DO leave adequate space on your PCB for EMI suppression devices. With good EMI design practices, your circuit board may be very quiet. But to be on the safe side, leave extra space on the board for the addition of filters and chokes. It is also a good idea to add extra pads to the board in case a shunt capacitor is needed here or there.
DO NOT assume that "second sourced" parts will have the same spectral characteristics as the original. This is especially important for active components such as DC-DC converters. The fit, form, and function may be the same, but the EMI noise could be significant. Before investing in a large stock of these extra parts, plug one into your design and take it for a test drive.
DO use ground and power planes when designing printed circuit boards. And where possible, use multiple ground planes. Not only are they useful in containing high frequency traces, they also help reduce the loop areas of signal and power traces, which are a major contributor of EMI emissions. In general, when it comes to ground traces, the more copper the better.
DO use wiring harnesses and wire ties when routing cables inside a box. EMI pickup on I/O cables is a major contributor to overall radiated noise. Route cables along the sides of the box and away from high frequency components and switching power supplies.
DO NOT have painted seams on a chassis or box. This is especially important if one of your EMI strategies is containment. Rivets and screws often do not provide adequate electrical conductance between chassis parts. Have the mating pieces masked before painting or powder coating. For added suppression, have each mating piece meet with a flange.
This information has been provided to DfR Solutions by the EMC engineering staff of MET Laboratories. For more information about MET Laboratories EMC testing services visit: http://www.metlabs.com/pages/emc.html
DfR represents that a reasonable effort has been made to ensure the accuracy and reliability of the information within this report. However, DfR Solutions makes no warranty, both express and implied, concerning the content of this report, including, but not limited to the existence of any latent or patent defects, merchantability, and/or fitness for a particular use. DfR will not be liable for loss of use, revenue, profit, or any special, incidental, or consequential damages arising out of, connected with, or resulting from, the information presented within this report.
Plastic encapsulated microcircuits with aluminum triple track structures were exposed to mixed flowing gas conditions to simulate and accelerate possible environments during long-term storage. No increase in resistance was measured and no corrosion products were observed after 800 h of accelerated exposure. Further experimentation indicated that chloride gas reacts with surface moisture in microscale and macroscale voids within the encapsulant, creating chloride ions.
Society has been enamored with wearable electronics for many years. From the futuristic suits in Tron to the recent use of Google Glass, taking electronic technology to this next level has fascinated us. Wiki defines wearable computers, also known as body-borne computers or wearables, as miniature electronic devices that are worn by the bearer under, with or on top of clothing. This class of wearable technology has been developed for general or special purpose information technologies and media development.