Homebrew PCBs

Many of the of "professional" lab/prototyping PCB exposure units seem to 
be fitted with a vacuum assisted frame. I'm wondering if vacuum has much 
advantage over conventional sandwiched rubber foam and glass.

These commercial exposure units are built using fluorescent lamps at 
point blank range. i.e light goes all directions. I could not think of 
better way to promote light undercut. I'm thinking the vacuum on the 
more expensive units is put there to help combat non-collimated light.

If the light source is reasonably collimated then does vacuum provide 
much advantage ?
Photoresist is about 50um thick. So I guess ideally the photomask should 
sit flat on the PCB with a air gap no greater than some fraction of the 
resist thickness.

Vacuum allows you to expose both sides at once, foam does not.

ST

On Fri, Mar 7, 2008 at 12:02 PM, Adam Seychell <a_seychell@...> wrote:
> Many of the of "professional" lab/prototyping PCB exposure units seem to
> be fitted with a vacuum assisted frame. I'm wondering if vacuum has much
> advantage over conventional sandwiched rubber foam and glass.
>
> These commercial exposure units are built using fluorescent lamps at
> point blank range. i.e light goes all directions. I could not think of
> better way to promote light undercut. I'm thinking the vacuum on the
> more expensive units is put there to help combat non-collimated light.
>
> If the light source is reasonably collimated then does vacuum provide
> much advantage ?
> Photoresist is about 50um thick. So I guess ideally the photomask should
> sit flat on the PCB with a air gap no greater than some fraction of the
> resist thickness.
>

I'm modifying an Epson Picturemate 200 for direct toner transfer, and 
I have a couple of questions about the ink cartridge that I hope 
someone can answer. The cartridge mounts at the bottom of the printer 
(not on the print head) and seems to have 5 ports. One is for each 
color, and the second goes to a grey tubing. My questions:

1 - Is the grey tubing used to pressurize the cartridge? If so, does 
anyone know the working pressure. I can measure it, if necessary, but 
I'd like some more information before I start mucking with it.

2 - There are 5(?) contacts on the side of the cartridge. I assume 
they detect the presence of the cartridge and the levels of each 
color. Does anyone know what signals are expected from the cartridge 
and how to "cheat" it?

I would like to remove the cartridge and feed the printer head from 
an external reservoir. The print head has 4 sets of 90 piezo jets, 
but I would only need one set at a time.

Thanks for any help or information sources.

Mark

Whoops - there are 7 contact.

At 02:57 PM 3/8/2008, you wrote:

>I'm modifying an Epson Picturemate 200 for direct toner transfer, and
>I have a couple of questions about the ink cartridge that I hope
>someone can answer. The cartridge mounts at the bottom of the printer
>(not on the print head) and seems to have 5 ports. One is for each
>color, and the second goes to a grey tubing. My questions:
>
>1 - Is the grey tubing used to pressurize the cartridge? If so, does
>anyone know the working pressure. I can measure it, if necessary, but
>I'd like some more information before I start mucking with it.
>
>2 - There are 5(?) contacts on the side of the cartridge. I assume
>they detect the presence of the cartridge and the levels of each
>color. Does anyone know what signals are expected from the cartridge
>and how to "cheat" it?
>
>I would like to remove the cartridge and feed the printer head from
>an external reservoir. The print head has 4 sets of 90 piezo jets,
>but I would only need one set at a time.
>
>Thanks for any help or information sources.
>
>Mark
>
>
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBs
>Yahoo! Groups Links
>
>
>

On 8 Mar 2008, at 20:00, Mark Lerman wrote:

> modifying an Epson Picturemate 200 for direct toner transfer,

Very hard to do with an inkjet printer, I'd imagine.

-- 

Cheers

Derryck

It's been done before - see the links for this group. I think it will provide the best resolution short of photographic techniques. From what I now have found out, the printer doesn't read the cartridge, rather it counts the droplets and calculates the ink remaining. There are chip resetters, but I'm not sure they will work with these cartridges. More research is necessary.

Mark

-----Original Message-----

>From: Derryck Croker <derryck@...>
>Sent: Mar 9, 2008 7:52 AM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: Re: [Homebrew_PCBs] Epson Cartridge Question
>
>
>On 8 Mar 2008, at 20:00, Mark Lerman wrote:
>
>> modifying an Epson Picturemate 200 for direct toner transfer,
>
>Very hard to do with an inkjet printer, I'd imagine.
>
>-- 
>
>Cheers
>
>Derryck
>
>
>
>
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBs 
>Yahoo! Groups Links
>
>
>

It is important to use the correct terms, I'm not trying to be
retentive. That is an inkjet and so uses ink, not toner.

I don't know if that's the best printer to modify for direct inkjet
resist printing. Sounds fiddly to add external ink feed.

