Ioan, the chances are that you don't care about trying to salvage the IC
at this point.  It sounds like you know which ball is the problem, but
since its not on an outside row you can't see it.

If you have access to a rotary tool such as a Dremel and a decent
10x-30x stereoscope, then just buy a cylindrical diamond burr from the
McMaster Carr company (www.mcmaster.com) and grind through the device
down to the suspect connection.  Use a little DI or distilled water to
lubricate the cut and remove debris.  You need some hand skills for this
job, but it's really pretty easy.  Just don't ding the board.

Wayne Thayer

>>> [log in to unmask] 6/16/2006 9:05 am >>>
Hi,

first it was the cracked capacitor question, thanks to all who
answered.

Now I have another one on the ethernal dilemma: is the BGA poorly
soldered or there is a design issue?

The question is: how can I assess whether the BGA that fails test is
properly soldered? I do not have a 5DX and whatever I can see with the
Ersascope looks OK. Needless to say, I cannot get the location of the
failed pin.

Will cross sectioning parallel to the surface of the board tell me
anything?
Can this be done? Any particularities regarding the polishing of the
surfaces?
What to look for?

Thanks,

Ioan

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