It must be a bit unusual. I have not see it. 
One of the guys here has. He prevented it by prebaking the board. 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Chris Mahanna
Sent: Wednesday, August 26, 2009 9:34 PM
To: [log in to unmask]
Subject: [TN] Via-in-pad blowing bubbles

Hello netters-

Have we a term for vias-in-pad blowing solder ball bubbles to the point of
bridging?
Regardless, is there a unique cure for the problem?
I wonder because- how does one get just enough pressure to blow the large
bubble, but not blow-out?   Bad luck?
Or is it not that unusual, and just usually gets screened before it gets to
me?

Chris


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