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'[EE]: PCBs using toner transfer paper'
2000\07\05@010724 by Alberto Stapelfeld

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Hi, I'm planning to make some PCBs. It seems the easiest method is using
toner transfer paper. How easy is it?, I  would like to use some TSOP ICs,
Could I get enough resolution using this method?

Alberto.

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2000\07\05@095637 by Francisco Armenta

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Alberto

I make some proofs whit toner transfer metod and work fine.

check this url: http://www.sysameri.com/marcelo/placa.htm

Regards

Francisco Armenta

Alberto Stapelfeld wrote:
{Quote hidden}

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2000\07\05@141006 by Mark Willis

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TSOP shouldn't be any problem at all;  Your resolution is 300DPI on a
300DPI printer, I use 2 pixels wide at least (3 is better) - 8 mil
(0.008") traces look pretty good under this method, the 10 mil text I
put as markings on my boards is quite readable.  (I go to 24 point more
often, the 10-point works where tiny's needed.)  Strategy is something
to think on, if you see that your laser printer prefers to print traces
one way but not the other etc., remember that.

Plan to use as small a drill bit as you can get that the pins will fit
through, if possible - makes for better solder joints.  (a 1/16" bit is
really NOT all that good.  Enco, at Use-Enco.Com or UseEnco.Com, had
1/32" HSS bits for cheap, or bug me and I can look at Boeing Surplus for
ya for Carbide bits.  HSS bits dull, but can be re-sharpened - Carbide
bits shatter, OTOH.)  2-sided boards are do-able, if toughish;  Also, I
use 15 mil pad holes (Makes starting even 125-mil holes accurately, a
LOT easier!)  (i.e. even the bolt-down hole for a DE-9 connector, I size
down to 15 mils on the pad master - they you drill starting with a
smaller drill bit and you are CENTERED.  10 mils is too small, you do
get some smearing and some holes dissapear then.)

I make do with a regular "clothes iron" right now - A laminator would be
a huge improvement, plan that soon enough, for small boards an iron'll
do - It's sort of an art, expect to have problems and get to strip the
toner off some boards and re-toner them until you get it right.  Too
much heat is bad, with too little the etch resist falls off the board.
Acetone (Fingernail Polish remover) does the job, to pull the toner.

I'm about to try the new cheaper paper (2-sided magazine cover stock) on
some boards, will report on how well it works.  3-4 cents a page for the
stuff.

 Mark

Alberto Stapelfeld wrote:
> Hi, I'm planning to make some PCBs. It seems the easiest method is using
> toner transfer paper. How easy is it?, I  would like to use some TSOP ICs,
> Could I get enough resolution using this method?
>
> Alberto.

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2000\07\05@143502 by Francisco Armenta

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> I make do with a regular "clothes iron" right now - A laminator would be
> a huge improvement, plan that soon enough, for small boards an iron'll
> do - It's sort of an art, expect to have problems and get to strip the
> toner off some boards and re-toner them until you get it right.  Too
> much heat is bad, with too little the etch resist falls off the board.

MARK
I use "WC paper" between "clothes iron" and paper, whit heat regulator
of "clothes iron" to max, the "WC paper" avoid to slide the toner

> I'm about to try the new cheaper paper (2-sided magazine cover stock) on
> some boards, will report on how well it works.  3-4 cents a page for the
> stuff.
>

I get very good quality whit Fax paper

Regards

Francisco Armenta
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2000\07\06@120939 by Randy A.

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Francsico:

When you say you get good results with FAX paper,  do you mean the thermal
fax paper cut to size and run thru a laser printer?  And exactly what are you
calling "WC" paper, I have had some problems with the pattern moving when I
iron it on even with a piece of regular paper between the iron and the sheet
with the pattern.

Thanks for any help,

Randy Abernathy

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2000\07\06@130346 by Francisco Armenta

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"Randy A." wrote:
>
> Francsico:
>
> When you say you get good results with FAX paper,  do you mean the thermal
> fax paper cut to size and run thru a laser printer?

Randy

Yes it is, the more coated side of paper must be recive the toner,
after printing the thermal fax paper was "darked", don´t worry this is
normal

>  And exactly what are you
> calling "WC" paper, I have had some problems with the pattern moving when I
> iron it on even with a piece of regular paper between the iron and the sheet
> with the pattern.
>
Sorry for my bad english "WC PAPER" = "toiled paper" or you can use a paper napkin


Francisco


> Thanks for any help,
>
> Randy Abernathy
>
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2000\07\06@153041 by Randy A.

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Franscico:

Thanks I thought that "WC" might be for water closet but wanted to make sure.
 I have been using paper towels with pretty good results.  The FAX paper
thing was what got my attention.  That is a LOT cheaper than label backing,
or the Toner Transfer Paper made for the job.

Thanks again,
Randy Abernathy

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2000\07\06@191504 by John Mullan

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The FAX paper got my attention as well.  However, I also like the
suggestion made about using high gloss magazine stock paper.  If that works
well I will stop using the expensive stuff!!!!

John Mullan


{Original Message removed}

2000\07\06@195330 by David VanHorn
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At 07:12 PM 7/6/00 -0400, John Mullan wrote:
>The FAX paper got my attention as well.  However, I also like the
>suggestion made about using high gloss magazine stock paper.  If that works
>well I will stop using the expensive stuff!!!!

"Honest boss, the subscription to penthouse was just so we could make
circuit boards!"

