PCB etching health hazards - Page 1
Forum section: electronics / general

author: Unknown
author_rank: Unknown
timestamp: February 24, 2017, 05:00:27 am
content: I am trying to etch PCBs in a dorm room, but before I start preparing vats of etchant I was hoping to learn a little more about how volatile the various etchants are and how dangerous their fumes are. My plan was to etch the PCBs outside (using ferric chloride as the etchant), then keep the leftover etchant in a sealed glass pyrex container in my room. The problem is that I don't know much about chemistry or what kinds of gasses might build up in my dorm without me knowing. I know that under the right circumstances this stuff can produce chlorine gas, so I want to make sure I get rid of my ignorance before it gets rid of me!My questions boil down to:1.) How volatile is ferric chloride/do you think a pyrex container sealed in a plastic gallon bag would be safe to keep in a room where you sleep?2.) Are there other etchants that might be less hazardous (if ferric chloride is cause for concern).

author: jh15
author_rank: Frequent Contributor
timestamp: February 24, 2017, 05:40:45 am
content: Good thread to continue. Doesn't it cause instant blindness if splashed in eyes? Problems with using it in my past, radioshack, etc is it stains everything. just bought some alternative from Amazon, ammonium persulfate with its own issues.

author: richardlawson1489
author_rank: Regular Contributor
timestamp: February 24, 2017, 06:40:19 am
content: Have you heard about etching PCB with vinegar? I think that would be better option.

author: george.b
author_rank: Frequent Contributor
timestamp: February 24, 2017, 02:31:56 pm
content: Quote from: MosFett on February 24, 2017, 05:00:27 am1. FeCl3 is not volatile. It may release HCl under certain circumstances, but is stable when adequately stored. If the container isn't amber glass or opaque, I would store it away from light.2. Yes, there are other etchants. I've been fine using FeCl3 since I was 15, though.Ferric Chloride Hexahydrate MSDS:http://www.sciencelab.com/msds.php?msdsId=9924034I wouldn't worry about storing it in a sealed container in your sleeping room.

author: elecman14
author_rank: Unknown
timestamp: February 24, 2017, 02:47:32 pm
content: Your college will probably not be to happy to learn you are storing any sort of acid in your dorm room no mater how harmless. If you are doing something weird outside your dorm it is probably only a matter or time before it attracts attention of someone who cares. Even though it is mostly safe I would look into a more appropriate area to do your etching. For example go talk to a chemistry or EE professor. They can probably find a more appropriate storage area for you and maybe even a better ventilated area (fume hood) to do your etching. I did something similar in college when I was de-capping ICs.

author: Bud
author_rank: Super Contributor
timestamp: February 24, 2017, 04:03:27 pm
content: I lived in a dorm room for several years, i etched boards and stored ferric chloride in a glass jar where i lived, fast forward several decades later i am still alive.

author: Fgrir
author_rank: Regular Contributor
timestamp: February 24, 2017, 06:35:51 pm
content: Quote from: Bud on February 24, 2017, 04:03:27 pmI could personally make quite a list of things that fit that sentence that I wouldn't recommend todayWith my own daughter in college now I can say that the world has changed quite a bit towards paranoia. Safe or not I wouldn't want to be in your shoes when you have to explain to your college authorities what that nasty brown fluid you were hiding in your dorm room was for after you spill it or someone takes a swig to see what it tastes like.

author: james_s
author_rank: Super Contributor
timestamp: February 24, 2017, 07:37:08 pm
content: The thing I hate about FeCl is that it stains *everything* if even a little gets on anything. Also anything that etches copper will corrode the hell out of just about anything metal nearby, even stainless. I use HCl mixed with a bit of hydrogen peroxide and recharge it with a bit of peroxide before use. It forms a green liquid that turns brown as it etches, Cupric Chloride as I recall.

author: Berni
author_rank: Super Contributor
timestamp: February 24, 2017, 08:45:14 pm
content: Ferric chloride is not very volatile or particularly harmful, no gasses or smell comes off it but it does leave horrible yellow stains on pretty much anything it comes in contact with. So make sure you protect any furniture you do it on.Personally the etchant i liked the most was sodium persuflate. Comes in a white crystalline form (looks like salt) and it just gives of oxygen as its working, no nasty smells, works faster than ferric chloride too while not leaving any dirty stains. Since its clear and turns slightly blue as its used means you can also easily see the progress trough the liquid.The one you really want to avoid is using HCl acid mixed with peroxide. While it does etch much faster than most methods (can etch it literally in a minute) but also gives off lots of nasty fumes that form in to acid when they come in contact with moisture. This includes your eyes and lungs and since the air contains moisture it also leaves acid on everything else, cording metal objects near by. The stuff absolutely can NOT be used indoors unless you do it in a fume hood.

