Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, Kim Lux <lux@d...> wrote:
> 
> I am about to make some printed circuit boards using a laser 
printer,
> the Pulsar transfer film and an H200 laminator.  Do I need to use 
toner
> reactive film or will the toner itself resist the etchant ?
> 
> Thanks 
> 
> 
> 
> 
> -- 
> Kim Lux (Mr.)  Diesel Research Inc

The toner Reactive file merely puts a harder surface in the top of 
the toner image.  It does not fill in holes in the toner nor does it 
fill any "jaggies" in trace lines or pads.

Its main purpose is to provide a harder, more impervious cover for 
the toner.  This is important if you are using Pulsar's 
recommended "direct rub" method of FeCl etching (which I use). 
The "direct rub" method relies on use of a soft sponge or brush to 
wipe the etchant across the board.  Small amounts of etchant are used 
at room temp and wiped across the board.  This speeds the etching 
process by constantly resupplying fresh FeCl to the copper surface 
while removing the copper-saturated etchant. Without the TRF 
overcoat, some of the toner will be rubbed off, exposing copper that 
you do not want removed.

If you are not using the "direct rub" method but are using an etching 
tank, I do not believe that the TRF is needed, but may enhance 
quality of the board. 

I also use the aluminum colored TRF to do the legend side of the 
board.  I have no problems getting a good component legend with the 
toner transfer and finishing it with the aluminum TRF.  I do 
encounter some minor problems when transferring a legend when a 
legend item is too close to a track or pad on a double-side board.  
The difference in the height of the copper and the board will cause a 
small skip in the toner due to this surface irregularity.  

The TRF coated legend is surprisingly scratch resistant.  I transfer 
the legend prior to drilling.  The legend side is face down on my 
drill press and after all of the positioning, sliding and drilling, 
the legend appears unaffected.

I use these techniques to make single/double sided boards from 3"x5" 
to 9"x6".  I do all thru-hole boards, so I make no representations 
regarding the efficacy of these techniques for SMD work.

Hope this helps.

Regards,

Rusty Turley