#homecmos IRC log for Friday, 2011-08-19

bart416azonenberg, would you trust a 1000 euro piece of equipment to an ikea table?16:53
azonenbergDepends, i dont have any ikea furiture16:53
azonenbergi have over 1000USD of equipment on a relatively cheap table now that's somewhat worrisome16:53
azonenbergwhile i am planning to replace it soon i don't feel the gear is in any immediate danger16:54
azonenbergAnd actually its probably closer to 2000USD16:54
azonenbergtwo microscopes, probing station, and fiber optic illuminator16:54
bart416well, this table looks sturdy at first sight17:00
bart416but the "wood" at the top is fairly light17:00
bart416If it's a layer of MDF with cardboard under it to fill up the space I don't mind17:02
bart416But else...17:02
adcwhos here17:26
adcthis should be a fun chan17:27
berndjdata 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 material18:24
berndjmy 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
bart416I've seen somebody fall through a glass table already18:26
berndjalso, unlike wood, chipboard and i guess MDF fails suddenly and catastrophically - it doesn't "yield" like real wood does18:26
berndjglass also doesn't yield :)18:26
berndjalthough that's likely to have been tempered glass, no?  so lots of little cubes rather than shards, i hope18:27
bart416yes it was tempered18:28
bart416but it still wasn't pretty18:28
bart416berndj, http://img688.imageshack.us/img688/7576/imag0484j.jpg18:29
berndji get a weird bit.ly frog in an ice cube :(  something about unregistered domain18:30
berndji'll try again later18:31
bart416just refresh18:31
bart416I also have it sometimes with imageshack18:31
XgFIt'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
azonenberghi adc18:38
azonenbergcheck the logs and lab notes on the googlecode repo to get up to speed on past work18:40
bart416berndj, does it work now?18:40
berndjazonenberg, i'm a bit behind with your tech.  your Ta2O5... do you start with some tantalum chloride in something-solution or what?18:40
berndjnope, still the frozen toad!18:40
bart416Also, please ignore the teken and doom3 posters, they're glued to the wall >_>18:40
bart416Does it work for you azonenberg ?18:41
XgFworks here18:41
berndjmaybe my isp is doing weird things18:42
XgFIt's my general observation that ISPs are like that18:43
berndjokay, getting it via ssh to another box18:43
berndjmaybe some confused "transparent" web proxy getting in the way18:44
azonenbergberndj: yes, i do18:44
azonenbergtantalum chloride in ethanol18:44
azonenbergspin coat, then bake in air at 200C for 1 hour18:44
azonenbergemulsitone tantalumfilm is the product i'm using18:44
azonenbergthey dont go into detail on the composition on the main page but the MSDS says its tantalum chloride in denatured alcohol18:45
azonenbergand i confirmed that by EDS18:45
berndjah, 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 kg18:45
nathan7azonenberg: and then?18:46
berndjazonenberg, 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
nathan7on a side note, where do you get that TaCl518:47
azonenbergberndj: 2TaCl5 + 5H2O = 10HCl + Ta2O518:47
azonenbergis the reaction afaik18:47
nathan7doesn't that give the oxychloride?18:48
bart416berndj, does a 5kg scope count? :P18:48
azonenbergI dont know the exact details, all i know is that the resulting film has the characteristics of tantalum oxide18:48
berndjpfft, maybe if you stack 10 of them!18:48
berndjnathan7, i imagine it's temperature-sensitive18:49
azonenbergnathan7: and when I ran EDS on the sample I found nothing but Si, O, Ta, and a trace of C (photoresist residue)18:49
nathan7it's just a guess, I don't know about tantalum18:49
berndjhigher temp would drive the equilibrium (if it's anywhere near the "middle") towards more HCl - 10HCl vs 5H20 - more degrees of freedom18:49
azonenbergI know tantalum oxychloride is formed in a similar reaction18:49
nathan7but anhydrous metal chlorides tend to do that18:49
azonenbergnathan7: http://www.emulsitone.com/taf.html18:50
azonenbergIts not a hot selling item18:50
azonenbergI'm the only customer for the lot number they sent me18:50
berndjand another thing azonenberg - how crazy do you go on reagent purity?18:50
azonenbergmade the batch on request for 500 USD lol18:50
