Homebrew PCBs

Hi,

want to raise the bubbler question once again,
I use a plastic hose with 6 holes in it, made by hot needle.

I have streaks on the pcb where the bubbles rise. what can i do about it?
What would give a better more random spread?


ST

Lots more smaller holes.  I've been making 0.002" holes with a hot wire.

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

From: "Stefan Trethan" <stefan_trethan@...>
To: <homebrew_pcbs@yahoogroups.com>
Sent: Monday, March 07, 2005 5:46 PM
Subject: [Homebrew_PCBs] bubbler - more even spread of bubbles


> 
> 
> Hi,
> 
> want to raise the bubbler question once again,
> I use a plastic hose with 6 holes in it, made by hot needle.
> 
> I have streaks on the pcb where the bubbles rise. what can i do about it?
> What would give a better more random spread?
> 
> 
> 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
> 
> 
> 
> 
> 
> 
> 
>

On Mon, 7 Mar 2005 18:38:59 -0500, Earl T. Hackett, Jr.  
<hacketet@...> wrote:

> Lots more smaller holes.  I've been making 0.002" holes with a hot wire.


that's 0.05mm!!!! what wire did you use? how did you do that?

Think and tinker says larger bubbles are desireable, they use a special  
hole pointed down 45 degree that allows a large bubble to assemble before  
breaking off.

I'm not sure what is best, all i know is i have a uneven etch and i'd like  
to change that.

st

In message <opsna8wwl0mg0lsf@...>
          "Stefan Trethan" <stefan_trethan@...> wrote:

> I'm not sure what is best, all i know is i have a uneven etch and i'd like  
> to change that.

I've been using a cheap fish tank air pump and a blue foam bubble hose. The
bubble hose has been bleached white by the FeCl and has a few "rust spots"
(probably from the Fe in the FeCl), but it still seems to work fine. Perfect,
even etching in my experience. A heater is also a useful addition.

Later.
-- 
Phil.                              | Acorn Risc PC600 Mk3, SA202, 64MB, 6GB,
philpem@...              | ViewFinder, 10BaseT Ethernet, 2-slice,
http://www.philpem.me.uk/          | 48xCD, ARCINv6c IDE, SCSI
... A)bort R)etry G)et a stick and kill it.

On Tue, 08 Mar 2005 11:42:03 GMT, Philip Pemberton <philpem@...>  
wrote:

>
> I've been using a cheap fish tank air pump and a blue foam bubble hose.  
> The
> bubble hose has been bleached white by the FeCl and has a few "rust  
> spots"
> (probably from the Fe in the FeCl), but it still seems to work fine.  
> Perfect,
> even etching in my experience. A heater is also a useful addition.
> Later.


I use a cheap fish tank air pump too, but i don't have a blue foam bubble  
hose or know where to get it.

A heater is no good for CuCl, but good for FeCl, i agree.


ST

Hi,

remember when i whined a wile ago that i have broken my nice hydrometer  
pipette (a huge eyedropper where the hydrometer swims inside and you  
simply suck etchant in with the rubber ball.)

Well, when looking how to get my bubbler going better i discovered a nice  
1.1 to 1.325 hydrometer, 0.025 resolution, meant for measuring car  
batteries. At the tools shop, for only 2eur or so, with pipette and rubber  
ball!

There's no easier or cheaper way to get your density measured. Ok quality  
(glass), accuracy unknown but could be tested against scale if required.  
Should be available in any car tools shop. There are also similar things  
made of plastic with a pivoting needle and a scale, not sure about their  
accuracy but the resolution is less so i chose the trusty hydrometer.

Oh well, the bubbler is still ???

ST

In our lab plating tanks we used 1" PVC pipe with two rows of 1/16" holed on 
1" or shorter centers at 45\ufffd up from the bottom.  These were big tanks 
(about 80 gal) and the boiling action was pretty impressive with 1 to 2" 
diameter bubbles.  In a small tank this level of sparging would send the 
etchant all over the room.  If the bubble is too small it just doesn't rise 
and doesn't move the etchant around.  You want as big a bubble as you can 
get while not splashing stuff all over the place and keeping the agitation 
uniform over the surface of the board.  My guess is that for most small 
tanks you want bubbles between 1/8 and 1/4" or 3 to 6 mm diameter.  You have 
to drive the whole sparger bar though.  Make sure you have the air capacity 
for that.  Also make sure the sparger is very close to level.  Otherwise 
once the first couple of holes open up, air pressure drops and you may not 
drive the etchant out and open up the other holes so you are really only 
sparging one end of the tank.

