This topic comes up on TechNet about every two years. Check the archives.
Remember that you are limited by diffusion and a higher vacuum is not always
better because if you end up freezing the water near the surface, well you
can imagine how slow things would be then.  There is also a volume change in
that case, but I am not sure there is enough water to cause delam, but I
would be careful.
Bev

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Reuven Rokah
Sent: Friday, June 01, 2012 1:57 PM
To: [log in to unmask]
Subject: Re: [TN] Vacuum Drying of PCB's

Hi Steve,

Usually it used for tape and reels (max temp allowed is 40 degC) so the
temp to be used is 40 degC and level of vacuum level is -25 / -30 inch Hg.

Reuven

On Fri, Jun 1, 2012 at 8:45 PM, Steven Creswick
<[log in to unmask]>wrote:

> Reuven,
>
> Thanks for the approximation.  This is without heat - correct?  What level
> of vacuum?
>
> Ditto on the radiation and conduction!  Absolutely correct!
>
> Steve
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Reuven Rokah
> Sent: Friday, June 01, 2012 1:37 PM
> To: [log in to unmask]
> Subject: Re: [TN] Vacuum Drying of PCB's
>
> Hi Richard,
>
> it about 30% faster and you should know that only thermal radiation and
> thermal conduction work in vacuum oven, no convection because of no air
> exist.  You should add more shelves and spread the PCBs / components on
the
> shelves to assure good contact.
>
> The advantage is less oxidation on pads / metal parts.
>
> Reuven
>
> On Fri, Jun 1, 2012 at 5:47 PM, Richard Kraszewski <
> [log in to unmask]> wrote:
>
> > I would appreciate anyone sharing their thoughts on vacuum drying of
> PCB's.
> >
> > What conditions do you use? (Time, temp and vacuum)
> >
> > I realize it can be used to reduce required peak temperature but is
> > there potentially any time reduction benefit to using vacuum?
> >
> > I saw a paper from the "Electronic Components and Systems Division
> > within German Electrical and Electronic Manufacturers´Association
> > Working Group", entitled
> >
> >  "Recommendation & Guideline Values for drying for bare PCBs"
> >
> > The offered a rather paltry reduction in drying time of 60 minutes
> > from 8 hours if vacuum was used. Doesn't seem like much of a benefit.
> >
> >
> > Rich Kraszewski/PLEXUS
> >
> >
> > ______________________________________________________________________
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>
> --
>
> Best Regards,
>
> *Reuven Rokah*
>
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-- 

Best Regards,

*Reuven Rokah*

Mobile: 972-52-6012018
Tel:        972-3-9360688
Fax:          076-5100674
 <http://www.rokah-technologies.com/>[log in to unmask]
[log in to unmask]
www.rokah-technologies.com

**
This e-mail message is intended for the recipient only and contains
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Technologies. If you have received this transmission in error, please
inform me by e-mail, phone or fax, and then please delete all of the
original files and all other copies exist.

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