Homebrew_PCBs

Just attempted my first photofabrication and it failed at the
developing stage. Within 30 seconds of immersion the board was
completely devoid of resist...

Here's what I did (all M.G. Chemicals supplies)

-Printed out my circuit onto a transparency (IBM Laser
Transparencies, 24L5041) using a Samsung ML-1210 laser printer.
-Poured two litres of hot tap water into a tray.
-Poured 200ml of Developer into the tray of water (10:1 as per
instructions).
-Set up the UV light using the supplied stands (about 5-6" high).
-Placed the sensitized board blue side up. Positioned my
transparency (ink side toward the board) and placed the plexi weight
on top.
- Waited 5 minutes then turned out the light (actually probably more
like 5.5 minutes).
- Immediately put the board into the developer solution. I used the
supplies foam brush to agitate the water (didn't come within 1/2" of
the board itself, just slowly waved it back and forth at the
surface). Solution was about 95-100F by this time.
- About 5 seconds in I could see my traces through the clouds of
black ink. As the black ink cleared I could see traces starting to
fade out too. This is about 15 seconds into the process. I realized
the board was already toast so I waited to see how long it would
take to completely erase the resist - was about 30 seconds.

The instructions say it should take about 2 minutes to develop the
board. This was a LOT faster... I'm thinking perhaps the developer
was too strong? What about temperature? Should I just use developer
at room temperature instead - give myself more "OOOOP" time?

I guess its also possible that this laser's toner isn't UV opaque
but, the speed at which the board completely blanked and the fact
that I saw traces - even for a short time, makes me think its a
developer problem.

What do you guru's think?

P.S. Traces were mostly 0.012 with power/ground at 0.02. Pads 0.07.

Also, I expected this first board to be a total flop. Actually, I
expect my first 5-10 to be varying degrees of failures :D This seems
more of an artform than a science!

--- In Homebrew_PCBs@yahoogroups.com, "ghidera2000
<ghidera2000@y...>" <ghidera2000@y...> wrote:

> Just attempted my first photofabrication and it failed at the
> developing stage. Within 30 seconds of immersion the board was
> completely devoid of resist...
>
> Here's what I did (all M.G. Chemicals supplies)
>

The most likely cause of the problem you describe is overexposure.
For fix problem one you need to determine minimum exposure time. You
do this by taking a blank board with photoresist and expose it for
different lengths of time using a sliding cover. You must let the
light pass through the transparency material to compensate for any
absorption of light energy. Expose the blank board in steps of say 30
seconds for total of 5 minutes, and leave one section completely
unexposed. I use a piece of black plastic and slide it across.

Prepare your developer and develop the board. You then get a good idea
on how long the resist must be exposed for the developer to dissolve
away the resist. If the section exposed for 30 second completely
dissolves in the developer (assuming positive resist) then your
exposure times are obviously much shorter than a few minutes. Exposure
time measurement is essential for anyone first starting out with a
particular photoresist and exposure unit.


ghidera2000 wrote:

> Just attempted my first photofabrication and it failed at the
> developing stage. Within 30 seconds of immersion the board was
> completely devoid of resist...
>
> Here's what I did (all M.G. Chemicals supplies)
>
> -Printed out my circuit onto a transparency (IBM Laser
> Transparencies, 24L5041) using a Samsung ML-1210 laser printer.
> -Poured two litres of hot tap water into a tray.
> -Poured 200ml of Developer into the tray of water (10:1 as per
> instructions).
> -Set up the UV light using the supplied stands (about 5-6" high).
> -Placed the sensitized board blue side up. Positioned my
> transparency (ink side toward the board) and placed the plexi weight
> on top.
> - Waited 5 minutes then turned out the light (actually probably more
> like 5.5 minutes).
> - Immediately put the board into the developer solution. I used the
> supplies foam brush to agitate the water (didn't come within 1/2" of
> the board itself, just slowly waved it back and forth at the
> surface). Solution was about 95-100F by this time.
> - About 5 seconds in I could see my traces through the clouds of
> black ink. As the black ink cleared I could see traces starting to
> fade out too. This is about 15 seconds into the process. I realized
> the board was already toast so I waited to see how long it would
> take to completely erase the resist - was about 30 seconds.
>
> The instructions say it should take about 2 minutes to develop the
> board. This was a LOT faster... I'm thinking perhaps the developer
> was too strong? What about temperature? Should I just use developer
> at room temperature instead - give myself more "OOOOP" time?
>
> I guess its also possible that this laser's toner isn't UV opaque
> but, the speed at which the board completely blanked and the fact
> that I saw traces - even for a short time, makes me think its a
> developer problem.
>
> What do you guru's think?
>
>
>
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
>
> To unsubscribe from this group, send an email to:
> Homebrew_PCBs-unsubscribe@yahoogroups.com
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>

Good idea! I'll try that with another (small) board. Expose a strip
at one end for 30 seconds then try the developer. If the whole board
is stripped clean then I know its developer. If not, I'll keep
trying to see how things go.

