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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?
<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.)