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'[EE] Etching PCBs - Danger?'
2009\01\22@214319 by solarwind

picon face
This dude gives a nice, simple guide to etching PCBs -
http://more.random.stuff.googlepages.com/howtomakepcbs

Looks nice and simple and the results are perfect.

However, the guys at systm http://revision3.com/systm/etching/ give a
lot of safety tips and make it sound like a very risky job.

What do you guys think?

--
solarwind

2009\01\22@223217 by Sean Breheny

face picon face
Well, I listened to about half of the video in the second link and
those guys are annoying and exaggerate the danger somewhat.

The two most common chemicals used are Ferric Chloride solution and
Ammonium Persulfate solution. Neither of them is a strong acid (as
they state again and again in the video). They are dangerous, but for
different reasons.

Ferric Chloride (let's call it FC) tends to work faster than Ammonium
Persulfate (call it AP) in my experience. FC is a dark liquid which
becomes opaque as it becomes filled with copper, whereas AP is
initially colorless and becomes blue-green as it reacts with the
copper.
This has the advantage that you can see the progress without removing
the PCB from the solution.

FC is very corrosive to most metals - staining them permanently or
even eating them away, as it does to copper. It is definitely
poisonous if you drink it or inhale its vapor in significant
quantities. The main danger here, I think, is burns to the membranes
in your respiratory or digestive system from the corrosive reaction
(which is NOT the same thing as an acid reaction). If you get it on
your skin, it will stain and dramatically dry out your skin in the
affected area, but you are unlikely to suffer any burns if you wash it
off within a minute or two. If you get it on clothing, you will never
be able to get the stain out. I have gotten a few drops of it on my
skin many times and I can no longer see any evidence of the stains,
nor did I experience any pain or other problems.

Dry FC is perhaps even more dangerous because it is deliquescent - it
absorbs water vapor from the air until there is enough water to
dissolve the FC, which then becomes a super concentrated solution. My
cat once licked a little bit of this from a stain on the floor and
vomited immediately. I didn't find out until much later but he
suffered no lasting problems that I can tell - although he probably
didn't take much of it in.

I have less experience with AP but I'd say that it is less harmful if
you get it on your skin. It is less "aggressive" in general at eating
away at things. The downside of this is that it does not etch well at
all unless you warm it and agitate it. If you just let a PCB sit in
room temp FC, it will etch in perhaps 45 minutes. It would take many
hours in AP. If you warm them to say, 50C, and agitate with bubbles
from a fish-tank air pump, the FC will etch the board in about 3
minutes and the AP in about 10 minutes.

Both FC and AP really should be warmed and agitated during etching to
ensure even coverage and relatively quick etching time. Long etching
times not only make you impatient but they also can allow the resist
material to begin to come off. Agitation has to be done very carefully
to avoid spraying warm FC or AP around.

Since most drain plumming is PVC and not metal, as far as I know, you
can dispose of small amounts (perhaps, say, 500mL or less) at a time
into the toilet in a normal sewer system. Probably not a good idea for
septic systems. It is very important to dilute it GREATLY before
disposal. I usually would pour about 50mL at a time into the toilet
bowl and then flush, then repeat. Then I would follow this up with
several buckets full of water. This is to avoid staining of
pipes/toilet bowl, any corrosion of metal parts that I may not be
aware of in the system, and to help guarantee that by the time it
arrives at any processing facility, it has been very much diluted.
Strictly speaking, you are probably supposed to take FC and AP to a
hazardous waste facility but I have never done that. I only used
perhaps 1 liter of it per year.

To use FC or AP, I would recommend safety glasses, a closed container
for your etchant tank so that splashing doesn't happen, and good
ventilation. If you were to do this on a daily basis, then I think you
would probably need a vent hood to limit chronic exposure.

I would say, though, that in the end, etching your own PCBs is not
worth it anymore for most people. PCB houses have become so
inexpensive and have relatively fast turn-around. Also, to produce
something anywhere near as nice-looking as a PCB house will take
considerable time, effort, and money. This is not even considering
things like plated-thru holes, soldermask or silkscreen, or more than
2 layers.

Sean


On Thu, Jan 22, 2009 at 9:42 PM, solarwind <spam_OUTx.solarwind.xTakeThisOuTspamgmail.com> wrote:
{Quote hidden}

> -

2009\01\22@223249 by peter green

flavicon
face
solarwind wrote:
> This dude gives a nice, simple guide to etching PCBs -
> http://more.random.stuff.googlepages.com/howtomakepcbs
>
> Looks nice and simple and the results are perfect.
>
> However, the guys at systm http://revision3.com/systm/etching/ give a
> lot of safety tips and make it sound like a very risky job.
>
> What do you guys think?
>  
I think they were exagerating on the strength of the stuff used to etch
PCBs, if it were really as bad as they made out then I would expect to
see much more protective equipment used when handling it.

I took a look to see just how hazardous ferric chrloride (the most
common etchant among hobbyists afaict) is. Here are a couple of links I
found.

www.rapidonline.com/netalogue/specs/34-0758h.pdf
http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc14/icsc1499.htm

They give the impression that it's not the sort of stuff you want to get
on your hands if you can help it but it's not horriblly dangerous
either. It is VERY corrosive towards most metals though ;)

2009\01\22@230745 by solarwind

picon face
I have not found a single PCB manufacturer with good prices. I can,
however, get the chemicals and agitation tank for making my own PCBs
for a very low cost and copper clad board is practically free. After
that, one can make any pcb at any size, good for hobby projects.

If I can get a full PCB under $20 from a PCB house, I'll go for it,
but anything more than that is expensive.

2009\01\22@231342 by solarwind

picon face
The cheapest I found was BatchPCB from Sparkfun.

Setup fee - $10
Cost - $2.50 / sq in
+ Shipping

So thats $10 + $30 + shipping for a 4 x 3 board. Wayyy too expensive.

2009\01\22@232319 by Bob Blick

face
flavicon
face
solarwind wrote:
> This dude gives a nice, simple guide to etching PCBs -
> more.random.stuff.googlepages.com/howtomakepcbs
>
> Looks nice and simple and the results are perfect.

Not perfect. I used to teach electronics and we made lots of PC boards,
the laser printer method was the least perfect. Quite often "good
enough" though.

Everyone should make their own PC boards at least enough times to find
out where their skill/comfort level is.

> However, the guys at systm http://revision3.com/systm/etching/ give a
> lot of safety tips and make it sound like a very risky job.

If it was so risky then Radio Shack wouldn't sell etchant. There is very
little danger to you, but try not to spill it on metal you care about.
And when you heat it, be aware that any metal nearby will corrode. If
you heat it in a microwave oven, put a sealed baggie over the container
so the vapors don't ruin your microwave.

Cheers,

Bob

2009\01\22@232458 by Jinx

face picon face

> FC is very corrosive to most metals - staining them permanently

Works on shirts too. Nothing gets FeCl stains out. Look

Seriously, I've never felt in danger whilst etching. More worried
about spashing hot water out of the jacket actually

> AP is initially colorless and becomes blue-green as it reacts with
> the copper. This has the advantage that you can see the progress
> without removing the PCB from the solution

My technique is to etch the board umop 3pisdn

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

> If you just let a PCB sit in room temp FC, it will etch in perhaps
> 45 minutes

New solution with a hot water jacket - 7, 8 minutes. Once it gets
past 15 minutes it's time t'go. For one thing, long etching times runs
the risk of under-cutting the resist. At best it can feather the edges
of tracks, a problem with thin ones of course, at worst the etchant
can be there long enough to creep under the resist and etch out
any low spots, eg scratches in the copper, resulting in very fine 'cuts'
across the track. Tinning will usually fix that

2009\01\22@233042 by Bob Blick

face
flavicon
face
solarwind wrote:
> I can,
> however, get the chemicals and agitation tank for making my own PCBs

Agitation tank? Why not just jiggle the Tupperware by hand while you
read or surf the net?

-Bob

2009\01\22@234711 by John Day

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face
At 11:30 PM 1/22/2009, you wrote:
>solarwind wrote:
> > I can,
> > however, get the chemicals and agitation tank for making my own PCBs
>
>Agitation tank? Why not just jiggle the Tupperware by hand while you
>read or surf the net?

For years I used a plastic "lunchbox" with a pencil under it so that
I could rock it!

John


>-Bob
>

2009\01\22@234905 by William \Chops\ Westfield

face picon face

On Jan 22, 2009, at 8:13 PM, solarwind wrote:

> The cheapest I found was BatchPCB from Sparkfun.
>    :
> So thats $10 + $30 + shipping for a 4 x 3 board. Wayyy too expensive.

Yeah, well.  That $40 will get you a lot nicer board than you'll be able
to achieve at home for any similar cost of materials...

Good Luck.
(hey, I spent a small fortune on PCB making machines so I wouldn't have
to use "expensive" fabs as well.  So I know the feeling.  (I'm still not
sure that I made a sound economic decision.  (Though since it's a hobby,
economics has little to do with it.)))

