Laser marking on PCB silkscreen legend

Currently, we are conducting laser marking onto a white region (5 x 5 mm) PCB silkscreen legend using carbon dioxide laser equipment.

What is PCB surface finishing required to enable laser marking application? What is its relationship between silkscreen legend thickness and laser marking parameters?

We are encountered with burnt barcode that resulted in illegible marking when we verified with the scanner unit. Therefore, we would like to further understand its co-relationship to establish a better process optimization and achieving better product yields results at the laser marking operation.

Using CO2 laser to mark PCB it is better to use yellow base epoxy ink compare to white one and to obtain a contrast marking by a change of color (black marking on yellow)

Nevertheless, the use of YAG laser marking will allow you to remove the white ink without damaging the underlayer. The contrast will be given by the underlayer color and the non treated part of the white ink.

Best regards

Gunther Heraly