Conductive Ink

[Rich Grise]

I'm about to embark on a prototyping project, and was thinking of
dead-bug, but from what I now of surface mount, dead-bug would
be ridiculous. So what I have in mind is to take a piece of single-sided
laminate (from the elec. store up the street), put it copper down,
which would be the ground plane, and on the top, glue the parts down
and literally draw the circuit.

So, does anyone have a good search phrase for google, or maybe
know off the top of your head where I might get some of the stuff?
Is that the sort of thing that general-purpose elec. stores (heat
shrink, NTE's, all the neat stuff that RS used to have) would
carry?

One caveat - this isn't a hobby project, I'm getting paid, so if
I should FOAD and STFW, please keep your reminders gentle.

Thanks,
Rich

 

[[email protected]]

I'm about to embark on a prototyping project, and was thinking of
dead-bug, but from what I now of surface mount, dead-bug would
be ridiculous. So what I have in mind is to take a piece of single-sided
laminate (from the elec. store up the street), put it copper down,
which would be the ground plane, and on the top, glue the parts down
and literally draw the circuit.

So, does anyone have a good search phrase for google, or maybe
know off the top of your head where I might get some of the stuff?
Is that the sort of thing that general-purpose elec. stores (heat
shrink, NTE's, all the neat stuff that RS used to have) would
carry?

One caveat - this isn't a hobby project, I'm getting paid, so if
I should FOAD and STFW, please keep your reminders gentle.

Thanks,
Rich

What do you mean SMT? SOIC-8? Or some sort of QFN? CSP?
Specify.
I've done some work with just a one-sided copper clad board, I sliced
it up with a grinding wheel for ground/power areas, and just tied the
signals together with 30 gauge wire. This was for a 32MHz VCXO.

Oh, I used Surfboards from Digikey too.

http://tinyurl.com/34n298

Of course, they're a whole 2 dollars.

For more RF-style stuff, I just engrave strips into copper clad
boards.

You could also use silver conductive epoxy. It's quite good, we've
pushed 3GBps signals in a test splice with the stuff.

 

[Rich Grise]

What do you mean SMT? SOIC-8? Or some sort of QFN? CSP?
Specify.

I don't know yet. To me, SMT == Surface Mount Technology. I guess
I've got some reading to do.

I've done some work with just a one-sided copper clad board, I sliced
it up with a grinding wheel for ground/power areas, and just tied the
signals together with 30 gauge wire. This was for a 32MHz VCXO.

Oh, I used Surfboards from Digikey too.

http://tinyurl.com/34n298

Of course, they're a whole 2 dollars.

For more RF-style stuff, I just engrave strips into copper clad
boards.

You could also use silver conductive epoxy. It's quite good, we've
pushed 3GBps signals in a test splice with the stuff.

Well, I've answered my own question - here's the first hit on "conductive
ink pen" at google:
http://www.hmcelectronics.com/cgi-bin/scripts/product/1530-0102

Thanks!
Rich

 

[Ecnerwal]

One caveat - this isn't a hobby project, I'm getting paid, so if
I should FOAD and STFW, please keep your reminders gentle.

While you can go with conductive paint, silver paint, etc (your search
terms)...

For a paying project, unless you are a masochist and in a terrific hurry
(hi D), have a prototype board house crank you out a few boards for
cheap, in a few days, with top and bottom copper, soldermask, plated
through holes, the whole nine yards. Looks better to the client who's
paying - "more professional". You can mount parts on both sides if it
makes it work better, or is easier to layout that way (but keep track of
which way is what or you'll be bending leads to flip packages).

Also: I'd be leery of trying to draw/paint to connect to typical
small-lead-spacing packages of most SMT ICs. The are pretty easy to
solder with a good layout and soldermask (you want the pads a bit beyond
where the leads stop for best manual soldering), but that same spacing
would be a real challenge with lumpy silver paint and a toothpick or
tiny brush.

expresspcb (I've worked with their boards, but they were ordered by a
guy I was doing assembly and test work for, so no direct connection)
seems to do nice work, and will spit out 3 for $51 plus shipping if you
keep it at their specific size limits for that deal. They and many
others have many other options...

 

[Ecnerwal]

seems to do nice work, and will spit out 3 for $51 plus shipping if you
keep it at their specific size limits for that deal.

