Homebrew PCBs

>    From: Stefan Trethan <stefan_trethan@...>
> Subject: Re: Re: How to cut circuit boards?
>
> On Tue, 23 Dec 2003 11:39:42 -0000, Mike Cowlishaw
> <mfcowli@...> wrote:
>
>> Mentioned before, I think, but another good way to cut PCBs is a
>> table-mounted jigsaw.  [snip]
>
> I'm not so sure if a jigsaw is safer.
> It may be harder to cut a finger off but with all the jerky up and
> down movement unexpected things can happen.
> (e.g. if you don't hold down the pcb properly)

Since I'm cutting the PCM into quite small pieces (around 25mm square) I
clamp the pcb to a relatively heavy chunk of wood -- this means the
vibration is minimized and it's a lot easier to control.  I would do the
same with a circular saw.

> But you are right, the blade did cut rather good, though i never got
> very straight ;-)
> I see you have some guiding there, very good idea i think.

Yes for straight cuts the fences that come with the table mount are very
helpful.   I've also done one circuit board with a curved edge (to fit in a
headlamp).  Jigsaw or similar is essential for that.

> What do you think about the bearings and the glass dust?
> i think the linear bearing on the piston (or tappet? what is the
> correct word here?) will not last too long?

Good question, though I'd hope Bosch have sealed that reasonably well (given
that they sell the table to let you mount the saw in that way).  Also I also
use dust extraction, so hopefully not too much dust gets near that
bearing...

Mike Cowlishaw

Hi!

I'm thinking about my etch tank.
Even if i make a vertical tank how can i make a airtight lid?
I want to keep the etchant in and prevent too much corrosion.

The lid shoud keep all gases in.
it should have a overpressure valve (because of decomposing H2O2, that is 
no problem).

Additionally it should prevent spattering.
(when the tiny bubbles (from the h2o2) burst there is etchant splattered 
out of the tank.)

The lid ideally should be constructed in a way ensuring any condensed (or 
accumulated from splattering) drops
building up will run down in the tank again, and not run off to the side 
when i take the lid off.

Now to the problem:

How can i ensure a airtight seal if i make the tank myself.
even if i use silicone to make something like a seal?
Would it work to bend the top of the tank outward to make something like a 
flange?
and on that a bead of silicone (nice flat) as a seal?
How to press the lid (with the pcb holder) against it?


The other idea: (horizontal etch tank)
Take a big tupperware container.
(the seals of these containers are tight enough for me i think.)
fill it a inch or so with etchant.
now suspend the pcb (somehow) in mid-etchant.
some holding mechainsm on the lid is needed again.


The whole jar can be mounted to a heavy wood plate, just to make it harder 
to knock it over
while removing the lid.


While etching the lid may only rest loosely on the cointainer, this would 
be enough to catch the splattes.
To store it away just press on the lid.

Two questions bother me to this idea:

a)is the lid really tight enough
b)is it a problem to etch horizontally (for uniformity?)
in tray etching the edges are faster, but it doesn't cause trouble.
i nudge the jar sometimes to mix the etchant.

I don't really like the idea of a bubbler but mechanic agitation is ok.
(it might be enough to slightly press on the lid of the tupperware 
container a few times
to make the etchant mix? assume the pcb is hold to the lid and acts as a 
stirring paddle)


Let me know what you think of the idea.


Stefan

----- Original Message ----- 

From: "Stefan Trethan" <stefan_trethan@...>
To: <homebrew_pcbs@yahoogroups.com>
Sent: Wednesday, December 24, 2003 12:26 PM
Subject: [Homebrew_PCBs] horiziontal / vertical etching, how to make a
sealing lid


> Hi!
>
> I'm thinking about my etch tank.
> Even if i make a vertical tank how can i make a airtight lid?
> I want to keep the etchant in and prevent too much corrosion.
>
> The lid shoud keep all gases in.
> it should have a overpressure valve (because of decomposing H2O2, that is
> no problem).
>
> Additionally it should prevent spattering.
> (when the tiny bubbles (from the h2o2) burst there is etchant splattered
> out of the tank.)

Some industrial cleaning tanks have plastic beads floating on the top of the
liquid. That might be all you need - they will prevent splattering and cut
down evaporation. You can just lower the PCB through the beads.

