Hey Poh!

    Are you using wave solder pallets for wave soldering?  There may be
resiual solder balls, chips, etc. on the solder pallet or fingers when
the board is being waved.  Also, the operator (screen printer or wave
solder) could be passing solder to the board.  The solder could also be
splattering onto the fingers during reflow, if the profile ramp is too
steep.  That way, there is no solder on the fingers after printing, but
it splatters there as the paste flux/binder is driven off.

Ryan Jennens

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