Homebrew_PCBs

After trying lots of paper and making a few boards with magazine
paper, I found just the right paper and a good technique. I'm very
pleased with the results for both 1 and 2 sided boards. Up until
now, I was pretty dissapointed with the quality of what i was making -
lots of trace blooming and areas of poor resist adhesion.. I know
others have different techniques that work but this is getting darn
near fool proof for me.

The paper is general purpose good quality inkjet paper - less than $5
for 500. I use a canon personal copier to get toner onto the paper
and crank the darkness up quite a bit. The toner goes on thick, the
paper absorbs the excess toner nicely and I get very very little
blooming of my traces anymore.

Copper substrate prep is pretty standard except I use emery cloth at
220 grit to significanly increase the surface area to improve toner
bonding. I'm going to try something finer than that. wash, degrease
and dry in oven.

I put the iron on just a touch back from the hottest setting
(cotton). I also use children's construction paper between the iron
and the toner paper as a pad to even out the pressure which I apply
quite liberally. I iron both sides for a minute at what my bathroom
scale says is 30 lbs of pressure. Finally, I leave the iron on top
of the board/paper assembly and turn it off to let it cool down.
This is an important step as it keeps the melted toner in strong
contact with the copper substrate to ensure good bonding. Once cool
enough to handle, it goes into the water for a standard soak and
rub. The paper falls apart very quickly and the toner doesn't flake
off at all so I can scrub pretty hard.

Also, I am getting good results with legend printing (some times
called silk screen). I use the above technique with 2 changes.
First one is that after one minute of ironing, I use the edge of the
iron to "burnish" the toner paper into the board. This ensures good
contact of the hot toner to all surfaces including next to traces.
The second one is that I do a hot peel of the toner paper. Enough
toner stays on the board to be very legable but more importantly, no
soak-n-rub cycle and thus I can go right to drilling with no more
than a 5 minute delay.

some pix taken with a 10X microscope
http://www.geocities.com/phil1960us/pcb/

Phil

I wonder if the grit is the same in your country as in mine.
i think it is some "peaks per area" reading so i guess it is different
between
metric and imperial.

Does anyone know that?

I use 600 grit for the pcb prep.
this is very fine paper, the coarsest you get is 40,
60, 80 or 100 being used for common wood sanding.

> Copper substrate prep is pretty standard except I use emery cloth at
> 220 grit to significanly increase the surface area to improve toner
> bonding. I'm going to try something finer than that. wash, degrease
> and dry in oven.
>

Nice results, especially the legend.
But some pads could be bigger you know....

st

It sounds similar. For wood projects I use 100, then 180, then 220.
sometimes 320 for really fine stuff.

220 is a bit too coarse for substrate prep but its what I had. think
and tinker have a "cleanser/brightener" that I'm thinking of trying.

by the way, that posting took over 2 hours to show up. I thought it
had gotten lost somewhere and, of course, it was one of the few times
didn't save a copy.

Phil

--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
<stefan_trethan@g...> wrote:

> I wonder if the grit is the same in your country as in mine.
> i think it is some "peaks per area" reading so i guess it is

different

> between
> metric and imperial.
>
> Does anyone know that?
>
> I use 600 grit for the pcb prep.
> this is very fine paper, the coarsest you get is 40,
> 60, 80 or 100 being used for common wood sanding.
>
>
> > Copper substrate prep is pretty standard except I use emery cloth

at

> > 220 grit to significanly increase the surface area to improve

toner

> > bonding. I'm going to try something finer than that. wash,

degrease

> > and dry in oven.
> >
>
> Nice results, especially the legend.
> But some pads could be bigger you know....
>
> st

> I'm very pleased with the results for both 1 and 2 sided boards.

Hi. I'm trying to perfect my double-sided boards. How do you make
your double sided boards? Do you line them up, tape them together,
insert the board in between and iron them at the same time?

-Josh

yes, that is exactly how I do it. Alignment is critical. some
things I've found that help:

I use full 8.5x11 sheets for each side - it makes it easier. Since
my paper costs me a penny a sheet I dont care if I waste a little.

It helps to have a tracing light box and a Scotch (I think) double
sided tape applicator. The paper I use is fairly translucent. I use
an old slide sorter for the light box. Its a pain to use but allows
pretty accurate alignment. A window on a sunny day does pretty well,
too. Temp tape the bottom paper to the glass and tweak the top until
you are there. Holding the two pieces of paper up to a lightbulb can
work but its much harder (for me anyway). I like to have a flat
surface to work on. a light box is pretty easy to build, by the way -
I plan on doing so, someday (hah, FLW).

The tape applicator allows one handed application of the double sided
tape so once you have your alignment, a quick swipe and you've got
your tape in place.

I try to tape as far away from the board image as possible to
minimize the effect of differential paper lengths from the tape to
the board.

vias make great registration points - if I can see light through the
hole, I know I'm pretty close. pay close attention vert and horiz
alignment. The good news is that you can be up 10 mils off and still
have a usable board.

