Anisotropic conductive film for flip-chip interconnectionof a high I/O silicon based finger print sensor

Anisotropic conductive film (ACF)
has been used for flip chip interconnection of a
silicon based MEMS finger print sensor to a signal
processing ASIC. The assembled sensor device was
subjected to a short term high temperature profile
with peak temperature 260°C simulating subsequent
reflow soldering of the device, and to thermal
shock cycling from -40 to +85°C. The reliability of
interconnects during ageing was investigated by
monitoring changes in electrical resistance of single
interconnects and interconnect daisy chains. The
electrical resistance increased after exposure to the
high temperature soldering profile, but no failures
were observed even after 10 repetitions. Thermal
shock cycling showed an increase in electrical resistance
and no failures. A relatively large resistance
increase was found for some interconnection points.