Search

Miniaturisierte und hochintegrierte Bauelemente mit besonderen Anforderungen an thermische Belastung und Bauteilbeeinflussung erfordern innovative Fugeverfahren, die den Anforderungen an kurze Taktzeiten und minimaler Fugegeometrie gerecht werden. Hinzu kommt ein steigender Materialmix, dem mit klassischen Fugetechnologien nicht mehr begegnet werden kann. Die Laser-Mikrofugetechnik bietet hier mit neuen kompakten Strahlquellen, z. B. Faserlasern und innovativen Prozessvarianten, Losungen, mit denen artungleiche Werkstoffkombinationen mit einem Minimum an Energieeintrag bei kurzen Fugezeiten im Millisekunden-Bereich erzeugt werden konnen. Schmelzefreie Prozessvarianten, wie das Laserbonden, ermoglichen hier sogar die Verbindung von Glas und Glas/Silizium-Komponenten ohne sichtbare Fugezone.

The production and machining of micro parts were in the past mainly made by technologies developed from the electronic industry, which is particularly based on silicon etching technologies for the production of, e.g., sensor elements. Due to the increasing demand for micro products in other production area such as medical-, automotive-, optical- and chemical-industry, suitable processes for machining parts from non-silicon materials has become increasingly more important. Laser technology has been qualified for microtechnology because of its high lateral resolution by minimized focusability down to a few microns, low heat input and high flexibility. Some examples for laser applications are micro welding, soldering, selective bonding of silicon and glass, micro structuring and laser assisted forming.

The joining processes in electronic device manufacturing are today still dominated by conventional joining techniques like press fitting, crimping and resistance welding. Laser beam joining techniques have been under intensive investigations and subsequently new processes for mass manufacturing and high accuracy assembling were established. With the newly developed SHADOW(R) welding technology technical aspects such as tensile strength, geometry and precision of the weld could be improved. This technology provides highest flexibility in weld geometry with a minimum welding time as well as new possibilities in using application adapted materials. Different parts and even different metals can be joined by a non-contact process. The application of a relative movement between the laser beam and the part to be joined at feed rates of up to 60 m/min produces weld seams with a length from 0.6 mm to 15.7 mm using a pulsed Nd:YAG laser with a pulse duration of up to 50 ms. Due to the low energy input, typically 1 J to 6 J, a weld width as small as 50 μm and a weld depth as small as 20 pm have been attained. This results in low distortion of the joined watch components. Within this paper this new welding process will be explained and several examples of joined components will be presented with respect to fundamentals and the sustainable implementation of the SHADOW (R) welding technique into watch manufacturing and electronic industry. For microsystem applications the laser joining technology is modified to join even silicon and glass parts without any melting based on the formation of a thermally induced oxygen bond. New fields of applications for joining different materials such as steel to brass or steel to copper for electrical interconnects will be discussed. Here the SHADOW(R) welding technique offers new possibilities for the combination of good electrical properties of copper with high mechanical stiffness of steel. The paper will give a closer look to microjoining applications especially using the SHADOW(R) welding technique. Basics of the process as well as its application on dedicated examples will be shown for small parts such as axis-wheel combinations and electrical connectors.© (2006) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Although laser beam welding is an established joining technology in the field of precision engineering, welding of copper materials is still a delicate issue. The fluctuating energy deposition resulting from the unsteady thermodynamic and optical properties of copper causes intermittent welding failures. To make welding processes more reliable, failure detection by online process monitoring is a common technology for large-scale welding applications.For micro welding, where material thicknesses far below 1 mm and focus diameters of 100 µm and less are used, the existing methods must be adapted to meet requirements such as extreme accuracy and processing times of a few milliseconds. Innovative monitoring systems based on ultra-fast cameras and optical sensors with signal processors capable of sampling rates up to 20 kHz provide new opportunities.In this paper monitoring of micro welding processes with pulsed Nd:YAG lasers and fiber lasers is examined. Different methods for process monitoring are compared, regarding what kind of information about the welding process can be gained and how failures can be identified. A special topic is the use of galvanometric scanners and how an integrated system consisting of a processing head and a monitoring system can be put into practice.Although laser beam welding is an established joining technology in the field of precision engineering, welding of copper materials is still a delicate issue. The fluctuating energy deposition resulting from the unsteady thermodynamic and optical properties of copper causes intermittent welding failures. To make welding processes more reliable, failure detection by online process monitoring is a common technology for large-scale welding applications.For micro welding, where material thicknesses far below 1 mm and focus diameters of 100 µm and less are used, the existing methods must be adapted to meet requirements such as extreme accuracy and processing times of a few milliseconds. Innovative monitoring systems based on ultra-fast cameras and optical sensors with signal processors capable of sampling rates up to 20 kHz provide new opportunities.In this paper monitoring of micro welding processes with pulsed Nd:YAG lasers and fiber lasers is examined. Different methods for process monitoring are compared, ...

