Following from the EMPF HelpLine in Indianapolis, prepared by Hamid Farsad:

An inert atmosphere will be helpful if you are planning to use low-residue 
(no-clean) fluxes.  I personally prefer the full tunnel simply because most 
of the oxidation takes place in the pre-heat section.  An inert atmosphere 
will reduce the rate of re-oxiadation.  But one may want to consider the 
cost vs benefits of a full tunnel.  One consideration which is very 
important in using low-residue fluxes is the flux application method.  Flux 
should be applied in a controled manner.  I recommend the use of spray 
fluxer over any other flux application method. You can contact us directly 
if your wish further discussion at 317.226.5616 or [log in to unmask]
 ----------------------------------------------------------

SUBJECT: Wave Soldering Machine
DATE: 1995-12-15 17:27:48
FROM: [log in to unmask]@PMDF@MBIN01
TO: [log in to unmask]@PMDF@MBIN01

We are planning on replacing our wave soldering equipment in the very near
future.  We are also begining to specify PCBs with OSP instead of HASL
coating.  The equipment we purchase will probably have an inerting system.
 Our choices include full tunnel or contour inerting.

Would anyone with experience using an inerting solder wave line please
comment on the pros and cons of each type. Suggestions would be much
appreciated.

Thank You,
[log in to unmask]