I have watched the discussions on printers and their limitations on this
forum.
I have seen the use of DLP projectors to harden resin in 3D printers.
I was wondering if a similar adaption will be effective in exposing
photoresist material at very high resolutions.
Maybe use high resolution CRT or LCD monitor as a contrasting source of PCB
image. A PCB could be prepared and taped on the monitor for exposed.
...raj
On Sun, Jan 8, 2012 at 9:53 AM, jpanhalt <janhalt@...> wrote:
> ∗∗
>
>
> I have been away for awhile and noticed several recent posts investigating
> various printers and inks for making really dark transparencies for photo
> exposure masks.
>
> I have been using the positive photoresist method for more than 10 years.
> Initially, I used an HP inkjet on a high quality (expensive) transparency
> medium produced for commerical artists. That worked well, but infrequent
> use led to dried ink cartridges and all the problems associated with that.
>
> More recently, I simply make my transparencies with a laserjet (HP 4101).
> It doesn't print particularly dark. I use 3M transparency CG3300. That
> probably doesn't matter. After printing, I let the transparency cool and
> then go over the entire image with a black, dry erase marker. I use Expo
> brand. Try to do it with single, overlapping strokes. The solvents in the
> marker will soften the toner image slightly. Don't scrub the marker back
> and forth over the transparency. Let it dry thoroughly (10 minutes), then I
> use folded facial tissue (Kleenex brand) to remove the dry erase. I usually
> make a first couple of swipes to remove the bulk of the excess, then open a
> clean surface and remove the rest. The dry erase sticks in the crevices and
> areas between toner particles, but removes cleanly from the clear areas.
> You can rub pretty hard to remove last little bits that might be stuck
> around thermals or other very fine details. In my experience, colored dry
> erase will not work, as the dyes used in them are not as easily removed.
>
> I will try to upload a picture of a recent board I did for a QFN package.
> Traces on the QFN sub-board are 16 mil. On the main board they are 24 mil,
> and you can see that the letters in my name and date are considerable
> smaller.
>
> John
>
>
>
--
Imagine no possessions
I wonder if you can
No need for greed or hunger
A brotherhood of man
Imagine all the people
Sharing all the world ... John Lennon
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