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'[EE]: First PCB!'
2003\06\17@123721 by Alex Kilpatrick

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I wanted to show off my first attempt at making a PCB.  I wanted to see
if I could make something as small as a SSOP package for a PIC16F628.
This package has a pitch of .65 mm, which is pretty small to me.
Here is a picture: home.austin.rr.com/kilpatrick/FirstPCB.JPG
(note that I didn't bother to etch the entire board.
The results were outstanding, much better than I expected.  The lines
are much sharper than they look in the picture.  The only problem I had
was one bit of copper left between a line and a pad.  I think that would
have come off if I had kept etching longer.
For those of you with experience with this kind of stuff -- do you need
to worry about etching too long (within reason)?  I am paranoid that if
I leave it in too long, I may start to lose some of my thin traces.
Alex

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2003\06\17@132545 by Mike Hord

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What method did you use for your resist mask?  I've been experimenting
lately
with direct toner transfer and have had uniformly horrible results.

I'm thinking of just going straight to positive exposed UV, as I've done
that in
the past and had much better results.

Mike H.


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2003\06\17@132549 by Paul James E.

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Alex,

What method did you use to put the pattern on the bare board?
Photographic?   Direct Etch patterns?

Whatever method you used, it looks good.

                           Regards,

                             Jim



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2003\06\17@140817 by Picdude

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On Tuesday 17 June 2003 11:35, Alex Kilpatrick scribbled:
> I wanted to show off my first attempt at making a PCB.  I wanted to see
> if I could make something as small as a SSOP package for a PIC16F628.
> This package has a pitch of .65 mm, which is pretty small to me.
>
> Here is a picture: home.austin.rr.com/kilpatrick/FirstPCB.JPG
> (note that I didn't bother to etch the entire board.

Nice.  What mil traces/spaces did you use?  Make sure you remove the resist to ensure that there are no breaks and under-cutting.  

> The results were outstanding, much better than I expected.  The lines
> are much sharper than they look in the picture.  The only problem I had
> was one bit of copper left between a line and a pad.  I think that would
> have come off if I had kept etching longer.

This is where agitating the board really helps ... it makes the etching much more even.


> For those of you with experience with this kind of stuff -- do you need
> to worry about etching too long (within reason)?  I am paranoid that if
> I leave it in too long, I may start to lose some of my thin traces.

Yes.  Too long is a problem.  Agitate and heat has given me excellent board consistency in the past.  Try it, even if manual .... I used to use a hair-dryer on low speed to do this in the past, and then upgraded to air-pump, etc.

Cheers,
-Neil.

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2003\06\17@141734 by Picdude

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I scribbled:
> On Tuesday 17 June 2003 11:35, Alex Kilpatrick scribbled:
> > For those of you with experience with this kind of stuff -- do you need
> > to worry about etching too long (within reason)?  I am paranoid that if
> > I leave it in too long, I may start to lose some of my thin traces.
>
> Yes.  Too long is a problem.  Agitate and heat has given me excellent board
> consistency in the past.  Try it, even if manual .... I used to use a
> hair-dryer on low speed to do this in the past, and then upgraded to
> air-pump, etc.

Word of caution here ... make sure you use a deep container for this when agitating, since ferric chloride (if that's what you're using) will stain everything.

Cheers,
-Neil.

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2003\06\17@145941 by Spehro Pefhany

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At 01:17 PM 6/17/2003 -0500, you wrote:

>Word of caution here ... make sure you use a deep container for this when
>agitating, since ferric chloride (if that's what you're using) will stain
>everything.

The fumes will also quickly rust fine steel such as machine tools.

Best regards,

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2003\06\17@184735 by Alex Kilpatrick

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>
>
>
>  Alex,
>
>  What method did you use to put the pattern on the bare board?
>  Photographic?   Direct Etch patterns?  
>
>  Whatever method you used, it looks good.
>
>                             Regards,
>
>                               Jim
>
I used a laser printer and a transparency.  The laser printer is 600
dpi, although it has a 1200 dpi mode that does <mumble> <mumble>
<mumble> to make things a little sharper.

