Local disposal of used PCB etching solution

[Martyn Welch]

Hi Guys,

I'm currently in the process of kitting my self out to etch some PCBs at
home (I'm fed up with using strip board, the thought of laying out a
project on strip board is enough to stop me before I start).

I've found tonnes of information about making the PCBs on the web, what I
haven't found yet is any localised information about the disposal of the
used etchant. Pouring it down the drain is not an option as it is hazardous
waste (it has dissolved copper in it and is an acid for a start...)

If you produce PCBs at home, what do you do?

Martyn

[Guy Burton]

Keep it in a pot until it burns through the sides and melts the carpet...

[Rushden Rotaract Webmaster]

not sure if it is the "right thing to do" but I was told to make it into
a brick with plaster paris and bin it

[Adrian Godwin]

If you use cupric chloride as an etchant, the waste product is more etchant, which you can use to fill up someone else's tank.  See http://wiki.hackspace.org.uk/wiki/Cupric_chloride_etchant


BTW, you're welcome to come and use my etch tank if it isn't too far to come (Bedford). Though I do appreciate it's nicer to have your own kit (which is why I've got mine!)

-adrian

[Martyn Welch]

On 13/01/11 17:20, Adrian Godwin wrote:

If you use cupric chloride as an etchant, the waste product is more etchant, which you can use to fill up someone else's tank.  See http://wiki.hackspace.org.uk/wiki/Cupric_chloride_etchant

I can across a web site talking about Cupric Chloride today and would like to take this route, though a few quick google searches didn't throw up and obvious suppliers or ready made solution and was considering using Sodium Persulfate initially until I had the basics down.

I was looking at setting up a bubble etch tank anyway, which from the description I read would be ideal for Cupric Chloride as I'd effectively be regenerating it a bit as I ran the bubbles.

I assume that you use Cupric Chloride, am I right in thinking the by-product of the regeneration is copper?

BTW, you're welcome to come and use my etch tank if it isn't too far to come (Bedford). Though I do appreciate it's nicer to have your own kit (which is why I've got mine!)

Thanks for the offer! I think in the long run I want to setup my own, but would very much appreciate a few lessons from someone already versed in producing PCBs at home.

Martyn

[Rushden Rotaract Webmaster]

I was once told that my 2 L tank would last me ages so I'd not fret about what to do with it if your only doing a few PCB's now and then, you won't have an industrial scale disposal problem on your hands

[Adrian Godwin]

On Thu, Jan 13, 2011 at 6:36 PM, Martyn Welch <mar...@welchs.me.uk> wrote:

 

I can across a web site talking about Cupric Chloride today and would like to take this route, though a few quick google searches didn't throw up and obvious suppliers or ready made solution and was considering using Sodium Persulfate initially until I had the basics down.

Not a bad idea.

 

I was looking at setting up a bubble etch tank anyway, which from the description I read would be ideal for Cupric Chloride as I'd effectively be regenerating it a bit as I ran the bubbles.

I assume that you use Cupric Chloride, am I right in thinking the by-product of the regeneration is copper?

No, it's cupric chloride ! To be fair, you do have to add a little HCl occasionally too. But actually I set the tank up because I had the opportunity to buy it cheap and wanted to do the job properly after making half-hearted attempts in the past. I haven't used it enough yet to have any waste products.

I made it with conc HCl, H2O2 and copper wire. pH and density measurement are very helpful but can be arranged very cheaply.
 

BTW, you're welcome to come and use my etch tank if it isn't too far to come (Bedford). Though I do appreciate it's nicer to have your own kit (which is why I've got mine!)

Thanks for the offer! I think in the long run I want to setup my own, but would very much appreciate a few lessons from someone already versed in producing PCBs at home.

See above .. I'm not really very good at it though i do have some reasonable kit now. I envy the guys at the london space - especially Charles, who started making them 6 months ago and now knocks them out in a few minutes using minimal equipment (laser printer, UV box, simple rocking tray with ferric chloride).

 

-adrian

[Martyn Welch]

On 13/01/11 20:30, Adrian Godwin wrote:

On Thu, Jan 13, 2011 at 6:36 PM, Martyn Welch <mar...@welchs.me.uk> wrote:

 

I can across a web site talking about Cupric Chloride today and would like to take this route, though a few quick google searches didn't throw up and obvious suppliers or ready made solution and was considering using Sodium Persulfate initially until I had the basics down.

Not a bad idea.

I've had a bit more of a read up about Cupric Chloride and it seems that it can be made with HCl, Scrap copper and Air:

http://members.optusnet.com.au/eseychell/PCB/etching_CuCl/index.html#Preparing_Cupric_Chloride_Etchant

So I might just bite the bullet and go straight to that. Just need to find somewhere to buy concentrated hydrochloric acid. Did you manage to source some locally?

