Hi Bob,
Thanks for all your help. I will try all your suggestions and see which one
works. Thanks again!
Marco Biagtan
NEC Components Phils., Inc.
Process Engineer
Bob Seyfert wrote:
>
> Hi Marco,
>
> If this is problem that occurs only with your contact films and not your
> plotted films, then I would look first at your contact printing process.
> It possible that it is rooted in your film (since this is a different
film
> than the plotter film), but I'd look first at the contacting process.
>
> It is quite possible that the film is getting distorted in the exposure
> step, as Paul suggested. In general, I recommend that you use a contact
> frame designed for film-to-film contacting, such as those used in the
> graphic arts (printing) industry. Trying to use a resist printer (which
> was designed for thicker panels and larger volume air evacuation) often
> results in dimensional stability problems. Also, some designs of contact
> printer work better than others. Many newer designs put high emphasis on
> rapid air evacuation to give short vacuum drawdown times. They do this
by
> various methods of applying pressure to push the air out. Some of these
> can produce machanical distortion of the film at the same time. Some
work
> fine.
>
> I suggest the following:
>
> 1. Be sure your contacting film is equlibrated the same way your
plotting
> film is.
>
> 2. Use a stiff, black, matted, plastic backup sheet behind your film
when
> you expose it. This will tend to protect the film from mechanical
> distortions. These are available commercially in the U.S. through
graphic
> arts suppliers. I am uncertain about availability in Japan.
>
> 3. Use adequate drawdown time to insure complete air evacuation. One to
> two minutes may be required on some contact frames. Run a test to
> determine what your frame needs.
>
> 4. In order to separate size changes that occur during exposure verus
> those that occur during processing, it is possible to expose a piece of
> film, apply developer to the areas that contain the fiducials with a
cotton
> swab, then fix the fiduals by applying fixer with a cotton swab. Now
turn
> on the lights and carefully rinse the processed areas with another cotton
> swab containing water. Allow the film to dry before measuring it.
>
>
> If you still can't find the cause of your size change, send me a note
> directly with the details of your process (type of contact frame, type of
> film, process steps, etc.) and we'll spend some time tracking it down.
>
> Best regards,
>
> Bob Seyfert
> DuPont Electronics
>
>
>
> At 09:04 AM 5/23/98 +0800, you wrote:
> >Hi John,
> >Sorry guys if I misunderstood. We do have a glass base over which the
> >films are laid and then this is covered by a rubber covering before
vacuum
> >and exposure.
> >I have always checked the film dimension after developing; I haven't
really
> >checked the dimensions of the film after exposure since only a latent
image
> >is seen (we're using silver halide for our contacts), but I'll try. We
do
> >use overcoats over our films (PPF) but this is applied later during the
> >process.
> >
> >
> >John Waite wrote,
> >>
> >> Hi Marco,
> >> What Paul is referring to is if the drawer has a glass base, and
the
> >top side has a mylar.
> >> It sounds like you have a "glass pac" style tooling. AT what point do
> >you see the "distortion".
> >> Is is off the diazo developer or during exposure, or after transfer of
> >the phototool to imaging
> >> area. Also, are you using a covercoat over your diazo (IE- APF,PPF,
> >etc). Sorry about my
> >> misinterpretation. I thought you were using 1st generation silvers.
> >JOHN WAITE
> >
> >>
> >> Marco Biagtan wrote:
> >>
> >> > Hi Paul,
> >> > I'm sorry but I don't quite understand what you mean about the
single
> >sided
> >> > glass exposure frame. The flexible membrane of our exposure machine
> >has a
> >> > thin glass frame on top of it as well as a thick glass frame where
we
> >lay
> >> > our films. Is this the same?
> >> >
> >> > Anyway, thanks a lot for the suggestion. This is the first time
I've
> >heard
> >> > of this and it might just be what I'm looking for.
> >> >
> >> > Marco Biagtan
> >> > NEC Components Phils. Inc.
> >> > Process Engineer
> >> >
> >> > Paul Gould wrote:
> >> >
> >> > > Marco,
> >> > > Just had another thought if it is only your contacts. If you are
> >using a
> >> > > single sided glass exposure frame with a flexible membrane over
the
> >top,
> >> > > your copy film will be in contact with the membrane and will tend
to
> >get
> >> > > mechanically stretched. This would result in an apparent shrinkage
> >after
> >> > > exposure. If this is a possibility, put a sheet of black card on
top
> >of
> >> > > the film before closing the lid and pulling the vacuum.
> >> > > Hope this helps.
> >> > > Paul Gould
> >> > > [log in to unmask]
> >> > > Teknacron Circuits Ltd
> >> > > Fax: 1983 865141
> >> > > Tel: 1983 866531
>
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