Electrical Overstress in Manufacturing and Test

Electrical overstress (EOS) is a major cause of device failure in manufacturing and in the field. Despite this, there is relatively little information on the sources of EOS and on prevention practices, particularly for the factory.

In this tutorial, the fundamentals of device overstress are reviewed. Relationships among device EOS stressing models, such as the Wunsch-Bell curve, are discussed. The causes of EOS and EOS-like events in manufacturing are described and categorized by source and by stress-type. The difficulties in distinguishing between power-induced EOS and high current ESD events such as charged-board events (CBE) and cable discharge events (CDE) are discussed. Case histories, including failure analysis and root cause determination, are presented and the few relevant industry specifications are reviewed.