azonenbergberndj: Not very for now since i'm not doing CMOS18:51
azonenbergi can get away with much lower tolerances18:51
nathan7Also, you seem to get all kinds of funny inorganics18:51
azonenbergthe photoresist is printed circuit board18:51
nathan7where'd I get PdCl2?18:51
berndji thought the semiconductor industry uses only an insane number of 9's in their purity of reagent, to avoid traces of unwanted stuff18:51
berndjbut 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
azonenbergmy NaOH and KOH are technical grade from a biodiesel vendor18:51
azonenbergso is the HCl18:51
azonenbergthe HF is sold in the grocery store as a rust remover18:52
XgFMy assumption is that MEMS is a lot less critical on purity?18:52
azonenberg3% H2O2 and ammnoia are from a drugstore18:52
nathan7I figured you'd know where to get some funny transition metal chloride18:52
berndjapropos HF, i've looked, but have not found anything HF-like in any normal shops18:52
azonenbergIPA is actually 99% / 1% DI water from a cleanroom supplier18:52
bart416If you need pure chemicals, go medical industry18:52
azonenbergberndj: Whink brand rust remover18:52
berndjthe only rust-pertaining products i've found seem to be based on phosphoric acid18:52
azonenbergmy acetone is from the same biodiesel supplier but i also have a can from a hardware store18:52
azonenbergI would not attempt CMOS with the stuff i have now, thats for sure18:53
berndj(i don't think we have whink here - i'm in ZA, not US)18:53
azonenbergBut for MEMS a few PPM of contaminants dont hurt anything18:53
azonenbergas long as it isnt enough to change the physical (rather than electrical) properties of the substrate18:53
Action: XgF thinks really this channel should be #homemems18:53
azonenbergXgF: CMOS is still on the wishlist18:54
azonenbergmuch of the equipment can be used for either18:54
azonenbergand once i get a furnace i plan to try duplicating jeri's transistor process18:54
berndjre ethanol / IPA, i imagine *water* itself isn't such a big deal - it also evaporates, albeit somewhat more slowly18:54
azonenbergberndj: Yes, but 70% drugstore grade tends to have salts etc in it18:54
berndjrather the sub-1% contaminants, whatever they may be.  assuming oily stuff18:54
berndjyes, and salts. indeed18:54
azonenbergnathan7: http://www.emulsitone.com/pdf.htmlmay be palladium chloride18:55
azonenberghttp://www.emulsitone.com/pdf.html may be*18:55
azonenbergit may be polymer based too18:55
azonenbergberndj: 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 stuff18:56
azonenbergso i'm gonna try and find highier grade at some point18:56
nathan7I need just a catalytic amount of PdCl218:56
azonenbergnathan7: Emulsitone won't sell you less than four ounces of their stuff18:56
azonenbergfluid ounces that is18:56
berndjsalts 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 thing18:56
azonenbergAnd the precious metal based ones tend to run around $500 for that volume18:56
XgFazonenberg: Hmm... what sort of purity do you need on the [denatured] alcohol?18:57
azonenbergWhen one says denatured alcohol, i assume that it's just ethanol with maybe 5% methanol18:57
azonenbergbut this stuff has other things inside too18:57
azonenbergmy guess is there's something oily18:58
berndjsigh, 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 here18:58
XgFDenatured alcohol always has other stuff inside18:58
XgFGenerally things like flavorants so it tastes disgusting18:58
azonenbergBut that's present in trace quantities in my HF too18:59
azonenbergand doesnt cause any problems18:59
bart416azonenberg, you need medical grade ethanol18:59
nathan7like you'd taste it before it's too late18:59
XgFThe list for UK denatured alcohol is pretty large18:59
bart416It's not that hard to get18:59
berndjor that purple stuff for methanol.  hobos here use bread to "filter it out", apparently18:59
bart416But it's pure18:59
azonenbergbart416: i'm seriously considering doing so18:59
azonenbergapparently you can buy it taxed as a beverage which saves all of the recordkeeping from buying untaxed 100% ethanol19:00
azonenbergcosts an extra few $$ per unit volume but if its 500ml of ACS trace metal grade ethanol then the extra $5 wont matter19:00
