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

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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