Homebrew PCBs

Hi all, 

I currently use a plotter and a Lumograph pen as the etch resist for
making my pcbs. Instead of drilling I just solder the dip components
directly onto the copper side - kindda modified smt. So far this has
sufficed but I decided to move to real smt and that is testing the
limits of the pens ( .4mm with a fresh tip -  about .5mm practically )
which gives 0.016in lines ( and spacing ) with barely enough clearance
between tracks. 

I was thinking of switching over to the toner transfer method but was
curious what is the resolution that people achieve with this method -
i.e. is it suitable for smt. I've heard that the toner spreads a bit
when heated but not sure how much. 

TIA 
Deepinder

On Sun, 21 Dec 2003 20:42:19 -0500, Deepinder Singh <deepinder_s@...> 
wrote:

> Hi all,
>
> I currently use a plotter and a Lumograph pen as the etch resist for
> making my pcbs. Instead of drilling I just solder the dip components
> directly onto the copper side - kindda modified smt. So far this has
> sufficed but I decided to move to real smt and that is testing the
> limits of the pens ( .4mm with a fresh tip -  about .5mm practically )
> which gives 0.016in lines ( and spacing ) with barely enough clearance
> between tracks.
>
> I was thinking of switching over to the toner transfer method but was
> curious what is the resolution that people achieve with this method -
> i.e. is it suitable for smt. I've heard that the toner spreads a bit
> when heated but not sure how much.
>
> TIA Deepinder
>

Hi!

I'm new to toner transfer too.
Yesterday i started my first smd board with it (Two non-smd made before).
it is PERFECT.
the genuine HP toner is FAR better (and eur 5 at ebay isn't that much ;-) ) 
.

There is still some spreading of the toner, but if you keep pressure light 
while ironing it is no problem.

I also still run with darkest setting (no other way with the previous 
toner).
I think i can reduce the toner density with this toner, possibly leaving 
less material to be spread.


The board i made uses a handful of 1206 Resistors and 10mil (0,254mm 
tracks).
It is still to be etched, and i hope there isn't much under-etching with 
the narrow tracks.

Otheres here regularly do SMD work with TT, also the very narrow spaced 
ics.


I abandoned the plotter thing for just that problem. i couldn't get a 
decent track between two ic pins DIL.
and the plotting took ages.


TT is really great, don't be frightened off by some bad early results.
once you have suitable paper and toner it is really the best method i know.

Stefan

--- In Homebrew_PCBs@yahoogroups.com, "Deepinder Singh" 
> I was thinking of switching over to the toner transfer method but 
was
> curious what is the resolution that people achieve with this 
method -
> i.e. is it suitable for smt. I've heard that the toner spreads a bit
> when heated but not sure how much. 

I normally use 12mil trace-6mil clearance.  You can do this without 
even thinking twice about it and not be very careful during the whole 
process.  I've done 6-6 with good results too, but you do need to be 
quite a bit more careful.  I've had difficulty with these, not 
manufacturing the board, but burning the traces off later  (the glue 
releases the copper under too much heat).  I have noticed that the 
FR4 1oz clad seems more robust than the paper phenol in this regard --
anyone else see this?  <-- That may be more a function of board stock 
brands.  Anyway if a PCB layout needs higher densities, I've tended 
to lower the clearance value rather than the trace.  That said 8-6 
works pretty well, although you do need to be more careful and put 
some toner nearby (ground planes, other signals ) --this tends to 
help keep the paper from pulling off that one lone trace.

I haven't seen too much spreading with the laminator.  I keep my 
printer set to normal rather than dark --if you get the right amount 
of heat/pressure/paper carrier, all the toner will get tranfered.

I have been using this method for a while now with pretty good 
results.

Points to note though,  Make sure PCB is really clean, I use a green 
scouring type pad and water to scrub the board firts then wipe with 
alcohol or thinners prior to transferring.

