Homebrew PCBs

Got some 8 mil thick clad, tried sending it through an old Laserjet 4.
The panel went through OK, but the toner just didn't stick to it.  I
saw a faint image of the board on the copper, and a second print on
paper had two copies of the board on it.

Sigh.

OTOH the lj4 seems to be able to image 3.33 mil lines reasonably well,
and 5 mil lines look nice and crisp.  Maybe it will work better for TT
than the 2550N, assuming I can get it onto the board without mangling
the toner.

Probably you already damaged the drum or fuser coating.
Direct laser printing will not work easily for several reason, many
discussed here at great length before.

The only possible semi-direct laser printing method i can imagine was
not tried yet as far as i know. Basically it involves an intermediate
silicone roller picking up the image from the drum to transfer it to a
heated board passing below. I have not found a theoretical reason yet
why it would not work but that doesn't mean much.

ST

On Nov 11, 2007 7:20 PM, DJ Delorie <dj@...> wrote:
>
> Got some 8 mil thick clad, tried sending it through an old Laserjet 4.
> The panel went through OK, but the toner just didn't stick to it.  I
> saw a faint image of the board on the copper, and a second print on
> paper had two copies of the board on it.
>
> Sigh.
>
> OTOH the lj4 seems to be able to image 3.33 mil lines reasonably well,
> and 5 mil lines look nice and crisp.  Maybe it will work better for TT
> than the 2550N, assuming I can get it onto the board without mangling
> the toner.
>
>
> Be sure to visit the group home and check for new Links, Files, and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBs
> Yahoo! Groups Links
>
>
>
>
>

"Stefan Trethan" <stefan_trethan@...> writes:
> Probably you already damaged the drum or fuser coating.

Hence "old laserjet" and not "new laserjet"  ;-)

I knew the risks.  The printer barely works on its own anyway.  And
the paper prints were done after the copper, so it seems to still
work.

> Direct laser printing will not work easily for several reason, many
> discussed here at great length before.

Yup, I remember.  Just had to try it myself, with the added variable
of a much thinner clad.

The copper just does not get hot enough I would guess.



On Nov 11, 2007, at 11:20 AM, DJ Delorie wrote:


Got some 8 mil thick clad, tried sending it through an old Laserjet 4.
The panel went through OK, but the toner just didn't stick to it. I
saw a faint image of the board on the copper, and a second print on
paper had two copies of the board on it.

Sigh.

OTOH the lj4 seems to be able to image 3.33 mil lines reasonably well,
and 5 mil lines look nice and crisp. Maybe it will work better for TT
than the 2550N, assuming I can get it onto the board without mangling
the toner.





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

agscal -AGSCalabrese wrote:
> The copper just does not get hot enough I would guess.
> 
> 
> 
> On Nov 11, 2007, at 11:20 AM, DJ Delorie wrote:
> 
> 
> Got some 8 mil thick clad, tried sending it through an old Laserjet 4.
> The panel went through OK, but the toner just didn't stick to it. I
> saw a faint image of the board on the copper, and a second print on
> paper had two copies of the board on it.
> 
> Sigh.
> 
> OTOH the lj4 seems to be able to image 3.33 mil lines reasonably well,
> and 5 mil lines look nice and crisp. Maybe it will work better for TT
> than the 2550N, assuming I can get it onto the board without mangling
> the toner.
> 
The basic theoretical reason that laser drum straight to copper circuit 
board won't work is that it(the copper surface) provides a short circuit 
onto the drum surface which is an insulator that has a few thousand 
volts applied to it to hold the toner. Stefan's idea that a pickup 
roller can then be provided is a good one. Next you would then need to 
provide a HT (high tension connection to pick the toner off the pickup 
roller and then onto the copper board and then fuse it on with heat.

Here is a rather poor explanation of the laser process.

http://www.everything2.com/index.pl?node_id=111795

A better explanation is in the book "Xerox - American Samurai" By 
Jacobson, Gary, Hillkirk, John 1986 Macmillan ISBN 0025516000
which details the evolution of the photocopier from wet process's to the 
laser printer.

regards Andrew

Ok, wild thought.  Can you image toner directly onto dry photomask
then?

* Does the laser use UV at all, exposing the mask?
* Will the toner stick to DPM?
* Can DPM stand the fuser heat?

Now, if we could modify a laser printer to directly UV expose a DPM,
that would be cool too.  I suspect it would require a pretty big laser
to expose it that fast, though.

