Model: Georgia SFM3.
Part Number: 3HE03618AAAA.
Serial Number: NS092362953.
No Defect Reported.
Objective of this analysis:
Explain the rootcause of damaged pads on SFM 3.
FA process verification:
During incoming inspection, no problems were found.
ICT verification process:
N/A. Our process do not requires it.FVS verification process:
The unit failed to initialize, has problems to boot, it shows fault at RAM 0 as following **ERROR: No DIMM in socket 0!**. As the unit has problems to initialize,the test was aborted, so there is not a log fail at Helios.
At Debug Bench was done a visual inspection and was not found any damage, after, was done achecking on P10 connector, as impedance and continuity, was found some impedances higher than nominal, we tried by pressing down the U144 and the impedance decreases, so U144 was asked for to replace,after component lifting, was found missing pads, was talked with process BGA Plant 1 people and they told us that the card has not evidence of pads while the component was removed and there is not anyevidence of this on U144, but is possible that pads were mixed or lost while it was removed, this card was sent to NER due to damaged pads.
Zoom scope on Damaged Pads.
On U144 couldnot be found presence from pads, after remove.
We have received previous SFM 3 cards, two of them had *Black Pads* on U144, at corners, and both of them reported RAM defectissues, one defect caused for hyper corrosion on pads, is the wire pad broking or a neck wire pad broke on a hyper corroded pad or *black pad*, that is why, while the component was removed, it has notevidence of pad, and because I suspect that the pads are mixed with solder on BGA, but process people did not found presence of this.
There is an important issue of *Black Pad* on U144, that is...