Diode Failure Analysis

A diode allows current to flow in one direction and blocks it in the other. Diodes are used for rectification, signal switching, voltage clamping and protection. The main types are signal, rectifier, Schottky, Zener and light-emitting diodes (LEDs).

Diodes fail in a few common ways. Electrical overstress (EOS) can melt metal or damage the junction. Mechanical stress can crack the die or the glass body, which causes an open circuit, an intermittent connection or a leakage path. Moisture or contamination can raise leakage current, and a poor solder or die-attach bond can open the circuit at high temperature.

The case studies in this category include a glass-sealed diode in a display socket that cracked from lead stress. Others include a signal diode with EOS damage to its epoxy body and silicon rectifier diodes that opened at high temperature.

The lab usually begins with curve tracing to find the electrical failure mode. We then decapsulate or open the part and inspect the die with optical microscopy. Scanning electron microscopy and X-ray radiography help when more detail is needed.

If you have failed diodes, request a quote and send us a description of the failure.