This is part two in my three part series about design cycles on glass circuit boards.
If you're curious about how I came to find out about the problems that I'm solving here,
click video one to your left.
If you'd like to find out how to populate these boards, click video two.
If you're curious how I actually print the glass circuit boards, just keep on watching.
In this video I use ferric chloride and potassium hydroxide and I do not go over safety measures
necessary when dealing with these chemicals, so please use other resources before attempting
PCB manufacture.
So, I found the problems with the board, and I corrected them.
So, now I can export as a postscript file.
This is a vector format which isn't useful for a lot of things, so I imported it into
gimp.
You can use just about any editor, photoshop or whatever.
Grayscale and a little bit of anti-aliasing really helps out.
Grayscale makes it so it takes up less space.
I crop it.
I invert the colors because I'm doing a negative process and I flip it so I can put the toner
side down.
Then I can re-save it off as a useful format.
In this case a PNG which can be easily dropped into openoffice here and I can make multiple
copies.
Always make multiple copies of boards if you can fit it at all because you'll always mess
one or two up.
It's just easier to make a bunch of copies and throw stuff out when it doesn't work out.
I go set up to print and print as dark as I possibly can.
The night is your friend.
And, in this case I'm using a $37 laser printer.
This is a pantum laser printer.
It's really cheap and it produces great prints.
Now, what I do is I take my glass.
In this case I'm using these microscope slides.
But, I have printed much larger pieces.
Microscope slides are just convenient because they're pre-cut.
And, I use acetone to de-grease.
There are better de-greasers.
But I'm not really that good at engineering to know which is which.
I use copper from nimrod-hall.
This is just 1 mil, or 1.4 mil copper and I sandpaper it, err sorry, steel wool.
Steel wools makes it so it has a really nice sheen to it.
It has this anisotropic effect and it also seems to help the glue stick better.
So, always always always sandpaper and try to do so in a uniform direction.
This Loctite 3301 is just amazing.
I had used several different types like many types of glues, and I finally settled on this
one because it has a very low viscosity which makes it easy to squeegy it to the edges and
it's resistant to the potassium hydroxide that I use later on in the process, whereas
other materials will just disintegrate immediately when they come in contact with it.
I can put the microscope slides face down and squeegy them around.
Conveniently you can seen in the back there where any bubbles are and you can apply force
on those bubbles in order to get them to the edges.
And uuh just kinda squeegy them on and squish them on and then black them with UV light.
I use a pretty easy to use grow light and I just blast it for a couple minutes.
A lot of people use this in the sun to cure.
Uuhh I don't know.
It's whatever goes I'm sure you can find something as long as it's emitting enough UV light.
I'm cleaning off the boards here so you don't have quite as much residue.
Now once that's done, not all of the material is going to be complete cured but it's enough
to hold all the copper on really good.
I also fold the copper down around the edges so that I know the limits of where the glass
is underneath.
This helps with positioning later on.
So, for each one of these I'm flipping them over and adding a little bit of creasing.
So, now we're at the point where we basically have a circuit board.
And, it's time to do the rest of the process which is pretty much the same as any other
circit board.
So, I clean it off and I use Riston, just like I do on my regular circuit boards.
Riston is a gel before it is exposed, it's kinda just a gel.
But, once it's exposed to UV it becomes a plastic.
So, it has a protective coating on both sides.
It's what I'm pulling off here.
And many times.
Sometimes it does get caught, so many times what I'll do is I'll use much larger sheets
and cut it back after I've peeled away.
In this case I've just decided to cut them individually.
No real reason why.
And you just peel off the protective coating, just kinda pulling at the edge.
Yeah.
That peelin' feelin' if you've ever seen that subreddit.
I use a little bit of water on the slide before I apply the Riston.
And that prevents it from sticking unevenly and makes it so I can kinda squeegy it around
and push it around in order to get it really flat.
And uuh just a little more water and applying the Riston.
So it starts to stick even though there's a little bit of water there, but it doesn't
really stick until after it goes through the next step here where I put it through the
laminator.
The laminator really helps to set the Riston.
So, look at this piece of history here.
I think it's pretty cool that I still have this scrap paper left over from '95.
But, you might not.
I'm sure this is older than some of the people who are watching this right now.
So, I take the uuh pieces and I slide it into this holder.
And the reason you do this is the Riston itself will gum up the laser printer, but if you
put it inside a little sheet of paper like that it prevents you from damaging the la...
I'm sorry - the laminator.
So, I put it through.
I normally do Riston up once and Riston down twice.
I've tried a number of different combinations.
That seems to be what works best I'm not really sure why.
Just it just is.
One other note I forgot to mention.
The water.
Make sure it's cold water.
Because if it's hot water, it can have little bubbles in it which can cause all sorts of
problems later on.
You want it to really not be bubbley water.
So, you take the circuit board with the Riston applied out.
The Riston still has a protective coating on it and it's still gel.
It hasn't been cured yet.
I am just cutting around the outside edge now.
Sometimes I'll pull off the protective coating before cutting.