>  >
>  The basic theoretical reason that laser drum straight to copper circuit
>  board won't work is that it(the copper surface) provides a short circuit


tried this with my hpl4, works 100% onto tin foil stuck to a sheet of
a4 copier paper
(usa: aluminum cooking / turkey foil ?)

maybe it works for me as the conductive area does not go all way to the edges?

I dont know how you got copper board through, except maybe it is
thinner than my copper board, which either scratches the image drum,
or jams on a lip in the guides.

The part of the board that did get toner was looking ok, it just never
made it out the other side etc, but transfer was good,just unfused.

I may try to thin some down or try peeling the copper off to  feed through.

I had a look at making it a flat path printer but too many vogs etc for me.

On Nov 12, 2007 5:21 AM, Andrew Tweddle <sarason@...> wrote:

> The basic theoretical reason that laser drum straight to copper circuit
> board won't work is that it(the copper surface) provides a short circuit
> onto the drum surface which is an insulator that has a few thousand
> volts applied to it to hold the toner. Stefan's idea that a pickup
> roller can then be provided is a good one. Next you would then need to
> provide a HT (high tension connection to pick the toner off the pickup
> roller and then onto the copper board and then fuse it on with heat.

Maybe even the corona wire wil be enough to push some charge on the
surface of the drum. Works with paper after all.


Lez, i know you say it looks OK, but i'll still believe not all toner
is transferred and it would not hold up to etching.
You are welcome to show that i'm mistaken.

ST

On 12/11/2007, Stefan Trethan <stefan_trethan@...> wrote:
>
>
>
>
>
>
> On Nov 12, 2007 5:21 AM, Andrew Tweddle <sarason@...> wrote:
>
>  > The basic theoretical reason that laser drum straight to copper circuit
>  > board won't work is that it(the copper surface) provides a short circuit
>  > onto the drum surface which is an insulator that has a few thousand
>  > volts applied to it to hold the toner. Stefan's idea that a pickup
>  > roller can then be provided is a good one. Next you would then need to
>  > provide a HT (high tension connection to pick the toner off the pickup
>  > roller and then onto the copper board and then fuse it on with heat.
>
>  Maybe even the corona wire wil be enough to push some charge on the
>  surface of the drum. Works with paper after all.
>
>  Lez, i know you say it looks OK, but i'll still believe not all toner
>  is transferred and it would not hold up to etching.
>  You are welcome to show that i'm mistaken.

well if the copper i have went through i'd love to, but from what i'm
seeing on foil, looks at least 75%, not being an expert on this
'judging transfer by eye' i'm not going to say its 100%, but it looks
just like what i see on paper, also not i amnot printing a pcb on
these tests, just doing a printer self test, so i get the demo picture
and text, so it gets some big black areas and some fine lines

maybe it sticks better to aluminium than copper, foil stuck to card
would be a cheap way to make bendable pcb's, if i could solder to it
lol

You could stick some tape on the back of the aluminum foil and try to
etch it with disposeable etchant.
This will show if it works or not.

It would probably not be terribly hard to get hold of copper foil (i
even have some narrow strips here), but the kitchen drawer still seems
less effort.

ST

On Nov 12, 2007 9:20 AM, Lez <lez.briddon@...> wrote:

> well if the copper i have went through i'd love to, but from what i'm
> seeing on foil, looks at least 75%, not being an expert on this
> 'judging transfer by eye' i'm not going to say its 100%, but it looks
> just like what i see on paper, also not i amnot printing a pcb on
> these tests, just doing a printer self test, so i get the demo picture
> and text, so it gets some big black areas and some fine lines
>
> maybe it sticks better to aluminium than copper, foil stuck to card
> would be a cheap way to make bendable pcb's, if i could solder to it
> lol
>

--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@...> wrote:
>
> You could stick some tape on the back of the aluminum foil and try to
> etch it with disposeable etchant.
> This will show if it works or not.
> 
> It would probably not be terribly hard to get hold of copper foil (i
> even have some narrow strips here), but the kitchen drawer still seems
> less effort.
> 
> ST
> 


I tried this with some 1" wide copper tape stuck to paper. I was
hoping it might work and could be used for flexible thin boards. It
didn't transfer well enough though. Not a complete wash but only about
50% transfer, no where near usable.  I only tried it on an HP8550
printer. Maybe I'll re-try on my old Epson 1500 at home (no copper
foil is going any where near my HP1200 - LOL).

- Phil