swkhan | azonenberg_work: that sounds good. i'm not sure were i can pick them up without alerting other group mates to what i'm doing | 00:37 |
---|---|---|
swkhan | i should specify one thing. the furnace usually grows some iii-v semiconductor nanowires | 00:38 |
swkhan | and the surrounding quartz will need to be cleaned. do you mind if i keep some of the pieces of silicon? like take a wafer and cut it into a bunch of pieces and try to grow the thermal oxide on some for you + send them to you and then keep some for myself so it looks like i'm doing something with it too? | 00:39 |
azonenberg | Just got back from a meeting of the Capital District Microscopy and Microanalysis Society (http://cdmms.org/) | 01:06 |
azonenberg | I highly recommend similar groups if you can find any locally | 01:06 |
azonenberg | the lecture today was on microscopy of semiconductors, by a FA engineer at IBM | 01:07 |
kristianpaul | cdmms know about your current work about homecmos? | 02:40 |
azonenberg | kristianpaul: A few of the members do | 03:06 |
azonenberg | i havent presented or anything | 03:06 |
azonenberg | But i've asked around for advice on sample prep etc | 03:09 |
azonenberg | I actually just joined today | 03:09 |
azonenberg | I know several of the members and wnated to join before but coudlnt make the last meeting | 03:09 |
azonenberg | its usually every couple of months (3-5 times a year) | 03:10 |
azonenberg | They seem to be mostly focused on the various forms of electron microscopy but there is definitely interest in light microscopy as well as general sample prep techniques etc | 03:11 |
gkwhc | Hi, I'm new to semiconductor design & fabrication. I'd like to know if it will be hard to design/fabricate a simple logic/counter chip that runs on 0.005uA? Would this be a design problem or a fabrication problem, or both? | 04:55 |
azonenberg | gkwhc: Depends on what fab you're using, to start | 04:58 |
azonenberg | This channel is a little less about chip design (for now, at least) and more on building a working fab from scratch | 04:59 |
azonenberg | if you're using a "real" process in a "proper" lab it's a lot more doable | 04:59 |
azonenberg | 5 nA is low, but for only a few gates on a low-leakage process tech it should be possible | 04:59 |
azonenberg | On 20 micron living room CMOS, i'd say most likely not | 04:59 |
azonenberg | I'm focusing on MEMS right now but in a year or so i'll probably have made a working chip with a couple of gates on it (most likely a 74HC04 or similar in a 14-ball CSP BGA) | 05:01 |
azonenberg | as in power, ground, six in, six out | 05:02 |
azonenberg | In terms of "a simple logic chip" | 05:02 |
azonenberg | what are you starting from | 05:03 |
azonenberg | pre-existing cell library, just arranging gates? | 05:03 |
azonenberg | drawing each transistor yourself? | 05:03 |
gkwhc | azonenberg: I might be drawing each transistor for a greater learning curve | 05:12 |
gkwhc | i know a university that has proper equipments, but I am not sure if the 5nA is achieved through proper design or proper fabrication? | 05:12 |
azonenberg | gkwhc: Both | 05:17 |
azonenberg | Do they have a course in vlsi design? | 05:19 |
azonenberg | And/or fab techniques? | 05:19 |
gkwhc | no, unfortunately | 05:20 |
azonenberg | But you say they have fab equipment? | 05:21 |
gkwhc | well, I am an undergraduate student. most people who operate the equipments are graduate students who have had proper training/knowledge of the manufacturing process | 05:22 |
azonenberg | Oh, i see | 05:23 |
azonenberg | Well, you can always jump ahead in the theory | 05:23 |
azonenberg | start learning layout yourself | 05:24 |
azonenberg | there are a bunch of free tools for design, i linked to several on the project wiki | 05:24 |
gkwhc | yes! i downloaded several of them | 05:25 |
azonenberg | If you hang out here we'll gladly discuss layout issues etc | 05:25 |
gkwhc | can you suggest any getting-started ebooks/guides? | 05:25 |
azonenberg | I'm a bit busy right now as i have homework due tomorrow morning | 05:25 |
azonenberg | and hmm | 05:25 |
gkwhc | ah i see | 05:25 |
azonenberg | wikibooks has a nice one on microfab but thats mostly fab processes | 05:25 |
azonenberg | and less on the design | 05:25 |
gkwhc | mhm | 05:26 |
azonenberg | It depends also on what you want | 05:26 |
azonenberg | For example, B0101 is interested in Josephson junctions | 05:26 |
azonenberg | I'm doing MEMS but want to try CMOS at some point | 05:26 |
azonenberg | You want to do digital logic but are you more interested in MOS, bipolar, or not sure yet? | 05:27 |
gkwhc | I am not quite sure yet - the only constraint is very low current consumption :) | 05:27 |
azonenberg | What's your use case? | 05:27 |
gkwhc | Learning-by-doing a watch/clock logic, like how the industry does it. | 05:29 |
gkwhc | I mean, using a MCU is overkill | 05:29 |
azonenberg | Ok | 05:29 |
azonenberg | Well, there are a couple of things to do | 05:29 |
azonenberg | The first is to prototype your design in an FPGA or (better) a CPLD, using as few gates as possible | 05:30 |
azonenberg | At some point in the future you can then turn that into a netlist suitable for fab | 05:30 |
gkwhc | mhm | 05:30 |
gkwhc | I see | 05:30 |
gkwhc | and then I will need to use the EDA software like Alliance or Magic to create the layout? | 05:31 |
azonenberg | Yes | 05:38 |
gkwhc | thanks :) | 05:40 |
azonenberg | And then as for fab, well, there are a couple routes to go | 05:40 |
gkwhc | mhm | 05:41 |
azonenberg | Send it out to a commercial shop like MOSIS (expensive, doesn't teach you much, but will give you the best chance of working) | 05:41 |
azonenberg | Build it yourself in a proper lab (less expensive, you learn a lot, but you might screw it up) | 05:41 |
azonenberg | and hack it up in a home lab | 05:41 |
azonenberg | Cheaper to operate (though equipment costs may be high as you get started), extremely educational | 05:41 |
gkwhc | I was quite surprised to hear that ahome lab is possible! | 05:41 |
azonenberg | Possible, yes | 05:42 |
azonenberg | Successful so far, no | 05:42 |
azonenberg | http://colossus.cs.rpi.edu/~azonenberg/images/homecmos/2011-09-20/die_i4_009.jpg | 05:42 |
azonenberg | That's my best work to date | 05:42 |
azonenberg | imaged in a SEM on campus | 05:42 |
azonenberg | 20 micron half-pitch copper wires on a silicon substrate | 05:42 |
gkwhc | wow that is neat! | 05:42 |
azonenberg | The wiring turned out pretty well | 05:43 |
