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Re: BS, was Re: [HP-Agilent-Keysight-equipment] Spread the word -- Swap Meet Returns!

 

Yep, I've used ferric chloride, and one of the disadvantages was that the etch product (copper chloride?) is dark and opaque and collects over the copper being etched. So agitation is in order, so that you can 1) see that the etching process is progressing, and 2) prevent the etch product from slowing or stopping the etching process. I'd heard of people putting marbles in the bottom of the etch tank and putting the board to be etched upside-down so that the etch product just falls off the board. But you can't easily monitor the process.

And monitoring is necessary; my first attempt back in the late 1980's failed because I had bad etchant. I left it sit with a heater under the tank for at least 10 hours while I went to work at my day job, and it didn't etch at all. Got another bottle of ferric chloride, and the second attempt was done in about 10 minutes. With some bumps every few seconds to move the etch product off the board.

IIRC, I diluted the waste in the tank with lots of cold water and poured it down the toilet.

Jim Ford

------ Original Message ------
From: "Lothar baier" <Lothar@...>
To: "[email protected]" <[email protected]>
Sent: 3/20/2022 2:21:46 PM
Subject: Re: BS, was Re: [HP-Agilent-Keysight-equipment] Spread the word -- Swap Meet Returns!

Ferric cloride wasn¡¯t used commercially for PCB making in Germany probably because of the potential impact on worker health but also because it was pretty aggressive, most companies used ammonia persulfate compositions one advantage of the stuff was that it was transparent so you were able to watch the progress of the etching.
One company I remember we visited back when i was in trade school used a spray etch line which was pretty cool to watch
On Mar 20, 2022, at 12:36, greenboxmaven via groups.io <ka2ivy@...> wrote:

?I used to think mean cruel mangement was unique to the Syracuse area. A friend went to dental offices asking for their old X-ray photo chemicals. 99% of them not only refused, they were actually furious at him for asking. They insisted on pouring it down the sewer, which did not help our already overloaded treatment plant. The silver residue was very toxic to the bacteria used to digest the sewage. Those of us working in consumer electronics sweatshops didn't fare any better. There would be massive amounts of abandoned equipment in attics and back rooms, yet the shop owners would not allow us to take it home or even buy it. It was always VERY curious that when I went on vacation and returned, they had decided while I was gone was just the time to clean out the junk room. By the late 70s, almost all of us had escaped to far better careers and the sweatshops were out of business.

Bruce Gentry, KA2IVY





They certainly do recycle the copper!
I presented the information to the VP of the company, and
he said no. The etchant tank had a plastic garden hose
fitting at its bottom, so I told him that I was willing
to fill the old carboys, with a garden hose, and even work
for free, as we used at least one carboy per day, which
exceeded my hourly pay... He said no...

I guess he liked pouring money down the drain for some
reason.

-Chuck Harris




Was it possible to recycle the copper removed by these etchants?

Bruce Gentry, KA2IVY




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