Homebrew_PCBs

Cute idea.



The silver conductive ink has been around for ages (quite expensive too) and is usually used for repairing PCB traces. People have managed to put it into an inkjet cartridge, eg: http://dl.acm.org/citation.cfm?id=2493486, the main barrier was the silver particles were too big.



This looks like what Squink are doing as well.



I guess the ‘conductive glue dots’ is solder paste. Or maybe not as ‘place in oven’ seems to be missing from the instructions. A different formulation to make the ink thicker?



Just the pick & place would be handy enough.



Tony











Wow, have you seen this?

https://www.kickstarter.com/projects/botfactory/squink-the-personal-electronic-circuit-factory



Never heard about the conductive glue, but it sees to work pretty well. 10 mils is not bad, It will be perfect to me when they get 6 mils resolution, vias and multilayer, but it is a very interesting beggining. It also has pick and place!



I really liked it, it's the future for amateur and hobby. I'm not going to spend more than $3000 on it, but I hope this can get cheaper and better in a near future.












[Non-text portions of this message have been removed]

On 7/16/2014 6:18 PM, Peter Johansson rockets4kids@...
[Homebrew_PCBs] wrote:

>
> On Wed, Jul 16, 2014 at 6:51 AM, Vicent Colomar Prats
> vicentecolomar@... <mailto:vicentecolomar@...>
> [Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com
> <mailto:Homebrew_PCBs@yahoogroups.com>> wrote:
>
> > Never heard about the conductive glue, but it sees to work pretty
> well. 10 mils is not bad, It will be perfect to me when they get 6
> mils resolution, vias and multilayer, but it is a very interesting
> beggining. It also has pick and place!
>
> Did you see the part on conductivity?
>
> >> After drawing the line shown above (1cm x 8cm), we measured 0.7
> ohms of resistance.
>
> Now calculate the resistance of those 10 mil traces.
>
> -p.

Hello--

I posted this topic a while ago, and I haven't received any responses from
3D printer owners who might have tried this approach (see below). As for
conducive-ink deposition, making reliable connections to traces may
prove problematical. Also, based on my infrequent use of a color-inkjet
printer, cartridges tend to dry out and/or clog print heads at a dismaying
rate. The high resistivity of the traces cited above may be troublesome, but
ink costs may be the showstopper.

73--

Brad AA1IP

************
Hello--

I'm posting John's thoughtful comments (which I very much appreciate) below
and inserting my responses. My original posting is appended.

On 5/6/2014 11:39 AM, John D'Ausilio wrote:
> Responses inline (since there are so many questions
>
>
> Questions and caveats:
>
> --Component pads' shapes may not translate well from Gerber code--
> i.e., several overlapping passes would be needed to make large pads.
> In general, printers which extrude ABS or PLA use a tip with a 0.4mm
> hole. The resulting "noodle" is generally around 0.5mm wide and
> roughly circular in cross-section.

Hello, John and the groups--

Depending on the "squishdown" factor, a 0.5 mm wide noodle might produce
a 0.020 inch wide trace. If the noodle doesn't become a semicircle upon
contact with the copperclad surface, the trace width would be narrower.
> --Extruded plastic may not adhere well to copper.
>
> --Unetched copperclad board may need to be heated for best trace
> adhesion.
> Getting the plastic to adhere to the build platform is challenging.
> ABS is usually printed on a heated metal plate covered with Kapton, or
> lately on a heated glass plate sprayed with cheap hairspray.
> I can try clipping some copperclad to my build plate and see what
> happens ..
Copper's higher thermal conductivity might be our friend. Imagine
using a couple of Dale RH-50 chassis-mounted wirewound resistors
clipped to opposite sides on top of the copperclad board. The resistors
could provide auxiliary heating.

> --Dimensional issues: how accurately can a 3-D printer locate
coordinates
> at distant extents of a large layout?
> Machines with orthogonal mechanics have the same accuracy at all
> points on the build plate. Machines with delta mechanics lose
> resolution towards the edges. The vast majority of hobbyist printers
> are orthogonal.
Excellent!
>> --What's the narrowest (or widest) trace that can be extruded?
>>
>> For general object printing the goal is to squash the first layer into
>> the build plate, reducing it's diameter and spreading it out.
>> Realistically you could probably achieve around 0.55 or so with a .4mm
>> nozzle
Converting 0.55 mm to inches would produce traces a whisker under .022
inches in width.
> --How accurate can the copperclad board be leveled on the printing
stage?
>
> We already level our platforms, assuming the copperclad is
> dimensionally stable over 20C-100C range (we usually heat to 100C for
> ABS) then leveling shouldn't present a problem.
One online source lists "...G-10 and FR-4 are rated at 285 degree F
continuous operating
temperature..." but I didn't locate a value for horizontal coefficient
of expansion.
>> --How well do various types of extruded plastic resist commonly-used
>> copper
>> etching solutions?
>>
> That's the $1000 question .. almost all printers in hobbyist use will
> print ABS or Polylactic Acid (PLA). I don't etch boards so I have no
> chemicals here, but I'd be happy to send you some samples.
The "go to" source for chemical resistance is apparently Cole-Parmer:

http://www.coleparmer.com/Chemical-Resistance?referred_id=11033&mkwid=sJFDnHw4J&pcrid=12430988319&kw=%2Bchemical%20%2Bresistance%20chart&mt=b&pdv=c&gclid=CLC49vnUl74CFe99OgodbF4A_w


...Or TinyURL...

