Denny,
We have always treated FR4 PCBs as moistures sensitive and baked them
out before reflow to be safe. Everyone has there own idea about bake out
time and temperature and most CMs do consider the PCB moisture
sensitive. We bake for 5-6 hrs at 110 C. Boards are generally used
within 2-weeks of bake out.
Best Regards,
-joe
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From: TechNet [mailto:[log in to unmask]] On Behalf Of Dennis Fritz
Sent: Wednesday, August 27, 2008 7:10 AM
To: [log in to unmask]
Subject: Re: [TN] Moisture in PCB Assemblies
Bill,
There has been some speculation that with the higher assembly
temperatures of lead-free, that PCBs should have a Moisture Sensitivity
Level - just like the components being mounted on them.? However, I
don't think JEDEC will step up to the plate to adopt anything to do with
PCBs.? So, it would be the job of the IPC to do that.?
With the upcoming IPC meeting in late September, Schaumburg, Illionois,
now would be a good time to debate the need for circuit board MSL
levels. As pointed out, the group working on Storage and Handling will
go a long way, but moisture absorbsion propensity is also a property of
the resin/glass composition of the board.?
How about it TechNetters?
Denny Fritz
MacDermid, Inc.
-----Original Message-----
From: [log in to unmask]
To: [log in to unmask]
Sent: Tue, 26 Aug 2008 7:19 pm
Subject: [TN] Moisture in PCB Assemblies
Fellow TechNetters:? I was asked a question by a valued customer if
there is any
other references made to moisture in raw PCBs and populated assemblies
other
than the J-STD-033 and also the IPC rework standards.? I've looked in
IPC
Standards I have on file however I could not find any
references/guidlelines at
all.? Can anyone out there shed some light on this???
I thank you folks in advance for your efforts on my behalf.
Bill Black
Medco
Q.A. Manager
Tel:? 631-667-9699
E-Mail:? [log in to unmask]
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