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'[EE]: Etchant tank'
2003\03\27@191952 by Jai Dhar

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Hello all,

I thought the next step-up for me in the EE world would be to finally try my
hand at creating my own PCB's instead of using damned Veroboard. I have been
reading up on the etching process and it's requirements, so I have just a few
questions. Most importantly, how did you guys make your etchant tanks? What do
you recommend for someone starting? Keep in mind cost is an issue, and I don't
need something high-tech at all. From what I understand, basically all you need
is a glass tank of some sort, a bubble generator, and some etchant solution. Is
there anything else? I guess if I could get recommendations on all three, it
would help me out a lot!

Thank you everyone,

Jai



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2003\03\27@193222 by Sid Weaver

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For Jai

For a tank, use any suitable polyethylene container.  Agitation can be
provided by an aquarium air pump.  Heating the etchant always speeds up the
process.  Suitable etchants are ferric chloride and  an ammonia compound -
can't remember whether it is ammonium persulphate or ammonium chloride./
When heated the ammonium compound is very fast.  If you have a company near
you that sells chemicals for the manufacture of PC boards or a PC board house
they can tell you what it is.  Both etchants must be thoroughly rinsed off to
prevent copper oxidation.



Sid Weaver
W4EKQ
Port Richey, FL

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2003\03\27@194046 by Tony Nixon

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Jai Dhar wrote:
>
> Hello all,
>
>  I thought the next step-up for me in the EE world would be to finally try my
> hand at creating my own PCB's instead of using damned Veroboard. I have been
> reading up on the etching process and it's requirements, so I have just a few
> questions. Most importantly, how did you guys make your etchant tanks? What do
> you recommend for someone starting? Keep in mind cost is an issue, and I don't
> need something high-tech at all. From what I understand, basically all you need
> is a glass tank of some sort, a bubble generator, and some etchant solution. Is
> there anything else? I guess if I could get recommendations on all three, it
> would help me out a lot!
>
> Thank you everyone,

I just use Ferric Chloride in a plastic food container that has a sealed
lid.

No need for agitators and such.

Just use insulated "bell wire" standoffs on each corner of the board and
place the board copper side down in the etchant. While gravity pulls the
etched copper off the board, go and have a cup of coffee and the board
should be etched by the time you come back. You may need a way of
heating it, but I've never had to worry much at room temp.

See...

http://www.bubblesoftonline.com/projects/pcb.html

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2003\03\27@195748 by SavanaPics

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I built my tank out of Plexiglass.  A quick trip to a local glass shop and I
found a piece of scrap that I was given.  I told the guy what I was doing and
asked him if he could cut if for me and he gladly did so,  I tipped him 20.00
worth it to me.

The bubble generator  is nothing more than a cheap aquarium pump with an
airstone on it, works great.....espcially if you go to a larger pet store and
get wone of the long ones

I also put an aquarium heater in mine. This keeps the etchant warm and makes
the process a little quicker.  I also buit a small cam system which rocks the
whiole assembly back and forth.  If you do this make sure it is a slow
rock,,, with all the liquid in the tank it is easily tipped  if you rock it
too fast

This may be a little more than you are looing for but if not a start at least
a second step


Eddie Turner, kc4awz

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2003\03\27@200213 by Josh Koffman
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You may find this funny, but I do a lot of my home etching in an old
listerene mouthwash bottle. It's tall, so I can stand the board up for 2
sided boards to get slightly more even etching. It's not too wide so I
don't need to use tons of etchant to cover the vertical board. And it
fits right into a large gladware style container that I fill with hot
water to warm the etchant. I drill a hole in the top of the board and
use dental floss to dunk the board like a teabag. Eventually I will add
a small piece of hose and an aquarium pump to agitate automatically.
Until then, it works great.

BTW, I don't store the etchant in it as I had to cut off the top of the
bottle to widen the opening, thus making sealing it rather difficult :)

Hope this helps,

Josh
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Jai Dhar wrote:
> need something high-tech at all. From what I understand, basically all you need
> is a glass tank of some sort, a bubble generator, and some etchant solution. Is
> there anything else? I guess if I could get recommendations on all

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2003\03\27@200757 by Jai Dhar

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Wow, this maybe easier than I thought - so let me get a few things clarified
here.
Sid, polyethylene - you are going to have to clarify here :-) Are we talking
about plastic here, or glass??? Or neither..

It seems from the rest of your posts that food containers are sufficient (which
is splendid - I happen to have a collection of yogurt containers that are doing
absolutely nothing but looking pretty.... don't ask).

Tony, what is bell wire, and what is the purpose of putting it in the corner of
the boards?

Basically, if I want to be cheap about this, all I need is some plastic
container, the etchant, and something to suspend the board?? The rest (heater,
pump) is just for convenience?

This is good news if I am correct, might be a lot easier, heh.

Thank you all,

Jai

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2003\03\27@202243 by Tony Nixon

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Jai Dhar wrote:

> Tony, what is bell wire, and what is the purpose of putting it in the corner of
> the boards?

If you use my method of placing the board copper side down and let
gravity pull the etched copper off the board (quite fast in fact), then
you need a way of holding the board off the bottom of the tank. Bell
wire is same as telephone wire - single strand insulated copper. Thread
this through a hole in each corner of the PCB and twist it tight to make
little PCB stand offs. Have one longer than the others so it sticks out
of the etchant. This makes it easy to pull the board out.


> Basically, if I want to be cheap about this, all I need is some plastic
> container, the etchant, and something to suspend the board?? The rest (heater,
> pump) is just for convenience?

Correct.

Heater may help if ambient temp is very cold as this slows the etching
down.

You also need a Dalo pen or equivalent to draw the pattern. There are
other methods of transferring artwork to the PCB. See the archives.

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2003\03\27@202500 by Kyrre Aalerud

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Correct.

I'd reccommend something a bit stronger than a yogurt container...
I use a 1-litre glass-jar (was filled with marmelade...) It will allow me to
etch a double-sided 70x120mm board. It is also very sturdy and won't topple
over.

Neat trick for nice bubble-solution in glass jar:
- Make a plastic disc that will fit in the bottom of the jar (for example
from the bottom of a yogurt container?) and draw up a spiral pattern for
your airhose...
- make holes in the disc that match the outlines of the airhose at a
somewhat regular intervall...
- clogg one end of the airhose.
- Use fishing-line to tie down the airhose starting with the clogged end in
the center and move outward in the spiral.
- experiment with making holes in the hose untill you are satisfied with the
bubble-pattern.  A hot needle is great for this!
- Use a bit of silicone or something to glue the disc to the bottom of the
jar.

I'd reccommend a lid on the jar while bubbling or you will cover your
work-area in acid from the mist rising from the water/acid while bubbling.

You can use the cheapest air-pump for aquariums that you can get your hands
on.  flow won't be a big deal...  However a little more expensive one
(10-15$?) will give you some headroom and the option to limit the airflow a
bit if needed.

   Have fun!

{Original Message removed}

2003\03\27@203118 by Kyrre Aalerud

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Just wondering...  How fast do you get a board etched with this
gravety-method ?
With my self-modded bubble-tank I can etch a 70x120mm 1-sided board in about
5 minutes with fresh acid.  Is it comparable to your speeds?

   KreAture


{Original Message removed}

2003\03\27@204609 by Herbert Graf

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>  I thought the next step-up for me in the EE world would be to
> finally try my
> hand at creating my own PCB's instead of using damned Veroboard.
> I have been
> reading up on the etching process and it's requirements, so I
> have just a few
> questions. Most importantly, how did you guys make your etchant
> tanks? What do
> you recommend for someone starting? Keep in mind cost is an
> issue, and I don't
> need something high-tech at all. From what I understand,
> basically all you need
> is a glass tank of some sort, a bubble generator, and some
> etchant solution.

       Nah, don't need to get that fancy. I etch my boards in a plastic container
(that doesn't react with etchant) sitting in warm water. Sure it takes a few
more minutes but the quality of the etch is very good. TTYL

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2003\03\27@204814 by Herbert Graf

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> Just wondering...  How fast do you get a board etched with this
> gravety-method ?
> With my self-modded bubble-tank I can etch a 70x120mm 1-sided
> board in about
> 5 minutes with fresh acid.  Is it comparable to your speeds?

       Depending on the board size, and how stingy I am with my etchant (I often
put as little as possible) I get etch times ranging from 5 minutes to 20
minutes, using a "just let it sit in the acid and move it every couple of
minutes" method. The quality of the etch is quite good, and I've got the
time... TTYL

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2003\03\27@205229 by Jai Dhar

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Just checked out your page Tony, thank you for documenting your work so well -
makes learning a lot easier for newbies like me :-) Your method definitely
looks the most attractive (and easiest), so I'm going to give it a shot this
weekend. But one thing that I don't think you mentioned... how do you know when
the board is done? Is this just a qualitative observation? How long does your
method usually take (at normal room temp).