Come to think of it, the light did come with a plastic cover for the
bulb. The fixture itself didn't work properly so I put the light
into a small fixture I already had and used that. No plastic cover
for the light. Perhaps it was filtering some of the UV and the
manufacturer factored in the weaker UV source... Guess I'll find out
pretty quick.

Thanks much for the fast response. I can start experimenting
tonight :D As with any new toy, its hard sitting around and waiting.


--- In Homebrew_PCBs@yahoogroups.com, Adam Seychell
<adam_seychell@y...> wrote:

> The most likely cause of the problem you describe is overexposure.
> For fix problem one you need to determine minimum exposure time.

You

> do this by taking a blank board with photoresist and expose it for
> different lengths of time using a sliding cover. You must let the
> light pass through the transparency material to compensate for any
> absorption of light energy. Expose the blank board in steps of say

30

> seconds for total of 5 minutes, and leave one section completely
> unexposed. I use a piece of black plastic and slide it across.
>
> Prepare your developer and develop the board. You then get a good

idea

> on how long the resist must be exposed for the developer to

dissolve

> away the resist. If the section exposed for 30 second completely
> dissolves in the developer (assuming positive resist) then your
> exposure times are obviously much shorter than a few minutes.

Exposure

> time measurement is essential for anyone first starting out with a
> particular photoresist and exposure unit.
>
>

ghidera2000 wrote:

> Just attempted my first photofabrication and it failed at the
> developing stage. Within 30 seconds of immersion the board was
> completely devoid of resist...
>
> Here's what I did (all M.G. Chemicals supplies)
>
> -Printed out my circuit onto a transparency (IBM Laser
> Transparencies, 24L5041) using a Samsung ML-1210 laser printer.
> -Poured two litres of hot tap water into a tray.
> -Poured 200ml of Developer into the tray of water (10:1 as per
> instructions).

The problem is you used *hot* water. Make sure it's warmer than 20deg
or it'll be slow. Make sure it's less than 30deg or it'll peel.
25deg is ideal.

> -Set up the UV light using the supplied stands (about 5-6" high).
> -Placed the sensitized board blue side up. Positioned my
> transparency (ink side toward the board) and placed the plexi weight
> on top.
> - Waited 5 minutes then turned out the light (actually probably more
> like 5.5 minutes).

Laser printouts can be pretty crappy. Can you see light thru the
larger black areas? Do some exposure test strips in 30s increments
starting from 1min. Consider getting a decent inkjet.

> - Immediately put the board into the developer solution. I used the
> supplies foam brush to agitate the water (didn't come within 1/2" of
> the board itself, just slowly waved it back and forth at the
> surface). Solution was about 95-100F by this time.
> - About 5 seconds in I could see my traces through the clouds of
> black ink. As the black ink cleared I could see traces starting to
> fade out too. This is about 15 seconds into the process. I realized
> the board was already toast so I waited to see how long it would
> take to completely erase the resist - was about 30 seconds.
>
> The instructions say it should take about 2 minutes to develop the
> board. This was a LOT faster... I'm thinking perhaps the developer
> was too strong? What about temperature? Should I just use developer
> at room temperature instead - give myself more "OOOOP" time?
>
> I guess its also possible that this laser's toner isn't UV opaque
> but, the speed at which the board completely blanked and the fact
> that I saw traces - even for a short time, makes me think its a
> developer problem.

The problem could be due to over exposure or developer is too strong.
Laser transparencies ARE perfect and I have been using them for MANY
years.
Exposure and developer strength is what counts.
Here in Texas temperature are moderate so I have no experience of
anything under 75F (about 24C)
I use GE 500W light bulb at 6" from the film and expose for 70 Seconds.
Developing in grocery store Lye (caustic soda) with the strength I have
takes about 45 second and I can do 5 mil line all day long....
The transparency materials important and I've tried several. 3M CG3300
is goo for 8-10 mil Apollo CG7060 is good for 5 mil every day.
I have a HP LJ1100 and set it to 600dpi economy setting turned off.
Yes I can see through the big patches, but if you are correct with
exposure and developing it does NOT matter.
Advice given from many years of home made PCB's...
Inkjet printers are fine, but I think it is wrong to say Laser jets are
bad, when the real issue if control of exposure and developing.
That's my 2 cents worth....
Hans W


