Spray-On shielding materials lighter and cheaper than metal cans

September 17, 2012 // By Julien Happich
Chomerics Europe has introduced two innovative new coatings that provide shielding of semiconductor packages and other board and package level electronic components that require protection from electromagnetic interference (EMI).

Cho-shield 604 and Cho-shield 571 are highly conductive materials suited for high volume applications and are applied using precise spray equipment to coat the target surface. Cho-shield 604 is a one component sliver-filled polyurethane material that achieves shielding effectiveness in the region of 100 dB (10 to10,000 MHz) and 80 dB at higher frequencies (10 -18 GHz). Cho-shield 571 meanwhile is a two-component silver-filled epoxy with shielding performance that can reach in excess of 120 dB (10 to 10,000 MHz) and 100 dB (10 – 18 GHz). Maximum surface resistivity for both materials is 10 milliohms / square at one mil. Both materials are flexible and offer a high degree of environmental stability. This helps it achieve an especially strong bond with component surfaces. Wave solder temperatures in excess 262°C can be withstood by both materials, and they have a continuous upper operating temperature of +85°C.

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