Steve Greenfield

--- In Homebrew_PCBs@...m, Mark Lerman <mlerman@...> wrote:

>
> I'm modifying an Epson Picturemate 200 for direct toner transfer, and 
> I have a couple of questions about the ink cartridge that I hope 
> someone can answer. The cartridge mounts at the bottom of the printer 
> (not on the print head) and seems to have 5 ports. One is for each 
> color, and the second goes to a grey tubing. My questions:
> 
> 1 - Is the grey tubing used to pressurize the cartridge? If so, does 
> anyone know the working pressure. I can measure it, if necessary, but 
> I'd like some more information before I start mucking with it.
> 
> 2 - There are 5(?) contacts on the side of the cartridge. I assume 
> they detect the presence of the cartridge and the levels of each 
> color. Does anyone know what signals are expected from the cartridge 
> and how to "cheat" it?
> 
> I would like to remove the cartridge and feed the printer head from 
> an external reservoir. The print head has 4 sets of 90 piezo jets, 
> but I would only need one set at a time.
> 
> Thanks for any help or information sources.
> 
> Mark
>

I had too many problems with direct resist printing on the Epson 
PM200 - the paper feed motor covered part of the (new) rear entrance 
for the pcb, and the external cartridge is cumbersome to implement. 
Has anyone used the CD/DVD printer in the Epson Stylus series to 
apply resist (ink) to the board directly? I realize that the board 
size would be limited, but I am mainly interest in making small boards anyway.

Mark

I have a stylus photo R280 I've been experimenting with, but even at
"ultimate photo quality" the dots don't line up as well as with my
laser printer.  I haven't tried a pcb in the dvd tray yet, though.
I'm not sure how I'd cut it into a circle either ;-)

I was thinking of using a cd with a square cutout for the pcb.  I 
thought that inkjets, especially ones for photos had a much higher 
resolution than laser printers.

Mark

11 04:50 PM 3/10/2008, you wrote:

>I have a stylus photo R280 I've been experimenting with, but even at
>"ultimate photo quality" the dots don't line up as well as with my
>laser printer.  I haven't tried a pcb in the dvd tray yet, though.
>I'm not sure how I'd cut it into a circle either ;-)
>
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBs
>Yahoo! Groups Links
>
>
>

There is where what seems right may not be.

Inkjet printers specifically randomize placement (it is called
"dithering") of the ink dots a bit to hide the fact that it is
printing in rigid, straight lines.

The higher the DPI you print with, the more leeway it has to randomize
the dots. So it may in fact give you better results to use something
like 720dpi, rather than 2880 or some other ultra super photo
smoothing. Rather than set it at super ultra photo printing, find a
setting that says it is for business graphics or DTP. Those should be
optimized for sharp edges of vector graphics.

What you really need is a RIP, software that gives you much more
control over the printer. I didn't get printer drivers for my Amiga
and had to buy a 3rd party package of drivers, but the upside was that
I had ultimate control over everything. I could use ordered dithering
or noise (randomized) dithering to make better photos, or use other
settings to optimize sharp edges on vector graphics.

There were two such printer driver packages, Turboprint and Studio
Print Pro II. Studio Print Pro II is long gone, but the gentleman who
wrote Turboprint has ported it to Linux.

http://www.turboprint.de/english.html

There is a demo, I think it prints half the image.

What you need is to be able to shut "dithering" off.

Steve Greenfield

--- In Homebrew_PCBs@yahoogroups.com, DJ Delorie <dj@...> wrote:

>
> 
> I have a stylus photo R280 I've been experimenting with, but even at
> "ultimate photo quality" the dots don't line up as well as with my
> laser printer.  I haven't tried a pcb in the dvd tray yet, though.
> I'm not sure how I'd cut it into a circle either ;-)
>

Mark Lerman <mlerman@...> writes:
> I thought that inkjets, especially ones for photos had a much higher
> resolution than laser printers.

They do.  However, *accuracy* is as important as resolution, so if you
get a high-res printer that can't position an ink dot within 10 mil,
it's not going to be useful for PCB artwork.  Useful for photos,
because the key there is tight dithering so you don't notice the
individual pixels anyway.

If my laser jet were "perfect" I could do 1.3 mil traces.  It's not
the resolution that's the limiting factor, it's how accurately it can
place the toner/ink to realize those pixels.

Well, the printer was "free" (with the purchase of a camera, which I
needed anyway) so I didn't get to choose one with Linux support.
Maybe I'll reverse engineer it so I can control every dot; then I can
overlay the various pigments also.

DJ Delorie wrote:
> I have a stylus photo R280 I've been experimenting with, but even at
> "ultimate photo quality" the dots don't line up as well as with my
> laser printer.  I haven't tried a pcb in the dvd tray yet, though.
> I'm not sure how I'd cut it into a circle either ;-)
> 

There is a physical limit on how precise the location of inkjet drop can 
be placed on the print media. No matter how you configure the driver the 
ink will not go exactly where it should. Printing in photo modes can 
blend colours if you don't have a photo black ink cartridge. This 
blending only further compromises line edge straightness.

It would be really nice if printer manufactures gave the user control 
over the print head speed so ink droplets were placed down more 
precisely. I bet if there were a bigger market for photomask generation 
then printer manufactures would do exactly that.