Safest etchant for home-made PCBs?

[AndyBeez]

Thinks, if the OP wants cheap and dirty one off prototype PCBs, then isolation milling is the safest and chemical free environmentally safe way forward.

https://www.digikey.com/en/maker/projects/everything-you-need-to-know-about-milling-pcbs/9b7575e4ee6e4109aa32c3ccd4d5605b

[Siwastaja]

Thinks, if the OP wants cheap and dirty one off prototype PCBs, then isolation milling is the safest and chemical free environmentally safe way forward.

If you are concerned about health, milling produces a lot of fine glassfiber + PCB resin dust. This can be bigger potential issue than the etchants.

Fume extraction of the etchant will be simpler and more obvious than safely getting rid of all the dust.

I don't know how big of an issue it actually is, but every time I milled FR4 I did have symptons of respiratory irritation.

[Canis Dirus Leidy]

In Soviet times, when iron chloride was in short supply, hobbyists used a mixture of two or three parts of kitchen salt to one part of copper sulfate.
And in present times, an option with pharmacy peroxide and citric acid has been proposed: 100ml of 3% hydrogen peroxide, 30 gram of citric acid and 5 gram (or just tea-spoon) of kitchen salt.

Both variants are safe enough but very slow. At room temperature, it takes hours to etch the board.

[freda]

the safest and easiest etchant is the one in a chinese pcb factory.
- it's far away where it can not splash , spill or creates fumes for you
- it's cheap. way cheaper than what you would pay per kg and it comes with a free doublesided board, soldermask , silkscreen and all.

drawback
it takes roughly 5 to 8 days to "etch" the board... but you can use that time to do something else.

Seconded. Thirded even.
...

it is ** NOT ** cheap. (for the hobbyist)
1. You can only order one PCB design per order
2. to Each order is added a very exorbitant postage $
3. you don't need 5 or whatever of those

So you guys are saying for every circuit, most probably a dozen or so components that
I prefer not doing a point to point prototype board for, just send it off to china!. FFS your in some bubble.

Sure for circuit that gonna make great use of double sided (or more layers) and you
have devoted some time to its development, and maybe already some prototyping of
parts of it, yeah finally sending off a design to china looks like a no brain-er only then.

I use ferrite chloride. One good thing about it is that pc boards can float on it, enough surface tension, this produces a cleaner/faster etch.

Still, problem when i run out of the quantity i have, where to now get more ? jaycar no longer sell it.
ammonia persulphate ? yeah i used it in distant past, not so thrilled with it.
been thinking the muriatic acid thing, but some comments above not really encouraging, lol

[golden_labels]

FFS your in some bubble.

The bubble is called “living in United States and earning United States wage”. That’s probabilistic, so of course there are similar people elsewhere, but the further away one moves from US, the more unrealistic that solution becomes.

[jpanhalt]

I use ferrite chloride. One good thing about it is that pc boards can float on it, enough surface tension, this produces a cleaner/faster etch.
Still, problem when i run out of the quantity i have, where to now get more ? jaycar no longer sell it.

By far the greatest use of ferric chloride is in water treatment.  A quick check showed that is still the case in Australia. (Aluminum chlorides are also used.)

It appears to be available from Element14 (https://au.element14.com/c/chemicals-adhesives/ferric-chloride), and the price for 4L is not unreasonable.  Amazon may be another source.  Barrel quantities are quite cheap.  If you buy the solid, I recommend the hexahydrate (which is most common).  It does not evolve much heat on dissolving.

[CatalinaWOW]

OK.  I'm in a bubble.   But I think if you add up the costs of tanks, bubble pumps, chemicals, blank boards and other supplies depending on which process you use you will find that the savings from making your own are not so great.  Unless you are fortunate enough to live somewhere where you can get surplus items, not pay postage on those items and so on.  Or you live in a different kind of bubble where you already own precision drills, exposure frames and many other tools.  Don't forget to include the cost of less than 100% yield, which is common in home built boards.

With a little thought you can reduce the effective cost of the chinese boards.  No, most people don't need five copies of their circuit card.  But if you arrange your board right you can have an amplifier section, an H-bridge section, a microcontroller section and perhaps other blocks, all of which can be used in other projects.  This is just one example, there are many others.

Finally, for me avoiding the need to drill holes and the simplification of having two or more layers to perform layout is worth a bit of extra expense.

[Siwastaja]

Another bubble would be if sharing the facility with others is possible. Then you'll be motivated to invest more into the process.

The club of electronic students at the university I attended to was highly useful, and I was able to tune the PCB process there. Although I made quite a lot of boards, it sure did help dozens of others made boards, too. I'd say on average 1-3 boards was made per day, which is a lot yearly.