*http://tinyurl.com/jwnnbk2

Commonly-used etchants include ferric chloride, hydrochloric acid,
ammonium persulfate
and vinegar.

ABS resistance:

Vinegar A-- Excellent
*
Ferric Chloride A-- Excellent

Hydrochloric Acid 20% A-Excellent

Ammonium Persulfate A^2 -Excellent (2 = satisfactory to +120 F (+48 C)

I couldn't locate a reference for polylactic acid's chemical resistance,
but I'm pressed for time.

-Could you use different colored extrusion plastics to mark, say, power
and ground traces?
> Not easily .. it's very challenging to print more than one color at
> the same height (you would need more than one nozzle, and a way to
> move them away from the piece so the unused one didn't plow into
> existing plastic)
Okay-- variously-colored resist would be a bonus.
> --Could you leave the extruded plastic traces in place as a solder mask
> and clean the plastic away only from component pads requiring soldering?
> All of our plastics melt at 220C or less .. not compatible with
> soldering temps.
That might not be a problem if the plastic melts short of contaminating
the solder
joint. Careful removal (mechanical abrasion?) of the resist on the pads
would
be necessary.

Further comments from all are welcome!

73--
Brad AA1IP
********************************

Original posting follows:

Excuse the somewhat off-topic nature of this posting, but
I'm picturing the Glowbug application (i.e., custom component-terminal
boards) along with QRP and general circuit-design applications.

Has anyone in the group used a 3-D printer to create one-off PC boards?
Consider this as the inverse process of removing copper via a
CNC milling machine.

***********
Here's how the process might work; unfortunately, I don't own a
3-D printer, and thus the following description is theoretical and
riddled with caveats.

1.) Create a PC-board layout using any of several available tools.

2.) Translate the layout program's output into an X versus Y format
understood by the 3-D printer.

3.) Extrude plastic to "draw" the layout's traces on a sheet of copperclad
board.

4.) Etch the board.

5.) Remove the plastic traces and drill holes in pads to accommodate
through-hole components' leads; tin-plate the board if desired.
******

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On Wed, Jul 16, 2014 at 8:18 PM, Brad Thompson
brad.thompson@... [Homebrew_PCBs]
<Homebrew_PCBs@yahoogroups.com> wrote:

> The high resistivity of the traces cited above may be troublesome, but
> ink costs may be the showstopper.

I don't know if it will be a "showstopper" for anyone who can afford
$3000 for the hardware, but there is certainly a reason they did not
mention consumable costs at all in the description.

-p.

> > Never heard about the conductive glue, but it sees to work pretty well. 10 mils is not bad, It will be perfect to me when they get 6 mils resolution, vias and multilayer, but it is a very interesting
> beggining. It also has pick and place!
>
> Did you see the part on conductivity?
>
> >> After drawing the line shown above (1cm x 8cm), we measured 0.7 ohms of resistance.
>
> Now calculate the resistance of those 10 mil traces.
>
> -p.
>

I'd be doubtful of the 0.7 ohms measurement, that meter wouldn't be accurate enough for that small a reading. Plus you'd need to know the thickness - I'm assuming they know that but it still needs to be mentioned (and used in the calc as obviously thicker = lower resistance).

Googling around for the figures for membrane switches gives their 0.0875 ohms a bit high by comparison, but not by much. People quote anywhere from 0.01 - 0.06, more silver = lower ohms.

As someone mentioned it'd work ok for digital circuits.

At least it's quieter than milling.

A thought that just occurred to me - if they're using an inkjet cartridge, why not use a printer for the first step? (Speed maybe? Printer too fast?)

Tony

On Thu, Jul 17, 2014 at 11:20 AM, 'Tony Smith' ajsmith1968@...
[Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:

> I'd be doubtful of the 0.7 ohms measurement, that meter wouldn't be accurate enough for that small a reading.

I'm giving them credit for knowing how to use a multimeter properly,
and assuming they are using one actually capable of sub-ohm
measurement. If they have failed on this, I don't even want to think
about what *else* they have overlooked.

-p.

And, of course, the actual impedance will be frequency dependent.

 

On Thu, Jul 17, 2014 at 11:20 AM, 'Tony Smith' ajsmith1968@...
[Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:

> I'd be doubtful of the 0.7 ohms measurement, that meter wouldn't be accurate enough for that small a reading.

I'm giving them credit for knowing how to use a multimeter properly,
and assuming they are using one actually capable of sub-ohm
measurement. If they have failed on this, I don't even want to think
about what *else* they have overlooked.

-p.

Hello, Jan--

Thank you for your thoughtful comments-- I have added a few responses,
not as criticism
but as further attempts to apply bounds to the problem (>).

