Mixing Ferric Chloride from Powder (Maplin)

[Deano]

I'm looking to etch my first PCB soon and I have bought some FeCl from maplin in a powder/crystal form.
It says that it will make 0.5l of solution.  Shall I mix the whole batch together and store it in a plastic bottle for later use, or should I mix only enough for what I need to use at the time?  I plan to use a tupperware box to etch in.  I read somewhere that the crystals can give off quite a bit of heat when mixed/ re-hydrated.  Any tips?  Should I use boiling water to mix them with or use cold water and stand the tupperware tub in a bath of hot water to speed etching?

[MikeH]

I'd mix with warm water.  And I don't see any reason not to mix the whole batch. BUT!!- remember; ALWAYS add the acid to the water; pouring the water into the acid will cause some pretty exciting, but bad, things to happen.

[MohiZ]

I don't intend to steal this topic but while you're at it:

Hey, out here where I live I haven't been able to locate any solution form of ferric chloride whatsoever, and all I can get are these weird grains that you're supposed to dissolve into water. Does anyone know what's the concentration supposed to be? I'm thinking I put too little of the grains into water because the etching is so devilishly slow, but I don't want to use more than is needed, either.

Here's a picture: http://www.partco.biz/verkkokauppa/images/tuotekuvat/f/ferrikloridi-large.jpg

[Ripthorn]

I mix mine in batches (just enough for however many boards I will do) and use a 60W light bulb over the top to keep it warm.  Also, agitating and etching with the board suspended face down in the solution will help.  I mix into warm water and just kind of estimate (e.g. use about half the powder in about .25l of water).  It has worked well for me thus far.

[newfish]

Hi,

I too have the powder from Maplins.

I mixed half my powder into half the amount of warm water.  From memory I think I used about 50ml water.

I keep mine in an old medicine bottle (washed thoroughly...), and simply pour our as much as is needed into a small plastic tub (from an Indian Takeaway, would you believe).

I keep *this* tub warm during etching by floating it on a larger tub of hot water, but have also been known to put the takeaway tub on a USB cup-warmer - which also does the job.

Good luck with your etching, I'm sure you'll get the hang of it.

p.s. Warming your boards before immersion can also help.  I leave mine on a radiator (flat, face down) for 10 minutes or so while I prepare the etching bath.

[MikeH]

I keep mine in an old medicine bottle (washed thoroughly...), and simply pour our as much as is needed into a small plastic tub (from an Indian Takeaway, would you believe).

The spice residue helps speed up the etching.  Sometimes I just order the extra-extra spicy curry and etch my boards in that 

[newfish]

The spices add extra Mojo.

...seriously...

[gez]

Rapid sell a 'safe' etching system.  All it comprises is a long, plastic bag, some clips to isolate the board from the etchant at various stages, and etchant.  Might seem a bit of a rip-off for the money, but the etchant seems to be a lot better than the stuff that Maplin sell (and everyone else - it's all made by the same manufacturer).  The etchant that comes with the kit looks different (it's lighter) and appears to be more efficient: I've etched using bags for a while, but the Rapid stuff does the job quicker.

Just thought I'd mention it.

[Boprikov]

Tape "handles" as in this picture make it easy to follow the etching process.

http://web.telia.com/~u85920178/data/pcb-etch1.jpg

By occasionally lifting the pcb up you can see when it is ready. Occasional lifting also breaks possible air bubbles under the board. Bubbles can leave round, un-etched areas.

[rnfr]

i mix mine per batch at about 1:3 powder to water ratio, then put on rubber gloves and rub it in the etch with a sponge.  sometimes i'll let it soak a bit before the rub, but this speeds up etching profusely.  it seems as if you can rub the copper right off once it's been soaking a bit.