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Old 5th Dec 2019, 4:00 am   #21
Argus25
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Default Re: Ferric Chloride

It is interesting the different experiences, materials and methods that everyone has with home pcb making.

Initially when I first tried it back in the 1970's I started out with ferric chloride and had little trouble, using a combination of Dalo pens and rub on transfers. One day the ferric chloride became unavailable and I had to use ammonium persultphate and it gave a poor result, with much more undercutting of the tracks and the ink even seemed less resistant to it. So I went back to ferric chloride. But it might have been a "one off" experience that put me off it.

So perhaps its easy to be put off by one off events, when really one technique or one product might be equally as good as another, if you persisted. Which may explain why there are so many different materials and techniques still around.

Over the years though I realized I could never get my home pcb's as good as a professionally made one, so for any project that I want like this I bow my head to my pcb maker and cough up the $. But if I want something to have a "home made" look, on occasions I still make one myself, with iron on film and ferric chloride.

Jaycar still sell a pcb ink marker pen that is pretty well identical to a Dalo pen:

https://www.jaycar.com.au/etch-resis...-blue/p/TM3002

Last edited by Argus25; 5th Dec 2019 at 4:04 am. Reason: add link
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Old 5th Dec 2019, 8:08 am   #22
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Default Re: Ferric Chloride

Hi. I only needed to make 2 PCB’s for my Class A amplifier project, so decided to mill, or ‘ grind’ away the copper with a dremel engraving blade.

It’s not very neat, but it has served its purpose. It also didn’t take very long to do, and looks slightly reminiscent of the way they were made many years ago!



Cheers. SimonT.
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Old 5th Dec 2019, 8:39 am   #23
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Default Re: Ferric Chloride

Another pen which I believe could substitute for a Dalo is this one
https://uniball.co.uk/uni-super-ink-marker-pna-125/.
Although the distributor is called Uniball, these particular pens (PNA-125) are fine fibre tips.

I've been buying these just as really good, indelible, fine marker pens, haven't yet tried them in PCB making, but suspect they tick the boxes. In the UK, your local Wilko sells them, but as they are made in Vietnam, they are probably available worldwide. In general use, these compare very favourably against the Lumocolour pens.

B
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Old 5th Dec 2019, 10:04 am   #24
David G4EBT
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Default Re: Ferric Chloride

I never had much success with Dalo pens - I found that they only deposited a very narrow and thin 'see through' layer and I couldn't thicken it by drawing over it because the new ink dissolved the old. The result was tracks which were generally electrically conductive, but were 'threadbare' and offensive to the eye, so for many years I resorted to rub-down transfers, 'Humbrol' modelling paints or 'Fablon' sticky-backed plastic.

Many magazine projects were designed using stripboard to save the hassle of needing a PCB, but I wasn't keen on that either, so even for quite simple projects, I tended to design a PCB instead of using the stripboard layout. Where PCBs were called for, the magazines often had a PCB service for the more popular projects. It seems to me that for anyone who has a laser printer, (I don't), the laser toner-transfer method seems to have much to commend it, though as with all techniques, some people get on with it better than others.
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Old 5th Dec 2019, 10:39 am   #25
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Default Re: Ferric Chloride

For pens I've found Steadler fine markers work fine. Sharpies are often recommended but I found they didn't work, at least not with sodium persulphate. Poundland ones worked but were too thick. I now use a fine 'paint' marker that I got via AliExpress. As the name implies, instead of ink this contains paint.
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Old 5th Dec 2019, 10:41 pm   #26
David G4EBT
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Default Re: Ferric Chloride

Occasionally, I've come across references (from Australia and America in particular) to using an etchant comprising 'muriatic acid' (which tends to be called hydrochloric acid in the UK), mixed with hydrogen peroxide, as an alternative to ferric chloride. I don't think it's found favour in the UK where as far as I can tell, the only alternative tends to be sodium persulphate, the downside of which is that it needs to be heated to about 45C to be effective, whereas ferric chloride can be used at room temperature.

In Australia and the USA, 'muriatric acid' is often called 'pool acid' as it used for killing bacteria in swimming pools, but we're not big on pools in the UK, where its sometimes called 'brick acid' as it's often used to remove cement mortar stains from brickwork, as well as cleaning concrete patio slabs, and for removing limescale.

I spotted and 'instructables' on internet which details the use of this etchant mixture, which is headed:

'Stop Using Ferric Chloride Etchant! (A Better Etching Solution.)'