 

I was looking at setting up a bubble etch tank anyway, which from the description I read would be ideal for Cupric Chloride as I'd effectively be regenerating it a bit as I ran the bubbles.

I assume that you use Cupric Chloride, am I right in thinking the by-product of the regeneration is copper?

No, it's cupric chloride ! To be fair, you do have to add a little HCl occasionally too. But actually I set the tank up because I had the opportunity to buy it cheap and wanted to do the job properly after making half-hearted attempts in the past. I haven't used it enough yet to have any waste products.

I made it with conc HCl, H2O2 and copper wire. pH and density measurement are very helpful but can be arranged very cheaply.
 

The site I mentioned above seems to have a good explanation of how to do that.

BTW, you're welcome to come and use my etch tank if it isn't too far to come (Bedford). Though I do appreciate it's nicer to have your own kit (which is why I've got mine!)

Thanks for the offer! I think in the long run I want to setup my own, but would very much appreciate a few lessons from someone already versed in producing PCBs at home.

See above .. I'm not really very good at it though i do have some reasonable kit now. I envy the guys at the london space - especially Charles, who started making them 6 months ago and now knocks them out in a few minutes using minimal equipment (laser printer, UV box, simple rocking tray with ferric chloride).

I'm thinking of taking the press-n-peel route initially so I don't have to deal with the UV box and developer. Might try with photo paper, but that seems like a bit of a faff.

Martyn

 

-adrian

[Adrian Godwin]

I've had a bit more of a read up about Cupric Chloride and it seems that it can be made with HCl, Scrap copper and Air:

http://members.optusnet.com.au/eseychell/PCB/etching_CuCl/index.html#Preparing_Cupric_Chloride_Etchant

So I might just bite the bullet and go straight to that. Just need to find somewhere to buy concentrated hydrochloric acid. Did you manage to source some locally?

Yes, the best bet is an old-fashioned hardware store. They usually have it in 500ml bottles (sometimes labelled as Spirits of Salt) by manufacturers such as Kilrock. Do NOT buy concrete cleaner from Wickes - it's weak and full of detergent. You may find they only have 2 or 3 bottles in stock. If you find someone with bigger bottles (they are available) you're doing well.

I got rather impatient trying to get it going on oxides alone. It took me the best part of a week even using conc H2O2 and doing titrations to avoid accidentally diluting it. you may have more patience ...

The site I mentioned above seems to have a good explanation of how to do that.

Probably the same one I used. Plastic syringes from ebay are a convenient way to measure samples for titration.
 

I'm thinking of taking the press-n-peel route initially so I don't have to deal with the UV box and developer. Might try with photo paper, but that seems like a bit of a faff.

Martyn

I always tried to avoid the photo route for the same reason. In the end I decided to stop mucking about and do what everybody else was doing. I may eventually find a better method but it's really not so bad.

-adrian

[Martyn Welch]

On 15/01/11 00:00, Adrian Godwin wrote:

I've had a bit more of a read up about Cupric Chloride and it seems that it can be made with HCl, Scrap copper and Air:

http://members.optusnet.com.au/eseychell/PCB/etching_CuCl/index.html#Preparing_Cupric_Chloride_Etchant

So I might just bite the bullet and go straight to that. Just need to find somewhere to buy concentrated hydrochloric acid. Did you manage to source some locally?

Yes, the best bet is an old-fashioned hardware store. They usually have it in 500ml bottles (sometimes labelled as Spirits of Salt) by manufacturers such as Kilrock. Do NOT buy concrete cleaner from Wickes - it's weak and full of detergent. You may find they only have 2 or 3 bottles in stock. If you find someone with bigger bottles (they are available) you're doing well.

After a bit more searching I discovered Toolstation (www.toolstation.com) who have stores through out the UK, including a newish store on St James Trade Park, stock Spirits of Salt in 500ml and 1l bottles. They are a 32% solution. The 1l bottle was £4.19.

I got rather impatient trying to get it going on oxides alone. It took me the best part of a week even using conc H2O2 and doing titrations to avoid accidentally diluting it. you may have more patience ...

If it saves me buying H2O2, I'm game. Tanks on order, better dig out some old copper cabling to strip down.

At least Sodium Hydroxide (needed for the titration and otherwise known as caustic soda) seems to be easier to get a hold of. I seems that Boots stock that as a drain cleaner.

The site I mentioned above seems to have a good explanation of how to do that.

Probably the same one I used. Plastic syringes from ebay are a convenient way to measure samples for titration.
 

I think I've got some spare from when I used to have an aquarium and used them to measure chemicals for the tank - I'll have to see if I can did them out.

