Homebrew PCBs

On Thu, 22 Jun 2006 03:45:27 +0200, Kamal Shankar  
<kbshankar2000@...m> wrote:

> Hi
> What's the method to find out the track width (in
> mils) that a laser printer can print reliably from
> it's resolution in dpi ?
> Stefan told me that a 600dpi can di upto 2mil ?
> I forgot to ask him how he did that ?


What it can print reliably might be quite different from how wide a dot  
is, theoretically.
If you make a layout you'll want to control how many dots the printer lays  
down beside each other, so you'll want to enter the calculated width.  
However this is probably not the final trace width, since it will spread  
out a little, underetch a little, etc...

You will not get a reliable trace at 1.66mil. I didn't get a reliable one  
at 3.33mil either, using toner transfer. 6.66 seems to work well however.  
This is a test i made some time ago:
<http://trethan.at.tf/pub/img1/PCB2.JPG>


I think the limit is underetching here, not the printer. If i remember  
right the 3.33mil line looked fine before the etch.

ST