I have a project with a glass PCB (novelty value, nothing more) that requires etching by hand. I'd like to try a UV reactive product, but was wondering if anyone had experience with various cheap press-on films or the more expensive liquid products.
There used to be a spray on window tint, but the last time I saw that was 50 years ago, not sure if they still make something like that.
Use acrylic or PVC sheet.
Etchants for glass are highly corrosive, and effing bloody dangerous, not for amateurs.
Hydrogen Fluoride and so on, read up then decide.
We do get UV protective film for windows, Garware used to make them, and Far East sources are there.
Basically polyester film in different colors and finishes, to be applied to a cleaned surface. They had water activated adhesive, and a release film.
Common for cars here, until the government changed the rules.
Old product, read up.
Etchants for glass are highly corrosive, and effing bloody dangerous, not for amateurs.
Hydrogen Fluoride and so on, read up then decide.
We do get UV protective film for windows, Garware used to make them, and Far East sources are there.
Basically polyester film in different colors and finishes, to be applied to a cleaned surface. They had water activated adhesive, and a release film.
Common for cars here, until the government changed the rules.
Old product, read up.
I'm not etching the glass; I'm etching the copper on the glass. Just need regular PCB film.
How will you bond the copper to the glass? How will you stop the glass cracking when you solder it?
There's no reason standard PCB photo resist couldn't be used, its only the copper that's involved in etching
and glass is very inert, but the bonding and thermal issues might be show-stoppers.
There's no reason standard PCB photo resist couldn't be used, its only the copper that's involved in etching
and glass is very inert, but the bonding and thermal issues might be show-stoppers.
I searched glass bonded copper, turned out glass epoxy laminates...which is a much more likely material for a PCB.
Which is why I asked for a photo, for some the difference between Phenolic and glass epoxy is unknown.
Which is why I asked for a photo, for some the difference between Phenolic and glass epoxy is unknown.
Do you already have copper clad glass sheet?
Will you make you own?
If so, epoxy will stick copper to glass, provided both are very clean, you work with surgical gloves, etc.
Remember etching will remove copper but still leave behind the cured Epoxy layer, which will be thin and translucent but not transparent, that might degrade a little the visuals you are trying to achieve.
Given that, any photopositive or negative emulsion, dry sheet or liquid, will work like on any regular PCB, because it will be applied over copper in any case, it does not know or care what lies "on the other side" of the copper sheet.
As mentioned above,drilling will be a problem.
Maybe a plain hard metal bit designed for epoxy-glass PCBs will work, probably under a constant water jet.
Maybe you design it so all or 95% of pads are no hole SMT type.
Soldering should be achievable.
Provided you are using real glass sheet:
Thin wrinkle free copper foil, about 100 microns.
Use the epoxy used for sticking handles to glass doors, it is clearer than most other epoxy grades.
Clean surfaces really well before bonding.
Tungsten carbide and diamond drills will work, use glass drilling techniques.
Soldering, don't linger too long in one place.
Thin wrinkle free copper foil, about 100 microns.
Use the epoxy used for sticking handles to glass doors, it is clearer than most other epoxy grades.
Clean surfaces really well before bonding.
Tungsten carbide and diamond drills will work, use glass drilling techniques.
Soldering, don't linger too long in one place.
Turns out all you need is a lot of trash and some paint thinner. It's prefab copper-plated glass - just a mirror. Copper is plated over aluminum, and I'm plating some more copper over the copper.
Can you recommend a user-friendly UV film? Also, are there any particularly hard films that might stand up to a bit of walnut blasting? It doesn't take much to eat through a few microns of copper.
Get a flexible PVC PCB from somewhere.
Who told you it is aluminum?
It is usually silver, aluminum and copper cause galvanic corrosion in each other.
Also explain how you gain by putting a circuit behind a mirror. Which is opaque.
I told you to put 100 micron film on glass, and you get a mirror from the trash!
If this is your competence level, include me out...
Who told you it is aluminum?
