Homebrew PCBs

I search messages arhive on this subject and no concludent result. 
Opinions are very diferent: 1mm holes at 2,5 mm space-large bubbles or 
aquarium tipe aerator whith millions of little bubles.

I have a 200x200x30mm etching tank and I use FeCl. I made a heater 
from a 4mm PVC hose aranged on entire surface of tank. Something like 
this
 __________
 __________|
|__________ 
 __________|
|__________

The hose is conected to my sower hose, so the temperature is fully 
ajustable. A simple and safe device...
I allso have a very powerfull air pump so I can generate a lot of air.


Adrian

Larger bubbles are supposedly required to get good scrubbing action at the  
surface of the PCB.
However, with my small air pump i could not produce enough large bubbles  
in enough places, so they would rise from a few spots only and create  
"streaks" on the board that etch much faster.

Since i have the bubbler hose with many tiny bubbles the etching is more  
even. Still not ideal 'cause large areas take longer - which could be  
improved with more scrubbing action. Also, the smaller the bubbles the  
slower they rise, and small bubbles will move around a lot more and not  
just go straight up in streaks.

With your large air pump i suppose big bubbles are good, if you can create  
them in enough places so no streaks are visible.
I reckon a moving air source would make things much easier to get even,  
maybe a tube with a spiral pattern of many holes, that is rotated slowly  
by the air in some way would be possible.

ST

On Thu, 22 Dec 2005 06:39:43 +0100, adicont2 <adicont2@...> wrote:

> I search messages arhive on this subject and no concludent result.
>
> Opinions are very diferent: 1mm holes at 2,5 mm space-large bubbles or
>
> aquarium tipe aerator whith millions of little bubles.
>
>
> I have a 200x200x30mm etching tank and I use FeCl. I made a heater
>
> from a 4mm PVC hose aranged on entire surface of tank. Something like
>
> this
>
>  __________
>
>  __________|
>
> |__________
>
>  __________|
>
> |__________
>
>
> The hose is conected to my sower hose, so the temperature is fully
>
> ajustable. A simple and safe device...
>
> I allso have a very powerfull air pump so I can generate a lot of air.
>
>
>
> Adrian
>
>

Bubbles must cover entire surface of the board. So I must made many 
large holes in the tube, something like 1mm diameter whith spaces 
about 10mm or less.

You are wright about rates of rise. I made some experiments and large 
bubbles rise verry fast and create a huge disturbance in tank. I'm 
worry about this. Fast rise means faster etch in bottom area of the 
board.

I think about a system to slowly rotate the board. A tiny motor...
Or orizontaly vibrating it... 

Adrian


--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan" 
<stefan_trethan@g...> wrote:
>
> Larger bubbles are supposedly required to get good scrubbing action 
at the  
> surface of the PCB.
> However, with my small air pump i could not produce enough large 
bubbles  
> in enough places, so they would rise from a few spots only and 
create  
> "streaks" on the board that etch much faster.
> 
> Since i have the bubbler hose with many tiny bubbles the etching is 
more  
> even. Still not ideal 'cause large areas take longer - which could 
be  
> improved with more scrubbing action. Also, the smaller the bubbles 
the  
> slower they rise, and small bubbles will move around a lot more and 
not  
> just go straight up in streaks.
> 
> With your large air pump i suppose big bubbles are good, if you can 
create  
> them in enough places so no streaks are visible.
> I reckon a moving air source would make things much easier to get 
even,  
> maybe a tube with a spiral pattern of many holes, that is rotated 
slowly  
> by the air in some way would be possible.
> 
> ST
> 
> On Thu, 22 Dec 2005 06:39:43 +0100, adicont2 <adicont2@y...> wrote:
> 
> > I search messages arhive on this subject and no concludent result.
> >
> > Opinions are very diferent: 1mm holes at 2,5 mm space-large 
bubbles or
> >
> > aquarium tipe aerator whith millions of little bubles.
> >
> >
> > I have a 200x200x30mm etching tank and I use FeCl. I made a heater
> >
> > from a 4mm PVC hose aranged on entire surface of tank. Something 
like
> >
> > this
> >
> >  __________
> >
> >  __________|
> >
> > |__________
> >
> >  __________|
> >
> > |__________
> >
> >
> > The hose is conected to my sower hose, so the temperature is fully
> >
> > ajustable. A simple and safe device...
> >
> > I allso have a very powerfull air pump so I can generate a lot of 
air.

> >
> >
> >
> > Adrian
> >
> >
>

I'm also using two "small bubble" makers on a dual outlet pump, but 
haven't had a chance to get much tank use yet. They're the kind with 
the "fuzzy" looking textured surface. They did put off a nice strong 
mist of bubble fizz, which was spread evenly across a vertically 
hanging double sided board, so I think they'll do OK. It was strong 
enough that if they were too close to the surface, it would produce an 
airborne mist (eventually I'll mount them to the base).

I looked at a standard tube with holes first, but chose these. I 
wonder if you could just drill up a tube for it. I thought about 
making a plexi rectangle with some type of standoffs to create a 
vented chamber in the bottom of the tank, and gluing my tubes through 
the tank's sides near the bottom, but figured it might be a hassle 
while filling the tank and waiting for the etchant to fill the chamber 
(or having the air try to lift it out). 

The bubblers seem like a good area for DIY. With economy heaters and 
pumps, they were almost as expensive as some of the important stuff.

-George

Stefan Trethan wrote:

>Larger bubbles are supposedly required to get good scrubbing action at the  
>surface of the PCB.
>  
>

  I'd guess larger bubbles gives greater displacement, so higher 
velocity for the etchant as it comes back in as the bubble passes..

