Homebrew_PCBs

Hello,

This is a plea for help!
I am on my 5th trial with this and while each trial improves somewhat
in end quality, and certainly in the process, (no longer spilling
solvent all over the basement), I still have yet to produce a board
that I thought could be etched.

The traces are very weak to washed out to non existant. At first I
thought I was under exposing now I suspect I am over exposing or just
not getting a good build up of the resist on the board to start with.

I am looking for someone familiar with this method to bounce a few
emails with so that I can get it right.

At this point I am:
In a 60watt bug light environment (Problem?)
Coating the boards with makeup swab rather then spraying, much nicer
coat and no smears, nice and shiny, dust free mostly.

Drying over night in a sealed shoebox, inside another box

Using tracing paper as negative nice black laser print (Reported to
work in many places)

Exposing with a 250watt photoflood for various times and developing
following supplier instructions with the recommended developer.

Exposure times have been, 22, 10, 5 with a couple of retrials in
between, no, luck. Any help would be greatly appreciated.

Thanks,
Eric

Does Datak mention anything about using a "sunlamp"...something with
some UV spectrum in it? That's what I used in a silk screen method
with photo-emulsion and tracing-paper/toner mask. About 10 minutes
exposure at a distance of about 20 inches or so (depends on how new
the sunlamp is)

Hope this helps,

Bob

--- In Homebrew_PCBs@yahoogroups.com, "ednspace" <ed@c...> wrote:
> Hello,
>
> This is a plea for help!
> I am on my 5th trial with this and while each trial improves
somewhat
> in end quality, and certainly in the process, (no longer spilling
> solvent all over the basement), I still have yet to produce a board
> that I thought could be etched.
>
> The traces are very weak to washed out to non existant. At first I
> thought I was under exposing now I suspect I am over exposing or
just
> not getting a good build up of the resist on the board to start
with.
>
> I am looking for someone familiar with this method to bounce a few
> emails with so that I can get it right.
>
> At this point I am:
> In a 60watt bug light environment (Problem?)
> Coating the boards with makeup swab rather then spraying, much nicer
> coat and no smears, nice and shiny, dust free mostly.
>
> Drying over night in a sealed shoebox, inside another box
>
> Using tracing paper as negative nice black laser print (Reported to
> work in many places)
>
> Exposing with a 250watt photoflood for various times and developing
> following supplier instructions with the recommended developer.
>
> Exposure times have been, 22, 10, 5 with a couple of retrials in
> between, no, luck. Any help would be greatly appreciated.
>
> Thanks,
> Eric

In article <boqubv+j70l@...>,
ednspace <ed@...> wrote:

> At this point I am:
> In a 60watt bug light environment (Problem?)

I have to say I haven't used this particular product but when I was using
some spray-on resist it had to be done in a "darkroom". Only illumination
was a 15W bulb in an photographic "safelight".

First attempts failed because there was some light leakage into the shed
were I was doing it. Repeated again at night and I was successful.

Stuart

--
__ __ __ __ __ ___ _____________________________________________
|__||__)/ __/ \|\ ||_ | /
| || \\__/\__/| \||__ | /...Internet access for all Acorn RISC machines
___________________________/ stuartwinsor@...

101 uses for a Pentium: No2 - A greenhouse heater.

Many years ago I made a bunch of boards using Datak Negative resist,
sprayed it on with a pump sprayer. Do you mean you paint it on with
those very soft fine foam makeup sponges?

Get a red bulb rather than the yellow bug light. You don't need a very
bright bulb ;') if you let your eyes become dark adjusted. I think I
used a 15 or 25W when I was doing this.

Dry them in a bigger box. A small box will get full of fumes of the
solvents and may never let the coating truly dry out. You might even
put it in the shoebox but then set that in a warm oven. Run the oven
up to about 150F, then set the box inside and shut the oven off and
leave it overnight with the oven door shut. Careful if you are using a
gas oven! I don't know if the fumes are flammable, although there
shouldn't be much.

I used a plant grow floodlamp. They specifically have some UV in them,
where a normal floodlamp is optimized for visible light. Especially if
it is not even a quartz halogen flood, normal floodlamps put out
barely any UV. And quartz halogen lights have filters to block the UV.

