V. Koeninger et al., DEGRADATION OF GOLD-ALUMINUM BALL BONDS BY AGING AND CONTAMINATION, IEEE transactions on components, packaging, and manufacturing technology. Part A, 18(4), 1995, pp. 835-841
The degradation of gold aluminium ball bonds has been studied by shear
tests, resistivity measurements, micrographs, EDX and AES as a functi
on of aging time at elevated temperatures and after various contaminat
ion treatments before and after bonding, Samples were subjected to ion
etching treatment immediately before bonding in order to guarantee a
comparable initial state. Incorporation of large amounts of Cl, Br, an
d F into the surface layer of the pad and other contamination treatmen
ts before bonding did not show detectable effects in subsequent anneal
ing treatments as long as the bonding process itself has not been impe
ded by thick surface layers, The degradation process during annealing
can be described as a three stage mechanism, Each stage can be clearly
distinguished by the fracture behavior in the shear test, the morphol
ogy of the bond shown by the micrographs and by the change of contact
resistivity.