Thank you all again,

Jai

Quoting Tony Nixon <RemoveMEtony.nixonspamTakeThisOuTENG.MONASH.EDU.AU>:

{Quote hidden}

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2003\03\27@205408 by Tony Nixon

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Kyrre Aalerud wrote:
>
> Just wondering...  How fast do you get a board etched with this
> gravety-method ?
> With my self-modded bubble-tank I can etch a 70x120mm 1-sided board in about
> 5 minutes with fresh acid.  Is it comparable to your speeds?

Fresh warm mixture is about the same.

A few other benefits...

- all etched copper "rubbish" stays on the bottom of the tank so
solution stays very clean.

- I've had etchant for years and still works

- bubbles sometimes smear or erase some artwork, especially small tracks
in in overly warm solution.

- The gravity method creates very sharp track edges.

- cheaper, less fuss, no mess

- double sided is a bit slower as the "top" layer pools it's own residue
on top, but the remainder etches quickly when flipped over.

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2003\03\27@220237 by Tony Nixon

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Jai Dhar wrote:
>
> Just checked out your page Tony, thank you for documenting your work so well -
> makes learning a lot easier for newbies like me :-) Your method definitely
> looks the most attractive (and easiest), so I'm going to give it a shot this
> weekend. But one thing that I don't think you mentioned... how do you know when
> the board is done? Is this just a qualitative observation? How long does your
> method usually take (at normal room temp).


Just lift the board out every so often and check. After a few boards,
you will know what to expect. It can vary with board size, copper
thickness, temperature, how many beers I had last night etc etc...

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2003\03\27@222108 by Eric Schlaepfer

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Well, this makes me feel good--I just etched a board today which took
over an hour to etch. (Fresh ferric chloride too!)

Maybe I should get some kind of heater for the solution...

Later,

Eric

>Just wondering...  How fast do you get a board etched with this
>gravety-method ?
>With my self-modded bubble-tank I can etch a 70x120mm 1-sided board in about
>5 minutes with fresh acid.  Is it comparable to your speeds?
>
>

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2003\03\27@223739 by Jinx

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> If you use my method of placing the board copper side down and let
> gravity pull the etched copper off the board (quite fast in fact), then
> you need a way of holding the board off the bottom of the tank.

PCB will float upside down. The saturated FeCl I have is quite dense.
You need only be reasonably careful. Put one edge just on the clean
etchant surface and lower the board down so that air doesn't become
trapped. If it's GRP board you can see the tracks appear under normal
lighting as the copper is etched. Phenolic is more opaque and needs
to be inspected, but this needs to be done only after a time based on
previous etching eexperience. One of these days I'll get around to
making a clear tank with back-lighting for those odd times I use phenolic.
Or even maybe just dunk a couple of protected white LEDs in there

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2003\03\27@224359 by Jinx

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> Well, this makes me feel good--I just etched a board today
> which took over an hour to etch. (Fresh ferric chloride too!)
>
> Maybe I should get some kind of heater for the solution...

Or use a jacket with boiled water. Either way, hot etchant
cuts etching time down considerably

http://home.clear.net.nz/pages/joecolquitt/0makepcb.html

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2003\03\27@225436 by Rick C.

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Try http://www.pic101.com/pcb
Rick
>

Hello all,

How did you guys make your etchant tanks? What do
you recommend for someone starting? Keep in mind cost is an issue, and I
don't
need something high-tech at all. From what I understand, basically all
you need
is a glass tank of some sort, a bubble generator, and some etchant
solution. Is
there anything else? I guess if I could get recommendations on all
three, it
would help me out a lot!

Thank you everyone,

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2003\03\28@004938 by jim barchuk

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Hi Eric and All!

On Thu, 27 Mar 2003, Eric Schlaepfer wrote:

{Quote hidden}

I did about a year of 'small shop' PCB work many years ago. Did everything
from film processing, resist laminating and exposing, silk screen resist,
electroless PTH, etching, copper and solder plating, gold finger plating,
shearing, routing. The only thing I didn't do much was drilling because I
frigging hated it. :)

There were no heaters or bubblers anywhere. In fact it was pretty cold in
winter. The only agitation anywhere was the electroless.

That '5 minute etch' sure makes me nervous. 'Enough' etch is enough.
Anything more and it starts to undercut the resist.  IIRC that was in the
20-30 min range or thereabouts. Maybe it was the concentration, because
now that I think about it the whole time I was there we never changed that
solution.

In any case my point is 'enough' vs 'too much.' For the solution we had,
if 20 mins was enough and I missed it by a few % it was no big deal. The
same % of 5 mins is *much* shorter and easier to miss, and possibly cut a
track.

I guess it's a matter of 'what's it worth?' If I spent a bunch of time
drawing or dry transfering or photo shooting a board I don't think I'd
mind much if it took a bunch longer to etch *and* I didn't have to worry
about undercutting. The first two methods cost time, the last costs $. In
either case I'd rather not risk needing to throw something away and
starting over again. Besides, the extra time isn't exactly wasted because
I'd be off doing something else anyway.

Too eatch their own. :)

Have a :) day!

jb

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2003\03\28@032027 by

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Hi.
Just the other day I did the following :

1. Downloaded a PCB design from Elektor web site in PDF format.
  ("Electronic RPG Dice Roller", Jan-2003)

2. Printed it on my LaserJet 4plus on  sheet of standard "Coated Inkjet
  Paper" (made to print "photographs" on inkjet printers).

3. Took the "reflected" version and ironed it onto the copper laminate.
  (Old, standard iron put at "cotton")

4. Put the laminate into water for some 5-10 mnutes until the paper
  could be pulled of. Had to manualy (thumb) clean out some stuck paper.

5. Etched in "Ammonium Persulphate" (a standard ethcant) in an empty
  plastic food contained put into a larger plastic food contained where
  I pured hot water now and then to keep the etchant at about 50 deg C.

6. Drilled with a Dremmel on a Dremmel stand using Carbide bits.


Observations :

- The "coated inkjet paper" actualy gave better results (for me!) then
 the "Press-n-Peel" material from Techniks I'v also tried. But I think
 I heated the PnP material to much so it curled. Have to experiment more.

- I made a single side PCB from double sided, 0.5mm, 35my laminate. The
 "other" side just etched away during the process.

Currently I'm looking for some cheaper way of getting "Ammonium Persulphate"
or "Sodium Persulfate" then the electronics distributors.

When I started etching PCB (late 70's) I used a mixture of "hydrochloric acid"
and "hydrogen peroxide" diluted with water. This was fast and etched fine
at room temp.

As "etching tank", for hobby use any plastic container works.

And, finaly, if you're looking for low cost PCB laminate and drills, see :
http://w1.121.telia.com/~u12103129/


Jan-Erik Söderhol,.


Jai Dhar wrote:

{Quote hidden}

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2003\03\28@045937 by Alex Holden

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part 1 1951 bytes content-type:text/plain (decoded 7bit)

On Fri, 2003-03-28 at 00:18, Jai Dhar wrote:
> questions. Most importantly, how did you guys make your etchant tanks? What do
> you recommend for someone starting? Keep in mind cost is an issue, and I don't
> need something high-tech at all. From what I understand, basically all you need
> is a glass tank of some sort, a bubble generator, and some etchant solution. Is

I've been photo-etching boards for years using standard photographic
print developer trays and a tray heater to heat the solution (Ferric
Chloride or Sodium Persulphate) up to about 35C. It often takes 20-30
minutes (depending on how "tired" the solution is) to etch a board.
Manually agitating a tray for several hours can get very tedious (I
often do batches of ten or more boards at a time, most of them double
sided), so I finally decided to build myself a bubble etch tank.

I made it all from 5mm Acrylic (PMMA, AKA Perspex, AKA Plexiglas) sheet
cut using a fine toothed tenon saw. The heater is a cheap 300W fish tank
heater with the end-stop removed from the thermostat dial so that it can
be set to higher than 32C (the thermostat mechanism itself seems to crap
out at about 50C). The bubbles are produced by a flexible fish tank air
pipe connected to a cheap fish tank air pump (I'm going to change the
air pipe though as I'm not 100% happy with it). I've attached a photo of
the tank whilst testing it for leaks with hot water. Unfortunately the
epoxy resin glue wasn't strong enough and the joints started to come
apart at about 60C, so I've ordered some special two part acrylic
polymer adhesive to redo it with.

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part 2 18217 bytes content-type:image/jpeg; name=pcb-etch-tank.jpg (decode)


part 3 2 bytes
-

2003\03\28@072413 by Rick C.

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Yes, heating the solution will speed up the process. Especially since
leaving the board in too long will undercut (overetch) the traces under
the resist. If you look at my web page, I explain the whole process that
I have been using successfully for over 30 years. When available, you
might switch to Sodium Persulfate. It's almost clear and will not stain
and is easier to dispose of.
http://www.pic101.com/pcb

I worked in a large scale PCB house in the '70s for about 5 years,
repairing and maintaining the etchers, platers, laminators, and
Excellon/Trudrill machines. We had a Ferric Chloride etcher that had a
pizza oven type conveyor belt and the etchant was heated and high
pressure sprayed on the boards. It was in and out in about 40 seconds
with professional results.
Good luck. Rick

Hi Eric and All!

