Desktop PCB production

Back to your original question - how about a mechanical system that could apply copper tape to a board, with little spots of solder paste at X/Y junctions? When all done run it thru a re-flow oven to join the junctions.

Looks like width would be an issue - I seee plenty of places with 10 mil thick, but not 10 mil wide.

Perhaps some kind of sintered metal that could then be baked/cured, similar to conductive ink, but in a more solid form.

Or! cover a board with a meltable powder, use laser to melt the traces into place, and then gather up the excess for the next application.

Do you have a link to this Shapelock stuff?

CrossRoads:
Back to your original question - how about a mechanical system that could apply copper tape to a board, with little spots of solder paste at X/Y junctions? When all done run it thru a re-flow oven to join the junctions.

Actually, I have manually used such a construction method in the past. Using the copper tape and kapton tape, I have made simple flexible circuits.

CrossRoads:
Looks like width would be an issue - I seee plenty of places with 10 mil thick, but not 10 mil wide.

Indeed. I got around this somewhat by cutting the tape with a hobby knife into thinner strips. Very time consuming. But the circuits were very simple.

CrossRoads:
Perhaps some kind of sintered metal that could then be baked/cured, similar to conductive ink, but in a more solid form.

Or! cover a board with a meltable powder, use laser to melt the traces into place, and then gather up the excess for the next application.

I believe the second idea is the same. Isn't that what sintering is? Or am I mistaken? That definitely does sound like the best approach since a laser could provide very fine detail.

CrossRoads:
Do you have a link to this Shapelock stuff?

It is called shapelock, polymorph, or friendly plastic. Polymorph seems to be the cheapest variety, though it is not so easy to get in the U.S. and getting it shipped from the UK makes it more expensive than shapelock.

https://www.inventables.com/technologies/hand-moldable-plastic
http://www.jameco.com/webapp/wcs/stores/servlet/StoreCatalogDrillDownView?langId=-1&storeId=10001&catalogId=10001&freeText=shapelock&search_type=jamecoall
http://www.kelvin.com/Merchant2/merchant.mv?Screen=PROD&Product_Code=570071

This one is the best offer I have seen. 1Kg for $22 is an awesome price for the stuff:
http://letsmakerobots.com/node/11563

And of course the original site:
http://shapelock.com/page2.html

Those pieces that I posted pictures of only used about a tablespoon of the stuff and could certainly be made even thinner and better shaped which would use less material. This stuff is extremely strong once it hardens. It is about the strength of an acetal/delrin cutting board.

Here's a neat guide on the stuff:
http://www.c-d-c-shop.com/Products/Polymorph/Polymorph.pdf

And this is what the stuff really is (Polycaprolactone):

Cool. Thanks for the data.

Reading the wikipedia page, I found myself thinking "It's a floor wax! It's a dessert topping!"

Some things are confusing - "PCL is degraded by hydrolysis of its ester linkages in physiological conditions (such as in the human body) and has therefore received a great deal of attention for use as an implantable biomaterial."

Wouldn't degraded in the human body make it a poor choice for a long term implantable device?

What "cures" (for lack of a better word) the stuff into hardened material? Just application of heat, then it melts to shape and stays that way?

Sintering would require pressure and temperature. You'd probably want to look more at some kind of paste as opposed to a powder.

Sintering, yeah, just showing my lack of knowledge in that area.

How about low vacuum pressure vaporization? Use laser to pretreat the areas to be coated, then put the board in a little oven for the treated areas to attract the vaporized metal (like Aluminum)? Might take a few passes for the metal to build up enough thickness to be durable for reflow soldering to attach parts.

Due to another post, I just realized that I have one of these sitting in storage:

It is a kodak dye sublimation (thermal) printer meant to print 4x6 to 5x7 photos. I bought it dirt cheap on ebay several years ago and used it alot for a while then stored it away and forgot about it.

Hmm... I wonder how easy it would be to modify this to print a resist directly to the board. Of course, it would still require etching, and I don't know if the wax would hold up to etchant. I smell an experiment coming...

One consideration is that the ribbons that I have apply a clear wax coating after the print to seal the image. I will have to find a way to bypass that or it would cover the entire board at the end.

Maybe use the salt, hydrogen peroxide, and (vinegar? alchohol? this mix was just posted in the last couple of days) as etchant.

CrossRoads:
Sintering, yeah, just showing my lack of knowledge in that area.

How about low vacuum pressure vaporization? Use laser to pretreat the areas to be coated, then put the board in a little oven for the treated areas to attract the vaporized metal (like Aluminum)? Might take a few passes for the metal to build up enough thickness to be durable for reflow soldering to attach parts.

I was just looking at UV curable inks to use as a carrier for some type of metal powder. Seems like it would create a lot of waste. What ideas do you have for the "pretreat" part? If the material is nonconductive, it may be possible to use static just like a laser printer and some type of metalized toner.

