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