| bart416 | azonenberg, would you trust a 1000 euro piece of equipment to an ikea table? | 16:53 |
|---|---|---|
| azonenberg | Depends, i dont have any ikea furiture | 16:53 |
| azonenberg | i have over 1000USD of equipment on a relatively cheap table now that's somewhat worrisome | 16:53 |
| azonenberg | while i am planning to replace it soon i don't feel the gear is in any immediate danger | 16:54 |
| azonenberg | And actually its probably closer to 2000USD | 16:54 |
| azonenberg | two microscopes, probing station, and fiber optic illuminator | 16:54 |
| smeding | hmm | 16:58 |
| bart416 | well, this table looks sturdy at first sight | 17:00 |
| bart416 | but the "wood" at the top is fairly light | 17:00 |
| bart416 | If it's a layer of MDF with cardboard under it to fill up the space I don't mind | 17:02 |
| bart416 | But else... | 17:02 |
| adc | whos here | 17:26 |
| adc | this should be a fun chan | 17:27 |
| berndj | data point: i have a former bookshelf, made of chipboard, standing outside; i rescued it from the neighbours' trash 3 winters ago, so it's seen some rain. parts have swollen, but it's still supporting a few potted plants. that's about as hostile an environment i can think of for the material | 18:24 |
| berndj | my personal advice would be: don't do anything stupid, like standing on a table to change a lightbulb, while there's a k$-value piece of equipment on it. don't do it anyway if you're unsure it'll hold: injuries are a pain in the ass (probably literally in this case) | 18:25 |
| bart416 | lol | 18:26 |
| bart416 | I've seen somebody fall through a glass table already | 18:26 |
| berndj | also, unlike wood, chipboard and i guess MDF fails suddenly and catastrophically - it doesn't "yield" like real wood does | 18:26 |
| berndj | glass also doesn't yield :) | 18:26 |
| berndj | although that's likely to have been tempered glass, no? so lots of little cubes rather than shards, i hope | 18:27 |
| bart416 | yes it was tempered | 18:28 |
| bart416 | but it still wasn't pretty | 18:28 |
| bart416 | berndj, http://img688.imageshack.us/img688/7576/imag0484j.jpg | 18:29 |
| berndj | i get a weird bit.ly frog in an ice cube :( something about unregistered domain | 18:30 |
| berndj | i'll try again later | 18:31 |
| bart416 | just refresh | 18:31 |
| bart416 | I also have it sometimes with imageshack | 18:31 |
| XgF | It's also inadvisible to inspect something on the ceiling while walking on a raised surface... | 18:37 |
| XgF | (Yes, the resultant catching of my leg in the subsequent 1 meter drop hurt) | 18:38 |
| azonenberg | hi adc | 18:38 |
| azonenberg | check the logs and lab notes on the googlecode repo to get up to speed on past work | 18:40 |
| bart416 | berndj, does it work now? | 18:40 |
| berndj | azonenberg, i'm a bit behind with your tech. your Ta2O5... do you start with some tantalum chloride in something-solution or what? | 18:40 |
| berndj | nope, still the frozen toad! | 18:40 |
| bart416 | Also, please ignore the teken and doom3 posters, they're glued to the wall >_> | 18:40 |
| bart416 | :S | 18:40 |
| bart416 | Does it work for you azonenberg ? | 18:41 |
| XgF | works here | 18:41 |
| berndj | maybe my isp is doing weird things | 18:42 |
| XgF | It's my general observation that ISPs are like that | 18:43 |
| berndj | okay, getting it via ssh to another box | 18:43 |
| berndj | maybe some confused "transparent" web proxy getting in the way | 18:44 |
| azonenberg | berndj: yes, i do | 18:44 |
| azonenberg | tantalum chloride in ethanol | 18:44 |
| azonenberg | spin coat, then bake in air at 200C for 1 hour | 18:44 |
| azonenberg | emulsitone tantalumfilm is the product i'm using | 18:44 |
| azonenberg | they dont go into detail on the composition on the main page but the MSDS says its tantalum chloride in denatured alcohol | 18:45 |
| azonenberg | and i confirmed that by EDS | 18:45 |
| berndj | ah, the table. bart416 i wouldn't worry about leaving expensive stuff on it, unless a) you have Mw 9.0 quakes regularly, b) drunken oafs falling around regularly, c) expensive stuff is more than a few dozens of kg | 18:45 |
| nathan7 | azonenberg: and then? | 18:46 |
| berndj | azonenberg, i was just wondering how you got past the insolubility of Ta2O5. i guess the baking is a sort of roasting process, where you substitute Cl ions with O^2- ? | 18:46 |
| nathan7 | on a side note, where do you get that TaCl5 | 18:47 |
| azonenberg | berndj: 2TaCl5 + 5H2O = 10HCl + Ta2O5 | 18:47 |
| azonenberg | is the reaction afaik | 18:47 |
| nathan7 | doesn't that give the oxychloride? | 18:48 |
| bart416 | berndj, does a 5kg scope count? :P | 18:48 |
| azonenberg | I dont know the exact details, all i know is that the resulting film has the characteristics of tantalum oxide | 18:48 |
| berndj | pfft, maybe if you stack 10 of them! | 18:48 |
| berndj | nathan7, i imagine it's temperature-sensitive | 18:49 |
| azonenberg | nathan7: and when I ran EDS on the sample I found nothing but Si, O, Ta, and a trace of C (photoresist residue) | 18:49 |
| nathan7 | it's just a guess, I don't know about tantalum | 18:49 |
| berndj | higher temp would drive the equilibrium (if it's anywhere near the "middle") towards more HCl - 10HCl vs 5H20 - more degrees of freedom | 18:49 |
| azonenberg | I know tantalum oxychloride is formed in a similar reaction | 18:49 |
| nathan7 | but anhydrous metal chlorides tend to do that | 18:49 |