bart416Or you could try a bottle of cheap russian vodka19:00
bart416That's usually fairly pure ethanol as well :P19:00
azonenbergbart416: waaaay too many organics in that19:00
azonenberginsoluble organics that is19:01
bart416Organics can survive in that?19:01
XgF...99% ABV grain alcohol maybe?19:01
nathan7of course, bart41619:01
nathan7ethanol itself is organic =p19:01
bart416nathan7, I was joking :|19:01
Action: nathan7 hits bart416 19:01
bart416No but seriously, cheap russian vodka is probably far more pure than your denatured alcohol19:01
azonenberg$63 for 500ml of ethanol USP19:02
XgFComes up as £13.80 here :o19:03
azonenbergprob detected a .uk IP address lol19:03
XgFYEah, sent me to UK site, but you're beingq uoted ~3.5x the price19:03
azonenbergnot sure19:03
azonenbergThis is taxed as a beverage in the US19:04
azonenbergyou can get it untaxed (much cheaper) but there are all kinds of paperwork stuff to follow19:04
azonenbergto prove nobody is drinking it19:04
bart416Mhhh Sigma Aldrich became cheaper19:04
azonenbergeasier to get the taxed version since you're legally clear19:04
nathan7make sure to have the paperwork look like it was filled in by a drunk person19:04
bart416Damn their FTO glass is cheap o_O19:05
Action: XgF would be surprised if a bottle of lab ethanol turned up here with a UK duty tax sticker on it :p19:05
azonenbergi should place an order from these guys at some point19:06
bart416and they're also cheaper than most for their SU-8 o-O19:07
nathan7you can order there?19:07
nathan7ebay's ¬50/g is starting to look very reasonable19:09
bart416http://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-O19:09
nathan7looking at aldrich19:09
azonenbergbart416: is that su-8?19:09
nathan7¬87.50/g, wtf19:10
bart416but they had something that was chemically identical to SU-8 at first glance19:10
bart416might have been mistaken19:10
azonenbergi see19:10
nathan7If I could find someone who needed 0.5g of PdCl2, I can't afford a gram of that shit19:10
nathan7man, drugs are cheaper than this19:10
bart416Palladium is expensive :(19:11
nathan7I should use the Wacker oxidation to make drugs to be able to afford the PdCl219:11
nathan7except I need the PdCl2 in the first place19:11
bart416Where could you get palladium cheaply19:12
nathan7I should start stealing catalytic converters, I guess19:13
bart416Maybe steal one from a car accident scene before the police gets there19:13
bart416nathan7, hey cheer up19:15
bart416It's still cheaper than platinum!19:15
bart416Platinum is cool though19:17
bart416Probably one of the safest materials you can possibly handle19:17
azonenbergGold comes pretty close19:18
azonenbergin terms of unreactivity19:18
bart416well, from a medical point of view gold is better19:18
azonenbergPt/Pd/Au are all very unreactive19:18
Action: berndj wonders if platinum dust in your lungs would catalyse some mega bad reaction19:18
Action: azonenberg would prefer not to find out experimentally19:19
berndji thought titanium was pretty much king in terms of biocompatibility. but maybe rather due to relative cost and mechanical properties19:19
bart416pure elemental platinum or not berndj ?19:19
XgFberndj: isn't it the king in terms of biocompatibility while bring /rigid/? :p19:19
berndjbart416, i dunno?  i thought Pt as catalyst was pretty much just the metal?19:20
bart416elemental platinum shouldn't cause too much problems19:20
bart416some irritation I figure19:20
bart416also titanium has its mechanical properties19:20
bart416But gold has some interesting ones as well19:20
bart416azonenberg, that's another thing19:22
bart416You could potentially make bio implants with your Tantalum Oxide processes19:22
berndjheh, okay, not metallic Pt, but cisplatin would be nasty19:23
azonenbergbart416: Not likely :P19:23
azonenbergAnd i have no idea how biocompatible ta2o5 is19:23
bart416Nah, tantalum is biocompatible19:23
bart416It should be19:23
bart416Ta2O5 is stable as far as I remember19:23
azonenbergits a glass19:24
azonenbergalmost indestructible19:24
azonenbergHF is about the only thing that attacks it chemically19:24
azonenbergAn order of magnitude or so slower than SiO219:24
bart416how are the oxygen atoms arranged around it again?19:24