I've had this goofy idea I've never tested, using a xenon strobe tube
to expose boards. The idea: a camera flash (xenon strobe) has a filter
over it, not just to balance the light but also to block the UV it
gives off. So if you had a largeish unfiltered strobe, perhaps a
specific number of flashes would properly expose a board. Test it,
find the range over which it works, and hit the middle. As the bulb
ages you may find you need to fire off a few more flashes.

Anyway, that was my goofy idea. I have no idea of that would take an
inordinate number of flashes, as that would be the real test of
whether or not it was worth it.

Steve Greenfield

--- In Homebrew_PCBs@yahoogroups.com, "ednspace" <ed@c...> wrote:
> Hello,
>
> This is a plea for help!
> I am on my 5th trial with this and while each trial improves somewhat
> in end quality, and certainly in the process, (no longer spilling
> solvent all over the basement), I still have yet to produce a board
> that I thought could be etched.
>
> The traces are very weak to washed out to non existant. At first I
> thought I was under exposing now I suspect I am over exposing or just
> not getting a good build up of the resist on the board to start with.
>
> I am looking for someone familiar with this method to bounce a few
> emails with so that I can get it right.
>
> At this point I am:
> In a 60watt bug light environment (Problem?)
> Coating the boards with makeup swab rather then spraying, much nicer
> coat and no smears, nice and shiny, dust free mostly.
>
> Drying over night in a sealed shoebox, inside another box
>
> Using tracing paper as negative nice black laser print (Reported to
> work in many places)
>
> Exposing with a 250watt photoflood for various times and developing
> following supplier instructions with the recommended developer.
>
> Exposure times have been, 22, 10, 5 with a couple of retrials in
> between, no, luck. Any help would be greatly appreciated.
>
> Thanks,
> Eric

--- In Homebrew_PCBs@yahoogroups.com, "Bob" <spoothammer@h...> wrote:

>
> Does Datak mention anything about using a "sunlamp"...something

with

> some UV spectrum in it?

Thanks for the reply Bob,

Could be part of the problem, I started with a standard sort of Grow-
lite by GE but did not know how much if any UV was in it, so switched
to the Photoflood bulb.

I am basing this switch on a web page where the person has made many
boards with one using KPR, which is supposed to be very similar. I
don't really know how much UV the bulb I have is putting out though.
I will dig around a bit more. So far both lights are producing very
similar results.

I may try another negative, right now I have very little black in
mine because the circuit is sitting in a ground plane, traces only
slightly seperated. Possibly I can tell whats going on with wider
space between light and dark areas of the negative.

Again thanks for the reply,

ED

--- In Homebrew_PCBs@yahoogroups.com, "ednspace" <ed@c...> wrote:

> --- In Homebrew_PCBs@yahoogroups.com, "Bob" <spoothammer@h...> wrote:
> >
> > Does Datak mention anything about using a "sunlamp"...something
> with
> > some UV spectrum in it?
>
> Thanks for the reply Bob,
>
> Could be part of the problem, I started with a standard sort of Grow-
> lite by GE but did not know how much if any UV was in it, so switched
> to the Photoflood bulb.

The photoflood is going to be optimized for balanced visible light.
The growlite will be optimized for more UV light, which plants need to
grow. I used a 150W growlite floodlamp.

> I may try another negative, right now I have very little black in
> mine because the circuit is sitting in a ground plane, traces only
> slightly seperated. Possibly I can tell whats going on with wider
> space between light and dark areas of the negative.

How are you holding the negative onto the board? Plexi or glass? How
thick? I'm not certain, but I think Plexiglass may block more UV than
glass, at least compared to cheap thin glass anyway.

Steve

More than likely, there is a film on the board and the
resist is not bonding to the board. Probably, it's
whatever your using to clean it with. I use comet or
ajax to clean scrub the board (This ensures fresh
exposed copper...). Then I wash with water to remove
any cleaner. I then wipe it down alcohol to make sure
no residues are on the board. At this point, I use a
new (And therefore, clean) paper towel. At this point,
I apply the resist.

Throughout this entire process, I wear latex
disposable gloves so that I do not inadvertently apply
my finger prints to the board.

YMMV, but it works for me every time.



Best regards

Marvin Dickens

=====
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If you use linux, get counted at:
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--- In Homebrew_PCBs@yahoogroups.com, "Steve" <alienrelics@y...>
wrote:

> Many years ago I made a bunch of boards using Datak Negative resist,
> sprayed it on with a pump sprayer. Do you mean you paint it on with
> those very soft fine foam makeup sponges?

