Aging Test, Insulation Test, and Safety Standards for PI Heaters

To ensure durability, stability, and safety, PI (Polyimide) flexible heaters undergo a series of reliability and electrical safety tests. These include aging tests, insulation resistance tests, dielectric withstand tests, and compliance with international safety standards. This guide explains how each test works and why it matters for manufacturers and end-users.

1. Why Reliability and Safety Testing Is Essential

PI heaters are widely used in batteries, medical devices, EV modules, sensors, aerospace, and consumer electronics. In these applications, heater failure can lead to:

Electrical short circuits
Thermal runaway or overheating
Device malfunction or shutdown
Burn hazards for users

That’s why systematic testing is a critical part of PI heater manufacturing.

2. Aging Test (Aging & Burn-In Test)

The aging test (or burn-in test) evaluates long-term performance by running the heater continuously under elevated temperature or voltage to reveal potential early failures.

2.1 What the Aging Test Evaluates

Thermal stability
Resistance drift over time
Bonding strength between layers
Thermal uniformity retention
Electrical reliability under heat stress

2.2 Typical Aging Test Conditions

Temperature: 80°C–120°C  
Duration: 8–72 hours (depending on customer spec)
Voltage: 110%–150% of rated voltage  
Evaluation: resistance changes must stay within ±5%

2.3 Why Aging Test Matters

Eliminates early failures (infant mortality failures)
Ensures heater stability before delivery
Prevents resistance drift in real applications

3. Insulation Resistance Test

The insulation test checks the electrical isolation between the heater circuit and the external environment. PI heaters rely on excellent electrical insulation to prevent shocks or shorts.

3.1 Test Method

Using a megohmmeter (500V~1000V), resistance is measured between:

Heater circuit → outer PI film
Heater circuit → ground
Heater circuit → metal parts (if any)

3.2 Typical Results Requirements

Insulation resistance: ≥ 100 MΩ  
Test voltage: 500V DC  
Pass condition: no breakdown, stable resistance

3.3 Why Insulation Test Matters

Prevents electrical leakage in humid environments
Ensures user safety
Ensures long-term reliability in EV, aerospace, and medical devices

4. Dielectric Withstand Voltage (Hipot Test)

The dielectric withstand (Hipot) test verifies that the insulation can withstand very high voltage without breakdown.

4.1 Test Conditions

Test voltage: 1000–3000V AC  
Duration: 1–60 seconds  
Leakage current requirement: < 1–5 mA  
Pass condition: no breakdown, no sparking, no insulation damage

4.2 Importance of Hipot Testing

Prevents catastrophic electric shock or fire
Ensures insulation can withstand real-world surges
Mandatory for medical and aerospace equipment

5. Mechanical and Environmental Tests

5.1 Bending Test

Bending radius: 5–10 mm  
Cycles: 2000–5000 cycles  
Requirement: no circuit crack, no delamination

5.2 Humidity Test

Temperature: 60°C  
Humidity: 90–95%RH  
Duration: 48–96 hours  
Requirement: insulation ≥ 100 MΩ after test

5.3 Thermal Shock Test

Cycle: -40°C → +85°C  
Duration: 30 minutes per stage  
Cycles: 20–50 cycles  
Requirement: resistance drift < ±5%

6. International Safety Standards for PI Heaters

PI heaters must meet global electrical and material safety certifications depending on the application.

6.1 Key Standards

UL 94 V-0 (flame retardancy)
UL 499 (electric heating appliances)
IEC 60601-1 (medical safety)
ROHS & REACH (material compliance)
ISO 9001 / 14001 (quality & environmental)
IPC-2223 (flex circuit design)
ASTM D5470 (thermal measurement)

6.2 Why Standards Matter

Guarantee safety for global markets
Ensure material and manufacturing consistency
Reduce risk for battery, medical, and aerospace applications

7. Example of a PI Heater Safety Test Report

MODEL: PI-HT-3020
Voltage: 24V
Power: 30W
------------------------------------------
Aging Test: PASS (ΔR = +1.8%)
Insulation Test: PASS (500V → 200 MΩ)
Hipot Test: PASS (1500V AC, 30 sec)
Bending Test: PASS (5000 cycles)
Humidity Test: PASS (100 MΩ)
Thermal Shock: PASS (ΔR = +2.1%)
------------------------------------------
Status: APPROVED FOR MASS PRODUCTION

Conclusion

Aging tests, insulation resistance tests, and compliance with safety standards ensure that PI heaters operate reliably over long periods and in harsh environments. Manufacturers that perform strict QC testing deliver safer and more stable heating solutions for all industries—from consumer electronics to aerospace.