A Guide to Laser Marking Parameters for PCBs

The project will explore how to adjust parameters such as laser power, frequency, and speed to ensure the accuracy of the laser marking while increasing the life of the equipment.The book provides practical techniques and is suitable for reference by electronic engineers and PCB production personnel.

Why do the settings of a parameter affect the accuracy and durability of a product?

We all know that the markings on a printed circuit board have to be clear and permanent, and must not damage the board.But many people just crank up the power and the result is that precision is improved, but the life of the equipment is drastically cut.In fact, the parameters of the laser are just like the temperature of a wok when stir-frying: too high and the food burns, too low and it doesn't cook.

How do you balance the three key factors?

Laser power: Don't turn it all the way up.

Too high a power level will burn through the copper coating. It is suggested that you work backwards from the material thickness.For example, with 0.8 mm FR-4 boards, it is safer to start with 40 % power.There is a little trick to this: If you are shooting on a scrap piece of wood and the edges are turning yellow, it means you are overloading the power.

Speed: Too fast and the machine won't be able to capture all the details, too slow and the machine will be unable to keep up with the movement of the subject.

If you do it too fast, the ink will be too thin, and if you do it too slow, there will be too much heat.We've done comparison tests: At a speed of 20 mm / s, the deviation of the galvanometer mirror after 5000 marks is 37 % less than at 10 mm / s.Remember to adjust the filling density at the same time.

Frequency setting: Don't underestimate this number.

High frequencies are suitable for fine text (80 kHz or more is recommended), while low frequencies are suitable for deep engraving.But the higher the frequency, the greater the strain on the laser.There was a compromise solution: to use high frequency to mark the outline, and low frequency to fill in the area. This would protect the equipment and still guarantee the effect.

This is the secret of long-term use.

This can't be taken lightly, especially after fiberglass has been processed.The worst case I've seen is when the lens got resin burned onto it, resulting in a deflection of the light path and a complete batch of PCBs being scrapped.I also recommend that the optical path be adjusted every quarter, rather than waiting for a problem to occur.

How do you solve problems?

If the edge of the marker appears to be blurred, first check whether the focus has shifted.If some of the boards are clear and some are blurry, chances are the fixture wasn't level.If you can't figure it out, it's better to take a snapshot of the parameters and send it to the manufacturer than to waste time fiddling around.