Homebrew PCBs

I made up a board on a CAD transfer program, and printed it off on a
transparency.  I exposed it to my homebrew UV LED array for 1'30" and
transferred it to a store baught developer.  I agitated it in the developer
at the recommended 10:1 concentration for well over 5 minutes and the light
sensitive coating showed no sign of coming off.  I exposed it again for a
solid 5 minutes, and again put it in the developer with no sign of any
action.  I have left in the back yard now to see if it will finally come
off.  It does look like some milky looking material is slowly coming off,
but this is MUCH longer than I expected.  I am asuming all the positive
boards require the same NaOH solution, so I don't think that's the problem,
but I am not sure.

Any suggestions?

Thanks,
Chris Maness


[Non-text portions of this message have been removed]

Chris Maness wrote:
> I made up a board on a CAD transfer program, and printed it off on a
> transparency.  I exposed it to my homebrew UV LED array for 1'30" and
> transferred it to a store baught developer.  I agitated it in the developer
> at the recommended 10:1 concentration for well over 5 minutes and the light
> sensitive coating showed no sign of coming off.  I exposed it again for a
> solid 5 minutes, and again put it in the developer with no sign of any
> action.  I have left in the back yard now to see if it will finally come
> off.  It does look like some milky looking material is slowly coming off,
> but this is MUCH longer than I expected.  I am asuming all the positive
> boards require the same NaOH solution, so I don't think that's the problem,
> but I am not sure.

Positive resist or negative?

On Fri, Apr 2, 2010 at 5:57 PM, Russell Shaw <rjshaw@...> wrote:

> Chris Maness wrote:
> > I made up a board on a CAD transfer program, and printed it off on a
> > transparency.  I exposed it to my homebrew UV LED array for 1'30" and
> > transferred it to a store baught developer.  I agitated it in the
> developer
> > at the recommended 10:1 concentration for well over 5 minutes and the
> light
> > sensitive coating showed no sign of coming off.  I exposed it again for a
> > solid 5 minutes, and again put it in the developer with no sign of any
> > action.  I have left in the back yard now to see if it will finally come
> > off.  It does look like some milky looking material is slowly coming off,
> > but this is MUCH longer than I expected.  I am asuming all the positive
> > boards require the same NaOH solution, so I don't think that's the
> problem,
> > but I am not sure.
>
> Positive resist or negative?
>

I'm an idiot.  I did not realize that there is a sticker covering the
sensitive side.  However, after developing, my traces look a little on the
thin side.  Maybe my masque was not dark enough, or I over exposed.  I ran
1m30s, using 15 LEDs on a 4x5 perf board.

Regards,
Chris Maness


[Non-text portions of this message have been removed]

Did you peel the protective film off after exposing?  (yes, I still make 
this mistake occasionally myself)

Note: most negative films want a 15 minute "rest" period (in the dark) 
before peeling and developing; the reaction creates some gasses that 
help with the hardening and they need to remain trapped by the film for 
that time.  Check with your board's instructions to see if your film 
needs it.

Chris Maness wrote:
> On Fri, Apr 2, 2010 at 5:57 PM, Russell Shaw <rjshaw@...> wrote:
> 
>> Chris Maness wrote:
>>> I made up a board on a CAD transfer program, and printed it off on a 
>>> transparency.  I exposed it to my homebrew UV LED array for 1'30" and 
>>> transferred it to a store baught developer.  I agitated it in the
>>> developer at the recommended 10:1 concentration for well over 5 minutes
>>> and the light sensitive coating showed no sign of coming off.  I exposed
>>> it again for a solid 5 minutes, and again put it in the developer with no
>>> sign of any action.  I have left in the back yard now to see if it will
>>> finally come off.  It does look like some milky looking material is
>>> slowly coming off, but this is MUCH longer than I expected.  I am asuming
>>> all the positive boards require the same NaOH solution, so I don't think
>>> that's the problem, but I am not sure.
>> Positive resist or negative?
>> 
> 
> I'm an idiot.  I did not realize that there is a sticker covering the 
> sensitive side.  However, after developing, my traces look a little on the 
> thin side.  Maybe my masque was not dark enough, or I over exposed.  I ran 
> 1m30s, using 15 LEDs on a 4x5 perf board.