On Thu, 27 Mar 2003, Eric Schlaepfer wrote:

{Quote hidden}

in about
> >5 minutes with fresh acid.  Is it comparable to your speeds?

>I did about a year of 'small shop' PCB work many years ago. Did
everything
>from film processing, resist laminating and exposing, silk screen
resist,
>electroless PTH, etching, copper and solder plating, gold finger
plating,
>shearing, routing. The only thing I didn't do much was drilling because
I
>frigging hated it. :)

>There were no heaters or bubblers anywhere. In fact it was pretty cold
in
>winter. The only agitation anywhere was the electroless.

>That '5 minute etch' sure makes me nervous. 'Enough' etch is enough.
>Anything more and it starts to undercut the resist.  IIRC that was in
the
>20-30 min range or thereabouts. Maybe it was the concentration, because

>now that I think about it the whole time I was there we never changed
that
>solution.

>In any case my point is 'enough' vs 'too much.' For the solution we
had,
>if 20 mins was enough and I missed it by a few % it was no big deal.
The
>same % of 5 mins is *much* shorter and easier to miss, and possibly cut
a
>track.

>I guess it's a matter of 'what's it worth?' If I spent a bunch of time
>drawing or dry transfering or photo shooting a board I don't think I'd
>mind much if it took a bunch longer to etch *and* I didn't have to
worry
>about undercutting. The first two methods cost time, the last costs $.
In
>either case I'd rather not risk needing to throw something away and
>starting over again. Besides, the extra time isn't exactly wasted
because
>I'd be off doing something else anyway.

>Too each their own. :)

>Have a :) day!

>jb

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2003\03\28@075120 by Sid Weaver

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In a message dated 03/27/2003 20:48:35 Eastern Standard Time,
.....jdharspam_OUTspamENGMAIL.UWATERLOO.CA writes:


> Sid, polyethylene - you are going to have to clarify here :-) Are we talking
> about plastic here, or glass??? Or neither..
>

Good morning Jai

Polyethylene is a plastic, impervious to almost all chemicals.  It what most
of the household containers such as wash basins, icebox storage containers,
etc., are made of.  When I had my PC board shop I had large 7-gallon tanks of
polythylene for sulfuric acid pre-clean, electroless copper, plating and
etchant.  You won't need tanks near that big.  A helpful method of heating is
to just place your etchant tank in a larger container filled with very hot
water.

Sid

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2003\03\28@110337 by John Ferrell

face picon face
I don't do this often, so I look for the easy way out.
  Wear good rubber gloves for personal safety.
 1- Find cardboard box of appropriate size
 2- Line box with plastic food wrap from kitchen, single sheet, no seams.
      Pay attention to the corner that you plan to use to pour the used
solution for recovery.
      Use masking tape to assure that the plastic stays in place.
 3- Throw away the box when done.

Do all work in a large plastic tray to limit any spill damage.

If the zip lock bags advertised on TV really work as well as advertised, I
will eventually get around to trying to etch in one.

Putting down resist need not be as difficult as the commercial folks lead us
to believe.
I have successfully used nail polish, masking tape, Scotch tape, shelf
paper, model airplane paint, labels, permanent markers.
Drilling holes before etching makes applying resist easier. I have not
found an easy way to apply resist to make DIP patterns.
Fortunately, sockets are cheap. I find that a combination of techniques
works better for me rather than single solution.
'Dead bug' and 'Manhattan construction are still my mainstays for prototype
construction. I cannot recall the last time I
bothered to repackage a project. Ugly is not necessarily bad!

John Ferrell
6241 Phillippi Rd
Julian NC 27283
Phone: (336)685-9606
Dixie Competition Products
NSRCA 479 AMA 4190  W8CCW
"My Competition is Not My Enemy"

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2003\03\28@114317 by William Chops Westfield

face picon face
Sheesh.  a <$5 "tupperware" container will work fine, and they're available in
a wide variety of sizes (many rectangular.)  A major reason for the popularity
of ferric chloride in hobbyist PCB production is that it DOESN'T require all
those extras like heaters, bubblers, sprayers, and so on.  Those might make
things go faster, but room-temperature drop-it-in and agitate every couple of
minutes will work.

BillW

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2003\03\28@124713 by Peter L. Peres

picon face
The simplest etchant tank is a tall plastic food container that stands in
a shallower one. The tall tank is filled to 2/3 with FeCl3 etching
solution and with a half dozen pebbles (to prevent it from floating) and
the outer shallow one is filled as high as you dare with water from a
kettle. If you use the lid on the etchant tank it will keep for 2 years or
more, in despite of what others say. You don't really need bubbles for a
start, just more time and move the board in the etchant from time to time.
I use a phonebook as insulation under the shallow container, it keeps the
water hot longer.

This is the starting point. I am sure the list will have contributed
computer controlled laser-powered interferometer-feedback units by the
time you read this.

Peter

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2003\03\28@131618 by Kyrre Aalerud

flavicon
face
I usually leave it alone...
Then I got time to work on the pic-code while I etch.

   KreAture

----- Original Message -----
From: "Herbert Graf" <TakeThisOuTmailinglist.....spamTakeThisOuTFARCITE.NET>
To: <TakeThisOuTPICLISTKILLspamspamspamMITVMA.MIT.EDU>
Sent: Friday, March 28, 2003 2:47 AM
Subject: Re: [EE]: Etchant tank


> > Just wondering...  How fast do you get a board etched with this
> > gravety-method ?
> > With my self-modded bubble-tank I can etch a 70x120mm 1-sided
> > board in about
> > 5 minutes with fresh acid.  Is it comparable to your speeds?
>
>         Depending on the board size, and how stingy I am with my etchant
(I often
> put as little as possible) I get etch times ranging from 5 minutes to 20
> minutes, using a "just let it sit in the acid and move it every couple of
> minutes" method. The quality of the etch is quite good, and I've got the
> time... TTYL
>
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2003\03\28@132047 by Kyrre Aalerud

flavicon
face
I use photoresist and thin ccopper and it is very resistant to over-etching.
The board can be finished in 5 minutes, and if I take it out after 10
minutes, no damage has been done.

   KreAture

{Original Message removed}

2003\03\28@134321 by Eric Schlaepfer

picon face
One of these days I will try out the photoresist approach.  What copper
thickness did you use for that?  I think my etching time was for 1 ounce
copper, although the board is from scrap and I am not sure how thick the
copper is.

I've been using toner transfer for my boards, usually with the DynaArt
transfer paper.  However, this last etch I was out of transfer paper so
I used a photocopier with plain paper, which didn't work very well at
all.  I had to touch up the design with a sharpie to fill in all the
dropouts.

Later,

Eric





>I use photoresist and thin ccopper and it is very resistant to over-etching.
>The board can be finished in 5 minutes, and if I take it out after 10
>minutes, no damage has been done.
>
>    KreAture
>
>{Original Message removed}

2003\03\28@151850 by Charles Anderson

flavicon
face
That looks a whole lot like mine, that I built out of 1/8" & 1/4 acryllic.
I tried to make it fit tight enought and cut straight enough that I wouldn't
have to put silicone sealant all over it, but alas, that was a pipe dream.

I'll try to take a picture and post it.

-Charlie
On Fri, Mar 28, 2003 at 09:58:05AM +0000, Alex Holden wrote:
{Quote hidden}

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2003\03\28@171015 by erholm (QAC)

flavicon
face
Hm, right now I'm doing some experiments with Laserjet
prints, an iron and some laminate. Standard printer
paper don't work well, as you said. The melted toner not
only sticks to the coper, it also sticks hard to the
paper base. Right now I have a test with "coated inkjet
paper" in the water to take the paper off. we'll see...

...a couple of hours (and beers) later...

Well, it's still some problem to get the paper off
the laminate after the ironing. Maybe I should have
let it stay longer in the water. I Just left it there
for a couple of minutes.

Anyway, this DynaArt transfer paper, is that something
like the Press-n-Peel material from Techniks ? I have
done some test with PnP-Wet, but my problem seems to
be that the PnP paper is thicker (and harder to warm
in th printer) so large black areas gets large dropouts.
Is the DynaArt material much thinker then standard paper ?
Do you have some link to the producer of DynaArt ?

What about this material that are used to iron pictures
on T-shirts ? Maybe I'll buy me a package...

Jan-Erik Soderholm

PS.
Earlier to day I bought hydrochloric acid (30%) and
hydrogen peroxide (30%). I mixed 1 part of each with 10
parts water and got much faster etching (at room temp)
then with the Ammonium/Sodium Persulphate etchers. One
just have to make sure that one pour the *hydrochloric acid*
into the *water* and not the other way around...
DS.

{Original Message removed}

2003\03\28@183632 by Dal Wheeler

flavicon
face
I've had pretty good results(toner transfer method) using semi-glossy
magazine pages --they have enough clay to keep the voids to a minimum and
the paper is thin enough that it soaks up the water quickly.  I found
putting a tiny bit of dish soap helps the paper penetration process as well.
I've commandeered my wife's paper laminator and found several passes through
it give just the right heat/pressure.  I've only done small boards with this
method...  I've tried a bunch of inkjet photopaper and found that the
glycerin tends to leave a little residue --plus the backer paper takes way
too long to penetrate.

