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Date: | Fri, 03 Jan 97 09:12:52 EST |
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T. Gaylor:
As you already know the main area of consideration in flex
manufacturing is the material. The flex layers are an integral part
of the construction and being a different material than the rigid
layers, they change differently. Flex material is a film which by
itself will shrink or grow depending on ambient conditions. Typically
polyimide film, (Kapton) can change a mil per inch during processing.
Some of this change can be compensated by scaling artwork, lamination
cycles and lam materials and a big one, handling.
Flex lamination requires a minimum of two lam cycles. The first is a
coverlayer which is the insulating film in the flex area. This
requires a conformal pad top and bottom in order to wrap the film
around the conductor. This pad structure can consist of teflon glass
cloth, tedlar, combination materials such a trade name product,
"pacothane" or silicone rubber. The second lam cycle is the
multilayer lamination which usually utilizes no-flow prepreg but could
be constructed using an unsupported adhesive film such as Dupont's
Pyralux. Again there can be different pad make ups. As with rigid
boards there can be blind or buried via processing.
The basic processing steps are the same for a rigid-flex as for a
rigid board except that there are more of them, and it requires more
tooling and front end engineering.
Obviously equipment must be capable of handling thin cores. A typical
double clad core will 1 oz cu/2 mil dielectric/1 oz cu which is less
than 5 mils thick. The copper is usually dead soft, rolled and
annealed which is where the handling problem comes in to play.
Another area of concern is hole quality. There are different drill
parameters required for rigid-flex and you would not typically stack
more than one high on the drill. Desmearing in most cases requires
plasma etch capabilities.
These are a few of my rambling thoughts. If you would like to discuss
off line give me a call.
Regards,
Ron Yanuszewski
603-337-1691
______________________________ Reply Separator _________________________________
Subject: Flex
Author: [log in to unmask] at !INTERNET
Date: 1/3/97 12:18 AM
I am curious, about the manufacturing of rigid/flex circuits.
At our shop, we currently are not looking into any type of technology
similar to this. I would like to know the considerations of working
with a process such as this.
I have heard that the lamination technique is somewhat different than
conventional rigid multilayer processing. Also, another difference I
have heard is the registrationing of the flex to rigid.
I would appreciate if someone could give me some insight on rigid/flex
processing.
Thanks in advance
T. Gaylor
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