Printing PCBs

I've been thinking a bit about the recent movement to make repraps print PCBs on their own. Why exactly are they going for a plastic / solder method? It seems like that is not a solution that would scale down very well.

Is there a particular advantage of using extruded plastic and solder over say, drawing or printing the circuit in ink, on a bare copper PCB and then using chemical to etch it? Or you could possibly cover the bare copper with tape and use the reprap to cut ( with a rotating exacto-knife like blade ) the circuit for etching. A precise enough milling head could even cut away the copper from a bare pcb and drill the holes too ( which is certantly nothing new, but it's tested and proven to work well ).

Thoughts?

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Thoughts?

Agreed.

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Is there a particular advantage of using extruded plastic and solder over say, drawing or printing the circuit in ink, on a bare copper PCB and then using chemical to etch it?

Correct. There's no preliminary advantage. Adrian et. al. have focused on trying to innovate a new process rather than first demonstrate success and workflow with a way to do the old technology that actually works, by you know, bolting a marker on to their machines and just etching some pcbs.

Exhibit A:
[www.maplin.co.uk] RESISTANT PEN
[www.stefanv.com]
[www.dutchforce.com]
I think the Steadler Lumocolor Red works, available in every art supply store on the planet.

So far depositing metal tracks has been a complete and utter intellectual rat hole, as far as I can tell. Eventually, maybe we'll find some magic alloy or polymer blend which will be cheap, and you know, just perfect. (Cue: angels singing)

It will allow us to build circuitry into our machines and components, rather than mucking about with copper wire and pcbs that just work. This will actually be dead sexy, and we can do things like (waves hands) electropolymer transistors. Except right now we've had absolutely fuck-all cooperation from plastics researchers for samples. To speak frankly, I've seen zero ROI on this research topic. We can blame the folk who've been stingy with samples for part of this.

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Or you could possibly cover the bare copper with tape and use the reprap to cut ( with a rotating exacto-knife like blade ) the circuit for etching.

Yup. The fablab folk do this with their vinyl cutters all the time.

I think I read that in "Fab". See also this thread:
[dev.forums.reprap.org]

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A precise enough milling head could even cut away the copper from a bare pcb and drill the holes too ( which is certantly nothing new, but it's tested and proven to work well ).

Yup. I've read that it's expensive and slow compared to other methods. CNC drilling is supposed to be really helpful, though.

More importantly, having a spindle on your machine is a revolutionary improvement. It means you can through-hole or rout aluminum sheet, etc.

All of these methods we've discussed are for prototyping. The tipping point is probably around 20 boards? Once you're in production, like Zach's operation, you just go with a board house. Unless you want to turn half your garage into a board house. But there you've taken on massive opportunity costs, (including lining up suppliers for big cheap sheets of board), as opposed to uploading your eagle files, punching in your visa number, and watching the UPS truck show up 3 days later with several hundred perfect boards.

That said, most experimenters need < 20 boards at a time, and they need something _right_ now, not in 3 days.

This should be up on the wiki, but right now, I'd like to see someone such as myself actually do it, rather than just harvesting content off a few other sites.

Is it ok if I hijack the thread and change the title "Has anyone made PCBs with their RepRap?" I'm feeling a little punchy right now.

Heh. Thats quite a response in just under an hour from my original post. I'm impressed.

I'm just hoping to just stir up some conversation around this. I've been following these forums like a crack fiend over the past few months, and I haven't seen a whole lot of discussion over this topic in particular.

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Correct. There's no preliminary advantage. Adrian et. al. have focused on trying to innovate a new process rather than first demonstrate success and workflow with a way to do the old technology that actually works, by you know, bolting a marker on to their machines and just etching some pcbs.

I figured that these efforts were mostly driven by the desire to keep the project true to it's sustainable roots.

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A precise enough milling head could even cut away the copper from a bare pcb and drill the holes too ( which is certantly nothing new, but it's tested and proven to work well ).