{Original Message removed}

2003\03\29@163816 by Kyrre Aalerud

flavicon
face
I used 17.5um thick copper.  (I don't know what that translates to in oz...)

Oh, and I might add:
In room temp of 22*C I can etch a board in about 20 minutes in bubble-tank
with mild acid.
It takes 1-2 hours in normal plastic-tray with agitation when i bother to
drop by and kick it around, so I definately reccommend everyone to get a
ultra-cheap aquarium air-pump and make themselves some bubbles.

   KreAture



{Original Message removed}

2003\03\29@172653 by

flavicon
face
18um : 0.5 oz
35um : 1.0 oz
70um : 2.0 oz

Isn't "oz" realy "oz per square feet" or something similar ?

Jan-Erik.

Kyrre Aalerud wrote:
> I used 17.5um thick copper.
> (I don't know what that translates to in oz...)

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2003\03\29@193539 by Jinx

face picon face
Just out of interest, having noticed the corrosion of iron when
it's around FeCl, I thought I'd try and make use of that, and
perhaps find a use for used FeCl

A simple experiment to see if rusting can be accelerated so
that finishing treatment can be applied earlier

http://home.clear.net.nz/pages/joecolquitt/corrosion.html

Starting with three mild steel welds ground flat. The bottom left
corner is left to age normally overnight, the bottom right has
vinegar rubbed in and the top left has spent FeCl rubbed in

The copper immediately drops out of the FeCl solution on to
the fresh iron surface. I doubt if it's bonded though

The next morning, the FeCl and vinegar welds show considerably
more rusting than the corner weld (which I think was being affected
by migrating chemicals from the other two. It should have been
just the golden colour in the extreme bottom left)

All three were then wire-brushed and treated with Blackguard, an
acrylic rust converter/primer

http://www.tergo.co.nz/Tech%20Data/HTML/blackguard.htm

6 hours later the FeCl weld rust conversion is patchy, although
places where copper didn't drop look pretty good. Similarly the
vinegar weld has a healthy amount of rust conversion and I think is
the best of the three. The normal weld still had bare steel in places
and should have had more time to build up consistent surface rust

Result - hmmm. Well, you have to try things sometimes just to see
what happens. Think I'll stick with vinegar. Fresh FeCl might work,
but that's probably wasting it

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2003\03\29@223829 by Jai Dhar

flavicon
face
Hey all,

I finally got myself a hold of some supplies. I decided to go with a simple
resealable container and some Ferric chloride. Now the stuff I got was solid,
they didn't have any premixed... for a bag of the stuff (it looked like yellow
beads), it said it could mix 1L. I figured this was more than I needed, so I
just used 1 Cup (~250ml), and consequently, a quarter of the bag. I cut myself
a really small peace of PCB material, drew some lines on it (both with an
etching marker that I purchased, and a 'Sharpie' - the etching marker was
really thick, so I decided to try both since the Sharpie was thinner). I have
been waiting 1.5 hours now, and I can't really tell if it is done, but it
doesn't seem to be. I take it out periodically, and dry it off. I then check
continuity in the regions OUTSIDE the tracks, and it is still conducting.
Shouldn't the etchant eat away everything but the tracks? When I rub the marker
off, there lies a nice shiny copper track... but it's still basically one
copper plate, not individual tracks. Am I doing something wrong (maybe not
enough FeCl, long enough period...)?

Thank you,

Jai

Ps: I mixed with hot water, just to speed things up.

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2003\03\29@230243 by Jinx

face picon face
> they didn't have any premixed... for a bag of the stuff (it looked
> like yellow beads), it said it could mix 1L. I figured this was more
> than I needed, so I just used 1 Cup (~250ml), and consequently,
> a quarter of the bag

You need a saturated solution of FeCl. Get the water really hot and
keep adding powder until no more will dissolve. When cool, decant
the solution off into a container. What's left in the original container
is FeCl, which you can make up into more solution. Do your mixing
well away from anything (especially metal, like a kitchen sink) you
want to keep clean. FeCl powder is hygroscopic and will stain

If you aren't etching in less than 10 minutes then either the solution
is too weak or it's not hot enough

I have this vague memory of being told that FeCl doesn't work so well
above 70-80dC. Something to do with electrochemistry. But I could be
confusing that with something else. FeCl is an ionic salt, maybe there's
a transition from ionic to molecular state. Anyhoo, in a hot water bath it
seems to etch OK

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2003\03\29@235338 by Dave Tweed

face
flavicon
face
Jan-Erik <RemoveMEJan-erik.SoderholmspamspamBeGonePAC.ERICSSON.SE> wrote:
> Kyrre Aalerud wrote:
> > I used 17.5um thick copper.
> > (I don't know what that translates to in oz...)
>
> 18um : 0.5 oz
> 35um : 1.0 oz
> 70um : 2.0 oz
>
> Isn't "oz" realy "oz per square feet" or something similar ?

Yes.

At 8.96 g/cm^3, one ounce of copper covers one square foot to a
thickness of 34.1 um.

-- Dave Tweed

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2003\03\30@002041 by Jai Dhar

flavicon
face
Ok, I guess they were being on the 'safe' side in the quantities, lol. I just
added a bit more (still haven't saturated it though), and I can actually tell
that hte board is etching, lol. I couldn't tell before, but not it looks like
the bottom side (it's not a double sided board).... guess all I need was a bit
more juice :-)

Thanks again,

Jai

Quoting Jinx <spamBeGonejoecolquitt@spam@spamspam_OUTCLEAR.NET.NZ>:

{Quote hidden}

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2003\03\31@044817 by Alan B. Pearce

face picon face
>A simple experiment to see if rusting can be accelerated so
>that finishing treatment can be applied earlier
>
>http://home.clear.net.nz/pages/joecolquitt/corrosion.html

I see your cat also has to be "foreman on the job" to make sure you do it
right :)))

We've got one like that too.

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2003\03\31@164738 by Peter L. Peres

picon face
Jai, I think that you diluted the FeCl3 too much. The normal way to
prepare the solution is to put the 'beads' in a container so there is a
single layer of them in it filling and spread on the bottom, then pour a
little water from a kettle (after it boiled) and stir with a plastic
spoon. The add more water etc until the last 'bead' is dissolved. That
makes a solution that is guaranteed to be saturated at room temperature
and slightly above. The total amount of water required makes an amount of
liquid with a level slightly lower than the tops of the 'beads' before you
started. If it works out otherwise then you used way too much water.

Normal etch time with this solution without stirring at room temp (25C) is
less than 30 minutes. With stirring or bubbles and heat it can be 5 to 7
minutes.

hope this helps,

Peter

Jai Dhar wrote:

I finally got myself a hold of some supplies. I decided to go with a
simple resealable container and some Ferric chloride. Now the stuff I got
was solid, they didn't have any premixed... for a bag of the stuff (it
looked like yellow beads), it said it could mix 1L. I figured this was
more than I needed, so I just used 1 Cup (~250ml), and consequently, a
quarter of the bag. I cut myself a really small peace of PCB material,
drew some lines on it (both with an etching marker that I purchased, and a
'Sharpie' - the etching marker was really thick, so I decided to try both
since the Sharpie was thinner).

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2003\03\31@174102 by jim barchuk

flavicon
face
Hi Jai!

> Jai Dhar wrote:

> drew some lines on it (both with an etching marker that I purchased, and a
> 'Sharpie' - the etching marker was really thick, so I decided to try both
> since the Sharpie was thinner).

How did the Sharpie work out as a resist?

And did you try it all again with a more concentrated solution, again
with the Sharpie, and how well did it work??

Have a :) day!

jb

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2003\03\31@193746 by Jai Dhar

flavicon
face
To let you guys know (who are tracking this), the Sharpie works great as long
as I make sure the lines are as dark as possible. Obviously I'm still
experimenting with the process since I'm new at this (thank god I have a lot of
boards). I don't think I will be able to do SMT with the sharpie though, unless
I get a super thin one. I guess using laser toner transfer would be the way to
go then? (thinking a few months down the road here).

I just bought a brand new dremel and drill press stand, so that and the etchant
will keep me busy for the next while :-)

Quoting jim barchuk <EraseMEjbspam@spam@JBARCHUK.COM>:

{Quote hidden}

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2003\03\31@200312 by Kyrre Aalerud

flavicon
face
Doing inkjet prints and UV-transfers is a good option.

What you need:
- Inkjet transparancies
- Boards coated with positive photo-resist
- developer (NaOH)
- etchant (Na?? you have this already...)
- UV source.  (If you live in a place with direct sunlight it will be
freeee!)

If you have a HP printer with a photo-ink or similar you will most likely
have very thick glossy black ink.  This is the best to use as you can get
away with a single layer.  With Canon it is best to print same drawing twice
and tape them together to get thicker black.

Sanwitch to your PCB after removing the protective dark layer and expose to
UV as needed ,(experiment!) (1-2 mins MAX with direct sunlight!) and
develop.
If done right you won't have to worry too much about over-developing within
the normal timeframe of developing.  (1-2 minutes max.)