Leon
--
Leon Heller, G1HSM
Email: aqzf13@...
My low-cost Philips LPC210x ARM development system:
http://www.geocities.com/leon_heller/lpc2104.html

On Wed, 24 Dec 2003 12:40:09 -0000, Leon Heller <leon_heller@...> 
wrote:

>
> ----- Original Message ----- From: "Stefan Trethan" 
> <stefan_trethan@...>
> To: <homebrew_pcbs@yahoogroups.com>
> Sent: Wednesday, December 24, 2003 12:26 PM
> Subject: [Homebrew_PCBs] horiziontal / vertical etching, how to make a
> sealing lid
>
>
>> Hi!
>>
>> I'm thinking about my etch tank.
>> Even if i make a vertical tank how can i make a airtight lid?
>> I want to keep the etchant in and prevent too much corrosion.
>>
>> The lid shoud keep all gases in.
>> it should have a overpressure valve (because of decomposing H2O2, that 
>> is
>> no problem).
>>
>> Additionally it should prevent spattering.
>> (when the tiny bubbles (from the h2o2) burst there is etchant splattered
>> out of the tank.)
>
> Some industrial cleaning tanks have plastic beads floating on the top of 
> the
> liquid. That might be all you need - they will prevent splattering and 
> cut
> down evaporation. You can just lower the PCB through the beads.
>
> Leon
> --
> Leon Heller, G1HSM

Thank you for the information but i'm not very fond of the idea.
It isn't really preventing evaporation totally (i forgot a tray beside some 
drills and had to
brush and oil them afterwards - don't like that again.)
And i think there wil always be beads sticking to the pcb/holder and so 
on...
I would rather like to have this thing closed well.
(i now store the etchant in a glass bottle with a pinhole in the lid for 
releasing pressure.
it stands close to iron parts and no rust at all for years)

ST

--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan 
<stefan_trethan@g...> wrote:
> On Wed, 24 Dec 2003 12:40:09 -0000, Leon Heller <leon_heller@h...> 
> wrote:
>
GLADPACK from your kitchen is cheapo and it works! 

Bengt

On Wed, 24 Dec 2003 13:12:23 -0000, bsjoelund <tecnoconsult@...> 
wrote:


> GLADPACK from your kitchen is cheapo and it works!
>
> Bengt
>

I honestly don't know what you are talking of.
I assume another tupperware "clone"?

I just used tupperware to describe any plastic kitchen containers because 
anyone knows
what i mean.
It is no problem to get such containers, from tupperware or others, but the 
question is more if they are suitable. And how they are best used (making 
the holder into the lid, and how to make the holder).

thanks

ST

>
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
>
> Yahoo! Groups Links
>
> To visit your group on the web, go to:
> http://groups.yahoo.com/group/Homebrew_PCBs/
>
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>
> Your use of Yahoo! Groups is subject to:
> http://docs.yahoo.com/info/terms/
>
>
>

--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan 
<stefan_trethan@g...> wrote:
> On Wed, 24 Dec 2003 13:12:23 -0000, bsjoelund <tecnoconsult@t...> 
> wrote:
> 
> 
> > GLADPACK from your kitchen is cheapo and it works!
> >
> > Bengt
> >
> 
> I honestly don't know what you are talking of.
> I assume another tupperware "clone"?
>
Stefan,
It´s the thin (plastic?) foil you use in the kitchen.

Bengt

On Wed, 24 Dec 2003 13:31:25 -0000, bsjoelund <tecnoconsult@...> 
wrote:

> --- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan 
> <stefan_trethan@g...> wrote:
>> On Wed, 24 Dec 2003 13:12:23 -0000, bsjoelund <tecnoconsult@t...> wrote:
>>
>>
>> > GLADPACK from your kitchen is cheapo and it works!
>> >
>> > Bengt
>> >
>>
>> I honestly don't know what you are talking of.
>> I assume another tupperware "clone"?
>>
> Stefan,
> It�s the thin (plastic?) foil you use in the kitchen.
>
> Bengt
>
>

I see, and how does this help me with pcb etching?
do i cover the tray with it?

thanks

ST

Sealing lid?

I assume you are using vertical tank and want to protect the 
surroundings from splashes etc..

Yes you can use this foil as a protective lid
Also as a sealing lid when storing the etchant in tank.

Bengt

----- Original Message ----- 

From: "bsjoelund" <tecnoconsult@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Wednesday, December 24, 2003 1:31 PM
Subject: [Homebrew_PCBs] Re: horiziontal / vertical etching, how to make a
sealing lid


--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
<stefan_trethan@g...> wrote:
> On Wed, 24 Dec 2003 13:12:23 -0000, bsjoelund <tecnoconsult@t...>
> wrote:
>
>
> > GLADPACK from your kitchen is cheapo and it works!
> >
> > Bengt
> >
>
> I honestly don't know what you are talking of.
> I assume another tupperware "clone"?
>
Stefan,
It\ufffds the thin (plastic?) foil you use in the kitchen.