Alex

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2003\06\17@185152 by Alex Kilpatrick

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>
> Nice.  What mil traces/spaces did you use?  Make sure you
> remove the resist to
> ensure that there are no breaks and under-cutting.  
>
I honestly don't know.  I used the autorouter in Eagle, and it does
whatever it wants to do.  I can't figure out how to change the size of
the traces.  Any help here?


Alex

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2003\06\17@185203 by Alex Kilpatrick

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> >
> > Yes.  Too long is a problem.  Agitate and heat has given me
> excellent
> > board consistency in the past.  Try it, even if manual ....
> I used to
> > use a hair-dryer on low speed to do this in the past, and then
> > upgraded to air-pump, etc.
>
> Word of caution here ... make sure you use a deep container
> for this when
> agitating, since ferric chloride (if that's what you're
> using) will stain
> everything.
>
Yes, I found out it stains driveways, even when heavily dilluted  :-(

For agitation, can you just use an aquarium air pump?  Do you use a
diffuser?

Alex

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2003\06\17@190412 by Alex Kilpatrick

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>
> >
> > Nice.  What mil traces/spaces did you use?  Make sure you
> > remove the resist to
> > ensure that there are no breaks and under-cutting.  
> >
>
> I honestly don't know.  I used the autorouter in Eagle, and it does
> whatever it wants to do.  I can't figure out how to change the size of
> the traces.  Any help here?
>
Nevermind, I figured it out.  Eagle is *so* unintuitive.  The idea of
picking the action, then the object is really weird.

Anyhow, these are 10 mil traces, and a routing grid of 14 mil.  I tried
it a little bigger, but I got vias.

Also, the boards I have (MG Chemicals) say not to remove the resists,
because it provides protection.

Alex

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2003\06\17@191649 by William Chops Westfield

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   > Nice.  What mil traces/spaces did you use?  Make sure you remove the
   > resist to ensure that there are no breaks and under-cutting.

   I honestly don't know.  I used the autorouter in Eagle, and it does
   whatever it wants to do.  I can't figure out how to change the size of
   the traces.  Any help here?

You can change the trace width either with the "class" command (which allows
multiple classes of net, each with its own width/etc), or by changing the
minimum trace width in the Design Rules boxes.

I find the default widths distressingly small for homebrew boards, but
perhaps I'm overly conservative.  And it's probably more appropriate for
your SSOP-based board than the DIP or discreet boards I've been mostly
dealing with...  Toner transfer also seems to "spread" a bit, and my LPKF
may be routing off wider bits than it really should, and... LOTS of bits of
information go into picking your trace widths, and they tend to conflict
with each other (what you really want is wide traces with plenty of room
between them...)

BillW

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2003\06\17@191659 by Picdude

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On Tuesday 17 June 2003 17:51, Alex Kilpatrick scribbled:
> Yes, I found out it stains driveways, even when heavily dilluted  :-(

Lucky for you, you found out on a driveway.  :-(


> For agitation, can you just use an aquarium air pump?  Do you use a
> diffuser?

IIRC, you are in Austin, right?  Petco on Great Hills Tr. has a small aquarium pump called a Profile 1000 (or something like that).  <$10 and works well for me.  Very quiet too.  Not sure what you mean by diffuser, so I guess that answer is no :-)

Cheers,
-Neil.

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2003\06\17@193137 by Alex Kilpatrick

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>
>
> > For agitation, can you just use an aquarium air pump?  Do you use a
> > diffuser?
>
> IIRC, you are in Austin, right?  Petco on Great Hills Tr. has
> a small aquarium
> pump called a Profile 1000 (or something like that).  <$10
> and works well for
> me.  Very quiet too.  Not sure what you mean by diffuser, so
> I guess that
> answer is no :-)
>
Yep, I'm in Austin (Round Rock).  Maybe we should get together and
compare notes.

I also do stuff with aquariums.  A diffuser (also called an airstone)
breaks up air into millions of tiny bubbles.  It would probably help
with etching, if I understand the process correctly.

