What are the other uses of N2 in building?
Flux, solder combinations?

I ran mostly lead free with a VOC flux pushing the limits of process.
My selective ran 5 times faster than manufacturers recommendation with
automotive electronics yields.
Also ran an alcohol flux for lead free and lead solder.
Lead is easy in comparison.

Used 3 large generators supporting oven, waves and selective. Maxed out
capacity.
Had 3 large compressors supporting generators.

Items to watch out for:
Generators swap volume/pressure for purity.

They take time to come up to purity levels. Maintenance saved money by
turning them off for the weekend. Lost over 1/2 a shift waiting for the
system to come up to speed.

My selective solder machines used the N2 for the compressed air supply. It
saved money in piping but meant the N2 had to run at over 90psi.
The machines would error out due to how close we ran to capacity. Re-piped
internal controls of machine to use compressed air for controls and lower
the N2 psi.
This common gas arrangement had worked in the factories that used LN2 as
the source.

Purity matters. I used the 2nd best gas purity. Manufactured called for
best.
When a generator was stretched purity and process yields fell at selective.
Changed Hula Skirts on reflow ovens to reduce the openings, which helped
conserve gas.
Chewed on Facilities Engineer who kept trying to reduce purity to save
electricity.
Those compressors used a lot of juice.
He was just doing his job but I would find out about it due to the charts
showing yield drops.

LN2 has its own problems.
The outside tank has to be kept filled.
If you are in the boonies it takes a while to get a tanker load.
Purchasing changed suppliers and the new one required more notification.
I was using over a truck a week due to the shared use of 140 environmental
chambers running 7x24.
Saw it happen in other locations where changes in production rates took
place without watching usage.
Autodelivery is based on past consumption.

Dewers located near the equipment need heat exchangers to keep system from
freezing up.

The N2 blanket design varies greatly by manufacturer.
There are wetted and unwetted nozzles.
Unwetted nozzles can get in tighter spaces and do not require re-tinning.
Wetted are less touchy when working.
Everything is co-dependant for your system, process and product.


Check calibration of the ppm monitors.
There are ways they can be thrown off.

Selective solder has its place.
It requires care and feeding on a shift basis.

Larry Dzaugis

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