Drilling without touching the workpiece

The laser can handle a variety of cutting tasks. These range from micrometre-precise cutting joints in paper-thin semiconductor chips to quality cuts in 30-millimetre-thick steel. In laser drilling, the laser beam generates very small to large holes in metals, plastics, paper and stone, without contact.

Where the focused laser beam strikes the workpiece, it heats the material so extremely that it melts or even vaporises. Once it has completely penetrated the workpiece, the cutting process can start: the laser beam moves along the part contour, melting the material as it goes. Usually, a stream of gas blows the melted material downwards, out of the cut. The gap is barely wider than the focused laser beam itself.

In laser drilling, a short laser pulse melts and vaporises the material with a high power density.

The resulting high pressure drives the molten material out of the hole.

Drilling

Without touching the workpiece, the laser beam produces holes – from ultra small to relatively large - in different materials. In laser drilling, a short laser pulse  with high power density feeds energy into the  workpiece extremely quickly, causing the material to melt and vaporise. The greater the pulse energy is, the more material is melted and vaporised. Vaporisation causes the material volume in the drilled hole to increase suddenly, creating high pressure. The vapor pressure expels the molten material from the hole. Over the years, several drilling processes have developed from the basic method.

Single-shot and percussion drilling

In the simplest case, a single laser pulse with comparatively high pulse energy is used to produce the hole. This method enables a large number of holes to be created in an extremely short amount of time. In percussion drilling, the hole is produced using multiple short-duration, low-energy laser pulses. This technique produces deeper, more precise holes than single-shot drilling and also enables smaller hole diameters.

Trepanning

Trepanning also uses multiple laser pulses to produce the hole. In this process, a pilot hole is first created using percussion drilling. Then the laser enlarges the pilot hole, moving over the workpiece in a series of increasingly larger circles. Most of the molten material is expelled downward through the hole.

Helical drilling

Unlike trepanning, helical drilling does not involve the creation of a pilot hole. Right from the start, the laser begins moving in circles over the material as the pulses are delivered, with a large amount of material shooting upward in the process. The laser continues to work its way through the hole in a downward spiral. The focus, meanwhile, can be adjusted so that it is always at the base of the hole. Once the laser has pierced through the material, it can complete a few more revolutions to enlarge the base of the hole and smooth out the edges. Helical drilling makes it possible to produce very large and deep high-quality holes.

Laser processing enables solar cells with higher efficiency; for instance, designs with contacts on the back side. Lasers wAir Jordan