Prolong wire bonding exceeding the recommended lifespan of 500k “touch down” will cause heavy (massive) metallization build –up (as shown). Under normal wire bonding process, the capillary start to gather excessive contamination after over 300K bond (refer pg.5)
After properly cleaning and removing metallization there appears a cratering ring mark. Such recess mark will cause loss in bond strength and inconsistent Free Air Ball (FAB) formation. Other typical characteristically problem arises are: appears a cratering ring mark.