Printing using black marker for etching Circuit boards

G'day,

Many people have proven that its possible for the Reprap's to draw using Black permanent markers (which happen to be etch-resistant too, although, there are also etch-resistant pens available). I'm thinking about exploiting this, to draw my own circuit boards. Then I simply need to drop them in a vat of acid to eat away the extra copper, and BOOM circuit boards for my second reprap (quite cheap to do too).

I haven't built my first reprap yet, but I'm just wondering if anyone has tried this approach yet for circuitry (and if it was successful).

More info at: [www.wikihow.com]

I've tried this technique before, and it's really difficult to get the precision you need for larger parts. I highly recommend starting with a laser printer toner transfer, and use the permanent marker to fix up any imperfections.

As for etchant, I use cupric chloride which turns the etched copper into more acid- nothing to dispose of, and you can make it at home from hydrochloric acid and scrap copper.

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Wooden Mendel
Teacup Firmware

Yep, I've also had really good results with laserprinter toner - and a cheap laserprinter is less than £50 (http://www.ebuyer.com/product/186126).

I've used some CD pens to tidy up the laser print transfer, but it depends on the pen which is best. laser toner is really resistant - the etchant 'beads up' and runs off.

Have a look at a couple of the boards i've etched
(renoirsrants)

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Reprapping blog and other rants: [renoirsrants.blogspot.com]
My Reprap: [sites.google.com]

G'day,

Certainly sounds like using toner is the better solution all round..

Thanks guys.

Not everybody has a BW laserprinter at home, so I think it is worth exploring if this method can be used as well.

... not only laserprinter-toner - i have some replacement bottles full of photocopier-toner from Sharp, sould work similar and maybe available for cheap ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Well actually, the reason I was thinking of black marker was as a dodgy hack to automate more of the process using the printer itself (especially as I don't have a laser printer, and PCB's look horrible when you draw them manually). But I guess finding one might be the better way then my idea.

Of course, I might just wait until Mendel can print electric circuits too (that would be ideal). Anyone know though if the plans are for Mendel to have the circuit printing or a newer generation? Trying to think about what I should do..

There is a kit that helps the laser print/copier approach work even better. They sell a transfer paper with a water soluble surface, so that 100% of the toner ends up on the copper. They also point out that the toner is not completely water proof, some acid gets through and starts to edge the traces. They sell something they call a foil, which only adheres to the toner that makes a water proof cover and improves the etching quality. They also sell a laminator that works better then using a household iron to transfer the toner onto the PC board. And for those who do not have a monochrome laser printer at home, you can still print out the patterns on an inkjet printer and then photocopy them onto the transfer paper. Much less expensive then buying a laser printer for just a few boards.

Mike

This makes me wonder if we could use toner directly applied to a board via a head on a Reprap. Toner for printers is essentially a very fine dust made of plastic. In a printer, it's laid on paper and then run through a heating mechanism which melts it and bonds it to the paper. I don't think it'd be unreasonable to lay toner down on a board, apply heat to bond it (either through the bottom via heated bed, or the top with an element that simply goes over the top...) and then follow the chemical etching process as normal.

I've never etched a board, am I missing anything?

sircaster,

you have the matter correct. Where I tend to think we should stick with the laser printer is two areas. The modern laser printers currently have about 600 dots per inch resolution and accuracy. That is about 1.6 mills per dot. The is right around the mechanical resolution of our reprap machines. If you only add toned where needed, it will be hard to get the powder to stay in such tight tollerances to heat the whole board from underneath. If we cover the whole board in powder, then user a focused laser or other spot heater, we will end up wasting all the rest of the powder laid out that is not used.

The second point is that it takes a long time for a reprap to cover the surface at 1.6 mill resolution or better, while a laser printer can do several pages per minute. This means this means that it will always be faster to use the laser printer.


On the other hand, I am advocating pretty much everywhere to look for ways to slightly tweak up the percentage of parts that are RP, and this is another possible route to do some of the work on the machine itself.

Mike

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Team Open Air
Blog Team Open Air
rocket scientists think LIGHTYEARS outside the box!

if we just clamp the board to your printer table and extrude directly onto the copper, given that we can find a heat profile that gives good bonding, our extruded plastic should make a lovely resist- no special heads necessary.

This does of course greatly limit the resolution of the boards, but it would be a neat feature to play with

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Wooden Mendel
Teacup Firmware

EDIT: Ignore bottom of post. Late at night, missunderstoud Triffid's post.

Yes, using a layer of ABS instead of toner to print directly onto the copper should work fine. It will be more water (acid) proof than the toner, but as you pointed out, probably not a finely detailed. The main advantage is it does part of the job on a reprap without requiring a special head. But if a reprap had a milling head, it would likely make better PC boards with finer traces, _and_ not require the outside process of acid etching. Currently not an option, certainly something to shoot for.

Mike



?Triffid,
? one minor problem with that. No matter how long you search for a laser printer ?with that straight a feed path, that can handle that wide a stiff a 'paper', you ?still cannot change the fact that the toner particles are positioned on the ?toner drum with static electricity, and copper is a very good conductor. Before ?the copper got close enough to press the toner particles onto the copper, the ?static charges would bleed off and there would be toner everywhere.

