Hi,
on a second thought, I'm no longer sure that the projector approach is even necessary to get some simple results. Real early chips were, IIRC, exposed through a mask made out of tape on some substrate (articles say vellum, but Wikipedia is ambiguous on what that even is, but I think any substrate will do as long as its flat and UV-transparent). AFAIK glass is UVA-transparent, so it will probably work as a substrate too, at least with that photoresist I found. Granted, that isn't maskless anymore, but a simple mask should be rather easy to make that way, it just doesn't scale well to complex masks.
Scaling the mask down to die size is easy with the optics from the dismantled projector. As a test, I projected a miniature version of my cellphone screen onto the table.
I'll next order some of the photoresist and do some exposure experiments, including masking with tape.
Greetings, Martin
On Fri, Apr 30, 2021 at 6:08 PM David Lanzendörfer < leviathan@libresilicon.com> wrote:
Hi I think this one is more suitable: https://eu.mouser.com/ProductDetail/Texas-Instruments/DLP2000AFQC? qs=T3oQrply3y%252B2%252BSUG%252B1A5CA%3D%3D https://eu.mouser.com/ProductDetail/Texas-Instruments/DLP2000AFQC?qs=T3oQrply3y%252B2%252BSUG%252B1A5CA%3D%3D
The board is connected through an FQC 42 connector socket, which I'm right now unable to find online. I guess I've gotta do some more digging on Alibaba and so on, in order to get my hands on one of those.
Cheers -lev
On Friday, April 30, 2021 3:34:10 PM WEST Martin Geisse wrote:
Hi,
I'm not sure who would be interested in buying a cheap makeshift spin-coater since you cannot get anywhere with just that, and it's super-easy to make yourself. For somebody who wants to make their own chips, a much more interesting target would IMHO be a development board
for
the DMD chip, even if it is nothing more than power, capacitors and a pin header for everything else. The DMD chip has an LGA package, and another one I found at TI has a PGA package, so that's a bit tough to solder by hand. There are dev boards available, but they are basically a simple projector (e.g. including optics) [1] -- maybe it is possible to modify that instead of a full projector.
[1]
https://www.mouser.de/ProductDetail/Texas-Instruments/DLPDLCR2000EVM?qs=BZBe
i1rCqCAQetmBz0G1xQ==
Anyway, I can't tell you the model of the fan/motor since it is one of
the
case fans of the DLP projector I took apart. I'm pretty sure that I can
get
a better PC case fan for 2€ at the next supplier for computer parts.
WRT financing, let me repeat that I'm willing to spend money on even the simplest chips, at this point even a single MOSFET, if they prove that
the
whole idea isn't vaporware. I'm pretty sure we can find more people that feel the same when the first actual device gets posted to Hackaday and similar sites. Also, a Patreon site like [2] may help, but again, only if you can actually present something working (that guy can't). I think Sam Zeloof neglected this too much and didn't give people an easy way to send him money, because I'm convinced he would have gotten a lot of it.
[2] https://www.patreon.com/user?u=14363159
Greetings, Martin
On Fri, Apr 30, 2021 at 2:52 PM David Lanzendörfer <
leviathan@libresilicon.com> wrote:
Hi So I've now set up the office here with tables and stuff and could reproduce your experiments. If we know which motor performs ok for building a cheap spin coater, I could actually build one a little bit more professionally, by ordering some
of
those motors from Aliexpress. We could then sell those coaters on eBay and finance LibreSilicon a bit with it.
What do you think?
Cheers -lev
On Wednesday, April 28, 2021 6:36:11 PM WEST Martin Geisse wrote:
Hi,
If I remember correctly the spin coaters used in clean rooms first spin
up the wafer and then dispense the liquid
That did the job. I still think that the RPM is quite low because the fan is too weak, and I might later switch to the power drill to improve that, but applying the liquid only after the motor is spinning is
definitely
very
important.
You need to dispense liquid in middle of wafer as liquid will
online
move
outwards.
Obviously :)
I guess, you're experiencing problems because you didn't apply a primer
first.
I only did a test, spinning oil onto a coin. I guess that the primer
helps
with wetting and/or sticking to the wafer surface, which wasn't
(yet) a
problem in my test. Anyway, good to know!
Greetings, Martin
On Wed, Apr 28, 2021 at 5:06 PM David Lanzendörfer <
leviathan@libresilicon.com> wrote:
Exactly. First you've gotta spin up the wafer, and then you've gotta
dispense
it kind of towards the center, but it's not so critical. I guess, you're experiencing problems because you didn't apply a primer first.
https://www.3mdeutschland.de/3M/de_DE/unternehmen-de/produkte/~/3M-Silan-G
las-Primer-Transparent-1-L-Flasche/?N=5002385+3294237313&rt=rud
Cheers -lev
On Wednesday, April 28, 2021 12:24:57 PM WEST Staf Verhaegen wrote:
On wo, 2021-04-28 at 11:23 +0200, Martin Geisse wrote: > Hi, > > - spin coating > > I finally tried to build a makeshift spin coater the way Sam > Zeloof > did, by mounting a plastic can on top of a CPU fan (actually a > case > fan from another device I had lying around). I can't say this
is
the
> way to go... the fan is way too weak to spin the can at a
meaningful
> speed. It is also very hard to center the can exactly, so it
wobbles
> a lot and that probably reduces the speed even more. Mounting a > die > without a container would allow the fan to spin faster, but
would
> likely clog the fan with chemicals in no time. I'll next try my > original idea, to mount the can to an axle that I'll stick
into a
> power drill. > > One thing I did find out is that the coating liquid should be
evenly
> applied before spinning. It will NOT spread to the whole
surface
> by > itself, but rather run to a single direction in a concentrated > stream, probably due to surface tension.
If I remember correctly the spin coaters used in clean rooms
first
spin
up the wafer and then dispense the liquid. You need to dispense
liquid
in middle of wafer as liquid will online move outwards.
greets, Staf.
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