Best etching chemical quetsion

[Ice-9]

I have just ran out of ferric chloride crystals for etching PCB's and as I have to now buy some new solution/crystals.  I was thinking of getting a different type, maybe better for the environment and easier to dispose of etc. I use photo resist board and sodium metasilicate to develop the boards. I was looking for some advice on an etchant to use, I don't really want to be looking for chemicals that i have to find in different places and mix together I just want an all in solution, but all ideas are welcome.

[KazooMan]

I don't have an answer, but I am very interested in this issue.  I am a hobbyist and don't make many boards, but I soon realized that the ferric chloride waste was going to be a problem (I am a chemist by training with long pharmaceutical industry experience).  I switched to persulfate as an etchant and was satisfied.  However, I had been using the laser printer transfer method and then decided to try the photosensitive boards.  What a revelation!  So much easier to do and better results.  From what I had read it seemed that these boards needed ferric chloride, so that is all I have used.  I would really like to use either persulfate or another method such as the hydrogen peroxide based systems to minimize (not eliminate) the hazardous waste issues.  I guess I should get back to my roots as an experimental scientist and do some testing, but it would be nice to learn that someone has already made the key discovery!

[davent]

Hydrogen peroxide/muriatic acid has always worked fine for etching the photoresist boards i've done. Just mix up enough to cover a board as needed.

dave

[Ice-9]

Hydrogen peroxide/muriatic acid has always worked fine for etching the photoresist boards i've done. Just mix up enough to cover a board as needed.

dave

Can I ask what strength of Hydrogen peroxide do you get, I ask this because It is available in the Uk and we can get it as a bleach for hair color remover or a mouth wash so I expect there is a massive difference in strenth ?

[Taylor]

I buy 40 volume clear developer from a beauty supply store. This is high concentration hydrogen peroxide - I forget what percentage 40 volume equates to, but I think around 30%. The drug store kind used for mouth wash or cleaning cuts is 3%. I water it down - more economical, otherwise you're paying mostly for water.

Just make sure - if buying from a beauty supply place - that you get clear developer, not cream. The cream is, as you'd expect, a glorpy milky stuff with all kind of oils, etc. in it.

[davent]

I'm just using the lowly drug store dilution but will have to check out the beauty supply store around the corner for the good stuff.

dave

[spargo]

I use ferric chloride, but instead of submerging my boards in a gallon of the stuff I soak some into a sponge and wipe at the boards.  It etches in a few minutes and the cleanup is what's left in the sponge vs. a whole container of the stuff.  Much neater!  I just rinse the sponge in a tub of water so it's extremely diluted and then flush it.

[salocin]

I use ferric chloride, but instead of submerging my boards in a gallon of the stuff I soak some into a sponge and wipe at the boards.  It etches in a few minutes and the cleanup is what's left in the sponge vs. a whole container of the stuff.  Much neater!  I just rinse the sponge in a tub of water so it's extremely diluted and then flush it.

i assume you don't heat the ferric chloride?

Personally I use ammonium persulphate in a pyrex glass dish over a small gas burner with a digital thermometer submerged to monitor temperature. Have also been wanting to experiment with other options though

[spargo]

I use ferric chloride, but instead of submerging my boards in a gallon of the stuff I soak some into a sponge and wipe at the boards.  It etches in a few minutes and the cleanup is what's left in the sponge vs. a whole container of the stuff.  Much neater!  I just rinse the sponge in a tub of water so it's extremely diluted and then flush it.

i assume you don't heat the ferric chloride?

Personally I use ammonium persulphate in a pyrex glass dish over a small gas burner with a digital thermometer submerged to monitor temperature. Have also been wanting to experiment with other options though

Nope, it's room temperature.  The board will usually etch in a couple of minutes with this method.

[markeebee]

I use sodium persulphate, mostly because it's clearish (actually goes a nice blue colour) so it's easy to see when a board is finished.

Kinda reminds me of Mrs Bee - cheap, strangely pretty, doesn't smell too bad, takes a while to warm up but is quite efficient when it gets going.

[johanp]

I have no experience with PCB etching, and no insight in chemistry whatsoever, but I did find a procedure in which you can re-use the etchant numereous times, so you don't have to throw it away (Something to do with the oxigen that "re-activates' the etchant).
So it's better for the envirnement, and you can make it with two easy to find ingredients (hydrochloric acid and hydrogen peroxide).
No idea how good it works though.

http://www.instructables.com/id/Stop-using-Ferric-Chloride-etchant!--A-better-etc/

[snakey]

ammonium persulphate in a small aluminum tin that i heat with an oxy and shake with a rag over my hand .

[chicago_mike]

Just remember to do the persulphate method outside and keep the muraic acid away from metals. I have a garage full of rusty stuff because of the acid fumes. 

[milosch]

I used muriatic and over-the-counter peroxide with good results, at least on the first round.  I melted a penny in it and then it was ready to go.  However, when I moved recently I decided I didn't want to have that nasty acid around anymore so I gave it to the yard man.  Hopefully he found a use for it.  I would consider going this route again but am back to the usual chemicals.  I also do laser printer to photo resist boards.

[Perrow]

I use ferric chloride, but instead of submerging my boards in a gallon of the stuff I soak some into a sponge and wipe at the boards.  It etches in a few minutes and the cleanup is what's left in the sponge vs. a whole container of the stuff.  Much neater!  I just rinse the sponge in a tub of water so it's extremely diluted and then flush it.

I guess you read this one on contact etching.