Homebrew PCBs

The other day I posted about a baffle I was trying to make.  My goal 
was to get good agitation with good dispersion of bubbles.  Someone 
said I had too big of holes, which weren't that way when I started.

Anyway, based on that comment I realized you can only get so much 
power (Air) out of a tiny fish tank pump. So, like all "real men" 
do, I opted for more power! MUCH MORE POWER!

I connected my big shop air compressor to the new baffle I made up.  
I turned down the regulator till I could barely feel air comming out 
of the air gun.  Then I held the baffle hose to the air gun and like 
magic I had good bubbles and lots of them - everywhere.

Knowing that I will forget to turn down the regulator when etching a 
board at some point, I will wait until I can hook up another 
regulator for attachement to the etching tank.  That way, I should 
be able to reduce the risk of having the whole tank of ferric 
chloride sprayed about the shop.

It's still very dangerous in my opinion, but rather than buying 
another fish tank pump, this is the next cheapest solution. 

The point of this post is, poor bubble volume and dispersion may not 
be the problem of the baffle (Hose, stones, etc.), but rather not 
enough volume of air going into the tank.

I suspect this will even out the etching and etch a heck of a lot 
faster than before!

Chris

--- In Homebrew_PCBs@yahoogroups.com, "lcdpublishing"
<lcdpublishing@...> wrote:
>
> The other day I posted about a baffle I was trying to make.  My goal 
> was to get good agitation with good dispersion of bubbles.  Someone 
> said I had too big of holes, which weren't that way when I started.
> 
> Anyway, based on that comment I realized you can only get so much 
> power (Air) out of a tiny fish tank pump. So, like all "real men" 
> do, I opted for more power! MUCH MORE POWER!
> 
> I connected my big shop air compressor to the new baffle I made up.  
> I turned down the regulator till I could barely feel air comming out 
> of the air gun.  Then I held the baffle hose to the air gun and like 
> magic I had good bubbles and lots of them - everywhere.
> 
> Knowing that I will forget to turn down the regulator when etching a 
> board at some point, I will wait until I can hook up another 
> regulator for attachement to the etching tank.  That way, I should 
> be able to reduce the risk of having the whole tank of ferric 
> chloride sprayed about the shop.
> 
> It's still very dangerous in my opinion, but rather than buying 
> another fish tank pump, this is the next cheapest solution. 
> 
> The point of this post is, poor bubble volume and dispersion may not 
> be the problem of the baffle (Hose, stones, etc.), but rather not 
> enough volume of air going into the tank.
> 
> I suspect this will even out the etching and etch a heck of a lot 
> faster than before!
> 
> Chris


My solution to this was to use two of the larger fish tank pumps that
have two air outputs, glue all four pairs of tubing into a brass or
plastic part that had a screw type pipe on one end big enough to fit
all four tubes in (make sure you get the glue /between/ the tubes as
well) and the other end a connector to attach another tube of the same
width. I half expected the combined pressure to simply make the tubes
pop off of the pumps, but it worked, and gave enough pressure for a
good bubble stream, but I always had problems with uneven etching,
even after getting what I thought was even bubbling, so I finally gave
up on it entirely. Better than worrying about making an etchant
fountain, really...

I first started out using an air brush pump but I didn't use it very
long as I didn't want to ruin it.

> -----Message d'origine-----
> De : Homebrew_PCBs@yahoogroups.com 
> [mailto:Homebrew_PCBs@yahoogroups.com] De la part de lcdpublishing
> Envoyé : juillet 12 2006 17:49
> À : Homebrew_PCBs@yahoogroups.com
> Objet : [Homebrew_PCBs] Super bubbler - got it working now!
> 
> 
... So, like all "real men" do, I opted for more power! MUCH MORE POWER!
...
> 
> Chris


You've come to the same conclusion I did several months ago, the fishtank
pump just doesn't cut it.  I connected my shop air compressor to a drilled
PVC tube I had running down the bottom of the etching tank.  I kept on
adding rows of holes until I got the desired 'coverage'.  I used a ball
valve with a nice red handle to control the air flow.

Like you, I knew that one accidental tap on that handle and I'd have a
disaster on my hands.  Don't forget, that bubbling action at the surface
creates a very fine ferric chloride mist.  Just 'cause you don't see it
doesn't mean it's not there, and I didn't have adequate ventilation for a
permanent installation.

I sure did get awesome bubbling action going though, like boiling water, but
not as crazy.  One day when I'm going to have a decent shop space, I will
make another etching tank.  But for the time being, all my equipment fits in
a large plastic bin, way up high on the top shelf (with the acid stored on
the bottom shelf of a cabinet out of harms way).