I don't think you have to go down to 0.002" - I was doing this to help 
develop a test method for monitoring the sterile barrier characteristics of 
medical packaging, but it is relatively easy to do.  I have an old Unimat 
drill press to which I attach the tweezers from a resistance soldering unit. 
I just put a piece of stiff wire of the size I want in the tweezers, press 
it against the plastic and turn on the power.  It heats quickly and melts 
through the plastic.  Leave it in too long and the hole gets a lot bigger. 
For these real small holes I've been using tungsten because it's about the 
only thing stiff enough.  If you go up to .005" there are plenty of metals 
that are stiff enough that they won't bend when you push (gently) on them.

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

From: "Stefan Trethan" <stefan_trethan@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Tuesday, March 08, 2005 3:37 AM
Subject: Re: [Homebrew_PCBs] bubbler - more even spread of bubbles


>
> On Mon, 7 Mar 2005 18:38:59 -0500, Earl T. Hackett, Jr.
> <hacketet@...> wrote:
>
>> Lots more smaller holes.  I've been making 0.002" holes with a hot wire.
>
>
> that's 0.05mm!!!! what wire did you use? how did you do that?
>
> Think and tinker says larger bubbles are desireable, they use a special
> hole pointed down 45 degree that allows a large bubble to assemble before
> breaking off.
>
> I'm not sure what is best, all i know is i have a uneven etch and i'd like
> to change that.
>

I have a 5 gal. tank and use Ferric Chloride  can etch upto 4 single 
sided 8" x 12" boards in it.  I have three rows of 1/2" CPVC pipe 
across the bottom with I think about 1/8" holes on each side about 
1" or so center to center.  I use a small air compressor to get 
enough air volume.  A standard fish tank pump worked OK when I had 
my smaller tank but had to go to the air compressor when I started 
using the 5 gal. tank.


Ben

I've have very bad luck with several of the fish tank bubblers and
CuCl (air stone is one product name).  They fell apart in the CuCl
after around 6-8 hrs exposure.

--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@g...> wrote:
> On Tue, 08 Mar 2005 11:42:03 GMT, Philip Pemberton <philpem@d...>  
> wrote:
> 
> >
> > I've been using a cheap fish tank air pump and a blue foam bubble
hose.  
> > The
> > bubble hose has been bleached white by the FeCl and has a few "rust  
> > spots"
> > (probably from the Fe in the FeCl), but it still seems to work fine.  
> > Perfect,
> > even etching in my experience. A heater is also a useful addition.
> > Later.
> 
> 
> I use a cheap fish tank air pump too, but i don't have a blue foam
bubble  

> hose or know where to get it.
> 
> A heater is no good for CuCl, but good for FeCl, i agree.
> 
> 
> ST

On Wed, 09 Mar 2005 17:22:39 -0000, Phil <phil1960us@...> wrote:

>
> I've have very bad luck with several of the fish tank bubblers and
> CuCl (air stone is one product name).  They fell apart in the CuCl
> after around 6-8 hrs exposure.


Ok, thanks for the warning.

ST

On Wed, 09 Mar 2005 17:22:39 -0000, Phil <phil1960us@...> wrote:

>
>
> I've have very bad luck with several of the fish tank bubblers and
> CuCl (air stone is one product name).  They fell apart in the CuCl
> after around 6-8 hrs exposure.
>

Phil, which material were these?
I got a round one with the pump that is a blue material, very much like a  
grinding stone in texture, very hard.
I wonder if there are any that hold up in CuCl...

ST

Phil wrote:
> 
> I've have very bad luck with several of the fish tank bubblers and
> CuCl (air stone is one product name).  They fell apart in the CuCl
> after around 6-8 hrs exposure.
> 

I've had the same experience. Nylon is the culprit. I've heard before 
that big bubbles produce more a agitation. This is where you need more 
air than conventional home fish tank air pump. I've looked around for 
such pumps and found some hydroponic stores sell large pumps, and then 
there are places that sell pumps for outdoor fish ponds and even home 
sewage treatment. There are high volume air pumps that are not too 
expensive. These cheaper high volume pumps are a bit louder and shorter 
life span, but that is unimportant for etching.