It is usually silver, aluminum and copper cause galvanic corrosion in each other.
Also explain how you gain by putting a circuit behind a mirror. Which is opaque.
I told you to put 100 micron film on glass, and you get a mirror from the trash!
If this is your competence level, include me out...
In no particular order but maybe some of this helps:
I make my own front panels and PCBs by silk-screening, don´t directly coat copperclad boards but the screens instead and although I might use dry film emulsion, so far only used liquid type.
But chemistry is the same, product is "about" the same and silk-screening has been used for selective surface-blasting for artistic purposes (protective coat is later removed chemically) for a long time so your idea is technically sound.
Sad I can´t give you a specific dry film brand, but again, it´s doable.
Walnut blasting is quite "light" , I have seen it done using much harsher sand or glass micro-spheres blasting and it worked very well .... of course don´t stay doing it so long that you sandblast everything out 🙂
Photosensitive films/emulsions such as used in silk-screening can get a hardening bath at the end of the process, T Shirt and textile printers do that routinely so screens stand LOTS of printing without damage, problem is that later you can NOT reclaim the screen with bleach, not sure It may bother you or not.
Meaning in your case it would be quite harder to remove the now hardened film.
Again,maybe you don´t actually need hardening for your relatively mild blasting.
Like always, experimenting rules.
I would buy 1 or 2 printer size sheets of dry emulsion which is available in your area, apply it to copper surface following Factory instructions and experiment.
Try different adhesion techniques, exposure times, hardening, etc. in half palm sized plates, then choose best for you.
Good luck 🙂
PS: not sure about the aluminum backing: ferric chloride etches copper and zinc well, but very poorly to aluminum.
And a wall to wall aluminum coat will "short everything" if remaining, even if microns thick:if it was conductive enough to take copper plating, it´s conductive enough to ruin your project.
BUT aluminum readily dissolves in a strong alkaline bath, I use "caustic soda" (sodium hydroxide) to surface etch my aluminum panels prior to painting or simply give it a surface similar to fine blasting.
Again, experimenting/testing RULES.
I'll give the sodium hydroxide a try. Isn't it also used to develop PCB film?
Which emulsion are you using to make PCBs?
Aluminum mirrors are pretty easy to tell; they look different from silver mirrors.
In any case, ferric chloride reacts with silver enough to etch through the microns of silver on the mirror.
And if it doesn't...well, this wouldn't be my first time using nitric acid on silver.
The film on glass looks terrible and the adhesives required are expensive. There's tutorials on Youtube; it's crude.
As for "Why?" the answer is "because I can." It's a decorative application; soldering to glass is just to prove it's possible.
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Photopositive PCB film developers are light alkaline solutions, think a spoonfulper liter or less; solutions to etch out aluminum are much stronger.
They may damage emulsion/film but since it would be at the end of the process, no big deal, since you will have to remove emulsion anyway to expose copper, which is NOT damaged by alkalines.
I use standard commercially available Silkscreen emulsions, a local brand so it won´t help you but "all are the same", so any regular one you get will be fine.
Again, experimenting is the key.
Nitric acid is the "universal" etcher, he he, so it will always work.
Just use it diluted so it´s not too fast and be aware that it often creates small bubbles on metal surface (I think those are Hydrogen bubbles) so have a small nylon bristle brush ready to remove them if needed, or you´ll end with small un-etched spots.
They may damage emulsion/film but since it would be at the end of the process, no big deal, since you will have to remove emulsion anyway to expose copper, which is NOT damaged by alkalines.
I use standard commercially available Silkscreen emulsions, a local brand so it won´t help you but "all are the same", so any regular one you get will be fine.
Again, experimenting is the key.
Nitric acid is the "universal" etcher, he he, so it will always work.
Just use it diluted so it´s not too fast and be aware that it often creates small bubbles on metal surface (I think those are Hydrogen bubbles) so have a small nylon bristle brush ready to remove them if needed, or you´ll end with small un-etched spots.