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How to Choose Closed Cell Silicone Foam for Gasketing & Sealing
In the electronics industry, engineers must address not only thermal management challenges but also seal failure issues. Once seals fail or become damaged, they can lead to catastrophic failures in electronic products, such as water ingress, leakage, and short circuits.By studying the structural characteristics, advantages, and application cases of closed-cell silicone, Sheen Technology provides you with suitable sealing material selection solutions.
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Understanding Closed Cell Silicone Foam Properties & Specifications
The Science Behind Material CompositionThe core essence of closed-cell silicone foam is a chemically foamed high-performance elastomer. During manufacturing, gas is injected into liquid silicone, forming millions of independent, non-interconnected bubbles.
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Sheen technology silicone foam Material Performance Parameters Table
| Model | SA700-S-200 | SA700-S-260 | SA700-S-300 | SA700-S-350 | SA700-S-400 |
| Color | White,Grey,Black | Grey,Black | Grey,Black,Red | Grey,Black | Grey,Black |
| Density(kg/m³) | 200 | 230 | 290 | 350 | 400 |
| Thickness(mm) | 1.6~20.0±10% | 1.2~20.0±10% | 1.2~20.0±10% | 0.6~20.0±10% | 1.0~12.0±10% |
| Compression Set(@100℃) | <5% | <5% | <5% | <5% | <5% |
| Tensile Strength(kPa) | 100 | 120 | 200 | 280 | 350 |
| Elongation at Break | 60% | 70% | 60% | 90% | 80% |
| Thermal Conductivity(W/m·K) | 0.05 | 0.05 | 0.05 | 0.071 | 0.064 |
| Flame Retardancy Rating(UL 94) | V-0, HF-1 | V-0, HF-1 | V-0, HF-1 | V-0, HF-1 | V-0, HF-1 |
| Operating Temperature(℃) | -55~200 | -55~200 | -55~200 | -55~200 | -50~200 |
Why Choose Closed Cell Silicone Foam for Gasketing & Sealing?
Closed-Cell Structure: Similar to bubble wrap, containing air inside for waterproofing.Open-Cell Structure: Similar to sponge, absorbs water but is not waterproof.
The Difference Between “Foam” and “Sponge”
Silicone Sponge: Primarily made of rubber with a tough, rough outer layer.Silicone Foam: Produced by heating and vulcanizing liquid silicone, offering superior compressibility, resilience, and sealing performance.
Key performance advantages
- Low water absorption
- Wide temperature tolerance
- Low compression set
- Biocompatibility options
Seal and Gasket Performance Evaluation: Compression, Rebound, and Aging
In specific applications, the hardness of sealing gaskets can be measured by density:- Low Density: Suitable for lighter equipment housings or uneven surfaces.
- Medium Density: The industry standard for general-purpose gaskets.
- High density: Used for heavy-duty vibration damping sealing requirements.
Understanding Compression Set and Stress Relaxation
The silent killer of gaskets is Compression Set. This measures the material's ability to rebound after being compressed for an extended period. If a gasket is compressed to 50% for a year and fails to spring back when the enclosure is opened (or when the gap expands due to thermal expansion), the seal is lost.High-quality closed cell silicone foams exhibit a compression set of <5% (at 100°C), vastly outperforming materials like Neoprene, which can permanently deform (taking a "set") and lose sealing pressure over time.
Adhesive Compatibility (PSA Selection)
A gasket is only useful if it stays in place during assembly. Closed cell foams are frequently supplied with a Pressure Sensitive Adhesive (PSA) backing.Acrylic PSA: High tack, lower cost. Bonds well to most metals and plastics but has a lower temperature limit (~150°C).
Silicone PSA: Lower initial tack but extreme temperature resistance matching the foam itself. Essential for low-surface-energy materials or extreme heat applications.
Industry Case Studies: Closed Cell Silicone Foam in Action
EV Battery Housing Gasket
- Challenge: maintain dielectric isolation and prevent moisture ingress over temperature extremes and vibration.
- Solution: high-density closed cell silicone foam with specified dielectric strength and low compression set; die-cut preforms with PSA backing.
Outdoor 5G/Telecom Enclosure
- Challenge: long service life under sun, rain, salt fog and frequent site maintenance.
- Solution: UV-stable closed cell silicone foam with silicone adhesive on one face; gasket geometry to divert water.
Medical Device Enclosure Gasket
- Challenge: withstand repeated cleaning/sterilization and preserve IP while meeting biocompatibility.
- Solution: medical-grade silicone foam, validated for repeated disinfectant exposure.
Outdoor Telecom Cabinet (installation optimization)
- Challenge: large flange gaps and ease of assembly in the field.
- Solution: thick closed cell foam with mechanical retention and finger-friendly die-cuts to speed install.
Frequently Asked Questions regarding Silicone Foam Gaskets
Q: What is the difference between closed-cell silicone foam and open-cell silicone foam?A: Closed-cell foam traps air bubbles and blocks liquids; open-cell foam absorbs and adsorbs moisture.
Q: What is the difference between silicone foam and silicone rubber?
A: The primary difference lies in compressibility. Solid silicone rubber is incompressible, while silicone foam contains air bubbles and can be compressed to a smaller volume.
Q: Can closed-cell silicone foam be used for sound insulation?
A: Yes, but open-cell foam is typically better suited for absorbing sound waves, while closed-cell foam is more effective at blocking sound transmission.
Q: Can silicone foam be used for electromagnetic shielding?
A: Use conductive silicone foam grades or combine foam gaskets with conductive fabrics/metal contacts.
Q: Does silicone foam have flame retardant ratings?
A: Certain formulations achieve UL 94 or equivalent ratings.
Ready to validate your design? Don't guess on your next prototype. Contact us today to request a Silicone Foam Material Selector Card or a free sample kit to test different densities in your own housing.
