Preferred Etchant?

[Mosaic]

I use conc. Nitric (HNO3) mixed down 1:4 in water to etch copper clad boards using the Toner Transfer method down to 10 mil traces.

Results are good, no warming and very little agitation required as the etching bubbles on its own. The acid mix is gentle enough to get on hands for a few secs with no harm. No staining.

The mix is transparent and gets bluer as its consumed. By the time it's ready to be changed u can hardly see a board in 1" deep mix. For the most part I can see the board as its etching and know when to take it out.

The HNO3 can also be used to desmut aluminum for DIY anodising!

What type of etchants do u use and prefer?

 

[RMMM]

Hydrogen Peroxide and Muriatic Acid. 3.

A 1 to 3 or 1 to 4 mix.

Usually 4 cups total. Get the H2O2 at the dollar store, and the acid at the pool store or most hardware stores.

It is sold as a pool chemical, or to clean concrete.

Quite fast acting. results in a quick etch and sharp lines.

 

[Sceadwian]

I haven't needed to etch yet, but I already have a preferred enchant of Ferric Chloride, it can be messy but it's simple and a local plating plant can use the waste product in their waste treatment process so I know where the copper is going. IE NOT down the drain.

 

[shokjok]

I have tried ammonium persulfate with good results. This etchant is available from Active Components in Canada, comes in a white crystalline powder and turns blue when etching is complete. It can be safely disposed of down the drain.
I have also used ferric chloride, staining my hands and clothes. In either case, I don't use washer fluid pumps to accelerate the process.

 

[Pommie]

Best etchant has to be Ammonium Persulphate, no smell or fumes and it comes as a nice white powder. The resultant solution contains Copper Sulphate and can be simply thrown down the drain. Anyone not happy throwing it down the drain can add some Sodium Bicarbonate and the copper will precipitate as Copper Carbonate.

Mike.

 

[DirtyLude]

I`ve tried AP, FC, and muriatic acid/peroxide. I prefer Ferric Chloride just because it makes the cleanest etch. acid/peroxide next, because it's pretty fast and cheap. AP last, because it seems to take forever. Heating the solution doesn't seem to help. Both AP and Acid/Peroxide manage to get past my toner transfer etch resist a bit and will give a slight rash.

 

[RMMM]

I`ve tried AP, FC, and muriatic acid/peroxide. I prefer Ferric Chloride just because it makes the cleanest etch. acid/peroxide next, because it's pretty fast and cheap. AP last, because it seems to take forever. Heating the solution doesn't seem to help. Both AP and Acid/Peroxide manage to get past my toner transfer etch resist a bit and will give a slight rash.

Add more peroxide. That should "sharpen" your etch.

 

[Pommie]

With Ammonium Persulphate I make the solution with boiling water and it literally etches in 5 minutes.

Mike.

 

[DirtyLude]

Add more peroxide. That should "sharpen" your etch.

I've added a lot. Enough that it doesn't dissolve that well anymore. Here it's more that it eats through the etch resist a bit, so I try to remove it when it's just etched through.

With Ammonium Persulphate I make the solution with boiling water and it literally etches in 5 minutes.

I've tried heating the AP solution, but not that hot. I'll give that a try.

 

[Sceadwian]

Pommie, unfortunatly you are dead wrong, no solution of disolved metals can be simply thrown down the drain legally in any state in the US and probably violates your residental sewer discharge permit. Unforuntaly your mindset is so prevalent I'll probably go down in flames for being right. Many cities and villages simply discharge their sewer water into local waterways, only some of the larger cities have waste water treatment plants for their sewer effluent, and that's only because so many people throw things down the drain they shouldn't that they have to because the final discharge point of a larger city becomes an unlivable cesspool.

 

[Pommie]

Pommie, unfortunatly you are dead wrong, no solution of disolved metals can be simply thrown down the drain legally in any state in the US and probably violates your residental sewer discharge permit. Unforuntaly your mindset is so prevalent I'll probably go down in flames for being right. Many cities and villages simply discharge their sewer water into local waterways, only some of the larger cities have waste water treatment plants for their sewer effluent, and that's only because so many people throw things down the drain they shouldn't that they have to because the final discharge point of a larger city becomes an unlivable cesspool.

I keep hearing this but it cannot be correct. Government agencies in the USA advocate using Copper Sulphate to clear drains (Clicky). How does pouring a dilute solution of CuSO4 down the drain compare to 2lb of powder?

Mike.