BillW

2009\01\22@234926 by solarwind

picon face
On Thu, Jan 22, 2009 at 11:30 PM, Bob Blick <.....bobblickKILLspamspam@spam@ftml.net> wrote:
> solarwind wrote:
>> I can,
>> however, get the chemicals and agitation tank for making my own PCBs
>
> Agitation tank? Why not just jiggle the Tupperware by hand while you
> read or surf the net?
>
> -Bob

LOL!

I want to build a simple tank with a heater because I want to make
PCBs often for my projects. I hate breadboards. And PCBs are nice and
easy to make. Drilling doesn't take too long and the tools needed to
etch are very inexpensive.

How much does a bottle of the etchant cost? How many PCBs can one etch
with it? Approx.


--
solarwind

2009\01\22@235857 by Jinx

face picon face
> Agitation tank? Why not just jiggle the Tupperware by hand while
> you read or surf the net?

I used to think about making a motorised wobbler or an aerator. But
then decided etching upside down with good etchant doesn't need any
help really, so I never bothered

2009\01\23@000546 by John Day

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face
At 11:13 PM 1/22/2009, you wrote:
>The cheapest I found was BatchPCB from Sparkfun.
>
>Setup fee - $10
>Cost - $2.50 / sq in
>+ Shipping
>
>So thats $10 + $30 + shipping for a 4 x 3 board. Wayyy too expensive.

Well, you have to decide your own comfort level and your own value.
$40 plus shipping is way less than anything I have had done for
years, so yes, it is very low cost. It just may not be the value you
are seeking.

For double sided plated through with solder mask and silk-screen good
value is about $160 for a batch, this can be anywhere form 25 to 50
boards depending on size. So if I do my job well the prototype batch
is also the first production batch.

The Sparkfun system is VERY good value. They panelise the boards and
then the setup and photo-tooling and silk screen costs are split
amongst a number of users. Typically the NRE (non-recurring
engineering) for a small panel is around $68 (in China, way more in
North America). For a 2x4" board I will end up paying $1.47 each for
25 boards or maybe $4 for just one, plus $68 for NRE. Given the value
of my time this is an absolute bargain! If your time is worth nothing
to you, then this is expensive.

As a further example of the China/North America comparison. The other
day I needed a few fast turned 4 layer boards. The PCB is 1.8x3.3",
for five pieces I was quoted $750 from one house, $550 from another
both offering 5 business day turn-around, plus shipping and shipping
delay. My favourite Chinese board house received the gerbers and
payment at about 3pm EST on Wednesday Jan 14th. The finished boards
arrived via Fedex during the day of the 20th. The fifth working day.
And the cost? A mere $320 USD including, NRE, bare board test, test
set-up and Fedex delivery.

John

>

2009\01\23@000808 by Bob Blick

face
flavicon
face
solarwind wrote:


> How much does a bottle of the etchant cost? How many PCBs can one etch
> with it? Approx.

Radio Shack stuff is pretty watered down.

If you can find it dry you'll know what you are getting. Use cold water
because it gets HOT when you mix it.

http://www.elexp.com/pro_3er3.htm

If that link works, they say 1 pint does 200 square inches, so $12 of
dry etchant is enough for 800 square inches.

Also, fishtank heaters are not very strong. If your etchant is cold you
will need to heat it up some other way, the fishtank heater can only
keep it warm for a while. We kept our "system" in a big styrofoam
icechest and had two fishtank heaters and an air pump for bubbles.

Cheers,

Bob

2009\01\23@001209 by John Day

flavicon
face
At 12:57 AM 1/23/2009, you wrote:
> > Agitation tank? Why not just jiggle the Tupperware by hand while
> > you read or surf the net?
>
>I used to think about making a motorised wobbler or an aerator. But
>then decided etching upside down with good etchant doesn't need any
>help really, so I never bothered

To get a good clean etch you should be gently circulating the etchant
so that the surface you are working on is always exposed to fresh
material. If you look at a board etched with no agitation you will
see undercut - the edges of the copper are undermined. On fine tracks
this can result in a serious loss of width and detail.

John


>

2009\01\23@001707 by Jinx

face picon face
> If that link works, they say 1 pint does 200 square inches, so $12
> of dry etchant is enough for 800 square inches.

You can improve that by not etching areas that don't need to be, ie
fat traces & filling in with resist

2009\01\23@002000 by solarwind

picon face
On Fri, Jan 23, 2009 at 12:07 AM, Bob Blick <bobblickspamKILLspamftml.net> wrote:
> If you can find it dry you'll know what you are getting. Use cold water
> because it gets HOT when you mix it.
>
> http://www.elexp.com/pro_3er3.htm
>
> If that link works, they say 1 pint does 200 square inches, so $12 of
> dry etchant is enough for 800 square inches.

For $12 I can etch 800 sq in? Now THAT's a bargain!

I'm not "cheap", I'm just a student and doing this as a hobby so I
don't have hundreds of dollars to spend on a pass-time like you
professionals. You guys do this for a living and may have unlimited
funding from your company even. I don't. I just have a few dollars
from extra lunch money, lol. So The difference between a few cents for
copper clad and $10 to etch all the boards I'll ever need vs $40 per
board + waiting time is a huge difference to me.

Time IS a value to me. If you put it that way - the time it takes for
me to send in my design to the time it arrives at my house may be a
week. In comparison, I can have a fully made PCB in about half an
hour.

10 minutes to print out and iron it on.
20 minutes to soak it in soapy water and peel off paper.
5 minutes to etch it in a hot, agitated solution of etchant.
5 - 10 minutes to clean it.

Now, if I obviously can't do 4 layer PCBs, but double sided shouldn't
be any harder than single sided. Just have to iron both sides, don't
I? And that's probably all I'll ever need. And judging from the
results from pictures, the results seem better than what everyone is
saying.



--
solarwind

2009\01\23@002011 by Jinx

face picon face
> >I used to think about making a motorised wobbler or an aerator. But
> >then decided etching upside down with good etchant doesn't need any
> >help really, so I never bothered
>
> To get a good clean etch you should be gently circulating the etchant

I used to do the opposite. Twirl the floating board. But as the contaminated
etchant sinks it creates its own eddies, so I don't even do that anymore

Man, it's the sweet lazy life being an etcher around here ;-)

2009\01\23@002212 by solarwind

picon face
On Fri, Jan 23, 2009 at 12:11 AM, John Day <.....john.dayKILLspamspam.....siliconrailway.com> wrote:
> To get a good clean etch you should be gently circulating the etchant
> so that the surface you are working on is always exposed to fresh
> material. If you look at a board etched with no agitation you will
> see undercut - the edges of the copper are undermined. On fine tracks
> this can result in a serious loss of width and detail.
>
> John

Yeah. I'm thinking about putting two fish tank bubblers on overdrive
and a heater coil to keep the solution at a certain temperature. Hey,
maybe I can make my own PCB and circuit to control temperature and
timing of solution :)

I can probably even make a system to sound an alert after the etching
time has completed.


--
solarwind

2009\01\23@002447 by solarwind

picon face
On Fri, Jan 23, 2009 at 1:15 AM, Jinx <EraseMEjoecolquittspam_OUTspamTakeThisOuTclear.net.nz> wrote:
>> If that link works, they say 1 pint does 200 square inches, so $12
>> of dry etchant is enough for 800 square inches.
>
> You can improve that by not etching areas that don't need to be, ie
>  fat traces & filling in with resist
>

$12 for 800 sq in.

BatchPCB's prices are $2.50 / sq in so the equivalnt cost to have this
done at BatchPCB is 800 x 2.5 = a spanking new expensive laptop for
me.

--
solarwind

2009\01\23@004347 by Bob Blick

face
flavicon
face
solarwind wrote:

> Now, if I obviously can't do 4 layer PCBs, but double sided shouldn't
> be any harder than single sided. Just have to iron both sides, don't
> I?

It's fine for crude stuff. But you can't get all four corners to
register exactly. Also, laser printers go faster and slower as the paper
goes through. So even if you could get all four corners to line up, in
between there would be registration errors between the two sides. But if
you are careful you can do coarse stuff on smallish boards.

Hey, go for it. You will see what the limitations are and if you're
doing the layout yourself you can design accordingly. Use big vias with
room around them. Or get good at drilling slanted holes :)

Best regards,

Bob

2009\01\23@012823 by Jesse Lackey

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face
Double-sided homebrew... PITA.

I wish you luck, IMHO you're pretty naive about what it is going to take
to do better than simple boards.  However if you're more excited about
the craft of it all than doing more sophisticated designs then by all
means go for it...

At one point I had a custom laminator and laserprinted resist on special
paper and a dremel with different bit sizes and drill press and etchant
solution and steel wool scrubbers and rubber gloves and so forth.

