Fiber laser ceramic processing for the electronics industry (FalKE)
New processing methods for the electrical industry
In the course of increasing miniaturization, the electronics industry is reaching the technical processing limits in the high-precision material processing of ceramic substrates. In the precision processing of ceramics, carbon dioxide lasers (CO2 lasers) are widely used in industry, as they have excellent absorption properties of the laser radiation in ceramics and already enable very high resolutions. However, the smallest achievable focus size is limited by the large wavelength of the CO2 laser. In order to meet the demands of the industry for ever higher precision in the micrometer range achieve, new processes such as fiber laser technology must be used.
As part of the fiber laser ceramic processing for the electrical industry (FalKE) project, fundamental investigations into the use of fiber lasers in the processing of ceramic substrates were carried out and compared with the processing results of CO2 lasers. The most commonly used high-performance ceramics, aluminum oxide (Al2O3) and aluminum nitride (AlN), were used for the tests. When laser drilling with the fiber laser, required drill diameters of less than 50 μm with good circularity and low conicity were achieved with short process times, which meant that the packing density on ceramic substrates could be significantly increased. When cutting, the fiber laser impressed with its very high cutting speeds of 300 mm/s at 500 W laser power. The comparison of experimental results with those of numerical simulations shows that even the cutting of corners and points does not result in any additional loss of strength due to the laser process.
In the subsequent Falke-Valid project, the investigation showed that the strength of ceramics cut with fiber lasers is significantly higher than that of samples cut with CO2 lasers. In addition, the strength of the samples could be increased to almost the same as the unprocessed material through digital modulation at lower speeds. Digital modulation also made it possible to produce complex inner and outer contours, which increases the degree of freedom in circuit design. Studies on the thermal shock resistance in the reflow soldering oven have shown that the ceramics cut with the fiber laser withstand typical temperature loads in the process chain without damage. With the same optical power, the productivity of the fiber laser is also six times higher than that of the CO2 laser, since the narrower kerfs mean that significantly less material has to be melted. Productivity can be further increased by using multiple heads and beam switches.
The project results clearly show that the use of the fiber laser in ceramic processing can be rated as consistently positive and has significant advantages over CO2 lasers. The unique beam quality and reliability of fiber laser technology are clear advantages that support wide industrial application.
From the basis to the qualified research result Research funding
The project “Fiber laser ceramic processing for the electrical industry (FalKE)” was funded by the Bavarian Research Foundation with around €50,000. The funding was used to carry out fundamental studies on the use of fiber lasers in ceramic processing. The consistently positive project results have given rise to follow-up studies.
The follow-up funding entitled Fiber laser ceramic processing for the electrical industry (FalKE-Valid) was funded with €300,000 in the program for validating research results and inventions (validation program) of the Bavarian State Ministry for Economic Affairs, Regional Development and Energy and supported by the Bavarian project management agency. The aim of the funding was to ensure the technological and economic connectivity, in particular the transfer to industrial research.