author: james_s
author_rank: Super Contributor
timestamp: February 24, 2017, 08:56:23 pm
content: Yeah I do it out on the deck on a sheet of plastic. I keep a container of water mixed with baking soda nearby in case of a spill and I wear goggles and gloves.

author: bsudbrink
author_rank: Frequent Contributor
timestamp: February 24, 2017, 09:08:20 pm
content: If you're enough of a go-getter that you're etching your own PCBs at college, then I'd think you would be able to get the attention of a CompSci or EE professor who could help you out. They could probably get the Chem department to give you a little space under a fume hood in a lab somewhere. Maybe even a key to it. Of course, I went to college a long time ago. Maybe things have changed more than I think.

author: Unknown
author_rank: Unknown
timestamp: February 25, 2017, 12:29:54 am
content: Thank you all for all the great advice! I didn't know about vinegar etching so I went ahead and gave that a try, but I'll probably give the other techniques a go at some point as well. It's good to know there are a lot of good options out there.I suspect I can't get lab space through my college though because my school doesn't have an EE program and thus I don't expect it to have much interest in my electronics projects. I might see if I can work something out with a professor, but until then I'll just be careful etching in my dorm.

author: james_s
author_rank: Super Contributor
timestamp: February 25, 2017, 12:35:47 am
content: One thing to keep in mind regardless of what etchant you use is disposal. Don't dump the used etchant where it may end up in lakes/streams/ocean, copper is highly toxic to many forms of marine life and whatever you etch with will become full of dissolved copper.

author: george.b
author_rank: Frequent Contributor
timestamp: February 25, 2017, 01:33:35 am
content: Quote from: james_s on February 24, 2017, 07:37:08 pmNot just metal - it'll quite happily eat up granite as well. Ask me how I found that one out

author: orin
author_rank: Frequent Contributor
timestamp: February 25, 2017, 02:13:26 am
content: I use this stuff:http://www.mgchemicals.com/products/prototyping-and-circuit-repair/prototyping/ferric-chloride-415There's a very long MSDS there.I don't worry about using it. FWIW, here is their neutralization procedure:Q. How do I dispose of Ferric Chloride Solution?A. There are two ways:Contact your local Hazardous Waste Disposal CompanyThe solution must not be put down the drain because of residual copper ions left in it. To make it safe for disposal, you can add sodium carbonate (washing soda) or sodium hydroxide to it to neutralize it, until the pH value goes up to between 7.0 and 8.0, testing it with indicator paper. Copper will be deposited as a sludge. Allow the sludge to settle, pour off the liquid, further dilute it with water and then it can be poured down the drain. Collect the sludge in plastic bags and dispose of it as required by your local waste authority.

author: hcglitte
author_rank: Regular Contributor
timestamp: February 25, 2017, 09:36:00 am
content: I'm curious to know why you would want to etch your own boards, when you can get 10 pcs of 100x100 mm^2 for 18 USD including shipping nowadays.Faster with DHL, and not too much more expensive.The reasons I can imagine are:1. Educational (but wouldn't it be better to use this time for something of more value, like the actual design?)2. You need a board "today" (very good argument)PS: I etched my own boards in the late 90s when I was a teenager, as this was the only viable solution for hobbyists back then.

author: Refrigerator
author_rank: Super Contributor
timestamp: February 25, 2017, 09:57:44 am
content: I personally use copper chloride to etch my boards because i couldn't get my hands on anything else.You basically mix HCl with some peroxide and feed copper until it's a deep green.HCl + peroxide is a good etchant in itself but it's stinky and becomes weaker with time.But copper chloride not only makes itself but becomes stronger the more oxygen it absorbs from the surrounding air, it's also not as stinky ( smells like dust from your pc ).I found storing it is not too difficult since it only eats metals, plastic and glass containers are ok.It also doesn't stain as much as ferric chloride does, all my plastic trays that had copper chloride in them cleaned up without a problem.

author: james_s
author_rank: Super Contributor
timestamp: February 25, 2017, 06:44:23 pm
content: That's what I use too, but I thought it was silly to just feed it copper when what you're etching is copper. Simply etch a few boards in the HCl+H2O2 and you've fed it all the copper needed and it quickly turns into the dark green liquid.