| azonenberg | nathan7: http://www.emulsitone.com/taf.html | 18:50 |
| nathan7 | interseting | 18:50 |
| nathan7 | *interesting | 18:50 |
| azonenberg | Its not a hot selling item | 18:50 |
| azonenberg | I'm the only customer for the lot number they sent me | 18:50 |
| berndj | and another thing azonenberg - how crazy do you go on reagent purity? | 18:50 |
| azonenberg | made the batch on request for 500 USD lol | 18:50 |
| azonenberg | berndj: Not very for now since i'm not doing CMOS | 18:51 |
| azonenberg | i can get away with much lower tolerances | 18:51 |
| nathan7 | Also, you seem to get all kinds of funny inorganics | 18:51 |
| azonenberg | the photoresist is printed circuit board | 18:51 |
| nathan7 | where'd I get PdCl2? | 18:51 |
| berndj | i thought the semiconductor industry uses only an insane number of 9's in their purity of reagent, to avoid traces of unwanted stuff | 18:51 |
| azonenberg | grade | 18:51 |
| berndj | but you seem to be using IPA etc al from the electronic equivalent of the corner grocer? | 18:51 |
| berndj | (or am i mistaken there) | 18:51 |
| azonenberg | my NaOH and KOH are technical grade from a biodiesel vendor | 18:51 |
| azonenberg | so is the HCl | 18:51 |
| nathan7 | mh-hrm | 18:52 |
| azonenberg | the HF is sold in the grocery store as a rust remover | 18:52 |
| XgF | My assumption is that MEMS is a lot less critical on purity? | 18:52 |
| azonenberg | 3% H2O2 and ammnoia are from a drugstore | 18:52 |
| nathan7 | I figured you'd know where to get some funny transition metal chloride | 18:52 |
| berndj | apropos HF, i've looked, but have not found anything HF-like in any normal shops | 18:52 |
| azonenberg | IPA is actually 99% / 1% DI water from a cleanroom supplier | 18:52 |
| bart416 | If you need pure chemicals, go medical industry | 18:52 |
| azonenberg | berndj: Whink brand rust remover | 18:52 |
| berndj | the only rust-pertaining products i've found seem to be based on phosphoric acid | 18:52 |
| azonenberg | my acetone is from the same biodiesel supplier but i also have a can from a hardware store | 18:52 |
| azonenberg | I would not attempt CMOS with the stuff i have now, thats for sure | 18:53 |
| berndj | (i don't think we have whink here - i'm in ZA, not US) | 18:53 |
| azonenberg | But for MEMS a few PPM of contaminants dont hurt anything | 18:53 |
| azonenberg | as long as it isnt enough to change the physical (rather than electrical) properties of the substrate | 18:53 |
| Action: XgF thinks really this channel should be #homemems | 18:53 | |
| azonenberg | XgF: CMOS is still on the wishlist | 18:54 |
| azonenberg | much of the equipment can be used for either | 18:54 |
| azonenberg | and once i get a furnace i plan to try duplicating jeri's transistor process | 18:54 |
| berndj | re ethanol / IPA, i imagine *water* itself isn't such a big deal - it also evaporates, albeit somewhat more slowly | 18:54 |
| azonenberg | berndj: Yes, but 70% drugstore grade tends to have salts etc in it | 18:54 |
| berndj | rather the sub-1% contaminants, whatever they may be. assuming oily stuff | 18:54 |
| berndj | yes, and salts. indeed | 18:54 |
| azonenberg | nathan7: http://www.emulsitone.com/pdf.htmlmay be palladium chloride | 18:55 |
| azonenberg | http://www.emulsitone.com/pdf.html may be* | 18:55 |
| azonenberg | it may be polymer based too | 18:55 |
| azonenberg | berndj: The lowest purity i have is my denatured alcohol (paint store grade) and that is actually bad enough that i saw problems resulting from using it to dilute stuff | 18:56 |
| azonenberg | so i'm gonna try and find highier grade at some point | 18:56 |
| nathan7 | I need just a catalytic amount of PdCl2 | 18:56 |
| azonenberg | nathan7: Emulsitone won't sell you less than four ounces of their stuff | 18:56 |
| azonenberg | fluid ounces that is | 18:56 |
| berndj | salts indeed, i was playing with water drops and a hot pan (leidenfrost effect) the other day. there was a "sticky" spot where drops got stuck; eventually a distinctive residue of stuff built up on said spot. i assume it was perhaps a carbonate type thing | 18:56 |
| azonenberg | And the precious metal based ones tend to run around $500 for that volume | 18:56 |
| XgF | azonenberg: Hmm... what sort of purity do you need on the [denatured] alcohol? | 18:57 |
| azonenberg | When one says denatured alcohol, i assume that it's just ethanol with maybe 5% methanol | 18:57 |
| azonenberg | but this stuff has other things inside too | 18:57 |
| azonenberg | my guess is there's something oily | 18:58 |
| berndj | sigh, i live in possibly the biggest Pd-producing country in the world, but i bet there's no way i can get any in less than ton quantities here | 18:58 |
| XgF | Denatured alcohol always has other stuff inside | 18:58 |
| XgF | Generally things like flavorants so it tastes disgusting | 18:58 |
| nathan7 | denatonium | 18:58 |
| nathan7 | generally | 18:58 |
| azonenberg | Correct | 18:59 |
| azonenberg | But that's present in trace quantities in my HF too | 18:59 |
| nathan7 | o.o | 18:59 |
| azonenberg | and doesnt cause any problems | 18:59 |
| bart416 | azonenberg, you need medical grade ethanol | 18:59 |
| bart416 | seirously | 18:59 |
| nathan7 | like you'd taste it before it's too late | 18:59 |
| bart416 | *seriously | 18:59 |
| XgF | The list for UK denatured alcohol is pretty large | 18:59 |
| bart416 | It's not that hard to get | 18:59 |