>With your large air pump i suppose big bubbles are good, if you can create  
>them in enough places so no streaks are visible.
>I reckon a moving air source would make things much easier to get even,  
>maybe a tube with a spiral pattern of many holes, that is rotated slowly  
>by the air in some way would be possible.
>
>ST
>  
>
  That could be extremely workable.  Think of a hose going down an arm, 
and then out an inch or two under the board.  A pendulum going back and 
forth under the board.  Linearize the swing and you would get almost 
guaranteed even etching, and it should be much easier to make and use 
than trying to get any long tube with holes along it to work evenly.  
Flood of bubbles and then a short time of contact to etch, I bet it 
wouldn't even be that much slower than a tank full of bubbles.

  Really, could come off both sides and make 3 short wands horizontally 
for bubbles from the arm.  More bubbles for faster etch, still 
reasonable enough to get them even, and the motion is really the key for 
evening things out..

  Heck, might work well with just 3 of the 1" or 2" stones sticking out 
from the arm.  While they suck for stationary use, with the motion they 
might work well and not have to make holes in tubing etc.

Alan

--- In Homebrew_PCBs@yahoogroups.com, "soffee83" <soffee83@y...>wrote:

I thought about 
> making a plexi rectangle with some type of standoffs to create a 
> vented chamber in the bottom of the tank, and gluing my tubes 
through 
> the tank's sides near the bottom, but figured it might be a hassle 
> while filling the tank and waiting for the etchant to fill the 
chamber 
> (or having the air try to lift it out). 

I see a comercial tank made it in this way, whith very short 
standoffs, so a little chamber. Gluing the tubes through the tank's 
sides near the bottom is not a good ideea. When you stop the pump, the 
solution goes in it. The tubes must be verticaly and goes out from 
tank at the solution sourface level. 


--- In Homebrew_PCBs@yahoogroups.com, Alan King <alan@n...> wrote:

Think of a hose going down an arm, 
> and then out an inch or two under the board.  A pendulum going back 
and 
> forth under the board.  Linearize the swing and you would get almost 
> guaranteed even etching, and it should be much easier to make and 
use 
> than trying to get any long tube with holes along it to work evenly. 
 
> Flood of bubbles and then a short time of contact to etch, I bet it 
> wouldn't even be that much slower than a tank full of bubbles.
> 

> Alan
>

Any kind of mouvement is certain a good ideea. 
I think there is much easy to mouve the board orizontaly. 
A rotary movement is ideal, because in this way, you can etch even the 
bottom and the top of the board. But you need a bigger tank for this.
I think about a suction cup in center of the board conected in some 
way to an outside little motor.


Adrian




Adrian

> I think about a suction cup in center of the board conected in some
>
> way to an outside little motor.

You better have one very large pad in that place than, or a groundplane ;-)

>
>
>
> Adrian


The rotating thing might be a OK idea.
if anyone is going to experiment with movement of either air or pcb  
consider using magnets like in a stirrer. Small neodymium magnets are  
cheap and surely will follow each other through the glass easily. You can  
have the motor outside, nice and dry, and the magnet inside the etchant  
can be encapsulated easily.

By the way i agree the hose must go out through the top to avoid any  
etchant coming into the pump.

Actually, when i suggested the moving air nozzle was thinking not of a  
pendulum, but of a rotating tube, like a barber's pole you know, with  
holes in a spiral pattern. At any time only one or few holes are on top,  
spewing air, but there is a total of very many holes in different places.  
Just an idea....
Might be easier to make the pole a bit shorter than the tank, and not  
rotate it but instead slide it back and forth with a magnet one the  
outside.


ST

--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan" 
<stefan_trethan@g...> wrote:

> You better have one very large pad in that place than, or a 
groundplane ;-)

We must learn this: suction cup is a verry good ideea to make huge 
pads ;-) 
I refer to a one side board. You are wright, this system is not 
applicable to 2 side boards. A frame system is better.;-)

About spiral patern: I'm not sure is working...it's a complicated 
question. In teory is working, but... 
Maybe we sould talk whith a fluids dinamics engineer to give us some 
advices ;-)
Or make some experiments. 

The magnets is the easyest way to rotate the board. I like this.
There is the easyest alternative to vibrating the board. I have an old 
shaveing machine for this job. But same problem: the bottom will be 
over etched. So let's return to rotating ideea...

Some experiments is a must...


Adrian

I don't think there is a easy way to get better uniformity. A spray etcher  
may not be that much more complicated in the end.

For now i'm satisfied with what i have. The underetching is OK down to  
like 6.66mil which is the smallest i'll need for a long time.
Also, by using ground planes one can keep "open areas" to a minimum and  
there's no need to wait for them to finish.

ST

On Fri, 23 Dec 2005 10:43:53 +0100, adicont2 <adicont2@...> wrote:

>
> We must learn this: suction cup is a verry good ideea to make huge
>
> pads
>
> I refer to a one side board. You are wright, this system is not
>
> applicable to 2 side boards. A frame system is better.;-)
>
>
> About spiral patern: I'm not sure is working...it's a complicated
>
> question. In teory is working, but...
>
> Maybe we sould talk whith a fluids dinamics engineer to give us some
>
> advices
>
> Or make some experiments.
>
>
> The magnets is the easyest way to rotate the board. I like this.
>
> There is the easyest alternative to vibrating the board. I have an old
>
> shaveing machine for this job. But same problem: the bottom will be
>
> over etched. So let's return to rotating ideea...
>
>
> Some experiments is a must...
>
>
>
> Adrian

Stefan Trethan wrote:

>
>Actually, when i suggested the moving air nozzle was thinking not of a  
>pendulum, but of a rotating tube, like a barber's pole you know, with  
>holes in a spiral pattern. At any time only one or few holes are on top,  
>spewing air, but there is a total of very many holes in different places.  
>Just an idea....
>  
>

  Yes, got that part of the idea but a simpler motion system will be 
easier..