Either which way.
It really doesn't matter that much as long as at the end of the day, you have basically
a circuit board with Riston applied.
Umm once it's applied, you can start to peel off the protective coating ontop of the Riston.
And it just peels off.
Both sides of the Riston have the protective coating on them.
Prevents it from sticking to everything.
It's really sticky gel.
Once you have the top off of all three here.
We need something to prevent the transparencies from sticking to it.
I use 3-in-1 oil.
I've seen some people - some other people have mentioned olive oil.
I really want to try that some time, see if it's any better.
So, I take the transparencies and I cut them to suit so they're about the right size.
So I cut around what's black, and then what I'll do is I'll take the 3-in-1 oil and dab
it on the Riston here.
By making it not stick it creates a very good interface.
And by making it not stick it creates a very very good interface.
It doesn't have much of a change in index of refraction so you get more uniform exposure
as compared to a just a regular air interface.
It also makes it less sticky and easier to get off later.
It's much more convenient to apply.
So, once all of these are nice and squeegied down.
All the air bubbles out.
Blast it again with UV light.
You'll really have to change the exposure time based on uuh the environment you're in
and distance to light and how bright your light is.
For me, it's about 3 minutes.
And, I get the water moving just for the next step of this.
Once it's exposed for the three minutes then I can go and take some water.
This is warm water and put in some washing soda.
Washing soda is not what I used to use.
I had a problem, and I found the problem was that I had been using way too much washing
soda by concentration before.
So, by having very little washing soda by concentration it develops really nicely.
It's actually better than the sodium bicarbonate I used before - the baking soda.
So I do recommend doing what the datasheet for Riston says and actually use washing soda.
What this does is anywhere the Riston is still a gel, it just washes away.
Just wipes away.
But, anywhere the Riston has been exposed to the UV light - so anywhere that's clear
on the mask - it's turned into plastic which the sodium - the sodium carbonate will not
eat through.
And what this does is it protects the copper underneath all the plastic areas from this:
Ferric Chloride.
Now, a lot of people really doesn't like ferric chloride.
I'm not sure why.
For me I found it definitely to be the best.
I've tried a couple other chemicals - including the citric acid ones and sodium perchlorate
and never really messed much with the cupric chloride but um whatever.
I have a landfill I can just take used ferric chloride to and it's $34/gallon which lasts
me like a year.
Any rate.
I can then take this, dump it back and forth.
And I use a sponge to take it back and forth and wash away all the copper that's interacting
with it and you can start to see through.
Straight through the glass circuit board there.
So, everywhere that there's the Riston that's turned into plastic the copper remains and
everywhere that it's not the ferric chloride has been able to eat right through and kill
all the copper.
Once all this is done, I can store the ferric chloride sludge.
It also has mixed in copper - copper sludge.
So you REALLY DON'T WANT TO PUT THIS DOWN THE DRAIN.
You really don't want to put this down the drain.
But it's totally fine to take to whoever takes your hasmat materials and everything else.
So, I just dry it off.
Everything's just standard.
Just dry.
And then you still have to take off the excess Riston.
So, right now underneath these parts here is copper.
You can still see the purple sheen and that the Riston.
And I use potassium hydroxide and the reason behind that is and odd one.
Instead of using sodium hydroxide is because the potassium hydroxide doesn't seem to bother
the loctite 3301, at least in the concentrations I'm using it.
So, it's really important to find a chemical that will eat away the Riston that's on top
of the copper but not eat away the glue that's holding the copper to the glass and that's
kinda been the big thing that's stopped me from taking off with these circuit boards.
So, I can then just kinda wipe away.
You can just see it peel off, come away, the Riston and exposing this beautiful bare copper
board.
Uuhh then I just rinse them off.
Sometimes I clean them off a little more.
I don't use acetone whenever I'm finishing off my circuit boards here, for glass.
Because acetone will eat away the loctite material underneath.
It's really sad.
I love using acetone to clean off my circuit boards, but it's just not possible when you're
using the loctite on the glass circuit boards.
So, once that's done you can just pour that down the drain.
It's analogous to drain cleaner and everything I found online indicated it was just fine
to pour down the drain.
So, now you can see the beautiful glass circuit board.
This is a complete uuh microscope slide-sized circuit board for the ESP8266 project.
You'll notice there's kinda a film around the outside where the Loctite is bound up
around the edges.
Conveniently, though that peels away really easily.
Uhh just clean that up and you're left with a beautiful circuit board there.
One of the problems that I sometimes run into is I try to push my traces all the way right
up to the edges and unless when you're applying the transparencies - if you're not spot on
sometimes you'll have a little bit of a trace go over the edge and the one I decided to
go with, the one that I decided to use for this, it did have a little bit of copper go
over the edge.
Thanks for watching how the glass circuit boards are printed.
Now, check this next video to see how I actually make them and get them working.
So, it's still kinda murky you can't quite see crystal clear through it so uhh one last
step here.
We're going to go spray this thing with polyurethane.