| berndj | or that purple stuff for methanol. hobos here use bread to "filter it out", apparently | 18:59 |
| bart416 | But it's pure | 18:59 |
| azonenberg | bart416: i'm seriously considering doing so | 18:59 |
| azonenberg | apparently you can buy it taxed as a beverage which saves all of the recordkeeping from buying untaxed 100% ethanol | 19:00 |
| azonenberg | costs an extra few $$ per unit volume but if its 500ml of ACS trace metal grade ethanol then the extra $5 wont matter | 19:00 |
| bart416 | Or you could try a bottle of cheap russian vodka | 19:00 |
| bart416 | That's usually fairly pure ethanol as well :P | 19:00 |
| azonenberg | bart416: waaaay too many organics in that | 19:00 |
| azonenberg | insoluble organics that is | 19:01 |
| bart416 | Organics can survive in that? | 19:01 |
| XgF | ...99% ABV grain alcohol maybe? | 19:01 |
| nathan7 | of course, bart416 | 19:01 |
| nathan7 | ethanol itself is organic =p | 19:01 |
| bart416 | nathan7, I was joking :| | 19:01 |
| Action: nathan7 hits bart416 | 19:01 | |
| bart416 | No but seriously, cheap russian vodka is probably far more pure than your denatured alcohol | 19:01 |
| azonenberg | http://www.sigmaaldrich.com/catalog/ProductDetail.do?D7=0&N5=SEARCH_CONCAT_PNO|BRAND_KEY&N4=493546|SIAL&N25=0&QS=ON&F=SPEC | 19:01 |
| azonenberg | $63 for 500ml of ethanol USP | 19:02 |
| XgF | Comes up as £13.80 here :o | 19:03 |
| azonenberg | prob detected a .uk IP address lol | 19:03 |
| XgF | YEah, sent me to UK site, but you're beingq uoted ~3.5x the price | 19:03 |
| azonenberg | not sure | 19:03 |
| azonenberg | This is taxed as a beverage in the US | 19:04 |
| azonenberg | you can get it untaxed (much cheaper) but there are all kinds of paperwork stuff to follow | 19:04 |
| azonenberg | to prove nobody is drinking it | 19:04 |
| bart416 | Mhhh Sigma Aldrich became cheaper | 19:04 |
| azonenberg | easier to get the taxed version since you're legally clear | 19:04 |
| nathan7 | make sure to have the paperwork look like it was filled in by a drunk person | 19:04 |
| bart416 | Damn their FTO glass is cheap o_O | 19:05 |
| Action: XgF would be surprised if a bottle of lab ethanol turned up here with a UK duty tax sticker on it :p | 19:05 | |
| azonenberg | http://www.sigmaaldrich.com/catalog/ProductDetail.do?lang=en&N4=179124|SIAL&N5=SEARCH_CONCAT_PNO|BRAND_KEY&F=SPEC | 19:06 |
| azonenberg | i should place an order from these guys at some point | 19:06 |
| bart416 | and they're also cheaper than most for their SU-8 o-O | 19:07 |
| nathan7 | you can order there? | 19:07 |
| nathan7 | sweet | 19:07 |
| nathan7 | ebay's ¬50/g is starting to look very reasonable | 19:09 |
| bart416 | http://www.sigmaaldrich.com/catalog/ProductDetail.do?D7=0&N5=SEARCH_CONCAT_PNO|BRAND_KEY&N4=654892|ALDRICH&N25=0&QS=ON&F=SPEC <-- this is cheap o-O | 19:09 |
| nathan7 | looking at aldrich | 19:09 |
| azonenberg | bart416: is that su-8? | 19:09 |
| bart416 | no | 19:09 |
| nathan7 | ¬87.50/g, wtf | 19:10 |
| bart416 | but they had something that was chemically identical to SU-8 at first glance | 19:10 |
| bart416 | might have been mistaken | 19:10 |
| azonenberg | i see | 19:10 |
| nathan7 | If I could find someone who needed 0.5g of PdCl2, I can't afford a gram of that shit | 19:10 |
| nathan7 | man, drugs are cheaper than this | 19:10 |
| azonenberg | lol | 19:10 |
| bart416 | Palladium is expensive :( | 19:11 |
| nathan7 | I should use the Wacker oxidation to make drugs to be able to afford the PdCl2 | 19:11 |
| nathan7 | except I need the PdCl2 in the first place | 19:11 |
| nathan7 | =p | 19:12 |
| bart416 | Where could you get palladium cheaply | 19:12 |
| bart416 | mhhh | 19:12 |
| nathan7 | I should start stealing catalytic converters, I guess | 19:13 |
| azonenberg | :p | 19:13 |
| bart416 | Probably | 19:13 |
| bart416 | Maybe steal one from a car accident scene before the police gets there | 19:13 |
| bart416 | lol | 19:13 |
| nathan7 | heh | 19:14 |
| bart416 | nathan7, hey cheer up | 19:15 |
| bart416 | It's still cheaper than platinum! | 19:15 |
| nathan7 | true | 19:15 |
| bart416 | Platinum is cool though | 19:17 |
| bart416 | Probably one of the safest materials you can possibly handle | 19:17 |
| azonenberg | Gold comes pretty close | 19:18 |
| azonenberg | in terms of unreactivity | 19:18 |
| bart416 | well, from a medical point of view gold is better | 19:18 |
| azonenberg | Pt/Pd/Au are all very unreactive | 19:18 |
| Action: berndj wonders if platinum dust in your lungs would catalyse some mega bad reaction | 19:18 | |
| Action: azonenberg would prefer not to find out experimentally | 19:19 | |
| berndj | i thought titanium was pretty much king in terms of biocompatibility. but maybe rather due to relative cost and mechanical properties | 19:19 |
| bart416 | pure elemental platinum or not berndj ? | 19:19 |
| XgF | berndj: isn't it the king in terms of biocompatibility while bring /rigid/? :p | 19:19 |
| berndj | bart416, i dunno? i thought Pt as catalyst was pretty much just the metal? | 19:20 |
| bart416 | elemental platinum shouldn't cause too much problems | 19:20 |
| bart416 | some irritation I figure | 19:20 |
| bart416 | also titanium has its mechanical properties | 19:20 |
| bart416 | But gold has some interesting ones as well | 19:20 |
| bart416 | azonenberg, that's another thing | 19:22 |
| bart416 | You could potentially make bio implants with your Tantalum Oxide processes | 19:22 |