Pardon - that's the "no soldermask, no screenprint" version.

 

[Rich Grise]

I don't know yet. To me, SMT == Surface Mount Technology. I guess
I've got some reading to do.


Well, I've answered my own question - here's the first hit on "conductive
ink pen" at google:
http://www.hmcelectronics.com/cgi-bin/scripts/product/1530-0102

OK here's a real question - teh chem-tronics one is anywhere from $18
to $23; RS has one for $5.98:
http://www.radioshack.com/product/i...roductId=2104395&support=support&tab=features

But the chemtronics one says "150 feet of traces" ; the RS one is so
cheap, should I expect more like 60 feet of traces? And the RS one isn't
stocked, so either one would have to be ordered.

Thanks,
Rich

 

[[email protected]]

I don't know yet. To me, SMT == Surface Mount Technology. I guess
I've got some reading to do.

I was just trying to get an idea of which technology you were thinking
of, and what frequency range/edge rates you want to tool around in.
How many chips? Surfboards are good for a few chips. More complex
stuff I would look into Olimex or a local proto PCB shop.

 

[Rich Grise]

While you can go with conductive paint, silver paint, etc (your search
terms)...

For a paying project, unless you are a masochist and in a terrific hurry
(hi D), have a prototype board house crank you out a few boards for
cheap, in a few days, with top and bottom copper, soldermask, plated
through holes, the whole nine yards. Looks better to the client who's
paying - "more professional". You can mount parts on both sides if it
makes it work better, or is easier to layout that way (but keep track of
which way is what or you'll be bending leads to flip packages).

Also: I'd be leery of trying to draw/paint to connect to typical
small-lead-spacing packages of most SMT ICs. The are pretty easy to
solder with a good layout and soldermask (you want the pads a bit beyond
where the leads stop for best manual soldering), but that same spacing
would be a real challenge with lumpy silver paint and a toothpick or
tiny brush.

expresspcb (I've worked with their boards, but they were ordered by a
guy I was doing assembly and test work for, so no direct connection)
seems to do nice work, and will spit out 3 for $51 plus shipping if you
keep it at their specific size limits for that deal. They and many
others have many other options...

Can they work from a schematic, or do I have to get software? The thing
is, this client seems to be in a hurry, so I was thinking of the quickest
way to get something running, that can be refined on the spot, "today".

I was thinking: Get something working in ink, characterize it, modify
as needed on the spot, and when it passes spec, _then_ get the board(s)
made.

And really, the only reason I'd want to use SMT is because that seems
to be about all that's available today, plus the small size and all
of that. I should probably check with him - I'd be much more comfortable
with through-hole - I can do that on perfboard or VectorBord(R).

Thanks,
Rich

 

[Ben Jackson]

and literally draw the circuit.

One tradeoff with surface mount is that it's harder to work without
a pcb, but on the plus side it's easier to make homemade pcbs because
there's no drilling. Assembly goes quicker because the parts and the
circuit are on the same side.

If I were you I'd get a resist pen and the single sided board and
draw + etch. Even if you don't want to use a layout program and do
toner transfer for everything, consider printing some footprints on
clay coated paper that you can iron on as needed before drawing the
rest of your circuit.

 

[Jeff Liebermann]

Well, I've answered my own question - here's the first hit on "conductive
ink pen" at google:
http://www.hmcelectronics.com/cgi-bin/scripts/product/1530-0102

<http://www.chemtronics.com/products/product.asp?id=7>
I've used those and had some problems.

The pen has a fairly fine tip, but not fine enough to lay an very thin
trace. It's great for laying large blobs, but not fine lines.

It comes out as a thick liquid, which like all good liquids, runs
downhill. If he board you're working on is anything but perfectly
horizontal, the ink will run.

Once used, the tip drys out and clogs after a few days. The tips come
in two sizes, but are not replaceable. I can clean it perhaps twice,
but no more. To solve this problem, I cracked open the pen, and
poured the contents into a medical glass syringe. Now, I have an
easily cleanable tip (stiff wire or cigarette lighter) and much better
control over the amount deposited.

