Five Minute Etching

[MartyB]

There's really no reason to heat the ferric chloride or its container in your microwave.  If you are using small (20cc) amounts of etchant in a ziplock snack baggie, you simply immerse the baggie in your tupperware tub full of tap-hot water. Agitate till visibly etched.  That's it.
Martyb

[Johnny G]

i know that this question has come up multiple times on the forum but what are you guys using to put the etch resist on? transfers/pens or what.

[Paul Perry (Frostwave)]

Etchant is an alkali and is removed with an acid rinse, after rinsing the board in water, place it in a shallow tupperware container, pour in 1/4" of vinegar, and scrub with an old toothbrush, rinse in water and repeat..

The etchant (if you mean Ferric Chloride) certainly ISN'T an alkali!!!
but, I agree entirely that it is well worth making an effort to scrub the board after etching. That vinegar IMHO is doing squat.
The important thing though, is you have a method that WORKS.

Where does this 'vinegar' conceprp come from? maybe from the photosensitised boards which ARE developed by an alkali, caustic soder to be precise.

[Brian Marshall]

(start of rant)...

Nope, that's all a bunch of BS, just extrapolation by psuedo-logic.

Put it in the microwave ...WITH THE LID ON... you will get no leakage or contamination WHATSOEVER, I've been doing this for a few years now with absolutely ZERO effect on the microwave.
(sorry Brian)

Well you dont need to be sorry if you dissagree, but I am not really concerned so much with the microwave, as i am concerned about your health.  it is not a bunch of BS.  Ever notice that when you put a glass of water in the microwave it ads a certain nasty flavor to it... that is little bits of taste of other things you have cooked in the microwave.

When you put something in the micorwave it heats at the molecular level... which ever molecule happens to get hit by radiation heats up a lot.... often if it is water it is hot enough to be at the boiling point.  You dont see it boil because it ends up dispersing its heat in to all the colder molecules arround it.  This is why your microwave often will not heat things evenly... some parts are still cold and others are piping hot.  Any sort of liquid can easilly become vaporized in small ammounts even if it doesnt boil.  Tupperware is not necessarilly air tight when it comes to letting air out of its seems.  

Perhaps if you only do it once an a while it isnt that big of a deal, but I etch a lot of boards.  One thing i will say is that if you ever spill any etchant in your microwave, dont try cooking food in it again.

Try this sometime... leave some etchant in a pan arround some metal objects... leave it uncovered for about an hour, and then seal it up or pour it back in to its container.  Come back a couple days later and you may notice some rust or corosion on the metal objects.

[David]

best way (only way) to heat it, is in an indirect water bath.
with the "tuperware technique", U could seal the tupperware,
and immerse it in a sink of hot water 4 a while.
tone

I tried the hot bath thing tonight with those partners in crime, muriatic acid and 30% peroxide.  I also shined a halogen lamp down on the acid mixture as I etched.  Since I keep the evil twins in the garage, my mixture was cold, which retarded the etching for a while.  When the solution warmed, the reaction sped up.

Just as an experiment, I kept the top of my inner etch container off -- and yes, I was in the house.  Probably not too smart, but it worked OK this time.  Anyway, I was able to see the last pieces of copper flake off the board and remove the board immediately thereafter.  Looks good!

[Dragonfly]

i know that this question has come up multiple times on the forum but what are you guys using to put the etch resist on? transfers/pens or what.

many people use sharpies...but ive had FAR better results by using a black (or any color, really...blacks easy to see ) paint marker.

[KMS]

I just etched my first board ever last week with ferric Cl and did not heat it up at all. It took 15 minutes.  I used high quality copper clad board, purest copper.   I drilled a hole in one corner and made an agitating tool out of plastic tubing that snaps into the hole in the corner and goes through to the other side sticking out about 1/4 inch.  I set the board copper facing down and just move it around a little and pick it back up to look at the copper.  The copper does not touch the bottom because the plastic tool sticking out 1/4 through the board holds it up from the bottom of the glass container I used. I didn't know you can save the used ferric Cl and I didn't know about heating it up.  Thanks for spreading the news even thought it looks like many already know about it.

