What Are the Difference between Polyimide Flexible Heater and FPC？

Introduction

While polyimide (PI) flexible heaters and flexible printed circuit boards (FPCs) may appear similar in structure, their materials, tolerances, and purposes are fundamentally different. PI flexible heaters are designed for heat generation and thermal management, whereas FPCs focus on signal transmission and electrical interconnection. This article explains their differences in features structures, and functions, helping engineers choose the optimal solution for their applications.

Features of Polyimide Flexible Heater

As part of thermal management solutions, the core function of polyimide flexible heaters is to convert electrical energy into heat, providing a stable and uniform temperature for heating, preheating, or maintaining a specific thermal environment. Considering thermal requirements and safety, these custom flexible heaters require precise resistance control, often with a ±0.05% line width tolerance, to ensure resistance values remain within the standard ±5% range.

• A flexible heater delivers high heating efficiency and a fast thermal response with uniform temperature distribution, allowing rapid heat-up times to meet application demands quickly and ensuring consistent warmth across the entire surface.

• As a custom product, an electronic heating film can be specifically designed to fit different sizes, shapes, wattages, temperatures, and so on. With good flexibility and customizable shapes, it can bend and conform to curved or irregular surfaces, making it suitable for a wide range of uses.

• Its ultra-thin profile and lightweight construction can fit easily into compact or limited spaces without adding bulk and compromising performance.

Features of FPC

FPC is a type of PCB that is primarily designed for signal transmission and component interconnection in electronic devices. They usually have a ±20% line width tolerance, which is sufficient for routing signals.

• Flex PCBs are also flexible and lightweight, which can be easily bent, folded, and integrated into compact or irregularly shaped electronic products.

• Thanks to their high wiring density and thin profile, FPCs help reduce the size and weight of devices while maintaining performance.

• Its ability to support three-dimensional routing provides greater design freedom for complex assemblies.

Structure of PI Flexible Heater

A PI flexible heater typically consists of:

• Insulation Layer: Polyimide film is ideal for electrical insulation and high-temperature resistance.

• Heating Element: Alloy materials such as brass, pure copper, stainless steel (SUS304), or FeCrAl alloy, selected for their higher resistivity, selected for their high resistivity and stable heat generation.

• Additional Components: Thermostat switches, NTC, adhesive backing, and lead wires (for power connection).

Structure of Single-layer FPC

A single-layer FPC is composed of:

• Substrate Layer: Polyimide film providing electrical insulation and high-temperature resistance.

• Electric Conductors: Copper foil with low resistivity, ideal for signal integrity, but unsuitable for generating significant heat.

• Adhesive: The sticky film is made of epoxy resin, for mechanical stability and layer bonding.

Applications of PI Flexible Heater

Typical applications of PI flexible heaters include consumer electronics (hand warmers, beauty devices, and wearable heating products), new energy vehicles (preheating and insulation for EV lithium battery packs), and medical and healthcare (physiotherapy devices, incubators, and temperature-controlled instruments).

Applications of FPC

Common applications of flex PCB include consumer electronics (smartphones, tablets, laptops, digital cameras, and wearable tech), automotive electronics (LED headlights, interior lighting, and driver assistance systems), industrial controllers, and medical devices (MRIs, CT scanners, and wearable monitoring devices), anywhere that requires lightweight, space-efficient circuit routing.

Conclusion

Although PI flexible heaters and FPCs share a similar layered structure, their purposes are entirely different. PI flexible heaters are built for precision thermal management in applications ranging from EV battery heating to medical incubators, while FPCs enable complex electronic signal routing in consumer electronics and industrial systems. Understanding these differences is essential to selecting the right solution for your engineering needs.