EMI shielding specialist Chomerics has launched two innovative coating materials for shielding semiconductor packages and other board-level electronic components that require protection from electromagnetic interference. Cho-Shield 571 and Cho-Shield 604 are highly conductive materials suited for high volume applications and designed to be applied by precise spray equipment to coat target surfaces. According to the manufacturer, they are lighter and cheaper than sheet-metal shielding.
Cho-Shield 571 is a two-component silver-filled epoxy material offering shielding performance of 120 dB or more in the 10 to 10,000 MHz region and 100 dB from 10 to 18 GHz), while Cho-Shield 604 is a one-component sliver-filled polyurethane material with a shielding rating of 100 dB for frequencies from 10 to10,000 MHz and 80 dB at higher frequencies (10 to18 GHz). The maximum surface resistivity of both materials is 10 milliohms/square at one mil thickness.
Both materials are flexible and have high environmental stability, which enhances their ability to bond well to component surfaces, and both can withstand wave soldering temperatures up to 262 °C. The rated maximum continuous operating temperature is +85 °C.