Adam

On Thu, 10 Mar 2005 08:08:45 +1100, Adam Seychell  
<a_seychell@...> wrote:

>
> I've had the same experience. Nylon is the culprit. I've heard before
> that big bubbles produce more a agitation. This is where you need more
> air than conventional home fish tank air pump. I've looked around for
> such pumps and found some hydroponic stores sell large pumps, and then
> there are places that sell pumps for outdoor fish ponds and even home
> sewage treatment. There are high volume air pumps that are not too
> expensive. These cheaper high volume pumps are a bit louder and shorter
> life span, but that is unimportant for etching.
> Adam


I just wrote a series of questions to ebay guys selling interesting  
bubblers, asking which material they are and to please describe it as best  
as they can if unsure.
As said the round one is no nylon, it seems like ceramic or something.
It looks just like the round grinding bit you get for drilling machines,  
with about 2cm diameter, and a seam in the middle from forming. It  
basically looks like blue quartz sand somehow magically held together.
If you'd glue in a shaft instead of the tube for the hose i'd have taken  
it as a grinding bit with no second thought.

I can throw that one in the CuCl just for fun to see if that sort of  
material holds up. I've already seen a bubbler that seems like that  
material but 25cm long.


I fear it was not a good idea to go for the cheapest and smallest air  
pump. I want to run it closed loop and i am a bit reluctant to spend much  
money for a pump which might have metal components in the air path which i  
can not use. I'd rather buy a second small pump and connect one each end  
of the stone.

Have you looked at think/tinker? they suggest drilling a larger hole, but  
not all the way through the tube-wall, to form a small space where the air  
collects before breaking free (which allows a small pump to make big  
bubbles).
In my small tank i can't fit a big tube with thick walls, but i think i  
could make the same effect by using electrical wiring tubing and a hot,  
blunt rod to make indentations, say 5mmdia and 5mm deep, and in the center  
drill a tiny hole.


Also, as it is now the airstream created huge eddy currents, rising in the  
middle of the tank and dropping at the outer sections. This current draws  
all air in to an extent where the air from the outermost nozzles is  
deflected to rise within the center half of the tank. Luckily most boards  
fit in that space but it might be a problem in the future.
I plan to make a wider tank when i have a better bubbler, which might  
solve that problem (or not).


ST

One I had was a blue tube say 2 cm diameter and 3-4 cm long. It felt
hard but brittle.  I thought it was some sort of foamed glass but when
it fell apart it was clearly some sort of plastic.  It turned white. 
I still have some bits of it floating in my etchant...

The other one was grey and some what like foam.  definitely plastic of
some sort.  It lasted only slightly longer.

Do you need bubbles or agitation?  These days I just let the end of
the air hose dangle in the etchant and the pressure causes it to go
back and forth giving me enough stirring so the etch is reasonably even.

Phil

--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@g...> wrote:
> On Wed, 09 Mar 2005 17:22:39 -0000, Phil <phil1960us@y...> wrote:
> 
> >
> >
> > I've have very bad luck with several of the fish tank bubblers and
> > CuCl (air stone is one product name).  They fell apart in the CuCl
> > after around 6-8 hrs exposure.
> >
> 
> Phil, which material were these?
> I got a round one with the pump that is a blue material, very much
like a  

> grinding stone in texture, very hard.
> I wonder if there are any that hold up in CuCl...
> 
> ST

On Wed, 09 Mar 2005 21:37:25 -0000, Phil <phil1960us@...> wrote:

>
> One I had was a blue tube say 2 cm diameter and 3-4 cm long. It felt
> hard but brittle.  I thought it was some sort of foamed glass but when
> it fell apart it was clearly some sort of plastic.  It turned white.
> I still have some bits of it floating in my etchant...
> The other one was grey and some what like foam.  definitely plastic of
> some sort.  It lasted only slightly longer.
> Do you need bubbles or agitation?  These days I just let the end of
> the air hose dangle in the etchant and the pressure causes it to go
> back and forth giving me enough stirring so the etch is reasonably even.
> Phil


Damn, and thank you for that post.
I almost bought one of the hard/brittle variety just now.
(two of 3 ebay sellers have relpied within 5 minutes, one is as we talk  
the hard and brittle variety and the other doesn't know the material, but  
it is a flexible porous hose so plastic.)

