Failure Analysis of Transistors

A transistor is a semiconductor device that works as a switch or an amplifier in a circuit. There are two main bipolar types, NPN and PNP. Field-effect transistors (FETs and MOSFETs) and insulated-gate bipolar transistors (IGBTs) are also widely used in power circuits.

Transistors usually fail by electrical overstress (EOS), which can leave the terminals shorted or the junction open. Other causes include electrostatic discharge (ESD), overheating, moisture entering through a defect in the passivation layer, contamination, and mechanical damage to the die or the package. The result is often a short, an open, or a leakage current that is too high.

The case studies in this category include power MOSFETs with all terminals shorted and an IGBT that could not hold its rated voltage because of a passivation defect. Others cover a JFET and optocouplers.

The lab starts with electrical tests and curve tracing to find the failure mode. We then decapsulate the part and inspect the die with optical microscopy. Scanning electron microscopy and X-ray radiography give more detail when needed.

If you have failed transistors, request a quote.