I am in the middle of setting up a small 'ammonical' copper etching tank. My main problem is finding detailed information on the bath composition and operating parameters for the ammonical etching.
Information I gathered from online articles in www.pcbfab.com/ineretch.html and the article by Rudy Sedlak www.finishing.com/library/rscuetch.html is about the best I can find. I have not found any books on printed circuit manufacture that go into necessary detail either. And as far as I know ammoniacal etching of copper is not used in any industrial process other than in PCB manufacture. Because this is a specialized process I suspect any technical information on ammoniacal etching is specific or proprietary to the suppliers of the etchant or etching equipment.
Would this be correct, and the only way I can find such data would be to visit the suppliers or do my own pain staking experiments ?Adam Seychell
Operating parameters are: 140-155 g/l Copper 180-190 g/l Chlorides, hence, you mix ammonia chloride with water. This is an endoterm reaction, which means that it needs heat to mix. I think that the mixture of ammonia chloride solution (170-175 g/l chlorides)in conjunction with a pH adjustment (ammonia)to about 9,(temp 50 C) will be enough to start the etching reaction. This way you can dissolve copper to desired concentration.
Then lower the pH to 8.5(by not adding more ammonia or vent) and start etching. And maintain the copper by adding the ammonia chloride solution. Its critical that the copper, pH and chlorides are in spec. Otherwise sludge occur. I think this will work if you don't want to use propriety chemicals, which contains speed enhancers and such. regards PeterPeter
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