Not worth it.  Saved the dremel and drillpress, gave all the other stuff
away.

barebonespcb.com is all I ever do when I don't need "real" boards.  1
day turnaround, pay per square inch, and with the "gerbmerge" program I
can take multiple gerbers from Eagle designs and merge together into a
single order.  I just did a personal project (qty 1), and two client
projects (qty 4 and qty 5) in one 13.5" x 6.8" panel, overnight fedex, $132.

The biggest advantage of barebonespcb is that you can design with
"normal" rules, not wider everything to make homebrew possible.  20 mil
SMT pin pitches?  No problem.

But as always there is the time/money tradeoff, though in this case DIY
will never be as good as what they do, unless you buy all the
professional gear a boardhouse has.

J



solarwind wrote:
{Quote hidden}

2009\01\23@015011 by solarwind

picon face
On Fri, Jan 23, 2009 at 1:27 AM, Jesse Lackey <@spam@jsl-mlKILLspamspamcelestialaudio.com> wrote:
> Double-sided homebrew... PITA.
>
> I wish you luck, IMHO you're pretty naive about what it is going to take
> to do better than simple boards.  However if you're more excited about
> the craft of it all than doing more sophisticated designs then by all
> means go for it...

IMHO you're severely underestimating what can be done with homebrew
double sided. I don't care how much experience you have. I've seen
"experienced" people make some stupid mistakes consistently throughout
their career. Remember that thread about the EE who taught people to
cold solder joints? Ya. I have no experience doing it but I've seen my
teacher's end result on a home brew double sided toner transfer PCB.
It was pretty complex and came out very well, way more than what I had
expected. I was impressed.

> At one point I had a custom laminator and laserprinted resist on special
> paper and a dremel with different bit sizes and drill press and etchant
> solution and steel wool scrubbers and rubber gloves and so forth.
>
> Not worth it.  Saved the dremel and drillpress, gave all the other stuff
> away.

Cool!

> barebonespcb.com is all I ever do when I don't need "real" boards.  1
> day turnaround, pay per square inch, and with the "gerbmerge" program I
> can take multiple gerbers from Eagle designs and merge together into a
> single order.  I just did a personal project (qty 1), and two client
> projects (qty 4 and qty 5) in one 13.5" x 6.8" panel, overnight fedex, $132.
>
> The biggest advantage of barebonespcb is that you can design with
> "normal" rules, not wider everything to make homebrew possible.  20 mil
> SMT pin pitches?  No problem.

$50 for a 3 x 4? You gotta be kidding, right? See, you're JOB forces
you to get this stuff done professionally. You don't want to be
constantly etching your own PCB. Besides, what will your clients
think?

> But as always there is the time/money tradeoff, though in this case DIY
> will never be as good as what they do, unless you buy all the
> professional gear a boardhouse has.
>
> J

Of course it wont be as good, but it'll be good enough.

--
solarwind

2009\01\23@042512 by apptech

face
flavicon
face

> I can probably even make a system to sound an alert after the etching
> time has completed.

The prior :-) noted - but, most home etching of PCBs of any complexity
benefits greatly from having an eye and brain in the control loop.

Of course, real men use Pirhana, which etches faster than most people can
think.

Is it done?
Maybe not.
Is it done?
Just about!
Is it done?
Oh bother!!!

Use outside.
Ventillate well.
Have paid up insurance.
Fun though.


     Russell


2009\01\23@045519 by peter green

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face

> Now, if I obviously can't do 4 layer PCBs, but double sided shouldn't
> be any harder than single sided.
Afaict homemade double sided is a PITA for two reasons

The first is alignment, with a single sided board you really don't need
to do any particularlly accurate alignment of your design. with double
sided you have to find a way to line up the patterns on the two sides.

Secondly your board wont be PTH, that means whenever a track leaves a
pad on the top layer you need to solder the component on the top layer
and whenever you have a via you need to put a peice of wire through it
and solder it on both sides.

2009\01\23@054354 by Jinx

face picon face
> Afaict homemade double sided is a PITA for two reasons

I've done many double-sided boards at home by hand, most a
mix of SMT and through-hole. Having a couple of reference
positions to measure from is usually all that's necessary, and you
double-check as you go. Quite reasonable results can be had
if you accept some limitations and aren't too ambitious

One I'm working on now has an array of through-hole tact
switches on one side, mounted SMT-style, plus SOIC logic,
diodes and SMT caps/resistors. On the other side is an 18F,
DIP, but mounted SMT-style and assorted through-hole and
SMT components

There aren't a lot of inter-layer connections needed for this
particular circuit. The tact switches and their debounce/buffer
logic are in one area of one side, with only the outputs of the
gates needing to go through the board to the PIC, and they're
arranged to do that through the pins of a SIL resistor array

The point I'm trying to make is that through-hole components
don't actually have to go through holes. One advantage of not
drilling is of course that you aren't intruding into useable area
on the other side. Plus it reduces the size of the board, having
components on both sides

2009\01\23@063106 by Carl Denk

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face
Caution, in addition to the usual healthy warnings, the etching process
generally liberates chlorine gas. Good ventilation is a must, but might
not be sufficient! My workshop has a good exhaust fan, plus being a
fairly open area. Several days after etching a few small boards, I
noticed rust forming on just about any bare steel in the workshop
including some very nice tools and good supplies. It was quite a project
to go through everything, remove the rust, some of it was getting to the
flaking stage within less than a week. Chlorine combines with the iron
>> FECL (might have some of the subscripts wrong) >> + H2O >> Rust +
Chlorine liberated. The Chlorine then is free to do it all over again!
Best to do it outside, UGH, it's been below 0F here for several nights.

Jinx wrote:
>> Afaict homemade double sided is a PITA for two reasons
>>
>
> I've done many double-sided boards at home by hand, most a
> mix of SMT and through-hole. Having a couple of reference
> positions to measure from is usually all that's necessary, and you
> double-check as you go. Quite reasonable results can be had
> if you accept some limitations and aren't too ambitious
>
> One I'm working on now has an array of through-hole tact
> switches on one side, mounted SMT-style, plus SOIC logic,
> diodes and SMT caps/resistors. On the other side is an 18F,
> DIP, but mounted SMT-style and assorted through-hole and
> SMT components
>
> There aren't a lot of inter-layer connections needed for this
> particular circuit. The tact switches and their debounce/buffer
> logic are in one area of one side, with only the outputs of the
> gates needing to go through the board to the PIC, and they're
> arranged to do that through the pins of a SIL resistor array
>
> The point I'm trying to make is that through-hole components
> don't actually have to go through holes. One advantage of not
> drilling is of course that you aren't intruding into useable area
> on the other side. Plus it reduces the size of the board, having
> components on both sides
>
>


KILLspampiclist-ownerKILLspamspammit.edu wrote:
{Quote hidden}

2009\01\23@065340 by olin piclist

face picon face
solarwind wrote:
> This dude gives a nice, simple guide to etching PCBs -
> http://more.random.stuff.googlepages.com/howtomakepcbs
>
> Looks nice and simple and the results are perfect.
>
> However, the guys at systm http://revision3.com/systm/etching/ give a
> lot of safety tips and make it sound like a very risky job.
>
> What do you guys think?

I think etching your own boards isn't worth it.  I also don't want to waste
time dealing with no plated thru holes, screwups due to lack of silkscreen,
and no solder mask.  Commercially made prototype PC boards are cheap and
widely available.

The tradeoffs may be a little different for hobbyists, but all the hassle
and downside of self-made boards still apply.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.

2009\01\23@071206 by olin piclist

face picon face
solarwind wrote:
> The cheapest I found was BatchPCB from Sparkfun.
>
> Setup fee - $10
> Cost - $2.50 / sq in
> + Shipping
>
> So thats $10 + $30 + shipping for a 4 x 3 board. Wayyy too expensive.

Not at all.  Etching your own boards isn't free either.

Show your parents what you're up to, show them that you've done your
homework by looking around at how to get PC boards made, the best deal
you've found, and see if they'll give you the money or order the boards for
you.  A few 10s of $$ is really a drop in the bucket compared to the cost of
raising a kid.  If they know the money is furthering your education as
apposed to you going out and goofing off with it with your friends, I
suspect you'll find them supportive.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.

2009\01\23@072325 by Jinx

face picon face
> the etching process generally liberates chlorine gas

I can honestly say I've never smelled chlorine whilst etching. My
guess would be that chlorine ions that don't bond with the copper
will go into solution

And just checking that

http://en.wikipedia.org/wiki/Ferric_chloride

FeCl3 + Cu ? FeCl2 + CuCl
FeCl3 + CuCl ? FeCl2 + CuCl2

The brown sludge left over would be the mix of iron and copper
chlorides. ISTR that electrolysis could recover the copper and
convert some of the Fe(II) chloride back to Fe(III) chloride





2009\01\23@080157 by William \Chops\ Westfield

face picon face

On Jan 23, 2009, at 5:21 AM, Jinx wrote:

>> the etching process generally liberates chlorine gas
>
> I can honestly say I've never smelled chlorine whilst etching

Me either, and I find the chemistry a bit questionable.  But the  
"everything metal in the workshop starts to rust" effect seems to be  
pretty real.  (Even the "stainless steel"!)  I've always assumed that  
it's due to microscopic droplets of etchant solution made airborne by  
the bubbler-style agitation.  (Hmm.  Still a good reason for adequate  
ventilation!)

