Solutions for processing technical ceramics blog

Ceramic cutting and drilling

In this article, Louise May, Luxinar’s Senior Applications Engineer, discusses the challenges and Luxinar’s solutions for processing technical ceramics.

Introduction

Technical ceramics encompass a range of inorganic solid materials with a host of unique and desirable characteristics including compressive strength, high hardness, resistance to corrosion and the ability to function at very high temperatures without degradation. As such, technical ceramics are ideal for addressing engineering challenges in applications from aerospace to electronics. However, the intrinsic properties that make ceramics so useful pose distinct manufacturing challenges. In this article, we look at how Luxinar, a leading UK manufacturer of CO2 laser sources, have addressed these challenges with particular reference to alumina, a ceramic material used in the electronics packaging industry.

Alumina

Alumina (Al2O3), a ceramic material prepared from high-purity aluminium oxide, is widely used in the electronics packaging industry, where it serves as a substrate for components including photovoltaics and high brightness LEDs. Alumina offers high-temperature stability (1000 to 1500°C); low density (3.5g/cm3); high hardness and wear resistance (Rockwell hardness of HRA80-90); good electrical insulation (electrical resistivity 1015Ω·cm with insulation strength of 15kV/mm); corrosion resistance; and thermal conductivity (20 to 30W/MK) making it suitable for heat conduction and heat dissipation applications.

In addition to electronics applications, alumina is used in the aerospace industry, e.g., as a thermal insulating material for aircraft, in the manufacture of medical devices, as engine insulation materials for automotive, and in mechanical engineering for the production of bearings and wear-resistant parts.

Manufacturing challenges

Alumina, like other types of technical ceramics, is sintered from inorganic materials, yielding fired parts of extreme hardness that are difficult to cut, drill or scribe. Although possible, traditional machining processes using diamond tools have a number of drawbacks as they have a limited life cycle and have to be replaced on a regular basis. Additionally, as technical ceramics are brittle materials machining can induce mechanical stress, which can result in fracture. Moreover, for thin ceramic components of a few millimetres thick, tooling and additional post-machining processes add significant cost and time to the manufacturing of the finished product.

Luxinar’s solution

Based in the UK with sales offices in Europe, China and the US, Luxinar has been a leading manufacturer of CO2 laser sources for over 25 years. Its lasers are used globally for applications such as the electronics, medical devices and automotive sectors for processing a wide range of materials, including ceramics, plastics, textiles, paper, and foil.

With specific regard to alumina, Luxinar’s lasers divide alumina sheets by scribing. In this process a CO2 laser is used to drill a series of closely spaced blind holes into the ceramic, penetrating roughly one third to a half of the thickness of the material. Each hole is drilled using a single laser pulse, with hole depth controlled by the pulse duration of typically 1ms. The material is weakened along the scribed line and can be mechanically broken to separate the components.

Luxinar has also conducted research to determine the optimum parameters for the CO2 laser cutting of alumina ceramic plates. Our aim was to assess the suitability of CO2 laser cutting for alumina ceramic sheets with thicknesses of 2.0mm, 2.3mm, 3.0mm, 5.5mm, and 6.8mm (see Figure 1 and Figure 2) and to evaluate the edge quality of the material after cutting.

Two Luxinar lasers were used. The first was the SR 15i sealed CO2 laser source with a power output of up to 175W and designed with an integrated RF power supply. The device is hermetically sealed, and the simple control interface and compact mechanical design of the unit allow easy integration into industrial laser-based processing machines. The second is the OEM 65iX, a sealed CO₂ laser – a compact solution that can also be easily integrated into industrial processing production lines. This laser has a power output of up to 650W and uses a single resonator design producing laser light with a linear polarisation and a beam quality of K> 0.8. 

The main testing parameters of power, duty cycle, frequency etc are shown in table 1.

Table 1: Luxinar recommended parameters for cutting alumina ceramic sheet of thicknesses ranging from 2.0mm to 6.8mm
Alumina ceramic thicknessLaserPowerDuty cycleFrequencyAssist gasCutting speed 
2.0mmSR 15i130W40%700HzCompressed air 3.5 bar500mm/min 
2.3mmSR 15i130W40%500HzCompressed air 6 bar350mm/min 
3.0mmSR 15i75W20%500HzCompressed air 6 bar10mm/min 
5.5mmOEM 65iX120W10%250HzCompressed air 6 bar10mm/min 
6.8mmOEM 65iX200-210W15%.1.25kHz-2kHzCompressed air 6 bar10mm/min 

Results demonstrated that CO2 lasers can effectively cut alumina ceramic materials with smooth, clean edges, and minimal dross. Based on our research, we have come up with the following additional conclusions and recommendations:

  1. Utilising lower frequency, duty cycle, and processing speed helps reduce heat accumulation, lower internal material stress, effectively prevent cracks and fissures, with the goal of achieving the best cut quality.
  2. For alumina ceramic sheets with thicknesses less than 5mm, the laser focus should be on the material’s surface, whereas for those with thicknesses greater than 5mm, the focus should be slightly below the surface, approximately 1-1.5mm, to facilitate more efficient energy transfer into the material, ensuring uniform heat distribution, reducing thermal stress, and optimising cut quality, while reducing the likelihood of cracking and bottom dross.
  3. High gas pressure (6bar) effectively reduces bottom dross and carbonisation at the material’s edge. Additionally, consider using oxygen as an assist gas.
  4. For the processing of all alumina ceramics, it is recommended to install an anti-reflective device in the laser beam delivery path (ATFR) to prevent damage to optical components caused by reflected beams.

Conclusion

Luxinar has demonstrated that CO₂ laser processing of technical ceramics, whether cutting, scribing or drilling, is a precise and effective method that achieves smooth, clean edges, and minimal dross. The hardness of the material presents no problem, and the non-contact nature of the laser process means there is no tool wear, thus minimising downtime and eliminating the associated costs of tool replacement.

Its cost-effective CO₂ laser sources are designed for integration into industrial machines, where they can operate in harsh environments. If you would like more information about how Luxinar can help you improve your manufacturing processes in relation to technical ceramics, please contact us at info@luxinar.com

Luxinar head office building

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