This forum is great!

KMS getting more knowledge everyday

[Johnny G]

hm, cheers dragonfly i might try to give it a go soon. rapidelectronics here in the uk actually has a little kit for etching in a plastic bag. also when you've finished with alltheetchant you add some powder to it and it neutralises it and turns it into a solid lump so you can throw it away easilly. i may give it a look

[The Tone God]

Ok a couple of things to run down.

Yes ferric chloride is made up with iron but that does not make it a metal. It is bonded to the chlorine and as such will not neccarily result in same behavour as iron would on its own.

I would not mix any other chemicals with ferric chloride unless you know what you are doing. I doubt adding anything else to the mix will help it out anyways.

A quick lesson in microwave ovens. A microwave over does not cook food. Microwaves are shot out of a magnatron that excite molecules in food particularly asymetrical molecules. These molecules would include some sugars, fats, and in particular water. The molecules rub against each other generating heat. This is what cooks food so in fact the food cooks itself.

Why do things not cook through even though they are cooking themselves internally ? Thats because the microwaves can only pentrate so far.

Now putting metal in a microwave will NOT cause it to blow up or anything like that although it is fun to put those AOHELL CDs in there and watch the light show. In fact you can put a bag with two metal staples spaced 2-3 inches apart and things will be okay. I do this for my own microwave popcorn. Yum. So why bring up CDs, popcorn, and metal staples ?

The popcorn plays out since microwave manufactures fire test their microwaves using popcorn bags with a ten penny nail in it. Then they see how long it will take (no if) for the bag to catch on fire. Metal in a microwave while it will not cause the microwave to blow up will superheat. I can get away with the stapes because then are shorter and spaced apart farthur then the microwaves and have little mass. So they are not affected. The CD comes into play because the metal makes close enough contact to the wall/floor of the over to cause arching.

Getting back to etching in the microwave I don't belive you are actually heating the ferric chloride or atleast not as much as you think you are. I would suspect that your in fact superheating the copper on the circuit board, unless your board is the size of a staple, which is in turn heating the ferric chloride. You could potentially superheat the copper to the point of causing a chemical fire with the ferric chloride. I would also concern myself if your board is close to a wall or the floor for arching can occur even through the container. Furthurmore worry that you are heating the air in the container too. If you are using a sealed container then you are increasing the internal pressure which may lead to an explosion. If you are not sealing the container then chemical fumes are escaping into the air which can contamminate future food.

Now know all that I think microwaving ferric chloride/circuit boards is a BAD idea.

I still support the tupperware/waterbath combo. I keep the lid off and use a plastic stick, like a coffee stir stick, to check on the board's progress. I use a utility sink which I do not prepare food in. A laundry room tub is good too.

Andrew

[toneman]

couple more thoughts thunk while thinking...
after RH's and TG's comments---
upon further reflection,
probably *is* "OK" 2 heat FeCL3 in microwave,
TG, Don't know if RH *actually* puts the pcb in the FeCL while in the microwave.  I'm thinking, by his description, that he doesn't.
The iron(Fe) is in solution, not a solid, so sparking/arcing should not occur.
Would i do it in *my* microwave?
i "might" give it a try....but, since i usually mix up my FeCl3 from
dry powder, and, since the reaction is exothermic, the mix is
hot *right away*.  &, since i use a bubble etcher & a 100W heater
& etch usually 5, 10, or 20 small pcbs, the "tupperetch" is much 2 small.
I *may* try heating the partially used solution that I have stored
in the 5gal bucket when I try the tupperetch 4 a quickie single pcb.
I used 2 B able 2 buy dry FeCL or $1 a lb.   I just paid $7 a lb for restocking my supply.  
Previously, i mentioned i "rejuvenate" my FeCL with HCL.
I've been doing this, on & off for over 25yrs.
I have an article about using FeCL as a "storage battery".
Meaning, the chemical reaction is *reversable*.. One of my "next"
experiments is to try to determine the "polarity" of the solution,
and try to reverse the polarity and take the copper *out* of solution.
That way, i can re-re-reuse the FeCL without it getting "thicker" as
happens when i add HCL(The copper stays in solution)
As for the kitchen sink or the laundry tub, i will do neither.
If U are carefull, U can probably get away with it.
And, again, 4 single, quickie pcb etch, if it's *your" sink, it's your choice.
It's not the fumes, it's the stains FeCL can leave on any porcelian surface.
Or on a tile countertop, or kitchen floor, or whereever it touches.
I recently etched some headph amps, but did not seethe MXR unit @ GGG.
I might try the mwave+tupperetch for the MXR amp.
Actually, i never really thought about heating FeCL in a mwave B4.
Thanx 4 the idea RH.
But, i'm going 2 buy a cheap Mwave & do tupperetch outside.
Already replaced my sink once.
Don't know if i'll ever chance the HCL/H2O2 in the Mwave.
But that's just me.....
There's a new Goodwill opening up soon near me....
I'll look for a large Mwave when they open....
stayetched!!!
tone

