Conductivity Loss: Why EMI Gaskets Fail after Thermal Cycling.

Conductivity Loss: Why EMI Gaskets Fail after Thermal Cycling

Problem Statement

EMI gaskets often experience conductivity loss after repeated thermal cycling between -40°C and 150°C. This failure compromises electromagnetic shielding, leading to signal interference in electronic systems.

Material Science Analysis

Conductivity loss occurs due to polymer matrix degradation and filler particle migration. Silicone rubber (VMQ) commonly fails because its low thermal stability accelerates filler oxidation. Fluorocarbon rubber (FKM) outperforms VMQ due to its higher fluorine content (66-70%), which enhances thermal stability and chemical resistance. FKM maintains filler dispersion integrity, ensuring consistent conductivity.

Technical Specs

• Material: FKM (Fluorocarbon Rubber)
• Shore A Hardness: 70 ± 5
• Tensile Strength: 12 MPa
• Elongation at Break: 200%
• Temperature Range: -40°C to 200°C
• Compression Set: 20% (22 hrs at 200°C)
• Chemical Resistance: Resistant to oils, fuels, and acids

Material Comparison

Material	Temperature Range (°C)	Compression Set (%)	Chemical Resistance	Conductivity Retention
FKM	-40 to 200	20	High	95%
VMQ	-60 to 150	35	Moderate	70%
EPDM	-50 to 150	30	Low	60%

Standard Compliance

RubberQ adheres to IATF 16949 standards, ensuring batch-to-batch consistency. Our in-house compounding process controls polymer ratios, fillers, and curing agents to meet ASTM D2000 material callouts and ISO 3601 sealing requirements. Each batch undergoes rigorous testing, including ASTM D429 adhesion testing, to guarantee zero-delamination quality.

For custom material compound development or IATF 16949 documentation, consult RubberQ's engineering department.