'Clingfilm'?

Leon
--
Leon Heller, G1HSM
Email: aqzf13@...
My low-cost Philips LPC210x ARM development system:
http://www.geocities.com/leon_heller/lpc2104.html

Hello Stefan,
 
I was able to achieve an air tight seal on my spray etcher using a
rubber strip that I purchased at an automobile parts store. The strip that
I used was the rubber weather proofing seal for a sun roof. It was
cheap and readily available. Alternatives to this include the rubber
seal for a refigerator or freezer or the weather proofing seal for an
automobile door. I used lexan for the top along with plastic hinges 
and plastic bolts. To attach the rubber seal, I used a marine adhesive.
 
Be advised that spray etchers atomize the etchant, so a good seal
is imperative.
 
Best regards
 
 
Marvin Dickens
Alpharetta, Georgia  USA


Stefan Trethan <stefan_trethan@...> wrote:
Hi!

I'm thinking about my etch tank.
Even if i make a vertical tank how can i make a airtight lid?
I want to keep the etchant in and prevent too much corrosion.

The lid shoud keep all gases in.
it should have a overpressure valve (because of decomposing H2O2, that is 
no problem).

Additionally it should prevent spattering.
(when the tiny bubbles (from the h2o2) burst there is etchant splattered 
out of the tank.)

The lid ideally should be constructed in a way ensuring any condensed (or 
accumulated from splattering) drops
building up will run down in the tank again, and not run off to the side 
when i take the lid off.

Now to the problem:

How can i ensure a airtight seal if i make the tank myself.
even if i use silicone to make something like a seal?
Would it work to bend the top of the tank outward to make something like a 
flange?
and on that a bead of silicone (nice flat) as a seal?
How to press the lid (with the pcb holder) against it?


The other idea: (horizontal etch tank)
Take a big tupperware container.
(the seals of these containers are tight enough for me i think.)
fill it a inch or so with etchant.
now suspend the pcb (somehow) in mid-etchant.
some holding mechainsm on the lid is needed again.


The whole jar can be mounted to a heavy wood plate, just to make it harder 
to knock it over
while removing the lid.


While etching the lid may only rest loosely on the cointainer, this would 
be enough to catch the splattes.
To store it away just press on the lid.

Two questions bother me to this idea:

a)is the lid really tight enough
b)is it a problem to etch horizontally (for uniformity?)
in tray etching the edges are faster, but it doesn't cause trouble.
i nudge the jar sometimes to mix the etchant.

I don't really like the idea of a bubbler but mechanic agitation is ok.
(it might be enough to slightly press on the lid of the tupperware 
container a few times
to make the etchant mix? assume the pcb is hold to the lid and acts as a 
stirring paddle)


Let me know what you think of the idea.


Stefan

Be sure to visit the group home and check for new Bookmarks and files:
http://groups.yahoo.com/group/Homebrew_PCBs 

Yahoo! Groups Links

To visit your group on the web, go to:
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To unsubscribe from this group, send an email to:
Homebrew_PCBs-unsubscribe@yahoogroups.com

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

---------------------------------
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[Non-text portions of this message have been removed]

On Wed, 24 Dec 2003 07:39:02 -0800 (PST), mpdickens <md30022@...> 
wrote:

> Hello Stefan,
> I was able to achieve an air tight seal on my spray etcher using a
> rubber strip that I purchased at an automobile parts store. The strip 
> that
> I used was the rubber weather proofing seal for a sun roof. It was
> cheap and readily available. Alternatives to this include the rubber
> seal for a refigerator or freezer or the weather proofing seal for an
> automobile door. I used lexan for the top along with plastic hinges and 
> plastic bolts. To attach the rubber seal, I used a marine adhesive.
> Be advised that spray etchers atomize the etchant, so a good seal
> is imperative.
> Best regards
>
> Marvin Dickens
> Alpharetta, Georgia  USA
>
>

Thanks, very good idea.

I abandoned the idea of a spray etcher because of that, and because i don't 
really need one.
i can wait a few minutes for the occassional pcb (and search together the 
components in the meanwhile).

But i still want a good seal. i don't have a spare room for this.
I don't want everything rusty.
the garage is usually overcrowded, and i don't want to go outside 
(especially now at these temperatures).

