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Reply To: | TechNet E-Mail Forum. |
Date: | Tue, 20 Jul 1999 14:02:45 -0800 |
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Charles-
Don't know where you are located but humidity will obviously effect
moisture absorption rates... here are some general guidelines:
1) Bake temp should be about 250 F. Baking at less than 220 will do very
little to drive out moisture. Extended bakes above 270 can embrittle the
adhesive.
2) Rigid-flex and flex printed wiring with acrylic adhesives are
significantly more hygroscopic than polyimide glass or epoxy glass
pwbs.
3) Profile ovens to determine start-up and recovery times - Large ovens
can take up to 10+ minutes to recover...
4) Standard flex single-sided / double-sided - 10-20 minutes
5) Multilayer flex (only) up to .050 thick - 1-2 hours
6) Rigid-flex 4-12 hours-- depending on thickness.
7) After baking, solder immediately - or use dry box with desiccant for
short term staging. Thicker parts will absorb moisture more slowly. Do
not recommend dry nitrogen.
Hope this helps...
>>> Charles Barker <[log in to unmask]> 07/19/99 11:25am >>>
Gosh Guys and Gals;
Are we the only ones working with rigid-flex? Or is this information
proprietary? The responses have been less than usual for some
reason. Is
the server getting this out to everyone?
Thanks,
Charlie B.
---------------------- Forwarded by Charles Barker/US/I-O INC on 07/19/99
02:07 PM ---------------------------
Charles Barker
07/18/99 01:53 PM
To: [log in to unmask]
cc:
Subject: Board baking
We are just getting into regular assembly of rigid-flex boards. What are
folks doing about removing the moisture absorbed in the flex?
Is anyone using nitrogen as a drying agent? What are sources of
"dry-boxes" and such?
All you flex makers out there, what do you recommend?
TIA
Charlie Barker
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