Alex

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2003\06\17@194150 by Mike Hord

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> > For agitation, can you just use an aquarium air pump?  Do you use a
> > diffuser?
>
>IIRC, you are in Austin, right?  Petco on Great Hills Tr. has a small
>aquarium
>pump called a Profile 1000 (or something like that).  <$10 and works well
>for
>me.  Very quiet too.  Not sure what you mean by diffuser, so I guess that
>answer is no :-)

I'm etching boards these days in a 1 gal aquarium that came from K-Mart
with an air pump and a diffuser.  Not a bad deal at $9!

A 25 W heater doesn't seem to be enough to heat the solution up
too much.  I guess I may try a larger one, but it works well enough at
room temp for me not to be too worried.

Incidentally, I'm using sodium persulphate for etching.  Does anyone know
anything about its toxicity compared to Ferric chloride?  It seems more
benign
to me; right now I have it in a fume hood but would like to move it out.  Is
that a bad idea?  I won't do it if anyone has any negative input on that
idea.

Mike H.

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2003\06\17@222551 by Marc Nicholas

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On 17/6/03 19:40, "Mike Hord" <EraseMEgaidinmdspam_OUTspamTakeThisOuTHOTMAIL.COM> wrote:

> Incidentally, I'm using sodium persulphate for etching.  Does anyone know
> anything about its toxicity compared to Ferric chloride?  It seems more benign
> to me; right now I have it in a fume hood but would like to move it out.  Is
> that a bad idea?  I won't do it if anyone has any negative input on that idea.

Here's an MSDS for you: http://www.mgchemicals.com/msds/english/4101.pdf

You should be reading an MSDS (Material Saftey Data Sheet) with pretty much
any chemical you're using that you're not sure about. They do err on the
side of caution (ever read the MSDS for water?), but you'll get a general
sense of issues.

Once-upon-a-time, I was an organic chemist of sorts. I've done some pretty
stupid/dangerous stuff (like the day I spilled H2SO4 on my hand!), so now
tend to a bit paranoid. If you have a fumehood, I'd use it...just because
sodium persulphate is a respiratory irritant, and having an irritated
respiratory tract ain't fun for most people. Oh, and wear thick walled
rubber or silicone gloves.

As for it's toxicity compared to ferric chloride, I'd stick with the sodium
persulphate. Ferric chloride is a corrosive substance and repeated exposure
can cause liver issues and eventual liver damage. If your eyes start to
change colour (go yellow) and you're etching PCBs with ferric chloride,
don't say I didn't warn you. ;-)

Two final comments: thanks for spelling persulphate properly! Changing
chemical name spellings for the sake of phonetics leads to confusion. Also,
please try and dispose of spent chemicals responsibly.

-marc





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2003\06\18@014025 by Picdude

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On Tuesday 17 June 2003 18:40, Mike Hord scribbled:
> I'm etching boards these days in a 1 gal aquarium that came from K-Mart
> with an air pump and a diffuser.  Not a bad deal at $9!

I hunted down tall thin containers so I could keep the board on edge and not use gazillions of etchant.  I was looking for some acrylic magazine racks, but ended up with some cheap cereal containers from WalMart.


> A 25 W heater doesn't seem to be enough to heat the solution up
> too much.  I guess I may try a larger one, but it works well enough at
> room temp for me not to be too worried.

Really?  Wow.  So far I haven't got a heater, but when I start the process (exposure, etc), I fill the sink with hot water and put the etchant container in.  Makes a ver noticeable difference over room-temp.


> Incidentally, I'm using sodium persulphate for etching.  Does anyone know
> anything about its toxicity compared to Ferric chloride?  It seems more
> benign
> to me; right now I have it in a fume hood but would like to move it out.
> Is that a bad idea?  I won't do it if anyone has any negative input on that
> idea.

Not specifically Sodium Persulphate, but Ammonium Persulphate is bad, bad stuff.  Even though MG states "plastic" on the outside, you can't leave it in a plastic container long as it will eat thru the plastic.

Cheers,
-Neil.