BillW

2009\01\23@081845 by Jinx

face picon face
> "everything metal in the workshop starts to rust" effect seems to
> be pretty real

Oh yeah, it'll eat anything. The fumes or "smell" of it permeates
across the bench and soon rusts tools etc

I even used it as a corrosive on purpose once. Made a friend some
mild steel square tube desk frames and he wanted them to look
"distressed", so the bare metal got a wipe-down with FeCl solution.
After a few days they were hosed down and lacquered. Didn't look
too bad actually, very artsy fartsy. Went well with his brick studio

2009\01\23@082237 by solarwind

picon face
On Fri, Jan 23, 2009 at 8:01 AM, William Chops Westfield <RemoveMEwestfwspamTakeThisOuTmac.com> wrote:

> Me either, and I find the chemistry a bit questionable.  But the
> "everything metal in the workshop starts to rust" effect seems to be
> pretty real.  (Even the "stainless steel"!)  I've always assumed that
> it's due to microscopic droplets of etchant solution made airborne by
> the bubbler-style agitation.  (Hmm.  Still a good reason for adequate
> ventilation!)

Don't want that in your lungs...

> BillW
>


--
solarwind

2009\01\23@084558 by Carl Denk

flavicon
face
Granted , I'm doing a little assuming, and having only a little college
chemistry. The facts as I know them:
1: The reactions I noted are the major cause of reinforced concrete
bridge deck failures in the northern climates where salt NACL is the
common deicer. The common item is the chlorine, iron, and the freeing,
recombining of the chlorine.
2: Most of the etching chemicals include Chlorine, and I have smelled
the gas slightly while etching. Don't know the reactions happening to
cause that, or remember what brand or type chemicals, except that
chlorine was one of the elements.
3: Within days of etching, this rust appeared on all exposed steel, and
some that was in loose boxes. No other chemicals had been used in the
area for some time before. This had not happened before in 30 years, and
hasn't happened the roughly 2 years after.

I think someone can find issue, but the bottom line is, etching does use
chemicals that are hazardous, deserve respect, there may be some
unintended consequences, and best to be conservative. :)

Jinx wrote:
{Quote hidden}

2009\01\23@090236 by solarwind

picon face
On Fri, Jan 23, 2009 at 8:45 AM, Carl Denk <cdenkEraseMEspam.....alltel.net> wrote:
> Granted , I'm doing a little assuming, and having only a little college
> chemistry. The facts as I know them:
> 1: The reactions I noted are the major cause of reinforced concrete
> bridge deck failures in the northern climates where salt NACL is the
> common deicer. The common item is the chlorine, iron, and the freeing,
> recombining of the chlorine.
> 2: Most of the etching chemicals include Chlorine, and I have smelled
> the gas slightly while etching. Don't know the reactions happening to
> cause that, or remember what brand or type chemicals, except that
> chlorine was one of the elements.
> 3: Within days of etching, this rust appeared on all exposed steel, and
> some that was in loose boxes. No other chemicals had been used in the
> area for some time before. This had not happened before in 30 years, and
> hasn't happened the roughly 2 years after.
>
> I think someone can find issue, but the bottom line is, etching does use
> chemicals that are hazardous, deserve respect, there may be some
> unintended consequences, and best to be conservative. :)


Ok, I'll make an agitation tank and do this outside in my back yard

--
solarwind

2009\01\23@092542 by Carl Denk

flavicon
face
No agitation or bubbler, other than a gentle rocking of the flat pan
container back and forth. All done at room temps, say 70F. :)

William "Chops" Westfield wrote:
{Quote hidden}

2009\01\23@094402 by solarwind

picon face
On Fri, Jan 23, 2009 at 9:25 AM, Carl Denk <EraseMEcdenkspamalltel.net> wrote:
> No agitation or bubbler, other than a gentle rocking of the flat pan
> container back and forth. All done at room temps, say 70F. :)

But will a heated bubble tank speed up etching and make more sharp
lines and allow for .4 mm pitch TQFP chips?

--
solarwind

2009\01\23@094526 by solarwind

picon face
On Fri, Jan 23, 2009 at 9:44 AM, solarwind <RemoveMEx.solarwind.xEraseMEspamEraseMEgmail.com> wrote:
> On Fri, Jan 23, 2009 at 9:25 AM, Carl Denk <RemoveMEcdenkspam_OUTspamKILLspamalltel.net> wrote:
>> No agitation or bubbler, other than a gentle rocking of the flat pan
>> container back and forth. All done at room temps, say 70F. :)
>
> But will a heated bubble tank speed up etching and make more sharp
> lines and allow for .4 mm pitch TQFP chips?
>
> --
> solarwind

Like the PIC32...



--
solarwind

2009\01\23@104506 by Joseph Bento

face
flavicon
face

On Jan 22, 2009, at 9:30 PM, Bob Blick wrote:

> solarwind wrote:
>> I can,
>> however, get the chemicals and agitation tank for making my own PCBs
>
> Agitation tank? Why not just jiggle the Tupperware by hand while you
> read or surf the net?
>

I've done several boards in a Tupperware container.  An inexpensive  
aquarium heater and bubbler will dramatically speed up the etching  
process, and it's far cheaper than an agitation tank.

Joe

2009\01\23@105314 by William \Chops\ Westfield

face picon face

On Jan 23, 2009, at 6:44 AM, solarwind wrote:

> But will a heated bubble tank speed up etching and make more sharp
> lines and allow for .4 mm pitch TQFP chips?

The etching will likely not be your limiting factor WRT pitch.
Resist application is the tough part...

BillW

2009\01\23@110033 by William \Chops\ Westfield

face picon face

On Jan 22, 2009, at 10:49 PM, solarwind wrote:

> but I've seen my teacher's end result on a home brew double sided  
> toner transfer PCB.  It was pretty complex and came out very well

Ah.  You have a local experienced mentor!  That should help a lot (and  
it explains this 'cheap access to expensive stuff' tone I've been  
hearing.)  I was assuming (and I suspect so were others) that you'd be  
starting from scratch on your own...

The worst part of homebrew double-sided boards, IMO, is the lack of  
plated through holes.  Having to add wires and solder your vias isn't  
TOO bad (although it can prevent you from putting vias UNDER SMT  
parts, I think), but the places where the PCB assumes that the  
mounting hold for a TH component will carry a signal from one side of  
the board to the other are AWFUL; they now need to be soldered on both  
sides of the board, and that's just not possible with some  
components!  You can design the PCB to correct for this (extra vias!),  
but it's not 'nice.'

BillW

2009\01\23@110341 by Alan B. Pearce

face picon face
>IMHO you're severely underestimating what can
>be done with homebrew double sided.

I don't believe anyone is under-estimating it. There used to be products out
in the marketplace that used double sided PCBs without plated through holes.
The connections that needed to be transferred from one side to the other
were done by either the component legs or short tinned copper wire links
that were hand assembled into the PCB and soldered both sides.

But they weren't without problems ...

2009\01\23@163524 by Jinx

face picon face
> 1: The reactions I noted are the major cause of reinforced
> concrete bridge deck failures in the northern climates where
> salt NACL is the common deicer. The common item is the
> chlorine, iron, and the freeing, recombining of the chlorine

Hi Carl,

What you describe is not quite the same type of reaction. The
sodium chloride dissociates to Na+ and Cl- which facilitates
electrochemical oxidation (rusting) in the presence of water and
oxygen

Have a quick squiz at the short 'Iron corrosion' section

http://en.wikipedia.org/wiki/Electrochemical

Etching is a redox reaction, also electrochemical but water ions
aren't involved, IOW, in this instance, the two metals exchange
possession of the chloride ion

Another redox reaction is thermite, where iron oxide is mixed with
aluminium and ignited. The aluminium 'steals' the oxygen from the
iron. The iron oxide has been reduced, the aluminium has been
oxidised => redox. You might think of etching as aqueous thermite.
Or you might not

Do you recall the electrochemical series ? Generally a list of
positive ions ranked in order of their ability to steal negative
ions (donate electrons) from positive ions ranked lower on the list

In this table you'll see that copper has a greater affinity for -ve ions
than iron

>http://en.wikipedia.org/wiki/Electronegativities_of_the_elements_(data_page)<

The common practical experiment to demonstrate this is throwing
alkali metals into water, the reaction getting more violent as you
move down the periodic table (eg Mythbusters MacGyver Special)

http://en.wikipedia.org/wiki/Electronegativity#Periodic_trends

> 2: .......and I have smelled the gas slightly while etching

I can only suggest contamination. With pure FeCl3 and clean
copper there shouldn't be any significant chlorine release

2009\01\23@165409 by Jinx

face picon face
> No agitation or bubbler, other than a gentle rocking of the flat pan
> container back and forth. All done at room temps, say 70F. :)

Raising the temperature even a little will speed things up considerably.
The recommended maximum is ~ 55-60C. I haven't found out yet
whether that's because the FeCl3 starts breaking down (if so, possibly
the cause of your chlorine smell, but 60C seems a bit low for that) or
whether the Fe/Cu/Cl interaction changes at an excessive temperature,
causing the etching to be slower

2009\01\23@171636 by KPL

picon face
>
> IMHO you're severely underestimating what can be done with homebrew
> double sided. I don't care how much experience you have. I've seen
> "experienced" people make some stupid mistakes consistently throughout
> their career. Remember that thread about the EE who taught people to
> cold solder joints? Ya. I have no experience doing it but I've seen my
> teacher's end result on a home brew double sided toner transfer PCB.
> It was pretty complex and came out very well, way more than what I had
> expected. I was impressed.
>

Solarwind, there is a mailing list called Homebrew_PCBs on
yahoogroups, they have huge collective knowledge on this subject, it
may be worth to join that group and check their files area at least.