>Might be easier to make the pole a bit shorter than the tank, and not  
>rotate it but instead slide it back and forth with a magnet one the  
>outside.
>
>  
>
  But that will require something else to do moving, and rotary to 
linear motion.

  Tank, then a pole on the outside center of the long side of the tank, 
that's 2x the height of the tank, so the hinge point is at 1x more above 
the edge of the tank.  Longer arm to make the sweep at the bottom more 
linear.  Say a 1.8X arm, with a stone at the bottom, and air tube to the 
stone.  Driving link and motor attach near the hinge, well out of the 
etchant.  Use a flat arm, flatten the tube a bit as it passes the lid, 
and have a decent raise/lower system for the board, and you can leave a 
top on the tank.  Just a slot for the arm/tube to sweep, and a slot to 
load the board through..  Clear PVC etc on each side of those slots, to 
close it except when the arm or board are right there, and you will have 
near zero evaporation, and almost never open the container.  Just slot 
load the board and etch.  No tube thing to build, just get a stone and 
some line and make a fairly simple pendulum and attach a motor to it.  
Can be greatly linearized with a little mechanical mixing, or a stepper 
etc could make it near perfectly linear.  So simple we should have come 
up with it talking about the rotary etcher and other types last year, 
duh if a stone is too uneven sitting there then move it..  Obvious 
concept, just didn't even cross my mind at that time..

  Wait till you see some video of my little manufacturing plant for 
rounding my boards and applying the LEDs, I think it's rather neat.. :)  
So nice to have all the flying dust stay inside a ziplock bag..  Now to 
automate my iron and solder feed and feeding the LEDs, may as well let 
it build the board for me while I go have a beer.

Alan

I'm not convinced those slots will be small enough to prevent the vapor  
coming out when the bubbler is on.

I see what you mean, my idea for the moving tube is because i would like  
to keep it fairly low in height so the tank mustn't be enlarged much. If  
one would be able to get a small number of holes working uniformly the  
length you need to move the nozzles would be reduced. I don't think it  
much of a problem to make a magnet slide around outside the tank...


Anyway, if you make that pendulum, why not attach soft plastic brushes  
that brush the board? might be more uniform, and the wiping action surely  
mixes the etchant well enough. If the brushes were moved with magnets one  
could put a windscreen wiper assy outside the tank, or something similar.

I'm not gonna try that any time soon, since my setup is just too simple  
and too well working to change. Even the thought of making a PCB holder  
that holds the board firmly enough to allow brushing seems way too much  
work to me.


ST

On Fri, 23 Dec 2005 13:17:09 +0100, Alan King <alan@...> wrote:

>
>
>   But that will require something else to do moving, and rotary to
>
> linear motion.
>
>
>   Tank, then a pole on the outside center of the long side of the tank,
>
> that's 2x the height of the tank, so the hinge point is at 1x more above
>
> the edge of the tank.  Longer arm to make the sweep at the bottom more
>
> linear.  Say a 1.8X arm, with a stone at the bottom, and air tube to the
>
> stone.  Driving link and motor attach near the hinge, well out of the
>
> etchant.  Use a flat arm, flatten the tube a bit as it passes the lid,
>
> and have a decent raise/lower system for the board, and you can leave a
>
> top on the tank.  Just a slot for the arm/tube to sweep, and a slot to
>
> load the board through..  Clear PVC etc on each side of those slots, to
>
> close it except when the arm or board are right there, and you will have
>
> near zero evaporation, and almost never open the container.  Just slot
>
> load the board and etch.  No tube thing to build, just get a stone and
>
> some line and make a fairly simple pendulum and attach a motor to it.
>
> Can be greatly linearized with a little mechanical mixing, or a stepper
>
> etc could make it near perfectly linear.  So simple we should have come
>
> up with it talking about the rotary etcher and other types last year,
>
> duh if a stone is too uneven sitting there then move it..  Obvious
>
> concept, just didn't even cross my mind at that time..
>
>
>   Wait till you see some video of my little manufacturing plant for
>
> rounding my boards and applying the LEDs, I think it's rather neat..
>
> So nice to have all the flying dust stay inside a ziplock bag..  Now to
>
> automate my iron and solder feed and feeding the LEDs, may as well let
>
> it build the board for me while I go have a beer.
>
>
> Alan
>
>

I dont' know how to spell it nor do I know if it is the thing I am 
thinking of....

There are these machines used for mixing chemicals. You see them in 
all sorts of video showing the mixing of chemicals. It is not the 
device like you see them place a bunch of test tubes on a spinning 
thing, this thing is different.

There is a spinning magnent under the top surface of the machine.  
You place a beaker of fluid on top of that surface and turn on the 
machine and the fluid spins like crazy - very good fluid agitation 
without any mechanical connections or hoses etc.  The things look 
neat as hell, but I have not idea what they are called or how 
exactly they work.  

If this could be done with the chemicals we use in this process, 
there could be some advantages..

1) you could seal the container during agitation (unless there is 
some gas given off during the process of eating away the coppper)

2) the agitation would be very consistant within the container and 
it would be a consistant process.  The board position within the 
container could be a problem though.

3) no hoses to siphon out the chemicals when doing something stupid 
(like placing the pump lower than the fluid level)

There are some draw backs too though.

The container would probably have to be round - just a guess
If enclosing the container, a support system would have to be made 
that could be kept inside the tank (I think most every hangs the 
boards from the top of the tank).

Just a thought on this subject, perhpas there is something there 
that is useful.

