diagnosing toner transfer problems

[DJ Delorie]

Ok, this is an old blank (I've had it since I was a teenager) and the
"special paper" is a few years old too. Lots of reasons why it could
have gone wrong, but if it's something in my technique, I'd like to
benefit from someone else's experience

low res: http://www.delorie.com/pcb/pcb-sm.html (88k jpeg)
high res: http://www.delorie.com/pcb/pcb.html (1.5M jpeg)

The board was sanded to 600 grit (yes, it was that oxidized) then
cleaned with dish soap and dried by paper towel then laying it on an
inverted iron for a few seconds to evaporate any remaining water. I
ironed at the cotton/linen setting for about a minute, moving the iron
around to avoid cold spots. The paper came off just fine in the
water.

The sections where the toner just peeled off are obvious; not enough
heat. However, I'm mostly wondering about the smudged parts, like the
board just above and left of center. Too much heat? Too much iron
motion? Some parts came out very crisp (like most of the board just
below it) so it *should* work OK if I can "tune it in".

DJ

 

[scada]

Ok, this is an old blank (I've had it since I was a teenager) and the
"special paper" is a few years old too. Lots of reasons why it could
have gone wrong, but if it's something in my technique, I'd like to
benefit from someone else's experience

low res: http://www.delorie.com/pcb/pcb-sm.html (88k jpeg)
high res: http://www.delorie.com/pcb/pcb.html (1.5M jpeg)

The board was sanded to 600 grit (yes, it was that oxidized) then
cleaned with dish soap and dried by paper towel then laying it on an
inverted iron for a few seconds to evaporate any remaining water. I
ironed at the cotton/linen setting for about a minute, moving the iron
around to avoid cold spots. The paper came off just fine in the
water.

The sections where the toner just peeled off are obvious; not enough
heat. However, I'm mostly wondering about the smudged parts, like the
board just above and left of center. Too much heat? Too much iron
motion? Some parts came out very crisp (like most of the board just
below it) so it *should* work OK if I can "tune it in".

DJ

I don't think you got it clean enough. I usualy use some #0000 steel wool to
polish. Also handle the cleaned board by it's edges, oils from your finger
prints can contaminate the board. I think you need to iron for a longer time
also, I seem to remember about 3-4 minutes.

 

[James Thompson]

Ok, this is an old blank (I've had it since I was a teenager) and the
"special paper" is a few years old too. Lots of reasons why it could
have gone wrong, but if it's something in my technique, I'd like to
benefit from someone else's experience

low res: http://www.delorie.com/pcb/pcb-sm.html (88k jpeg)
high res: http://www.delorie.com/pcb/pcb.html (1.5M jpeg)

The board was sanded to 600 grit (yes, it was that oxidized) then
cleaned with dish soap and dried by paper towel then laying it on an
inverted iron for a few seconds to evaporate any remaining water. I
ironed at the cotton/linen setting for about a minute, moving the iron
around to avoid cold spots. The paper came off just fine in the
water.

The sections where the toner just peeled off are obvious; not enough
heat. However, I'm mostly wondering about the smudged parts, like the
board just above and left of center. Too much heat? Too much iron
motion? Some parts came out very crisp (like most of the board just
below it) so it *should* work OK if I can "tune it in".

DJ

Well, looks to me you pressed too hard. Use a light hand and longer heating
time. gently smooth the paper over the board after it is very hot. All you
want to due is make sure it is tacked down to the pcb, and not smashed onto
it. Remember, it's not the pressure that attaches the toner - its the heat.
Get some Emory cloth or wet/dry sanding paper as fine as you can get it.
Then clean it with soap n water and dry with an old undershirt, not paper.
Maybe even use a hair blow dryer on it. Any contaminant on the copper will
make your traces not stick. JTT

 

[Tim Auton]

Ok, this is an old blank (I've had it since I was a teenager) and the
"special paper" is a few years old too. Lots of reasons why it could
have gone wrong, but if it's something in my technique, I'd like to
benefit from someone else's experience [snip]
The sections where the toner just peeled off are obvious; not enough
heat. However, I'm mostly wondering about the smudged parts, like the
board just above and left of center. Too much heat? Too much iron
motion? Some parts came out very crisp (like most of the board just
below it) so it *should* work OK if I can "tune it in".

It looks like there has been a lot of pressure in small areas, which has
made the toner spread out. Try to avoid any temptation to use the tip or
an edge of the iron to get more pressure - you just end up spreading the
toner around. I've found more time and heat are much more effective than
more pressure.

