Charles Caswell,
From an ESD perspective, I believe that you are in good shape. You're using
Nitrogen with a grounded tip to blow off alcohol. If you or you customer
need confirmation, get a static meter, and see if you can generate a charge
from the gun / tip when in use. My only concern is that I've used pressures
up to 80 psi, but that's because the facilities I've worked in never had
Nitrogen or Shop Air above 80 psi. At 100 psi, I would be more concerned
about damaging the hardware with that amount of pressure.
Having worked previously with space applications, if I was your customer, I
would be more concerned about using just IPA to clean boards instead of
using an aqueous cleaner. For spot cleaning, IPA works well, but for board
cleaning using rosin based flux (I'm assuming that you're using rosin flux
for space applications), I found that IPA may not be as great a cleaner as
the customer may think. Most aqueous cleaners are better, from an ionic and
non-ionic standpoint, than Freon based cleaners and IPA. Just my opinion.
For an experiment, build some "flight quality" hardware, clean a few boards
with just IPA, and a few with the aqueous cleaner. Test the boards via Ionic
Chromatography and see if the IPA cleaned boards are as "dirty" as the
aqueous cleaned boards; what level of and types of contamination both boards
are at.
Good Luck
Lee Whiteman
Senior Manufacturing Engineer
ACI / EMPF
Telephone: (610) 362-1200; Ext. 208
FAX: (610) 362-1290
E-Mail: [log in to unmask] <mailto:[log in to unmask]>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of [log in to unmask]
> Sent: Monday, August 28, 2000 10:41 AM
> To: [log in to unmask]
> Subject: [TN] Another ESD question
>
>
> How do you folks feel about using compressed nitrogen to dry
> printed circuit
> boards? One of our customers will not allow aqueous cleaning of
> their hardware.
> As a result we clean all of their hardware in alcohol and dry by
> blowing it off
> with compressed nitrogen with the regulator at about 100 PSI. The
> nozzle is
> grounded at the tip. Please note that this is not related to my
> earlier quetion
> as this is done in a different area and only used on our space
> flight hardware.
> Thanks again,
> Charles Caswell
>
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