--
KPL

2009\01\23@175201 by sergio masci

flavicon
face


On Sat, 24 Jan 2009, Jinx wrote:

> > No agitation or bubbler, other than a gentle rocking of the flat pan
> > container back and forth. All done at room temps, say 70F. :)
>
> Raising the temperature even a little will speed things up considerably.
> The recommended maximum is ~ 55-60C. I haven't found out yet
> whether that's because the FeCl3 starts breaking down (if so, possibly
> the cause of your chlorine smell, but 60C seems a bit low for that) or
> whether the Fe/Cu/Cl interaction changes at an excessive temperature,
> causing the etching to be slower

I thought the problem with HOT etchent was that it damages the
photoresist? Surely the ABSOLUTE maximum is 50C.

Regards
Sergio Masci

2009\01\23@175725 by solarwind

picon face
On Fri, Jan 23, 2009 at 11:00 AM, William Chops Westfield
<RemoveMEwestfwTakeThisOuTspamspammac.com> wrote:
>
> On Jan 22, 2009, at 10:49 PM, solarwind wrote:
>
>> but I've seen my teacher's end result on a home brew double sided
>> toner transfer PCB.  It was pretty complex and came out very well
>
> Ah.  You have a local experienced mentor!  That should help a lot (and
> it explains this 'cheap access to expensive stuff' tone I've been
> hearing.)  I was assuming (and I suspect so were others) that you'd be
> starting from scratch on your own...

It's a "former" teacher (they don't like the term "old"). I don't have
access to him, just see him ocasionally around the school. He used to
work there but he retired and only comes in as a supply when the main
teacher gets sick or something. I am starting from scratch. I have no
"mentors".

{Quote hidden}

--
solarwind

2009\01\23@175845 by solarwind

picon face
On Fri, Jan 23, 2009 at 5:16 PM, KPL <EraseMEkpl.listesspamspamspamBeGonegmail.com> wrote:
> Solarwind, there is a mailing list called Homebrew_PCBs on
> yahoogroups, they have huge collective knowledge on this subject, it
> may be worth to join that group and check their files area at least.
>
> --
> KPL
> --

Thanks, I'll check it out.

--
solarwind

2009\01\23@175858 by solarwind

picon face
On Fri, Jan 23, 2009 at 8:32 PM, sergio masci <RemoveMEsmplxKILLspamspamallotrope.net> wrote:
> I thought the problem with HOT etchent was that it damages the
> photoresist? Surely the ABSOLUTE maximum is 50C.
>
> Regards
> Sergio Masci

I heard somewhere that one should heat to 100 degrees C.


--
solarwind

2009\01\23@181228 by sergio masci

flavicon
face


On Sat, 24 Jan 2009, Jinx wrote:

> In this table you'll see that copper has a greater affinity for -ve ions
> than iron

I hate to correct you but copper is less reactive than iron. Iron has a
greater tendency to lose an electron than copper does. If you look at it
like this copper should be unaffected by iron chloride. This does tend to
confuse people. However what you should be looking at is the tendency for
iron2+ to go to iron3+ and copper0+ to go to copper1+

then you will see that
copper0+ goes to copper1+ plus 1 electron
and
iron3+ plus 1 electron (from the copper above) goes to iron2+

It all comes down to the amount of energy required to remove a electron
from an atom or ion verses the amount of energy liberated by adding an
electron to another atom or ion.

Regards
Sergio Masci

2009\01\23@181728 by sergio masci

flavicon
face


On Fri, 23 Jan 2009, solarwind wrote:

> On Fri, Jan 23, 2009 at 8:32 PM, sergio masci <smplxSTOPspamspamspam_OUTallotrope.net> wrote:
> > I thought the problem with HOT etchent was that it damages the
> > photoresist? Surely the ABSOLUTE maximum is 50C.
> >
> > Regards
> > Sergio Masci
>
> I heard somewhere that one should heat to 100 degrees C.

I'm pretty sure this is wrong.

I've been using ammonium persulphate at 45C which is the recommended upper
limit. I have read that Iron Chloride is faster and needs a lower temp.

Regards
Sergio Masci

2009\01\23@190809 by Jinx

face picon face
> However what you should be looking at is the tendency for
> iron2+ to go to iron3+ and copper0+ to go to copper1+

Yes, that is the way to look at it, etching of copper by FeCl3
is a two-stage reaction

2009\01\23@194224 by Jinx

face picon face
> I thought the problem with HOT etchant was that it damages the
> photoresist?

Don't know about that. What I generally use now is a Sharpie and
I'd be guessing what's laid down would be carbon in quite a thin film,
probably much like the toner method. Never seen a problem with it
lifting or deteriorating. In fact it's possible to have the smallest whisker
bridges or fine detail in the resist that will get through the etching
undamaged

> Surely the ABSOLUTE maximum is 50C

The water-jacket method I use gets the etchant to about 60C, give
or take, depends on the start temperature of the etchant

Just to satisfy my own curiousity I'd like to find out why a limit of
55-60 is often mentioned

And don't call me Shirley

2009\01\23@202115 by Peter

picon face
FeCl3 etching is always done at over 35 degrees C, else it takes too long and
may cause pitting or other artifacts. The exact parameters depend on the
required speed and on what the resist can take. Industrial resist is baked after
solvent drying and will resist bath temperatures of over 70 degrees C (some
resist can take over 100 degrees C). FeCl3 is a mordant for Cu and it will etch
vertically (along the crystal grain) first, making pits. This is useful for
litography and not useful for PCB etching. The etch direction can be controlled
with additives (proprietary) and temperature. Higher temperature makes the etch
more isotropic (smoother). See pg 32 - 37 here:

dspace.lib.cranfield.ac.uk/bitstream/1826/1846/1/
Blondeau,%20Sebastien%20MSc.pdf

(paste on 1 line)

Peter


2009\01\23@202324 by sergio masci

flavicon
face


On Sat, 24 Jan 2009, Jinx wrote:

> > Surely the ABSOLUTE maximum is 50C
>
> The water-jacket method I use gets the etchant to about 60C, give
> or take, depends on the start temperature of the etchant
>
> Just to satisfy my own curiousity I'd like to find out why a limit of
> 55-60 is often mentioned
>
> And don't call me Shirley

Roger Roger.

2009\01\23@211241 by Jinx

face picon face
>
dspace.lib.cranfield.ac.uk/bitstream/1826/1846/1/Blondeau,%20Sebastien%2
0MSc.pdf

Interesting, thanks

> > And don't call me Shirley
>
> Roger Roger

"Huh ?" ;-)

http://www.imdb.com/title/tt0080339/quotes



2009\01\24@185952 by bob.axtell

face picon face
Hi Solarwind,

I think trying to do this stuff is a great waste of time. Just layout
the PCB & send it to AP Circuits in Canada or one of the myriad
prototype houses. For the $75 you might save "rolling yer own"
there is a LOT of grief attached.

Are you married? Fooling around with Ferric Chloride will get
you locked out of the house in a New York Minute.

--Bob A



On 1/22/09, solarwind <spamBeGonex.solarwind.xSTOPspamspamEraseMEgmail.com> wrote:
{Quote hidden}

> -

2009\01\24@201628 by solarwind

picon face
On Sat, Jan 24, 2009 at 6:59 PM,  <KILLspambob.axtellspamBeGonespamgmail.com> wrote:
> Hi Solarwind,
>
> I think trying to do this stuff is a great waste of time. Just layout
> the PCB & send it to AP Circuits in Canada or one of the myriad
> prototype houses. For the $75 you might save "rolling yer own"
> there is a LOT of grief attached.
>
> Are you married? Fooling around with Ferric Chloride will get
> you locked out of the house in a New York Minute.
>
> --Bob A

No, I'm not married. I want to, but unfortunately marriage can only be
with one other person. I have too many girlfriends.

