Homebrew PCBs

For anyone interested, there is absolutely no reason that laser 
printers cannot directly deposit toner on pcb boards. The practical 
problems are the fuser and the paper path. As a proof of concept, I 
took a Brother HL2140 laser printer that has a manual feed for 
thicker media and fed a sheet of thin (8 mil) laminate through the 
printer. Nothing printed.

I then removed the fuser, using appropriate resistors to simulate the 
correct fuser temperature and thereby fool the printer controller 
into thinking the fuser was still there. I ran the same test, and 
sure enough, it printed perfectly! Of course, the toner was only held 
to the board by electrostatic attraction, but I then put the board 
into my trusty toaster oven and "fused" it.

There are other practical problems, but these can be overcome with a 
little bit of work. A small mcu will be needed to simulate some of 
the feed sensors and the paper path will have to be changed, but my 
experiments show that these are (relatively) easily done.

I have used a datalogger to check the function of the three main 
sensors - paper feed, start print (rear register) and eject - and can 
simulate all of these and I have actually run the printer using an 
mcu instead of the sensors. However, the real problem is that the 
machine is not rugged enough to handle a lot of manipulation - the 
connectors break down easily and you end up with error lights that 
you have no idea how to fix, a tiny slip that causes a momentary 
short will sometimes blow a board, etc.

If anyone is interested in more details, I am happy to share.

Mark

As an addendum, it will also print on a sheet of thin aluminum. I 
just ran a piece of  10 mil aluminum flashing through the printer - 
it printed, but the lines were a bit wavy, probably due to the coarse 
surface of this aluminum.
Mark

At 08:30 AM 3/14/2009, you wrote:

>For anyone interested, there is absolutely no reason that laser
>printers cannot directly deposit toner on pcb boards. The practical
>problems are the fuser and the paper path. As a proof of concept, I
>took a Brother HL2140 laser printer that has a manual feed for
>thicker media and fed a sheet of thin (8 mil) laminate through the
>printer. Nothing printed.
>
>I then removed the fuser, using appropriate resistors to simulate the
>correct fuser temperature and thereby fool the printer controller
>into thinking the fuser was still there. I ran the same test, and
>sure enough, it printed perfectly! Of course, the toner was only held
>to the board by electrostatic attraction, but I then put the board
>into my trusty toaster oven and "fused" it.
>
>There are other practical problems, but these can be overcome with a
>little bit of work. A small mcu will be needed to simulate some of
>the feed sensors and the paper path will have to be changed, but my
>experiments show that these are (relatively) easily done.
>
>I have used a datalogger to check the function of the three main
>sensors - paper feed, start print (rear register) and eject - and can
>simulate all of these and I have actually run the printer using an
>mcu instead of the sensors. However, the real problem is that the
>machine is not rugged enough to handle a lot of manipulation - the
>connectors break down easily and you end up with error lights that
>you have no idea how to fix, a tiny slip that causes a momentary
>short will sometimes blow a board, etc.
>
>If anyone is interested in more details, I am happy to share.
>
>Mark
>
>
>
>------------------------------------
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>

Absolutely none is a strong statement.
I would say there is a number of good reasons why it does not work.

The toner is transferred from the drum to the paper via an
electrostatic charge delivered by the corona wire. A metallic PCB
shorts this charge, making the transfer efficiency ~50% (pure chance)
which is usually not enought to work as resist.

The drum is coated with a very delicate photoconductor. This layer is
easily damaged by board edges, metal burrs, accidents of any kind.

The only approach that sounded promising to me was presented by
someone who is no longer a member here. It involved installing a
silicone rubber coated drum right under the photo drum (in contact
with it). Below the silicone drum a heated PCB would pick up the
toner. This transfer drum would solve both problems.


Don't get me wrong i'm very supportive of any efforts towards direct
laser printing, i think it would be very neat. But you have not yet
identified all the problems.