Then etch as if you used any other transfer method.

This method allows for better accuracy than toner-transfer and is a very
good solution even for hobbyists.  I often like to make my tracks as wide as
possible to prevent any mishaps during etching, but I can reliably do 12mil
wide tracks without being too careful.  12mil with toner-transfer is scetchy
at best!

   KreAture



{Original Message removed}

2003\03\31@221741 by Herbert Graf

flavicon
face
> Doing inkjet prints and UV-transfers is a good option.
>
> What you need:
> - Inkjet transparancies
> - Boards coated with positive photo-resist
> - developer (NaOH)
> - etchant (Na?? you have this already...)
> - UV source.  (If you live in a place with direct sunlight it will be
> freeee!)

       FWIW regular fluorescent lights work very well for this sort of thing. Only
need about 10 minute exposure (or less) for the boards I use. TTYL

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'[EE]: Etchant tank'
2003\04\01@025721 by
flavicon
face
Kyrre Aalerud wrote:

> What you need:
> - Inkjet transparancies
> - Boards coated with positive photo-resist

 What's the lists opinion on thoses photoresists that you
 spray on clean copper clab from a can ?

 Jan-Erik.

> - developer (NaOH)
> - etchant (Na?? you have this already...)
> - UV source.  (If you live in a place with direct sunlight it will be
> freeee!)

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2003\04\01@060726 by Kyrre Aalerud

flavicon
face
Wow...
I use 3x 4w UV tubes and need 15 minutes for single transparancy and 30 mins
for double.
Are you perhaps using 30w tubes ?  (I'm trying to make a small compact
lightbox as the one I have is clearly too low power...

   KreAture



{Original Message removed}

2003\04\01@061509 by Kyrre Aalerud

flavicon
face
Too much mess, and almost as expensive.

   KreAture

----- Original Message -----
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To: <.....PICLISTSTOPspamspam@spam@MITVMA.MIT.EDU>
Sent: Tuesday, April 01, 2003 9:54 AM
Subject: Re: [EE]: Etchant tank


{Quote hidden}

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2003\04\01@062132 by Alex Holden

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face
On Tue, 2003-04-01 at 12:17, Kyrre Aalerud wrote:
> I use 3x 4w UV tubes and need 15 minutes for single transparancy and 30 mins
> for double.
> Are you perhaps using 30w tubes ?  (I'm trying to make a small compact
> lightbox as the one I have is clearly too low power...

My small commercially made light box has two 8W tubes and takes about 4
minutes per side (it can only expose one side at a time). Maybe your
tubes are putting out the wrong wavelength of UV?

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2003\04\01@062757 by Mike Harrison

flavicon
face
On Tue, 1 Apr 2003 13:24:59 +0200, you wrote:

>Too much mess, and almost as expensive.
>
>    KreAture
>
>{Original Message removed}

2003\04\01@063007 by Mike Harrison

flavicon
face
I've used UV boxes with 2 x 8W and 4x15W, time is typically 5 mins.
Obviously it depends on the resist and the tube distance but 15 mins is forever. What transparency
are you using. Tracing paper is by faer the best I've found for use in laser printers, cheap and
good toner adhesion.

On Tue, 1 Apr 2003 13:17:19 +0200, you wrote:

>Wow...
>I use 3x 4w UV tubes and need 15 minutes for single transparancy and 30 mins
>for double.
>Are you perhaps using 30w tubes ?  (I'm trying to make a small compact
>lightbox as the one I have is clearly too low power...
>
>    KreAture
>
>
>
>{Original Message removed}

2003\04\01@063211 by Russell McMahon

face
flavicon
face
> On Tue, 2003-04-01 at 12:17, Kyrre Aalerud wrote:
> > I use 3x 4w UV tubes and need 15 minutes for single transparancy and 30
mins
> > for double.
> > Are you perhaps using 30w tubes ?  (I'm trying to make a small compact
> > lightbox as the one I have is clearly too low power...
>
> My small commercially made light box has two 8W tubes and takes about 4
> minutes per side (it can only expose one side at a time). Maybe your
> tubes are putting out the wrong wavelength of UV?

There are "black light" UV tubes and long wavelength germicidal tubes. You
want the latter.
Black light tubes are dark almost black when off and a very deep purple when
running.
Germicidal etc tubes are usually clear and have a violent purple look when
you look at them - for a few seconds anyway - don't do it !


           RM

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2003\04\01@063625 by Kyrre Aalerud

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face
No... Yours are 8w unfiltered UV or blacklights.
Mine are 4w filtered blacklights.  (filtered are the purple/blue ones.)
And, by using double film I reduce the throughput a lot.

I will be making a better one soon. Will be using 2x8w like yours.

My question was what type of "ordinary" tubes was used...

   KreAture


{Original Message removed}

2003\04\01@063837 by Russell McMahon

face
flavicon
face
>>>   What's the lists opinion on thoses photoresists that you
>>>   spray on clean copper clab from a can ?

>>Too much mess, and almost as expensive.

>Complete waste of time - you get uneven coating, and dust spots.
> DOn;t even think about it unless you have a cleanroom and a dip-tank.

I've read opinion here that says you can get excellent results if you
understand your materials. Elevated temperatures to allow very rapid drying
was a major factor AFAIR.

My experience, long ago, was that it is doable with great care, attention to
detail and consistent technique obtained by experiment. ie can be done but
needs dedication and discipline.


       RM

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2003\04\01@065120 by

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In the catalog, they recomend drying in 70 deg C
for 5 min. Drying time at 25 deg C is 24h.

They also say : "Photoresist is very easy to use"

:-) :-)

Anyway, I'll get me a can and try it.

Jana-Erik.

Russell McMahon wrote:

>>>   What's the lists opinion on thoses photoresists that you
>>>   spray on clean copper clab from a can ?

>>Too much mess, and almost as expensive.

>Complete waste of time - you get uneven coating, and dust spots.
> Don't even think about it unless you have a cleanroom and a dip-tank.

I've read opinion here that says you can get excellent results if you
understand your materials. Elevated temperatures to allow very rapid drying
was a major factor AFAIR.

My experience, long ago, was that it is doable with great care, attention to
detail and consistent technique obtained by experiment. ie can be done but
needs dedication and discipline.

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2003\04\01@071234 by Kyrre Aalerud

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face
My transparencys are the coated kind for inkjets.
(Laser would be better I know, but I don't have a laser that doesn't leave
streaks all over the page right now...)

My problem is simple, I have the coated kind of tubes and only 4 watts...  I
addition they are run by a inferior inverter sucking 3 amps at 12 volts.

I'm off to buy new gear now :-)

   KreAture


{Original Message removed}

2003\04\01@071433 by Kyrre Aalerud

flavicon
face
Elfa ?
hehe

Well, precoated boards are easier to use :-)

   KreAture (off to Elfa to buy gear for new lightbox...)

{Original Message removed}

2003\04\01@071847 by Mike Harrison

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face
There are 3 types of tube commonly available : 1) 'Blacklight' - used for effects lighting -  these look black - not used them, they may be
suitable, but may extend exposure time 2) Insect killer tubes - these look while (like normal tubes) when off - these are the ideal type
for PCB exposure 3) Germicidal (also for eprom erasers) - These look transparent - they emit shortwave UV hazardous
to skin and eyes, and are no good for PCB exposure.


On Tue, 1 Apr 2003 11:24:00 +1200, you wrote:

{Quote hidden}

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2003\04\01@081056 by Olin Lathrop

face picon face
> There are "black light" UV tubes and long wavelength germicidal tubes.

Actually, the germicidal tubes have an even shorter wavelength than the
"black light" tubes.


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2003\04\01@112215 by Herbert Graf

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> Kyrre Aalerud wrote:
>
> > What you need:
> > - Inkjet transparancies
> > - Boards coated with positive photo-resist
>
>   What's the lists opinion on thoses photoresists that you
>   spray on clean copper clab from a can ?

       I don't know about the rest of the list but I have heard that they are more
trouble then they are worth. Presensitized boards result in far more
consistent results. TTYL

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2003\04\01@112220 by Herbert Graf

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> Wow...
> I use 3x 4w UV tubes and need 15 minutes for single transparancy
> and 30 mins
> for double.
> Are you perhaps using 30w tubes ?  (I'm trying to make a small compact
> lightbox as the one I have is clearly too low power...

       The one I use is 20W, it just my desk light, works fine. I tried the light
box method using UV tubes and it's just much slower. TTYL

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2003\04\01@122703 by Kyrre Aalerud

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Might be some sort of daylight reading lamp you got there.
Withoug a glass in front of the bulb you will get a little more light and if
it's not UV-shielded you should get enough UV to do a board....  But still,
a lightbox with quarts glass and 2x8w real UV will be faster.  The one we
have at the university takes 3 minutes.