Yes, I am. They work well and seam to leave no fibre behind, like a
tightly woven q-tip. I can get good coverage with no waste and even
pull any tiny dust particles to the side at least.

>
> Get a red bulb rather than the yellow bug light. You don't need a

very

> bright bulb ;') if you let your eyes become dark adjusted. I think I
> used a 15 or 25W when I was doing this.

Several people now have suggested this, may be part of the problem,
it would make sense, since the pattern seems to only be there
partially or not at all, leads me to believe that the whole board is
getting exposed instead of just the parts I want.

>
> Dry them in a bigger box. A small box will get full of fumes of the
> solvents and may never let the coating truly dry out.

Also a good thought, I do have them in a small box now, I will try
stepping up the size/oven idea.

Also your xenon flash idea is good to. I was thinking about trying
to expose with my scanner, possibly a certain number of slow scans.
But for right now I think I need to eliminate variables rather then
add them.

Thanks,
ED

Hello there Marvin,

--- In Homebrew_PCBs@yahoogroups.com, mpdickens <md30022@y...> wrote:
> More than likely, there is a film on the board and the
> resist is not bonding to the board. Probably, it's
> whatever your using to clean it with. I use comet or
> ajax to clean scrub the board (This ensures fresh
> exposed copper...). Then I wash with water to remove
> any cleaner. I then wipe it down alcohol to make sure
> no residues are on the board. At this point, I use a
> new (And therefore, clean) paper towel. At this point,
> I apply the resist.

I am scrubbing with ajax right now with bleach and a new scotch
bright. This was my first thought too, but I think the boards are
getting clean enough at this point. However, the gloves are a good
idea and also the alchohol wipe down. They do mention to use amonia
in the directions at there web site and I have not tried this yet.
>
> YMMV, but it works for me every time.

Do you just spray on one coat of the resist? I am wondering about the
depth of the coat.
How do you expose, for how long?
What are you using for a negative!

Thanks for the response, I feel as though I am very close, however
not quite there. Whats the board look like when your done, still
pretty much clear but just barely see the traces when tipped to the
side in the light?

_ED

Hello there Marvin,

--- In Homebrew_PCBs@yahoogroups.com, mpdickens <md30022@y...> wrote:
> More than likely, there is a film on the board and the
> resist is not bonding to the board. Probably, it's
> whatever your using to clean it with. I use comet or
> ajax to clean scrub the board (This ensures fresh
> exposed copper...). Then I wash with water to remove
> any cleaner. I then wipe it down alcohol to make sure
> no residues are on the board. At this point, I use a
> new (And therefore, clean) paper towel. At this point,
> I apply the resist.

I am scrubbing with ajax right now with bleach and a new scotch
bright. This was my first thought too, but I think the boards are
getting clean enough at this point. However, the gloves are a good
idea and also the alchohol wipe down. They do mention to use amonia
in the directions at there web site and I have not tried this yet.
>
> YMMV, but it works for me every time.

Do you just spray on one coat of the resist? I am wondering about the
depth of the coat.
How do you expose, for how long?
What are you using for a negative!

Thanks for the response, I feel as though I am very close, however
not quite there. Whats the board look like when your done, still
pretty much clear but just barely see the traces when tipped to the
side in the light?

_ED

--- In Homebrew_PCBs@yahoogroups.com, Stuart Winsor
<stuartwinsor@a...> wrote:

> I have to say I haven't used this particular product but when I was

using

> some spray-on resist it had to be done in a "darkroom". Only

illumination

> was a 15W bulb in an photographic "safelight".

Hey Stuart,

Yes this is going out! Sounds like it may be part if not the whole
problem. I am going to back the light out or down until I know I
have a safe space to coat the boards, and then if I still dont get
good results I will switch to sunlight just to prove to myself that I
have a good source of UV.

Right now it does seem like the problem is over exposure rather then
under and it may be the bug light zapping them before I ever even get
going...

thanks to all who have replied and helped by pointing out the
details, I will try it again with the new techniques and let you all
know how it goes. Though its at least a day between each trial.