If i can seal the unit up to near air-tight (not pressure tight of course) 
i can keep it with my tools
and material. (the vapors would corrode not only iron, electronic parts, 
wires, all oxidizes terribly. - don't ask)


I like the idea of the horizontal etch.
If i choose a container with a clear lid (most are milky white) i can even 
see the progress without
opening. And from the top, which allows safe placing in a bigger "emergency 
container".
(like a big plastic box). I can then put another cover on the plastic box 
and have all safely stored away.
A vertical tank needs much more room (a higher box) and needs a good stand 
to prevent it toppling over.
In the same plastic box another container, with water in it should have 
space enough.
The procedure would be to lift the lid, put the pcb in while keeping the 
lid over the etchant tray (drops).
then put it in, etch, when ready lift again and rinse in the water 
container.

If there are any spilled drops they would be within the safety box, no 
mess.
i like the idea.

The thing i haven't planned yet is the pcb holder.
I will find some solution for sure..
it shouldn't obscure the view from the top (through the lid)
and it should be capable of holding very tiny pcbs.


I will keep you informed what i come up with.
I wouldn't fear the welding of a tank myself but if i can use a tupperware
container (with zero work involved and maybe cheaper (sheet plastic costs)) 
i will use that.

Stefan

--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
<stefan_trethan@g...> wrote:
> On Wed, 24 Dec 2003 13:12:23 -0000, bsjoelund <tecnoconsult@t...> 
> wrote:
> 
> 
> > GLADPACK from your kitchen is cheapo and it works!
> >
> > Bengt
> >
> 
> I honestly don't know what you are talking of.
> I assume another tupperware "clone"?

Yes, it is a very inexpensive tupperware clone made from very thin
plastic. Looks vacuum/blow molded. Not a long term thing, made to be
throwaways.

Steve Greenfield

My interest in a spray etcher was driven by two issues:
 
1.) The need to reduce under cutting. Reducing under cuts allows for thinner traces and less space between the traces.
 
2.) The ability to have consistant, reproducable results.
 
I am almost finished with my spray etcher. The hard part(s) are done and as soon as I've
got a few free nights, It will be complete. I've kept good notes that include a complete bill
of materials, a vendor list and instructions on how I did it. I've also been taking digital pictures throughout the entire build process. As soon as it is complete and working, I'm going to stick the whole thing up in the files section of this group. The total cost is less than $200.00 USD.
 
Best regards and Happy Holidays to all!
 
Marvin Dickens
Alpharetta, Georgia  USA



Thanks, very good idea.

I abandoned the idea of a spray etcher because of that, and because i don't 
really need one.
i can wait a few minutes for the occassional pcb (and search together the 
components in the meanwhile).


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

---------------------------------
Do you Yahoo!?
Yahoo! Photos - Get your photo on the big screen in Times Square

[Non-text portions of this message have been removed]

Stefan Trethan wrote:
> Hi!
> 
> I'm thinking about my etch tank.
> Even if i make a vertical tank how can i make a airtight lid?
> I want to keep the etchant in and prevent too much corrosion.
> 
> The lid shoud keep all gases in.
> it should have a overpressure valve (because of decomposing H2O2, that is 
> no problem).
> 
> Additionally it should prevent spattering.
> (when the tiny bubbles (from the h2o2) burst there is etchant splattered 
> out of the tank.)
> 
> The lid ideally should be constructed in a way ensuring any condensed (or 
> accumulated from splattering) drops
> building up will run down in the tank again, and not run off to the side 
> when i take the lid off.
> 
> Now to the problem:
> 
> How can i ensure a airtight seal if i make the tank myself.
> even if i use silicone to make something like a seal?
> Would it work to bend the top of the tank outward to make something like a 
> flange?
> and on that a bead of silicone (nice flat) as a seal?
> How to press the lid (with the pcb holder) against it?
> 
> 
> The other idea: (horizontal etch tank)
> Take a big tupperware container.
> (the seals of these containers are tight enough for me i think.)
> fill it a inch or so with etchant.
> now suspend the pcb (somehow) in mid-etchant.
> some holding mechainsm on the lid is needed again.
> 
> 
> The whole jar can be mounted to a heavy wood plate, just to make it harder 
> to knock it over
> while removing the lid.
> 
> 
> While etching the lid may only rest loosely on the cointainer, this would 
> be enough to catch the splattes.
> To store it away just press on the lid.
> 
> Two questions bother me to this idea:
> 
> a)is the lid really tight enough
> b)is it a problem to etch horizontally (for uniformity?)
> in tray etching the edges are faster, but it doesn't cause trouble.
> i nudge the jar sometimes to mix the etchant.
> 
> I don't really like the idea of a bubbler but mechanic agitation is ok.
> (it might be enough to slightly press on the lid of the tupperware 
> container a few times
> to make the etchant mix? assume the pcb is hold to the lid and acts as a 
> stirring paddle)
> 
> 
> Let me know what you think of the idea.
> 
> 
> Stefan



Can I ask why you decided that the lid must be air tight ?

