Damon,
No worries, it was not me who wrote the other answer :-). I have no
problem to disclose all information or else I would not have uploaded
the stuff. in fact I did so in the hope it helps other interested
parties. However, there's not that much to it actually that's why I
thought not more information is needed. But you are right, the devil
sometimes lies in the details.
What I can aditionally clarify here is that by "battery charger" in my
previous post I meant a CAR battery charger. That's a good source for
cheap transformers where I live (Switzerland). Surprizingly, if I buy a
transformer in an electronics part shop, I pay more than if I buy such a
car battery charger. I often buy some of them if they are on sale. The
nice thing here is that with the bigger units, you really get powerfull
tranformers which otherwise would be fairly costly (again, where I live,
no idea wether they are cheap elsewhere) - plus usually an amp meter,
some cabling fuses and a housing that can be reused as a plus :-)
The exposure unit boxes where choosen so as a double euro card could be
exposed, but later on it turned out that buying that many LEDs would be
too costly. The cheapest source for the LEDs I found so far is Reichelt
in germany, (www.reichelt.de) where one LED is 1.4 EUR. They otherwise
seem to be either fairly high prized or not available - at least where I
can buy them.
HTH
Markus
javaguy11111 schrieb:
>
> It is up to you how much information you want to supply. If I or
> someone else were to try and duplicate your work it helps to have as
> much information as possible. Whether it is datasheets, schematics,
> process, etc. That is why I ask all the questions. You are obviously
> under no obligation to answer them.
>
> I think the datasheet for the UV LED is probably the most important part.
>
> Thanks,
> Damon
>
> --- In Homebrew_PCBs@yahoogroups.com
> <mailto:Homebrew_PCBs%40yahoogroups.com>, Markus Zingg <homebrew-pcb@...>
> wrote:
> >
> > 1. Not sure what you mean. I use overhead foils that I print onto using
> > an Epson Stylus C62. The PCB's are laminated using dryfilm fotoresist
> > (in my case Ordyl Alpha 950)
> >
> > 2. The datasheet is now uploaded in the project directory (
> > Homemade_PCB_equipment -> UV LED exposure unig)
> >
> > 3. I could, but it's realy dead simple. Since I use 5 LEDs in series,
> > ~20V are requiered. I used a transformer that I took out of an el
> cheapo
> > battery charger (a 4 amp part with a center tab actually rated for 12V
> > but by not using the center I can draw 24V @ 2amps). That goes
> through a
> > rectifier and then a traditional LM317T is used to regulate the voltage
> > to 20V. Just downlaod the datasheet from national and look at the
> > standard cirquitry. I think if you build such a unit you may want to
> > change things or use some parts you have laying around. Well, if you
> > really want I can upload the eagle schematics and board layout.
> >
> > 4. I so far only did boards with it for customers where I first would
> > have to ask for the Ok to publish their board here. My boards are
> > probably a bit special in that they are mostly 4 layers with solder
> stop
> > mask etc. pp. So they look pretty much like any other profesionally
> made
> > board you may have laying around anyways. However, what in
> particular do
> > you want to see/know? I may can upload a part of a board only?
> >
> > Markus
> >
> > javaguy11111 schrieb:
> > >
> > > Very nice. A few questions
> > > 1. What are you using for the mask
> > > 2. Can you upload the datasheet for the LED's you are using.
> > > 3. Can you post parts lists and schematics for the driver board.
> > > 4. Do you have any pictures of boards you have done with it.
> > >
> > > Again very nice. Congratulations.
> > >
> > > --- In Homebrew_PCBs@yahoogroups.com
> <mailto:Homebrew_PCBs%40yahoogroups.com>
> > > <mailto:Homebrew_PCBs%40yahoogroups.com>, Markus Zingg <homebrew-pcb@>
> > > wrote:
> > > >
> > > > Hi group
> > > >
> > > > Last summer I created a UV LED based exposure unit with which I had
> > > IMHO
> > > > very good results. I uploaded a description and pictures to the
> > > > following place in the files section:
> > > >
> > > > Files </group/Homebrew_PCBs/files/> > Homemade_PCB_equipment
> > > > </group/Homebrew_PCBs/files/Homemade_PCB_equipment/> > UV LED
> > > exposure unit
> > > >
> > > > Below you find the descriptive text for your quick reference -
> enjoy!
> > > >
> > > > Markus
> > > >
> > > > <------- cut here --------->
> > > >
> > > > UV LED exposer unit
> > > > -------------------
> > > >
> > > > In this folder you can see pics of my homebrew, UV LED based double
> > > side exposure unit. The folowing features are maybe "special" enough
> > > to be noted:
> > > >
> > > > - It generates very PARALELL light. This is important if you want to
> > > make small traces. Using this unit, I already sucessfully created
> > > boards with 5 mil traces using dry film fotoresist.
> > > >
> > > > - There are two holes in each glass allowing the positioning shafts
> > > I use to allign the films against the PCB to remain. This allows me to
> > > leave the protection foil on the dryfilm resist, resulting in almost
> > > no wear out on the films.
> > > >
> > > > - Obviousely this unit allows to expose both sides of a PCB at the
> > > same time. To do this, the upper box is simply placed on top of the
> > > lower. The glass is intentionally NOT mounted to the boxes. This
> > > allows me to fimrly press the two glasses together thereby makeing
> > > sure there are no air bubbles.
> > > >
> > > > - The LED distance is 20mm square, distance from the LEDs to the PCB
> > > is ~65mm
> > > >
> > > > The exposure time is longer than what's normal with tube oriented
> > > units. I'm almost exclusively working with dryfilm resist due to it's
> > > several advantages. There the time is exactly one minute.
> > > >
> > > > Feel free to ask questions, otherwiese enjoy :-)
> > > >
> > > > Markus
> > > >
> > >
> > >
> >
>
>