XC2V1500 / FPGA

1
Manufacturing problem on most recent FED
production Serial Nrs 006-011 all exhibited
shorts between power and ground. (N.b. There were
no BGA related problems observed on
001-005) X-Rays showed problems under largest
FPGAs On one FED all (9) large FPGAs were removed
and replaced with new parts. Initial idea of
cause is contamination of metal plating on pcb
(immersion tin). Causes solder on some pads to
migrate and form shorts between Gnd and Vcc
balls. Removing FPGAs and cleaning up cleared
shorts. Now performing Boundary Scan tests to
verify other digital connections.
XRAY image / BGA 676 pins 1 mm pitch
XC2V1500 / FPGA
Components ok
example of solder bridges potential shorts
between power and gnd pins
Note tracks between vias and caps are not visible