Russell wrote:

> ghidera2000 wrote:
> > Just attempted my first photofabrication and it failed at the
> > developing stage. Within 30 seconds of immersion the board was
> > completely devoid of resist...
> >
> > Here's what I did (all M.G. Chemicals supplies)
> >
> > -Printed out my circuit onto a transparency (IBM Laser
> > Transparencies, 24L5041) using a Samsung ML-1210 laser printer.
> > -Poured two litres of hot tap water into a tray.
> > -Poured 200ml of Developer into the tray of water (10:1 as per
> > instructions).
>
> The problem is you used *hot* water. Make sure it's warmer than 20deg
> or it'll be slow. Make sure it's less than 30deg or it'll peel.
> 25deg is ideal.
>
> > -Set up the UV light using the supplied stands (about 5-6" high).
> > -Placed the sensitized board blue side up. Positioned my
> > transparency (ink side toward the board) and placed the plexi weight
>
> > on top.
> > - Waited 5 minutes then turned out the light (actually probably more
>
> > like 5.5 minutes).
>
> Laser printouts can be pretty crappy. Can you see light thru the
> larger black areas? Do some exposure test strips in 30s increments
> starting from 1min. Consider getting a decent inkjet.
>
> > - Immediately put the board into the developer solution. I used the
> > supplies foam brush to agitate the water (didn't come within 1/2" of
>
> > the board itself, just slowly waved it back and forth at the
> > surface). Solution was about 95-100F by this time.
> > - About 5 seconds in I could see my traces through the clouds of
> > black ink. As the black ink cleared I could see traces starting to
> > fade out too. This is about 15 seconds into the process. I realized
> > the board was already toast so I waited to see how long it would
> > take to completely erase the resist - was about 30 seconds.
> >
> > The instructions say it should take about 2 minutes to develop the
> > board. This was a LOT faster... I'm thinking perhaps the developer
> > was too strong? What about temperature? Should I just use developer
> > at room temperature instead - give myself more "OOOOP" time?
> >
> > I guess its also possible that this laser's toner isn't UV opaque
> > but, the speed at which the board completely blanked and the fact
> > that I saw traces - even for a short time, makes me think its a
> > developer problem.
>
>
>
>
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>
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>
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[Non-text portions of this message have been removed]

I actually have an inkjet already. I emailed MG Chemicals and asked
about using inkjets instead of laser. They replied and said that
inkjet inks aren't UV opaque and don't work well for the process.
So, since I was already strongly considering buying another laser, I
said what the hell and picked this one up.(I print so infrequently
that my inkjet cartridges keep drying out on me so toner/developer
is cheaper in the long run).

And no, I couldn't see light through the larger areas but, my
largest areas are the power traces and pads. I did do a plain paper
print with a large black area. Coverage was actually quite decent
considering lasers aren't all that good at it. Way better than my
old Epson Action II laser though.

--- In Homebrew_PCBs@yahoogroups.com, Hans Wedemeyer <hans@c...>
wrote:

> The problem could be due to over exposure or developer is too

strong.

> Laser transparencies ARE perfect and I have been using them for

MANY

> years.
> Exposure and developer strength is what counts.
> Here in Texas temperature are moderate so I have no experience of
> anything under 75F (about 24C)
> I use GE 500W light bulb at 6" from the film and expose for 70

Seconds.

> Developing in grocery store Lye (caustic soda) with the strength I

have

> takes about 45 second and I can do 5 mil line all day long....
> The transparency materials important and I've tried several. 3M

CG3300

> is goo for 8-10 mil Apollo CG7060 is good for 5 mil every day.
> I have a HP LJ1100 and set it to 600dpi economy setting turned off.
> Yes I can see through the big patches, but if you are correct with
> exposure and developing it does NOT matter.
> Advice given from many years of home made PCB's...
> Inkjet printers are fine, but I think it is wrong to say Laser

jets are

> bad, when the real issue if control of exposure and developing.
> That's my 2 cents worth....
> Hans W
>
>

removed]

ghidera2000 wrote:

> I actually have an inkjet already. I emailed MG Chemicals and asked
> about using inkjets instead of laser. They replied and said that
> inkjet inks aren't UV opaque and don't work well for the process...

Nothing could be further from the truth. Inkjet inks are excellent at
blocking UV, but can be completely transparent to infrared. If i want
a cheap IR filter, i just print a black area onto transparency with
an epson stylus 400 colour. Note that only a few inkjet printers give
good results printing onto transparency.

