Failure Analysis:
A post-mortem examination of failed devices for the purpose of verifying the reported failure and identifying the mode or mechanism of failure. Failure analysis techniques may range from simple electrical and/or visual examination to some of the more advanced techniques of physics, metallurgy, and chemistry.

Failure rate:
The calculated rate at which device failures will occur within a total device population.

Fault isolation diagnostics:
A feature (normally associated with built-in test) that allows identification of a malfunctioning subcircuit or circuits within a complex device.

FET
The field-effect transistor (FET) is a type of transistor that relies on an electric field to control the shape and hence the conductivity of a channel of one type of charge carrier in a semiconductor material. FETs are sometimes called unipolar transistors to contrast their single-carrier-type operation with the dual-carrier-type operation of bipolar (junction) transistors (BJT).

FIB
Focused Ion Beam (FIB) technologies, testing and failure analysis of microelectronic devices,

Flat package:
A thin package with ribbon leads coming out opposite sides of the package.

Foreign material:
Any material that is foreign to a microcircuit or any non-foreign material that is displaced from its original or intended position within a microcircuit package.

Front end:
A slang term often applied to the wafer fabrication portion of the semiconductor manufacturing process.