azonenberg | This is a long shot of the pattern http://colossus.cs.rpi.edu/~azonenberg/images/homecmos/2011-09-20/die_i4_002.jpg | 05:43 |
azonenberg | and http://colossus.cs.rpi.edu/~azonenberg/images/homecmos/2011-09-20/die_i4_001.jpg is the whole chip | 05:43 |
azonenberg | the entire chip is around 2x3mm | 05:43 |
azonenberg | of which the patterned area is around 0.5mm diameter | 05:43 |
azonenberg | I am planning to do both etching of the silicon itself (for making MEMS devices) and doping (for transistors) | 05:44 |
azonenberg | But have not yet gotten that far | 05:44 |
azonenberg | Photoresist coating and patterning is being done at home, as is etching | 05:44 |
azonenberg | I did the copper deposition on campus as well, i plan on building a vacuum coating rig | 05:45 |
azonenberg | at home | 05:45 |
gkwhc | wow | 05:45 |
azonenberg | But the chamber hasnt arrived yet (ordered) | 05:45 |
azonenberg | nice little 10x15 inch glass bell jar | 05:45 |
gkwhc | may I ask why do it at home if its possible on campus? | 05:45 |
azonenberg | And i have to use it for somebody else's research project first | 05:45 |
azonenberg | first, the on campus labs cost money to operate | 05:45 |
azonenberg | either out of my pocket or a grant | 05:45 |
azonenberg | Mine is relatively cheap to run | 05:46 |
azonenberg | Once the tooling is set up, that is | 05:46 |
azonenberg | And the processes are potentially scalable to a hgih school chem lab etc | 05:46 |
azonenberg | Which is the ultimate goal | 05:46 |
azonenberg | bring fab to the masses as much as feasible | 05:46 |
gkwhc | oh yeah, I just found out that it costs money to go into the lab today | 05:46 |
gkwhc | thats a good idea :) | 05:47 |
azonenberg | a HS science teacher should be able to build a comb drive in the classroom | 05:47 |
azonenberg | etc | 05:47 |
azonenberg | The second is that by doing all of the process development i have the fun of homebrewing it :p | 05:47 |
gkwhc | haha definitely! | 05:47 |
azonenberg | http://colossus.cs.rpi.edu/~azonenberg/images/homecmos/2011-09-20/overview_001.jpg is an overview of all of the chips i was imaging in that session | 05:47 |
azonenberg | Notice the patterned areas on the one at right are ~4x smaller | 05:48 |
azonenberg | and there are a couple of them | 05:48 |
azonenberg | That was an experimental run of the 5 micron process | 05:48 |
azonenberg | Which was unsuccessful | 05:48 |
gkwhc | from home? | 05:48 |
azonenberg | The pictures were taken in the older of the mat sci department's two SEMs | 05:48 |
azonenberg | The copper was deposited in the mat sci lab as well | 05:49 |
gkwhc | i see | 05:49 |
azonenberg | I did all of the lithograpy (including photoresist coating, exposure, developing, and etching) at home | 05:49 |
gkwhc | its rather hard for me to grasp how such is possible! since the patterns are layed on such a small scale | 05:50 |
azonenberg | gkwhc: My lab notes are in the google code repository under lithography_tests/labnotes/ | 05:51 |
azonenberg | They go into pretty good detail on fab processes | 05:51 |
gkwhc | great! | 05:51 |
azonenberg | tldr: print mask from layout tool on laser printer | 05:51 |
azonenberg | overhead transparency film | 05:51 |
azonenberg | 600 DPI | 05:51 |
azonenberg | 200 micron line width | 05:52 |
azonenberg | (its actually not exactly 200, it's five pixels / 600 pixels per inch) | 05:52 |
azonenberg | Anything <5 pix you run the risk of lines not being sharply defined on the printer | 05:52 |
gkwhc | interesting | 05:53 |
azonenberg | Then i stick the mask on top of the camera port of my microscope | 05:53 |
azonenberg | and shine a halogen lamp through it | 05:53 |
azonenberg | the objective reduces the mask image appropriately (I usually use a 10x objective) | 05:53 |
azonenberg | Which gives me 20um lines | 05:53 |
azonenberg | I tried the 40x objective for 5um lines but have so far had trouble getting consistent results | 05:53 |
azonenberg | i always under/overexpose | 05:53 |
azonenberg | the window for proper exposure time is narrower than on the 10x since features are smaller | 05:54 |
azonenberg | less margin for error | 05:54 |
azonenberg | I'm confident i'll get there eventually | 05:54 |
azonenberg | Just not there yet | 05:54 |
gkwhc | nice! | 05:54 |
azonenberg | For such a hacked process, not in a cleanroom or anything close to it, i think its turning out decently | 05:55 |
azonenberg | The current roadmap calls for a working MEMS comb drive by end of this calendar year | 05:55 |
azonenberg | and a working CMOS IC by the end of next year | 05:55 |
gkwhc | then its coming pretty soon! | 05:56 |
azonenberg | This is a spare-time project, i'm a PhD student (in computer science) who has classes to take, research to do, exams to grade, etc | 05:56 |
azonenberg | So work that would take a week or two of lab time, if that, takes months of calendar time | 05:56 |
azonenberg | i try to get at least one or two nights a week of work in my lab | 05:56 |
azonenberg | and then every month or two i do an imaging or evaporation run in the mat sci lab | 05:57 |
gkwhc | ah thats good scheduling | 05:57 |
azonenberg | It's rather rough | 05:57 |
azonenberg | You can see exact dates in the lab notes | 05:57 |
azonenberg | Whcih reminds me i never wrote a lab report from my last SEM session | 05:58 |
gkwhc | by the way, Ive been trying to find your lab notes but couldnt find them..are they under http://code.google.com/p/homecmos/ ? | 05:58 |
azonenberg | gotta do that soon | 05:58 |
azonenberg | http://code.google.com/p/homecmos/source/browse/trunk/lithography-tests/labnotes/azonenberg_labnotes.txt | 05:58 |
gkwhc | thanks!! | 05:59 |
gkwhc | azonenberg: Thank you soo much for the help & advices! Im gonna catch up on some sleep - its 2AM here! | 06:01 |
azonenberg | Photos from many of the lab sessions are at http://colossus.cs.rpi.edu/~azonenberg/images/homecmos/ | 06:01 |
azonenberg | I havent uploaded all of them yet unfortunately | 06:01 |
azonenberg | and it is here too | 06:01 |
azonenberg | where you at? | 06:01 |
gkwhc | Virginia Tech :) | 06:02 |
azonenberg | Ah | 06:02 |
azonenberg | RPI here | 06:02 |
gkwhc | cool! | 06:02 |
azonenberg | i'm off to finish two more hw problems before class tomorrrow | 06:03 |
azonenberg | ttyl | 06:03 |
gkwhc | bye! and thanks again! | 06:03 |
Action: azonenberg AFKs | 06:03 | |
azonenberg_work | Well... looks like I may not be getting much lab work done for a few days - homework to do, then busy all weekend | 16:26 |