[Nikolay]

Making PCB
http://pacificsun.ca/~robert/pcb/pcb.htm

[bwanasonic]

why even perf when U can etch??

Because then you have to drill. No thanks. With the menagerie of children and small animals that I live with, I'd rather not be playing with caustic chemicals in my kitchen sink either. It's breadboard and perf for me, and if I want PCBs, Express PCB provides much better results than I could ever hope to achieve in my sink. I spent many years fiddling with trays of caustic chemicals for a living, so there is no romance in it for me now. But if I were to have some sort of "McGuyver" situation, where I needed to etch a board, I appreciate the info on baggies/tupperware and hot water.

Kerry M

[Paul Perry (Frostwave)]

That way, i can re-re-reuse the FeCL without it getting "thicker" as happens when i add HCL(The copper stays in solution)
tone

This is interesting, what happens is the cuprous chloride (only slightly soluble) forms a complex with the excess chloride ions from the HCl & goes into solution. The etchant isn't actually regenerated in any way, but maybe things work better on purely physical grounds not having crap deposited everywhere.
I remember there is a trick you can do if you have cuprous chloride dissolved in concentrated hydrochloric acid, you pour it into water and suprisingly it deposits out! as a white cloudy precipitate from memory. OK it isn't a David Copperfield trick..

Good luck with the electrolytic regenration attempt! let us know what happens, I can't personally imagine..! you'll probably need a graphite rod for the + terminal. (get one from an old D cell).

[RedHouse]

I must have posted my proceedure unclearly as I don't actually place the circuit board in the container while it's in the microwave.

1.) place container with etchant only in microwave
2.) remove the container from the microwave
3.) place board in container
4.) place container in sink, rock (agitate) and observe progress.

Paul Perry (Frostwave)
The etchant (if you mean Ferric Chloride) certainly ISN'T an alkali!!!

quite right, appologies for the mis-information there I'm no chemist.

I got that acid rinse thing from a book on prototyping circuits that I had some years ago, it said to use the 5% HCL tincture for final cleaning of ferric chloride etched PCB's, also does something to the copper surface that makes it take the solder better (or so they say). Back then I had made some PCB's that developed green corrosion on the copper at the sides of the copper traces sometime after etching, then I found in that book where the author described an etchant cleaning process to solve that kind of problem.

I think most folks don't consider it an issue because they usually solder or plate the PCB fairly soon after etching and that covers up the evidence.

The vinegar thing came to me from a friend who works with etching copper plates for a graphic arts company (dunno why they do it), he said they use Acetic acid to remove all traces of etchant, but that I could just use vinegar and get similar results.
(and final rinsing in distilled water)

It has worked for me so I thought I'd chime-in.

[Paul Perry (Frostwave)]

thanks for that RedHouse, the more tips the better, doubtless there is plenty of 'wisdom of the ancients' to be passed on to us! anyone using the vinegar, let us know how it goes. I always scrub boards with a wire brush before soldering.