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<wolfspraul> wpwrak: thanks again for taking the time to go through the pcb process yesterday!
<wolfspraul> made me happy, I am thinking about buying things now and experimenting :-)
<wpwrak> was a pleasure :) and you'll have fun, too ;-)
<wolfspraul> I start easy with some of the smaller utentils, and then I go to an electronics market with xiangfu for some of the more elaborate things, especially also to talk with guys and see what they think and/or use
<wolfspraul> I will drag xiangfu into this right away as well
<wpwrak> elaborate things = scope, ultrasonic cleaner, ... ?
<wpwrak> and let's not forget the CNC :)
<wolfspraul> yah, basically. also chatting with the guys there
<wolfspraul> laser printers cost as little as 80 USD now, amazing
<wpwrak> wow
<wolfspraul> yeah
<wolfspraul> I was wondering whether one could directly print onto the pcb?
<wpwrak> there have been attempts. with ink, though.
<wolfspraul> how about other printers?
<wolfspraul> ah ok, but you think the toner transfer is a good standard still, well known to work...
<wpwrak> there are basically three approaches:
<wolfspraul> but maybe a laser printer is so flat that it can pull a 0.8mm (or thinner) pcb right through it? :-)
<wolfspraul> well I can imagine that there are potentially infinite ways how to get this printed
<wpwrak> 1) lithography, with UV light and photo-coated PCBs. popular but a bit messy. never tried that. that's probably still what industry uses.
<wpwrak> 2) toner transfer. less capable but reasonably straightforward.
<wpwrak> 3) milling of the non-copper areas
<wolfspraul> so you apply the etch resist (positive or negative), then uv light to remove parts, then etch?
<wolfspraul> yeah I'll just go with the toner transfer first
<wolfspraul> feels right and uses only cheap tools and simple chemicals and steps
<wolfspraul> except for your stepper-motor laminator, which I hope to bypass
<wpwrak> 3) should be cool, because you avoid the chemistry and it's just one step. drawbacks: the finer your traces, the easier your mills break. and you need very precise depth control. i experimented a bit with this but eventually gave up. never succeeded in making a board that actually looked right.
<wolfspraul> nah I don't feel good about 3
<wolfspraul> lithography or lasering, chemicals - that sounds better
<wpwrak> (photo process) you make a transparent mask, then expose with UV, then develop (chemically), then remove the developed/undeveloped part (not sure if you need special chemicals for that), then etch, then remove all the photoresist (chemically)
<wpwrak> a heck of a pipeline
<wolfspraul> maybe you can print the mask with a regular printer just like for those overhead projectors
<wolfspraul> would need someone who still has a simple lab for analog photo development
<wpwrak> and it also complicates the handling of the PCB material, since there's the photosensitive coating to worry about
<wpwrak> you don't need the entire lab. just a few bits of it.
<wpwrak> but still seems messy to me :)
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<kristianpaul> 80usd !!
<kristianpaul> wow
<kristianpaul> toner transfer, indeed is nice, but is not one step solution, so more probably to make mistakes
<kristianpaul> at least thats my experience
<kristianpaul> tought laser printing tech had improve a lot, now i should try again :)
<kristianpaul> 3) is messy, even more mechanical posibillities to get a failure...
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<wolfspraul> you tried toner transfer before?
<wolfspraul> but it seems you have no idea for a better process?
<kristianpaul> yes i did when in the University
<kristianpaul> to be honest i tried no more than 5 times, then decide outsource :)
<kristianpaul> no idea for better indeed
<kristianpaul> when i tried laser printed was new.. all was most ink so...
<kristianpaul> resolution wasnt the best
<kristianpaul> also i dint knew about the mix of chemicals werner pointed, thats is a cleaner solution
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<wolfspraul> wpwrak: so maybe on my initial purchase, 100ml h2o2 and 100ml hcl is enough?
<wolfspraul> or more?
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<wpwrak> 100 ml of each should be sufficient for several boards. but you may not be able to buy in such small quantities. especially not the HCl.
<wpwrak> there, they typical minimum quantity would be more like 0.5-1 l
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<wpwrak> 1 l in easy.com.ar :) peroxide i can get in bottles of 0.1 l - 0.5 l at a pharmacy
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<wpwrak> and don't be shocked by the prices. all that stuff is cheap.
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<wolfspraul> hah yes, went as expected. I got hcl and h202, but at unknown concentrations :-)
<wolfspraul> when pressed, they would try to come up with the number they thought you would like to hear
<wolfspraul> labeling of the bottles is chaotic, multiple labels, hand-written, refilled etc. etc. fun.
