I’ve consistently had inconsistent results from etching PCBs. My best luck has been with PCB developing using a laser printer and transparency sheets. I was whiping up a batch of PCBs for my 6 meter amplifier when I decided I was really getting annoyed with figuring out how to keep the etchant hot, but not too hot. This PLC modulates the temperature at a predefined setpoint. It switches a relay on and off to a heating element I scrapped out of a 10$ coffee maker and I used a little fountain water pump that cost me $8. The rest of the materials I had laying around. I kept my etchant at 125 deg F. A probe within the 5 gallon bucket monitored the temperature. Because of the staged heating the temperature varied about 5 degrees total. The heat of the water pumping transferred through the plastic container and heated the etchant so I didn’t have to directly heat the etchant.
I still have the bones of this project though I haven’t etched a board in a solid two years so I re-purposed some of the items.