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Yup. I've read that it's expensive and slow compared to other methods. CNC drilling is supposed to be really helpful, though.

Why would this process necessarily be slow or expensive? Couldn't you use a fine tip bit and just trace around all of the lines, leaving the unused space as ground?

JHoff

Edited 1 time(s). Last edit at 12/02/2009 10:44PM by jhoff.

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I figured that these efforts were mostly driven by the desire to keep the project true to it's sustainable roots.

Which is laudable, but ...
1) The roses metal and woods metal is expensive, and I don't trust random non-copper metals for long-term use unless we've done systematic testing to make sure we don't have wonky electrochemistry where one metal eats the other. Woods metal is pretty well understood from its use in physics apparatus, so maybe it's safe.

On the other hand, Adrian et. al. is doing basic research, which is important. Because all the conventional methods are just that. We can do them, we just haven't.

1b) Sourcing. The marketplace has set up lots of tools for the conventional pcb prototyping pathway. We're looking at 'scrounge some woods metal on ebay' or 'yeah, we're waiting on the boys in the lab to make another 300 mL of fancy electro-plastic'.

2) We need a solution which works right now. That means bolting a $3 pen onto the darwin, to begin with.

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Why would this process necessarily be slow or expensive? Couldn't you use a fine tip bit and just trace around all of the lines, leaving the unused space as ground?

I'm very fuzzy on this bit, but I think you have to worry about cross-talk or something if you don't have enough isolation. Sometimes it bites you, sometimes it doesn't? Or maybe it's just an issue of getting solder bridges _everywhere_.

Forrest Higgs has done a bit of board engraving, I think, as have half the people on this forum, most likely. Just not with a Darwin or Mendel.

I don't know how long the tips last. Hundreds of inches?

But it's still much faster to buy sensitized boards, print a mask onto transparency with a laser/inkjet printer, bodge together an exposure cabinet from a box and a uv light bulb, and then expose the boards, etch, expose the boards, etch, expose the boards, etch, expose the boards, etch. (etc.)

I don't have any numbers or experience to present, but the CNC router/ other methods comparison might be like the difference between a pen plotter and a stencil or stamp. It's a 1D process versus a 2D process.

Now you've got to drill all those boards ...

-----------------------------

Here's a nice photo-tour of a modern board house that came up in a search just now.
[www.ami.ac.uk]

SebastienBailard Wrote:
-------------------------------------------------------
> But it's still much faster to buy sensitized
> boards, print a mask onto transparency with a
> laser/inkjet printer, bodge together an exposure
> cabinet from a box and a uv light bulb, and then
> expose the boards, etch (etc.)

how about print, iron transfer, etch? cupric chloride can be reused indefinitely if you feed it air and some HCl occasionally.

Laser toner is actually super-fine black plastic powder - maybe we could just print a layer straight onto the copper with our reprap and etch?

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Laser toner is actually super-fine black plastic powder - maybe we could just print a layer straight onto the copper with our reprap and etch?

It's a 1D process. And you want it pre-solublized, e.g. a felt tip pen.

Not that a RepRap with 1024 tiny nozzles/inch wouldn't be cool. But we're a long way from there.

I seem to recall ( a long time ago ) that using a marker ( like a sharpie ) resulted in pretty poor traces. Granted, I was still in High school the last time I actually last etched my own board, so I probably was doing something wrong, but I seem to remember having to basically coat the thing in solder afterwords because there were so many breaks in the traces.

Is there something else that could work? Maybe this is a silly idea, but what about extruded plastic? The two problems I would foresee with that is the reaction ( if any ) to the etching chemical, as well as it's ease ( or difficulty ) of removal. This is assuming that your extruder handled it's hair well enough.

If it worked, there would be no additional modifications needed to a Reprap. Granted its a whole other ballgame to fully automate, but the time it would take to print would be minimal, so automation may be unnecessary. You could just print a single layer out onto a pcb and drop it in the etching solution, then a short Sodium hydroxide (lye) bath later, you have your ready to drill pcb. Maybe we would get lucky enough for the plastic to just easily peel right off of the copper after the etching bath.