azonenberg_work | But I want to do some KOH tests soon | 16:26 |
azonenberg_work | hopefully sunday evening or monday | 16:26 |
azonenberg_work | Or, if i'm lucky, tonight | 16:26 |
bart416 | azonenberg_work, we had a funny discussion today with some people at university | 16:41 |
bart416 | Writing a website in VHDL :P | 16:41 |
bart416 | Obviously integrated the web server into the fpga with only an external IC for the hardware layer of the network | 16:41 |
azonenberg_work | bart416: lol | 16:50 |
azonenberg_work | Would that be done with a softcore cpu (easy) or just raw tcp/ip/ethernet? | 16:50 |
azonenberg_work | Would be fun to say the least | 16:50 |
azonenberg_work | the lowest i've gotten so far was a webserver in x86-64 asm (no libc, just linux syscalls) | 16:50 |
azonenberg_work | but i used the linux tcp/ip stack | 16:50 |
lekernel | people did that already | 16:51 |
lekernel | there's a youtube video of it | 16:51 |
lekernel | it's a pretty stupid thing to do however | 16:51 |
azonenberg_work | Yeah | 16:51 |
azonenberg_work | More of a stunt than useful | 16:52 |
bart416 | raw tcp/ip ofc | 17:17 |
bart416 | No OS | 17:17 |
azonenberg_work | lol yeah | 17:17 |
bart416 | You have the hardware layer provided by the IC | 17:18 |
bart416 | But that's it | 17:18 |
bart416 | lekernel, it's still an interesting exercise | 17:18 |
bart416 | Especially if you would write a cross compiler | 17:18 |
bart416 | Say convert PHP to VHDL and then send it to whatever FPGA that you have | 17:18 |
azonenberg_work | Oh, lol | 17:19 |
azonenberg_work | server side scripting, not just static content? | 17:19 |
azonenberg_work | better yet, no cross compiler | 17:19 |
azonenberg_work | actually write HDL for the script :P | 17:19 |
bart416 | lol | 17:20 |
bart416 | That'd be hard | 17:20 |
bart416 | But if you'd convert PHP it would actually be useful | 17:20 |
azonenberg_work | reg[511:0] hdrs; | 17:20 |
bart416 | meh :P | 17:20 |
azonenberg_work | initial begin \ hdrs = "HTTP/1.1 200 OK\r\nX-Server: XC3S200A\r\n\r\n"; | 17:21 |
azonenberg_work | lol | 17:21 |
bart416 | The latest in Cloud-HDL-Computing! | 17:22 |
azonenberg_work | lol | 17:22 |
bart416 | We could start a new cloud hype with this lol | 17:22 |
azonenberg_work | One thing's for sure, it would be fast | 17:22 |
azonenberg_work | imagine having fifty webserver modules muxed into a giant output FIFO and an ethernet PHY | 17:22 |
bart416 | yeah, if you think about it, for a system that doesn't change often it'd actually be pretty effective | 17:22 |
azonenberg_work | store static html in block ram | 17:22 |
azonenberg_work | you could probably push Gbps of data without even trying too hard | 17:23 |
azonenberg_work | the NIC would be the bottleneck | 17:23 |
azonenberg_work | have preformed IP packets that you just patch up sequence numbers etc :p | 17:23 |
bart416 | Meh, 10 Gbps should be enough :P | 17:23 |
azonenberg_work | lol | 17:24 |
azonenberg_work | XC6SLX75T plus GBIC slot? | 17:24 |
azonenberg_work | s/GBIC/SFP | 17:24 |
bart416 | lol | 17:24 |
azonenberg_work | Or ditch the SFP and just have a raw fiber connector | 17:25 |
bart416 | What we're actually considering doing is building a complete processor on transistor level (16 bit) without any help from software | 17:26 |
azonenberg_work | who's "we" | 17:26 |
bart416 | EE students | 17:26 |
azonenberg_work | and you want to do it by hand, like the 4004 was? | 17:26 |
azonenberg_work | or using cad but no synthesis? | 17:26 |
bart416 | by hand | 17:26 |
azonenberg_work | i.e draw out cells, then place and route by hand? | 17:26 |
bart416 | No software | 17:26 |
azonenberg_work | THAT is just crazy lol | 17:26 |
bart416 | No PCBs though | 17:26 |
azonenberg_work | i could understand doing it without synthesis | 17:26 |
bart416 | Just wiring | 17:26 |
azonenberg_work | Oh | 17:26 |
azonenberg_work | i thought you meant vlsi lol | 17:27 |
bart416 | Modules can be PCBs | 17:27 |
bart416 | You nuts? | 17:27 |
bart416 | We're with 7 people | 17:27 |
bart416 | It'd take us months | 17:27 |
azonenberg_work | Not really | 17:27 |
azonenberg_work | Do the design on paper, maybe start with HDL and hand synthesize | 17:28 |
bart416 | Keep in mind we also have classes | 17:28 |
azonenberg_work | then design a bunch of logic cells | 17:28 |
bart416 | I meant VLSI | 17:28 |
azonenberg_work | cut and paste to form a reasonable (though perhaps not optimal) placement | 17:28 |
lekernel | you'd need inane amounts of transistors | 17:28 |
azonenberg_work | draw out routing | 17:28 |
lekernel | 4 bits could be feasible, but 16 ... | 17:28 |
azonenberg_work | You dont draw each transsitor by hand | 17:28 |
bart416 | That'd take months in the bit of time we have though azonenberg | 17:28 |
bart416 | easily | 17:28 |
lekernel | you'd need a cabinet | 17:28 |
bart416 | Yes, we will need a cabinet | 17:28 |
bart416 | that's the point | 17:28 |
azonenberg_work | lol | 17:28 |
bart416 | We want to prove a professor wrong | 17:29 |
azonenberg_work | Why not use 7400 chips | 17:29 |
bart416 | lol | 17:29 |
azonenberg_work | ... oh | 17:29 |
azonenberg_work | lol | 17:29 |
azonenberg_work | Thats a worthy excuse | 17:29 |
azonenberg_work | i've done crazy things to prove faculty wrong | 17:29 |
bart416 | Cause with 7400 chips it's just stupid and anybody can do it | 17:29 |
bart416 | With 7400 series it takes almost no skill to make a small functional CPU | 17:29 |
azonenberg_work | Like doing full functional programming (including passing a function as an argument to another function) in C | 17:29 |
azonenberg_work | when he said it wasnt possible to do functional programming | 17:30 |
azonenberg_work | Or writing an entire file system emulator (including the command line argument parsing) in x86 assembly | 17:30 |
azonenberg_work | 3000 lines in two weeks, including other homework | 17:30 |
azonenberg_work | Or implementing an algorithm for solving the Towers of Hanoi puzzle (algorithm given to us) in x86 (which was the assignment) | 17:30 |
azonenberg_work | But doing it in 19 instructions | 17:31 |
azonenberg_work | when he said <20 was impossible | 17:31 |
bart416 | We had a fun one | 17:31 |
bart416 | Random dice throw generator | 17:31 |
bart416 | But only 2 d latch flip flops | 17:31 |
bart416 | Not as easy as it looks | 17:31 |
bart416 | (and it has to be able to hold a *random* value and be able to reset) | 17:32 |
bart416 | Using only digital logic | 17:32 |