azonenbergNo idea19:24
azonenbergI treat it as potentially dangerous since i'd rather not find out the hard way it wasnt harmless19:24
azonenbergiow, with the same caution i'd use with my HF, conc. HCl, etc19:25
berndjexcept with those you KNOW a priori that they're not harmless!19:25
berndjand they make it pretty obvious that they aren't19:26
azonenbergBut the MSDS for this substance indicated it hadnt had any formal toxicity studies conducted19:26
azonenbergSo i treat it as potentially nasty19:26
azonenbergi may well be overreacting19:26
azonenbergbut i'd rather be safe19:26
bart416looks like Ta2O5 is safe19:27
azonenbergHow about the chloride though?19:27
berndjwell, 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 much19:27
bart416well yeah, only found one paper on it but meh19:27
bart416Chlorides are bad generally19:27
azonenbergThe glass is pretty obviously stable19:27
azonenbergThe chloride is what i'm concerned about19:28
bart416Chlorides are generally rather reactive19:28
azonenbergHence the usual gloves-lab coat-goggles routine19:28
berndji can't imagine the chloride ion itself could cause much harm: you have plenty of it in your body19:28
azonenbergberndj: The concern is the Ta+ ion19:28
berndjany toxicity would have to be special to the tantalum ioin19:28
bart416Tantalum on its own is biocompatible19:29
azonenbergbart416: Metallic, sure19:29
berndjyeah; 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
bart416berndj, just saying chlorides are generaly rather reactive, not that they themselves are bad19:30
bart416It's too complicated to bother19:30
bart416Quick glance I'd say Ta+ would start acting very similar to Mg+19:35
bart416You're not going to die from it unless it are large quantities19:35
azonenbergBut still, i have no plans to become any more casual in my handling of it19:36
bart416You don't want Tantalum bones?19:37
bart416Where do you think Magnesium ends up?19:39
azonenbergi'm saying, i dont :P19:40
bart416I thought you'd love that azonenberg, imagine how fun MRIs would become :P19:42
berndjmy *guess* would be you have more to worry about from the pH effects of TaCl5 interacting with your body than from Ta(V) itself19:45
berndjhttp://www.lookchem.com/Tantalum-chloride/ thinks its vapour pressure is 33900mmHg at 25°C :(19:47
berndjprobably they meant µmHg19:48
azonenbergLooks like its nasty if it gets inside19:49
azonenbergbut doesnt penetrate skin19:49
berndjbut: that page does have a safety section19:49
azonenbergits corrosive but not toxic on skin contact19:49
berndjpoison by intraperitoneal route.  iow, don't eat it19:49
azonenbergYeah lol19:49
berndjlol, LD50 at 1900mg/kg (the higher of two values)19:50
berndjthat's close to death by overeating19:51
azonenberg1.9 grams/kg? Yeah lol19:51
azonenbergthats a LOT19:51
azonenbergi dont even know if my entire bottle of solution is that much19:51
berndji 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
azonenbergi wouldnt use piranha in this lab lol19:53
berndjat some point you incur more risk in trying to avoid the original risk, than from accepting the original risk itself19:53
berndj(which i'm not saying you're doing)19:53
berndjhow closely can you control the layer thickness?19:54
azonenbergProcess control, especially on the tantalum oxide layers, is a sticky point right now19:55
azonenbergi'm having trouble getting consistent good film quality19:55
azonenbergPhotoresist and other stuff i can spincoat fine19:55
berndjand, can you produce a "clean" layer of Ta2O5 (smooth, mainly, and uniform thickness)?19:55
azonenbergOver what area?19:55
bart416mhhh, how hard would it be to dispose silver on acrylics19:55
berndjover a square foot or so :)19:55
azonenbergNot even close :P19:55
azonenbergi've had trouble on 2-inch wafers getting uniform coatings19:56
berndjwhat thickness do you typically try to deposit though?19:56
berndji'm just wondering if it's useful as a reflection-enhancing coating on optics (telescope mirrors)19:56
azonenbergNo, in fact the opposite19:56
azonenbergits routeinely used as an antireflective coating on lenses :P19:57
berndjits insolubility would be a boon19:57
berndjantireflective vs reflection-enhancing is just a matter of film thickness :)19:57