I'm thinking of taking the press-n-peel route initially so I don't have to deal with the UV box and developer. Might try with photo paper, but that seems like a bit of a faff.

I always tried to avoid the photo route for the same reason. In the end I decided to stop mucking about and do what everybody else was doing. I may eventually find a better method but it's really not so bad.

It's the extra cost that's putting me off at the moment. If I generally get on with making PCBs at home with the press-n-peel, I'll consider the photographic approaches at a later date.

Martyn

[Martyn Welch]

On 15/01/11 16:31, Martyn Welch wrote:

On 15/01/11 00:00, Adrian Godwin wrote:

I've had a bit more of a read up about Cupric Chloride and it seems that it can be made with HCl, Scrap copper and Air:

http://members.optusnet.com.au/eseychell/PCB/etching_CuCl/index.html#Preparing_Cupric_Chloride_Etchant

So I might just bite the bullet and go straight to that. Just need to find somewhere to buy concentrated hydrochloric acid. Did you manage to source some locally?

Yes, the best bet is an old-fashioned hardware store. They usually have it in 500ml bottles (sometimes labelled as Spirits of Salt) by manufacturers such as Kilrock. Do NOT buy concrete cleaner from Wickes - it's weak and full of detergent. You may find they only have 2 or 3 bottles in stock. If you find someone with bigger bottles (they are available) you're doing well.

After a bit more searching I discovered Toolstation (www.toolstation.com) who have stores through out the UK, including a newish store on St James Trade Park, stock Spirits of Salt in 500ml and 1l bottles. They are a 32% solution. The 1l bottle was £4.19.

I got rather impatient trying to get it going on oxides alone. It took me the best part of a week even using conc H2O2 and doing titrations to avoid accidentally diluting it. you may have more patience ...

If it saves me buying H2O2, I'm game. Tanks on order, better dig out some old copper cabling to strip down.

At least Sodium Hydroxide (needed for the titration and otherwise known as caustic soda) seems to be easier to get a hold of. I seems that Boots stock that as a drain cleaner.

Ok, I've got a bit further with this now :-)

I think I have my etch tank setup. After stripping down quite a few metres of old coax cabling I had the nearly 300g of copper I needed for the volume of solution in my tank. My tank is about 2.3L by the time I have put the heater in it.

I managed to kick-start the process with just oxides. It took a few days for the process to really kick in, but over one night the solution turned pitch black (so thick that I couldn't shine a torch through the 1-2" thickness of the clear sided tank. I could just about see some of the copper against the side of the tank, which slowly disappeared over a few days, then the solution slowly turned emerald green. I think this is the colour it should be (anyone know?).

I haven't managed to test the concentration yet, I need to get some accurate scales to mix up the sodium hydroxide for the titration.

I was hoping to get a chance to give the etching a bash this weekend, but I've been rather busy doing other things :-(

Martyn

[Adrian Godwin]

Yes, emerald green is good.

-adrian

[Martyn Welch]

With the solution looking good, having a bit of time available and the weather being a bit better (so that I feel comfortable being in the garage with the door open), I decided to give etching a go!

I've been collecting a few photos as I've been going along, so I've put them up for all to enjoy (well, it might keep someone amused for a few minutes):

https://picasaweb.google.com/101676653054234697688/MyFirstEtchTank

Martyn

[Rushden Rotaract Webmaster]

How are you getting on with the tank ? I bought one like that off ebay. Have filled it but not used it yet

Simon

[Martyn Welch]

On 02/04/11 17:40, Rushden Rotaract Webmaster wrote:

How are you getting on with the tank ? I bought one like that off ebay. Have filled it but not used it yet

Think I may change the heater for a slightly smaller unit, the tank has to be filled closer to the top than I'd like to get the the minimum submersion height on the unit supplied. It's just a standard fish tank heater, so that won't be too hard.


I can only compare the end result to the boards I've had professionally made in the past and those that the technician made when I was back at Uni using slightly more professional kit. Just made my first PCB today, the board was etched in about 8 minutes. There were a few patches where the resist wasn't perfect, though that is likely to have more to do with using the "press n' peel" I'm using as an etch resist and the fact that the toner seems to be running low in my laser printer. Given that it's my first try I'm very impressed and encouraged by the result I got.