 

[Sceadwian]

Pommie, you'd have to trace the local state and federal waste water discharge requirements for your area. It's an impossible paper trail to follow, and it's completely overlooked, one hand doesn't know what the other is doing. It should be noted that EVERYTHING you toss down the drain ends up in a body of water somewhere, either in local drinking water or a water table where the landfill is. That's why I like Ferric Chloride, I know I can give the spent solution to my local plater and it will go through their waste treatment system, the still usable ferric chloride helps establish a flock for lighter metals in the waste treatment stream and the copper goes along for the ride after it's been neutralized and everything starts to precipitate out, that is then legally disposed of by immobilization in concrete or an appropriate landfill sites in bedrock areas where disolution of the waste material into ground water will either not occur or will occur slowly enough to not be a problem. That is of course the theory =)

What you and I dump down a drain a metal finishing plant would be fined 10,000 dollars for if it was discovered. There's a massive policy vs policability issue in this area.

 

[Mosaic]

Copper salts are popularly used as biocides to handle fungus build up etc. U can buy/use CuSo4 to spray your herbs at home. Sodium or Potassium chloride/iodide are metal salts. U can eat them. Magnesium hydroxide is a metal salt - milk of magnesia,. I add extra CuSO4 to my outdoor house paint to get less fungal growth on the concrete etc.

Metal salts surround us. Calcium carbonate is found in lime stone.

All etchants result in copper salts which are useful in killing off assorted fungi. You cannot apply industrial restrictions to hobby applications.

If a plant were to dump 100 tonnes of waste bleach into a single river....they'd be liable for the damage. If 1,000,000 consumers dump 100 tonnes total of waste bleach...it passes through a 100,000 different water courses and is neutralised by the soil/fungal contact.

Similarly for ferric or cupro metal salts. They don't cause 'heavy' metal build up in organisms like lead/mercury and will pass through organic systems.

Most pool water systems use copper sulphate and Chlorine/bromine as oxidiser/fungicides, they don't need 'treatment' to go down the drain.

It's a matter of quantity, too much of anything is bad. Let's not go overboard for a liter of etchant per month shall we?

 

[Sceadwian]

I'm sorry Mosaic, but you as well as nearly every person in the US thinks like this, and is DEAD WRONG. If you would care to correct me please contact your local municipality and obtain a copy of your local sewer discharge permit and send it to me, but please stop stating something that is absolutely false. As I've said previously, this is simply and glaringly overlooked by pretty much everyones down the drain or in the can out of mind mentality.

Here's a link to my local counties program for household hazardous wastes.
Environmental Services | Monroe County, NY

Pretty much every sewer discharge permit you'll see will state that the only thing you can discharge down a sewer drain is 'domestic waste' This is basically toilet water and dirty dishwater, pesticides and chemicals from ANY process are not domestic waste. Technically it's not okay to dump draino down your household drain. There is however no way to enforce this kind of thing. There are fines and what not for illegal sewer dumping that would apply to homeowners but again there's no practical way to enforce that and it's simply over looked.

It's truly sad that so many people think like this, and it's irresponsible to say this is going overboard. It is a TRIVIAL thing to collect and dispose of this stuff lawfully and safely. I collect all my used batteries CFL tubes etc.. etc.. and it's a 5 minute out of my way trip to drop them off at the counties disposal site, and again that's why I prefer ferric chloride because even the spent solution is a net benefit to the waste treatment process at a local plating shop.

As you say it's a matter of quantity. How many millions of people think just like you and dump that or worse down the drain everyday? LOTS

 

[Sceadwian]

Made a mistake on this post, voided =)

 

[RMMM]

Wow, in Maryland, anything besides standard domestic wastewater requires an additional paid-for permit.

They MAX out. at this:

Q. Are there limits to what can be discharged into the sanitary sewer system?

A. Yes. The following list identifies those, which have had specific limits set by the treatment plant. These and other pollutants may be further limited on a case-by-case basis or be set by the Environmental Protection Agency based on industry category. If you are discharging or wish to discharge an unlisted pollutant to the sanitary sewer as part of the wastewater generated at your business, please contact the Engineering and Regulation Division of the Bureau of Utilities at 410-887-5477.

Pollutant Limit

Cadmium 0.21 mg/L
Chromium 6.89 mg/L
Copper 6.59 mg/L
Cyanide 1.9 mg/L
Lead 0.01 mg/L
Mercury 0.01 mg/L
Nickel 2.82 mg/L
Silver 1.2 mg/L
Zinc 17.85 mg/L
Fat/Oils 100.0 mg/L
Total Toxic
Organics 2.13 mg/L
pH range 6.0 to 10.0 pH units

Using 1 liter of etchant, if you etch a 6x6 2 sided board using 1oz per side board loosing 50% of the copper, you are flushing 1 oz if dissolved copper. If you only etch 1 board or equivalent with this liter before dumping it, you would be flushing ~1600mg/L (WAY more than the 6.59 limit WITH a purchased industrial discharge permit.