azonenbergHmm, good point19:57
azonenbergIn any case i'm having trouble getting good yields with it19:58
azonenbergtonight i'll actually be conducting some experiments with the goal of removing it from my process19:58
berndjin 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
azonenberg2.5ish i think?19:58
azonenbergthats for bulk material though19:58
azonenbergthin films may be different19:58
berndjwould 100nm count as "thin film"?19:59
azonenbergbut yes i think its higher than that of the lens19:59
azonenbergSubmicron, generally19:59
azonenbergas a rough rule of thumb19:59
berndjstill, it's an interesting idea; sounds like it's better than impossible to get hold of, it's water-insoluble, and good transmission window20:00
berndjwhat sort of non-uniformity were you getting?20:00
azonenbergFirst, pinholes in the surface20:01
berndjlocal or global, specifically?20:01
azonenbergthose were local and went all the way through the layer but were tiny20:01
berndji think pinholes wouldn't be a problem for a reflection coating20:01
azonenbergThen there were global thickness variations as well, probably due to viscosity of the solution20:01
azonenbergi think i need to thin it down more20:01
berndjmore important would be if you could maintain thickness to within a dozen percent over a square foot20:01
azonenbergA dozen percent? Hmm20:01
azonenbergI'm getting visible color variations right now over a 2-inch wafer20:02
berndjeven if not, it would probably still be better than no coating at all20:02
azonenbergBut hopefully the process can be improved to the point that this goes away20:02
berndjdo you know that those color variations are due to film thickness variations, and not just viewing angle?20:02
azonenbergThey show up under microscopy from a straight-down angle20:03
berndjyou could expect circles of fixed path length-difference showing up20:03
azonenbergand are consistent as i move around20:03
berndjsounds like the film then20:03
azonenbergthese are theta-related20:03
azonenbergstreaks going from center out to the rim, slightly thicker or thinner than the rest20:03
berndjoh right, yes, that does sound like what i'd expect from spin coating + too much viscosity20:04
berndjin fact i'm still surprised that spin coating works at all in giving a ~uniform film thickness20:04
azonenbergI need to get higher purity ethanol20:04
azonenbergto thin the solution down20:04
azonenbergthe stuff i was using seems to be contaminated somehow20:05
berndjcould ethanol evaporation be causing problems?  you'd have locally more-concentrated regions, which would be more viscous20:05
azonenbergI dont think so, i got better results in the past20:05
azonenbergthere is a contaminant somewhere and i suspect my ethanol20:06
azonenbergBut one experiment was anomalous20:06
berndjanyway, i don't think one can (easily) spin-coat a miror!20:06
azonenbergi got the same result from using pure tantalumfilm with no dilution20:06
azonenbergso either it wasnt as pure as i thought20:06
azonenbergor there is another variable out there20:06
azonenbergone i'm not seeing20:06
berndjwait, how much water was in your ethanol again?20:06
azonenbergi dont know20:07
azonenbergThe tantalumfilm is 16% solids by weight, the remainder is semiconductor grade denatured alcohol (which basically means ethanol+methanol w/ nothing else)20:07
azonenbergI prepared a dilution of a few drops of this mixed with my ethanol20:07
azonenbergWhich is paint store grade20:07
azonenbergi dont even have an msds for it listing the denaturants20:08
berndjyeah, i imagine any water at all would cause partial hydrolysis20:08
azonenbergOoh, interesting20:08
berndjdisclaimer: i'm just parroting wikipedia and my other google results from the last hour20:08
azonenbergyou're thinking my ethanol is contaminated with water20:08
azonenbergand that its hydrolyzing some of the stuff on contact without heating?20:08
berndjsomething like that20:09
XgFWater would be an especially cheap denaturant20:09
berndjso there might be some tantalum oxychloride20:09
azonenbergberndj: The results i was seeing were catastrophic though20:09
azonenbergnot a slight degradation in film quality20:09
azonenbergthere was no film to speak of20:09