| berndj | heh, okay, not metallic Pt, but cisplatin would be nasty | 19:23 |
| azonenberg | bart416: Not likely :P | 19:23 |
| azonenberg | And i have no idea how biocompatible ta2o5 is | 19:23 |
| bart416 | Nah, tantalum is biocompatible | 19:23 |
| bart416 | It should be | 19:23 |
| bart416 | Ta2O5 is stable as far as I remember | 19:23 |
| azonenberg | its a glass | 19:24 |
| azonenberg | almost indestructible | 19:24 |
| azonenberg | HF is about the only thing that attacks it chemically | 19:24 |
| azonenberg | An order of magnitude or so slower than SiO2 | 19:24 |
| bart416 | how are the oxygen atoms arranged around it again? | 19:24 |
| azonenberg | No idea | 19:24 |
| azonenberg | I treat it as potentially dangerous since i'd rather not find out the hard way it wasnt harmless | 19:24 |
| azonenberg | iow, with the same caution i'd use with my HF, conc. HCl, etc | 19:25 |
| berndj | except with those you KNOW a priori that they're not harmless! | 19:25 |
| azonenberg | Correct | 19:25 |
| berndj | and they make it pretty obvious that they aren't | 19:26 |
| azonenberg | But the MSDS for this substance indicated it hadnt had any formal toxicity studies conducted | 19:26 |
| azonenberg | So i treat it as potentially nasty | 19:26 |
| azonenberg | i may well be overreacting | 19:26 |
| azonenberg | but i'd rather be safe | 19:26 |
| bart416 | looks like Ta2O5 is safe | 19:27 |
| azonenberg | How about the chloride though? | 19:27 |
| berndj | well, i wouldn't inject myself with TaCl5 solution, but if i spilled some on my skin i'd probably wash it off and not worry too much | 19:27 |
| bart416 | well yeah, only found one paper on it but meh | 19:27 |
| bart416 | Chlorides are bad generally | 19:27 |
| azonenberg | The glass is pretty obviously stable | 19:27 |
| azonenberg | The chloride is what i'm concerned about | 19:28 |
| bart416 | Chlorides are generally rather reactive | 19:28 |
| azonenberg | Hence the usual gloves-lab coat-goggles routine | 19:28 |
| berndj | i can't imagine the chloride ion itself could cause much harm: you have plenty of it in your body | 19:28 |
| azonenberg | berndj: The concern is the Ta+ ion | 19:28 |
| berndj | any toxicity would have to be special to the tantalum ioin | 19:28 |
| bart416 | Tantalum on its own is biocompatible | 19:29 |
| azonenberg | bart416: Metallic, sure | 19:29 |
| berndj | yeah; i'm just countering the "chlorides are bad" thing. i think they're generally bad because chlorides are generally more likely to be soluble, hence can get through your skin? | 19:29 |
| bart416 | berndj, just saying chlorides are generaly rather reactive, not that they themselves are bad | 19:30 |
| bart416 | It's too complicated to bother | 19:30 |
| bart416 | Quick glance I'd say Ta+ would start acting very similar to Mg+ | 19:35 |
| azonenberg | Meaning? | 19:35 |
| bart416 | You're not going to die from it unless it are large quantities | 19:35 |
| azonenberg | Lol | 19:36 |
| azonenberg | But still, i have no plans to become any more casual in my handling of it | 19:36 |
| bart416 | lol | 19:37 |
| bart416 | You don't want Tantalum bones? | 19:37 |
| azonenberg | lol | 19:39 |
| bart416 | What? | 19:39 |
| bart416 | Where do you think Magnesium ends up? | 19:39 |
| azonenberg | i'm saying, i dont :P | 19:40 |
| bart416 | I thought you'd love that azonenberg, imagine how fun MRIs would become :P | 19:42 |
| azonenberg | lol | 19:42 |
| berndj | my *guess* would be you have more to worry about from the pH effects of TaCl5 interacting with your body than from Ta(V) itself | 19:45 |
| berndj | http://www.lookchem.com/Tantalum-chloride/ thinks its vapour pressure is 33900mmHg at 25°C :( | 19:47 |
| azonenberg | lol | 19:48 |
| berndj | probably they meant µmHg | 19:48 |
| azonenberg | Looks like its nasty if it gets inside | 19:49 |
| azonenberg | but doesnt penetrate skin | 19:49 |
| berndj | but: that page does have a safety section | 19:49 |
| azonenberg | its corrosive but not toxic on skin contact | 19:49 |
| berndj | poison by intraperitoneal route. iow, don't eat it | 19:49 |
| azonenberg | Yeah lol | 19:49 |
| berndj | lol, LD50 at 1900mg/kg (the higher of two values) | 19:50 |
| berndj | that's close to death by overeating | 19:51 |
| azonenberg | 1.9 grams/kg? Yeah lol | 19:51 |
| azonenberg | thats a LOT | 19:51 |
| azonenberg | i dont even know if my entire bottle of solution is that much | 19:51 |
| berndj | i guess treating everything as potentially harmful is a good idea, but on balance i don't think it's necessary to treat it the same way you treat piranha! | 19:52 |
| azonenberg | i wouldnt use piranha in this lab lol | 19:53 |
| berndj | at some point you incur more risk in trying to avoid the original risk, than from accepting the original risk itself | 19:53 |
| berndj | (which i'm not saying you're doing) | 19:53 |
| berndj | how closely can you control the layer thickness? | 19:54 |
| azonenberg | Process control, especially on the tantalum oxide layers, is a sticky point right now | 19:55 |
| azonenberg | i'm having trouble getting consistent good film quality | 19:55 |
| azonenberg | Photoresist and other stuff i can spincoat fine | 19:55 |
| berndj | and, can you produce a "clean" layer of Ta2O5 (smooth, mainly, and uniform thickness)? | 19:55 |
| azonenberg | Over what area? | 19:55 |
| bart416 | mhhh, how hard would it be to dispose silver on acrylics | 19:55 |
| berndj | over a square foot or so :) | 19:55 |
