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February 2004

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Subject:
From:
Tom Gervascio <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 25 Feb 2004 08:01:08 -0500
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In a previous life, we used to use a Centech vapor phase reflow to
reflow large backplanes. May have issues with thermal shock due to the
large temperature gradient generated when the vapor phase fluid (which
is very expensive) condenses on the board and gives up the latent heat
(heats up the board). On the positive side, it is impossible to overheat
the board and can heat up large thermal masses quickly.


Also maybe a preheat of a board before running the boards thru the
solder wave with some topside flux application (just make sure that the
flux gets properly activated and cleaned off).

Hope this helps

Tom Gervascio
Senior Process Engineer
Sparton Electronics
(352) 540-4040

>>> [log in to unmask] 02/24/04 02:50PM >>>
Hi everyone,

I am a Manufacturing Engineering in an area that builds test equipment
for
airborne radar systems.  For the past several months Design Engineering
has
been giving us a variety of "thick" boards to which to solder thru
hole
components.  The boards range in thickness up to .250".  We have been
substituting press-in sockets where possible, but they are not always
available in the sizes we need.  So far, in the most difficult
situations, I
have been using an Airvac solder volcano.  This works fairly well, but
can't
be used in all situations, and doesn't always result in flow thru to
the
other side.

Is there any other system that would be more appropriate for thick
boards
where flow thru is a problem?  We are working to            J-Std-001B
Class
3.  We are ready to go back to the designers (and have gone back to
them),
but I would like to find out if there are other possibilities first.

Thanks for any help you can give,

Bill Mengers
Mfg. Engineer
Northrop Grumman Corp.
Baltimore

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