:)

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2000\07\07@134559 by Sumiec Jerry

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 Does anyone had any experience with Technik's Press-n-Peel??  This
discussion has sparked my interest in creating a couple of boards for some
projects that I've done, but I've always used wirewrapping and have wanted
to try making my own PCBs...  I've read some mixed reviews about problems
with getting the toner to stick to the copper with the toner transfer
paper... Is this typical?  Or maybe they just didn't prepare (clean) the
copper properly before applying the transfer paper?

Thanks,
Jerry

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2000\07\07@174743 by Randy A.

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Jerry:

You are correct to think that preparation is the key also they heat and time
you leave the heat on the transfer to the board are also very important.  I
haven't used the Press-n-Peel as such because it is usually so expensive.  I
have had pretty good luck with the slick backing material used for laser
label sheets.  I use the 3 1/2" diskette labels and just peel off the labels
and run the backer thru my HP laser printer.

As you have seen there are many other approaches to this and I am going to
give some of them a try.  Of course if you are looking to do more than one or
two boards, making a negative or positive and using the photo-etch method is
much more efficient and usually better overall.  I have the capability for
both but when I am doing a one shot prototype I find the toner transfer gets
it done quicker although sometimes "dirtier".

Regards,
Randy A.

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2000\07\10@094859 by Sumiec Jerry

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What do you find gives you the best results for using label backing?

Paper towel between label backing and iron?
Amount of time with iron, using the max setting?
After ironing, cool down before you put it in water to remove backing?
Does the backing just slip off or can you peel it off?

These are just a few of the things that I've found to be conflicting between
the testimonials I've read...

Also, how easy is it to do double sided??  can it be done one side at a
time, or would you maybe need two irons pressed together?  I thought about
this a little bit, you could just put 2 reference holes in your layout
software, then drill the holes on the board to line up the layout on each
side..

Sorry for all the questions.  I'll probably just run up to Radioshack and
pick up a board or two and just try a few different ways to see how the
toner sticks...  Just want to get a good idea of what I need to try...  I
may also buy some of that Press-n-Peel to see how it goes.  My quantities
will be rather small, so the price doesn't concern me too much (at first
anyway).

Thanks,
Jerry

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2000\07\10@111827 by Bob Blick

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Regarding Press'n'Peel and other methods of special paper, some things
that work for me:

Small boards OK, big boards not so OK.

Use a piece of Press'n'Peel bigger than your board but not a whole sheet.
Attach it to a sheet of paper with a laser label. If you do a test print
on paper you know where to attach it.

If you are in a high humidity area forget about Toner Transfer System,
it curls and cracks too much. Maybe if I lived in Sacramento it'd work.
The Press'n'Peel is plastic and does not have that problem.

The real secret I can offer is:
Alberta Printed Circuits :-)

Cheers,

Bob

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2000\07\10@154654 by Mark Willis

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Sumiec Jerry wrote:
> What do you find gives you the best results for using label backing?

Haven't used that.

> Paper towel between label backing and iron?

I do use laser printer paper or paper towel between the iron and the
papers I do use.

> Amount of time with iron, using the max setting?

30-40 seconds, I think?  Also pre-heat the PCB for 10 seconds or so.  (I
sorta have to be there, sorta do it experientially not by timer.  Been
reworking the computer room for the last week, still much to do, then
I'll get back to board making.)

> After ironing, cool down before you put it in water to remove backing?

Usually <G>

> Does the backing just slip off or can you peel it off?

If you peel, you lose traces - go do something else for 10 minutes and
"slosh" the water a little when you come back, it'll be free by then.

> These are just a few of the things that I've found to be conflicting between
> the testimonials I've read...
>
> Also, how easy is it to do double sided??  can it be done one side at a
> time, or would you maybe need two irons pressed together?  I thought about
> this a little bit, you could just put 2 reference holes in your layout
> software, then drill the holes on the board to line up the layout on each
> side..

I do 2 over-sized pieces of paper - line them up and tape or staple them
to each other, sandwiching the PCB between them.  Then I iron one side
on, flip and iron the other side.

Try this: Make a test slip or 3 with some "spare" parts of your film and
experiment on some scrap PCB bits - get your settings right with those,
you'll prefer not messing up your master PCB film (little 1" square
fragment of film can tell you a LOT about what works with YOUR iron at
YOUR settings!)

Oh.  And get rid of the water in your "Steam iron" if any, before
starting <G>  That won't help at all.

> Sorry for all the questions.  I'll probably just run up to Radioshack and
> pick up a board or two and just try a few different ways to see how the
> toner sticks...  Just want to get a good idea of what I need to try...  I
> may also buy some of that Press-n-Peel to see how it goes.  My quantities
> will be rather small, so the price doesn't concern me too much (at first
> anyway).

Good way to go!

> Thanks,
> Jerry

 Mark

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2000\07\10@202252 by Randy A.

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Jerry:

You are right, different people do have different ways of doing the toner
transfer method.  I have had fair results with the label backing sheets and I
use a paper tower between the iron and the board.  I let the board cool down
completely before putting it in water but have also just peeled the sheet off
of it but have had the toner come off the board that way with really thin
traces.

Doing the double sided boards are not all that hard as long as you put
accurate targets on both sides to line up with the edges/corners of the
board.  You must have a steady hand for this as well.  :-)

I have CircuitMaker Pro and TraxMaker Pro so doing the targets etc. is not a
problem.

However, if you are looking for really good professional looking PC boards
the photo etch method for is still the best for hobbyist types.  I actually
use my boards in my business in the machinery I retro fit and repair and
haven't had any problems with the toner transfer ones as yet.

Randy

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2000\07\14@082746 by Sumiec Jerry

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Well, I gave it a shot this past week using label backing...  I actually had
some success after the third try, but the results still weren't that great.
I'll probably do some more experimenting though.

