Hi Genny,
Treating PCBs as moisture sensitive devices is a good move.
As your pink HICs show, MBBs are not hermetic and it is also likely that your PCBs already have absorbed moisture.
If you do not have any idea how much moisture there is, the recommendation is at least 24 hours at no less than 105C.
I have a whole section on moisture absorption, bake-out, packaging, etc. in my White Paper on secifying PCBs for survivability of Pbfree processes.
Werner


 


 

-----Original Message-----
From: Genny Gibbard <[log in to unmask]>
To: [log in to unmask]
Sent: Wed, Oct 14, 2009 1:10 pm
Subject: [TN] PCB moisture










We have recently decided to start handling bare PCBs as moisture
sensitive devices internally.  
We pack them in MBB, if they do not arrive that way from the supplier.
Now we are seeing a lot of HICs pink when we open the packages at a
later date.  Should we be baking these boards?  Any recommendation as to
how to bake, or where to look for the best source of info for that?
The most common finishes we use these days are Immersion Ag and tin-lead
HASL.  As the volumes on our products get higher, a lot of our PCBs get
made off-shore.

Genny 

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