Maybe even something along the lines of an etch-a-sketch which would use a magnet beneath the material to hold the conductive powder. Again, the difficulty is finding something with a melting temperature above soldering and finding something capable of providing that amount of heat in a localized manner.

I really appreciate the ideas and input!

CrossRoads:
Maybe use the salt, hydrogen peroxide, and (vinegar? alchohol? this mix was just posted in the last couple of days) as etchant.

I seen that the other day. Definitely something I would like to experiment with.

If you wanted to go the electroplating route you could first use conductive paint to mark out your traces, then use electroplating to make those traces thicker.

Pretreat, I don't know. Not sure what you could do to a piece of fiberglass to make something else want to stick to it.
Static electricity, conductive paint, seems like everything turns into a multi-pass process.
Maybe just burning off the clearences around traces with a laser is the way to go.

Here is a nice step by step guide, with videos of how one company does PCB manufacturing. They use photo-resist, and electroplating. Might give you some ideas.
http://www.eurocircuits.com/index.php/making-a-pcb-eductional-movies/35-front-end-tool-data-preparation-

CrossRoads:
Pretreat, I don't know. Not sure what you could do to a piece of fiberglass to make something else want to stick to it.
Static electricity, conductive paint, seems like everything turns into a multi-pass process.
Maybe just burning off the clearences around traces with a laser is the way to go.

WARNING: 100% noob question ahead!

Won't the laser be reflected by the copper surface of the board? Not only that, but you'll need an extremely powerful laser to do that. I have no idea how to calculate the required power of such laser, common sense tells me it'd be over 15W. How much does such a beast cost?

Focusing this laser to burn 4mil-10mil wide clearances between tracks and pads would also require some effort creating the focusing lenses (reuse a set of Nikkor or Canon lenses??), not to mention that there must be an excellent cooling system for the dissipated heat.

I for one would love a system where blank copper board goes into an end and a drilled, ready to solder PCB comes in the other.

I still have a working, ancient Epson Stylus Color II. they don't even make cartridges for it anymore, I guess. I'll try to work something out of it.

Indeed, it would reflect. I don't suspect that would be an issue so much, though. Enough of it would be absorped. Cutting metal with a laser is nothing new. I don't think the laser would need to be that powerful since we are cutting a very thin layer of copper. Removing the cut pieces, I am not sure about. I don't expect that the material would simply vaporize, but maybe that is how it works.

I would also suspect that focusing wouldn't be extremely difficult given that a laser printer is capable of such a fine pitch.

And you are right, a very large heatsink would probably be required to keep the overall copper cool while cutting it.

Come to think of it, one of the stupid things I tried when I was a teen was to play with the flyback transformer from an old 5 inch B&W TV I took apart. I remember being able to cut through soda cans like butter (and shocking myself several times while experimenting!) I wonder if something similar would work for this purpose? However, the main reason that worked is that it would burn through the material to create a complete circuit. Obviously that isn't what we want to do here (cut through the substrate.) But I wonder if placing both pieces on the copper just far enough that it can't arc on its own, so that the copper would complete the circuit and "blow" a line following the path of the eletrode and cathode. Obviously we know what happens when we blow a trace on a board, the copper trace appears to evaporate.

Sure, but just burn it at an angle, let the reflection be absorbed at the transmitter side. Or, pulse the laser with just enough power to remove the copper and not destroy the fiberglass underneath.
Could also be very thin copper, with things like liquid tin applied after burning to make what's left thicker.
I don't know how much power would be needed.
Also need to address vias and plated thru holes for component legs.

Board to drilled PCB - I think only CNC machines can do that right now, with the via/thruhole limitations.
You can get boards done overnight, just cost a lot more than sending away and waiting a few weeks.

CrossRoads:
Pretreat, I don't know. Not sure what you could do to a piece of fiberglass to make something else want to stick to it.
Static electricity, conductive paint, seems like everything turns into a multi-pass process.
Maybe just burning off the clearences around traces with a laser is the way to go.

heat/uv curing adhesives perhaps?

CrossRoads:
Board to drilled PCB - I think only CNC machines can do that right now, with the via/thruhole limitations.
You can get boards done overnight, just cost a lot more than sending away and waiting a few weeks.

If it were possible to get a laser to work, it would be capable of also doing the drilling/milling/slots, etcs.. by allowing it to cut all the way through some areas. This would need some type of adjustable columnating lens for varying the thinkness of the beam (well, or just multiple passes to cut away material.)

I am no laser expert, so if someone reading this is, I would definitely appreciate some insight or even a "No! That isn't gonna work!" feedback to stop thinking in that direction.

For vias and throughholes, I had seen a few years ago a system that deposited a bead of conductive adhesive and used a vacuum to pull it through the hole.

This guy made a double-sided board at home including vias and through-holes. Lots of steps, though.