Electronic Design

Board-Level Shielding Solution Solves Wireless EMI Problems

Designing RF products is hard enough, but nothing is more difficult than ferreting out RF leakage and interference in a new design. Once you figure out the problem, you invariably need a custom metal shield between one or more parts of the product. This typically leads to an ugly soldered metal can that's difficult and expensive to make and even messier to install.

To solve the problem, W.L. Gore & Associates unveiled its snapSHOT board-level multicavity shielding product. The lightweight, metallized plastic material, made as a snap-on shield, provides high-end protection against electromagnetic interference (EMI). It's designed for cell phones and other wireless products like PDAs, PCMCIA cards, wireless local-area network (802.11a/b/g) cards, Bluetooth-enabled products, and laptops.

The metallized plastic material can be thermoformed to virtually any shape. It is 0.125 mm thick and the outside metallized tin layer is only 5 mm, yet it provides a 75-dB shielding effectiveness in close quarters. This effectiveness is at least 20 to 30 dB better than more conventional perforated metal cans. The shield is so thin, it also accommodates narrower ground traces and reduced space between components. One neat advantage is that the shield is easily removed and reinstalled by hand.

The shield attaches to the pc-board via a patented mechanism that uses individual solder spheres as snap attachments. The solder balls are formed during the surface-mount reflow process around the periphery of the area to be shielded. The shield then simply snaps into place with the appropriate tool. DEK (www.dek.com), a maker of high-accuracy mass imaging equipment and process support of the electronics assembly industry, makes the equipment for forming the solder balls.

W.L. Gore

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