17
\$\begingroup\$

I've been making a few hobbyist PCBs at home and note that the photoresist developer and ferric chloride etch solutions are both pretty nasty chemicals that come with all kinds of warnings.

So I've been extremely careful

  • Wearing safety goggles while dealing with them.
  • Wearing disposable gloves at all times and throwing them away afterwards.
  • Wearing old heavy clothes so that a splash won't immediately touch skin.
  • Rinsing everything with large amounts of water afterwards.

My question is just how much of this is needed and how "nasty" are the chemicals?

I shall continue to wear goggles as they are no trouble and there seems no point risking eye damage however unlikely.

But what about the rest? If I get a single drop of the photoresist developer or feric chloride on me (and wash it off quickly) is that likely to be a huge problem? If I've rinsed something badly and there is still a trace of diluted chemical on there is that harmful? For example I'm throwing away my disposable gloves every time. I don't believe I get significant amounts of either on there but I'm not taking any risks. I could always wash them and use them again but they are cheap so I don't. But what risk is there that a few drops were on there and didn't get entirely removed by washing and they touched my skin?

I'm of course not looking for someone to say go ahead, it's fine :) I'm just looking to know what the risks actually are so I can be an appropriate level of careful rather than over the top careful which I am now, which frankly can be a pain.

\$\endgroup\$
  • \$\begingroup\$ Thanks for all the answers, +1 for them all :) Was hard to know which one to accept, they were all good. but that one seemed popular and answered my question most directly I suppose. \$\endgroup\$ – John Burton Jul 16 '10 at 14:49
16
\$\begingroup\$

The developer is simply a dilute alkali, I use 12g of NaOH in a litre of water. It's quite safe but don't get it in your eyes and wash it off if you get it on the skin. Ferric chloride is quite safe, just wash it off if it gets on the skin. I always wear rubber gloves, both for protection and so that I can use hot etchant with manual agitation (I put the etchant and board in a small container in an old washing-up bowl with about 1" of just boiled water in it).

I've been making my own PCBs at home for about 40 years, using ferric chloride mostly. The only accident I've had that could have been serious was when I was walking across the room with an open bottle of conc. HCl in my hand, tripped, and a little splashed on my face next to an eye. I thought it might have got in the eye, but the fumes were bad enough. I immediately put my face under a tap and flushed the eye out for several minutes. It was sore for a few hours, but there was no damage.

\$\endgroup\$
  • \$\begingroup\$ Good answer and I agree completely. The basic point in working with these chemicals is to prevent long exposure to them. Wash it off if spashed on skin and perhaps an eye shower is good to have around if you are particularly worried, but I find that a tap (as mentioned in the article) works fine (although I only had to use it once and that was with the particularly dangerous chemical substance called deoderant.) \$\endgroup\$ – Wouter Simons Jul 27 '10 at 5:28
  • \$\begingroup\$ How do you safely dispose of the wastage? \$\endgroup\$ – deostroll Dec 2 '18 at 1:57
  • \$\begingroup\$ I no longer make my own boards - easier to buy them from China - but I used to use the etchant indefinitely by adding hydrogen peroxide and HCl occasionally. No wastage! It gradually becomes cupric chloride, which is an etchant in its own right. \$\endgroup\$ – Leon Heller Dec 2 '18 at 17:52
8
\$\begingroup\$

For a definitive answer, consult the Material Safety Data Sheets (MSDS) associated with the products you are using. According to USA laws, at least, the manufacturer is required to make MSDSs available on request. Simply doing a Google search with the product name and "msds" will usually get results.

An MSDS is a bit difficult to read, and there is no real standard format, but you should be able to find out what you need for protective clothing, eyewear, and the like. Also included are many other topics, such as fire and explosion data, and HAZMAT transportation information.

Going beyond the MSDS; doing a search of the primary ingredients listed should turn up good data if you're interested in long-term effects such as carcinogens and the like.

I hope this helps.