   KreAture

{Original Message removed}

2003\04\01@123917 by Jai Dhar

flavicon
face
Since this thread has (naturally) progressed to track drawing methods, it has
peeked my interest into this UV business. So let's say I would want to get away
from Sharpie's, what are my options? 1) Buy a laser printer (which I don't
exactly have the money for), transfer onto some special paper and then iron on
the tracks? (I might not have the method exactly right, but something along
those lines??). 2) The UV method... anything else? If I wanted to do UV, what
do I need? Can I do it with regular copper clad boards, or do I have to
get "pre-sensitized" boards. How much am I looking at to build a UV box? Or do
I need a box? Someone mentioned simply using their desk lamp.. is it possible
to just get a UV tube and do it this way? I'm totally foreign to the idea of UV
transfer, and the recent postings have both informed about it, yet confused me
about the process.

Thanks again,

Jai

Quoting Mike Harrison <RemoveMEmikeKILLspamspamTakeThisOuTWHITEWING.CO.UK>:

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2003\04\01@125458 by Wagner Lipnharski

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Mike Harrison wrote:
> There are 3 types of tube commonly available :
> 1) 'Blacklight' - used for effects lighting -  these look black - not
> used them, they may be
> suitable, but may extend exposure time
> 2) Insect killer tubes - these look while (like normal tubes) when
> off - these are the ideal type
> for PCB exposure
> 3) Germicidal (also for eprom erasers) - These look transparent -
> they emit shortwave UV hazardous
> to skin and eyes, and are no good for PCB exposure.


It worths to say, internally they are all the same.

Most "white lamps" have the bulb made of glass with an internal coating of
phosphor powder. Electrons flowing between electrodes hit the mercury
vapor, it generates UV radiation, hits the phosphor powder, that emits
white light.  In "glass" bulbs, the UV is strongly blocked, by the phosphor
and by the glass, that is a not so good UV conductor.

When the bulb is made of "crystal" instead "glass", the UV gets out easily.
The UV can kills (slowly) insects that are attracted by the white or UV
light.  Speeding up insect killer operation can be done by some High
Voltage grid around the lamps, that simply zap them with a "fatal strike
calling message from after-life dimension", known as the "10kV grid wires
dimension"... :)

I personally never saw a "crystal" bulb with phosphor coating, but it may
exist. I don't see any particular application for it, since the UV would be
reduced, and the phosphor light would be most useful for human view, but
with UV present, no human view would be recommended, so... I can guess some
machinery can be benefited by some white light and UV at the same time.

There are some UV sensitive ink in the market, specially good for the
Germicide lamp use.  Germicide lamps are also used to erase windowed eprom
type chips.

More info about fluorescent lamps, check http://www.ustr.net

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2003\04\01@125721 by Kyrre Aalerud

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As i said in my previous posting, the difference is either pre-sensitized
boards or a can of spray-on sensitizer, and a UV-source.

   KreAture

{Original Message removed}

2003\04\01@150244 by Olin Lathrop

face picon face
> As i said in my previous posting, the difference is either
> pre-sensitized boards or a can of spray-on sensitizer, and a UV-source.

A long time ago in the late 1970s and early 1980s I experimented with
etching my own boards.  At the time at least, the spray on resist was hard
to use.  There was another product I had reasonable success with.  It came
in two parts.  You mixed them shortly before use and painted them onto a
board.  After drying, it left a greenish film.  This was exposed with
white light and developed with plain water.  The only inconvenient part
was that after developing you had to bake the board to make the unetched
resist become permanent.  I think it was called something like "Resolv".
All in all I liked it much better than the lacquer based spray on resist.
I have no idea if it's still available.


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2003\04\01@153546 by

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face
I "exposed" pre-sensitized boards using a ordinary
desk lamp fitted with one of these small, 12V, 20W
halogen lamp bulbs (with two pins). Take some
10-20 min with the lamp aprox 10 cm over the board.
The film is standard OH film with pattern printed on
a HP DeskJet 960C (mostly from PDF files downloaded
from e.g. the Elektor site).

Another method I have been thinking about, but not tested,
is to put the board and film in the scanner part of my
HP OfficeJet R series (with the flatbed scanner on
th top), and then just run a number of "scans"
or "copies". I'm not sure that the lamp moves with an
even speed, depending on the setup it often moves a few
cm's, then pause and so on. Well, might not work at all...


Kyrre Aalerud wrote:

>Might be some sort of daylight reading lamp you got there.

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2003\04\01@154823 by

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You points 1) and 2) below are not realy to options,
but rather two different steps in the UV-process.

You have to :

1) Produce a "positive film" of your PCB pattern.
  Personaly I have had good results with a HP LaserJet 960C
  and standard OH inkjet film, but a good laser printer
  or Xerox copier should also work.

2) Use copper clad with a "positive photoresist" layer.
  These can be bought ready made, or be made by applying
  photoresist to bare copper clad baords. Then expose with
  UV light. Standard lamps take longer, UV lamps cost $$'s
  and the sunlight is 100% free...
  (You need a pair of glass sheets also)

And the different ironing (heat) transfer methods (like
Press-n-Peel from Techniks) has nothing to do with "UV" at all...

Jan-Erik Söderholm.



Jai Dhar wrote:

{Quote hidden}

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2003\04\01@161417 by Jai Dhar

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face
Quoting "Jan-erik Söderholm (QAC)" <Jan-erik.SoderholmspamBeGonespam.....PAC.ERICSSON.SE>:

> You points 1) and 2) below are not realy to options,
> but rather two different steps in the UV-process.
>
> You have to :
>
> 1) Produce a "positive film" of your PCB pattern.
>    Personaly I have had good results with a HP LaserJet 960C
>    and standard OH inkjet film, but a good laser printer
>    or Xerox copier should also work.

Would an inkjet printer work? Or are there any methods to produce a positive film with an inkjet?
>
> 2) Use copper clad with a "positive photoresist" layer.
>    These can be bought ready made, or be made by applying
>    photoresist to bare copper clad baords. Then expose with
>    UV light. Standard lamps take longer, UV lamps cost $$'s
>    and the sunlight is 100% free...
>    (You need a pair of glass sheets also)

Time is not really an issue, these would all be one off's so it's ok. If I wanted to go with a 'standard' lamp, what kind of lamp is that exactLY? Halogen? Just a regular Incandescent light bulb? And how much are UV lamps typically?

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2003\04\01@171440 by

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Sorry !!
It's a "HP DeskJet 960C", of course !
          ====

Or, in other words, an "inkjet" type printer. So the answer
to your question is, yes :-)

Most lamps of any type has *some* UV in there light,
it just a matter of exposure time (and much testing).
The UV-lamps *I* have seen was 30-40 USD. And don't
forget the "standard" sunlight.

Jan-Erik.

Jai Dhar wrote :

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2003\04\01@174346 by Herbert Graf

flavicon
face
> Might be some sort of daylight reading lamp you got there.
> Withoug a glass in front of the bulb you will get a little more
> light and if
> it's not UV-shielded you should get enough UV to do a board....
> But still,
> a lightbox with quarts glass and 2x8w real UV will be faster.  The one we
> have at the university takes 3 minutes.

       Agreed, but at the same time there is a cost factor. 10 minutes versus 3
minutes isn't worth the cost of the "proper" equipment. My desk light is
"free" after all. TTYL

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2003\04\01@200904 by Kyrre Aalerud

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My time is worth more than a simple UV-lamp.

- A good but cheap-ish lightboard costs about $500 so that's out...

- A normal reading-lamp with a daylight tube may get you results in 5-20
minutes so it's a good option for a one-off every milennia.

- A couple of lamp-sockets, some UV-tubes, igniters and a transformer costs
about $40 and gives repeatable results in 1-5 minutes so for me that's the
way to go!

Oh, and before anyone mentions press&peel I urge them to try and do a board
with one or two tracks going between two of the pads on a 2.54 spaced DIP
without having to correct the board and cross your fingers.

   KreAture

{Original Message removed}

2003\04\02@020244 by

flavicon
face
Kyrre Aalerud wrote:

>Oh, and before anyone mentions press&peel I urge them to try and do a board
>with one or two tracks going between two of the pads on a 2.54 spaced DIP
>without having to correct the board and cross your fingers.

Whould you say that there is any major difference in this
regard between "PnP BLUE" and "PnP WET" ?

Jan-Erik Söderholm.

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2003\04\02@060950 by Kyrre Aalerud

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Sure, but you still need to cross your fingers and hope you have ironed it
enough...
And, there are limits to how fine tracks it is possible to reproduce with
p&p...

   KreAture

{Original Message removed}

2003\04\02@071900 by Hugo Harming

flavicon
-----Original Message-----
From: RemoveMEjdharspamBeGonespamRemoveMEENGMAIL.UWATERLOO.CA [KILLspamjdharspamBeGonespamENGMAIL.UWATERLOO.CA]
Sent: Tuesday, April 01, 2003 11:58 PM
To: @spam@PICLISTSTOPspamspam@spam@MITVMA.MIT.EDU
Subject: Re: [EE]: Etchant tank


>>> Would an inkjet printer work? Or are there any methods to produce a positive
>>> film with an inkjet?
>>> Time is not really an issue, these would all be one off's so it's ok. If I
>>> wanted to go with a 'standard' lamp, what kind of lamp is that exactLY?
>>> Halogen? Just a regular Incandescent light bulb? And how much are UV lamps
>>> typically?