| azonenberg | Not even close :P | 19:55 |
| azonenberg | i've had trouble on 2-inch wafers getting uniform coatings | 19:56 |
| berndj | what thickness do you typically try to deposit though? | 19:56 |
| azonenberg | 50-100nm | 19:56 |
| berndj | i'm just wondering if it's useful as a reflection-enhancing coating on optics (telescope mirrors) | 19:56 |
| azonenberg | No, in fact the opposite | 19:56 |
| azonenberg | its routeinely used as an antireflective coating on lenses :P | 19:57 |
| berndj | its insolubility would be a boon | 19:57 |
| berndj | antireflective vs reflection-enhancing is just a matter of film thickness :) | 19:57 |
| azonenberg | Hmm, good point | 19:57 |
| azonenberg | In any case i'm having trouble getting good yields with it | 19:58 |
| azonenberg | tonight i'll actually be conducting some experiments with the goal of removing it from my process | 19:58 |
| berndj | in fact i'm surprised they'd use it as an ANTIreflective coating - i'd imagine its "high" refractive index is higher than that of the lens material? do you have any idea what its index of refraction is? | 19:58 |
| azonenberg | 2.5ish i think? | 19:58 |
| azonenberg | thats for bulk material though | 19:58 |
| azonenberg | thin films may be different | 19:58 |
| berndj | would 100nm count as "thin film"? | 19:59 |
| azonenberg | but yes i think its higher than that of the lens | 19:59 |
| azonenberg | Yes | 19:59 |
| azonenberg | Submicron, generally | 19:59 |
| azonenberg | as a rough rule of thumb | 19:59 |
| berndj | still, it's an interesting idea; sounds like it's better than impossible to get hold of, it's water-insoluble, and good transmission window | 20:00 |
| berndj | what sort of non-uniformity were you getting? | 20:00 |
| azonenberg | First, pinholes in the surface | 20:01 |
| berndj | local or global, specifically? | 20:01 |
| azonenberg | those were local and went all the way through the layer but were tiny | 20:01 |
| berndj | i think pinholes wouldn't be a problem for a reflection coating | 20:01 |
| azonenberg | Then there were global thickness variations as well, probably due to viscosity of the solution | 20:01 |
| azonenberg | i think i need to thin it down more | 20:01 |
| berndj | more important would be if you could maintain thickness to within a dozen percent over a square foot | 20:01 |
| azonenberg | A dozen percent? Hmm | 20:01 |
| azonenberg | I'm getting visible color variations right now over a 2-inch wafer | 20:02 |
| berndj | even if not, it would probably still be better than no coating at all | 20:02 |
| azonenberg | But hopefully the process can be improved to the point that this goes away | 20:02 |
| berndj | do you know that those color variations are due to film thickness variations, and not just viewing angle? | 20:02 |
| azonenberg | They show up under microscopy from a straight-down angle | 20:03 |
| berndj | you could expect circles of fixed path length-difference showing up | 20:03 |
| azonenberg | and are consistent as i move around | 20:03 |
| berndj | sounds like the film then | 20:03 |
| azonenberg | these are theta-related | 20:03 |
| azonenberg | streaks going from center out to the rim, slightly thicker or thinner than the rest | 20:03 |
| berndj | oh right, yes, that does sound like what i'd expect from spin coating + too much viscosity | 20:04 |
| azonenberg | Yes | 20:04 |
| berndj | in fact i'm still surprised that spin coating works at all in giving a ~uniform film thickness | 20:04 |
| azonenberg | I need to get higher purity ethanol | 20:04 |
| azonenberg | to thin the solution down | 20:04 |
| azonenberg | the stuff i was using seems to be contaminated somehow | 20:05 |
| berndj | could ethanol evaporation be causing problems? you'd have locally more-concentrated regions, which would be more viscous | 20:05 |
| azonenberg | I dont think so, i got better results in the past | 20:05 |
| azonenberg | there is a contaminant somewhere and i suspect my ethanol | 20:06 |
| azonenberg | But one experiment was anomalous | 20:06 |
| berndj | anyway, i don't think one can (easily) spin-coat a miror! | 20:06 |
| azonenberg | i got the same result from using pure tantalumfilm with no dilution | 20:06 |
| azonenberg | so either it wasnt as pure as i thought | 20:06 |
| azonenberg | or there is another variable out there | 20:06 |
| azonenberg | one i'm not seeing | 20:06 |
| berndj | wait, how much water was in your ethanol again? | 20:06 |
| azonenberg | i dont know | 20:07 |
| azonenberg | The tantalumfilm is 16% solids by weight, the remainder is semiconductor grade denatured alcohol (which basically means ethanol+methanol w/ nothing else) | 20:07 |
| azonenberg | I prepared a dilution of a few drops of this mixed with my ethanol | 20:07 |
| azonenberg | Which is paint store grade | 20:07 |
| azonenberg | i dont even have an msds for it listing the denaturants | 20:08 |
| berndj | yeah, i imagine any water at all would cause partial hydrolysis | 20:08 |
| azonenberg | Ooh, interesting | 20:08 |
| berndj | disclaimer: i'm just parroting wikipedia and my other google results from the last hour | 20:08 |
| azonenberg | you're thinking my ethanol is contaminated with water | 20:08 |
| azonenberg | and that its hydrolyzing some of the stuff on contact without heating? | 20:08 |
| berndj | something like that | 20:09 |
| XgF | Water would be an especially cheap denaturant | 20:09 |
| berndj | so there might be some tantalum oxychloride | 20:09 |