Here's a clip:

Quote:

Ferric chloride is a traditional home-use circuit board etchant. It's easy enough to come by, and the Ferric by itself is no big environmental problem. However, once you've etched a board with it, you're left with a solution with a bunch of copper chloride in it. This dissolved copper is an environmental problem, and you can't just pour it down the drain (legally) -- you're supposed to take it to a hazardous waste facility.

Wouldn't it be nice if there were an etchant that you could re-use indefinitely so that you don't have to worry about disposing of the copper, and that could be made in lifetime supply for like $10.00 with ingredients bought at hardware and drugstores? (And it's prettier too.)

I've got seven words for you: Copper Chloride in Aqueous Hydrochloric Acid Solution!
But how're you going to get CCiAHAS? Conveniently enough, by starting out with a simple two-ingredient starter etchant, and doing a bunch of etching.

Measure out two quantities of hydrogen peroxide and pour it into your non-metallic container.

Measure out one quantity of hydrochloric acid and pour it in. ("Do like you oughta, add acid to water" to minimize the chance of an out-of-control exothermic reaction.)

Be careful with the acid. This stuff (at 10 molar) is strong. Mine fumed a bit when I took the cap off. Don't breathe it directly, and be sure you've opened the kitchen window.
Hydrochloric (muriatic acid, "pool acid", etc.) is available at a hardware store. The acid I got is 31.45% (or 10M) and should run around $5 per gallon. Which is more than you'll ever, ever need.

The peroxide is normal 3% for mouthwash or cleaning cuts, and can be bought at a drug store for $2-3 for a big bottle.

End quote.

Here's the link:

Stop Using Ferric Chloride Etchant! (A Better Etching Solution.)

https://www.instructables.com/id/Sto...-A-better-etc/

He mentions using acid which is '10 MOLAR'. The only acid which seems to be widely available in the UK is 0.1M, which I assume is 1/100th of the strength of 10 MOL, but maybe the chemists among us could advise on that?. (I might be looking in the wrong place?).

EG:

Hydrochloric Acid Solution : 0.1M (0.1N) £9.99 a Litre post free:

https://www.ebay.co.uk/i/16188041622...&mfe-Id=100887

He mentions 3% Hydrogen Peroxide, which is readily available in the UK (as is 6,9 & 12%). EG :

Hydrogen peroxide £7.24/Litre post free:

https://www.ebay.co.uk/itm/HYDROGEN-...8d22df97d23a28

I had to smile where he says 'the fumes can be nasty - open the kitchen window'. The inference being 'do this in the kitchen'. Errm, do what in the kitchen?!!

I also noted that he stores the used etchant in a whisky decanter. It has a passing resemblance to whisky, so that could be a 'Darwin Awards' winner in the 'non -survival of the stupidest' stakes.

Like ferric chloride it can be used cold and used again and again up to a point, but it looks just as messy and seemingly has little to commend it. Maybe that's why ferric chloride seems to be the etchant of choice in the UK, with sodium persulphate being my preferred option for reasons already stated.

I wondered if any forum members use this as an etchant, either in the UK or elsewhere?
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Old 6th Dec 2019, 12:26 am   #27
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Default Re: Ferric Chloride

Wendy- I find that despite all the bad sayings on Express PCB, there's the option to give a copper screen, resulting in a lot less area of copper to be removed.
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Old 6th Dec 2019, 3:14 pm   #28
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Default Re: Ferric Chloride

I thought hydrochloric acid was a big No No..as it attacks most things except ceramic or porcelain....I will stick to Ferric Chloride and say.. yaa boo.. to any other chemicals...Its strange.. when I started this thread.. I didnt expect such an in depth reply. Thanks to all contributors.
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Old 6th Dec 2019, 6:48 pm   #29
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Default Re: Ferric Chloride

Well, stomach acid is mostly hydrochloric acid I think.
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Old 7th Dec 2019, 12:21 am   #30
Wendymott
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Default Re: Ferric Chloride

Hi Tony..... Yes but our internal chemistry has enzymes that counter the acid...or so I am led to believe...and when we shuffle off this planet, we cease making these enzymes and the acid gets "its go".
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Old 7th Dec 2019, 1:25 pm   #31
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Default Re: Ferric Chloride

Just seen the 10 molar hydrochloric acid solution above and laughed. That stuff is nasty and dangerous to handle. I know this after giving myself about 20 years of nasty dermatitis after accidentally putting water in some. Ended up with it all over my hands

While it’s nice to make a PCB I contract it out to JLCPCB or just don’t bother now. Some FR4 and aviation shears and super glue is a much nicer solution and a lot less nasty
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