Manufacturing Process of PI Heating Films: From PI Cutting to SMT

Polyimide (PI) heating films are widely used in electronics, medical devices, automotive systems, EV batteries, aerospace, and precision instruments. Their durability, thinness, and stability make PI heaters ideal for applications requiring fast, uniform, and controllable heating. Understanding the manufacturing process helps engineers design higher-performing heating systems and ensures buyers can evaluate the quality of a PI heater supplier.

This article provides a step-by-step breakdown of how PI heating films are produced — from raw material selection to SMT assembly and final testing.

1. Raw Material Selection

The process begins with selecting high-quality materials:

Polyimide Film (PI) – high temperature resistance, chemical stability.
Copper Foil – usually 12–35 μm thick.
Adhesive Layer – high-temperature acrylic or adhesive-free lamination.

Quality materials directly determine heater performance, flexibility, and lifespan.

2. PI Film Cutting

The raw roll of PI+copper laminate is cut into sheets that match production size. This ensures consistent dimensions for future processing.

Laser cutting is often used for precision and low waste.

3. Circuit Pattern Exposure & Etching

This is one of the core manufacturing steps where the heating circuit pattern is created.

Steps include:

Photoresist coating — copper surface is coated.
UV exposure — circuit design is printed through a mask.
Chemical etching — unwanted copper is removed.
Stripping — photoresist is cleaned off.

The result is a precisely etched copper heating circuit with controlled resistance.

4. PI Lamination

After the circuit is etched, another layer of PI film is laminated on top. This protects the copper and forms the final flexible heater structure.

Lamination includes:

Heat pressing
Vacuum curing
Adhesive bonding or adhesive-free fusion

The lamination quality determines insulation, flexibility, and resistance to delamination.

5. Golden Finger & Connector Processing

High-end PI heaters use golden finger technology — gold-plated copper pads for superior conductivity and corrosion resistance.

Improved durability
Better current carrying capability
Smaller and thinner connection interface

SMT connectors may also be added depending on the application.

6. SMT Assembly: Thermistors, Sensors, Connectors

SMT is one of the most important processes in modern PI heater manufacturing.

Common SMT components:

NTC Thermistors (10K / 100K)
Thermal fuses
Temperature sensors (PTC, RTD)
SMT connectors

SMT ensures precise temperature control and supports integration with modern electronics.

7. Die Cutting & Shape Forming

After SMT processing, the PI heater is cut into its final shape.

Cutting methods:

Die cutting
Laser cutting
Plotter cutting

8. Final Quality Inspection

Every PI heating film undergoes a strict QC process:

Resistance test
Dielectric strength
Insulation test
Temperature uniformity test
Peel strength
Full functional testing

Only heaters that pass all inspection steps are packaged and shipped.

Conclusion

The manufacturing process of PI heating films is highly technical and requires precise engineering control at each step. From PI cutting to circuit etching, lamination, golden finger treatment, SMT assembly, and quality testing — every stage determines the final heater’s reliability and performance.

Understanding this workflow helps engineers choose the right PI heater supplier and design better thermal systems for their projects.