Mask - fine structures

A line-shaped laser beam is guided over a mask with the desired welding contour. In places without coating, the laser beam reaches the joining surfaces and welds the parts.

If the laser beam hits the mask coating, it is reflected and no welding takes place in the shadow below. 

In order to weld the finest possible structures, such as micro-channels, the shadow of the mask should be defined as sharply as possible. The mask is therefore placed as close as possible to the weld seam between the parts and the clamping glass. The parts have to be adjusted well enough to the mask position.

The laser welding of plastics with masks has been patented by Leister until January 2019 (some countries January 2020).