Chris







-- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan" 
<stefan_trethan@g...> wrote:
>
> I'm not convinced those slots will be small enough to prevent the 
vapor  
> coming out when the bubbler is on.
> 
> I see what you mean, my idea for the moving tube is because i 
would like  
> to keep it fairly low in height so the tank mustn't be enlarged 
much. If  
> one would be able to get a small number of holes working uniformly 
the  
> length you need to move the nozzles would be reduced. I don't 
think it  
> much of a problem to make a magnet slide around outside the tank...
> 
> 
> Anyway, if you make that pendulum, why not attach soft plastic 
brushes  
> that brush the board? might be more uniform, and the wiping action 
surely  
> mixes the etchant well enough. If the brushes were moved with 
magnets one  
> could put a windscreen wiper assy outside the tank, or something 
similar.
> 
> I'm not gonna try that any time soon, since my setup is just too 
simple  
> and too well working to change. Even the thought of making a PCB 
holder  
> that holds the board firmly enough to allow brushing seems way too 
much  
> work to me.
> 
> 
> ST
> 
> 
> On Fri, 23 Dec 2005 13:17:09 +0100, Alan King <alan@n...> wrote:
> 
> >
> >
> >   But that will require something else to do moving, and rotary 
to
> >
> > linear motion.
> >
> >
> >   Tank, then a pole on the outside center of the long side of 
the tank,
> >
> > that's 2x the height of the tank, so the hinge point is at 1x 
more above
> >
> > the edge of the tank.  Longer arm to make the sweep at the 
bottom more
> >
> > linear.  Say a 1.8X arm, with a stone at the bottom, and air 
tube to the
> >
> > stone.  Driving link and motor attach near the hinge, well out 
of the
> >
> > etchant.  Use a flat arm, flatten the tube a bit as it passes 
the lid,
> >
> > and have a decent raise/lower system for the board, and you can 
leave a
> >
> > top on the tank.  Just a slot for the arm/tube to sweep, and a 
slot to
> >
> > load the board through..  Clear PVC etc on each side of those 
slots, to
> >
> > close it except when the arm or board are right there, and you 
will have
> >
> > near zero evaporation, and almost never open the container.  
Just slot
> >
> > load the board and etch.  No tube thing to build, just get a 
stone and
> >
> > some line and make a fairly simple pendulum and attach a motor 
to it.
> >
> > Can be greatly linearized with a little mechanical mixing, or a 
stepper
> >
> > etc could make it near perfectly linear.  So simple we should 
have come
> >
> > up with it talking about the rotary etcher and other types last 
year,
> >
> > duh if a stone is too uneven sitting there then move it..  
Obvious
> >
> > concept, just didn't even cross my mind at that time..
> >
> >
> >   Wait till you see some video of my little manufacturing plant 
for
> >
> > rounding my boards and applying the LEDs, I think it's rather 
neat..
> >
> > So nice to have all the flying dust stay inside a ziplock bag..  
Now to
> >
> > automate my iron and solder feed and feeding the LEDs, may as 
well let

> >
> > it build the board for me while I go have a beer.
> >
> >
> > Alan
> >
> >
>

"I'm not convinced those slots will be small enough to prevent the 
vapor coming out when the bubbler is on."

Those slots can be sealed whith soft rubber material like surgical 
gloves. I understand that you keep the etchant in tank when you don't 
use it. Am I wright?

"Anyway, if you make that pendulum, why not attach soft plastic 
brushes that brush the board? might be more uniform, and the wiping 
action surely mixes the etchant well enough." 

I'm totaly agree whith this opinion. All my actual boards is made 
whith a bowl and a sponge brush. The quality of etched board is very 
good.

"A spray etcher may not be that much more complicated in the end."
Yes if we solve the pump corosion problem.  
 
"I'm not gonna try that any time soon, since my setup is just too 
simple  and too well working to change.

Tell me Stefan, you use a homemade tube or a comercialy one like those 
make it for aquariums, or a long stone? 

"duh if a stone is too uneven sitting there then move it"

Is perfect true. Moving the bubbler or the board orizontaly is much 
better. But this don't solve the problem of differences between top 
and bottom of the board.




Adrian

On Fri, 23 Dec 2005 15:47:42 +0100, adicont2 <adicont2@...> wrote:

> Yes if we solve the pump corosion problem.

A diaphragm pump can be used and doesn't corrode. I'm not sure which,  
either shurflow or flojet was recommended, look in the archives. But they  
are not cheap. (They are usually used for water supply in camping vans and  
stuff).


> "I'm not gonna try that any time soon, since my setup is just too
>
> simple  and too well working to change.
>
>
> Tell me Stefan, you use a homemade tube or a comercialy one like those
>
> make it for aquariums, or a long stone?

I use a aquarium flexible hose. It is made of some foamy material and has  
two rows of very small punctures.
The homemade tube didn't work well (streaks).

>
>
> "duh if a stone is too uneven sitting there then move it"
>
>
> Is perfect true. Moving the bubbler or the board orizontaly is much
>
> better. But this don't solve the problem of differences between top
>
> and bottom of the board.


I don't think this problem can be solved entirely in a vertical immersion  
etcher, well, maybe with the brushes....
Even rotating it will not entirely solve it since the middle is always in  
the middle. (It is kind of the microwave i have here that has a "cold  
spot" exactly in the center. A bloody rotating plate is no help whatsoever  
if there's a cold spot in the center!)

Even with spray etchers this is an issue, a industrial conveyor sprayer  
will show different speeds between the leading edge and the rest of the  
board, because a puddle builds up. On top side that is.