Try ironing for longer, with modest pressure using only the flat of the
iron. 5 minutes or more is not unusual for me.


Tim

 

[Mike]

There are 3 major factors that you have to get right for it work.

1- Cleanliness
2- Correct temperature
3 - correct and even pressure

Here's how I do the cleaning..
I do a light sanding if it's badly oxidized then follow that up with a good
scrubbing using an SOS pad. The steel type with the soap in it. It comes out
nice and shiny. Try not to touch the copper at this point to keep oil from your
fingers from contaminating it. Next rinse it really well in very hot water to
remove all the soap residue and finally wipe it with alcohol.

The correct temperature depends entirely on the toner. Not all toners are
created equal. The toner is basically powdered plastic with some other junk
mixed in and has to be heated to just the right temperature. For my printer
350deg is just right. If the temperature is too low if won't get soft enough to
transfer. If it's too hot it will it be too liquid and tend to run together.
Unfortunately temperature can only be determined by trial and error. It's also
important to get an even temperature across the entire surface of the board.
Large boards (bigger than the footprint of the iron) are harder to heat evenly.
Warped boards also present a problem here. Depending on how the board was cut to
size. There could be a slight ridge around the edges which will prevent the iron
from contacting the copper towards the edges. I cut the boards a little large
and trim down to size after etching. I use a radial arm saw with an 80 tooth
carbide tipped blade and cut with the copper side up. IMPORTANT: wear a
breathing mask! You don't want to be breathing fiberglass dust.

It is important to exert a firm and even pressure on the iron in order to assure
even heating and to force the toner into all the microscopic crevasses in the
board. This is probably the least critical factor, but still important.

Sorry, but your board looks like you had problems with all three factors.
Probably not clean enough and uneven heating mostly.
I was making lots of boards for awhile and solved the temperature and pressure
problems by buying a T-Shirt heat press that has adjustable temperature and
pressure. It works great, but was kinda pricey.

If you have problems with pitting in solid copper areas you might try burnishing
the board after you remove the paper. You can do that by placing a clean sheet
of paper over the board and reheating it with the iron. There is also some stuff
called GreenTRF (Digi-Key P/N 182-1021-ND) that will seal the toner on the board
and prevent pitting and etching under the edges. You would just use it instead
of the paper in the burnishing step.

Mike


"The scientist is possessed by the sense of universal
causation...His religious feeling takes the form of
rapturous amazement at the harmony of natural law,
which reveals the intelligence of such superiority
that, compared with it, systematic thinking and acting
of human beings is an utterly insignificant reflection."
Albert Einstein (theoretical physicist)

 

[JeffM]

low res: http://www.delorie.com/pcb/pcb-sm.html (88k jpeg)

high res: http://www.delorie.com/pcb/pcb.html (1.5M jpeg)
. . .
The sections where the toner just peeled off are obvious;
not enough heat.
However, I'm mostly wondering about the smudged parts,
like the board just above and left of center.
Too much heat? Too much iron motion?
DJ Delorie

Folks have already mentioned dwell time (don't get in a hurry)
and pressure (use caution).
Here's an old thread with some more ideas:
http://groups.google.com/group/sci....hness-*-improves-adhesion+pink.haze+oxidation

 

[[email protected]]

Ok, this is an old blank (I've had it since I was a teenager) and the
"special paper" is a few years old too. Lots of reasons why it could
have gone wrong, but if it's something in my technique, I'd like to
benefit from someone else's experience

low res: http://www.delorie.com/pcb/pcb-sm.html (88k jpeg)
high res: http://www.delorie.com/pcb/pcb.html (1.5M jpeg)

The board was sanded to 600 grit (yes, it was that oxidized) then
cleaned with dish soap and dried by paper towel then laying it on an
inverted iron for a few seconds to evaporate any remaining water. I
ironed at the cotton/linen setting for about a minute, moving the iron
around to avoid cold spots. The paper came off just fine in the
water.

The sections where the toner just peeled off are obvious; not enough
heat. However, I'm mostly wondering about the smudged parts, like the
board just above and left of center. Too much heat? Too much iron
motion? Some parts came out very crisp (like most of the board just
below it) so it *should* work OK if I can "tune it in".

DJ

Your adhesion generally looks pretty good to me. Non-adherent areas
are ones you didn't iron. Smearing--your greatest problem--comes from
excessive massaging with the iron, though it might also result from
movement of the paper.

My technique is to bring the board to temperature with the iron, then
rub the iron on the board to effect the transfer. I also have a 2nd
chance: as I soak the board, my paper comes off in layers. Leaving a
thin layer of paper, I dry with the iron, which reveals non-adherent
areas as raised white areas. After re-ironing, they're fine, and I
proceed with soaking.

