berndj | i thought pretty much any electrical copper is pretty darn pure, because its conductivity is so super sensitive to impurities | 00:10 |
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azonenberg | Yeah, same here | 00:12 |
azonenberg | I did my last evaporation run with wire i cut out of a random AC power cord lol | 00:12 |
azonenberg | that i found on the loading dock in a dumpster :P | 00:12 |
berndj | although i guess sometimes you get beryllium | 00:14 |
berndj | wow, they have copper in dumptrucks where you live?? | 00:14 |
azonenberg | no lol | 00:14 |
azonenberg | this is the loading dock behind the matsci building | 00:14 |
azonenberg | they have a giant e-waste bin there | 00:14 |
azonenberg | full of scrap for the taking if you get there before the collection day | 00:14 |
berndj | ah, nice. | 00:14 |
azonenberg | Quote of the day - apparently a character in some TV show once said "it's impossible to do microelectronics with gloves on" | 01:47 |
azonenberg | And of course anyone who's actually spent time with them knows it's impossible to NOT do it with gloves on :P | 01:48 |
azonenberg | At least not if you expect the device to work by the time you're done with it | 01:48 |
CIA-67 | homecmos r110 | trunk/lithography-tests/ (34 files in 18 dirs) | Pushing latest changes to 600dpi test pattern database | 06:26 |
Last message repeated 1 time(s). | 06:35 | |
smeding | azonenberg: haha, have those writers ever seen a clean room | 12:40 |
azonenberg | smeding: no idea lol | 12:40 |
azonenberg | They were admittedly talking about PCB assembly rather than IC fab, i think | 12:41 |
azonenberg | But still - i often wear gloves for that | 12:41 |
smeding | nothing micro about that | 12:41 |
azonenberg | fingerprints on copper can mess p solder joints | 12:41 |
azonenberg | up* | 12:41 |
azonenberg | And agreed | 12:41 |
smeding | i don't, but i tend to build fairly simple low-speed digital circuits on protoboard :p | 12:42 |
azonenberg | Yeah, those are less criticial | 12:42 |
smeding | i was going to try my hand at etching PCBs this week but the people at revspace took all the etching equipment to CCC :( | 12:42 |
azonenberg | currently working on final design review for my latest project - 32 channel FPGA based PWM controller | 12:42 |
smeding | nice | 12:42 |
azonenberg | As you can probably guess this board is not being homebrewed | 12:42 |
smeding | yeah... anything with vias gets annoying | 12:43 |
azonenberg | I tried them - they're OK as long as they're out in the open | 12:43 |
azonenberg | But most of my boards use the majority of vias under ICs :P | 12:43 |
azonenberg | And when you have thirty vias under a single TQFP, well... | 12:43 |
smeding | heh | 12:43 |
smeding | yeah... i'm running into issues designing a board with an 8DIP and a 20DIP :p | 12:44 |
azonenberg | If nothing else, the via plating process i've used (or tried to, anyhow) is too tall to fit under SMT ics | 12:44 |
azonenberg | they have bumps on top | 12:44 |
smeding | what plating process did you use? did it require any tooling? | 12:44 |
azonenberg | Tried several simple ones | 12:44 |
smeding | i wish there was money for a proper PCB manufacturing line at revspace, but alas | 12:45 |
azonenberg | conductive paint (didnt work), wire + solder (worked but left a bump and some of them didnt work) | 12:45 |
azonenberg | Ended up sending the board out for professional fab | 12:45 |
azonenberg | I still do single-layer ones in house for simple breakouts etc | 12:45 |
azonenberg | but i've come to the conclusion it isnt worth it for complex designs | 12:45 |
smeding | wire+solder is what we've been doing... but plated through-holes won't work with that, and it's something i would like to have | 12:45 |
azonenberg | until i get via plating working | 12:45 |
azonenberg | Yeah | 12:45 |
azonenberg | I want to try it some time, i have ideas | 12:46 |