 The first two times I tried to make the Modified ICD board on
http://www.piclist.com, and about 80% of it came out really clear, but the
remaining 20% was a mess...

The first time I just put it on for about 1 minute with the iron on full and
with a piece of paper towel folded once in between the label backing and the
iron.  I let it cool then soaked it in water for about 30 minutes.

The second time I ironed it for about 2-3 minutes rotating it 180 degrees
half way through (To assure equal exposure to the heat).  Cooled it and
soaked it in water for 45 minutes or so.

Then finally I figured I'd try an easier layout, so I whipped up a little
circuit with a 16f84 and 8 LEDs for outputs (Just to have a working product
when I was done :)  )....  This time I heated it for about 3-4 minutes,
rotating it a couple of times...  All the traces came out, but some where
broken here or there, so I went back with a marker and touched it up... I
finally had something I could etch!   So I etched it and it turned out
-okay-...  Drilled the holes, soldered it and wrote a little led chaser
program and it worked fine...

I'll probably give it a try a couple more times, then maybe try the transfer
paper and see if that makes a big difference.  If not, maybe I'll give the
photo method a try...

Jerry

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2000\07\14@093910 by Mitchell D. Miller

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paper and see if that makes a big difference.  If not, maybe I'll give the
> photo method a try...

I just did my first PCB using the photo method, and feel like I had GREAT
luck.  I had 16 mil traces, and every one of them came out great.  Even had
a ground plane under my OSC with 10 mil isolation, and it etched
beautifully.  I printed my circuit 200% on a laser printer, then took it to
a photocopier and reduced it 50% as it printed onto the transparency.  I cut
the transparency to slightly larger than the board and exposed it according
to Mfr. directions.  I used the MG Checmicals starter kit and their exposure
light.  Exposure and development of the board went fine ... etching was
quite slow because I didn't keep my etchant (ferric chloride) warm.  As a
result, some of the edges weren't very sharp, but at 16 mil, they were still
very intact, and without a magnifying glass, you'd never see where the
etchant crept under the resit.

Nice thing about MG Chemical's stuff is that it uses a Positive photo
process ... transparency looked exactly like the copper I wanted to keep.

I drilled the board, mounted the parts, and it worked after one slight
modification ... I forgot to put the 1Mohm resistor across the resonator's
pins.  After that mod, the board has been running for several days w/o
glitch.

-- Mitch

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2000\07\14@141002 by Lawrence Lile

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This is a typical experience with toner transfer paper - much frustration,
unless you have that "touch".
Some people have nothing but luck, and can't understand why 90% of us end by
waddding up our toner transfer paper, selling our homemade transfer presses
to the T-shirt crowd, and buying a photo etch kit.

go to http://www.kepro.com  and get yourself set up with a photo etch kit.  You
won't regret it.


--Lawrence

{Original Message removed}

2000\07\14@153604 by Mark Willis

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Mitchell D. Miller wrote:
<snip>
> light.  Exposure and development of the board went fine ... etching was
> quite slow because I didn't keep my etchant (ferric chloride) warm.  As

My lowest-budget trick here:  I use a Rubbermaid low rectangular plastic
container to etch in - I fill the sink with HOT water, about 5 minutes
early - then drop the board into that hot ferric chloride once it's
warm.  Works pretty well.  Don't over-fill the plastic container with
etchant! <G>

 Mark

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2000\07\14@161012 by Bob Blick

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On Fri, 14 Jul 2000, Mark Willis wrote:
> My lowest-budget trick here:  I use a Rubbermaid low rectangular plastic
> container to etch in - I fill the sink with HOT water, about 5 minutes
> early - then drop the board into that hot ferric chloride once it's
> warm.  Works pretty well.  Don't over-fill the plastic container with
> etchant! <G>

A microwave oven works well for heating the etchant, but your etchant ends
up smelling like food, and vice-versa :-)

-Bob

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2000\07\14@161849 by Gordon Varney (personal)

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> Mitchell D. Miller wrote:
> <snip>
> > light.  Exposure and development of the board went fine ... etching was
> > quite slow because I didn't keep my etchant (ferric chloride) warm.  As
>
> My lowest-budget trick here:  I use a Rubbermaid low rectangular plastic
> container to etch in - I fill the sink with HOT water, about 5 minutes
> early - then drop the board into that hot ferric chloride once it's
> warm.  Works pretty well.  Don't over-fill the plastic container with
> etchant! <G>
>
>   Mark

Use a green Scotch-Brite on the circuit board, make it shine, before you
place the toner. Go directly to the etchant as soon as possible. DO NOT get
oil from your hands on the board. Your board will etch twice as fast and the
toner will adhere much better.
(the shinier the better)(you can buy Scotch-Brite from your local grocery
store, look in the pots and pans cleaning section)
You will be amazed at the difference in etching quality.

Gordon Varney B.S.E.E.
tel: 573-243-5186

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2000\07\14@165547 by Thomas McGahee

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Since the yearly discussion on toner transfer methods has come
up again, forgive me if I just drag out the post I sent last year,
with a few minor changes:

Subject: PCB Methods: Iron On Transfers
Date: Wed, 24 Mar 1999 13:02:18 -0500

Dear PICsters,

One method for making printed circuit boards is to use commercial
iron on transfer products, such as DynaArt Transfer Paper.

DynaArt Designs
3535 Stillmeadow Lane
Lancaster, California  93536-6624

http://www.dynaart.com/

The DynaArt paper is specially treated on one side. This side has
a thin layer of water-soluble material coating it. The idea is that
you print the reversed toner image on this coated side, then
use heat to transfer the toner to the copper. Once the board has
cooled down, you soak it in water. The water-soluble layer
dissolves, releasing the paper and leaving the toner still
attached to the copper. It works quite well if you follow a few
guidelines.