azonenbergIt beaded up and didnt stick to the surface20:10
berndjit was that "flaky" looking stuff in your pics?20:10
azonenbergi pipette a ml or so of the solution (pure or diluted) onto a wafer20:10
nathan7OXYCHLORIDE, POW20:10
azonenbergspin at maximum speed on my spin coater20:10
berndjoh no, the flaky stuff was your PR20:10
azonenbergbefore spinning it formed a nice thin layer over the wafer20:11
azonenbergas i spin, i see it gradually thinning20:11
azonenbergthen radial lines start appearing20:11
azonenberg(well before it hits the desired thickness)20:11
berndja sort of surface tension thing?20:11
azonenbergso i remove power and spin down20:11
azonenbergand i see balls of solution in a relatively random pattern across the surface20:11
azonenbergsome free, some connected by narrow lines of coated area20:11
azonenbergthe rest of the silicon was uncoated20:12
azonenbergwish i had a photo but my hands had something on them and i didnt want to contaminte my camera20:12
berndjsounds like a surface tension issue20:13
berndjyour "silicon" (or maybe more likely, the SiO2 covering it) didn't like the film20:13
azonenberghence why i suspected a contaminant in the film20:13
azonenbergSince in the past it had worked beautifully20:13
azonenbergI tried stripping native oxide in HF20:13
azonenbergand coating immediately20:13
nathan7quaternary ammonium salt might help with wetting20:13
azonenbergthat didnt work any better20:13
azonenbergSo i re-grew the oxide in heated 3% H2O2 (didnt wnat to wait a week for it to form on its own)20:14
berndjcan contaminants cause such gross changes in surface tension behaviour?20:14
nathan7I figure it'd degrade to N2 during the oxidation steps20:14
azonenbergverified native oxide was present by the water-droplet test20:14
azonenbergand coated again20:14
azonenbergstill didnt work20:14
azonenbergafter three or four tries it spontaneously worked20:14
azonenbergi baked it, not wanting to risk losing a semi-decent film20:15
azonenbergthen after several tries got an ok-ish one on the back side20:15
azonenbergBut i have no idea what the variable was20:15
azonenbergSome of my best Ta2O5 films were gotten by diluting with alcohol20:15
berndjethanol soaking up whatever impurities were on the wafer?20:15
azonenbergthe same alocohol that i previously thought was my problem20:16
azonenbergI did an acetone rinse, then a native oxide strip followed by regrow20:16
azonenbergnot a full RCA clean but should have gotten everything but trace metals20:16
azonenbergI'm now out of <110> wafers so i cant run any more tests of this type until i order another one from MTI20:17
azonenbergprobably next month20:17
azonenbergIn the meantime, i have these two wafers20:18
azonenbergone with so-so Ta2O5 on both sides and the other without any oxide20:18
azonenbergboth coated in 5nm Cr and 1000nm Cu20:18
azonenbergon the polished sides20:18
azonenberg(one is double side and one is single)20:18
azonenbergGoing to do some KOH testing to see how well the CuCr stack handles it20:18
azonenbergif the Cr improved adhesion enough i may be able to ditch the Ta2O5 entirely20:19
azonenbergat least for shallow etches20:19
azonenbergAlso, Cr has virtually zero etch rate in KOH20:19
azonenbergactually no sorry20:19
azonenbergi was thinking Ni20:20
nathan7the only etching would come from oxidation and stuff, I figure20:20
azonenbergCr is around 5nm/min - low but definitely nonzero20:20
azonenbergKOH + Cu i'm told does react slightly20:20
nathan7in an inert atmosphere it'd be zero20:20
nathan7and yes, that forms cuprate if dissolved oxygen is there20:20
nathan7again atmosphere screwing with it20:20
azonenbergHow would i go about removing said oxygen? :P20:20
nathan7inert atmosphere, run the water over something reducing20:21
berndjlike potassium metal!20:21
nathan7Yeah, that'll reduce your water too.20:21
nathan7I figure H2 could help20:22
azonenberghow about cesium :P20:22
berndji hope you guys have seen that sodium party website20:22
berndjH2 in presence of catalyst (Pt?): not a bad idea20:22
nathan7Pd can absorb H220:22
nathan7and if you buy Pd, azonenberg, give me a little =p20:23
azonenbergnathan7: Do i look like i'm made of money? :P20:23
nathan70.3g will do, sir20:23