I start ironing in the middle of the board as that is the best chance
of evening out the distortion caused by the differential paper
lengths.

Once I started using the ink jet paper, it took me about 4 tries to
finally get it. I bought a bunch of cheap, thin double sided boards
from goldmine and practiced. dont be afraid to wash off the toner
and start again. acetone strips toner almost instantly.

One final point. Its often the case that if you tweak your design
around a bit, you can get to a single sided board. this is always
more desirable than double. at least from a simplifying production
basis. I'll often change pin assignments on my MCUs to reduce
complexity. pin-swap is a good thing too.

Good luck.

Phil

--- In Homebrew_PCBs@yahoogroups.com, "joshdewinter"
<joshdewinter@y...> wrote:

> > I'm very pleased with the results for both 1 and 2 sided boards.
>
> Hi. I'm trying to perfect my double-sided boards. How do you make
> your double sided boards? Do you line them up, tape them together,
> insert the board in between and iron them at the same time?
>
> -Josh

Phil,

Thank you for a really detailed useful post!

One question: Do you worry about the conductivity of the
toner "screen print"? Seems that it could be an issue...

Ballendo

--- In Homebrew_PCBs@yahoogroups.com, "Phil" <phil1960us@y...> wrote:
> After trying lots of paper and making a few boards with magazine
> paper, I found just the right paper and a good technique. I'm very
> pleased with the results for both 1 and 2 sided boards. Up until
> now, I was pretty dissapointed with the quality of what i was
making -
> lots of trace blooming and areas of poor resist adhesion.. I know
> others have different techniques that work but this is getting darn
> near fool proof for me.
>
> The paper is general purpose good quality inkjet paper - less than
$5
> for 500. I use a canon personal copier to get toner onto the paper
> and crank the darkness up quite a bit. The toner goes on thick,
the
> paper absorbs the excess toner nicely and I get very very little
> blooming of my traces anymore.
>
> Copper substrate prep is pretty standard except I use emery cloth
at
> 220 grit to significanly increase the surface area to improve toner
> bonding. I'm going to try something finer than that. wash, degrease
> and dry in oven.
>
> I put the iron on just a touch back from the hottest setting
> (cotton). I also use children's construction paper between the
iron
> and the toner paper as a pad to even out the pressure which I apply
> quite liberally. I iron both sides for a minute at what my
bathroom
> scale says is 30 lbs of pressure. Finally, I leave the iron on top
> of the board/paper assembly and turn it off to let it cool down.
> This is an important step as it keeps the melted toner in strong
> contact with the copper substrate to ensure good bonding. Once
cool
> enough to handle, it goes into the water for a standard soak and
> rub. The paper falls apart very quickly and the toner doesn't
flake
> off at all so I can scrub pretty hard.
>
> Also, I am getting good results with legend printing (some times
> called silk screen). I use the above technique with 2 changes.
> First one is that after one minute of ironing, I use the edge of
the
> iron to "burnish" the toner paper into the board. This ensures
good
> contact of the hot toner to all surfaces including next to traces.
> The second one is that I do a hot peel of the toner paper. Enough
> toner stays on the board to be very legable but more importantly,
no
> soak-n-rub cycle and thus I can go right to drilling with no more
> than a 5 minute delay.
>
> some pix taken with a 10X microscope
> http://www.geocities.com/phil1960us/pcb/
>
> Phil

Interesting question. I think its pretty much an insulator since it
gets picked up via static electricity prior to fusing. I think a
conductor would have problems. but I just tried a quick test with
my multimeter and got nothing. maybe its an issue but i haven't seen
any problems, yet.

--- In Homebrew_PCBs@yahoogroups.com, "ballendo" <ballendo@y...>
wrote:

> Phil,
>
> Thank you for a really detailed useful post!
>
> One question: Do you worry about the conductivity of the
> toner "screen print"? Seems that it could be an issue...
>
> Ballendo
>
> --- In Homebrew_PCBs@yahoogroups.com, "Phil" <phil1960us@y...>

wrote:

> > After trying lots of paper and making a few boards with magazine
> > paper, I found just the right paper and a good technique. I'm

very

> > pleased with the results for both 1 and 2 sided boards. Up until
> > now, I was pretty dissapointed with the quality of what i was
> making -
> > lots of trace blooming and areas of poor resist adhesion.. I

know

> > others have different techniques that work but this is getting

darn

> > near fool proof for me.
> >
> > The paper is general purpose good quality inkjet paper - less

than

> $5
> > for 500. I use a canon personal copier to get toner onto the

paper

> > and crank the darkness up quite a bit. The toner goes on thick,
> the
> > paper absorbs the excess toner nicely and I get very very little
> > blooming of my traces anymore.
> >
> > Copper substrate prep is pretty standard except I use emery cloth
> at
> > 220 grit to significanly increase the surface area to improve