| azonenberg | berndj: The results i was seeing were catastrophic though | 20:09 |
| azonenberg | not a slight degradation in film quality | 20:09 |
| azonenberg | there was no film to speak of | 20:09 |
| azonenberg | It beaded up and didnt stick to the surface | 20:10 |
| berndj | yikes | 20:10 |
| berndj | it was that "flaky" looking stuff in your pics? | 20:10 |
| azonenberg | No | 20:10 |
| azonenberg | worse | 20:10 |
| azonenberg | i pipette a ml or so of the solution (pure or diluted) onto a wafer | 20:10 |
| nathan7 | OXYCHLORIDE, POW | 20:10 |
| azonenberg | spin at maximum speed on my spin coater | 20:10 |
| berndj | oh no, the flaky stuff was your PR | 20:10 |
| nathan7 | oh | 20:10 |
| azonenberg | before spinning it formed a nice thin layer over the wafer | 20:11 |
| azonenberg | as i spin, i see it gradually thinning | 20:11 |
| azonenberg | then radial lines start appearing | 20:11 |
| azonenberg | (well before it hits the desired thickness) | 20:11 |
| berndj | a sort of surface tension thing? | 20:11 |
| azonenberg | so i remove power and spin down | 20:11 |
| azonenberg | and i see balls of solution in a relatively random pattern across the surface | 20:11 |
| azonenberg | some free, some connected by narrow lines of coated area | 20:11 |
| azonenberg | the rest of the silicon was uncoated | 20:12 |
| azonenberg | wish i had a photo but my hands had something on them and i didnt want to contaminte my camera | 20:12 |
| berndj | sounds like a surface tension issue | 20:13 |
| azonenberg | Agreed | 20:13 |
| berndj | your "silicon" (or maybe more likely, the SiO2 covering it) didn't like the film | 20:13 |
| azonenberg | hence why i suspected a contaminant in the film | 20:13 |
| azonenberg | Since in the past it had worked beautifully | 20:13 |
| azonenberg | I tried stripping native oxide in HF | 20:13 |
| azonenberg | and coating immediately | 20:13 |
| nathan7 | quaternary ammonium salt might help with wetting | 20:13 |
| azonenberg | that didnt work any better | 20:13 |
| azonenberg | So i re-grew the oxide in heated 3% H2O2 (didnt wnat to wait a week for it to form on its own) | 20:14 |
| berndj | can contaminants cause such gross changes in surface tension behaviour? | 20:14 |
| nathan7 | I figure it'd degrade to N2 during the oxidation steps | 20:14 |
| azonenberg | verified native oxide was present by the water-droplet test | 20:14 |
| azonenberg | and coated again | 20:14 |
| azonenberg | still didnt work | 20:14 |
| nathan7 | :( | 20:14 |
| azonenberg | after three or four tries it spontaneously worked | 20:14 |
| azonenberg | i baked it, not wanting to risk losing a semi-decent film | 20:15 |
| azonenberg | then after several tries got an ok-ish one on the back side | 20:15 |
| azonenberg | But i have no idea what the variable was | 20:15 |
| azonenberg | Some of my best Ta2O5 films were gotten by diluting with alcohol | 20:15 |
| berndj | ethanol soaking up whatever impurities were on the wafer? | 20:15 |
| azonenberg | the same alocohol that i previously thought was my problem | 20:16 |
| azonenberg | I did an acetone rinse, then a native oxide strip followed by regrow | 20:16 |
| azonenberg | not a full RCA clean but should have gotten everything but trace metals | 20:16 |
| azonenberg | I'm now out of <110> wafers so i cant run any more tests of this type until i order another one from MTI | 20:17 |
| azonenberg | probably next month | 20:17 |
| azonenberg | In the meantime, i have these two wafers | 20:18 |
| azonenberg | one with so-so Ta2O5 on both sides and the other without any oxide | 20:18 |
| azonenberg | both coated in 5nm Cr and 1000nm Cu | 20:18 |
| azonenberg | on the polished sides | 20:18 |
| azonenberg | (one is double side and one is single) | 20:18 |
| azonenberg | Going to do some KOH testing to see how well the CuCr stack handles it | 20:18 |
| azonenberg | if the Cr improved adhesion enough i may be able to ditch the Ta2O5 entirely | 20:19 |
| azonenberg | at least for shallow etches | 20:19 |
| azonenberg | Also, Cr has virtually zero etch rate in KOH | 20:19 |
| azonenberg | actually no sorry | 20:19 |
| azonenberg | i was thinking Ni | 20:20 |
| nathan7 | the only etching would come from oxidation and stuff, I figure | 20:20 |
| azonenberg | Cr is around 5nm/min - low but definitely nonzero | 20:20 |
| azonenberg | KOH + Cu i'm told does react slightly | 20:20 |
| nathan7 | in an inert atmosphere it'd be zero | 20:20 |
| nathan7 | and yes, that forms cuprate if dissolved oxygen is there | 20:20 |
| nathan7 | again atmosphere screwing with it | 20:20 |
| azonenberg | How would i go about removing said oxygen? :P | 20:20 |
| nathan7 | inert atmosphere, run the water over something reducing | 20:21 |
| berndj | like potassium metal! | 20:21 |
| nathan7 | Yeah, that'll reduce your water too. | 20:21 |
| azonenberg | lol | 20:22 |
| nathan7 | I figure H2 could help | 20:22 |
| azonenberg | how about cesium :P | 20:22 |
| nathan7 | heh | 20:22 |
| berndj | i hope you guys have seen that sodium party website | 20:22 |
| berndj | H2 in presence of catalyst (Pt?): not a bad idea | 20:22 |
| nathan7 | Yeah. | 20:22 |
| nathan7 | Pd can absorb H2 | 20:22 |
| nathan7 | and if you buy Pd, azonenberg, give me a little =p | 20:23 |
| azonenberg | nathan7: Do i look like i'm made of money? :P | 20:23 |
| nathan7 | 0.3g will do, sir | 20:23 |