azonenberggood luck finding anyone willing to sell you 300mg of the stuff20:23
nathan7Yeah. I should try cocaine.20:24
nathan7maybe it works as a catalyst.20:24
bart416what do you guys think about using conductive epoxy and then copper plating that20:24
azonenbergbart416: For what?20:24
Last message repeated 1 time(s).20:24
nathan7I should try that20:24
azonenbergI was considering it for via plating20:24
nathan7that sounds viable20:25
nathan7or spend ¬50 on a gramme of PdCl220:25
azonenbergUse something conductive, maybe silver pen or maybe conductive epoxy20:25
azonenbergthen electroplate up20:25
berndjvia plating: another interwebs research project that has so far frustrated me20:25
bart416I'm considering it for making multilayer pcbs20:25
nathan7PdCl2 is the standard way of doing vias20:25
nathan7PdCl2, then SnCl220:25
berndjagain, afaict palladium / platinum seem to be involved20:25
nathan7then electroless plate it20:25
nathan7and then electroplate20:25
azonenbergIf anyone wants to put some time into developing a non-PdCl2 based process for via plating i'd be interested20:26
nathan7¬50 for 1g of PdCl2, lasts a lifetime20:26
berndjhmm... find a PCB manufacturer who'll let you scoop out a teaspoon of PdCl2?20:26
bart416I'm probably just going to end up asking a chemistry professor what's the best way to electroless copper plate something without killing yourself20:26
nathan7electroless copper is just an aldehyde and a copper salt afaik20:26
azonenbergLike i said i'll gladly collaborate if you guys want to test a process20:26
nathan7I wonder if auric chloride or something would work as well20:27
berndjcollaborate, v., t.; we suggest random crazy stuff and azonenberg tries it out20:27
bart416nathan7, there's more to it20:27
azonenbergI expect some degree of sanity to the suggestions20:27
nathan7surfactants and things20:27
bart416You need to keep the pH in check20:27
bart416And most methods generate cyanides20:27
azonenbergOh fun20:27
azonenbergAnybody see problems with silver ink + electroplating?20:28
nathan7not me20:28
azonenbergDo this before laying down photoresist20:28
berndji think some ppl in the homebrew pcb world do exactly that20:28
nathan7bart416: cyanides, are used for electroplating20:28
nathan7matte electroplating20:28
azonenbergThen spin coat the board in PR, expose, develop, etch20:28
azonenbergActually, maybe do the PR first20:29
nathan7I have gotten beautiful shiny Cu plates with CuCl220:29
azonenbergnathan7: CuCl2? Interesting20:29
azonenbergHow did you synthesize that20:29
nathan7It works damn well.20:29
bart416nathan7, I can do basic chemistry20:29
nathan7I had some Cu(OH)2 left over from something20:29
berndjHCl + H2O2 + Cu20:29
bart416But I'm certain there is a better way than anything we can come up with20:29
azonenbergBecause CuxClx is a waste product of HCl:H2O2 etching of Cu20:29
nathan7azonenberg: get CuO at pottery place20:29
bart416I want something with chemicals I can buy easily without having to fill in 50 pages of paperwork if possible20:29
azonenbergI have a pretty significant amount of it (though dilute)20:29
berndjdid you mean *pure* CuCl2?20:30
nathan7etch PCBs with CuCl2/HCl(aq)20:30
azonenbergAnd if i could plate it out onto vias rather than having to dispose of it as hazardous waste20:30
nathan7berndj: (aq), acidified.20:30
nathan7to a fancy green colour :D20:30
azonenbergthat would improve things20:30
nathan7I use a copper anode20:30
azonenbergI could certainly boil it down to a reduced volume20:30
nathan7I dunno, I try to keep it somewhat concentrated20:31
azonenbergthe stuff i have is quite dilute because whenever i rinse Cu+ contaminted glassware (like etch beakers) i dump the first rinse in the waste jar20:31
berndjnathan7, do you know what potential you need to maintain to avoid etching the electrodes?20:31
nathan7I have a something big amount of transition metal waste20:32
nathan7in the form of hydroxides, some carbonates20:32
nathan7meh, no, all hydroxides really20:32
nathan7berndj: unsure20:32
nathan7I was just plating experimentally for solderability20:32
azonenbergMy waste right now is three big 950ml containers20:32
berndjmy teenage electrolysis / electroplating experiments always just ended up as a green/grey/brown sludge :(20:33