author: Unknown
author_rank: Unknown
timestamp: February 25, 2017, 07:27:31 pm
content: Quote from: hcglitte on February 25, 2017, 09:36:00 amSpeed and because I typically will only need one or two copies of each board. Speed is especially important because I figure I will botch enough designs (especially because I am new to Eagle) that it would take a lot of cash and year or so to get one simple design made correctly just because I will go through so many failed attempts. This way I can learn a little faster and hopefully save a few bucks through only making as many boards as I need.

author: james_s
author_rank: Super Contributor
timestamp: February 25, 2017, 07:45:08 pm
content: I etch my own boards when I want a one-off like an adapter for a SMT IC I want to prototype with, or some little doohickey I only want one of. I can go from finished layout to an etched board ready to build in less than an hour versus waiting 3 weeks to get boards from China. It's also handy for prototypes, I can etch a board and make sure the circuit works as expected, then tack on any changes needed, polish up the layout and send it out for production. It can save a huge amount of time over waiting for each iteration, even if I were to use expedited shipping.Also it's kind of fun to build something completely from scratch with a board etched at home. It's a bit like a hand made quilt or pillow. Why would anyone sew up a pillow at home when they can go buy one for $8 at Walmart? Because it's fun to make stuff.

author: bsudbrink
author_rank: Frequent Contributor
timestamp: February 27, 2017, 05:31:19 pm
content: Quote from: hcglitte on February 25, 2017, 09:36:00 am3. Reproduce a project in an old magazine.4. IT'S FUN!Quote from: hcglitte on February 25, 2017, 09:36:00 amWhy'd you have to remind me how old I am? I etched my own boards in the _1970s_ when I was a teenager, as this was the only viable solution for hobbyists back then. (The forum needs a "graybeard" emoticon... "Get off of my lawn")

author: Cerebus
author_rank: Super Contributor
timestamp: February 27, 2017, 09:06:52 pm
content: Quote from: bsudbrink on February 27, 2017, 05:31:19 pmI generally find that I don't need other people to remind me how old I am, just climb some stairs and my knees do the job. As to the emoticon - a picture of Bob Pease?

author: S13
author_rank: Regular Contributor
timestamp: February 28, 2017, 02:35:29 pm
content: I only have negative experience with HCL and peroxide. That stuff is just way to corrosive imo. Ive done etching both outside and in a tool shed. I can tell you the fumes are not something to mess around with. There were some tools and blank metal sheets in the vicinity of the HCL (a couple of feet away) in the shed, and only a few hours later i noticed a lot of the tools and huge patches of sheet metal were highly corroded. Stupid mistake i guess... Well you learn the hard waySo i cannot imagine using this stuff inside your house safely.At my school we used ferric chloride, which was actually comparable in speed but much less dangerous (though watch out for staining like mentioned before).But if it were up to me i would look in to PCB prototyping services. Ive recently switched from home etching to elecrow (but there are lots of others as well) and cant believe the low prices they charge. It does take the fun out of etching and it takes a bit longer (like 2-3 weeks or something), but its cheaper, less dangerous en you get a higher quality board in the end. So that might be something to consider as well?

author: nctnico
author_rank: Super Contributor
timestamp: February 28, 2017, 03:41:15 pm
content: My father (well versed in chemistry) let me use FeCL when I was a kid (12 or 13) and etch boards in the kitchen. As others noted FeCl stains are permanent but other than that it is quite safe.

author: CraigHB
author_rank: Regular Contributor
timestamp: February 28, 2017, 06:33:28 pm
content: Yeah that stuff is like ink and it even damages stainless steel. The peroxide stuff seems like a better solution. I haven't tried it yet, but I probably will when my current supply of FeCl runs out.I still etch boards sometimes. Mainly it's for simple one-offs where I want something real quick. There's always a week or two lead time on fabricated boards which is the only reason I don't use them for everything. Though they're so cheap now anything complex at all I send out. There was a time not so long ago where any fab was cost prohibitive on your own dime so you had to etch your own boards for everything pretty much.

author: tpowell1830
author_rank: Frequent Contributor
timestamp: February 28, 2017, 06:53:19 pm
content: I have always used FECL for one or two offs for testing. I found the best way to etch is in a zip lock bag and hold the bag under hot running water to speed up the process. Roll the bag gently back and forth under the hot water stream for even distribution. After done, remove the board and zip up the waste leftover and then can be easily disposed. Sometimes I simply reused the leftover etchant until it quit working. Either way, the ziplock bag was so easy. If you do this over a sink, when you remove the board to rinse off, aluminum foil under the area will prevent staining permanent items such as the sink, fixtures etc. If you have concerns about fixtures, wrap with the foil. Keep running the water for a time to completely flush the stuff away.

