hollow strip soft pressure enclosure
At NEDC, we mostly die-cut, knife-cut, or waterjet cut gaskets. However, we do also fabricate, glue, or bond together some gaskets. Why do we do this? The short answer is because we cannot die cut, or waterjet cut them. However, sometimes it’s also for performance reasons.
The Softest EMI/RFI Gasket There Is:
The Softest EMI Gasket out there is not actually soft necessarily in the material itself, but it is soft because of its composition. What is it? It is the Bulb or the Hollow O-Ring
The Bulb or Hollow O-Ring for EMI/RFI Shielding:
When designing a gasket for the maximum compression with little ability to compress that gasket, I always start with the 30A, 40A, 50A EMI Gaskets, then quickly work our way into the foams, and sponges, and then if those are still too hard, or perhaps alternatively not providing the strength, stability, or EMI performance required, I fall back to the notorious EMI/RFI Gasketing Bulb, or Hollow O-Ring.
How Are EMI/RFI Bulb/Hollow Gaskets Made?
These type gaskets are manufactured by an extrusion machine, or an extruder. These extruders push material out like play-doo. Afterwards, these gasketing materials are bonded, or glued together to make a complete gasket.
Why the Bulb/Hollow for EMI?
The Bulb allows the user to get an extruded profile of any material they want:
-Silver Copper Silicone, MIL-DTL-83528 Type A
-Pure Silver Silicone/Fluorosilicone
-Silver Aluminum Silicone/Fluorosilicone MIL-DTL-83528 Type B, and Type D
-Nickel Graphite Silicone/Fluorosilicone
-Nickel Aluminum Silicone/Fluorosilicone
But instead of just settling at the standard MAXIMUM 20% compression that is typical of EMI/RFI flat gaskets, they can now ultra compress the Hollow Profile to allow for maximum EMI performance, but also great environmental performance.
electronic low pressure enclosure
Alternatives to EMI Gasketing to Bulb/Hollow EMI Gaskets
When your thinking about alternatives to bulb, or hollow gasketing, finding alternatives can start to become fairly difficult. However, there is one last option. These materials are called “Fabric Over Foam” EMI Gasketing. The way these materials work is the fabric is an electrically conductive fabric, while the foam is a normal urethane foam. Similiar to bulb materials, these materials are available in a number of different configurations.
More Information on Bulb/Hollow Gaskets
NEDC manufactures gaskets of all shapes, and sizes for its customers. Most EMI/RFI gaskets that are bonded together are bonded together due to size limitations, or rarely, but sometimes cost. For more information on EMI/RFI gasketing, please contact sales@nedc.com.