Dear Technetters,

We had two boards out of 25 with a nonwetting problem. After reflow there was no solder on the flashgolden pads. Instead all the solder had gone to the leads of the 0805 capacitor.

Our pcb producer comes with the following conclusion:

 	"Our Q-dept. just informed me that they did x-ray inspection of the 2  boards you sent us back recently. Apparently 	there have been components used which contain up to 20% lead. During reflow-soldering the tin-lead on those 	components will melt first and absorb all the solder paste even before the tin which is included in the solder paste 	will melt. A golden flashgold pad without any tin will be the result. The tin will accumulate on the components and 	create those solder-balls instead. 

	In a second test we did lead-free soldering  on the side which contains no components. The two PCBs showed excellent 	tin-wetting on this side. All pads – big and small ones – are nicely covered with tin. So basically we will reject 	any complaint - the boards are ok."


Does this make sense?

Regards,

Lon Weffers

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