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June 2011

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Subject:
From:
"Goodyear, Patrick" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Goodyear, Patrick
Date:
Tue, 7 Jun 2011 20:10:34 -0700
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I would recommend that you do dry bake them at say 120 deg for at least
an hour to dry out the PCB, the other option would be using a moisture
absorbing chemical.   We have recently repaired a bunch of 40 year old
single sided boards, measling was an issue due to the moisture content
of the boards.  We did heat the ones that required extensive rework with
a heat gun for a few minutes and that helped.   However I prefer to put
them in our environmental oven for at least 4 hours to dry them.  

Pat Goodyear 
Control tech PG&E 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Joe Macko
Sent: Tuesday, June 07, 2011 10:48 AM
To: [log in to unmask]
Subject: [TN] PCB dry-bake requirement for thru hole connector
replacement

All,

 

I would like to hear  some comments as well as lessons learned from the
experts concerning the basic requirement to dry-bake populated boards
prior to some thru hole connector replacement. The boards are double
sided and are also populated with numerous SMT components, some of which
are moisture sensitive. Solder alloy is SnPb.

 

Our normal process is to dry-bake "PCBs" prior to reflow and so the
question came up if we should also dry-bake the now populated boards
prior to replacement of some thru hole connectors to prevent potential
damage to the PCB and/or surrounding parts.  The connectors will be
removed and replaced using  either one or a combination of a Selective
Solder machine and\or solder pot. If we were doing a BGA replacement
using a hot air machine, we would dry-bake the populated board.

 

Thanks again for the valuable feedback.

-Joe

 


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