I have been using the DynaArt Transfer Paper for a couple of years.
When I first started I used an iron and got mixed results. Smaller
boards generally came out OK, but anything much larger than the
iron itself created a problem.

I finally stopped playing around with the iron and ordered the
SuperFuser, which is a laminator modified for a different temp range,
and much slower feed rate.

The advantages of the SuperFuser are:
1) consistency of results, and
2) once it is loaded you can do something else with your time.

Disadvantage is the cost, which is about $250.

The SuperFuser once properly adjusted for temperature, gives
me excellent boards. Note that different brands of toner require
slight changes in the temperature setting!

In the interest of helping others, here is a quick outline of
how I do my own PC Boards.

1) Clean the PCB blank vigorously with a Scotchbrite pad.
This mechanical cleaning is very important. The pcb blank should
be shiny, and when water is applied, the water should cover the surface
uniformly.

2) When the mechanical cleaning is done I
then clean it with a little TSP solution(Tri Sodium Phosphate). This
helps remove fingerprints, grease, etc. Rinse thoroughly in running
water to remove all chemicals.

3)I then wipe dry with a CLEAN cotton wipe, making sure no lint
remains. Make sure *both* sides are completely dry.

4) I preheat the board with either a heat gun by waving it evenly
over the surface, or by placing it in a little oven I have that
was originally designed for drying glassware. This pre-heating
helps, because when a cold board is placed in the SuperFuser there
is a large temperature gradient, and the part of the board that goes
in first would otherwise not get as evenly heated as the last
part of the board.

5) The DynaArt paper is placed face-down on the copper side of the
pcb blank. I have the paper cut to the exact size of the board,
and I line it up and hand-feed it into the SuperFuser. I maintain
a slight forward pressure to get the sandwich of pcb and toner paper
started through the rollers. Once about 1/4" has been fed in, then I
leave the SuperFuser alone. I use no tape or adhesive to hold the
paper on. The pressure of the rollers is sufficient.

5) When the board exits the SuperFuser I turn it around 90
degrees and run it through again immediately. If you do not do this,
then you will sometimes find that long runs that are parallel
to the board travel direction tend to lift off.

6) When the board comes out of the SuperFuser the second time,
I let it sit on a dry cloth for about three minutes. This allows
the board to cool slowly. Rapid cooling can cause the pattern to
pull away from the board.

7) Once the board is cool to the touch, then I place it in a pan
of room temperature water and let it sit for as long as it takes
for the paper to float loose. Avoid the temptation to speed the
process up by aggressively agitating the water, as this can cause
sections to lift. A minute or two is normally long enough.

**** Additional info ****

You might also find it useful to preheat the transfer paper
that has the image on it. This preheating helps to cause any
tiny toner pinholes that may be present to disappear as the
toner melts slightly. You have to be careful not to overdo
this preheating. The idea is to allow pinholes to close up,
but not to allow any dimension changes in the toner image.

If you experience any problems with dimensional shrinkage of
the image, then you might want to preheat the transfer paper
*before* running it through the Laser Printer. That will cut
shrinkage down by at least half. I usually make smallish PCBs,
so I don't often have to resort to this.

As regards toner. I use an el-cheapo re-manufactured cartridge
to do my proofs, but the actual tranfer is done using an
original cartridge. I prefer the cartridges that have the
extra-fine toner. These are sometimes sold as 'extra black
graphics cartridges', or 'specially formulated for high
resolution graphics work' or something to that effect. I happen
to use a 1200 DPI (true resolution) Lasermaster Unity 1000
printer. I have found that the 300 dpi printers are not high res
enough. 600 DPI is useable. 1200 DPI is excellent. This goes
not only for direct tranfer PCB work, but also if you are
preparing your own 1:1 transparencies. When I do photographic
versions of my PCB designs I usually produce artwork that is
1.5:1 or 2:1 and then have it photographically reduced to
actual size. This allows for very fine lines, such as those that
go between IC pins.

And, it goes without saying, don't forget to make sure that the
image you PRINT is a mirror image. I have had my fair share of
times when I rushed a job only to discover that I had failed to
flip the image first. I always try to have some lettering on the
design that helps me know when I have made this mistake.
Better to mess up just a sheet of transfer paper than to actually
etch the board before you find the mistake!

I try not to waste the special transfer paper so as to save
money. I usually arrange my mirrored image so that it will
fall at the bottom corner of a sheet of paper. I first print
onto a regular sheet of paper, then I cut out the corner
that has the toner design on it, leaving a margin of between
1/4 and 1/2 inch. I then use Scotch Tape to hold on a section
of transfer paper that slightly overlaps the section cut out.
The shiny side of the transfer paper should be facing where
the toner will be applied. I then load this modified carrier
sheet and print the image again, with the exact same settings
as before. I adjust my printer so that the sheet comes straight
out the back of the printer, instead of turning around and coming
out the top. This helps to insure that the taped transfer
paper does not get stuck in the printer.

BTW, use 3M Scotch tape, and not some cheap imitation, as
some of the imitations cannot take the heat of the printer,
and they will melt inside and make a real mess.

I do my etching with Ammonium Persulphate that I purchase from
Mouser Electronics. My etcher is a slightly modified version
of the etcher sold by DynaArt. I made a few changes to enhance
the flow of etchant. Originally the pumps would give me
trouble. They were designed for pumping water, and the extra
densisty of the Ammonium Persulphate solution was just enough
to sometimes cause one or more of the pumps to stall. I
modified the pumps by cutting the rotor blades down a bit, and
now they pump reliably.

