Design

Many sources recently have reported that electrical failures to components previously classified as EOS (Electrical Overstress) are instead the result of ESD (Electrostatic Discharge) failures due to charged-board events (CBE) [1,2]. A charged printed circuit board assembly stores substantially more charge than a discrete device as its capacitance is larger. A subsequent discharge of the board assembly results in increased current for that event - versus that of the discrete component. Consequently, a device’s CDM (charged device model) rating is lowered when mounted in a printed circuit board (PCB). In an attempt to get a feel for just how much it is lowered, we conducted CDM stress tests on components in discrete form, and again after insertion into larger and larger sized pc boards. We found that the CDM ratings are lowered dramatically!

Asurion of Smyrna, TN has recalled about 470,000 counterfeit Blackberry-brand cell phone batteries, distributed in refurbished Blackberry-branded devices.

Each year the IEEE Electromagnetic Compatibility Society sponsors a Best Student Paper competition as part of the IEEE International Symposium on EMC.  The contest is administered by the Educational and Student Activities Committee (ESAC) of the Society.  For the 2010 Symposium 33 student papers were submitted, the largest number in recent memory.  An ESAC panel reviewed and ranked the submissions based on technical contribution, accuracy, and clarity.  It always proves to be a challenge to select a single winner from the many fine papers covering many diverse aspects of EMC that are received.  The paper selected for 2010 use modal decomposition to derive a transmission line model for printed circuit board vias that can be implemented in circuit simulators.  The new model has a significantly faster computation time than that of a full-wave simulator while giving results that are in good agreement.  The practical benefit is an improved facility for of the design and optimization of high speed digital circuit boards for both signal integrity and EMC compliance.

EMI shielding is a critical component of many electronics-based medical devices, which are in turn integral for life-saving procedures and ongoing patient health care. Medical devices are frequently used in the vicinity of other electronic instruments, resulting in an increased risk of electromagnetic interference (EMI). This risk can be mitigated through the use and care of EMI shielding gaskets. For more than a decade the FDA has also expressed concerns for public health and safety in regards to device EMI and the solutions for these concerns.

There has been much to do about the sudden unexpected acceleration EMI connection. There is no shortage of opinions on this subject. We’ve heard from manufacturers and their EMI consultants as well as from many recognized industrial and academic EMI experts. Most manufacturers have been very supportive of each other but have been very careful not to utter direct EMI related statements as they would rather not be seen in the spotlight of any investigations aimed in their direction. I guess they think that the EMI gods have decided to target just one automobile manufacturer.

The Method of Moments has become one of the most powerful tools in the RF engineer’s arsenal. In this chapter, we make the transition from theory to practice, first by attempting to compute the characteristics of a “short dipole” by hand, and then by demonstrating that a computer can do that in just a few seconds.

In the past EMC Engineers have relied on metallic enclosures to contain electromagnetic fields and meet radiated emissions limits in military and consumer products. Modern commercial electronics products typically use molded plastic enclosures since they are considered to be aesthetically more pleasing than a metal enclosure, but also to save weight and cost.