Are you using a PCB with an ENIG finish aren't you...

Paul 

Paul Edwards
Surface Art Engineering

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Cong He
Sent: Thursday, December 04, 2008 6:09 PM
To: [log in to unmask]
Subject: [TN] BGA soldering open issue

dear all:

I am facing a problem of bga soldering.

when the board have just soldered ,it pass all test.
But after sometime, maybe for a few weeks,
some of the bga balls opened. the function became normal if i press the
chip on the top side.

It seems that the pcb didn't warp much,it seems even no warp at all.
Does any of you know why? And how to improve?






Hechong

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