Micromachining Lasers

In recent years, micromachining lasers have shown rapid growth.  This interest in micromachining has led to the development of ultrashort pulsed lasers in the picosecond and femtosecond regime with higher output powers and energies. Such sources are starting to make a big impact on a variety of micromachining applications in the semiconductor, medical and industrial markets.

Unlike CW, nanosecond, and longer pulsed lasers, that remove material via heat, picosecond and femtosecond pulses remove material via a non-thermal process called a Coulomb explosion.  At sufficient energy densities, when using a picosecond or femtosecond laser, electrons are stripped from the atoms inside the material and the positively charged atoms undergo this Coulomb explosion.

The Coulomb explosion removes, via “cold ablation”, a material layer on the order of 10-100nm per pulse. Since the cold ablation process is material unspecific, ultrafast lasers provide a universal micromachining tool for virtually any material, unlike nanosecond lasers which partially rely on wavelength-specific absorption to heat the material and ablate by evaporation.

Micromachining Lasers:

An ultrafast laser should be considered anytime the user is looking to limit the amount of HAZ (Heat Affected Zone) on a given material.  HAZ is almost always present when using CW or longer pulsed nano or microsecond laser sources.  Common features of HAZ are microcracks, slag, recast and the darkening of the material along the laser cut.  Brittle materials, such as those used in the display and solar industry, benefit from the use of these ultrafast, picosecond and femtosecond laser sources.  One example would be the solar industry that offers long-term warranties on their solar panels.  In that instance, microcracks and other HAZ related features can greatly reduce the lifetime and efficiency of the processed materials.  Overtime microcracks could propagate through the material and lead to either a complete failure of the panel or a significant reduction in the solar panel’s efficiency.

The medical industry also looks to picosecond laser and femtosecond lasers for their abilities to deliver superb quality when machining a variety of materials used for implantable devices.  The cut quality achieved with these ultra-short pulsed lasers also minimizes the amount of post processing that might otherwise be required with a CW or longer pulsed laser source