azonenbergone (nearly empty) is HF based20:33
nathan7well, teenage I am20:33
nathan7and my electroplating seems to go fine (=20:33
azonenbergone is HCl/H2O2/CuxClx/water20:33
berndjwhich i now figure must've been Cu(OH)n20:33
nathan7Acid, my friend.20:33
nathan7You need more Hz20:33
azonenbergand one is mixed solvent waste (acetone, IPA, ethanol)20:33
nathan7Apparently CuSO4/H2SO4 works well too20:33
nathan7but I have little H2SO420:34
nathan7fucking hell, a CFL20:34
nathan7a *shitty* CFL at it20:34
berndjthe last time i tried to plate anything was to get even just a *little* Cu onto an aluminium laser pointer battery tube20:35
nathan7Al is hell to plate20:35
berndjdidn't plate nicely at all thoughj20:35
nathan7you need to do zinc first20:35
berndjyeah, that damn oxide layer no doubt20:35
nathan7before you plate *anything* onto Al, Zn first.20:35
berndjbut it "worked": i managed to solder something onto the tube20:35
nathan7Al reduction is an excellent way to make metal powders20:36
bart416copper plating acrylic sucks20:36
bart416I've done a few attempts already20:36
nathan7I know20:36
azonenberghow do you do that20:36
nathan7PMMA, acrylic, plexiglass20:36
bart416azonenberg, as described above20:36
azonenbergBut its nonconductive?20:37
nathan7all the on-plastic plating seems to use PdCl2 first20:37
bart416yeah, that's the issue20:37
bart416My film forms20:37
bart416but doesn't stick20:37
nathan7then they do electroless Ni20:37
azonenbergony plating methods i know of are electroplating, evaporation, and sputtering20:37
azonenbergfor metals20:37
azonenbergand CVD for glasses20:37
azonenbergthen spinning for polymers20:37
berndjazonenberg, 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 lamp20:38
berndjwould be interesting to know the vapour pressure of pcb materials20:39
bart416Are you thinking what I'm thinking?20:45
bart416We want a thin, flexible sheet that's conductive to electrocoat...20:46
bart416That we can later chemically fuse together in layers20:46
nathan7What you trying to do?20:51
nathan7also, transparent conductors, isn't there this cheapish ITO alternativ20:51
nathan7Al/Ga/doped ZnO20:52
nathan7I misread that20:52
bart416nathan7, something that's probably far too complicated for you20:52
bart416copper deposition on acrylics with non expensive chemicals20:52
nathan7Al/ZnO, Ga/ZnO or In/ZnO20:52
nathan7Ga is cheapish20:53
nathan7and easy to deposit20:53
nathan7(ever played with Ga?)20:53
bart416Multiple times20:53
nathan7you can probably electroplate your hand after.20:53
nathan7or, polyaniline20:54
nathan7ammonium persulphate, aniline20:54
nathan7no idea where to get aniline for non-chemists20:54
bart416I can get anything that isn't high explosive or highly radioactive20:55
nathan7aniline, ammonium persulphate.20:55
berndji'd like a kilo of astatine please, thanks!20:55
nathan7you have 8h to deliver it20:56
nathan7most stable isotope20:56
nathan7send 2kg, deliver in 8h20:56
nathan71kg will arrive20:56
berndjand a ready-cooked meal20:56
nathan7also a hazmat van will arrive20:57
berndjgood, i never like washing the dishes after i eat anyway20:57
bart416astatine you say?20:57
bart416Could probably do20:58
berndjhmm, have you played with gallium, nathan7 ?20:58
nathan7bart416: yes20:58
berndjdid you get it on your skin and turn into the terminator20:58
nathan7my gallium solidified recently20:58
berndjjust how *do* you get it off again?20:58
nathan7soap, water20:59
berndji can't tell if you're pulling my leg :-/20:59
nathan7on a piece of kitchen paper20:59
nathan7rub well20:59
nathan7does wonders20:59
bart416Am I the only person who wears gloves or what? O_o21:01
Action: XgF kinda misses doing chemistry stuff21:02
nathan7bart416: not for gallium21:02
bart416I always wear gloves when working with chemicals or pure materials21:03
bart416Even if it's only to avoid contaminating them21:03
nathan7yes, that gallium was just for toying with really21:04
bart416Bismuth is better for that21:05
bart416(though not healthier :P )21:07
berndjdoes bismuth also wet the skin?22:01
berndjor what special properties are you referring to22:01
adcanyone have a pudn login?23:50
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