Laser Welding

Plastics are laser-welded by passing laser light through a (laser transparent) top part onto a (laser absorbent) bottom part. The absorbed laser energy softens and melts both parts. With externally applied clamping pressure, the parts are bonded upon cooling. Typically, diode lasers having a wavelength in the (infra-red) range of 800nm-1000nm are used in this process.

Advantages of laser welding:

• Joint design need only be surface to surface. There is no need for energy directors or collapse of the weld joint.


• Weld lines can be as narrow as 0.1mm (0.004 in.)


• Good welds can be achieved, even to a hermetic seal. Tensile strength is that of the unreinforced base resin


• There is no relative motion between the parts as happens with vibration welding. There are no vibrations that could damage electronic components


• Three-dimensional geometries can be welded


• There is no part marking or bleed through


• The joint has less flash than with other methods

The four main laser welding methods:

• Spot laser welding


• Line laser welding


• Mask laser welding


• Simultaneous through welding

In spot welding, a circular spot of laser energy traverses a pre-programmed contour path. The simultaneous line method creates a laser line for welding, while the mask method blocks the laser line in a predefined pattern. Simultaneous through welding delivers laser energy to the entire surface via a fiber optic head and typically runs a three to five second cycle. (ticona.com)