We finally had a CNC drill, through hole plating process and soldermask process. With dry film photoresist + laminator and heavily agitated cupric chloride tank, plus some stock of ½oz clad for more demanding boards, resolution and yield was just excellent; I made some highly integrated FPGA boards with 6/6 mil rules, and they were just perfect, but of course suffered from being limited to 2 layers.

Many times I went from an idea to CAD, then after 1 hour in CAD and another hour in manufacturing, I had a finished PCB. This was faster than working with soldered breadboards where you need to cut traces and solder tiny wires on at a time.

But I haven't been active there since 2015. Probably the process is still running because cupric chloride in a large (10 liters or so?) tank only requires adding HCl every 500-1000 boards, and probably ditching half of the etchant after 10000 boards or so; I don't know because I never did see the need for latter.

But we had compressed air and a proper fume hood available from the start.

[free_electron]

FFS your in some bubble.

The bubble is called “living in United States and earning United States wage”. That’s probabilistic, so of course there are similar people elsewhere, but the further away one moves from US, the more unrealistic that solution becomes.

/pedantic mode on/ china is about as far away from the us as possible... and they get it even cheaper cause they don't have to pay international shipping !

have you seen the cost of bare copper clad these days ? it is three times the price of a board made in china.
a 10x8 inch is 15 $ at digikey.

and those are not even photosensitive !
if you want them photosensitive : a 6x4 (roughly eurocard) is 10$
by the time you got etchant and developer you just lost your money.

developer : draino works in a pinch but you are better off with the clean powder

i'm a bit shocked at the prices. when i was a kid (16 years ... fff that's 35 years ago) a eurocard , presensitized from Bungard (german brand, excellent quality fiberglass copper clad) was like 2 $ ...
i've made many boards with that stuff. i used to buy double eurocard size. i even had a pcb guillotine...
i made a custom acrylic etch tank and used ammonium persulfate. aquarium heater , air bubbler...

before that : decon-dalo pens and dry-rub transfers (mecanorma and radio shack) on phenolic boards.
i had hundreds of round pcb's that came from local TV manufacturer. They were the cutouts from the large boards in the tv. The hole where the neck of the picture tube has to go through. single sided, phenolic with bare copper.
My favorite layout tool back then ( being a 8 year old.. ) was an american 1/5 inch grid notebook and a mechanical pencil... the grid was easy to draw ic sockets. resistors,diodes were 3 grid spaces... caps were 2 spaces (those wima 10mm pitch caps) or 1 grid.
Then i got my first pc and .. smartwork (through school) ! and in 1988 : protel easytrax 1.61. two years later at work we got autotrax and protel for windows.  the rest is history.

I Made my negatives using Agfa Litex film (x-ray film)
Print it on fotopaper using an inkjet : contact transfer to litex. Develop film using photo developer and fixer.
That was really BLACK !
You had to reverse the film (litex inverts the image) . I got a process where i would take the still wet first exposure , put a new sheet in contact, se a squeegee to remove as much water as possible from in-between and re-expose. i could remove parallax problems . The initial exposure would make the opening from trace to pad a but due to light leakage. ( sensitive side away from original print so you use the thickness of the litex film to bleed light: induce parallax)
Then sensitive to sensitive transfer (no parallax).

Haven't etched a board  since iteaadstudio and seeedstudio started offering boards. now pcbway and jlcpcb ...

[tooki]

FFS your in some bubble.

The bubble is called “living in United States and earning United States wage”. That’s probabilistic, so of course there are similar people elsewhere, but the further away one moves from US, the more unrealistic that solution becomes.

You think the US is at the top of the list of wages? 
As an American, lemme tell you: while the mathematical average (mean) income in USA is pretty high thanks to the insane incomes of the top 0.01%, the median income is significantly worse. Many countries fare better, and the high cost of living in USA, relative to income, is a serious problem.

But yeah… whether USA or Switzerland, the cost of raw materials, not to mention the value of the time it takes to do it, makes DIYing PCBs here economically silly compared to ordering from China. You do it locally (whether DIY or from a local PCB manufacturer) when the priority is speed.

[Old Printer]

Another consideration...since I have Co2 laser engravers and flatbed UV printers at my disposal I have tried to use those to make DIY PCB's. With the laser you need to coat the copper with some sort of resist, like spray paint etc, then burn away what needs to be exposed to the enchant. With the UV printer you print the resist, a heavy coat of black ink, then off to the enchant. I was using peroxide/HCI as Radio Shack is no more and that is where I got my ferric chloride. The main problem I had was the peroide/HCI would lift off any resist coating, either the UV ink or anything I tried to use with the laser. I finally gave up until I ran across a source for ferric chloride and tried again. The ferric did not disturb my DIY resists like the perox/HCI did and the boards came out quite nice.