So, yes, it is bad.

Time to re-think my flushing.

Also, ferric chloride is used during the first step in potable water treatment, so ferric chloride would be morally better, but the amount of copper is still way out of here.

 

[EternityForest]

This is why i never DIY PCBs. Those copper salts and dissolved copper cause all sorts of assorted problems.
If you are going to etch your own pcbs(with any etchant) Please, don't pour it in the loo.
Dispose of in in a safe and lawful manner. If you don't: A, it hurts this planet our mother, B, It's illegal , and C, It gives us electronics people a bad name.

It is very easy to put that crap in a bucket or something and take it to a safe place to get rid of.
I would like to see a stickied thread about safe disposal with per-state lists of places. I personally don't do etching so i don't know where those would be, but if someone wants to start one i think it would be much needed.
-Danny

 

[Mosaic]

RMMM, dont worry yourself , it's the OVERALL amt that matters.

Add your 1 litre per month of 1600mg of copper to your multi thousand litre total bath, kitchen, rain runoff etc. You'll quickly realise that you're not in contravention. It's not about the tiny individual doses ....it's about the overall dosage that matters.

That's why draino and muriatic acid and copper salts used to clear drains is not considered enough of a problem to legislate or police. Folks who want to sweat the small stuff can if they want to. It's the big consumers that really matter since their average output can be very damaging. Sometimes I wonder if the people who agonise over carbon emissions and global warming etc. ought to perhaps hold their breath and don't crap or fart (methane) for 50% of the time to see if that improves things.

Do you know that the MAJORITY of global warming gases come from livestock? Basically animal husbandry is a major cause? Environmentalists don't really always focus on the real causes just the stuff that is convenient.

Edit:
B4 others in this thread jump on me (again) let's consider this. You are happily washing up after dinner....steak & fries. Whoops that bit of stringy fat you cut from the steak (2 grams) slips down with the waste water. Oh NO....2000mg of fat....voids your 100mg/L limit....you are in contravention and NEED to be charged to the full extent of the LAW. Overtones of Judge Dredd....

OR...you are sick...you barf out the entire meal including your CENTRUM silver vitamin...

**broken link removed**

Oh NO...you have surely overstepped you Zinc levels in the waste water, not to mention the 5000 milli grams of fat u unwittingly ate in the beef & fries.

Judge Dredd is at your door to enforce the sanitation statute.

OR you pour 1 Litre of old 'flat' coke ( from the 2L you had in the fridge since last week) down the sink. OOOPS...thats 2.6PH ...caught AGAIN.



get real people.

 

[DirtyLude]

Using 1 liter of etchant, if you etch a 6x6 2 sided board using 1oz per side board loosing 50% of the copper, you are flushing 1 oz if dissolved copper. If you only etch 1 board or equivalent with this liter before dumping it, you would be flushing ~1600mg/L (WAY more than the 6.59 limit WITH a purchased industrial discharge permit..

Those limits you listed are limits for industrial sewage. The limits are for continuous disposal and isn't meant to represent an individual litre of waste on its own.

 

[Sceadwian]

Mosaic, what you don't get is that the overall amount is HUGE, because everyone thinks like that and dumps the stuff down the drain. Your kind of mentality is a crime against common sense. This isn't just about hobbyist etchers, the average person in the US and around the world for that matter uses many chemicals and disposes of them improperly in VAST quantities as a whole, the problem is it's not measured, it can't be unless you want to set up point measuring stations at the sewer discharge pipe of every home.

Mosaic... You're really off your rocker and apparently are hiding your head in the sand about an issue that the government actively thinks it's a problem, people such as yourself that spread that this is a non issues ARE the problem.
**broken link removed**
Keep looking on the net you'll see virtual every county in the US has sites like this.

This is a problem in MANY communities, and it's completely unpolicable because EVERYONE does it, it's like tire dumping, or putting batteries and electronics in your local dumpster. There's absolutly nothing they can do about it except try to properly educate the general public about this as a problem, you're actively arguing for intentional discharge of hazardous chemicals directly into public water ways, common sense should have kicked in a LONG time ago. As populations in cities increase over the coming years the problem is just going to keep on getting worse.