I get consistent good results from a HP895Cxi, printing Eagle layouts to inkjet transparencies.
Smallest reliable track width/track spacing is about 12 mils.
I print two copies of the layout and tape them together. I'm not really sure if this is needed, but it gives me some extra scratch protection and UV block.

I use an old Philips half-body sunbed (or whatever it's called in english) for the exposure.

Board face up, double transparencies, sheet of glass for good contact. About 15 cm board to tubes - any closer gives uneven exposure.
Exposure time differs with make of presensitized board, but is in the 2,5 to 3 minute range.
Then a quick dip in developer, I'd say 10 - 20 s.
I've had an etching tank made from 5 mm glass, holds just over 2 l. Normal fish tank heater (100 W, thermostat slightly remodeled), air pump and 'bubble block' (whitch dissolves over time but are cheap).
Etchant is natriumperoxidsulfat in swedish.
Etching takes 10 - 15 minutes depending of state of etchant.
I cut boards to size with a guilliotine type paper cutter.

This setup gives crisp looking boards in reasonable time.

Get a more powerful heater if you can find/fit it, as warmup time is long with my setup.


Anyways, thats just how I do it.

Best of luck!

/Hugo

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2003\04\02@072727 by Alan B. Pearce

face picon face
>I use an old Philips half-body sunbed (or whatever
>it's called in english) for the exposure.

(shouts over shoulder) "Sorry darling, I'm using the sunbed today, it's
printed circuit board day" :))

>Etchant is natriumperoxidsulfat in swedish.

Sodium Persulphate perhaps ???

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2003\04\02@164757 by Peter L. Peres

picon face
>Complete waste of time - you get uneven coating, and dust spots. DOn;t =
>even think about it unless you have a cleanroom and a dip-tank.=20 =20

Okay, that is an opinion. I use CRC spray-on photoresist and get great
results. You do not need a cleanroom, you need to preheat the board to
~60C before spraying each layer. I have traces down to 20 mils without
trouble. No uneven coating, no dust spots.

Peter

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2003\04\02@164803 by Peter L. Peres

picon face
My problem with pre-sensitized boards is a) price and b) the fact that the
resist chips off if I try to cut them to shape before exposure. My boards
are small and I can use a sheet of pre-sensitized for a long run of
prototypes if I can cut it. But I cannot. So I use the spray.

Peter

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2003\04\02@171633 by Kyrre Aalerud

flavicon
face
From: "Peter L. Peres" <plpspamBeGonespamspamBeGoneACTCOM.CO.IL>
> My problem with pre-sensitized boards is a) price and b) the fact that the
> resist chips off if I try to cut them to shape before exposure. My boards
> are small and I can use a sheet of pre-sensitized for a long run of
> prototypes if I can cut it. But I cannot. So I use the spray.

How to you cut it when you manage to get the photoresist to chip?
I cut mine with a sharp knife making a deep groove on each side of board and
simply snap it.
On thinner boards like 0.8mm I simply cut with a large pair of scissors.

   KreAture

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2003\04\02@174753 by Jinx

face picon face
> >I use an old Philips half-body sunbed (or whatever
> >it's called in english) for the exposure.
>

Alan B. Pearce wrote in sunblock on his leg

>
> (shouts over shoulder) "Sorry darling, I'm using the sunbed today,
> it's printed circuit board day" :))

Ay-oop lad, surely thas don't need t'sunbed in north of England ?

"Sitting in an English garden waiting for the sun
If the sun don't come, you get a tan from standing
in the English rain"

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2003\04\02@193815 by Vern Jones

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face
Hello All,

I use 3 Phillips TLD 15W/05 bulbs in a home made fixture that has an
exposure area of 12" x 18" (45.7 x 30.5 cm.)  spaced 6" (15 cm.) below
the exposure surface. I ran 3 - 1.5" x 3.5"  (8.9 x 3.8 cm.) pieces of
wood through the table saw at an angle to cut a parabolic shape in the
wood pieces the length of the lamps. Then I glued foil to the parabolic
surfaces for reflectors. The lamp fixtures were some low priced 15W
florescent fixtures that I used for parts.  I place the film
(transparency) on the glass surface, the circuit board on top emulsion
side down with a piece of foam rubber on top,  then a lid (painted flat
black) to hold the sandwich of glass, transparency, board and foam rubber
together. Makes a light tight package to keep UV out of the eyes and hold
the board in contact with the transparency.

I get very consistent exposures this way (2 min. 25 sec.) by using my
darkroom timer to control the exposure lamps.  I like this as there are
no wasted boards. I use transparencies produced by an inkjet printer for
all of my in house boards. Otherwise it is Gerber files to the board
house.

Vern



Jinx wrote:

{Quote hidden}

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2003\04\03@024743 by jim barchuk

flavicon
face
Hi Peter!

On Thu, 3 Apr 2003, Peter L. Peres wrote:

> My problem with pre-sensitized boards is a) price and b) the fact that
> the resist chips off if I try to cut them to shape before exposure. My
> boards are small and I can use a sheet of pre-sensitized for a long run
> of prototypes if I can cut it. But I cannot. So I use the spray.
>
> Peter

That 'long run of prototypes' is unclear.

Does it mean making a series of similar boards, with slight changes, until
a circuit ir right?

Or meaning making a bunch of boards all identical, but low volume enough
to not make sense to give to a board house?

If the former, then you're doing it right of course and can ignore the
next paragraph. :) I'd guess it's easier to get a uniform coating on a
small board, no more than one 'spray width,' rather than back-and-forth to
cover a larger board. Maybe that's why you get better results.

If the latter then you should be using a step/repeat technique with a
larger piece of film, larger board to start with, do all processing except
cutting into smaller boards which is the last step.

Have a :) day!

jb

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2003\04\04@051434 by Peter L. Peres

picon face
jim barchuk wrote:

> If the former, then you're doing it right of course and can ignore the
> next paragraph. :) I'd guess it's easier to get a uniform coating on a
> small board, no more than one 'spray width,' rather than back-and-forth
> to cover a larger board. Maybe that's why you get better results.

By prototypes I meant prototypes, as in successive versions of a board,
until it works right.

The uniform coating works differently for photoresist. You spray so far
away that the speed of the droplets is near zero at the board. So you
cover a lot of surface (20x30cm is easy). It's all in the wrist. Uniform
coverage is more important than layer thickness, each layer just barely
covers the board (hard to see in subdued light). I do 3 layers, with 1
minute between them, the board being on a heater. Beware the fire risk.

Peter

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2003\04\04@052248 by Peter L. Peres

picon face
>How to you cut it when you manage to get the photoresist to chip? I cut
>mine with a sharp knife making a deep groove on each side of board and
>simply snap it. On thinner boards like 0.8mm I simply cut with a large
>pair of scissors.

I cut the board to shape first then I coat it with photoresist. I use
shears, a jeweller's saw, and files and abrasive paper to obtain the right
shape. Then I tack it to a piece of stiff cardboard and it stays there
until after exposure (for one sided boards). Two sided are harder to
handle.

Peter

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2003\04\04@140957 by Dwayne Reid

flavicon
face
At 12:16 PM 4/4/03 +0300, Peter L. Peres wrote:

>The uniform coating works differently for photoresist. You spray so far
>away that the speed of the droplets is near zero at the board.

I've made this offer before and am doing so again: if anyone in the
Edmonton, AB, Canada region wants to prep their own photo-sensitive PCB
material, they can do so in my shop on weekends.

We purchase DuPont Riston 4215 film in large rolls (each box contains 2-
500' rolls) and have the appropriate laminator for applying the film to the
boards.

Its a small prototype system - all the board prep is completely
manual.  Count on it taking 2-3 hours to prep and laminate 10 sq feet of board.

But its cheap: the film costs about $1 per foot and you supply the
labor.  Its best if you supply your own PCB material but I keep 3 or 4
sheets on hand if you don't have any.

You can also expose and develop the board in my shop if you want.  The
etcher is empty right now but if we have it ready to go, you can etch as well.

For what its worth, I hardly use the photo etch system any more.  One of
the guys here (Ryan) has a neat little setup that mills copper-clad
board.  It has its drawbacks but it is less hassle than the photo
setup.  On the other hand, the photo setup is *much* more accurate and does
not leave large copper islands like the mill does.

We use both systems but the mill now does most of our quick prototype boards.

dwayne

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2003\04\04@142000 by Dal Wheeler

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----- Original Message -----
From: "Dwayne Reid" <RemoveMEdwaynerspamspamPLANET.EON.NET>
> For what its worth, I hardly use the photo etch system any more.  One of
> the guys here (Ryan) has a neat little setup that mills copper-clad
> board.  It has its drawbacks but it is less hassle than the photo
> setup.  On the other hand, the photo setup is *much* more accurate and
does
> not leave large copper islands like the mill does.

Is this a hand built mill?  Pictures?  Just curious as I'm building aone to
mill small plastic and wood --Hobby stuff...

