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Failure Analysis | Electrical Testing| Non-Destructive Evaluation| Destructive Evaluation| Contact Us| - Destructive Evaluation - All plastic encapsulated microcircuits (PEM's) will absorb moisture because the epoxy molding compounds used in packaging are hygroscopic. During the solder reflow process, surface mount PEM's are exposed to temperatures of 210 to 260°C for periods of 30 seconds to 5 minutes. These high temperatures and rapid ramp rate will prevent the absorbed moisture from escaping. As the moisture begins to vaporize, the local pressure will increase rapidly, leading to delamination at the die/package interface and cracking of plastic packaging. This phenomenon is known as "popcorning". The extent of popcorning is influenced by package materials, package geometry, and assembly process parameters.
When the cracking and delamination during popcorning is not severe, electrical
characteristics of the PEM can remain stable for a period of time after the
manufacturing assembly process. Nevertheless, reliability risks are introduced,
since the plastic is free to move relative to the die surface during
temperature excursions and moisture can be trapped at the die surface,
creating conditions for accelerated corrosion. Studies have shown that
delamination at the die surface can reduce expected lifetime operation
by causing wire bond degradation, metallization shifting, passivation
cracks and corrosion
*Scanning Electron Microscopy (SEM) *Energy Dispersive Microscopy (EDS) Focused Ion Beam (FIB) Imaging *Scanning Magnetic Microscopy (SMM) Transmission Electron Microscopy (TEM) *Fourier Transform Infrared Spectroscopy (FTIR) *Contact Resistance Measurements Assessment of Popcorning in PEMs *These techniques are also performed during |
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