JHoff

jHoff: toner transfer method uses plastic in the form of laser toner, and many etchants are stored in plastic bottles or containers, so plastic is already proven to be an excellent resist

... i would try some MID-methods - e.g. fabbing with a paste mixed from coated metallic nanoparticles and a binder.

When fabbing, the paste dries/cures to a non conducting solid, but when heating the surface with a lowpower laser (1Watt should be enough, see my posts about diode-lasers), then the coating breaks free, carbonize, the metallic particles mold/fuse partially and the heated tray went conducting.

When growing some copper or other metall with galvanics on the conducting trays, you'll receive perfect solid metallic trays stable enough for soldering and mechanical stress ...

Viktor

How about making a photo-exposure head with a small fiberoptic to photo-etch sensitized boards? With some more modification you could even have it do both sides simutaniously with two fixed heads to get perfectly aligned two-sided foil patterns.

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jhoff
Is there a particular advantage of using extruded plastic and solder over say, drawing or printing the circuit in ink, on a bare copper PCB and then using chemical to etch it?

IMHO the most interesting circuits to fabricate require multilayer boards. These are seriously challenging to fabricate in a garage. To oversimplify: you have to etch, drill, electro-plate vias, bond, repeat, resist the pads, laquer, clean, 'tin' the pads, just to get the PCB. Then you need make a stencil, print solder paste through it, Pick & Place, and bake under stringent temperature control. The tolerances on these steps are almost all very close.

I've used UV and ferric chloride to make a single sided through hole 0.1" board, in a garage, and that wasn't trivially easy, or totally reliable. I fear that even just half the pitch would be much harder (narrower tracks etch away more easily, narrower gaps bridge more easily, etc).

I see many advantages to printing the metal:

One process on one machine produces a finished circuit.
- less space for manufacturing
- first 'board' is faster
No design specific tooling.
- small runs are as cheap as large ones
No wet chemical processes.
- less space
- less mess
- less smell
The circuit can be made with an arbitrary number of 'layers' without multiplying the cost. This make human place and route much faster and easier and means that more circuits can be placed and routed totally automatically.
- less effort
Circuits can be made 3D, with components layered over each other.
- potentially smaller
- potentially higher performance.
Heat sinks and/or coolant channels can be fabricated in place.
- potentially smaller
- easier
- small heatsinks cheaper for small runs

I'm going to work on this, I've got ideas (especially printing non-eutectic alloys or alloys loaded with copper microparticles), and I'll post any progress. Expect to hear from me over the next few months.

Cheers,

Leo

On the other hand, direct application of resist may produce good results, and I'm eager to see what you come up with.

Cheers,

Leo

The talk on this thread is starting to remind me of an article I came across recently about a researcher who was able to produce microfluid chips on the cheap using a laser printer and shrinky dinks:

[www.switched.com]

effectively replacing the need for $100,000 worth of equipment.

I know this doesn't directly answer any of the problems brought up so far (the need for appropriate materials to use to extrude conductive pathways, and the ability to build a 3d circut), but if an appropriate material is found, this may be an economical way to make the path created from a relatively low resolution extruder head become a much higher rez shrunken version.


On the same topic, I remember many years ago at a Computer City (I told you it was many years ago) I saw an inkjet type printer that printed with color (CMYK) and two different types of foil (gold and silver color). The gold and silver cartriges were incredibly expensive, and the printer appeared to have already run out of the metalic ink from people printing an endless number of samples. I'm trying to find out what the stuff was that it printed and how conductive it was. It may be worth research if I can find the original printer.

MID is an important research topic, and I see where Adrian is headed now. And Leo. And ...?

However, we should try to demonstrate and integrate some of the well=known and effective methods, such as marker-resist, laser-printed optical masks on transparency, and so on. To say nothing of rotary tools.

These are not research topics, exactly. They're well written up online. And anyone with a 3-axis positioning system can play, just by buying a marker or a dremel.