ST

On Sat, Mar 14, 2009 at 1:30 PM, Mark Lerman <mlerman@...> wrote:
> For anyone interested, there is absolutely no reason that laser
> printers cannot directly deposit toner on pcb boards.

I'm not sure about the charge problem, but the way I planned to 
handle the drum was with soft plastic on the leading edge of the 
board and by beveling and smoothing the other edges. If the board is 
smooth, it shouldn't damage the drum. However, I take back my 
"absolutely" and will let you all know how things go.

Mark

At 10:24 AM 3/14/2009, you wrote:

>Absolutely none is a strong statement.
>I would say there is a number of good reasons why it does not work.
>
>The toner is transferred from the drum to the paper via an
>electrostatic charge delivered by the corona wire. A metallic PCB
>shorts this charge, making the transfer efficiency ~50% (pure chance)
>which is usually not enought to work as resist.
>
>The drum is coated with a very delicate photoconductor. This layer is
>easily damaged by board edges, metal burrs, accidents of any kind.
>
>The only approach that sounded promising to me was presented by
>someone who is no longer a member here. It involved installing a
>silicone rubber coated drum right under the photo drum (in contact
>with it). Below the silicone drum a heated PCB would pick up the
>toner. This transfer drum would solve both problems.
>
>
>Don't get me wrong i'm very supportive of any efforts towards direct
>laser printing, i think it would be very neat. But you have not yet
>identified all the problems.
>
>ST
>
>On Sat, Mar 14, 2009 at 1:30 PM, Mark Lerman <mlerman@...> wrote:
> > For anyone interested, there is absolutely no reason that laser
> > printers cannot directly deposit toner on pcb boards.
>
>
>------------------------------------
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>

Check out www.laserpcb.com

We make copper foils laminated to kapton that you can put through an unmodified laser printer and directly deposit the toner onto the copper.  The laminate has a pressure-sensitive adhesive to allow you to stick it to the supplied FR4 board before etching.

Dave


--- In Homebrew_PCBs@yahoogroups.com, Mark Lerman <mlerman@...> wrote:

>
> For anyone interested, there is absolutely no reason that laser 
> printers cannot directly deposit toner on pcb boards. The practical 
> problems are the fuser and the paper path. As a proof of concept, I 
> took a Brother HL2140 laser printer that has a manual feed for 
> thicker media and fed a sheet of thin (8 mil) laminate through the 
> printer. Nothing printed.
> 
> I then removed the fuser, using appropriate resistors to simulate the 
> correct fuser temperature and thereby fool the printer controller 
> into thinking the fuser was still there. I ran the same test, and 
> sure enough, it printed perfectly! Of course, the toner was only held 
> to the board by electrostatic attraction, but I then put the board 
> into my trusty toaster oven and "fused" it.
> 
> There are other practical problems, but these can be overcome with a 
> little bit of work. A small mcu will be needed to simulate some of 
> the feed sensors and the paper path will have to be changed, but my 
> experiments show that these are (relatively) easily done.
> 
> I have used a datalogger to check the function of the three main 
> sensors - paper feed, start print (rear register) and eject - and can 
> simulate all of these and I have actually run the printer using an 
> mcu instead of the sensors. However, the real problem is that the 
> machine is not rugged enough to handle a lot of manipulation - the 
> connectors break down easily and you end up with error lights that 
> you have no idea how to fix, a tiny slip that causes a momentary 
> short will sometimes blow a board, etc.
> 
> If anyone is interested in more details, I am happy to share.
> 
> Mark
>

--- In Homebrew_PCBs@yahoogroups.com, Mark Lerman <mlerman@...> wrote:
>
> For anyone interested, there is absolutely no reason that laser 
> printers cannot directly deposit toner on pcb boards. The practical 
> problems are the fuser and the paper path. As a proof of concept, I 
> took a Brother HL2140 laser printer that has a manual feed for 
> thicker media and fed a sheet of thin (8 mil) laminate through the 
> printer. Nothing printed.

