Prototyping PCB using CNC Laser Engraver - Results

Here are some initial results when using laser directly out-of-the-box without any modifications to the laser driver board or PWM logic.

The main challenge is to find an optimum speed v laser intensity setting. When the laser is full on it burns the UV coatiing and when running at high speed the PWM pattern of the laser could be seen on the board.

Test strips were created to see at which speed the PWM pattern was no longer visible but at the same time was 'exposing' the UV board; rather than burning the UV coating on the board. 

G-code for creating the test pattern

G00 Z1.0000

M03 S1000

G4 P1

G00 X10 Y0  F1000

G01 X25 Y0  F400

G00 X0 Y1   F1000 

G01 X25 Y1  F500

G00 X0 Y2   F1000

G01 X25 Y2  F600

G00 X0 Y3   F1000 

G01 X25 Y3  F700

G00 X0 Y4   F1000

G01 X25 Y4  F800

G00 X0 Y5   F1000

G01 X25 Y5  F900

G00 X0 Y6   F1000

G01 X25 Y6  F1000

M05  

The PWM pulse pattern is clearly visible at F=1000mm/s

F500 gave the cleanest line, however if looking closely at the lines t's also possilbe to see two parallel lines as though there are two parallel laser beams being projected.

In the next image you can see that power above 89 just burn way the UV etch resist layer on top of the board.