| azonenberg | good luck finding anyone willing to sell you 300mg of the stuff | 20:23 |
| nathan7 | Yeah. I should try cocaine. | 20:24 |
| nathan7 | maybe it works as a catalyst. | 20:24 |
| bart416 | lol | 20:24 |
| azonenberg | Lol | 20:24 |
| bart416 | what do you guys think about using conductive epoxy and then copper plating that | 20:24 |
| azonenberg | bart416: For what? | 20:24 |
| nathan7 | that | 20:24 |
| Last message repeated 1 time(s). | 20:24 | |
| nathan7 | I should try that | 20:24 |
| azonenberg | I was considering it for via plating | 20:24 |
| nathan7 | that sounds viable | 20:25 |
| azonenberg | :P | 20:25 |
| nathan7 | or spend ¬50 on a gramme of PdCl2 | 20:25 |
| azonenberg | Use something conductive, maybe silver pen or maybe conductive epoxy | 20:25 |
| azonenberg | then electroplate up | 20:25 |
| berndj | via plating: another interwebs research project that has so far frustrated me | 20:25 |
| bart416 | I'm considering it for making multilayer pcbs | 20:25 |
| nathan7 | PdCl2 is the standard way of doing vias | 20:25 |
| nathan7 | PdCl2, then SnCl2 | 20:25 |
| berndj | again, afaict palladium / platinum seem to be involved | 20:25 |
| nathan7 | then electroless plate it | 20:25 |
| nathan7 | and then electroplate | 20:25 |
| azonenberg | If anyone wants to put some time into developing a non-PdCl2 based process for via plating i'd be interested | 20:26 |
| nathan7 | ¬50 for 1g of PdCl2, lasts a lifetime | 20:26 |
| berndj | hmm... find a PCB manufacturer who'll let you scoop out a teaspoon of PdCl2? | 20:26 |
| azonenberg | lol | 20:26 |
| bart416 | I'm probably just going to end up asking a chemistry professor what's the best way to electroless copper plate something without killing yourself | 20:26 |
| nathan7 | Hmm? | 20:26 |
| nathan7 | electroless copper is just an aldehyde and a copper salt afaik | 20:26 |
| azonenberg | Like i said i'll gladly collaborate if you guys want to test a process | 20:26 |
| nathan7 | I wonder if auric chloride or something would work as well | 20:27 |
| berndj | collaborate, v., t.; we suggest random crazy stuff and azonenberg tries it out | 20:27 |
| azonenberg | lol | 20:27 |
| bart416 | nathan7, there's more to it | 20:27 |
| azonenberg | I expect some degree of sanity to the suggestions | 20:27 |
| nathan7 | surfactants and things | 20:27 |
| bart416 | You need to keep the pH in check | 20:27 |
| bart416 | And most methods generate cyanides | 20:27 |
| azonenberg | Oh fun | 20:27 |
| azonenberg | Anybody see problems with silver ink + electroplating? | 20:28 |
| nathan7 | not me | 20:28 |
| azonenberg | Do this before laying down photoresist | 20:28 |
| berndj | i think some ppl in the homebrew pcb world do exactly that | 20:28 |
| nathan7 | bart416: cyanides, are used for electroplating | 20:28 |
| nathan7 | matte electroplating | 20:28 |
| azonenberg | Then spin coat the board in PR, expose, develop, etch | 20:28 |
| azonenberg | Actually, maybe do the PR first | 20:29 |
| nathan7 | I have gotten beautiful shiny Cu plates with CuCl2 | 20:29 |
| azonenberg | nathan7: CuCl2? Interesting | 20:29 |
| azonenberg | How did you synthesize that | 20:29 |
| nathan7 | It works damn well. | 20:29 |
| bart416 | nathan7, I can do basic chemistry | 20:29 |
| nathan7 | I had some Cu(OH)2 left over from something | 20:29 |
| berndj | HCl + H2O2 + Cu | 20:29 |
| bart416 | But I'm certain there is a better way than anything we can come up with | 20:29 |
| azonenberg | Because CuxClx is a waste product of HCl:H2O2 etching of Cu | 20:29 |
| nathan7 | azonenberg: get CuO at pottery place | 20:29 |
| bart416 | I want something with chemicals I can buy easily without having to fill in 50 pages of paperwork if possible | 20:29 |
| azonenberg | I have a pretty significant amount of it (though dilute) | 20:29 |
| nathan7 | hmm | 20:30 |
| berndj | did you mean *pure* CuCl2? | 20:30 |
| nathan7 | etch PCBs with CuCl2/HCl(aq) | 20:30 |
| azonenberg | And if i could plate it out onto vias rather than having to dispose of it as hazardous waste | 20:30 |
| nathan7 | berndj: (aq), acidified. | 20:30 |
| nathan7 | to a fancy green colour :D | 20:30 |
| azonenberg | that would improve things | 20:30 |
| nathan7 | I use a copper anode | 20:30 |
| azonenberg | I could certainly boil it down to a reduced volume | 20:30 |
| nathan7 | I dunno, I try to keep it somewhat concentrated | 20:31 |
| azonenberg | the stuff i have is quite dilute because whenever i rinse Cu+ contaminted glassware (like etch beakers) i dump the first rinse in the waste jar | 20:31 |
| berndj | nathan7, do you know what potential you need to maintain to avoid etching the electrodes? | 20:31 |
| nathan7 | I have a something big amount of transition metal waste | 20:32 |
| nathan7 | in the form of hydroxides, some carbonates | 20:32 |
| nathan7 | meh, no, all hydroxides really | 20:32 |
| nathan7 | berndj: unsure | 20:32 |
| nathan7 | I was just plating experimentally for solderability | 20:32 |
| azonenberg | My waste right now is three big 950ml containers | 20:32 |
| berndj | my teenage electrolysis / electroplating experiments always just ended up as a green/grey/brown sludge :( | 20:33 |
| azonenberg | one (nearly empty) is HF based | 20:33 |
| nathan7 | well, teenage I am | 20:33 |
| nathan7 | and my electroplating seems to go fine (= | 20:33 |
| azonenberg | one is HCl/H2O2/CuxClx/water | 20:33 |
| berndj | which i now figure must've been Cu(OH)n | 20:33 |