azonenberg | Some crazy ones ;) | 12:46 |
azonenberg | for example - start out with a blank copper board | 12:46 |
azonenberg | Drill all of the holes | 12:46 |
smeding | but yeah, i want to etch like four small (maybe 10cm²) boards, it's not worth ordering a whole panel | 12:46 |
azonenberg | Sputter coat a thin layer of something conductive (probably wouldnt work though, i dont think fr4 is vacuum safe) | 12:46 |
azonenberg | then electroplate up | 12:47 |
azonenberg | and etch the wiring layer | 12:47 |
azonenberg | lol | 12:47 |
smeding | yeah... i don't think it is | 12:47 |
azonenberg | Which means i'd need to use a glass or ceramic substrate | 12:47 |
azonenberg | and then the costs start rising etc | 12:47 |
smeding | i think the commercial process uses some annoying chemicals to deposit copper, and then electroplates the rest on? | 12:47 |
azonenberg | They try to do additive as much as possible from what i understand | 12:47 |
azonenberg | because every gram of copper you etch is a gram of copper wasted | 12:48 |
azonenberg | so they start really thin, pattern that | 12:48 |
azonenberg | and then plate up | 12:48 |
smeding | sounds pretty sane | 12:48 |
azonenberg | Re vias... http://i.imgur.com/Quh56.png is the simplest of the two boards i'm currently working on | 12:48 |
azonenberg | The other one is the same size but has like six more ICs, four layers instead of two, and has some really tiny components like 0402s | 12:49 |
smeding | what do you use to design those? | 12:50 |
azonenberg | Expresspcb, but i'm moving away from it | 12:50 |
azonenberg | Even ignoring the fact that its not using an open file format, there are more serious issues | 12:50 |
azonenberg | Like the single-level undo | 12:50 |
smeding | i kind of want to use gEDA | 12:50 |
azonenberg | lack of an autorouter | 12:50 |
azonenberg | etc | 12:50 |
azonenberg | Yes, thats what i'm looking at too | 12:50 |
smeding | but it's prety bad | 12:50 |
azonenberg | Only reason i've stuck with express is that the fab is dirt cheap | 12:51 |
smeding | i'm thinking of rallying the people to fix it | 12:51 |
azonenberg | and beats every other one i've found | 12:51 |
smeding | don't they take gerber or something? | 12:51 |
azonenberg | in terms of being cost effective for a one-off design | 12:51 |
azonenberg | Nope | 12:51 |
azonenberg | Only thier format | 12:51 |
smeding | huh | 12:51 |
smeding | odd | 12:51 |
azonenberg | if they took gerber there would be no reason for people to use their proprietary cad tool :P | 12:51 |
azonenberg | Though i'm sure it gets turned into gerber internally | 12:51 |
smeding | well, yes, but they could probably get more sales | 12:51 |
azonenberg | I only use them for one-off designs that i know i will not need to mass produce | 12:52 |
azonenberg | Like a prototype that i already plan to completely redo | 12:52 |
azonenberg | so i'd do rev1 in expresspcb and then based on what i learn from that do rev 2 at a different fab with more layers etc | 12:52 |
smeding | so what are those boards for, anyway? | 12:53 |
azonenberg | This one is a 32-channel RC servo controller for a research group on campus | 12:53 |
azonenberg | designing a prototype robotic arm and couldnt find a MCU with enough outputs | 12:53 |
azonenberg | So they had me do an FPGA based design | 12:53 |
smeding | ah, yeah | 12:54 |
azonenberg | Even the 50k gate i'm using is probably overkill | 12:54 |
azonenberg | i fit six channels into a large CPLD | 12:54 |
smeding | yeah.. i wrote a PWM controller for a uni project | 12:54 |
azonenberg | but there's nothing in between the 3k gate CPLD it didnt fit in and the 50k fpga on this board | 12:54 |
smeding | they're not complicated | 12:54 |
azonenberg | i really need like a 15 or 20 | 12:54 |
azonenberg | And yeah, this is my first actual FPGA based design | 12:54 |
azonenberg | wanted to start simple | 12:54 |
