Homebrew PCBs

twb8899:

I also remember cutting "Rubylith",
but I guess that sort of stuff is gone
forever.

"Coordinatograph"  pops  up in my
memory.

Roland F. Harriston
*****************
twb8899 wrote:
>
> Roland,
>
> You're correct about using the methods I mentioned earlier for micro
> wave strip lines. I used to have a commercial shop and used much of
> the same equipment I now have to make strip line and other RF
> circuits. These were for McDonnell F/A-18 parts and equipment. I
> closed that plant several years ago but kept most of the smaller
> equipment for my home based shop.
>
> I built my spray developer and spray etcher from scratch and use them
> all the time. They are a simple design and kind of based on the Kepro
> stuff. When Kepro shut down I bought quite a bit of the manufacturing
> equipment they used to make their products. I'm now thinking about
> making the etchers myself and offering them for sale. Biggest problem
> is getting the cost down. The Kepro units were way too expensive and
> could probably be offered for a more attractive price with some
> engineering changes.
>
> This new spray etcher is in the works but it's still to early to say
> much about it except that the prototype works great. If we can get the
> cost just right it will be available later this summer. If anyone is
> interested in a product like this contact me by email and I'll forward
> photographs and more information when we are ready to go.
>
> Tom
>
> --- In Homebrew_PCBs@yahoogroups.com 
> <mailto:Homebrew_PCBs%40yahoogroups.com>, "Roland F. Harriston"
> <rolohar@...> wrote:
> >
> > twb8899:
> >
> > Your technique is probably the most "professional"
> > that I've read about on this forum.
> >
> > Negative acting resist may have an edge over
> > the positive stuff, and may produce better products.
> >
> > I don't know if "Resiston" or any of the laminated resist
> > materials are still being made, but this stuff worked really good.
> > But one needs to have a dry film laminating setup to use it.
> >
> > I recall the excellent results that Kodak KPR resists
> > could produce, but alas, the Feds said it was too
> > nasty and Kodak moved away from it, although I
> > think some version of KPR is still being made for
> > the microcircuit fab industry, but not generally
> > available to the public.
> >
> > A lot of microstripline work used to be done using
> > the photo plotter methods you described, but I've been divorced
> > from that area for so long, I don't know what they
> > are using now. It might be interesting to set up a
> > plotter using an LED "pen" in a dark box to plot
> > on sheets of litho film and then develop the film
> > in AB litho developer. I think such a setup could
> > produce some really high contrast PC artwork.
> >
> > Having done "tape-up" artwork as large as 10X,
> > and having it reduced to Actual on a big copy
> > camera, I have a feeling for the accuracy one can
> > obtain from the methods you described.
> >
> > Good Show!
> >
> > Roland F. Harriston
> >
> >
> >
> >
> >
> >
> > twb8899 wrote:
> > >
> > >
> > > I use photo plotted film negatives with negative acting dry film photo
> > > resist. Expose with 1 kW mercury vapor bulb for 17 seconds. Etching is
> > > with ferric chloride at 110 degrees F in a small spray etcher. I use
> > > negative acting resist because it's lower cost and exposes much faster
> > > than positive types. Almost never have any rejects using this method.
> > > My production is 10 to 50 boards per lot with nearly 100% yield every
> > > time.
> > >
> > > Find a supplier in your area with a photo plotter to make your films.
> > > If that's not available plot the design at 2:1 scale with black ink on
> > > white paper and have a printing shop shoot a negative film at 50%
> > > reduction on their camera. You will have a high accuracy master film
> > > that will last for years.
> > >
> > > Do some research on D-min and D-max concerning photo films. It's the
> > > measure of density in the clear and black areas of the film. The
> > > biggest problem with laser and ink jet printing is not enough D-max or
> > > very dense black areas. Shine a lamp through the black areas of your
> > > film and look at it with a maginfier. This is what your photoresist is
> > > seeing and it's usually not dense enough for a proper exposure.
> > >
> > > Tom
> > >
> > > --- In Homebrew_PCBs@yahoogroups.com 
> <mailto:Homebrew_PCBs%40yahoogroups.com>
> > > <mailto:Homebrew_PCBs%40yahoogroups.com>, "lcdpublishing"
> > > <lcdpublishing@> wrote:
> > > >
> > > > Hi guys,
> > > >
> > > > I have almost given up on direct ink-jet resist and on "plotting"
> > > > with Staedtler pens using the CNC machine, and I am about to abandon
> > > > toner transfer. Only problem with toner transfer is the "scaling"
> > > > issues either through the printer or from the paper not being stable
> > > > which causes problem with CNC drilling.
> > > >
> > > > Anyway, I ordered up some negative type resist chemical, the
> > > > developer, a lamp, and an exposure frame. I am not expecting this
> > > > to go "perfectly" either, but am hoping to have a bit less
> > > > frustration in other areas.
> > > >
> > > > I am thinking the best accuracy I can get when printing is to use an
> > > > ink jet printer (I have Epson R220 and Epson CX6600). I have a PDF
> > > > editor program that allows me to edit trace colors and back ground
> > > > colors so that I can make negatives so that shouldn't be a problem.
> > > >
> > > > The first "problem" I suspect I will run into is getting enough
> > > > density on the transparency to make sure the "black" areas are dense
> > > > enough to block out the UV exposure lamp where needed. Has anyone
> > > > run into this issue and how do you deal with it?
> > > >
> > > > Any other pointers would be greatly appreciated as well as this is
> > > > my first time for "photo-processing".
> > > >
> > > > Thanks
> > > >
> > > > Chris
> > > >
> > >
> > >
> >
>
>