The presence of a copper oxide layer on the leadframe of plasticIC packages was found to cause delamination at the diepad/mold compoundinterface. The failure mechanism seems to be the presence of voids atthe oxide/metal interface, which increased as the degree of oxidationwas increased. Elevated temperature processes used in assembly such asdie attach curing and wire bonding were found to be the primary causesof oxidation. However, an important observation was made in that theduration of post mold curing was also found to have a great impact onthe interfacial integrity of the oxidized interface within anencapsulated package. Depending on the degree of oxidation and theduration of post mold curing, the susceptibility of the packagedelamination during solder reflow was found to shift from diepad/compound interface to die attach region. This paper also describes anovel method of characterising oxidation using SIMS (Secondary Ion MassSpectroscopy) depth profiling. SEM (Scanning Electron Microscopy) andXPS (X-ray Photoelectron Spectroscopy) was used to characterise oxidemorphology and oxide composition change on the samples. In parallel, theadhesion strength of the oxidized copper leadframe to a mold compoundwas characterised using an adhesion test. These data were correlated tothe degree of package delamination on a QFP package using C-modeScanning Acoustic Microscopy. This work shows that it is important tocontrol the oxide thickness on the copper leadframe die pad for improvedpackage integrity, especially when larger die pad sizes are considered
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