 

[Vladimir Vassilevsky]

I'm about to embark on a prototyping project, and was thinking of
dead-bug, but from what I now of surface mount, dead-bug would
be ridiculous. So what I have in mind is to take a piece of single-sided
laminate (from the elec. store up the street), put it copper down,
which would be the ground plane, and on the top, glue the parts down
and literally draw the circuit.

So, does anyone have a good search phrase for google, or maybe
know off the top of your head where I might get some of the stuff?
Is that the sort of thing that general-purpose elec. stores (heat
shrink, NTE's, all the neat stuff that RS used to have) would
carry?

One caveat - this isn't a hobby project, I'm getting paid, so if
I should FOAD and STFW, please keep your reminders gentle.

http://www.radioshack.com/search/in...SK/2032058&categoryId=2032058&kwCatId=2032058

Catalog #: 64-4339


Is that what you are looking for?


Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com

 

[Tolstoy]

You could also use silver conductive epoxy. It's quite good, we've
pushed 3GBps signals in a test splice with the stuff.- Hide quoted text -

- Show quoted text -

I have an idea, might be good might be bad.
Is aluminum paint, the stuff sometimes people use to
paint radiators, conductive enough for traces?

 

[JosephKK]

Rich Grise [email protected] posted to sci.electronics.design:

OK here's a real question - teh chem-tronics one is anywhere from
$18 to $23; RS has one for $5.98:
http://www.radioshack.com/product/i...roductId=2104395&support=support&tab=features

But the chemtronics one says "150 feet of traces" ; the RS one is so
cheap, should I expect more like 60 feet of traces? And the RS one
isn't stocked, so either one would have to be ordered.

Thanks,
Rich

Chemtronics is slightly more reputable.

 

[robb]

I'm about to embark on a prototyping project, and was thinking of
dead-bug, but from what I now of surface mount, dead-bug would
be ridiculous. So what I have in mind is to take a piece of single-sided
laminate (from the elec. store up the street), put it copper down,
which would be the ground plane, and on the top, glue the parts down
and literally draw the circuit.

So, does anyone have a good search phrase for google, or maybe
know off the top of your head where I might get some of the stuff?
Is that the sort of thing that general-purpose elec. stores (heat
shrink, NTE's, all the neat stuff that RS used to have) would
carry?

One caveat - this isn't a hobby project, I'm getting paid, so if
I should FOAD and STFW, please keep your reminders gentle.

Thanks,
Rich

Hello Rich,

having just done the whole board fabrication stuff i can offer
this.

If you are near a fry's ? they sell a similar pen (CircuitWriter
by CAIG labs, silver/acetone/acrylic resin) can be soldered to
but it is difficult to control as one compresses the tip to
release the liquid. it seems to dry quickly and the pen gunks up
if you go backwards or over another not so dry trace.

The copper etching method is quite easy, alot easier than i
imagined. Since you are doing SMC (surface mount components) then
all the easier as the through hole drilling is the worst part

if you want a ground plane then Radio Shaft sells double sided
copper boards (probably super cheapo but it worked for me). just
spray paint the ground side completely with some ? acrylic/laquer
paint ? before etching

draw and print the PCB with a **laser printer** on magazine
paper, iron onto the cleaned copper board
, wash paper off, check for thin etch resist (fix with sharpie),
etch with (muriatic + %3 peroxide - 1:2), approx 4 minutes later
PCB is etched , remove and wash with water, remove etch resist
with acetone

PCB is ready.

my first attempt i was able to get nice looking traces as small
as .015" with .015" spacing and i think i could easily get .010"
or less.

hope you did not already know this ,
robb

 

[D from BC]

I'm about to embark on a prototyping project, and was thinking of
dead-bug, but from what I now of surface mount, dead-bug would
be ridiculous. So what I have in mind is to take a piece of single-sided
laminate (from the elec. store up the street), put it copper down,
which would be the ground plane, and on the top, glue the parts down
and literally draw the circuit.

So, does anyone have a good search phrase for google, or maybe
know off the top of your head where I might get some of the stuff?
Is that the sort of thing that general-purpose elec. stores (heat
shrink, NTE's, all the neat stuff that RS used to have) would
carry?

One caveat - this isn't a hobby project, I'm getting paid, so if
I should FOAD and STFW, please keep your reminders gentle.