bart416 | And you're not allowed to make new flip flops | 17:32 |
azonenberg_work | Random number generator | 17:33 |
azonenberg_work | Using two dff | 17:33 |
bart416 | The random generator is easy | 17:33 |
bart416 | Just use the system clock | 17:33 |
bart416 | that was available | 17:33 |
azonenberg_work | Ok, if it has one | 17:33 |
azonenberg_work | But two dff | 17:33 |
azonenberg_work | for six values | 17:33 |
azonenberg_work | you only have two bits? | 17:33 |
bart416 | It's possible weirdly enough | 17:33 |
azonenberg_work | Oh, i believe you | 17:34 |
azonenberg_work | i'm curious now | 17:34 |
azonenberg_work | was it a dynamic state? | 17:34 |
bart416 | I never found it myself either | 17:34 |
azonenberg_work | three bits, two in flipflops and one in motion? | 17:34 |
bart416 | I think he used the clock and somehow locked it as the final bit | 17:34 |
azonenberg_work | like a circular shift register | 17:34 |
azonenberg_work | crossed with a delay line | 17:34 |
azonenberg_work | Just caught my pipelining bug | 17:40 |
azonenberg_work | The latest one, at least | 17:40 |
azonenberg_work | Subject: test program busy-waits on UART data ready, then reads byte, adds one, echoes out uart | 17:40 |
azonenberg_work | repeats forever | 17:40 |
azonenberg_work | Symptom: after processing 16 bytes (depth of the FIFO) it goes nuts and starts echoing the same value over and over | 17:41 |
azonenberg_work | Eventually traced it to a bug where issuing a conditional the clock after a memory read would give an incorrect value if you used the result of the memory read | 17:41 |
berndj | bart416, cutting mylar tape? | 17:54 |
bart416 | What about it berndj? | 17:54 |
berndj | azonenberg_work, i've actually got a pipe dream of a fully trustable computer that's consist of *only* 74*00's | 17:55 |
mrdata | lol | 17:55 |
berndj | maybe not quite as trustable as relays as switching elements | 17:55 |
bart416 | Prepare for a very expensive project berndj :P | 17:55 |
mrdata | "fully trustable"! | 17:55 |
berndj | yes, a bit like "a little bit pregnant" :-/ | 17:57 |
berndj | bart416, i was referring to your no-software layout | 17:57 |
bart416 | How does that relate to mylar tape? | 17:58 |
Action: azonenberg_work needs to get some kapton tape | 17:58 | |
bart416 | We have enough breadboards at college to model an entire x86 cpu on them I think | 17:58 |
azonenberg_work | bart416: lol | 17:59 |
azonenberg_work | maybe an 8086 | 17:59 |
azonenberg_work | not an i7 :p | 17:59 |
berndj | bart416, i thought that's how they did 4004-era chips | 17:59 |
bart416 | azonenberg, uhm the professor has a few cabinets in his office filled with boxes with nothing but breadboards... | 17:59 |
berndj | and 8086 was about 35000 transistors IIRC, is that an "insane" number? | 17:59 |
azonenberg_work | berndj: if you are going to do that | 18:00 |
bart416 | 35000, meh | 18:00 |
azonenberg_work | Design custom PCBs for each 7400 chip | 18:00 |
azonenberg_work | Have a few dozen of each sent out | 18:00 |
azonenberg_work | s/dozen/hundred | 18:00 |
azonenberg_work | and load them up with SOT23 mosfets | 18:00 |
berndj | azonenberg_work, yes, i was going to do it like that, have an "adder" board that gets reused a few times etc | 18:00 |
mrdata | what would a MEMS pressure sensor look like? | 18:00 |
azonenberg_work | s/7400/4000 | 18:00 |
bart416 | I'd guess a sort of membrane ish structure | 18:01 |
berndj | oh, but i'd make it a (super slow) bit slice processor, taking 16 cycles to do a 16-bit ALU op | 18:01 |
azonenberg_work | mrdata: Thats like saying what would a car look like | 18:01 |
azonenberg_work | It deends completely on the design | 18:01 |
azonenberg_work | parallel membranes is one option | 18:01 |
bart416 | and using the capacity between the membranes as reference | 18:01 |
azonenberg_work | Yeah | 18:01 |
azonenberg_work | That would be my first thought | 18:01 |
bart416 | Looks the easiest way to go about it | 18:01 |
azonenberg_work | i'd do it from two bonded wafers | 18:01 |
bart416 | But there might also be materials that change conductivity based on pressure I'd guess | 18:02 |
berndj | if you used mosfets i guess you could have PCBs with nothing but transistors on them, right? | 18:02 |
berndj | no resistors for bias etc | 18:02 |
azonenberg_work | berndj: yes | 18:02 |
azonenberg_work | Do CMOS | 18:02 |
azonenberg_work | sot23 fets | 18:02 |
berndj | how many SOT23 could you fit on a board? on the order of 1000? | 18:02 |
azonenberg_work | berndj: i was thinking making them 4000 series actually | 18:02 |
Action: mrdata likes the parallel membranes; how hard would that be to make? | 18:03 | |
azonenberg_work | a wide (0.6 inch) dip14 etc | 18:03 |
azonenberg_work | but if you want to do more complex modules thats fine | 18:03 |
azonenberg_work | mrdata: Hmm | 18:03 |
azonenberg_work | Let's see, we need a framework | 18:03 |
mrdata | ok | 18:03 |
azonenberg_work | two parallel membranes with an air gap between them | 18:03 |
mrdata | sure | 18:03 |
azonenberg_work | Both conductive, and insulated from their surroundings | 18:03 |
berndj | azonenberg_work, ooh, you mean making little modules out of 7400-only, that emulate the other common logic functions? | 18:03 |
azonenberg_work | And not touching | 18:03 |
azonenberg_work | berndj: i was saying to make a DIP14 sized PCB with a few dozen sot23 (wide dip) | 18:04 |
berndj | oh, lol | 18:04 |
azonenberg_work | for a 4x 2NAND etc | 18:04 |
mrdata | how small could it be made? what equipment would i want, to fab these? | 18:04 |
bart416 | mrdata, you could do this fairly large scale actually | 18:05 |
azonenberg_work | mrdata: Well, let's see | 18:05 |
berndj | hmm, to make a 7404 you'd need 12 transistors; can you fit them all? | 18:05 |
azonenberg_work | Bonded wafers is something i havent looked into | 18:05 |
bart416 | azonenberg, I'd do this large scale | 18:05 |
bart416 | Take mylar | 18:05 |
bart416 | Space it slightly | 18:05 |
bart416 | so you have maybe a mm in between | 18:05 |
azonenberg_work | bart416: i am thinking mems:p | 18:05 |
bart416 | yeah, but if you have to make it at home | 18:05 |
azonenberg_work | Actually a pressure sensor would be a cool project once i do the comb drive | 18:06 |
mrdata | yes | 18:06 |
azonenberg_work | let me see, i read an interesting paper on making membranes by KOH etch of silicon | 18:06 |
azonenberg_work | with heavy boron doping as an etch-stop layer | 18:07 |
azonenberg_work | I have a slightly different idea | 18:07 |
