Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Solder Balls in Vias

ckd

#20192

Solder Balls in Vias | 4 June, 2002

Hi All - My question is how do solder balls form and stay in the vias? The assembly goes thru SMT top placement, reflow then thru hole components mounts on top side as well. The board is sent thru the wave solder process. Has anyone experienced this? Any ideas or comments would be greatly appreciated. I have gone thru the archives and found some related information but nothing specific to the solder balls in the via locations.

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Hussman69

#20193

Solder Balls in Vias | 4 June, 2002

If you have solder balls in vias on the "component side" it probably is your wave solder process. Most waves have an option that is designed to make sure your surface mount parts solder - but if turned up too high, can actually push solder up through via holes.

Without knowing much to do about your process, perhaps you can check before and after wave to verify.

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#20198

Solder Balls in Vias | 4 June, 2002

Another thing we see is solder balls (sometimes fines, sometimes larger stuff) in the vias after a misprint has been poorly cleaned, as in wiped down but not washed. They end up in the plated through holes too, but those get nicely cleaned up in the wave.

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ckd

#20199

Solder Balls in Vias | 4 June, 2002

I meant to include this in the original message. One, the solder balls are on the circuit side of PCB. Two, some of the vias on both top and bottom are closed and some are not. Is this a process problem with the board house(s)?

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Hussman69

#20204

Solder Balls in Vias | 4 June, 2002

Closed by solder mask? At any rate, still sounds like wave solder. Take a look before and after wave. That should tell ya.

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Plasma prior Conformal Coating