Why would you want to use your RepRap to print a PCB, when you can use your laser Printer?

[nospecifictopic.blogspot.com]

Best step by step.
[www.fullnet.com]

I think the RepRap would make a great CNC for the holes if you where doing mass production, but beyond that, it's going to be hard for RepRap out do the quality and price possible with this procedure.

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repraplogphase.blogspot.com

Why would you want to use your RepRap to print a PCB, when you can use your laser Printer?

Partially because of a sense of completeness and because we're fabrication geeks. And also because if all it takes is a marker, and you don't have a laser printer or a lightbox, you can still do it without heading out to kinkos.

There are many ways to do it. Laser printer is one of the best ones, I agree.

> There are many ways to do it. Laser printer is one of the best ones, I agree.

And a tedious one. Especially for two sided pcbs.

You simply cant finish with a pcb under an hour. No matter how good you are. I would consider using a darwin with a dremel head much more effective. Less labour work in the process.

... e.g. - single-sided PCBs 160x100mm, ca. 30 components (2 SMD), ca. 100 holes, designed and isolation-contours with Target ... had to make 6 of them:

- milling the isolation lines ~ 20 minutes.
- drilling holes ~ 3 minutes.

Viktor

Has it been mentioned to print with an acid paste?

You can either do a full photo negative or just outline the trace like you would with a dremel

If you let it go too long it would obviously spread beyond the contact point.

Sawdust could probably used as a binging agent with standard etching acid as the solvent, I would assume you would want it to be roughly the same consistency as henna paste (the temporary tattoos).

I will do some experiments when I go home on leave next week.

Victor, or anyone else who knows

I need to use Bertha to mill some simple prototype PCB s.
As your last post indicates milling a PCB requires a different design style/concept to make a millable PCB to an etch able PCB design.

My questions are based on how you can simply switch from a track based design to an isolation based PCB design.

Do any of the Free PCB design packages support this?

Is there another package that can take a tracked based design and convert to an isolation based design?

Are any of the intermediate files compatible between PCB design packages?

For example the .sch file type.

Or are there any file formats that allow/give this ability or file convertion tools?

Nophead, Grael and AK47 are using the KiCad PCB package I think that they all buy etched PCB s and do not mill their PCB designs. For the moment I am trying to avoid spending money so milling prototype PCB s is my only option.

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Bodge It [reprap.org]
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BIQ Sanguinololu SD LCD board	BIQ Stepcon	BIQ Opto Endstop
BIQ Heater Block PCB	BIQ Extruder Peek clamp replacement	BIQ Huxley Seedling
BIQ Sanguinololu mounting	BIQ standalone Sanguinololu or Ramps mounting	Print It Stick It Cut it

My rep strap: [repstrapbertha.blogspot.com]

Buy the bits from B&Q pipestrap [diyrepstrap.blogspot.com]
How to Build a Darwin without any Rep Rap Parts [repstrapdarwin.blogspot.com]
Web Site [www.takeaway3dtech.com]

Hi Bodge It,

... i'm using Target and Eagle for free ...

Eagle is limited in size to 100x80mm, Target is free in size but 'limited' to one sheet, max. doublesided PCB's (no multilayer) and max. 250 pads/pins.

Both programs can output etching films or isolation-lines ...

Viktor

There are a set of scripts available for Eagle that will output gcode for a board you've designed and routed. It is how I plan to use my repstrap (with the 5D firmware) to mill circuit boards. This link describes the things you have to add to eagle to get it to spit out gcode: [www.brusselsprout.org]

As stated earlier in the thread, fablabs use both vinyl cutter machines and a small CNC mill called the Modela to make circuit boards. They use both Eagle, and an open source program developed by them called cad.py (top link on this page: [fab.cba.mit.edu]). They get really good results with the Modela, and build a lot of surface mount stuff with small lead pitches (e.g., TQFP packages).