Now add a section of metal pipe after the air compressor, place a heat
source alongside that pipe and you've added temperature control to the
etching.

Robert
:)

>You've come to the same conclusion I did several months ago, the 
>fishtank pump just doesn't cut it. 

Well it certainly cuts it here provided you're only etching one to two 
boards at a time and the good part is that the tank, heater and 
aquarium pump only cost me $29.00. The size of the tank and the size 
of the holes (hence the size of the bubbles) is the key to the design. 

http://www.pbase.com/eldata/image/62352753/original

--- In Homebrew_PCBs@yahoogroups.com, Robert Hedan <robert.hedan@...> 
wrote:
>

So what kind of etch times to you get with your super bubbler? We use
a warming plate and an agitator that simply rocks the solution back
and forth. No bubbles. We get times in the 5 to 10 minute range
depending on the cleanness of the soultion.


Regards
-- 
Royce

------
The real problem is not whether machines think but whether men do.
B. F. Skinner

Hi ROyce.

Don't know yet.  I am still trying to find a regulator that I can use 
for this and don't have time for the "Search" yet.  I am hoping this 
weekend I will get some time to finish it up.

I did notice though an interesting thing (I am only using water at the 
moment).  There does seem to be a bias as to how the water flows and 
circulates in the tank.

For example, if there are more bubbles on the left side, the flow of 
water is in a circular, clockwise rotation.  This draws the bubbles 
from the right bottom and pulls them towards the left side as they 
rise up.  What I am not sure of is if the bubbles actually do 
the "Scrubbing" or is the "Scubbing" simply a function of the flow of 
etchant.

If the bubbles are doing something, I will be getting some uneven 
etching. I am going to try and modify the baffle a bit so that the 
flow is back to front as opposed to left to right.  I believe this 
would even out the etching.




--- In Homebrew_PCBs@yahoogroups.com, "Royce Pipkins" 
<royce.pipkins@...> wrote:

>
> So what kind of etch times to you get with your super bubbler? We use
> a warming plate and an agitator that simply rocks the solution back
> and forth. No bubbles. We get times in the 5 to 10 minute range
> depending on the cleanness of the soultion.
> 
> 
> Regards
> -- 
> Royce
> 
> ------
> The real problem is not whether machines think but whether men do.
> B. F. Skinner
>

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

From: "Royce Pipkins" <royce.pipkins@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Friday, July 14, 2006 11:54 AM
Subject: [Homebrew_PCBs] Re: Super bubbler - got it working now!


> So what kind of etch times to you get with your super bubbler? We use
> a warming plate and an agitator that simply rocks the solution back
> and forth. No bubbles. We get times in the 5 to 10 minute range
> depending on the cleanness of the soultion.

That's about how long it takes for me with manual agitation and warm 
etchant.

Leon

On Fri, 14 Jul 2006 16:05:03 +0200, lcdpublishing  
<lcdpublishing@...m> wrote:

> Hi ROyce.
> Don't know yet.  I am still trying to find a regulator that I can use
> for this and don't have time for the "Search" yet.  I am hoping this
> weekend I will get some time to finish it up.
> I did notice though an interesting thing (I am only using water at the
> moment).  There does seem to be a bias as to how the water flows and
> circulates in the tank.
> For example, if there are more bubbles on the left side, the flow of
> water is in a circular, clockwise rotation.  This draws the bubbles
> from the right bottom and pulls them towards the left side as they
> rise up.  What I am not sure of is if the bubbles actually do
> the "Scrubbing" or is the "Scubbing" simply a function of the flow of
> etchant.
> If the bubbles are doing something, I will be getting some uneven
> etching. I am going to try and modify the baffle a bit so that the
> flow is back to front as opposed to left to right.  I believe this
> would even out the etching.


I see the same here.
When i switch the pump on the bubbler will fill from the left, so will  
bubble there first, causing a circuiar current to start.
This is sustained unless i stop the pump, wait for the current to slow,  
and start the pump again (now with a bubbler already filled with air).

There's still such currents then, but not as extreme.

I guess nothing can be done, it will be impossible to get it totally even.

ST

An I guess a lot of that mist can be mitigated by  having something 
floating on the surface of the etchant so as the tiny bubbles collect
and form larger bubbles prior to breaking the surface. Most of the mist 
is generated by the surface  tention of the liquid breaking at the 
bubble pops causing tiny droplets of liquid. Therefore if the bubbles 
are collect into larger bubbles before breaking the surface then there 
is less 'surface-tention breaking events' thus less mist.

