PCB Etching for Dummies

[jimosity]

Well -- at least I considered myself a total dummy when it came to etching PCB a week or two ago and wanted to share my journey from being total lost about it to quickly and easily making my own boards in no time flat.

I quickly found that getting Ferric Chloride wasn't easy locally and I'm very impatient with ordering things...so I found a note on Tom Gootee's page about etching that said you could use a mix of 2:1 (Hydrogen Peroxide and Myriatic Acid).
Since I remember seeing the acid at Lowe's and most hardware stores and knew that I could get Hydrogen Peroxide just about anywhere...off to the store I went.  This stuff works incredible!
It takes about 5 minutes or so to etch an entire board, it's clear so you can see the progress and it's way cleaner to deal with than I'm guessing Ferric Chloride would be.

I've etched about half a dozen boards in the last week and populated all of them so far (Dr. Boogey, Condor Cab Sim, Rebote 2.5, Thunderchief, Krank Distortius Maximus...).
I've got all of 'em populated, but it seemed that I was missing a piece here or there for each of them, so now I'm waiting on parts deliveries.
My Dr. Boogey is complete though and it sounds AWESOME (thought I still need to tweak a trim pot here and there...)!!
I've owned several Dual Rectos over the years and this build is incredibly realistic!!   I'm betting I could use this and tell anybody it's a real Dual Recto and they'd believe me...

With that being said; I do believe that while I made the Dr. Boogey my first etching attempt, I can't say that I recommend it as the 'first build' for a newbie...I did run into a few problems (mixing up a few nf / pf cap values, which I didn't figure out until later...).
I also etched my board a bit larger than it was supposed to be because I wanted it to be easier and knew that a larger layout would fit into the box I was going to put it in.   My second build was a Rebote 2.5 delay at normal size, which is significantly smaller and more compact in the number of parts per sq. inch compared to the Dr. Boogey.

I gotta say; I had done a few projects in the past using normal predrilled perf board you get at Radio Shack and always seemed to have problems with the size of the board, my less than stellar soldering skills at the time...and just plain out messy work.
I had given up on doing any more projects until I figured out how to do this etching stuff...now I'm hooked more than ever!

Anyways; here's a blog I posted about my process and my very first etching (the dr. boogey...) with lots of pics.
http://bandslink.com/wordpress/?p=22

[culturejam]

Nice work. I see you used a scroll saw to cut your boards. I've done this too, and it works pretty good, but fiberglass wears out a blade in no time at all. Seriously, you can make about 7 or 8 cuts and the blade is bald in the center.

I find that the easiest way to cut the fiberglass is with a pair of tin snips. Then I hit all the edges and corners with a sanding block to smooth it out.

[jimosity]

Nice work. I see you used a scroll saw to cut your boards. I've done this too, and it works pretty good, but fiberglass wears out a blade in no time at all. Seriously, you can make about 7 or 8 cuts and the blade is bald in the center.

I find that the easiest way to cut the fiberglass is with a pair of tin snips. Then I hit all the edges and corners with a sanding block to smooth it out.

Thanks for the tip!
Tin snips have been added to my shopping list...

[darron]

thanks jimosity. i too tried to make the acid concoction. i went into bunnings to observe their massive isle of pool cleaners. none of them looked right and i ended up buying the only one that sounded like it had some sort of chlorine in it, because i think that was a par of the mix? every single product there had different chemicals in it. my mix didn't work very well, but it makes the copper VERY shiny. could be the peroxide

you've given me the boost i needed to search further and give it another shot (:

thanks

[Dragonfly]

Cool Blog...I think it will help a LOT of people !

[jefe]

Yeah, very cool Jim. Makes me want to start etching (been using perf for everything).

Where / how did you get rid of your used etchant solution?

[demonstar]

Never etched before but I think you've just given me a good reason to start.

Thanks!

[tranceracer]

Good Job!
On the component side, you should also clean the surface with the scotch brite and wipe with acetone, to give the toner something to bite into.  You'll get great results!

[mike_a]

Amazing job!

I'm also facing my first etching experience, and you tutorial is GREAT!

Do you find the sticker backing paper a good method?

Thanks again!
Mike.

[frequencycentral]

Excellent tutorial!

