Application of pulsed fiber laser in non-metal cutting

Introduction

Although nanosecond pulse fiber lasers are commonly used for laser marking, they are also very suitable for non-metal cutting due to their low cost, compactness, reliability, and lack of frequent maintenance. By using designs such as MOPA (master oscillator power amplifier) ​​that directly modulate the seed laser, we can obtain short pulses and relatively high peak power, which turn lasers into effective tools for cutting non-metals.

As an alternative to continuous wave cutters, pulsed fiber lasers can be used in multi-pass evaporative cutting processes, where a monitoring device controls the laser to pass back and forth through the cutting line, removing only a small amount of metal each time, and without the need for nozzles and auxiliary gases. This technology provides a flexible, precise and reasonable solution. And this equipment is basically a simple laser marking system.

This cutting technology can be widely applied to a wide range of materials, from non-ferrous metals, non-ferrous metals, to ceramics, polymer materials and even carbon-containing composite materials. The cutting speed can be easily changed, for thin metal sheets, it can be less than 10mm/min, for thick materials, the cutting speed can be greater than 1mm/min. When used to cut thicker metals, special techniques such as cutting line compensation or beam swing must be used to effectively expand the incision width. These speeds may be slow compared to traditional laser cutting, but for many applications, the low cost and flexibility of nanosecond pulsed fiber lasers are very attractive.

The experimental results show that all SM/HS/HM models of SPI lasers can achieve effective cutting, but the cutting characteristics of each machine will be slightly different, which is related to the choice of material and the required output. Taking narrow kerf width as an example, SM type lasers with high quality beam and small spot are most suitable, while for thicker materials, HM type with higher peak power and larger spot size will have better results.

Silicon cutting

Silicon (technically a metal) is widely used in the electronics and solar industries, where there are many cutting applications. This material is usually diced or cut using a mechanical gemstone cutting wheel, but there are many limitations for very thin materials, and edge cuts can cause flaking. Pulsed lasers offer a flexible alternative that can be used to cut complex shapes. Using a 20W SM laser, a 5mm square can be cut in 6 seconds.

Figure 1: A square cut from 200um thick polysilicon

Ceramic cutting

The industry has a great demand for ceramic cutting. In the electronics industry, many thin substrate materials are cut by scribing, breaking or cutting. Again, the material's absorptivity is one of the limiting factors. The key materials are aluminum oxide and aluminum nitride, and their ability to be cut by 1um lasers depends on the material's specificity and surface finish. The following picture shows green aluminum nitride being quickly cut from a substrate. (Figures 2 and 3)

Figure 2: 3mm thick aluminum nitride green ceramic cut out by 6 50mm cuts using a 40W HM laser

Figure 3 0.7mm thick aluminum ceramic cut and marked using a 20W HS laser

Non-metal cutting

Pulsed lasers can also be used to cut many non-metallic materials, such as plastics, rubber, etc. The key factor that determines whether the material is suitable for laser cutting is its absorption capacity for 1um wavelength lasers. Many plastics have a high transmission coefficient in this wavelength range, so they are not suitable for cutting with lasers, but some materials can still be cut. An example of plastic cutting: plastic labels, we can mark them on them, and at the same time, as long as the parameters are slightly modified, they can be cut out of the substrate. (Figure 4)

Figure 4: Label marking and cut-out shape in heat shrink material

Other examples include cutting of protective plastic coverings such as metal commonly used on cables and wires. (Figure 5)

Figure 5: Using a 20W HS laser to cut insulating plastic from a copper substrate

Some special rubber materials can also be effectively cut to surprising thicknesses. The picture below is a 4mm thick black rubber sheet with a 1mm through hole on the side. (Figure 6)

Figure 6 4mm rubber cut using a 20WHS laser

Composite Materials

Composite materials such as carbon fiber materials can be cut to a maximum depth of 1 mm, but the processing conditions need to be adjusted according to the material itself, for example, some materials are very sensitive to carbonization. In addition, multi-layer materials can be cut. In the electronics industry, an interesting application is the use of 20W HS lasers on cross-sectional parts. The flexibility of the laser allows the cutting of different material layers. (Figure 7)

Figure 7: IC chips cut using a 20W HS laser to illustrate different layers

Summarize

Nanosecond pulse fiber lasers are very suitable for evaporation cutting. The above examples show that many types of metals can be cut by lasers, which also shows the versatility of this laser.