PCB etching

[poorchava]

I could only find new, fancy kind and there was no easy way to deemulsify it.

Exactly the same thing here. Actually the only two ways to get 'real' peroxide was to either buy it from pharmacy as 3% solution, or from chemical supply wholesaler, but the minimum quantity of technical grade is 20L and it's not that cheap (around 17€ / 20L).

In Poland companies dealing in chemicals generally refuse to sell acids to private people, because those are perceived as dangerous/toxic substances. In most cases giving your personal information (name, address etc) is enough, but then not many companies are willing to sell so low volumes (where low volume = less than 200 liter barrel)

[flolic]

Up until few years ago, here in Croatia you could buy 30% peroxide in every pharmacy. Then they change some rules and now you can buy only diluted 3% "safe" concentration.
But if you know right people... 

[Resistoid]

Well I did it with 2m hcl and alot of peroxide, I don't know the proportions but it took forever

megahz, if you just stick to the concentrations and proportions I gave you earlier you should not have any problems etching your boards.

What I am telling you is verified by personal experience:

Peroxide: 2 parts (160 ml).  Concentration 6% - 9%. - You can almost certainly buy this from a pharmacy.

HCl:          1 part (80 ml).  Concentration at least 25%. - You can almost certainly buy this from a hardware store.

You'll have to decide the volume of a "part" -  use enough of the mixture to cover the surface of your board when it's lying flat in your etching tank.

Agitate or swirl the etchant so it washes over the surface of your board and keep a close eye on proceedings.

A double-sided FR4 board, roughly 14cm x 12cm etched in 5 to 10 minutes; probably closer to the former.

This method is much more rapid than etching with ferric chloride under similar conditions.

Good luck.

Resistoid.

[ptricks]

check out this video where the guy  shows 10 different etchants and how to make them.



The guy NurdRage has a lot of other interesting videos, most are chemistry type stuff.


I found something interesting when I let my last batch of etchant dry out:




The cystals are a couple inches tall and very  detailed. The etchat I use is copper chloride.

[megahz]

the pharmacy near me does not sell 6 or 9%, only 3%H2O2

[ptricks]

the pharmacy near me does not sell 6 or 9%, only 3%H2O2

3% will work for etchant , I use it all the time.  The thing to remember is not to shake the container or leave it uncapped for long or it will revert to plain water.

[ddavidebor]

I use 30% hcl with 130vol h2o2, casual quantity.

[M0BSW]

What is this ho2o or hci anyways , is it somekind of secret code, or are you from those UFO's I saw.

[Resistoid]

megahz, ptricks has told us that he uses 3% peroxide successfully. - I too have a vague memory that I may have done this in the past, as I mentioned in my first post on this subject.

I suspect that the culprit is your 2M HCl: It's probably too weak.

Allow me to explain: 2M HCl contains c. 72 grams of HCl per litre (1 mole of HCl weighs about 36 grams).

Calculating the weight in volume concentration as a percentage gives: (72g / 1000ml) x 100 = 7.2% w/v.

Your 2M HCl is the same thing as 7.2% HCl. - Apparently too weak. - Remember I recommended that you use 25% HCl, or higher.

25% HCl contains 250 grams HCl per litre. Expressing that concentration as a molarity requires that we divide 250 grams by 36 grams (i.e. the weight of one mole of HCl):

250g / 36g = 6.94.

In other words, my 25% HCl is the equivalent of nearly 7M HCl.

If I were you, I would try much stronger acid, at least 25% or 7M with the 3% peroxide your pharmacy sells.

Let us know how you get on.

Resistoid.

[Resistoid]

What is this ho2o or hci anyways , is it somekind of secret code, or are you from those UFO's I saw.

M0BSW, I am from the UFO and I will let you in on the secret code:

HCl = Hydrochloric acid

H2O2 = Hydrogen peroxide

Resistoid.

[M0BSW]

What is this ho2o or hci anyways , is it somekind of secret code, or are you from those UFO's I saw.

M0BSW, I am from the UFO and I will let you in on the secret code:

HCl = Hydrochloric acid

H2O2 = Hydrogen peroxide

Resistoid.

Thank you space man na noo na noo

[Resistoid]

You are most welcome, Earthling. Now, take me to your leader

Resistoid.

[chipwitch]

Anyone looking for HCl... just ask for Muriatic acid (another name for HCl) at the local pool supply.  Costs about $3 US/gal. for 10M (about 32%).

[Resistoid]

Anyone looking for HCl... just ask for Muriatic acid (another name for HCl) at the local pool supply.  Costs about $3 US/gal. for 10M (about 32%).

That's right. - This information was included in the "Instructables" link I gave megahz in my first post on his problem (Reply #4 on: April 08, 2013, 06:40:48 AM).

The only significant difference I can see is the price quoted by you, chipwitch, is even more reasonable than the $5 per gallon according to "Instructables".

Moreover, Instructables' method specifies 3% peroxide, which is precisely what megahz says he can get.

Resistoid.

[megahz]

cool, the pool supply place down the street had some, now I just need another board to etch

[IanB]

It may have been said before, but if you buy muriatic acid (hydrochoric acid) at some strong concentration like ~35% and it comes in a plastic bottle, then don't store it anywhere near tools that you value, or anything that will rust. The best place to store it is outside, under cover. If you put it in your garage, then anything made of iron or steel nearby will crumble into brown dust in a matter of months. By the time you notice, it will be too late. HCl is evil!

[amspire]

check out this video where the guy  shows 10 different etchants and how to make them.

I took a look at the videos from this guy, and they are among the best I have seen. It is not just the different methods, but you can make your own ferric chloride pretty easily from  iron (nails or steel wool), HCl and either air or H₂O₂. I love information like this that empowers me to do things I never thought of doing.

Thanks to this thread, I am going put aside my current store-bought etchant for now to try some of the different etchants myself. I have never used the HCL/H₂O₂ etchant before so that is the first test.

Great thread!

[ptricks]

It may have been said before, but if you buy muriatic acid (hydrochoric acid) at some strong concentration like ~35% and it comes in a plastic bottle, then don't store it anywhere near tools that you value, or anything that will rust. The best place to store it is outside, under cover. If you put it in your garage, then anything made of iron or steel nearby will crumble into brown dust in a matter of months. By the time you notice, it will be too late. HCl is evil!

Very true. The acid I use even lets off a little puff of smoke like gas whenever I take off the lid. When I let my etchant dry out I had it below a piece of stainless steel, that steel is now coated in rust.