Hello ghidera2000,

31. December 2002, 03:09:00, you wrote:

ggyc> -Poured two litres of hot tap water into a tray.
===

And I replied:

As underlined! The developer temperature should be around 25degC. At
higher temperatures the developer will strip whole board.

--
Best Regards,
Zoran
mailto:zasto@...

ghidera2000 wrote:

> I actually have an inkjet already. I emailed MG Chemicals and asked
> about using inkjets instead of laser. They replied and said that
> inkjet inks aren't UV opaque and don't work well for the process.
> So, since I was already strongly considering buying another laser, I
> said what the hell and picked this one up.(I print so infrequently
> that my inkjet cartridges keep drying out on me so toner/developer
> is cheaper in the long run).
>

Inkjet black images on transparency film is extremely opaque to UV-A radiation.
In fact I find it almost impossible to do overexposure with my Epson Stylus and
Epson transparencies. I do not have a UV photometer to give you actual
absorption figures but its definitely more than adequate. The Epson ink is dye
based (soluble organic colorants) and actually looks deep red through bright
light. HP & Lexmark inks are pigment based (carbon black dispersion) and are
also extremely opaque to UV. The problems arising with some inkjet printers used
to create PCB photomasks is micro pinholes, banding and ink splattering. If you
find good inkjet system that does not have these problems then you are set.

I decided to let the developer cool to room temperature before
starting the timing experiments. 25C is about 77F so my 95-100F
developer would definately have been way too warm. I'll find out
this morning either way.


--- In Homebrew_PCBs@yahoogroups.com, "Zoran A. Scepanovic"
<zasto@y...> wrote:

> Hello ghidera2000,
>
> 31. December 2002, 03:09:00, you wrote:
>
> ggyc> -Poured two litres of hot tap water into a tray.
> ===
>
> And I replied:
>
> As underlined! The developer temperature should be around

25degC. At

> higher temperatures the developer will strip whole board.
>
> --
> Best Regards,
> Zoran
> mailto:zasto@y...

And Zoran wins the prize! With the developer down to 69F I got a
(seemingly) perfect result with a 5 minute exposure time. Its in the
sparger now (no heater, I want to have LOTS of "Hmmm,
wassitluklikenow" time).

This is fun!

Thanks greatly to all that have replied. Tons of food for thought!

--- In Homebrew_PCBs@yahoogroups.com, "Zoran A. Scepanovic"
<zasto@y...> wrote:

> Hello ghidera2000,
>
> 31. December 2002, 03:09:00, you wrote:
>
> ggyc> -Poured two litres of hot tap water into a tray.
> ===
>
> And I replied:
>
> As underlined! The developer temperature should be around

25degC. At

> higher temperatures the developer will strip whole board.
>
> --
> Best Regards,
> Zoran
> mailto:zasto@y...

I had the same problem when I first started out, your water shouldn't be hot or the developer will peel right off. If I remember correctly it should never go beyond 85 degrees F.
Good Luck!
Randy Knutson
"ghidera2000 <ghidera2000@...>" <ghidera2000@...> wrote:Just attempted my first photofabrication and it failed at the
developing stage. Within 30 seconds of immersion the board was
completely devoid of resist...

Here's what I did (all M.G. Chemicals supplies)

-Printed out my circuit onto a transparency (IBM Laser
Transparencies, 24L5041) using a Samsung ML-1210 laser printer.
-Poured two litres of hot tap water into a tray.
-Poured 200ml of Developer into the tray of water (10:1 as per
instructions).
-Set up the UV light using the supplied stands (about 5-6" high).
-Placed the sensitized board blue side up. Positioned my
transparency (ink side toward the board) and placed the plexi weight
on top.
- Waited 5 minutes then turned out the light (actually probably more
like 5.5 minutes).
- Immediately put the board into the developer solution. I used the
supplies foam brush to agitate the water (didn't come within 1/2" of
the board itself, just slowly waved it back and forth at the
surface). Solution was about 95-100F by this time.
- About 5 seconds in I could see my traces through the clouds of
black ink. As the black ink cleared I could see traces starting to
fade out too. This is about 15 seconds into the process. I realized
the board was already toast so I waited to see how long it would
take to completely erase the resist - was about 30 seconds.

The instructions say it should take about 2 minutes to develop the
board. This was a LOT faster... I'm thinking perhaps the developer
was too strong? What about temperature? Should I just use developer
at room temperature instead - give myself more "OOOOP" time?

I guess its also possible that this laser's toner isn't UV opaque
but, the speed at which the board completely blanked and the fact
that I saw traces - even for a short time, makes me think its a
developer problem.

What do you guru's think?



Be sure to visit the group home and check for new Bookmarks and files:
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