The only possible reason I can see why you may want an air 
tight seal is if your planning on storing concentrated HCl 
and you don't want the any fumes to escape. If you are 
running HCl+CuCl2+H2O2 mix then the acid concentration 
should not be so high that any significant amounts of HCl 
gas escapes.
A 5% HCl solution is normally what they run at. Yes, HCl 
gets consumed during etching, but assuming you have 
relatively large volume of solution to the etching copper 
mass then your HCl additions should not be too frequent.

To make air tight seal then you must have a flanged tank and 
a flat rubber seal between the flange and lid. Then 
depending on the thickness of the plastic used the lid must 
be tightly clamped to the flange at every 20 mm to 60 mm 
with screws. This is how I sealed my spray etcher chamber, 
but as Marvin pointed out this is essential when spraying.

I think a partly sealed lid is all you need, just so that 
evaporation and  any air flow are restricted. There is a 
large range of rubber foam strips available for door seals. 
These will make a good seal for a etchant tank lid just from 
the weight of the lid on the foam.


The biggest problem you may have is spillage from the 
dripping etchant from the lid as its removed. All the 
supermarket plastic containers I've seen are not designed to
avoid dripping. I made my own tanks and did it in such a way 
to avoid this problem. The top of the tank has a flange 
which is right angled. This makes like a step. A cross 
section of the tank looks something like this;



|                          |
|                          |
-----                 -----
     |                 |
     |                 |
     |                 |
     |                 |
     |                 |
     |                 |
     |                 |
     |                 |
     |                 |
     |                 |
     |                 |
     |                 |
     |                 |
     |                 |
     -------------------




There is a lid which sits on the step. There is also a 
rubber foam strip between the horizontal part of the flange 
and the flat plastic lid (not shown). The lid normally never 
completely leaves the tank as it can sit on its edge inside 
the flange and rest vertically against something. This way 
the lid is out of the way while the PCB is being immersed in 
the tank.
How you make a tank with a flange like this may be difficult 
without plastic folding and welding. It might be possible 
with acrylic sheet (perspex, plexiglass)) and the solvent 
cement.

>
> Can I ask why you decided that the lid must be air tight ?
>
> The only possible reason I can see why you may want an air tight seal is 
> if your planning on storing concentrated HCl and you don't want the any 
> fumes to escape. If you are running HCl+CuCl2+H2O2 mix then the acid 
> concentration should not be so high that any significant amounts of HCl 
> gas escapes.
> A 5% HCl solution is normally what they run at. Yes, HCl gets consumed 
> during etching, but assuming you have relatively large volume of solution 
> to the etching copper mass then your HCl additions should not be too 
> frequent.

You didn't have to clean my drills did you? ;-)
NoNo, that must be sealed up! i forgot a open jar with my etchant (it is 
like you assumed)
on a desk with tooling on it. the drills developed nice red rust which i 
had to brush off
and oil them. (i dipped them in weak NaOh to neutralize any acid residue 
just to be sure)

>
> To make air tight seal then you must have a flanged tank and a flat 
> rubber seal between the flange and lid. Then depending on the thickness 
> of the plastic used the lid must be tightly clamped to the flange at 
> every 20 mm to 60 mm with screws. This is how I sealed my spray etcher 
> chamber, but as Marvin pointed out this is essential when spraying.
>
"airtight" not exactly. tupperware says their containers are "almost 
airtight".
that's very fine for me.
The bottle with the 1mm pin hole in the lid isn't causing rusting tools. 
(for years).


> I think a partly sealed lid is all you need, just so that evaporation and 
> any air flow are restricted. There is a large range of rubber foam strips 
> available for door seals. These will make a good seal for a etchant tank 
> lid just from the weight of the lid on the foam.
>

I think you are right.

> .... cropped (don't think the rest was bad - just because of the archive 
> storage space)


Thank you for your drawing and hints.
I thought of a similar design too.

But i am determined to give the horizontal etch a try.
I will use a tupperware container, and suspend the pcb holder off the lid.

I hope i can soften the lid with the heat gun and depress it in the center.
this would make any condensed drops run together there and drop down.
should be possible, what is tupperware made of? PP?


If it works it would be much less work than welding a complete tank.
(this would take at least a day).

I'm stillthinking about the pcb holder design.

Stefan