--
solarwind

2009\01\24@202023 by sergio masci

flavicon
face


On Fri, 23 Jan 2009, apptech wrote:

{Quote hidden}

Nah, real men use platimum pentafloride (the stuff that even reacts with
noble gasses like xenon)

You just threaten to use it on the PCB and it's done :-)

Regards
Sergio Masci

2009\01\24@204801 by Vitaliy

flavicon
face
"Microcontroller discussion list - Public." wrote:
> I think trying to do this stuff is a great waste of time. Just layout
> the PCB & send it to AP Circuits in Canada or one of the myriad
> prototype houses. For the $75 you might save "rolling yer own"
> there is a LOT of grief attached.

I was able to convince a student whose project we're sponsoring to have his
PCB done professionally. Unfortunately, he decided to save some money, and
sent his gerbers to a Chinese PCB maker (I forget the name, it was mentioned
on this list recently). Murphy intervened, and they won't be able to ship
the boards until the end of the Lunar New Year, which would in the best case
leave him eight days to assemble, program, and test his project. For
time-sensitive stuff, I would definitely go with a US-based manufacturer --  
Advanced Circuits lets students buy PCBs for $33 each, and they don't take
three week vacations.

> Are you married? Fooling around with Ferric Chloride will get
> you locked out of the house in a New York Minute.

LOL! :)

I am lucky to have a very patient and understanding spouse (in many ways,
she's a saint). She just asked me if I could do the etching on the balcony,
and clean the sink after use. CLR works wonders on the plastic sinks, you
just let it sit for 15 minutes or so, and you can wipe the rust off with
your finger.

Solarwind isn't married, but FeCl3 can surely get him in trouble with his
parents. :)

Vitaliy

2009\01\24@211542 by Joseph Bento

face
flavicon
face

On Jan 24, 2009, at 6:16 PM, solarwind wrote:
>
> No, I'm not married. I want to, but unfortunately marriage can only be
> with one other person. I have too many girlfriends.


Well, just choose one and beat the others off with a stick!  :-)


Joe

2009\01\24@213748 by solarwind

picon face
On Sat, Jan 24, 2009 at 9:15 PM, Joseph Bento <EraseMEjosephspamEraseMEkirtland.com> wrote:
>
> On Jan 24, 2009, at 6:16 PM, solarwind wrote:
>>
>> No, I'm not married. I want to, but unfortunately marriage can only be
>> with one other person. I have too many girlfriends.
>
>
> Well, just choose one and beat the others off with a stick!  :-)
>
>
> Joe

Lol, if I chose one, it would get boring. Besides, the beating I'll be
doing wont be with a stick.


--
solarwind

2009\01\24@215416 by Sean Breheny

face picon face
On Sat, Jan 24, 2009 at 8:16 PM, solarwind <@spam@x.solarwind.x@spam@spamspam_OUTgmail.com> wrote:
> No, I'm not married. I want to, but unfortunately marriage can only be
> with one other person. I have too many girlfriends.

Sounds like a nice problem to have!!!

>
> --
> solarwind
> -

2009\01\25@080706 by apptech

face
flavicon
face
> For
> time-sensitive stuff, I would definitely go with a US-based
> manufacturer --
> Advanced Circuits lets students buy PCBs for $33 each, and they don't take
> three week vacations.

Chinese new year is usually 10 days.
And it's by far the largest holiday taken. Outside that period you are
liable to et them to work 8 days a week, sometimes 9.

That said, it depends how westernised the firm has got. Some work Sundays
without a qualm while others actually do do 40 hour weeks. Then others I've
seen do 7 day 70 hour weeks ... .

FWIW: I'll be back in China just after the new year celebrations end.



     Russell


2009\01\25@123749 by Vitaliy

flavicon
face
"apptech" wrote:
> Chinese new year is usually 10 days.
> And it's by far the largest holiday taken.

You've got to figure in the travel time, too.


> Outside that period you are
> liable to et them to work 8 days a week, sometimes 9.

I work this kind of schedule myself. :)


> That said, it depends how westernised the firm has got. Some work Sundays
> without a qualm while others actually do do 40 hour weeks. Then others
> I've
> seen do 7 day 70 hour weeks ... .

That *is* pretty crazy.


> FWIW: I'll be back in China just after the new year celebrations end.

I hope there will be more pictures?

Vitaliy

2009\01\25@135528 by Richard Prosser

picon face
2009/1/26 apptech <spamBeGoneapptechspamKILLspamparadise.net.nz>:
{Quote hidden}

Russel

So will I - I'm in Shenzhen from the 5th to about the 18th, how about you?

Richard

2009\01\25@212048 by Peter

picon face
William "Chops" Westfield <westfw <at> mac.com> writes:
> > I can honestly say I've never smelled chlorine whilst etching

As you may have read in the pdf document linked by me before, FeCl3 etches by
releasing Cl ions into the solution. It is very likely that the presence of some
impurites can cause HCl and other toxic chemicals to be released into the air
bubbles that percolate through the solution. The FeCl3 bath has a peculiar
characteristic smell, but that is not the smell of chlorine. Adding certain
chemicals to the bath while trying to neutralize it can produce really bad
fumes, however.

Peter


2009\01\25@213250 by Forrest W Christian

flavicon
face
Back when I was etching boards myself, I was a big fan of ammonium
persulphate.   Much less nasty than Ferric Chloride.

-forrest

Peter wrote:
{Quote hidden}

2009\01\25@214901 by solarwind

picon face
On Sun, Jan 25, 2009 at 9:30 PM, Forrest W Christian <.....forrestcspam_OUTspamimach.com> wrote:
> Back when I was etching boards myself, I was a big fan of ammonium
> persulphate.   Much less nasty than Ferric Chloride.
>
> -forrest

I'll give that a try - thanks.

--
solarwind

2009\01\26@032924 by Jinx

face picon face
> persulphate.   Much less nasty than Ferric Chloride.

I agree but add that in any situation there is only potential for
nastiness. What ? Well, FeCl3 is only nasty if you allow it to do
something you shouldn'ta

Treat it with care and pay attention. Wear a smock and eye
protection, don't drink it, don't splash it around or use on a
surface that you don't worry about messing up and dispose
of it conscientiously

Compared with most other life hazards, especially those around
the workshop, it's not a biggie

2009\01\26@120915 by Isaac Marino Bavaresco

flavicon
face
Jinx escreveu:
>> persulphate.   Much less nasty than Ferric Chloride.
>>    
>
> I agree but add that in any situation there is only potential for
> nastiness. What ? Well, FeCl3 is only nasty if you allow it to do
> something you shouldn'ta
>
> Treat it with care and pay attention. Wear a smock and eye
> protection, don't drink it, don't splash it around or use on a
> surface that you don't worry about messing up and dispose
> of it conscientiously
>
> Compared with most other life hazards, especially those around
> the workshop, it's not a biggie
>  

I started using FeCl3 when I was 12 years old. Now I am 38 and don't
think it affected may health in any way.

In the early years, I used to stain my hands and clothes with it and
breathing its vapors. The stains  lasted weeks in the skin and forever
in the clothes.

Now I use the services of a local shop that makes photolithographic
films and cliché (metallic stamp) for the printing industries. They
provide a semi-professional PCB service (industry quality etched board
without solder mask, silk-screen or drilling). I send them the Gerber
files by e-mail and after +- 4 hours the board is ready.

Usually each board below 5"x5" costs around US$7.00 (bigger boards cost
a little more).

I probably will never etch my own prototype boards again.

I think other shops in this business that etch metal cliché may do PCBs
either. Just go there and ask if they are interested in making prototype
PCBs.

Best regards,

Isaac
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2009\01\26@141938 by solarwind

picon face
On Mon, Jan 26, 2009 at 11:41 AM, Isaac Marino Bavaresco
<TakeThisOuTisaacbavaresco.....spamTakeThisOuTyahoo.com.br> wrote:
> Now I use the services of a local shop that makes photolithographic
> films and cliché (metallic stamp) for the printing industries. They
> provide a semi-professional PCB service (industry quality etched board
> without solder mask, silk-screen or drilling). I send them the Gerber
> files by e-mail and after +- 4 hours the board is ready.
>
> Usually each board below 5"x5" costs around US$7.00 (bigger boards cost
> a little more).
>
> I probably will never etch my own prototype boards again.
>
> I think other shops in this business that etch metal cliché may do PCBs
> either. Just go there and ask if they are interested in making prototype
> PCBs.
>
> Best regards,
>
> Isaac

That certainly sounds interesting. So basically you give them a blank
copper clad board and they do a single sided PCB for you?

--
solarwind

2009\01\26@144514 by Isaac Marino Bavaresco

flavicon
face
solarwind escreveu:
{Quote hidden}

They have already some blank PCB panels in stock.
And they do double-sided also, I just need to drill it myself.


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2009\01\26@144538 by Isaac Marino Bavaresco

flavicon
face
solarwind escreveu:
{Quote hidden}

They have already some blank PCB panels in stock.
And they do double-sided also, I just need to drill it myself.


