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Conductive Foam Gasket Types: A Clear Guide to FOF, SMT, AIR LOOP, and More
“I need a conductive foam gasket.”
“That depends. FOF or SMT? Full wrap or half wrap? Nickel, gold, tin, or carbon? D-shape or P-shape?”
This is a normal conversation in Konlida’s sales and engineering teams. For new engineers and buyers, the naming system can feel confusing because the same product may be described from different angles.
If you are still new to the topic, start with What Is EMI Foam? A Complete Guide to EMI Foam. It gives a solid foundation for understanding how EMI shielding foam works in electronic assemblies.
This guide organizes conductive foam into five practical classification dimensions. Once you understand them, you can read a part number or product description much faster and identify the right structure for your application.
1. Classification by Structure and Manufacturing Process
This is the most fundamental way to categorize a conductive foam gasket. It is based on how the product is built and how it is manufactured.
| Structure Type | Short Name | Key Feature | Typical Use |
|---|---|---|---|
| Fabric over Foam Gasket | FOF | Conductive fabric wrapped around a foam core | Traditional EMI grounding and sealing |
| SMT Gasket | SMT | Silicone core + conductive PI film + metal pads, reflow solderable | Automated PCB assembly |
| AIR LOOP Conductive Foam | ALG / LOOP | Hollow tube-like structure with very low compression force | Lightweight, low-force shielding designs |
| Omnidirectional Conductive Foam Gasket | Full conductive foam | Fully metal-coated, conductive in X-Y-Z directions | High-performance shielding and grounding |
For a deeper breakdown of the wrapped structure, see Fabric Over Foam Gaskets: Why FOF Remains the Best Value EMI Solution.
Quick rule of thumb
- Solid core + wrapped fabric = FOF
- Solderable + silicone core = SMT
- Hollow + low force = AIR LOOP
- Fully plated + multi-directional conductivity = omnidirectional conductive foam gasket
2. Classification by Wrap Style
Within the FOF family, wrap style is another important layer of classification.
| Wrap Style | Structure | Advantage | Best For |
| Full wrap | Fabric covers the foam core completely | Conductive contact on all sides | General grounding, enclosure sealing |
| Half wrap (C-shape) | Fabric covers the top and both sides | Lower material usage, lower cost | One-sided conductive contact |
| Single-side wrap | Fabric covers only the top surface | Lowest material cost | Simple top-contact applications |
When the installation direction is fixed and only one surface needs to conduct, half wrap or single-side wrap can reduce material cost without affecting the overall design intent.
3. Classification by Conductive Plating
The conductive layer has a direct impact on conductivity, oxidation resistance, and cost.
| Plating Type | Appearance | Surface Resistance | Main Benefit |
| Nickel plating | Silver-gray | ≤0.05 Ω | Balanced performance and cost |
| Gold plating | Gold | ≤0.03 Ω | Strong oxidation resistance |
| Tin plating | Silver-gray | ≤0.05 Ω | Good solder compatibility |
| Carbon plating | Black | ≤0.05 Ω | Anti-oxidation and wear resistance |
If you are comparing plated options for EMI reliability, the choice is usually driven by environment, cost target, and long-term corrosion risk.
4. Classification by Cross-Section Shape
The cross-section determines how well the foam fits the available assembly space. This is where shape matters most.
| Cross-Section | Feature | Best Fit | Related Guide |
| Rectangular / square | Standard shape | General grounding | - |
| D-shape | Flat bottom + rounded top | Door frames, display bezels | Custom EMI Gasket Foam Guide: D, P, C & L Profiles |
| P-shape | Flat on one side, rounded on the other | Curved edges and bends | Same guide |
| C-shape | Semi-wrapped profile | Single-side conduction, cost-sensitive projects | Same guide |
| L-shape | Right-angle profile | Enclosure corners | Same guide |
| Knife shape | Thin and narrow profile | Tight gaps | Same guide |
| Loop shape | Hollow rectangular ring | Cable pass-through shielding | Same guide |
For compact devices that need a lightweight sealing design, an omnidirectional conductive foam gasket may be a stronger option than a standard wrapped profile. See Omnidirectional Conductive Foam Gasket vs. Standard Conductive Foam Gasket for a direct comparison.
5. Classification by Foam Core Material
The core material determines resilience, compression range, heat resistance, and cost.
| Core Material | Density Range | Main Advantage | Typical Application |
| PU foam | 18–50 kg/m³ | Soft, easy to form, low cost | General consumer electronics |
| PORON | Higher density | High precision and strong rebound | Premium consumer devices |
| Silicone foam | Customizable | Heat resistance and weather resistance | Automotive and outdoor equipment |
| CR (neoprene) | Customizable | Good flame resistance | Flame-retardant applications |
| EPDM | Customizable | Excellent weather resistance | Outdoor communication equipment |
6. A Complete View of Conductive Foam Gasket Categories
| Classification Dimension | Category 1 | Category 2 | Category 3 | Category 4 |
| Structure | FOF | SMT | AIR LOOP | Omnidirectional conductive foam gasket |
| Wrap style | Full wrap | Half wrap (C-shape) | Single-side wrap | - |
| Plating | Nickel | Gold | Tin | Carbon |
| Cross-section | Rectangular / D / P | C / L | Knife / loop | Trapezoid / custom |
| Core material | PU | PORON | Silicone foam | CR / EPDM |
7. How to Read a Part Number Quickly
Suppose you receive this part code: FOF-D-Ni-PU-5×3×2
Here is how to decode it:
- FOF = fabric over foam gasket structure
- D = D-shaped cross-section
- Ni = nickel plating
- PU = PU foam core
- 5×3×2 = width 5 mm × height 3 mm × length 2 mm
That means it is a D-shaped FOF conductive foam gasket with a nickel-coated fabric and PU core, suitable for general-purpose grounding in consumer electronics.
Another example: SMT-Au-Sili-4×4×3
- SMT = SMT gasket structure
- Au = gold plating
- Sili = silicone core
- 4×4×3 = 4 mm × 4 mm × 3 mm
That points to a gold-plated SMT gasket with a silicone core, which is often chosen for automotive or other high-reliability applications.
8. Fast FAQ
Q1: Is there a difference in shielding effectiveness between full-wrap and half-wrap foam?
A: Shielding effectiveness depends mainly on the conductive layer and compression ratio. Wrap style has less influence as long as contact is stable and well-compressed.
Q2: Is a C-shape foam the same as a half-wrap foam?
A: Yes. C-shape is the common name for half-wrap conductive foam.
Q3: What is fully sealed conductive foam?
A: It usually refers to a structure where the foam is fully wrapped and the seam is sealed for better dust and moisture resistance. The term is close to full-wrap, but it emphasizes environmental sealing.
Q4: What if my application does not fit these categories?
A: These categories cover most mainstream designs. If your geometry is unusual, a custom structure may be the better path.
About Konlida
Suzhou Konlida Precision Electronics Co., Ltd. was founded in 2006 and is one of the major manufacturers of conductive foam products. Our portfolio covers all five classification dimensions discussed in this article, from FOF and SMT to AIR LOOP and omnidirectional conductive foam gasket designs, from standard shapes to custom cross-sections, and from nickel plating to gold, tin, carbon, and more.
For engineers looking for a reliable conductive foam gasket supplier, Konlida provides one-stop selection support and custom development based on real application needs.
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