Homebrew PCBs

Hi all,

After a hiatus of many years I'm getting back into electronics (robotics 
in particular). I have made a couple of PCBs using the photo transfer 
method.
I am now venturing into SMD components and want to use the toner 
transfer method as I have discarded my UV lightbox.
So I'd like to know what methods you guys use to get very thin traces 
reliably.
What are the limits of this method?
What are the things to look out for to get reliable thin traces?

Thanks.

Bert

On Mon, 12 Mar 2012 09:48:12 +0100, you wrote:

>Hi all,
>
>After a hiatus of many years I'm getting back into electronics (robotics 
>in particular). I have made a couple of PCBs using the photo transfer 
>method.
>I am now venturing into SMD components and want to use the toner 
>transfer method as I have discarded my UV lightbox.
>So I'd like to know what methods you guys use to get very thin traces 
>reliably.

clean board, good paper, good laminator.

>What are the limits of this method?

I find that 10 mil traces are reliable, but somewhat picky to get
right.  0.5 mm spacing on a VQFP-100 flatpack is about the limit for
me, and the board still needs a bit of hand rework at times.


>What are the things to look out for to get reliable thin traces?

clean the board well.  proper temperature and pressure in the
laminator.  For large (5x7) boards I run through 8 to 10 times with
the laminator I have.  You will need to experiment.  Green foil helps
a lot, but I have had instances where it simply does not adhere at
all, ever.  Then it may ruin the board.  Odd.  Best boards have green
foil done properly.  Photoresist is actually a better process when
done with a good negative.

You will need a laser printer with 1200 DPI, dense toner, and one that
the toner softens at the proper temperature (that of the laminator).
600 DPI does not work for fine traces.

Harvey

>
>Thanks.
>
>Bert

Thanks for the info.

I'll start my tests with through hole and a regular iron.
Did anyone ever try to use a fuser unit from an old laser printer?
I have an old Laserjet II I can sacrifice for that. It should have the 
perfect temperature to transfer the toner. If I could get the speed down 
there should not be any need for multiple passes.

Bert


On 13/03/2012 15:22, Harvey White wrote:
>
> On Mon, 12 Mar 2012 09:48:12 +0100, you wrote:
>
> >Hi all,
> >
> >After a hiatus of many years I'm getting back into electronics (robotics
> >in particular). I have made a couple of PCBs using the photo transfer
> >method.
> >I am now venturing into SMD components and want to use the toner
> >transfer method as I have discarded my UV lightbox.
> >So I'd like to know what methods you guys use to get very thin traces
> >reliably.
>
> clean board, good paper, good laminator.
>
> >What are the limits of this method?
>
> I find that 10 mil traces are reliable, but somewhat picky to get
> right. 0.5 mm spacing on a VQFP-100 flatpack is about the limit for
> me, and the board still needs a bit of hand rework at times.
>
> >What are the things to look out for to get reliable thin traces?
>
> clean the board well. proper temperature and pressure in the
> laminator. For large (5x7) boards I run through 8 to 10 times with
> the laminator I have. You will need to experiment. Green foil helps
> a lot, but I have had instances where it simply does not adhere at
> all, ever. Then it may ruin the board. Odd. Best boards have green
> foil done properly. Photoresist is actually a better process when
> done with a good negative.
>
> You will need a laser printer with 1200 DPI, dense toner, and one that
> the toner softens at the proper temperature (that of the laminator).
> 600 DPI does not work for fine traces.
>
> Harvey
>
> >
> >Thanks.
> >
> >Bert
>
> 



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

On Tue, 13 Mar 2012 19:49:32 +0100, you wrote:

>Thanks for the info.
>
>I'll start my tests with through hole and a regular iron.
>Did anyone ever try to use a fuser unit from an old laser printer?
>I have an old Laserjet II I can sacrifice for that. It should have the 
>perfect temperature to transfer the toner. If I could get the speed down 
>there should not be any need for multiple passes.

I have one that's sitting there asking to be a project.  It's on the
list, that's all I can say.

I have a thermocouple controller, and I'll be using the original
heating element, providing a constant speed drive to the gearing.
Further than that, no ideas yet, although I think I will be perhaps
using aluminum, or something that is an insulator and easy to replace.

