To understand the “cold” laser technology, we should first take a look at laser applications in general. Usually, the laser is used to apply high energy to a small area. If a laser beam is focused on a small spot, an extremely high energy density is generated. The wavelengths of the laser and the duration of the energy input are responsible for this. A continuous laser beam transmits the laser energy without interruption. However, the energy input to be achieved per area is relatively low.
With a pulsed beam, on the other hand, the laser energy is collected for a moment and then emitted in a short pulse. Peak powers of individual pulses can be achieved on the one hand by spatial concentration on a small area and on the other hand by an extremely short pulse duration. With the ultra-short pulse laser (UKP) this is possible and various processes can be realized: Drilling and cutting, structuring and ablation. UKP laser processing is considered “cold processing” because the heat input to the adjacent materials is very low due to the short laser pulses. Longer pulse durations usually produce melting and vaporization of material.
With “cold processing”, on the other hand, the focused material becomes directly gaseous thanks to the ultrashort laser pulses. As a result, practically no heat transfer takes place in this type of material processing. This, in turn, can be a distinct advantage for many materials, as it minimizes material stress. Distortion or even delamination is thus avoided. The “cold” laser processing can be used in the prototype production of printed circuit boards as well as for depaneling of already assembled and soldered assemblies. It is important to keep the heat stress for components and solder joints as low as possible to avoid subsequent damage. Furthermore, depaneling with UKP lasers produces technically clean cut edges that prevent the PCB from getting dirty. The evaporation of the material produces neither dust nor other impurities which could lead to subsequent short circuits. Further cleaning processes are not necessary.
Do you have questions regarding this matter?
Your contact person: Lars Führmann
Company: LPKF Laser & Electronics
