One fly makes no summer. Is ONE solder ball a problem? We see small solder balls frequently when the boards are inspected after wave or vapour soldering. It's because the process is not 100% perfect. Out of billions of solder particles, some singular escape and do not participate in the solder melting. The reasons for that is many. We don't see the phenomenon as a problem, because the 'free' solderballs use to vanish during the board cleaning. The jet pressure is so high, that they can't stick to the board.
/Inge 
 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Iven, Jowan
Sent: onsdag 28 oktober 2009 14:06
To: [log in to unmask]
Subject: Re: [TN] Birth of a Solderball

Hi Leland,

What about the location of the solderball?
Doesn't that give you enough information?

Where on the board was the solderball located?
Or did the problem occur somewere else but the board?


Jowan


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Leland Woodall
Sent: Wednesday, October 28, 2009 12:54 PM
To: [log in to unmask]
Subject: Birth of a Solderball

TechNetters,

Is there any possible way to determine the origin of a solder ball?
We've had a failure because of one, and we're trying to determine whether it came from our SMT or wave soldering process.

We use SAC305 at both, so using the SEM to determine alloy composition is not really helping.

The ball itself is spherical with no "tails" and quite shiny in appearance.

If we cross section the ball, will we see a difference in grain structure due to the differences in cool down rates?  Is there anything else we can use or do?

Thanks in advance for your help!

Leland

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