I really thought the hard/brittle type would work and i'm done with it....
Back to the drawing board then.

I want the air to mix the etchant, but also to help agitate the etchant  
right at the board, now i see much faster etching in the streaks where the  
bubbles rise.


ST

I'm thinking of going to a mechanical agitator to move the board up/dn
but have no idea if it will work well.  I figure something around 100
hz to start with.

--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@g...> wrote:
> On Wed, 09 Mar 2005 21:37:25 -0000, Phil <phil1960us@y...> wrote:
> 
> >
> > One I had was a blue tube say 2 cm diameter and 3-4 cm long. It felt
> > hard but brittle.  I thought it was some sort of foamed glass but when
> > it fell apart it was clearly some sort of plastic.  It turned white.
> > I still have some bits of it floating in my etchant...
> > The other one was grey and some what like foam.  definitely plastic of
> > some sort.  It lasted only slightly longer.
> > Do you need bubbles or agitation?  These days I just let the end of
> > the air hose dangle in the etchant and the pressure causes it to go
> > back and forth giving me enough stirring so the etch is reasonably
even.
> > Phil
> 
> 
> Damn, and thank you for that post.
> I almost bought one of the hard/brittle variety just now.
> (two of 3 ebay sellers have relpied within 5 minutes, one is as we
talk  
> the hard and brittle variety and the other doesn't know the
material, but  
> it is a flexible porous hose so plastic.)
> 
> I really thought the hard/brittle type would work and i'm done with
it....
> Back to the drawing board then.
> 
> I want the air to mix the etchant, but also to help agitate the
etchant  
> right at the board, now i see much faster etching in the streaks
where the  

> bubbles rise.
> 
> 
> ST

Phil writes:

> I'm thinking of going to a mechanical agitator to move the board up/dn
> but have no idea if it will work well.  I figure something around 100
> hz to start with.

I'm a newbie to the group.  The last time I etched a board was perhaps
20 years ago masked with an etch-resistant pen.  I've been mostly a
software guy since then, but I'm getting back into hardware as a
hobby.  So, my appologies in advance if this is old news...

Here's a thought on agitation:  Find a gear motor that runs somewhere
arround 30 RPM.  Mount a disc perhaps 2-3 inches in diameter with an
offset center to the motor.  Mount underneath one edge of the tray.
Might something like this do the trick?

-p.

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

From: "Phil" <phil1960us@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Thursday, March 10, 2005 6:24 PM
Subject: [Homebrew_PCBs] Re: bubbler - more even spread of bubbles


>
>
> I'm thinking of going to a mechanical agitator to move the board up/dn
> but have no idea if it will work well.  I figure something around 100
> hz to start with.

One manufacturer of etching equipment uses a foam generator with FeCl3. I 
think I saw one of their tanks in the Farnell catalogue.

Leon

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

From: "Peter Johansson" <peter@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Thursday, March 10, 2005 7:22 PM
Subject: Re: [Homebrew_PCBs] Re: bubbler - more even spread of bubbles


>
>
> Phil writes:
>
>> I'm thinking of going to a mechanical agitator to move the board up/dn
>> but have no idea if it will work well.  I figure something around 100
>> hz to start with.
>
> I'm a newbie to the group.  The last time I etched a board was perhaps
> 20 years ago masked with an etch-resistant pen.  I've been mostly a
> software guy since then, but I'm getting back into hardware as a
> hobby.  So, my appologies in advance if this is old news...
>
> Here's a thought on agitation:  Find a gear motor that runs somewhere
> arround 30 RPM.  Mount a disc perhaps 2-3 inches in diameter with an
> offset center to the motor.  Mount underneath one edge of the tray.
> Might something like this do the trick?

Something like that was in the ARRL Handbook a few years ago. A heat lamp 
mounted above the etchant container kept the solution hot.

Leon

In article <20050310192228.GB2891@...>,
   Peter Johansson <peter@...> wrote:
> Here's a thought on agitation:  Find a gear motor that runs somewhere
> arround 30 RPM.  Mount a disc perhaps 2-3 inches in diameter with an
> offset center to the motor.  Mount underneath one edge of the tray.
> Might something like this do the trick?