Down the road a bit.

Harvey

>
>Bert
>
>
>On 13/03/2012 15:22, Harvey White wrote:
>>
>> On Mon, 12 Mar 2012 09:48:12 +0100, you wrote:
>>
>> >Hi all,
>> >
>> >After a hiatus of many years I'm getting back into electronics (robotics
>> >in particular). I have made a couple of PCBs using the photo transfer
>> >method.
>> >I am now venturing into SMD components and want to use the toner
>> >transfer method as I have discarded my UV lightbox.
>> >So I'd like to know what methods you guys use to get very thin traces
>> >reliably.
>>
>> clean board, good paper, good laminator.
>>
>> >What are the limits of this method?
>>
>> I find that 10 mil traces are reliable, but somewhat picky to get
>> right. 0.5 mm spacing on a VQFP-100 flatpack is about the limit for
>> me, and the board still needs a bit of hand rework at times.
>>
>> >What are the things to look out for to get reliable thin traces?
>>
>> clean the board well. proper temperature and pressure in the
>> laminator. For large (5x7) boards I run through 8 to 10 times with
>> the laminator I have. You will need to experiment. Green foil helps
>> a lot, but I have had instances where it simply does not adhere at
>> all, ever. Then it may ruin the board. Odd. Best boards have green
>> foil done properly. Photoresist is actually a better process when
>> done with a good negative.
>>
>> You will need a laser printer with 1200 DPI, dense toner, and one that
>> the toner softens at the proper temperature (that of the laminator).
>> 600 DPI does not work for fine traces.
>>
>> Harvey
>>
>> >
>> >Thanks.
>> >
>> >Bert
>>
>> 
>
>
>
>[Non-text portions of this message have been removed]

--- In Homebrew_PCBs@yahoogroups.com, Bert Van Kets <mailing@...> wrote:
>
> Thanks for the info.
> 
> I'll start my tests with through hole and a regular iron.
> Did anyone ever try to use a fuser unit from an old laser printer?
> I have an old Laserjet II I can sacrifice for that. It should have the 
> perfect temperature to transfer the toner. If I could get the speed down 
> there should not be any need for multiple passes.
> 
> Bert

I'm sure you could use a fuser but you would need to do some modifications

I was thinking about it but in the end I went with the laminator because everything was already in the one unit and to get it up to correct temperature I just needed to add 1 resistor to the control circuitry.

Mine does seem to need a few passes but that doesn't worry me a great deal, considering how easy it was to get up and running.

This tip only applies to small boards, but when I make things like SMD to DIP adapters, I make multiple copies on the 3"x4" boards I use for such things.  The duplicate array of the PC board's artwork is made easily using a graphics/paint/drawing program.  This is the same method used by IC manufacturers where multiple dies are made on the same wafer and then the bad ones discarded.

Here an example of panelizing using DipTrace - for one of my small Toner
Transfer projects.

http://wa0uwh.blogspot.com/2012/03/prop-tcvcxo-pcb.html


Regards,
Eldon Brown

72 - Eldon - WA0UWH - CN88xc - http://WA0UWH.blogspot.com/

On Wed, Mar 14, 2012 at 08:13, sheldon_mp_cooper <bigbazinga@yahoo.com>wrote:

> **
>
>
> This tip only applies to small boards, but when I make things like SMD to
> DIP adapters, I make multiple copies on the 3"x4" boards I use for such
> things. The duplicate array of the PC board's artwork is made easily using
> a graphics/paint/drawing program. This is the same method used by IC
> manufacturers where multiple dies are made on the same wafer and then the
> bad ones discarded.
>
>  
>


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

Using 15 mill traces, I can get 100% (no breaks, no rework) results on the first try with magazine paper. The 8 mil traces were also completely intact, but I never tried a complete board with that size yet.  My only complaint is that I get paper fiber between some traces which must be manually removed with a needle.

I just tried HP presentation paper (from Staples).  I didn't etch yet, but the toner deposit looked much better.  The paper also lifted off by itself after about 2 minutes of soaking with not a single fiber bridge!