ST

On Fri, 23 Dec 2005 15:34:50 +0100, lcdpublishing  
<lcdpublishing@...> wrote:

>
>
> There is a spinning magnent under the top surface of the machine.
>
> You place a beaker of fluid on top of that surface and turn on the
>
> machine and the fluid spins like crazy - very good fluid agitation
>
> without any mechanical connections or hoses etc.  The things look
>
> neat as hell, but I have not idea what they are called or how
>
> exactly they work.


This is called a magnetic stirrer. You drop a magnet, often coated in  
teflon, in the glass and a rotating magnetic field spins it. Often those  
machines are combined with a hotplate.


Your expected drawbacks are probably why this isn't used very often for  
etching.


ST

Okay, so you still have to put something in the fluid.  I didn't 
realize that and that too would be another problem - it might beat 
the PCB to death before I get the chance of letting it's magic smoke 
out!

Chris



--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan" 
<stefan_trethan@g...> wrote:
>
> On Fri, 23 Dec 2005 15:34:50 +0100, lcdpublishing  
> <lcdpublishing@y...> wrote:
> 
> >
> >
> > There is a spinning magnent under the top surface of the machine.
> >
> > You place a beaker of fluid on top of that surface and turn on 
the
> >
> > machine and the fluid spins like crazy - very good fluid 
agitation
> >
> > without any mechanical connections or hoses etc.  The things look
> >
> > neat as hell, but I have not idea what they are called or how
> >
> > exactly they work.
> 
> 
> This is called a magnetic stirrer. You drop a magnet, often coated 
in  
> teflon, in the glass and a rotating magnetic field spins it. Often 
those  
> machines are combined with a hotplate.
> 
> 
> Your expected drawbacks are probably why this isn't used very 
often for  

> etching.
> 
> 
> ST
>

Dave Kush is using one!!! www.buildyouridea.com


--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@g...> wrote:
>
> On Fri, 23 Dec 2005 15:34:50 +0100, lcdpublishing  
> <lcdpublishing@y...> wrote:
> 
> >
> >
> > There is a spinning magnent under the top surface of the machine.
> >
> > You place a beaker of fluid on top of that surface and turn on the
> >
> > machine and the fluid spins like crazy - very good fluid agitation
> >
> > without any mechanical connections or hoses etc.  The things look
> >
> > neat as hell, but I have not idea what they are called or how
> >
> > exactly they work.
> 
> 
> This is called a magnetic stirrer. You drop a magnet, often coated in  
> teflon, in the glass and a rotating magnetic field spins it. Often
those  
> machines are combined with a hotplate.
> 
> 
> Your expected drawbacks are probably why this isn't used very often
for  

> etching.
> 
> 
> ST
>

I know this foamy hoses. 
You keep the etcher and the hose in tank when you don't use it? Or you 
wash all stuff, including hose after each sesion. I'm worry about 
copper residues witch maybe seal those tiny holes.

So pendulum-not perfect. Rotating board-not perfect. 
Maybe togheter ;-)

But not now. Is a long time project. Now I will try to make something 
common whith a simple bubbler like all comercials tanks. There is an 
old russian proverb or a Murphy law, I don't remember: "If a thing 
work, don't improuve it" ;-)
 


Adrian


--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan" 
<stefan_trethan@g...> wrote:
>
> On Fri, 23 Dec 2005 15:47:42 +0100, adicont2 <adicont2@y...> wrote:
> 
> > Yes if we solve the pump corosion problem.
> 
> A diaphragm pump can be used and doesn't corrode. I'm not sure 
which,  
> either shurflow or flojet was recommended, look in the archives. But 
they  
> are not cheap. (They are usually used for water supply in camping 
vans and  
> stuff).
> 
> 
> > "I'm not gonna try that any time soon, since my setup is just too
> >
> > simple  and too well working to change.
> >
> >
> > Tell me Stefan, you use a homemade tube or a comercialy one like 
those
> >
> > make it for aquariums, or a long stone?
> 
> I use a aquarium flexible hose. It is made of some foamy material 
and has  
> two rows of very small punctures.
> The homemade tube didn't work well (streaks).
> 
> >
> >
> > "duh if a stone is too uneven sitting there then move it"
> >
> >
> > Is perfect true. Moving the bubbler or the board orizontaly is 
much
> >
> > better. But this don't solve the problem of differences between 
top
> >
> > and bottom of the board.
> 
> 
> I don't think this problem can be solved entirely in a vertical 
immersion  
> etcher, well, maybe with the brushes....
> Even rotating it will not entirely solve it since the middle is 
always in  
> the middle. (It is kind of the microwave i have here that has a 
"cold  
> spot" exactly in the center. A bloody rotating plate is no help 
whatsoever  
> if there's a cold spot in the center!)
> 
> Even with spray etchers this is an issue, a industrial conveyor 
sprayer  
> will show different speeds between the leading edge and the rest of 
the  

> board, because a puddle builds up. On top side that is.
> 
> 
> 
> ST
>

adicont2 wrote:

>"I'm not convinced those slots will be small enough to prevent the 
>vapor coming out when the bubbler is on."
>
>Those slots can be sealed whith soft rubber material like surgical 
>gloves. I understand that you keep the etchant in tank when you don't 
>use it. Am I wright?
>
>  
>
  Yes, it'll be very easy to do..

>"Anyway, if you make that pendulum, why not attach soft plastic 
>brushes that brush the board? might be more uniform, and the wiping 
>action surely mixes the etchant well enough." 
>
>I'm totaly agree whith this opinion. All my actual boards is made 
>whith a bowl and a sponge brush. The quality of etched board is very 
>good.
>
>  
>
  While this can work well by hand, a mechanical means will tend to make 
streaks.  And a pendulum has a non-linear sweep from top to bottom 
anyway.  Bubbles have the high advantage of once released they travel 
basically linearly upwards.

