May 2021 - Libresilicon-developers

Announcement - Mumble session on Sunday 2021-05-30 @ 18:00 UTC
by Hagen SANKOWSKI 29 May '21

29 May '21

Hello List! This is our weekly announcement for the next Mumble Sessions on Sunday 2021-05-30 @ 18:00 UTC. Please join us as usual at our Mumble Server murmur.libresilicon.com at Port 64738, the Channel is IC. We like to follow-up our topics from mumble sessions before. Regards, Hagen.

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Announcement - Mumble session on Sunday 2021-05-23 @ 18:00 UTC
by Hagen SANKOWSKI 21 May '21

21 May '21

Hello List! This is our weekly announcement for the next Mumble Sessions on Sunday 2021-05-23 @ 18:00 UTC. Please join us as usual at our Mumble Server murmur.libresilicon.com at Port 64738, the Channel is IC. We like to follow-up our topics from mumble sessions before: - Glove Box - technology issues - etc Regards, Hagen.

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Open... (and Libre) Silicon ASIC Conference idea by Matt Venn
by Luke Kenneth Casson Leighton 19 May '21

19 May '21

https://forms.gle/BdLWdyryLJbj8kY9A https://libre-soc.org/conferences/mattvennidea2021/?updated https://twitter.com/matthewvenn/status/1395005398046978048 Matt Venn has suggested the idea of an "Open Source" ASIC conference. bless him, it's a fantastic idea, my only concern being that the emphasis on "Open" will end up with the same completely unintentional exclusion caused by, just picking one example, OpenPOWER NA 2020 selecting slack as the sole exclusive attendee discussion forum. as a result it was a deeply disturbing psychological experience to present at, being completely cut off and isolated from the other speakers and attendees, only "rolled on" to give an actual talk then "rolled off" back in the box, silenced by the non-diverse non-inclusive accidental choice of technology. if you believe the idea to be a good one - and after the excitement that was caused by David's "Reprap ASIC" presentation at NGI Forum 2021 yesterday - i think it is, please do spread the word and emphasise to people to advocate for *Libre* inclusive hosting technology. the most obvious answer there is "follow what FOSDEM2021 and Debconf or XDC2020 do", they all used jitsi in some fashion. FOSDEM and Debconf also use matrix/element.io, XDC2020 used jitsi plus IRC plus a jitsi youtube live plugin. if you choose not to use google forms, you can ask someone to enter the responses for you, i am happy to do that, please email me directly. l. --- crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68

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Sputtering
by David Lanzendörfer 17 May '21

17 May '21

Hi everyone So yesterday in the meeting, we came across the problem, that we need to deposit metal onto our silicon oxide. There already has been progress from hobbyists on building home made Magnetron sputtering setups: https://transmitter.ieee.org/makerproject/view/9ce06 I think I will replicate this project (and others like it) and bring it into a form, in which I can use it in my garage. for depositing a Nickel layer. Opinions? Cheers -lev

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Announcement - Mumble session on Sunday 2021-05-16 @ 18:00 UTC
by Hagen SANKOWSKI 16 May '21

16 May '21

Hello List! This is our weekly announcement for the next Mumble Sessions on Sunday 2021-05-16 @ 18:00 UTC. Please join us as usual at our Mumble Server murmur.libresilicon.com at Port 64738, the Channel is IC. We like to follow-up our topics from mumble sessions before: - DMD chips for the Stepper - Glove Box - NLnet (virtual) Workshop - etc. Regards, Hagen.

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Virtual workshop, May 18
by David Lanzendörfer 08 May '21

08 May '21

Hi everyone So at the 18th May from 15-16h CEST there will be a virtual workshop happen, organized by NLNet and NG Zero: https://nlnet.nl/news/2021/20210507-NGI-Zero-workshop-open-hardware.html I'll be showing a 10 slide presentation on my strategy of setting up a micro chip foundry in the basement, using glove boxes with a closed loop system. In case you've got some input and ideas on what to also talk about in my 10 minutes, please come forward, I'm looking forward to your input :-) Cheers -lev

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Stepper electronics and optics
by David Lanzendörfer 08 May '21