With the film still on, the traces get thinner due to light-undercutting
travelling through the film under the track.

It was positive film.

Chris

On Fri, Apr 2, 2010 at 7:06 PM, DJ Delorie <dj@...> wrote:

> Did you peel the protective film off after exposing?  (yes, I still make
> this mistake occasionally myself)
>
> Note: most negative films want a 15 minute "rest" period (in the dark)
> before peeling and developing; the reaction creates some gasses that
> help with the hardening and they need to remain trapped by the film for
> that time.  Check with your board's instructions to see if your film
> needs it.
>
>
> ------------------------------------
>
> Be sure to visit the group home and check for new Links, Files, and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>
>


[Non-text portions of this message have been removed]

Well, it sort of worked.  I think my contrast needs to be beefed up on my
masque.  I had them print the transparency at Office Max.  Very good
resolution, but not the contrast I need.  I was going to do it myself on the
ink jet, but they wanted $50 for a small pack of ink jet transparencies
which I think is totally ridiculous.

Thanks,
Chris Maness


[Non-text portions of this message have been removed]

On Fri, Apr 2, 2010 at 10:02 PM, Chris Maness <chris@...> wrote:

> Well, it sort of worked.  I think my contrast needs to be beefed up on my
> masque.  I had them print the transparency at Office Max.  Very good
> resolution, but not the contrast I need.  I was going to do it myself on the
> ink jet, but they wanted $50 for a small pack of ink jet transparencies
> which I think is totally ridiculous.
>
> Thanks,
> Chris Maness
>

Yea!!  It worked.  I used my laser printer at work with standard OH
transparency sheets.  It came out very dark and contrasty.  This time
exposed for 4:30s from 12" (small light source).  It took some time for the
developer to remove the exposed resist (positive board), but it etched very
nicely in CuCl2 and H2O2.  I also had a H2O2 bath to periodically remove
insoluble CuCl from the board while I was etching.  I would like to get a
bubble tank so I don't have to do that, but it worked very well.

I am now ready to drill my board for my movie sound project.  ;o)

Thanks,
Chris Maness
KQ6UP


[Non-text portions of this message have been removed]

> >
> 
> Yea!!  It worked.  I used my laser printer at work with standard OH
> transparency sheets.  It came out very dark and contrasty.  This time
> exposed for 4:30s from 12" (small light source).  It took some time for the
> developer to remove the exposed resist (positive board), but it etched very
> nicely in CuCl2 and H2O2.  I also had a H2O2 bath to periodically remove
> insoluble CuCl from the board while I was etching.  I would like to get a
> bubble tank so I don't have to do that, but it worked very well.
> 
> I am now ready to drill my board for my movie sound project.  ;o)
> 
> Thanks,
> Chris Maness
> KQ6UP
> 
>


You don't even need transparencies. I've used ordinary laser printer paper, a friend of mine has better results using tracing paper and laser printing on that. You have to make sure you print it so the toner side is against the board when you expose, and weight a piece of glass over it to hold the pattern completely flat against the board. Once you figure out the correct exposure time it can produce very consistent results.

Bubble tank is easy, I built one out of acrylic but I've seen people use those narrow rectangular food storage containers with an aquarium air pump and heater. The heat is the most important part.

On 15/04/2010 22:10, James wrote:
>
>
>
> You don't even need transparencies. I've used ordinary laser printer paper, a friend of mine has better results using tracing paper and laser printing on that. You have to make sure you print it so the toner side is against the board when you expose, and weight a piece of glass over it to hold the pattern completely flat against the board. Once you figure out the correct exposure time it can produce very consistent results.
>
> Bubble tank is easy, I built one out of acrylic but I've seen people use those narrow rectangular food storage containers with an aquarium air pump and heater. The heat is the most important part.

When I used a laser printer for transparencies I got good results with 
tracing paper. I have heard of people putting cooking oil onto artwork 
printed on ordinary paper, to make it translucent. I tried it once, and 
it worked, but it was a bit messy.