| nathan7 | Acid, my friend. | 20:33 |
| nathan7 | You need more Hz | 20:33 |
| azonenberg | and one is mixed solvent waste (acetone, IPA, ethanol) | 20:33 |
| nathan7 | Apparently CuSO4/H2SO4 works well too | 20:33 |
| nathan7 | but I have little H2SO4 | 20:34 |
| nathan7 | fucking hell, a CFL | 20:34 |
| nathan7 | a *shitty* CFL at it | 20:34 |
| berndj | the last time i tried to plate anything was to get even just a *little* Cu onto an aluminium laser pointer battery tube | 20:35 |
| nathan7 | Al.. | 20:35 |
| nathan7 | Al is hell to plate | 20:35 |
| berndj | didn't plate nicely at all thoughj | 20:35 |
| nathan7 | you need to do zinc first | 20:35 |
| berndj | yeah, that damn oxide layer no doubt | 20:35 |
| nathan7 | before you plate *anything* onto Al, Zn first. | 20:35 |
| berndj | but it "worked": i managed to solder something onto the tube | 20:35 |
| nathan7 | Al reduction is an excellent way to make metal powders | 20:36 |
| bart416 | copper plating acrylic sucks | 20:36 |
| bart416 | I've done a few attempts already | 20:36 |
| nathan7 | acrylic?! | 20:36 |
| bart416 | plexiglas | 20:36 |
| nathan7 | awesome | 20:36 |
| nathan7 | I know | 20:36 |
| azonenberg | how do you do that | 20:36 |
| nathan7 | PMMA, acrylic, plexiglass | 20:36 |
| bart416 | azonenberg, as described above | 20:36 |
| azonenberg | But its nonconductive? | 20:37 |
| nathan7 | all the on-plastic plating seems to use PdCl2 first | 20:37 |
| bart416 | yeah, that's the issue | 20:37 |
| bart416 | My film forms | 20:37 |
| bart416 | but doesn't stick | 20:37 |
| nathan7 | then they do electroless Ni | 20:37 |
| azonenberg | ony plating methods i know of are electroplating, evaporation, and sputtering | 20:37 |
| azonenberg | for metals | 20:37 |
| azonenberg | and CVD for glasses | 20:37 |
| azonenberg | then spinning for polymers | 20:37 |
| berndj | azonenberg, i don't think this falls into your "sane" qualifier, but i was wondering if one could plate a pcb with gelatine or something, add bacteria, a mask, and a germicidal lamp | 20:38 |
| berndj | would be interesting to know the vapour pressure of pcb materials | 20:39 |
| bart416 | http://solutions.3m.com/wps/portal/3M/en_US/AdhesivesForElectronics/Home/Products/EMIEMC/TransparentConductors/ | 20:45 |
| bart416 | Are you thinking what I'm thinking? | 20:45 |
| bart416 | We want a thin, flexible sheet that's conductive to electrocoat... | 20:46 |
| bart416 | *plate | 20:46 |
| bart416 | That we can later chemically fuse together in layers | 20:46 |
| nathan7 | What you trying to do? | 20:51 |
| nathan7 | also, transparent conductors, isn't there this cheapish ITO alternativ | 20:51 |
| nathan7 | e | 20:51 |
| nathan7 | Al/Ga/doped ZnO | 20:52 |
| nathan7 | err | 20:52 |
| nathan7 | I misread that | 20:52 |
| bart416 | nathan7, something that's probably far too complicated for you | 20:52 |
| nathan7 | no | 20:52 |
| bart416 | copper deposition on acrylics with non expensive chemicals | 20:52 |
| nathan7 | Al/ZnO, Ga/ZnO or In/ZnO | 20:52 |
| nathan7 | Ga is cheapish | 20:53 |
| nathan7 | and easy to deposit | 20:53 |
| nathan7 | (ever played with Ga?) | 20:53 |
| bart416 | Multiple times | 20:53 |
| nathan7 | you can probably electroplate your hand after. | 20:53 |
| nathan7 | or, polyaniline | 20:54 |
| nathan7 | ammonium persulphate, aniline | 20:54 |
| nathan7 | no idea where to get aniline for non-chemists | 20:54 |
| bart416 | I can get anything that isn't high explosive or highly radioactive | 20:55 |
| nathan7 | aniline, ammonium persulphate. | 20:55 |
| berndj | i'd like a kilo of astatine please, thanks! | 20:55 |
| nathan7 | you have 8h to deliver it | 20:56 |
| nathan7 | most stable isotope | 20:56 |
| nathan7 | iirc | 20:56 |
| nathan7 | send 2kg, deliver in 8h | 20:56 |
| nathan7 | 1kg will arrive | 20:56 |
| berndj | and a ready-cooked meal | 20:56 |
| nathan7 | =p | 20:57 |
| nathan7 | also a hazmat van will arrive | 20:57 |
| berndj | good, i never like washing the dishes after i eat anyway | 20:57 |
| bart416 | astatine you say? | 20:57 |
| bart416 | Could probably do | 20:58 |
| berndj | hmm, have you played with gallium, nathan7 ? | 20:58 |
| bart416 | lol | 20:58 |
| nathan7 | bart416: yes | 20:58 |
| nathan7 | berndj* | 20:58 |
| berndj | did you get it on your skin and turn into the terminator | 20:58 |
| nathan7 | Yeah. | 20:58 |
| nathan7 | my gallium solidified recently | 20:58 |
| berndj | just how *do* you get it off again? | 20:58 |
| nathan7 | soap, water | 20:59 |
| berndj | i can't tell if you're pulling my leg :-/ | 20:59 |
| nathan7 | on a piece of kitchen paper | 20:59 |
| nathan7 | rub well | 20:59 |
| nathan7 | does wonders | 20:59 |
| bart416 | Am I the only person who wears gloves or what? O_o | 21:01 |
| Action: XgF kinda misses doing chemistry stuff | 21:02 | |
| nathan7 | bart416: not for gallium | 21:02 |
| bart416 | I always wear gloves when working with chemicals or pure materials | 21:03 |
| bart416 | Even if it's only to avoid contaminating them | 21:03 |
| nathan7 | yes, that gallium was just for toying with really | 21:04 |
| bart416 | Bismuth is better for that | 21:05 |
| bart416 | (though not healthier :P ) | 21:07 |
| berndj | does bismuth also wet the skin? | 22:01 |
| berndj | or what special properties are you referring to | 22:01 |
| adc | anyone have a pudn login? | 23:50 |
| --- Sat Aug 20 2011 | 00:00 | |
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