PCB Etching Method

[hugoender]

I would like to form a compilation of PCB etching methods along with the pros, cons, materials, speed (time to etch), complexity factor of each method, etc.

There are a couple of RF circuits I want to create that require me to use a PCB (due to the high frequencies) and because of this I have been forced to start looking into etching solutions. Now mind you, for me the best etching solution would be the one that is cheapest, requires the least amount of materials, and is the least dangerous (in that order ).

If people could start posting the etching method they are familiar with along with the abovementioned characteristics for the method mentioned, this thread could serve as a great reference to those looking to enter the world of pcb etching.

In order to make this thread somewhat coherent, I will include an example template which you guys can use to post your etchant of choice:

Etchant: (etchant name here, i.e. Ferric Chloride)
Price: (rating of price; $$$$-Expensive, $-Cheap)
Danger Level: (rating of how easy it is for a newbie to hurt themselves using this method; XXXX-Dangerous, X-Not Dangerous)
Time: (approximately how long it takes to etch and what can be done to speed up the process)
Regenerative (Y/N): (whether the chemical etchant can be reused after an etch and if so, the degree of reusability, or how many times can one bath of etchant be used before it does not etch)
Materials: (list of chemicals or materials needed in order to etch)
Description: (brief description of what it is and how it works)
Procedure: (rough outline of the procedure to etch with this etching method)

 

[hugoender]

By the way, this template is by no means perfect or complete so feel free to add or change whatever you feel is necessary.

 

[TiagoSilva]

Etchant: 80% chloridric acid + 20% hydrogen peroxide
Price: $$
Danger Level: XXXXX
Time: 5 to 10 Minutes, heat a little to speed up and shake it gently
Regenerative (Y/N): It can be used while it has the peroxide hydrogen bubbles, after that you can add a little more peroxide or just dispose of it
Materials: 80% chloridric acid + 20% hydrogen peroxide
Description: It's activated acid, it produces some nocious vapors.

Procedure: Use lattex or rubber gloves and face mask, just mix the reagents, the measures i gave are somewhat like guidelines, they are not strict... Use protective eye gear to avoid splaches to the eyes...
If that happen pour lots of what on the eyes and avoid direct sunlight contact to avoid serious eye damage !!!!
It will burn the skin after some time of direct contact... so use the gloves.

If you intend to dispose it to the sewer be sure to neutralise the acid first, to do that use any carbon liquid... Just like milk ! After some time the milk will look like yogurt, don't eat it its toxic... and if no acid is to be seen it is ready to go in to the sewers... but be careful has this might be ilegal...

 

[HarveyH42]

I'd suggest using this site's search option. We do this topic almost monthly, so you will get lot's of hits. Be a lot quicker, then to wait for people to re-post the same information, just one more time, just for you. Believe we just had this about a week ago. I've lost interest in repeating myself on this topic, got a hunch several others are burned out on it as well. Might try Google, I remember a link somebody posted here, and the site had pretty much everything you were asking about. Ir was mostly about Toner-Transfer, but went into good detail on some other methods, and several etch solution options... I don't do high volume, but can be about finished soldering in about an hour after printing the artwork...

 

[Krumlink]

Tiago, I have used this method before, and one problem I face with it is that it tends to be too strong and eat too much copper away, even under the drawn traces!

I have heard that pandemonium sulfate crystals work great, but I have not used it before.

 

[hugoender]

@Harvey:
I agree with you... this topic has been exhausted in these forums and other websites. However, I am trying to create a one-stop place where you can find all the etching methods and what they entail. It is a lot easier to decide which etching method is best for you when it is all compiled in one place as opposed to having to go through numerous threads and sites. I am in no hurry to get a response for this thread since I have been searching these forums and noting which methods I prefer. I just want to try and make it a little easier for anyone else that might be entering into the pcb making part of electronics.

With that said, if anyone has a link to a site that has a compilation of etching methods in one place, by all means, post it here. Then when other people search these forums to figure out what type of etching is best for them, they will stumble upon this thread and the link to the site.

 

[3v0]

Allow me to pull out my crystal ball.

You place safety last and low cost first.
Which I feel is a huge mistake but your choice to make.

You will pick the "80% chloridric acid + 20% hydrogen peroxide" method.

Ferric Chloride would be less dangerous but more expensive.

Sodium Persulphate is even less dangerous and more expensive the Ferric Chloride. It will not corrode/stain you sink or plumbing. It will not rot your lungs or burn your skin. I do not know just how safe it is but it is more so then anything else I have tried.

Crystal balls can be wrong.

 

[hugoender]

lol 3v0 very well put.

Care to elaborate on the Ferric Chloride and Sodium Persulphate methods so that others reading this thread (which by the way is not turning out how I meant for it to turn out) can be informed/enlightened?

 

[3v0]

lol 3v0 very well put.

Care to elaborate on the Ferric Chloride and Sodium Persulphate methods so that others reading this thread (which by the way is not turning out how I meant for it to turn out) can be informed/enlightened?

As said earlier this is getting old!
Quick and dirty OK?

To be safe you should use Ferric Chloride under a fume hood or with a fan venting the fumes away from you. If you inhale enough of this you lungs will feel like you have pneumonia. I will stain/etch fixtures and is said to corrode plumbing. It has been the standard hobby etchant for decades.