I manage 12/12/12 without difficulty, 8/8/8 with touch-ups.

HTH,
James Arthur

 

[samiam]

Ok, this is an old blank (I've had it since I was a teenager) and the

You really have to clean the board. I mean some serious scrubbing in
circular motion until its a dull shine.

I go at it with gloves on and soap and steel wool. then isoprophl
alcohol and steel wool.

Then dry with paper towel.
I use the blue PNP paper and I get 100% registration (15 mil traces and
faily populated 8x8 sized boards)

I iron it with pressure until the paper sticks to the board. Then I iron
as if I were irons cloths ... every 30 seconds Ill stop, examine the
board and switch to a different side

Afterwards I let is sit on a wooden plank and place a heavy flat object
(paper weight) on top of it for a few minutes

 

[ehsjr]

Ok, this is an old blank (I've had it since I was a teenager) and the
"special paper" is a few years old too. Lots of reasons why it could
have gone wrong, but if it's something in my technique, I'd like to
benefit from someone else's experience

low res: http://www.delorie.com/pcb/pcb-sm.html (88k jpeg)
high res: http://www.delorie.com/pcb/pcb.html (1.5M jpeg)

The board was sanded to 600 grit (yes, it was that oxidized) then
cleaned with dish soap and dried by paper towel then laying it on an
inverted iron for a few seconds to evaporate any remaining water. I
ironed at the cotton/linen setting for about a minute, moving the iron
around to avoid cold spots. The paper came off just fine in the
water.

The sections where the toner just peeled off are obvious; not enough
heat. However, I'm mostly wondering about the smudged parts, like the
board just above and left of center. Too much heat? Too much iron
motion? Some parts came out very crisp (like most of the board just
below it) so it *should* work OK if I can "tune it in".

DJ

What others have said, and ...
I don't iron it with it directly on a padded ironing
board. I use a piece of plywood under the PC board -
that helps to keep the pressure even across the surface.

Ed

 

[DJ Delorie]

I'd like to thank everyone who replied to my query. It took most of
the day, but I managed to get a board that worked "well enough". This
is after a half dozen failed attempts, two dozen science experiments
to calibrate the iron, and two more attempts, the second of which was
the first to actually work. Or at least, mostly work, but I got most
of the boards on the panel (6 each of the important ones, three look
usable) to come out "clean".

What was my problem? A combination of too much heat and inconsistent
pressure. That's why I was having lifted toner *and* blurry toner in
the same board. The solution? It seems to be a combination of these
key points:

* Iron at maximum temperature.

* Pre-heat the board (I just sat the iron on it for 45 seconds)

* Medium pressure.

* Pass the iron from left to right, as if it were a laminator roller.
I put a full sheet of paper over the stack, held one edge firmly,
and moved the iron away from that edge to keep it from moving the
toner paper. Two or three passes seems to be sufficient.

* *Immediately* move the board to water, so that the paper lets go of
the toner before it expands due to the cold and rips the toner off.

I also baked the board after removing the paper, just to make sure the
toner was stuck. I'm not sure there's any advantage in that. A few
minutes at 350 seemed best, and again, right into the water to cool
the toner before anything bad can happen to it.

Then, the usual 20 minute agitated FeCl bath. Also, goof-off removes
the toner MUCH faster than acetone-based nail polish remover.

Final results:

low res: http://www.delorie.com/pcb/pcb-sm.html (130k jpeg)
high res: http://www.delorie.com/pcb/pcb.html (1.2M jpeg)

A few lost traces here and there, but I only need one of each board
for my immediate needs.

On the topmost six boards, I included some "test traces" to see how
small traces worked. On the left of each board, from the top,
they're: 7, 6, 5, 4, 10, and 8 mil lines with same-sized space (looks
like 7 mil is my limit). The annuli on the right range from 12 mil
down to 5.75 mil on a 13.5 mil drill. The smaller of the two ICs is a
TVSOP-14, which is 0.2 mm (~8 mil) line/space. The smallest feature
is the 01005 footprint, which is the 6 mil gap in the trace off pin 9
of that chip.

Thanks!
DJ

 

[DJ Delorie]

what kind of paper did you use?

Pulsar's transfer paper. The printed image is nice and crisp, and
when you drop the board in water the paper just falls off after a
minute or so when the last bit lets go. It's coated with a heat-proof
yet quickly-water-soluble layer. When you take it out of the water,
that side of the wet paper is very slippery.

