It's just a matter of testing the energy required to burn thru the copper
compared to burning thru the FR4. If (for example) it takes 1ms to burn thru
the copper and 10us to burn thru the FR4, then you could generate the burn-path
with high frequency pulsing/moving of the laser head, with an excess of 0.1us
to make sure the copper is burn right thru and 1/100th the way into the
substrate. You could try making your own pcb from a ceramic substrate that
is more resistant to laser.
Hans Wedemeyer wrote:
> Well I posted a similar question and got the reply ... you will end up
> with a PCB jigsaw....
> How are you going to stop the laser burning the FR4 material ?
> If you can do that I'm interested....
> Hans W
>
> anode505 wrote:
>>
>>Has anyone thought of a Yag laser for PCBs?
>>I see people are actually 'milling' the unwanted copper off the
>>boards.
>>
>>
>>Yags are great for copper (On CO2 lasers, copper is a BIG no-no) and
>>the beam can be delivered via fiber optics with a Yag. Plus you
>>cna 'drill' the holes without a tool change. Get fancy and you can
>>adjust to focus for bigger/smaller kerfs (though not recomemned)
>>
>>Nice chemical free way of doing it (at least chem free before PTHs)