Hi,
We used drafting film for direct imaging UV sensitive PCB's with good results. It gave the best results for artwork plotted done by our old HP pen plotters.
Unfortunately the pens were too thick for today's boards that require 8mil or 5mil track widths to suit modern semiconductors and connectors :-(
It also took a LONG time to plot out boards with large filled areas (especially with thin pens, and it's probably one of the reasons why cross-hatch fills were invented :-)
In case anyone is wondering, drafting film is generally a polymer film (not a paper, so it does melt!) that has silica powder added to the plastic mix (double side matt finish), or has silica powder pressed into one side (single matt). The idea is to print on the matt side where the silica absorbs the ink, and as others suggest, is the side that has to be in contact with the PCB resist during exposure.
BTW, silica in drafting film is really good at blunting scissors!
More recently I experimented with old Tektronix/Xerox Phaser printers (colour wax printers) directly onto adhesive backed copper foil.
This worked quite well, although the adhesive starts to soften if you leave it in hot etchant too long.
I then stick an adhesive polymer film over the top to hold the copper in place, and remove the foil's own backing to expose the copper's adhesive.
Then I stick it all down on a blank board, and finally peel the top film off (being careful to leave the copper behind on the substrate).
The process need refinement, but has produced a couple of prototype flex circuits to date. Unfortunately the foil's adhesive isn't designed for high temperatures so solder quickly! Some future experimentation with epoxy glues is in order.
Cheers,
Mark
Bionics Institute
Melbourne, Australia
-----Original Message-----
From:
Homebrew_PCBs@yahoogroups.com [mailto:
Homebrew_PCBs@yahoogroups.com] On Behalf Of Mitch Davis
Sent: Wednesday, 22 May 2013 11:52 AM
To:
Homebrew_PCBs@yahoogroups.comSubject: Re: [Homebrew_PCBs] Re: printer
On Wed, May 22, 2013 at 3:30 AM, Phil@Yahoo <yahoo@...> wrote:
>
> do more than six feet. Now that I'm almost 60 (yikes!) well, you don't want to know.
Switch to metric. You can stand a lot closer, your feet stay drier,
and you can keep your vanity "score" the same :-)
> I make double sided PCBs with plated-thru holes
I'd be very interested to read more about that, do you have a blog
page or web page showing what you do? I'm especially interested in
how you get registration between the two sides right.
> a side because of the distortion caused by printing laser transparencies.
Have you tried printing on drafting paper? Drafting paper is
transparent to UV, and I've had good success with it. I just bought a
pad at the stationery shop. And just as for transparency, the
printing should go against the board.
You can read about my method with drafting paper here:
http://capnstech.blogspot.com/2011/05/playpause-making-pcbs-at-home.html
All the best!
Mitch.
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