I'm not sure I understand why nothing printed here...


> I then removed the fuser, using appropriate resistors to simulate the 
> correct fuser temperature and thereby fool the printer controller 
> into thinking the fuser was still there. I ran the same test, and 
> sure enough, it printed perfectly! Of course, the toner was only held 
> to the board by electrostatic attraction, but I then put the board 
> into my trusty toaster oven and "fused" it.
> 

That is very interesting... Why did removing the fuser cause it to print? 

<SNIP>

> If anyone is interested in more details, I am happy to share.
> 
> Mark
>


I would be VERY interested in pictures, and descriptions of the modifications you made.

--
James Newton
http://techref.massmind.org/techref/pcbs.htm

I think the fuser scraped the toner off because the board couldn't heat fast enough to fuse it. I've destroyed a couple of printers doing these tests but I think I understand what has to be done to make it work. Stefan has suggested that the charge on the board may be insufficient to attract enough toner to act as a resist, but visually it looks okay to me. I have to add a small mcu to simulate some of the printer's functions to test this further, but I plan to do some printing and etching tests next week. If necessary, I could either tweak the paper charge voltage a bit or add an external high voltage power supply, But I'm not at all sure it will be necessary. I also think the drum is somewhat tougher than Stefan thinks it is, and in any case it is easily replaceable if it gets damaged. An external smooth carrier might be necessary to mitigate this problem, but I think it is doable.

I should also add that the toner seems very well adhered to the board as it comes out of the printer. I can turn the board over and even blow on it without disturbing the toner. Once it is "cooked" in the oven, it seems very hard, though I have not etched a board yet. 

Mark

-----Original Message-----

>From: James Newton <jamesmichaelnewton@...>
>Sent: Mar 14, 2009 9:11 PM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: [Homebrew_PCBs] Re: Direct Laser PCB's (not TT)
>
>--- In Homebrew_PCBs@yahoogroups.com, Mark Lerman <mlerman@...> wrote:
>>
>> For anyone interested, there is absolutely no reason that laser 
>> printers cannot directly deposit toner on pcb boards. The practical 
>> problems are the fuser and the paper path. As a proof of concept, I 
>> took a Brother HL2140 laser printer that has a manual feed for 
>> thicker media and fed a sheet of thin (8 mil) laminate through the 
>> printer. Nothing printed.
>
>I'm not sure I understand why nothing printed here...
>
>
>> I then removed the fuser, using appropriate resistors to simulate the 
>> correct fuser temperature and thereby fool the printer controller 
>> into thinking the fuser was still there. I ran the same test, and 
>> sure enough, it printed perfectly! Of course, the toner was only held 
>> to the board by electrostatic attraction, but I then put the board 
>> into my trusty toaster oven and "fused" it.
>> 
>
>That is very interesting... Why did removing the fuser cause it to print? 
>
><SNIP>
>
>> If anyone is interested in more details, I am happy to share.
>> 
>> Mark
>>
>
>
>I would be VERY interested in pictures, and descriptions of the modifications you made.
>
>--
>James Newton
>http://techref.massmind.org/techref/pcbs.htm 
>
>
>
>
>------------------------------------
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>

Hi mark,

I don't know if you remember me, but some time ago I asked for your advices on modifing a HP 6L laser printer.

I had the same problem you said about aluminiun sheet. When I print on the board, the lines are wavy and do not correctly conect each other.
I think the surface is not perfectly flat...
Do you have any idea? I was almost giving up, but since you mentioned the method...

Roger Dupont

Hi Roger,

Yes, I do remember. I lost interest a year ago, but got interested again recently when I got a Brother HL-2140 printer. The printer has a fairly flat manual feed slot and can be (relatively) easily modified to handle rigid boards. The gearing is also advantageous for what I want to do and since the paper path is horizontal rather than vertical (the ML-2510 I was using previously was vertical), that problem is also solved. One key to doing this is to datalog all the sensors so you are not dependent on the timing built into the printer. The Hl-2140 has 3 sensors you have to simulate, but they are easy to get to. One problem is that all these connectors and such are pretty fragile - they break loose or lose electrical contact - then you get ar error led and have no idea what's wrong.

