Hi Ahne,

The Coefficient of Thermal Expansion (CTE) for all phototooling films on
7-mil (175 um) polyester base is 0.0010%/ºF (10 ppm/ºF).  The Coefficient
of Hydroscopic (Humidity) Expansion (CHE) varies somewhat from film to film
depending on structure and composition.  Diazo films have a CHE of about
0.0009%/%RH (9 ppm/%RH).  Modern (gel-polymer) silver halide films have a
CHE generally in range 0.0010 to 0.0012%/%RH.  Older silver halide films
have a CHE in the range of 0.0012 - 0.0015%/%RH.

Size changes that occur during long term storage depend highly on the
storage conditions.  Polyester exhibits hysterisis when exposed to large
changes in relative humidity.  When stored under consistant temperature and
relative humidity, however, the films will retain accurate size.

There's an article in the July 1998 issue of Printed Circuit Fabrication
that goes into more detail.

Does anyone know the CTE/CHE of laminate?

Regards,

Bob Seyfert
Technical Manager - Phototools
DuPont Electronics



At 08:50 AM 8/7/98 -0700, Ahne Oosterhof wrote:
>Hi Bob,
>Do you have typical numbers for expansion / contraction for film materials
>with respect to temperature and humidity and maybe even age ?
>
>Ahne Oosterhof,
>A-Laser, Inc
>
>
>-----Original Message-----
>From:  TechNet [mailto:[log in to unmask]] On Behalf Of Bob Seyfert
>Sent:  Thursday, August 06, 1998 14:27
>To:    [log in to unmask]
>Subject:       Re: [TN] Film Stabilization
>
>Hi Marco,
>
>It does not matter what temperature or RH you choose for your plotter room,
>conditioning room, yellow room, etc-provided that the conditions are the
>same in all areas where the film is handled and used; and the conditions in
>these rooms are not changing.  Pick conditions that are easy to control to
>and comfortable to work in.  The film does need to be pre-conditioned and
>plotted at the same temperature and RH as the yellow room where it will be
>used.  Complete pre-conditioning requires 6-8 hours if you use a cabinet
>designed to allow air to come into contact with both sides of the film (open
>wire shelves - one sheet per shelf).  It will take considerably longer under
>other conditions.  After post-processing conditioning requires 1-2 hours on
>open shelves.
>Regards,
>Bob Seyfert
>Technical Manager - Phototools
>DuPont Electronics

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