>"A spray etcher may not be that much more complicated in the end."
>Yes if we solve the pump corosion problem.  
>  
>
  Order of magnitude more of a PITA to get many nozzels to spray evenly, 
and sweeping just one or very few in both X and Y will require much more 
complexity.  Point source for bubbles, and gravity takes care of the 
other direction. 


> 
>"I'm not gonna try that any time soon, since my setup is just too 
>simple  and too well working to change.
>
>Tell me Stefan, you use a homemade tube or a comercialy one like those 
>make it for aquariums, or a long stone? 
>
>"duh if a stone is too uneven sitting there then move it"
>
>Is perfect true. Moving the bubbler or the board orizontaly is much 
>better. But this don't solve the problem of differences between top 
>and bottom of the board.
>
>
>  
>

  Almost every other aspect of a bubbler and several other methods was 
discussed thoroughly a year or two ago..   A simple wedge shape to force 
the bubbles back against the board as they try to spread out as they 
rise is all that's needed.  Easy to linearize the swing, and with the 
edge of the board not holding the bubbles in place as well, non-linear a 
bit may actually be better.

  Construction and maintenance advantages should be way over the other 
units. Once engineered, about anyone could go to Walmart and the 
hardware store, get the parts, and build it up in an hour or two.  While 
many things can be made to work, air is simple and reliable.  I'd bet 
you could assemble 3 or 4 of these or more in the time taken to get 
about anything else working evenly, not even thinking about whether the 
others will be long term reliable.  So simple I may make it just to see 
it work, even though I'm moving away from making most of my own boards..

Alan

On Fri, 23 Dec 2005 20:04:27 +0100, adicont2 <adicont2@...> wrote:

> I know this foamy hoses.
>
> You keep the etcher and the hose in tank when you don't use it? Or you
>
> wash all stuff, including hose after each sesion. I'm worry about
>
> copper residues witch maybe seal those tiny holes.

I keep them all in forever, no adverse effects. For a while when i ran the  
thing closed loop (air pump intake in tank) the mist made the pump valves  
stick and i thought the hose had deteriorated, but now that i have cleaned  
the pump and run it open loop i see the hose is like on the first day.


> So pendulum-not perfect. Rotating board-not perfect.
>
> Maybe togheter
> But not now. Is a long time project. Now I will try to make something
>
> common whith a simple bubbler like all comercials tanks. There is an
>
> old russian proverb or a Murphy law, I don't remember: "If a thing
>
> work, don't improuve it"
>
> Adrian

Yes, it's called "never touch a running system", i think, or "if it ain't  
broken, don't fix it".

I must admit i sometimes didn't follow the rule and tried to improve  
things, making it much worse...

ST

I must admit i sometimes didn't follow the rule and tried to improve 
 things, making it much worse...

Me too...;-)


Adrian

adicont2 wrote:

>I know this foamy hoses. 
>You keep the etcher and the hose in tank when you don't use it? Or you 
>wash all stuff, including hose after each sesion. I'm worry about 
>copper residues witch maybe seal those tiny holes.
>  
>
  It is a don't care item, pull it up, put on another stone for $.50, 
and toss the old one.  Not like it'd clog up that fast anyway..

>So pendulum-not perfect.
>
  Maybe in your mind, I'm pretty sure off hand it'll be about as close 
as you'll ever be able to get.

> Rotating board-not perfect. 
>Maybe togheter ;-)
>  
>
  That will be a step backwards, the center of a spinning board will be 
guaranteed less etched..

>But not now. Is a long time project. Now I will try to make something 
>common whith a simple bubbler like all comercials tanks. There is an 
>old russian proverb or a Murphy law, I don't remember: "If a thing 
>work, don't improuve it" ;-)
> 
>  
>

  Refer back to the beginning of the law, *"If a thing work.."*.  Rarely 
is someone trying to sell something like this interested in whether it 
works or not nearly as much as if they can sell it..  Even if their's 
does, it's no guarantee you'll be able to get a homemade one working as 
easily as you appear to be thinking..  Should be easy enough to get ok 
results. but also don't be too surprised if you don't, they've likely 
solved many small problems you don't yet know about to get their's to 
even work ok..

  There are also some other sayings, like don't do things the hard way.  
I haven't even built it yet, but I'd already put money on swinging the 
stone being 3 to 5 times simpler to get up and going than anything 
else.  Extremely simple idea, that already eliminates the sticking 
points from a static bubbler.  Everything else has a critical point or 
two that will be rather finiky.  You guys might not see it yet, but I 
still have all the solutions from a year ago clearly in mind, it'll be a 
breeze.  I think you'll have a lot more trouble recreating the flat hose 
type than I'll have getting the pendulum going.  Heck may go back out to 
Walmart even with the Christmas rush to get some of the small cheap 
stones, only kept the rail types from last time.

Alan

A simple wedge shape to force 
> the bubbles back against the board as they try to spread out as they 
> rise is all that's needed.  Easy to linearize the swing, and with 
the 
> edge of the board not holding the bubbles in place as well, non-
linear a 
> bit may actually be better.

Sorry, I'm affraid I dont understand... A "wedge shape"...


