Conductive Foam Compression–Recovery Curve Analysis: How to Match Pressure Across Structural Gaps
In EMI shielding and sealing design, the compression and recovery force of conductive foam directly determines the reliability of long-term electrical contact. Excessive compression may deform housings, while insufficient pressure causes unstable conductivity.
As a leading EMI materials manufacturer, Konlida offers advanced high-resilience conductive foam such as the CD-880 PORON® series, proven for outstanding mechanical and electrical stability in 5G base stations and EV applications.
1. Compression–Recovery Testing Standards and Parameters
Mechanical performance of EMI foams is commonly evaluated under ASTM D575 and IEC 60352-2 standards, focusing on:
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Compression range: 10%–70% (simulating actual assembly compression)
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Test speed: 5 mm/min (to avoid dynamic interference)
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Temperature: 23°C ± 2°C (standard laboratory condition)
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Cycle count: 1–10 cycles (evaluating fatigue and recovery rate)
Results are plotted as a force–strain curve, helping engineers identify the optimal compression range for their assembly design.
2. Comparative Recovery Performance of Konlida Conductive Foams
| Product Model | Base Material | 20% Compression (N/cm²) | 50% Compression (N/cm²) | Recovery Rate (%) | Application |
|---|---|---|---|---|---|
| CD-550 | Silicone | 0.8–1.2 | 2.5–3.5 | 75–80% | Industrial & consumer electronics |
| CD-880 (PORON®) | High-resilience polyurethane | 1.0–1.5 | 3.0–4.0 | 90–95% | 5G base stations, automotive radar |
| CD-330 | PET fiber | 0.5–0.8 | 1.8–2.5 | 85–90% | Low-pressure sealing |
Tests show CD-880 maintains over 90% rebound even under 50% compression—significantly outperforming standard silicone foams.
In a 5G cabinet design, over-compression (4.5 N/cm²) caused casing deformation and EMI leakage. Switching to Konlida’s CD-880 conductive foam reduced pressure to 3.2 N/cm², maintaining stable contact while preventing structural damage.
3. Relationship Between Compression Force and Electrical Performance
Compression force has a direct impact on vertical contact resistance (MIL-STD-202G):
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<1 kg/cm²: Insufficient contact → resistance >20 mΩ
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1–3 kg/cm²: Stable conductive network → resistance <10 mΩ
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>5 kg/cm²: Layer damage → resistance rises again
When compression increases from 30% to 60%, surface resistance (per ASTM D4935) drops by ~40%. Beyond 70%, resistance rises again due to plastic deformation.
Konlida CD-880 maintains 0.05 Ω/□ surface resistance at 60% compression—superior to typical EMI foams.
Learn more about the electrical testing of conductive foams in Conductive Foam Surface Resistance Testing: A Practical Guide to ASTM D4935.
4. Design Recommendations for Compression Matching
Step 1: Determine Structural Pressure Limits
| Structure Type | Max Allowable Pressure | Recommended Product |
|---|---|---|
| Plastic housing | ≤3 N/cm² | CD-330 or CD-880 |
| Metal chassis | ≤6 N/cm² | CD-880 |
| Flexible PCB | ≤1 N/cm² | Ultra-thin CD-220 |
Step 2: Verify Long-Term Elastic Recovery
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Konlida’s foams undergo 10-cycle compression testing, with recovery loss <5%.
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High-temperature aging (70°C × 1000h) validates long-term performance for automotive-grade reliability.
Compression–recovery force is not a fixed number but a dynamic curve varying with compression rate. Understanding this curve enables engineers to precisely align mechanical resilience with electrical stability, preventing both over-compression and under-contact issues.
For a deeper understanding of conductive foam evolution and performance, see From Material to Application — The Evolution of Conductive Foam.
5. Comprehensive Testing and Material Optimization
Konlida provides a complete mechanical–electrical co-testing dataset, helping engineers achieve accurate impedance matching and structural optimization across product lifecycles.
Only by balancing mechanical elasticity and electrical conductivity can designers ensure truly reliable and durable EMI shielding performance in advanced electronic systems.
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