Electronic Component News   Ensuring Reliability: A New Method
for Measuring Pressure Distribution During Encapsulation Tue,
11/23/2010 - 5:45am  Thermo-mechanical stress from non-uniform
encapsulation pressures on flip chips, quad flat no leads,
sensors, and thin substrates can lead to hidden damage or to
long-term reliability problems. Until now, pressure differences
during molding were assumed to be negligible, despite the
presence of filler particles in the epoxy molding compound
(EMC). The Fraunhofer results show that substantial pressure
differences can occur, with potential damage to components and
substrates.  Conventional pressure sensors measure pressure at
only a single point, not simultaneously across the entire area.
They also require modifying the metal molding tool to bring out
their data without short-circuits. Present sensors also leave
markings on the device surface that can later interfere with
pick-and-place assembly, or with laser labeling.  Commercially
available sensor film placed withi