08 May '21

Hi So Hagen apparently has been going full speed OCD into the selection of components for our stepper, of which the findings we will discuss tomorrow in our weekly Mumble session (murmur.libresilicon.com, 1800Z, -> UTC <-). I've been looking through the data sheet of the controller for the 4k DMD chip[1] and it turns out, that it's already the most suitable micro controller possible. I think we should just try to use the features available in KiCAD, for routing impendance controlled differential line pairs[2]. If those features are good enough for CERN, they should be good enough for us. I already once did successfully DDR3 RAM for an embedded device with KiCAD, so it's possible. I think it's the easiest to just use the controller from Texas Instruments, because the DLPC6540 comes with a USB interface, so we'd basically be done and just have to plug it into the computer used to control the stepping. About the x-y-System, Hagen has been talking about, I'm already working on that end for a while. I ended up with a gear shift design (I guess the Swiss genetics is coming forward again here. Yikes. LOL) and a laser distance measuring system to compensate for missed steps. Cheers -lev [1] https://www.ti.com/lit/ds/symlink/dlpc6540.pdf?ts=1620316149365 [2] https://forum.kicad.info/t/differencial-pair-impedance-calculator/4178

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Stepper optics
by David Lanzendörfer 03 May '21

03 May '21

Hi So Hagen and I have been going through potential candidates for the DMD chips and looking at the interfaces, which are super complex. Anything above 1080p is not usable anymore with a reasonable PCB layouting effort from our side. https://www.ti.com/dlp-chip/display-and-projection/pico-chipsets/getting-st… Hagen is right now going through the diverse chips and we will discuss his findings next week. Until then, we should already start discussing the lens system. What we need are lenses which make a focus roughly 1 cm away from the lens, I'd say, we're going for a projector design for now, because the micro mirrors still are of a size below our target feature size, so we've got to magnify the pattern. According to the DMD data sheets, a visible UV LED should work just fine with it. https://pt.mouser.com/ProductDetail/OSRAM-Opto-Semiconductors/GD-CSSRM214-A… Would be cool to have Shaktor on the mailing list here :-) Cheers -lev

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coating / chemicals / litho / strategy
by Martin Geisse 02 May '21

02 May '21

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. - chemicals I did find this resist which is meant for PCB etching, so I don't know yet whether it has some kind of "grain size" that limits the resolution. The datasheet explicitly states that it can take up to 40% hydrofluoric acid, though, and be used for glass etching (so I hope it will actually stick to glass). It is also liquid until soft-baking, so spin-coating should be possible. https://www.reichelt.de/fotopositiv-resist-positiv-20-200-ml-kontakt-235-p9… WRT hydrofluoric acid, there is something called "glass etching cream", the best-known brand being "Armour Etch". This contains fluorides, i.e. HF salts, is *somewhat* safer than HF itself (less fumes I think, but don't get it on your skin), and can be ordered by private individuals. The downside is that I could not find any information on whether it contains an abrasive. - photolithography Sam Zeloof used a modified DLP projector for his litho setup. He either used magic to do that or chose exactly the right projector. I took apart a used DLP and the UV filter is the only thing that could be taken out without destroying the projector. The color wheel, and even more so the optics, are buried under tons of other stuff, most of which is glued together. Also, the optics path itself is mostly glued. So I think David's plan of taking the DMD chip and building his own optics setup is a far better idea than modding a projector. To me as a layman in these things, stiching a larger image together from multiple images with a stepper sounds more logical than using multiple DMD chips. This XY table is cheap and has stepper motors that can position the table in increments of 5 microns. I have actually wondered if a first prototype should use a DMD at all, or just focus a single UV LED and "draw" by moving the XY table. https://www.amazon.de/Proxxon-27100-MICRO-Koordinatentisch-KT/dp/B000S81MHY - strategy I also thought a bit about who would be interested in making your own chips. High-volume production has far better, established processes, and low-volume production would use an FPGA or other off-the-shelf parts. Silicon testing before production isn't useful when the process is different. This leaves education and hobbyists. In other words, a free silicon process must be sustainable based solely on education and hobbyists, otherwise it won't stand a chance. There is another problem that goes in the same direction: a "democratized" chip making process should not rely on actors like INL, because there are too few of them -- less than 10 in the whole of Europe. Even if INL agrees to host the LibreSilicon process, a single decision by INL that chip making isn't interesting anymore can shut the whole thing down. I'm not particularly enthusiatic about the "glove box" idea either because I don't think it is practical, nor doable in a useful price range. The usual answer to the "expensive tools" problem is shared labs, usually as "fab labs", "makerspaces" or similar. I think this is a way in which chip making could actually work, especially if it works on dual-use tools that benefit a makerspace in other ways, like an XY table, microscope etc. I wanted to contact a local makerspace in my town, but unfortunately Germany just went into full Covid lockdown, so it's going to take a while until that. Greetings, Martin

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