Jeffery,

We have seen a few wicking problems over the years.  A few of the problems
were a result of plating problems on the PCB.  I would not suspect this
to be you problem.  
Years back when we used IR reflow ovens, we had many more wicking problems,
the first thing you might want to do is investigate the pads in which solder
is being wicked away from.  Are these pads tied to ground planes?  If there
is an obvious correlation in which only those pads tied into a dense ground
plane are wicking, then the board is not being sufficiently soaked.
If this is a fairly dense board, and you are bringing it up to 220C and are
only above reflow for 60-70 seconds, then I would think that the board is not
soaking in enough heat- the delta across the board could be huge!

On dense board profiles made when we had a Vitronics 722 oven, we usually could
only achieve 212C and had a hard time keeping reflow above liquidous times 
under 2 minutes.  We tried to meet recommended time and temperature parameters
as much as possible, but used 5 thermocouples when profiling, and paid special
attention to reduce the varience across the board.

The best long term solution is to get a convection oven.
                                                            Steve A

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