smeding | well, for our project it was part of a little robot thing | 12:55 |
azonenberg | Was yours in software or hardware though? | 12:55 |
smeding | VHDL on an FPGA | 12:55 |
smeding | so hardware... at least sort of :p | 12:55 |
azonenberg | bitbanging in an arduino is a bit different than custom softcores | 12:55 |
azonenberg | and yeah, that counts as hardware in my book | 12:55 |
smeding | we didn't use a softcore | 12:55 |
smeding | it was a big, ugly FSM | 12:55 |
azonenberg | Lol | 12:55 |
azonenberg | I'd still consider that a softcore | 12:56 |
azonenberg | as opposed to a hard IP block in an ASIC | 12:56 |
smeding | well, several - they had us implement the PWM as an FSM for some daft reason | 12:56 |
azonenberg | Lol | 12:56 |
azonenberg | Doesnt make too much sense | 12:56 |
smeding | instead of like a single comparator | 12:56 |
smeding | well, counter and comparator | 12:56 |
azonenberg | Yeah | 12:57 |
azonenberg | Thats what i did in my design | 12:57 |
azonenberg | cant see any other sane way to do it for a 10-bit duty cycle | 12:57 |
azonenberg | not gonna do a 1024 step FSM | 12:57 |
smeding | well, the design was weird | 12:57 |
smeding | but they wanted it to do it that way... | 12:57 |
smeding | s/it/us/ | 12:57 |
azonenberg | Anyway so my other board is a slightly larger fpga (200k gate) and an embedded MIPS microcontroller | 12:58 |
smeding | thankfully they left us alone for most of the project | 12:58 |
azonenberg | intended for general purpose embedded development | 12:58 |
smeding | oh, yeah, the pic32 thing? | 12:58 |
azonenberg | the fpga has 3bpp (8 channel) vga out | 12:58 |
azonenberg | yeah | 12:58 |
smeding | with the ringosc :p | 12:58 |
azonenberg | Lol yep | 12:58 |
azonenberg | Coudlnt resist sticking some art on that one too | 12:58 |
smeding | art is good | 12:58 |
azonenberg | you can see the smiley face on this one | 12:58 |
smeding | yeah i noticed | 12:58 |
Action: smeding goes back to coding a little driver program for a hp7550a plotter from '84 | 13:00 | |
azonenberg | I stick that one on all of my boards unless i decide to do something more elaboate instead | 13:00 |
Action: azonenberg goes to take shower before work :P | 13:00 | |
azonenberg | sadly life isn't all fun and games lol | 13:00 |
smeding | plan on converting the plotter into a multifunctional thing for vinyl cutting / something with PCB development | 13:01 |
azonenberg | And the professor i work for has stuff she needs done before i finish up my summer research assistantship | 13:01 |
azonenberg | and start working on my PhD stuff | 13:01 |
smeding | plan on looking at drawing etch resist directly onto a PCB - if that doesn't work i'll try a photoplotter | 13:01 |
azonenberg | I want to make a photoplotter | 13:01 |
azonenberg | But my design was going to be small | 13:01 |
azonenberg | like, using steerable mirrors and a bluray laser with a 1cm^2 field or something | 13:02 |
azonenberg | the goal is to improve my in-house mask shop :) | 13:02 |
smeding | well, the 7550a is a very nice plotter - though it might be complicated to make it accept media sizes other than a3/a4 | 13:02 |
azonenberg | not familiar wit hthat particular model | 13:02 |
azonenberg | but like i said i want to make a photoplotter good to 20 microns or better lol | 13:03 |
smeding | yeah.. that might be a bit ambitious for this | 13:03 |
azonenberg | So it needs either minimal reduction (2-4x projection) or nothing (contact mask) | 13:03 |
azonenberg | rather than the 10x i'm doing now | 13:03 |
smeding | anyway, go shower, man | 13:03 |
azonenberg | i'm having issues with line edge roughness since i'm operating this printer so close to its limits | 13:03 |
smeding | :p | 13:03 |
azonenberg | even my 5-lambda design rule is pushing it for this printer | 13:04 |
--- Thu Aug 11 2011 | 00:00 |
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