azonenberg_work | Bottom wafer is the carrier | 18:07 |
azonenberg_work | the die has a ground terminal on it | 18:07 |
azonenberg_work | and a big conductive disk | 18:08 |
Action: mrdata is thinking about the size of an LED | 18:08 | |
azonenberg_work | mrdata: yeah, thats doable | 18:08 |
azonenberg_work | So i was thinking of having a copper membrane | 18:08 |
azonenberg_work | Deposited over silicon | 18:08 |
azonenberg_work | then you etch the silicon out from under it | 18:08 |
azonenberg_work | leaving it around the edges to support the membrane | 18:08 |
azonenberg_work | you then place this framed membrane over another, stationary, conductor | 18:09 |
azonenberg_work | apply pressure to the hole the membrane is in | 18:10 |
azonenberg_work | and it will bow down | 18:10 |
azonenberg_work | reducing plate separation | 18:10 |
mrdata | yes | 18:10 |
mrdata | and how would you etch the silicon? | 18:11 |
azonenberg_work | KOH, thats easy | 18:11 |
azonenberg_work | the harder part is masking it | 18:11 |
azonenberg_work | Anyway so the thinking is | 18:11 |
azonenberg_work | Bottom wafer, cover in copper | 18:11 |
azonenberg_work | attach a ground terminal to the copper | 18:11 |
azonenberg_work | s/wafer/die | 18:11 |
azonenberg_work | Top die, cover top side in copper | 18:12 |
azonenberg_work | flop over, put etch mask on bottom (material tbd) | 18:12 |
azonenberg_work | put circular hole in the middle of this mask | 18:12 |
azonenberg_work | oh, when you cover the top die in copper | 18:12 |
azonenberg_work | do it over thermal oxide | 18:12 |
azonenberg_work | So you have a circular hole in the mask | 18:12 |
azonenberg_work | then you KOH through the top wafer from bottom up | 18:12 |
azonenberg_work | This leaves us a big silicon die | 18:13 |
azonenberg_work | with copper over the entire top surface | 18:13 |
azonenberg_work | insulated from the silicon | 18:13 |
azonenberg_work | by an oxide layer | 18:13 |
azonenberg_work | the center of the die is just a copper film with nothing under it | 18:13 |
azonenberg_work | thats our sensing element | 18:13 |
azonenberg_work | Then we bond this to the original bottom die | 18:14 |
azonenberg_work | hook a wire up to each copper laye | 18:14 |
azonenberg_work | r | 18:14 |
azonenberg_work | Bonding the dies together is a TBD problem | 18:14 |
azonenberg_work | make sense? | 18:14 |
mrdata | kind-of | 18:14 |
azonenberg_work | the two unsolved problems in that process as far as i'm concerned are how to mask the KOH etch | 18:15 |
azonenberg_work | and how to attach the wafers to each other | 18:15 |
azonenberg_work | the second i havent looked at much | 18:15 |
azonenberg_work | the first is something i am actively exploring | 18:15 |
mrdata | i've etched aluminum with NaOH | 18:16 |
mrdata | but havent etched any silicon | 18:16 |
azonenberg_work | mrdata: NaOH or KOH is simple enough to use, they are very similiar | 18:16 |
azonenberg_work | The hard part is masking them | 18:16 |
mrdata | yes | 18:16 |
azonenberg_work | As they eat photoresist (among other things) | 18:17 |
mrdata | saponification, yeah | 18:17 |
azonenberg_work | So you basically need a metal or oxide hardmask | 18:18 |
azonenberg_work | and they eat SiO2 as well - around 40x slower than Si but its a nontrivial rate | 18:18 |
azonenberg_work | normally they use silicon nitride but thats hard for an amateur to make | 18:19 |
mrdata | do they eat vinyl? | 18:19 |
azonenberg_work | mrdata: not sue | 18:20 |
azonenberg_work | never seen characterizatinos of that reaction | 18:20 |
berndj | do pretty much all SOT23's have the same pinout? | 18:21 |
Action: mrdata wouldnt assume so | 18:22 | |
berndj | or rather, is it less of a mess than through-hole devices | 18:22 |
azonenberg_work | berndj: my guess is, no | 18:25 |
mrdata | hmm... http://memscyclopedia.org/su8.html | 18:31 |
azonenberg_work | mrdata: su-8 is fun stuff but its almost impossible to remove once patterned | 18:31 |
mrdata | oh really | 18:32 |
azonenberg_work | useful more as a directly photosensitive structural material than a photoresist | 18:32 |
azonenberg_work | its epoxy based | 18:32 |
azonenberg_work | you spin coat, expose, develop | 18:32 |
azonenberg_work | then i think anything that was hit by UV is now crosslinked | 18:32 |
azonenberg_work | and super strong | 18:32 |
azonenberg_work | anything that wasnt gets washed off | 18:32 |
berndj | hmm, 2 SOT23s right next to each other already occupy 1/4 of a 300mil-wide DIP14 footprint :( | 18:36 |
azonenberg_work | berndj: use a 6 | 18:36 |
azonenberg_work | its gonna be big | 18:36 |
azonenberg_work | also, compnents on both sides | 18:36 |
azonenberg_work | components* | 18:36 |
berndj | hmm, i didn't think of that | 18:36 |
azonenberg_work | also | 18:36 |
azonenberg_work | look into transistor arrays | 18:37 |
azonenberg_work | i think you can get like a TSSOP with 12 pins and four transistors | 18:37 |
azonenberg_work | they're technically ics, but might be ok to use since there is no connectivity on the die | 18:37 |
bart416 | SU-8 is also extremely expensive | 18:39 |
azonenberg_work | bart416: how much | 18:39 |
azonenberg_work | never looked into buying it | 18:39 |
bart416 | Don't remember exact pricing | 18:40 |
bart416 | But remember, I looked at it for my home multi layer pcb project | 18:40 |
azonenberg_work | Yeah | 18:40 |
azonenberg_work | but is it more expensive than other semiconductor grade chemicals? | 18:40 |
bart416 | It's far more expensive than regular resist you'd use for semiconductor grade | 18:41 |
bart416 | Even when ordered with educational discount through the university | 18:41 |
azonenberg_work | Interesting | 18:41 |
bart416 | http://www.mesacrl.utwente.nl/mis/generalinfo/downloads/equipment/Delta%2020%20SU-8/Description%20of%20SU.pdf | 18:43 |
bart416 | Chemical structure is fairly complex | 18:43 |
azonenberg_work | Is the epoxy itself photosensitive or is it mixed with an initiator of some sort? | 18:44 |
bart416 | It's photoresist | 18:44 |
bart416 | check the pdf I linked | 18:45 |
bart416 | It mentions A complete SU-8 process consists of: spin coat, soft bake, exposure, post expose bake | 18:45 |
bart416 | and development | 18:45 |
azonenberg_work | i know that much | 18:45 |
azonenberg_work | what i meant was, chemically | 18:45 |
azonenberg_work | is it one substance or two | 18:45 |
mrdata | if you skip some of those steps, maybe it isnt permanent? | 18:46 |