<wolfspraul> I was upgraded from "wild blob of duct tape" to a proper rubber knob closure of the bottles only after complaining :-)
<wolfspraul> so who knows, I will find out the concentration "in the field", china style
<wolfspraul> the hcl is of some greenish color, and the seller told me I shouldn't spill it over my hands. that's a good sign, must be the right stuff...
<wolfspraul> maybe there is a standardized and easy test which would let me guess the concentration of the hcl and h2o2? I think I will just try etching instead, see whether anything happens.
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<pabs3> green hcl? /me guesses it is contaminated, maybe with copper
<whitequark> wolfspra1l: that's some really bad customer service
<whitequark> when I bought chemicals on a market here in Moscow, behind the counter there were two nice girls _and_ they knew more about pcbs than I do now
<whitequark> not to say that bottles etc. were of uncomparable quality. strange. I thought it should be good in China as it's an industrial center and whatnot, no?
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<whitequark> pabs3: or complex ions of Fe, they're green in some cases too
<whitequark> copper is mostly blue as I've seen it...
<mth> outdoor bronze turns green, isn't that oxidized copper?
<mth> wikipedia says it's a carbonate instead: http://en.wikipedia.org/wiki/Patina#Acquired_patina
<mth> and other non-oxide molecules
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<whitequark> yeah, Copper(I) oxide is red: https://en.wikipedia.org/wiki/Copper(I)_oxide
<whitequark> and Copper(II) oxide is, erm
<whitequark> it's kinda bluish
<whitequark> as you can see, sulphate is blue: https://en.wikipedia.org/wiki/Copper_sulphate
<whitequark> so will be any other dissolved compound when copper ions are only coordinated by water molecules
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<LunaVorax> Hello everyone!
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<kristianpaul> hi
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<qi-bot> [commit] Adam Wang: js28f256j3f105.lib: pin 43, pin name changed to VCCQ (master) http://qi-hw.com/p/kicad-libs/bbab963
<qi-bot> [commit] Adam Wang: Merge branch 'master' of projects.qi-hardware.com:kicad-libs (master) http://qi-hw.com/p/kicad-libs/4be16e3
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<wpwrak> wolfspraul: green is a bit unusual. should be more like colorless or perhaps a little yellowish. but maybe it's an additive. that sometimes happens. is it still transparent enough to see through a cm of it ?
<wolfspraul> yes definitely
<wolfspraul> concentration no idea
<wolfspraul> and for the h2o2 I'm not even sure whether it is h2o2 :-)
<wolfspraul> the pharmacy had a more trustworthy h2o2, but concentration was listed at 2.5%-3.5% only
<wpwrak> you can try this: cut a bit off a PCB. make you mixture. WEAR GLOVES AND GOGGLES. set up the stuff outside, somewhere where spills don't harm. even if it would decide to boil.
<wolfspraul> is there an easy way to reduce h2o2 to increase the concentration?
<wpwrak> weark clothes you don't mind discarding. if you have some plastic poncho, raincoat, or such, wear that too.
<wpwrak> then toss the copper inside and see what happens.
<wpwrak> (reduce concentration) yes, add water :)
<wolfspraul> need to increase the concentration
<wpwrak> oh, increase
<wpwrak> naw, not really
<wolfspraul> the h2o2 at the pharmacy is only 2.5%-3.5%
<wpwrak> that's probably good enough. lemme check what the one i have is ...
<wolfspraul> yes I will just try, the main protection being that I will try with small amounts
<wolfspraul> come on everybody here uses this stuff all over, I won't make myself too laughable :-)
<wpwrak> hmm. bottle says "10 volumenes". 10 % ? let's find out what the google scienctists has to say about it ...
<wpwrak> with the peroxide concentration known to be low, you're already on much safer ground. when you wrote that it's all weird, i thought, the peroxide was unknown too
<wolfspraul> it is, I got the one in the market, not the pharmacy
<wolfspraul> could be anything :-)
<wolfspraul> I will get the one from the pharmacy too, good idea
<wpwrak> (if you mix, say, 35% HCl with 30% H2Os, you get a VERY reaction-happy acid. etches a board clean in just a few seconds. alas, it also starts boiling quickly ...)
<wpwrak> s/H2Os/H2O2
<qi-bot> wpwrak meant: "(if you mix, say, 35% HCl with 30% H2O2, you get a VERY reaction-happy acid. etches a board clean in just a few seconds. alas, it also starts boiling quickly ...)"