I can generally etch a board in 3 to 5 minutes with fresh
etchant that has been heated. Room temperature etchant takes
twice as long.

Hope this helps.
Fr. Tom McGahee

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2000\07\14@194811 by Jinx

face picon face
> Mitchell D. Miller wrote:
> <snip>
> > light.  Exposure and development of the board went fine ... etching was
> > quite slow because I didn't keep my etchant (ferric chloride) warm.  As
>
> My lowest-budget trick here:  I use a Rubbermaid low rectangular plastic
> container to etch in - I fill the sink with HOT water, about 5 minutes
> early - then drop the board into that hot ferric chloride once it's
> warm.  Works pretty well.  Don't over-fill the plastic container with
> etchant! <G>
>
>   Mark

To get away from the sink and serious assault if FeCl gets anywhere
it shouldna, I use a 1 litre container inside a 2 litre and peg them at the
top edge. Fill the 2l with hot water from the kettle to match the level of
the FeCl in the 1l. Then float the board upside-down on top of the FeCl.
There's enough surface tension to do this if you're careful. And once the
Cu starts coming off, the board becomes lighter. I've found this etches
much faster even without agitation (ie you can go clean up the mess
you left behind drawing up the board) than letting the board languish at
the bottom facing up. Probably because the dirty etchant drops away from
the Cu and doesn't just pool up on it. With most grp board the contrast
between dark FeCl and the etched pattern is good enough to see thru
the board, and I have a pair of plastic tongs to check after 5 minutes. It
can be put back on the surface quite easily. The only caveat is that the
FeCl must be decanted from it's bottle fairly carefully to stop too much
scum floating on the surface. However, the small amount that does re-
dissolves once the FeCl heats up. Bubbles under the board is rarely a
problem once you have the knack of sliding it on the surface. Lifting
it by one end and then putting it back down drives any bubbles out, if
they were there in the first place, which they usually aren't. Mostly I'd
only use 1/2" of FeCl, the less the better for taking heat away from
the hot water, and it'll stay very hot for the 7-10 minutes etching time

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2000\07\15@024030 by Stuart

flavicon
face
I have to say the best advice I've received so far with respect to etching
circuit boards came from Tony Nixon. I heat my etchant by putting my etching
tray in a sink of warm water, I use a small paint brush and I brush  the
circuit board while it is in the etchant (gently brushing away the copper).
This changed my etching time from about 25 minutes using room temp etchant
and agitation to about 3 minutes with warm etchant and a brush.

Regards
Stuart O'Reilly

{Original Message removed}

2000\07\15@204312 by Jinx

face picon face
When using DIP, instead of automatically plotting a board out for
through-pin, make it upside-down (or lay traces on the "top" side).
Bend IC legs out SMT-style, bend them under PLCC-style or cut the
legs short and just sit the IC on the tracks. In all cases make the bends
or cuts in the narrowest part of the leg so you can use thinner tracks.

Several plusses for me - saves W&T on drill bits, easier to follow
signal paths when you can see the pin a track is connected to and I
get to use some recycled SMT passive parts from scrap boards

Double-siding is a lot easier when you don't have to avoid pins from
the other side. A few pins can be left straight to go through the board
for power / logic connections

********************************
A programmer is a device for turning coffee into software

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2000\07\17@124657 by Mitchell D. Miller

picon face
> I have to say the best advice I've received so far with respect to etching
> circuit boards came from Tony Nixon. I heat my etchant by putting my
etching
> tray in a sink of warm water,

I agree.  I rearranged my lab over the weekend, and did another board
yesterday.  I now have a utility sink available (fiberglass).  I filled the
sink with about 1" of hot water, placed my etchant container in the water,
and filled it with etchant.

I also used the "upside down" technique someone previously mentioned.  By
placing the board (single sided, 1oz, FR4) face down on top of the etchant,
I could actually see where the copper had been removed.

The combination of both reduced my etching time to about 5 minutes.

-- Mitch

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2000\07\17@135743 by Lawrence Lile

flavicon
face
I get minimum etch time by using these tricks:

1.  I use a hair dryer to heat the etchant.  My etch tank has a "secondary
containment" tank that surrounds it, made from a plastic laundry tub with a
lid.  I stick a hair dryer through a hole in the side of the laundry tub.
This gets the inside to about 130F

2.  I bubble air through the etchant.  I have a piece of fiberglass hose
(originally used for electrical insulation) hot glued to the bottom of the
etch tank.  I run 15-20PSI compressed air onto the hose, turning the etch
tank into a seething froth.   With this arrangement, you really need the
secondary containment tank because it make a lot of mess.

Mind you, this may sound funky but it is not a hobby arrangement - just low
budget!

-- Lawrence
{Original Message removed}

2000\07\17@144558 by Thomas McGahee

flavicon
face
Instead of attempting to "float" the board copper-side
down on the etchant (as mentioned in a previous post),
attach one or two rubber-suction cups to the back
of the board and suspend the board a fraction of an inch
below the surface. In the past I have used suction cups
attached to plastic shafts (kiddie arrows with the shaft
cut short) Avoid wooden shafts, as the etchant will
destroy the wood very quickly.

I had a strip of old pc board stock that I drilled
a few holes in, and stuck in rubber grommets. Then I
could stick the shafts throgh the grommets which
grabbed the shafts with a medium pressure. This
allowed me to position the submerged pc board any where
I wanted within the tub. It also made it easy to
remove the pcb when I wanted to inspect it.