Thanks,
Rich

ewwwww...conductive ink prototyping..
I've considered it, but won't try it...

My favorite is to do fast thinking layout and connections in CAD.
Autoroute..and human clean up.
I like the software error checking when I'm in a rush.

I still like homebrew photoresist boards and etch for fast prototypes.

(Small boards can be done in a rice cooker.)
D from BC

 

[James Arthur]

Hello Rich,

having just done the whole board fabrication stuff i can offer
this.

If you are near a fry's ? they sell a similar pen (CircuitWriter
by CAIG labs, silver/acetone/acrylic resin) can be soldered to
but it is difficult to control as one compresses the tip to
release the liquid. it seems to dry quickly and the pen gunks up
if you go backwards or over another not so dry trace.

The copper etching method is quite easy, alot easier than i
imagined. Since you are doing SMC (surface mount components) then
all the easier as the through hole drilling is the worst part

if you want a ground plane then Radio Shaft sells double sided
copper boards (probably super cheapo but it worked for me). just
spray paint the ground side completely with some ? acrylic/laquer
paint ? before etching

draw and print the PCB with a **laser printer** on magazine
paper, iron onto the cleaned copper board
, wash paper off, check for thin etch resist (fix with sharpie),
etch with (muriatic + %3 peroxide - 1:2), approx 4 minutes later
PCB is etched , remove and wash with water, remove etch resist
with acetone

PCB is ready.

my first attempt i was able to get nice looking traces as small
as .015" with .015" spacing and i think i could easily get .010"
or less.

hope you did not already know this ,
robb

Rich, count me with robb and Jeff--the silver ink pens' traces are
unsuitable: too wide and too delicate for surface mount stuff. I've
tried it.

For very simple boards you can use a resist pen; with this and a
needle you can make very fine features. Plan the layout on paper,
then place the parts on the copperclad. Draw in the traces, lifting
parts as needed to draw pads. You can easily define a fine wire going
through a small gap by painting crudely with the resist pen, then
scratching the fine details with the needle. Etch.

Or you can lay out the board as above, then route out isolation
channels with a Dremel and a broken [sic] remnant of a carbie pcb
drill bit.

Another choice is dead-bug. Splaying alternate smd pins in opposite
directions gives you plenty of access and space to access and solder
each pin.

Or, for a more professional job, use the toner transfer method.

HTH,
James Arthur

 

[Frnak McKenney]

I'm about to embark on a prototyping project, and was thinking of
dead-bug, but from what I now of surface mount, dead-bug would
be ridiculous. So what I have in mind is to take a piece of single-sided
laminate (from the elec. store up the street), put it copper down,
which would be the ground plane, and on the top, glue the parts down
and literally draw the circuit.

Rich,

I had to read this twice before I stopped assuming that you'd have a
problem with soldering to the newly-drawn traces.

You're not, though, are you? You're thinking about letting the
conductive ink flow onto the component's leads as if it _were_
solder... but without the usual concerns about "cold solder joints".

Wonder how one would go about laying down a non-conductive drawing
pattern on a phenlolic-like surface for those of us (<ahem!>) who
have trouble drawing straight lines?

Oh. You could use this approach to lay out a (working) circuit on
plastic... or glass... or lots of other things.

Thanks for the concept, Rich. I don't have an immediate application
for it, but if I ponder what you're pondering for a few months, I'm
sure I'll come up with one or two. <grin!>

Maybe a glass firefly jar whose inner surface is coated with SMT
LEDs? Maybe... (Sorry. Gotta get back to RealWork(tm). <grin>)


Frank

 

[[email protected]]

draw and print the PCB with a **laser printer** on magazine

Don't print on paper, print on the glossy backing used for stickers.
Toner just peels right off.

 

[James Arthur]

Don't print on paper, print on the glossy backing used for stickers.
Toner just peels right off.

Isn't that a problem--the toner falling off too easily? What brand of
backing did/have you used?

Cheers,
James Arthur

 

[robb]

Don't print on paper, print on the glossy backing used for stickers.
Toner just peels right off.

i have same issue as James.


you must be using something different as the stuff i used the
toner was knocked off coming out of the printer and i
experimented with lots of diff paper... label backing, gift wrap,
diff weights copy paper etc

even tried parchment which you can blow the fused toner off of

robb