Looking for help with solder moving from pad-to-pad during reflow.

I have an low noise amp. (LNA) in what looks like an SOIC-8 with a
continuous ground pad on the bottom of the package.  For RF reasons this
bottom plad must be soldered to a ground pad which has several vias to an
internal ground plane.  My problem is that after reflow, I end up with one
of the eight leads with excessive solder and one with insufficient solder.
I suspect that this solder movement is partially due to the thermal effect
of the ground pad along with the .015" spacing between the ground pad and
lead pads causing solder to be robbed to and from the ground pad.  I've
tried playing with the oven profile but can see no difference.

The RF designers will not give me more than this .015" spacing between the
heel end of the lead pad and the dreaded ground pad, so I plan on widening
the separation of the solder deposits on my stencil to prevent slumping and
bridging of the solder mounds prior to reflow.

 Any other ideas on what may be causing this solder swap or what I might do
to minimize the problem?

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