If I was going to bubble-etch the board, I could adjust
the ends of the pcb to be at different depths. This held
the board at an angle in the etchant, and allowed the
bubbles to run up the copper. This helped the etching
process to be more uniform.

****
My current method of etching uses pumped ammonium
persulphate that is heated and made to flow over the
copper side of the pcb. Fresh hot etchant can etch a
board in 2 minutes. Once the time to etch rises to
5 minutes I replace the etchant.

Fr. Tom McGahee

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2000\07\17@151236 by Mitchell D. Miller

picon face
> My current method of etching uses pumped ammonium
> persulphate that is heated and made to flow over the
> copper side of the pcb.

How to you pump the etchant?  Don't most pumps have at least some metal that
would quickly disappear?  What type of arrangement do you have at the high
point that flows the etchant evenly over the width of the board?

-- Mitch

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2000\07\17@151453 by Andrew Kunz

flavicon
face
Use a fish tank bubbler.

Also, most of the magnetically-coupled water pumps (also for fish) have no
exposed metal.

Andy

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2000\07\17@152109 by Mitchell D. Miller

picon face
> My current method of etching ...

P.S.  How fine can you make your traces and how much isolation do you use?
Using the upside-down-cake (er, board) method with Ferric Cloride, I've done
16 mil traces with 14 mil isloation with great success.  On my last board, I
had drawn a single line about 10 mils, but there were several spots where
the etchant undercut it pretty bad.  Not sure why, but this one trace is
much worse than the others.  I've been creating my board with precoated,
positive acting boards (from MG Chemicals) and a laser printed image on a
transparency.

-- Mitch

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2000\07\17@152114 by Mitchell D. Miller

picon face
> Use a fish tank bubbler.

For pumping or just bubbling?

-- Mitch

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2000\07\17@152306 by Spehro Pefhany

picon face
At 03:15 PM 7/17/00 -0400, you wrote:
>Use a fish tank bubbler.
>
>Also, most of the magnetically-coupled water pumps (also for fish) have no
>exposed metal.
>
You can use an aquarium heater as well (sorry if this has already been
suggested). Peristaltic pumps work fine for pumping etchant.

Best regards,

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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spam_OUTspeffTakeThisOuTspaminterlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com
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2000\07\17@154007 by Andrew Kunz

flavicon
face
The bubbling action moves the etchant as well, so in a way it is a pump for the
etchant.

Just make sure you don't get bubbles "stuck" to your board, or you will have
unetched areas.  We always used the boards in a vertical arrangement, but then
again we were making 25 sheets at a time...

Andy









"Mitchell D. Miller" <.....mdmiller2KILLspamspam@spam@HOME.COM> on 07/17/2000 03:20:10 PM

Please respond to pic microcontroller discussion list <PICLISTspamKILLspamMITVMA.MIT.EDU>








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Subject: Re: [EE]: PCBs using toner transfer paper








> Use a fish tank bubbler.

For pumping or just bubbling?

-- Mitch

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2000\07\17@181742 by Mark Willis

flavicon
face
Mitchell D. Miller wrote:
> > My current method of etching ...
>
> P.S.  How fine can you make your traces and how much isolation do you use?
> Using the upside-down-cake (er, board) method with Ferric Cloride, I've done
> 16 mil traces with 14 mil isloation with great success.  On my last board, I
> had drawn a single line about 10 mils, but there were several spots where
> the etchant undercut it pretty bad.  Not sure why, but this one trace is
> much worse than the others.  I've been creating my board with precoated,
> positive acting boards (from MG Chemicals) and a laser printed image on a
> transparency.
>
> -- Mitch

Some laser printers do NOT like to put lines down in certain
orientations - Try rotating your artwork 90 degrees then printing the
image again, see if that changes your results (If you're having this
problem, you can see the difference when you print to plain paper, sort
of pinholing through the center of the trace and/or edges.)  This can
also be a symptom of not quite enough heat, for that matter.  Try
carefully looking at the traces before etching, if it doesn't LOOK good,
don't expect good results!

I've used 8 mil traces and 12 mil isolation and not had much problems
that weren't Mark-caused (over heating or moving the iron're MY
problems!), when I mess up I clean the board and put new toner down to
solve the cause, not try to fight the symptoms <G>

 Mark

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2000\07\17@190658 by Tony Nixon

flavicon
picon face
Thomas McGahee wrote:
>
> Instead of attempting to "float" the board copper-side
> down on the etchant (as mentioned in a previous post),
> attach one or two rubber-suction cups to the back
> of the board and suspend the board a fraction of an inch
> below the surface. In the past I have used suction cups
> attached to plastic shafts (kiddie arrows with the shaft
> cut short) Avoid wooden shafts, as the etchant will
> destroy the wood very quickly.

I use insulated bell wire threaded through 1mm, or whatever, holes in
each corner of the PCB which make cheap and easy to use stand offs.
These are usually drilled out for mounting holes later on.

The upside method is an excellent way of etching boards, no pumps,
aerators, special tanks etc. The etchant stays stagnent all the time
which keeps it clean and the copper residue collects on the bottom, and
because there is no movement means a much "crisper" track outline with
no risk of resist smudging or lifting from the board surface.

It does not pay to have the etchant too hot either, especially if using
etch resist pens (Dalo type), because the heat thins the resist and it
"melts" off the board causing thin or missing traces.

From what I understand, ammonium persulphate has a limited shelf life
once mixed, whereas I have used the same batch of ferric chloride for
years. I get more than 50 hobby sized PCBs from a 1 litre batch.