On 7/16/2014 11:41 PM, Jan Kok jan.kok.5y@... [Homebrew_PCBs] wrote:
> I've used hobby-type 3D printers and also used HP pen plotters (for
> their normal purposes, not for producing PC boards). Based on that
> experience, I suspect that using using something like an Ultra Sharpie
> pen (but with still finer tip) to draw resist on a board would give
> better results than trying to lay down plastic resist with a 3D
> printer. The problems with laying down plastic resist are:
>
> Hard to control the height of the nozzle above the board with
> sufficient accuracy, thus the traces would be wider in some parts of
> the board than others.
> Trace-width variability might not be a problem for low-density,
discrete-component layouts. For
surface-mount designs, fat and lumpy resist would cause problems.
> How would you mount the board to the table perfectly flat?
>Double-sided-sticky tape between the copperclad and the table? Drilled
and tapped holes
in the table and washers overlapping the blank board's edges? Screws
through the washers
and into the mounting holes would clamp the board to the table.
> Even a slight bend in the board could cause lots of problems.
>Agreed.
> Some copper clad also has a surface texture due to the fiberglass
> weave in the substrate.
>Does this depend on the cladding's thickness? It might be needed to
specify 1-ounce copper cladding.
> That could lead to variable trace widths.
>Agreed.
> In contrast, the pen tip can contact the board with light spring
> pressure, thus the trace widths should be more consistent.
>Would pen-point life be a problem? Flare due to breakdown under spring
pressure
would cause thicker traces.
>
> There _may_ be problems with getting traces to start and stop exactly
> where you want. The way to stop a trace is to stop pushing plastic
> through the heated nozzle, while continuing to move in X or Y. In fact
> the extruder motor is usually reversed a bit to avoid continued
> extrusion due to compression of the plastic fiber into the nozzle.
> Then when you want to start a new trace, you have to run the extruder
> forward by about the same amount before the plastic starts to extrude
> again. I suspect that tuning that process could be time consuming, and
> the process might not be stable (depending on nozzle temperature and
> other factors).
>Ah-- I was unaware of that as it's not covered in the ads<g>. Could
the extruder nozzle be raised (Z axis)
as the motor gets reversed? That might leave a vertical lump at the
trace's end.
>
> I think a 3D printer would be a great platform for experimenting with
> pen-plotting resist onto copper clad. Just replace the extruder nozzle
> with a pen holder. Or possibly an ink jet cartridge.
>That's an excellent point. Flat-bed pen plotters are essentially 2-D
printers, with a binary
Z axis (pen up or down), and finer control might be an an improvement.

If someone out there has a 3-D printer and PC board design software,
perhaps he or she
could actually try a sample layout? That would yield some definitive
results, or point out
showstopping flaws.

Thanks again, Jan, and 73--

Brad AA1IP

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> > I'd be doubtful of the 0.7 ohms measurement, that meter wouldn't be
> accurate enough for that small a reading.
>
> I'm giving them credit for knowing how to use a multimeter properly, and
> assuming they are using one actually capable of sub-ohm measurement. If
> they have failed on this, I don't even want to think about what *else* they have
> overlooked.

Well yeah, but THAT meter isn't what you'd use for the job. Apparently it's a little more complicated than that - http://en.wikipedia.org/wiki/Four-terminal_sensing

Whatever the resistance is, it seems to work.

Tony

Dan,
At $3500 a piece, not many chances for DIY. But the industry would not even look at it. If timing is an issue, Industry will pay expediting fees to get the pro to on time.
This might be for tinkerers, but not for serious designers. the result is far too different from a real multilayer PCB to even be considered for prototypes.
Before I retired, we would get PCB with next day delivery, and proto assembly house would build immediately when PCB were delivered.
It might seem expensive for your DIY pocket, but not for RD&E groups on a tight schedule.

We don’t even know if they will be able to have a proper design for the change of tools, from INK to GLUE to P&P.
INK printing needs are very different from GLUE dispensing, and Pick and Place is a totally new ball game with camera inspection, and head rotation.

I am not sure what is the niche market for such a device. a real 3D printer with metal and plastic (laser sintering) capability would be a better option, making multilayer more probable.

My $0.02,
Jean-Paul
AC9GH

On Jul 17, 2014, at 12:44 PM, Daniel Donnelly KC7VDA@... [Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:

>
> What a marvelous machine!
> this is not just a device that prints the traces, it also deposits the conductive glue and picks and places the components!
> If you have ever done any prototyping you know what a pain surface mount assembly is, This little machine eliminates all the drudgery and combines conceptualization, prototyping and evaluation to become a one step process.
>
> At a cost of $3000.00 I don't know of many amateurs that would buy it, but in industry $3k would just about pay the secretary to type up the proposal for a new product.
> The Squink is a concept that could revolutionize not just small business but electronic design as a whole. I sincerely hope that they get the funding for this project. If I had a few of hundred to spare I would certainly invest in this company. this is a ground floor opportunity.
>
> Dan kc7vda.
>
>
>