Cheers,
David




Robert Hedan wrote:

>>-----Message d'origine-----
>>De : Homebrew_PCBs@yahoogroups.com 
>>[mailto:Homebrew_PCBs@yahoogroups.com] De la part de lcdpublishing
>>Envoy\ufffd : juillet 12 2006 17:49
>>\ufffd : Homebrew_PCBs@yahoogroups.com
>>Objet : [Homebrew_PCBs] Super bubbler - got it working now!
>>
>>
>>    
>>
>... So, like all "real men" do, I opted for more power! MUCH MORE POWER!
>...
>  
>
>>Chris
>>    
>>
>
>
>You've come to the same conclusion I did several months ago, the fishtank
>pump just doesn't cut it.  I connected my shop air compressor to a drilled
>PVC tube I had running down the bottom of the etching tank.  I kept on
>adding rows of holes until I got the desired 'coverage'.  I used a ball
>valve with a nice red handle to control the air flow.
>
>Like you, I knew that one accidental tap on that handle and I'd have a
>disaster on my hands.  Don't forget, that bubbling action at the surface
>creates a very fine ferric chloride mist.  Just 'cause you don't see it
>doesn't mean it's not there, and I didn't have adequate ventilation for a
>permanent installation.
>
>I sure did get awesome bubbling action going though, like boiling water, but
>not as crazy.  One day when I'm going to have a decent shop space, I will
>make another etching tank.  But for the time being, all my equipment fits in
>a large plastic bin, way up high on the top shelf (with the acid stored on
>the bottom shelf of a cabinet out of harms way).
>
>Now add a section of metal pipe after the air compressor, place a heat
>source alongside that pipe and you've added temperature control to the
>etching.
>
>Robert
>:)
>
>
>
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBs
>
>If Files or Photos are running short of space, post them here:
>http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
>Yahoo! Groups Links
>
>
>
> 
>
>
>
> 
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>Date: Wed, 12 Jul 2006 19:02:15 -0400
>Subject: RE : [Homebrew_PCBs] Super bubbler - got it working now!
>Reply-To: Homebrew_PCBs@yahoogroups.com
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>  
>
>>-----Message d'origine-----
>>De : Homebrew_PCBs@yahoogroups.com 
>>[mailto:Homebrew_PCBs@yahoogroups.com] De la part de lcdpublishing
>>Envoy\ufffd : juillet 12 2006 17:49
>>\ufffd : Homebrew_PCBs@yahoogroups.com
>>Objet : [Homebrew_PCBs] Super bubbler - got it working now!
>>
>>
>>    
>>
>... So, like all "real men" do, I opted for more power! MUCH MORE POWER!
>...
>  
>
>>Chris
>>    
>>
>
>
>You've come to the same conclusion I did several months ago, the fishtank
>pump just doesn't cut it.  I connected my shop air compressor to a drilled
>PVC tube I had running down the bottom of the etching tank.  I kept on
>adding rows of holes until I got the desired 'coverage'.  I used a ball
>valve with a nice red handle to control the air flow.
>
>Like you, I knew that one accidental tap on that handle and I'd have a
>disaster on my hands.  Don't forget, that bubbling action at the surface
>creates a very fine ferric chloride mist.  Just 'cause you don't see it
>doesn't mean it's not there, and I didn't have adequate ventilation for a
>permanent installation.
>
>I sure did get awesome bubbling action going though, like boiling water, but
>not as crazy.  One day when I'm going to have a decent shop space, I will
>make another etching tank.  But for the time being, all my equipment fits in
>a large plastic bin, way up high on the top shelf (with the acid stored on
>the bottom 
>  
>  
> -0-0-0- 
>  
>

On Sat, 15 Jul 2006 00:27:38 +0200, David Cureton <yahoo@...>  
wrote:

> An I guess a lot of that mist can be mitigated by  having something
> floating on the surface of the etchant so as the tiny bubbles collect
> and form larger bubbles prior to breaking the surface. Most of the mist
> is generated by the surface  tention of the liquid breaking at the
> bubble pops causing tiny droplets of liquid. Therefore if the bubbles
> are collect into larger bubbles before breaking the surface then there
> is less 'surface-tention breaking events' thus less mist.
> Cheers,
> David


You mean like the styrofoam pellets thrown into septic tanks (hole in lid  
== outside loo) in africa to stop dangerous insects from breeding?

I'm not sure that would be so practical, but you are right, a lid makes a  
whole lot of difference. The mist seems to condense on the surfaces.

ST

> Don't know yet.  I am still trying to find a regulator that I can use
> for this and don't have time for the "Search" yet.

For what it is worth, don't forget that most compressors put out a  
fair amount of water and some oil with the air, you might want to put  
a filter in line as well as your regulator.

-----

George Lawrence Storm
Macintosh Applications Development
Edmonds (Seattle), Washington
E-mail: <keencoyote@...>



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