I use "Brasso" liquid metal polish for cleaning the boards and then give
it a light rub with turpentine finished by a detergent and water rinse
off. If any water beads on the copper after this then it may not etch
properly. This method leaves the copper with a mirror finish and the
solder loves it.

--
Best regards

Tony

mICro's
http://www.picnpoke.com
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2000\07\17@205258 by Thomas McGahee

flavicon
face
I use a high-volume aquarium pump.The label says "Powerhead 802".
This baby really moves the etchant!

The pump is completely sealed. The impeller blades are driven by
a shaft connected to a permanent magnet rotor that is some
kind of high strength ceramic magnet that the etchant does
not attack.

The pump is located at the lower left side of a plexiglass
enclosure that is held together with stainless steel hardware,
which the etchant does not attack. I refer to this section as the
Main Reservoir. The Main Reservoir contains the submersible
pump and (optionally) one or two heaters that are contained in
glass enclosures. When the pump is off, then all the etchant resides
in the Main Reservoir. There is a plexiglass wall that separates the
Main Reservoir from the Lift Chamber, which is on the right
hand side of the main enclosure.

A short length of clear vinyl tubing connects between the
pump and the Lift Chamber. This forces the etchant to rise
in the Lift Chamber about 2 inches. At this point the
left-most wall of the Lift Chamber is bent such that the
etchant now flows down a flat piece of plexiglass that runs
to within a half inch of the left side of the plexiglass
wall that begins the Main Reservoir.

I use various sized lengths of "T" shaped pieces of
plexiglass to act as a kind of adjustable dam on either side
of the board being etched. This forces the etchant to rise
and flow mostly over the pcb. Fine adjustment of the flow is
accomplished by using a few wooden wedges placed underneath the
edges of the outer container as needed.

The outer enclosure which holds the apparatus happens to be a big
plastic container originally designed to act as a mini filing
cabinet. I replaced the metal hinge rod with a stainless
steel one.

The current apparatus has just sort of grown over the last several
years. I had purchased a DynaArt etching tank, but found it
too wimpy for my tastes

Fr. Tom McGahee


{Original Message removed}

2000\07\17@210516 by Thomas McGahee

flavicon
face
Ten mil lines work fine. When you etch fast you have to keep a close eye
on the board or you can undercut the runs. Adjusting the temperature
and etchant flow allows me to make the etch time a bit longer, but
with a "gentler" touch on those thin runs.

If you find you are getting jaggedy edges or pinholes, check the
resist pattern BEFORE etching. Many times the problem is not at the
etching end, but at the resist end. If there is a pinhole the
etcher will just naturally eat away at it!

CLEANLINESS of the board before and after the resist is applied
is crucial to successful etching of really thin traces.

Fr. Tom McGahee

{Original Message removed}

2000\07\18@100438 by Randy A.

picon face
I have an etchant tank from Datek that costs around $40.00 or less and it
comes with the aquarium pump, plastic tank, board holder for 2  8" X 9"
boards and an aquarium heater to heat the etchant.  You can also make your
own but when you figure in the time to put it all together, find and purchase
the components, you can't make one for that price.  Especially with the board
holder for setting the boards in vertically and the holder has air bubble
holes made into it and a length of plastic hose to run to the pump.  I
purchased mine thru Jayco Electronics.  Datek has a full line of PCB
materials at very low cost compared to a lot of the other suppliers and for a
hobbyist or even light production it works just as well.

Hope this helps out.

Randy

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2000\07\18@121034 by Mitchell D. Miller

picon face
> purchased mine thru Jayco Electronics.  Datek has a full line of PCB
> materials at very low cost compared to a lot of the other suppliers and
for a
> hobbyist or even light production it works just as well.

Would you happen to have a URL for Datek or Jayco?  http://www.Datek.com brings up
an investment broker.  http://www.Jayco.com brings up a camping trailer mfr.

-- Mitch

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2000\07\18@154950 by Mark Willis

flavicon
face
Try this phone #:  Jayco Electronics Inc @ 800-668-6587

(I think that's a 4 year old #?)

 Mark

Mitchell D. Miller wrote:
> > purchased mine thru Jayco Electronics.  Datek has a full line of PCB
> > materials at very low cost compared to a lot of the other suppliers and
> for a
> > hobbyist or even light production it works just as well.
>
> Would you happen to have a URL for Datek or Jayco?  http://www.Datek.com brings up
> an investment broker.  http://www.Jayco.com brings up a camping trailer mfr.
>
> -- Mitch

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2000\07\18@231057 by Randy A.

picon face
Sorry but I got my suppliers mixed up the supplier is Jay-Tronics and their
URL is http://www.jaytronics.com,  again sorry about that.  The manufacturere is
Datak and their URL is http://www.philmore-datak.com.  I must have had a typo if I
typed Datek on the original reply again sorry.  Shouldn't do these so late at
night or early in the morning.  Hope this helps.  The Datak products are good
and they are quite reasonable in price.

Randy

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2000\07\19@135609 by jamesnewton

face picon face
Ok, now this is going to sound completely nuts, but...

Has anyone tried making PCBs by printing directly on the PCB with a dot
matrix printer and a ribbon soaked in resist ink? Or with a laser printer?

I ran better than 16th inch card stock through a Brother HL-10...
something... laser printer some years ago without killing it (it had a dead
straight paper path) and I remember seeing an old ad for Agfa? Alpha?
something dot matrix printers that showed them printing on sheet steel.

Some of the thinner PCB stocks will warp slightly and aren't much thicker
than card stock.