[oldrocker]

Yes Ferric Chloride can be a bit messy.  I heard the fumes from Myriatic acid and HP can be dangerous too.  I wanted to try it too though since most places arn't carrying Ferric Chloride anymore.
Etching is fun though.

[jimosity]

Amazing job!

I'm also facing my first etching experience, and you tutorial is GREAT!

Do you find the sticker backing paper a good method?

Thanks again!
Mike.

I found that if you have any of the Avery type labels and peel all of 'em off and print on the slick side of that paper, it works great.
My first transfer was done using this method; it came out a little weaker than I had hoped, but I believe that's because my toner was about out and any print outs I did were light in spots, I'm positive that had an effect.
The next board I etch, I'll try that method again since I just got a new toner cartridge.

The best part of using that paper is that when you get it ironed onto the board and then drop it in water, it's ready to come off pretty dang quick (I think I waited less than a minute)... then gently peeled it off.
Best thing with this method also is that when the paper comes off, it all comes 100% off, so there's no left over paper on the board like there is with the photo paper.

[Paul Perry (Frostwave)]

thanks jimosity. i too tried to make the acid concoction. i went into bunnings to observe their massive isle of pool cleaners. none of them looked right

Darron, you can get persulphate from Jaycar. (Dissolve it in warm water & use it warm, or it is verrrrry slooooow....
I wouldn't go messing with pool cleaner - you might end up generating chlorine gas.
Chlorine wasn't fun in the trenches in WW1, it's no fun today either.

[jimosity]

Yes Ferric Chloride can be a bit messy.  I heard the fumes from Myriatic acid and HP can be dangerous too.  I wanted to try it too though since most places arn't carrying Ferric Chloride anymore.
Etching is fun though.

I believe the fumes can be dangerous, but you have to be pretty much right over it to really notice any smell.
It's pretty dang clean of a method and doesn't stink up the place either.

[killerkev]

Yeah, look out for the fumes... Muriatic acid is Hydrochloric acid which is very toxic and oderous. Adding a strong oxidizer like hydrogen peroxide could only intensify this. Do this outdoors fot the sake of you and your family! Very intersting though! done in 5 mins? Much faster than Ferric!

[darron]

you didn't mention heating the solution at all, did you? would this be beneficial? it is for ferric chloride. i'm getting a bit sick of my FC process because sometimes it take ages before i see any results. maybe my batches have been sitting in the shop for a few years and are weak.

[frank_p]

Jim, try to find a iron that can heat more, you may not have to touch-up with a sharpie.  Then the photo paper will be much harder to peel off also.

thanks jimosity. i too tried to make the acid concoction. i went into bunnings to observe their massive isle of pool cleaners. none of them looked right and i ended up buying the only one that sounded like it had some sort of chlorine in it, because i think that was a par of the mix? every single product there had different chemicals in it. my mix didn't work very well, but it makes the copper VERY shiny. could be the peroxide

I foud my muriatic acid in the masonry department, for cleaning before covering/painting on bricks and stones.

thanks jimosity. i too tried to make the acid concoction. i went into bunnings to observe their massive isle of pool cleaners. none of them looked right

Darron, you can get persulphate from Jaycar. (Dissolve it in warm water & use it warm, or it is verrrrry slooooow....
I wouldn't go messing with pool cleaner - you might end up generating chlorine gas.
Chlorine wasn't fun in the trenches in WW1, it's no fun today either.

You already have chlorine in the muriatic acid so it's already leaching chlorine fumes.  Use that outside or in a well ventilated place.

Where / how did you get rid of your used etchant solution?

use SEARCH on this forum, you can use again the solution by adding a couple of spoons of peroxyde.

you didn't mention heating the solution at all, did you? would this be beneficial? it is for ferric chloride. i'm getting a bit sick of my FC process because sometimes it take ages before i see any results. maybe my batches have been sitting in the shop for a few years and are weak.

If you have anoff peroxyde you should not have to heat it, it's quite fast on the first run (5 to 15 mins in my case).  Note that high concentration peroxyde added in muriatic acid can be explosive. I would not mess with heat also. Plus muriatic acid is considered highly dangerous stuff.

There has been many cases of burnt skin in the respiratory organs with muriatic use.  That is why it tends to disapear from the shelves.  Wear glasses, etc...