Martyn

[Rushden Rotaract Webmaster]

Yea I found i needed more than 2 litres of liquid to get high enough, but I like the power of the 300W heater. I used to use a 100W fishtank heater in a 1 L cereal box and was never impressed with the heating speed. The 300W heater supplied is quite compact, a 300W fishtank heater is much much larger probably so that it don't get too hot on its surface. Comparing the new 300W to my old 100W the 300W glows and must certainly have quite a high surface temperature, so you will probably end up with a 100-150W heater to fit that tank if you get a fish one

Simon

[Martyn Welch]

On 02/04/11 18:12, Rushden Rotaract Webmaster wrote:

Yea I found i needed more than 2 litres of liquid to get high enough, but I like the power of the 300W heater. I used to use a 100W fishtank heater in a 1 L cereal box and was never impressed with the heating speed. The 300W heater supplied is quite compact, a 300W fishtank heater is much much larger probably so that it don't get too hot on its surface. Comparing the new 300W to my old 100W the 300W glows and must certainly have quite a high surface temperature, so you will probably end up with a 100-150W heater to fit that tank if you get a fish one

Mines definitely a fish one, I recognise the make from some of our rabbit stuff:

http://www.ferplast.it/scheda_prodotto_eng.php/prodotto=/id_item=66330017/id_menu=06040401

Looks like the one that I have is also 300W. I thought about using a cereal box, but decided that getting the purpose built container would be more stable, allow me to etch a larger PCB for the volume of etchant (due to it's slightly more ideal dimensions) and providing a good flow of bubbles. I guess the cost of the unit wasn't wildly more than that which I'd have to have spent on a 300W heater, bubbling system and a suitable container.

Martyn

[Adrian Godwin]

On Sat, Apr 2, 2011 at 8:13 PM, Martyn Welch <mar...@welchs.me.uk> wrote:

Mines definitely a fish one, I recognise the make from some of our rabbit stuff:

I look forward to meeting your aquatic rabbits ...

-adrian

[Martyn Welch]

Heh, I'm afraid we have but one normal mini lop-eared house rabbit. I'm not sure how keen he'd be on swimming regardless of how well heated the water is :-)

Martyn

[Rushden Rotaract Webmaster]

Hm that's interesting, the last 300W fish heater i saw was massive and I was surprised to see mine glowing (understandable for the size) maybe cheapo units made by someone that don't care about burning fish.

Yes I reasoned the same as you on the tank sizes and was getting fed up with the cereal box and no bubbler so went the full hog.

You could use photosensitive boards, use caustic soda for developing, people say it is too aggressive but that's no wonder if you heat it, barely warm and you have all the time in the world to develop

Simon

[Martyn Welch]

On 03/04/11 01:03, Rushden Rotaract Webmaster wrote:

Yes I reasoned the same as you on the tank sizes and was getting fed up with the cereal box and no bubbler so went the full hog.

You could use photosensitive boards, use caustic soda for developing, people say it is too aggressive but that's no wonder if you heat it, barely warm and you have all the time in the world to develop

I'd really like to lower the number of steps further rather than increasing them. I'd also rather not increase the number and amount of chemicals I need to dispose of, that was one of the reasons I decided to start with Cupric Chloride. I have got some caustic soda for titration, but the quantity I need to use is minimal and occasional.

Direct resist printing onto the stock looks really cool, however it seems a bit too hit and miss at the moment for my liking, depends far too much on pot luck with the type of ink that can be purchased:

http://techref.massmind.org/techref/pcb/etch/directinkjetresist.htm

Cost and space are also a factor, whilst I have to buy the print n' peel (though I have read that glossy paper will do) it takes up almost no space and I can get away with printing with an unmodified laser printer (which I have and managed to pick up for free) that can also be easily used for other things.

Martyn

[Rushden Rotaract Webmaster]

well as caustic soda is cheap I just make up about a half inches worth in a lunch box develop and then tip it down an outside drain, I'm not sure what it becomes but I guess that at that point it is still mostly caustic soda, it's cheap to buy anyhow. Providing you get the exposure right and don't heat up the caustic soda too much you will have plenty of time to play with it

Simon

[Adrian Godwin]

Caustic soda is often sold as drain cleaner. I can't see anyone objecting particularly to you pouring it down a drain in small quantities.

Having said that, some people don't like it for developer. Not sure of the reasons, but Mega Electronics sell a 1L bottle of non-caustic-soda based stuff for about £12 that's diluted 20 times for use and has a long shelf life, so is fairly reasonable to use.

-adran

[Rushden Rotaract Webmaster]

caustic soda is known to the "aggressive", indeed I developed my first board in about 5 seconds and was just lucky i was fast to chuck it in a jug of water before it was all gone. Later i found that having it any hotter than about 35 degrees (going by how hot it felt to me) makes developing instant to the point it strips all of the photoresist off as soon as it goes in. I think about 20-25 degrees is probably better that way you have time to react. It could be that it is too aggressive for small traces but I always try to use 30 thou minimum

Simon

[Adrian Godwin]

There's an interesting idea referenced here:

Printing Wax onto PCB – Simple, Quick DIY PCB’s

(printing a resist layer using a modified epson inkjet)

-adrian