I've never tried other papers, but I did use laser transparencies for
my science experiments so I could examine the state of the toner
before peeling it off to test adhesion. The toner didn't want to let
go of that (duh).

What I did was print the board on regular paper, then cut out a piece
of transfer paper just big enough for the board, taped it to the
regular paper in the right spot (using Avery laser lables for tape),
and printed again. My printer reprints within 0.1" or so (worst
case), so I leave that much margin. I haven't missed yet.

The paper was trimmed to the same size as the pcb, maybe a tiny bit
smaller, before ironing it. A thought: I might tape over the exposed
borders next time I do this, so I don't waste time or etchant etching
them.

 

[Jamie]

I'd like to thank everyone who replied to my query. It took most of
the day, but I managed to get a board that worked "well enough". This
is after a half dozen failed attempts, two dozen science experiments
to calibrate the iron, and two more attempts, the second of which was
the first to actually work. Or at least, mostly work, but I got most
of the boards on the panel (6 each of the important ones, three look
usable) to come out "clean".

What was my problem? A combination of too much heat and inconsistent
pressure. That's why I was having lifted toner *and* blurry toner in
the same board. The solution? It seems to be a combination of these
key points:

* Iron at maximum temperature.

* Pre-heat the board (I just sat the iron on it for 45 seconds)

* Medium pressure.

* Pass the iron from left to right, as if it were a laminator roller.
I put a full sheet of paper over the stack, held one edge firmly,
and moved the iron away from that edge to keep it from moving the
toner paper. Two or three passes seems to be sufficient.

* *Immediately* move the board to water, so that the paper lets go of
the toner before it expands due to the cold and rips the toner off.

I also baked the board after removing the paper, just to make sure the
toner was stuck. I'm not sure there's any advantage in that. A few
minutes at 350 seemed best, and again, right into the water to cool
the toner before anything bad can happen to it.

Then, the usual 20 minute agitated FeCl bath. Also, goof-off removes
the toner MUCH faster than acetone-based nail polish remover.

Final results:

low res: http://www.delorie.com/pcb/pcb-sm.html (130k jpeg)
high res: http://www.delorie.com/pcb/pcb.html (1.2M jpeg)

A few lost traces here and there, but I only need one of each board
for my immediate needs.

On the topmost six boards, I included some "test traces" to see how
small traces worked. On the left of each board, from the top,
they're: 7, 6, 5, 4, 10, and 8 mil lines with same-sized space (looks
like 7 mil is my limit). The annuli on the right range from 12 mil
down to 5.75 mil on a 13.5 mil drill. The smaller of the two ICs is a
TVSOP-14, which is 0.2 mm (~8 mil) line/space. The smallest feature
is the 01005 footprint, which is the 6 mil gap in the trace off pin 9
of that chip.

Thanks!
DJ

what kind of paper did you use?
i use magazine (glossy) paper or ink jet photo paper (glossy)..
the ink jet paper washes away with water nicely.

 

[Jim]

What was my problem? A combination of too much heat and inconsistent
pressure. That's why I was having lifted toner *and* blurry toner in
the same board. The solution? It seems to be a combination of these
key points:

* Iron at maximum temperature.

* Pre-heat the board (I just sat the iron on it for 45 seconds)

* Medium pressure.

I ran across a website that recommends using a laminator, the kind that
laminates protective plastic onto photographs.

The major drawback I see is that the board thickness is limited to .030
boards, but that's a minor consideration for most circuit designs.

The nice part is, this approach simplifies doing doublesided boards. The
lineup of the paper has to be done carfully, but this system heats and
presses both sides at the same time.


http://www.pulsar.gs/PCB/a_Pages/4_Products/4d_Toner_Applicator/Toner_Applicator.html




I checked at my local Staples store, and I find the same laminator on the
shelf, Price about $60.00


Jim Pennell



--

13:05 Pacific Time Zone
Sep 10 2006

International Time
20:05 UTC
10.09.2006

 

[DJ Delorie]

I ran across a website that recommends using a laminator, the kind that
laminates protective plastic onto photographs.

I got the idea from that.

http://www.pulsar.gs/PCB/a_Pages/4_Products/4d_Toner_Applicator/Toner_Applicator.html

Actually, I'm low on consumables anyway, so I ordered their starter
kit (without goof-off) which gets me the laminator and the thinner
boards. I'll use the remaining thick boards for boards with larger
traces.

Bonus pic: the boards I made yesterday have a HAND SOLDERED 01005
capacitor on them now! http://www.delorie.com/pcb/first.html

Now, if we just had an elegant solution for plated-through vias...