Druid, At the moment, we are speaking of heterogeneous integration: assemble an IC, assemble a PIC separately, integrate both components together. Wouldn't the reflow process happen separately during the IC manufacturing, without interfering with the PIC part?
This issue, if it is one, doesn't sound to me like it would affect the PIC manufacturing until we speak of On-Board optics, which isn't for a few years ahead at this point in time...
We'll cross that bridge when we get there kinda problem...
GLTAL
AR.