<Noxz>
and like everyone I recognize in here is also in electronics..
<diginet>
haha
<Noxz>
anywho..
<Noxz>
MEMS question, still trying to get a solid answer, instead of using a thick resist such as SU-8 for building molds to then electroplate tiny metal gears (or whatever) could I potentially use a thin film on silicon(which is easier to focus the photomask), control etch anisotropically to have vertical sidewalls, then electroplate/form inside of the silicon wafer, then release the part/dissolve the silicon?
<diginet>
I don't think you electroplate SU8 since it's non-conductive
<diginet>
(could be wrong there)
<Noxz>
you don't, you use it as a mold for the sidewalls
<diginet>
and yeah, what I think you're describing is the lift-off process
<Noxz>
but if you put it on a silicon wafer or osmething, anythign conductive, you can then eelctroplate for it
<Noxz>
it's just limited by taking time to etch vertical sidewalls through Silicon?
<diginet>
but dissolving the whole wafer would be hard
<diginet>
you need plasma etching to get good aspect rations
<Noxz>
what about doing a steam step to add SiO2 ?
<diginet>
you can use some tricks with preferential etching for certain crystallographic plans to get anisotropy, but it won't compare to anything like with plasma
<diginet>
the problem with what (I think) you're describing is that it would be hard to get good aspect ratios
<Noxz>
I was reading that KOH and NaOH, up to about 30% by wt with IPA to be used as a suficant etches sidewalls vertically
<diginet>
the operative word here is "preferentially"
<Noxz>
well, yes, silicon doesnt relaly come in big depths like you can easily put on like su-8
<diginet>
if you're using SU8, the silicon is just a substrate
<diginet>
for MEMS
<diginet>
are you talking about soft lithography?
<diginet>
oh, wait, I reread what you wrote, now I understand
<diginet>
are you a university student? I ask because photoresists like SU-8 are nearly impossible to acquire as an individual
<diginet>
I've been trying to come up with my own formula, but progress has been slow
<diginet>
azonenberg can attest to my difficulties therein
<Noxz>
that's why I said without SU-8
<Noxz>
and no, I am not.. but I do live in silicon valley, if that helps
<Noxz>
but ho I work for does not do anything fun
<diginet>
probbably not
<Noxz>
just a sysadmin for a website
<diginet>
(help I mean)
<diginet>
unless your employer would let you ship to their office
<Noxz>
grantid, my group owns over 20k baremetal servers..
<diginet>
companies will not ship to individuals
<Noxz>
right
<diginet>
there are no openly available photoresists suitable for anything vaguely MEMS like
<diginet>
even if you could acquire it, it's very expensive, $600/L or something
<diginet>
granted, that would effectively last you a lifetime
<diginet>
(though they do have expiration dates)
<diginet>
and they won't sell in smaller quantities
<Noxz>
what about dry films that I laminate on?
<Noxz>
like I said, I will be using the silicon wafer as the mold
<Noxz>
a thin film to etch the silicon
<diginet>
dry films probabky wouldn't adhere well
<diginet>
plus the resolution is very poor
<diginet>
you'd be lucky to get 10micron or so
<Noxz>
hrrmm
<diginet>
(could be wrong there)
<Noxz>
but yeah, given the method I propposed, I don't need a thick film for MEMS
<diginet>
trust me when I say there is no easy option, I've spent a good portion of the last two years trying to find a pay to do amateur microscale patterning
<diginet>
s/way/pay
<Noxz>
hrmm.. well.. I have some time to pitch in ;)
<diginet>
heh, well good
<diginet>
definitely keep around
<Noxz>
and I am fairly motivated
<diginet>
we're trying to get as many people interested as possible
<Noxz>
like I said, I have one specific application
<diginet>
yeah
<diginet>
but the difficulty in patterning is the same
<Noxz>
and I know a person or two in the chip fab business in the valley around here.. not sure if that would help
<diginet>
ehh, probably not
<diginet>
if I had $20k to spare, I could get all I need, problem is I don't, neither do most people
<Noxz>
well, one guy said he could probably get me in contact with a guy who could make masks from $50-100/hr
<Noxz>
sure
<diginet>
what feature size?
<Noxz>
if I need one final mask in the end though..
<Noxz>
dunno
<Noxz>
but, MEMS was the discussion
<diginet>
film masks at ~5micron feature size are about that price
<diginet>
my goal at least, is to make things available to an amateur, granted it still won't be cheap, but at least possible
<Noxz>
right
<diginet>
but supposing you got the masks, the other stuff is non-trivial
<Noxz>
an American Scientific article is what got me REALLY interested in this, a few months back
<diginet>
which one?