Nice work !

[dxm1]

While it's true that anything that will eat copper off of pcb material is "dangerous", it's all a matter of degree.  In the US, muriatic acid is used to maintain the correct chemistry in swimming pools, so it's available at all hardware stores.  Products labeled as "pool acid" are typically less than 30% solutions of acid.  High mol concentrations of hydrochloric acid are certainly dangerous, and capable of burning your skin, etc.

But consider - "pool acid" is sold freely to the average American couch potato (you know, the mental giants that make "American Idol" the number one rated TV show in the country...)  There are no federal restrictions on this product.  Now, that doesn't mean that it is inherently safe, but it not plutonium, either.

For the average sized effects pcb, I use a 2:1 peroxide (3%) to muriatic acid (28%) solution.  That's 1/2 fluid ounce (15ml) of peroxide and 1/4 fluid ounce (7.5ml) of acid. Less than an ounce total.

Mixed in a small plastic container, this will easily etch 4 or 5 "ToneBender" sized boards.  Adding a little more peroxide when the etching slows down will allow another set of 4 or 5.  When I'm done etching, I dilute the mixture with about a cup of water, and add a few tablespoons of baking powder
to neutralize the acid.  At this point, the mixture is "safe" to handle, although the suspended copper ions make it extremely poisonous (especially to fish and amphibians).  If you're sure your drain leads to a proper waste treatment plant, you can flush the neutralized solution.  Don't dispose of it anywhere it may make into the environment untreated (storm drains, etc.)

The reaction with copper releases both hydrogen and chlorine gases.  Hydrogen is highly flammable (think Hindenburg), so no smoking or open flames while etching - although the amount produced by this amount of solution is trivial.  Same goes for the chlorine gas - not enough to wipe out a single WWI type trench in your local ant wars...

In short, just about anything that etches copper is by nature caustic and must be handled with a reasonable amount of care.  The byproduct of the etching reaction will contain free copper ions that are bad news if released untreated into the environment.  Use your head (and gloves and eye protection), and dispose of the used solution responsibly.

Muriatic acid and hydrogen peroxide are both cheap and readily available (at least in the US).  If you're extremely green-centered, there is no reason why you cannot save the used solution in a plastic gallon jug, and take it to the hazardous recycling center to dispose of it (probably about once a year for the average hobbyist).

[darron]

i remade a batch with new acid and it worked a treat. i went to the local hardware store and bought a massive contain of hydrochloric acid for $10. this stuff is NASTY! as soon as you open the lid fumes are coming out. i mixed it 2:1 peroxide 3% to hydrochloric acid. probably etched a pcb in about 15-20 minutes which is good considering ferric chloride usually takes more than an hour (heated) for me. i must have super thick copper huh?

the fumes smell deadly.. i couldn't be around the thing without covering my nose/mouth. my main concern isn't burns (well, except my eyes), it's respiratory and long-term damage.

half way through etching the board i submurged the glass jar of acid in factory-strength boiling hot water. the acid in the jar actually continued to bubble for hours after etching. i left it in a glass jar in a plastic bucket in a stainless sink tonight. hope it's alright! i left a lump of copper in there to see if it disappears.

supposedly this mix will just keep on working forever? http://www.instructables.com/id/Stop-using-Ferric-Chloride-etchant!--A-better-etc/?ALLSTEPS


i tried some of the unmixed hydrochloric acid for etching an enclosure. it almost bubbled all of the paint masked around the etched areas right off in 30 secs so i might try it again later watered down since it' so much cheaper/faster than FC.



i used to use the persulphate from jaycar, but then i just started stocking FC so that i could use it on enclosures. i was originally making my own ferric chloride solution from analytic grade pure FC mixed down with water.

[plankspank]

i'm getting a bit sick of my FC process because sometimes it take ages before i see any results. maybe my batches have been sitting in the shop for a few years and are weak.

Ditto here. I mixed a batch of Fe Cl a few months back and it worked great for a while; was able to etch a small board in 10-20 minutes, and the fumes were hardly noticible. I went to etch a board last week and it took me almost 1 hr. so it looks like the shelf life of Fe Cl is not that great.
     I picked up some 30% Muratic at the hardware store and will try it (with a respirator, goggles and gloves, I might add.)