azonenberg_work | for example DNQ-novolac resists are DNQ (photosensitive) + novolac (resin) | 18:46 |
azonenberg_work | mrdata: no, the exposure makesi t permanent | 18:46 |
azonenberg_work | PEB is just to smooth edges | 18:46 |
mrdata | ok | 18:47 |
bart416 | Good question | 18:47 |
bart416 | And it's so complex that I don't even have a clue on how to synthesise it easily at home | 18:50 |
azonenberg_work | ll | 18:51 |
azonenberg_work | lol* | 18:51 |
azonenberg_work | i woudlnt even attempt i | 18:51 |
azonenberg_work | heck, i wouldnt attempt DNQ personally | 18:51 |
azonenberg_work | Some materials it just isnt feasible to homebrew | 18:51 |
mrdata | ++ungood | 18:52 |
bart416 | DNQ I'd be willing to try | 18:52 |
mrdata | if i cant homebrew, then my post-apocalyptic MEMS lab will be ruined | 18:53 |
azonenberg_work | mrdata: no, you cant homebrew SU8 | 18:55 |
azonenberg_work | that doesnt mean you cant do other stuf | 18:55 |
azonenberg_work | i'm already doing alternate materials as i cant feasibly do CVD or RIE | 18:55 |
mrdata | then i'll have to take up bread baking | 18:55 |
bart416 | SU8 is complicated | 18:55 |
azonenberg_work | mrdata: you could also become a nomadic warlord | 18:55 |
bart416 | IBM didn't even mention the composition in the patent | 18:55 |
bart416 | grrr >_> | 18:55 |
mrdata | hmm... perhaps | 18:56 |
azonenberg_work | patent expired yet? | 18:56 |
bart416 | how long do US patents last? | 18:56 |
azonenberg_work | 17 years last time i checked | 18:56 |
mrdata | didn't even mention the composition??!? failure to disclose that would tend to invalidate the patent | 18:56 |
bart416 | It was issued Nov 21, 1989 | 18:56 |
azonenberg_work | mrdata: actually, the patent might be more generic | 18:56 |
azonenberg_work | and k, it should be expired now | 18:56 |
bart416 | http://www.google.com/patents?id=8943AAAAEBAJ&zoom=4&pg=PA1#v=onepage&q=synthesis&f=false | 18:57 |
azonenberg_work | So thats a non-issue | 18:57 |
mrdata | good | 18:57 |
azonenberg_work | The composition is most likely a trade scret | 18:57 |
mrdata | oh, as in, it's a base patent? | 18:57 |
azonenberg_work | that nobody has bothered to reverse engineer | 18:57 |
mrdata | let's reverse engineer a better one, then | 18:57 |
azonenberg_work | Or that somebody has, but not published it | 18:57 |
bart416 | They mention some names | 18:57 |
azonenberg_work | Or has, published it, and we havent found it :p | 18:57 |
bart416 | But nothing exact | 18:57 |
Action: mrdata decides to start with vinyl | 18:58 | |
azonenberg_work | Alternative solutions are a definite possibility | 18:58 |
bart416 | Homebrewing SU8 would be a worthwhile project on its own... | 18:58 |
azonenberg_work | lol, yes | 18:58 |
berndj | mrdata, re post-apocalyptic semi fab, what about bacterial cultures | 18:59 |
berndj | place mask, then feed them sunlight and starch / gelatine | 18:59 |
azonenberg_work | berndj: lol | 18:59 |
bart416 | Mhhh, I wonder if I could get the chemicals they list in the example | 19:00 |
berndj | some kind of bacterium that photosynthesizes, of course | 19:00 |
mrdata | berndj, yes, bacterial cultures | 19:00 |
mrdata | that's why bread | 19:00 |
mrdata | sourdough, actually | 19:00 |
berndj | lol, i just took a loaf of sourdough bread out the oven | 19:00 |
mrdata | whee! | 19:00 |
berndj | but how do you selectively kill it? will UV-A do? | 19:01 |
berndj | UV-B and C might be harder to do optics for | 19:01 |
mrdata | seems probable that UV-A could kill it, yes | 19:01 |
mrdata | but KOH would also etch it, likely | 19:01 |
azonenberg_work | berndj: I've done contact litho with UV-C | 19:02 |
azonenberg_work | unshielded mercury vapor germicidal tubes | 19:02 |
berndj | *post-apocalyptic optics | 19:02 |
azonenberg_work | berndj: Mercury, vacuum, glass tube | 19:02 |
berndj | hmm, the UV-C source i can still imagine, but what is the mask made of? | 19:03 |
azonenberg_work | post-apocalyptic? Harder | 19:03 |
azonenberg_work | i used a laser printer + transparency film | 19:03 |
azonenberg_work | hobbyist friendly but requires some infrastructure | 19:03 |
berndj | same stuff the bulb envelope is made of, i guess | 19:03 |
azonenberg_work | You could do chrome on glass, but have to pattern that somehow | 19:04 |
berndj | yes, with a sharp-pointed rock | 19:04 |
azonenberg_work | berndj: lol | 19:04 |
berndj | might want to reduce the mask though, which would need optics | 19:04 |
azonenberg_work | I think you should get basic chemistry and machining working first | 19:04 |
berndj | yeah | 19:05 |
bart416 | basic chemistry is hard without basic machining | 19:05 |
bart416 | You'd need to be able to blow your own glass instruments and grind your lenses | 19:05 |
berndj | but i think getting up to manually operated machine tools is a hard, but solved problem | 19:05 |
mrdata | post-apocalyptic optics could fall back to galileo | 19:05 |
berndj | with things like the gingery lathe and opensourceecology, you've got the metal supply and tool design covered | 19:06 |
berndj | soda-lime glass is probably *just* doable | 19:06 |
mrdata | renaissance glass making | 19:06 |
berndj | but something that works well in UV? much harder | 19:06 |
bart416 | You need a blast furnace to make glass | 19:07 |
berndj | you need high-purity silica to start with | 19:07 |
mrdata | in Venice. that's where they learned it | 19:07 |
berndj | not even - a blast furnace is for steel | 19:07 |
mrdata | 1000C should do | 19:07 |
mrdata | for a lot of stuff | 19:07 |
mrdata | maybe 1500C | 19:07 |
azonenberg_work | Conveniently 1200ish is all you need for semiconductor fab | 19:07 |
berndj | you'd need 1500C for steel | 19:07 |
azonenberg_work | Once you have the wafers, that is | 19:07 |
azonenberg_work | CZ process would need more | 19:08 |
berndj | do you actually have to *melt* silicon to grow crystals? or can you do it like with metals, and let the crystals grow in solid phase | 19:08 |
bart416 | berndj, to get high quality you need to go higher temperature than just melting | 19:09 |
azonenberg_work | berndj: for large crystals you need full melt | 19:09 |
azonenberg_work | even for float zone | 19:09 |
berndj | oh, but reflective optics is both UV-compatible and post-apocalypse-accessible | 19:09 |
bart416 | + higher temperature allows you to get the impurities out of the material easier | 19:09 |
berndj | higher temperature almost always means faster | 19:10 |
bart416 | + a blast furnace is easy to make anyway | 19:11 |