Vinyl cutter: [fab.cba.mit.edu]
Modela mill: [fab.cba.mit.edu]

The repstrap we built currently has a dremel in it (that I'll be using to make a pinch-wheel-extruder drive block as soon as I figure out why it is losing steps in the Y axis), and I'm planning on using it to make PCBs (with a 1/64" carbide bit). Based on vibration and play in the spindle (Dremels are not precision instruments) I'm considering making my own spindle based on this design: [mtm.cba.mit.edu]. Depending on the vibration characteristics, it might even be something suitable for mounting in a Mendel.


As an extra added bonus, here is a simple-to-make machine specifically designed to mill PCBs (related to the MIT "How to make (almost) anything" class): [mtm.cba.mit.edu]

Wow guys ~ Thank you Victor I do now have a copy of the 5.6 free Eagle.

Quadshop... [www.brusselsprout.org] is a very interesting blog thank you.

Yes I was thinking of making a spindle like that as the Dremel is extremly noisy
My construction will be using two blocks of wood a length 22mm copper pipe with skate bearings at each end for the spindle drive bearing system. possibly two at the tool end of the spindle thou.

It will look a little like the slider system here.
An abandoned attempt at making a slider bearing for RepRap but ideal for a spindle I think.

[repstrapdarwin.blogspot.com]

I am surprised to see a direct drive as al the other spindle systems I have seen have pulleys and belts to drive the spindle.

As for the bonus link Wow that looks a little familiar the style of machine is very much like the Makerbot machine.

It looks like the it could be a good test project for my Big Bertha project which should be able to CNC an 4' X 2' sheet of MDF when its finished.



Great links thank you.

Vinyl cutter: [fab.cba.mit.edu]
Modela mill: [fab.cba.mit.edu]

Edited 1 time(s). Last edit at 12/10/2009 12:35AM by BodgeIt.

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Bodge It [reprap.org]
=======================================

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BIQ Sanguinololu SD LCD board	BIQ Stepcon	BIQ Opto Endstop
BIQ Heater Block PCB	BIQ Extruder Peek clamp replacement	BIQ Huxley Seedling
BIQ Sanguinololu mounting	BIQ standalone Sanguinololu or Ramps mounting	Print It Stick It Cut it

My rep strap: [repstrapbertha.blogspot.com]

Buy the bits from B&Q pipestrap [diyrepstrap.blogspot.com]
How to Build a Darwin without any Rep Rap Parts [repstrapdarwin.blogspot.com]
Web Site [www.takeaway3dtech.com]

What about having the reprap solder bare copper wire to proto-board? The proto-board comes with a grid of pre-drilled pads. You just need the connections. It would be similar to an automated sewing machine in that respect.

The head would need to spool and cut copper wire and also solder the wire to the appropriate pads. Alternatively the wire could be placed with a pre-applied adhesive using one head, soldered with a second head and the surplus wire cut with a third one.

A further improvement would be to use insulated wire and automate stripping the insulation. Melting it off might be the simplest way. Insulated wire can have any number of overlaps and that's almost as good as multilayer boards.

Why not just print the board and circurt board at the same time? Add a few chips and your done. I read something on popsci about silver ink that xerox was work on that could be applyed on just like the plastic at room temp.

[www.popsci.com]

My idea is you make the board with the holes for the chips, and then apply the ink from the silver ink from a another nozzle, add the chips and there you have a curcirt board that you could use.

codeflash

Hey,

I've only read half of this thread (it seems to have snowballed), but you may be interested in these links for easy ways to make PCB's at home.

Method 1
Method 2

I havn't tried either to date, but here they are none the less.

i dont know if this has been mentioned before but i was at radio shack the other day and saw a pen for repairing PCB, and thought that it could be used to draw the paths. like the sharpie attachments for drawing.

davidrvalencia: I have such a pen, and they're great for certain things, but not suitable for our purposes because 1) they're quite expensive and 2) you can't solder to the track they lay down. They lay down a track of micronised silver packaged in a combination glue and solvent. I think the tracks would have significant resistance compared to solid copper, so not much current ability.