What is IEC 60674 and what does it cover?

IEC 60674 is the international standard for plastic films used in electrical insulation. It is divided into three parts: Part 1 covers definitions and general requirements, Part 2 specifies test methods, and Part 3 provides individual material specifications for PET, PP, PC, PI/Kapton, PEN, and PPS films.

What are the key differences between PET and polyimide (Kapton) films under IEC 60674?

PET offers mechanical strength at lower cost with thermal class 105–130°C. Polyimide (Kapton) provides superior high-temp performance up to 200°C+ with outstanding chemical resistance — preferred for aerospace, high-temp motors, and flexible PCBs.

What tests are required by IEC 60674 Part 2?

Dielectric strength, dissipation factor, tensile strength, thermal endurance, dimensional stability, tear strength, surface/volume resistivity, plus thickness, density, moisture absorption, and chemical resistance.

How are IEC 60674 films used in EV traction motors?

Used as slot liners (polyimide or PET/nomex), phase/turn insulation, hairpin winding insulation. 800V architectures demand higher dielectric strength and PD resistance. DC-link capacitors use ultra-thin PP films (2–12 μm).

IEC 60674 Plastic Films for Electrical Purposes – The Complete Guide 🎬⚡

The IEC 60674 series is the cornerstone international standard for plastic films used in electrical insulation. Whether you’re designing high-voltage capacitors for grid-scale power electronics, insulating hairpin windings in next-generation EV traction motors, or specifying substrates for flexible printed circuits, this standard defines the material grades, test methods, and acceptance criteria you cannot afford to ignore. 🔬

From polyethylene terephthalate (PET) films rated at 105–130 °C to ultra-high-temperature polyimide (Kapton®) films that withstand 200 °C and beyond, IEC 60674 provides a unified framework across three parts: definitions, test methods, and material-specific specifications. This article breaks down every aspect engineers need to know. 🏭

1. Overview of IEC 60674 – Structure and Scope 📋

Part 1 – Definitions and General Requirements

IEC 60674-1 establishes the vocabulary, classification system, and general requirements applicable to all plastic films used for electrical purposes.

Part 2 – Methods of Test

IEC 60674-2 is the engineering backbone of the standard:

Dielectric strength and breakdown voltage – per IEC 60243
Dissipation factor (tan δ) and permittivity
Tensile strength and elongation at break – MD and TD
Thermal endurance – per IEC 60216
Dimensional stability, surface/volume resistivity

Part 3 – Specifications for Individual Materials

PET, PP, PC, PI (Kapton®), PEN, PPS — covering 1.5 μm to 500 μm thickness range.

2. Material Comparison Table 🔬

Property	PET	PP	PC	PI (Kapton®)	PEN	PPS
Thermal Class (°C)	105–130	90–100	110–125	200–240	155	180–200
Dielectric Strength (kV/mm)	200–300	200–250	150–200	220–300	200–280	200–250
Dissipation Factor (tan δ)	0.002–0.005	0.0001–0.0005	0.001–0.01	0.002–0.003	0.003–0.005	0.0003–0.001
Tensile Strength (MPa)	150–250	100–150	60–80	170–230	200–270	150–200
Thickness Range (μm)	1.5–500	2–350	2–250	7.5–125	1.5–350	1.5–100
Relative Cost	Low	Low	Medium	High	Medium-High	Medium-High

3. Key Applications – From Capacitors to EV Motors 🔌

Capacitor Dielectrics 💡

PP films dominate AC/DC-link capacitors; PET for DC cost-sensitive; ultra-thin PP (2–12 μm) for EV traction inverters. 🔋

Motor and Generator Insulation ⚙️

PET for general-purpose; polyimide for EV traction motors and aerospace generators. Corona-resistant PI for inverter-duty. 🚗

Transformer Layer Insulation 🏗️

PET/PEN films for dry-type and distribution transformers.

Flexible Printed Circuits (FPC) 🔧

Polyimide is the substrate of choice — soldering resistance up to 280°C.

🎯 Engineering Design Insights

Thermal class must match the insulation system — align with IEC 60664 principles.
Dielectric strength is thickness-dependent — design with ≥2× safety factor vs. breakdown.
Corona/PD resistance matters — specify corona-resistant grades for inverter-duty. Reference IEC 60684.
Creepage and clearance coordination — combine solid insulation with per IEC 60664 creepage.
Fire safety — verify IEC 60695 flammability classification.
Environmental aging — humidity, chemical compatibility, radiation resistance.

4. IEC 60674 in the Era of Electrification ⚡🔋

800V EV architectures • SiC/GaN wide-bandgap semiconductors • Hairpin windings • Sustainable materials • Thinner films (<2 μm) for compact power electronics.

❓ Frequently Asked Questions (FAQ)

Q: What is IEC 60674?

International standard for plastic films in electrical insulation: Part 1 definitions, Part 2 tests, Part 3 material specs (PET, PP, PC, PI, PEN, PPS) from 1.5–500 μm.

Q: PET vs polyimide (Kapton®) differences?

PET: mechanical strength, lower cost, 105–130°C. Polyimide: 200°C+, aerospace/EV motors/flex PCBs.

Q: What tests in IEC 60674 Part 2?

Dielectric strength, tan δ, tensile, thermal endurance, dimensional stability, tear strength, resistivity.

Q: IEC 60674 films in EV traction motors?

Slot liners, phase/turn insulation, hairpin windings. 800V demands higher dielectric strength. DC-link caps use PP films (2–12 μm).

📚 Related Standards & Further Reading

🔗 IEC 60664 – Insulation Coordination
🔗 IEC 60684 – Flexible Insulating Sleeving
🔗 IEC 60695 – Fire Hazard Testing