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September 2006

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Subject:
From:
Steve Gregory <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Steve Gregory <[log in to unmask]>
Date:
Wed, 6 Sep 2006 12:07:27 -0500
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text/plain
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text/plain (71 lines)
Hi Joe!

Going through a aqueous cleaner won't cause problems with 2nd side
reflow. The moisture that you have to worry about is the moisture that
is absorbed over time. Sticking to the floor life time guidelines that
go along with the limits of each part, i.e.; Level 1, 2, 3, etc., is
what you need to be concerned about. You don't need to re-bake the
assemblies if you're within the floor life of the part.

-Steve Gregory-

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Macko, Joe @ IEC
Sent: Wednesday, September 06, 2006 11:31 AM
To: [log in to unmask]
Subject: [TN] Populated board bake out after 1st side reflow/DI wash

Fellow techs,



Hello.

A general question came up about the need to re-bake a double sided
board after 1st side reflow/DI wash before starting 2nd side assembly.
The concern is that the board (or mounted MSDs) may absorb enough
moisture going through the high-pressure DI water in-line cleaner to
potentially cause a problem during 2nd side reflow. There are some MSDs
mounted on the 1st side but both sides are assembled before exceeding
any of the component's floor life. It has been suggested that some level
of bake out should be performed after 1st side cleaning to prevent
potential problems during 2nd side reflow but the push back is that this
adds cost, handling, etc... that may introduce its own associated
problems and is not really necessary.



Thanks again. It is great to have a knowledgeable forum such as TechNet.



Joe






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