Actually, i will reproduce a version of an etching bath, that is very popular, and many people use it for etching jobs. My version will be for small production for home use, but with professional result. The maximum width will be 10cm (3.9'') and the maximum height will be 22cm (8.6''). The etching solution will be heated with a 100Watt submersible aquarium heater, and the agitation will be done with an aquarium air pump.
I found a very nice 2.2lt water container for the refrigerator's door in my local super market. What's nice about this container, is that it is tall and thin. Thus, with just one liter of water (or FeCl3), it is half-filled, and that is about 12cm height. In other words, to etch a 10 by 10cm PCB (10x10 is the max size that Eagle PCB free versiob allows), i will use only 1 liter of etching solution - and i will only have to store one liter of etching solution.
The heating element
To maintain the etching solution at the proper temperature (around 40oC), i bought a 100 Watts aquarioum sumbersible heater. Unfortunately, this heater had an in-built thermostat with maximum temperature up to 32oC. Therefore, before installing it into my tank, i had to remove this thermostat and replace it with my own thermostat circuit. You can see the whole procedure of removing the thermostat here:
To boost the etching procedure even more, i bought an aquarium air pump to make bubles - the classic method. The pump that i bought is capable to provide 4 lt/min of air, at about 100cm water height. It operates directly with 220/240 VAC.
For those starting out making pcbs who want an out of the box solution, tank, heater, bubbler,thermometer have a look at kinsten.com.au $AU65 for the complete kit.
Look up edinborough etch - by adding citric acid to the ferric chloride solution - the copper ions are moved away from the pcb's copper surface much more efficiently than using bubbles.
Also, when I am only making a quick small board, I put the ferric chloride into a conical(erlinmyer) flask put it in a bath of boiling water from the kettle whens it's above 45C pour it into a plastic bowl & drop the board in & move the ferric chloride over the board with a brush.
@Skiwee Yes i do use it quite often indeed. As a matter of fact, this is the setup i use to make all my PCBs and never failed me.
I plan to make a bigger one, like 4 liters or maybe bigger. So i have some questions that maybe you could answer. To avoid flooding the comments board, i have open a thread in the forum. Please visit the following link:
http://www.pcbheaven.com/forum/index.php/topic,1486.0.html
I like the setup, you seem to use it quite often.
In the second video you agitate your etching solution. There\'s no need for that it\'s just copper sediment and waste from previous uses (it\'s best to hand this to your local hazardous waste management/company).
The solution should have a dark orange/brown \"oily\" appearance.
example image; http://upload.wikimedia.org/wikipedia/en/thumb/8/8c/Iron%28III%29_chloride.JPG/551px-Iron%28III%29_chloride.JPG
for more information on chemicals a quick MSDS search on google goes a long way.
Were did you find the air pumb and the heating resistor ... Also an other thing is about the thermistor is PTC or Ntc what you suggest!
Very nice job !! ... i Would like to build one too :-p
Welcomes from Crete!!
At 28 February 2011, 13:01:30 user Fung wrote: [reply @ Fung]
What will happen if the process is overtime? (ie The board is done but not taken out on time)
Hi Das,
the bubbles accelerate the procedure. They do not stick on the PCB, and even if one bubble sticks on it, there will be another bubble to remove it within a moment. The do a great job.
I do not know if a pump could do a better job, i have not test it yet. But i do know that it would be an ugly job to clean it. Copper remains would destroy the pump if not used. It had to be cleaned regularly to keep it clean. And moreover, why risk circulating the messy etchant outside the tank, if the bubbles work that fine?
At 1 January 2011, 17:37:49 user Das wrote: [reply @ Das]
wont the bubbles stick to the PCB during the process and hence reduce the effectiveness??
since you already used a fish tank air pump, why not a water pump to circulate the solution? if a pipe with holes along the length is made and one end sealed off, that would help distribute the solution even better.
herctrap you are so right. I had totally forgotten it. I had the masters given to a friend to make the video, but he never did it and did not inform me. I forgot all about it. I will search for the masters (although i am sure that i will not find them again) or i will run a new video. thanks for noticing reminding me.
By the way, my goal was to have a video for each project or circuit (and sometimes for theories and experiments). The fact that you noticed that this page should have a video, makes me double happy. This proves 2 things for me: first that people want to see videos of the circuits and the projects (and so my efforts to make them is not useless), and second that people do know that in this site they expect find videos, and that something is going wrong if there is no video in a project. When i upload the video i will post it in the RSS. Thank you again.
At the moment, i etch without ventilation, but i have an old vacuum that i will convert to ventilator. I really had no idea that rust could occur, although now it sound normal to me! I was considering the ventilation for health reasons only. Thank you for the info Vern!
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