<Noxz>
lemme dig it up
<diginet>
you can't really effectively electroplate bare silicon, AFAIK
<Noxz>
May 2014
<diginet>
my understanding is that most processes use a sputtered seed layer
<diginet>
interesting, but there are others doing similar things
<Noxz>
sure, but it got me interested
<diginet>
I'm generally wary of people who think they've stumbled on the next big thing
<Noxz>
nah, just a scientific american article
<Noxz>
I am not sure if that's what got me interested to get a watch with a silicon balance spring or not
<Noxz>
but yeah, I have a 2013 Omega Speedmaster Racing, for the sole purpose of saying/knowing that I have a silicon spring
<Noxz>
and I stumbled upon an ebay auction where it was not that bad of a price
<Noxz>
so, I used to be a bicycle mechanic, so I am into gears and such.. if I could have it my way, I would fly out to switzerland to go to watchmaking school
<Noxz>
boring sysadmin work for now, though
<diginet>
there's actually a watchmaking school here
<diginet>
Ohio Institute of Technology IIRC has a watchmaking program
<Noxz>
anyways.. I can't really do fine "swiss" types of finishes on something I can't see
<Noxz>
but, I will still try
<Noxz>
and I will probably first start with Nickel plating, then when I have a function calibre probably go to gold/platinum.. the thing is going to be so tiny it wont cost too much
<diginet>
ehhh
<diginet>
the materials might not
<diginet>
but making this happen will not be cheap
<Noxz>
I know
<Noxz>
I sort of have a budget in my head
<Noxz>
of course being single only helps
<diginet>
hmm?
<Noxz>
no wife/gf to stop me from spending too much, or rather taking my money away
<Noxz_>
VPN kicked me off, I didn't want to enter in the code again
<Noxz_>
done with work for now
<diginet>
$135 for a 7um mask
<Noxz_>
ahh, nice
<diginet>
that should be fine for MEMS
<Noxz_>
what do you think a workable area should be, anyways?
<diginet>
you'll need to, at the very least build some sort of spin coater, and figure out a way to get photoresist
<Noxz_>
1cm^2 ?
<diginet>
no idea
<Noxz_>
sure.. or test some laminated ones on the market
<Noxz_>
I like the idea of the simple-ness involved in them
<Noxz_>
versus spin coating, pre-baking, exposing, post baking, etc etc etc
<diginet>
there's no way, unless I'm totally mistaken, laminated masks will be good enough
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<diginet>
not to mention I imagine adhesion to Si would be a huge issue
<Noxz>
the reason is adhesion?
<diginet>
among other things
<diginet>
environmental instability is another
<Noxz>
filling the gaps.. having air bubles
<diginet>
and really, just the chemistry
<Noxz>
oh
<diginet>
thermal expansion, etc
<Noxz>
I was trying to look at DJ DevCorp SUEX thick film resist, specifically for MEMS, but there isn't too much on it
<Noxz>
no price sheet anywhere
<Noxz>
5 or so papers reference using it
<diginet>
rule of thumb: if you have to ask for a quite, it's probably very expensive and not sold to individuals
<Noxz>
quote* ;)
<diginet>
Also, I recommend against using new/unusual stuff unless you have a very good reason
<diginet>
right hahah
<diginet>
mostly because we're already basically on our own, not many people are attempting this
<Noxz>
sure
<diginet>
at least with the more established resists there's some people who might be able to help
<Noxz>
everyone interested in it is going to school for it, right?
<diginet>
yes, but it's not just that
<diginet>
azonenberg is a PhD student for example
<Noxz>
my previous job I had a "Student" position, even though I was not, at Chemical Abstract Services.. they wre THE chemistry registry database, that "cas: 123-456-789" number you seee often after chemical names
<diginet>
university research tends to assume university environments
<diginet>
i.e. access to fancy labs, chemicals, etc
<Noxz>
but not always true
<diginet>
so there's a lot less to draw on that's applicable to people like you and me
<Noxz>
sure
<Noxz>
it like needing a 7.5mm screw and all thati's offered is a 7mm and 8mm.. so you have to redesign based on wht is available
<diginet>
something like that, yes
<diginet>
I've been working on a water-developable resist formulation, which uses PVA and a chemically amplified design. The idea is to avoid dangerous stuff, but it's still not easy
<diginet>
I'm not a chemist, so that doesn't help either
<diginet>
but probably your best bet is to see if any of your contacts can get you some resist
<Noxz>
ah, sure
<diginet>
unfortunately that's not really a long-term solution
<diginet>
some of those chemicals are *nasty*
<diginet>
I highly advise against working with them without a fumehood, for example
<Noxz>
well, my initial idea seems decent enough, except for the adheshion issue
<Noxz>
right, like KOH
<diginet>
KOH is not as bad
<diginet>
I'm more referring to things like HF
<Noxz>
ohh, that too, that's on my lsit to disolve SiO2 if needed to have a release layer
<diginet>
I don't think that's going to work very well
<Noxz>
eh, I'm not there yet
<Noxz>
;)
<diginet>
true, true
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<Noxz>
I'm giving my buddy a half hour to call me (going to buy a backgammon set.. maybe, plus dinner) before I get food myself
<diginet>
ahh
<Noxz>
a friend thought it would be funny to dump a bunch of ahlloween candy on my couch before boardgames last night.. and now I have a headache
<Noxz>
agh, gotta VPN back in.. I'll be sure to add this channel onto my desktop for connecting
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<Noxz>
What are opinoins on using the headphone/audio out jack on a soundcard to position a CNC ? I know the resolution isn't fantastic
<SpeedEvil>
It's ACcoupled
<Noxz>
ah, right
<Noxz>
someone just wrote "yee-haw" in an email.. awesome