* wpwrak is still in pre-caffeine state
<wolfspraul> sure but most likely the stuff I buy here errs on the side of water
<wolfspraul> not on the other side
<wolfspraul> I will try a little :-)
<wolfspraul> there's no way I can get high-reliability chemicals anyway here
<wpwrak> good :) so the chinese are not all _that_ keen on massively negative population growth ;-)
<wpwrak> since we don't know for sure what the acid is, you should follow the usual precautions: give peroxide into the basin first, then add the acid. that way, the risk of splashes with high concentration is lower
<wolfspraul> good
<wpwrak> you should still wear gloves and glasses/goggles, though
<wpwrak> (peroxide) "10 volumenes" = 3%. so yours is perfect.
<wolfspraul> ah ok
<wpwrak> so only the HCl is unknown. during etching, a bit of Cl gas should escape. it has a very characteristic smell. so that shuold allow you to tell tht there's indeed Cl in there
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<wpwrak> so, first experiment: make a bit of acid and toss a piece of copper-clad PCB inside. 1 cm^2 will do nicely
<wpwrak> then watch what happens. move it around a bit with a stick made of plastic, wood, or glass
<wolfspraul> sure, I remember from my visit :-)
<wpwrak> if it's double-sided, you can also turn it over, move it for a while "bottom up", then flip, etc.
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<wpwrak> you should see that both sides etch at different speeds. that's probably because of differences in the flow of the acid in the basin. i find that usually the bottom side etches faster.
<wpwrak> the chemical reaction should produce 1) little gas bubbles on the copper. 2) bluish/greenish traces that come off the board. the blue are your copper ions. the green is them with chloride.
<wpwrak> pity that your HCl already has that color. but you may still see some changes. eventually, the whole solution turns green-blueish, even if you start with "clean" HCl.
<wpwrak> complete removal of all the copper should take between 10-20 minutes.
<wpwrak> ah, maybe give your pcb a scrub with steel wool first. not sure how much the acid likes the copper oxide. might slow it down.
<wpwrak> (steel wool and then clean with alcohol. wouldn't want to add iron to the reaction.)
<wolfspraul> good good
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<qi-bot> [commit] Maarten ter Huurne: MIPS: JZ4740: SLCD: Fixed sysfs tvout value parsing. (jz-3.3) http://qi-hw.com/p/qi-kernel/f20d896
<qi-bot> [commit] Maarten ter Huurne: MIPS: JZ4740: SLCD: Ignore sysfs rewrite of current TV-out mode (jz-3.3) http://qi-hw.com/p/qi-kernel/0a96d72
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<canoso> have anyone used gnublin embedded GNU/Linux?
<GNUtoo-desktop> canoso, what's that?
<canoso> it is a embedded linux board with an ARM microcontroller.
<canoso> It is open hardware
<GNUtoo-desktop> is it 100% free software?
<GNUtoo-desktop> seem so at first sight
<GNUtoo-desktop> btw how much does it cost?
<canoso> about 50 euros
<GNUtoo-desktop> ok
<lindi-> wrong language :(
<GNUtoo-desktop> ?
<lindi-> (german)
<GNUtoo-desktop> ah ok
<canoso> it has USB On the Go. Can I connect any usb device to it?
<lindi-> canoso: I wouldn't call that a microcontroller
<lindi-> since linux doesn't run on microcontrollers :)
<GNUtoo-desktop> depends
<GNUtoo-desktop> linux runs on blackfin for instance
<GNUtoo-desktop> or stuff without mmu
<GNUtoo-desktop> but in that case it's a SOC
<lindi-> and it has 8 MB of RAM
<GNUtoo-desktop> yes
<GNUtoo-desktop> I think the minimum specs is 4M
<canoso> lindi-: it is a microcontroller
<canoso> lindi-: it has many peripherals integrated in the same chip
<canoso> lindi-: and RAM in the chip
<lindi-> openmoko has ram in the chip too
<lindi-> (half of it)
<lindi-> canoso: I guess we just have different terminology :)
<GNUtoo-desktop> microcontroller and SOC are not that different
<lindi-> for me microcontroller is something without MMU certainly and without cache too
<GNUtoo-desktop> linux run on some stuff without MMU
<lindi-> yeah but that's quite an exception
<kristianpaul> milkymist soc dont have mmu btw :-)
<GNUtoo-desktop> lindi-, an exception that is in mainline?
<lindi-> GNUtoo-desktop: yeah :)
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<wolfspraul> canoso: [gnublin] nice link, thanks a lot!
<wolfspraul> first time I see this, and please always feel free to post links to new or potentially new open hardware anything here
<wolfspraul> we love to learn
<wolfspraul> :-)
<wolfspraul> I haven't checked about license, tools, etc. but anyway, nice simple project.
<GNUtoo-desktop> yes indeed seem nice
<wpwrak> lindi-: linux runs fine on microcontrollers. here's an example: http://www.bit-tech.net/news/hardware/2012/03/30/linux-atmel-microcontrollers/1
<canoso> wolfspraul: ty
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