author: Cerebus
author_rank: Super Contributor
timestamp: February 28, 2017, 07:30:50 pm
content: Quote from: tpowell1830 on February 28, 2017, 06:53:19 pmRather a bad idea to mix as reactive a metal as aluminium with a powerful oxidizing agent - under the wrong set of circumstances I can see that becoming rapidly exothermic. Stick to a polythene sheet or similar.

author: james_s
author_rank: Super Contributor
timestamp: February 28, 2017, 11:15:22 pm
content: I wouldn't worry about exothermic reactions with a sheet of foil, but I certainly would be careful about what chemicals are being used. I found out when I was about 12 that aluminum foil in HCl releases copious amounts of hydrogen sulfide. The area around my grandmother's garden shed reeked like the worst rotten egg farts I've ever smelled. The stuff is fairly toxic in high doses too.

author: BradC
author_rank: Super Contributor
timestamp: March 01, 2017, 02:31:21 am
content: Quote from: james_s on February 28, 2017, 11:15:22 pmWhere did the sulfur come from?

author: Ian.M
author_rank: Super Contributor
timestamp: March 01, 2017, 03:23:08 am
content: Quote from: BradC on March 01, 2017, 02:31:21 amHe probably mis-remembered it and used battery acid.Its a pity theSeno Etch in a Bagkit isn't readily available outside Europe. Its the least mess and fuss you'll see for FeCl etching systems, and uses a small volume of FeCl solution compared to etching tanks. Instructions here:http://www.megauk.com/datasheets/5116_Data_Sheet_Ferric_Chloride_Etch_in_bag_Kit_(600-017).pdfIf you've got access to a bag sealer with a supply of extra heavy polythene 4" lay-flat tubing, you could easily replicate the Seno bags, double sealing the bottom and usinghttps://www.anylock.com/for the clips.Neutralising spent FeCl for disposal has been previously discussed - The essential factor is to make the solution alkaline to precipitate out the copper as salts with minimal solubility. Probably the best bet is to use a 50/50 mix of powdered chalk or limestone and cement to have similar results to the Seno neutraliser.

author: james_s
author_rank: Super Contributor
timestamp: March 01, 2017, 05:47:41 am
content: Whoops! You're right of course, I was trying to get hydrogen which is what you get by putting aluminum in HCl. The particular acid I used turned out to be H2SO4 and that's what released the hydrogen sulfide. It was an ancient bottle of drain opener as I recall.

author: technotronix
author_rank: Regular Contributor
timestamp: March 07, 2017, 02:25:10 pm
content: Anyone tried PCB etching vinegar? Is it right way?

author: BradC
author_rank: Super Contributor
timestamp: March 08, 2017, 06:57:45 am
content: Quote from: james_s on March 01, 2017, 05:47:41 amFor future reference, sodium hydroxide and aluminium is a much nicer way to get hydrogen. HCl tends to lose gaseous HCl as it reacts and heats up, so you get Hydrogen & HCl in that mix with the HCl quickly migrating to wherever your most expensive metal tools are stored and causing havoc. NaOH is easier to get hold of (generally in the cleaning aisle of the supermarket) and is relatively easier to put up with. Just don't get it on your hands as it'll start to saponify your fatty cells, whereas HCl just stings a bit.Back on topic, I used to etch with FeCl by putting a bit of it in a zip-loc bag with the PCB and sloshing it around in a hot water bath. Take the PCB out, zip the bag back up and dispose of the lot. I used so little of the liquid a bottle lasted me years.Now I have access to decent concentration H2O2 I use that and HCl (outside in a well ventilated area) if I'm in a hurry, or CuCl if I'm not. The H202/HCl mix winds up in my CuCl bottle at the end of the day anyway. Again, with good strength H202 and HCl you need so little to do a quick etch it's easy to deal with.Here HCl is available in most places in nice clean pool acid form. ~30%. About $17 for 4 Litres.

author: james_s
author_rank: Super Contributor
timestamp: March 08, 2017, 09:28:35 pm
content: Quote from: BradC on March 08, 2017, 06:57:45 amMaybe it was sodium hydroxide I was supposed to use, I don't actually remember, I think I was about 12 at the time. Now if I wanted to get hydrogen I'd just go to Praxair and buy a tank of it.