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Here at Modus Advanced, we truly enjoy getting involved with our customers early in the design phase for their projects. It gives us the opportunity to build trust and to iterate on design with our customers to ensure their part is crafted with speed and precision – the Modus way.
This article will provide insight into the world of conductive fabric gaskets, which are referred to in the industry as fabric-over-foam gaskets. We'll cover when and where to use them, and a few critical considerations in selecting them as your gasket of choice.
Let’s get to it.
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Everything you've ever wanted to know about EMI gasket design
What is a Conductive Fabric Gasket?
A conductive fabric gasket, more commonly referred to as a fabric-over-foam gasket, is almost as straightforward as it sounds: it’s a type of gasket that is made of conductive material, either a fabric or a foam, that has been coated or infused with conductive materials such as metal particles or carbon.
This type of gasket is designed to provide electrical conductivity between two surfaces, typically in electronic devices or equipment where electromagnetic interference (EMI) needs to be minimized. The need for this type of gasket extends across many different applications – everything from aerospace and defense to medical devices and space.
An effective conductive fabric gasket works by creating a conductive path between two mating surfaces. This seal reduces the EMI that can occur between the two surfaces, and restricts ingress and egress of EMI. The gasket is used to provide a seal that is both conductive and flexible.
These types of gaskets are most commonly used in applications that require shielding against radio frequency interference (RFI) and electromagnetic interference (EMI) and are ubiquitous in industries such as the aerospace and defense, medical device, and emerging technology categories where electromagnetic shielding is critical.
Conductive Fabric Gaskets vs. Fabric-Over-Foam Gaskets
Chances are that you landed here via a Google search using the terms "conductive fabric gasket". We're certain you've found what you're looking for, but it's worth noting that while Google brought you here, there is a different term used within the industry for these types of gaskets – fabric-over-foam gaskets.
They are indeed the same thing, but the technical term provides a better understanding of the outward physical properties of the gasket.
Conductive Elastomers vs. Conductive Fabric Gaskets
Conductive elastomers and conductive fabric gaskets/fabric-over-foam gaskets are two types of custom gaskets used to provide EMI/RFI shielding between mating surfaces in electronic devices. While they’re both intended to do similar things, there are a few key differences between them that can impact your decision-making.
Conductive elastomers are made from silicone rubber or other elastomeric materials that have conductive particles distributed throughout the material. Silver or nickel are among the most commonly used conductive materials.
These elastomers are effectively flexible and can be molded into many different shapes and sizes to fit the needs of your particular device. They’re ideal for applications where a custom fit is needed. Conductive elastomers are also highly effective at providing EMI/RFI shielding and can withstand a wide range of temperatures and environmental conditions that are present in many industries such as defense and aerospace.
Alternatively, conductive fabric gaskets are made from fabric that has been coated with or had conductive particles distributed throughout it which is placed over a conductive foam core. These gaskets are typically more compressible than their conductive elastomer counterpart, which makes them ideal for applications that require a high degree of flexibility.
Conductive fabric gaskets are also effective at providing EMI/RFI shielding and are often used in applications where weight and space constraints are critical (perhaps in… space applications).
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Making the Choice
Your specific application will dictate the requirements needed for your conductive gasket, but that doesn’t mean it will always be an obvious choice. Here are some factors to consider when deciding between the two:
- Compression Requirements: Conductive elastomer gaskets are better suited for environments that require higher degree of compression for longer periods of time. They’re also a better choice for sealing surfaces that are uneven or rough. Conductive fabric gaskets, on the other hand, are more compressible and can conform better to surfaces with less compression force.
- Space and Weight Constraints: If space and weight are a concern, when you’re heading to space for example, the conductive fabric gaskets are thinner and lighter making them a better choice.
- Environmental Factors: Conductive elastomer gaskets are typically more forgiving (and effective) when it comes to extreme temperatures, moisture, and other environmental factors.
- Shielding Performance: While both types of gaskets offer EMI/RFI shielding, the shielding performance can be affected by the composition of the conductive materials used in the gasket. In general, conductive elastomer gaskets offer better shielding effectiveness in lower frequency ranges, while conductive fabric gaskets are more effective in higher frequency ranges.
- Customization: Conductive elastomer gaskets are easily customizable, while fabric-over-foam gaskets are typically available in standard sizes and shapes (which is great for rapid production).
The choice between the two really comes down to the specific requirements of the application. Working with a trusted manufacturing partner such as Modus can significantly alleviate any headaches associated with analysis paralysis in the design phase.
Advantages and Limitations of Conductive Fabric Gaskets
Conductive fabric gaskets may not be the right choice for every application, but there are several reasons to consider them when you are iterating through the decision-making process;
- Flexibility: Conductive fabric gaskets are incredibly flexible, allowing them to conform to irregular surfaces, absorb vibrations, and provide a tight seal even under compression. They may be a good fit for complex geometries as well.
- EMI shielding performance: The flexibility offered by conductive fabric gaskets allows it to provide a better seal against EMI/RFI in certain applications compared to other gasket materials.
- Better thermal management properties in high-temperature environments: Conductive fabric gaskets can dissipate heat more efficiently, providing better thermal management in high-temperature environments.
This all sounds promising however, there are some limitations of conductive fabric gaskets which may render them inappropriate for your project:
- Lower compression set and resilience compared to conductive elastomers: This means that over time, the gasket may lose its ability to compress and seal properly, leading to leaks and reduced performance.
- Limited chemical resistance: They may degrade or break down when exposed to certain chemicals, leading to reduced performance and shorter lifespan.
- Less suitable for applications that require high-force compression or high-frequency EMI shielding: While they are highly flexible and can conform to irregular surfaces, they may not provide sufficient compression force for applications that require a tight seal or high-frequency EMI/RFI shielding.
Choosing the Right Conductive Fabric Gasket for Your Application
We’ve covered what conductive fabric gaskets/fabric-over-foam gaskets are, how they work, and their applications. Depending on your application and requirements, this type of gasket may be the answer to your prayers.
If you’re still unsure of where to go next, reach out to the expert engineering team at Modus Advanced. We’re ready to partner with you in bringing your life-changing and life-saving projects to life.