ED

Oh, and I should mention that the page I have been following is:

http://www.pic101.com/pcb

it is excellent and where I got the idea for the makeup swabs and the
photoflood bulb, just to give credit where credit is due.

thanks for your efforts to help,

ED

> They do mention to use amonia
> in the directions at there web site and I have not
> tried this yet.

Ammonia is a degrease. I used to use it, but the fumes
are enough to cause insanity. So, I switched to
alcohol for decreasing. Also, I use denatured alcohol
of the highest purity I can find (I buy it at the
hardware store. It's not reagent grade, but it's clean
enough).

> Do you just spray on one coat of the resist? I am
> wondering about the
> depth of the coat.

The way I've always done it is to spray it on.
However, the spray bottle I use I purchased at the
shop that sell cookware (Pots, pans and etc...). The
bottle has a pump built into it. I put the resist into
it, pump it up and then spray it as if it were a can
of spray paint: I start at the top of the card and
spray from left to right (I'm right handed...). Once I
reach the far right of the card, I move down the card
just a bit and then spray from right to left, move
down the card, spray left to right. I do this motion
again and again until I'm at the bottom of the card. I
then inspect the card for an even coat. If the coat is
not even, I do it again over the uneven coat using the
same motion. Ultimately, you end up with a super even
coat. However, be careful: There is a fine line
between just right and too much...

This motion gives a *really* even coat (Using this
method, you can make canned spray paint look like it
was applied using an airbrush...).

> How do you expose, for how long?

I use quantity-4, 8-watt black lights. They emit UV
radiation around 325 to 350nM range which is the part
of the spectrum this type of resist reacts to. So, my
exposures are short: Depending on the size of the card
and the distance from the lamps, anywhere from 30
seconds to 5 minutes.

> What are you using for a negative!

I use clear transparencies (The type that are used in
overhead projectors) that I purchase at office depot
and staples (And occasionally, walmart...) I print
using an HP 7350 deskjet at 1200 dpi. Also, I ALWAYS
use original HP black ink. I've found the ink in the
clone cartidges and the refills to be too thin.

> your done, still
> pretty much clear but just barely see the traces
> when tipped to the
> side in the light?

This is a subjective question whose answer is function
of how good a persons eye sight is. So, the answer is
yes I can see it clearly, but at the same time, not
nearly as well as my 10 year old daughter (I'mm 44yrs
old...).


Best regards


Marvin Dickens
Alpharetta, Georgia

=====
Registered Linux User No. 80253
If you use linux, get counted at:
http://www.linuxcounter.org

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Eric,
Be sure to shake the can before you spray!

John

--- In Homebrew_PCBs@yahoogroups.com, "ednspace" <ed@c...> wrote:
> Hello,
>
> This is a plea for help!
> I am on my 5th trial with this and while each trial improves
somewhat
> in end quality, and certainly in the process, (no longer spilling
> solvent all over the basement), I still have yet to produce a board
> that I thought could be etched.
>
> The traces are very weak to washed out to non existant. At first I
> thought I was under exposing now I suspect I am over exposing or
just
> not getting a good build up of the resist on the board to start
with.
>
> I am looking for someone familiar with this method to bounce a few
> emails with so that I can get it right.
>
> At this point I am:
> In a 60watt bug light environment (Problem?)
> Coating the boards with makeup swab rather then spraying, much
nicer
> coat and no smears, nice and shiny, dust free mostly.
>
> Drying over night in a sealed shoebox, inside another box
>
> Using tracing paper as negative nice black laser print (Reported to
> work in many places)
>
> Exposing with a 250watt photoflood for various times and developing
> following supplier instructions with the recommended developer.
>
> Exposure times have been, 22, 10, 5 with a couple of retrials in
> between, no, luck. Any help would be greatly appreciated.
>
> Thanks,
> Eric

Hello mpdickens,

Wednesday, November 12, 2003, 5:40:56 AM, you wrote:

<snip>

m> I use quantity-4, 8-watt black lights. They emit UV
m> radiation around 325 to 350nM range which is the part
m> of the spectrum this type of resist reacts to. So, my
m> exposures are short: Depending on the size of the card
m> and the distance from the lamps, anywhere from 30
m> seconds to 5 minutes.


And I replied:

Do visit the following location http://www.stoufer.net and try to find the
explanation on using the 21 step Stoufer gauge for determining the right
time for wxposure. The board area is in no relation to eposure time. Only
the distance from the bulbs to ypur artwork/board combo.

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