Leon
-- 
Leon Heller
G1HSM

On Thu, Apr 15, 2010 at 3:09 PM, Leon Heller <leon355@...> wrote:

> On 15/04/2010 22:10, James wrote:
> >
> >
> >
> > You don't even need transparencies. I've used ordinary laser printer
> paper, a friend of mine has better results using tracing paper and laser
> printing on that. You have to make sure you print it so the toner side is
> against the board when you expose, and weight a piece of glass over it to
> hold the pattern completely flat against the board. Once you figure out the
> correct exposure time it can produce very consistent results.
> >
> > Bubble tank is easy, I built one out of acrylic but I've seen people use
> those narrow rectangular food storage containers with an aquarium air pump
> and heater. The heat is the most important part.
>
> When I used a laser printer for transparencies I got good results with
> tracing paper. I have heard of people putting cooking oil onto artwork
> printed on ordinary paper, to make it translucent. I tried it once, and
> it worked, but it was a bit messy.
>
> Leon
> --
> Leon Heller
> G1HSM


I went to my local $.99 store and purchased a cheap picture frame w/ two
pieces of glass.  I used two plastic spring loaded clamps to hold my PCB
sandwich together.  I find those clamps are perfect.  I have heard the
tracing paper trick.  I actually have those OH transparency sheets laying
around because I teach school.  But I am stuck doing one at home I will give
it a try.

Is there a adjustment factor when using tracing sheets instead of
transparency sheets?

Thanks,
Chris Maness
KQ6UP


[Non-text portions of this message have been removed]

> 
> I went to my local $.99 store and purchased a cheap picture frame w/ two
> pieces of glass.  I used two plastic spring loaded clamps to hold my PCB
> sandwich together.  I find those clamps are perfect.  I have heard the
> tracing paper trick.  I actually have those OH transparency sheets laying
> around because I teach school.  But I am stuck doing one at home I will give
> it a try.
> 
> Is there a adjustment factor when using tracing sheets instead of
> transparency sheets?
> 
> Thanks,
> Chris Maness
> KQ6UP
> 
> 
> [Non-text portions of this message have been removed]
>

I found it was hard to get a solid enough print on transparencies.

Best with any method to do a test exposure. Cut a strip of board, put a test pattern on it, then cover most of it and expose for 30 sec, uncover another increment, expose, repeat until you have a strip with a bunch of segments of incrementing exposure time and note the one with the best results.

On 15/04/2010 23:18, Chris Maness wrote:
> On Thu, Apr 15, 2010 at 3:09 PM, Leon Heller<leon355@...>  wrote:
>

>> G1HSM
>
>
> I went to my local $.99 store and purchased a cheap picture frame w/ two
> pieces of glass.  I used two plastic spring loaded clamps to hold my PCB
> sandwich together.  I find those clamps are perfect.  I have heard the
> tracing paper trick.  I actually have those OH transparency sheets laying
> around because I teach school.  But I am stuck doing one at home I will give
> it a try.
>
> Is there a adjustment factor when using tracing sheets instead of
> transparency sheets?

It was a long time ago, but I think it was about the same. It seemed 
quite transparent to UV.

Leon
-- 
Leon Heller
G1HSM

Chris,

Here is a site with a wealth of information that you may find interesting,

http://www.capefearpress.com/puretchpcb.html

There was one reference to this site in a posting about 1 year ago relative to sources of dry film resist.

They are selling a high resolution negative Riston at $10.00 for 2 square feet as a sample size. The price drops by 1/2 if you buy 20 square feet $(45.00). I learned a lot by watching their videos.  In particular, the explanations of the Stouffer step gauge are excellent.

Baxter

--- In Homebrew_PCBs@yahoogroups.com, Chris Maness <chris@...> wrote:

>
> I made up a board on a CAD transfer program, and printed it off on a
> transparency.  I exposed it to my homebrew UV LED array for 1'30" and
> transferred it to a store baught developer.  I agitated it in the developer
> at the recommended 10:1 concentration for well over 5 minutes and the light
> sensitive coating showed no sign of coming off.  I exposed it again for a
> solid 5 minutes, and again put it in the developer with no sign of any
> action.  I have left in the back yard now to see if it will finally come
> off.  It does look like some milky looking material is slowly coming off,
> but this is MUCH longer than I expected.  I am asuming all the positive
> boards require the same NaOH solution, so I don't think that's the problem,
> but I am not sure.
> 
> Any suggestions?
> 
> Thanks,
> Chris Maness
> 
> 
> [Non-text portions of this message have been removed]
>