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 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
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.