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2003\04\04@153148 by Dwayne Reid

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At 12:18 PM 4/4/03 -0700, Dal Wheeler wrote:

>Is this a hand built mill?  Pictures?  Just curious as I'm building aone to
>mill small plastic and wood --Hobby stuff...

The mill itself started life as a CNC engraving machine, just like those
that you see in malls everywhere (name tags, etc).  The electronics inside
failed (spectacularly!) and the company manufacturing it also failed - they
are no longer around.  Ryan bought the dead machine for a few hundred dollars.

I wrote a simple stepper controller for him (1- 12c508 per axis) and he is
driving the whole rig from the parallel port of an old DOS machine running
Stepster (that he has also modified).

The original stepper motors, drivers and power supply were all OK, as was
the spindle motor.  Ryan did change pulleys so as to get the spindle speed
much higher.

There is a fair amount of work involved to take the output of the CAD
system and turn it into G-code - it takes Ryan about an hour to do a
moderately complex board.  I'll get him to document the procedure in a form
suitable for public viewing one of these days.

Milling 1 side of a moderately complex board (4"x6", 107 components, 328
holes) takes less than an hour.  The only human touch required is to change
the mill bit for drill bits (< 10 secs each change) at the end of the
process.  Then load a new blank and hit start again.

I'll see about getting pictures up (also One Of These Days).

dwayne

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2003\04\04@155608 by Timothy Box

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dwayne

"Milling 1 side of a moderately complex board (4"x6", 107 components, 328
holes) takes less than an hour.  The only human touch required is to change
the mill bit for drill bits (< 10 secs each change) at the end of the
process.  Then load a new blank and hit start again."

Just out of curiosity can you mill pads at 0.5mm pitch?

Tim

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2003\04\04@182236 by Chris Loiacono

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Hey Dwayne:

Not that I intend to show up at your door on Monday or anything, but what
exactly is this photo laminate system and how does it work? Feel free to
tell me to go look it up on a web site somewhere, that would be fine - I'm
just too lazy (read: run down)at the moment to go hunting.

Chris

> We purchase DuPont Riston 4215 film in large rolls (each box
> contains 2-
> 500' rolls) and have the appropriate laminator for applying
> the film to the
> boards.
>
> Its a small prototype system - all the board prep is completely
> manual.

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2003\04\04@194709 by Brendan Moran

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>The mill itself started life as a CNC engraving machine, just like those
>that you see in malls everywhere (name tags, etc).  The electronics inside
>failed (spectacularly!) and the company manufacturing it also failed - they
>are no longer around.  Ryan bought the dead machine for a few hundred dollars.

Now you've got me really curious:  How fine of a trace can you cut with
this machine?  Like... can you do 12 mil?

The other question is: Is there a converter from Gerber to CNC code?

--Brendan

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2003\04\04@235241 by Dwayne Reid

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At 09:56 PM 4/4/03 +0100, Timothy Box wrote:
>dwayne
>
>"Milling 1 side of a moderately complex board (4"x6", 107 components, 328
>holes) takes less than an hour.  The only human touch required is to change
>the mill bit for drill bits (< 10 secs each change) at the end of the
>process.  Then load a new blank and hit start again."
>
>Just out of curiosity can you mill pads at 0.5mm pitch?

Not a hope.  It can handle simple SOICs (0.05" pitch) but that is about
it.  The problem is not the resolution but rather the mill bit.

On the other hand, the photo process would do .05mm (~.020") pitch easily.

As I mentioned earlier, having both techniques available is useful for
those sudden rush projects when I simply can't wait the 3 days for boards
from APC.

dwayne

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2003\04\04@235246 by Dwayne Reid

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At 06:23 PM 4/4/03 -0500, Chris Loiacono wrote:
>Hey Dwayne:
>
>Not that I intend to show up at your door on Monday or anything, but what
>exactly is this photo laminate system and how does it work? Feel free to
>tell me to go look it up on a web site somewhere, that would be fine - I'm
>just too lazy (read: run down)at the moment to go hunting.

Kepro has a good description of the whole system, although only the
laminator came from them.

I'm going to take the easy way out and simply copy a post I made on the
Homebrew PCB forum last year:

The photo process uses DuPont Riston 4215 laminate film, a much modified
Ibico laminator supplied by Kepro, developer is Soda Ash (Potassium
Carbonate), etch is Ammonium Persulphate, stripper is Caustic Soda (Sodium
Hydroxide), drilling is by Gordon Robineau's PCB drill.  This is a very
mature process - we have made thousands of boards with the process over the
past 18 years or so.

The downside is the prep time.  The raw board has to go through a 5 step
cleaning process before being laminated.  The negative has to be done at a
local print shop - someone takes over a floppy and comes back with a
negative.  Drilling used to be done by hand but is now with Gordon
Robineau's seriously cool PC drill - I simply feed it the drill file from
my CAD program.  The bottom line is that it is a half day process from
start to finish - 1 board or 20 boards takes about the same amount of
time.  The boards turn out perfect - it is a great process.  But it ties up
somebody for that half day.

One of my techs purchased a dead engraving machine from the local repair
outfit.  The computer part of it was completely dead but the mechanical
stuff was just fine.  He cut the stepper motor drive section off of the CPU
card - he now had a stepper controlled X-Y-Z mill, complete with stepper
drivers.  I wrote a simple PIC stepper controller (12c508) that takes in
step and direction commands and generates the step sequences for the
stepper drivers.

Ryan spent a couple of months in his spare time learning how make the
system work.  He now uses a somewhat modified version of Kevin Carroll's
Stepster as the G-code interpreter - its what drives the stepper controllers.

It takes Ryan about 40 minutes to process the plot file from my CAD package
into G-code suitable for feeding to Stepster.  I don't know the exact steps
involved: I do know that he uses Corel Draw, Adobe Photoshop, and Desk-NC
in the process.  I'll document the procedure sometime soon and post it.

The milling bits are standard high speed steel engraving machine bits.  For
milling PC boards, Ryan has the bits ground to what the re-grinder calls a
.005" flat.  That means the tapered bit does not come to a point but
instead has a .005" wide flat surface at the very tip of the
bit.  Apparently any finer than that results in a tip that is too fragile.

Milling a board takes anywhere from 20 minutes to an hour, depending upon
the size of the board and how much copper has to be removed.  The boards
turn out OK - Ryan can get a trace between 2 IC pads reliably.  The sides
of the traces are somewhat jagged - not perfectly smooth like the photo
process.  The isolation path is probably about 0.015" or so - it means you
have to take a little care when soldering to make sure you do not bridge
the gap.

The boards are drilled after the isolation paths have been milled.  Ryan
simply changes the milling bit to a drill bit, loads the (edited) .NCD
file, hits GO, and walks away.  When all the holes for that size have been
milled, he changes the bit to the next size and the machine drills
those.  The PC board is not moved between any of those steps so
registration remains perfect.

We now rarely use the photo process!  The milled boards don't look quite as
nice as the photo etched boards but it takes less time to get a board made
and the milled board takes only about 1/4 of the total man-hours of actual
labor.

I've been planning on doing a bit of a write-up on the whole process - lack
of time has stopped me.  But I'll try to get some pictures of actual boards
made on the machine - soon.

dwayne

PS - Ryan has done one hell of a great job in turning a dead engraver into
a wonderfully useful CNC tool.  He was the driving force behind this - I
assisted him with some things but Ryan deserves all the credit.  I want to
be clear on this - it was his idea, he found and purchased the dead
engraving machine, he figured out how to make the software available to him
do the job he needed.

dwayne

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2003\04\04@235251 by Dwayne Reid

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At 04:44 PM 4/4/03 -0800, Brendan Moran wrote:
>>The mill itself started life as a CNC engraving machine, just like those
>>that you see in malls everywhere (name tags, etc).  The electronics inside
>>failed (spectacularly!) and the company manufacturing it also failed - they
>>are no longer around.  Ryan bought the dead machine for a few hundred
>>dollars.
>
>Now you've got me really curious:  How fine of a trace can you cut with
>this machine?  Like... can you do 12 mil?

Barely.  20 mil is better.

>The other question is: Is there a converter from Gerber to CNC code?

I'm not aware of any inexpensive software for doing this.  I'd like to find
some - Ryan has spent a lot of time evaluating the various shareware
packages out there but so far has not found anything suitable.

He's now talking about writing his own version but he's about as busy as he
can handle and it won't happen anytime soon.

dwayne

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2003\04\06@131619 by Mike DeMetz

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www.imsrv.com/deskpcb/


> The other question is: Is there a converter from Gerber to CNC code?

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2003\04\07@003537 by Frank Collingwood

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I built one out Perspex (Plexiglas) - it consists of 3 vertical rectangular
tanks, with a small air gap between each. The first tank is for developing
the boards, the middle tank for rinsing, and the last one for etching. The
developing and etching tanks have aquarium bubble strips in the bottom, the
etching tank also has an aquarium heater. The bottoms of each tank are
slightly inclined, with taps at the lower ends to drain the tanks.

I use spray photoresist for the boards, and use tranparancies produced on my
bromide camera.

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