At glasstec 2004 in Dsseldorf, JENOPTIK Automatisierungstechnik GmbH showed its new laser cutting system called thermal laser beam separation (TLS). The system is suitable for cutting glass, silicon o…
At glasstec 2004 in Dsseldorf, JENOPTIK Automatisierungstechnik GmbH showed its new laser cutting system called thermal laser beam separation (TLS). The system is suitable for cutting glass, silicon or sapphire as well as the ceramics for which the system was originally designed. JENOPTIK developed the TLS process and the required machinery in order to cut brittle materials such as Al2O3 ceramics. Many electronic circuits use Al2O3 ceramic substrate on which printed conductors and electronic components are mounted. The separation of substrates from large ceramic plates is a particular problem, with the traditional method of laser sublimation presenting a number of drawbacks: the method typically produces chips with serrated edge profile; there is high heat input and flashing along the edges; when the plates are separated, the material tends to break along the edges releasing dust particles. As a result, the separation of the material must occur at the beginning of the process, which requires a lot of handling in all subsequent steps. In JENOPTIK“s TLS process, defined parts of the surface of the ceramic substrate are heated by a CO2 laser. This produces compressive stress in the uppermost layers of the material which, however, does not lead to destruction. Directly following the laser beam is a cooling system which causes sudden local cooling of the laser track. The resulting high temperature gradient generates tensile stress above the strength limit of the material in the outer layers. As a result, defined cracks form in the ceramic material along the lattice structure. This scribing generates a line of pre-weakening for subsequent breaking. The material does not melt and a continuous cut is obtained. Depending on the material, cutting speeds of up to 300 mm/s are possible. The new method produces cutting edges of the highest quality and strength in Al2O3 ceramics and makes finishing steps, such as grinding, unnecessary. The method does not involve ablation (i.e., removal of material), so no deposits of molten material or any kind of sediment form on the ceramic surface. In contrast to laser sublimation, hardly any particles are released in breaking the ceramic material. This makes it possible to put the breaking of the plates almost at the end of the technological process and so substantially reduce the handling required. At the 2004 SMT exhibition in Nrnberg, ceramic substrate plates processed by JENOPTIK“s new method and broken into chips with Schiller equipment were shown for the first time at the stand of Sieghard Schiller GmbH & Co. KG. The breaking systems, which had been used for conventional laser sublimated ceramic chips, did not even require modification for handling the JENOPTIK materials. Interested companies can test their materials and products extensively and assess their suitability for the TLS method at JENOPTIK“s customer applications center in Jena, eastern Germany.