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22 February 2010
Author: Giorgos Lazaridis
PCB Etching Bath with Heater and Agitation

Worklog - The cabinet design (March 2 2009)

Well, we have the drill with the foot pedal, we have the neat PCB artwork transfer UV LED box, what we lack of is the etching bath, otherwise the PCB lab is incomplete. Here we are again with a PCB Heaven project.

What's in my mind after all?

The 2.2lt thin and tall tank

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:

Agitating the solution

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.