Most of the time we worry about moisture when delamination
occurs. When boards are built well using FR4 delamination is rarely an
issue. For some other materials it is a different story. I had a FR4
test board that had 1/2 " drilled holes to test a wave solder wave
height. It never delaminated, did not ever bake it.
	Delamination occurs due to unclean surfaces, contaminants
entrapped.... Some people have the recipe and follow it and some do not.
	Regards,
	Ramon	



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Richard Kraszewski
Sent: Tuesday, May 29, 2007 10:53 AM
To: [log in to unmask]
Subject: Re: [TN] PWB Moisture Diffusion Rates

I'd be real appreciative of getting details on this topic also. Seems
that everyone agrees that mositure is detrimental for a PCB on multiple
levels but good documented evidence, & studies seem to be short supply. 

BTW- One recent study on this subject was however presented at APEX this
past year by Paul Hamilton of Intel. 

Rich K / GTS
847-621-7310
 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Gumpert, Ben
Sent: Tuesday, May 29, 2007 8:16 AM
To: [log in to unmask]
Subject: [TN] PWB Moisture Diffusion Rates

Fellow Technetters,

Anyone have data on moisture diffusion in and out of various PWB
materials? For various thicknesses, geometry, layers?

Is anyone treating boards differently through any processes, such as
duration and temperature of pre-build bake, or maximum time allowed out
of packaging before baking (for initial build or hand soldering /
rework) based on material or physical dimensions?

Ben Gumpert



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