The joining processes in watch manufacturing industry are today still dominated by conventional joining techniques like press fitting or crimping. Laser beam micro welding provides consistent joining and high flexibility. Different parts and even different metals can be joined in a non-contact process. The application of a relative movement between the laser beam and the part to be joined at feed rates of up to 60 m/min produces weld seams with a length from 0.6 mm to 15.7 mm using a pulsed Nd:YAG laser with a pulse duration of up to 20 ms. Due to the low energy input, typically 1 J to 6 J, a weld width as small as 50 μm and a weld depth as small as 20 μm have been attained. This results in low distortion of the joined watch components. Since the first applications of laser beam micro welding of watch components showed promising results, the process could be further enhanced using the SHADOW welding technique. Aspects of the technique such as tensile strength, geometry and precision of the weld been improved. Within the scope of this paper this new welding process will be explained and several examples of joined watch components will be presented with respect to fundamentals and the sustainable implementation of the SHADOW welding technique into watch manufacturing. New fields of applications for joining different materials such as steel to brass or steel to copper for electrical interconnects will be discussed. Here the SHADOW welding technique offers new possibilities for the combination of good electrical properties of copper with high mechanical stiffness of steel. The paper will give a closer look to micro joining applications especially using the SHADOW welding technique. Basics of the process as well as its application on dedicated examples will be shown for small parts such as axis-wheel combinations.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

SHADOW® is a welding technique where one single pulse of a Nd:YAG laser with high feed rate is used to produce weld seams of several millimetres of length. In several applications this welding technique has replaced the spot welded seams and further conventional joining techniques like press fit or soldering. The laser power necessary for a good weld seam is mainly depending on feed rate, material and process stadium. At the beginning of the weld seam, more laser power is necessary to remove the oxide skin from the material surface and melt the material. Since the material is molten, less power is necessary to maintain the weld pool. An overheating of the melt pool has to be avoided as well. Cracks and spatter formation are affected by the different physical properties and should be avoided. Overlap welds and bead-on-plate welds are produced. High strength and reproducibility as well as good appearance are the main objective. In this investigation, the pulse forming for stainless steel (X5CrNi1810), copper (CuNi3SiMg) and brass (CuZn37) is optimised.

The combination of dissimilar materials like brass and stainless steel is often needed in watch movements due to tribologic aspects. For mass production in automotive applications, a joining technique for alloyed copper with alloyed steel is needed. Laser beam micro welding offers an alternative to conventional joining techniques like press fit or soldering. Depending on the joining geometry, two different welding techniques are investigated: seam and spot welding. High strength and reproducibility are the main objective of joining dissimilar metals. Cracks and spillings are affected by the metallic continuity and should be avoided. Lap- and T-joints can be produced by the SHADOW-Welding technique. The length of the continuous welding seams are up to 15.7 mm at a feed rate of up to 60 m/min with a pulsed laser source. The weld width attained ranges from 50 to 250 μm and a weld depth from 20 to 150 μm. This low energy joining process with minimized heat input results in low distortion of the parts joined. Applying spot welding, the pulse forming capability is needed especially for highly reflective metals like copper. The welded joints have a higher strength than the basic material.

The combination of dissimilar materials like brass and stainless steel is often needed in watch movements due to tribologic aspects. For mass production in automotive applications, a joining technique for alloyed copper with alloyed steel is needed. Laser beam micro welding offers an alternative to conventional joining techniques like press fit or soldering. The laser beam micro welding of stainless steel (X5CrNi1810) to copper (CuNi3SiMg) and brass (CuZn37) with a fiber-guided pulsed Nd:YAG laser is investigated. The weld seams are produced with the SHADOW-Welding: one single pulse with high feed rate by beam movement or part movement. The joint configurations are t-joints. High strength and reproducibility as well as good appearance are the main objective of joining dissimilar metals. Cracks and spatter formation are affected by the different physical properties and should be avoided. The welding results of joint configurations as well as welded parts are presented. The length of the continuous welding seams are up to 15.7 mm at a feed rate of up to 60 m/min. The weld width attained is from 50 to 250 µm and a weld depth from 20 to 150 µm. This low energy joining process with minimized head input results in low distortion of the parts joined.The combination of dissimilar materials like brass and stainless steel is often needed in watch movements due to tribologic aspects. For mass production in automotive applications, a joining technique for alloyed copper with alloyed steel is needed. Laser beam micro welding offers an alternative to conventional joining techniques like press fit or soldering. The laser beam micro welding of stainless steel (X5CrNi1810) to copper (CuNi3SiMg) and brass (CuZn37) with a fiber-guided pulsed Nd:YAG laser is investigated. The weld seams are produced with the SHADOW-Welding: one single pulse with high feed rate by beam movement or part movement. The joint configurations are t-joints. High strength and reproducibility as well as good appearance are the main objective of joining dissimilar metals. Cracks and spatter formation are affected by the different physical properties and should be avoided. The welding results of joint configurations as well as welded parts are presented. The length of the continuous welding ...