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2009\01\26@153647 by solarwind

picon face
On Mon, Jan 26, 2009 at 2:44 PM, Isaac Marino Bavaresco
<RemoveMEisaacbavarescospamspamBeGoneyahoo.com.br> wrote:
> They have already some blank PCB panels in stock.
> And they do double-sided also, I just need to drill it myself.

What method do they use to produce it?


--
solarwind

2009\01\26@174510 by Jinx

face picon face
> Now I use the services of a local shop that makes photolithographic
> films and cliché (metallic stamp) for the printing industries

Isaac, don't get me wrong. For quantity and quality I always use the
professionals, but etch my own one-offs, prototypes, test boards, and
those funny little boards you sometimes need (like a little SMT to DIP).\

I go through a lot of proto boards for various ideas and products at
different stages and if I couldn't do my own it would be very inconveneient.
Breadboards are OK too but they have their limits

Cost is not a significant factor, but in the time it takes to draw it all up
with
a CAD package and get it to the board house I can have a hand-made one
ready to use. And that's not forgetting the several days waiting for the board
house. When you need a board, any board, to work with and you need it,
to quote Steve Martin, "right %#$^ing now", there's nothing wrong with a
home-brew

2009\01\26@180521 by solarwind

picon face
On Mon, Jan 26, 2009 at 6:43 PM, Jinx <spamBeGonejoecolquitt@spam@spamspam_OUTclear.net.nz> wrote:
> Isaac, don't get me wrong. For quantity and quality I always use the
> professionals, but etch my own one-offs, prototypes, test boards, and
> those funny little boards you sometimes need (like a little SMT to DIP).\
>
> I go through a lot of proto boards for various ideas and products at
> different stages and if I couldn't do my own it would be very inconveneient.
> Breadboards are OK too but they have their limits
>
> Cost is not a significant factor, but in the time it takes to draw it all up
> with
> a CAD package and get it to the board house I can have a hand-made one
> ready to use. And that's not forgetting the several days waiting for the board
> house. When you need a board, any board, to work with and you need it,
> to quote Steve Martin, "right %#$^ing now", there's nothing wrong with a
> home-brew
>
>

Well put. Thank you.

--
solarwind

2009\01\26@194059 by Isaac Marino Bavaresco

flavicon
face
Jinx escreveu:
>> Now I use the services of a local shop that makes photolithographic
>> films and cliché (metallic stamp) for the printing industries
>>    
>
> Isaac, don't get me wrong. For quantity and quality I always use the
> professionals, but etch my own one-offs, prototypes, test boards, and
> those funny little boards you sometimes need (like a little SMT to DIP).\
>  

For production batches, of course I use the service of professional
shops, with components silk-screen, solder mask, plated holes (for
multi-layer boards) and HAL Sn-Pb.

> I go through a lot of proto boards for various ideas and products at
> different stages and if I couldn't do my own it would be very inconveneient.
> Breadboards are OK too but they have their limits
>  
I usually draw a board and make a prototype, then adjust the circuit by
cutting/bridging traces and changing component values. After everything
is OK I rework the first design and make the final boards. If I´m not
100% confident I make one more prototype.

It´s hard to breadboard or proto-board circuits with several 100-pin
0.5mm pitch ICs. I don´t like adapters also, and they are expensive too.
And for some circuits proto-boards may introduce undesirable effects.

I use proto-boards only to pre-test sub-circuits that I think may be
hard to get right.

> Cost is not a significant factor, but in the time it takes to draw it all up
> with
> a CAD package and get it to the board house I can have a hand-made one
> ready to use. And that's not forgetting the several days waiting for the board
>  
The shop I use for prototypes is here in my city and they make my boards
the same day. I send them the files by e-mail in the morning and receive
the boards by courier in the afternoon.

> house. When you need a board, any board, to work with and you need it,
> to quote Steve Martin, "right %#$^ing now", there's nothing wrong with a
> home-brew
>  
Of course it´s OK to etch your boards, but I found their services so
convenient that I´m not compelled to do it myself anymore. Besides, I
can´t reach their 8000+ DPI quality.

Regards,

Isaac
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2009\01\26@195351 by Isaac Marino Bavaresco

flavicon
face
solarwind escreveu:
> On Mon, Jan 26, 2009 at 2:44 PM, Isaac Marino Bavaresco
> <TakeThisOuTisaacbavarescospamspamyahoo.com.br> wrote:
>  
>> They have already some blank PCB panels in stock.
>> And they do double-sided also, I just need to drill it myself.
>>    
>
> What method do they use to produce it?
>  
They make the film in a laser photoplotter, then sensitize (cover) the
boards with photoresist and expose the board to a special light, with
the film on top of it.
Then they use some nasty chemicals to remove the un-exposed resist and
etch the exposed copper with FeCl3.

To finish, the hardened resist is removed with caustic soda.

The drilling I do myself.


Best regards,

Isaac

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2009\01\26@202809 by solarwind

picon face
On Mon, Jan 26, 2009 at 7:53 PM, Isaac Marino Bavaresco
<isaacbavarescoEraseMEspamyahoo.com.br> wrote:
> They make the film in a laser photoplotter, then sensitize (cover) the
> boards with photoresist and expose the board to a special light, with
> the film on top of it.
> Then they use some nasty chemicals to remove the un-exposed resist and
> etch the exposed copper with FeCl3.
>
> To finish, the hardened resist is removed with caustic soda.
>
> The drilling I do myself.
>
>
> Best regards,
>
> Isaac

Do they do through-hole plating? Also, if I were to look for one of
these places in my area, how would I find it?


--
solarwind

2009\01\26@205418 by Jinx

face picon face

> It´s hard to breadboard or proto-board circuits with several 100-pin
> 0.5mm pitch ICs

Agree with that completely, but it's hard to ignore that little voice saying
"Yeah, go on, you can do it". 1mm I'd have a look at, not 0.5mm. Tried
and failed. Still, that's how you find out

I think I do what most people would do. If it's a job you can do reasonably
competently or better, then DIY. eg a lot of jobs I've done (to a good
standard IMVHO) around the house.  I wouldn't even think of getting a
builder or a painter in. I wouldn't get an IT wiz to lay LAN cables either.
There are times when you need professionals, times when you don't, and
it's not always so simple as having or saving $$$ or being/not being capable
of doing it yourself

2009\01\26@205958 by Isaac Marino Bavaresco

flavicon
face
solarwind escreveu:
{Quote hidden}

No, they don´t do through-hole plating.

I´m in Brazil and speak Portuguese, but the English equivalent would be
"photo-engraver".

Try these keywords also: photolith film, flexography, photoplotter, etch.

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2009\01\27@003147 by Peter

picon face
Forrest W Christian <forrestc <at> imach.com> writes:
> persulphate.   Much less nasty than Ferric Chloride.

FeCl3 is used in industrial quantities in water treatment plants. It is not
particularly nasty as a chemical (it is a close relative of common rust, so to
speak). Don't drink it, don't get it into your eyes and don't worry about it.
The nasty part is the copper salts that appear in used etching baths. That is
toxic (the copper), not the FeCl3.

Peter


2009\01\27@124638 by Peter

picon face
solarwind <x.solarwind.x <at> gmail.com> writes:
> I want to build a simple tank with a heater because I want to make

I used a tupperware/rubbermaid style hinged lid, tall, rectangular container to
keep 1 liter of FeCl3 solution and made my boards in it for more than 2 years.
The closed lid keeps air out and the solution viable for longer. Air will kill
the solution faster than the boards you make.

FeCl3 comes in pebble like rust colored lumps. You put them in the container
and cover with water from the hot water kettle, and stir until dissolved.
That's it mostly. If you want to be accurate get a liquid density gauge (the
kind used for tomato juice is right) and adjust the density with water until
it is just right (32 degrees Baume at 50 deg. C). Let it sit for a few hours
before first use.

My high tech way to do it X years ago was:

1. put a large pebble in the FeCl3 container so it won't float (see below)
2. put an old phone book on the floor (thermal insulation and spill soak-up)
3. put a 2-3l tupperware container on the phone book
4. pour +1l of boiling water from the kettle into the large container
5. put the weighted (pebble) etchant container in the large container
6. wait about 5-10 minutes for the etchant to heat up a little
7. put the board in the etchant container and etch for 20-25 minutes with
occasional rocking. The board was hung by fishing line monofilament from a
pencil or wood stick (brush handle) that sat on top the etchant container.
Periodically remove the board to inspect it against a strong light for
etching completion and problems. Drill a hole in the edge of the board to
thread the monofilament through. The board should not touch the container
while hanging in the etchant.

