getting frustrated with etching. halp.

[Zilla]

I've been etching aluminum enclosures for about a while and I'm starting to get very frustrated. i'm hoping there's something obvious that i'm missing here.

i've done the toner transfer method using magazine paper, presentation paper, and PNP blue and i seem to get fairly good transfers.  I prep the enclosure by sanding up to etiher 220 or 400 grit. clean with alcohol before toner transfer. pre-heat the enclosure a bit before placing the paper and then using a hot iron.

When i peel off the backing paper, i fill "solid" areas of toner with nail polish "just in case" but i can't get nail polish into the text because the details are too fine.

After etching, i STILL get pinholes throughout areas that have toner AND nail polish on them even though there are no visible holes, and then the areas around any text look "dirty" because it looks like the ferric chloride makes it's way through the toner.

I'm using MG Chemicals ferric chloride. it's ready to use out of the bottle.  I etch for about 15-18 minutes to get a good deep etch.

This happens regardless if i'm using PNP blue or magazine paper.  The only way that i've been able to get a nice clean etch is if i use a vinyl mask.

I'm at a loss now.  Is the ferric too concentrated and it's blasting through?  Should i dilute it?

halp.

[R.G.]

Laser printer toner is highly printer specific. Getting enough density of toner for what amounts to optical or chemical resist is difficult. Often there are simply pinholes in the original toner and the iron-on doesn't fill them.

I've heard of people exposing toner-printed surfaces to the vapor rising off a container of acetone to "smooth" the toner layer. Acetone is a FAST solvent for toner, and the vapor may be enough to slightly melt the toner on the enclosure and fill pinholes.

Maybe.

[Zilla]

R.G.,

I expect a difference between optical transparency and chemical resistance, but what I don't get is even areas that i cover with nail polish will still develop pinholes.

With PNP Blue i've overlaid the film after i've etched and removed the resist and i cannot see any leftover pieces of PNP Blue on the transfer paper where i have pinholes.

I've seen demo videos from various people on here and FSB showing their results and i can only seem to get comparable clean etches when using a vinyl mask, but then i have issues with the vinyl cutter not being able to reproduce fine details...

[R.G.]

There are lots of variables. One big one is how well the enclosure is prepped before applying the toner. It's another possibility.

For clean toner etches, the toner has to stick to the enclosure surface tightly enough to exclude the etchant. If there are microscopic bits of dust or oil keeping the toner from adhering, you get pinholes. Likewise if the enclosure surfaces is too smooth for the toner.

This is speculation based on experience with toner, etching, and painting over a few decades. You might try first using very fine steel wool on the enclosure first to get a very finely scratched surface. Then degrease, clean, degrease, degrease, clean, degrease, using only gloved hands. Then apply toner. Then etch.

As another variable, you can reheat the entire enclosure just to the point the toner softens, or try acetone vapor. Then etch.

The practice of doing old silver-based B&W photography with chemicals and trays was a GREAT intro to how to make surface treatments work first time every time. It was very demanding of consistency, and showed you your mistakes clearly.

[Zilla]

R.G,

I am very familiar with photolithography having worked in a micro- and nano fabrication facility.  This is why i am getting so frustrated as to why these pinholes keep forming on areas that have toner+ pnp blue backer + nailpolish layers.

[R.G.]

You're far beyond my expertise then. What are you using for etchant?

[Zilla]

http://www.mgchemicals.com/products/prototyping-and-circuit-repair/prototyping/ferric-chloride-415/

I've tried emailing MG to see if they have any etch rate information or the concentration information but they either don't have it or won't share it with me.

[Beo]

Etch long enough, and it'll get through anywhere the resist is weakest. I agree, around text is the hardest. I've found toner type is a big deal... brother is a no-no, Canon and Samsung OEM toner is better. Nail polish has been solid for me, tape works well too... maybe try some different types of nail polish on scrap. Consistent heating and pressure is impossible for me... I use a laminator for PCBs which works great, but PCBs are flat, enclosures pretty much never are, no matter how much you work it. The edges/corners don't get nearly as much heat (thicker) and are hard to get details on. I dab on solution with a sponge brush instead of immersing, brushing to clear residue, and I expose a little less time around text... more shallow etch, but cleaner. Tried NAOH a few times and I like it... goes fast.

I can't do the superstar pristine etches. My best have been reverse etches (less toner), fatter font (can still read the letters), and graphics that will look good roughed up. Tattoo outline art looks good, even if edges get eaten into. Rustic / post-apocalyptic themes look fine with blemishes.

Aside: My wife just painted all our nice darkwood bedroom furniture with some kind of off-white chalk paint, and then scuffed them with sandpaper for a distressed look. Not my thing... but a smart idea when it comes to more forgiving enclosure etches. Make the defects part of the design.

Last aside: Perfect is the enemy of good. I've lost a lot of the limited time I have for this hobby trying to master perfect etches and enclosure graphics. This is still a problem for me, and has prevented me from completing a lot of builds. Don't let it hang you up too much.

[Zilla]

I've been using original hp timer for all my etches. My toner cartridge is on its legs and it's time to get a new printer because it's cheaper than getting a new toner cart. Was thinking about a Samsung.  Are these known to be good for toner transfer?


All good points beo. Perfection paralysis is a killer.

[Adhesives Assistant]

http://www.mgchemicals.com/products/prototyping-and-circuit-repair/prototyping/ferric-chloride-415/

I've tried emailing MG to see if they have any etch rate information or the concentration information but they either don't have it or won't share it with me.

Hi Zilla,

We are a distributor for MG Chemicals based in the UK, if we can be of any assistance you can find us here:

http://www.techsil.co.uk/manufacturer-s/mgchemicals

[Mandobird]

I use a HP LaserJet Pro P1102w, and the toner holds up well enough for etching.  I previously used a HP Laserjet 1100, and the toner was weaker.  The difference is the P1102w has a toner density setting (the 1100 doesn't), which I set to maximum thickness.  I guess a printer with a toner density option (whether it's HP or not) will be more likely to provide thicker tone, and hopefully a cleaner etch.

I sill don't get the consistently super pristine etches some achieve (like me you may need nail varnish or tape over the toner to stop pitting) - this may or may not be due to the toner (there's so many variables with etching, and so many things can go wrong).  But using the 1102w definitely helped me get some much better results - I'd recommend it.  It's fairly affordable, and not too big - I bought it having read this guide, which also recommends it:
http://music.codydeschenes.com/?page_id=2035