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solder balls on pcb

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#57085

solder balls on pcb | 23 October, 2008

We have 8 layer HASL PCB. We saw molten solder blobs / balls on op side of assembled PCB. (to check, if this was a bare board problem), We passed bare board as received thru, SMT reflow oven and saw solder balls on top side of board. What could be the reason and possible solution? Is this due to out gassing?

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CL

#57086

solder balls on pcb | 24 October, 2008

Good Morning WS,

If you experieced the solder balls after reflow of a bare board through the oven, then the source of the solder is either the oven or the board. I have had boards with untented via's that were HASL'd that had entrapped solder and flux into the via. When reflowed, the flux would outgas and eject a small amount of solder. We were able to see some of the solder residue in the via's.

Worth checking.

Good luck

C

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#57098

solder balls on pcb | 27 October, 2008

So you passed a BARE board thru the oven and got solder balls?

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#57099

solder balls on pcb | 27 October, 2008

Do you refer to the highlight in the picture as a solderball? Looks more like copper to me.

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#57135

solder balls on pcb | 30 October, 2008

solder ball was caused by hasl process not reflow. seen before many times, look around wells of smt on bare boards should be more of them

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#57173

solder balls on pcb | 4 November, 2008

I have to agree with Patrick here. This image appears to show a board that is NOT HASL as there is what appears to be a copper pad in the upper portion of the image. But then again the arrow tip appears to be white and I woudl expect that to be red so who knows.

If this is not HASL then it appears that there is some form of leaching of copper through the solder mask.

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3D SPI

Reflow Ovens thermal process improvement