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2003\06\18@014249 by Picdude

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On Tuesday 17 June 2003 18:30, Alex Kilpatrick scribbled:
> > > For agitation, can you just use an aquarium air pump?  Do you use a
> > > diffuser?
> >
> > IIRC, you are in Austin, right?  Petco on Great Hills Tr. has
> > a small aquarium
> > pump called a Profile 1000 (or something like that).  <$10
> > and works well for
> > me.  Very quiet too.  Not sure what you mean by diffuser, so
> > I guess that
> > answer is no :-)
>
> Yep, I'm in Austin (Round Rock).  Maybe we should get together and
> compare notes.

Sure.  Email me offline.  Wanna help me build a sprinkler controller? :-)


> I also do stuff with aquariums.  A diffuser (also called an airstone)
> breaks up air into millions of tiny bubbles.  It would probably help
> with etching, if I understand the process correctly.

Shouldn't be necessary -- the IMO (there's that acronym again!), the agitation keeps the "used" parts of the etchant away from the board (thereby "blocking" fresh etchant from reaching it) so that the copper always sees fresh etchant.  Standing it vertically also helps.

Cheers,
-Neil.

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2003\06\18@015141 by Stuart Meier

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> chemical name spellings for the sake of phonetics leads to confusion. Also,
> please try and dispose of spent chemicals responsibly.

OK Marc, I guess the question is, how should one dispose of sodium persulphate?
Stuart

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2003\06\18@032413 by William Chops Westfield

face picon face
>>  how should one dispose of sodium persulphate?

Sodium persulphate is used extensively for sanitizing swimming pools (to
oxidze excessive waste products) (at a rate of a pound or so per 10,000
gallons of pool water.)  It's more of a problem once it's got copper
disolved in it, since it's the copper that's more of an enviormental
poison... (you can still potentially throw it into the swimming pool.
Copper is a popular algicide, in much greater quantitites than you'll
get off a couple of PCBs...)  (do make sure it doesn't contain any of
those mercury-based catalysts I hear are sometimes used.)

That doesn't really answer the question, but we are talking about
relatively benign chemicals...

BillW

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2003\06\18@074450 by Olin Lathrop

face picon face
> I honestly don't know.  I used the autorouter in Eagle, and it does
> whatever it wants to do.  I can't figure out how to change the size of
> the traces.  Any help here?

Use net classes.


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2003\06\18@092723 by Mike Hord

picon face
>Copper is a popular algicide, in much greater quantitites than you'll
>get off a couple of PCBs...

There's my solution!  I'll give it to my friend with the algae overgrown
backyard
pond!  Or pour it into my algae overgrown fishtank!  ;-)

I've been wondering what to do with it...I've heard that pouring soda
(laundry
soap) in will cause the copper to precipitate out in a sludge to make it
easier
to handle.  Anyone have any comment on this?

Oh, and Marc, of course I checked the MSDS!  But like you said, they do tend
to be a bit paranoid.

Mike H.

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2003\06\18@153151 by Vern Jones

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Our local refuse company has a free hasmat unit open on Saturdays for
people with small quantities of hazardous wastes. All of my spent
chemicals go there...

Vern

Mike Hord wrote:
{Quote hidden}

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2003\06\18@165141 by William Chops Westfield

face picon face
There's my solution!  I'll give it to my friend with the algae overgrown
   backyard pond!  Or pour it into my algae overgrown fishtank!  ;-)

It's an algacide for swimming pools.  I think it'll kill fish...


   I've heard that pouring soda (laundry soap) in will cause the
   copper  to precipitate out in a sludge to make it easier to handle.

I've heard that too, for ferric chloride etchant as well.  Percipitate
out Copper carbonate and cast into concrete blocks...

Frankly, unless you're planning on making lots and lots of boards, you're
probably just fine dumping it down the toilet.  Applying hazmat disposal
concerns to individual's usage patterns is something that makes sense as
the number of people doing it starts to get large (like, you used to be
able to buy copper sulfate as "root killer", INTENDED to be dumped down
your drain a pound or two at a time.  Get a whole high-density urban
neighborhood doing that at the same time, and you have a problem.  One kid
throwing out the results from his chemistry set (or PCB etching) is another
matter.  Industrial usage levels are another matter.  Copper carbonate is
slightly soluble, so it's not obvious to me that it's less of a pollutant
than more soluble copper salts.  It's also a naturally occuring mineral.