Err... standard disclaimer "don't try this at home" and "I assume no
responsibility for damage to yourself or your equipment if you are stupid
enough to actually do what I suggested". In fact
http://www.piclist.com/../legalese

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jamesnewtonspamspam_OUTpiclist.com 1-619-652-0593
PIC/PICList FAQ: http://www.piclist.com or .org

{Original Message removed}

2000\07\19@151602 by Dale Botkin

flavicon
face
On Wed, 19 Jul 2000, James Newton wrote:

> Ok, now this is going to sound completely nuts, but...
>
> Has anyone tried making PCBs by printing directly on the PCB with a dot
> matrix printer and a ribbon soaked in resist ink? Or with a laser printer?

None of the above, BUT...  I have had wonderful success with an H-P
plotter.  I used a 7474 and a 7475 (I think -- these were HP plotters with
IBM logos on them).  The plotters were multi-pen carousel A and B size
that moved the paper along the Y axis and the pen along the X axis.  I
dissected the HP felt-tip pen body and slipped in a .5mm permanent marker
I found at an art supply store -- perfect fit.  With the plot speed set to
1 inch per second and the copperclad board taped to a sheet of paper, I
was able to have a board ready to etch in about 30 minutes, start to
finish.

That was a while ago -- like '92, '93.  Now I use perfboard or send the
stuff to ExpressPCB or somewhere if it's important enough to need a PCB.

Dale
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2000\07\24@082753 by Jinx

face picon face
Just a point of curiosity that I got reminded of today -

Can anyone offer an explanation of why etchant will take copper
off a board firstly immediately next to the traces and then work
its way to the open spaces ? Noticed it again when etching a board
this afternoon. As I've said B4, I float the PCB upside-down on
the FeCl and can see the pattern develop. All the traces and pads
appear with a thin gap around them, then nothing seems to happen
for a minute or two, then the open spaces just clear as the last thin
coat of copper falls off. I've tried to reason it out but can't explain it.
Does this happen just with an unagitated etching (like mine) or does
it also happen in agitated tanks ?

Just one of those nutty little things I wonder about

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2000\07\24@094352 by Michael Rigby-Jones

flavicon
face
A guess:

In the large areas of copper away from traces, the solution become localy
'saturated' with copper, and etching takes place slower.  Near the traces,
there is less copper to etch and the solution around the PCB is 'stronger'
i.e. has less copper disolved in it. (you may notice, I'm not a chemist :o)

This being the case, if the solution is agitated, this phenomenon ought to
disappear.

Cheers

Mike

> {Original Message removed}

2000\07\24@095013 by Thomas McGahee

flavicon
face
A pcb will etch more rapidly along the edges of the board
and next to the areas covered with resist. Along the edges
of the board you have the side edge of the copper exposed
as well as the flat copper face, so that partially explains
that phenomenon. There are other forces at work, and these
other forces also cause the higher rate of etching that you
notice near traces.

1) the etchant gets depleted more rapidly when there is more
copper surface exposed. The partially depleted etchant is
still active, but does not eat away the copper as fast as
fresher, less-depleted etchant. This effect is even more
noticeable when the etchant is moving. The edge of the board
that is first touched by the moving etchant will etch much
faster than any other part of the board. This is one reason why
it is a good idea to rotate a board several times during the
etching process.

2) Sharp edges will etch faster than smoothly curved edges.
Small curves (such as pads) will etch faster than large curves.
This is partially accounted for by the tendency for ionization
to occur at sharp edges. There will be a tendency for undercutting
to occur, especially along traces, since the more rapid
etching along the edge of the trace exposes the side to etchant
action EARLY in the process, and etching of the sides of the traces
continues as the larger copper areas are being etched.

3) VERY small holes usually take longer to etch than a medium
size hole. A small hole does not get a good flow of fresh etchant
into it, as the depleted etchant will tend to linger at the site.
This can be overcome to some extent by agitation of the etchant.

Making the etchant flow will increase the etching rate, but you
should then rotate the board at about one or two minute intervals.
You can minimize the problem of undercutting by ensuring that there
are no large exposed areas of copper to be etched away. Use these
areas instead as part of a ground plane (it is not a good idea to have
isolated floating islands of copper. Ground them.)  If the board
is large, you can make these ground areas "hatched" instead of
solid. This can help minimize warping in large boards.

Fr. Tom McGahee
{Original Message removed}

2000\07\24@165123 by Morgan Olsson

picon face
Thomas McGahee wrote:
>This can help minimize warping in large boards.

Sorry, what´s warping?

...

BTW, Years ago I used a device with bubbles and I think it did etch at an overall even rate.

But the bubbles make lot of very small drops of etchant fly away, so it is no good idea to etch in the lab...

Been thinking about using a small dc motor to make a vibrator that vibrates the board in small circular pattern.

Regards
/Morgan

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2000\07\24@172004 by David VanHorn

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At 10:42 PM 7/24/00 +0200, Morgan Olsson wrote:
>Thomas McGahee wrote:
> >This can help minimize warping in large boards.
>
>Sorry, what´s warping?

Twisting, bending, bowing..
To become other than perfectly flat.
Especially under weight or heat.

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2000\07\24@194402 by Jinx

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Thanks, that all sounded pretty reasonable. The point about small
holes etching slower than large ones was worth noting. 1or 2% of
my pads don't get the hole in them. I'd long ago dismissed that as
some piece of dirt stopping the etchant getting to it, and not given
it any thought after that, as you do. Now I realise that would take
several long-odds coincidences for it to happen on a regular basis.
I should get my A into G and make a stirrer

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2000\07\25@104512 by Randy A.

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I can't tell you why but I can tell you my agitated tank does the same thing
whether I am doing one or two boards at a time.  Just some quirk of physics
or chemistry I guess.

Randy

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