? Unfortunately, you still need to transfer the toner onto another insulator ?first and fuse it, before you can put it on copper or any other conductor.

?Mike

Edited 1 time(s). Last edit at 03/05/2010 11:21AM by rocket_scientist.

@rocket_scentist
I think Triffid_Hunters idea doesn't involve a laser printer at all, merely using the Mendel "as is" to extrude directly onto the copper layer, if the ABS or PLA will stick to copper, it might just be a matter of cleaning up some traces with a pen-knife.

Another idea might be to sprinkle toner, maybe using a brush, and the heating with a laser from a CD-ROM/DVD drive.

What about printing using metal exclusively.. I was thinking of using a low melting point metal such as Field's metal (and then realised thats exactly what [hackaday.com] was doing). But it looks like they are making channels in plastic to do it.

Not a professional on the topic, but I assume they are doing it that way because the metals don't bond very well to plastic. However, has anyone thought about printing a small layer of something such as Rosin where the tracks should be (not sure though if it bonds to plastic/silicon well), and then printing the metal layer on top (I assume that Mendel has the precision to do this). Or just use a substance that allows metal and silicon to stick? I'm not an Chemistry professional (or electrical), so just thinking..

Edited 1 time(s). Last edit at 03/05/2010 02:01AM by andrewluecke.

By the way, I'm just thinking about loud.. Still haven't even ordered the parts for my Mendel Kit yet (because I want to spend my money on a 3D printer that can print PCB's). Maybe I'm oversimplifying it though..

Quote
andrewluecke
I'm not an Chemistry professional (or electrical), so just thinking..

I don't want to sidestep this thread, but IMO: "a blind chicken sometimes will find a corn", that's what Open development is all about, brainstorming is all about getting ideas out there, no matter how crazy, and then hope that others can improve on the ideas, or maybe use the ideas as the basis of yet another idea. Don't let lack of knowledge hold your creativity back.

... 3D-MID uses plastics with metallic particles, what's normaly nonconducting, but when heating with a laser the plastic in the spot carbonises ans some of the metallic particles are laid free, so you can grow stable metallic trays and pads with galvanics on the lasercured areas ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Anton,
Thanks for the reassurance! In the week since I have joined, I have been fire-hosing the forums with ideas, none of which I have the time or equipment to test yet. I am collecting materials for a McWire, and have most of the non-RP parts for a Mendel to follow, but until the team I am mentoring finish their FIRST Robotics Challenge Regional Competition, there will be no time for reprap building. I am glad to know that throwing out dozens of ideas to get discussions started (and maybe points towards the Gada Prize) is not offending others.


Mike



anton Wrote:
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> I don't want to sidestep this thread, but IMO: "a
> blind chicken sometimes will find a corn", that's
> what Open development is all about, brainstorming
> is all about getting ideas out there, no matter
> how crazy, and then hope that others can improve
> on the ideas, or maybe use the ideas as the basis
> of yet another idea. Don't let lack of knowledge
> hold your creativity back.

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Team Open Air
Blog Team Open Air
rocket scientists think LIGHTYEARS outside the box!

Actually, I've thought of another alternative. This one seems like it might work REALLY well.

Who said tracks need to be composed of metals? It looks like conductive plastic exists:
[www.inventables.com]
[www.chomerics.com]
[www.boedeker.com]

Apparently its plastic with carbon mixed, which allows it to be conductive (the amount of nanoparticles affects its conductivity).. We should be able to print using it too I'd imagine, without serious modifications.


This way we could print the entire circuit boards using 2 different plastic compounds. Technically it would permit tracks to follow a 3D pattern, and be totally embedded within the plastic too (in fact, it would be part of the plastic so add to the strength). Most of the the tracks wouldn't have to be exposed, (only the connections to the components). We could maybe even print connectors to connect wires to and such without needing to later solder them onto the board.


Anyone tried this and knows its feasibility? My dad gave me the idea when he was discussing semi-conductors.

... i used silver-filled Polyimide for bonding wires and drawing short tracks - ist's fairly good conducting, but not absolute stable over time and temperature-changes.

It's a viscous paste, can be dipped, dispensed, drawed ... then cure around 120 centigrades to 'solid' ... but it's really pricey too

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

I've had a look at conductive plastics too, and from everything I read they have significant resistance- dozens or even hundreds of ohms per meter, so fine for signals but useless for high current stuff.

I've also encountered the idea of performing electrodeposition of copper as a post-processing step to significantly reduce the resistance, but this of course won't work in 3d unless the traces run over the surface of the object.

you can make some basic stuff really easily by mixing graphite powder with glue or epoxy

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Wooden Mendel
Teacup Firmware

... search for 3D-MID-methods - here you build with a plastic mixed with metallic particles or salts and convert parts of the surface by heating/burning with a laser into conducting trays and grow metallic copper on this thrays with electrochemistry ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]