PQFP Heat Damage - Application Note 1148
Sample & Method
In order to simulate the higher temperatures of lead-free processing, this PQFP was first imaged acoustically, next subjected to high temperatures, and then imaged acoustically again. The purpose of this early experiment was to learn what effects the higher temperatures might have on conventional components. Reflow temperatures where leaded solder is used typically peak at 225o C. For lead-free solders the peak temperature could be as high as 260o C.
Imaging in both instances was performed at 30 MHz. In this component there are no delaminations along the lead fingers (a defect one might expect from higher temperatures), but the die has been completely disbonded (red) from the molding compound. More information is available from Sonoscan's Lead-Free Team.