Adrian

On Fri, 23 Dec 2005 21:41:33 +0100, Alan King <alan@...> wrote:

>
>
>   There are also some other sayings, like don't do things the hard way.
>
> I haven't even built it yet, but I'd already put money on swinging the
>
> stone being 3 to 5 times simpler to get up and going than anything
>
> else.  Extremely simple idea, that already eliminates the sticking
>
> points from a static bubbler.  Everything else has a critical point or
>
> two that will be rather finiky.  You guys might not see it yet, but I
>
> still have all the solutions from a year ago clearly in mind, it'll be a
>
> breeze.  I think you'll have a lot more trouble recreating the flat hose
>
> type than I'll have getting the pendulum going.  Heck may go back out to
>
> Walmart even with the Christmas rush to get some of the small cheap
>
> stones, only kept the rail types from last time.
>
>
> Alan


Yes, well, you like the pendulum idea, i don't like it. With the pendulum  
outside the tank, and magnetic traction, maybe...
You do things by gut feeling and educated guesses, i do them the same way,  
we just disagree on that one ;-)

ST

On Fri, 23 Dec 2005 21:43:04 +0100, adicont2 <adicont2@...> wrote:

>
> Sorry, I'm affraid I dont understand... A "wedge shape"...
>
>
>
> Adrian


The discussion back then was the lower edge of the board etches faster -  
why?
probably because the bubbles hit the lower edge, but then drift away from  
the board as they rise.
If one would put a wedge "guide" there, combined with largish bubbles,  
that would press them against the pcb all the way.

ST

In a message dated 12/23/2005 8:35:42 A.M. Central Standard Time,  
lcdpublishing@... writes:

Just a  thought on this subject, perhpas there is something there 
that is  useful


Sadly, there is a "thing" in there that makes the liquid spin,  usually a 
magnet in a fuzed-shut glass tube or a molded over (teflon?) jacket,  etc.   
Would NOT be useful around a vertical, flat, being-etched  PCB.  
 
Too bad the etchants are such nasty liquids, as the best way  would be a pump 
that sprays from many tiny holes in a straight line, so the  liquid would 
rinse down both faces of the board, being continuously mixed until  depleted, so 
always the same etch-rate, all over, until done.  But  selection/paying-for a 
pump that will handle the nasties with acceptably-little  maintenance is SUCH 
a drag!  The bubbling idea is second-best, but getting  the holes in the 
"pipe" and air-pressure just right for consistently-sized  and/or ideal 
quantities/second bubbles is SUCH a variable hassle!  
 
Centrifuge.        JRR


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

Stefan Trethan wrote:

>On Fri, 23 Dec 2005 21:41:33 +0100, Alan King <alan@...> wrote:
>
>  
>
>>  There are also some other sayings, like don't do things the hard way.
>>
>>
>>    
>>
>
>Yes, well, you like the pendulum idea, i don't like it. With the pendulum  
>outside the tank, and magnetic traction, maybe...
>You do things by gut feeling and educated guesses, i do them the same way,  
>we just disagree on that one ;-)
>
>  
>

  Well you have to have the hose going down to the stone anyway, and 
over the tank edge is preferred for that.  Using flat stock it won't 
really add anything to the tank over the size of the stone, so don't see 
any advantage to outside. 

  Yes, I like this very much, because the other problems for this method 
we've fairly well worked out, and moving the stone bypasses the 
remaining sticking point or two from a flat horizontal line, making 
everything non-critical.  Can't get much simpler than stick a stone on a 
hose down there and swing it around under the board, and pumps and 
stones are known to be reliable for long periods.  Not that other things 
can't be made to work quite well, but I think that even after you solve 
the little gotchas, it's going to be a lot harder for the next guy to 
repeat your solutions accurately.  Stone on a hose with a little 
mechanics is simplistic enough that I think it'll be fairly easy for 
anyone to build it up and get it working well..

Alan

Aha, now I understand. Thanks Stefan.
If the board is not perfect verticaly, but a little bit inclined at 
30* or less, maybe will be same effect.


Adrian 

--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan" 
<stefan_trethan@g...> wrote:

> 
> The discussion back then was the lower edge of the board etches 
faster -  
> why?
> probably because the bubbles hit the lower edge, but then drift away 
from  
> the board as they rise.
> If one would put a wedge "guide" there, combined with largish 
bubbles,  

> that would press them against the pcb all the way.
> 
> ST
>

Dave Kush is using a glass baking dish with glass marbles to hold the
board above the spinning magnet.

Link from my conference to Dave's page

http://buildyouridea.com/hardware/modus/phase_5/phase_5.html


--- In Homebrew_PCBs@yahoogroups.com, JanRwl@A... wrote:
>
>  
> In a message dated 12/23/2005 8:35:42 A.M. Central Standard Time,  
> lcdpublishing@y... writes:
> 
> Just a  thought on this subject, perhpas there is something there 
> that is  useful
> 
> 
> Sadly, there is a "thing" in there that makes the liquid spin, 
usually a 
> magnet in a fuzed-shut glass tube or a molded over (teflon?) jacket,
 etc.   
> Would NOT be useful around a vertical, flat, being-etched  PCB.  
>  
> Too bad the etchants are such nasty liquids, as the best way  would
be a pump 
> that sprays from many tiny holes in a straight line, so the  liquid
would 
> rinse down both faces of the board, being continuously mixed until 
depleted, so 
> always the same etch-rate, all over, until done.  But 
selection/paying-for a 
> pump that will handle the nasties with acceptably-little 
maintenance is SUCH 
> a drag!  The bubbling idea is second-best, but getting  the holes in
the 

> "pipe" and air-pressure just right for consistently-sized  and/or ideal 
> quantities/second bubbles is SUCH a variable hassle!  
>  
> Centrifuge.        JRR
> 
> 
> [Non-text portions of this message have been removed]
>

adicont2 wrote:

>A simple wedge shape to force 
>  
>
>>the bubbles back against the board as they try to spread out as they 
>>rise is all that's needed.  Easy to linearize the swing, and with 
>>    
>>
>the 
>  
>
>>edge of the board not holding the bubbles in place as well, non-
>>    
>>
>linear a 
>  
>
>>bit may actually be better.
>>    
>>
>
>Sorry, I'm affraid I dont understand... A "wedge shape"...
>
>
>  
>

   Think of looking at the edge of the vertical standing board as a 
line, and put another board over to the side, with the top tilted to the 
board you're etching.  Forces the bubbles back towards the board, get 
the distance and tilt right and it should get the etching to almost 
exactly even..  Bubbles spread out as well as going up, a wedge on 
either side would correct most of it by forcing them back to the 
board..  Would look about like this from one end:

  / | \
 /o|o\
/ o|o  \
  o o


  But while I consider this something to design out very soon just to 
see exactly how well I can make it work, I have boards to finish cutting 
out and make first..