GOOD MSDS data includes things like LD50 info, so you can figure out things
like "oh, this is actually a bit lesss poisonous than salt..."

billW

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2003\06\18@171229 by Mike Hord

picon face
I believe the MSDS specified the LD50 as 680 mg/kg, which is just
outrageous.

It also begs the question:  how did they force a bunch of lab rats to ingest
(or otherwise internalize) 65%+ of their body weight?  I think internalizing
that much of anything might kill you.  ;-)

Mike H.

>GOOD MSDS data includes things like LD50 info, so you can figure out things
>like "oh, this is actually a bit lesss poisonous than salt..."
>
>billW

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2003\06\18@172232 by David Minkler

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That looks like mg/kg not g/kg

Dave

Mike Hord wrote:
> I believe the MSDS specified the LD50 as 680 mg/kg, which is just
> outrageous.
>
> It also begs the question:  how did they force a bunch of lab rats to
> ingest
> (or otherwise internalize) 65%+ of their body weight?  I think
> internalizing
> that much of anything might kill you.  ;-)

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2003\06\18@173440 by David VanHorn
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At 02:21 PM 6/18/2003 -0700, David Minkler wrote:

>That looks like mg/kg not g/kg
>
>Dave
>
>Mike Hord wrote:
>>I believe the MSDS specified the LD50 as 680 mg/kg, which is just
>>outrageous.


EEK! I just dosed myself with over 1500mG/kG!!!

Gaaak.. AGGGGhh.. Gargle.. Oh. I guess it was g/kg

FWIW:  12 oz is 335000 mg.

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2003\06\18@185715 by Marc Nicholas

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On 18/6/03 17:09, "Mike Hord" <gaidinmdspamspam_OUTHOTMAIL.COM> wrote:

> I believe the MSDS specified the LD50 as 680 mg/kg, which is just
> outrageous.
>
> It also begs the question:  how did they force a bunch of lab rats to ingest
> (or otherwise internalize) 65%+ of their body weight?  I think internalizing
> that much of anything might kill you.  ;-)

LD50s are not necessarily completely linear between species.

As for getting rats to ingest that much, you really, really don't want an
answer to that question.


-marc

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2003\06\18@235811 by Bob Ammerman

picon face
You are off by a factor of 1000. It is mg/kg, not g/kg or mg/g.

Bob Ammerman
RAm Systems

----- Original Message -----
From: "Mike Hord" <@spam@gaidinmdKILLspamspamHOTMAIL.COM>
To: <KILLspamPICLISTKILLspamspamMITVMA.MIT.EDU>
Sent: Wednesday, June 18, 2003 5:09 PM
Subject: Re: [EE]: First PCB!


> I believe the MSDS specified the LD50 as 680 mg/kg, which is just
> outrageous.
>
> It also begs the question:  how did they force a bunch of lab rats to
ingest
> (or otherwise internalize) 65%+ of their body weight?  I think
internalizing
> that much of anything might kill you.  ;-)
>
> Mike H.
>
> >GOOD MSDS data includes things like LD50 info, so you can figure out
things
{Quote hidden}

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2003\06\19@091329 by Mike Hord

picon face
I'm just a little slow today.

Red faced.

Mike H.

>From: David Minkler <RemoveMEMinkTakeThisOuTspamLUXTRON.COM>
>That looks like mg/kg not g/kg

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2003\06\19@110231 by Sean H. Breheny

face picon face
I was trying to figure out what LD50 was so I did a web search. Not only
did I find out what it meant, but I also found this interesting MSDS. This
is one you DON'T want to have to deal with!

http://www.ilpi.com/msds/vx.html

Sean

At 11:53 PM 6/18/2003 -0400, you wrote:
>You are off by a factor of 1000. It is mg/kg, not g/kg or mg/g.
>
>Bob Ammerman
>RAm Systems
>
>{Original Message removed}

2003\06\26@041158 by Charles Craft

picon face
Off in the bushes but here's an article on the MSDS for H2O:

http://www.loganact.com/tips/royko.htm


--{Original Message removed}

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