How about sitting the tray on the cone edges of an old loudspeaker - say
about an 8". With a tone generator and an amplifier you could experiment
with different frequencies to see which produced the desired effect -
ultrasonic?

Or you could attach a pager motor to the outside of the etching tank.

http://www.pagermotors.com/index_files/English/Parts.htm

Ed Okerson

>      In article ,
>     Peter Johansson  wrote:
>  > Here's a thought on agitation:  Find a gear motor that runs somewhere
>  > arround 30 RPM.  Mount a disc perhaps 2-3 inches in diameter with an
>  > offset center to the motor.  Mount underneath one edge of the tray.
>  > Might something like this do the trick?
>
>  How about sitting the tray on the cone edges of an old loudspeaker - say
>  about an 8". With a tone generator and an amplifier you could
> experiment
>  with different frequencies to see which produced the desired effect -
>  ultrasonic?
>
>
>
>   Be sure to visit the group home and check for new Bookmarks and files:
>  http://groups.yahoo.com/group/Homebrew_PCBs
>
>
>       Yahoo! Groups Sponsor     ADVERTISEMENT
>
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On Thu, 10 Mar 2005 18:24:46 -0000, Phil <phil1960us@...> wrote:

>
> I'm thinking of going to a mechanical agitator to move the board up/dn
> but have no idea if it will work well.  I figure something around 100
> hz to start with.


tried it, it works but bubbler works better and no danger of board  
slipping out of holder.

ST

On Thu, 10 Mar 2005 22:47:31 +0100, lists  
<stuart.winsor.lists@...> wrote:

>
> How about sitting the tray on the cone edges of an old loudspeaker - say
> about an 8". With a tone generator and an amplifier you could experiment
> with different frequencies to see which produced the desired effect -
> ultrasonic?


I'm curious about ultrasonic myself, but nobody having a ultrasonic  
cleaner has agreed to put in a plastic bag filled with etchant and board  
and try. Couldn't even find someone agreeing to see if toner "resist"  
survives ultrasonic in water.

As for the other motor/tray suggestions, i've graduated from tray to tank  
some time back, and no wish to go back.
thanks anyway.


ST

(P.S.: After one day in etchant (small jar don't want to contaminate tank)  
the round bubbler is still ok)

The objective in any etching system is to replace the spent etchant at the 
surface of the board with fresh.  The speed of the etchant moving doesn't 
contribute to the etch rate other than to bring fresh etchant to the 
surface.  Friction between the etchant and the board surface makes this 
quite difficult.  This is why spray etching is the best - if you have enough 
of the right spray nozzles to produce a uniform spray pattern.  In a spray 
etch 1 oz copper foil will etch in a little over a minute.  If you look 
inside you'll see why.  The etchant is rushing over the board surface at 
about a thousand feet per minute.  In a bubbler system your lucky to get to 
50 feet per minute.  In an ultrasonic cleaner there is almost no movement so 
all the etchant does is sit there and shake.

I remember trying reverse electroplating as an etch method in an attempt to 
minimize waste treatment and equipment costs.  The circuit board was used as 
the anode and a sheet of stainless steel used to collect the copper.  It 
didn't work very well and was way too slow for production.  A lot of things 
have been tried, but the critical factor is always getting fresh etchant to 
the board surface.

On Fri, 11 Mar 2005 11:33:42 -0500, Earl T. Hackett, Jr.  
<hacketet@...> wrote:

>
> The objective in any etching system is to replace the spent etchant at  
> the
> surface of the board with fresh.  The speed of the etchant moving doesn't
> contribute to the etch rate other than to bring fresh etchant to the
> surface.  Friction between the etchant and the board surface makes this
> quite difficult.  This is why spray etching is the best - if you have  
> enough
> of the right spray nozzles to produce a uniform spray pattern.  In a  
> spray
> etch 1 oz copper foil will etch in a little over a minute.  If you look
> inside you'll see why.  The etchant is rushing over the board surface at
> about a thousand feet per minute.  In a bubbler system your lucky to get  
> to
> 50 feet per minute.  In an ultrasonic cleaner there is almost no  
> movement so
> all the etchant does is sit there and shake.


so that means what? big bubbles are better? spray etchers are awfully  
complicated to build and i have yet to hear of someone building one that  
works. Has anyone tried toner transfer with a sprayer? and what about CuCl?

ST