toner

> > bonding. I'm going to try something finer than that. wash,

degrease

> > and dry in oven.
> >
> > I put the iron on just a touch back from the hottest setting
> > (cotton). I also use children's construction paper between the
> iron
> > and the toner paper as a pad to even out the pressure which I

apply

> > quite liberally. I iron both sides for a minute at what my
> bathroom
> > scale says is 30 lbs of pressure. Finally, I leave the iron on

top

> > of the board/paper assembly and turn it off to let it cool down.
> > This is an important step as it keeps the melted toner in strong
> > contact with the copper substrate to ensure good bonding. Once
> cool
> > enough to handle, it goes into the water for a standard soak and
> > rub. The paper falls apart very quickly and the toner doesn't
> flake
> > off at all so I can scrub pretty hard.
> >
> > Also, I am getting good results with legend printing (some times
> > called silk screen). I use the above technique with 2 changes.
> > First one is that after one minute of ironing, I use the edge of
> the
> > iron to "burnish" the toner paper into the board. This ensures
> good
> > contact of the hot toner to all surfaces including next to

traces.

> > The second one is that I do a hot peel of the toner paper.

Enough

> > toner stays on the board to be very legable but more importantly,
> no
> > soak-n-rub cycle and thus I can go right to drilling with no more
> > than a 5 minute delay.
> >
> > some pix taken with a 10X microscope
> > http://www.geocities.com/phil1960us/pcb/
> >
> > Phil

On Fri, 19 Mar 2004 09:47:10 -0000, Phil <phil1960us@...> wrote:

> Interesting question. I think its pretty much an insulator since it
> gets picked up via static electricity prior to fusing. I think a
> conductor would have problems. but I just tried a quick test with
> my multimeter and got nothing. maybe its an issue but i haven't seen
> any problems, yet.
>

You can repair potentiometers with ironing on toner.
i would not put it on if i have top-level copper.

I actually thought about trying to "print on" resistors but did not try
yet...
Might work for very low requirements stuff like pullups/dns..

Might not be all toner that is conductive.
I read it at sam's repair faq i think.

ST

It is carbon in a plastic that melts to hold it in place. So in a high
impedance or high voltage circuit, it can cause problems, but for most
circuits it would likely not cause any problems.

And then you can just be careful not to have printing in those parts
of the circuit.

Steve

--- In Homebrew_PCBs@yahoogroups.com, "Phil" <phil1960us@y...> wrote:
> Interesting question. I think its pretty much an insulator since it
> gets picked up via static electricity prior to fusing. I think a
> conductor would have problems. but I just tried a quick test with
> my multimeter and got nothing. maybe its an issue but i haven't seen
> any problems, yet.

Hello,

Yes, that's why I asked. I used to repair copiers, and that toner was
definitely conductive.

Ballendo


--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
<stefan_trethan@g...> wrote:

> On Fri, 19 Mar 2004 09:47:10 -0000, Phil <phil1960us@y...> wrote:
>
> > Interesting question. I think its pretty much an insulator since

it

> > gets picked up via static electricity prior to fusing. I think a
> > conductor would have problems. but I just tried a quick test

with

> > my multimeter and got nothing. maybe its an issue but i haven't

seen

> > any problems, yet.
> >
>
> You can repair potentiometers with ironing on toner.
> i would not put it on if i have top-level copper.
>
> I actually thought about trying to "print on" resistors but did not

try

> yet...
> Might work for very low requirements stuff like pullups/dns..
>
> Might not be all toner that is conductive.
> I read it at sam's repair faq i think.
>
> ST

On Sat, 20 Mar 2004 16:52:21 -0000, ballendo <ballendo@...> wrote:

> Hello,
>
> Yes, that's why I asked. I used to repair copiers, and that toner was
> definitely conductive.
>
> Ballendo

My meter shows nothing on a normal transferred line.
some day i will put a bit of toner on paper and iron it to get
a thicker layer.


A line with a pencil is definitely much more conductive.

ST

--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
<stefan_trethan@g...> wrote:

> On Sat, 20 Mar 2004 16:52:21 -0000, ballendo <ballendo@y...> wrote:
>
> > Hello,
> >
> > Yes, that's why I asked. I used to repair copiers, and that toner was
> > definitely conductive.
> >
> > Ballendo
>
>
> My meter shows nothing on a normal transferred line.
> some day i will put a bit of toner on paper and iron it to get
> a thicker layer.

Yes, but try the same thing with an antistatic bag or antistatic IC
carrier tube. They won't show on your meter, either, but they are in
fact slightly conductive.

Steve

> Yes, but try the same thing with an antistatic bag or antistatic IC
> carrier tube. They won't show on your meter, either, but they are in
> fact slightly conductive.
>
> Steve
>
>

I know, i just wanted to say it doesn't matter for some circuits...

there is no "conductive" and "not conductive" it's just a matter
of moving electrons, right?

ST