type b, mil-dtl-83528, silicone emi gasketing
Customers ask me for material selection recommendations all the time. One way I believe I build trust with clients is, I don’t upsell things I don’t need to. Customers literally once a week call and say, I NEED VITON! Oftentimes my response is “Hey, I’ll sell you Viton, but I don’t want to sell you something you don’t need.”
The reason I bring this up, I see pure silver gaskets on prints from time to time. I have to believe to myself that these pure silver gaskets were a result of over engineering. Although, it’s possible I could be wrong about this… however, that’s not likely, ha. The reason I often think this when I see pure silver gaskets is because of a few reasons.
Our Reasoning to Reconsider Pure Silver EMI Gaskets:
Reason 1, Cost:
There are more economically available gaskets that cost FAR, and AWAY less than pure silver. As of this writing pure silver silicone gaskets cost 10x that of their silver aluminum counterparts. If you think paying 10x the amount for slightly better performance is worth it, that’s surprises me, but hey.
Reason 2, Requirements:
If we are going strictly by the MIL-DTL-83528, the requirements for the MIL-DTL-83528 Type F is 110 dB of shielding at 10 GHz, or 10000 MHz. You may, or may not know this, but we used to manufacture these gaskets 4 years ago. We had to send these gaskets out for official testing. Our Type D, which is fluorosilicone silver aluminum gaskets tested above this requirement of 110 dB at 1 through 10 GHz. In fact, during the testing the worst attenuation was 114.1 dB. The point is, Pure Silver tests close, if not equivalent to Silver/Aluminum or a low cost alternative in most EMI testing.
Reason 3, Margin of Error:
As mentioned above, when we tested our material years ago, our silver aluminum tested above the requirements of what pure silver gaskets should test at. Using that example, those gaskets perform at the 110 dB requirement, you’d have to assume that pure silver would test the same, and pass. Any good engineer would make sure it passes by a large margin, not a few dBs.
Which MIL-DTL-83528 Types are Pure Silver EMI Gaskets?
Type J- Low Durometer Pure Silver EMI/RFI Gasket
Type E- Pure Silver Filler, in Silicone Rubber gasketing material – EMI/RFI Gasket
Type F- Pure Silver Filler, in Fluorosilicone Rubber Gasketing Material – EMI/RFI Gasket
Type H- High Durometer, Pure Silver EMI/RFI Gasket
Radio frequency spectrum during electromagnetic compatibility emissions scan
Radio frequency spectrum during electromagnetic compatibility emissions scan
Pure Silver EMI/RFI Gaskets Alternatives
MIL-DTL-83528 Type E Pure Silver Silicone, Alternative: MIL-DTL-83528 Type B Silver Aluminum Silicone
MIL-DTL-83528 Type F Pure Silver Fluorosilicone, Alternative: MIL-DTL-83528 Type D Silver Aluminum Fluorosilicone
An Even Lower Cost Alternative: Nickel Graphite Gaskets:
Data has shown that Nickel Graphite Gaskets often provide just as good of shielding performance as its silver aluminum counterparts.
More Information:
For more information on materials, or pure silver EMI/RFI gaskets, please contact sales@nedc.com. NEDC die-cuts, waterjet-cuts gaskets for aerospace, military customers. In addition, we add 3M adhesive tapes to these gasketing materials.