\$\endgroup\$
  • 1
    \$\begingroup\$ Good answer. But doesn't really quantify how much should I worry if I get a drop on me and wash it off quickly. \$\endgroup\$ – John Burton Jul 15 '10 at 13:05
  • \$\begingroup\$ True, it is somewhat limited. I would defer to some of the more experienced folks here for that situation. Personally, though, it's probably better to have protective gear and not need it, rather than the other way around! \$\endgroup\$ – Jesse Jul 15 '10 at 13:50
  • 1
    \$\begingroup\$ The MSDS quantifies that. It goes without saying that you familiarize yourself with the MSDS as part of normal precautions in handling the material, not during an accident. \$\endgroup\$ – Harper - Reinstate Monica Feb 3 at 2:58
7
\$\begingroup\$

Personally, I'm pretty cavalier. But, don't get ferric chloride on your clothes, it never comes out.

\$\endgroup\$
7
\$\begingroup\$

I'd agree with Jesse, go to the official government stuff for details - if you're worried.

But.....from purely an experiential standpoint -

To be honest I've had ferric chloride on my skin more times than I'd care to mention, however I do use thick rubber gloves and ventilation whilst etching.

When I get it on my skin I'll just stop.....pop my PCB in a sink/bucket of water (if i'm etching caveman stye) remove gloves, then get plenty of water on the area and give it a good wash off.

A while ago - I was alone at home etching and I got a splash of ferric chloride in my eye!....didn't have time to save the board...but got to the kitchen sink and put my eye under the tap whilst blinking franticly.

My eye was fine afterward, but it could have been worse (may have tripped and hurt myself!)...so next time I'm etching alone I'll take extra precautions with eye protection!

\$\endgroup\$
5
\$\begingroup\$

My worst chemical mishap was probably when I was supergluing some things together and a part slipped and splashed little glue droplets around the desk and me. My first thought was, did I really manage to make drops of flying cyanoacrylate and what if one had hit my eye. I still don't wear goggles while etching or even gloves (I use tweezers, wire, and cotton swabs etc to manipulate the parts), though I do in a lot of other things. I tend towards paranoid carefulness in general otherwise.

I think the important thing in dealing with chemicals is general hygiene. Don't let the chemicals touch anything you haven't intended to contaminate. Always keep a separate spoon/measure/jar/tweezers/spoon for each chemical etc. Store things in appropriate ways, label things and keep foodstuffs well away from toxic things. Know the particular ingredients and their behaviour as well as you can.

\$\endgroup\$
4
\$\begingroup\$

An environmental concern is copper ions in the used etching fluid. It's quite likely that down the sink, NaOH and even ferric chloride are not as nasty as copper salts. Care should be taken when disposing of old fluid.

\$\endgroup\$
2
\$\begingroup\$

A year ago, I would have said "Anything that can dissolve copper must be a dangerously strong acid".

However, salt and vinegar are generally considered harmless enough to eat and drink, and I've recently come across people who claim mixing the two makes an acid strong enough to etch copper-clad circuits:

Salt and vinegar etching, also etching FabFM radio smt pcb with Salt and Vinegar.

Perhaps it would be less hassle to use salt and vinegar, even if it etches boards a little more slowly, rather than spending a lot of time and emotional stress being over-the-top careful and worried.

\$\endgroup\$
1
\$\begingroup\$

as far as the toxic nature of these chemicals, the only thing you really need to worry about is the resulting copper chloride. Copper is quite toxic and should definitely not be ingested. That's not too hard, though, and getting a bit of it on your skin isn't terribly dangerous. That's about as bad as it gets.

\$\endgroup\$
1
\$\begingroup\$

From my own experience, the ferric chloride is something you have to be very careful to avoid damaging something near (like furniture). You have to store it very well, preferably in an airtight container inside other airtight container. Its evaporation or spills will stain practically anything it's near of. Be especially careful about aluminium objects, it reacts instantly with them corroding completely and liberating gas (if you drop a piece of aluminium in the ferric chloride solution it'll look like an alka-seltzer tablet).

When in contact to the skin it'll not burn or make damage (provided you wash instantly), but it'll stain (to the point it'll take days to vanish). If you buy it in powder form and dillute yourself, do it in a ventilated place since it'll release gases when dilluted with water.

\$\endgroup\$
  • 1
    \$\begingroup\$ Oxalic acid removes ferric chloride stains. \$\endgroup\$ – Leon Heller Aug 30 '10 at 3:17
  • \$\begingroup\$ Is it safe to use/store oxalic acid just for that? Its safety sheet looks a bit scary. \$\endgroup\$ – fceconel May 3 '11 at 21:31

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.