I hope to get back to it next week and will give you an update. I'm going to actually print and etch a few boards on some 9 mil board and will post the results. The board is thin and flexable enough to pass through the printer with only a small modification - the eject sensor has to be fooled.

Mark

-----Original Message-----

>From: rogerfdupont <rogerdupont@...>
>Sent: Mar 15, 2009 9:32 AM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: [Homebrew_PCBs] Re: Direct Laser PCB's (not TT)
>
>Hi mark,
>
>I don't know if you remember me, but some time ago I asked for your advices on modifing a HP 6L laser printer.
>
>I had the same problem you said about aluminiun sheet. When I print on the board, the lines are wavy and do not correctly conect each other.
>I think the surface is not perfectly flat...
>Do you have any idea? I was almost giving up, but since you mentioned the method...
>
>Roger Dupont
>
>
>
>
>------------------------------------
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>

Dave,
    So could we use the kapton laminate by itself as a flex pcb?. I was 
looking for some flex pcb.
Kim

----- Original Message ----- 

From: "drpain1313" <yahoo@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Saturday, March 14, 2009 2:42 PM
Subject: [Homebrew_PCBs] Re: Direct Laser PCB's (not TT)


> Check out www.laserpcb.com
>
> We make copper foils laminated to kapton that you can put through an 
> unmodified laser printer and directly deposit the toner onto the copper. 
> The laminate has a pressure-sensitive adhesive to allow you to stick it to 
> the supplied FR4 board before etching.
>
> Dave
>

I wonder how using Micr toner then plating copper onto it instead of
etching it off wold work?

Jack Coats wrote:
>
> I wonder how using Micr toner then plating copper onto it instead of
> etching it off wold work?
>

Remember toner is a plastic and 'black stuff' mix so fused toner is likely to expose a high proportion of plastic. This would likely preclude plating copper but on the other hand it may protect the magnetic particles in MICR toner from etchant attack.

Well, the LaserPCB has an adhesive and peel-away liner attached, so I'm not sure if it would be suitable as a flex circuit.  I suppose it would depend on the application.  I'd be happy to send you a sample so you could decide for yourself.  Just send an email request with your mailing address to: support at laserpcb.com

Dave


--- In Homebrew_PCBs@yahoogroups.com, "Kim Vellore" <kimvellore@...> wrote:

>
> Dave,
>     So could we use the kapton laminate by itself as a flex pcb?. I was 
> looking for some flex pcb.
> Kim
> 
> ----- Original Message ----- 
> From: "drpain1313" <yahoo@...>
> To: <Homebrew_PCBs@yahoogroups.com>
> Sent: Saturday, March 14, 2009 2:42 PM
> Subject: [Homebrew_PCBs] Re: Direct Laser PCB's (not TT)
> 
> 
> > Check out www.laserpcb.com
> >
> > We make copper foils laminated to kapton that you can put through an 
> > unmodified laser printer and directly deposit the toner onto the copper. 
> > The laminate has a pressure-sensitive adhesive to allow you to stick it to 
> > the supplied FR4 board before etching.
> >
> > Dave
> >
>

On Sat, 14 Mar 2009 11:25:10 -0400, you wrote:

>
>I'm not sure about the charge problem, but the way I planned to 
>handle the drum was with soft plastic on the leading edge of the 
>board and by beveling and smoothing the other edges. If the board is 
>smooth, it shouldn't damage the drum. However, I take back my 
>"absolutely" and will let you all know how things go.
>
>Mark

About 40 years ago I saw a variant on this process ( and acutally made
board with it) that transferred the toner to a "carrier" sheet and
then to the pcb using electrostatic transfer. The toner was fused to
the board using tricloroethane or trichloroethelene vapor, I don't
remember which.