Sodium Persulphate may etch a bit slower Ferric Chloride. More so as the solution get used up. Heat is good with both processes but vital with SP. Starts out as a clear liquid and goes blue as it is used up. If you are not in a hurry you can etch just one more board sort of thing prior to giving up on the batch. I allow my used solution to evaporate leaving blue crystals behind The quantity is small. After a few years I will take what I have collected and turn them in at a recycling event.

One of our members who lives in a collage dorm has an interesting method. He microwaves water in a freezer zip lock bag. Adds etchant to the solution. Add the board and seals the bag. He agitates liquid till the board is etched and discards the etchant.

I have etched in a bread pan heated with by a halogen work light and a jar immersed in a crock pot of hot water. No hight tech is required but agitation is required. The solution does not smell bad but I try to advoid breathing it anyway.

 

[picbits]

That reminds me. I really must have a play with my sodium persulphate.

I have a 25kg sack of it sitting in the workshop ........

 

[jbeng]

I have heard that pandemonium sulfate crystals work great, but I have not used it before.

Pandemonium Sulfate? I would expect you mean Ammonium Persulphate ... and it does work well ... but I usually use ferric chloride solution, since that's what I have on hand.

Jeff

 

[picbits]

The persulphates tend to deteriorate over time when not used (and when used) so have a limited shelf life.

Ferric Chloride while being rather messy and nasty stuff lasts forever (well nearly).

Don't ever mix single coat plaster with FeCl to try and neutralise it/dispose of it. I had a nasty experience while experimenting.

Basically imagine that expanding foam stuff with the stain factor of FeCl and you'll get the general idea. I had to evacuate our pet rabbit as the foam decided to travel over 6 feet and started encroaching on his hutch.

It took me nearly 2 days to clean up all the mess. This was from 5 litres of FeCl and a shovelfull of one coat plaster.

 

[hugoender]

The persulphates tend to deteriorate over time when not used (and when used) so have a limited shelf life.

Ferric Chloride while being rather messy and nasty stuff lasts forever (well nearly).

Don't ever mix single coat plaster with FeCl to try and neutralise it/dispose of it. I had a nasty experience while experimenting.

Basically imagine that expanding foam stuff with the stain factor of FeCl and you'll get the general idea. I had to evacuate our pet rabbit as the foam decided to travel over 6 feet and started encroaching on his hutch.

It took me nearly 2 days to clean up all the mess. This was from 5 litres of FeCl and a shovelfull of one coat plaster.

LOL! That is pretty amazing!

 

[mneary]

Ferric Chloride while being rather messy and nasty stuff lasts forever (well nearly).

I bought a few gallons in 1967 and I'm still using it.

 

[3v0]

The persulphates tend to deteriorate over time when not used (and when used) so have a limited shelf life.

After it is mixed with water or in the dry crystal state ?

 

[picbits]

After it is mixed with water or in the dry crystal state ?

If its in an airtight bag the crystals will last a very long time.

In liquid state it has a much shorter shelf life.

A datasheet I have say unopened Sodium Persulphate has a shelf life of 3 years while opened Sodium Persulphate has a shelf life of 1 month.

I've also got a datasheet to say that Ammonium Persulphate has a shelf life of 1 year in crystal form.

 

[3v0]

My 1KG bottle is over a year old, maybe closer to two. It still works. I do not know if it etches any slower because I did not time it when new. When it is nearly gone I may get a new supply and run a test with two identical boards to see if the old is slower.

Still good stuff but stocking up might be a bad idea.

If its in an airtight bag the crystals will last a very long time.

In liquid state it has a much shorter shelf life.

A datasheet I have say unopened Sodium Persulphate has a shelf life of 3 years while opened Sodium Persulphate has a shelf life of 1 month.

I've also got a datasheet to say that Ammonium Persulphate has a shelf life of 1 year in crystal form.

 

[theo92]

CAN somebody please tell me; what amount of Ferric Chloride (anhydrous) to be mixed with what amount of water for etching one 9cm x 5cm board.
Please!!!!!

 

[3v0]

CAN somebody please tell me; what amount of Ferric Chloride (anhydrous) to be mixed with what amount of water for etching one 9cm x 5cm board.
Please!!!!!

The size of the board is not a good indicator. If the copper is twice as heavy it will use up twice as much etchant. If the copper is to be mostly etched away it will use up much more solution then if most of the copper remains.

Determine how much solution it will take to cover the board or fill you etching tank. Your choice.

Earlier Torben linked to a page that pointed out 100 grams of crystals per 200ml of water.

Just do it.

 

[CCD]

Hi,
check out here a nice tutorial on making pcb using the etchant ferric chloride, a laser printer and an iron!! really effective one, check it out:

**broken link removed**

it's simple n useful for do-it-yourself kind of projects. Recently i tested it by making a single layer ATmega32 experiment card. it took 2 hours for etching (i didn't steer the liquid frequently). U can check my board design here:

http://dharmanitech.blogspot.com/2008/08/make-yourself-atmega32-starters-kit.html

Enjoy!
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http://dharmanitech.blogspot.com