My high tech way I did not implement (never needed it):

1. use a flat container for the etchant (tray like)
2. obtain a cardboard box that is slightly smaller than it
3. cut the lid off the cardboard box, line it with aluminum foil and mount a
40-75 Watt light fixture and bulb in it (wattage tbd)
4. duct tape the cardboard box to the bottom of the tray (around it) using
heavy duty tape. The other sode of the box can be opened to change bulbs.
5. fill the bath with H2O, turn on the light, and use a liquid thermometer to
get the right wattage that keeps the H2O at 45-55 deg. C indefinitely.
6. replace the H2O with FeCl3 solution and etch boards in style, while the
light shining through the bottom of the plastic container allows etching
inspection without removing the board, besides keeping the solution at the
right temperature.
7. optionally add a $2 'cocktail stirrer' (with plastic stirrer paddle) to be
clamped to the tray and agitate the solution.

(you first saw it here)
Peter

PS: FeCl3 tends to corrode everything so it is a no shipping item. Obtain it
locally from a chemical supply. It only costs a few dollars per pound/kg.

PS2: Wrt toxicity and MSDS - compare the msds sheets of NaCl and FeCl3 :) :)
(hint: salt is to be kept 'locked up' and is 'mutagenic to mammalian somatic
cells' - the other ingredient of the solution is dihydorgen monoxyde, also
dangerous when ingested in large quantities or inhaled)


2009\01\27@141021 by solarwind

picon face
On Tue, Jan 27, 2009 at 12:45 PM, Peter <@spam@plpeter2006RemoveMEspamEraseMEyahoo.com> wrote:
{Quote hidden}

Your high-tech way is genious. Bud do you think an incandescent bulb
of 40 - 75 watt will release enough heat to keep the solution at 50
degrees C?


--
solarwind

2009\01\27@145332 by olin piclist

face picon face
solarwind wrote:
> Bud do you think an incandescent bulb
> of 40 - 75 watt will release enough heat to keep the solution at 50
> degrees C?

Incandescent bulb are crappy light generators, but very cheap and effective
resistive heaters.  40 to 75 watts of incandescent bulb will get you 39 to
73 watts of heat or so.


********************************************************************
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(978) 742-9014.  Gold level PIC consultants since 2000.

2009\01\27@153119 by solarwind

picon face
On Tue, Jan 27, 2009 at 2:53 PM, Olin Lathrop <EraseMEolin_piclistspam@spam@embedinc.com> wrote:
> Incandescent bulb are crappy light generators, but very cheap and effective
> resistive heaters.  40 to 75 watts of incandescent bulb will get you 39 to
> 73 watts of heat or so.

Wow. Time to make a light box. Damn ya learn something new every day.
I searched and searched on Google but I kept getting the same old fish
tank bubble results... I never get anything new or innovative like
this. I've also searched for etching PCBs and I didn't hear of the
direct inkjet-to-copper clad method till someone mentioned it on this
list.


--
solarwind

2009\01\27@170651 by Peter

picon face
solarwind <x.solarwind.x <at> gmail.com> writes:
> > Incandescent bulb are crappy light generators, but very cheap and effective
> > resistive heaters.  40 to 75 watts of incandescent bulb will get you 39 to
> > 73 watts of heat or so.
>
> Wow. Time to make a light box. Damn ya learn something new every day.

Actually an incandescent light makes for a crappy light box. Use an energy
saving 'electronic' lamp for that, and a diffuser (calque drawing paper works in
a pinch). As Olin has noticed, the incandescent bulb provides both light and
heat, and about as much heat as an aquarium heater provides, which is about the
right size for that kind of etching tray job.

Peter


2009\01\27@171926 by olin piclist

face picon face
solarwind wrote:
>> Incandescent bulb are crappy light generators, but very cheap and
>> effective resistive heaters.  40 to 75 watts of incandescent bulb
>> will get you 39 to 73 watts of heat or so.
>
> Wow. Time to make a light box.

It seems you got it backwards.  If you want light, incandescent bulbs would
be the last choice.  I was trying to point out that they are far better
heaters than light sources.  If I remember right, something like 2.5%
efficient light sources, which would make them 97.5% efficient heaters even
if all the light escapes.  A plain old resistor is a 100% efficient heater,
but nowhere near as cheap and available as incandescent bulbs at 10s of
watts.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.

2009\01\27@171937 by solarwind

picon face
On Tue, Jan 27, 2009 at 5:06 PM, Peter <@spam@plpeter2006spam_OUTspam.....yahoo.com> wrote:
> Actually an incandescent light makes for a crappy light box. Use an energy
> saving 'electronic' lamp for that, and a diffuser (calque drawing paper works in
> a pinch). As Olin has noticed, the incandescent bulb provides both light and
> heat, and about as much heat as an aquarium heater provides, which is about the
> right size for that kind of etching tray job.
>
> Peter

Yeah, that's what I meant. I'll use it for its heat output.


--
solarwind

2009\01\27@172455 by solarwind

picon face
On Tue, Jan 27, 2009 at 5:19 PM, Olin Lathrop <spamBeGoneolin_piclistEraseMEspamembedinc.com> wrote:
> It seems you got it backwards.  If you want light, incandescent bulbs would
> be the last choice.  I was trying to point out that they are far better
> heaters than light sources.  If I remember right, something like 2.5%
> efficient light sources, which would make them 97.5% efficient heaters even
> if all the light escapes.  A plain old resistor is a 100% efficient heater,
> but nowhere near as cheap and available as incandescent bulbs at 10s of
> watts.

I got it right, lol, I just used the wrong word. I meant heat box.
Heat box. Yes.


--
solarwind

2009\01\27@174422 by sergio masci

flavicon
face


On Tue, 27 Jan 2009, solarwind wrote:

{Quote hidden}

Try again - you mean an oven :-)

Regards
Sergio Masci

2009\01\27@181300 by Peter

picon face
solarwind <x.solarwind.x <at> gmail.com> writes:
> Yeah, that's what I meant. I'll use it for its heat output.

You use it for both light and heat. The light will shine through the bottom of
the plastic tray and through the board being etched and the solution, so you can
see when the etching is about done, as well as small misplaced things and dirt
in the solution. The light will go through the 1-2 cm deep solution and the
board (where there is no copper).

Peter


2009\01\27@193639 by Nate Duehr

face
flavicon
face
Wow, I'm kinda surprised this isn't more widely known.  

I've seen people use incandescent bulb lamps under sinks in houses that were
"closed up for winter" as poor-man's anti-pipe-freezing tools, and at least
one radio club that was having radio problems with a mountain-top site that
had plenty of power, but no built in heating system, use a 100W bulb and
some judicious use of cardboard (around the radio, to keep the heat from
rising up the cabinet), to keep a crystal on-frequency until repairs could
be made the next summer.

Drop-lights... they're not just for lighting anymore!  (GRIN)

Nate

{Original Message removed}

2009\01\28@133717 by Alan B. Pearce

face picon face
>Wow, I'm kinda surprised this isn't more widely known.

Me too ...

>I've seen people use incandescent bulb lamps under sinks
>in houses that were "closed up for winter" as poor-man's
>anti-pipe-freezing tools,
...

I new of a guy who lived in Fiji, who used a 15W pygmy lamp in the bottom of
the cupboard where he stored his photographic equipment, to keep the
equipment at a temperature where the humidity was lowered enough to keep
fungi from growing on lenses, and generally limit the effects of the
humidity on the rest of the gear. This was all around 40 years ago.

2009\01\28@142855 by Bob Axtell

face picon face
In my young engineer days at Texas Instruments I was sent on a field
trip to repair a semi-custom piece of electronic gear in central
America (Guatemala). For two weeks
I lived in a house near the beach.

There was a 75watt incandescent bulb always on in the clothes closet.
I was told that if it were turned off or removed, the humidity and the
insects would ravage the clothes. It seemed
to work for me.

The problem took a while to solve. It turned out that critical PCBs in
the ailing system had to be sprayed with a plastic spray to prevent
moisture from condensing on the PCB surfaces.
I used Scotch (3M) polaroid film coating; its all I could find in that village.

Fun stuff.

--Bob

On Wed, Jan 28, 2009 at 11:37 AM, Alan B. Pearce
<RemoveMEAlan.B.Pearce@spam@spamspamBeGonestfc.ac.uk> wrote:
{Quote hidden}

> -

2009\01\28@165437 by William \Chops\ Westfield

face picon face
>> [incandescent lamps as heaters.]

> I'm kinda surprised this isn't more widely known.

It *IS* widely known.  There must be hundreds of children's toys over  
the last 50 years that use a light bulb as the heating source for all  
sorts of oven-like devices, starting with your classic "Easy Bake  
Oven"...

BillW

2009\01\28@174822 by Tamas Rudnai

face picon face
> No, I'm not married. I want to, but unfortunately marriage can only be
> with one other person. I have too many girlfriends.

There are some countries where you can have up to 4 wifes if you have enough
money. You may need to change location and religion :-)

Tamas
PS: For me 1 is too many sometimes, especially when I want to work on
something late night :-)


On Sun, Jan 25, 2009 at 1:16 AM, solarwind <.....x.solarwind.x@spam@spamEraseMEgmail.com> wrote:

{Quote hidden}

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