Etching Issue

[Guybrush]

Hey

I've been attempting my first etched enclosure today and run into a problem. The ferric chloride just doesn't seem to be working. I followed a tutorial and got my image into the enclosure pretty much hassle free. It's been sitting in the FC for hours now and it's only etched a tiny amount. There's no heat or bubbles either.

Anyone got any ideas as to why this might be? I've been moving the container around to aggravate the FC  and taken the enclosure out a few times to give the design a scrub and a rinse but nothing really seems to be happening.

Does FC 'go off' after a while? I've had the bottle for quite some time as I've used it to etch a few circuit boards last year.

Any help would be greatly appreciated!

Cheers

[gtangas]

Try to heat the solution with a hair dryer or a heat gun. And you can't leave it there without some shaking

With time the FC looses is strength. Normally I leave the bottle open for a night after I hetch something

[pryde]

Not sure about the FC shelf-life but it HAS to be bad if it is not eating into the bare aluminum. Really no other reason it could be. Grab a new bottle at RS.

[Guybrush]

Cheers guys.

I tried warming it up but it didn't help. I guess it's just gone bad.

I'll get another bottle and hope the etch is salvageable.

Cheers!

[nieradka]

Its unlikely the ferric chloride has gone bad, we use ferric chloride baths at my work, and change them once a year, it shouldnt break down, except from alot of use, and still, it would probably just etch slow. More likely the aluminum is oxidized, or otherwise not clean.

[rullywowr]

Ensure the enclosure is clean and try warming the solution.

[Guybrush]

More likely the aluminum is oxidized, or otherwise not clean.

Pretty sure your right. I left a few days between sanding the enclosure and starting the etch.

I'm going to start again with a new enclosure. Assuming I've done the correct prep, how long should the etch take? Minutes or hours? Should I be taking it out every so often to rinse and scrub the design or is it best just to leave it to get on with it?

Thanks for your help.

[Thomas_H]

It usually takes between 15 min and 1hrs depending on the strength and temperature of the solution.
You said you've got a bottlte. What does it say about the strength of the solution? I usually do prepare it from solid FC and you will get very strong stuff mixing it with the same amount of water
But doing so might ruin your etch especially when you just drop your enclosure in. The stronger the solution the more moving and looking after that needs. Otherwise it will burn it to pieces. When etching fine structures i always use not so strong stuff so you have more time to react

[Guybrush]

Hmmm... I'm not at home at the moment so can't check the bottle but it's this stuff http://www.ebay.co.uk/itm/140621145774?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2648

The enclosure I've been working on is ruined. I think its a combination of the FC being too cold, the enclosure having oxidized and me leaving it in the cold FC for dar too long. THe Press n peel has lifted and the FC has leaked underneath. I also ruined a previous attempt by not masking the rest of the enclosure off properly. I'm learning etching the expensive way! third time lucky!

[pryde]

Dont throw them out. Just take very agressive sandpaper and sand back to bare aluminum and try again.

I use a belt sander to make short work of it but hand sanding will get the job done as well 

[ch1naski]

Took me three times to get a decent etch. And by "decent", I mean not totally ruined.



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[nieradka]

Yeah its not ruined, its a piece of metal, just sand it clean and start over. FeCl will work cold, it just takes a bit longer. I prefer it room temp, the etch is more controllable and clean. (no under biting). It can take an hour or two depending on how deep an etch you want.

For aluminum, I prefer stannous chloride. Ferric chloride is meant more for copper, dont reuse ferric chloride that you use to etch aluminum (with copper, you can do many, many boards before its spent), and make sure you have decent ventilation.

Ferric chloride works best around 35 baume (1.32 specific gravity) ,I believe higher densities will etch slower, or less reliably, at least with copper, but I forget why exactly. But the strength is impossible to know without a hydrometer, dont sweat it, for what we are doing it will be fine.   

[Guybrush]

Cheers for the info. I've never heard of stannous chloride before. All the tutorials always talk about FC. Is it the same process? Why is it better?

I've spent 20mins hand sanding the enclosure and got nowhere with it. I could buy a belt sander but it'd probably be cheaper just to but a new enclosure.

On a side note, can you use a small hand sander (like a black and decker mouse) to sand an enclosure ready for an etch or is it better to do it by hand?

[ch1naski]

Cheers for the info. I've never heard of stannous chloride before. All the tutorials always talk about FC. Is it the same process? Why is it better?

I've spent 20mins hand sanding the enclosure and got nowhere with it. I could buy a belt sander but it'd probably be cheaper just to but a new enclosure.

On a side note, can you use a small hand sander (like a black and decker mouse) to sand an enclosure ready for an etch or is it better to do it by hand?

you can use a small sander, i sometimes start off with an orbital, but make sure you finish-sand it with a block or similar sanding tool. To keep it all perfectly flat and even for transferring your design to the enclosure.

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[nieradka]

Stannous (tin) chloride is used to etch aluminum plate for printmaking and similar processes, we use it at my work.  It etchs more evenly and is a more stable reaction. I dont think it produces hydrogen gas, and doesnt produce much heat. Im not sure if it is easily available.