bart416 | And fairly easy to operate | 19:11 |
bart416 | It's pretty much fool proof | 19:11 |
berndj | uhm, "blast furnace" has a specific technical meaning i don't think you mean to imply? | 19:11 |
berndj | a *blast* furnace is pretty far along in tech, afaict | 19:11 |
berndj | but if you mean just reaching the temperatures accessible in those, then yes | 19:12 |
bart416 | You are thinking too high tech | 19:13 |
bart416 | The early blast furnaces were easy in construction | 19:13 |
bart416 | And use | 19:13 |
berndj | but you don't need the "blast" part to melt sand anyway | 19:15 |
bart416 | Good luck melting sand with just coal | 19:15 |
bart416 | It sounds easy | 19:16 |
berndj | oh, sorry, you're right; i was thinking of the bessemer process | 19:16 |
bart416 | Actually doing it is different :P | 19:16 |
bart416 | blast furnaces have been around for over two millenia :P | 19:17 |
bart416 | But with the extra oxygen flow you can get a serious amount of heat out of the coal easily | 19:18 |
mrdata | coal is good, that way | 19:18 |
bart416 | Is anything in that GVCS thing actually finished lol? | 19:21 |
berndj | some prototypes | 19:22 |
berndj | but there's a whoooole lot to do in not much time at all | 19:22 |
bart416 | If they'd be smart they'd throw a contest for engineering students | 19:23 |
bart416 | That would get a lot of designs done | 19:23 |
bart416 | Additionally I see a serious issue with their list | 19:25 |
bart416 | They don't have a metal extruder... | 19:26 |
bart416 | Good luck making pipes without that :P | 19:26 |
berndj | bent and welded | 19:26 |
bart416 | That's impossible for many shapes | 19:26 |
bart416 | And gives horrible properties from a fluid dynamic point | 19:27 |
berndj | hmm, maybe, but maybe round pipes are all the "pipe" the GVCS need? | 19:27 |
berndj | fluid dynamics? what do you mean? | 19:27 |
bart416 | Weld joins created turbulence | 19:27 |
bart416 | *create | 19:28 |
berndj | i doubt the GVCS needs hydraulics where such turbulence is an issue? | 19:28 |
berndj | also, don't weld like crap then :-P | 19:28 |
bart416 | Not to mention weld joins are horrible at containing pressure | 19:28 |
berndj | yeah, there's that | 19:28 |
berndj | and are hard to make gas-tight | 19:28 |
bart416 | Useless for high pressure hydraulics | 19:29 |
berndj | which they *are* using | 19:29 |
azonenberg_work | bart416: well done TiG welds are good with negative pressure | 19:29 |
bart416 | azonenberg, there you mention something important | 19:29 |
azonenberg_work | in terms of vacuum gear etc | 19:29 |
bart416 | WEll done :P | 19:29 |
azonenberg_work | But these are, like, really well done ones | 19:29 |
azonenberg_work | i am not that good, or even close | 19:29 |
bart416 | + negative pressure is quite different | 19:29 |
bart416 | that'll try to compress the joint | 19:30 |
azonenberg_work | in fact i dont even know TiG lol | 19:30 |
bart416 | positive pressure will try to pull it appart | 19:30 |
berndj | azonenberg_work, auto-darkening filters really do make a big difference eh | 19:30 |
azonenberg_work | MiG is on the get-good-at list first | 19:30 |
azonenberg_work | berndj: yeah | 19:30 |
azonenberg_work | going down to the shop to practice again tonight after office hours, actually | 19:30 |
bart416 | azonenberg, if you're ever in the area I think I need to teach you how to weld properly :P | 19:30 |
berndj | i tried mine the other day | 19:30 |
berndj | by comparison, the fixed-shade helmet is like working blind | 19:30 |
azonenberg_work | bart416: define"the area" :p | 19:31 |
bart416 | Belgium lol | 19:31 |
azonenberg_work | berndj: agreed, i used a fixed shade 10 (i think) in the engineering processes class when i first took it | 19:31 |
azonenberg_work | bart416: no plans to be in europe any time soon | 19:31 |
azonenberg_work | berndj: and yeahm being totally unable to see until you strike the arc? Not my idea of a good working environment | 19:32 |
bart416 | could be worse :P | 19:33 |
azonenberg_work | bart416: have you ever tried welding with a fixed shade helmet? :p | 19:34 |
bart416 | nope | 19:34 |
azonenberg_work | Good | 19:34 |
azonenberg_work | Keep it that way :p | 19:34 |
azonenberg_work | They'll protect you but are useless for actually getting work done | 19:34 |
bart416 | I have welded in a fire proximity suit though | 19:34 |
bart416 | lol | 19:34 |
azonenberg_work | lol | 19:34 |
bart416 | The metalised foil makes is less than interesting lol | 19:35 |
azonenberg_work | so... you were welding in extreme ambient heat? | 19:35 |
bart416 | yes | 19:35 |
azonenberg_work | like inside a furnace or something? | 19:35 |
bart416 | Close to one | 19:35 |
azonenberg_work | oh fun | 19:36 |
azonenberg_work | Arc, i assume? | 19:36 |
bart416 | Yes | 19:36 |
bart416 | Acetylene is too dangerous in high temperature environments | 19:36 |
azonenberg_work | i woudl not want to bring acetylene anywhere near an environemnt that needed a fire suit | 19:36 |
azonenberg_work | lol | 19:36 |
bart416 | If you're standing 3m from molten metals you need one no matter what >_> | 19:37 |
azonenberg_work | lol | 19:37 |
azonenberg_work | True that | 19:37 |
bart416 | somebody forgot to weld rings onto the metal we had to use so we couldn't lift it into the furnace with the crane | 19:37 |
azonenberg_work | wait a minute, you were welding lifting attachments onto the furnace charge? | 19:38 |
azonenberg_work | a few meters from a vat of molten metal? | 19:38 |
bart416 | Yes | 19:38 |
azonenberg_work | Oh | 19:38 |
azonenberg_work | That would explain it | 19:38 |
azonenberg_work | Any issues with shielding gas? | 19:38 |
bart416 | No | 19:38 |
azonenberg_work | interms of overpressure, spatter damaging the hoses, etc | 19:38 |
bart416 | You can't make the nicest of welds in such environment no | 19:39 |
bart416 | But it just has to hold | 19:39 |
azonenberg_work | What i meant was, the equipment being damaged by ehe environment | 19:39 |
bart416 | No, it are only small spats of metal | 19:40 |
azonenberg_work | Ok, so it wasnt like 800C ambient temp | 19:40 |
azonenberg_work | in air | 19:40 |
berndj | lol | 19:40 |
azonenberg_work | or something crazy like that | 19:40 |
berndj | that would be insane | 19:40 |
bart416 | 800°C? | 19:40 |
bart416 | Are you nuts | 19:40 |
azonenberg_work | sorry, i meant 800F | 19:40 |
azonenberg_work | which is like 300C | 19:40 |
berndj | i think even that is nuts, no? | 19:41 |
