Part Number: AFE7903
We've been succesfully using the AFE7903IABJ in a socket since we started the project. We just spun and assembled our first two boards that solder the part on. Both boards have failed in a very pecuiliar way. 1.2V and 1.8V are shorted on the part itself.
The balls underneath all look just fine--there are no bridges here.
We removed one of the AFE7903's and probed its 1.2V and GND pins and found a 50mOhm resistance between them. 1.8V and GND also have similarly low impedance.
But most surprising, there is what looks like a solderball that appeared underneath the heat spreader. There's nothing in our process (entirely SMT) that would account for solder appearing on both boards (assembled on different days) in the same location. See attached images for chip1 (removed from board) and chip2 (still on board). They both have the same blob(?) of solder(?) in the same location. I did not photograph these parts before placing them, but none of the rest in our lot have this defect before soldering.
We followed the Loctite GC10 reflow curve #2:
The following are "chip1" (taken off PCB):
The following are taken from "chip 2" still on the PCB:
Please advise on next steps. Burning these rather expensive chips is getting painful.