Alan

On Fri, 23 Dec 2005 23:31:41 +0100, adicont2 <adicont2@...> wrote:

> Aha, now I understand. Thanks Stefan.
>
> If the board is not perfect verticaly, but a little bit inclined at
>
> 30* or less, maybe will be same effect.
>
>
>
> Adrian


You are thinking single-sided again ;-)

ST

...and you are wright again ;-)
I made only single sided boards until now...so I have a single sided 
brain ;-)



Adrian


--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan" 
<stefan_trethan@g...> wrote:
>
> On Fri, 23 Dec 2005 23:31:41 +0100, adicont2 <adicont2@y...> wrote:
> 
> > Aha, now I understand. Thanks Stefan.
> >
> > If the board is not perfect verticaly, but a little bit inclined 
at

> >
> > 30* or less, maybe will be same effect.
> >
> >
> >
> > Adrian
> 
> 
> You are thinking single-sided again ;-)
> 
> ST
>

I understand. Thanks for your eplications.
I'm impatient to see youre pendulum at work.





Adrian
--- In Homebrew_PCBs@yahoogroups.com, Alan King <alan@n...> wrote:
>
> adicont2 wrote:
> 
> >A simple wedge shape to force 
> >  
> >
> >>the bubbles back against the board as they try to spread out as 
they 
> >>rise is all that's needed.  Easy to linearize the swing, and with 
> >>    
> >>
> >the 
> >  
> >
> >>edge of the board not holding the bubbles in place as well, non-
> >>    
> >>
> >linear a 
> >  
> >
> >>bit may actually be better.
> >>    
> >>
> >
> >Sorry, I'm affraid I dont understand... A "wedge shape"...
> >
> >
> >  
> >
> 
>    Think of looking at the edge of the vertical standing board as a 
> line, and put another board over to the side, with the top tilted to 
the 
> board you're etching.  Forces the bubbles back towards the board, 
get 
> the distance and tilt right and it should get the etching to almost 
> exactly even..  Bubbles spread out as well as going up, a wedge on 
> either side would correct most of it by forcing them back to the 
> board..  Would look about like this from one end:
> 
>   / | \
>  /o|o\
> / o|o  \
>   o o
> 
> 
>   But while I consider this something to design out very soon just 
to 
> see exactly how well I can make it work, I have boards to finish 
cutting 

> out and make first..
> 
> Alan
>

Yes, so am I.  Have my boards to cut out, and the CNC to do, so will 
be doing lots of mechanical things this week anyway.  Have some stuff to 
return too, likely will pick up a few stones in the next day or two.  
Doubt I will etch anything, just set up a proof of concept in water so 
you can see where it's headed.  Meant to buy some Amonium Persulfate 
before anyway, now I will have to order some soon to have the clear 
etchant and take some video.  Many other things to do soon though and 
having boards made now so less need for home etching, so may be a while 
before I make the real tank. 

  Also never even thought to add a drop of dishwashing liquid to the 
etchant, wondering if it'll foam up ok without messing it up.  Doubt 
it'd help the speed etc, but more of a foaming than bubbling could help 
with the evening of the etching..

Alan


adicont2 wrote:

>I understand. Thanks for your eplications.
>I'm impatient to see youre pendulum at work.
>
>
>  
>

i don't see how etchant foam spilling out of the tank and all over your  
shop floor would make things better?

ST

On Mon, 26 Dec 2005 02:12:07 +0100, Alan King <alan@...> wrote:

>
>
>   Also never even thought to add a drop of dishwashing liquid to the
>
> etchant, wondering if it'll foam up ok without messing it up.  Doubt
>
> it'd help the speed etc, but more of a foaming than bubbling could help
>
> with the evening of the etching..
>
>
> Alan

Drop or two, not half the bottle..  Could improve the evening of the 
circulation in the center section, basically a foaming volcano.  Likely 
not needed at all, but something else to try that would tend to make the 
etching more even.  Heck I will try it just to see it happening..

Alan


Stefan Trethan wrote:

>i don't see how etchant foam spilling out of the tank and all over your  
>shop floor would make things better?
>
>ST
>
>
>
>On Mon, 26 Dec 2005 02:12:07 +0100, Alan King <alan@...> wrote:
>
>  
>

I don't know to much chemistry...but take care about dishwashing 
liquid. Do not exagerate. I'm not sure about chemical reaction, but I 
think will be a lot of foam there.
Teoreticaly foam means more density, so less bubbles speed...



Adrian




--- In Homebrew_PCBs@yahoogroups.com, Alan King <alan@n...> wrote:
>
>   Drop or two, not half the bottle..  Could improve the evening of 
the 
> circulation in the center section, basically a foaming volcano.  
Likely 
> not needed at all, but something else to try that would tend to make 
the 
> etching more even.  Heck I will try it just to see it happening..
> 
> Alan
> 
> 
> Stefan Trethan wrote:
> 
> >i don't see how etchant foam spilling out of the tank and all over 
your  

> >shop floor would make things better?
> >
> >ST
> >
> >
> >
> >On Mon, 26 Dec 2005 02:12:07 +0100, Alan King <alan@n...> wrote:
> >
> >  
> >
>