Homebrew PCBs

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
>
>