I bought a laminator from this website 
http://www.dynaart.com/index.html and it works great, I also found a 
similar one at an office supply for 1/2 the price. 
At the same website they sell a roll of green plastic that you 
transfer on after the toner to help seal the toner...it really works.

I have had fair results with their toner transfer paper, but am not 
totally satisified although it could be my printer, not the paper.

I am using thier roll of white plastic to transfer a psuedo "silk 
screen" component legend and I absoloutely love it.

Sorry if this is starting to sound like an advertisment but I am 
overall quite pleased with my results.

They have small cans of translucent green paint that acts like a 
green soldermask, you spray it on the copper side, wait for it to dry 
and it becomes a solder mask, you can soder right through it at the 
pads and the remainder remains to protedt the copper tracks. 

I am goin to try different printers and also maybee the magazine 
paper for toner transfers as Thier TT paper gets expensive after a 
while.

Hope this helps.
David

On Tue, 23 Dec 2003 17:41:15 -0000, aussiedude36 <aussiedude@...> 
wrote:

> I have been using this method for a while now with pretty good results.
>
> Points to note though,  Make sure PCB is really clean, I use a green 
> scouring type pad and water to scrub the board firts then wipe with 
> alcohol or thinners prior to transferring.

I use 600 grit sandpaper and then wipe with with thinner or alcohol. very 
important point i agree.

>
> I bought a laminator from this website http://www.dynaart.com/index.html 
> and it works great, I also found a similar one at an office supply for 
> 1/2 the price. At the same website they sell a roll of green plastic that 
> you transfer on after the toner to help seal the toner...it really works.
>
> I have had fair results with their toner transfer paper, but am not 
> totally satisified although it could be my printer, not the paper.
>
> I am using thier roll of white plastic to transfer a psuedo "silk screen" 
> component legend and I absoloutely love it.
>
> Sorry if this is starting to sound like an advertisment but I am overall 
> quite pleased with my results.
>
> They have small cans of translucent green paint that acts like a green 
> soldermask, you spray it on the copper side, wait for it to dry and it 
> becomes a solder mask, you can soder right through it at the pads and the 
> remainder remains to protect the copper tracks.

Well, then it is no solder mask if you can solder right through it ;-) .

>
> I am goin to try different printers and also maybee the magazine paper 
> for toner transfers as Their TT paper gets expensive after a while.
>
> Hope this helps.
> David
>
>


I'm quite pleased with my results too.
With the genuine toner there are no problems at all.
No pinholes (pin is the wrong word, much bigger) like with the rebuilt 
toner.

I put not much emphasis on ironing now.
I just put it on for a few seconds to get the paper stuck and the board 
hot.
then i go over the board with the curved edge.

The resolution is more than i ever asked for.
two tracks between 1206 smd resistor pads is no problem at all.
I'm sure even 3 would work properly.
I can use 10mil with, which i hardly used with the photo process and 
routing is much easier.

I still have to experiment with toner density setting, how it affects the 
quality.
i want to get it down as much as possible to prevent spreading completely.

I didn't make component legend until now.
I don't know if it will look good with my paper (white residue).
Maybe baking would make it look better, or maybe a quick wipe with solvent.
Another option which i am sure would work is a coat of clear laquer.
The white residue only shows when dry, if wet the transfer is completely 
black.
Clear laquer would make it look like wet permanently and prevent scratching 
off too.
I will have to test this. BAD THING: My libraries are not quite up to the 
standard with component ledgend.
i never cared. Will need rework there.


I also went back to more smd now.
The "steel wire clamping device" is GREAT.
its a lot faster to make, not to mention the size.
no drilling, no bending and snipping off leads, no hold down properly on 
the other side while it gets damn hot....

Next thing:
Off to the DIY shop with me and buy some acryl glass to make a permanent 
tank.
I want a sealed unit where i can store the etchant in. i'm sick of tray 
etching.

Merry Christmas to everyone, and thanks for all the help.

Stefan