bart416 | I wouldn't dare to enter 300°C ambient air, even with a fire proximity suit :| | 19:41 |
azonenberg_work | They have proximity suits, but then they have entry suits | 19:41 |
azonenberg_work | which are designed for walking through flames for rescue ops etc | 19:41 |
bart416 | Advised use was up to 85°C | 19:41 |
bart416 | 100°C for 5 minutes | 19:41 |
berndj | with a pack of ice in your backpack? | 19:42 |
azonenberg_work | berndj: the entry suits are designed for very brief exposure | 19:42 |
azonenberg_work | to extremely high temp | 19:42 |
berndj | no doubt! | 19:42 |
azonenberg_work | i think they can handle 1000F+ for a minute or so | 19:42 |
bart416 | berndj, the heat can't really go through the clothing | 19:42 |
bart416 | Your own body becomes a problem though | 19:42 |
bart416 | + it's fairly heavy clothing | 19:43 |
berndj | oh ok | 19:43 |
bart416 | Can't imagine what a 1000F+ one must weigh | 19:43 |
azonenberg_work | bart416: those are not meant for extended wear lol | 19:44 |
berndj | so you stay just as long as it takes for your body to heat your mini environment over what's tolerable | 19:44 |
bart416 | In the environment of a furnace it's tolerable for several hours actually | 19:44 |
bart416 | But you need to drink a lot | 19:45 |
bart416 | And be in a somewhat good physical condition | 19:45 |
berndj | oh really? wow | 19:45 |
azonenberg_work | bart416: you mean near a furnace | 19:45 |
azonenberg_work | not inside one | 19:45 |
bart416 | yeah | 19:45 |
bart416 | Inside, are you nuts? | 19:45 |
berndj | i suppose the fluid intake is a significant heat sink | 19:45 |
azonenberg_work | I think the entry suits are rated for entry for shorttimes | 19:45 |
bart416 | I doubt even with fire entry suits that you'd survive that | 19:45 |
azonenberg_work | let me look one up | 19:45 |
azonenberg_work | we're not talking immersion | 19:46 |
azonenberg_work | in molten metal | 19:46 |
azonenberg_work | this is for large ovens etc | 19:46 |
berndj | immersion in molten metal like the terminator! | 19:46 |
bart416 | azonenberg, ambient temperature in a furnace to melt iron is fairly high though... | 19:47 |
azonenberg_work | bart416: i'm not talking thati | 19:48 |
azonenberg_work | i'm talking like i said 1000C ish | 19:48 |
azonenberg_work | 1000F* | 19:48 |
azonenberg_work | gtg. class is out - back in a few | 19:48 |
azonenberg_work | bart416: http://www.newtex.com/extremeprotective/protective_suits/fire_entry_suits/ | 20:01 |
azonenberg_work | 3000 series is rated to 1650C | 20:02 |
azonenberg_work | / 3000F | 20:02 |
azonenberg_work | for short duration | 20:02 |
azonenberg_work | radiant heat | 20:02 |
azonenberg_work | and ambient temperature of up to 1500F / 815C | 20:03 |
bart416 | What's short duration? | 20:03 |
berndj | cripes! 1650C! | 20:13 |
berndj | radiant heat != ambient | 20:15 |
berndj | it's a bit fuzzy what "radiant heat" is supposed to mean when they use the term | 20:16 |
bart416 | Not really | 20:20 |
bart416 | Black body temperature ;) | 20:21 |
berndj | well, how big is the radiator? | 20:27 |
berndj | i'm wearing nothing special, and my clothes can withstand 3000C radiant heat easy peasy! just switch on a light bulb and see for yourself! | 20:27 |
bart416 | yeah, now try that without a vacuum and a few kg of molten metal ;) | 20:33 |
azonenberg_work | bart416: in any case its rated to 1500F ambient | 20:48 |
azonenberg_work | Which is pretty signiicant | 20:48 |
azonenberg_work | significant* | 20:48 |
bart416 | True | 21:06 |
bart416 | I just wish it'd be acceptable to wear scrubs in public :( | 21:06 |
azonenberg_work | lol who says it isnt? | 21:10 |
bart416 | I used to wear them when I was on my way home and people look weird at you on the bus and train heh | 21:10 |
bart416 | We all agreed they were far more comfortable than our regular clothes that we wore when we arrived at work | 21:11 |
bart416 | But loads of people put on their regular clothes again lol | 21:11 |
bart416 | Even if they weren't contaminated | 21:11 |
bart416 | Simply to avoid weird faces | 21:11 |
azonenberg_work | lol | 21:11 |
Action: bart416 stopped caring after a while though | 21:16 | |
bart416 | + it's not as bad as my girlfriend at the time | 21:17 |
bart416 | She once wore a lab coat on the bus lol | 21:17 |
bart416 | cause she spilled something nasty over her tshirt | 21:17 |
azonenberg_work | lol | 21:25 |
azonenberg_work | shouldnt you be spiling nasty stuff on the lab coat? | 21:25 |
azonenberg_work | and not your street clothes? | 21:25 |
bart416 | azonenberg, insane korean girl... | 21:39 |
bart416 | I don't think she ever did anything normal | 21:40 |
bart416 | That includes liking me | 21:40 |
azonenberg_work | lol | 21:52 |
bart416 | If it wasn't for the fact that she moved I think I'd still be together with her at this point heh | 21:54 |
bart416 | It's a small wonder we never got arrested heh | 21:55 |
bart416 | azonenberg_work, I like blowing up things as much as the next guy... | 22:01 |
bart416 | But she... | 22:01 |
bart416 | In the US she'd probably be on every single terrorist watch list by now lol | 22:01 |
azonenberg | Lol | 22:46 |
azonenberg | How do you know she isn't still? :p | 22:52 |
bart416 | Cause she lives in South Korea? | 22:55 |
azonenberg | But how do you know she isnt on their watchlists? :P | 22:55 |
bart416 | She's too cute for that | 22:56 |
azonenberg | Too cute to be on watchlists? Lol | 22:56 |
azonenberg | Knowing some of the cops here that'd put you higher on the list :p | 22:56 |
bart416 | lol | 22:57 |
bart416 | But seriously, she was the best thing that ever happened to me; and her having to leave was the worst | 22:57 |
azonenberg | Yeah... i know what you mean | 22:58 |
azonenberg | The one person i met at school that i was starting to like transferred out like a month or two after we met :p | 22:59 |
azonenberg | we saw each other irl... twice? in total | 22:59 |
bart416 | Heh, I knew her since birth though | 22:59 |
bart416 | We grew up together lol | 22:59 |
azonenberg | oh, that would make it worse | 23:00 |
bart416 | And always had a thing for each other | 23:00 |
bart416 | We were 5 years old and they already said "that's going to become a couple later on" | 23:00 |
bart416 | lol | 23:00 |
azonenberg | lol | 23:00 |
bart416 | Two over achievers that know each other from young age = not the safest thing | 23:02 |
azonenberg | oh boy | 23:02 |
azonenberg | lol | 23:02 |
--- Fri Sep 23 2011 | 00:00 |
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