film?

The key difference lies in material composition and manufacturing tolerance.

Standard PI film supports long-term operation up to around 130°C, with short bursts to 150°C.

High-temperature PI film, on the other hand, is made using advanced formulations designed to endure 200°C or higher.

However, high-temperature-grade PI films are still in the research and testing phase. Besides, the entire lamination process must also handle these extreme conditions to maintain durability.

When Should You Choose a Silicone Heater Instead of a PI Heater?

If your application requires higher temperatures or needs to handle frequent thermal cycling, silicone rubber heaters are a better choice.

Silicone heaters can typically:

• Operate continuously up to 200°C
• Withstand short-term peaks of 230°C
• Provide excellent flexibility and moisture resistance

They are ideal for industrial, automotive, and outdoor heating applications where PI films would be less stable.

Can PI Heaters Be Combined with Temperature Sensors?

Yes. PI heaters are often paired with thermistors, RTDs, or thermocouples for precise temperature feedback.

By integrating these sensors, the heater can be connected to a temperature controller that regulates power output automatically. This helps prevent overheating and maintains stable performance, especially when working near the temperature limit.

Such designs are commonly used in battery warming pads, camera modules, and laboratory instruments.

How to Ensure Safe Operation of PI Heating Films?

To ensure safe and stable operation, follow these essential practices:

• Do not exceed the rated voltage or temperature.
• Avoid bending, tearing, or sharp folding of the heater film.
• Make sure the heater is installed flat on the surface for proper heat transfer.
• Use a temperature control system to prevent overheat damage.
• For high-voltage models, ensure proper insulation to prevent leakage.

Proper installation and controlled operation will greatly extend the heater’s service life.

In Conclusion

Currently, standard PI heaters are safe for long-term use below 130°C and short-term peaks up to 150°C.

Operating above that range is only possible with special high-temperature PI materials, which are still being tested and not yet available for large-scale production. If your application requires a higher temperature range, silicone rubber heaters are a more dependable solution.

At Danyu electronics, we continue to explore advanced PI materials and fabrication methods for next-generation flexible heaters. Our engineering team ensures every heater offers precise control, long service life, and consistent reliability — no matter the application.

Frequently Asked Questions (FAQ)

1. What is the maximum continuous working temperature of a PI heater?

Most standard PI heaters can operate continuously up to 130°C, with short-term operation up to 150°C.

2. Can PI heaters be customized for higher temperatures?

Yes, but this requires special high-temperature polyimide films and heat-resistant adhesives, which are still under testing and not yet mass-produced.

3. What heater types are better for temperatures above 150°C?

Silicone rubber heaters are currently the most common alternative, supporting up to 200°C continuous and 230°C short-term operation.

4. Why can’t regular PI heaters exceed 150°C?

Because the film and adhesive layers begin to degrade under prolonged heat, affecting insulation, stability, and overall safety.

5. Where can I get reliable PI or silicone heaters for industrial use?

You can contact Danyu electronics, a professional PCB and flexible heater manufacturer, providing customized PI and silicone heating films with rigorous quality control and global delivery support.

标签：pi flexible heater · pi heaters · polyimide heater