Zener Diode Failure in a Clipper Application

February 6, 2012 | Leave a Comment

This is an application where two Zener diodes were placed in series, in a back to back configuration. They were placed across the primary winding of a transformer used to apply modulation to an AM transmitter. The modulation was in the form of a single frequency, and the modulation level was not to exceed 30% [...]

Sep

7

The Case of the Malnourished Zener Diode

September 7, 2011 | Leave a Comment

Zener diodes are among the most misunderstood and misused parts in electronic systems. How can this be? You might ask. The diode only has two connections, run some current through it, and it simply clamps to a specific voltage. Couldn’t be easier. End of story. Maybe. This is the tale of a 50 mHz. low [...]

Aug

5

Printed Circuit Boards and Reliability

August 5, 2011 | Leave a Comment

Potting compounds are often used on printed circuit boards to improve reliability. In spite of this added protection, adhesive failures, otherwise known as delamination, can occur and lead to substantial problems from moisture ingress. Root causes of adhesive failures may be surface contaminants, inherently weak bonding between solder mask and potting material or thermal stresses [...]