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From:
Francois Monette <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 26 Aug 2003 09:23:28 -0400
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Bonjour Yannick,

Here are a few additional considerations relative to dry storage :

Make sure that you understand exactly what kind of benefit you will get from
your dry storage solution. In the contract manufacturing business, many of
your customers will expect that you comply with the guidelines from the
latest IPC/JEDEC standard J-STD-033A. This document contains precise rules
on how to account for dry storage. In summary the clock of exposure time
does not necessarily stop when previously exposed components are returned to
dry storage, whether it be a dry cabinet, Nitrogen box or re-sealed dry bag
with desiccant.  The actual effect of dry storage on the remanining floor
life will vary based on the type of component (MS level), the type of dry
storage (RH level) and the complete history of exposure and subsequent
storage.

I also suggest that you be careful when reading the marketing data provided
by some of the vendors of dry storage solutions. In many cases their
conclusions are based on experimental data using a weight gain measurement
technique. This is not consistent with the current industry standard which
is based on a much more accurate moisture diffusion model. I can provide
more details and technical references if you are interested.

Regards,

Francois Monette
Cogiscan Inc.
Tel : 450-534-2644




-----Message d'origine-----
De : Steve Gregory [mailto:[log in to unmask]]
Envoy=E9 : Thursday, August 21, 2003 11:19 AM
=C0 : [log in to unmask]
Objet : Re: [TN] Dry Cabinet


Hi Yannick!

We use the McDry cabinents here, and they work great. The humidity =
level is
kept around 4% RH, and that's not too bad..you know, it never gets hot =
or
humid here in Tulsa, Oklahoma (GRIN). Also, when I start running low on =
beef
jerky, I'll just throw a few slabs of beef in for a few days...(JUST
KIDDING)

You may think at first they are expensive, but when you figure the =
costs of
plumbing nitrogen, and the on-going expense of using the nitrogen, the =
costs
really aren't that bad.

There's virtually no maintenance on them, as they self-regenerate the
dessicant in them. You should send the humidity meter out annually for
calibration, McDry will do that for you. In fact, they send you a =
notice
when yours is due for calibration.

Camera dry boxes are kind of small, and the ones I've seen don't go =
down to
the low humidity levels that the dry boxes for electronics do.

One good thing about desiccant cabinents, is that you can avoid baking =
if
the components are left in the dry box long enough. According to the =
data,
they will actually "de-humidify" the components bringing the absorbed
moisture down to a level below where "pop-corning" or micro-cracking =
can
occur.

There's two companies that I know of that make these desiccant dry =
boxes.
One is McDry (the ones I use), and the other is a company called Toyo
Living. This last APEX show is the first time I've seen Toyo Living dry
boxes. They supposedly are cheaper than McDry, and also contain heaters =
that
work in conjunction with the desiccant. Here's the links to both =
companies"

http://www.seikausa.com/mcdry/
http://www.toyoliving.biz/

Best regards,

-Steve Gregory-




Hi,=20

we'll use the cabinet for keep our QFP dry, we use to have a moisture
probleme right now, I don't know the level of humidity/dryness to be
maintained, cause it's maybe depending of the component, we don't what
something complex, jsut a standard cAbinet not to expensive...

Yannick

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